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Sample records for additional latent heat

  1. Understanding Latent Heat of Vaporization.

    ERIC Educational Resources Information Center

    Linz, Ed

    1995-01-01

    Presents a simple exercise for students to do in the kitchen at home to determine the latent heat of vaporization of water using typical household materials. Designed to stress understanding by sacrificing precision for simplicity. (JRH)

  2. Retrieved Latent Heating from TRMM

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, Eric A.; Houze Jr, Robert

    2008-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of precipitation formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the tropics with the associated latent heating (LH) accounting for three-fourths of the total heat energy available to the Earth's atmosphere. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. In the last decade, it has been established that standard products of LH from satellite measurements, particularly TRMM measurements, would be a valuable resource for scientific research and applications. Such products would enable new insights and investigations concerning the complexities of convection system life cycles, the diabatic heating controls and feedbacks related to meso-synoptic circulations and their forecasting, the relationship of tropical patterns of LH to the global circulation and climate, and strategies for improving cloud parameterizations in environmental prediction models. The status of retrieved TRMM LH products, TRMM LH inter-comparison and validation project, current TRMM LH applications and critic issues/action items (based on previous five TRMM LH workshops) is presented in this article.

  3. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E.; Olson, W.

    2005-01-01

    Rainfall production is a fundamental process within the Earth;s hydrological cycle because it represents both a principal forcing term in surface water budgets, and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations with the Tropics - as well as modify the energetic efficiencies of mid-latitude weather systems. This paper highlights the retrieval of observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional amount of rainfall over the global Tropics and sub-tropics - information which can be used to estimate the spacetime structure of latent heating across the Earth's low latitudes. A set of algorithm methodologies has and continues to be developed to estimate latent heating based on rain rate profile retrievals obtained from TRMM measurements. These algorithms are briefly described followed by a discussion of the foremost latent heating products that can be generate from them. The investigation then provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  4. Open cycle latent heat engine

    SciTech Connect

    Czaja, J.

    1989-12-19

    This patent describes an open cycle latent heat engine. It comprises: an elevator passageway having an entrance at a lower level and an exit at a higher level having a substantially higher elevation than the lower level; means for inputting warm water vapor into the lower level of the elevator passageway to produce a wet adiabatic expansion of moist air rising in the passageway; a condensate remover in the region of the exit from the elevator, the condensate remover being arranged for removing water condensed from the vapor at the higher elevation of the exit: compressor passageway descending from the region of the elevator passageway exit to the region of the elevator passageway entrance; an ejector arranged at a lower region of the compressor passageway and means for extracting energy from the air circulation flow established by the elevator passageway, the compressor passageway, and the ejector.

  5. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, E. A.; Adler, R.; Haddad, Z.; Hou, A.; Iguchi, T.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.

    2004-01-01

    Rainfall production is the fundamental variable within the Earth's hydrological cycle because it is both the principal forcing term in surface water budgets and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations within the tropics - as well as modifying the energetic efficiencies of midlatitude weather systems. This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission (TRMM) satellite observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional account of rainfall over the global tropics and sub-tropics, information which can be used to estimate the space-time structure of latent heating across the Earth's low latitudes. The paper examines how the observed TRMM distribution of rainfall has advanced an understanding of the global water and energy cycle and its consequent relationship to the atmospheric general circulation and climate via latent heat release. A set of algorithm methodologies that are being used to estimate latent heating based on rain rate retrievals from the TRMM observations are described. The characteristics of these algorithms and the latent heating products that can be generated from them are also described, along with validation analyses of the heating products themselves. Finally, the investigation provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  6. Latent Heating Structures Derived from TRMM

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E. A.; Adler, R.; Hou, A.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.; Olson, W.; Satoh, S.

    2004-01-01

    Rainfall is the fundamental variable within the Earth's hydrological cycle because it is both the main forcing term leading to variations in continental and oceanic surface water budgets. The vertical distribution of latent heat release, which is accompanied with rain, modulates large-scale meridional and zonal circulations within the tropics as well as modifying the energetic efficiency of mid-latitude weather systems. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water.This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission 0. The TRMM observatory, whose development was a joint US-Japan space endeavor, was launched in November 1997. TRMM measurements provide an accurate account of rainfall over the global tropics, information which can be .used to estimate the four-dimensional structure of latent heating across the entire tropical and sub-tropical regions. Various algorithm methodologies for estimating latent heating based on rain rate measurements from TRMM observations are described. The strengths and weaknesses of these algorithms, as well as the latent heating products generated by these algorithms, are also discussed along with validation analyses of the products. The investigation paper provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, and concludes with remarks designed to stimulate further research on latent heating retrieval

  7. Dish-mounted latent heat buffer storage

    NASA Technical Reports Server (NTRS)

    Manvi, R.

    1981-01-01

    Dish-mounted latent heat storage subsystems for Rankine, Brayton, and Stirling engines operating at 427 C, 816 C, and 816 C respectively are discussed. Storage requirements definition, conceptual design, media stability and compatibility tests, and thermal performance analyses are considered.

  8. The effective latent heat of aqueous nanofluids

    NASA Astrophysics Data System (ADS)

    Lee, Soochan; Taylor, Robert A.; Dai, Lenore; Prasher, Ravi; Phelan, Patrick E.

    2015-06-01

    Nanoparticle suspensions, popularly termed ‘nanofluids’, have been extensively investigated for their thermal and radiative properties (Eastman et al 1996 Mater. Res. Soc. Proc. 457; Keblinski et al 2005 Mater. Today 8 36-44 Barber et al 2011 Nanoscale Res. Lett. 6 1-13 Thomas and Sobhan 2011 Nanoscale Res. Lett. 6 1-21 Taylor et al 2011 Nanoscale Res. Lett. 6 1-11 Fang et al 2013 Nano Lett. 13 1736-42 Otanicar et al 2010 J. Renew. Sustainable Energy 2 03310201-13 Prasher et al 2006 ASME J. Heat Transfer 128 588-95 Shin and Banerjee 2011 ASME J. Heat Transfer 133 1-4 Taylor and Phelan 2009 Int. J. Heat Mass Transfer 52 5339-48 Ameen et al 2010 Int. J. Thermophys. 31 1131-44 Lee et al 2014 Appl. Phys. Lett. 104 1-4). Such work has generated great controversy, although it is (arguably) generally accepted today that the presence of nanoparticles rarely leads to useful enhancements in either thermal conductivity or convective heat transfer. On the other hand, there are still examples of unanticipated enhancements to some properties, such as the specific heat of molten salt-based nanofluids reported by Shin and Banerjee (2011 ASME J. Heat Transfer 133 1-4) and the critical heat flux mentioned by Taylor and Phelan (2009 Int. J. Heat Mass Transfer 52 5339-48). Another largely overlooked example is the reported effect of nanoparticles on the effective latent heat of vaporization (hfg) of aqueous nanofluids, as reported by Ameen et al (2010 Int. J. Thermophys. 31 1131-44). Through molecular dynamics (MD) modeling supplemented with limited experimental data they found that hfg increases with increasing nanoparticle concentration, for Pt nanoparticles (MD) and Al2O3 nanoparticles (experiments). Here, we extend those exploratory experiments in an effort to determine if hfg of aqueous nanofluids can be manipulated, i.e., increased or decreased by the addition of graphite or silver nanoparticles. Our results to date indicate that, yes, hfg can be substantially impacted, by

  9. Latent Heat in Soil Heat Flux Measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  10. Revisiting Black's experiments on the latent heats of water

    NASA Astrophysics Data System (ADS)

    Güémez, J.; Fiolhais, C.; Fiolhais, M.

    2002-01-01

    Historical experiments may help students to better understand some physical phenomena. We reproduced Black's original experiments on the latent heats of water (fusion and vaporization). To obtain both latent heats with reasonable accuracy we needed concepts, which were not used by Black, such as the water equivalent of a calorimeter and Newton's law of cooling. The melting experiment is adequate to obtain an accurate value for the latent heat with a small uncertainty, but the same is not true for the vaporization experiment.

  11. Low temperature latent heat thermal energy storage - Heat storage materials

    NASA Astrophysics Data System (ADS)

    Abhat, A.

    1983-01-01

    Heat-of-fusion storage materials for low temperature latent heat storage in the temperature range 0-120 C are reviewed. Organic and inorganic heat storage materials classified as paraffins, fatty acids, inorganic salt hydrates and eutectic compounds are considered. The melting and freezing behavior of the various substances is investigated using the techniques of Thermal Analysis and Differential Scanning Calorimetry. The importance of thermal cycling tests for establishing the long-term stability of the storage materials is discussed. Finally, some data pertaining to the corrosion compatibility of heat-of-fusion substances with conventional materials of construction is presented.

  12. Determination of the Latent Heats and Triple Point of Perfluorocyclobutane

    ERIC Educational Resources Information Center

    Briggs, A. G.; Strachan, A. N.

    1977-01-01

    Proposes the use of Perfluorocyclobutane in physical chemistry courses to conduct experiments on latent heat, triple point temperatures and pressures, boiling points, and entropy of vaporization. (SL)

  13. Solar thermoelectricity via advanced latent heat storage

    NASA Astrophysics Data System (ADS)

    Olsen, M. L.; Rea, J.; Glatzmaier, G. C.; Hardin, C.; Oshman, C.; Vaughn, J.; Roark, T.; Raade, J. W.; Bradshaw, R. W.; Sharp, J.; Avery, A. D.; Bobela, D.; Bonner, R.; Weigand, R.; Campo, D.; Parilla, P. A.; Siegel, N. P.; Toberer, E. S.; Ginley, D. S.

    2016-05-01

    We report on a new modular, dispatchable, and cost-effective solar electricity-generating technology. Solar ThermoElectricity via Advanced Latent heat Storage (STEALS) integrates several state-of-the-art technologies to provide electricity on demand. In the envisioned STEALS system, concentrated sunlight is converted to heat at a solar absorber. The heat is then delivered to either a thermoelectric (TE) module for direct electricity generation, or to charge a phase change material for thermal energy storage, enabling subsequent generation during off-sun hours, or both for simultaneous electricity production and energy storage. The key to making STEALS a dispatchable technology lies in the development of a "thermal valve," which controls when heat is allowed to flow through the TE module, thus controlling when electricity is generated. The current project addresses each of the three major subcomponents, (i) the TE module, (ii) the thermal energy storage system, and (iii) the thermal valve. The project also includes system-level and techno- economic modeling of the envisioned integrated system and will culminate in the demonstration of a laboratory-scale STEALS prototype capable of generating 3kWe.

  14. Retrieval of Latent Heating from TRMM Measurements

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E. A.; Adler, R. F.; Hou, A. Y.; Meneghini, R.; Simpson, J.; Haddad, Z. S.; Iguchi, T.; Satoh, S.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C. D.; Lang, S.; Nakamura, K.; Nakazawa, T.; Okamoto, K.; Shige, S.; Olson, W. S.; Takayabu, Y.; Tripoli, G. J.; Yang, S.

    2006-01-01

    Precipitation, in driving the global hydrological cycle, strongly influences the behavior of the Earth's weather and climate systems and is central to their variability. Two-thirds of the global rainfall occurs over the Tropics, which leads to its profound effect on the general circulation of the atmosphere. This is because its energetic equivalent, latent heating (LH), is the tropical convective heat engine's primary fuel source as originally emphasized by Riehl and Malkus (1958). At low latitudes, LH stemming from extended bands of rainfall modulates large-scale zonal and meridional circulations and their consequent mass overturnings (e.g., Hartmann et al. 1984; Hack and Schubert 1990). Also, LH is the principal energy source in the creation, growth, vertical structure, and propagation of long-lived tropical waves (e.g., Puri 1987; Lau and Chan 1988). Moreover, the distinct vertical distribution properties of convective and stratiform LH profiles help influence climatic outcomes via their tight control on large-scale circulations (Lau and Peng 1987; Nakazawa 1988; Sui and Lau 1988; Emanuel et al. 1994; Yanai et al. 2000; Sumi and Nakazawa 2002; Schumacher et al. 2004). The purpose of this paper is to describe how LH profiles are being derived from satellite precipitation rate retrievals, focusing on those being made with Tropical Rainfall Measuring Mission (TRMM) satellite measurements.

  15. Shallow and Deep Latent Heating Modes Over Tropical Oceans Observed with TRMM PR Spectral Latent Heating Data

    NASA Technical Reports Server (NTRS)

    Takayabu, Yukari N.; Shige, Shoichi; Tao, Wei-Kuo; Hirota, Nagio

    2010-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. Three-dimensional distributions of latent heating estimated from Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR)utilizing the Spectral Latent Heating (SLH) algorithm are analyzed. Mass-weighted and vertically integrated latent heating averaged over the tropical oceans is estimated as approx.72.6 J/s (approx.2.51 mm/day), and that over tropical land is approx.73.7 J/s (approx.2.55 mm/day), for 30degN-30degS. It is shown that non-drizzle precipitation over tropical and subtropical oceans consists of two dominant modes of rainfall systems, deep systems and congestus. A rough estimate of shallow mode contribution against the total heating is about 46.7 % for the average tropical oceans, which is substantially larger than 23.7 % over tropical land. While cumulus congestus heating linearly correlates with the SST, deep mode is dynamically bounded by large-scale subsidence. It is notable that substantial amount of rain, as large as 2.38 mm day-1 in average, is brought from congestus clouds under the large-scale subsiding circulation. It is also notable that even in the region with SST warmer than 28 oC, large-scale subsidence effectively suppresses the deep convection, remaining the heating by congestus clouds. Our results support that the entrainment of mid-to-lower-tropospheric dry air, which accompanies the large

  16. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  17. A solar air collector with integrated latent heat thermal storage

    NASA Astrophysics Data System (ADS)

    Charvat, Pavel; Ostry, Milan; Mauder, Tomas; Klimes, Lubomir

    2012-04-01

    Simulations of the behaviour of a solar air collector with integrated latent heat thermal storage were performed. The model of the collector was created with the use of coupling between TRNSYS 17 and MATLAB. Latent heat storage (Phase Change Material - PCM) was integrated with the solar absorber. The model of the latent heat storage absorber was created in MATLAB and the model of the solar air collector itself was created in TRNSYS with the use of TYPE 56. The model of the latent heat storage absorber allows specification of the PCM properties as well as other parameters. The simulated air collector was the front and back pass collector with the absorber in the middle of the air cavity. Two variants were considered for comparison; the light-weight absorber made of sheet metal and the heat-storage absorber with the PCM. Simulations were performed for the climatic conditions of the Czech Republic (using TMY weather data).

  18. Survey of sensible and latent heat thermal energy storage projects

    NASA Astrophysics Data System (ADS)

    Baylin, F.; Merino, M.

    1981-05-01

    Ongoing and completed research projects on sensible and latent heat thermal enegy storage for low, intermediate, and high temperature applications are reviewed. Projects in the United States and abroad are included. Several research efforts are in the index although the project descriptions are absent. Project lists are organized into four sections: short term sensible heat storage; seasonal sensible heat storage; latent heat storage; and models, economic analysis, and support studies. The organization of the Department of Energy programs managing many of these projects is also outlined. Projects are presented in a standard format that includes laboratory; funding level and period; status; project description; technical and economic parameters; and applications.

  19. Latent Heating Retrievals Using the TRMM Precipitation Radar: A Multi-Seasonal Study

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, S.; Meneghini, R.; Halverson, J.; Johnson, R.; Simpson, J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. Present largescale weather and climate models can simulate latent heat release only crudely, thus reducing their confidence in predictions on both global and regional scales. This paper represents the first attempt to use NASA Tropical Rainfall Measuring Mission (TRMM) rainfall information to estimate the four-dimensional structure of global monthly latent heating profiles over the global tropics from December 1997 to October 2000. The Goddard Convective-Stratiform. Heating (CSH) algorithm and TRMM precipitation radar data are used for this study. We will examine and compare the latent heating structures between 1997-1998 (winter) ENSO and 1998-2000 (non-ENSO). We will also examine over the tropics. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental; Indian oceans vs west Pacific; Africa vs S. America) will be also examined and compared. In addition, we will examine the relationship between latent heating (max heating level) and SST. The period of interest also coincides with several TRMM field campaigns that recently occurred over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and in the central Pacific in 1999 (KWAJEX). Sounding diagnosed Q1 budgets from these experiments could provide a means of validating the retrieved profiles of latent heating from the CSH algorithm.

  20. The meridional scale of baroclinic waves with latent heat release

    NASA Technical Reports Server (NTRS)

    Tang, Chung-Muh

    1988-01-01

    The control on the meridional scale of a class of the baroclinic waves exercised by latent heat release is analyzed. A meridional-scale equation is derived, in which the dry model and the moist model without the meridional variation of the baroclinic waves are revealed. It is shown that, in the dry model the stability analysis cannot determine the meridional scale of the baroclinic waves. When latent heat release is included, the meridional variation of the waves either vanishes or is finite. When the waves have the meridional variation with latent heat release, the growth rate increases as the heating increases for a given Froude number, and there are two modes - the first mode has a small ascending region and a large descending region, while the second mode has a small descending region and a large ascending region.

  1. [Latent heat of vaporization in amaranth (Amaranthus hybridus)].

    PubMed

    Alvarado, J D; Toaza, E; Coloma, G

    1990-09-01

    The vapor pressure at four temperatures and 10 moisture contents in a range between 26.8 and 3.6 g/100 dry matter, were determined by the manometric method in two samples of milled amaranth seeds, known as "ataco" or "sangoracha". For each humidity, the relationship between vapor pressure of the flour and vapor pressure of water at different temperatures is satisfactorily described by power equations, which are herein presented. The slope was used in the determination of latent heat of vaporization, according to Othmer's law. An exponential equation describing the relationship between the rate of latent heat and moisture content on a dry basis are established and discussed. This allows calculation with sufficient exactitude of the latent heat of vaporization values in amaranth, particularly at low moisture contents. The data are useful in calculations for drying or extrusion operations, largely applied in cereals. PMID:2134140

  2. Scale effects in the latent heat of melting in nanopores.

    PubMed

    Shin, J-H; Parlange, J-Y; Deinert, M R

    2013-07-28

    The curvature of a liquid vapor interface has long been known to change the equilibrium vapor pressure. It has also been shown that a capillary structure will affect the temperature at which both freezing and vaporization of a substance will occur. However, describing interfacial effects on the latent heat of a phase change has proven more difficult. Here, we present a classical thermodynamic model for how the latent heat of melting changes as the size of the particles undergoing the transition decreases. The scale dependence for the surface tension is taken into consideration using a Tolman length correction. The resulting model is tested by fitting to published experimental data for the latent heat of melting for benzene, heptane, naphthalene, and water contained in nano-porous glass. In all cases the model fits the data with a R(2) ≥ 0.94. PMID:23901997

  3. Design and simulation of latent heat storage units. Final report

    SciTech Connect

    Shamsundar, N.; Stein, E.; Rooz, E.; Bascaran, E.; Lee, T.C.

    1992-04-01

    This report presents the results of two years of research and development on passive latent heat storage systems. Analytical models have been developed and extended, and a computer code for simulating the performance of a latent heat storage has been developed. The code is intended to be merged into a larger solar energy system simulation code and used for making realistic system studies. Simulation studies using a code which has a flexible and accurate routine for handling the storage subsystem should lead to the development of better systems than those in which storage is added on after the rest of the system has already been selected and optimized.

  4. Design and simulation of latent heat storage units

    SciTech Connect

    Shamsundar, N.; Stein, E.; Rooz, E.; Bascaran, E.; Lee, T.C. )

    1992-04-01

    This report presents the results of two years of research and development on passive latent heat storage systems. Analytical models have been developed and extended, and a computer code for simulating the performance of a latent heat storage has been developed. The code is intended to be merged into a larger solar energy system simulation code and used for making realistic system studies. Simulation studies using a code which has a flexible and accurate routine for handling the storage subsystem should lead to the development of better systems than those in which storage is added on after the rest of the system has already been selected and optimized.

  5. Studies of Phase Change Materials and a Latent Heat Storage Unit Used for a Natural Circulation Cooling/Latent Heat Storage System

    NASA Astrophysics Data System (ADS)

    Sakitani, Katsumi; Honda, Hiroshi

    Experimental and theoretical studies were made of the heat transfer characteristics of a latent heat storage unit used for a natural circulation cooling /latent heat storage system. Heating and cooling curves of the latent heat storage unit undergoing solid-liquid phase change of a PCM (lauric acid) was obtained by using anatural circulation loop of R22 which consisted of an electrically heated evaporater, a water cooled condenser and the latent heat storage unit. The latent heat storage unit showed a heat transfer performance which was high enough for practical use. An approximate theoretical analysis was conducted to investigate transient behavior of the latent heat storage unit. Predictions of the refrigerant and outer surface temperatures during the melting process were in fair agreement with the experimental data, whereas that of the refrigerant temperature during the solidification process was considerably lower than the measurement.

  6. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. Additional information is included in the original extended abstract.

  7. Filled Carbon Nanotubes: Superior Latent Heat Storage Enhancers

    SciTech Connect

    2009-04-01

    This factsheet describes a rstudy whose technical objective is to demonstrate the feasibility of filled carbon nanotubes (CNT) as latent heat storage enhancers, with potential applications as next generation thermal management fluids in diverse applications in industries ranging from high-demand microelectronic cooling, manufacturing, power generation, transportation, to solar energy storage.

  8. Indirectly heated fluidized bed biomass gasification using a latent heat ballast

    SciTech Connect

    Pletka, R.; Brown, R.; Smeenk, J.

    1998-12-31

    The objective of this study is to improve the heating value of gas produced during gasification of biomass fuels using an indirectly heated gasifier based on latent heat ballasting. The latent heat ballast consists of lithium fluoride salt encased in tubes suspended in the reactor. The lithium fluoride has a melting point that is near the desired gasification temperature. With the ballast a single reactor operating in a cyclic mode stores energy during a combustion phase and releases it during a pyrolysis phase. Tests were carried out in a fluidized bed reactor to evaluate the concept. The time to cool the reactor during the pyrolysis phase from 1,172 K (1,650 F) to 922 K (1,200 F) increased 102% by use of the ballast system. This extended pyrolysis time allowed 33% more biomass to be gasified during a cycle. Additionally, the total fuel fraction pyrolyzed to produce useful gas increased from 74--80%. Higher heating values of 14.2 to 16.6 MJ/Nm{sup 3} (382--445 Btu/scf) on a dry basis were obtained from the ballasted gasifier.

  9. Metal-halide mixtures for latent heat energy storage

    NASA Technical Reports Server (NTRS)

    Chen, K.; Manvi, R.

    1981-01-01

    Some candidates for alkali metal and alkali halide mixtures suitable for thermal energy storage at temperatures 600 C are identified. A solar thermal system application which offer advantages such as precipitation of salt crystals away from heat transfer surfaces, increased thermal conductivity of phase change materials, corrosion inhibition, and a constant monotectic temperature, independent of mixture concentrations. By using the lighters, metal rich phase as a heat transfer medium and the denser, salt rich phase as a phase change material for latent heat storage, undesirable solidification on the heat transfer surface may be prevented, is presented.

  10. Heat Transfer and Latent Heat Storage in Inorganic Molten Salts for Concentrating Solar Power Plants

    SciTech Connect

    Mathur, Anoop

    2013-08-14

    A key technological issue facing the success of future Concentrating Solar Thermal Power (CSP) plants is creating an economical Thermal Energy Storage (TES) system. Current TES systems use either sensible heat in fluids such as oil, or molten salts, or use thermal stratification in a dual-media consisting of a solid and a heat-transfer fluid. However, utilizing the heat of fusion in inorganic molten salt mixtures in addition to sensible heat , as in a Phase change material (PCM)-based TES, can significantly increase the energy density of storage requiring less salt and smaller containers. A major issue that is preventing the commercial use of PCM-based TES is that it is difficult to discharge the latent heat stored in the PCM melt. This is because when heat is extracted, the melt solidifies onto the heat exchanger surface decreasing the heat transfer. Even a few millimeters of thickness of solid material on heat transfer surface results in a large drop in heat transfer due to the low thermal conductivity of solid PCM. Thus, to maintain the desired heat rate, the heat exchange area must be large which increases cost. This project demonstrated that the heat transfer coefficient can be increase ten-fold by using forced convection by pumping a hyper-eutectic salt mixture over specially coated heat exchanger tubes. However,only 15% of the latent heat is used against a goal of 40% resulting in a projected cost savings of only 17% against a goal of 30%. Based on the failure mode effect analysis and experience with pumping salt at near freezing point significant care must be used during operation which can increase the operating costs. Therefore, we conclude the savings are marginal to justify using this concept for PCM-TES over a two-tank TES. The report documents the specialty coatings, the composition and morphology of hypereutectic salt mixtures and the results from the experiment conducted with the active heat exchanger along with the lessons learnt during

  11. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs. S. America ) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model. Review of other latent heating algorithms will be discussed in the workshop.

  12. Studies of Phase Change Materials and a Latent Heat Storage Unit Used for a Natural Circulation Cooling/Latent Heat Storage System

    NASA Astrophysics Data System (ADS)

    Sakitani, Katsumi; Honda, Hiroshi

    Experiments were performed to investigate feasibility of using organic materials as a PCM for a latent heat storage unit of a natural circulation cooling/latent heat storage system. This system was designed to cool a shelter accommodating telecommunication equipment located in subtropical deserts or similar regions without using a power source. Taking into account practical considerations and the results of various experiments regarding the thermodynamic properties, thermal degradation, and corrosiveness to metals, lauric acid and iron was selected for the PCM and the latent heat storage unit material, respectively. Cyclic heating and cooling of the latent heat storage unit undergoing solid-liquid phase change was repeated for more than 430 days. The results showed that the heating-cooling curve was almost unchanged between the early stage and the 1,870th cycle. It was concluded that the latent heat storage unit could be used safely for more than ten years as a component of the cooling system.

  13. Cold Heat Storage Characteristics of O/W-type Latent Heat Emulsion Including Continuum Phase of Water Treated with a Freezing Point Depression

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Morita, Shin-Ichi

    This paper deals with flow and cold heat storage characteristics of the oil (tetradecane, C14H30, freezing point 278.9 K, Latent heat 229 kJ/kg)/water emulsion as a latent heat storage material having a low melting point. The test emulsion includes a water-urea solution as a continuum phase. The freezing point depression of the continuum phase permits enhancement of the heat transfer rate of the emulison, due to the large temperature difference between the latent heat storage material and water-urea solution. The velocity of emulsion flow and the inlet temperature of coolant in a coiled double tube heat exchanger are chosen as the experimental parameters. The pressure drop, the heat transfer coefficient of the emulsion in the coiled tube are measured in the temperture region over solid and liquid phase of the latent heat storage material. The finishing time of the cold heat storage is defined experimentally in the range of sensible and latent heat storage. It is clarified that the flow behavior of the emulsion as a non-Newtonian fluid has an important role in cold heat storage. The useful nondimentional correlation equations for the additional pressure loss coefficient, the heat transfer coefficient and the finishing time of the cold heat storage are derived in terms of Dean number and heat capacity ratio.

  14. Latent heat sink in soil heat flux measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  15. Intercomparison of Latent Heat Fluxes Over Global Oceans

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.; Chou, Ming-Dah

    2003-01-01

    Turbulent fluxes of momentum, moisture, and heat at the air-sea interface are essential for climate studies. Version 2 Goddard Satellite-based Surface Turbulent Fluxes (GSSTF2) has been derived from the Special Sensor Microwave/Imager (SSM/I) radiance measurements. This dataset, covering the period July 1987-December 2000 over global oceans, has a spatial resolution of 1 deg x 1 deg lat-long and a temporal resolution of 1 day. Turbulent fluxes are derived from the SSM/I surface winds and surface air humidity, as well as the 2-m air and sea surface temperatures (SST) of the NCEP/NCAR reanalysis, using a bulk aerodynamic algorithm based on the surface layer similarity theory. The GSSTF2 bulk flux model, and retrieved daily wind stress, latent heat flux, wind speed, and surface air humidity validate well with ship observations of ten field experiments over the tropical and midlatitude oceans during 1991-99. The global distributions of 1988-2000 annual- and seasonal-mean turbulent fluxes show reasonable patterns related to the atmospheric general circulation and seasonal variations. Latent heat fluxes and related input parameters over global oceans during 1992-93 have been compared among GSSTF1 (version 1), GSSTF2, HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP/NCAR reanalysis, and one based on COADS (Comprehensive Ocean-Atmosphere Data Set). Our analyses suggest that the GSSTF2 latent heat flux, surface air humidity, surface wind, and SST are quite realistic compared to the other four flux datasets examined. However, significant differences are found among these five flux datasets. The GSSTF2, available at http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/hydrology/hd_gsstf2.O.html, is useful for climate studies.

  16. MJO Signals in Latent Heating: Results from TRMM Retrievals

    SciTech Connect

    Zhang, Chidong; Ling, Jian; Hagos, Samson M.; Tao, Wei-Kuo; Lang, Steve; Takayabu, Yukari N.; Shige, Shoichi; Katsumata, Masaki; Olson, William S.; L'Ecuyer, Tristan S.

    2010-11-01

    Four Tropical Rainfall Measuring Mission (TRMM) datasets of latent heating were diagnosed for signals in the Madden-Julian Oscillation (MJO). In all four datasets, vertical structures of latent heating are dominated by two components, one deep with its peak above the melting level and one shallow with its peak below. Profiles of the two components are nearly ubiquitous in longitude, allowing a separation of the vertical and zonal/temporal variations when the latitudinal dependence is not considered. All four datasets exhibit robust MJO spectral signals in the deep component as eastward propagating spectral peaks centered at period of 50 days and zonal wavenumber 1, well distinguished from lower- and higher-frequency power and much stronger than the corresponding westward power. The shallow component shows similar but slightly less robust MJO spectral peaks. MJO signals were further extracted from a combination of band-pass (30 – 90 day) filtered deep and shallow components. Largest amplitudes of both deep and shallow components of the MJO are confined to the Indian and western Pacific Oceans. There is a local minimum in the deep components over the Maritime Continent. The shallow components of the MJO differ substantially among the four TRMM datasets in their detailed zonal distributions in the eastern hemisphere. In composites of the heating evolution through the life cycle of the MJO, the shallow components lead the deep ones in some datasets and at certain longitudes. In many respects, the four TRMM datasets agree well in their deep components, but not in their shallow components and the phase relations between the deep and shallow components. These results indicate that caution must be exercised in applications of these latent heating data.

  17. A study on cooling characteristics of clathrate compound as low temperature latent heat storage material

    NASA Astrophysics Data System (ADS)

    Kim, Chang Oh; Kim, Jin Heung; Chung, Nak Kyu

    2007-07-01

    Materials that can store low temperature latent heat are organic/inorganic chemicals, eutectic salt system and clathrate compound. Clathrate compound is the material that host compound in hydrogen bond forms cage and guest compound is included into it and combined. Crystallization of hydrate is generated at higher temperature than that of ice from pure water. And physical properties according to temperature are stable and congruent melting phenomenon is occurred without phase separation and it has relatively high latent heat. But clathrate compound still has supercooling problem occurred in the course of phase change and supercooling should be minimized because it affects efficiency of equipment very much. Therefore, various studies on additives to restrain this or heat storage methods are needed. Supercooling is the phenomenon that low temperature thermal storage material is not crystallized and existed as liquid for some time under phase change temperature. Because phase change into solid is delayed and it is existed as liquid due to this, heat transfer from low temperature thermal storage material is lowered. Therefore it is not crystallized at original phase change temperature and crystallized after cooled as much as supercooling degree and operation time of refrigerator is increased. In this study was investigated the cooling characteristics of the clathrate compound as a low temperature latent heat storage material. And additive was added to clathrate compound and its supercooling restrain effect was studied experimentally.

  18. Heat Shock Factor 1 Mediates Latent HIV Reactivation

    PubMed Central

    Pan, Xiao-Yan; Zhao, Wei; Zeng, Xiao-Yun; Lin, Jian; Li, Min-Min; Shen, Xin-Tian; Liu, Shu-Wen

    2016-01-01

    HSF1, a conserved heat shock factor, has emerged as a key regulator of mammalian transcription in response to cellular metabolic status and stress. To our knowledge, it is not known whether HSF1 regulates viral transcription, particularly HIV-1 and its latent form. Here we reveal that HSF1 extensively participates in HIV transcription and is critical for HIV latent reactivation. Mode of action studies demonstrated that HSF1 binds to the HIV 5′-LTR to reactivate viral transcription and recruits a family of closely related multi-subunit complexes, including p300 and p-TEFb. And HSF1 recruits p300 for self-acetylation is also a committed step. The knockout of HSF1 impaired HIV transcription, whereas the conditional over-expression of HSF1 improved that. These findings demonstrate that HSF1 positively regulates the transcription of latent HIV, suggesting that it might be an important target for different therapeutic strategies aimed at a cure for HIV/AIDS. PMID:27189267

  19. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM rainfall products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2001. Rainfall, latent heating and radar reflectivity structures between El Nino (DE 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs. west Pacific, Africa vs. S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in strtaiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  20. Vertical Profiles of Latent Heat Release over the Global Tropics Using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in straitform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMXX), Brazil in 1999 (TRMM- LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  1. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  2. TRMM observations of latent heat distribution over the Indian summer monsoon region and associated dynamics

    NASA Astrophysics Data System (ADS)

    Subrahmanyam, Kandula V.; Kishore Kumar, Karanam

    2016-05-01

    The latent heat released/absorbed in the Earth's atmosphere due to phase change of water molecule plays a vital role in various atmospheric processes. It is now well established that the latent heat released in the clouds is the secondary source of energy for driving the atmosphere, the Sun being the primary. In this context, studies on latent heat released in the atmosphere become important to understand the some of the physical processes taking place in the atmosphere. One of the important implications of latent heat release is its role in driving the circulations on various temporal and spatial scales. Realizing the importance of latent heat released in the clouds, a comprehensive study is carried out to understand its role in driving the mesoscale circulation. As Indian summer monsoon (ISM) serves as natural laboratory for studying the clouds and their microphysics, an attempt is made to explore the latent heat distribution over this region using 13 years of Tropical Rainfall Measuring Mission (TRMM) observations. The observed profiles of latent heating over ISM region showed large spatial and temporal variability in the magnitude thus reflecting the presence of organization of convection on mesoscale. The latent profiles in convective and stratiform regions are segregated to study the differences in their interaction with large-scale environment. Various re-analysis dataset were used to examine the role of latent heating distribution on the mesoscale circulation. The significance of the present study lies in establishing the vertical distribution of latent heating and their impact on the background circulation.

  3. Wallboard with Latent Heat Storage for Passive Solar Applications

    SciTech Connect

    Kedl, R.J.

    2001-05-31

    Conventional wallboard impregnated with octadecane paraffin [melting point-23 C (73.5 F)] is being developed as a building material with latent heat storage for passive solar and other applications. Impregnation was accomplished simply by soaking the wallboard in molten wax. Concentrations of wax in the combined product as high as 35% by weight can be achieved. Scale-up of the soaking process, from small laboratory samples to full-sized 4- by 8-ft sheets, has been successfully accomplished. The required construction properties of wallboard are maintained after impregnation, that is, it can be painted and spackled. Long-term, high-temperature exposure tests and thermal cycling tests showed no tendency of the paraffin to migrate within the wallboard, and there was no deterioration of thermal energy storage capacity. In support of this concept, a computer model was developed to handle thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions and also by comparison with temperatures measured in wallboard during an experimentally generated thermal transient. Agreement between the model and known solution was excellent. Agreement between the model and thermal transient was good, only after the model was modified to allow the PCM to melt over a temperature range, rather than at a specific melting point. When the melting characteristics of the PCM (melting point, melting range, and heat of fusion), as determined from a differential scanning calorimeter plot, were used in the model, agreement between the model and transient data was very good. The confirmed computer model may now be used in conjunction with a building heating and cooling code to evaluate design parameters and operational characteristics of latent heat storage wallboard for passive solar applications.

  4. Relating Convective and Stratiform Rain to Latent Heating

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, Stephen; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

    2010-01-01

    The relationship among surface rainfall, its intensity, and its associated stratiform amount is established by examining observed precipitation data from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). The results show that for moderate-high stratiform fractions, rain probabilities are strongly skewed toward light rain intensities. For convective-type rain, the peak probability of occurrence shifts to higher intensities but is still significantly skewed toward weaker rain rates. The main differences between the distributions for oceanic and continental rain are for heavily convective rain. The peak occurrence, as well as the tail of the distribution containing the extreme events, is shifted to higher intensities for continental rain. For rainy areas sampled at 0.58 horizontal resolution, the occurrence of conditional rain rates over 100 mm/day is significantly higher over land. Distributions of rain intensity versus stratiform fraction for simulated precipitation data obtained from cloud-resolving model (CRM) simulations are quite similar to those from the satellite, providing a basis for mapping simulated cloud quantities to the satellite observations. An improved convective-stratiform heating (CSH) algorithm is developed based on two sources of information: gridded rainfall quantities (i.e., the conditional intensity and the stratiform fraction) observed from the TRMM PR and synthetic cloud process data (i.e., latent heating, eddy heat flux convergence, and radiative heating/cooling) obtained from CRM simulations of convective cloud systems. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. Major differences between the new and old algorithms include a significant increase in the amount of low- and midlevel heating, a downward emphasis in the level of maximum cloud heating by about 1 km, and a larger variance between land and ocean in

  5. Study on Latent Heat of Fusion of Ice in Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Kumano, Hiroyuki; Asaoka, Tatsunori; Saito, Akio; Okawa, Seiji

    In this study, latent heat of fusion of ice in aqueous solutions was measured to understand latent heat of fusion of ice slurries. Propylene glycol, ethylene glycol, ethanol, NaCl and NaNO3 solutions were examined as the aqueous solutions. In the measurement, pure ice was put into the solution, and the temperature variation of the solution due to the melting of the ice was measured. Then, the effective latent heat of fusion was calculated from energy balance equation. When ice melts in solution, the concentration of the solution varies due to the melting of the ice, and dilution heat must be considered. Therefore, the latent heat of fusion of ice in aqueous solutions was predicted by considering the effects of dilution and freezing-point depression. The latent heat of fusion was also measured by differential scanning calorimetry(DSC) to compare the results obtained from the experiments with that obtained by DSC. As the result, it was found that the effective latent heat of fusion of ice decreased with the increase of the concentration of solution, and the effective latent heat of fusion was calculated from latent heat of fusion of pure ice and the effects of freezing-point depression and the dilution heat.

  6. Performance of direct contact latent heat storage unit

    SciTech Connect

    Farid, M.; Yacoub, K. )

    1989-01-01

    The performance of direct contact latent heat storage unit has been investigated in a glass column having an inside diameter and length of 0.2 m and 1.5 m respectively. Kerosene, as a heat transfer fluid, was bubbled through the continuous phase which was a solution of one of the hydrated salts: Na{sub 2}CO{sub 3}{center dot}10H{sub 2}O, Na{sub 2}SO{sub 4}{center dot}10H{sub 2}O, and Na{sub 2}HPO{sub 4}{center dot}12H{sub 2}O. The continuous phase temperature at different heights together with the kerosene inlet and outlet temperatures were measured with time during both heat charge and discharge. Theoretical prediction of the performance of the unit has been achieved employing the model for drop with internal circulation which was used to evaluate the transfer efficiency. Thermal efficiency of the nit was found to increase with the larger column. A sharp decrease in the magnitude of the heat transfer coefficient was observed soon after crystallization started. The coefficient increased significantly at higher kerosene flow rates due to the information of smaller bubbles.

  7. Convective and Stratiform Precipitation Processes and their Relationship to Latent Heating

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, Steve; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

    2009-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. An improved convective -stratiform heating (CSH) algorithm has been developed to obtain the 3D structure of cloud heating over the Tropics based on two sources of information: 1) rainfall information, namely its amount and the fraction due to light rain intensity, observed directly from the Precipitation Radar (PR) on board the TRMM satellite and 2) synthetic cloud physics information obtained from cloud-resolving model (CRM) simulations of cloud systems. The cloud simulations provide details on cloud processes, specifically latent heating, eddy heat flux convergence and radiative heating/cooling, that. are not directly observable by satellite. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. One of the major differences between new and old algorithms is that the level of maximum cloud heating occurs 1 to 1.5 km lower in the atmosphere in the new algorithm. This can effect the structure of the implied air currents associated with the general circulation of the atmosphere in the Tropics. The new CSH algorithm will be used provide retrieved heating data to other heating algorithms to supplement their performance.

  8. Satellite-observed latent heat release in a tropical cyclone

    NASA Technical Reports Server (NTRS)

    Adler, R. F.; Rodgers, E. B.

    1977-01-01

    The latent heat release (LHR) and the distribution of rainfall rate of a tropical cyclone as it grows from a tropical disturbance to a typhoon were determined from Nimbus 5 Electrically Scanning Microwave Radiometer data. The LHR (calculated over a circular area of 4 deg latitude radius) increased during the development and intensification of the storm from a magnitude of 2.7 x 10 to the fourteenth W (in the disturbance stage) to 8.8 x 10 to the fourteenth W (typhoon stage). The latter value corresponds to a mean rainfall rate of 2.0 mm/h. The more intense the cyclone and the greater the LHR, the greater the percentage contribution of the larger rainfall rates to the LHR. As a cyclone intensifies, the higher rainfall rates tend to concentrate toward the center of the circulation.

  9. Fluid Latent Heat Storage Material Using Ethanol Water Mixture

    NASA Astrophysics Data System (ADS)

    Ohkubo, Hidetoshi; Yasunari, Yuki

    Ethanol water mixture has a liquidus line ( or crystallizing line) and a solidus line (or melting line) that are separated, and therefore it can have both liquid and solid phases existing together. With advances in low temperature technology in recent days, ethanol water mixture is attaching more and more attention as an environment-friendly coolant or as a thermal storage material. In the present study, we observed the crystallization process in the mixture and carried out experiments to evaluate fluidity of the mixture, with the objective of utilizing an ethanol water mixture as a coolant or a thermal energy storage material. Crystal formation and growing process within a minute droplet of a binary mixture was modeled. As a result, we found a novel method to produce a fluid latent heat storage material continuously and an apparent coefficient of viscosity show that rotational speed and solid phase fraction have a strong effect on the fluidity of the mixture.

  10. Conventional wallboard with latent heat storage for passive solar applications

    SciTech Connect

    Kedl, R.J.

    1990-01-01

    Conventional wallboard impregnated with octadecane paraffin (Melting Point -- 73.5{degree}F) is being developed as a building material with latent heat storage for passive solar applications. Impregnation was accomplished simply by soaking the wallboard in molten paraffin. Concentrations of paraffin in the combined product as high as 35{percent} by weight were achieved. In support of this concept, a computer model was developed to describe thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions where the PCM melts at a specific melting point. However, agreement between the model and an experimentally produced thermal transient involving impregnated wallboard was only good after the model was modified to allow the paraffin to melt over a temperature range. This was accomplished by replacing the heat of fusion with a triangular heat capacity relationship that mimics the triangular melt curve found through differential scanning calorimetry. When this change was made, agreement between the model and the experimental transient was very good. 4 refs., 8 figs.

  11. The surface latent heat flux anomalies related to major earthquake

    NASA Astrophysics Data System (ADS)

    Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

    2011-12-01

    SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

  12. Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Olson, W. S.; Meneghini, R.; Yang, S.; Simpson, J.; Kummerow, C.; Smith, E.

    2000-01-01

    This paper represents the first attempt to use TRMM rainfall information to estimate the four dimensional latent heating structure over the global tropics for February 1998. The mean latent heating profiles over six oceanic regions (TOGA COARE IFA, Central Pacific, S. Pacific Convergence Zone, East Pacific, Indian Ocean and Atlantic Ocean) and three continental regions (S. America, Central Africa and Australia) are estimated and studied. The heating profiles obtained from the results of diagnostic budget studies over a broad range of geographic locations are used to provide comparisons and indirect validation for the heating algorithm estimated heating profiles. Three different latent heating algorithms, the Goddard Convective-Stratiform (CSH) heating, the Goddard Profiling (GPROF) heating, and the Hydrometeor heating (HH) are used and their results are intercompared. The horizontal distribution or patterns of latent heat release from the three different heating retrieval methods are quite similar. They all can identify the areas of major convective activity (i.e., a well defined ITCZ in the Pacific, a distinct SPCZ) in the global tropics. The magnitude of their estimated latent heating release is also not in bad agreement with each other and with those determined from diagnostic budget studies. However, the major difference among these three heating retrieval algorithms is the altitude of the maximum heating level. The CSH algorithm estimated heating profiles only show one maximum heating level, and the level varies between convective activity from various geographic locations. These features are in good agreement with diagnostic budget studies. By contrast, two maximum heating levels were found using the GPROF heating and HH algorithms. The latent heating profiles estimated from all three methods can not show cooling between active convective events. We also examined the impact of different TMI (Multi-channel Passive Microwave Sensor) and PR (Precipitation Radar

  13. Sensitivity of Latent Heating Profiles to Environmental Conditions: Implications for TRMM and Climate Research

    NASA Technical Reports Server (NTRS)

    Shepherd, J. Marshall; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The Tropical Rainfall Measuring Mission (TRMM) as a part of NASA's Earth System Enterprise is the first mission dedicated to measuring tropical rainfall through microwave and visible sensors, and includes the first spaceborne rain radar. Tropical rainfall comprises two-thirds of global rainfall. It is also the primary distributor of heat through the atmosphere's circulation. It is this circulation that defines Earth's weather and climate. Understanding rainfall and its variability is crucial to understanding and predicting global climate change. Weather and climate models need an accurate assessment of the latent heating released as tropical rainfall occurs. Currently, cloud model-based algorithms are used to derive latent heating based on rainfall structure. Ultimately, these algorithms can be applied to actual data from TRMM. This study investigates key underlying assumptions used in developing the latent heating algorithms. For example, the standard algorithm is highly dependent on a system's rainfall amount and structure. It also depends on an a priori database of model-derived latent heating profiles based on the aforementioned rainfall characteristics. Unanswered questions remain concerning the sensitivity of latent heating profiles to environmental conditions (both thermodynamic and kinematic), regionality, and seasonality. This study investigates and quantifies such sensitivities and seeks to determine the optimal latent heating profile database based on the results. Ultimately, the study seeks to produce an optimized latent heating algorithm based not only on rainfall structure but also hydrometeor profiles.

  14. Heat capacity and latent heat measurements of CoMnSi using a microcalorimeter.

    PubMed

    Miyoshi, Y; Morrison, K; Moore, J D; Caplin, A D; Cohen, L F

    2008-07-01

    A new method of utilizing a commercial silicon nitride membrane calorimeter to measure the latent heat at a first order phase transition is presented. The method is a direct measurement of the thermoelectric voltage jump induced by the latent heat, in a thermally isolated system ideally suited for single crystal and small microgram samples. We show that when combined with the ac calorimetry technique previously developed, the resultant thermal measurement capabilities are extremely powerful. We demonstrate the applicability of the combined method with measurements on a 100 microm size fragment of CoMnSi exhibiting a sizable magnetocaloric effect near room temperature, and obtain good agreement with previously reported values on bulk samples. PMID:18681727

  15. Wallboard with latent heat storage for passive solar applications

    SciTech Connect

    Kedl, R.J.

    1991-05-01

    Conventional wallboard impregnated with octadecane paraffin is being developed as a building material with latent heat storage for passive solar and other applications. Impregnation was accomplished simply by soaking the wallboard in molten wax. Concentrations of wax in the combined product as high as 35% by weight can be achieved. Scale-up of the soaking process, from small laboratory samples to full-sized 4- by 8-ft sheets, has been successfully accomplished. The required construction properties of wallboard are maintained after impregnation, that is, it can be painted and spackled. Long-term, high-temperature exposure tests and thermal cycling tests showed no tendency of the paraffin to migrate within the wallboard, and there was no deterioration of thermal energy storage capacity. In support of this concept, a computer model was developed to handle thermal transport and storage by a phase change material (PCM) dispersed in a porous media. The computer model was confirmed by comparison with known analytical solutions and also by comparison with temperatures measured in wallboard during an experimentally generated thermal transient. Agreement between the model and known solution was excellent. Agreement between the model and thermal transient was good, only after the model was modified to allow the PCM to melt over a temperature range, rather than at a specific melting point. When the melting characteristics of the PCM, as determined from a differential scanning calorimeter plot, were used in the model, agreement between the model and transient data was very good. 11 refs., 25 figs., 2 tabs.

  16. Development of composite latent/sensible heat storage media

    SciTech Connect

    Petri, R.; Ong, E.T.; Kardas, A. )

    1990-12-01

    Results of an on-going program to develop a composite latent-sensible thermal energy storage medium, trade marked CompPhase, are presented. The target application area was periodic kiln energy recovery. The concept is that of a composite salt/ceramic material processed such that the medium maintains its shape and mechanical integrity through the salt melting temperature. As such, the media can be fabricated into a variety of shapes suitable for packed beds, fluidized beds, or direct contact heat exchangers. The properties of ten carbonate salt or eutectic mixtures of carbonate salts were reviewed to select the most appropriate candidates for development. Three salts and two ceramic materials were evaluated in laboratory tests to select the final material, a composite of sodium-barium eutectic/magnesium oxide, for development. Two methods of processing the constituent powders for fabrication into storage pellets were developed, and one method was applied to pellet fabrication by commercial processing equipment. Two different preliminary cost estimates bracketed the expected cost of commercially fabricating storage pellets. Also, two modifications to the material processing method were suggested to reduce costs. Thermal cycling was conducted on laboratory produced experimental pellets and on prototype pellets fabricated by commercial processes. Detailed laboratory tests to determine composite mechanical and thermal properties were conducted. It is concluded that further laboratory, field, and economic studies are required before the concept of composite storage media can be considered fully developed for commercialization. 5 refs., 73 figs., 20 tabs.

  17. Preparation of fine powdered composite for latent heat storage

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Pomaleski, Marina; Trník, Anton; Pavlíková, Milena; Pavlík, Zbyšek

    2016-07-01

    Application of latent heat storage building envelope systems using phase-change materials represents an attractive method of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. This study deals with a preparation of a new type of powdered phase change composite material for thermal energy storage. The idea of a composite is based upon the impregnation of a natural silicate material by a reasonably priced commercially produced pure phase change material and forming the homogenous composite powdered structure. For the preparation of the composite, vacuum impregnation method is used. The particle size distribution accessed by the laser diffraction apparatus proves that incorporation of the organic phase change material into the structure of inorganic siliceous pozzolana does not lead to the clustering of the particles. The compatibility of the prepared composite is characterized by the Fourier transformation infrared analysis (FTIR). Performed DSC analysis shows potential of the developed composite for thermal energy storage that can be easily incorporated into the cement-based matrix of building materials. Based on the obtained results, application of the developed phase change composite can be considered with a great promise.

  18. Latent heat of magnetization for MnFeSi0 . 33P0 . 66

    NASA Astrophysics Data System (ADS)

    Roy, Prasenjit; de Groot, Robert A.; Theoretical Chemistry Team

    2015-03-01

    Magnetic refrigeration is a very promising environmental-friendly method to encounter the energy shortage of the world by implementing the magnetocaloric effect. MnFeSiP series of materials are distinguishable magnetocaloric meterial for the use of non-toxic, inexpensive elements as well as high efficiency. There are several ways to measure the efficiency of the MCE, viz.- measuring the adiabatic temperature change or measuring the entropy change at the transition. MnFeSiP materials show a first order magneto-elastic phase transition at the Curie temperature (TC). This simultaneous occourance of the magnetic and elastic transition in this material account for a higher ΔTad (or high entropy change), which is linearly proportional to the Latent heat (L) of magnetization. Experimentally L can be determined with techniques such as Differential Scanning Calorimetry. In our study we use VASP in addition to the Phonopy package, to determine the finite temperature properties of the system. Quasi Harmonic Approximation was applied successfully to determine the Gibbs free energy of MnFeSi0.33 P0.66. Hence we show a phase transition around 425 K. From the temperature derivative of G , the specific heat was obtained and finally the latent heat was obtained. Foundation for fundamental research on matter.

  19. Latent heat exchange in the boreal and arctic biomes.

    PubMed

    Kasurinen, Ville; Alfredsen, Knut; Kolari, Pasi; Mammarella, Ivan; Alekseychik, Pavel; Rinne, Janne; Vesala, Timo; Bernier, Pierre; Boike, Julia; Langer, Moritz; Belelli Marchesini, Luca; van Huissteden, Ko; Dolman, Han; Sachs, Torsten; Ohta, Takeshi; Varlagin, Andrej; Rocha, Adrian; Arain, Altaf; Oechel, Walter; Lund, Magnus; Grelle, Achim; Lindroth, Anders; Black, Andy; Aurela, Mika; Laurila, Tuomas; Lohila, Annalea; Berninger, Frank

    2014-11-01

    In this study latent heat flux (λE) measurements made at 65 boreal and arctic eddy-covariance (EC) sites were analyses by using the Penman-Monteith equation. Sites were stratified into nine different ecosystem types: harvested and burnt forest areas, pine forests, spruce or fir forests, Douglas-fir forests, broadleaf deciduous forests, larch forests, wetlands, tundra and natural grasslands. The Penman-Monteith equation was calibrated with variable surface resistances against half-hourly eddy-covariance data and clear differences between ecosystem types were observed. Based on the modeled behavior of surface and aerodynamic resistances, surface resistance tightly control λE in most mature forests, while it had less importance in ecosystems having shorter vegetation like young or recently harvested forests, grasslands, wetlands and tundra. The parameters of the Penman-Monteith equation were clearly different for winter and summer conditions, indicating that phenological effects on surface resistance are important. We also compared the simulated λE of different ecosystem types under meteorological conditions at one site. Values of λE varied between 15% and 38% of the net radiation in the simulations with mean ecosystem parameters. In general, the simulations suggest that λE is higher from forested ecosystems than from grasslands, wetlands or tundra-type ecosystems. Forests showed usually a tighter stomatal control of λE as indicated by a pronounced sensitivity of surface resistance to atmospheric vapor pressure deficit. Nevertheless, the surface resistance of forests was lower than for open vegetation types including wetlands. Tundra and wetlands had higher surface resistances, which were less sensitive to vapor pressure deficits. The results indicate that the variation in surface resistance within and between different vegetation types might play a significant role in energy exchange between terrestrial ecosystems and atmosphere. These results suggest the need

  20. Evaluation and Application of Satellite-Based Latent Heating Profile Estimation Methods

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Grecu, Mircea; Yang, Song; Tao, Wei-Kuo

    2004-01-01

    In recent years, methods for estimating atmospheric latent heating vertical structure from both passive and active microwave remote sensing have matured to the point where quantitative evaluation of these methods is the next logical step. Two approaches for heating algorithm evaluation are proposed: First, application of heating algorithms to synthetic data, based upon cloud-resolving model simulations, can be used to test the internal consistency of heating estimates in the absence of systematic errors in physical assumptions. Second, comparisons of satellite-retrieved vertical heating structures to independent ground-based estimates, such as rawinsonde-derived analyses of heating, provide an additional test. The two approaches are complementary, since systematic errors in heating indicated by the second approach may be confirmed by the first. A passive microwave and combined passive/active microwave heating retrieval algorithm are evaluated using the described approaches. In general, the passive microwave algorithm heating profile estimates are subject to biases due to the limited vertical heating structure information contained in the passive microwave observations. These biases may be partly overcome by including more environment-specific a priori information into the algorithm s database of candidate solution profiles. The combined passive/active microwave algorithm utilizes the much higher-resolution vertical structure information provided by spaceborne radar data to produce less biased estimates; however, the global spatio-temporal sampling by spaceborne radar is limited. In the present study, the passive/active microwave algorithm is used to construct a more physically-consistent and environment-specific set of candidate solution profiles for the passive microwave algorithm and to help evaluate errors in the passive algorithm s heating estimates. Although satellite estimates of latent heating are based upon instantaneous, footprint- scale data, suppression

  1. A model for the latent heat of melting in free standing metal nanoparticles

    SciTech Connect

    Shin, Jeong-Heon; Deinert, Mark R.

    2014-04-28

    Nanoparticles of many metals are known to exhibit scale dependent latent heats of melting. Analytical models for this phenomenon have so far failed to completely capture the observed phenomena. Here we present a thermodynamic analysis for the melting of metal nanoparticles in terms of their internal energy and a scale dependent surface tension proposed by Tolman. The resulting model predicts the scale dependence of the latent heat of melting and is confirmed using published data for tin and aluminum.

  2. Measurement of Latent Heat of Melting of Thermal Storage Materials for Dynamic Type Ice Thermal Storage

    NASA Astrophysics Data System (ADS)

    Sawada, Hisashi; Okada, Masashi; Nakagawa, Shinji

    In order to measure the latent heat of melting of ice slurries with various solute concentrations, an adiabatic calorimeter was constructed. Ice slurries were made from each aqueous solution of ethanol, ethylene glycol and silane coupling agent. The latent heat of melting of ice made from tap water was measured with the present calorimeter and the uncertainty of the result was one percent. Ice slurries were made both by mixing ice particles made from water with each aqueous solution and by freezing each aqueous solution with stirring in a vessel. The latent heat of melting of these ice slurries was measured with various concentrations of solution. The latent heat of melting decreased as the solute concentration or the freezing point depression increased. The latent heat of ice slurries made from ethanol or ethylene glycol aqueous solution agreed with that of ice made from pure water known already. The latent heat of melting of ice slurries made from silane coupling agent aqueous solution got smaller than that of ice made from pure water as the freezing point depression increased.

  3. Environmental Forcing of Super Typhoon Paka's (1997) Latent Heat Structure

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Olson, William; Halverson, Jeff; Simpson, Joanne; Pierce, Harold

    1999-01-01

    The distribution and intensity of total (i.e., combined stratified and convective processes) rainrate/latent heat release (LHR) were derived for tropical cyclone Paka during the period 9-21 December, 1997 from the F-10, F-11, F-13, and F-14 Defense Meteorological Satellite Special Sensor Microwave/Imager and the Tropical Rain Measurement Mission Microwave Imager observations. These observations were frequent enough to capture three episodes of inner core convective bursts that preceded periods of rapid intensification and a convective rainband (CRB) cycle. During these periods of convective bursts, satellite sensors revealed that the rainrates/LHR: 1) increased within the inner eye wall region; 2) were mainly convectively generated (nearly a 65% contribution), 3) propagated inwards; 4) extended upwards within the middle and upper-troposphere, and 5) became electrically charged. These factors may have caused the eye wall region to become more buoyant within the middle and upper-troposphere, creating greater cyclonic angular momentum, and, thereby, warming the center and intensifying the system. Radiosonde measurements from Kwajalein Atoll and Guam, sea surface temperature observations, and the European Center for Medium Range Forecast analyses were used to examine the necessary and sufficient condition for initiating and maintaining these inner core convective bursts. For example, the necessary conditions such as the atmospheric thermodynamics (i.e., cold tropopause temperatures, moist troposphere, and warm SSTs [greater than 26 deg]) suggested that the atmosphere was ideal for Paka's maximum potential intensity (MPI) to approach super-typhoon strength. Further, Paka encountered weak vertical wind shear (less than 15 m/s ) before interacting with the westerlies on 21 December. The sufficient conditions, on the other hand, appeared to have some influence on Paka's convective burst, but the horizontal moisture flux convergence values in the outer core were weaker than

  4. Evolution of Latent Heating Profiles in Two MC3E MCSs

    NASA Astrophysics Data System (ADS)

    Saleeby, S. M.; Marinescu, P. J.; van den Heever, S. C.; Kreidenweis, S. M.

    2015-12-01

    Mesoscale convective systems (MCSs) can be separated into convective and stratiform regions, with each region being associated with characteristic microphysical processes. As such, latent heating that occurs within convective and stratiform regions also has distinct vertical profiles. The latent heating in MCSs plays an important role in the (1) redistribution of energy and moisture from near the Earth's surface to the upper atmosphere, (2) generation of buoyancy forcing for updrafts and downdrafts, and (3) creation of pressure waves that can propagate away from the MCS and alter the surrounding environment. During the various stages of an MCS's lifecycle, the latent heating vertical profiles within the convective and stratiform regions can change. To provide details on these dynamic latent heating profiles, results from two MCS simulations will be presented. Three-dimensional, cloud-resolving model simulations are performed using the Regional Atmospheric Modeling System (RAMS) to represent two MCS events from the Midlatitude Continental Convective Cloud Experiment (MC3E), which occurred in Spring 2011 in the Southern Great Plains of the United States. Comparisons of simulations against observations demonstrate that both simulations capture many features of the observed MC3E MCS events very well, such as precipitation, cold pool strength, and MCS cloud structure. Precipitation regions within these simulations are broken up into convective and stratiform regions using a convective-stratiform separation algorithm. Region-specific latent heating vertical profiles are assessed both as averages over the simulation and as a function of time. In the middle and upper troposphere, convective region warming from latent heating decreases in magnitude throughout the MCS lifecycle, while stratiform warming increases in magnitude in a more confined region between 4 and 8 kilometers above the surface. In the lower troposphere, cooling from latent heating is dominant in both

  5. Latent Heat and Sensible Heat Fluxes Simulation in Maize Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Safa, B.

    2015-12-01

    Latent Heat (LE) and Sensible Heat (H) flux are two major components of the energy balance at the earth's surface which play important roles in the water cycle and global warming. There are various methods for their estimation or measurement. Eddy covariance is a direct and accurate technique for their measurement. Some limitations lead to prevention of the extensive use of the eddy covariance technique. Therefore, simulation approaches can be utilized for their estimation. ANNs are the information processing systems, which can inspect the empirical data and investigate the relations (hidden rules) among them, and then make the network structure. In this study, multi-layer perceptron neural network trained by the steepest descent Back-Propagation (BP) algorithm was tested to simulate LE and H flux above two maize sites (rain-fed & irrigated) near Mead, Nebraska. Network training and testing was fulfilled using hourly data of including year, local time of day (DTime), leaf area index (LAI), soil water content (SWC) in 10 and 25 cm depths, soil temperature (Ts) in 10 cm depth, air temperature (Ta), vapor pressure deficit (VPD), wind speed (WS), irrigation and precipitation (P), net radiation (Rn), and the fraction of incoming Photosynthetically Active Radiation (PAR) absorbed by the canopy (fPAR), which were selected from days of year (DOY) 169 to 222 for 2001, 2003, 2005, 2007, and 2009. The results showed high correlation between actual and estimated data; the R² values for LE flux in irrigated and rain-fed sites were 0.9576, and 0.9642; and for H flux 0.8001, and 0.8478, respectively. Furthermore, the RMSE values ranged from 0.0580 to 0.0721 W/m² for LE flux and from 0.0824 to 0.0863 W/m² for H flux. In addition, the sensitivity of the fluxes with respect to each input was analyzed over the growth stages. Thus, the most powerful effects among the inputs for LE flux were identified net radiation, leaf area index, vapor pressure deficit, wind speed, and for H

  6. Effects of dynamic heat fluxes on model climate sensitivity Meridional sensible and latent heat fluxes

    NASA Technical Reports Server (NTRS)

    Gutowski, W. J., Jr.; Wang, W.-C.; Stone, P. H.

    1985-01-01

    The high- and low-latitude radiative-dynamic (HLRD) climatic model of Wang et al. (1984) was used to study the effect of meridional heat (MH) fluxes on climate changes caused by increases of CO2 abundance and solar constant variations. However, the empirical MH parameterization of the HLRD model was replaced by physically based parameterization, which gives separate meridional sensible and latent heat fluxes and provides a complete representation of the dependence of the flux on the mean temperature field. Both parameterization methods yielded about the same changes in global mean surface temperature and ice line, and both produced only small changes in meridional temperature gradient, although the latter were even smaller with the physically based parameterizations. At any latitude, the hemispheric mean surface temperature, rather than MH fluxes, dominates the surface temperature changes.

  7. Fundamental Properties of TBAF Clathrate for Usage as a Latent Heat Storage at a Room Temperature

    NASA Astrophysics Data System (ADS)

    Mizushima, Takanari; Kawamura, Hiroshi; Takao, Shingo; Yabe, Akira

    For promotion of further energy conservation, development of a coolant with a higher heat capacity regulated around a room temperature is strongly required. As a candidate of such a new coolant, we employ the clathrate hydrate, i.e., a mixture of Tetra n-butyl ammonium fluoride (TBAF) and water. This clathrate hydrate is composed of the micro crystals with an order of 100 μm in dimension. It retains fluidity and melting point at a room temperature of about 25 °C. Moreover, the melting point is able to be controlled between 25 °C and 0 °C by changing the concentration of TBAF. The temperature can be regulated by its latent heat at the melting point. Characteristics such as the latent heat and the crystal structure of the clathrate have been experimentally obtained to confirm the feasibility for its usage as the latent heat storage around a room temperature.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Implicit measurement of the latent heat in a magnetocaloric NiMnIn Heusler alloy

    NASA Astrophysics Data System (ADS)

    Ghahremani, Mohammadreza; ElBidweihy, Hatem; Bennett, Lawrence H.; Della Torre, Edward; Zou, Min; Johnson, Francis

    2013-05-01

    The latent heat linked with the first-order transformation of a NiMnIn Heusler alloy has been studied through direct measurements of the adiabatic temperature change, ΔTad, during magnetization process. The experimental procedure used guarantees independent data points and negates any contribution of hysteretic losses to the magnetocaloric effect. Thus, the differences between the magnitudes of ΔTad measurements during the magnetization with the initial temperature change directions from low-to-high and high-to-low are solely attributed to the latent heat exchange, which accompanies the irreversible structural first-order transformation. An estimate of the latent heat inducing such differences is about 0.292 J/g.

  10. Experimental investigation of the latent heat of vaporization in aqueous nanofluids

    SciTech Connect

    Lee, Soochan; Phelan, Patrick E. Dai, Lenore; Prasher, Ravi; Gunawan, Andrey; Taylor, Robert A.

    2014-04-14

    This paper reports an experimental investigation of the latent heat of vaporization (h{sub fg}) in nanofluids. Two different types of nanoparticles, graphite and silver, suspended in deionized water were exposed to a continuous laser beam (130 mW, 532 nm) to generate boiling. The latent heat of vaporization in the nanofluids was determined by the measured vapor mass generation and the heat input. To ensure that the measured h{sub fg} values are independent of heating method, the experiments were repeated with an electrically heated hot wire as a primary heat input. These experiments show considerable variation in the h{sub fg} of nanofluids. That is, graphite nanofluid exhibits an increased h{sub fg} and silver nanofluid shows a decrease in h{sub fg} compared to the value for pure water. As such, these results indicate that relatively low mass fractions of nanoparticles can apparently create large changes in h{sub fg}.

  11. Multi-heat addition turbine engine

    NASA Technical Reports Server (NTRS)

    Franciscus, Leo C. (Inventor); Brabbs, Theodore A. (Inventor)

    1993-01-01

    A multi-heat addition turbine engine (MHATE) incorporates a plurality of heat addition devices to transfer energy to air and a plurality of turbines to extract energy from the air while converting it to work. The MHATE provides dry power and lower fuel consumption or lower combustor exit temperatures.

  12. The impact of latent heating on the location and strength of the tropical easterly jet

    NASA Astrophysics Data System (ADS)

    Rao, Samrat; Srinivasan, Jayaraman

    2016-04-01

    The tropical easterly jet (TEJ) is a prominent atmospheric circulation feature observed during the Asian summer monsoon. It is generally assumed that sensible heating over the Tibetan Plateau directly influences the location of the TEJ. However, other studies have suggested the importance of latent heating in determining the jet location. In this paper, the relative importance of latent heating on the maintenance of the TEJ is explored through simulations with a general circulation model. The simulation of the TEJ by the Community Atmosphere Model, version 3.1 is discussed in detail. These simulations showed that the location of the TEJ is well correlated with the location of the precipitation. Significant zonal shifts in the location of the precipitation resulted in similar shifts in the zonal location of the TEJ. These zonal shifts had minimal effect on the large-scale structure of the jet. Further, provided that precipitation patterns were relatively unchanged, orography did not directly impact the location of the TEJ. These changes were robust even with changes in the cumulus parameterization. This suggests the potential important role of latent heating in determining the location and structure of the TEJ. These results were used to explain the significant differences in the zonal location of the TEJ in the years 1988 and 2002. To understand the contribution of the latitudinal location of latent heating on the strength of the TEJ, aqua-planet simulations were carried out. It has been shown that for similar amounts of net latent heating, the jet is stronger when heating is in the higher tropical latitudes. This may partly explain the reason for the jet to be very strong during the JJA monsoon season.

  13. Simulation and evaluation of latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Sigmon, T. W.

    1980-01-01

    The relative value of thermal energy storage (TES) for heat pump storage (heating and cooling) as a function of storage temperature, mode of storage (hotside or coldside), geographic locations, and utility time of use rate structures were derived. Computer models used to simulate the performance of a number of TES/heat pump configurations are described. The models are based on existing performance data of heat pump components, available building thermal load computational procedures, and generalized TES subsystem design. Life cycle costs computed for each site, configuration, and rate structure are discussed.

  14. The Estimation Surface Latent Heat Flux Over the Ocean and its Relationship to Marine Atmospheric Boundary Layer (MABL) Structure

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Schwemmer, Geary K.; Vandemark, Doug; Evans, Keith; Miller, David O.

    1999-01-01

    A new technique combining active and passive remote sensing instruments for the estimation of surface latent heat flux over the ocean is presented. This synergistic method utilizes aerosol lidar backscatter data, multi-channel infrared radiometer data and microwave scatterometer data acquired onboard the NASA P-3B research aircraft during an extended field campaign over the Atlantic ocean in support of the Lidar In-space Technology Experiment (LITE) in September of 1994. The 10 meter wind speed derived from the scatterometers and the lidar-radiometer inferred near-surface moisture are used to obtain an estimate of the surface flux of moisture via bulk aerodynamic formulae. The results are compared with the Special Sensor Microwave Imager (SSM/I) daily average latent heat flux and show reasonable agreement. However, the SSM/I values are biased high by about 30 W/sq m. In addition, the MABL height, entrainment zone thickness and integrated lidar backscatter intensity are computed from the lidar data and compared with the magnitude of the surface fluxes. The results show that the surface latent heat flux is most strongly correlated with entrainment zone top, bottom and the integrated MABL lidar backscatter, with corresponding correlation coefficients of 0.62, 0.67 and 0.61, respectively.

  15. The Estimation of Surface Latent Heat Flux over the Ocean and its Relationship to Marine Atmospheric Boundary Layer (MABL) Structure

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Schwemmer, Geary K.; Vandemark, Doug; Evans, Keith; Miller, David O.; Demoz, Belay B.; Starr, David OC. (Technical Monitor)

    2001-01-01

    A new technique combining active and passive remote sensing instruments for the estimation of surface latent heat flux over the ocean is presented. This synergistic method utilizes aerosol lidar backscatter data, multi-channel infrared radiometer data, and microwave scatterometer data acquired onboard the NASA P-313 research aircraft during an extended field campaign over the Atlantic ocean in support of the Lidar In-space Technology Experiment (LITE) in September of 1994. The 10 meter wind speed derived from scatterometers and lidar-radiometer inferred near-surface moisture are used to obtain an estimate of the surface flux of moisture via a bulk aerodynamic formula. The results are compared with the Special Sensor Microwave Imager (SSM/I) daily average latent heat flux and show reasonable agreement. However, the SSM/I values are biased low by about 15 W/sq m. In addition, the Marine Atmospheric Boundary Layer (MABL) height, entrainment zone thickness and integrated lidar backscatter intensity are computed from the lidar data and compared with the magnitude of the surface fluxes. The results show that the surface latent heat flux is most strongly correlated with entrainment zone depth, MABL height and the integrated MABL lidar backscatter, with corresponding correlation coefficients of 0.39, 0.43 and 0.71, respectively.

  16. The Estimation of Surface Latent Heat Flux Over the Ocean and its Relationship to Marine Atmospheric Boundary Layer (MABL) Structure

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Miller, David O.; Schwemmer, Geary

    2000-01-01

    A new technique combining active and passive remote sensing instruments for the estimation of surface latent heat flux over the ocean is presented. This synergistic method uses aerosol lidar backscatter data, multi-channel infrared radiometer data and microwave scatterometer data acquired onboard the NASA P-3B research aircraft during an extended field campaign over the Atlantic ocean in support of the Lidar In-space Technology Experiment (LITE) in September of 1994. The 10 meter wind speed derived from the scatterometers and the lidar-radiometer inferred near-surface moisture are used to obtain an estimate of the surface flux of moisture via bulk aerodynamic formulae. The results are compared with the Special Sensor Microwave Imager (SSM/I) daily average latent heat flux and show reasonable agreement with an rms error and bias of about 50 and 25 W per square meters, respectively. In addition, the MABL height, entrainment zone thickness and integrated lidar backscatter intensity are computed from the lidar data and compared with the magnitude of the surface fluxes. The results show that the surface latent heat flux is most strongly correlated with entrainment zone top, bottom and the integrated MABL lidar backscatter, with corresponding correlation coefficients of 0.62, 0.67 and 0.61, respectively.

  17. Sensitivity of model parameterizations for simulated latent heat flux at the snow surface for complex mountain sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The snowcover energy balance is typically dominated by net radiation and sensible and latent heat fluxes. Validation of the two latter components is rare and often difficult to undertake at complex mountain sites. Latent heat flux, the focus of this paper, is the primary coupling mechanism between...

  18. The Measurement of the Specific Latent Heat of Fusion of Ice: Two Improved Methods.

    ERIC Educational Resources Information Center

    Mak, S. Y.; Chun, C. K. W.

    2000-01-01

    Suggests two methods for measuring the specific latent heat of ice fusion for high school physics laboratories. The first method is an ice calorimeter which is made from simple materials. The second method improves the thermal contact and allows for a more accurate measurement. Lists instructions for both methods. (Author/YDS)

  19. Robust estimates of soil moisture and latent heat flux coupling strength obtained from triple collocation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land surface models (LSMs) are often applied to predict the one-way coupling strength between surface soil moisture (SM) and surface latent heat (LH) flux. However, the ability of LSMs to accurately represent such coupling has not been adequately established. Likewise, the estimation of one-way SM/L...

  20. Daily evapotranspiration estimates by scaling instantaneous latent heat flux derived from a two-source model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radiometric brightness temperature can be used in energy balance models that estimate sensible and latent heat fluxes of the land surface. However, brightness temperature is usually available only at one time of day when acquired from aircraft, fine-scale satellite platforms, or infrared thermometer...

  1. Joseph Black, carbon dioxide, latent heat, and the beginnings of the discovery of the respiratory gases.

    PubMed

    West, John B

    2014-06-15

    The discovery of carbon dioxide by Joseph Black (1728-1799) marked a new era of research on the respiratory gases. His initial interest was in alkalis such as limewater that were thought to be useful in the treatment of renal stone. When he studied magnesium carbonate, he found that when this was heated or exposed to acid, a gas was evolved that he called "fixed air" because it had been combined with a solid material. He showed that the new gas extinguished a flame, that it could not support life, and that it was present in gas exhaled from the lung. Within a few years of his discovery, hydrogen, nitrogen, and oxygen were also isolated. Thus arguably Black's work started the avalanche of research on the respiratory gases carried out by Priestley, Scheele, Lavoisier, and Cavendish. Black then turned his attention to heat and he was the first person to describe latent heat, that is the heat added or lost when a liquid changes its state, for example when water changes to ice or steam. Latent heat is a key concept in thermal physiology because of the heat lost when sweat evaporates. Black was a friend of the young James Watt (1736-1819) who was responsible for the development of early steam engines. Watt was puzzled why so much cooling was necessary to condense steam into water, and Black realized that the answer was the latent heat. The resulting improvements in steam engines ushered in the Industrial Revolution. PMID:24682452

  2. Latent heat of the first-order magnetic transition of MnFeSi0.33P0.66

    NASA Astrophysics Data System (ADS)

    Roy, P.; Brück, E.; de Groot, R. A.

    2016-04-01

    The latent heat of a magnetoelastic phase transition is used as a measure of the magnetocaloric effect since it is directly proportional to the entropy change. Taking MnFeSi0.33P0.66 as a model magnetocaloric material, density functional theory calculations in addition to the phonon calculations based on the density functional perturbation theory were performed in order to calculate the latent heat of the magnetoelastic phase transition. The Curie temperature (TC) was determined by taking into account the quasiharmonic approximation and the configurational entropy. The material exhibits a first-order magnetic transition accompanied by a large latent-heat (19.97 kJ/kg) near-room-temperature operation.

  3. Experimental simulation of latent heat thermal energy storage and heat pipe thermal transport for dish concentrator solar receiver

    NASA Technical Reports Server (NTRS)

    Narayanan, R.; Zimmerman, W. F.; Poon, P. T. Y.

    1981-01-01

    Test results on a modular simulation of the thermal transport and heat storage characteristics of a heat pipe solar receiver (HPSR) with thermal energy storage (TES) are presented. The HPSR features a 15-25 kWe Stirling engine power conversion system at the focal point of a parabolic dish concentrator operating at 827 C. The system collects and retrieves solar heat with sodium pipes and stores the heat in NaF-MgF2 latent heat storage material. The trials were run with a single full scale heat pipe, three full scale TES containers, and an air-cooled heat extraction coil to replace the Stirling engine heat exchanger. Charging and discharging, constant temperature operation, mixed mode operation, thermal inertial, etc. were studied. The heat pipe performance was verified, as were the thermal energy storage and discharge rates and isothermal discharges.

  4. Sensible and latent heat loss from the body surface of Holstein cows in a tropical environment

    NASA Astrophysics Data System (ADS)

    Maia, A. S. C.; Dasilva, R. G.; Battiston Loureiro, C. M.

    2005-09-01

    The general principles of the mechanisms of heat transfer are well known, but knowledge of the transition between evaporative and non-evaporative heat loss by Holstein cows in field conditions must be improved, especially for low-latitude environments. With this aim 15 Holstein cows managed in open pasture were observed in a tropical region. The latent heat loss from the body surface of the animals was measured by means of a ventilated capsule, while convective heat transfer was estimated by the theory of convection from a horizontal cylinder and by the long-wave radiation exchange based on the Stefan-Boltzmann law. When the air temperature was between 10 and 36°C the sensible heat transfer varied from 160 to -30 W m-2, while the latent heat loss by cutaneous evaporation increased from 30 to 350 W m-2. Heat loss by cutaneous evaporation accounted for 20-30% of the total heat loss when air temperatures ranged from 10 to 20°C. At air temperatures >30°C cutaneous evaporation becomes the main avenue of heat loss, accounting for approximately 85% of the total heat loss, while the rest is lost by respiratory evaporation.

  5. Combining Satellite Microwave Radiometer and Radar Observations to Estimate Atmospheric Latent Heating Profiles

    NASA Technical Reports Server (NTRS)

    Grecu, Mircea; Olson, William S.; Shie, Chung-Lin; L'Ecuyer, Tristan S.; Tao, Wei-Kuo

    2009-01-01

    In this study, satellite passive microwave sensor observations from the TRMM Microwave Imager (TMI) are utilized to make estimates of latent + eddy sensible heating rates (Q1-QR) in regions of precipitation. The TMI heating algorithm (TRAIN) is calibrated, or "trained" using relatively accurate estimates of heating based upon spaceborne Precipitation Radar (PR) observations collocated with the TMI observations over a one-month period. The heating estimation technique is based upon a previously described Bayesian methodology, but with improvements in supporting cloud-resolving model simulations, an adjustment of precipitation echo tops to compensate for model biases, and a separate scaling of convective and stratiform heating components that leads to an approximate balance between estimated vertically-integrated condensation and surface precipitation. Estimates of Q1-QR from TMI compare favorably with the PR training estimates and show only modest sensitivity to the cloud-resolving model simulations of heating used to construct the training data. Moreover, the net condensation in the corresponding annual mean satellite latent heating profile is within a few percent of the annual mean surface precipitation rate over the tropical and subtropical oceans where the algorithm is applied. Comparisons of Q1 produced by combining TMI Q1-QR with independently derived estimates of QR show reasonable agreement with rawinsonde-based analyses of Q1 from two field campaigns, although the satellite estimates exhibit heating profile structure with sharper and more intense heating peaks than the rawinsonde estimates. 2

  6. Copper-silicon-magnesium alloys for latent heat storage

    DOE PAGESBeta

    Gibbs, P. J.; Withey, E. A.; Coker, E. N.; Kruizenga, A. M.; Andraka, C. E.

    2016-06-21

    The systematic development of microstructure, solidification characteristics, and heat of solidification with composition in copper-silicon-magnesium alloys for thermal energy storage is presented. Differential scanning calorimetry was used to relate the thermal characteristics to microstructural development in the investigated alloys and clarifies the location of one of the terminal three-phase eutectics. Repeated thermal cycling highlights the thermal storage stability of the transformation through multiple melting events. In conclusion, two near-terminal eutectic alloys display high enthalpies of solidification, relatively narrow melting ranges, and stable transformation hysteresis behaviors suited to thermal energy storage.

  7. Copper-Silicon-Magnesium Alloys for Latent Heat Storage

    NASA Astrophysics Data System (ADS)

    Gibbs, P. J.; Withey, E. A.; Coker, E. N.; Kruizenga, A. M.; Andraka, C. E.

    2016-06-01

    The systematic development of microstructure, solidification characteristics, and heat of solidification with composition in copper-silicon-magnesium alloys for thermal energy storage is presented. Differential scanning calorimetry was used to relate the thermal characteristics to microstructural development in the investigated alloys and clarifies the location of one of the terminal three-phase eutectics. Repeated thermal cycling highlights the thermal storage stability of the transformation through multiple melting events. Two near-terminal eutectic alloys display high enthalpies of solidification, relatively narrow melting ranges, and stable transformation hysteresis behaviors suited to thermal energy storage.

  8. Imprint of the ENSO on rainfall and latent heating variability over the Southern South China Sea from TRMM observations

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Huang, Ke

    2016-04-01

    Analyses of the Tropical Rainfall Measuring Mission (TRMM) datasets revealed a prominent interannual variation in the convective-stratiform rainfall and latent heating over the southern South China Sea (SCS) during the winter monsoon between 1998 and 2010. Although the height of maximum latent heating remained nearly constant at around 7 km in all of the years, the year-to-year changes in the magnitudes of maximum latent heating over the region were noticeable. The interannual variations of the convective- stratiform rainfall and latent heating over the southern SCS were highly anti-correlated with the Niño-3 index, with more (less) rainfall and latent heating during La Niña (El Niño) years. Analysis of the large-scale environment revealed that years of active rainfall and latent heating corresponded to years of large deep convergence and relative humidity at 600 hPa. The moisture budget diagnosis indicated that the interannual variation of humidity at 600 hPa was largely modulated by the vertical moisture advection. The year-to-year changes in rainfall over the southern SCS were mainly caused by the interannual variations of the dynamic component associated with anomalous upward motions in the middle troposphere, while the interannual variations of the thermodynamic component associated with changes in surface specific humidity played a minor role. Larger latent heating over the southern SCS during La Niña years may possibly further enhance the local Hadley circulation over the SCS in the wintertime.

  9. A neural network to retrieve the mesoscale instantaneous latent heat flux over oceans from SSM/I observations

    NASA Technical Reports Server (NTRS)

    Bourras, D.; Eymard, L.; Liu, W. T.

    2000-01-01

    The turbulent latent and sensible heat fluxes are necessary to study heat budget of the upper ocean or initialize ocean general circulation models. In order to retrieve the latent heat flux from satellite observations authors mostly use a bulk approximation of the flux whose parameters are derived from different instrument. In this paper, an approach based on artificial neural networks is proposed and compared to the bulk method on a global data set and 3 local data sets.

  10. Latent Heating Retrieval from TRMM Observations Using a Simplified Thermodynamic Model

    NASA Technical Reports Server (NTRS)

    Grecu, Mircea; Olson, William S.

    2003-01-01

    A procedure for the retrieval of hydrometeor latent heating from TRMM active and passive observations is presented. The procedure is based on current methods for estimating multiple-species hydrometeor profiles from TRMM observations. The species include: cloud water, cloud ice, rain, and graupel (or snow). A three-dimensional wind field is prescribed based on the retrieved hydrometeor profiles, and, assuming a steady-state, the sources and sinks in the hydrometeor conservation equations are determined. Then, the momentum and thermodynamic equations, in which the heating and cooling are derived from the hydrometeor sources and sinks, are integrated one step forward in time. The hydrometeor sources and sinks are reevaluated based on the new wind field, and the momentum and thermodynamic equations are integrated one more step. The reevalution-integration process is repeated until a steady state is reached. The procedure is tested using cloud model simulations. Cloud-model derived fields are used to synthesize TRMM observations, from which hydrometeor profiles are derived. The procedure is applied to the retrieved hydrometeor profiles, and the latent heating estimates are compared to the actual latent heating produced by the cloud model. Examples of procedure's applications to real TRMM data are also provided.

  11. Metal-halide mixtures for latent heat energy storage

    NASA Technical Reports Server (NTRS)

    Chen, K.; Manvi, R.

    1981-01-01

    Alkali metal and alkali halide mixtures are identified which may be suitable for thermal energy storage at temperatures above 600 C. The use of metal-halides is appropriate because of their tendency to form two immiscible melts with a density difference, which reduces scale formation and solidification on heat transfer surfaces. Also, the accumulation of phase change material along the melt interface is avoided by the self-dispersing characteristic of some metal-halides, in particular Sr-SrCl2, Ba-BaCl2, and Ba-BaBr2 mixtures. Further advantages lie in their high thermal conductivities, ability to cope with thermal shock, corrosion inhibition, and possibly higher energy densities.

  12. Additive Manufacturing and High-Performance Computing: a Disruptive Latent Technology

    NASA Astrophysics Data System (ADS)

    Goodwin, Bruce

    2015-03-01

    This presentation will discuss the relationship between recent advances in Additive Manufacturing (AM) technology, High-Performance Computing (HPC) simulation and design capabilities, and related advances in Uncertainty Quantification (UQ), and then examines their impacts upon national and international security. The presentation surveys how AM accelerates the fabrication process, while HPC combined with UQ provides a fast track for the engineering design cycle. The combination of AM and HPC/UQ almost eliminates the engineering design and prototype iterative cycle, thereby dramatically reducing cost of production and time-to-market. These methods thereby present significant benefits for US national interests, both civilian and military, in an age of austerity. Finally, considering cyber security issues and the advent of the ``cloud,'' these disruptive, currently latent technologies may well enable proliferation and so challenge both nuclear and non-nuclear aspects of international security.

  13. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 2; Evaluation of Estimates Using Independent Data

    NASA Technical Reports Server (NTRS)

    Yang, Song; Olson, William S.; Wang, Jian-Jian; Bell, Thomas L.; Smith, Eric A.; Kummerow, Christian D.

    2004-01-01

    Rainfall rate estimates from space-borne k&ents are generally accepted as reliable by a majority of the atmospheric science commu&y. One-of the Tropical Rainfall Measuring Mission (TRh4M) facility rain rate algorithms is based upon passive microwave observations fiom the TRMM Microwave Imager (TMI). Part I of this study describes improvements in the TMI algorithm that are required to introduce cloud latent heating and drying as additional algorithm products. Here, estimates of surface rain rate, convective proportion, and latent heating are evaluated using independent ground-based estimates and satellite products. Instantaneous, OP5resolution estimates of surface rain rate over ocean fiom the improved TMI algorithm are well correlated with independent radar estimates (r approx. 0.88 over the Tropics), but bias reduction is the most significant improvement over forerunning algorithms. The bias reduction is attributed to the greater breadth of cloud-resolving model simulations that support the improved algorithm, and the more consistent and specific convective/stratiform rain separation method utilized. The bias of monthly, 2.5 deg. -resolution estimates is similarly reduced, with comparable correlations to radar estimates. Although the amount of independent latent heating data are limited, TMI estimated latent heating profiles compare favorably with instantaneous estimates based upon dual-Doppler radar observations, and time series of surface rain rate and heating profiles are generally consistent with those derived from rawinsonde analyses. Still, some biases in profile shape are evident, and these may be resolved with: (a) additional contextual information brought to the estimation problem, and/or; (b) physically-consistent and representative databases supporting the algorithm. A model of the random error in instantaneous, 0.5 deg-resolution rain rate estimates appears to be consistent with the levels of error determined from TMI comparisons to collocated radar

  14. Uncertainty in Tropical Ocean Latent Heat Flux Variability During the Last 25 Years

    NASA Technical Reports Server (NTRS)

    Robertson, F. R.; Lu, H.-I.; Bosilovich, M. G.; Miller, T. L.

    2007-01-01

    When averaged over the tropical oceans (30deg N/S), latent heat flux anomalies derived from passive microwave satellite measurements as well as reanalyses and climate models driven with specified seal-surface temperatures show considerable disagreement in their decadal trends. These estimates range from virtually no trend to values over 8.4 W/sq m decade. Satellite estimates also tend to have a larger interannual signal related to El Nino/Southern Oscillation (ENSO) events than do reanalyses or model simulations. An analysis of wind speed and humidity going into bulk aerodynamic calculations used to derive these fluxes reveals several error sources. Among these are apparent remaining intercalibration issues affecting passive microwave satellite 10 m wind speeds and systematic biases in retrieval of near-surface humidity. Likewise, reanalyses suffer from discontinuities in availability of assimilated data that affect near surface meteorological variables. The results strongly suggest that current latent heat flux trends are overestimated.

  15. Spectral Retrieval of Latent Heating Profiles from TRMM PR Data: Comparison of Look-Up Tables

    NASA Technical Reports Server (NTRS)

    Shige, Shoichi; Takayabu, Yukari N.; Tao, Wei-Kuo; Johnson, Daniel E.; Shie, Chung-Lin

    2003-01-01

    The primary goal of the Tropical Rainfall Measuring Mission (TRMM) is to use the information about distributions of precipitation to determine the four dimensional (i.e., temporal and spatial) patterns of latent heating over the whole tropical region. The Spectral Latent Heating (SLH) algorithm has been developed to estimate latent heating profiles for the TRMM Precipitation Radar (PR) with a cloud- resolving model (CRM). The method uses CRM- generated heating profile look-up tables for the three rain types; convective, shallow stratiform, and anvil rain (deep stratiform with a melting level). For convective and shallow stratiform regions, the look-up table refers to the precipitation top height (PTH). For anvil region, on the other hand, the look- up table refers to the precipitation rate at the melting level instead of PTH. For global applications, it is necessary to examine the universality of the look-up table. In this paper, we compare the look-up tables produced from the numerical simulations of cloud ensembles forced with the Tropical Ocean Global Atmosphere (TOGA) Coupled Atmosphere-Ocean Response Experiment (COARE) data and the GARP Atlantic Tropical Experiment (GATE) data. There are some notable differences between the TOGA-COARE table and the GATE table, especially for the convective heating. First, there is larger number of deepest convective profiles in the TOGA-COARE table than in the GATE table, mainly due to the differences in SST. Second, shallow convective heating is stronger in the TOGA COARE table than in the GATE table. This might be attributable to the difference in the strength of the low-level inversions. Third, altitudes of convective heating maxima are larger in the TOGA COARE table than in the GATE table. Levels of convective heating maxima are located just below the melting level, because warm-rain processes are prevalent in tropical oceanic convective systems. Differences in levels of convective heating maxima probably reflect

  16. The effects of latent heat release on the waves with Ekman pumping

    NASA Technical Reports Server (NTRS)

    Tang, C. M.

    1984-01-01

    The problem of the effects of the latent heat release on the waves with both upper and lower boundary frictional effects is investigated. The influence of the vertical shear of the basic wind in these models will be investigated. These investigations will shed some light on the method of solution to the problem of including the effect of Ekman pumping on the moist baroclinic waves in the model of Tang and Fichtl.

  17. Experimental study on latent heat storage characteristics of W/O emulsion -Supercooling rate of dispersed water drops by direct contact heat exchange-

    NASA Astrophysics Data System (ADS)

    Morita, Shin-ichi; Hayamizu, Yasutaka; Horibe, Akihiko; Haruki, Naoto; Inaba, Hideo

    2013-04-01

    Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ˜ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.

  18. Cold Heat Release Characteristics of Solidified Oil Droplet-Water Solution Latent Heat Emulsion by Air Bubbles

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Morita, Shin-Ichi

    The present work investigates the cold heat-release characteristics of the solidified oil droplets (tetradecane, C14H30, freezing point 278.9 K)/water solution emulsion as a latent heat-storage material having a low melting point. An air bubbles-emulsion direct-contact heat exchange method is selected for the cold heat-results from the solidified oil droplet-emulsion layer. This type of direct-contact method results in the high thermal efficiency. The diameter of air bubbles in the emulsion increases as compared with that in the pure water. The air bubbles blown from a nozzle show a strong mixing behavior during rising in the emulsion. The temperature effectiveness, the sensible heat release time and the latent heat release time have been measured as experimental parameters. The useful nondimensional emulsion level equations for these parameters have been derived in terms of the nondimensional emalsion level expressed the emulsion layer dimensions, Reynolds number for air flow, Stefan number and heat capacity ratio.

  19. A method to model latent heat for transient analysis using NASTRAN

    NASA Technical Reports Server (NTRS)

    Harder, R. L.

    1982-01-01

    A sample heat transfer analysis is demonstrated which includes the heat of fusion. The method can be used to analyze a system with nonconstant specific heat. The enthalpy is introduced as an independent degree of freedom at each node. The user input consists of a curve of temperature as a function of enthalpy, which may include a constant temperature phase change. The basic NASTRAN heat transfer capability is used to model the effects of latent heat with existing direct matrix output and nonlinear load data cards. Although some user care is required, the numerical stability of the integration is quite good when the given recommendations are followed. The theoretical equations used and the NASTRAN techniques are shown.

  20. Including latent and sensible heat fluxes from sea spray in global weather and climate models

    NASA Astrophysics Data System (ADS)

    Copsey, Dan

    2016-04-01

    Most standard weather and climate models calculate interfacial latent (evaporation) and sensible heat fluxes over the ocean based on parameterisations of atmospheric turbulence, using the wave state only in the calculation of surface roughness length. They ignore latent and sensible heat fluxes generated by sea spray, which is an acceptable assumption at low wind speeds. However at high wind speeds (> 15 m/s) a significant amount of sea spray is generated from the sea surface which, while airborne, cools to an equilibrium temperature, absorbs heat and releases moisture before re-impacting the sea surface. This could impact, for example, the total heat loss from the Southern Ocean (which is anomalously warm in Met Office coupled models) or the accuracy of tropical cyclone forecasts. A modified version of the Fairall sea spray parameterisation scheme has been tested in the Met Office Unified Model including the JULES surface exchange model in both climate and NWP mode. The fast part of the scheme models the temperature change of the droplets to an equilibrium temperature and the slow part of the scheme models the evaporation and heat absorption while the droplets remain airborne. Including this scheme in the model cools and moistens the near surface layers of the atmosphere during high wind events, including tropical cyclones. Sea spray goes on to increase the convection intensity and precipitation near the high wind events in the model.

  1. A wind-driven, hybrid latent and sensible heat coastal polynya off Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Hirano, Daisuke; Fukamachi, Yasushi; Watanabe, Eiji; Ohshima, Kay I.; Iwamoto, Katsushi; Mahoney, Andrew R.; Eicken, Hajo; Simizu, Daisuke; Tamura, Takeshi

    2016-01-01

    The nature of the Barrow Coastal Polynya (BCP), which forms episodically off the Alaska coast in winter, is examined using mooring data, atmospheric reanalysis data, and satellite-derived sea-ice concentration and production data. We focus on oceanographic conditions such as water mass distribution and ocean current structure beneath the BCP. Two moorings were deployed off Barrow, Alaska in the northeastern Chukchi Sea from August 2009 to July 2010. For sea-ice season from December to May, a characteristic sequence of five events associated with the BCP has been identified; (1) dominant northeasterly wind parallel to the Barrow Canyon, with an offshore component off Barrow, (2) high sea-ice production, (3) upwelling of warm and saline Atlantic Water beneath the BCP, (4) strong up-canyon shear flow associated with displaced density surfaces due to the upwelling, and (5) sudden suppression of ice growth. A baroclinic current structure, established after the upwelling, caused enhanced vertical shear and corresponding vertical mixing. The mixing event and open water formation occurred simultaneously, once sea-ice production had stopped. Thus, mixing events accompanied by ocean heat flux from the upwelled warm water into the surface layer played an important role in formation/maintenance of the open water area (i.e., sensible heat polynya). The transition from a latent to a sensible heat polynya is well reproduced by a high-resolution pan-Arctic ice-ocean model. We propose that the BCP, previously considered to be a latent heat polynya, is a wind-driven hybrid latent and sensible heat polynya, with both features caused by the same northeasterly wind.

  2. New latent heat storage system with nanoparticles for thermal management of electric vehicles

    NASA Astrophysics Data System (ADS)

    Javani, N.; Dincer, I.; Naterer, G. F.

    2014-12-01

    In this paper, a new passive thermal management system for electric vehicles is developed. A latent heat thermal energy storage with nanoparticles is designed and optimized. A genetic algorithm method is employed to minimize the length of the heat exchanger tubes. The results show that even the optimum length of a shell and tube heat exchanger becomes too large to be employed in a vehicle. This is mainly due to the very low thermal conductivity of phase change material (PCM) which fills the shell side of the heat exchanger. A carbon nanotube (CNT) and PCM mixture is then studied where the probability of nanotubes in a series configuration is defined as a deterministic design parameter. Various heat transfer rates, ranging from 300 W to 600 W, are utilized to optimize battery cooling options in the heat exchanger. The optimization results show that smaller tube diameters minimize the heat exchanger length. Furthermore, finned tubes lead to a higher heat exchanger length due to more heat transfer resistance. By increasing the CNT concentration, the optimum length of the heat exchanger decreases and makes the improved thermal management system a more efficient and competitive with air and liquid thermal management systems.

  3. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Alario, J.; Kosson, R.; Haslett, R.

    1980-01-01

    Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application (300 MW sub t storage for 6 hours). Two concepts were selected for hardware development: (1) a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and (2) a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which was nickel plated to decrease adhesion forces. In addition to improving performance by providing a nearly constant transfer rate during discharge, these active heat exchanger concepts were estimated to cost at least 25% less than the passive tube-shell design.

  4. Sensible and Latent Heat Exchange at the Soil Surface Beneath a Maize Canopy

    NASA Astrophysics Data System (ADS)

    Sauer, Thomas John

    Soil heat and vapor exchange at the soil surface beneath a plant canopy was measured using heat and vapor source plates. Data from field and laboratory experiments were used to derive equations predicting interfacial heat and vapor transfer coefficients for inclusion in an existing, comprehensive soil-plant-atmosphere model, Cupid. Heat and vapor source plates constructed of anodized aluminum (305 by 864 mm by 13 mm thick) were installed level with the soil surface within a maize (Zea mays, L.) field to provide an area of known and controllable temperature and/or vapor pressure and sensible and/or latent heat flux. Sensible heat flux density was determined from an energy budget analysis while evaporation from wetted felt fabric on one plate's surface was used to determine the latent heat flux density. Flux measurements were combined with measured temperature and vapor pressure differences to determine the interfacial transfer coefficients. Field measurements were made during all stages of canopy development and were supplemented by extensive measurements of the local microclimate. Controlled forced convection experiments were also conducted in a wind tunnel using three levels of turbulence intensity and two arrays of aluminum roughness elements to assess the effects of turbulence and surface roughness on heat and mass transfer. Measured interfacial transfer coefficients during the field experiments ranged from 2 to 30 mm s ^{-1} over wind speeds of 5 to 280 cm s^{-1} measured 3 cm above the plate surface. Equations based on dimensionless parameters were developed and fit to the wind tunnel data, compared with the field data, and incorporated into the computer model. The new transfer coefficient relationships had less scatter and were more closely correlated to within -canopy wind speed than the previous formulations. Predictions of canopy microclimate characteristics were significantly improved as compared to those predictions obtained using transfer coefficients

  5. Latent heat thermal energy storage: Determination of properties of storage media and development of a new transfer system

    NASA Astrophysics Data System (ADS)

    Abhat, A.; Aboul-Enein, S.; Malatidis, N. A.

    1982-01-01

    A latent heat storage system for low temperature solar heating applications was developed. Latent heat storage materials were studied and a heat exchanger design was evaluated. Thermophysical properties of 14 organic and inorganic heat storage materials, including 5 inexpensive commercial paraffins, 2 fatty acids, and 5 salt hydrates, were measured with a precision differential scanning calorimeter. Data pertaining to phase transition temperature, enthalphy and, specific heat of the heat storage materials in solid and liquid phases were taken. The influence of thermal cycling on the melting and freezing behavior of the materials and on changes in thermophysical properties was analyzed. A heat exchanger with finned annulus heat exchanger elements was investigated. Tests were performed, using two laboratory models that employed a paraffin, two fatty acids and one salt hydrate as heat storage materials.

  6. Development of approximate method to analyze the characteristics of latent heat thermal energy storage system

    SciTech Connect

    Saitoh, T.S.; Hoshi, Akira

    1999-07-01

    Third Conference of the Parties to the U.N. Framework Convention on Climate Change (COP3) held in last December in Kyoto urged the industrialized nation to reduce carbon dioxide (CO{sub 2}) emissions by 5.2 percent (on the average) below 1990 level until the period between 2008 and 2012 (Kyoto protocol). This implies that even for the most advanced countries like the US, Japan, and EU implementation of drastic policies and overcoming many barriers in market should be necessary. One idea which leads to a path of low carbon intensity is to adopt an energy storage concept. One of the reasons that the efficiency of the conventional energy systems has been relatively low is ascribed to lacking of energy storage subsystem. Most of the past energy systems, for example, air-conditioning system, do not have energy storage part and the system usually operates with low energy efficiency. Firstly, the effect of reducing CO{sub 2} emissions was also examined if the LHTES subsystems were incorporated in all the residential and building air-conditioning systems. Another field of application of the LHTES is of course transportation. Future vehicle will be electric or hybrid vehicle. However, these vehicles will need considerable energy for air-conditioning. The LHTES system will provide enough energy for this purpose by storing nighttime electricity or rejected heat from the radiator or motor. Melting and solidification of phase change material (PCM) in a capsule is of practical importance in latent heat thermal energy storage (LHTES) systems which are considered to be very promising to reduce a peak demand of electricity in the summer season and also reduce carbon dioxide (CO{sub 2}) emissions. Two melting modes are involved in melting in capsules. One is close-contact melting between the solid bulk and the capsule wall, and another is natural convection melting in the liquid (melt) region. Close-contact melting processes for a single enclosure have been solved using several

  7. A preliminary evaluation of surface latent heat flux as an earthquake precursor

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhao, J.; Wang, W.; Ren, H.; Chen, L.; Yan, G.

    2013-10-01

    The relationship between variations in surface latent heat flux (SLHF) and marine earthquakes has been a popular subject of recent seismological studies. So far, there are two key problems: how to identify the abnormal SLHF variations from complicated background signals, and how to ensure that the anomaly results from an earthquake. In this paper, we proposed four adjustable parameters for identification, classified the relationship and analyzed SLHF changes several months before six marine earthquakes by employing daily SLHF data. Additionally, we also quantitatively evaluate the long-term relationship between earthquakes and SLHF anomalies for the six study areas over a 20 yr period preceding each earthquake. The results suggest the following: (1) before the South Sandwich Islands, Papua, Samoa and Haiti earthquakes, the SLHF variations above their individual background levels have relatively low amplitudes and are difficult to be considered as precursory anomalies; (2) after removing the clustering effect, most of the anomalies prior to these six earthquakes are not temporally related to any earthquake in each study area in time sequence; (3) for each case, apart from Haiti, more than half of the studied earthquakes, which were moderate and even devastating earthquakes (larger than Mw = 5.3), had no precursory variations in SLHF; and (4) the correlation between SLHF and seismic activity depends largely on data accuracy and parameter settings. Before any application of SLHF data on earthquake prediction, we suggest that anomaly-identifying standards should be established based on long-term regional analysis to eliminate subjectivity. Furthermore, other factors that may result in SLHF variations should also be carefully considered.

  8. Method and apparatus for inoculating crystallization seeds into a liquid latent heat storage substance

    SciTech Connect

    Lindner, F.; Scheunemann, K.

    1984-07-24

    A method and apparatus for inoculating a liquid latent heat storage substance of the type convertible to the solid state on cooling is disclosed. A portion of the substance is caused to crystallize on a cooled active surface, immersed in the substance and preferably vertically arranged, whereupon the active surface is heated to fuse-off the formed crystals to release them into the liquid portion of the storage substance to thus form inoculation seeds on which further crystallization of the storage substance takes place on withdrawal of heat from same. In one described embodiment, a pair of active surfaces is provided by using a Peltier element operating with a DC source having selectively reversible polarity whereby one surface is cooled down while the other is heated and vice versa, depending on the instant polarity of the DC source. In another embodiment, the active surface is alternately heated and cooled by heat carrier medium of a heat pump circulation system drawn from the respective sections of the system in alternating fashion. Due to the formation of crystallization seeds from the heat storage substance, problems normally associated with the use of a foreign inoculation substance are avoided.

  9. Computational modeling of latent-heat-storage in PCM modified interior plaster

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Maděra, Jiří; Trník, Anton; Pavlíková, Milena; Pavlík, Zbyšek

    2016-06-01

    The latent heat storage systems represent a promising way for decrease of buildings energy consumption with respect to the sustainable development principles of building industry. The presented paper is focused on the evaluation of the effect of PCM incorporation on thermal performance of cement-lime plasters. For basic characterization of the developed materials, matrix density, bulk density, and total open porosity are measured. Thermal conductivity is accessed by transient impulse method. DSC analysis is used for the identification of phase change temperature during the heating and cooling process. Using DSC data, the temperature dependent specific heat capacity is calculated. On the basis of the experiments performed, the supposed improvement of the energy efficiency of characteristic building envelope system where the designed plasters are likely to be used is evaluated by a computational analysis. Obtained experimental and computational results show a potential of PCM modified plasters for improvement of thermal stability of buildings and moderation of interior climate.

  10. A methodology for mapping forest latent heat flux densities using remote sensing

    NASA Technical Reports Server (NTRS)

    Pierce, Lars L.; Congalton, Russell G.

    1988-01-01

    Surface temperatures and reflectances of an upper elevation Sierran mixed conifer forest were monitored using the Thematic Mapper Simulator sensor during the summer of 1985 in order to explore the possibility of using remote sensing to determine the distribution of solar energy on forested watersheds. The results show that the method is capable of quantifying the relative energy allocation relationships between the two cover types defined in the study. It is noted that the method also has the potential to map forest latent heat flux densities.

  11. Effects of latent heating on driving atmospheric circulation of brown dwarfs and directly imaged giant planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2015-12-01

    Growing observations of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs), such as brightness variability and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of BDs include modeling of convection from the interior and its interactions with stably stratified atmospheres. These models show that such interactions can drive an atmospheric circulation, forming zonal jets and/or vortices. However, these models are dry, not including condensation of various chemical species. Latent heating from condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various chemical species are believed to be an important source in driving the atmospheric circulation of BDs and directly imaged EGPs. Here we present results from three-dimensional simulations for the atmospheres of BDs and EGPs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly. We examine the circulation patterns caused by large-scale latent heating which results from condensation of silicate vapor in hot dwarfs and water vapor in the cold dwarfs. By varying the abundance of condensable vapor and the radiative timescale, we conclude that under normal atmospheric conditions of BDs (hot and thus with relatively short radiative timescale), latent heating alone by silicate vapor is unable to drive a global circulation, leaving a quiescent atmosphere, because of the suppression to moist instability by downward transport of dry air. Models with relatively long radiative timescale, which may be the case for cooler bodies, tend to maintain an active hydrological cycle and develop zonal jets. Once condensation happens, storms driven by

  12. Evaporative cooling: effective latent heat of evaporation in relation to evaporation distance from the skin.

    PubMed

    Havenith, George; Bröde, Peter; den Hartog, Emiel; Kuklane, Kalev; Holmer, Ingvar; Rossi, Rene M; Richards, Mark; Farnworth, Brian; Wang, Xiaoxin

    2013-03-15

    Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available, which has found little use in recent literature. In this experiment a thermal manikin, (MTNW, Seattle, WA) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently, allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used, and different numbers of layers were used. Tests took place in 20°C, 0.5 m/s at different humidities and were performed both dry and with a wet layer, allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin, λeff is close to the theoretical value (2,430 J/g) but starts to drop when more clothing is worn, e.g., by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base layer), increasing toward 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear, the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed. PMID:23329814

  13. Persistent unstable atmospheric boundary layer enhances sensible and latent heat loss in a tropical great lake: Lake Tanganyika

    NASA Astrophysics Data System (ADS)

    Verburg, Piet; Antenucci, Jason P.

    2010-06-01

    Energy fluxes across the surface of lakes regulate heat storage and affect the water balance. Sensible and latent heat fluxes are affected by atmospheric stability, especially for large lakes. We examined the effect of atmospheric stability on the heat fluxes on seasonal time scales at Lake Tanganyika, East Africa, by estimating hourly sensible and latent heat fluxes and net radiation using thermistor chains and meteorological stations. The atmosphere was almost always unstable, in contrast to the atmosphere above North American Great Lakes which is unstable in winter and stable in summer. Persistent atmospheric instability resulted in a 13% and 18% increase in the annual mean heat loss by latent and sensible heat fluxes, respectively, relative to conditions of neutral stability. The persistent unstable atmosphere is caused by a higher water surface temperature compared with air temperature, which we argue is the case in general in (sub)tropical lakes. Low humidity further enhanced the frequency of unstable conditions and enhanced the exchange of heat and vapor from the lake to the atmosphere. The estimated heat fluxes were sensitive to the temporal scale of data inputs and to the local values of parameters such as air density. To our knowledge this is the first paper that demonstrates and quantifies the effect of atmospheric stability on latent and sensible heat fluxes from a lake on an annual basis, using data collected from the lake surface.

  14. Performance of direct contact latent heat storage units with two hydrated salts

    SciTech Connect

    Farid, M.M. ); Khalaf, A.N. )

    1994-02-01

    The performance of a direct contact latent heat storage unit, that consists of two columns with different hydrated salts, has been investigated. Na[sub 2]CO[sub 3]-10H[sub 2]O (sodium carbonate decahydrate) and Na[sub 2]S[sub 2]O[sub 3][center dot]5H[sub 2]O (sodium thiosulphate pentahydrate) were contained in separate columns both having an inside diameter and total length of 0.184 m and 1.0 m, respectively. During heat charge, the hot keresone as a heat transfer fluid was bubbled through the sodium thiosulfate solution first. The partially cooled kerosene was then pumped to the second column containing the sodium thiosulfate solution first. The partially cooled kerosene was then pumped to the second column containing the sodium carbonate solution, discharging most of its heat content. Flow direction was reversed during heat discharge. The continuous phase temperature in the two columns, as well as kerosene inlet and outlet temperatures, were measured continuously. Results showed significant improvement in heat transfer rates by using two separate columns containing similar or different salts. The use of a combination of two different salts, having different crystallization temperatures, and contained in different columns connected in series, may provide better means of heat storage by allowing the system to operate as a phase change storage for longer periods of operation. This is particularly suitable for solar energy applications in which the collector temperature may vary significantly during the day.

  15. Heat Exchange, Additive Manufacturing, and Neutron Imaging

    SciTech Connect

    Geoghegan, Patrick

    2015-02-23

    Researchers at the Oak Ridge National Laboratory have captured undistorted snapshots of refrigerants flowing through small heat exchangers, helping them to better understand heat transfer in heating, cooling and ventilation systems.

  16. Latent heat at the first order phase transition point of SU(3) gauge theory

    NASA Astrophysics Data System (ADS)

    Shirogane, Mizuki; Ejiri, Shinji; Iwami, Ryo; Kanaya, Kazuyuki; Kitazawa, Masakiyo; WHOT-QCD Collaboration

    2016-07-01

    We calculate the energy gap (latent heat) and pressure gap between the hot and cold phases of the SU(3) gauge theory at the first order deconfining phase transition point. We perform simulations around the phase transition point with the lattice size in the temporal direction Nt=6 , 8 and 12 and extrapolate the results to the continuum limit. We also investigate the spatial volume dependence. The energy density and pressure are evaluated by the derivative method with nonperturabative anisotropy coefficients. We adopt a multipoint reweighting method to determine the anisotropy coefficients. We confirm that the anisotropy coefficients approach the perturbative values as Nt increases. We find that the pressure gap vanishes at all values of Nt when the nonperturbative anisotropy coefficients are used. The spatial volume dependence in the latent heat is found to be small on large lattices. Performing extrapolation to the continuum limit, we obtain Δ ɛ /T4=0.75 ±0.17 and Δ (ɛ -3 p )/T4=0.623 ±0.056 .

  17. A Latent Heat Retrieval and its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part I: The Algorithm and Observations.

    NASA Technical Reports Server (NTRS)

    Guimond, Stephen R.; Bourassa, mark A.; Reasor, Paul D.

    2011-01-01

    The release of latent heat in clouds is an essential part of the formation and I intensification ohurricanes. The community knows very little about the intensity and structure of latent heating due largely to inadequate observations. In this paper, a new method for retrieving the latent heating field in hurricanes from airborne Dopple radar is presented and fields from rapidly intensifying Hurricane Guillermo (1997) are shown.

  18. A Wind-Driven, Hybrid Latent and Sensible Heat Coastal Polynya at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Hirano, D.; Fukamachi, Y.; Watanabe, E.; Iwamoto, K.; Mahoney, A. R.; Eicken, H.; Shimizu, D.; Ohshima, K. I.; Tamura, T.

    2014-12-01

    The nature of the Barrow Coastal Polynya (BCP) formed off the Alaska Coast in winter is examined using mooring data (temperature, salinity, and ocean current), atmospheric re-analysis data (ERA-Interim), and AMSR-E-derived sea-ice concentration and production data (Iwamoto et al., 2014). Previously, the BCP has been considered to be a latent heat polynya formed by predominantly offshore winds resulting in sea-ice divergence. Recently, it has been suggested that the sea-ice production rate in the BCP is suppressed by warm Pacific- or Atlantic-origin waters distributed beneath the BCP (e.g. Itoh et al., 2012). In this study, we focus on the oceanographic conditions such as water mass distribution and ocean current structure beneath the BCP, which have not been fully documented. A mooring was deployed off Barrow, Alaska in the northeast Chukchi Sea (71.23°N, 157.65°W, water depth 55 m) from August 2009 to July 2010. During the freeze-up period from December to May, five BCP events occurred in the same manner; 1) dominant wind parallel to Barrow Canyon, with an offshore component near Barrow, 2) high sea-ice production followed by sudden cessation of ice growth, 3) upwelling of warm (>2 K above freezing point) and saline (>34) Atlantic Water (AW) beneath the BCP, 4) strong up-canyon flow (>100cm/s) associated with density fluctuations. A baroclinic current structure, established after the upwelling, resulted in enhanced vertical shear, promoting vertical mixing. The mixing event and open water formation occurred simultaneously, once sea-ice production had stopped. Thus, mixing events accompanied by ocean heat flux from AW into the surface layer were likely to form/maintain the open water area that is a sensible heat polynya. The transition from a latent to a sensible heat polynya was well reproduced by a pan-Arctic ice-ocean model (COCO). We propose that the BCP is a hybrid latent and sensible heat polynya, with both processes driven by the same offshore wind.

  19. TRMM Latent Heating Retrieval and Comparisons with Field Campaigns and Large-Scale Analyses

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Takayabu, Yukuri; Lang, S.; Shige, S.; Olson, W.; Hou, A.; Jiang, X.; Zhang, C.; Lau, W.; Krishnamurti, T.; Waliser, D.; Grecu, M.; Ciesielski, P. E.; Johnson, R. H.; Houze, R.; Kakar, R.; Nakamura, K.; Braun, S.; Hagos, S.; Oki, R.; Bhardwaj, A.

    2012-01-01

    Rainfall production is a fundamental process within the Earth's hydrological cycle because it represents both a principal forcing term in surface water budgets, and its energetics corollary, latent heating (LH), is one of the principal sources of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The vertical distribution of LH has a strong influence on the atmosphere, controlling large-scale tropical circulations, exciting and modulating tropical waves, maintaining the intensities of tropical cyclones, and even providing the energetics of midlatitude cyclones and other mobile midlatitude weather systems. Moreover, the processes associated with LH result in significant non-linear changes in atmospheric radiation through the creation, dissipation and modulation of clouds and precipitation. Yanai et al. (1973) utilized the meteorological data collected from a sounding network to present a pioneering work on thermodynamic budgets, which are referred to as the apparent heat source (Q1) and apparent moisture sink (Q2). Yanai's paper motivated the development of satellite-based LH algorithms and provided a theoretical background for imposing large-scale advective forcing into cloud-resolving models (CRMs). These CRM-simulated LH and Q1 data have been used to generate the look-up tables used in LH algorithms. This paper examines the retrieval, validation, and application of LH estimates based on rain rate quantities acquired from the Tropical Rainfall Measuring Mission satellite (TRMM). TRMM was launched in November 1997 as a joint enterprise between the American and Japanese space agencies -- with overriding goals of providing accurate four-dimensional estimates of rainfall and LH over the global Tropics and subtropics equatorward of 35o. Other literature has acknowledged the achievement of the first goal of obtaining an accurate rainfall climatology. This paper describes the

  20. Passive and Active Microwave Remote Sensing of Precipitation and Latent Heating Distributions in the Tropics from TRMM

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Haddad, Ziad S.; Tao, Wei-Kuo; Wang, Yansen; Lang, Stephen E.; Braun, Scott A.; Chiu, Christine; Wang, Jian-Jian

    2002-01-01

    Passive and active microwave remote sensing data are analyzed to identify signatures of precipitation and vertical motion in tropical convection. A database of cloud/radiative model simulations is used to quantify surface rain rates and latent heating profiles that are consistent with these signatures. At satellite footprint-scale (approximately 10 km), rain rate and latent heating estimates are subject to significant random errors, but by averaging the estimates in space and time, random errors are substantially reduced, Bias errors have been minimized by improving the microphysics in the supporting cloud/radiative model simulations, and by imposing a consistent definition of remotely-sensed and model-simulated convective/stratiform rain coverage. Remotely-sensed precipitation and latent heating distributions in the tropics are derived from Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave/ Imager (SSM/ I) sensor data. The prototype Version 6 TRMM passive microwave algorithm typically yields average heating profiles with maxima between 6 and 7 km altitude for organized mesoscale convective systems. Retrieved heating profiles for individual convective systems are compared to coincident estimates based upon a combination of dual-Doppler radar and rawinsonde data. Also, large-scale latent heating distributions are compared to estimates derived from a simpler technique that utilizes observations of surface rain rate and stratiform rain proportion to infer vertical heating structure. Results of these tests will be presented at the conference.

  1. Comparisons of sensible and latent heat fluxes using surface and aircraft data over adjacent wet and dry surfaces

    SciTech Connect

    Doran, J.C.; Hubbe, J.M.; Shaw, W.J. ); Baldocchi, D.D.; Crawford, T.L.; Dobosy, R.J.; Meyers, T.J. . Air Resources Lab. Atmospheric Turbulence and Diffusion Div.)

    1992-01-01

    In June 1991, a field study of surface fluxes of latent and sensible heat over heterogeneous surfaces was carried out near Boardman, Oregon (Doran et al., 1992). The object of the study was to develop improved methods of extrapolating from local measurements of fluxes to area-averaged values suitable for use in general circulation models (GCMs) applied to climate studies. A grid element in a GCM is likely to encompass regions whose fluxes vary significantly from one surface type to another. The problem of integrating these fluxes into a single, representative value for the whole element is not simple, and describing such a flux in terms of flux-gradient relationships, as is often done, presents additional difficulties.

  2. Combined solar heat and power system with a latent heat storage - system simulations for an economic assessment

    NASA Astrophysics Data System (ADS)

    Zipf, Verena; Neuhäuser, Anton

    2016-05-01

    Decentralized solar combined heat and power (CHP) systems can be economically feasible, especially when they have a thermal storage. In such systems, heat provided by solar thermal collectors is used to generate electricity and useful heat for e.g. industrial processes. For the supply of energy in times without solar irradiation, a thermal storage can be integrated. In this work, the performance of a solar CHP system using an active latent heat storage with a screw heat exchanger is investigated. Annual yield calculations are conducted in order to calculate annual energy gains and, based on them; economic assumptions are used to calculated economic numbers in order to assess the system performance. The energy savings of a solar system, compared to a system with a fossil fuel supply, are calculated. Then the net present value and the dynamic payback are calculated with these savings, the initial investment costs and the operational costs. By interpretation and comparison of these economic numbers, an optimum system design in terms of solar field size and storage size was determined. It has been shown that the utilization of such systems can be economical in remote areas without gas and grid connection. Optimal storage design parameters in terms of the temperature differences in the heat exchanger and the storage capacity have been determined which can further increase the net present value of such system.

  3. Latent heat induced rotation limited aggregation in 2D ice nanocrystals

    NASA Astrophysics Data System (ADS)

    Bampoulis, Pantelis; Siekman, Martin H.; Kooij, E. Stefan; Lohse, Detlef; Zandvliet, Harold J. W.; Poelsema, Bene

    2015-07-01

    The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still not understood. Insufficient knowledge of the interaction potentials and the lack of relevant experimental access to the growth process are to blame for this failure. Here, we study the growth of fractal nanostructures in a two-dimensional (2D) system, intercalated between mica and graphene. Based on our scanning tunneling spectroscopy data, we provide compelling evidence that these fractals are 2D ice. They grow while they are in material contact with the atmosphere at 20 °C and without significant thermal contact to the ambient. The growth is studied in situ, in real time and space at the nanoscale. We find that the growing 2D ice nanocrystals assume a fractal shape, which is conventionally attributed to Diffusion Limited Aggregation (DLA). However, DLA requires a low mass density mother phase, in contrast to the actual currently present high mass density mother phase. Latent heat effects and consequent transport of heat and molecules are found to be key ingredients for understanding the evolution of the snow (ice) flakes. We conclude that not the local availability of water molecules (DLA), but rather them having the locally required orientation is the key factor for incorporation into the 2D ice nanocrystal. In combination with the transport of latent heat, we attribute the evolution of fractal 2D ice nanocrystals to local temperature dependent rotation limited aggregation. The ice growth occurs under extreme supersaturation, i.e., the conditions closely resemble the natural ones for the growth of complex 2D snow (ice) flakes and we consider our findings crucial for solving the "perennial" snow (ice) flake enigma.

  4. Latent heat induced rotation limited aggregation in 2D ice nanocrystals.

    PubMed

    Bampoulis, Pantelis; Siekman, Martin H; Kooij, E Stefan; Lohse, Detlef; Zandvliet, Harold J W; Poelsema, Bene

    2015-07-21

    The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still not understood. Insufficient knowledge of the interaction potentials and the lack of relevant experimental access to the growth process are to blame for this failure. Here, we study the growth of fractal nanostructures in a two-dimensional (2D) system, intercalated between mica and graphene. Based on our scanning tunneling spectroscopy data, we provide compelling evidence that these fractals are 2D ice. They grow while they are in material contact with the atmosphere at 20 °C and without significant thermal contact to the ambient. The growth is studied in situ, in real time and space at the nanoscale. We find that the growing 2D ice nanocrystals assume a fractal shape, which is conventionally attributed to Diffusion Limited Aggregation (DLA). However, DLA requires a low mass density mother phase, in contrast to the actual currently present high mass density mother phase. Latent heat effects and consequent transport of heat and molecules are found to be key ingredients for understanding the evolution of the snow (ice) flakes. We conclude that not the local availability of water molecules (DLA), but rather them having the locally required orientation is the key factor for incorporation into the 2D ice nanocrystal. In combination with the transport of latent heat, we attribute the evolution of fractal 2D ice nanocrystals to local temperature dependent rotation limited aggregation. The ice growth occurs under extreme supersaturation, i.e., the conditions closely resemble the natural ones for the growth of complex 2D snow (ice) flakes and we consider our findings crucial for solving the "perennial" snow (ice) flake enigma. PMID:26203037

  5. Materials compatibility in Dish-Stirling solar generators using Cu-Si-Mg eutectic for latent heat storage

    NASA Astrophysics Data System (ADS)

    Kruizenga, A. M.; Withey, E. A.; Andraka, C. E.; Gibbs, P. J.

    2016-05-01

    Dish-Stirling systems are a strong candidate to meet cost production goals for solar thermal power production. Thermal energy storage improves the capacity factor of thermal power systems; copper-silicon-magnesium eutectic alloys have been investigated as potential latent heat storage materials. This work examines the ability of commercially available plasma spray coatings to serve as protective barriers with these alloys, while highlighting mechanistic insights into materials for latent heat storage systems. Computed tomography was leveraged as a rapid screening tool to assess the presence of localized attack in tested coatings.

  6. Novel functional materials from renewable lipids: Amphiphilic antimicrobial polymers and latent heat thermal energy storage

    NASA Astrophysics Data System (ADS)

    Floros, Michael Christopher

    Vegetable oils represent an ideal and renewable feedstock for the synthesis of a variety of functional materials. However, without financial incentive or unique applications motivating a switch, commercial products continue to be manufactured from petrochemical resources. Two different families of high value, functional materials synthesized from vegetable oils were studied. These materials demonstrate superior and unique performance to comparable petrochemical analogues currently on the market. In the first approach, 3 amphiphilic thermoplastic polytriazoles with differing lipophilic segment lengths were synthesized in a polymerization process without solvents or catalysts. Investigation of monomer structure influence on the resultant functional behaviour of these polymers found distinctive odd/even behaviour reliant on the number of carbon atoms in the monomers. Higher concentrations of triazole groups, due to shorter CH2 chains in the monomeric dialkynes, resulted in more brittle polymers, displaying higher tensile strengths but reduced elongation to break characteristics. These polymers had similar properties to commercial petroleum derived thermoplastics. One polymer demonstrated self-assembled surface microstructuring, and displayed hydrophobic properties. Antimicrobial efficacy of the polymers were tested by applying concentrated bacterial solutions to the surfaces, and near complete inhibition was demonstrated after 4 hours. Scanning electron microscope images of killed bacteria showed extensive membrane damage, consistent with the observed impact of other amphiphilic compounds in literature. These polytriazoles are suited for applications in medical devices and implants, where major concerns over antibiotic resistance are prevalent. In the second approach, a series of symmetric, saturated diester phase change materials (PCMs) were also synthesized with superior latent heat values compared to commercial petrochemical analogues. These diesters exhibit

  7. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.; Knowles, G. R.; Mathur, A. K.; Budimir, J.

    1979-01-01

    Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs. A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out.

  8. Robust estimates of soil moisture and latent heat flux coupling strength obtained from triple collocation

    NASA Astrophysics Data System (ADS)

    Crow, Wade T.; Lei, Fangni; Hain, Christopher; Anderson, Martha C.; Scott, Russell L.; Billesbach, David; Arkebauer, Timothy

    2015-10-01

    Land surface models (LSMs) are often applied to predict the one-way coupling strength between surface soil moisture (SM) and latent heat (LH) flux. However, the ability of LSMs to accurately represent such coupling has not been adequately established. Likewise, the estimation of SM/LH coupling strength using ground-based observational data is potentially compromised by the impact of independent SM and LH measurements errors. Here we apply a new statistical technique to acquire estimates of one-way SM/LH coupling strength which are nonbiased in the presence of random error using a triple collocation approach based on leveraging the simultaneous availability of independent SM and LH estimates acquired from (1) LSMs, (2) satellite remote sensing, and (3) ground-based observations. Results suggest that LSMs do not generally overestimate the strength of one-way surface SM/LH coupling.

  9. The sensitivity of latent heat flux to the air humidity approximations used in ocean circulation models

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, Pearn P.

    1990-01-01

    In deriving the surface latent heat flux with the bulk formula for the thermal forcing of some ocean circulation models, two approximations are commonly made to bypass the use of atmospheric humidity in the formula. The first assumes a constant relative humidity, and the second supposes that the sea-air humidity difference varies linearly with the saturation humidity at sea surface temperature. Using climatological fields derived from the Marine Deck and long time series from ocean weather stations, the errors introduced by these two assumptions are examined. It is shown that the errors reach above 100 W/sq m over western boundary currents and 50 W/sq m over the tropical ocean. The two approximations also introduce erroneous seasonal and spatial variabilities with magnitudes over 50 percent of the observed variabilities.

  10. Dehumidification: Prediction of Condensate Flow Rate for Plate-Fin Tube Heat Exchangers Using the Latent j Factor

    SciTech Connect

    Baxter, V.D.; Chen, D.T.; Conklin, J.C.

    1999-03-15

    Condensate flow rate is an important factor in designing dehumidifiers or evaporators. In this paper, the latentj fimtor is used to analyze the dehumidification performance of two plate-fin tube heat exchangers. This latent j factor, analogous to the total j factor, is a flmction of the mass transfa coefllcient, the volumetric air flow rate, and the Schmidt number. This latent j factor did predict condensate flow rate more directly and accurately than any other sensiblej factor method. The Iatentj factor has been used in the present study because the sensible j factor correlations presented in the literature failed to predict the condensate flow rate at high Reynolds numbers. Results show that the latent j i%ctor em be simply correlated as a fhnction of the Reynolds number based on the tube outside diameter and number of rows of the heat exchanger.

  11. Precipitation and Latent Heating Distributions from Satellite Passive Microwave Radiometry. Part 1; Method and Uncertainties

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Kummerow, Christian D.; Yang, Song; Petty, Grant W.; Tao, Wei-Kuo; Bell, Thomas L.; Braun, Scott A.; Wang, Yansen; Lang, Stephen E.; Johnson, Daniel E.

    2004-01-01

    A revised Bayesian algorithm for estimating surface rain rate, convective rain proportion, and latent heating/drying profiles from satellite-borne passive microwave radiometer observations over ocean backgrounds is described. The algorithm searches a large database of cloud-radiative model simulations to find cloud profiles that are radiatively consistent with a given set of microwave radiance measurements. The properties of these radiatively consistent profiles are then composited to obtain best estimates of the observed properties. The revised algorithm is supported by an expanded and more physically consistent database of cloud-radiative model simulations. The algorithm also features a better quantification of the convective and non-convective contributions to total rainfall, a new geographic database, and an improved representation of background radiances in rain-free regions. Bias and random error estimates are derived from applications of the algorithm to synthetic radiance data, based upon a subset of cloud resolving model simulations, and from the Bayesian formulation itself. Synthetic rain rate and latent heating estimates exhibit a trend of high (low) bias for low (high) retrieved values. The Bayesian estimates of random error are propagated to represent errors at coarser time and space resolutions, based upon applications of the algorithm to TRMM Microwave Imager (TMI) data. Errors in instantaneous rain rate estimates at 0.5 deg resolution range from approximately 50% at 1 mm/h to 20% at 14 mm/h. These errors represent about 70-90% of the mean random deviation between collocated passive microwave and spaceborne radar rain rate estimates. The cumulative algorithm error in TMI estimates at monthly, 2.5 deg resolution is relatively small (less than 6% at 5 mm/day) compared to the random error due to infrequent satellite temporal sampling (8-35% at the same rain rate).

  12. Discussion on the Correlation of Surface Latent Heat Flux Variation and Marine Earthquakes

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Zhang, W.; Wang, W.; Ren, H.; Yan, G.

    2011-12-01

    In recent years, the relationship between the anomalous variation of SLHF (Surface Latent Heat Flux) and marine earthquakes has been a new subject of seismology study. It is a key problem that how to detect and extract the abnormal changes which is directly or indirectly result of seismic activities from the whole complicated latent heat flux varying background. In this presentation, by using SLHF data of NCEP (National Center for Environmental Prediction), we discussed the SLHF behaviors prior and post to five giant marine earthquakes (Sumatra, 2001/01/12, Mw9.1; Papua, 2009/01/03, Ms7.7; Samoa 2009/09/29, Ms8.0; Haiti, 2010/01/12, Ms7.0 and Tohoku, 2011/03/11, Mw 9.0). Besides, we also analyzed the long-term relationship of earthquakes and so-called SLHF anomalies of the five individual study areas in twenty years. The results suggest that, (1) the SLHF variations which happened before Tohoku and Papua earthquake were probably not anomalies, and they might not be caused by these events; (2) there were many "anomalies" which cannot find out any earthquake in the study area might be related to; (3) there were more than 60% earthquakes without any SLHF varying precursors; (4) related factors should be taken into account as many as possible to analyze correlation between SLHF variation and seismic activities; (5) we should investigate long time series data instead of focusing on individual earthquake event; (6) the detecting procedure should be formalized and related parameters should be got rid of subjective or retroactive adjustment.

  13. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.; Mathur, A. K.

    1980-01-01

    Five tasks to select, design, fabricate, test and evaluate candidate active heat exchanger modules for future applications to solar and conventional utility power plants were discussed. Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion phase change materials (PCMs) in the temperature range of 250 to 350 C. Twenty-six heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were selected for small-scale experimentation: a coated tube and shell heat exchanger and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over 50 candidate inorganic salt mixtures. Based on a salt screening process, eight major component salts were selected initially for further evaluation. The most attractive major components in the temperature range of 250 to 350 C appeared to be NaNO3, NaNO2, and NaOH. Sketches of the two active heat exchange concepts selected for test are given.

  14. The variability of hop latent viroid as induced upon heat treatment.

    PubMed

    Matousek, J; Patzak, J; Orctová, L; Schubert, J; Vrba, L; Steger, G; Riesner, D

    2001-09-01

    We have previously shown that heat treatment of hop plants infected by hop latent viroid (HLVd) reduces viroid levels. Here we investigate whether such heat treatment leads to the accumulation of sequence variability in HLVd. We observed a negligible level of mutated variants in HLVd under standard cultivation conditions. In contrast, the heat treatment of hop led to HLVd degradation and, simultaneously, to a significant increase in sequence variations, as judged from temperature gradient-gel electrophoresis analysis and cDNA library screening by DNA heteroduplex analysis. Thirty-one cDNA clones (9.8%) were identified as deviating forms. Sequencing showed mostly the presence of quadruple and triple mutants, suggesting an accumulation of mutations in HLVd during successive replication cycles. Sixty-nine percent of base changes were localised in the left half and 31% in the right half of the secondary structure proposed for this viroid. No mutations were found in the central part of the upper conserved region. A "hot spot" region was identified in a domain known as a "pathogenicity domain" in the group representative, potato spindle tuber viroid. Most mutations are predicted to destabilise HLVd secondary structure. All mutated cDNAs, however, were infectious and evolved into complex progeny populations containing molecular variants maintained at low levels. PMID:11531412

  15. A dual-temperature-difference approach to estimate daytime sensible and latent heat fluxes under advective conditions during BEAREX08

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Dual-Temperature-Difference (DTD) approach uses continuous radiometric surface temperature measurements in a two-source (soil + vegetation) energy balance model to solve for the daytime evolution of the sensible and latent heat fluxes. By using the surface-air temperature difference at two time...

  16. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Lefrois, R. T.

    1980-01-01

    Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCM's) in the temperature range of 250 C to 350 C for solar and conventional power plant applications. Over 24 heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were chosen for small-scale experimentation: a coated tube and shell that exchanger, and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over fifty inorganic salt mixtures investigated. Preliminary experiments with various tube coatings indicated that a nickel or chrome plating of Teflon or Ryton coating had promise of being successful. An electroless nickel plating was selected for further testing. A series of tests with nickel-plated heat transfer tubes showed that the solidifying sodium nitrate adhered to the tubes and the experiment failed to meet the required discharge heat transfer rate of 10 kW(t). Testing of the reflux boiler is under way.

  17. Characterization of Turbulent Latent and Sensible Heat Flux Exchange Between the Atmosphere and Ocean in MERRA

    NASA Technical Reports Server (NTRS)

    Robert, J. Brent; Robertson, Franklin R.; Clayson, Carol Anne; Bosilovich, Michael G.

    2012-01-01

    Turbulent fluxes of heat and moisture across the atmosphere-ocean interface are fundamental components of the Earth's energy and water balance. Characterizing both the spatiotemporal variability and the fidelity of these exchanges of heat and moisture is critical to understanding the global water and energy cycle variations, quantifying atmosphere-ocean feedbacks, and improving model predictability. This study examines the veracity of the recently completed NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) product with respect to its representation of the surface turbulent heat fluxes. A validation of MERRA turbulent heat fluxes and near-surface bulk variables at local, high-resolution space and time scales is achieved by making comparisons to a large suite of direct observations. Both in situ and satellite-observed gridded surface heat flux estimates are employed to investigate the spatial and temporal variability of the surface fluxes with respect to their annual mean climatologies, their seasonal covariability of near-surface bulk parameters, and their representation of extremes. The impact of data assimilation on the near-surface parameters is assessed through evaluation of incremental analysis update tendencies produced by the assimilation procedure. It is found that MERRA turbulent surface heat fluxes are relatively accurate for typical conditions but have systematically weak vertical gradients in moisture and temperature and have a weaker covariability between the near-surface gradients and wind speed than found in observations. This results in an underestimate of the surface latent and sensible heat fluxes over the western boundary current and storm track regions. The assimilation of observations mostly acts to bring MERRA closer to observational products by increasing moisture and temperature near the surface and decreasing the near-surface wind speeds. The major patterns of spatial and temporal variability of the turbulent heat

  18. Characterization of Turbulent Latent and Sensible Heat Flux Exchange Between the Atmosphere and Ocean in MERRA

    NASA Technical Reports Server (NTRS)

    Roberts, J. Brent; Robertson, Franklin R.; Clayson, Carol Anne; Bosilovich, Michael G.

    2012-01-01

    Turbulent fluxes of heat and moisture across the atmosphere-ocean interface are fundamental components of the Earth s energy and water balance. Characterizing both the spatiotemporal variability and the fidelity of these exchanges of heat and moisture is critical to understanding the global water and energy cycle variations, quantifying atmosphere-ocean feedbacks, and improving model predictability. This study examines the veracity of the recently completed NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) product with respect to its representation of the surface turbulent heat fluxes. A validation of MERRA turbulent heat fluxes and near-surface bulk variables at local, high-resolution space and time scales is achieved by making comparisons to a large suite of direct observations. Both in situ and satellite-observed gridded surface heat flux estimates are employed to investigate the spatial and temporal variability of the surface fluxes with respect to their annual mean climatologies, their seasonal covariability of near-surface bulk parameters, and their representation of extremes. The impact of data assimilation on the near-surface parameters is assessed through evaluation of incremental analysis update tendencies produced by the assimilation procedure. It is found that MERRA turbulent surface heat fluxes are relatively accurate for typical conditions but have systematically weak vertical gradients in moisture and temperature and have a weaker covariability between the near-surface gradients and wind speed than found in observations. This results in an underestimate of the surface latent and sensible heat fluxes over the western boundary current and storm track regions. The assimilation of observations mostly acts to bring MERRA closer to observational products by increasing moisture and temperature near the surface and decreasing the near-surface wind speeds. The major patterns of spatial and temporal variability of the turbulent heat

  19. The application of satellite data to study the effects of latent heat release on cyclones

    NASA Technical Reports Server (NTRS)

    Clark, J. H. E.

    1984-01-01

    Generalized energetics were studied for nonlinear inviscid symmetric instability (SI). It was found that the linear theory fails to predict the stability in certain cases where the basic state is transitional between stability and instability. The initial growth of the SI perturbations can be fairly well approximated by linear theory, but the long time nonlinear evaluations will be bonded energetically if the SI region is finite. However, a further extension of the energetics to conditional symmetric instability (CSI) shows that the nonlinear evolution of circulation will energetically depend much more on the precipitation in a complicated way. By treating the latent heat as a source which is implicitly related to the motion field, the existence, uniqueness and stability of steady viscous (CSI) circulations are studied. Viscous CSI circulations are proved to be unique and asymptotically stable when the heat sources are weak and less sensitive to the motion perturbations. By considering the fact that moist updrafts are narrow and using eddy viscosity of 0(1,000 m squared/s) the stability criterion suggests that some frontal rainbands were probably dominated by the CSI mechanism even in their mature quasi-steady stage.

  20. Active heat exchange system development for latent heat thermal energy storage

    NASA Technical Reports Server (NTRS)

    Alario, J.; Haslett, R.

    1980-01-01

    Various active heat exchange concepts were identified from among three generic categories: scrapers, agitators/vibrators and slurries. The more practical ones were given a more detailed technical evaluation and an economic comparison with a passive tube-shell design for a reference application. Two concepts selected for hardware development are a direct contact heat exchanger in which molten salt droplets are injected into a cooler counterflowing stream of liquid metal carrier fluid, and a rotating drum scraper in which molten salt is sprayed onto the circumference of a rotating drum, which contains the fluid heat sink in an internal annulus near the surface. A fixed scraper blade removes the solidified salt from the surface which has been nickel plated to decrease adhesion forces. Suitable phase change material (PCM) storage media with melting points in the temperature range of interest (250 C to 400 C) were investigated. The specific salt recommended for laboratory tests was a chloride eutectic (20.5KCl-24/5 NaCl-55.0MgCl 2% by wt.), with a nominal melting point of 385 C.

  1. Cloud-scale simulation study on the evolution of latent heat processes of mesoscale convective system accompanying heavy rainfall: The Hainan case

    NASA Astrophysics Data System (ADS)

    Li, Jiangnan; Wu, Kailu; Li, Fangzhou; Chen, Youlong; Huang, Yanbin

    2016-03-01

    This paper investigates the structure of latent heat budgets and dynamical structure of mesoscale convective systems (MCS) accompanying heavy rain using a cloud-scale model WRF simulation for the Hainan case. Results show that: (1) according to the fractions skill score and HK scores, the WDM6 scheme is more suitable to predict the rainfall than other microphysical schemes. (2) During the lifetime of MCSs, the top two heating microphysical processes are water vapor condensed into cloud water and water vapor condensed into rainwater. The total latent heat is closely related to the top two heating processes. However, the change of latent heat released by some microphysical processes is not identical with the different rainfall processes. (3) The total latent heat of MCS1 increases during the short life, while the total latent heat of MCS2 and MCS3 reach maximum during the mature stage. The difference is mainly caused by the latent heat of water vapor condensed into cloud water and rainwater. The total latent heat released by cond and rcond of MCS1 is smallest during the mature stage, while it is largest during the mature stage of MCS2 and MCS3. (4) The vertical motions are different with different MCSs. The descending motion of the short-lived process (MCS1) is strongest during the mature stage. It caused the smallest latent heat released by water vapor condensed into cloud water and rainwater at the same period. Besides, there are some differences in the change of latent heat released by microphysical processes of MCS2 and MCS3, which are closely related to the drag force of the vertical motion.

  2. Verification of High Resolution Soil Moisture and Latent Heat in Germany

    NASA Astrophysics Data System (ADS)

    Samaniego, L. E.; Warrach-Sagi, K.; Zink, M.; Wulfmeyer, V.

    2012-12-01

    Improving our understanding of soil-land-surface-atmosphere feedbacks is fundamental to make reliable predictions of water and energy fluxes on land systems influenced by anthropogenic activities. Estimating, for instance, which would be the likely consequences of changing climatic regimes on water availability and crop yield, requires of high resolution soil moisture. Modeling it at large-scales, however, is difficult and uncertain because of the interplay between state variables and fluxes and the significant parameter uncertainty of the predicting models. At larger scales, the sub-grid variability of the variables involved and the nonlinearity of the processes complicate the modeling exercise even further because parametrization schemes might be scale dependent. Two contrasting modeling paradigms (WRF/Noah-MP and mHM) were employed to quantify the effects of model and data complexity on soil moisture and latent heat over Germany. WRF/Noah-MP was forced ERA-interim on the boundaries of the rotated CORDEX-Grid (www.meteo.unican.es/wiki/cordexwrf) with a spatial resolution of 0.11o covering Europe during the period from 1989 to 2009. Land cover and soil texture were represented in WRF/Noah-MP with 1×1~km MODIS images and a single horizon, coarse resolution European-wide soil map with 16 soil texture classes, respectively. To ease comparison, the process-based hydrological model mHM was forced with daily precipitation and temperature fields generated by WRF during the same period. The spatial resolution of mHM was fixed at 4×4~km. The multiscale parameter regionalization technique (MPR, Samaniego et al. 2010) was embedded in mHM to be able to estimate effective model parameters using hyper-resolution input data (100×100~km) obtained from Corine land cover and detailed soil texture fields for various horizons comprising 72 soil texture classes for Germany, among other physiographical variables. mHM global parameters, in contrast with those of Noah-MP, were

  3. Estimation of the average exchanges in momentum and latent heat between the atmosphere and the oceans with Seasat observations

    NASA Technical Reports Server (NTRS)

    Liu, W. T.

    1983-01-01

    Ocean-surface momentum flux and latent heat flux are determined from Seasat-A data from 1978 and compared with ship observations. Momentum flux was measured using the Seasat-A scatterometer system (SASS) heat flux, with the scanning multichannel MW radiometer (SMMR). Ship measurements were quality selected and averaged to increase their reliability. The fluxes were computed using a bulk parameterization technique. It is found that although SASS effectively measures momentum flux, variations in atmospheric stability and sea-surface temperature cause deviations which are not accounted for by the present data-processing algorithm. The SMMR-latent-heat-flux algorithm, while needing refinement, is shown to given estimations to within 35 W/sq m in its present form, which removes systematic error and uses an empirically determined transfer coefficient.

  4. A comparison of surface sensible and latent heat fluxes from aircraft and surface measurements in FIFE 1987

    NASA Technical Reports Server (NTRS)

    Kelly, Robert D.; Smith, Eric A.; Macpherson, J. Ian

    1990-01-01

    Surface fluxes of sensible and latent heat over a tall-grass prairie in central Kansas, as measured by 22 surface stations during FIFE 1987, are compared with values gained indirectly by linear extrapolation of aircraft-measured flux profiles to the surface. The results of 33 such comparisons covering the period 26 June to 13 October 1987 indicate that the sensible heat flux profiles were generally more linear with less scatter in the measurements at each level than were the latent heat flux profiles, the profile extrapolations of sensible heat flux in general underestimate the surface averages by about 30 percent, with slightly better agreement during periods of small flux, and the profile extrapolations of latent heat flux in general underestimate the surface averages by about 15 percent, with overestimates during periods of small fluxes (dry conditions) and overestimates during periods of large fluxes (moist conditions). Possible origins of the differences between the two sets of measurements are discussed, as directions for further research.

  5. A Comparison of Latent Heat Fluxes over Global Oceans for Four Flux Products

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.

    2003-01-01

    To improve our understanding of global energy and water cycle variability, and to improve model simulations of climate variations, it is vital to have accurate latent heat fluxes (LHF) over global oceans. Monthly LHF, 10-m wind speed (U10m), 10-m specific humidity (Q10h), and sea-air humidity difference (Qs-Q10m) of GSSTF2 (version 2 Goddard Satellite-based Surface Turbulent Fluxes) over global Oceans during 1992-93 are compared with those of HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP (NCEP/NCAR reanalysis). The mean differences, standard deviations of differences, and temporal correlation of these monthly variables over global Oceans during 1992-93 between GSSTF2 and each of the three datasets are analyzed. The large-scale patterns of the 2yr-mean fields for these variables are similar among these four datasets, but significant quantitative differences are found. The temporal correlation is higher in the northern extratropics than in the south for all variables, with the contrast being especially large for da Silva as a result of more missing ship data in the south. The da Silva has extremely low temporal correlation and large differences with GSSTF2 for all variables in the southern extratropics, indicating that da Silva hardly produces a realistic variability in these variables. The NCEP has extremely low temporal correlation (0.27) and large spatial variations of differences with GSSTF2 for Qs-Q10m in the tropics, which causes the low correlation for LHF. Over the tropics, the HOAPS LHF is significantly smaller than GSSTF2 by approx. 31% (37 W/sq m), whereas the other two datasets are comparable to GSSTF2. This is because the HOAPS has systematically smaller LHF than GSSTF2 in space, while the other two datasets have very large spatial variations of large positive and negative LHF differences with GSSTF2 to cancel and to produce smaller regional-mean differences. Our analyses suggest that the GSSTF2 latent heat flux

  6. Aircraft- and tower-based fluxes of carbon dioxide, latent, and sensible heat

    NASA Technical Reports Server (NTRS)

    Desjardins, R. L.; Hart, R. L.; Macpherson, J. I.; Schuepp, P. H.; Verma, S. B.

    1992-01-01

    Fluxes of carbon dioxide, water vapor, and sensible heat obtained over a grassland ecosystem, during the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), using an aircraft- and two tower-based systems are compared for several days in 1987 and in 1989. The tower-based cospectral estimates of CO2, sensible heat, water vapor, and momentum, expressed as a function of wavenumber K times sampling height z, are relatively similar to the aircraft-based estimates for K x z greater than 0.1. A measurable contribution to the fluxes is observed by tower-based systems at K x z less than 0.01 but not by the aircraft-based system operating at an altitude of approximately 100 m over a 15 x 15 km area. Using all available simultaneous aircraft and tower data, flux estimates by both systems were shown to be highly correlated. As expected from the spatial variations of the greenness index, surface extrapolation of airborne flux estimates tended to lie between those of the two tower sites. The average fluxes obtained, on July 11, 1987, and August 4, 1989, by flying a grid pattern over the FIFE site agreed with the two tower data sets for CO2, but sensible and latent heat were smaller than those obtained by the tower-based systems. However, in general, except for a small underestimation due to the long wavelength contributions and due to flux divergence with height, the differences between the aircraft- and tower-based surface estimates of fluxes appear to be mainly attributable to differences in footprint, that is, differences in the area contributing to the surface flux estimates.

  7. Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model

    NASA Astrophysics Data System (ADS)

    Hawcroft, Matt; Dacre, Helen; Forbes, Richard; Hodges, Kevin; Shaffrey, Len; Stein, Thorwald

    2016-06-01

    Extratropical cyclones are a key feature of the weather in the extratropics, which climate models need to represent in order to provide reliable projections of future climate. Extratropical cyclones produce significant precipitation and the associated latent heat release can play a major role in their development. This study evaluates the ability of a climate model, HiGEM, to represent latent heating in extratropical cyclones. Remote sensing data is used to investigate the ability of both the climate model and ERA-Interim (ERAI) reanalysis to represent extratropical cyclone cloud features before latent heating itself is assessed. An offline radiance simulator, COSP, and the ISCCP and CloudSat datasets are used to evaluate comparable fields from HiGEM and ERAI. HiGEM is found to exhibit biases in the cloud structure of extratropical cyclones, with too much high cloud produced in the warm conveyor belt region compared to ISCCP. Significant latent heating occurs in this region, derived primarily from HiGEM's convection scheme. ERAI is also found to exhibit biases in cloud structure, with more clouds at lower altitudes than those observed in ISCCP in the warm conveyor belt region. As a result, latent heat release in ERAI is concentrated at lower altitudes. CloudSat indicates that much precipitation may be produced at too low an altitude in both HiGEM and ERAI, particularly ERAI, and neither capture observed variability in precipitation intensity. The potential vorticity structure in composite extratropical cyclones in HiGEM and ERAI is also compared. A more pronounced tropopause ridge evolves in HiGEM on the leading edge of the composite as compared to ERAI. One future area of research to be addressed is what impact these biases in the representation of latent heating have on climate projections produced by HiGEM. The biases found in ERAI indicate caution is required when using reanalyses to study cloud features and precipitation processes in extratropical cyclones or

  8. Sources of discrepancies between satellite-derived and land surface model estimates of latent heat fluxes

    NASA Astrophysics Data System (ADS)

    Lipton, Alan E.; Liang, Pan; Jiménez, Carlos; Moncet, Jean-Luc; Aires, Filipe; Prigent, Catherine; Lynch, Richard; Galantowicz, John F.; d'Entremont, Robert P.; Uymin, Gennady

    2015-03-01

    Monthly-average estimates of latent heat flux have been derived from a combination of satellite-derived microwave emissivities, day-night differences in land surface temperature (from microwave AMSR-E), downward solar and infrared fluxes from ISCCP cloud analysis, and MODIS visible and near-infrared surface reflectances. The estimates, produced with a neural network, were compared with data from the Noah land surface model, as produced for GLDAS-2, and with two alternative estimates derived from different datasets and methods. Areas with extensive, persistent, substantial discrepancies between the satellite and land surface model fluxes have been analyzed with the aid of data from flux towers. The sources of discrepancies were found to include problems with the model surface roughness length and turbulent exchange coefficients for midlatitude cropland areas in summer, inaccuracies in the precipitation data that were used as forcing for the land surface model, and model underestimation of transpiration in some forests during dry periods. At the tower sites analyzed, agreement with tower data was generally closer for our satellite-derived fluxes than for the land surface model fluxes, in terms of monthly averages.

  9. Trends and Variations of Ocean Surface Latent Heat Flux: Results from GSSTF2c Data Set

    NASA Technical Reports Server (NTRS)

    Gao, Si; Chiu, Long S.; Shie, Chung-Lin

    2013-01-01

    Trends and variations of Goddard Satellite-based Surface Turbulent Fluxes (GSSTF) version 2c (GSSTF2c) latent heat flux (LHF) are examined. This version of LHF takes account of the correction in Earth incidence angle. The trend of global mean LHF for GSSTF2c is much reduced relative to GSSTF version 2b Set 1 and Set 2 for the same period 1988-2008. Temporal increase of GSSTF2c LHF in the two decades is 11.0%, in which 3.1%, 5.8%, and 2.1% are attributed to the increase in wind, the increase in sea surface saturated air humidity, and the decrease in near-surface air humidity, respectively. The first empirical orthogonal function of LHF is a conventional El Nino Southern Oscillation (ENSO) mode. However, the trends in LHF are independent of conventional ENSO phenomena. After removing ENSO signal, the pattern of LHF trends is primarily determined by the pattern of air-sea humidity difference trends.

  10. A comparison of small and larger mesoscale latent heat and radiative fluxes: December 6 case study

    NASA Technical Reports Server (NTRS)

    Gultepe, I.; Starr, David; Heymsfield, A. J.

    1993-01-01

    Because of the small amounts of water vapor, the potential for rapid changes, and the very cold temperatures in the upper troposphere, moisture measuring instruments face several problems related to calibration and response. Calculations of eddy moisture fluxes are, therefore, subject to significant uncertainty. The purpose of this study is to examine the importance of latent heat (moisture) fluxes due to small and larger mesoscale circulations in comparison to radiative fluxes within cirrus. Scale separation is made at about 1 km because of significant changes in the structures within cirrus. Only observations at warmer than -40 C are used in this study. The EG&G hygrometer that is used for measuring dewpoint temperature (Td) is believed to be fairly accurate down to -40 C. On the other hand, Lyman-Alpha (L-alpha) hygrometer measurements of moisture may include large drift errors. In order to compensate for these drift errors, the L-alpha hygrometer is often calibrated against the EG&G hygrometer. However, large errors ensue for Td measurements at temperatures less than -40 C. The cryogenic hygrometer frost point measurements may be used to calibrate L-alpha measurements at temperatures less than -40 C. In this study, however, measurements obtained by EG&G hygrometer and L-alpha measurements are used for the flux calculations.

  11. Melting and solidification characteristics of a mixture of two types of latent heat storage material in a vessel

    NASA Astrophysics Data System (ADS)

    Yu, JikSu; Horibe, Akihiko; Haruki, Naoto; Machida, Akito; Kato, Masashi

    2016-01-01

    In this study, we investigated the fundamental melting and solidification characteristics of mannitol, erythritol, and their mixture (70 % by mass mannitol: 30 % by mass erythritol) as potential phase-change materials (PCMs) for latent heat thermal energy storage systems, specifically those pertaining to industrial waste heat, having temperatures in the range of 100-250 °C. The melting point of erythritol and mannitol, the melting peak temperature of their mixture, and latent heat were measured using differential scanning calorimetry. The thermal performance of the mannitol mixture was determined during melting and solidification processes, using a heat storage vessel with a pipe heat exchanger. Our results indicated phase-change (fusion) temperatures of 160 °C for mannitol and 113 and 150 °C for the mannitol mixture. Nondimensional correlation equations of the average heat transfer during the solidification process, as well as the temperature and velocity efficiencies of flowing silicon oil in the pipe and the phase-change material (PCM), were derived using several nondimensional parameters.

  12. Re-examining the roles of surface heat flux and latent heat release in a "hurricane-like" polar low over the Barents Sea

    NASA Astrophysics Data System (ADS)

    Kolstad, Erik W.; Bracegirdle, Thomas J.; Zahn, Matthias

    2016-07-01

    Polar lows are intense mesoscale cyclones that occur at high latitudes in both hemispheres during winter. Their sometimes evidently convective nature, fueled by strong surface fluxes and with cloud-free centers, have led to some polar lows being referred to as "arctic hurricanes." Idealized studies have shown that intensification by hurricane development mechanisms is theoretically possible in polar winter atmospheres, but the lack of observations and realistic simulations of actual polar lows have made it difficult to ascertain if this occurs in reality. Here the roles of surface heat fluxes and latent heat release in the development of a Barents Sea polar low, which in its cloud structures showed some similarities to hurricanes, are studied with an ensemble of sensitivity experiments, where latent heating and/or surface fluxes of sensible and latent heat were switched off before the polar low peaked in intensity. To ensure that the polar lows in the sensitivity runs did not track too far away from the actual environmental conditions, a technique known as spectral nudging was applied. This was shown to be crucial for enabling comparisons between the different model runs. The results presented here show that (1) no intensification occurred during the mature, postbaroclinic stage of the simulated polar low; (2) surface heat fluxes, i.e., air-sea interaction, were crucial processes both in order to attain the polar low's peak intensity during the baroclinic stage and to maintain its strength in the mature stage; and (3) latent heat release played a less important role than surface fluxes in both stages.

  13. Revisiting the latent heat nudging scheme for the rainfall assimilation of a simulated convective storm

    NASA Astrophysics Data System (ADS)

    Leuenberger, D.; Rossa, A.

    2007-12-01

    Next-generation, operational, high-resolution numerical weather prediction models require economical assimilation schemes for radar data. In the present study we evaluate and characterise the latent heat nudging (LHN) rainfall assimilation scheme within a meso-γ scale NWP model in the framework of identical twin simulations of an idealised supercell storm. Consideration is given to the model’s dynamical response to the forcing as well as to the sensitivity of the LHN scheme to uncertainty in the observations and the environment. The results indicate that the LHN scheme is well able to capture the dynamical structure and the right rainfall amount of the storm in a perfect environment. This holds true even in degraded environments but a number of important issues arise. In particular, changes in the low-level humidity field are found to affect mainly the precipitation amplitude during the assimilation with a fast adaptation of the storm to the system dynamics determined by the environment during the free forecast. A constant bias in the environmental wind field, on the other hand, has the potential to render a successful assimilation with the LHN scheme difficult, as the velocity of the forcing is not consistent with the system propagation speed determined by the wind. If the rainfall forcing moves too fast, the system propagation is supported and the assimilated storm and forecasts initialised therefrom develop properly. A too slow forcing, on the other hand, can decelerate the system and eventually disturb the system dynamics by decoupling the low-level moisture inflow from the main updrafts during the assimilation. This distortion is sustained in the free forecast. It has further been found that a sufficient temporal resolution of the rainfall input is crucial for the successful assimilation of a fast moving, coherent convective storm and that the LHN scheme, when applied to a convective storm, appears to necessitate a careful tuning.

  14. Estimating the daily course of Konza Prairie latent Heat fluxes using a modified Tergra model

    NASA Astrophysics Data System (ADS)

    Hope, Allen S.

    1992-11-01

    The Tergra model simulates the daily course of water and energy flows through the soil-plantatmosphere system and was intended for use with remotely sensed data. In its original form, the model is not well suited to estimating spatial patterns of latent heat flux (λE) in the Konza Prairie since the determination of canopy resistance requires knowledge of vegetation height, and the defined relationship between leaf water potential and rc is specific to C3 plants. The canopy resistance component of Tergra was replaced by a routine that includes the calculation of minimum canopy resistance (rcm) from the normalized difference vegetation index (NDVI) and stress adjustment factors for leaf water potential and vapor pressure deficit to determine actual canopy resistance (rc). The relationship between rc and leaf water potential is defined for both C3 and C4 plants, and total λE is obtained from the sum of the proportional contributions from these two vegetation classes. The modified Tergra model (Tergra-2) was tested using input and flux data collected at four First ISLSCP Field Experiment (FIFE) sites during three periods characterized by different soil moisture conditions. Tergra-2 was found to be a good simulator of λE and in most cases gave substantially better results than those obtained using the original model. The greatest inaccuracy using Tergra-2 occurred under extremely dry soil moisture conditions, whereas absolute errors for both models tended to increase around solar noon. Leaf water potential was the dominant stress factor affecting modeled rc. It was concluded that vapor pressure deficit and leaf water potential should not be regarded as completely independent factors affecting rc. A brief comparison of modeled and observed canopy temperatures is presented and discussed.

  15. Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites

    NASA Astrophysics Data System (ADS)

    Wilson, Kell B.; Baldocchi, Dennis D.; Aubinet, Marc; Berbigier, Paul; Bernhofer, Christian; Dolman, Han; Falge, Eva; Field, Chris; Goldstein, Allen; Granier, Andre; Grelle, Achim; Halldor, Thorgeirsson; Hollinger, Dave; Katul, Gabriel; Law, B. E.; Lindroth, Anders; Meyers, Tilden; Moncrieff, John; Monson, Russ; Oechel, Walter; Tenhunen, John; Valentini, Riccardo; Verma, Shashi; Vesala, Timo; Wofsy, Steve

    2002-12-01

    The warm season (mid-June through late August) partitioning between sensible (H) and latent (LE) heat flux, or the Bowen ratio (β = H/LE), was investigated at 27 sites over 66 site years within the international network of eddy covariance sites (FLUXNET). Variability in β across ecosystems and climates was analyzed by quantifying general climatic and surface characteristics that control flux partitioning. The climatic control on β was quantified using the climatological resistance (Ri), which is proportional to the ratio of vapor pressure deficit (difference between saturation vapor pressure and atmospheric vapor pressure) to net radiation (large values of Ri decrease β). The control of flux partitioning by the vegetation and underlying surface was quantified by computing the surface resistance to water vapor transport (Rc, with large values tending to increase β). There was a considerable range in flux partitioning characteristics (Rc, Ri and β) among sites, but it was possible to define some general differences between vegetation types and climates. Deciduous forest sites and the agricultural site had the lowest values of Rc and β (0.25-0.50). Coniferous forests typically had a larger Rc and higher β (typically between 0.50 and 1.00 but also much larger). However, there was notable variability in Rc and Ri between coniferous site years, most notably differences between oceanic and continental climates and sites with a distinct dry summer season (Mediterranean climate). Sites with Mediterranean climates generally had the highest net radiation, Rc, Ri, and β. There was considerable variability in β between grassland site years, primarily the result of interannual differences in soil water content and Rc.

  16. Characteristics of Precipitation, Cloud, and Latent Heating Associated with the Madden-Julian Oscillation

    NASA Technical Reports Server (NTRS)

    Lau, K-M.; Wu, H-T.

    2010-01-01

    This study investigates the evolution of cloud and rainfall structures associated with Madden Julian oscillation (MJO) using Tropical Rainfall Measuring Mission (TRMM) data. Two complementary indices are used to define MJO phases. Joint probability distribution functions (PDFs) of cloud-top temperature and radar echo-top height are constructed for each of the eight MJO phases. The genesis stage of MJO convection over the western Pacific (phases 1 and 2) features a bottom-heavy PDF, characterized by abundant warm rain, low clouds, suppressed deep convection, and higher sea surface temperature (SST). As MJO convection develops (phases 3 and 4), a transition from the bottom-heavy to top-heavy PDF occurs. The latter is associated with the development of mixed-phase rain and middle-to-high clouds, coupled with rapid SST cooling. At the MJO convection peak (phase 5), a top-heavy PDF contributed by deep convection with mixed-phase and ice-phase rain and high echo-top heights (greater than 5 km) dominates. The decaying stage (phases 6 and 7) is characterized by suppressed SST, reduced total rain, increased contribution from stratiform rain, and increased nonraining high clouds. Phase 7, in particular, signals the beginning of a return to higher SST and increased warm rain. Phase 8 completes the MJO cycle, returning to a bottom-heavy PDF and SST conditions similar to phase 1. The structural changes in rain and clouds at different phases of MJO are consistent with corresponding changes in derived latent heating profiles, suggesting the importance of a diverse mix of warm, mixed-phase, and ice-phase rain associated with low-level, congestus, and high clouds in constituting the life cycle and the time scales of MJO.

  17. Coupled fvGCM-GCE Modeling System, TRMM Latent Heating and Cloud Library

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2004-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to imiprove the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. A seed fund is available at NASA Goddard to build a MMF based on the 2D GCE model and the Goddard finite volume general circulation model (fvGCM). A prototype MMF will be developed by the end of 2004 and production runs will be conducted at the beginning of 2005. The purpose of this proposal is to augment the current Goddard MMF and other cloud modeling activities. I this talk, I will present: (1) A summary of the second Cloud Modeling Workshop took place at NASA Goddard, (2) A summary of the third TRMM Latent Heating Workshop took place at Nara Japan, (3) A brief discussion on the Goddard research plan of using Weather Research Forecast (WRF) model, and (4) A brief discussion on the GCE model on developing a global cloud simulator.

  18. Coupled fvGCM-GCE Modeling System: TRMM Latent Heating and Cloud Library

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo

    2005-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. A seed fund is available at NASA Goddard to build a MMF based on the 2D GCE model and the Goddard finite volume general circulation model (fvGCM). A prototype MMF will be developed by the end of 2004 and production runs will be conducted at the beginning of 2005. The purpose of this proposal is to augment the current Goddard MMF and other cloud modeling activities. In this talk, I will present: (1) A summary of the second Cloud Modeling Workshop took place at NASA Goddard, (2) A summary of the third TRMM Latent Heating Workshop took place at Nara Japan, (3) A brief discussion on the GCE model on developing a global cloud simulator.

  19. Surface renewal performance to independently estimate sensible and latent heat fluxes in heterogeneous crop surfaces

    NASA Astrophysics Data System (ADS)

    Suvočarev, K.; Shapland, T. M.; Snyder, R. L.; Martínez-Cob, A.

    2014-02-01

    Surface renewal (SR) analysis is an interesting alternative to eddy covariance (EC) flux measurements. We have applied two recent SR approaches, with different theoretical background, that from Castellví (2004), SRCas, and that from Shapland et al. (2012a,b), SRShap. We have applied both models for sensible (H) and latent (LE) heat flux estimation over heterogeneous crop surfaces. For this, EC equipments, including a sonic anemometer CSAT3 and a krypton hygrometer KH20, were located in two zones of drip irrigated orchards of late and early maturing peaches. The measurement period was June-September 2009. The SRCas is based on similarity concepts for independent estimation of the calibration factor (α), which varies with respect to the atmospheric stability. The SRShap is based on analysis of different ramp dimensions, separating the ones that are flux-bearing from the others that are isotropic. According to the results obtained here, there was a high agreement between the 30-min turbulent fluxes independently derived by EC and SRCas. The SRShap agreement with EC was slightly lower. Estimation of fluxes determined by SRCas resulted in higher values (around 11% for LE) with respect to EC, similarly to previously published works over homogeneous canopies. In terms of evapotranspiration, the root mean square error (RMSE) between EC and SR was only 0.07 mm h-1 (for SRCas) and 0.11 mm h-1 (for SRShap) for both measuring spots. According to the energy balance closure, the SRCas method was as reliable as the EC in estimating the turbulent fluxes related to irrigated agriculture and watershed distribution management, even when applied in heterogeneous cropping systems.

  20. A preliminary evaluation of surface latent heat flux as an earthquake precursor

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhao, J.; Wang, W.; Ren, H.; Chen, L.; Yan, G.

    2013-06-01

    The relationship between variations in surface latent heat flux (SLHF) and marine earthquakes has been a popular subject of recent seismological studies. So far, there are two key problems: how to identify the abnormal SLHF variations from complicated background signals, and how to ensure that the anomaly results from earthquake. In this paper, we proposed four adjustable parameters for identification, classified the relationship and analyze SLHF changes several months before six marine earthquakes by employing daily SLHF data. Besides, we also quantitatively evaluate the long-term relationship between earthquakes and SLHF anomalies for the six study areas over a 20 yr period preceding each earthquake. The results suggest: (1) before the South Sandwich Islands, Papua, Samoa and Haiti earthquakes, the SLHF variations above their individual background levels have relatively low amplitudes and are difficult to be considered as precursory anomalies; (2) after removing the clustering effect, most of the anomalies prior to these six earthquakes are not temporally related to any earthquake in each study area in time sequence; (3) for each case, apart from Haiti, more than half of studied earthquakes which were moderate even devastating earthquakes (larger than Mw = 5.3) had no precursory variations in SLHF; and (4) the correlation between SLHF and seismic activity depends largely on data accuracy and parameter settings. Before any application of SLHF data on earthquake prediction, we suggest that anomaly-identifying standards should be established based on long-term regional analysis to eliminate subjectivity. Furthermore, other factors which may result in SLHF variations also should be carefully considered.

  1. Analysis and Evaluation of Supersonic Underwing Heat Addition

    NASA Technical Reports Server (NTRS)

    Luidens, Roger W.; Flaherty, Richard J.

    1959-01-01

    The linearized theory for heat addition under a wing has been developed to optimize wing geometry, heat addition, and angle of attack. The optimum wing has all of the thickness on the underside of the airfoil, with maximum-thickness point well downstream, has a moderate thickness ratio, and operates at an optimum angle of attack. The heat addition is confined between the fore Mach waves from under the trailing surface of the wing. By linearized theory, a wing at optimum angle of attack may have a range efficiency about twice that of a wing at zero angle of attack. More rigorous calculations using the method of characteristics for particular flow models were made for heating under a flat-plate wing and for several wings with thickness, both with heat additions concentrated near the wing. The more rigorous calculations yield in practical cases efficiencies about half those estimated by linear theory. An analysis indicates that distributing the heat addition between the fore waves from the undertrailing portion of the wing is a way of improving the performance, and further calculations appear desirable. A comparison of the conventional ramjet-plus wing with underwing heat addition when the heat addition is concentrated near the wing shows the ramjet to be superior on a range basis up to Mach number of about B. The heat distribution under the wing and the assumed ramjet and airframe performance may have a marked effect on this conclusion. Underwing heat addition can be useful in providing high-altitude maneuver capability at high flight Mach numbers for an airplane powered by conventional ramjets during cruise.

  2. Validity of Five Satellite-Based Latent Heat Flux Algorithms for Semi-arid Ecosystems

    SciTech Connect

    Feng, Fei; Chen, Jiquan; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Liu, Meng; Zhang, Nannan; Guo, Yang; Yu, Jian; Sun, Minmin

    2015-12-09

    Accurate estimation of latent heat flux (LE) is critical in characterizing semiarid ecosystems. Many LE algorithms have been developed during the past few decades. However, the algorithms have not been directly compared, particularly over global semiarid ecosystems. In this paper, we evaluated the performance of five LE models over semiarid ecosystems such as grassland, shrub, and savanna using the Fluxnet dataset of 68 eddy covariance (EC) sites during the period 2000–2009. We also used a modern-era retrospective analysis for research and applications (MERRA) dataset, the Normalized Difference Vegetation Index (NDVI) and Fractional Photosynthetically Active Radiation (FPAR) from the moderate resolution imaging spectroradiometer (MODIS) products; the leaf area index (LAI) from the global land surface satellite (GLASS) products; and the digital elevation model (DEM) from shuttle radar topography mission (SRTM30) dataset to generate LE at region scale during the period 2003–2006. The models were the moderate resolution imaging spectroradiometer LE (MOD16) algorithm, revised remote sensing based Penman–Monteith LE algorithm (RRS), the Priestley–Taylor LE algorithm of the Jet Propulsion Laboratory (PT-JPL), the modified satellite-based Priestley–Taylor LE algorithm (MS-PT), and the semi-empirical Penman LE algorithm (UMD). Direct comparison with ground measured LE showed the PT-JPL and MS-PT algorithms had relative high performance over semiarid ecosystems with the coefficient of determination (R2) ranging from 0.6 to 0.8 and root mean squared error (RMSE) of approximately 20 W/m2. Empirical parameters in the structure algorithms of MOD16 and RRS, and calibrated coefficients of the UMD algorithm may be the cause of the reduced performance of these LE algorithms with R2 ranging from 0.5 to 0.7 and RMSE ranging from 20 to 35 W/m2 for MOD16, RRS and UMD. Sensitivity analysis showed that radiation and vegetation terms were the dominating

  3. Validity of Five Satellite-Based Latent Heat Flux Algorithms for Semi-arid Ecosystems

    DOE PAGESBeta

    Feng, Fei; Chen, Jiquan; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Liu, Meng; Zhang, Nannan; Guo, Yang; Yu, Jian; Sun, Minmin

    2015-12-09

    Accurate estimation of latent heat flux (LE) is critical in characterizing semiarid ecosystems. Many LE algorithms have been developed during the past few decades. However, the algorithms have not been directly compared, particularly over global semiarid ecosystems. In this paper, we evaluated the performance of five LE models over semiarid ecosystems such as grassland, shrub, and savanna using the Fluxnet dataset of 68 eddy covariance (EC) sites during the period 2000–2009. We also used a modern-era retrospective analysis for research and applications (MERRA) dataset, the Normalized Difference Vegetation Index (NDVI) and Fractional Photosynthetically Active Radiation (FPAR) from the moderate resolutionmore » imaging spectroradiometer (MODIS) products; the leaf area index (LAI) from the global land surface satellite (GLASS) products; and the digital elevation model (DEM) from shuttle radar topography mission (SRTM30) dataset to generate LE at region scale during the period 2003–2006. The models were the moderate resolution imaging spectroradiometer LE (MOD16) algorithm, revised remote sensing based Penman–Monteith LE algorithm (RRS), the Priestley–Taylor LE algorithm of the Jet Propulsion Laboratory (PT-JPL), the modified satellite-based Priestley–Taylor LE algorithm (MS-PT), and the semi-empirical Penman LE algorithm (UMD). Direct comparison with ground measured LE showed the PT-JPL and MS-PT algorithms had relative high performance over semiarid ecosystems with the coefficient of determination (R2) ranging from 0.6 to 0.8 and root mean squared error (RMSE) of approximately 20 W/m2. Empirical parameters in the structure algorithms of MOD16 and RRS, and calibrated coefficients of the UMD algorithm may be the cause of the reduced performance of these LE algorithms with R2 ranging from 0.5 to 0.7 and RMSE ranging from 20 to 35 W/m2 for MOD16, RRS and UMD. Sensitivity analysis showed that radiation and vegetation terms were the dominating variables

  4. Simulating heat addition via mass addition in constant area compressible flows

    NASA Astrophysics Data System (ADS)

    Heiser, W. H.; McClure, W. B.; Wood, C. W.

    1995-01-01

    A study conducted demonstrated the striking similarity between the influence of heat addition and mass addition on compressible flows. These results encourage the belief that relatively modest laboratory experiments employing mass addition can be devised that will reproduce the leading phenomena of heat addition, such as the axial variation of properties, choking, and wall-boundary-layer separation. These suggest that some aspects of the complex behavior of dual-mode ramjet/scramjet combustors could be experimentally evaluated or demonstrated by replacing combustion with less expensive, more easily controlled, and safer mass addition.

  5. The use of simple physiological and environmental measures to estimate the latent heat transfer in crossbred Holstein cows

    NASA Astrophysics Data System (ADS)

    Santos, Severino Guilherme Caetano Gonçalves dos; Saraiva, Edilson Paes; Pimenta Filho, Edgard Cavalcanti; Gonzaga Neto, Severino; Fonsêca, Vinicus França Carvalho; Pinheiro, Antônio da Costa; Almeida, Maria Elivania Vieira; de Amorim, Mikael Leal Cabral Menezes

    2016-07-01

    The aim of the present study was to estimate the heat transfer through cutaneous and respiratory evaporation of dairy cows raised in tropical ambient conditions using simple environmental and physiological measures. Twenty-six lactating crossbred cows (7/8 Holstein-Gir) were used, 8 predominantly white and 18 predominantly black. The environmental variables air temperature, relative humidity, black globe temperature, and wind speed were measured. Respiratory rate and coat surface temperature were measured at 0700, 0900, 1100, 1300, and 1500 h. The environmental and physiological data were used to estimate heat loss by respiratory (ER) and cutaneous evaporation (EC). Results showed that there was variation (P < 0.01) for respiratory rate depending on the times of the day. The highest values were recorded at 1100, 1300, and 1500 h, corresponding to 66.85 ± 10.20, 66.98 ± 7.80, and 65.65 ± 6.50 breaths/min, respectively. Thus, the amount of heat transferred via respiration ranged from 19.21 to 29.42 W/m2. There was a variation from 31.6 to 38.8 °C for coat surface temperature; these values reflected a range of 55.52 to 566.83 W/m2 for heat transfer via cutaneous evaporation. However, throughout the day, the dissipation of thermal energy through the coat surface accounted for 87.9 % total loss of latent heat, and the remainder (12.1 %) was via the respiratory tract. In conclusion, the predictive models based on respiratory rate and coat surface temperature may be used to estimate the latent heat loss in dairy cows kept confined in tropical ambient conditions.

  6. Assimilating Latent Heat Fluxes From Meteorological Geostationary Satellite Data In A Hydrological Model At The Scale of 20000 Km2

    NASA Astrophysics Data System (ADS)

    Roulin, E.

    This paper focuses on the use of evapotranspiration estimated from Meteosat data and from conventional meteorological information in a simple hydrological model at the scale of the river Scheldt and the river Meuse basins in Belgium and France. The radia- tive balance at the ground is computed from infrared and visible counts, radiosound- ing profiles and meteorological information from the synoptic network (Roulin et al., 1996). Latent heat flux is computed using the Monin-Obukhov theory and data of an automatic station. The ratio between latent heat flux and energy balance at the automatic station is used to infer evapotranspiration over the whole area (Gellens- Meulenberghs, 2000). The hydrological model is adapted from a conceptual model onto a grid of cells with 50 km2 area. Seven vegetation covers are represented. Wa- ter from vegetation and two soil buckets is depleted regarding the Penman-Monteith potential evapotranspiration. A simple assimilation scheme of the evapotranspiration from Meteosat is applied for the year 1995. The results are compared with soil mois- ture data gathered during a field campaign in a study area of 2200 km2 by UCL (Auquière et al., 1997).

  7. Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

    NASA Astrophysics Data System (ADS)

    de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes

    2014-03-01

    The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands ( P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

  8. Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment

    NASA Astrophysics Data System (ADS)

    de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes

    2013-03-01

    The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands (P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

  9. Latent heat contribution to the direct magnetocaloric effect in Ni–Mn–Ga shape memory alloys with coupled martensitic and magnetic transformations

    NASA Astrophysics Data System (ADS)

    Caballero-Flores, R.; Sánchez-Alarcos, V.; Recarte, V.; Pérez-Landazábal, J. I.; Gómez-Polo, C.

    2016-05-01

    We report the direct magnetocaloric response of materials that present a second-order phase transition in the temperature range where a first-order structural transition also occurs. In particular, the influence of the latent heat on the field-induced adiabatic temperature change has been analyzed in a Ni–Mn–Ga alloy with coupled martensitic and magnetic transformations. It is found that discrepancies around 20% arise depending on whether the latent heat is taken into account or not. From the observed results, a general expression for the indirect determination of the adiabatic temperature change, that takes into account the contributions of both the martensitic and magnetic transformations, is proposed and experimentally confirmed. The observed key role of the latent heat allows us to understand why materials with first-order transformations do not present adiabatic temperature changes as higher as those which would correspond to materials undergoing second-order transformations with similar isothermal entropy change.

  10. Regional CO2 and latent heat surface fluxes in the Southern Great Plains: Measurements, modeling, and scaling

    SciTech Connect

    Riley, W. J.; Biraud, S.C.; Torn, M.S.; Fischer, M.L.; Billesbach, D.P.; Berry, J.A.

    2009-08-15

    Characterizing net ecosystem exchanges (NEE) of CO{sub 2} and sensible and latent heat fluxes in heterogeneous landscapes is difficult, yet critical given expected changes in climate and land use. We report here a measurement and modeling study designed to improve our understanding of surface to atmosphere gas exchanges under very heterogeneous land cover in the mostly agricultural U.S. Southern Great Plains (SGP). We combined three years of site-level, eddy covariance measurements in several of the dominant land cover types with regional-scale climate data from the distributed Mesonet stations and Next Generation Weather Radar precipitation measurements to calibrate a land surface model of trace gas and energy exchanges (isotope-enabled land surface model (ISOLSM)). Yearly variations in vegetation cover distributions were estimated from Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index and compared to regional and subregional vegetation cover type estimates from the U.S. Department of Agriculture census. We first applied ISOLSM at a 250 m spatial scale to account for vegetation cover type and leaf area variations that occur on hundred meter scales. Because of computational constraints, we developed a subsampling scheme within 10 km 'macrocells' to perform these high-resolution simulations. We estimate that the Atmospheric Radiation Measurement Climate Research Facility SGP region net CO{sub 2} exchange with the local atmosphere was -240, -340, and -270 gC m{sup -2} yr{sup -1} (positive toward the atmosphere) in 2003, 2004, and 2005, respectively, with large seasonal variations. We also performed simulations using two scaling approaches at resolutions of 10, 30, 60, and 90 km. The scaling approach applied in current land surface models led to regional NEE biases of up to 50 and 20% in weekly and annual estimates, respectively. An important factor in causing these biases was the complex leaf area index (LAI) distribution within

  11. Latent Heat Flux Estimate Through an Energy Water Balance Model and Land Surface Temperature from Remote Sensing

    NASA Astrophysics Data System (ADS)

    Corbari, Chiara; Sobrino, Jose A.; Mancini, Marco; Hidalgo, Victoria

    2011-01-01

    Soil moisture plays a key role in the terrestrial water cycle and is responsible for the partitioning of precipitation between runoff and infiltration. Moreover, surface soil moisture controls the redistribution of the incoming solar radiation on land surface into sensible and latent heat fluxes. Recent developments have been made to improve soil moisture dynamics predictions with hydrologic land surface models (LSMs) that compute water and energy balances between the land surface and the low atmosphere. However, most of the time soil moisture is confined to an internal numerical model variable mainly due to its intrinsic space and time variability and to the well known difficulties in assessing its value from remote sensing as from in situ measurements. In order to exploit the synergy between hydrological distributed models and thermal remote sensed data, FEST-EWB, a land surface model that solves the energy balance equation, was developed. In this hydrological model, the energy budget is solved looking for the representative thermodynamic equilibrium temperature (RET) defined as the land surface temperature that closes the energy balance equation. So using this approach, soil moisture is linked to the latent heat flux and then to LST. In this work the relationship between land surface temperature and soil moisture is analysed using LST from AHS (airborne hyperspectral scanner), with a spatial resolution of 2-4 m, LST from MODIS, with a spatial resolution of 1000 m, and thermal infrared radiometric ground measurements that are compared with the thermodynamic equilibrium temperature from the energy water balance model. Moreover soil moisture measurements were carried out during the airborne overpasses and then compared with SM from the hydrological model. An improvement of this well known inverse relationship between soil moisture and land surface temperature is obtained when the thermodynamic approach is used. The analysis of the scale effects of the different

  12. The role of water vapor and its associated latent heating in extreme Beaufort coastal storm surge events

    NASA Astrophysics Data System (ADS)

    Gyakum, J. R.; Small, D. L.; Atallah, E.; Liu, N.; Kuo, Y.

    2009-12-01

    During the rather limited ice-free season that typically may occur from late July through early October, the Beaufort Sea region is susceptible to extreme windstorms, many of which produce damaging storm surges to low-lying coastal communities. During the most recent years, the ice-free season has lengthened, suggesting an increased vulnerability of coastal communities to cyclogenesis-related windstorms. Therefore, our research focuses on the dynamic and thermodynamic mechanisms responsible for significant surface wind events during the ice-free season in this region. We demonstrate that these storm surge events are often associated with the generation of large-scale atmospheric circulation regomes conducive to North American droughts. Our analysis methodology includes the detailed synoptic-dynamic analysis, including numerical experiments, on a case of an especially long-lived extreme storm surge that occurred in September 1999. We utilize conventional surface and upper-air station data, along with satellite and ground-based water vapor data. We also utilize global and regional reanalysis data to document the synoptic-scale and mesoscale environments associated with the cyclogenesis events. Our numerical experiments with the Weather Research and Forecasting (WRF) model include sensitivity testing with COSMIC-derived water vapor data, and sensitivity tests to illustrate the relative roles that latent heating plays in the storm surge event, at various stages in its lifecycle. A particularly important finding of our research on the devastating September 1999 storm surge event is that a relatively rare case of explosive cyclogenesis in the Gulf of Alaska is a key player in this Beaufort storm surge. The deep-tropospheric latent heating during the explosive cyclogenesis generates a dynamic tropopause ridge. This ridge in turn induces surface ridging that contributes to the strong west-northwesterlies associated with the storm surge. This generation of the dynamic

  13. A 3-year dataset of sensible and latent heat fluxes from the Tibetan Plateau, derived using eddy covariance measurements

    NASA Astrophysics Data System (ADS)

    Li, Maoshan; Babel, Wolfgang; Chen, Xuelong; Zhang, Lang; Sun, Fanglin; Wang, Binbin; Ma, Yaoming; Hu, Zeyong; Foken, Thomas

    2015-11-01

    The Tibetan Plateau (TP) has become a focus of strong scientific interest due to its role in the global water cycle and its reaction to climate change. Regional flux estimates of sensible and latent heat are important variables for linking the energy and hydrological cycles at the TP's surface. Within this framework, a 3-year dataset (2008-2010) of eddy covariance measured turbulent fluxes was compiled from four stations on the TP into a standardised workflow: corrections and quality tests were applied using an internationally comparable software package. Second, the energy balance closure ( C EB) was determined and two different closure corrections applied. The four stations (Qomolangma, Linzhi, NamCo and Nagqu) represent different locations and typical land surface types on the TP (high altitude alpine steppe with sparse vegetation, a densely vegetated alpine meadow, and bare soil/gravel, respectively). We show that the C EB differs between each surface and undergoes seasonal changes. Typical differences in the turbulent energy fluxes occur between the stations at Qomolangma, Linzhi and NamCo, while Nagqu is quite similar to NamCo. Specific investigation of the pre-monsoon, the Tibetan Plateau summer monsoon, post-monsoon and winter periods within the annual cycle reinforces these findings. The energy flux of the four sites is clearly influenced by the Tibetan Plateau monsoon. In the pre-monsoon period, sensible heat flux is the major energy source delivering heat to the atmosphere, whereas latent heat flux is greater than sensible heat flux during the monsoon season. Other factors affecting surface energy flux are topography and location. Land cover type also affects surface energy flux. The energy balance residuum indicates a typically observed overall non-closure in winter, while closure (or `turbulent over-closure') is achieved during the Tibetan Plateau summer monsoon at the Nagqu site. The latter seems to depend on ground heat flux, which is higher in the

  14. Interlayer-interaction dependence of latent heat in the Heisenberg model on a stacked triangular lattice with competing interactions

    NASA Astrophysics Data System (ADS)

    Tamura, Ryo; Tanaka, Shu

    2013-11-01

    We study the phase transition behavior of a frustrated Heisenberg model on a stacked triangular lattice by Monte Carlo simulations. The model has three types of interactions: the ferromagnetic nearest-neighbor interaction J1 and antiferromagnetic third nearest-neighbor interaction J3 in each triangular layer and the ferromagnetic interlayer interaction J⊥. Frustration comes from the intralayer interactions J1 and J3. We focus on the case that the order parameter space is SO(3)×C3. We find that the model exhibits a first-order phase transition with breaking of the SO(3) and C3 symmetries at finite temperature. We also discover that the transition temperature increases but the latent heat decreases as J⊥/J1 increases, which is opposite to the behavior observed in typical unfrustrated three-dimensional systems.

  15. Applying a simple three-dimensional eddy correlation system for latent and sensible heat flux to contrasting forest canopies

    NASA Astrophysics Data System (ADS)

    Bernhofer, Ch.

    1992-06-01

    A simple eddy correlation system is presented that allows on-line calculation of latent and sensible heat fluxes. The system is composed of a three dimensional propeller anemometer, a thermocouple and a capacitance relative humidity sensor. Results from two contrasting sites demonstrate the capability of the system to measure turbulent fluxes under varying conditions. A dry mixed (dominantly coniferous) forest in hilly terrain in Austria is compared to a well irrigated, heavily transpiring, deciduous pecan orchard in the Southwest of the US. The US site shows insufficient closure of the energy balance that is attributed to non-turbulent fluxes under advective conditions in a stable boundary layer (Blanford et al., 1991) while the Austrian site exhibits almost perfect closure with the use of the very same instruments when the boundary layer is convective and advection is negligible.

  16. Complementary-relationship-based 30 year normals (1981-2010) of monthly latent heat fluxes across the contiguous United States

    NASA Astrophysics Data System (ADS)

    Szilagyi, Jozsef

    2015-11-01

    Thirty year normal (1981-2010) monthly latent heat fluxes (ET) over the conterminous United States were estimated by a modified Advection-Aridity model from North American Regional Reanalysis (NARR) radiation and wind as well as Parameter-Elevation Regressions on Independent Slopes Model (PRISM) air and dew-point temperature data. Mean annual ET values were calibrated with PRISM precipitation (P) and validated against United States Geological Survey runoff (Q) data. At the six-digit Hydrologic Unit Code level (sample size of 334) the estimated 30 year normal runoff (P - ET) had a bias of 18 mm yr-1, a root-mean-square error of 96 mm yr-1, and a linear correlation coefficient value of 0.95, making the estimates on par with the latest Land Surface Model results but without the need for soil and vegetation information or any soil moisture budgeting.

  17. Spectral Retrieval of Latent Heating Profiles from TRMM PR data. Part 3; Moistening Estimates over Tropical Ocean Regions

    NASA Technical Reports Server (NTRS)

    Shige, S.; Takayabu, Y.; Tao, W.-K.

    2007-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of precipitation formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the tropics with the associated latent heating (LH) accounting for threefourths of the total heat energy available to the Earth's atmosphere. In the last decade, it has been established that standard products of LH from satellite measurements, particularly TRMM measurements, would be a valuable resource for scientific research and applications. Such products would enable new insights and investigations concerning the complexities of convection system life cycles, the diabatic heating controls and feedbacks related to rne-sosynoptic circulations and their forecasting, the relationship of tropical patterns of LH to the global circulation and climate, and strategies for improving cloud parameterizations In environmental prediction models. However, the LH and water vapor profile or budget (called the apparent moisture sink, or Q2) is closely related. This paper presented the development of an algorithm for retrieving Q2 using 'TRMM precipitation radar. Since there is no direct measurement of LH and Q2, the validation of algorithm usually applies a method called consistency check. Consistency checking involving Cloud Resolving Model (CRM)-generated LH and 42 profiles and algorithm-reconstructed is a useful step in evaluating the performance of a given algorithm. In this process, the CRM simulation of a time-dependent precipitation process (multiple-day time series) is used to obtain the required input parameters for a given algorithm. The algorithm is then used to "econsti-LKth"e heating and moisture profiles that the CRM simulation originally produced, and finally both sets of conformal estimates (model and algorithm) are compared each other. The results indicate that discrepancies between the reconstructed and CM-simulated profiles for Q2, especially at low levels

  18. The effect of latent heat release on synoptic-to-planetary wave interactions and its implication for satellite observations: Theoretical modeling

    NASA Technical Reports Server (NTRS)

    Branscome, Lee E.; Bleck, Rainer

    1989-01-01

    Simple models are being developed to simulate interaction of planetary and synoptic-scale waves incorporating the effects of large-scale topography; eddy heat and momentum fluxes (or nonlinear dynamics); radiative heating/cooling; and latent heat release (precipitation) in synoptic-scale waves. The importance of latent heat release is determined in oceanic storm tracks for temporal variability and time-mean behavior of planetary waves. The model results were compared with available observations of planetary and synoptic-scale wave variability and time-mean circulation. The usefulness of monitoring precipitation in oceanic storm tracks by satellite observing systems was ascertained. The modeling effort includes two different low-order quasi-geostrophic models-time-dependent version and climatological mean version. The modeling also includes a low-order primitive equation model. A time-dependent, multi-level version will be used to validate the two-level Q-G models and examine effects of spherical geometry.

  19. Extracellular heat shock protein HSP90{beta} secreted by MG63 osteosarcoma cells inhibits activation of latent TGF-{beta}1

    SciTech Connect

    Suzuki, Shigeki; Kulkarni, Ashok B.

    2010-07-30

    Transforming growth factor-beta 1 (TGF-{beta}1) is secreted as a latent complex, which consists of latency-associated peptide (LAP) and the mature ligand. The release of the mature ligand from LAP usually occurs through conformational change of the latent complex and is therefore considered to be the first step in the activation of the TGF-{beta} signaling pathway. So far, factors such as heat, pH changes, and proteolytic cleavage are reportedly involved in this activation process, but the precise molecular mechanism is still far from clear. Identification and characterization of the cell surface proteins that bind to LAP are important to our understanding of the latent TGF-{beta} activation process. In this study, we have identified heat shock protein 90 {beta} (HSP90{beta}) from the cell surface of the MG63 osteosarcoma cell line as a LAP binding protein. We have also found that MG63 cells secrete HSP90{beta} into extracellular space which inhibits the activation of latent TGF-{beta}1, and that there is a subsequent decrease in cell proliferation. TGF-{beta}1-mediated stimulation of MG63 cells resulted in the increased cell surface expression of HSP90{beta}. Thus, extracellular HSP90{beta} is a negative regulator for the activation of latent TGF-{beta}1 modulating TGF-{beta} signaling in the extracellular domain. -- Research highlights: {yields} Transforming growth factor-beta 1 (TGF-{beta}1) is secreted as a latent complex. {yields} This complex consists of latency-associated peptide (LAP) and the mature ligand. {yields} The release of the mature ligand from LAP is the first step in TGF-{beta} activation. {yields} We identified for the first time a novel mechanism for this activation process. {yields} Heat shock protein 90 {beta} is discovered as a negative regulator for this process.

  20. Development of media for dynamic latent heat storage for the low-temperature range. Part 1: Thermal analyses of selected salt hydrate systems

    NASA Technical Reports Server (NTRS)

    Kanwischer, H.; Tamme, R.

    1985-01-01

    Phase change temperatures and phase change enthalpies of seventeen salt hydrates, three double salts, and four eutectics were measured thermodynamically and the results reported herein. Good results were obtained, especially for congruently melting salt hydrates. Incongruently melting salt hydrates appear less suitable for heat storage applications. The influence of the second phase - water, acid and hydroxide - to the latent heat is described. From these results, basic values of the working temperatures and storage capabilities of various storage media compositions may be derived.

  1. Evidence for increased latent heat transport during the Cretaceous (Albian) greenhouse warming

    USGS Publications Warehouse

    Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzke, B.J.

    2004-01-01

    Quantitative estimates of increased heat transfer by atmospheric H 2O vapor during the Albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport. Sphaerosiderite ??18O values in paleosols of the North American Cretaceous Western Interior Basin are a proxy for meteoric ??18O values, and mass-balance modeling results suggest that Albian precipitation rates exceeded modern rates at both mid and high latitudes. Comparison of modeled Albian and modern precipitation minus evaporation values suggests amplification of the Albian moisture deficit in the tropics and moisture surplus in the mid to high latitudes. The tropical moisture deficit represents an average heat loss of ???75 W/m2 at 10??N paleolatitude (at present, 21 W/m2). The increased precipitation at higher latitudes implies an average heat gain of ???83 W/m2 at 45??N (at present, 23 W/m2) and of 19 W/m2 at 75??N (at present, 4 W/m2). These estimates of increased poleward heat transfer by H2O vapor during the Albian may help to explain the reduced equator-to-pole temperature gradients. ?? 2004 Geological Society of America.

  2. Improving Latent and Sensible Heat Flux Estimates for the Atlantic Ocean (1988 99) by a Synthesis Approach(.

    NASA Astrophysics Data System (ADS)

    Yu, Lisan; Weller, Robert A.; Sun, Bomin

    2004-01-01

    A new daily latent and sensible flux product developed at the Woods Hole Oceanographic Institution (WHOI) with 1° × 1° resolution for the Atlantic Ocean (65°S 65°N) for the period from 1988 to 1999 was presented. The flux product was developed by using a variational objective analysis approach to obtain best estimates of the flux-related basic surface meteorological variables (e.g., wind speed, air humidity, air temperature, and sea surface temperature) through synthesizing satellite data and outputs of numerical weather prediction (NWP) models at the National Centers for Environmental Prediction (NCEP) and the European Centre for Medium-Range Weather Forecasts (ECMWF). The state-of-the-art bulk flux algorithm 2.6a, developed from the field experiments of the Coupled Ocean Atmosphere Response Experiment (COARE), was applied to compute the flux fields.The study focused on analyzing the mean field properties of the WHOI daily latent and sensible heat fluxes and their comparisons with the ship-based climatology from the Southampton Oceanography Centre (SOC) and NWP outputs. It is found that the WHOI yearly mean fluxes are consistent with the SOC climatology in both structure and amplitude, but the WHOI yearly mean basic variables are not always consistent with SOC; the better agreement in the fluxes is due to the effects of error compensation during variable combinations. Both ECMWF and NCEP Department of Energy (DOE) Atmospheric Model Intercomparison Project (AMIP) Reanalysis-2 (NCEP2) model data have larger turbulent heat loss (20 W m-2) than the WHOI product. Nevertheless, the WHOI fluxes agree well with the NCEP-2 Reanalysis fluxes in structure and the trend of year-to-year variations, but not with the ECMWF operational outputs; the latter have a few abrupt changes coinciding with the modifications in the model forecast analysis system. The degree of impact of the model changes on the basic variables is not as dramatic, a factor that justifies the inclusion

  3. Performance analysis of a latent heat storage system with phase change material for new designed solar collectors in greenhouse heating

    SciTech Connect

    Benli, Hueseyin; Durmus, Aydin

    2009-12-15

    The continuous increase in the level of greenhouse gas emissions and the rise in fuel prices are the main driving forces behind the efforts for more effectively utilize various sources of renewable energy. In many parts of the world, direct solar radiation is considered to be one of the most prospective sources of energy. In this study, the thermal performance of a phase change thermal storage unit is analyzed and discussed. The storage unit is a component of ten pieced solar air collectors heating system being developed for space heating of a greenhouse and charging of PCM. CaCl{sub 2}6H{sub 2}O was used as PCM in thermal energy storage with a melting temperature of 29 C. Hot air delivered by ten pieced solar air collector is passed through the PCM to charge the storage unit. The stored heat is utilized to heat ambient air before being admitted to a greenhouse. This study is based on experimental results of the PCM employed to analyze the transient thermal behavior of the storage unit during the charge and discharge periods. The proposed size of collectors integrated PCM provided about 18-23% of total daily thermal energy requirements of the greenhouse for 3-4 h, in comparison with the conventional heating device. (author)

  4. Solar passive ceiling system. Final report. [Passive solar heating system with venetian blind reflectors and latent heat storage in ceiling

    SciTech Connect

    Schneider, A.R.

    1980-01-01

    The construction of a 1200 square foot building, with full basement, built to be used as a branch library in a rural area is described. The primary heating source is a passive solar system consisting of a south facing window system. The system consists of: a set of windows located in the south facing wall only, composed of double glazed units; a set of reflectors mounted in each window which reflects sunlight up to the ceiling (the reflectors are similar to venetian blinds); a storage area in the ceiling which absorbs the heat from the reflected sunlight and stores it in foil salt pouches laid in the ceiling; and an automated curtain which automatically covers and uncovers the south facing window system. The system is totally passive and uses no blowers, pumps or other active types of heat distribution equipment. The building contains a basement which is normally not heated, and the north facing wall is bermed four feet high around the north side.

  5. Towards the development of latent heat storage electrodes for electroporation-based therapies

    NASA Astrophysics Data System (ADS)

    Arena, Christopher B.; Mahajan, Roop L.; Rylander, Marissa Nichole; Davalos, Rafael V.

    2012-08-01

    Phase change materials (PCMs) capable of storing a large amount of heat upon transitioning from the solid-to-liquid state have been widely used in the electronics and construction industries for mitigating temperature development. Here, we show that they are also beneficial for reducing the peak tissue temperature during electroporation-based therapies. A numerical model is developed of irreversible electroporation (IRE) performed with hollow needle electrodes filled with a PCM. Results indicate that this electrode design can be utilized to achieve large ablation volumes while reducing the probability for thermal damage.

  6. A field study of the effects of inhomogeneities of surface sensible and latent heat fluxes

    SciTech Connect

    Doran, J.C.; Barnes, F.J.; Coulter, R.L.; Crawford, T.L.

    1992-01-01

    In recent years, the problem of characterizing turbulent fluxes of heat, momentum, and moisture over inhomogeneous surfaces has received increasing attention. This issue is relevant to the performance of general circulation models (GCMs), in which a single grid element can encompass a variety of surface and topographical features. Although considerable progress has been made in describing the energy balance at a surface partially covered by vegetation, less is known about how to treat adjacent regions of sharply contrasting surface characteristics. One difficulty is the scarcity of suitable data sets with which to study the problem, particularly on scales of tens to hundreds of kilometers.

  7. Thermal Assessment of a Latent-Heat Energy Storage Module During Melting and Freezing for Solar Energy Applications

    NASA Astrophysics Data System (ADS)

    Ramos Archibold, Antonio

    Capital investment reduction, exergetic efficiency improvement and material compatibility issues have been identified as the primary techno-economic challenges associated, with the near-term development and deployment of thermal energy storage (TES) in commercial-scale concentrating solar power plants. Three TES techniques have gained attention in the solar energy research community as possible candidates to reduce the cost of solar-generated electricity, namely (1) sensible heat storage, (2) latent heat (tank filled with phase change materials (PCMs) or encapsulated PCMs packed in a vessel) and (3) thermochemical storage. Among these the PCM macro-encapsulation approach seems to be one of the most-promising methods because of its potential to develop more effective energy exchange, reduce the cost associated with the tank and increase the exergetic efficiency. However, the technological barriers to this approach arise from the encapsulation techniques used to create a durable capsule, as well as an assessment of the fundamental thermal energy transport mechanisms during the phase change. A comprehensive study of the energy exchange interactions and induced fluid flow during melting and solidification of a confined storage medium is reported in this investigation from a theoretical perspective. Emphasis has been placed on the thermal characterization of a single constituent storage module rather than an entire storage system, in order to, precisely capture the energy exchange contributions of all the fundamental heat transfer mechanisms during the phase change processes. Two-dimensional, axisymmetric, transient equations for mass, momentum and energy conservation have been solved numerically by the finite volume scheme. Initially, the interaction between conduction and natural convection energy transport modes, in the absence of thermal radiation, is investigated for solar power applications at temperatures (300--400°C). Later, participating thermal radiation

  8. An Empirical Orthogonal Function-Based Algorithm for Estimating Terrestrial Latent Heat Flux from Eddy Covariance, Meteorological and Satellite Observations.

    PubMed

    Feng, Fei; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Chen, Jiquan; Zhao, Xiang; Jia, Kun; Pintér, Krisztina; McCaughey, J Harry

    2016-01-01

    Accurate estimation of latent heat flux (LE) based on remote sensing data is critical in characterizing terrestrial ecosystems and modeling land surface processes. Many LE products were released during the past few decades, but their quality might not meet the requirements in terms of data consistency and estimation accuracy. Merging multiple algorithms could be an effective way to improve the quality of existing LE products. In this paper, we present a data integration method based on modified empirical orthogonal function (EOF) analysis to integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product (MOD16) and the Priestley-Taylor LE algorithm of Jet Propulsion Laboratory (PT-JPL) estimate. Twenty-two eddy covariance (EC) sites with LE observation were chosen to evaluate our algorithm, showing that the proposed EOF fusion method was capable of integrating the two satellite data sets with improved consistency and reduced uncertainties. Further efforts were needed to evaluate and improve the proposed algorithm at larger spatial scales and time periods, and over different land cover types. PMID:27472383

  9. An Empirical Orthogonal Function-Based Algorithm for Estimating Terrestrial Latent Heat Flux from Eddy Covariance, Meteorological and Satellite Observations

    PubMed Central

    Feng, Fei; Li, Xianglan; Yao, Yunjun; Liang, Shunlin; Chen, Jiquan; Zhao, Xiang; Jia, Kun; Pintér, Krisztina; McCaughey, J. Harry

    2016-01-01

    Accurate estimation of latent heat flux (LE) based on remote sensing data is critical in characterizing terrestrial ecosystems and modeling land surface processes. Many LE products were released during the past few decades, but their quality might not meet the requirements in terms of data consistency and estimation accuracy. Merging multiple algorithms could be an effective way to improve the quality of existing LE products. In this paper, we present a data integration method based on modified empirical orthogonal function (EOF) analysis to integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product (MOD16) and the Priestley-Taylor LE algorithm of Jet Propulsion Laboratory (PT-JPL) estimate. Twenty-two eddy covariance (EC) sites with LE observation were chosen to evaluate our algorithm, showing that the proposed EOF fusion method was capable of integrating the two satellite data sets with improved consistency and reduced uncertainties. Further efforts were needed to evaluate and improve the proposed algorithm at larger spatial scales and time periods, and over different land cover types. PMID:27472383

  10. Latent Heat Characteristics of Biobased Oleochemical Carbonates as Novel Phase Change Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oleochemical carbonates are biobased materials that were readily prepared through a carbonate interchange reaction between renewable C10-C18 fatty alcohols and dimethyl or diethyl carbonate in the presence of a catalyst. These carbonates have various commercial uses in cosmetic, fuel additive and l...

  11. An Empirically Derived Approach to the Latent Structure of the Adult Attachment Interview: Additional Convergent and Discriminant Validity Evidence

    PubMed Central

    Haydon, Katherine C.; Roisman, Glenn I.; Marks, Michael J.; Fraley, R. Chris

    2011-01-01

    Building on studies examining the latent structure of attachment-related individual differences as assessed by the Adult Attachment Interview (AAI) via Principal Components Analysis, the current report further explores the validity of four AAI dimensions reported by Haydon, Roisman, and Burt (in press): dismissing states of mind, preoccupied states of mind, and inferred negative experience with maternal and paternal caregivers. Study 1 reports evidence of distinctive cognitive correlates of dismissing v. preoccupied states of mind with reaction time in an attachment Stroop task and the valence of endorsed self-descriptors, respectively. Study 2 replicates prior meta-analytic findings of generally trivial convergence between state of mind dimensions and self-reported avoidance and anxiety (i.e., Roisman, Holland, et al., 2007). Study 3 contrastively demonstrates moderate empirical overlap between inferred experience—but not state of mind—AAI scales and self-reported avoidance and anxiety when the latter were assessed at the level of specific caregivers. Taken together, these findings add to accumulating evidence that an empirically-driven approach to scaling adults on AAI dimensions (Haydon et al., in press; Roisman et al., 2007) aids in identifying theoretically anticipated and distinctive affective, behavioral, and cognitive correlates of dismissing versus preoccupied states of mind. PMID:21838649

  12. Multiple solutions and numerical analysis to the dynamic and stationary models coupling a delayed energy balance model involving latent heat and discontinuous albedo with a deep ocean.

    PubMed

    Díaz, J I; Hidalgo, A; Tello, L

    2014-10-01

    We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge-Kutta total variation diminishing for time integration. PMID:25294969

  13. Multiple solutions and numerical analysis to the dynamic and stationary models coupling a delayed energy balance model involving latent heat and discontinuous albedo with a deep ocean

    PubMed Central

    Díaz, J. I.; Hidalgo, A.; Tello, L.

    2014-01-01

    We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge–Kutta total variation diminishing for time integration. PMID:25294969

  14. Estimating the daily course of Konza Prairie latent heat fluxes using a modified Tergra model

    NASA Technical Reports Server (NTRS)

    Hope, Allen S.

    1992-01-01

    Experimental tests of the Tergra-2 model are based on data collected under moderately wet to wet and very dry soil moisture conditions. Further testing of the model under intermediate soil moisture conditions is required and additional testing under very dry conditions may lead to modifications that make the model more suitable to water-stressed conditions. Combining the Tergra model with a soil evaporation routine should enhance the accuracy of the model and allow it to be employed in situations where vapor fluxes are not almost solely attributable to transpiration.

  15. Improvement of discharge characteristics of latent heat thermal energy storage unit by using carbon fibers

    SciTech Connect

    Fukai, Jun; Oishi, Akira; Kodama, Yoshikazu; Kanou, Makoto; Miyatake, Osamu

    1999-07-01

    Many phase change materials have unacceptably low thermal conductivities. Metal fins, metal honeycombs and metal matrices have been examined to enhance the thermal conductivity of the PCMs. This study proposed an enhancement technique using carbon fibers with high thermal conductivity. The thermal conductivity of the carbon fibers prepared in this study is 220 W/(m{center_dot}K). Paraffin wax (0.26 W/(m{center_dot}K) in solid phase) and Na{sub 2}SO{sub 4}{center_dot}10H{sub 2}O-mixture (0.8 W/(m{center_dot}K) in solid phase) were selected as heat storage media. The fibers were uniformly mixed with th PCM encapsulated in a cylindrical capsule. The effective thermal conductivities of the fibers/PCM composites were measured. Figure A-1 shows the ratio of the effective thermal conductivity of the composite (k{sub c}) to the thermal conductivity of the phase change material (k{sub m}). The figure demonstrates that the fibers essentially enhance the thermal conductivities of paraffin. For paraffin, there is little dependence of the effective thermal conductivity on the fiber length (L{sub f}). Though the k{sub c}/k{sub m} for Na{sub 2}SO{sub 4}{center_dot}10H{sub 2}O-mixture is lower than that of the paraffin wax, 2% fibers increase the thermal conductivity of the PCM by a factor of about three. This value is almost identical to the thermal conductivity of ice (2.2 W/(m{center_dot}K)). The effect of the carbon fibers on discharge characteristics of a thermal energy storage system was investigated. Capsules containing a carbon fibers/paraffin composite are packed into a thermal energy storage unit. The inlet fluid temperature (T{sub in})and the outlet fluid temperature (T{sub out}) were measured during the discharge process. Figure A-2 shows a typical result of the experiments. Remarkable effect of the fibers is observed after the outlet temperature reaches the phase change temperature ({approx}60 C). That is, the period where the outlet temperature is maintained near the

  16. Latent heat loss of dairy cows in an equatorial semi-arid environment

    NASA Astrophysics Data System (ADS)

    da Silva, Roberto Gomes; Maia, Alex Sandro Campos; de Macedo Costa, Leonardo Lelis; de Queiroz, João Paulo A. Fernandes

    2012-09-01

    The present study aimed to evaluate evaporative heat transfer of dairy cows bred in a hot semi-arid environment. Cutaneous ( E S) and respiratory ( E R) evaporation were measured (810 observations) in 177 purebred and crossbred Holstein cows from five herds located in the equatorial semi-arid region, and one herd in the subtropical region of Brazil. Rectal temperature ( T R), hair coat surface temperature ( T S) and respiratory rate ( F R) were also measured. Observations were made in the subtropical region from August to December, and in the semi-arid region from April to July. Measurements were done from 1100 to 1600 hours, after cows remained in a pen exposed to the sun. Environmental variables measured in the same locations as the animals were black globe temperature ( T G), air temperature ( T A), wind speed ( U), and partial air vapour pressure ( P V). Data were analysed by mixed models, using the least squares method. Results showed that average E S and E R were higher in the semi-arid region (117.2 W m-2 and 44.0 W m-2, respectively) than in the subtropical region (85.2 W m-2 and 30.2 W m-2, respectively). Herds and individual cows were significant effects ( P < 0.01) for all traits in the semi-arid region. Body parts did not affect T S and E S in the subtropical region, but was a significant effect ( P < 0.01) in the semi-arid region. The average flank T S (42.8°C) was higher than that of the neck and hindquarters (39.8°C and 41.6°C, respectively). Average E S was higher in the neck (133.3 W m-2) than in the flank (116.2 W m-2) and hindquarters (98.6 W m-2). Coat colour affected significantly both T S and E S ( P < 0.01). Black coats had higher T S and E S in the semi-arid region (41.7°C and 117.2 W m-2, respectively) than white coats (37.2°C and 106.7 W m-2, respectively). Rectal temperatures were almost the same in both subtropical and semi-arid regions. The results highlight the need for improved management methods specific for semi-arid regions.

  17. Estimation of Mesoscale Atmospheric Latent Heating Profiles from TRMM Rain Statistics Utilizing a Simple One-Dimensional Model

    NASA Technical Reports Server (NTRS)

    Iacovazzi, Robert A., Jr.; Prabhakara, C.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    In this study, a model is developed to estimate mesoscale-resolution atmospheric latent heating (ALH) profiles. It utilizes rain statistics deduced from Tropical Rainfall Measuring Mission (TRMM) data, and cloud vertical velocity profiles and regional surface thermodynamic climatologies derived from other available data sources. From several rain events observed over tropical ocean and land, ALH profiles retrieved by this model in convective rain regions reveal strong warming throughout most of the troposphere, while in stratiform rain regions they usually show slight cooling below the freezing level and significant warming above. The mesoscale-average, or total, ALH profiles reveal a dominant stratiform character, because stratiform rain areas are usually much larger than convective rain areas. Sensitivity tests of the model show that total ALH at a given tropospheric level varies by less than +/- 10 % when convective and stratiform rain rates and mesoscale fractional rain areas are perturbed individually by 1 15 %. This is also found when the non-uniform convective vertical velocity profiles are replaced by one that is uniform. Larger variability of the total ALH profiles arises when climatological ocean- and land-surface temperatures (water vapor mixing ratios) are independently perturbed by +/- 1.0 K (+/- 5 %) and +/- 5.0 K (+/- 15 %), respectively. At a given tropospheric level, such perturbations can cause a +/- 25 % variation of total ALH over ocean, and a factor-of-two sensitivity over land. This sensitivity is reduced substantially if perturbations of surface thermodynamic variables do not change surface relative humidity, or are not extended throughout the entire model evaporation layer. The ALH profiles retrieved in this study agree qualitatively with tropical total diabatic heating profiles deduced in earlier studies. Also, from January and July 1999 ALH-profile climatologies generated separately with TRMM Microwave Imager and Precipitation Radar rain

  18. Validation of HOAPS and ERA Interim latent heat fluxes against parameterizations applied to RV Polarstern data for 1995-1997

    NASA Astrophysics Data System (ADS)

    Bumke, Karl; Kinzel, Julian

    2014-05-01

    Latent heat fluxes (LHF) represent a crucial component of the global energy cycle. As LHF provide one of the upper boundary conditions for the oceanic component of coupled atmosphere-ocean circulation models, it is desirable to rely on one consistent LHF data source with sufficient spatial and temporal resolution. Remotely sensed LHF, particularly the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS) climatology, are considered to fulfil this criterion. However, the validity of HOAPS LHF needs to be investigated to assess its potential of reliably representing an essential part of the global freshwater cycle. Within this study, a validation of HOAPS-3.0-based LHF at pixel-level resolution for 1995-1997 is performed over the Atlantic basin. A recently developed bulk flux algorithm termed OCEANET (Bumke et al., 2013), derived from turbulence measurements onboard R/V Polarstern by inertial dissipation method, is applied to hourly bulk measurements obtained during 19 Atlantic cruises of R/V Polarstern. Its LHF output serves as the in-situ validation data source, which is supplemented by ERA-Interim reanalysis data. By means of the nearest-neighbor approach, a collocation of HOAPS- to OCEANET- and ERA-Interim data is carried out. Bias analyses suggest that HOAPS LHF are on average significantly underestimated compared to OCEANET and ERA-Interim (-8 W/m²). A sub-division into latitudinal bands resolves absolute biases exceeding -20 W/m² in the tropics. As the minor differences between the HOAPS- and OCEANET-based transfer coefficients lie within the uncertainty range inherent to bulk flux parameterizations, it is suggested that the significant LHF deviations for the most part arise from deviations among the bulk input variables. Investigations of bulk input parameters reveal that the observed negative LHF biases within the HOAPS record are mainly associated with an overrepresentation of air specific humidity for 20°S - 60°N. Latitudinal

  19. Array-Based Transcript Profiling and Limiting-Dilution Reverse Transcription-PCR Analysis Identify Additional Latent Genes in Kaposi's Sarcoma-Associated Herpesvirus▿ †

    PubMed Central

    Chandriani, Sanjay; Ganem, Don

    2010-01-01

    Kaposi's sarcoma-associated herpesvirus (KSHV) is a B-lymphotropic herpesvirus strongly linked to both lymphoproliferative diseases and Kaposi's sarcoma. The viral latency program of KSHV is central to persistent infection and plays important roles in the pathogenesis of KSHV-related tumors. Up to six polypeptides and 18 microRNAs are known to be expressed in latency, but it is unclear if all major latency genes have been identified. Here, we have employed array-based transcript profiling and limiting-dilution reverse transcription-PCR (RT-PCR) methodologies to explore this issue in several KSHV-infected cell lines. Our results show that RNAs encoding the K1 protein are found at low levels in most latently infected cell lines. The gene encoding v-IL-6 is also expressed as a latent transcript in some contexts. Both genes encode powerful signaling molecules with particular relevance to B cell biology: K1 mimics signaling through the B cell receptor, and v-IL-6 promotes B cell survival. These data resolve earlier controversies about K1 and v-IL-6 expression and indicate that, in addition to core latency genes, some transcripts can be expressed in KSHV latency in a context-dependent manner. PMID:20219929

  20. Evaluation of heat shock proteins for discriminating between latent tuberculosis infection and active tuberculosis: A preliminary report.

    PubMed

    Shekhawat, Seema D; Purohit, Hemant J; Taori, Girdhar M; Daginawala, Hatim F; Kashyap, Rajpal S

    2016-01-01

    The diagnosis of a latent tuberculosis infection (LTBI) is of the utmost concern. The available tests, the tuberculin skin test (TST) and the Quantiferon-TB Gold test (QFT-G) cannot discriminate between active TB and LTBI. Therefore, the aim of the study is to identify new biomarkers that can discriminate between active TB and LTBI and can also assess the risk of the individual developing active TB. In total, 55 blood samples were collected, of which 10 samples were from the active TB infection group, 10 were from the high-risk exposure group, 23 were from the low-risk exposure group, and 12 were from healthy controls living in a non-TB endemic area. A panel of heat shock proteins (Hsps), including host Hsp25, Hsp60, Hsp70, and Hsp90 and Mycobacterium tuberculosis (MTB) Hsp16, were evaluated in all of the collected samples using ELISA. The levels of the host Hsp(s) (Hsp25, Hsp60, Hsp70 and Hsp90) and MTB Hsp16 were significantly (p<0.05) elevated in the active TB group compared to the high-risk exposure group, the low-risk exposure group and the control group. Notably, the levels of the same panel of Hsp(s) were elevated in the high-risk exposure group compared to the low-risk exposure group. On follow-up, out of the 10 high-risk exposure participants, 3 converted into active TB, indicating that this group has the highest risk of developing TB. Thus, the evaluated panel of Hsp(s) can discriminate between LTBI and active TB. They can also identify individuals who are at the highest risk of developing active TB. Because they can be rapidly detected, Hsp(s) have an edge over the existing diagnostic tools for LTBI. The evaluation of these proteins will be useful in designing better diagnostic methods for LTBI. PMID:26300163

  1. Comparison between global latent heat flux computed from multisensor (SSM/I and AVHRR) and from in situ data

    NASA Technical Reports Server (NTRS)

    Jourdan, Didier; Gautier, Catherine

    1995-01-01

    Comprehensive Ocean-Atmosphere Data Set (COADS) and satellite-derived parameters are input to a similarity theory-based model and treated in completely equivalent ways to compute global latent heat flux (LHF). In order to compute LHF exclusively from satellite measurements, an empirical relationship (Q-W relationship) is used to compute the air mixing ratio from Special Sensor Microwave/Imager (SSM/I) precipitable water W and a new one is derived to compute the air temperature also from retrieved W(T-W relationship). First analyses indicate that in situ and satellite LHF computations compare within 40%, but systematic errors increase the differences up to 100% in some regions. By investigating more closely the origin of the discrepancies, the spatial sampling of ship reports has been found to be an important source of error in the observed differences. When the number of in situ data records increases (more than 20 per month), the agreement is about 50 W/sq m rms (40 W/sq m rms for multiyear averages). Limitations of both empirical relationships and W retrieval errors strongly affect the LHF computation. Systematic LHF overestimation occurs in strong subsidence regions and LHF underestimation occurs within surface convergence zones and over oceanic upwelling areas. The analysis of time series of the different parameters in these regions confirms that systematic LHF discrepancies are negatively correlated with the differences between COADS and satellite-derived values of the air mixing ratio and air temperature. To reduce the systematic differences in satellite-derived LHF, a preliminary ship-satellite blending procedure has been developed for the air mixing ratio and air temperature.

  2. The Contribution of Englacial Latent Heat Transfer to Seaward Ice Flux from Regions of Convergent and Divergent Ice Flow in Western Greenland

    NASA Astrophysics Data System (ADS)

    Poinar, K.; Joughin, I. R.

    2014-12-01

    Glacial meltwater can refreeze within firn and crevasses, warming the ice through latent heat transfer. The consequent softening of the ice has been identified as a potential destabilization mechanism for the Greenland Ice Sheet, which would flow more quickly seaward with lower viscosity. We calculate the effect of meltwater refreezing within firn and englacial features on ice temperature and viscosity in two contrasting areas of western Greenland: Jakobshavn Isbrae, a convergent, fast-flowing outlet glacier, and the Pakitsoq area (Swiss Camp) directly to its north, a "dead zone" experiencing slow, divergent flow because of its location between two outlet glaciers. We explore how much refreezing affects the seaward velocity of ice in each location by comparing our modeled temperature profiles to borehole data. Pakitsoq ice shows significant englacial latent heat transfer, or cryo-hydrologic warming, while the ice in Jakobshavn has warmed largely due to percolation within the firn. We find that the Pakitsoq region is rather unique in western Greenland because of the long residence time of the ice in the ablation zone (800 years) there; ice flowing through Jakobshavn, by contrast, spends only 20 years in the ablation zone, not enough time for deep, diffusive englacial warming to occur. Examination of the velocity field of the ice sheet indicates that 70% of the ice flux through western Greenland spends insufficient time (200 years or less) in the ablation zone to produce significant englacial warming. Thus, the effects of englacial latent heat transfer may be fairly limited to regions of divergent flow such as Pakitsoq. Ice loss in these regions, which tend to be land-terminating, is dominated by surface melt rather than seaward ice motion, further suggesting that englacial heat transfer may have a lesser effect on the stability of the ice sheet than previously supposed.

  3. Effect of fetch length on latent heat flux data accuracy calculated by Bowen ratio energy balance method

    NASA Astrophysics Data System (ADS)

    Pozníková, Gabriela; Fischer, Milan; Trnka, Miroslav; Orság, Matěj; Kučera, Jiří; Žalud, Zdeněk

    2013-04-01

    Bowen ratio energy balance (BREB) is one of the most widely used indirect methods for deriving latent heat (LE) and sensible heat fluxes. The BREB technique relies on net radiation, ground heat flux, and air temperature and humidity gradients measurements. Whilst the first two mentioned can be practically considered as point measurements, the source area of temperature and humidity gradients is at least one order of magnitudes larger. Therefore, the horizontal, homogeneous and extensive area is necessary prerequisite for correct flux determination by BREB method. An ideal fetch for BREB has been reported to be within 10 to 200 times the height of upper measuring level above zero plane displacement. This broad range is a result of different atmospheric stratifications and surface roughness, but the fetch to height ratio 100:1 has become generally acknowledged as a rule of thumb. In this study, data from four different BREB systems above various covers (two poplar plantations, grassland and turf grass field) will be used to calculate and analyse LE for different fetches. Data were recorded in Domanínek near Bystřice nad Pernštejnem in Czech-Moravian highlands where two BREB systems have measured above poplar plantation and turf grass since summer 2008 until present and two more systems have been placed above grassland and another poplar plantation at the beginning of 2011 and have measured until present time. During the measurements changing wind direction limited the fetch of particular BREB systems on the sites. That is why LE calculated for particular fetch lengths will be split into three categories - fetch classes ("good", "medium", and "bad") according to prevailing wind direction and corresponding fetch. These categories will be delimited using the simple footprint model. Fetches with more than 75% of the measured entities coming from the area of interest will be considered as the "good" ones. The "medium" class will contain fetches with 50-75% of the flux

  4. Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations

    NASA Astrophysics Data System (ADS)

    Martin, J.; Reichstein, M.

    2012-12-01

    We upscaled FLUXNET observations of carbon dioxide, water and energy fluxes to the global scale using the machine learning technique, Model Tree Ensembles (MTE). We trained MTE to predict site-level gross primary productivity (GPP), terrestrial ecosystem respiration (TER), net ecosystem exchange (NEE), latent energy (LE), and sensible heat (H) based on remote sensing indices, climate and meteorological data, and information on land use. We applied the trained MTEs to generate global flux fields at a 0.5° x 0.5o spatial resolution and a monthly temporal resolution from 1982-2008. Cross-validation analyses revealed good performance of MTE in predicting among-site flux variability with modeling efficiencies (MEf) between 0.64 and 0.84, except for NEE (MEf = 0.32). Performance was also good for predicting seasonal patterns (MEf between 0.84 and 0.89, except for NEE (0.64)). By comparison, predictions of monthly anomalies were weak. Our products are increasingly used to evaluate global land surface models. However, depending on the flux of interest (e.g. gross primary production, terrestrial ecosystem respiration, net ecosystem exchange, evapotranspiration) and the pattern of interest (mean annual map, seasonal cycles, interannual variability, trends) the robustness and uncertainty of these products varies considerably. To avoid pitfalls, this talk also aims at providing an overview of uncertainties associated with these products, and to provide recommendations on the usage for land surface model evaluations. Finally, we present FLUXCOM - an ongoing activity that aims at generating an ensemble of data-driven FLUXNET based products based on diverse approaches.

  5. The Simulation of the Opposing Fluxes of Latent Heat and CO2 over Various Land-Use Types: Coupling a Gas Exchange Model to a Mesoscale Atmospheric Model

    NASA Astrophysics Data System (ADS)

    Reyers, Mark; Krüger, Andreas; Werner, Christiane; Pinto, Joaquim G.; Zacharias, Stefan; Kerschgens, Michael

    2011-04-01

    A mesoscale meteorological model (FOOT3DK) is coupled with a gas exchange model to simulate surface fluxes of CO2 and H2O under field conditions. The gas exchange model consists of a C3 single leaf photosynthesis sub-model and an extended big leaf (sun/shade) sub-model that divides the canopy into sunlit and shaded fractions. Simulated CO2 fluxes of the stand-alone version of the gas exchange model correspond well to eddy-covariance measurements at a test site in a rural area in the west of Germany. The coupled FOOT3DK/gas exchange model is validated for the diurnal cycle at singular grid points, and delivers realistic fluxes with respect to their order of magnitude and to the general daily course. Compared to the Jarvis-based big leaf scheme, simulations of latent heat fluxes with a photosynthesis-based scheme for stomatal conductance are more realistic. As expected, flux averages are strongly influenced by the underlying land cover. While the simulated net ecosystem exchange is highly correlated with leaf area index, this correlation is much weaker for the latent heat flux. Photosynthetic CO2 uptake is associated with transpirational water loss via the stomata, and the resulting opposing surface fluxes of CO2 and H2O are reproduced with the model approach. Over vegetated surfaces it is shown that the coupling of a photosynthesis-based gas exchange model with the land-surface scheme of a mesoscale model results in more realistic simulated latent heat fluxes.

  6. The Linkages between Latent Heating to Cloud and Precipitation Profiles in WRF Model Simulations of Typhoon Chaba (2004)

    NASA Astrophysics Data System (ADS)

    Li, R.; Guo, J.; Fu, Y.

    2013-12-01

    Abstract Despite its fundamental role in driving the genesis and evolution of tropical cyclones as well as large scale atmospheric waves including ENSO, monsoon and MJO, the spatial and temporal distribution of latent heating (LH) remains one of the largest uncertainties in weather and climate modeling. With the rapid advance in satellite active sensors such as the TRMM PR, CloudSat CPR and the coming GPM DPR, more comprehensive and reliable observations of cloud and precipitation profiles provide great opportunities to improve the accuracy of estimating LH from space. However, LH is released through the 'processes' of water phase change in the atmosphere while satellite observations provide the estimation of the 'state' of cloud and precipitation, the physical linkages between LH to cloud and precipitation profiles are required to develop next generation physical-based LH algorithms. In this study, we examined the relationships among the condensations heating (LHcon), cloud water content (CWC) and rain rate (Rr) in the Weather Research and Forecasting (WRF) model simulations of typhoon Chaba (2004) under five different microphysical schemes including Purdue Lin, Goddard Cumulus Ensemble Model, WSM6, Thompson et al. and Morrison et al. 2-Moment schemes, respectively. Firstly, the LHcon has the highest correlations (~ 0.85 for convective rains) with the term of Rr αCWC which represents the rate of rain formation from auto-conversion and accretion. Although cloud and precipitation, as the ultimate outcomes of water vapor condensation process, also have inherent correlations to LHcon, the connections are significantly weaker than the LHcon - Rr αCWC linkages. Such findings are valid in all selected microphysical schemes in both 2-D CRM (Min et al 2013; Li et al 2013) and 3-D WRF simulations. Secondly, the sensitivity of maximum explained variances of LHcon by Rr αCWC to different microphysical schemes are relatively low. The associated optimal exponential of α is

  7. Nitrogen Flow in a Nanonozzle with Heat Addition

    NASA Astrophysics Data System (ADS)

    Averkin, Sergey; Zhang, Zetian; Gatsonis, Nikolaos

    2012-11-01

    The nitrogen flow in conical nanonozzles at atmospheric pressures are investigated using a three-dimensional unstructured direct simulation Monte Carlo (U3DSMC) method. The DSMC simulations are performed in computational domains that feature the plenum, the nanonozzle region and the external plume expansion region. The inlet and outlet boundaries are modeled by the Kinetic-Moment (KM) boundary conditions method. This methodology is based on the local one dimensional inviscid (LODI) formulation used in compressible (continuous) flow computations. The cross section for elastic collisions is based on the variable hard sphere (VHS) model. The Larsen-Borgnakke (L-B) model is used to simulate the exchange of the internal energy in the collision pair. Solid surfaces are modeled as being either diffuse or specularly reflecting. The effects of Knudsen number, aspect ratio, and nanonozzle scale on the heat transfer are investigating by ranging the throat diameters from 100-500 nm, exit diameter from 100-1000 nm, stagnation pressure from 1-10atm, and wall temperature from 300K-500K. Finite backpressure and vacuum conditions are considered. Macroscopic flow variables are obtained and compared with continuum predictions in order to elucidate the impacts of nanoscale.

  8. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  9. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  10. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  11. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  12. Acidization of a Direct Heat Hydrothermal Well and its Potential in Developing Additional Direct Heat Projects

    SciTech Connect

    Dolenc, M.R.; Strawn, J. A.; Prestwich, S.M.

    1981-01-01

    A matrix acid treatment on a limestone formation in a low temperature hydrothermal production well in South Dakota has resulted in a 40% increase in heat (BTU) available for use in space heating a hospital. The results of this experimental treatment on the Madison Limestone suggest a significant potential may exist for similar applications, particularly throughout the western United States. This paper presents the results of the acid treatment, suggests other possible areas for similar application, and analyzes the economics for successful treatments.

  13. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosols on precipitation in organized deep convective systems

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-06-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updrafts/downdrafts in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  14. Development of latent heat reservoirs - New reservoir materials and concepts for solar energy, rational energy use and space flight applications

    NASA Astrophysics Data System (ADS)

    Glueck, Andreas; Krause, Siegfried; Lindner, Friedrich; Staehle, Hans-Joerg; Tamme, Rainer

    1991-11-01

    New kinds of thermal storage devices with greater heat density using unconventional materials are discussed. Attention is given to devices using salt hydrates and devices using graphite. Devices with direct heat exchange are examined. The applications of these thermal reservoirs to space flight are considered.

  15. Heat acclimation improves intermittent sprinting in the heat but additional pre-cooling offers no further ergogenic effect.

    PubMed

    Castle, Paul; Mackenzie, Richard W; Maxwell, Neil; Webborn, Anthony D J; Watt, Peter W

    2011-08-01

    The aim of this study was to determine the effect of 10 days of heat acclimation with and without pre-cooling on intermittent sprint exercise performance in the heat. Eight males completed three intermittent cycling sprint protocols before and after 10 days of heat acclimation. Before acclimation, one sprint protocol was conducted in control conditions (21.8 ± 2.2°C, 42.8 ± 6.7% relative humidity) and two sprint protocols in hot, humid conditions (33.3 ± 0.6°C, 52.2 ± 6.8% relative humidity) in a randomized order. One hot, humid condition was preceded by 20 min of thigh pre-cooling with ice packs (-16.2 ± 4.5°C). After heat acclimation, the two hot, humid sprint protocols were repeated. Before heat acclimation, peak power output declined in the heat (P < 0.05) but pre-cooling prevented this. Ten days of heat acclimation reduced resting rectal temperature from 37.8 ± 0.3°C to 37.4 ± 0.3°C (P < 0.01). When acclimated, peak power output increased by ∼2% (P < 0.05, main effect) and no reductions in individual sprint peak power output were observed. Additional pre-cooling offered no further ergogenic effect. Unacclimated athletes competing in the heat should pre-cool to prevent reductions in peak power output, but heat acclimate for an increased peak power output. PMID:21777052

  16. Heat transfer characteristics for some coolant additives used for water cooled engines

    SciTech Connect

    Abou-Ziyan, H.Z.; Helali, A.H.B.

    1996-12-31

    Engine coolants contain certain additives to prevent engine overheating or coolant freezing in cold environments. Coolants, also, contain corrosion and rust inhibitors, among other additives. As most engines are using engine cooling solutions, it is of interest to evaluate the effect of engine coolants on the boiling heat transfer coefficient. This has its direct impact on radiator size and environment. This paper describes the apparatus and the measurement techniques. Also, it presents the obtained boiling heat transfer results at different parameters. Three types of engine coolants and their mixtures in distilled water are evaluated, under sub-cooled and saturated boiling conditions. A profound effect of the presence of additives in the coolant, on heat transfer, was clear since changes of heat transfer for different coolants were likely to occur. The results showed that up to 180% improvement of boiling heat transfer coefficient is experienced with some types of coolants. However, at certain concentrations other coolants provide deterioration or not enhancement in the boiling heat transfer characteristics. This investigation proved that there are limitations, which are to be taken into consideration, for the composition of engine coolants in different environments. In warm climates, ethylene glycol should be kept at the minimum concentration required for dissolving other components, whereas borax is beneficial to the enhancement of the heat transfer characteristics.

  17. The effect of latent heat release on synoptic-to-planetary wave interactions and its implication for satellite observations: Theoretical modeling

    NASA Technical Reports Server (NTRS)

    Branscome, Lee E.; Bleck, Rainer; Obrien, Enda

    1990-01-01

    The project objectives are to develop process models to investigate the interaction of planetary and synoptic-scale waves including the effects of latent heat release (precipitation), nonlinear dynamics, physical and boundary-layer processes, and large-scale topography; to determine the importance of latent heat release for temporal variability and time-mean behavior of planetary and synoptic-scale waves; to compare the model results with available observations of planetary and synoptic wave variability; and to assess the implications of the results for monitoring precipitation in oceanic-storm tracks by satellite observing systems. Researchers have utilized two different models for this project: a two-level quasi-geostrophic model to study intraseasonal variability, anomalous circulations and the seasonal cycle, and a 10-level, multi-wave primitive equation model to validate the two-level Q-G model and examine effects of convection, surface processes, and spherical geometry. It explicitly resolves several planetary and synoptic waves and includes specific humidity (as a predicted variable), moist convection, and large-scale precipitation. In the past year researchers have concentrated on experiments with the multi-level primitive equation model. The dynamical part of that model is similar to the spectral model used by the National Meteorological Center for medium-range forecasts. The model includes parameterizations of large-scale condensation and moist convection. To test the validity of results regarding the influence of convective precipitation, researchers can use either one of two different convective schemes in the model, a Kuo convective scheme or a modified Arakawa-Schubert scheme which includes downdrafts. By choosing one or the other scheme, they can evaluate the impact of the convective parameterization on the circulation. In the past year researchers performed a variety of initial-value experiments with the primitive-equation model. Using initial

  18. Thermal energy storage – overview and specific insight into nitrate salts for sensible and latent heat storage

    PubMed Central

    Bauer, Thomas; Martin, Claudia; Eck, Markus; Wörner, Antje

    2015-01-01

    Summary Thermal energy storage (TES) is capable to reduce the demand of conventional energy sources for two reasons: First, they prevent the mismatch between the energy supply and the power demand when generating electricity from renewable energy sources. Second, utilization of waste heat in industrial processes by thermal energy storage reduces the final energy consumption. This review focuses mainly on material aspects of alkali nitrate salts. They include thermal properties, thermal decomposition processes as well as a new method to develop optimized salt systems. PMID:26199853

  19. Airborne flux measurements of CO{sub 2}, sensible, and latent heat over the Hudson Bay lowland

    SciTech Connect

    Desjardins, R.L.; Hayhoe, H.N.; MacPherson, J.I.; Schuepp, P.H.

    1994-01-20

    This article describes the results of aerial surveys conducted in 1990 over the Hudson Bay Lowland as part of the Northern Wetlands Study by the National Research Council of Ottawa, Canada. Two aerial runs of approximately 100 kilometers in length were completed from James Bay to the Kinosheo Lake area. Atmospheric research aircraft was used to measure the spatial and temporal variations in carbon dioxide, water, and sensible heat fluxes over the wetlands areas. The data collected as part of this study and interpretation of the results are presented in this paper. 27 refs., 10 figs., 4 tabs.

  20. Proper use of sludge-control additives in residential heating oil systems

    SciTech Connect

    Tatnall, R.E.

    1995-04-01

    Discussed are various aspects of heating oil `sludge`: How it forms, typical problems it causes, how sludge-control additives work, what should be expected of them, and what happens in a contaminated system when such additives are used. Test results from laboratory and field experiments demonstrate that performance of commercially available additives varies greatly. The concept of `end-of-the-line` treatment is described and compared with bulk fuel treatment. A procedure is described whereby a retailer can test additives himself, and thus determine just what those additives will or will not do for his business. Finally, the economics of an effective treatment program are outlined.

  1. HEAT: High accuracy extrapolated ab initio thermochemistry. III. Additional improvements and overview.

    SciTech Connect

    Harding, M. E.; Vazquez, J.; Ruscic, B.; Wilson, A. K.; Gauss, J.; Stanton, J. F.; Chemical Sciences and Engineering Division; Univ. t Mainz; The Univ. of Texas; Univ. of North Texas

    2008-01-01

    Effects of increased basis-set size as well as a correlated treatment of the diagonal Born-Oppenheimer approximation are studied within the context of the high-accuracy extrapolated ab initio thermochemistry (HEAT) theoretical model chemistry. It is found that the addition of these ostensible improvements does little to increase the overall accuracy of HEAT for the determination of molecular atomization energies. Fortuitous cancellation of high-level effects is shown to give the overall HEAT strategy an accuracy that is, in fact, higher than most of its individual components. In addition, the issue of core-valence electron correlation separation is explored; it is found that approximate additive treatments of the two effects have limitations that are significant in the realm of <1 kJ mol{sup -1} theoretical thermochemistry.

  2. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  3. Manifest and Latent Variates

    ERIC Educational Resources Information Center

    Maraun, Michael D.; Halpin, Peter F.

    2008-01-01

    The clue to what latent variable models are, and to a workable account of the basis for the traditional manifest/latent variable distinction, lies in a reconsideration of the indeterminacy property of linear factor structures. In this article, the authors contend that latent variable models are not detectors of unobservable latent structures,…

  4. Investigation of the stability of paraffin-exfoliated graphite nanoplatelet composites for latent heat thermal storage systems

    SciTech Connect

    Abdelaziz, Omar; Mallow, Anne; Graham, Samuel; Kalaitzidou, Kyriaki

    2012-01-01

    Organic materials, such as paraffin wax, are sought as stable and environmentally friendly phase change materials (PCM) for thermal energy storage, but they suffer from low thermal conductivity which limits the rate at which thermal energy flows into and out of the material. A common method to improve the PCM thermal behavior is through loading with high thermal conductivity particulate fillers. However, the stability of these composites in the molten state is a concern as settling of the fillers will change the effective thermal conductivity. In this work, we investigate the stability of wax loaded with exfoliated graphite nanoplatelets either of 1 m (xGnP-1) or 15 m (xGnP-15) diameter. The effect of dispersants, oxidation of the wax, viscosity of the wax, mixing time, and hydrocarbon chain length on stability is reported. It was found that the addition of octadecylphosphonic acid (ODPA) is an effective dispersant for xGnP in paraffin and microcrystalline wax. In addition, mixing time, viscosity, and oxidation of the wax influence stability in the molten state. Overall, it was found that a mixing time of 24 hours for xGnP-15 along with ODPA mixed in a high viscosity, oxidized microcrystalline wax results in composite PCM systems with the greatest stability determined at 80 C in the molten state.

  5. Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor

    NASA Technical Reports Server (NTRS)

    Wilson, Scott D.; Reid, Terry V.; Schifer, Nicholas A.; Briggs, Maxwell H.

    2012-01-01

    The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. Microporous bulk insulation is used in the ground support test hardware to minimize the loss of thermal energy from the electric heat source to the environment. The insulation package is characterized before operation to predict how much heat will be absorbed by the convertor and how much will be lost to the environment during operation. In an effort to validate these predictions, numerous tasks have been performed, which provided a more accurate value for net heat input into the ASCs. This test and modeling effort included: (a) making thermophysical property measurements of test setup materials to provide inputs to the numerical models, (b) acquiring additional test data that was collected during convertor tests to provide numerical models with temperature profiles of the test setup via thermocouple and infrared measurements, (c) using multidimensional numerical models (computational fluid dynamics code) to predict net heat input of an operating convertor, and (d) using validation test hardware to provide direct comparison of numerical results and validate the multidimensional numerical models used to predict convertor net heat input. This effort produced high fidelity ASC net heat input predictions, which were successfully validated using

  6. Evaluation of the low temperature heat exchanger fouling problem. Results of studies on soot production and condensing system fouling. [Recovery of latent heat of vaporization of moisture

    SciTech Connect

    Butcher, T.; Celebi, Y.; Piraino, M.

    1984-06-01

    The development of condensing heat exchangers for oil-fired heating equipment would yield a significant improvement in thermal efficiency. Soot production by oil burners, however, could lead to serious fouling problems in these systems. The objectives of this study were to investigate the causes of fouling in oil-fired condensing systems and to evaluate the need for the development of advanced oil burners. Tests were done to evaluate the effect of operating conditions on start-up and shutdown smoke production in both noncondensing and condensing furnaces. Modern retention head burners which are commonly used in the US were included as well as one European burner with some different design features. These features included the head design, a fuel shut-off in the nozzle tip, and nozzle heating. This burner was found to produce less smoke on start-up and shutdown than the common US burner. Fouling studies were done on both types of burners under cyclic conditions with relatively low excess air (10% CO/sub 2/) and continuous induced draft. Soot deposition did not cause any change in system thermal performance although soot deposition was heavier than would be expected with a noncondensing system. Tests were also done on the effects of fuel quality on soot production. Measurement techniques for soot included the common Bacharach smoke spot test, optical opacity, and filtration (EPA method 5). 27 refs., 69 figs., 18 tabs.

  7. Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Farjam, Aslan; Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-10-01

    In this work, aluminum and aluminum-alumina powder mixtures were used to produce pyramidal fin arrays on aluminum substrates using cold spray as an additive manufacturing process. Using aluminum-alumina mixtures instead of pure aluminum powder could be seen as a cost-effective measure, preventing nozzle clogging or the need to use expensive polymer nozzles that wear out rapidly during cold spray. The fin geometries that were produced were observed using a 3D digital microscope to determine the flow passages width and fins' geometric details. Heat transfer and pressure drop tests were carried out using different ranges of appropriate Reynolds numbers for the sought commercial application to compare each fin array and determine the effect of alumina content. It was found that the presence of alumina reduces the fins' performance when compared to pure aluminum fins but that they were still outperforming traditional fins. Numerical simulations were performed to model the fin arrays and were used to predict the pressure loss in the fin array and compare these results with experimental values. The numerical model opens up new avenues in predicting different applicable operating conditions and other possible fin shapes using the same fin composition, instead of performing costly and time-consuming experiments.

  8. Improved superconducting properties of melt-textured Nd123 by additional heat treatment

    NASA Astrophysics Data System (ADS)

    Chikumoto, N.; Yoshioka, J.; Murakami, M.

    1997-02-01

    We have investigated the effect of additional heat-treatment on the superconducting transition and the flux pinning properties of NdBaCuO melt-textured in air. After the heat-treatment at high temperatures, >900°C, under low oxygen partial pressure, P(O 2) = 0.001 atm, the superconducting transition became sharper accompanied by an increase of Jc. However, the increase of Jc was very small and the secondary peak effect commonly observed in NdBaCuO melt textured in low P(O 2) could not be observed. Transmission electron microscopic observations and energy dispersive X-ray analyses show that the spatial variation of the Nd/Ba ratio is reduced after high-temperature heat-treatment, which indicates that an improvement in Tc and Jc is attributed to a suppression of Nd substitution on the Ba site.

  9. Additive Manufacturing for Cost Efficient Production of Compact Ceramic Heat Exchangers and Recuperators

    SciTech Connect

    Shulman, Holly; Ross, Nicole

    2015-10-30

    An additive manufacture technique known as laminated object manufacturing (LOM) was used to fabricate compact ceramic heat exchanger prototypes. LOM uses precision CO2 laser cutting of ceramic green tapes, which are then precision stacked to build a 3D object with fine internal features. Modeling was used to develop prototype designs and predict the thermal response, stress, and efficiency in the ceramic heat exchangers. Build testing and materials analyses were used to provide feedback for the design selection. During this development process, laminated object manufacturing protocols were established. This included laser optimization, strategies for fine feature integrity, lamination fluid control, green handling, and firing profile. Three full size prototypes were fabricated using two different designs. One prototype was selected for performance testing. During testing, cross talk leakage prevented the application of a high pressure differential, however, the prototype was successful at withstanding the high temperature operating conditions (1300 °F). In addition, analysis showed that the bulk of the part did not have cracks or leakage issues. This led to the development of a module method for next generation LOM heat exchangers. A scale-up cost analysis showed that given a purpose built LOM system, these ceramic heat exchangers would be affordable for the applications.

  10. Modeled heating and surface erosion comparing motile (gas borne) and stationary (surface coating) inert particle additives

    SciTech Connect

    Buckingham, A.C.; Siekhaus, W.J.

    1982-09-27

    The unsteady, non-similar, chemically reactive, turbulent boundary layer equations are modified for gas plus dispersed solid particle mixtures, for gas phase turbulent combustion reactions and for heterogeneous gas-solid surface erosive reactions. The exterior (ballistic core) edge boundary conditions for the solutions are modified to include dispersed particle influences on core propellant combustion-generated turbulence levels, combustion reactants and products, and reaction-induced, non-isentropic mixture states. The wall surface (in this study it is always steel) is considered either bare or coated with a fixed particle coating which is conceptually non-reactive, insulative, and non-ablative. Two families of solutions are compared. These correspond to: (1) consideration of gas-borne, free-slip, almost spontaneously mobile (motile) solid particle additives which influence the turbulent heat transfer at the uncoated steel surface and, in contrast, (2) consideration of particle-free, gas phase turbulent heat transfer to the insulated surface coated by stationary particles. Significant differences in erosive heat transfer are found in comparing the two families of solutions over a substantial range of interior ballistic flow conditions. The most effective influences on reducing erosive heat transfer appear to favor mobile, gas-borne particle additives.

  11. Model Scramjet Inlet Unstart Induced by Mass Addition and Heat Release

    NASA Astrophysics Data System (ADS)

    Im, Seong-Kyun; Baccarella, Damiano; McGann, Brendan; Liu, Qili; Wermer, Lydiy; Do, Hyungrok

    2015-11-01

    The inlet unstart phenomena in a model scramjet are investigated at an arc-heated hypersonic wind tunnel. The unstart induced by nitrogen or ethylene jets at low or high enthalpy Mach 4.5 freestream flow conditions are compared. The jet injection pressurizes the downstream flow by mass addition and flow blockage. In case of the ethylene jet injection, heat release from combustion increases the backpressure further. Time-resolved schlieren imaging is performed at the jet and the lip of the model inlet to visualize the flow features during unstart. High frequency pressure measurements are used to provide information on pressure fluctuation at the scramjet wall. In both of the mass and heat release driven unstart cases, it is observed that there are similar flow transient and quasi-steady behaviors of unstart shockwave system during the unstart processes. Combustion driven unstart induces severe oscillatory flow motions of the jet and the unstart shock at the lip of the scramjet inlet after the completion of the unstart process, while the unstarted flow induced by solely mass addition remains relatively steady. The discrepancies between the processes of mass and heat release driven unstart are explained by flow choking mechanism.

  12. Ecological Optimization and Parametric Study of an Irreversible Regenerative Modified Brayton Cycle with Isothermal Heat Addition

    NASA Astrophysics Data System (ADS)

    Tyagi, Sudhir K.; Kaushik, Subhash C.; Tiwari, Vivek

    2003-12-01

    An ecological optimization along with a detailed parametric study of an irreversible regenerative Brayton heat engine with isothermal heat addition have been carried out with external as well as internal irreversibilities. The ecological function is defined as the power output minus the power loss (irreversibility) which is ambient temperature times the entropy generation rate. The external irreversibility is due to finite temperature difference between the heat engine and the external reservoirs while the internal irreversibilities are due to nonisentropic compression and expansion processes in the compressor and the turbine respectively and the regenerative heat loss. The ecological function is found to be an increasing function of the isothermal-, sink- and regenerative-side effectiveness, isothermal-side inlet temperature, component efficiencies and sink-side temperature while it is found to be a decreasing function of the isobaric-side temperature and effectiveness and the working fluid heat capacitance rate. The effects of the isobaric-side effectiveness are found to be more than those of the other parameters and the effects of turbine efficiency are found to be more than those of the compressor efficiency on all the performance parameters of the cycle.

  13. One-dimensional analysis of thermal choking in case of heat addition in ducts

    NASA Astrophysics Data System (ADS)

    Miyazato, Yoshiaki; Masuda, Mitsuharu; Matsuo, Kazuyasu; Kashitani, Masashi; Yamaguchi, Yutaka

    2000-09-01

    The thermal choking phenomenon is of great importance in an inlet isolator in dual-mode ram jet/scramjet combustor. In some cases the choked flow creates a pseudo-shock wave including a shock train in it at the engine inlet and causes large amounts of drag and radically reduces the performance of the engine at high flight Mach numbers. The present paper describes a one-dimensional flow model taking account of the upstream boundary-layer as well as heat addition by using a mass-weighted averaging technique. The simple relationships for the flow field in a constant area duct in which the effect of the upstream boundary-layer is considered but the effect of the wall friction in the duct can be neglected are presented. The results of the calculation such as the maximum heat addition when the thermal choking occurs, the downstream Mach number and the static pressure ratio are presented and examined in detail.

  14. The influence of heat accumulation on the surface roughness in powder-bed additive manufacturing

    NASA Astrophysics Data System (ADS)

    Jamshidinia, Mahdi; Kovacevic, Radovan

    2015-03-01

    The influence of heat accumulation on surface roughness during powder-bed additive manufacturing was investigated. A series of Ti-6Al-4V thin plates were produced by using an identical heat input by electron beam melting® (EBM). Spacing distances of 5 mm, 10 mm, and 20 mm were used. The surface roughness of as-built thin plates was measured using a two-axis profilometer. A numerical model was developed to study the influence of spacing distance on heat accumulation. An inverse relationship between the spacing distance and surface roughness was revealed. The experimental and numerical results showed that the surface quality of buildups could be controlled not only by process parameters, but also by the arrangement of components in the buildup chamber. At a constant spacing distance, an increase in the number of powder layers resulted in the accumulation of more heat between the thin plates. An increase in the spacing distance resulted in an upward translation of the Bearing Area Curve (BAC) toward shallower depths, with a reduced core roughness depth (Rk) and peak height (Rpk). A logarithmic regression equation was established from the experimental data. This equation could be used to predict the surface roughness of parts fabricated by EBM® in the studied range of spacing distances.

  15. Generalized Latent Trait Models.

    ERIC Educational Resources Information Center

    Moustaki, Irini; Knott, Martin

    2000-01-01

    Discusses a general model framework within which manifest variables with different distributions in the exponential family can be analyzed with a latent trait model. Presents a unified maximum likelihood method for estimating the parameters of the generalized latent trait model and discusses the scoring of individuals on the latent dimensions.…

  16. Heat transfer and material flow during laser assisted multi-layer additive manufacturing

    SciTech Connect

    Manvatkar, V.; De, A.; DebRoy, T.

    2014-09-28

    A three-dimensional, transient, heat transfer, and fluid flow model is developed for the laser assisted multilayer additive manufacturing process with coaxially fed austenitic stainless steel powder. Heat transfer between the laser beam and the powder particles is considered both during their flight between the nozzle and the growth surface and after they deposit on the surface. The geometry of the build layer obtained from independent experiments is compared with that obtained from the model. The spatial variation of melt geometry, cooling rate, and peak temperatures is examined in various layers. The computed cooling rates and solidification parameters are used to estimate the cell spacings and hardness in various layers of the structure. Good agreement is achieved between the computed geometry, cell spacings, and hardness with the corresponding independent experimental results.

  17. Heat transfer and material flow during laser assisted multi-layer additive manufacturing

    NASA Astrophysics Data System (ADS)

    Manvatkar, V.; De, A.; DebRoy, T.

    2014-09-01

    A three-dimensional, transient, heat transfer, and fluid flow model is developed for the laser assisted multilayer additive manufacturing process with coaxially fed austenitic stainless steel powder. Heat transfer between the laser beam and the powder particles is considered both during their flight between the nozzle and the growth surface and after they deposit on the surface. The geometry of the build layer obtained from independent experiments is compared with that obtained from the model. The spatial variation of melt geometry, cooling rate, and peak temperatures is examined in various layers. The computed cooling rates and solidification parameters are used to estimate the cell spacings and hardness in various layers of the structure. Good agreement is achieved between the computed geometry, cell spacings, and hardness with the corresponding independent experimental results.

  18. Measuring the Heats of Water.

    ERIC Educational Resources Information Center

    Hunt, James L.; Tegart, Tracy L.

    1994-01-01

    Uses common equipment (tea kettle and vacuum bottles) to precisely measure the specific heat, latent heat of fusion, and latent heat of vaporization of water. Provides descriptions for all three experiments. (MVL)

  19. Exergy Analysis and Second Law Efficiency of a Regenerative Brayton Cycle with Isothermal Heat Addition

    NASA Astrophysics Data System (ADS)

    Jubeh, Naser M.

    2005-09-01

    The effect of two heat additions, rather than one, in a gas turbine engine is analyzed from the second law of thermodynamics point of view. A regenerative Brayton cycle model is used for this study, and compared with other models of Brayton cycle. All fluid friction losses in the compressor and turbine are quantified by an isentropic efficiency term. The effect of pressure ratio, turbine inlet temperature, ambient temperature, altitude, and altitude with variable ambient temperature on irreversibility "exergy destroyed" and second law efficiency was investigated and compared for all models. The results are given graphically with the appropriate discussion and conclusion.

  20. Estimating seasonal changes of land cover, surface wetness and latent heat flux of wet polygonal tundra (Samoylov Island, Lena-Delta, Siberia) with high-resolution aerial and hyperspectral CHRIS Proba satellite imagery

    NASA Astrophysics Data System (ADS)

    Muster, S.; Langer, M.; Boike, J.

    2009-12-01

    Vegetation cover, land cover and surface wetness are few of the many factors exerting control on the partitioning of energy to latent, sensible and ground heat flux. Spatial estimates of these factors can be inferred from remote sensing data. The fractionated polygonal tundra landscape of Samoylov Island of wet and dry surfaces induces strong spatial variations of resistance to evapotranspiration. The development of low-centered ice-wedge polygons results in a prominent microrelief that is the most important factor for small-scale differences in vegetation type and near surface soil moisture. Depressed polygon centers alternate with elevated polygon rims with elevation differences of up to 0.5 m over a few meters distance. In the depressed polygon centers, drainage is strongly impeded due to the underlying permafrost resulting in water-saturated soils or small ponds. A process-based understanding of the surface energy balance, however, needs to consider both the temporal and the spatial variations of the surface. In the course of the summer season, the surface wetness changes significantly since the water table falls about 5 cm below the surface. This change in surface wetness is likely to be associated with changing evapotranspiration rates. We consider the effect of seasonal changes in land cover, vegetation cover and surface wetness on latent heat flux by investigating a time-series of high-resolution aerial and hyperspectral satellite imagery and comparing them to ground-based measurements of near-surface soil moisture and latent heat flux. Two sets of aerial images from August 15 and September 11, 2008 in the VNIR provide detailed information of the polygonal landscape with a resolution of 0.3m. CHRIS Proba imagery provides hyperspectral data with 18 spectral bands in the VNIR range (400 - 1050 nm) and a resolution of 17 m. Acquisition dates are June 21, July 23 and September 10, 2008. Daily point-based measurements of near-surface soil moisture and latent

  1. Effects of Si Addition and Heating Ar on the Electromigration Performance of Al-Alloy Interconnects

    NASA Astrophysics Data System (ADS)

    Lee, Dok Won; Lee, Byung-Zu; Jeong, Jong Yeul; Park, Hyun; Shim, Kyu Cheol; Kim, Jong Seok; Park, Young Bae; Woo, Sun-Woong; Lee, Jeong-gun

    2002-02-01

    The electromigration (EM) performance of Ti/Al-alloy multilayered metallization with one-step sputtered Al-alloy has been studied. The Al-alloys investigated included Al-1.0%Si-0.5%Cu and Al-0.5%Cu, and the Al-alloy films were prepared with and without heating Ar. The package-level EM test results indicate that the EM resistance of the Al-Si-Cu stack is nearly identical to that of the Al-Cu stack. Si addition was found to degrade the microstructure of the Al-alloy film, while it had the retarding effect on the Ti/Al reaction, which suggests that there exists a trade-off between the film microstructure and the formation of TiAl3 intermetallic compound. The EM performance of the one-step sputtered Al-alloy stack was enhanced by the use of heating Ar during the deposition of Al-alloy film, which has been attributed to the improved microstructure of the Al-alloy film by the use of heating Ar.

  2. Charge state of arginine as an additive on heat-induced protein aggregation.

    PubMed

    Miyatake, Takumi; Yoshizawa, Shunsuke; Arakawa, Tsutomu; Shiraki, Kentaro

    2016-06-01

    Arginine (Arg) is one of the most versatile solvent additives, such as suppressing protein aggregation, increasing solubility of small aromatic compounds and peptides, and preventing protein binding on solid surfaces. In this study, we investigated the role of the charged state of α-amino group of Arg for the prevention of protein aggregation. As expected, Arg effectively suppressed thermal aggregation of hen egg-white lysozyme at neutral pH, whereas the suppression effect diminished at and above pH 9.0, which corresponds to the pK of Arg's α-amino group. The pH dependence of Arg as an aggregation suppressor was confirmed by additional experiments with neutral proteins, bovine hemoglobin and bovine γ-globulin. Interestingly, N-acetylated arginine, which lacks the α-amino group, showed a weaker suppressive effect on protein aggregation than Arg, even at neutral pH. These results indicate that both positively charged α-amino group and guanidinium group play important roles in suppressing heat-induced protein aggregation by Arg. The elucidated limitation of Arg at alkaline pH provides new insight in the application as well as the mechanism of Arg as a solvent additive. PMID:26987431

  3. On latent fingerprint enhancement

    NASA Astrophysics Data System (ADS)

    Yoon, Soweon; Feng, Jianjiang; Jain, Anil K.

    2010-04-01

    Automatic feature extraction in latent fingerprints is a challenging problem due to poor quality of most latents, such as unclear ridge structures, overlapped lines and letters, and overlapped fingerprints. We proposed a latent fingerprint enhancement algorithm which requires manually marked region of interest (ROI) and singular points. The core of the proposed enhancement algorithm is a novel orientation field estimation algorithm, which fits orientation field model to coarse orientation field estimated from skeleton outputted by a commercial fingerprint SDK. Experimental results on NIST SD27 latent fingerprint database indicate that by incorporating the proposed enhancement algorithm, the matching accuracy of the commercial matcher was significantly improved.

  4. Precipitation of sword bean proteins by heating and addition of magnesium chloride in a crude extract.

    PubMed

    Nishizawa, Kaho; Masuda, Tetsuya; Takenaka, Yasuyuki; Masui, Hironori; Tani, Fumito; Arii, Yasuhiro

    2016-08-01

    Sword bean (Canavalia gladiata) seeds are a traditional food in Asian countries. In this study, we aimed to determine the optimal methods for the precipitation of sword bean proteins useful for the food development. The soaking time for sword beans was determined by comparing it with that for soybeans. Sword bean proteins were extracted from dried seeds in distilled water using novel methods. We found that most proteins could be precipitated by heating the extract at more than 90 °C. Interestingly, adding magnesium chloride to the extract at lower temperatures induced specific precipitation of a single protein with a molecular weight of approximately 48 kDa. The molecular weight and N-terminal sequence of the precipitated protein was identical to that of canavalin. These data suggested that canavalin was precipitated by the addition of magnesium chloride to the extract. Our results provide important insights into the production of processed foods from sword bean. PMID:27022983

  5. Nonlinear feedback in a six-dimensional Lorenz Model: impact of an additional heating term

    NASA Astrophysics Data System (ADS)

    Shen, B.-W.

    2015-03-01

    In this study, a six-dimensional Lorenz model (6DLM) is derived, based on a recent study using a five-dimensional (5-D) Lorenz model (LM), in order to examine the impact of an additional mode and its accompanying heating term on solution stability. The new mode added to improve the representation of the steamfunction is referred to as a secondary streamfunction mode, while the two additional modes, that appear in both the 6DLM and 5DLM but not in the original LM, are referred to as secondary temperature modes. Two energy conservation relationships of the 6DLM are first derived in the dissipationless limit. The impact of three additional modes on solution stability is examined by comparing numerical solutions and ensemble Lyapunov exponents of the 6DLM and 5DLM as well as the original LM. For the onset of chaos, the critical value of the normalized Rayleigh number (rc) is determined to be 41.1. The critical value is larger than that in the 3DLM (rc ~ 24.74), but slightly smaller than the one in the 5DLM (rc ~ 42.9). A stability analysis and numerical experiments obtained using generalized LMs, with or without simplifications, suggest the following: (1) negative nonlinear feedback in association with the secondary temperature modes, as first identified using the 5DLM, plays a dominant role in providing feedback for improving the solution's stability of the 6DLM, (2) the additional heating term in association with the secondary streamfunction mode may destabilize the solution, and (3) overall feedback due to the secondary streamfunction mode is much smaller than the feedback due to the secondary temperature modes; therefore, the critical Rayleigh number of the 6DLM is comparable to that of the 5DLM. The 5DLM and 6DLM collectively suggest different roles for small-scale processes (i.e., stabilization vs. destabilization), consistent with the following statement by Lorenz (1972): If the flap of a butterfly's wings can be instrumental in generating a tornado, it can

  6. Nonlinear feedback in a six-dimensional Lorenz model: impact of an additional heating term

    NASA Astrophysics Data System (ADS)

    Shen, B.-W.

    2015-12-01

    In this study, a six-dimensional Lorenz model (6DLM) is derived, based on a recent study using a five-dimensional (5-D) Lorenz model (LM), in order to examine the impact of an additional mode and its accompanying heating term on solution stability. The new mode added to improve the representation of the streamfunction is referred to as a secondary streamfunction mode, while the two additional modes, which appear in both the 6DLM and 5DLM but not in the original LM, are referred to as secondary temperature modes. Two energy conservation relationships of the 6DLM are first derived in the dissipationless limit. The impact of three additional modes on solution stability is examined by comparing numerical solutions and ensemble Lyapunov exponents of the 6DLM and 5DLM as well as the original LM. For the onset of chaos, the critical value of the normalized Rayleigh number (rc) is determined to be 41.1. The critical value is larger than that in the 3DLM (rc ~ 24.74), but slightly smaller than the one in the 5DLM (rc ~ 42.9). A stability analysis and numerical experiments obtained using generalized LMs, with or without simplifications, suggest the following: (1) negative nonlinear feedback in association with the secondary temperature modes, as first identified using the 5DLM, plays a dominant role in providing feedback for improving the solution's stability of the 6DLM, (2) the additional heating term in association with the secondary streamfunction mode may destabilize the solution, and (3) overall feedback due to the secondary streamfunction mode is much smaller than the feedback due to the secondary temperature modes; therefore, the critical Rayleigh number of the 6DLM is comparable to that of the 5DLM. The 5DLM and 6DLM collectively suggest different roles for small-scale processes (i.e., stabilization vs. destabilization), consistent with the following statement by Lorenz (1972): "If the flap of a butterfly's wings can be instrumental in generating a tornado, it can

  7. Latent and delayed action polymerization systems.

    PubMed

    Naumann, Stefan; Buchmeiser, Michael R

    2014-04-01

    Various approaches to latent polymerization processes are described. In order to highlight recent advances in this field, the discussion is subdivided into chapters dedicated to diverse classes of polymers, namely polyurethanes, polyamides, polyesters, polyacrylates, epoxy resins, and metathesis-derived polymers. The described latent initiating systems encompass metal-containing as well as purely organic compounds that are activated by external triggers such as light, heat, or mechanical force. Special emphasis is put on the different chemical venues that can be taken to achieve true latency, which include masked N-heterocyclic carbenes, latent metathesis catalysts, and photolatent radical initiators, among others. Scientific challenges and the advantageous application of latent polymerization processes are discussed. PMID:24519912

  8. Experimental investigation of nucleate boiling heat transfer mechanisms for cylinders in water and FC-72

    SciTech Connect

    Ammerman, C.N.; You, S.M.; Hong, Y.S.

    1995-12-31

    A recently developed photographic method is used to quantify vapor volumetric flow rate above a boiling wire. The volumetric flow rate is combined with additional analyses to determine the overall contributions to the total heat flux from four nucleate boiling heat transfer mechanisms (latent heat, natural convection, Marangoni flow, and micro-convection). This technique is used to quantify the boiling heat transfer mechanisms versus heat flux for a 510-{micro}m wire immersed in saturated water and in water with a small amount of liquid soap added. These data are compared with similar data taken for a 75-{micro}m wire boiling in saturated FC-72. For all cases, latent heat is the dominant heat transfer mechanism in the fully developed nucleate boiling regime. In addition, the latent heat component is significantly increased by the addition of small amounts of soap (surfactant).

  9. Additions to compact heat exchanger technology: Jet impingement cooling & flow & heat transfer in metal foam-fins

    NASA Astrophysics Data System (ADS)

    Onstad, Andrew J.

    Compact heat exchangers have been designed following the same basic methodology for over fifty years. However, with the present emphasis on energy efficiency and light weight of prime movers there is increasing demand for completely new heat exchangers. Moreover, new materials and mesoscale fabrication technologies offer the possibility of significantly improving heat exchanger performance over conventional designs. This work involves fundamental flow and heat transfer experimentation to explore two new heat exchange systems: in Part I, large arrays of impinging jets with local extraction and in Part II, metal foams used as fins. Jet impingement cooling is widely used in applications ranging from paper manufacturing to the cooling of gas turbine blades because of the very high local heat transfer coefficients that are possible. While the use of single jet impingement results in non-uniform cooling, increased and more uniform mean heat transfer coefficients may be attained by dividing the total cooling flow among an array of smaller jets. Unfortunately, when the spent fluid from the array's central jets interact with the outer jets, the overall mean heat transfer coefficient is reduced. This problem can be alleviated by locally extracting the spent fluid before it is able to interact with the surrounding jets. An experimental investigation was carried out on a compact impingement array (Xn/Djet = 2.34) utilizing local extraction of the spent fluid (Aspent/Ajet = 2.23) from the jet exit plane. Spatially resolved measurements of the mean velocity field within the array were carried out at jet Reynolds numbers of 2300 and 5300 by magnetic resonance velocimetry, MRV. The geometry provided for a smooth transition from the jet to the target surface and out through the extraction holes without obvious flow recirculation. Mean Nusselt number measurements were also carried out for a Reynolds number range of 2000 to 10,000. The Nusselt number was found to increase with the

  10. Latent Variable Theory

    ERIC Educational Resources Information Center

    Borsboom, Denny

    2008-01-01

    This paper formulates a metatheoretical framework for latent variable modeling. It does so by spelling out the difference between observed and latent variables. This difference is argued to be purely epistemic in nature: We treat a variable as "observed" when the inference from data structure to variable structure can be made with certainty and as…

  11. LATENT LIFE OF ARTERIES.

    PubMed

    Carrel, A

    1910-07-23

    When a segment of artery, killed by heat, formalin or glycerin is transplanted, it undergoes a rapid degeneration. Its muscle fibers disappear while the tissue of the host reacts by building a new wall of connective tissue. When the transplanted vessel has been preserved in a condition of latent life, no degeneration of the wall occurs, or the wall undergoes only partial degeneration. The muscle fibers can keep their normal appearance, even for a long time after the operation. It is, therefore, demonstrated that arteries can be preserved outside of the body in a condition of unmanifested actual life. The best method of preservation consists of placing the vessels, immersed in vaselin, in an ice box, the temperature of which is slightly above the freezing point. From a surgical standpoint, the transplantation of preserved vessels can be used with some safety. When the arteries were kept in defibrinated blood or vaselin and in cold storage, the proportion of positive results was 75 and 80 per cent., and this can probably be increased. PMID:19867337

  12. Additive impacts on particle emissions from heating low emitting cooking oils

    NASA Astrophysics Data System (ADS)

    Amouei Torkmahalleh, M.; Zhao, Y.; Hopke, P. K.; Rossner, A.; Ferro, A. R.

    2013-08-01

    The effect of five additives, including table salt, sea salt, black pepper, garlic powder, and turmeric, on the emission of PM2.5 and ultrafine particles (UFP) from heated cooking oil (200 °C) were studied. One hundred milligrams of the additives were added individually to either canola or soybean oil without stirring. Black pepper, table salt, and sea salt reduced the PM2.5 emission of canola oil by 86% (p < 0.001), 88% (p < 0.001), and 91% (p < 0.001), respectively. Black pepper, table salt, and sea salt also decreased the total particle number emissions of canola oil by 45% (p = 0.003), 52% (p = 0.001), and 53% (p < 0.001), respectively. Turmeric and garlic powder showed no changes in the PM2.5 and total number emissions of canola oil. Table salt and sea salt, decreased the level of PM2.5 emissions from soybean oil by 47% (p < 0.001) and 77% (p < 0.001), respectively. No differences in the PM2.5 emissions were observed when other additives were added to soybean oil. Black pepper, sea salt, and table salt reduced the total particle number emissions from the soybean oil by 51%, 61% and 68% (p < 0.001), respectively. Turmeric and garlic powder had no effect on soybean oil with respect to total particle number emissions. Our results indicate that table salt, sea salt, and black pepper can be used to reduce the particle total number and PM2.5 emissions when cooking with oil.

  13. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  14. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  15. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  16. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  17. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  18. Corrosion and Heat Transfer Characteristics of Water Dispersed with Carboxylate Additives and Multi Walled Carbon Nano Tubes

    NASA Astrophysics Data System (ADS)

    Moorthy, Chellapilla V. K. N. S. N.; Srinivas, Vadapalli

    2016-02-01

    This paper summarizes a recent work on anti-corrosive properties and enhanced heat transfer properties of carboxylated water based nanofluids. Water mixed with sebacic acid as carboxylate additive found to be resistant to corrosion and suitable for automotive environment. The carboxylated water is dispersed with very low mass concentration of carbon nano tubes at 0.025, 0.05 and 0.1 %. The stability of nanofluids in terms of zeta potential is found to be good with carboxylated water compared to normal water. The heat transfer performance of nanofluids is carried out on an air cooled heat exchanger similar to an automotive radiator with incoming air velocities across radiator at 5, 10 and 15 m/s. The flow Reynolds number of water is in the range of 2500-6000 indicating developing flow regime. The corrosion resistance of nanofluids is found to be good indicating its suitability to automotive environment. There is a slight increase in viscosity and marginal decrease in the specific heat of nanofluids with addition of carboxylate as well as CNTs. Significant improvement is observed in the thermal conductivity of nanofluids dispersed with CNTs. During heat transfer experimentation, the inside heat transfer coefficient and overall heat transfer coefficient has also improved markedly. It is also found that the velocity of air and flow rate of coolant plays an important role in enhancement of the heat transfer coefficient and overall heat transfer coefficient.

  19. Multimethod latent class analysis

    PubMed Central

    Nussbeck, Fridtjof W.; Eid, Michael

    2015-01-01

    Correct and, hence, valid classifications of individuals are of high importance in the social sciences as these classifications are the basis for diagnoses and/or the assignment to a treatment. The via regia to inspect the validity of psychological ratings is the multitrait-multimethod (MTMM) approach. First, a latent variable model for the analysis of rater agreement (latent rater agreement model) will be presented that allows for the analysis of convergent validity between different measurement approaches (e.g., raters). Models of rater agreement are transferred to the level of latent variables. Second, the latent rater agreement model will be extended to a more informative MTMM latent class model. This model allows for estimating (i) the convergence of ratings, (ii) method biases in terms of differential latent distributions of raters and differential associations of categorizations within raters (specific rater bias), and (iii) the distinguishability of categories indicating if categories are satisfyingly distinct from each other. Finally, an empirical application is presented to exemplify the interpretation of the MTMM latent class model. PMID:26441714

  20. One-dimensional analysis of unsteady flows due to supercritical heat addition in high speed condensing steam

    NASA Astrophysics Data System (ADS)

    Malek, N. A.; Hasini, H.; Yusoff, M. Z.

    2013-06-01

    Unsteadiness in supersonic flow in nozzles can be generated by the release of heat due to spontaneous condensation. The heat released is termed "supercritical" and may be responsible for turbine blades failure in turbine cascade as it causes a supersonic flow to decelerate. When the Mach number is reduced to unity, the flow can no longer sustain the additional heat and becomes unstable. This paper aims to numerically investigate the unsteadiness caused by supercritical heat addition in one-dimensional condensing flows. The governing equations for mass, momentum and energy, coupled with the equations describing the wetness fraction and droplet growth are integrated and solved iteratively to reveal the final solution. Comparison is made with well-established experimental and numerical solution done by previous researchers that shows similar phenomena.

  1. Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor

    NASA Technical Reports Server (NTRS)

    Wilson, Scott D.; Reid, Terry; Schifer, Nicholas; Briggs, Maxwell

    2011-01-01

    Past methods of predicting net heat input needed to be validated. Validation effort pursued with several paths including improving model inputs, using test hardware to provide validation data, and validating high fidelity models. Validation test hardware provided direct measurement of net heat input for comparison to predicted values. Predicted value of net heat input was 1.7 percent less than measured value and initial calculations of measurement uncertainty were 2.1 percent (under review). Lessons learned during validation effort were incorporated into convertor modeling approach which improved predictions of convertor efficiency.

  2. Decrease in the acrylamide content in canned coffee by heat treatment with the addition of cysteine.

    PubMed

    Narita, Yusaku; Inouye, Kuniyo

    2014-12-17

    Acrylamide (AA) is classified as a Group 2A carcinogen according to the International Agency for Research on Cancer. Although coffee contains a small amount of AA, it is a popular beverage worldwide. Approximately 10 billion canned coffees are consumed each year in Japan. In this study, we investigated how to decrease AA contained in canned coffee by modifying the heat treatment used for sterilization during the manufacturing process. The AA content of both types of canned coffee (black and milk) was decreased by approximately 95% by heat treatment with adding cysteine at 121 °C for 6 min. The content was also decreased by heat treatment with dithiothreitol, although that with cystine had no effect. Therefore, it is shown that thiol groups in cysteine and dithiothreitol might play an important role in decreasing the AA content. PMID:25420187

  3. Extending periodic eddy covariance latent heat fluxes through tree sap-flow measurements to estimate long-term total evaporation in a peat swamp forest

    NASA Astrophysics Data System (ADS)

    Clulow, A. D.; Everson, C. S.; Mengistu, M. G.; Price, J. S.; Nickless, A.; Jewitt, G. P. W.

    2015-05-01

    A combination of measurement and modelling was used to find a pragmatic solution to estimate the annual total evaporation from the rare and indigenous Nkazana Peat Swamp Forest (PSF) on the east coast of Southern Africa to improve the water balance estimates within the area. Actual total evaporation (ETa) was measured during three window periods (between 7 and 9 days each) using an eddy covariance (EC) system on a telescopic mast above the forest canopy. Sap flows of an understory tree and an emergent tree were measured using a low-maintenance heat pulse velocity system for an entire hydrological year (October 2009 to September 2010). An empirical model was derived, describing the relationship between ETa from the Nkazana PSF and sap-flow measurements. These overlapped during two of the window periods (R2 = 0.92 and 0.90), providing hourly estimates of ETa from the Nkazana PSF for a year, totalling 1125 mm (while rainfall was 650 mm). In building the empirical model, it was found that to include the understory tree sap flow provided no benefit to the model performance. In addition, the relationship between the emergent tree sap flow with ETa between the two field campaigns was consistent and could be represented by a single empirical model (R2 = 0.90; RMSE = 0.08 mm h-1). During the window periods of EC measurement, no single meteorological variable was found to describe the Nkazana PSF ETa satisfactorily. However, in terms of evaporation models, the hourly FAO Penman-Monteith reference evaporation (ETo) best described ETa during the August 2009 (R2 = 0.75), November 2009 (R2 = 0.85) and March 2010 (R2 = 0.76) field campaigns, compared to the Priestley-Taylor potential evaporation (ETp) model (R2 = 0.54, 0.74 and 0.62 during the respective field campaigns). From the extended record of ETa (derived in this study from sap flow) and ETo, a monthly crop factor (Kc) was derived for the Nkazana PSF, providing a method of estimating long-term swamp forest water-use from

  4. Effects of different additives with assistance of microwave heating for heavy metal stabilization in electronic industry sludge.

    PubMed

    Jothiramalingam, R; Lo, Shang-Lien; Chen, Ching-lung

    2010-01-01

    Electronic industrial wastewater sludge in Taiwan is normally passed through an acid-extraction process to reclaim most of the copper ions, the remaining residue may still need to be treated by various stabilization technologies using suitable additives. Cement solidification is used as the common method to stabilize the industrial wastewater sludge in Taiwan. However, this method has the disadvantage of an increase in waste volume. In the present study selective additives such as sodium sulfide, barium manganate and different phase of alumina were tested as a possible alternate additive to stabilize the heavy metal ion in the treated solid waste sludge via microwave heating treatment. The effects of additive amount, power of microwave irradiation and reaction time have been studied. Heavy metal leaching capacity is determined by using standard toxicity characteristic leaching procedure test and elemental content in the leachate is analyzed by inductively coupled plasma analysis. Sodium sulfide is effectively stabilizing the leaching copper ion with high selectivity in the presence of microwave irradiation and finally stabilized in the form of copper sulfide, which is a significant reaction to stabilize the copper ion leaching in the waste sludge. Complete stabilization of heavy metal ion and copper ion content (<5mgL(-1)) in industrial sludge is achieved by heating the microwave treated barium manganate and alumina additives by adopting suitable reaction conditions. Hybrid microwave and conventional heating process with minor amount of additive providing the efficient heavy metal stabilization for treated electronic industry waste sludge. PMID:19945139

  5. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX BUDGET TRADING PROGRAM AND CAIR NOX AND SO2 TRADING PROGRAMS... a NOX Budget unit that monitors and reports NOX mass emissions using a NOX concentration system and a flow system shall also monitor and report heat input rate at the unit level using the...

  6. The Synergism Between Heat and Mass Transfer Additive and Advanced Surfaces in Aqueous LiBr Horizontal Tube Absorbers

    SciTech Connect

    Miller, W.A.

    1999-03-24

    Experiments were conducted in a laboratory to investigate the absorption of water vapor into a falling-film of aqueous lithium bromide (LiBr). A mini-absorber test stand was used to test smooth tubes and a variety of advanced tube surfaces placed horizontally in a single-row bundle. The bundle had six copper tubes; each tube had an outside diameter of 15.9-mm and a length of 0.32-m. A unique feature of the stand is its ability to operate continuously and support testing of LiBr brine at mass fractions {ge} 0.62. The test stand can also support testing to study the effect of the failing film mass flow rate, the coolant mass flow rate, the coolant temperature, the absorber pressure and the tube spacing. Manufacturers of absorption chillers add small quantities of a heat and mass transfer additive to improve the performance of the absorbers. The additive causes surface stirring which enhances the transport of absorbate into the bulk of the film. Absorption may also be enhanced with advanced tube surfaces that mechanically induce secondary flows in the falling film without increasing the thickness of the film. Several tube geometry's were identified and tested with the intent of mixing the film and renewing the interface with fresh solution from the tube wall. Testing was completed on a smooth tube and several different externally enhanced tube surfaces. Experiments were conducted over the operating conditions of 6.5 mm Hg absorber pressure, coolant temperatures ranging from 20 to 35 C and LiBr mass fractions ranging from 0.60 through 0.62. Initially the effect of tube spacing was investigated for the smooth tube surface, tested with no heat and mass transfer additive. Test results showed the absorber load and the mass absorbed increased as the tube spacing increased because of the improved wetting of the tube bundle. However, tube spacing was not a critical factor if heat and mass transfer additive was active in the mini-absorber. The additive dramatically affected

  7. Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature using Group Additivity. I. Hydrocarbon Compounds

    NASA Astrophysics Data System (ADS)

    Růžička, Vlastimil; Domalski, Eugene S.

    1993-05-01

    A second-order group additivity method has been developed for the estimation of the heat capacity of liquid hydrocarbons as a function of temperature in the range from the melting temperature to the normal boiling temperature. The temperature dependence of group contributions and structural corrections has been represented by a polynomial expression. The adjustable parameters in the polynomials have been calculated using a weighted least squares minimization procedure. Recommended heat capacities from a large compilation of critically evaluated data that contains over 1300 organic liquids served as a database both for the development and testing of the method.

  8. Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium.

    PubMed

    Amin Yavari, S; Chai, Y C; Böttger, A J; Wauthle, R; Schrooten, J; Weinans, H; Zadpoor, A A

    2015-06-01

    Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20V anodizing time: 30min to 3h) are used for anodizing porous titanium structures that were later heat treated at 500°C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500°C improve the cell culture response of porous titanium. PMID

  9. Latent Semantic Analysis.

    ERIC Educational Resources Information Center

    Dumais, Susan T.

    2004-01-01

    Presents a literature review that covers the following topics related to Latent Semantic Analysis (LSA): (1) LSA overview; (2) applications of LSA, including information retrieval (IR), information filtering, cross-language retrieval, and other IR-related LSA applications; (3) modeling human memory, including the relationship of LSA to other…

  10. Measuring Latent Quantities

    ERIC Educational Resources Information Center

    McDonald, Roderick P.

    2011-01-01

    A distinction is proposed between measures and predictors of latent variables. The discussion addresses the consequences of the distinction for the true-score model, the linear factor model, Structural Equation Models, longitudinal and multilevel models, and item-response models. A distribution-free treatment of calibration and…

  11. Latent Variable Interaction Modeling.

    ERIC Educational Resources Information Center

    Schumacker, Randall E.

    2002-01-01

    Used simulation to study two different approaches to latent variable interaction modeling with continuous observed variables: (1) a LISREL 8.30 program and (2) data analysis through PRELIS2 and SIMPLIS programs. Results show that parameter estimation was similar but standard errors were different. Discusses differences in ease of implementation.…

  12. Solar heat storage in phase change material

    SciTech Connect

    Phillips, H.J.

    1984-02-28

    The objective of this project was to develop a chemical heat storage system that had a phase change with release of latent heat at about 105/sup 0/F. The primary reason this kind on system was sought was that heat storage capacity of commonly used storage systems do not match the heat collection capacity of open air collectors. In addition to the phase change three other factors were considered: the cost of the material, the amount of heat the system would hold per unit volume, and the rate at which the system released sensible and latent heat. One hundred nineteen tests were made on 32 systems. Only data on six of the more promising are presented. In the six systems, borax was used as the major component with other materials used as nucleating agents toraise the temperature of phase change.

  13. 40 CFR 60.4176 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Compliance Times for Coal-Fired Electric Steam Generating Units Monitoring and Reporting § 60.4176 Additional... mass emissions using a Hg concentration monitoring system and a flow monitoring system shall...

  14. 40 CFR 60.4176 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Compliance Times for Coal-Fired Electric Steam Generating Units Monitoring and Reporting § 60.4176 Additional... mass emissions using a Hg concentration monitoring system and a flow monitoring system shall...

  15. Addition of simultaneous heat and solute transport and variable fluid viscosity to SEAWAT

    USGS Publications Warehouse

    Thorne, D.; Langevin, C.D.; Sukop, M.C.

    2006-01-01

    SEAWAT is a finite-difference computer code designed to simulate coupled variable-density ground water flow and solute transport. This paper describes a new version of SEAWAT that adds the ability to simultaneously model energy and solute transport. This is necessary for simulating the transport of heat and salinity in coastal aquifers for example. This work extends the equation of state for fluid density to vary as a function of temperature and/or solute concentration. The program has also been modified to represent the effects of variable fluid viscosity as a function of temperature and/or concentration. The viscosity mechanism is verified against an analytical solution, and a test of temperature-dependent viscosity is provided. Finally, the classic Henry-Hilleke problem is solved with the new code. ?? 2006 Elsevier Ltd. All rights reserved.

  16. Emulsifying properties and oil/water (O/W) interface adsorption behavior of heated soy proteins: effects of heating concentration, homogenizer rotating speed, and salt addition level.

    PubMed

    Cui, Zhumei; Chen, Yeming; Kong, Xiangzhen; Zhang, Caimeng; Hua, Yufei

    2014-02-19

    The adsorption of heat-denatured soy proteins at the oil/water (O/W) interface during emulsification was studied. Protein samples were prepared by heating protein solutions at concentrations of 1-5% (w/v) and were then diluted to 0.3% (w/v). The results showed that soy proteins that had been heated at higher concentrations generated smaller droplet size of emulsion. Increase in homogenizer rotating speed resulted in higher protein adsorption percentages and lower surface loads at the O/W interface. Surface loads for both unheated and heated soy proteins were linearly correlated with the unadsorbed proteins' equilibrium concentration at various rotating speeds. With the rise in NaCl addition level, protein adsorption percentage and surface loads of emulsions increased, whereas lower droplet sizes were obtained at the ionic strength of 0.1 M. The aggregates and non-aggregates displayed different adsorption behaviors when rotating speed or NaCl concentration was varied. PMID:24460091

  17. Latent effects decision analysis

    DOEpatents

    Cooper, J. Arlin; Werner, Paul W.

    2004-08-24

    Latent effects on a system are broken down into components ranging from those far removed in time from the system under study (latent) to those which closely effect changes in the system. Each component is provided with weighted inputs either by a user or from outputs of other components. A non-linear mathematical process known as `soft aggregation` is performed on the inputs to each component to provide information relating to the component. This information is combined in decreasing order of latency to the system to provide a quantifiable measure of an attribute of a system (e.g., safety) or to test hypotheses (e.g., for forensic deduction or decisions about various system design options).

  18. Fabrication of Thermoelectric Devices Using Additive-Subtractive Manufacturing Techniques: Application to Waste-Heat Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Tewolde, Mahder

    Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are well suited for waste-heat energy harvesting applications as opposed to primary energy generation. Commercially available thermoelectric modules are flat, inflexible and have limited sizes available. State-of-art manufacturing of TEG devices relies on assembling prefabricated parts with soldering, epoxy bonding, and mechanical clamping. Furthermore, efforts to incorporate them onto curved surfaces such as exhaust pipes, pump housings, steam lines, mixing containers, reaction chambers, etc. require custom-built heat exchangers. This is costly and labor-intensive, in addition to presenting challenges in terms of space, thermal coupling, added weight and long-term reliability. Additive manufacturing technologies are beginning to address many of these issues by reducing part count in complex designs and the elimination of sub-assembly requirements. This work investigates the feasibility of utilizing such novel manufacturing routes for improving the manufacturing process of thermoelectric devices. Much of the research in thermoelectricity is primarily focused on improving thermoelectric material properties by developing of novel materials or finding ways to improve existing ones. Secondary to material development is improving the manufacturing process of TEGs to provide significant cost benefits. To improve the device fabrication process, this work explores additive manufacturing technologies to provide an integrated and scalable approach for TE device manufacturing directly onto engineering component surfaces. Additive manufacturing techniques like thermal spray and ink-dispenser printing are developed with the aim of improving the manufacturing process of TEGs. Subtractive manufacturing techniques like laser micromachining are also studied in detail. This includes the laser processing parameters for cutting the thermal spray materials efficiently by

  19. Thermally Stable, Latent Olefin Metathesis Catalysts.

    PubMed

    Thomas, Renee M; Fedorov, Alexey; Keitz, Benjamin K; Grubbs, Robert H

    2011-12-26

    Highly thermally stable N-aryl,N-alkyl N-heterocyclic carbene (NHC) ruthenium catalysts were designed and synthesized for latent olefin metathesis. These catalysts showed excellent latent behavior toward metathesis reactions, whereby the complexes were inactive at ambient temperature and initiated at elevated temperatures, a challenging property to achieve with second generation catalysts. A sterically hindered N-tert-butyl substituent on the NHC ligand of the ruthenium complex was found to induce latent behavior toward cross-metathesis reactions, and exchange of the chloride ligands for iodide ligands was necessary to attain latent behavior during ring-opening metathesis polymerization (ROMP). Iodide-based catalysts showed no reactivity toward ROMP of norbornene-derived monomers at 25 °C, and upon heating to 85 °C gave complete conversion of monomer to polymer in less than 2 hours. All of the complexes were very stable to air, moisture, and elevated temperatures up to at least 90 °C, and exhibited a long catalyst lifetime in solution at elevated temperatures. PMID:22282652

  20. Global Atmospheric Heat Distributions Observed from Space

    NASA Technical Reports Server (NTRS)

    Lin, Bing; Fan, Tai-Fang

    2009-01-01

    This study focuses on the observations of global atmospheric heat distributions using satellite measurements. Major heat components such as radiation energy, latent heat and sensible heat are considered. The uncertainties and error sources are assessed. Results show that the atmospheric heat is basically balanced, and the observed patterns of radiation and latent heat from precipitation are clearly related to general circulation.

  1. Estimation of the Heat Capacities of Organic Liquids as a Function of Temperature Using Group Additivity. An Amendment

    NASA Astrophysics Data System (ADS)

    Zábranský, Milan; Růžička, Vlastimil

    2004-12-01

    An amendment to a second-order group additivity method for the estimation of the heat capacity of pure organic liquids as a function of temperature in the range from the melting temperature to the normal boiling temperature is reported. The temperature dependence of various group contributions and structural corrections is represented by a series of second order polynomial expressions. The group contribution parameters have been developed from an extended database of more than 1800 recommended heat capacity values. The present method should be more versatile and more accurate than the previous one [Růžička and Domalski, J. Phys. Chem. Ref. Data 22, 597, 619 (1993)] due to the use of a larger database and an improved procedure for parameter calculation.

  2. Group additive values for the gas-phase standard enthalpy of formation, entropy and heat capacity of oxygenates.

    PubMed

    Paraskevas, Paschalis D; Sabbe, Maarten K; Reyniers, Marie-Françoise; Papayannakos, Nikos; Marin, Guy B

    2013-11-25

    A complete and consistent set of 60 Benson group additive values (GAVs) for oxygenate molecules and 97 GAVs for oxygenate radicals is provided, which allow to describe their standard enthalpies of formation, entropies and heat capacities. Approximately half of the GAVs for oxygenate molecules and the majority of the GAVs for oxygenate radicals have not been reported before. The values are derived from an extensive and accurate database of thermochemical data obtained by ab initio calculations at the CBS-QB3 level of theory for 202 molecules and 248 radicals. These compounds include saturated and unsaturated, α- and β-branched, mono- and bifunctional oxygenates. Internal rotations were accounted for by using one-dimensional hindered rotor corrections. The accuracy of the database was further improved by adding bond additive corrections to the CBS-QB3 standard enthalpies of formation. Furthermore, 14 corrections for non-nearest-neighbor interactions (NNI) were introduced for molecules and 12 for radicals. The validity of the constructed group additive model was established by comparing the predicted values with both ab initio calculated values and experimental data for oxygenates and oxygenate radicals. The group additive method predicts standard enthalpies of formation, entropies, and heat capacities with chemical accuracy, respectively, within 4 kJ mol(-1) and 4 J mol(-1) K(-1) for both ab initio calculated and experimental values. As an alternative, the hydrogen bond increment (HBI) method developed by Lay et al. (T. H. Lay, J. W. Bozzelli, A. M. Dean, E. R. Ritter, J. Phys. Chem.- 1995, 99, 14514) was used to introduce 77 new HBI structures and to calculate their thermodynamic parameters (Δ(f)H°, S°, C(p)°). The GAVs reported in this work can be reliably used for the prediction of thermochemical data for large oxygenate compounds, combining rapid prediction with wide-ranging application. PMID:24123572

  3. Capsaicin-induced reactivation of latent herpes simplex virus type 1 in sensory neurons in culture.

    PubMed

    Hunsperger, Elizabeth A; Wilcox, Christine L

    2003-05-01

    Herpes simplex virus type 1 (HSV-1) produces a life-long latent infection in neurons of the peripheral nervous system, primarily in the trigeminal and dorsal root ganglia. Neurons of these ganglia express high levels of the capsaicin receptor, also known as the vanilloid receptor-1 (VR-1). VR-1 is a non-selective ion channel, found on sensory neurons, that primarily fluxes Ca(2+) ions in response to various stimuli, including physiologically acidic conditions, heat greater than 45 degrees C and noxious compounds such as capsaicin. Using an in vitro neuronal model to study HSV-1 latency and reactivation, we found that agonists of the VR-1 channel - capsaicin and heat - resulted in reactivation of latent HSV-1. Capsaicin-induced reactivation of HSV-1 latently infected neurons was dose-dependent. Additionally, activation of VR-1 at its optimal temperature of 46 degrees C caused a significant increase in virus titres, which could be attenuated with the VR-1 antagonist, capsazepine. VR-1 activation that resulted in HSV-1 reactivation was calcium-dependent, since the calcium chelator BAPTA significantly reduced reactivation following treatment with caspsaicin and forskolin. Taken together, these results suggest that activation of the VR-1 channel, often associated with increases in intracellular calcium, results in HSV-1 reactivation in sensory neurons. PMID:12692270

  4. Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models

    SciTech Connect

    Tao, Wei-Kuo; Houze, Robert, A., Jr.; Zeng, Xiping

    2013-03-14

    observations to evaluate model simulations In cooperation with Profs. Bob Houze at University of Washington and Steven Rutledge at Colorado State University, numerical model results were evaluated with observations from W- and C-band radars and CloudSat/TRMM satellites. These studies exhibited some shortcomings of current numerical models, such as too little of thin anvil clouds, directing the future improvement of cloud microphysics parameterization in CRMs. Two papers of Powell et al (2012) and Zeng et al. (2013), summarizing these studies, were published in the Journal of the Atmospheric Sciences. 4. Analyzed the water budgets of MCSs Using ARM data from TWP-ICE, ARM-SGP and other field campaigns, the Goddard CRM simulations were carried out to analyze the water budgets of clouds from TWP-ICE and AMMA. The simulations generated a set of datasets on clouds and radiation, which are available http://cloud.gsfc.nasa.gov/. The cloud datasets were available for modelers and other researchers aiming to improve the representation of cloud processes in multi-scale modeling frameworks, GCMs and climate models. Special datasets, such as 3D cloud distributions every six minutes for TWP-ICE, were requested and generated for ARM/ASR investigators. Data server records show that 86,206 datasets were downloaded by 120 users between April of 2010 and January of 2012. 5. MMF simulations The Goddard MMF (multi-scale modeling framework) has been improved by coupling with the Goddard Land Information System (LIS) and the Goddard Earth Observing System Model, Version 5 (GOES5). It has also been optimized on NASA HEC supercomputers and can be run over 4000 CPUs. The improved MMF with high horizontal resolution (1 x 1 degree) is currently being applied to cases covering 2005 and 2006. The results show that the spatial distribution pattern of precipitation rate is well simulated by the MMF through comparisons with satellite retrievals from the CMOPRH and GPCP data sets. In addition, the MMF results

  5. Latent semantic analysis.

    PubMed

    Evangelopoulos, Nicholas E

    2013-11-01

    This article reviews latent semantic analysis (LSA), a theory of meaning as well as a method for extracting that meaning from passages of text, based on statistical computations over a collection of documents. LSA as a theory of meaning defines a latent semantic space where documents and individual words are represented as vectors. LSA as a computational technique uses linear algebra to extract dimensions that represent that space. This representation enables the computation of similarity among terms and documents, categorization of terms and documents, and summarization of large collections of documents using automated procedures that mimic the way humans perform similar cognitive tasks. We present some technical details, various illustrative examples, and discuss a number of applications from linguistics, psychology, cognitive science, education, information science, and analysis of textual data in general. WIREs Cogn Sci 2013, 4:683-692. doi: 10.1002/wcs.1254 CONFLICT OF INTEREST: The author has declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website. PMID:26304272

  6. Learning multimodal latent attributes.

    PubMed

    Fu, Yanwei; Hospedales, Timothy M; Xiang, Tao; Gong, Shaogang

    2014-02-01

    The rapid development of social media sharing has created a huge demand for automatic media classification and annotation techniques. Attribute learning has emerged as a promising paradigm for bridging the semantic gap and addressing data sparsity via transferring attribute knowledge in object recognition and relatively simple action classification. In this paper, we address the task of attribute learning for understanding multimedia data with sparse and incomplete labels. In particular, we focus on videos of social group activities, which are particularly challenging and topical examples of this task because of their multimodal content and complex and unstructured nature relative to the density of annotations. To solve this problem, we 1) introduce a concept of semilatent attribute space, expressing user-defined and latent attributes in a unified framework, and 2) propose a novel scalable probabilistic topic model for learning multimodal semilatent attributes, which dramatically reduces requirements for an exhaustive accurate attribute ontology and expensive annotation effort. We show that our framework is able to exploit latent attributes to outperform contemporary approaches for addressing a variety of realistic multimedia sparse data learning tasks including: multitask learning, learning with label noise, N-shot transfer learning, and importantly zero-shot learning. PMID:24356351

  7. Effects of Heat and Momentum Addition Inside and Outside the Compound Sonic Point of the Solar Wind

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Webb, G. M.; McKenzie, J. F.

    2014-12-01

    We consider the effect of heat and momentum addition to the solar wind for a model including the effects of Alfven waves and plasma pressure (proton plus electron pressure). The mass flux per unit area in 1D flow maximizes when the flow speed equals the compound sound speed, including the effects of the Alfven wave pressure. We discuss the analogue of the Laval nozzle for the solar wind flow, and the dependence of the effective nozzle area as a function of radial distance, and the relationship of the nozzle area to the momentum equation and the Mach number of the flow. An analysis is carried out of the effects of heat and momentum addition to the wind, using a thin slice approximation, which leads to Rankine Hugoniot relations for weak deflagrations and detonations (i.e. the combustion Hugoniot). The linearized Hugoniot is used to analyze the effects of small momentum and energy addition to the wind in the thin slice approximation. We obtain the fully nonlinear Rankine Hugoniot equation solutions. The analysis also holds in the presence of Alfven waves, in which the wave energy exchange equation yields the wave action flux conservation law when their contribution to the compound sound speed is taken into account. The effective polytropic index γgamma and flow speed relative to the compound flow speed ahead of the slice play crucial roles in determining whether local acceleration or deceleration results. Some results are at first sight unexpected since γgamma for Alfven waves ranges from -1/2 (in sub-Alfvenic flow) to 3/2 in super-Alfvenic flow.

  8. A Latent Transition Model with Logistic Regression

    ERIC Educational Resources Information Center

    Chung, Hwan; Walls, Theodore A.; Park, Yousung

    2007-01-01

    Latent transition models increasingly include covariates that predict prevalence of latent classes at a given time or transition rates among classes over time. In many situations, the covariate of interest may be latent. This paper describes an approach for handling both manifest and latent covariates in a latent transition model. A Bayesian…

  9. Addition polyimide adhesives containing various end groups

    NASA Technical Reports Server (NTRS)

    Saint Clair, A. K.; Saint Clair, T. L.

    1982-01-01

    Addition polyimode oligomers have been synthesized from 3,3 prime, 4,4 prime-benzophenone tetracarboxylic acid dianhydride and 3,3 prime-methylenedianiline using a variety of latent crosslinking groups as end-caps. The nominal 1300 molecular weight imide prepolymers were isolated and characterized for solubility in amide, chlorinated and ether solvents, melt-flow and cure properties, glass transition temperature, and thermal stability on heating in an air atmosphere. Adhesive strengths of the polyimides were obtained both at ambient and elevated temperatures before and after aging at 232 C. Properties of the novel addition polyimides were compared to a known nadic end-capped adhesive, LARC-13.

  10. Latent heat and the Fourier law

    NASA Astrophysics Data System (ADS)

    Colangeli, M.; De Masi, A.; Presutti, E.

    2016-04-01

    We present computer simulations run with a stochastic cellular automaton which describes d = 1 particle systems connected to reservoirs which keep two different densities at the endpoints. We fix the parameters so that there is a phase transition (of the van der Waals type) and observe that if the densities at the boundaries are metastable then, after a transient, the system reaches an apparently stationary regime where the current flows from the reservoir with smaller density to the one with larger density.

  11. Latent heat characteristics of biobased oleochemical carbonates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oleochemical carbonates represent biobased materials that can be readily prepared through a carbonate interchange reaction between renewably available C10-C18 fatty alcohols. Although these carbonates have commercial use in cosmetics and lubricant applications, they have not been examined as phase ...

  12. Additive Manufacturing of 17-4 PH Stainless Steel: Post-processing Heat Treatment to Achieve Uniform Reproducible Microstructure

    NASA Astrophysics Data System (ADS)

    Cheruvathur, Sudha; Lass, Eric A.; Campbell, Carelyn E.

    2016-03-01

    17-4 precipitation hardenable (PH) stainless steel is a useful material when a combination of high strength and good corrosion resistance up to about 315°C is required. In the wrought form, this steel has a fully martensitic structure that can be strengthened by precipitation of fine Cu-rich face-centered cubic phase upon aging. When fabricated via additive manufacturing (AM), specifically laser powder-bed fusion, 17-4 PH steel exhibits a dendritic structure containing a substantial fraction of nearly 50% of retained austenite along with body centered cubic/martensite and fine niobium carbides preferentially aligned along interdendritic boundaries. The effect of post-build thermal processing on the material microstructure is studied in comparison to that of conventionally produced wrought 17-4 PH with the intention of creating a more uniform, fully martensitic microstructure. The recommended stress relief heat treatment currently employed in industry for post-processing of AM 17-4 PH steel is found to have little effect on the as-built dendritic microstructure. It is found that, by implementing the recommended homogenization heat treatment regimen of Aerospace Materials Specification 5355 for CB7Cu-1, a casting alloy analog to 17-4 PH, the dendritic solidification structure is eliminated, resulting in a microstructure containing about 90% martensite with 10% retained austenite.

  13. First principles based group additive values for the gas phase standard entropy and heat capacity of hydrocarbons and hydrocarbon radicals.

    PubMed

    Sabbe, Maarten K; De Vleeschouwer, Freija; Reyniers, Marie-Françoise; Waroquier, Michel; Marin, Guy B

    2008-11-27

    In this work a complete and consistent set of 95 Benson group additive values (GAVs) for standard entropies S(o) and heat capacities C(p)(o) of hydrocarbons and hydrocarbon radicals is presented. These GAVs include 46 groups, among which 25 radical groups, which, to the best of our knowledge, have not been reported before. The GAVs have been determined from a set of B3LYP/6-311G(d,p) ideal gas statistical thermodynamics values for 265 species, consistently with previously reported GAVs for standard enthalpies of formation. One-dimensional hindered rotor corrections for all internal rotations are included. The computational methodology has been compared to experimental entropies (298 K) for 39 species, with a mean absolute deviation (MAD) between experiment and calculation of 1.2 J mol(-1) K(-1), and to 46 experimental heat capacities (298 K) with a resulting MAD = 1.8 J mol(-1) K(-1). The constructed database allowed evaluation of corrections on S(o) and C(p)(o) for non-nearest-neighbor effects, which have not been determined previously. The group additive model predicts the S(o) and C(p)(o) within approximately 5 J mol(-1) K(-1) of the ab initio values for 11 of the 14 molecules of the test set, corresponding to an acceptable maximal deviation of a factor of 1.6 on the equilibrium coefficient. The obtained GAVs can be applied for the prediction of S(o) and C(p)(o) for a wide range of hydrocarbons and hydrocarbon radicals. The constructed database also allowed determination of a large set of hydrogen bond increments, which can be useful for the prediction of radical thermochemistry. PMID:18980365

  14. Inactivation of Salmonella Enteriditis and Salmonella Senftenberg in liquid whole egg using generally recognized as safe additives, ionizing radiation and heat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of combining irradiation followed by heat on Salmonella Enteriditis and Salmonella Senftenberg inoculated into liquid whole egg (LWE) with added nisin, EDTA, sorbic acid, carvacrol, or combinations of these GRAS additives was investigated. Synergistic reductions of Salmonella populations ...

  15. Latent-failure risk estimates for computer control

    NASA Technical Reports Server (NTRS)

    Dunn, William R.; Folsom, Rolfe A.; Green, Owen R.

    1991-01-01

    It is shown that critical computer controls employing unmonitored safety circuits are unsafe. Analysis supporting this result leads to two additional, important conclusions: (1) annual maintenance checks of safety circuit function do not, as widely believed, eliminate latent failure risk; (2) safety risk remains even if multiple, series-connected protection circuits are employed. Finally, it is shown analytically that latent failure risk is eliminated when continuous monitoring is employed.

  16. Additional double-wall roof in single-wall, closed, convective incubators: Impact on body heat loss from premature infants and optimal adjustment of the incubator air temperature.

    PubMed

    Delanaud, Stéphane; Decima, Pauline; Pelletier, Amandine; Libert, Jean-Pierre; Stephan-Blanchard, Erwan; Bach, Véronique; Tourneux, Pierre

    2016-09-01

    Radiant heat loss is high in low-birth-weight (LBW) neonates. Double-wall or single-wall incubators with an additional double-wall roof panel that can be removed during phototherapy are used to reduce Radiant heat loss. There are no data on how the incubators should be used when this second roof panel is removed. The aim of the study was to assess the heat exchanges in LBW neonates in a single-wall incubator with and without an additional roof panel. To determine the optimal thermoneutral incubator air temperature. Influence of the additional double-wall roof was assessed by using a thermal mannequin simulating a LBW neonate. Then, we calculated the optimal incubator air temperature from a cohort of human LBW neonate in the absence of the additional roof panel. Twenty-three LBW neonates (birth weight: 750-1800g; gestational age: 28-32 weeks) were included. With the additional roof panel, R was lower but convective and evaporative skin heat losses were greater. This difference can be overcome by increasing the incubator air temperature by 0.15-0.20°C. The benefit of an additional roof panel was cancelled out by greater body heat losses through other routes. Understanding the heat transfers between the neonate and the environment is essential for optimizing incubators. PMID:27387899

  17. The effect of additives on the speed of the crystallization front of xylitol with various degrees of supercooling

    SciTech Connect

    Seppaelae, Ari; Merilaeinen, Arttu; Wikstroem, Lisa; Kauranen, Pertti

    2010-07-15

    Some liquids can be kept in a supercooled or supersaturated metastable state for substantially long periods. Such liquids can be applied as long-term heat storage where the latent heat can be released when needed. As xylitol possesses a relatively high value of latent heat and as it can be easily supercooled, it has promising properties for this application. However, the speed of the crystallization of xylitol is low, leading to a low release rate of latent heat. Several additives have been experimentally tested for the purpose of accelerating the crystallization speed. The effect of the additives on the latent heat, on the melting temperatures, and on the long-term durability of the supercooled state was also measured. The highest speeds of the crystallization front, at a temperature of 22 C, were achieved with methanol as an additive leading to speeds 33 times higher in vertical experiments and in 170 times higher in horizontal ones than with pure xylitol. The improved speed of the crystallization front is mostly caused by the methanol flow currents generated as a result of the separation of methanol during crystallization, and to a lesser extent, as a result of the increase in the speed of the growth of the crystals. (author)

  18. Effect of Boron Addition and Initial Heat-Treatment Temperature on Microstructure and Mechanical Properties of Modified 9Cr-1Mo Steels Under Different Heat-Treatment Conditions

    NASA Astrophysics Data System (ADS)

    Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murty, B. S.

    2013-05-01

    The effect of initial heat treatment on microstructure and mechanical properties of boron-free and boron-containing modified 9Cr-1Mo steel (P91 and P91B, respectively) has been studied under different heat-treatment conditions. The prior austenite grains evolved in P91 steel, having different prior austenite grain sizes, were found to be similar in size after heat treatment in the range of 1073 K to 1448 K (800 °C to 1175 °C) for 5 minutes. The microstructural evolution in P91B steel having different prior austenite grain sizes appeared to be uniform when subjected to different heat-treatment temperatures with the prior austenite grain size being similar to that of initial grain size. Lath martensite was observed in P91B steel after all heat treatments. On the other hand, lath martensite was observed in P91 steel only when subjected to high-temperature heat treatment, whereas subgrain/substructure as well as coarse precipitates were observed after a lower temperature heat treatment. Large differences in the hardness/strength values between different microstructures corresponding to coarse-grained heat-affected zone (CGHAZ) and intercritical HAZ (ICHAZ) of P91 steel weldment were due to the distinct difference in these microstructures. The difference in hardness/strength values between the CGHAZ and ICHAZ was found to be insignificant in P91B steel under similar heat-treatment conditions.

  19. A Magnetically Responsive Polydiacetylene Precursor for Latent Fingerprint Analysis.

    PubMed

    Lee, Joosub; Lee, Chan Woo; Kim, Jong-Man

    2016-03-01

    A magnetically responsive diacetylene (DA) powder was developed for the visualization of latent fingerprints. A mixture of the DA and magnetite nanoparticles, applied to a surface containing latent fingermarks, becomes immobilized along the ridge patterns of the fingerprints when a magnetic field is applied. Alignment along the ridge structures is a consequence of favorable hydrophobic interactions occurring between the long alkyl chains in the DAs and the lipid-rich, sebaceous latent fingermarks. UV irradiation of the DA-magnetite composite immobilized on the latent fingerprint results in the generation of blue-colored PDAs. Heat treatment of the blue-colored image promotes a blue-to-red transition as well as fluorescence turn-on. A combination of the aligned pale brown-colored monomeric state, UV irradiation generated blue-colored PDA state, as well as the heat treatment generated red-colored and fluorescent PDA state enables efficient visual imaging of a latent fingerprint, which is deposited on various colored solid surfaces. PMID:26895283

  20. Effect of additional heat treatment of 2024-T3 on the growth of fatigue crack in air and in vacuum

    NASA Technical Reports Server (NTRS)

    Louwaard, E. P.

    1986-01-01

    In order to determine the influence of ductility on the fatigue crack growth rate of aluminum alloys, fatigue tests were carried out on central notched specimens of 2024-T3 and 2024-T8 sheet material. The 2024-T8 material was obtained by an additional heat treatment applied on 2024-T3 (18 hours at 192 C), which increased the static yield strength from 43.6 to 48.9 kgf/sq mm. A change in the ultimate strength was not observed. Fatigue tests were carried out on both materials in humid air and in high vacuum. According to a new crack propagation model, crack extension is supported to be caused by a slip-related process and debonding triggered by the environment. This model predicts an effect of the ductility on the crack growth rate which should be smaller in vacuum than in humid air; however, this was not confirmed. In humid air the crack-growth rate in 2024-T8 was about 2 times faster than in 2024-T3, while in vacuum the ratio was about 2.5. Crack closure measurements gave no indications that crack closure played a significant role in both materials. Some speculative explanations are briefly discussed.

  1. Detecting Mixtures from Structural Model Differences Using Latent Variable Mixture Modeling: A Comparison of Relative Model Fit Statistics

    ERIC Educational Resources Information Center

    Henson, James M.; Reise, Steven P.; Kim, Kevin H.

    2007-01-01

    The accuracy of structural model parameter estimates in latent variable mixture modeling was explored with a 3 (sample size) [times] 3 (exogenous latent mean difference) [times] 3 (endogenous latent mean difference) [times] 3 (correlation between factors) [times] 3 (mixture proportions) factorial design. In addition, the efficacy of several…

  2. Predicting Latent Class Scores for Subsequent Analysis

    ERIC Educational Resources Information Center

    Petersen, Janne; Bandeen-Roche, Karen; Budtz-Jorgensen, Esben; Larsen, Klaus Groes

    2012-01-01

    Latent class regression models relate covariates and latent constructs such as psychiatric disorders. Though full maximum likelihood estimation is available, estimation is often in three steps: (i) a latent class model is fitted without covariates; (ii) latent class scores are predicted; and (iii) the scores are regressed on covariates. We propose…

  3. Additional cooling and heating load improvements in seasonal performance modeling of room and central air conditioners and heat pumps. Topical report, Subtask 3. 2

    SciTech Connect

    Not Available

    1980-04-09

    The study focuses on improving the load modeling technique of Seasonal Performance Model (SPM) in order to estimate a more realistic load for seasonal analysis calculations on an hourly basis. A computer simulation program, Seasonal Performance Model Load (SPMLD), was used to calculate the cooling and heating loads for a typical residence in Caribou, Maine; Columbia, Missouri; and Fort Worth, Texas. The derivation of the SPMLD is described and changes made to improve cooling and heating load estimates are identified. (MCW)

  4. Gene variants associated with antisocial behaviour: A latent variable approach

    PubMed Central

    Bentley, Mary Jane; Lin, Haiqun; Fernandez, Thomas V.; Lee, Maria; Yrigollen, Carolyn M.; Pakstis, Andrew J.; Katsovich, Liliya; Olds, David L.; Grigorenko, Elena L.; Leckman, James F.

    2013-01-01

    Objective The aim of this study was to determine if a latent variable approach might be useful in identifying shared variance across genetic risk alleles that is associated with antisocial behaviour at age 15 years. Methods Using a conventional latent variable approach, we derived an antisocial phenotype in 328 adolescents utilizing data from a 15-year follow-up of a randomized trial of a prenatal and infancy nurse-home visitation program in Elmira, New York. We then investigated, via a novel latent variable approach, 450 informative genetic polymorphisms in 71 genes previously associated with antisocial behaviour, drug use, affiliative behaviours, and stress response in 241 consenting individuals for whom DNA was available. Haplotype and Pathway analyses were also performed. Results Eight single-nucleotide polymorphisms (SNPs) from 8 genes contributed to the latent genetic variable that in turn accounted for 16.0% of the variance within the latent antisocial phenotype. The number of risk alleles was linearly related to the latent antisocial variable scores. Haplotypes that included the putative risk alleles for all 8 genes were also associated with higher latent antisocial variable scores. In addition, 33 SNPs from 63 of the remaining genes were also significant when added to the final model. Many of these genes interact on a molecular level, forming molecular networks. The results support a role for genes related to dopamine, norepinephrine, serotonin, glutamate, opioid, and cholinergic signaling as well as stress response pathways in mediating susceptibility to antisocial behaviour. Conclusions This preliminary study supports use of relevant behavioural indicators and latent variable approaches to study the potential “co-action” of gene variants associated with antisocial behaviour. It also underscores the cumulative relevance of common genetic variants for understanding the etiology of complex behaviour. If replicated in future studies, this approach may

  5. Incorporating comorbidities into latent treatment pattern mining for clinical pathways.

    PubMed

    Huang, Zhengxing; Dong, Wei; Ji, Lei; He, Chunhua; Duan, Huilong

    2016-02-01

    In healthcare organizational settings, the design of a clinical pathway (CP) is challenging since patients following a particular pathway may have not only one single first-diagnosis but also several typical comorbidities, and thus it requires different disciplines involved to put together their partial knowledge about the overall pathway. Although many data mining techniques have been proposed to discover latent treatment information for CP analysis and reconstruction from a large volume of clinical data, they are specific to extract nontrivial information about the therapy and treatment of the first-diagnosis. The influence of comorbidities on adopting essential treatments is crucial for a pathway but has seldom been explored. This study proposes to extract latent treatment patterns that characterize essential treatments for both first-diagnosis and typical comorbidities from the execution data of a pathway. In particular, we propose a generative statistical model to extract underlying treatment patterns, unveil the latent associations between diagnosis labels (including both first-diagnosis and comorbidities) and treatments, and compute the contribution of comorbidities in these patterns. The proposed model extends latent Dirichlet allocation with an additional layer for diagnosis modeling. It first generates a set of latent treatment patterns from diagnosis labels, followed by sampling treatments from each pattern. We verify the effectiveness of the proposed model on a real clinical dataset containing 12,120 patient traces, which pertain to the unstable angina CP. Three treatment patterns are discovered from data, indicating latent correlations between comorbidities and treatments in the pathway. In addition, a possible medical application in terms of treatment recommendation is provided to illustrate the potential of the proposed model. Experimental results indicate that our approach can discover not only meaningful latent treatment patterns exhibiting

  6. Effect of heat treatment, pH, sugar concentration, and metal addition on green color retention in homogenized puree of Thompson seedless grape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Homogenized puree of Thompson seedless (Vitis vinifera ‘Thompson Seedless’) grape was treated under different conditions, including heating time (5-30 min), temperature (20-80°C) and pH (2-10). Treatments with separate additions of glucose, fructose, and sucrose at concentrations of 100-600 g/L and ...

  7. Effect of cerium addition on casting/chill interfacial heat flux and casting surface profile during solidification of Al-14%Si alloy

    NASA Astrophysics Data System (ADS)

    Vijeesh, V.; Prabhu, K. N.

    2016-03-01

    In the present investigation, Al-14 wt. % Si alloy was solidified against copper, brass and cast iron chills, to study the effect of Ce melt treatment on casting/chill interfacial heat flux transients and casting surface profile. The heat flux across the casting/chill interface was estimated using inverse modelling technique. On addition of 1.5% Ce, the peak heat flux increased by about 38%, 42% and 43% for copper, brass and cast iron chills respectively. The effect of Ce addition on casting surface texture was analyzed using a surface profilometer. The surface profile of the casting and the chill surfaces clearly indicated the formation of an air gap at the periphery of the casting. The arithmetic average value of the profile departure from the mean line (Ra) and arithmetical mean of the absolute departures of the waviness profile from the centre line (Wa) were found to decrease on Ce addition. The interfacial gap width formed for the unmodified and Ce treated casting surfaces at the periphery were found to be about 35µm and 13µm respectively. The enhancement in heat transfer on addition of Ce addition was attributed to the lowering of the surface tension of the liquid melt. The gap width at the interface was used to determine the variation of heat transfer coefficient (HTC) across the chill surface after the formation of stable solid shell. It was found that the HTC decreased along the radial direction for copper and brass chills and increased along radial direction for cast iron chills.

  8. Additional heat treatment of non-porous coatings obtained on medium carbon steel substrates by electron beam cladding of a Ti-Mo-C powder composition

    NASA Astrophysics Data System (ADS)

    Mul, D. O.; Drobyaz, E. A.; Zimoglyadova, T. A.; Bataev, V. A.; Lazurenko, D. V.; Shevtsova, L. I.

    2016-04-01

    The structure and microhardness of surface layers, obtained by non-vacuum electron beam cladding of Ti-Mo-C powder mixture on a steel substrate after different types of heat treatment, were investigated. After cladding samples were heat treated in a furnace at 200...500 °C, as well as quenched at 860 ° C and then underwent high-temperature tempering. Heat treatment of cladded coatings induced tempering of martensite and precipitation of cementite particles (Fe3C). Transmission electron microscopy of the samples after heating and holding at 300 ° C revealed precipitation of nanosized cubical TiC particles. The formation of hard nanosized particles led to the surface layer microhardness growth. The highest level of microhardness (which was 1.2...1.5-fold higher in comparison with coating microhardness after heat treatment) was achieved after heating of the claded material at 300 °C and 400 °C Additional quenching of samples at 860 °C did not increase the microhardness level.

  9. Improving high temperature creep resistance of reduced activation steels by addition of nitrogen and intermediate heat treatment

    NASA Astrophysics Data System (ADS)

    Liu, W. B.; Zhang, C.; Xia, Z. X.; Yang, Z. G.

    2014-12-01

    In the present study, we report an enhanced high-temperature creep resistance in reduced activation ferrite/martensite (RAFM) steels, by introducing nitrogen (0.035 wt%, M3 steel) and employing a novel intermediate heat treatment I-Q-T (intermediate treatment, quenching and tempering). In comparison with all the control groups, the uniaxial tests of the I-Q-T treated M3 steel showed significant increase in rupture time and decrease in elongation. The microstructures of the samples were further characterized to elucidate the origin of the enhanced creep resistance. It is found that, by introducing nitrogen, the primary TaC particles were refined; by employing the I-Q-T heat treatment, the dispersed fine secondary MX precipitates, as well as the lath subgrains containing high-density dislocations, were increased: all are responsible for the improved creep resistance.

  10. Measured effects of retrofits -- a refrigerant oil additive and a condenser spray device -- on the cooling performance of a heat pump

    SciTech Connect

    Levins, W.P.; Sand, J.R.; Baxter, V.D.; Linkous, R.L.

    1996-05-01

    A 15-year old, 3-ton single package air-to-air heat pump was tested in laboratory environmental chambers simulating indoor and outdoor conditions. After documenting initial performance, the unit was retrofitted with a prototype condenser water-spray device and retested. Results at standard ARI cooling rating conditions (95 F outdoor dry bulb and 80/67 F indoor dry bulb/wet bulb temperatures) showed the capacity increased by about 7%, and the electric power demand dropped by about 8%, resulting in a steady-state EER increase of 17%. Suction and discharge pressures were reduced by 7 and 37 psi, respectively. A refrigerant oil additive formulated to enhance refrigerant-side heat transfer was added at a dose of one ounce per ton of rated capacity, and the unit was tested for several days at the same 95 F outdoor conditions and showed essentially no increase in capacity, and a slight 3% increase in steady-state EER. Adding more additive lowered the EER slightly. Suction and discharge pressures were essentially unchanged. The short-term testing showed that the condenser-spray device was effective in increasing the cooling capacity and lowering the electrical demand on an old and relatively inefficient heat pump, but the refrigerant additive had little effect on the cooling performance of the unit. Sprayer issues to be resolved include the effect of a sprayer on a new, high-efficiency air conditioner/heat pump, reliable long-term operation, and economics.

  11. Latent Growth Modeling for Logistic Response Functions

    ERIC Educational Resources Information Center

    Choi, Jaehwa; Harring, Jeffrey R.; Hancock, Gregory R.

    2009-01-01

    Throughout much of the social and behavioral sciences, latent growth modeling (latent curve analysis) has become an important tool for understanding individuals' longitudinal change. Although nonlinear variations of latent growth models appear in the methodological and applied literature, a notable exclusion is the treatment of growth following…

  12. A Multicomponent Latent Trait Model for Diagnosis

    ERIC Educational Resources Information Center

    Embretson, Susan E.; Yang, Xiangdong

    2013-01-01

    This paper presents a noncompensatory latent trait model, the multicomponent latent trait model for diagnosis (MLTM-D), for cognitive diagnosis. In MLTM-D, a hierarchical relationship between components and attributes is specified to be applicable to permit diagnosis at two levels. MLTM-D is a generalization of the multicomponent latent trait…

  13. A Dynamic Model for Induced Reactivation of Latent Virus

    PubMed Central

    Kepler, G.M.; Nguyen, H.K.; Webster-Cyriaque, J.; Banks, H.T.

    2007-01-01

    We develop a deterministic mathematical model to describe reactivation of latent virus by chemical inducers. This model is applied to the reactivation of latent KSHV in BCBL-1 cell cultures with butyrate as the inducing agent. Parameters for the model are first estimated from known properties of the exponentially growing, uninduced cell cultures. Additional parameters that are necessary to describe induction are determined from fits to experimental data from the literature. Our initial model provides good agreement with two independent sets of experimental data, but also points to the need for a new class of experiments which are required for further understanding of the underlying mechanisms. PMID:17045614

  14. Accuracy and reliability of forensic latent fingerprint decisions

    PubMed Central

    Ulery, Bradford T.; Hicklin, R. Austin; Buscaglia, JoAnn; Roberts, Maria Antonia

    2011-01-01

    The interpretation of forensic fingerprint evidence relies on the expertise of latent print examiners. The National Research Council of the National Academies and the legal and forensic sciences communities have called for research to measure the accuracy and reliability of latent print examiners’ decisions, a challenging and complex problem in need of systematic analysis. Our research is focused on the development of empirical approaches to studying this problem. Here, we report on the first large-scale study of the accuracy and reliability of latent print examiners’ decisions, in which 169 latent print examiners each compared approximately 100 pairs of latent and exemplar fingerprints from a pool of 744 pairs. The fingerprints were selected to include a range of attributes and quality encountered in forensic casework, and to be comparable to searches of an automated fingerprint identification system containing more than 58 million subjects. This study evaluated examiners on key decision points in the fingerprint examination process; procedures used operationally include additional safeguards designed to minimize errors. Five examiners made false positive errors for an overall false positive rate of 0.1%. Eighty-five percent of examiners made at least one false negative error for an overall false negative rate of 7.5%. Independent examination of the same comparisons by different participants (analogous to blind verification) was found to detect all false positive errors and the majority of false negative errors in this study. Examiners frequently differed on whether fingerprints were suitable for reaching a conclusion. PMID:21518906

  15. Interrater Agreement Evaluation: A Latent Variable Modeling Approach

    ERIC Educational Resources Information Center

    Raykov, Tenko; Dimitrov, Dimiter M.; von Eye, Alexander; Marcoulides, George A.

    2013-01-01

    A latent variable modeling method for evaluation of interrater agreement is outlined. The procedure is useful for point and interval estimation of the degree of agreement among a given set of judges evaluating a group of targets. In addition, the approach allows one to test for identity in underlying thresholds across raters as well as to identify…

  16. An Alternative Approach for Nonlinear Latent Variable Models

    ERIC Educational Resources Information Center

    Mooijaart, Ab; Bentler, Peter M.

    2010-01-01

    In the last decades there has been an increasing interest in nonlinear latent variable models. Since the seminal paper of Kenny and Judd, several methods have been proposed for dealing with these kinds of models. This article introduces an alternative approach. The methodology involves fitting some third-order moments in addition to the means and…

  17. Mechanism of coercivity enhancement by Ag addition in FePt-C granular films for heat assisted magnetic recording media

    SciTech Connect

    Varaprasad, B. S. D. Ch. S.; Takahashi, Y. K. Wang, J.; Hono, K.; Ina, T.; Nakamura, T.; Ueno, W.; Nitta, K.; Uruga, T.

    2014-06-02

    We investigated the Ag distribution in a FePtAg-C granular film that is under consideration for a heat assisted magnetic recording medium by aberration-corrected scanning transmission electron microscope-energy dispersive X-ray spectroscopy and X-ray absorption fine structure. Ag is rejected from the core of FePt grains during the deposition, forming Ag-enriched shell surrounding L1{sub 0}-ordered FePt grains. Since Ag has no solubility in both Fe and Pt, the rejection of Ag induces atomic diffusions thereby enhancing the kinetics of the L1{sub 0}-order in the FePt grains.

  18. Latent Viruses: A Space Travel Hazard??

    NASA Technical Reports Server (NTRS)

    Ling, P. D.; Peng, R. S.; Pierson, D.; Lednicky, J.; Butel, J. S.

    1999-01-01

    A major issue associated with long-duration space flight is the possibility of infectious disease causing an unacceptable medical risk to crew members. Our proposal is designed to gain information that addresses several issues outlined in the Immunology/Infectious disease critical path. The major hypothesis addressed is that space flight causes alterations in the immune system that may allow latent viruses which are endogenous in the human population to reactivate and shed to higher levels than normal which can affect the health of crew members during a long term space-flight mission. We will initially focus our studies on the human herpesviruses and human polyomaviruses which are important pathogens known to establish latent infections in the human population. Both primary infection and reactivation from latent infection with this group of viruses can cause a variety of illnesses that result in morbidity and occasionally mortality of infected individuals. Effective vaccines exist for only one of the eight known human herpesviruses and the vaccine itself can still reactivate from latent infection. Available antivirals are of limited use and are effective against only a few of the human herpesviruses. Although most individuals display little if any clinical consequences from latent infection, events which alter immune function such as immunosuppressive therapy following solid organ transplantation are known to increase the risk of developing complications as a result of latent virus reactivation. This proposal will measure both the frequency and magnitude of viral shedding and genome loads in the blood from humans participating in activities that serve as ground based models of space flight conditions. Our initial goal is to develop sensitive quantitative competitive PCR- based assays (QC-PCR) to detect the herpesvirus Epstein-Barr virus (EBV), and the polyomaviruses SV40, BKV, and JCV. Using these assays we will establish baseline patterns of viral genome load in

  19. Phase Change Heat Transfer Device for Process Heat Applications

    SciTech Connect

    Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

    2010-10-01

    The next generation nuclear plant (NGNP) will most likely produce electricity and process heat, with both being considered for hydrogen production. To capture nuclear process heat, and transport it to a distant industrial facility requires a high temperature system of heat exchangers, pumps and/or compressors. The heat transfer system is particularly challenging not only due to the elevated temperatures (up to approx.1300 K) and industrial scale power transport (=50MW), but also due to a potentially large separation distance between the nuclear and industrial plants (100+m) dictated by safety and licensing mandates. The work reported here is the preliminary analysis of two-phase thermosyphon heat transfer performance with alkali metals. A thermosyphon is a thermal device for transporting heat from one point to another with quite extraordinary properties. In contrast to single-phased forced convective heat transfer via ‘pumping a fluid’, a thermosyphon (also called a wickless heat pipe) transfers heat through the vaporization/condensing process. The condensate is further returned to the hot source by gravity, i.e., without any requirement of pumps or compressors. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. Two-phase heat transfer by a thermosyphon has the advantage of high enthalpy transport that includes the sensible heat of the liquid, the latent heat of vaporization, and vapor superheat. In contrast, single-phase forced convection transports only the sensible heat of the fluid. Additionally, vapor-phase velocities within a thermosyphon are much greater than single-phase liquid velocities within a forced convective loop. Thermosyphon performance can be limited by the sonic limit (choking) of vapor flow and/or by condensate entrainment. Proper thermosyphon requires analysis of both.

  20. Additive Manufacturing/Diagnostics via the High Frequency Induction Heating of Metal Powders: The Determination of the Power Transfer Factor for Fine Metallic Spheres

    SciTech Connect

    Rios, Orlando; Radhakrishnan, Balasubramaniam; Caravias, George; Holcomb, Matthew

    2015-03-11

    Grid Logic Inc. is developing a method for sintering and melting fine metallic powders for additive manufacturing using spatially-compact, high-frequency magnetic fields called Micro-Induction Sintering (MIS). One of the challenges in advancing MIS technology for additive manufacturing is in understanding the power transfer to the particles in a powder bed. This knowledge is important to achieving efficient power transfer, control, and selective particle heating during the MIS process needed for commercialization of the technology. The project s work provided a rigorous physics-based model for induction heating of fine spherical particles as a function of frequency and particle size. This simulation improved upon Grid Logic s earlier models and provides guidance that will make the MIS technology more effective. The project model will be incorporated into Grid Logic s power control circuit of the MIS 3D printer product and its diagnostics technology to optimize the sintering process for part quality and energy efficiency.

  1. Non-additive response of blends of rice and potato starch during heating at intermediate water contents: A differential scanning calorimetry and proton nuclear magnetic resonance study.

    PubMed

    Bosmans, Geertrui M; Pareyt, Bram; Delcour, Jan A

    2016-02-01

    The impact of different hydration levels, on gelatinization of potato starch (PS), rice starch (RS) and a 1:1 blend thereof, was investigated by differential scanning calorimetry and related to nuclear magnetic resonance proton distributions of hydrated samples, before and after heating. At 20% or 30% hydration, the visual appearance of all samples was that of a wet powder, and limited, if any, gelatinization occurred upon heating. At 30% hydration, changes in proton distributions were observed and related to plasticization of amorphous regions in the granules. At 50% hydration, the PS-RS blend appeared more liquid-like than other hydrated samples and showed more pronounced gelatinization than expected based on additive behavior of pure starches. This was due to an additional mobile water fraction in the unheated PS-RS blend, originating from differences in water distribution due to altered stacking of granules and/or altered hydration of PS due to presence of cations in RS. PMID:26304387

  2. Latent Variable Models of Need for Uniqueness.

    PubMed

    Tepper, K; Hoyle, R H

    1996-10-01

    The theory of uniqueness has been invoked to explain attitudinal and behavioral nonconformity with respect to peer-group, social-cultural, and statistical norms, as well as the development of a distinctive view of self via seeking novelty goods, adopting new products, acquiring scarce commodities, and amassing material possessions. Present research endeavors in psychology and consumer behavior are inhibited by uncertainty regarding the psychometric properties of the Need for Uniqueness Scale, the primary instrument for measuring individual differences in uniqueness motivation. In an important step toward facilitating research on uniqueness motivation, we used confirmatory factor analysis to evaluate three a priori latent variable models of responses to the Need for Uniqueness Scale. Among the a priori models, an oblique three-factor model best accounted for commonality among items. Exploratory factor analysis followed by estimation of unrestricted three- and four-factor models revealed that a model with a complex pattern of loadings on four modestly correlated factors may best explain the latent structure of the Need for Uniqueness Scale. Additional analyses evaluated the associations among the three a priori factors and an array of individual differences. Results of those analyses indicated the need to distinguish among facets of the uniqueness motive in behavioral research. PMID:26788594

  3. A Framework for Reproducible Latent Fingerprint Enhancements.

    PubMed

    Carasso, Alfred S

    2014-01-01

    Photoshop processing of latent fingerprints is the preferred methodology among law enforcement forensic experts, but that appproach is not fully reproducible and may lead to questionable enhancements. Alternative, independent, fully reproducible enhancements, using IDL Histogram Equalization and IDL Adaptive Histogram Equalization, can produce better-defined ridge structures, along with considerable background information. Applying a systematic slow motion smoothing procedure to such IDL enhancements, based on the rapid FFT solution of a Lévy stable fractional diffusion equation, can attenuate background detail while preserving ridge information. The resulting smoothed latent print enhancements are comparable to, but distinct from, forensic Photoshop images suitable for input into automated fingerprint identification systems, (AFIS). In addition, this progressive smoothing procedure can be reexamined by displaying the suite of progressively smoother IDL images. That suite can be stored, providing an audit trail that allows monitoring for possible loss of useful information, in transit to the user-selected optimal image. Such independent and fully reproducible enhancements provide a valuable frame of reference that may be helpful in informing, complementing, and possibly validating the forensic Photoshop methodology. PMID:26601028

  4. A Framework for Reproducible Latent Fingerprint Enhancements

    PubMed Central

    Carasso, Alfred S.

    2014-01-01

    Photoshop processing1 of latent fingerprints is the preferred methodology among law enforcement forensic experts, but that appproach is not fully reproducible and may lead to questionable enhancements. Alternative, independent, fully reproducible enhancements, using IDL Histogram Equalization and IDL Adaptive Histogram Equalization, can produce better-defined ridge structures, along with considerable background information. Applying a systematic slow motion smoothing procedure to such IDL enhancements, based on the rapid FFT solution of a Lévy stable fractional diffusion equation, can attenuate background detail while preserving ridge information. The resulting smoothed latent print enhancements are comparable to, but distinct from, forensic Photoshop images suitable for input into automated fingerprint identification systems, (AFIS). In addition, this progressive smoothing procedure can be reexamined by displaying the suite of progressively smoother IDL images. That suite can be stored, providing an audit trail that allows monitoring for possible loss of useful information, in transit to the user-selected optimal image. Such independent and fully reproducible enhancements provide a valuable frame of reference that may be helpful in informing, complementing, and possibly validating the forensic Photoshop methodology. PMID:26601028

  5. Chemical TOPAZ: Modifications to the heat transfer code TOPAZ: The addition of chemical reaction kinetics and chemical mixtures

    SciTech Connect

    Nichols, A.L. III.

    1990-06-07

    This is a report describing the modifications which have been made to the heat flow code TOPAZ to allow the inclusion of thermally controlled chemical kinetics. This report is broken into parts. The first part is an introduction to the general assumptions and theoretical underpinning that were used to develop the model. The second section describes the changes that have been implemented into the code. The third section is the users manual for the input for the code. The fourth section is a compilation of hints, common errors, and things to be aware of while you are getting started. The fifth section gives a sample problem using the new code. This manual addenda is written with the presumption that most readers are not fluent with chemical concepts. Therefore, we shall in this section endeavor to describe the requirements that must be met before chemistry can occur and how we have modeled the chemistry in the code.

  6. Turbulence structure of drag-reducing surfactant solution in two-dimensional channel with additional heat transfer enhancement method

    SciTech Connect

    Li, P.W.; Daisaka, H.; Kawaguchi, Y.; Yabe, A.; Hishida, K.; Maeda, M.

    1999-07-01

    The turbulent characteristics of a surfactant water solution in changing from drag-reducing flow to turbulent flow inside a two-dimensional smooth channel and in changing from turbulent flow to drag-reducing flow in the same channel with a mesh plug were investigated through LDV measurement in this study. The mesh plug was used to exert high shear stress to destroy micelle structures in the surfactant solution so that turbulence could be produced for better heat transfer. The two-component LDV system was installed on a movable platform, which could be moved streamwise of the flow to measure the two-dimensional velocity at different stations downstream from the mesh plug. The surfactant tested was Cetyltrimethyl ammonium chloride (C{sub 16}H{sub 33}N(CH{sub 3}){sub 3}Cl, abbreviated as CTAC). Local tap water was used as solvent and same weight concentration of sodium salicylate was used as the counter-ion material. The investigation of turbulent parameters for the drag-reducing flow with increasing Reynolds number showed that when the Reynolds number exceeded the drag-reducing region, the turbulent character was the same as that of water. The turbulent parameters of surfactant flow downstream the mesh plug showed that the high heat transfer region had the same turbulent intensity as that of water flow. As the critical Reynolds number was approached, it became easier to obtain such a turbulent region by mesh plug. In such cases, the mesh helped to create high wall shear stress and therefore to destroy the super-ordered structures of rod-like micelles for introducing turbulence. However, it was found that the turbulent intensities of the velocity gradually decreased to the same as those of drag-reducing flow downstream from the mesh because the mesh plug only produced a local high shear stress.

  7. A Herpesviral Lytic Protein Regulates the Structure of Latent Viral Chromatin

    PubMed Central

    Raja, Priya; Lee, Jennifer S.; Pan, Dongli; Pesola, Jean M.; Coen, Donald M.

    2016-01-01

    ABSTRACT Latent infections by viruses usually involve minimizing viral protein expression so that the host immune system cannot recognize the infected cell through the viral peptides presented on its cell surface. Herpes simplex virus (HSV), for example, is thought to express noncoding RNAs such as latency-associated transcripts (LATs) and microRNAs (miRNAs) as the only abundant viral gene products during latent infection. Here we describe analysis of HSV-1 mutant viruses, providing strong genetic evidence that HSV-infected cell protein 0 (ICP0) is expressed during establishment and/or maintenance of latent infection in murine sensory neurons in vivo. Studies of an ICP0 nonsense mutant virus showed that ICP0 promotes heterochromatin and latent and lytic transcription, arguing that ICP0 is expressed and functional. We propose that ICP0 promotes transcription of LATs during establishment or maintenance of HSV latent infection, much as it promotes lytic gene transcription. This report introduces the new concept that a lytic viral protein can be expressed during latent infection and can serve dual roles to regulate viral chromatin to optimize latent infection in addition to its role in epigenetic regulation during lytic infection. An additional implication of the results is that ICP0 might serve as a target for an antiviral therapeutic acting on lytic and latent infections. PMID:27190217

  8. Hippocampus NMDA receptors selectively mediate latent extinction of place learning.

    PubMed

    Goodman, Jarid; Gabriele, Amanda; Packard, Mark G

    2016-09-01

    Extinction of maze learning may be achieved with or without the animal performing the previously acquired response. In typical "response extinction," animals are given the opportunity to make the previously acquired approach response toward the goal location of the maze without reinforcement. In "latent extinction," animals are not given the opportunity to make the previously acquired response and instead are confined to the previous goal location without reinforcement. Previous evidence indicates that the effectiveness of these protocols may depend on the type of memory being extinguished. Thus, one aim of the present study was to further examine the effectiveness of response and latent extinction protocols across dorsolateral striatum (DLS)-dependent response learning and hippocampus-dependent place learning tasks. In addition, previous neural inactivation experiments indicate a selective role for the hippocampus in latent extinction, but have not investigated the precise neurotransmitter mechanisms involved. Thus, the present study also examined whether latent extinction of place learning might depend on NMDA receptor activity in the hippocampus. In experiment 1, adult male Long-Evans rats were trained in a response learning task in a water plus-maze, in which animals were reinforced to make a consistent body-turn response to reach an invisible escape platform. Results indicated that response extinction, but not latent extinction, was effective at extinguishing memory in the response learning task. In experiment 2, rats were trained in a place learning task, in which animals were reinforced to approach a consistent spatial location containing the hidden escape platform. In experiment 2, animals also received intra-hippocampal infusions of the NMDA receptor antagonist 2-amino-5-phosphopentanoic acid (AP5; 5.0 or 7.5 ug/0.5 µg) or saline vehicle immediately before response or latent extinction training. Results indicated that both extinction protocols were

  9. Influence of additives on the increase of the heating value of Bayah's coal with upgrading brown coal (UBC) method

    NASA Astrophysics Data System (ADS)

    Heriyanto, Heri; Widya Ernayati, K.; Umam, Chairul; Margareta, Nita

    2015-12-01

    UBC (upgrading brown coal) is a method of improving the quality of coal by using oil as an additive. Through processing in the oil media, not just the calories that increase, but there is also water repellent properties and a decrease in the tendency of spontaneous combustion of coal products produced. The results showed a decrease in the water levels of natural coal bayah reached 69%, increase in calorific value reached 21.2%. Increased caloric value and reduced water content caused by the water molecules on replacing seal the pores of coal by oil and atoms C on the oil that is bound to increase the percentage of coal carbon. As a result of this experiment is, the produced coal has better calorific value, the increasing of this new calorific value up to 23.8% with the additive waste lubricant, and the moisture content reduced up to 69.45%.

  10. Optimization of microwave heating in an existing cubicle cavity by incorporating additional wave guide and control components

    SciTech Connect

    Erle, R.R.; Eschen, V.G.; Sprenger, G.S.

    1995-04-01

    The use of microwave energy to thermally treat Low Level (LLW), Transuranic (TRU), and mixed waste has been under development at the Rocky Flats Environmental Technology Site (Site) since 1986. During that time, the technology has progressed from bench-scale tests, through pilot-scale tests, and finally to a full-scale demonstration unit. Experimental operations have been conducted on a variety of non-radioactive surrogates and actual radioactive waste forms. Through these studies and development efforts, the Microwave Vitrification Engineering Team (MVET) at Rocky Flats has successfully proven the application of microwave energy for waste treatment operations. In the microwave solidification process, microwave energy is used to heat a mixture of waste and glass frit to produce a vitrified product that meets all the current acceptance criteria at the final disposal sites. All of the development to date has utilized a multi-mode microwave system to provide the energy to treat the materials. Currently, evaluations are underway on modifications to the full-scale demonstration system that provide a single-mode operation as a possible method to optimize the system. This poster presentation describes the modifications made to allow the single-mode operation.

  11. The Effect of Al2O3 Addition on the Thermal Diffusivity of Heat Activated Acrylic Resin

    PubMed Central

    Atla, Jyothi; Manne, Prakash; Gopinadh, A.; Sampath, Anche; Muvva, Suresh Babu; Kishore, Krishna; Sandeep, Chiramana; Chittamsetty, Harika

    2013-01-01

    Aim: This study aimed at investigating the effect of adding 5% to 20% by weight aluminium oxide powder (Al2O3) on thermal diffusivity of heat–polymerized acrylic resin. Material and Methods: Twenty five cylindrical test specimens with an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). The specimens were divided into five groups (5 specimens/group) which were coded A to E. Group A was the control group (unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with 5%, 10%, 15%, and 20% Al2O3 by weight. Results were analysed by using one–way analysis of variance (ANOVA). Results: Test specimens which belonged to Group E showed the highest mean thermal diffusivity value of 10.7mm2/sec, followed by D (9.09mm2/sec), C (8.49mm2/sec), B(8.28mm2/sec) and A(6.48mm2/sec) groups respectively. Thermal diffusivities of the reinforced acrylic resins were found to be significantly higher than that of the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler. Conclusion: Al2O3 fillers have potential to provide increased thermal diffusivity. Increasing the heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction. PMID:24086917

  12. Effects of Al Content and Addition of Third Element on Fabrication of Ti-Al Intermetallic Coatings by Heat Treatment of Warm-Sprayed Precursors

    NASA Astrophysics Data System (ADS)

    Sienkiewicz, J.; Kuroda, S.; Minagawa, K.; Murakami, H.; Araki, H.; Kurzydłowski, K. J.

    2015-06-01

    Four powder mixtures of titanium and aluminum with 50:50, 40:60, 30:70, and 20:80 atomic ratios were used as feedstock for Warm Spray process to produce composite coatings. A two-stage heat treatment at 600 and 1000 °C was applied to the deposits in order to obtain titanium aluminide intermetallic phases. The microstructure, chemical, and phase composition of the as-deposited and heat-treated coatings were investigated using SEM, EDS, and XRD. It was found that the Al content affects on the thickness expansion of the heat-treated Ti-Al coatings significantly and also has a major influence on the porosity development, which is caused by the Kirkendall effect. The effects of adding a third element Si and heat treatment with pressure to produce denser Ti-Al intermetallic coating were also examined. The investigated hot-pressed coatings with addition of Si exhibited much denser microstructure and contained Ti-Al intermetallic phases with titanium silicide precipitates.

  13. On the one-dimensional theory of steady compressible fluid flow in ducts with friction and heat addition

    NASA Technical Reports Server (NTRS)

    Hicks, Bruce L; Montgomery, Donald; Wasserman, Robert H

    1947-01-01

    Steady, diabatic (nonadiabatic), frictional, variable-area flow of a compressible fluid is treated in differential form on the basis of the one-dimensional approximation. The basic equations are first stated in terms of pressure, temperature, density, and velocity of the fluid. Considerable simplification and unification of the equations are then achieved by choosing the square of the local Mach number as one of the variables to describe the flow. The transformed system of equations thus obtained is first examined with regard to the existence of a solution. It is shown that, in general, a solution exists whose calculation requires knowledge only of the variation with position of any three of the dependent variables of the system. The direction of change of the flow variables can be obtained directly from the transformed equations without integration. As examples of this application of the equations, the direction of change of the flow variables is determined for two special flows. In the particular case when the local Mach number m = 1, a special condition must be satisfied by the flow if a solution is to exist. This condition restricts the joint rate of variation of heating, friction, and area at m = 1. Further analysis indicates that when a solution exists at this point it is not necessarily unique. Finally it is shown that the physical phenomenon of choking, which is known to occur in certain simple flow situations, is related to restrictions imposed on the variables by the form of the transformed equations. The phenomenon of choking is thus given a more general significance in that the transformed equations apply to a more general type of flow than has hitherto been treated. (author)

  14. A vigilance model for latent learning.

    PubMed

    Boguslavsky, G W

    1978-01-01

    The author proposes a heuristic model for latent learning. It is concluded that to regard academic learning as qualitatively different from other forms of learning is to deny evolutionary continuity. Academic learning is not a unitary process governed by a single set of parameters. In addition, it is observed that the problem of student motivation may very well turn out to be purely academic. The instructional technique for a captive audience of a class may be so structured as to make the direction of attention irresistible, the performance of a response, when needed, compelling, and the acquisition of knowledge inevitable. Vigilance is an instance of innate foundation. Its most striking characteristics are its universality in the animal world, its ready evocation by a wide range of stimuli, and its apparent behavior and physiological manifestations. The last two are the natural resources for objective investigation, and the first may well be the basis of broad and valid generalizations. PMID:748845

  15. Additional ECR heating of a radially inhomogeneous plasma via the absorption of satellite harmonics of the surface flute modes in a rippled magnetic field

    SciTech Connect

    Girka, V. O.; Girka, I. O.

    2006-12-15

    A theoretical study is made of the possibility of additional heating of a radially inhomogeneous plasma in confinement systems with a rippled magnetic field via the absorption of satellite harmonics of the surface flute modes with frequencies below the electron gyrofrequency in the local resonance region, {epsilon}{sub 1} (r{sub 1}) = [2{pi}c/({omega}L)]{sup 2}, where {epsilon}{sub 1} is the diagonal element of the plasma dielectric tensor in the hydrodynamic approximation, L is the period of a constant external rippled magnetic field, and the radical coordinate r{sub 1} determines the position of the local resonance. It is found that the high-frequency power absorbed near the local resonance is proportional to the square of the ripple amplitude of the external magnetic field. The mechanism proposed is shown to ensure the absorption of the energy of surface flute modes and, thereby, the heating of a radially inhomogeneous plasma.

  16. Toward Surface-Enhanced Raman Imaging of Latent Fingerprints

    SciTech Connect

    Connatser, Raynella M; Prokes, Sharka M.; Glembocki, Orest; Schuler, Rebecca A.; Gardner, Charles W.; Lewis Sr, Samuel Arthur; Lewis, Linda A

    2010-01-01

    Exposure to light or heat, or simply a dearth of fingerprint material, renders some latent fingerprints undetectable using conventional methods. We begin to address such elusive fingerprints using detection targeting photo- and thermally stable fingerprint constituents: surface-enhanced Raman spectroscopy (SERS). SERS can give descriptive vibrational spectra of amino acids, among other robust fingerprint constituents, and good sensitivity can be attained by improving metal-dielectric nanoparticle substrates. With SERS chemical imaging, vibrational bands intensities recreate a visual of fingerprint topography. The impact of nanoparticle synthesis route, dispersal methodology-deposition solvent, and laser wavelength are discussed, as are data from enhanced vibrational spectra of fingerprint components. SERS and Raman chemical images of fingerprints and realistic contaminants are shown. To our knowledge, this represents the first SERS imaging of fingerprints. In conclusion, this work progresses toward the ultimate goal of vibrationally detecting latent prints that would otherwise remain undetected using traditional development methods.

  17. Heat treatment and the use of additives to improve the stability of paralytic shellfish poisoning toxins in shellfish tissue reference materials for internal quality control and proficiency testing.

    PubMed

    Burrell, Stephen; Clion, Valentin; Auroy, Virginie; Foley, Barry; Turner, Andrew D

    2015-06-01

    The need for homogenous reference materials stable for paralytic shellfish toxins is vital for the monitoring and quality assurance of these potent neurotoxins in shellfish. Two stabilisation techniques were investigated, heat treatment through autoclaving and the addition of preserving additives into the tissue matrix. Short and long-term stability experiments as well as homogeneity determination were conducted on materials prepared by both techniques in comparison with an untreated control using two LC-FLD methods. Both techniques improved the stability of the matrix and the PSP toxins present compared to the controls. A material was prepared using the combined techniques of heat treatment followed by spiking with additives and data is presented from this optimised reference material as used over a two year period in the Irish national monitoring program and in a development exercise as part of a proficiency testing scheme operated by QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe) since 2011. The results were indicative of the long-term stability of the material as evidenced through consistent assigned values in the case of the proficiency testing scheme and a low relative standard deviation of 10.5% for total toxicity data generated over 24 months. PMID:25816999

  18. Latent IBP Compound Dirichlet Allocation.

    PubMed

    Archambeau, Cedric; Lakshminarayanan, Balaji; Bouchard, Guillaume

    2015-02-01

    We introduce the four-parameter IBP compound Dirichlet process (ICDP), a stochastic process that generates sparse non-negative vectors with potentially an unbounded number of entries. If we repeatedly sample from the ICDP we can generate sparse matrices with an infinite number of columns and power-law characteristics. We apply the four-parameter ICDP to sparse nonparametric topic modelling to account for the very large number of topics present in large text corpora and the power-law distribution of the vocabulary of natural languages. The model, which we call latent IBP compound Dirichlet allocation (LIDA), allows for power-law distributions, both, in the number of topics summarising the documents and in the number of words defining each topic. It can be interpreted as a sparse variant of the hierarchical Pitman-Yor process when applied to topic modelling. We derive an efficient and simple collapsed Gibbs sampler closely related to the collapsed Gibbs sampler of latent Dirichlet allocation (LDA), making the model applicable in a wide range of domains. Our nonparametric Bayesian topic model compares favourably to the widely used hierarchical Dirichlet process and its heavy tailed version, the hierarchical Pitman-Yor process, on benchmark corpora. Experiments demonstrate that accounting for the power-distribution of real data is beneficial and that sparsity provides more interpretable results. PMID:26353244

  19. Estimating and Interpreting Latent Variable Interactions: A Tutorial for Applying the Latent Moderated Structural Equations Method

    ERIC Educational Resources Information Center

    Maslowsky, Julie; Jager, Justin; Hemken, Douglas

    2015-01-01

    Latent variables are common in psychological research. Research questions involving the interaction of two variables are likewise quite common. Methods for estimating and interpreting interactions between latent variables within a structural equation modeling framework have recently become available. The latent moderated structural equations (LMS)…

  20. Optimization-Based Model Fitting for Latent Class and Latent Profile Analyses

    ERIC Educational Resources Information Center

    Huang, Guan-Hua; Wang, Su-Mei; Hsu, Chung-Chu

    2011-01-01

    Statisticians typically estimate the parameters of latent class and latent profile models using the Expectation-Maximization algorithm. This paper proposes an alternative two-stage approach to model fitting. The first stage uses the modified k-means and hierarchical clustering algorithms to identify the latent classes that best satisfy the…

  1. Information-Theoretic Latent Distribution Modeling: Distinguishing Discrete and Continuous Latent Variable Models

    ERIC Educational Resources Information Center

    Markon, Kristian E.; Krueger, Robert F.

    2006-01-01

    Distinguishing between discrete and continuous latent variable distributions has become increasingly important in numerous domains of behavioral science. Here, the authors explore an information-theoretic approach to latent distribution modeling, in which the ability of latent distribution models to represent statistical information in observed…

  2. Semi-Nonparametric Methods for Detecting Latent Non-Normality: A Fusion of Latent Trait and Ordered Latent Class Modeling

    ERIC Educational Resources Information Center

    Schmitt, J. Eric; Mehta, Paras D.; Aggen, Steven H.; Kubarych, Thomas S.; Neale, Michael C.

    2006-01-01

    Ordered latent class analysis (OLCA) can be used to approximate unidimensional latent distributions. The main objective of this study is to evaluate the method of OLCA in detecting non-normality of an unobserved continuous variable (i.e., a common factor) used to explain the covariation between dichotomous item-level responses. Using simulation,…

  3. Effectiveness: N(sub TU) relationships for the design and performance evaluation of additional shell-and-tube heat exchanger geometries

    NASA Astrophysics Data System (ADS)

    1988-11-01

    This Data Item 88021, an addition to the Sub-series on Heat Transfer, complements ESDU 86018 by extending the range of configurations covered there and in particular considering the effect of using small numbers of baffles for E- and J-shells and the use of J-shells in series. It also explores the limitations of the assumptions associated with the effectiveness - N(sub TU) method and shows where those assumptions break down. The curves presented for each exchanger geometry show the locus of designs for which a temperature cross may occur and the locus of 95 percent heat transfer effectiveness which indicates the region of uneconomic design. The method assumes a linear temperature/enthalpy relationship (constant specific heat capacity) for both streams. It applies to boiling or condensing flow of a single component with no temperature change, or boiling and condensing flow of a mixture that is always two-phase. It excludes conditions in which transition from single- to two-phase flow occurs. However, by use of average property values, it is possible to extend the method to apply to cases where there is some variation of physical and thermodynamic properties with temperature.

  4. Green technology effect of injection pressure, timing and compression ratio in constant pressure heat addition cycle by an eco-friendly material.

    PubMed

    Karthikayan, S; Sankaranarayanan, G; Karthikeyan, R

    2015-11-01

    Present energy strategies focus on environmental issues, especially environmental pollution prevention and control by eco-friendly green technologies. This includes, increase in the energy supplies, encouraging cleaner and more efficient energy management, addressing air pollution, greenhouse effect, global warming, and climate change. Biofuels provide the panorama of new fiscal opportunities for people in rural area for meeting their need and also the demand of the local market. Biofuels concern protection of the environment and job creation. Renewable energy sources are self-reliance resources, have the potential in energy management with less emissions of air pollutants. Biofuels are expected to reduce dependability on imported crude oil with connected economic susceptibility, reduce greenhouse gases, other pollutants and invigorate the economy by increasing demand and prices for agricultural products. The use of neat paradise tree oil and induction of eco-friendly material Hydrogen through inlet manifold in a constant pressure heat addition cycle engine (diesel engine) with optimized engine operating parameters such as injection timing, injection pressure and compression ratio. The results shows the heat utilization efficiency for neat vegetable oil is 29% and neat oil with 15% Hydrogen as 33%. The exhaust gas temperature (EGT) for 15% of H2 share as 450°C at full load and the heat release of 80J/deg. crank angle for 15% Hydrogen energy share. PMID:26025643

  5. Network-based modular latent structure analysis

    PubMed Central

    2014-01-01

    Background High-throughput expression data, such as gene expression and metabolomics data, exhibit modular structures. Groups of features in each module follow a latent factor model, while between modules, the latent factors are quasi-independent. Recovering the latent factors can shed light on the hidden regulation patterns of the expression. The difficulty in detecting such modules and recovering the latent factors lies in the high dimensionality of the data, and the lack of knowledge in module membership. Methods Here we describe a method based on community detection in the co-expression network. It consists of inference-based network construction, module detection, and interacting latent factor detection from modules. Results In simulations, the method outperformed projection-based modular latent factor discovery when the input signals were not Gaussian. We also demonstrate the method's value in real data analysis. Conclusions The new method nMLSA (network-based modular latent structure analysis) is effective in detecting latent structures, and is easy to extend to non-linear cases. The method is available as R code at http://web1.sph.emory.edu/users/tyu8/nMLSA/. PMID:25435002

  6. Rating Scale Analysis with Latent Class Models.

    ERIC Educational Resources Information Center

    Rost, Jurgen

    1988-01-01

    A general approach for analyzing rating data with latent class models is described, paralleling rating models in the framework of latent trait theory. A general rating model and a two-parameter model with location and dispersion parameters are derived and illustrated. (Author/SLD)

  7. Consequences of Fitting Nonidentified Latent Class Models

    ERIC Educational Resources Information Center

    Abar, Beau; Loken, Eric

    2012-01-01

    Latent class models are becoming more popular in behavioral research. When models with a large number of latent classes relative to the number of manifest indicators are estimated, researchers must consider the possibility that the model is not identified. It is not enough to determine that the model has positive degrees of freedom. A well-known…

  8. Latent Memory for Sensitization in "Aplysia"

    ERIC Educational Resources Information Center

    Philips, Gary T.; Tzvetkova, Ekaterina I.; Marinesco, Stephane; Carew, Thomas J.

    2006-01-01

    In the analysis of memory it is commonly observed that, even after a memory is apparently forgotten, its latent presence can still be revealed in a subsequent learning task. Although well established on a behavioral level, the mechanisms underlying latent memory are not well understood. To begin to explore these mechanisms, we have used "Aplysia,"…

  9. Epstein–Barr virus latent genes

    PubMed Central

    Kang, Myung-Soo; Kieff, Elliott

    2015-01-01

    Latent Epstein–Barr virus (EBV) infection has a substantial role in causing many human disorders. The persistence of these viral genomes in all malignant cells, yet with the expression of limited latent genes, is consistent with the notion that EBV latent genes are important for malignant cell growth. While the EBV-encoded nuclear antigen-1 (EBNA-1) and latent membrane protein-2A (LMP-2A) are critical, the EBNA-leader proteins, EBNA-2, EBNA-3A, EBNA-3C and LMP-1, are individually essential for in vitro transformation of primary B cells to lymphoblastoid cell lines. EBV-encoded RNAs and EBNA-3Bs are dispensable. In this review, the roles of EBV latent genes are summarized. PMID:25613728

  10. Latent classiness and other mixtures.

    PubMed

    Neale, Michael C

    2014-05-01

    The aim of this article is to laud Lindon Eaves' role in the development of mixture modeling in genetic studies. The specification of models for mixture distributions was very much in its infancy when Professor Eaves implemented it in his own FORTRAN programs, and extended it to data collected from relatives such as twins. It was his collaboration with the author of this article which led to the first implementation of mixture distribution modeling in a general-purpose structural equation modeling program, Mx, resulting in a 1996 article on linkage analysis in Behavior Genetics. Today, the popularity of these methods continues to grow, encompassing methods for genetic association, latent class analysis, growth curve mixture modeling, factor mixture modeling, regime switching, marginal maximum likelihood, genotype by environment interaction, variance component twin modeling in the absence of zygosity information, and many others. This primarily historical article concludes with some consideration of some possible future developments. PMID:24477932

  11. Latent Classiness and Other Mixtures

    PubMed Central

    Neale, Michael C.

    2014-01-01

    The aim of this article is to laud Lindon Eaves’ role in the development of mixture modeling in genetic studies. The specification of models for mixture distributions was very much in its infancy when Professor Eaves implemented it in his own FORTRAN programs, and extended it to data collected from relatives such as twins. It was his collaboration with the author of this article which led to the first implementation of mixture distribution modeling in a general-purpose structural equation modeling program, Mx, resulting in a 1996 article on linkage analysis in Behavior Genetics. Today, the popularity of these methods continues to grow, encompassing methods for genetic association, latent class analysis, growth curve mixture modeling, factor mixture modeling, regime switching, marginal maximum likelihood, genotype by environment interaction, variance component twin modeling in the absence of zygosity information, and many others. This primarily historical article concludes with some consideration of some possible future developments. PMID:24477932

  12. The importance of heat evolution during the overcharge process and the protection mechanism of electrolyte additives for prismatic lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Shiun; Hu, Chi-Chang; Li, Yuan-Yao

    In this work, the rate of heat generation in the overcharge period for 103450 prismatic lithium ion batteries (LIBs) of the LiCoO 2-graphite jellyroll type with a basic electrolyte consisting of 1 M LiPF 6-PC/EC/EMC (1/3/5 in weight ratio) has been found to be more important than the gas evolution which was traditionally considered as the main reason in the overcharge protection mechanism. The cell voltage, charge current, and skin temperature were monitored during the charge process. For a single battery or batteries in parallel, LIBs without any additives is an acceptable design if the cell voltage is not charged above 4.55 V under the common charge program. The rate of heat generation from the polymerization of 3 wt% cyclohexyl benzene (CHB) is high enough to cause the explosion or thermal runaway of a battery, which is not found for an LIB containing 2 wt% CHB + 1 wt% tert-amyl benzene (TAB). In the 12 V overcharge test at 1C, the thermal fuse was broken by the high skin temperature (ca. 80 °C) due to the polymerization of 3 wt% CHB, which was also the case for LIBs containing 2 wt% CHB + 1 wt% TAB. The disconnection of the thermal fuse, however, did not interrupt the thermal runaway of LIBs without any additives because the battery voltage was too high (ca. 4.9 V). The influence of specific surface area of active materials in the anode on the polymerization kinetics of additives has to be carefully considered in order to add correct amount of overcharge protection agents.

  13. Simplified numerical description of latent storage characteristics for phase change wallboard

    SciTech Connect

    Feustel, H.E.

    1995-05-01

    Cooling of residential California buildings contributes significantly to electrical consumption and peak power demand. Thermal mass can be utilized to reduce the peak-power demand, down-size the cooling systems and/or switch to low-energy cooling sources. Large thermal storage devices have been used in the past to overcome the short-comings of alternative cooling sources or to avoid high demand charges. With the advent of phase change material (PCM) implemented in gypsum board, plaster or other wall-covering material, thermal storage can be part of the building structure even for light-weight buildings. PCMs have two important advantages as storage media: they can offer an order-of-magnitude increase in thermal storage capacity and their discharge is almost isothermal. This allows to store large amounts of energy without significantly changing the temperature of the sheathing. As heat storage takes place in the building part where the loads occur, rather than externally (e.g., ice or chilled water storage), additional transport energy is not needed. To numerically evaluate the latent storage performance of treated wallboard, RADCOOL, a thermal building simulation model based on the finite difference approach, will be used. RADCOOL has been developed in the SPARK environment in order to be compatible with the new family of simulation tools being developed at Lawrence Berkeley Laboratory. As logical statements are difficult to use in SPARK, a continuous function for the specific heat and the enthalpy had to be found. This report covers the development of a simplified description of latent storage characteristics for wallboard treated with phase change material.

  14. Latent fingermark development using low-vacuum vaporization of ninhydrin.

    PubMed

    Chen, Chun-Chieh; Yang, Chao-Kai; Liao, Jeh-Shane; Wang, Sheng-Meng

    2015-12-01

    The vacuum technique is a method of vaporizing a solid material to its gas phase, helping deposit reagents gently on target surfaces to develop latent fingermarks. However, this application is rarely reported in the literature. In this study, a homemade fume hood with a built-in vacuum control system and programmable heating system designed by the Taiwan Criminal Investigation Bureau is introduced. Factors that affect the instrument's performance in developing fingermarks are discussed, including the quantity of chemicals for vaporization, heating program arrangement, and paper of different materials. The results show that fingermarks are effectively developed by vaporizing solid ninhydrin. This would be an alternative application in selecting a solvent-free method for protecting the environment and reducing health hazards in the lab. In terms of the heating program, the result indicates that under a low-vacuum condition (50 mTorr), 80-90 °C is a suitable temperature range for ninhydrin vaporization, allowing ninhydrin to be vaporized without bumping and waste. In terms of the performance on different material papers, this instrument demonstrates its capacity by developing latent fingermarks on thermal paper without discoloration or damaging the original writing, and the same results are also observed on Taiwan and United States banknotes. However, a coherent result could be hardly obtained using the same vaporization setting because different banknotes have their own surface features and water absorption ability or other unique factors may influence the effect of ninhydrin deposition. This study provides a reliable application for developing latent fingermarks without using solvents, and it is also expected to contribute to environmental protection along with the trend of green chemistry technology. PMID:26451774

  15. A novel approach for latent print identification using accurate overlays to prioritize reference prints.

    PubMed

    Gantz, Daniel T; Gantz, Donald T; Walch, Mark A; Roberts, Maria Antonia; Buscaglia, JoAnn

    2014-12-01

    A novel approach to automated fingerprint matching and scoring that produces accurate locally and nonlinearly adjusted overlays of a latent print onto each reference print in a corpus is described. The technology, which addresses challenges inherent to latent prints, provides the latent print examiner with a prioritized ranking of candidate reference prints based on the overlays of the latent onto each candidate print. In addition to supporting current latent print comparison practices, this approach can make it possible to return a greater number of AFIS candidate prints because the ranked overlays provide a substantial starting point for latent-to-reference print comparison. To provide the image information required to create an accurate overlay of a latent print onto a reference print, "Ridge-Specific Markers" (RSMs), which correspond to short continuous segments of a ridge or furrow, are introduced. RSMs are reliably associated with any specific local section of a ridge or a furrow using the geometric information available from the image. Latent prints are commonly fragmentary, with reduced clarity and limited minutiae (i.e., ridge endings and bifurcations). Even in the absence of traditional minutiae, latent prints contain very important information in their ridges that permit automated matching using RSMs. No print orientation or information beyond the RSMs is required to generate the overlays. This automated process is applied to the 88 good quality latent prints in the NIST Special Database (SD) 27. Nonlinear overlays of each latent were produced onto all of the 88 reference prints in the NIST SD27. With fully automated processing, the true mate reference prints were ranked in the first candidate position for 80.7% of the latents tested, and 89.8% of the true mate reference prints ranked in the top ten positions. After manual post-processing of those latents for which the true mate reference print was not ranked first, these frequencies increased to 90

  16. Numerical modeling of heat-transfer and the influence of process parameters on tailoring the grain morphology of IN718 in electron beam additive manufacturing

    DOE PAGESBeta

    Raghavan, Narendran; Dehoff, Ryan; Pannala, Sreekanth; Simunovic, Srdjan; Kirka, Michael; Turner, John; Carlson, Neil; Babu, Sudarsanam S.

    2016-04-26

    The fabrication of 3-D parts from CAD models by additive manufacturing (AM) is a disruptive technology that is transforming the metal manufacturing industry. The correlation between solidification microstructure and mechanical properties has been well understood in the casting and welding processes over the years. This paper focuses on extending these principles to additive manufacturing to understand the transient phenomena of repeated melting and solidification during electron beam powder melting process to achieve site-specific microstructure control within a fabricated component. In this paper, we have developed a novel melt scan strategy for electron beam melting of nickel-base superalloy (Inconel 718) andmore » also analyzed 3-D heat transfer conditions using a parallel numerical solidification code (Truchas) developed at Los Alamos National Laboratory. The spatial and temporal variations of temperature gradient (G) and growth velocity (R) at the liquid-solid interface of the melt pool were calculated as a function of electron beam parameters. By manipulating the relative number of voxels that lie in the columnar or equiaxed region, the crystallographic texture of the components can be controlled to an extent. The analysis of the parameters provided optimum processing conditions that will result in columnar to equiaxed transition (CET) during the solidification. Furthermore, the results from the numerical simulations were validated by experimental processing and characterization thereby proving the potential of additive manufacturing process to achieve site-specific crystallographic texture control within a fabricated component.« less

  17. Orientation field estimation for latent fingerprint enhancement.

    PubMed

    Feng, Jianjiang; Zhou, Jie; Jain, Anil K

    2013-04-01

    Identifying latent fingerprints is of vital importance for law enforcement agencies to apprehend criminals and terrorists. Compared to live-scan and inked fingerprints, the image quality of latent fingerprints is much lower, with complex image background, unclear ridge structure, and even overlapping patterns. A robust orientation field estimation algorithm is indispensable for enhancing and recognizing poor quality latents. However, conventional orientation field estimation algorithms, which can satisfactorily process most live-scan and inked fingerprints, do not provide acceptable results for most latents. We believe that a major limitation of conventional algorithms is that they do not utilize prior knowledge of the ridge structure in fingerprints. Inspired by spelling correction techniques in natural language processing, we propose a novel fingerprint orientation field estimation algorithm based on prior knowledge of fingerprint structure. We represent prior knowledge of fingerprints using a dictionary of reference orientation patches. which is constructed using a set of true orientation fields, and the compatibility constraint between neighboring orientation patches. Orientation field estimation for latents is posed as an energy minimization problem, which is solved by loopy belief propagation. Experimental results on the challenging NIST SD27 latent fingerprint database and an overlapped latent fingerprint database demonstrate the advantages of the proposed orientation field estimation algorithm over conventional algorithms. PMID:22826508

  18. Predictive Inference Using Latent Variables with Covariates*

    PubMed Central

    Schofield, Lynne Steuerle; Junker, Brian; Taylor, Lowell J.; Black, Dan A.

    2014-01-01

    Plausible Values (PVs) are a standard multiple imputation tool for analysis of large education survey data that measures latent proficiency variables. When latent proficiency is the dependent variable, we reconsider the standard institutionally-generated PV methodology and find it applies with greater generality than shown previously. When latent proficiency is an independent variable, we show that the standard institutional PV methodology produces biased inference because the institutional conditioning model places restrictions on the form of the secondary analysts’ model. We offer an alternative approach that avoids these biases based on the mixed effects structural equations (MESE) model of Schofield (2008). PMID:25231627

  19. Extraction of latent images from printed media

    NASA Astrophysics Data System (ADS)

    Sergeyev, Vladislav; Fedoseev, Victor

    2015-12-01

    In this paper we propose an automatic technology for extraction of latent images from printed media such as documents, banknotes, financial securities, etc. This technology includes image processing by adaptively constructed Gabor filter bank for obtaining feature images, as well as subsequent stages of feature selection, grouping and multicomponent segmentation. The main advantage of the proposed technique is versatility: it allows to extract latent images made by different texture variations. Experimental results showing performance of the method over another known system for latent image extraction are given.

  20. Latent progenitor cells as potential regulators for tympanic membrane regeneration

    NASA Astrophysics Data System (ADS)

    Kim, Seung Won; Kim, Jangho; Seonwoo, Hoon; Jang, Kyung-Jin; Kim, Yeon Ju; Lim, Hye Jin; Lim, Ki-Taek; Tian, Chunjie; Chung, Jong Hoon; Choung, Yun-Hoon

    2015-06-01

    Tympanic membrane (TM) perforation, in particular chronic otitis media, is one of the most common clinical problems in the world and can present with sensorineural healing loss. Here, we explored an approach for TM regeneration where the latent progenitor or stem cells within TM epithelial layers may play an important regulatory role. We showed that potential TM stem cells present highly positive staining for epithelial stem cell markers in all areas of normal TM tissue. Additionally, they are present at high levels in perforated TMs, especially in proximity to the holes, regardless of acute or chronic status, suggesting that TM stem cells may be a potential factor for TM regeneration. Our study suggests that latent TM stem cells could be potential regulators of regeneration, which provides a new insight into this clinically important process and a potential target for new therapies for chronic otitis media and other eardrum injuries.

  1. (Thermal energy storage technologies for heating and cooling applications)

    SciTech Connect

    Tomlinson, J.J.

    1990-12-19

    Recent results from selected TES research activities in Germany and Sweden under an associated IEA annex are discussed. In addition, several new technologies for heating and cooling of buildings and automobiles were reviewed and found to benefit similar efforts in the United states. Details of a meeting with Didier-Werke AG, a leading German ceramics manufacturer who will provide TES media necessary for the United States to complete field tests of an advanced high temperature latent heat storage material, are presented. Finally, an overview of the December 1990 IEA Executive Committee deliberations on TES is presented.

  2. Application of the standard addition method for the determination of acrylamide in heat-processed starchy foods by gas chromatography with electron capture detector.

    PubMed

    Zhu, Yonghong; Li, Genrong; Duan, Yunpeng; Chen, Shiqi; Zhang, Chun; Li, Yanfei

    2008-08-15

    A gas chromatography electron capture detector (GC-ECD) using the standard addition method was developed for the determination of acrylamide in heat-processed foods. The method entails extraction of acrylamide with water, filtration, defatting with n-hexane, derivatization with hydrobromic acid and saturated bromine-water, and liquid-liquid extraction with ethyl acetate. The sample pretreatment required no SPE clean-up and concentration steps prior to injection. The final extract was analyzed by GC-ECD. The chromatographic analysis was performed on polar columns, e.g. Supelcowax-10 capillary column, and good retention and peak response of the analyte were achieved under the optimal conditions. The qualification of the analyte was by identifying the peak with same retention time as standard compound 2,3-DBPA and confirmed by GC-MS. GC-MS analysis confirmed that 2,3-DBPA was converted to 2-BPA nearly completely on the polar capillary column, whether or not treated with triethylamine. A four-point standard addition protocol was used to quantify acrylamide in food samples. The limit of detection (LOD) was estimated to be 0.6μg/kg on the basis of ECD technique. Validation and quantification results demonstrated that the method should be regarded as a low-cost, convenient, and reliable alternative for conventional investigation of acrylamide. PMID:26050006

  3. Numerical investigation of the mechanical properties of the additive manufactured bone scaffolds fabricated by FDM: The effect of layer penetration and post-heating.

    PubMed

    Naghieh, S; Karamooz Ravari, M R; Badrossamay, M; Foroozmehr, E; Kadkhodaei, M

    2016-06-01

    In recent years, thanks to additive manufacturing technology, researchers have gone towards the optimization of bone scaffolds for the bone reconstruction. Bone scaffolds should have appropriate biological as well as mechanical properties in order to play a decisive role in bone healing. Since the fabrication of scaffolds is time consuming and expensive, numerical methods are often utilized to simulate their mechanical properties in order to find a nearly optimum one. Finite element analysis is one of the most common numerical methods that is used in this regard. In this paper, a parametric finite element model is developed to assess the effects of layers penetration׳s effect on inter-layer adhesion, which is reflected on the mechanical properties of bone scaffolds. To be able to validate this model, some compression test specimens as well as bone scaffolds are fabricated with biocompatible and biodegradable poly lactic acid using fused deposition modeling. All these specimens are tested in compression and their elastic modulus is obtained. Using the material parameters of the compression test specimens, the finite element analysis of the bone scaffold is performed. The obtained elastic modulus is compared with experiment indicating a good agreement. Accordingly, the proposed finite element model is able to predict the mechanical behavior of fabricated bone scaffolds accurately. In addition, the effect of post-heating of bone scaffolds on their elastic modulus is investigated. The results demonstrate that the numerically predicted elastic modulus of scaffold is closer to experimental outcomes in comparison with as-built samples. PMID:26874065

  4. Polymer alloys with balanced heat storage capacity and engineering attributes and applications thereof

    DOEpatents

    Soroushian, Parviz

    2002-01-01

    A thermoplastic polymer of relatively low melt temperature is blended with at least one of thermosets, elastomers, and thermoplastics of relatively high melt temperature in order to produce a polymer blend which absorbs relatively high quantities of latent heat without melting or major loss of physical and mechanical characteristics as temperature is raised above the melting temperature of the low-melt-temperature thermoplastic. The polymer blend can be modified by the addition of at least one of fillers, fibers, fire retardants, compatibilisers, colorants, and processing aids. The polymer blend may be used in applications where advantage can be taken of the absorption of excess heat by a component which remains solid and retains major fractions of its physical and mechanical characteristics while absorbing relatively high quantities of latent heat.

  5. Latent Change Classes in Dichotomous Data.

    ERIC Educational Resources Information Center

    Formann, Anton K.; Ponocny, Ivo

    2002-01-01

    Developed a method, based on the conditional maximum likelihood principle, for establishing latent change classes in dichotomous data. Simulation studies and a real data set from an earlier study illustrate the method of parameter estimation. (SLD)

  6. Heteroscedastic Latent Trait Models for Dichotomous Data.

    PubMed

    Molenaar, Dylan

    2015-09-01

    Effort has been devoted to account for heteroscedasticity with respect to observed or latent moderator variables in item or test scores. For instance, in the multi-group generalized linear latent trait model, it could be tested whether the observed (polychoric) covariance matrix differs across the levels of an observed moderator variable. In the case that heteroscedasticity arises across the latent trait itself, existing models commonly distinguish between heteroscedastic residuals and a skewed trait distribution. These models have valuable applications in intelligence, personality and psychopathology research. However, existing approaches are only limited to continuous and polytomous data, while dichotomous data are common in intelligence and psychopathology research. Therefore, in present paper, a heteroscedastic latent trait model is presented for dichotomous data. The model is studied in a simulation study, and applied to data pertaining alcohol use and cognitive ability. PMID:25080866

  7. Reactivation of Latent Viruses in Space

    NASA Technical Reports Server (NTRS)

    Pierson, D. L.; Mehta, S. K.; Tyring, S. K.; Lugg, D. J.

    1999-01-01

    Reactivation of latent viruses is an important health risk for people working and living in physically isolated extreme environments such as Antarctica and space. Preflight quarantine does not significantly reduce the risk associated with latent viruses, however, pharmaceutical countermeasures are available for some viruses. The molecular basis of latency is not fully understood, but physical and psychosocial stresses are known to initiate the reactivation of latent viruses. Presumably, stress induced changes in selected hormones lead to alterations in the cell- mediated immune (CMI) response resulting in increased shedding of latent viruses. Limited access to space makes the use of ground-based analogs essential. The Australian Antarctic stations serve as a good stress model and simulate many aspects of space flight. Closed environmental chambers have been used to simulate space flight since the Skylab missions and have also proven to be a valuable analog of selected aspects of space flight.

  8. Latent phenotypes pervade gene regulatory circuits

    PubMed Central

    2014-01-01

    Background Latent phenotypes are non-adaptive byproducts of adaptive phenotypes. They exist in biological systems as different as promiscuous enzymes and genome-scale metabolic reaction networks, and can give rise to evolutionary adaptations and innovations. We know little about their prevalence in the gene expression phenotypes of regulatory circuits, important sources of evolutionary innovations. Results Here, we study a space of more than sixteen million three-gene model regulatory circuits, where each circuit is represented by a genotype, and has one or more functions embodied in one or more gene expression phenotypes. We find that the majority of circuits with single functions have latent expression phenotypes. Moreover, the set of circuits with a given spectrum of functions has a repertoire of latent phenotypes that is much larger than that of any one circuit. Most of this latent repertoire can be easily accessed through a series of small genetic changes that preserve a circuit’s main functions. Both circuits and gene expression phenotypes that are robust to genetic change are associated with a greater number of latent phenotypes. Conclusions Our observations suggest that latent phenotypes are pervasive in regulatory circuits, and may thus be an important source of evolutionary adaptations and innovations involving gene regulation. PMID:24884746

  9. The Latent Structure of Dictionaries.

    PubMed

    Vincent-Lamarre, Philippe; Massé, Alexandre Blondin; Lopes, Marcos; Lord, Mélanie; Marcotte, Odile; Harnad, Stevan

    2016-07-01

    How many words-and which ones-are sufficient to define all other words? When dictionaries are analyzed as directed graphs with links from defining words to defined words, they reveal a latent structure. Recursively removing all words that are reachable by definition but that do not define any further words reduces the dictionary to a Kernel of about 10% of its size. This is still not the smallest number of words that can define all the rest. About 75% of the Kernel turns out to be its Core, a "Strongly Connected Subset" of words with a definitional path to and from any pair of its words and no word's definition depending on a word outside the set. But the Core cannot define all the rest of the dictionary. The 25% of the Kernel surrounding the Core consists of small strongly connected subsets of words: the Satellites. The size of the smallest set of words that can define all the rest-the graph's "minimum feedback vertex set" or MinSet-is about 1% of the dictionary, about 15% of the Kernel, and part-Core/part-Satellite. But every dictionary has a huge number of MinSets. The Core words are learned earlier, more frequent, and less concrete than the Satellites, which are in turn learned earlier, more frequent, but more concrete than the rest of the Dictionary. In principle, only one MinSet's words would need to be grounded through the sensorimotor capacity to recognize and categorize their referents. In a dual-code sensorimotor/symbolic model of the mental lexicon, the symbolic code could do all the rest through recombinatory definition. PMID:27424842

  10. Latent developmental and evolutionary shapes embedded within the grapevine leaf.

    PubMed

    Chitwood, Daniel H; Klein, Laura L; O'Hanlon, Regan; Chacko, Steven; Greg, Matthew; Kitchen, Cassandra; Miller, Allison J; Londo, Jason P

    2016-04-01

    Across plants, leaves exhibit profound diversity in shape. As a single leaf expands, its shape is in constant flux. Plants may also produce leaves with different shapes at successive nodes. In addition, leaf shape varies among individuals, populations and species as a result of evolutionary processes and environmental influences. Because leaf shape can vary in many different ways, theoretically, the effects of distinct developmental and evolutionary processes are separable, even within the shape of a single leaf. Here, we measured the shapes of > 3200 leaves representing > 270 vines from wild relatives of domesticated grape (Vitis spp.) to determine whether leaf shapes attributable to genetics and development are separable from each other. We isolated latent shapes (multivariate signatures that vary independently from each other) embedded within the overall shape of leaves. These latent shapes can predict developmental stages independent from species identity and vice versa. Shapes predictive of development were then used to stage leaves from 1200 varieties of domesticated grape (Vitis vinifera), revealing that changes in timing underlie leaf shape diversity. Our results indicate that distinct latent shapes combine to produce a composite morphology in leaves, and that developmental and evolutionary contributions to shape vary independently from each other. PMID:26580864

  11. Modeling healthcare data using multiple-channel latent Dirichlet allocation.

    PubMed

    Lu, Hsin-Min; Wei, Chih-Ping; Hsiao, Fei-Yuan

    2016-04-01

    Information and communications technologies have enabled healthcare institutions to accumulate large amounts of healthcare data that include diagnoses, medications, and additional contextual information such as patient demographics. To gain a better understanding of big healthcare data and to develop better data-driven clinical decision support systems, we propose a novel multiple-channel latent Dirichlet allocation (MCLDA) approach for modeling diagnoses, medications, and contextual information in healthcare data. The proposed MCLDA model assumes that a latent health status group structure is responsible for the observed co-occurrences among diagnoses, medications, and contextual information. Using a real-world research testbed that includes one million healthcare insurance claim records, we investigate the utility of MCLDA. Our empirical evaluation results suggest that MCLDA is capable of capturing the comorbidity structures and linking them with the distribution of medications. Moreover, MCLDA is able to identify the pairing between diagnoses and medications in a record based on the assigned latent groups. MCLDA can also be employed to predict missing medications or diagnoses given partial records. Our evaluation results also show that, in most cases, MCLDA outperforms alternative methods such as logistic regressions and the k-nearest-neighbor (KNN) model for two prediction tasks, i.e., medication and diagnosis prediction. Thus, MCLDA represents a promising approach to modeling healthcare data for clinical decision support. PMID:26898516

  12. Heating Structures Derived from Satellite

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Adler, R.; Haddad, Z.; Hou, A.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C.; Lang, S.; Meneghini, R.; Olson, W.

    2004-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent-heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. The Tropical Rainfall Measuring Mission (TRMM), a joint U.S./Japan space project, was launched in November 1997. It provides an accurate measurement of rainfall over the global tropics which can be used to estimate the four-dimensional structure of latent heating over the global tropics. The distributions of rainfall and inferred heating can be used to advance our understanding of the global energy and water cycle. This paper describes several different algorithms for estimating latent heating using TRMM observations. The strengths and weaknesses of each algorithm as well as the heating products are also discussed. The validation of heating products will be exhibited. Finally, the application of this heating information to global circulation and climate models is presented.

  13. A study on the carcinogenicity of human diets in rats: the influence of heating and the addition of vegetables and fruit.

    PubMed

    Alink, G M; Kuiper, H A; Beems, R B; Koeman, J H

    1989-07-01

    The influence of dietary factors such as total composition, thermal processing, and the addition of vegetables and fruit on the tumour rate in rats was studied in a long-term experiment. Groups of 50 male and 50 female Wistar rats were fed one of the following diets: a semi-synthetic animal diet (A, control); diet A to which vegetables and fruit were added (B); an uncooked human diet (meat, bread and eggs) supplemented with semi-synthetic compounds (C); diet C with fried or baked products (D); a complete human diet consisting of heated products, vegetables and fruit prepared according to mean consumption figures in The Netherlands (E). The animal diets (A and B) contained 26.0 energy (E)% protein, 21.6 E% fat, 52.4 E% carbohydrate and 10.7% (w/w) fibre. The human diets contained 13.2 E% protein, 40.6 E% fat, 46.2 E% carbohydrate and 5% (w/w) fibre. The rats were fed ad lib. for 142 wk. In males and females fed human diets (C, D or E) hepatocellular vacuolization was observed. Male rats (but not female) fed the human diet had a significantly (P less than 0.02) higher incidence of epithelial tumours than those fed the animal diet. This increase was mainly due to tumours of the pituitary and thyroid. Frying and baking of food products (diet D) and the addition of vegetables and fruit (diet E) induced minor differences in tumour rate, but they were not statistically significant. PMID:2777146

  14. Latent Curve Models and Latent Change Score Models Estimated in R

    ERIC Educational Resources Information Center

    Ghisletta, Paolo; McArdle, John J.

    2012-01-01

    In recent years the use of the latent curve model (LCM) among researchers in social sciences has increased noticeably, probably thanks to contemporary software developments and the availability of specialized literature. Extensions of the LCM, like the the latent change score model (LCSM), have also increased in popularity. At the same time, the R…

  15. Siloxane containing addition polyimides

    NASA Technical Reports Server (NTRS)

    Maudgal, S.; St. Clair, T. L.

    1984-01-01

    Addition polyimide oligomers have been synthesized from bis(gamma-aminopropyl) tetramethyldisiloxane and 3, 3', 4, 4'-benzophenonetetracarboxylic dianhydride using a variety of latent crosslinking groups as endcappers. The prepolymers were isolated and characterized for solubility (in amide, chlorinated and ether solvents), melt flow and cure properties. The most promising systems, maleimide and acetylene terminated prepolymers, were selected for detailed study. Graphite cloth reinforced composites were prepared and properties compared with those of graphite/Kerimid 601, a commercially available bismaleimide. Mixtures of the maleimide terminated system with Kerimid 601, in varying proportions, were also studied.

  16. Chromatin organization of gammaherpesvirus latent genomes.

    PubMed

    Tempera, Italo; Lieberman, Paul M

    2010-01-01

    The gammaherpesviruses are a subclass of the herpesvirus family that establish stable latent infections in proliferating lymphoid and epithelial cells. The latent genomes are maintained as multicopy chromatinized episomes that replicate in synchrony with the cellular genome. Importantly, most of the episomes do not integrate into the host chromosome. Therefore, it is essential that the viral "minichromosome" establish a chromatin structure that is suitable for gene expression, DNA replication, and chromosome segregation. Evidence suggests that chromatin organization is important for each of these functions and plays a regulatory role in the establishment and maintenance of latent infection. Here, we review recent studies on the chromatin organization of the human gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV). We discuss the potential role of viral origins of DNA replication and viral encoded origin-binding proteins like EBNA1 and LANA in establishment of viral chromosome organization during latent infection. We also discuss the roles of host cell factors, like CTCF and cohesins, that contribute to higher-order chromosome structures that may be important for stable gene expression programs during latent infection in proliferating cells. PMID:19853673

  17. Composite latent/sensible energy storage media for high-temperature industrial applications

    SciTech Connect

    Olszewski, M.

    1984-01-01

    An advanced thermal energy storage media concept is being developed for industrial process and reject heat applications. This composite medium consists of a phase-change carbonate salt, supported and immobilized within a submicron-sized capillary structure of a particulate ceramic matrix of porous sintered ceramic. Immobilization of the molten salt within the ceramic structure permits operation of the composite pellets, bricks or other shapes in direct contact with compatible fluids. Energy storage occurs in both sensible and latent forms with the composite providing higher energy storage densities than standard sensible heat storage systems. This paper describes the composite latent/sensible media concept and its potential advantage over state-ofthe-art systems. Current development activities concerning media stability and fabrication are described. Economic viability of the concept, especially in comparison to extant sensible heat storage systems, is also presented.

  18. Primary Energy Efficiency Analysis of Different Separate Sensible and Latent Cooling Techniques

    SciTech Connect

    Abdelaziz, Omar

    2015-01-01

    Separate Sensible and Latent cooling (SSLC) has been discussed in open literature as means to improve air conditioning system efficiency. The main benefit of SSLC is that it enables heat source optimization for the different forms of loads, sensible vs. latent, and as such maximizes the cycle efficiency. In this paper I use a thermodynamic analysis tool in order to analyse the performance of various SSLC technologies including: multi-evaporators two stage compression system, vapour compression system with heat activated desiccant dehumidification, and integrated vapour compression with desiccant dehumidification. A primary coefficient of performance is defined and used to judge the performance of the different SSLC technologies at the design conditions. Results showed the trade-off in performance for different sensible heat factor and regeneration temperatures.

  19. Effects of alpha-tocopherol addition to polymeric coatings on the UV and heat resistance of a fibrous collagen material--chrome-free leather

    Technology Transfer Automated Retrieval System (TEKTRAN)

    UV and heat resistance are very important qualities of leather because most leather products are constantly exposed to outdoor environments. In recent years, we have focused on using environmentally friendly antioxidants that will improve the UV and heat resistance of chrome-free leather. Tocopher...

  20. Enceladus' Enigmatic Heat Flow

    NASA Astrophysics Data System (ADS)

    Howett, C.; Spencer, J. R.; Spencer, D.; Verbiscer, A.; Hurford, T.; Segura, M.

    2013-12-01

    Accurate knowledge of Enceladus' heat flow is important because it provides a vital constraint on Enceladus' tidal dissipation mechanisms, orbital evolution, and the physical processes that generate the plumes. In 2011 we published an estimate of the current heat flow from Enceladus' active south polar terrain: 15.8 +/- 3.1 GW (Howett et al., 2011). This value was calculated by first estimating by modeling, and then removing, the passive component from 17 to 1000 micron observations made of the entire south polar terrain by Cassini's Composite Infrared Spectrometer (CIRS). The heat flow was then directly calculated from the residual, assumed endogenic, component. The derived heat flow of 15.8 GW was surprisingly high, about 10 times greater than that predicted by steady-state tidal heating (Meyer and Wisdom, 2007). CIRS has also returned high spatial resolution observations of Enceladus' active south polar terrain. Two separate observations are used: 9 to 16 micron observations taken over nearly the complete south polar terrain and a single 17 to 1000 micron scan over Damascus, Baghdad and Cairo. The shorter wavelength observations are only sensitive to high temperature emission (>70 K), and so longer wavelength observations are required (despite their limited spatial coverage) to estimate the low temperature emission from the stripes. Analysis of these higher resolution observations tells a different story of Enceladus' endogenic heat flow: the preliminary estimate of the heat flow from the active tiger stripes using these observations is 4.2 GW. An additional 0.5 GW must be added to this number to account for the latent heat release by the plumes (Ingersoll and Pankine 2009), giving a total preliminary estimate of 4.9 GW. The discrepancy in these two numbers is significant and we are currently investigating the cause. One possible reason is that there is significantly higher endogenic emission from the regions between the tiger stripes than we currently estimate

  1. Diagnosis and Treatment of Latent Tuberculosis Infection in Healthcare Workers

    PubMed Central

    2016-01-01

    Tuberculosis (TB) is one of the most important occupational risks for healthcare workers (HCWs) in South Korea. Many policies regarding the control and prevention of TB in healthcare settings recommend that HCWs are tested for latent tuberculosis infection (LTBI) in addition to active TB. Moreover, the Korean Tuberculosis Prevention Act also recommends that HCWs receive regular testing for LTBI. However, there are no specific or detailed guidelines for dealing with LTBI in HCWs. Herein, we discuss the diagnosis and treatment of LTBI in HCWs and focus particularly on the baseline screening of hired HCWs, routine follow-up, and contact investigation. PMID:27433172

  2. The addition of heat shock protein HSPA8 to cryoprotective media improves the survival of brown bear (Ursus arctos) spermatozoa during chilling and after cryopreservation.

    PubMed

    Alvarez-Rodríguez, M; Alvarez, M; Borragan, S; Martinez-Pastor, F; Holt, W V; Fazeli, A; de Paz, P; Anel, L

    2013-02-01

    The Cantabrian brown bear survives as a small remnant population in northern Spain and semen cryopreservation for future artificial insemination is one of the measures being implemented for conservation of this species. As part of this program we investigated the value of adding heat shock protein A8 (HSPA8) to media (N-[Tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid-TRIS-fructose with 20% egg yolk) used for chilling and cryopreserving the spermatozoa. Semen samples from eight brown bears were obtained by electroejaculation during the breeding season. In experiment 1, we tested three concentrations of HSPA8 (0.5, 1, and 5 μg/mL) to determine whether sperm motility (computer assisted sperm analysis system) and sperm survival could be improved during refrigeration (5 °C) up to 48 hours. Results showed that sperm viability (test with propidium iodide) was improved by the addition of 0.5 and 5 μg/mL HSPA8. In experiment 2, HSPA8 was added to the cryopreservation media (6% final glycerol concentration) before the freezing process. Though there were no differences in sperm viability immediately after thawing (analyses to 0 hours), plasma membrane permeability (test with YO-PRO-1) was significantly lower by the presence of HSPA8 (1 μg/mL) and acrosomal damage (test with peanut agglutinin-fluorescein isothiocyanate conjugate) was reduced by higher concentrations of HSPA8 (1 and 5 μg/mL) (analyses after thermal stress test incubating over 2 hours to 37 °C). In experiment 3, results of a simple progression test carried out through artificial mucus (hyaluronic acid 4 mg/mL) showed a significant decrease in the total number of sperm able to swim a distance of 0.5 to 2 cm through a capillary tube for all HSPA8-based extenders. Nevertheless, the distance traveled by the vanguard spermatozoa, which represent a highly motile subpopulation, was restored by the inclusion of 1 and 5 μg/mL HSPA8 in the cryopreservation media. Thus, the HSPA8 addition to extender improves

  3. Latent image exposure monitor using scatterometry

    SciTech Connect

    Milner, L.M.; Hickman, K.C.; Gaspar, S.M.; Bishop, K.P.; Naqvi, S.S.; McNeil, J.R.; Blain, M.; Draper, B.L.

    1992-09-01

    We discuss the use of light scattered from a latent image to control photoresist exposure dose and focus conditions which results in improved control of the critical dimension (CD) of the developed photoresist. A laser at a non-exposing wavelength is used to illuminate a latent image grating. The light diffracted from the grating is directly related to the exposure dose and focus and thus to the resultant CD in the developed resist. Modeling has been done using rigorous coupled wave analysis to predict the diffraction from a latent image as a function of the substrate optical properties and the photoactive compound (PAC) concentration distribution inside the photoresist. It is possible to use the model to solve the inverse problem: given the diffraction, to predict the parameters of the latent image and hence the developed pattern. This latent image monitor can be implemented in a stepper to monitor exposure in situ, or prior to development to predict the developed CD of a wafer for early detection of bad devices. Experimentation has been conducted using various photoresists and substrates with excellent agreement between theoretical and experimental results. The technique has been used to characterize a test pattern with a focused spot as small as 36{mu}m in diameter. Using diffracted light from a simulated closed-loop control of exposure dose, CD control was improved by as much as 4 times for substrates with variations in underlying film thickness, compared to using fixed exposure time. The latent image monitor has also been applied to wafers with rough metal substrates and focus optimization.

  4. Latent image exposure monitor using scatterometry

    SciTech Connect

    Milner, L.M.; Hickman, K.C.; Gaspar, S.M.; Bishop, K.P.; Naqvi, S.S.; McNeil, J.R. . Center for High Technology Materials); Blain, M.; Draper, B.L. )

    1992-01-01

    We discuss the use of light scattered from a latent image to control photoresist exposure dose and focus conditions which results in improved control of the critical dimension (CD) of the developed photoresist. A laser at a non-exposing wavelength is used to illuminate a latent image grating. The light diffracted from the grating is directly related to the exposure dose and focus and thus to the resultant CD in the developed resist. Modeling has been done using rigorous coupled wave analysis to predict the diffraction from a latent image as a function of the substrate optical properties and the photoactive compound (PAC) concentration distribution inside the photoresist. It is possible to use the model to solve the inverse problem: given the diffraction, to predict the parameters of the latent image and hence the developed pattern. This latent image monitor can be implemented in a stepper to monitor exposure in situ, or prior to development to predict the developed CD of a wafer for early detection of bad devices. Experimentation has been conducted using various photoresists and substrates with excellent agreement between theoretical and experimental results. The technique has been used to characterize a test pattern with a focused spot as small as 36{mu}m in diameter. Using diffracted light from a simulated closed-loop control of exposure dose, CD control was improved by as much as 4 times for substrates with variations in underlying film thickness, compared to using fixed exposure time. The latent image monitor has also been applied to wafers with rough metal substrates and focus optimization.

  5. Comparative evolution: latent potentials for anagenetic advance.

    PubMed Central

    Stebbins, G L; Hartl, D L

    1988-01-01

    One of the principles that has emerged from experimental evolutionary studies of microorganisms is that polymorphic alleles or new mutations can sometimes possess a latent potential to respond to selection in different environments, although the alleles may be functionally equivalent or disfavored under typical conditions. We suggest that such responses to selection in microorganisms serve as experimental models of evolutionary advances that occur over much longer periods of time in higher organisms. We propose as a general evolutionary principle that anagenic advances often come from capitalizing on preexisting latent selection potentials in the presence of novel ecological opportunity. PMID:3293050

  6. Learning Minimal Latent Directed Information Polytrees.

    PubMed

    Etesami, Jalal; Kiyavash, Negar; Coleman, Todd

    2016-09-01

    We propose an approach for learning latent directed polytrees as long as there exists an appropriately defined discrepancy measure between the observed nodes. Specifically, we use our approach for learning directed information polytrees where samples are available from only a subset of processes. Directed information trees are a new type of probabilistic graphical models that represent the causal dynamics among a set of random processes in a stochastic system. We prove that the approach is consistent for learning minimal latent directed trees. We analyze the sample complexity of the learning task when the empirical estimator of mutual information is used as the discrepancy measure. PMID:27391682

  7. TV system for detection of latent fingerprints

    NASA Astrophysics Data System (ADS)

    Li, Ping; Ban, Xianfu; Liu, Shaowu; Ding, Zhenfang

    1993-04-01

    A fingerprint is reliable evidence for recognizing criminals in detecting cases. There are many conventional chemical and physical methods in detecting fingerprints. In this paper, a newly developed portable TV system for detecting a latent fingerprint is described. This system is suited for field reconnaissance of cases as well as for laboratory testing. It can display a latent fingerprint, which is hard to identify and even cannot be displayed by conventional methods, and it can detect prints or stamps which are faded, altered, or falsified, etc.

  8. A further assessment of the Hall-Rodriguez theory of latent inhibition.

    PubMed

    Leung, Hiu Tin; Killcross, A S; Westbrook, R Frederick

    2013-04-01

    The Hall-Rodriguez (G. Hall & G. Rodriguez, 2010, Associative and nonassociative processes in latent inhibition: An elaboration of the Pearce-Hall model, in R. E. Lubow & I. Weiner, Eds., Latent inhibition: Data, theories, and applications to schizophrenia, pp. 114-136, Cambridge, England: Cambridge University Press) theory of latent inhibition predicts that it will be deepened when a preexposed target stimulus is given additional preexposures in compound with (a) a novel stimulus or (b) another preexposed stimulus, and (c) that deepening will be greater when the compound contains a novel rather than another preexposed stimulus. A series of experiments studied these predictions using a fear conditioning procedure with rats. In each experiment, rats were preexposed to 3 stimuli, 1 (A) taken from 1 modality (visual or auditory) and the remaining 2 (X and Y) taken from another modality (auditory or visual). Then A was compounded with X, and Y was compounded with a novel stimulus (B) taken from the same modality as A. A previous series of experiments (H. T. Leung, A. S. Killcross, & R. F. Westbrook, 2011, Additional exposures to a compound of two preexposed stimuli deepen latent inhibition, Journal of Experimental Psychology: Animal Behavior Processes, Vol. 37, pp. 394-406) compared A with Y, finding that A was more latently inhibited than Y, the opposite of what was predicted. The present experiments confirmed that A was more latently inhibited than Y, showed that this was due to A entering the compound more latently inhibited than Y, and finally, that a comparison of X and Y confirmed the 3 predictions made by the theory. PMID:23586536

  9. Latent Fingerprint Matching: Performance Gain via Feedback from Exemplar Prints.

    PubMed

    Arora, Sunpreet S; Liu, Eryun; Cao, Kai; Jain, Anil K

    2014-12-01

    Latent fingerprints serve as an important source of forensic evidence in a court of law. Automatic matching of latent fingerprints to rolled/plain (exemplar) fingerprints with high accuracy is quite vital for such applications. However, latent impressions are typically of poor quality with complex background noise which makes feature extraction and matching of latents a significantly challenging problem. We propose incorporating top-down information or feedback from an exemplar to refine the features extracted from a latent for improving latent matching accuracy. The refined latent features (e.g. ridge orientation and frequency), after feedback, are used to re-match the latent to the top K candidate exemplars returned by the baseline matcher and resort the candidate list. The contributions of this research include: (i) devising systemic ways to use information in exemplars for latent feature refinement, (ii) developing a feedback paradigm which can be wrapped around any latent matcher for improving its matching performance, and (iii) determining when feedback is actually necessary to improve latent matching accuracy. Experimental results show that integrating the proposed feedback paradigm with a state-of-the-art latent matcher improves its identification accuracy by 0.5-3.5 percent for NIST SD27 and WVU latent databases against a background database of 100k exemplars. PMID:26353151

  10. Demonstration of Super Cooled Ice as a Phase Change Material Heat Sink for Portable Life Support Systems

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Bue, Grant C.

    2009-01-01

    A phase change material (PCM) heat sink using super cooled ice as a nontoxic, nonflammable PCM is being developed. The latent heat of fusion for water is approximately 70% larger than most paraffin waxes, which can provide significant mass savings. Further mass reduction is accomplished by super cooling the ice significantly below its freezing temperature for additional sensible heat storage. Expansion and contraction of the water as it freezes and melts is accommodated with the use of flexible bag and foam materials. A demonstrator unit has been designed, built, and tested to demonstrate proof of concept. Both testing and modeling results are presented along with recommendations for further development of this technology.

  11. Latent Trait Estimation: Theory vs. Practice.

    ERIC Educational Resources Information Center

    Kolakowski, Donald

    Empirical results are presented as regards the implementation of a latent-trait psychometric model by means of conditional maximum likelihood estimation. Items are scored polychotomously into varying numbers of nominal categories and the test and item characteristic curves and information functions are examined. It is concluded that scoring items…

  12. Detection of latent prints by Raman imaging

    SciTech Connect

    Lewis, Linda Anne; Connatser, Raynella Magdalene; Lewis, Sr., Samuel Arthur

    2011-01-11

    The present invention relates to a method for detecting a print on a surface, the method comprising: (a) contacting the print with a Raman surface-enhancing agent to produce a Raman-enhanced print; and (b) detecting the Raman-enhanced print using a Raman spectroscopic method. The invention is particularly directed to the imaging of latent fingerprints.

  13. Immune Function and Reactivation of Latent Viruses

    NASA Technical Reports Server (NTRS)

    Butel, Janet S.

    1999-01-01

    A major concern associated with long-duration space flight is the possibility of infectious diseases posing an unacceptable medical risk to crew members. One major hypothesis addressed in this project is that space flight will cause alterations in the immune system that will allow latent viruses that are endogenous in the human population to reactivate and shed to higher levels than normal, which may affect the health of crew members. The second major hypothesis being examined is that the effects of space flight will alter the mucosal immune system, the first line of defense against many microbial infections, including herpesviruses, polyomaviruses, and gastroenteritis viruses, rendering crew members more susceptible to virus infections across the mucosa. We are focusing the virus studies on the human herpesviruses and polyomaviruses, important pathogens known to establish latent infections in most of the human population. Both primary infection and reactivation from latent infection with these groups of viruses (especially certain herpesviruses) can cause a variety of illnesses that result in morbidity and, occasionally, mortality. Both herpesviruses and polyomaviruses have been associated with human cancer, as well. Effective vaccines exist for only one of the eight known human herpesviruses and available antivirals are of limited use. Whereas normal individuals display minimal consequences from latent viral infections, events which alter immune function (such as immunosuppressive therapy following solid organ transplantation) are known to increase the risk of complications as a result of viral reactivations.

  14. Forensic Chemistry: The Revelation of Latent Fingerprints

    ERIC Educational Resources Information Center

    Friesen, J. Brent

    2015-01-01

    The visualization of latent fingerprints often involves the use of a chemical substance that creates a contrast between the fingerprint residues and the surface on which the print was deposited. The chemical-aided visualization techniques can be divided into two main categories: those that chemically react with the fingerprint residue and those…

  15. Residual Structures in Latent Growth Curve Modeling

    ERIC Educational Resources Information Center

    Grimm, Kevin J.; Widaman, Keith F.

    2010-01-01

    Several alternatives are available for specifying the residual structure in latent growth curve modeling. Two specifications involve uncorrelated residuals and represent the most commonly used residual structures. The first, building on repeated measures analysis of variance and common specifications in multilevel models, forces residual variances…

  16. Hierarchical Latent Trait Approach in Test Analysis.

    ERIC Educational Resources Information Center

    Dimitrov, Dimiter M.

    An approach is described that reveals the hierarchical test structure (HTS) based on the cognitive demands of the test items, and conducts a linear trait modeling by using the HST elements as item difficulty components. This approach, referred to as the Hierarchical Latent Trait Approach (HLTA), employs an algorithm that allows all test items to…

  17. Component Latent Trait Models for Test Design.

    ERIC Educational Resources Information Center

    Embretson, Susan Whitely

    Latent trait models are presented that can be used for test design in the context of a theory about the variables that underlie task performance. Examples of methods for decomposing and testing hypotheses about the theoretical variables in task performance are given. The methods can be used to determine the processing components that are involved…

  18. Latent TGF-β-binding proteins

    PubMed Central

    Robertson, Ian B.; Horiguchi, Masahito; Zilberberg, Lior; Dabovic, Branka; Hadjiolova, Krassimira; Rifkin, Daniel B.

    2016-01-01

    The LTBPs (or latent transforming growth factor β binding proteins) are important components of the extracellular matrix (ECM) that interact with fibrillin microfibrils and have a number of different roles in microfibril biology. There are four LTBPs isoforms in the human genome (LTBP-1, -2, -3, and -4), all of which appear to associate with fibrillin and the biology of each isoform is reviewed here. The LTBPs were first identified as forming latent complexes with TGFβ by covalently binding the TGFβ propeptide (LAP) via disulfide bonds in the endoplasmic reticulum. LAP in turn is cleaved from the mature TGFβ precursor in the trans golgi network but LAP and TGFβ remain strongly bound through non-covalent interactions. LAP, TGFβ, and LTBP together form the large latent complex (LLC). LTBPs were originally thought to primarily play a role in maintaining TGFβ latency and targeting the latent growth factor to the extracellular matrix (ECM), but it has also been shown that LTBP-1 participates in TGFβ activation by integrins and may also regulate activation by proteases and other factors. LTBP-3 appears to have a role in skeletal formation including tooth development. As well as having important functions in TGFβ regulation, TGFβ-independent activities have recently been identified for LTBP-2 and LTBP-4 in stabilizing microfibril bundles and regulating elastic fiber assembly. PMID:25960419

  19. Generalized Structured Component Analysis with Latent Interactions

    ERIC Educational Resources Information Center

    Hwang, Heungsun; Ho, Moon-Ho Ringo; Lee, Jonathan

    2010-01-01

    Generalized structured component analysis (GSCA) is a component-based approach to structural equation modeling. In practice, researchers may often be interested in examining the interaction effects of latent variables. However, GSCA has been geared only for the specification and testing of the main effects of variables. Thus, an extension of GSCA…

  20. Confirmatory Measurement Model Comparisons Using Latent Means.

    ERIC Educational Resources Information Center

    Millsap, Roger E.; Everson, Howard

    1991-01-01

    Use of confirmatory factor analysis (CFA) with nonzero latent means in testing six different measurement models from classical test theory is discussed. Implications of the six models for observed mean and covariance structures are described, and three examples of the use of CFA in testing the models are presented. (SLD)

  1. Atmospheric Diabatic Heating Distributions Derived from a Combination of Satellite Sensor Data

    NASA Astrophysics Data System (ADS)

    Olson, W. S.; L'Ecuyer, T. S.; Gu, G.; Grecu, M.; Bosilovich, M. G.

    2010-12-01

    Satellite estimates of atmospheric latent+eddy heating (Q1-QR) and radiative heating (QR) are combined to yield estimates of the large-scale diabatic heating, or apparent heat source (Q1). The latent+eddy and radiative heating estimates rely on cloud and precipitation information from TRMM Microwave Imager (TMI) data, with additional cloud information supplied by the TRMM Visible and Infrared Scanner (VIRS) and clear-air environmental properties from NCEP reanalyses. Comparisons of the diabatic heating estimates to those derived primarily from the TRMM Precipitation Radar (PR) and from rawinsonde diagnostic budgets are favorable, although some biases due to differences in sampling and the limited sensitivity of the TMI are noted. The addition of an approximate Q1-QR estimate for non-precipitating regions leads to mean heating from precipitating/non-precipitating Q1-QR and mean cooling from QR in the troposphere that are roughly balanced over the TRMM domain. Recently, an eleven-year database of diabatic heating has been constructed using TRMM observations from 1998-2008, as part of NASA’s Energy and Water cycle Study (NEWS) program. Initial applications of this dataset have been the delineation of the seasonal cycle in the tropics/subtropics, the distribution of heating anomalies associated with the phases of ENSO, and the progression of heating in the Madden Julian Oscillation. Preliminary comparisons of satellite heating estimates versus model-based heating and dynamical fields from the Modern Era Retrospective-Analysis for Research and Applications (MERRA) will be presented at the conference.

  2. Class Evolution Tree: A Graphical Tool to Support Decisions on the Number of Classes in Exploratory Categorical Latent Variable Modeling for Rehabilitation Research

    ERIC Educational Resources Information Center

    Kriston, Levente; Melchior, Hanne; Hergert, Anika; Bergelt, Corinna; Watzke, Birgit; Schulz, Holger; von Wolff, Alessa

    2011-01-01

    The aim of our study was to develop a graphical tool that can be used in addition to standard statistical criteria to support decisions on the number of classes in explorative categorical latent variable modeling for rehabilitation research. Data from two rehabilitation research projects were used. In the first study, a latent profile analysis was…

  3. Assessment of input uncertainty by seasonally categorized latent variables using SWAT

    NASA Astrophysics Data System (ADS)

    Yen, Haw; Su, Yu-Wen; Wolfe, June E.; Chen, Shien-Tsung; Hsu, Yu-Chao; Tseng, Wen-Hsiao; Brady, Dawn M.; Jeong, Jaehak; Arnold, Jeffrey G.

    2015-12-01

    Watershed processes have been explored with sophisticated simulation models for the past few decades. It has been stated that uncertainty attributed to alternative sources such as model parameters, forcing inputs, and measured data should be incorporated during the simulation process. Among varying uncertainty sources, input uncertainty attributed to precipitation data exhibits a dominant role, as it is the source driving most hydrologically-related processes. In previous studies, latent variables (normally distributed random noise) have been implemented to explicitly incorporate input uncertainty from precipitation data. However, it may not be appropriate to apply the same set of latent variables throughout temporal series without considering seasonal effects. In this study, seasonally categorized latent variables were defined to investigate potential effects on model predictions and associated predictive uncertainty. Results show that the incorporation of seasonal latent variables resulted in better statistical solutions (NSE, Nash-Sutcliffe Efficiency coefficient) for both calibration (0.58[streamflow]/0.73[sediment]/0.59[ammonia]) and validation (0.57[streamflow]/0.45[sediment]/0.53[ammonia]) periods. Alternative definitions of Dry/Wet seasonality (two definitions are defined in this study) also affected model predictions. In addition, it was determined that predictive uncertainty can be enhanced by incorporating more latent variables during model calibration. The implementations of proposed seasonal latent variables have further substantiated the importance of incorporating seasonal effects when conducting comparable approaches. Applications of latent variables on future work should evaluate potential effects on model predictions before performing associated scientific studies or relevant decision making processes.

  4. Thermal energy storage heat exchanger: Molten salt heat exchanger design for utility power plants

    NASA Technical Reports Server (NTRS)

    Ferarra, A.; Yenetchi, G.; Haslett, R.; Kosson, R.

    1977-01-01

    Sizing procedures are presented for latent heat thermal energy storage systems that can be used for electric utility off-peak energy storage, solar power plants and other preliminary design applications.

  5. A General Approach to Defining Latent Growth Components

    ERIC Educational Resources Information Center

    Mayer, Axel; Steyer, Rolf; Mueller, Horst

    2012-01-01

    We present a 3-step approach to defining latent growth components. In the first step, a measurement model with at least 2 indicators for each time point is formulated to identify measurement error variances and obtain latent variables that are purged from measurement error. In the second step, we use contrast matrices to define the latent growth…

  6. Fingerprint Minutiae from Latent and Matching Tenprint Images

    National Institute of Standards and Technology Data Gateway

    NIST Fingerprint Minutiae from Latent and Matching Tenprint Images (PC database for purchase)   NIST Special Database 27 contains latent fingerprints from crime scenes and their matching rolled fingerprint mates. This database can be used to develop and test new fingerprint algorithms, test commercial and research AFIS systems, train latent examiners, and promote the ANSI/NIST file format standard.

  7. The Latent Speaker: Attaining Adult Fluency in an Endangered Language

    ERIC Educational Resources Information Center

    Basham, Charlotte; Fathman, Ann

    2008-01-01

    This paper focuses on how latent knowledge of an ancestral or heritage language affects subsequent acquisition by adults. The "latent speaker" is defined as an individual raised in an environment where the ancestral language was spoken but who did not become a speaker of that language. The study examines how attitudes, latent knowledge and…

  8. A Note on Cluster Effects in Latent Class Analysis

    ERIC Educational Resources Information Center

    Kaplan, David; Keller, Bryan

    2011-01-01

    This article examines the effects of clustering in latent class analysis. A comprehensive simulation study is conducted, which begins by specifying a true multilevel latent class model with varying within- and between-cluster sample sizes, varying latent class proportions, and varying intraclass correlations. These models are then estimated under…

  9. Skills Diagnosis Using IRT-Based Continuous Latent Trait Models

    ERIC Educational Resources Information Center

    Stout, William

    2007-01-01

    This article summarizes the continuous latent trait IRT approach to skills diagnosis as particularized by a representative variety of continuous latent trait models using item response functions (IRFs). First, several basic IRT-based continuous latent trait approaches are presented in some detail. Then a brief summary of estimation, model…

  10. Bayesian Semiparametric Structural Equation Models with Latent Variables

    ERIC Educational Resources Information Center

    Yang, Mingan; Dunson, David B.

    2010-01-01

    Structural equation models (SEMs) with latent variables are widely useful for sparse covariance structure modeling and for inferring relationships among latent variables. Bayesian SEMs are appealing in allowing for the incorporation of prior information and in providing exact posterior distributions of unknowns, including the latent variables. In…

  11. Stochastic Approximation Methods for Latent Regression Item Response Models

    ERIC Educational Resources Information Center

    von Davier, Matthias; Sinharay, Sandip

    2010-01-01

    This article presents an application of a stochastic approximation expectation maximization (EM) algorithm using a Metropolis-Hastings (MH) sampler to estimate the parameters of an item response latent regression model. Latent regression item response models are extensions of item response theory (IRT) to a latent variable model with covariates…

  12. Integrated Evaluation of Latent Viral Reactivation During Spaceflight

    NASA Technical Reports Server (NTRS)

    Pierson, Duane L.; Paloski, W. H. (Technical Monitor)

    2000-01-01

    This application proposes a continuation of our current effort, which has provided the first demonstration of viral reactivation during space flight. We have used the herpesvirus EBV as a model for latent viral reactivation and have shown that increased amounts of EBV DNA were shed by astronauts during space flight. Analysis of the Antarctic space flight analog indicated that the frequency of viral shedding may also increase (along with the increased numbers of virus) during long periods of isolation. However, a number of critical questions remain before the findings may be considered a significant health risk during extended space flight. These include: Are other latent viruses (e.g., other herpesviruses and polyornaviruses) in addition to EBV also reactivated and shed more frequently and/or in higher numbers during space flight? Is the viral reactivation observed in space flight and ground-based analogs mediated through the hypothalamus-pituitary-adrenal (HPA) axis resulting in a decreased cell-mediated immune response? How does detection of viral DNA by PCR analysis correlate with infectious virus? How does the amount of virus found during flight compare with viral levels observed in acute/chronic viral illnesses and in control individuals? This expanded study will examine the phenomenon of viral reactivation from the initiating stress through the HPA axis with the accompanying suppression of the immune system resulting in viral reactivation. This information is essential to determine if latent viral reactivation among crewmembers represents a sufficient medical risk to space travel to require the development of suitable countermeasures.

  13. Analysis of the freeze/thaw characteristics of external artery heat pipes

    NASA Astrophysics Data System (ADS)

    Lu, Xiaojun

    Monogroove heat pipes are one of the high performance heat pipe configurations planned for use on space station to reject waste heat generated inside the habitation modules. These devices work well under normal operating conditions, however, the working fluid inside the heat pipes may be in a solid state initially, due to the extreme cold conditions encountered during build up. Thus, how the heat pipes behave during the initial startup from a frozen state will determine if the heat pipes will work properly or fail completely. Following is an analysis of the freeze/thaw characteristics of the monogroove heat pipes during the startup from a frozen state in reduced and one-g environments. The startup of monogroove heat pipes from the frozen state at the very early stages is essentially a transient heat conduction problem with phase transformation of the working fluid from a frozen state to a liquid state. Although the heat conduction mechanism is well understood, the addition of a phase transformation introduces a latent heat term and a moving interface between the two phases, making it a highly non-linear problem, which is difficult to solve in a multi-dimensional domain. In this study, a computer model has been developed to solve the frozen startup of monogroove heat pipes. The numerical computation scheme utilizes the fixed grid finite element method with implicit time step procedures. A special technique, referred to as the budget node method is used in the numerical algorithm to accommodate the latent heat and moving boundary problem. Although the computer model is very sensitive to the time step, convergent results can be obtained by appropriate selection of the time step size. To check the validity of the computer model, a simple experimental setup was designed and an experimental work was conducted to compare the experimental data with the results from the numerical model. In general, a good agreement between the numeral and experimental data was obtained.

  14. No improvement in serological response among serofast latent patients retreated with benzathine penicillin.

    PubMed

    Ren, Rong-Xin; Wang, Lin-Na; Zheng, He-Yi; Li, Jun

    2016-01-01

    Persistent non-treponemal titres after treatment are common among patients with latent syphilis. Although retreatment is often done in clinical practice, optimal management remains uncertain due to the paucity of data regarding serological response to retreatment and long-term outcomes. We compared the serological responses of serofast latent syphilis patients retreated with 7.2 million units of benzathine penicillin with the responses of patients who did not receive retreatment (control group). We retrospectively analysed the serological response to therapy following retreatment of 35 serofast latent syphilis patients at 12 months with benzathine penicillin 2.4 million units weekly for 3 weeks. In all, 74.3% (26/35) of the cases with latent syphilis who failed to achieve serological cure at 12 months after initial therapy achieved serological cure after retreatment and after an additional 12 months of follow-up. However, statistically similar serological cure rate was observed in 80.0% (28/35) of the control group (p > .05). Our findings illustrate no improvement in serological response among serofast latent patients retreated with three doses of benzathine penicillin. PMID:25691394

  15. Evaluation of Reliability Coefficients for Two-Level Models via Latent Variable Analysis

    ERIC Educational Resources Information Center

    Raykov, Tenko; Penev, Spiridon

    2010-01-01

    A latent variable analysis procedure for evaluation of reliability coefficients for 2-level models is outlined. The method provides point and interval estimates of group means' reliability, overall reliability of means, and conditional reliability. In addition, the approach can be used to test simple hypotheses about these parameters. The…

  16. Modeling Nonlinear Change via Latent Change and Latent Acceleration Frameworks: Examining Velocity and Acceleration of Growth Trajectories

    ERIC Educational Resources Information Center

    Grimm, Kevin; Zhang, Zhiyong; Hamagami, Fumiaki; Mazzocco, Michele

    2013-01-01

    We propose the use of the latent change and latent acceleration frameworks for modeling nonlinear growth in structural equation models. Moving to these frameworks allows for the direct identification of "rates of change" and "acceleration" in latent growth curves--information available indirectly through traditional growth curve models when change…

  17. Heat Pipes

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

  18. Two Studies of Specification Error in Models for Categorical Latent Variables

    ERIC Educational Resources Information Center

    Kaplan, David; Depaoli, Sarah

    2011-01-01

    This article examines the problem of specification error in 2 models for categorical latent variables; the latent class model and the latent Markov model. Specification error in the latent class model focuses on the impact of incorrectly specifying the number of latent classes of the categorical latent variable on measures of model adequacy as…

  19. Development of latent fingermarks by aqueous electrolytes.

    PubMed

    Jasuja, Om Prakash; Singh, Gagandeep; Almog, Joseph

    2011-04-15

    In this work we present our observations on the interaction between metallic (copper, aluminum, iron, brass, zinc) and non-metallic (glass and plastic) surfaces bearing latent fingermarks and several aqueous electrolytic solutions. Good quality fingermarks could be observed on some of the metallic and even on non-metallic surfaces after such treatment. The influence of factors such as time interval from deposition, pH of the electrolytes, wiping the latent marks prior to processing and the presence of a second metal on the quality and permanence of the developed impressions have been studied. As a rule, sebaceous marks provided much better quality impressions on all the surfaces. Initial explanations based on electrochemical processes are suggested. PMID:21067875

  20. Blocking of potentiation of latent inhibition.

    PubMed

    Hall, Geoffrey; Rodriguez, Gabriel

    2011-01-01

    We present a theory of latent inhibition based on the Pearce-Hall (Pearce & Hall, 1980) model for classical conditioning. Its central features are (1) that the associability of a stimulus declines as it comes to predict its consequences and (2) that nonreinforced exposure to a stimulus engages an associative learning process that makes the stimulus an accurate predictor of its consequences (in this case, the occurrence of no event). A formalization of this theory is shown to accommodate the finding that preexposure in compound with another cue can potentiate latent inhibition to the target cue. It further predicts that preexposure to the added cue will eliminate the potentiation effect. An experiment using rats and the flavor-aversion procedure confirmed this prediction. PMID:20822295

  1. On Latent Trait Estimation in Multidimensional Compensatory Item Response Models.

    PubMed

    Wang, Chun

    2015-06-01

    Making inferences from IRT-based test scores requires accurate and reliable methods of person parameter estimation. Given an already calibrated set of item parameters, the latent trait could be estimated either via maximum likelihood estimation (MLE) or using Bayesian methods such as maximum a posteriori (MAP) estimation or expected a posteriori (EAP) estimation. In addition, Warm's (Psychometrika 54:427-450, 1989) weighted likelihood estimation method was proposed to reduce the bias of the latent trait estimate in unidimensional models. In this paper, we extend the weighted MLE method to multidimensional models. This new method, denoted as multivariate weighted MLE (MWLE), is proposed to reduce the bias of the MLE even for short tests. MWLE is compared to alternative estimators (i.e., MLE, MAP and EAP) and shown, both analytically and through simulations studies, to be more accurate in terms of bias than MLE while maintaining a similar variance. In contrast, Bayesian estimators (i.e., MAP and EAP) result in biased estimates with smaller variability. PMID:24604245

  2. Discovering latent commercial networks from online financial news articles

    NASA Astrophysics Data System (ADS)

    Xia, Yunqing; Su, Weifeng; Lau, Raymond Y. K.; Liu, Yi

    2013-08-01

    Unlike most online social networks where explicit links among individual users are defined, the relations among commercial entities (e.g. firms) may not be explicitly declared in commercial Web sites. One main contribution of this article is the development of a novel computational model for the discovery of the latent relations among commercial entities from online financial news. More specifically, a CRF model which can exploit both structural and contextual features is applied to commercial entity recognition. In addition, a point-wise mutual information (PMI)-based unsupervised learning method is developed for commercial relation identification. To evaluate the effectiveness of the proposed computational methods, a prototype system called CoNet has been developed. Based on the financial news articles crawled from Google finance, the CoNet system achieves average F-scores of 0.681 and 0.754 in commercial entity recognition and commercial relation identification, respectively. Our experimental results confirm that the proposed shallow natural language processing methods are effective for the discovery of latent commercial networks from online financial news.

  3. Effects of dietary addition of heat-killed Mycobacterium phlei on growth performance, immune status and anti-oxidative capacity in early weaned piglets.

    PubMed

    Zhong, Jin-Feng; Wu, Wei-Gao; Zhang, Xiao-Qing; Tu, Wei; Liu, Zhen-Xiang; Fang, Re-Jun

    2016-08-01

    The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses. PMID:27216553

  4. The observed impacts of South Asian summer monsoon on the near-surface turbulent heat exchange over the Southeast Tibet

    NASA Astrophysics Data System (ADS)

    Zhou, Libo

    2016-04-01

    The Southeast Tibet is an important region of the Tibetan Plateau bearing the interaction between the Tibetan and the neighbor atmospheric systems. The South Asian summer monsoon (SASM) as a basic climate system in Asia could impact the local atmosphere and the near-surface heat exchange process in the Southeast Tibet. An observational campaign, OSEP2013, was carried out in this region during SASM in 2013. The atmospheric parameters and turbulent heat fluxes were observed and averaged over three different land surfaces of the inhomogeneous landscape during the observation campaign. Results show clear SASM impacts on the local atmosphere and near-surface heat exchange in the Southeast Tibet. The South Asian summer monsoon was onset on June 1, 2013, and experienced a south phase and north phase during OSEP2013. The convection and humidity were increased in the Southeast Tibet by SASM, especially during the north phase. The observation domain received low radiation energy due to the convective clouds brought by SASM, and the soil and air temperatures were lowered as consequence. In addition, the air humidity was increased over this region by the wet air transportation of SASM circulation. The sensible and latent heat transfers were decreased by the low land-air temperature difference and high air humidity during SASM. The latent heat transfer dominated the total heat transfer in the Southeast Tibet due to the low sensible heat transfer in the SASM situation, and the domination was increased as the sensible heat transfer was further decreased during the SASM north phase.

  5. Phase-Change Heat-Storage Module

    NASA Technical Reports Server (NTRS)

    Mulligan, James C.

    1989-01-01

    Heat-storage module accommodates momentary heating or cooling overload in pumped-liquid heat-transfer system. Large heat-storage capacity of module provided by heat of fusion of material that freezes at or near temperature desired to maintain object to be heated or cooled. Module involves relatively small penalties in weight, cost, and size and more than compensates by enabling design of rest of system to handle only average load. Latent heat of fusion of phase-change material provides large heat-storage capacity in small volume.

  6. Non-destructive forensic latent fingerprint acquisition with chromatic white light sensors

    NASA Astrophysics Data System (ADS)

    Leich, Marcus; Kiltz, Stefan; Dittmann, Jana; Vielhauer, Claus

    2011-02-01

    Non-destructive latent fingerprint acquisition is an emerging field of research, which, unlike traditional methods, makes latent fingerprints available for additional verification or further analysis like tests for substance abuse or age estimation. In this paper a series of tests is performed to investigate the overall suitability of a high resolution off-the-shelf chromatic white light sensor for the contact-less and non-destructive latent fingerprint acquisition. Our paper focuses on scanning previously determined regions with exemplary acquisition parameter settings. 3D height field and reflection data of five different latent fingerprints on six different types of surfaces (HDD platter, brushed metal, painted car body (metallic and non-metallic finish), blued metal, veneered plywood) are experimentally studied. Pre-processing is performed by removing low-frequency gradients. The quality of the results is assessed subjectively; no automated feature extraction is performed. Additionally, the degradation of the fingerprint during the acquisition period is observed. While the quality of the acquired data is highly dependent on surface structure, the sensor is capable of detecting the fingerprint on all sample surfaces. On blued metal the residual material is detected; however, the ridge line structure dissolves within minutes after fingerprint placement.

  7. Influence of self heating and Li{sub 2}SO{sub 4} addition on the microstructural development of calcium aluminate cement

    SciTech Connect

    Gosselin, Christophe Gallucci, Emmanuel; Scrivener, Karen

    2010-10-15

    Hydrated Calcium Aluminate Cement (CAC) is known to have a complex microstructure involving different phase assemblages strongly dependant on the temperature. This work presents an experimental approach to study the microstructure of CAC pastes from the first minute of hydration with controlled time-temperature histories up to several months of curing. The self heating usually occurring in the CAC concrete is considered and its influence on the growth and assemblage of the hydration products and subsequent space filling is shown. Quantification of the degree of CA hydration by BSE image analysis is used to understand the evolution of phases throughout the hydration process. Lithium sulphate is commonly used to control the setting time of CAC based materials. It is shown that this promotes the formation of more stable hydrates, but slightly reduces the extent of CA hydration.

  8. Estimates of zonally averaged tropical diabatic heating in AMIP GCM simulations. PCMDI report No. 25

    SciTech Connect

    Boyle, J.S.

    1995-07-01

    An understanding of the processess that generate the atmospheric diabatic heating rates is basic to an understanding of the time averaged general circulation of the atmosphere and also circulation anomalies. Knowledge of the sources and sinks of atmospheric heating enables a fuller understanding of the nature of the atmospheric circulation. An actual assesment of the diabatic heating rates in the atmosphere is a difficult problem that has been approached in a number of ways. One way is to estimate the total diabatic heating by estimating individual components associated with the radiative fluxes, the latent heat release, and sensible heat fluxes. An example of this approach is provided by Newell. Another approach is to estimate the net heating rates from consideration of the balance required of the mass and wind variables as routinely observed and analyzed. This budget computation has been done using the thermodynamic equation and more recently done by using the vorticity and thermodynamic equations. Schaak and Johnson compute the heating rates through the integration of the isentropic mass continuity equation. The estimates of heating arrived at all these methods are severely handicapped by the uncertainties in the observational data and analyses. In addition the estimates of the individual heating components suffer an additional source of error from the parameterizations used to approximate these quantities.

  9. Restoring Latent Visual Working Memory Representations in Human Cortex.

    PubMed

    Sprague, Thomas C; Ester, Edward F; Serences, John T

    2016-08-01

    Working memory (WM) enables the storage and manipulation of limited amounts of information over short periods. Prominent models posit that increasing the number of remembered items decreases the spiking activity dedicated to each item via mutual inhibition, which irreparably degrades the fidelity of each item's representation. We tested these models by determining if degraded memory representations could be recovered following a post-cue indicating which of several items in spatial WM would be recalled. Using an fMRI-based image reconstruction technique, we identified impaired behavioral performance and degraded mnemonic representations with elevated memory load. However, in several cortical regions, degraded mnemonic representations recovered substantially following a post-cue, and this recovery tracked behavioral performance. These results challenge pure spike-based models of WM and suggest that remembered items are additionally encoded within latent or hidden neural codes that can help reinvigorate active WM representations. PMID:27497224

  10. Stereotype Threat and College Academic Performance: A Latent Variables Approach*

    PubMed Central

    Owens, Jayanti; Massey, Douglas S.

    2013-01-01

    Stereotype threat theory has gained experimental and survey-based support in helping explain the academic underperformance of minority students at selective colleges and universities. Stereotype threat theory states that minority students underperform because of pressures created by negative stereotypes about their racial group. Past survey-based studies, however, are characterized by methodological inefficiencies and potential biases: key theoretical constructs have only been measured using summed indicators and predicted relationships modeled using ordinary least squares. Using the National Longitudinal Survey of Freshman, this study overcomes previous methodological shortcomings by developing a latent construct model of stereotype threat. Theoretical constructs and equations are estimated simultaneously from multiple indicators, yielding a more reliable, valid, and parsimonious test of key propositions. Findings additionally support the view that social stigma can indeed have strong negative effects on the academic performance of pejoratively stereotyped racial-minority group members, not only in laboratory settings, but also in the real world. PMID:23950616

  11. Targeting the latent reservoir to achieve functional HIV cure

    PubMed Central

    Cary, Daniele C.; Peterlin, B. Matija

    2016-01-01

    While highly active anti-retroviral therapy has greatly improved the lives of HIV-infected individuals, current treatments are unable to completely eradicate the virus. This is due to the presence of HIV latently infected cells which harbor transcriptionally silent HIV. Latent HIV does not replicate or produce viral proteins, thereby preventing efficient targeting by anti-retroviral drugs. Strategies to target the HIV latent reservoir include viral reactivation, enhancing host defense mechanisms, keeping latent HIV silent, and using gene therapy techniques to knock out or reactivate latent HIV. While research into each of these areas has yielded promising results, currently no one mechanism eradicates latent HIV. Instead, combinations of these approaches should be considered for a potential HIV functional cure. PMID:27303638

  12. Bayesian Analysis of Multivariate Latent Curve Models with Nonlinear Longitudinal Latent Effects

    ERIC Educational Resources Information Center

    Song, Xin-Yuan; Lee, Sik-Yum; Hser, Yih-Ing

    2009-01-01

    In longitudinal studies, investigators often measure multiple variables at multiple time points and are interested in investigating individual differences in patterns of change on those variables. Furthermore, in behavioral, social, psychological, and medical research, investigators often deal with latent variables that cannot be observed directly…

  13. Dimensionality of the Latent Structure and Item Selection via Latent Class Multidimensional IRT Models

    ERIC Educational Resources Information Center

    Bartolucci, F.; Montanari, G. E.; Pandolfi, S.

    2012-01-01

    With reference to a questionnaire aimed at assessing the performance of Italian nursing homes on the basis of the health conditions of their patients, we investigate two relevant issues: dimensionality of the latent structure and discriminating power of the items composing the questionnaire. The approach is based on a multidimensional item…

  14. A Latent Transition Analysis Model for Latent-State-Dependent Nonignorable Missingness.

    PubMed

    Sterba, Sonya K

    2016-06-01

    Psychologists often use latent transition analysis (LTA) to investigate state-to-state change in discrete latent constructs involving delinquent or risky behaviors. In this setting, latent-state-dependent nonignorable missingness is a potential concern. For some longitudinal models (e.g., growth models), a large literature has addressed extensions to accommodate nonignorable missingness. In contrast, little research has addressed how to extend the LTA to accommodate nonignorable missingness. Here we present a shared parameter LTA that can reduce bias due to latent-state-dependent nonignorable missingness: a parallel-process missing-not-at-random (MNAR-PP) LTA. The MNAR-PP LTA allows outcome process parameters to be interpreted as in the conventional LTA, which facilitates sensitivity analyses assessing changes in estimates between LTA and MNAR-PP LTA. In a sensitivity analysis for our empirical example, previous and current membership in high-delinquency states predicted adolescents' membership in missingness states that had high nonresponse probabilities for some or all items. A conventional LTA overestimated the proportion of adolescents ending up in a low-delinquency state, compared to an MNAR-PP LTA. PMID:25697371

  15. Oxidative Autoactivation of Latent Collagenase by Human Neutrophils

    NASA Astrophysics Data System (ADS)

    Weiss, S. J.; Peppin, G.; Ortiz, X.; Ragsdale, C.; Test, S. T.

    1985-02-01

    The pathological destruction of collagen plays a key role in the development of inflammatory disease states affecting every organ system in the human body. Neutrophils localized at inflammatory sites can potentially degrade collagen by releasing a metalloenzyme, collagenase, which is stored in a latent inactive form. Triggered human neutrophils were shown to release and simultaneously activate their latent collagenase. The activation of the latent enzyme was coupled to an oxidative process that required the generation of a highly reactive oxygen metabolite, hypochlorous acid. Oxidative regulation of latent collagenase activity may be important in the pathogenesis of connective tissue damage in vivo.

  16. Influence of additives on the increase of the heating value of Bayah’s coal with upgrading brown coal (UBC) method

    SciTech Connect

    Heriyanto, Heri; Widya Ernayati, K.; Umam, Chairul; Margareta, Nita

    2015-12-29

    UBC (upgrading brown coal) is a method of improving the quality of coal by using oil as an additive. Through processing in the oil media, not just the calories that increase, but there is also water repellent properties and a decrease in the tendency of spontaneous combustion of coal products produced. The results showed a decrease in the water levels of natural coal bayah reached 69%, increase in calorific value reached 21.2%. Increased caloric value and reduced water content caused by the water molecules on replacing seal the pores of coal by oil and atoms C on the oil that is bound to increase the percentage of coal carbon. As a result of this experiment is, the produced coal has better calorific value, the increasing of this new calorific value up to 23.8% with the additive waste lubricant, and the moisture content reduced up to 69.45%.

  17. Evaluation of the thermal performance of fire fighter protective clothing with the addition of phase change material

    NASA Astrophysics Data System (ADS)

    McCarthy, Lee K.

    Fire fighters rely on fire fighter protective clothing (FFPC) to provide adequate protection in the various hazardous environments they may encounter during operations. FFPC has seen significant advancement in technology over the past few decades. The addition of phase change material (PCM) to FFPC is a new technology with potential to enhance the thermal protection provided by the FFPC. To explore this technology, data from bench-scale experiments involving FFPC with PCMs are compared with a theoretical finite difference heat transfer model. The results demonstrate an effective method to mathematically model the heat transfer and provide insight into the effectiveness of improving the thermal protection of FFPC. The experiments confirm that the latent heat absorbed during the phase change reduces temperatures that might be experienced at the fire fighter's skin surface, advancing the high temperature performance of FFPC.

  18. Causal mediation analysis with a latent mediator.

    PubMed

    Albert, Jeffrey M; Geng, Cuiyu; Nelson, Suchitra

    2016-05-01

    Health researchers are often interested in assessing the direct effect of a treatment or exposure on an outcome variable, as well as its indirect (or mediation) effect through an intermediate variable (or mediator). For an outcome following a nonlinear model, the mediation formula may be used to estimate causally interpretable mediation effects. This method, like others, assumes that the mediator is observed. However, as is common in structural equations modeling, we may wish to consider a latent (unobserved) mediator. We follow a potential outcomes framework and assume a generalized structural equations model (GSEM). We provide maximum-likelihood estimation of GSEM parameters using an approximate Monte Carlo EM algorithm, coupled with a mediation formula approach to estimate natural direct and indirect effects. The method relies on an untestable sequential ignorability assumption; we assess robustness to this assumption by adapting a recently proposed method for sensitivity analysis. Simulation studies show good properties of the proposed estimators in plausible scenarios. Our method is applied to a study of the effect of mother education on occurrence of adolescent dental caries, in which we examine possible mediation through latent oral health behavior. PMID:26363769

  19. Latent TGF-[beta] structure and activation

    SciTech Connect

    Shi, Minlong; Zhu, Jianghai; Wang, Rui; Chen, Xing; Mi, Lizhi; Walz, Thomas; Springer, Timothy A.

    2011-09-16

    Transforming growth factor (TGF)-{beta} is stored in the extracellular matrix as a latent complex with its prodomain. Activation of TGF-{beta}1 requires the binding of {alpha}v integrin to an RGD sequence in the prodomain and exertion of force on this domain, which is held in the extracellular matrix by latent TGF-{beta} binding proteins. Crystals of dimeric porcine proTGF-{beta}1 reveal a ring-shaped complex, a novel fold for the prodomain, and show how the prodomain shields the growth factor from recognition by receptors and alters its conformation. Complex formation between {alpha}v{beta}6 integrin and the prodomain is insufficient for TGF-{beta}1 release. Force-dependent activation requires unfastening of a 'straitjacket' that encircles each growth-factor monomer at a position that can be locked by a disulphide bond. Sequences of all 33 TGF-{beta} family members indicate a similar prodomain fold. The structure provides insights into the regulation of a family of growth and differentiation factors of fundamental importance in morphogenesis and homeostasis.

  20. Improved solar heating systems

    DOEpatents

    Schreyer, J.M.; Dorsey, G.F.

    1980-05-16

    An improved solar heating system is described in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75 to 180/sup 0/F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing ad releasing heat for distribution.

  1. Solar heating system

    DOEpatents

    Schreyer, James M.; Dorsey, George F.

    1982-01-01

    An improved solar heating system in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75.degree. to 180.degree. F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing and releasing heat for distribution.

  2. Subscale Water Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik; Hansen, Scott

    2016-01-01

    Supplemental heat rejection devices are required in many spacecraft as the radiators are not sized to meet the full heat rejection demand. One means of obtaining additional heat rejection is through the use of phase change material heat exchangers (PCM HX's). PCM HX's utilize phase change to store energy in unfavorable thermal environments (melting) and reject the energy in favorable environments (freezing). Traditionally, wax has been used as a PCM on spacecraft. However, water is an attractive alternative because it is capable of storing about 40% more energy per unit mass due to its higher latent heat of fusion. The significant problem in using water as a PCM is its expansion while freezing, leading to structural integrity concerns when housed in an enclosed heat exchanger volume. Significant investigation and development has taken place over the past five years to understand and overcome the problems associated with water PCM HX's. This paper reports on the final efforts by Johnson Space Center's Thermal Systems Branch to develop a water based PCM HX. The test article developed and reported on is a subscale version of the full-scale water-based PCM HX's constructed by Mezzo Technologies. The subscale unit was designed by applying prior research on freeze front propagation and previous full-scale water PCM HX development. Design modifications to the subscale unit included use of urethane bladder, decreased aspect ratio, perforated protection sheet, and use of additional mid-plates. Testing of the subscale unit was successful and 150 cycles were completed without fail.

  3. Water Based Phase Change Material Heat Exchanger Development

    NASA Technical Reports Server (NTRS)

    Hansen, Scott W.; Sheth, Ribik B.; Atwell, Matt; Cheek, Ann; Agarwal, Muskan; Hong, Steven; Patel, Aashini,; Nguyen, Lisa; Posada, Luciano

    2014-01-01

    In a cyclical heat load environment such as low Lunar orbit, a spacecraft’s radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a “topper” to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. Studies conducted in this paper investigate utilizing water’s high latent heat of formation as a PCM, as opposed to traditional waxes, and corresponding complications surrounding freezing water in an enclosed volume. Work highlighted in this study is primarily visual and includes understanding ice formation, freeze front propagation, and the solidification process of water/ice. Various test coupons were constructed of copper to emulate the interstitial pin configuration (to aid in conduction) of the proposed water PCM HX design. Construction of a prototypic HX was also completed in which a flexible bladder material and interstitial pin configurations were tested. Additionally, a microgravity flight was conducted where three copper test articles were frozen continuously during microgravity and 2-g periods and individual water droplets were frozen during microgravity.

  4. Reactivation of Latent HIV-1 Expression by Engineered TALE Transcription Factors

    PubMed Central

    Perdigão, Pedro; Gaj, Thomas; Santa-Marta, Mariana; Goncalves, Joao

    2016-01-01

    The presence of replication-competent HIV-1 –which resides mainly in resting CD4+ T cells–is a major hurdle to its eradication. While pharmacological approaches have been useful for inducing the expression of this latent population of virus, they have been unable to purge HIV-1 from all its reservoirs. Additionally, many of these strategies have been associated with adverse effects, underscoring the need for alternative approaches capable of reactivating viral expression. Here we show that engineered transcriptional modulators based on customizable transcription activator-like effector (TALE) proteins can induce gene expression from the HIV-1 long terminal repeat promoter, and that combinations of TALE transcription factors can synergistically reactivate latent viral expression in cell line models of HIV-1 latency. We further show that complementing TALE transcription factors with Vorinostat, a histone deacetylase inhibitor, enhances HIV-1 expression in latency models. Collectively, these findings demonstrate that TALE transcription factors are a potentially effective alternative to current pharmacological routes for reactivating latent virus and that combining synthetic transcriptional activators with histone deacetylase inhibitors could lead to the development of improved therapies for latent HIV-1 infection. PMID:26933881

  5. Mechanical properties and retained austenite in intercritically heat-treated bainite-transformed steel and their variation with Si and Mn additions

    NASA Astrophysics Data System (ADS)

    Sakuma, Yasuharu; Matsumura, Osamu; Takechi, Hiroshi

    1991-02-01

    Processing peculiarities and functions of alloying elements, such as Si and Mn, were studied for improving formability of steel sheets with mixed microstructures. Annealing a sheet steel with 0.2 pct C in the intercritical range produced very fine particles of retained austenite which were moderately stabilized due to C enrichment by subsequent holding in the bainite transformation range. Its strength-ductility balance is greatly superior to that of other dual-phase steels due to transformation-induced plasticity ( TRIP). The holding time in the bainite transformation range varies with temperature, depending on the activation energy of C diffusion in austenite, and shifts to longer times with an increase of Si or Mn additions. The optimum cooling rate from the intercritical region is reduced with an increase of Mn content but is not influenced by Si content. Additional Mn makes the retained austenite content larger, although uniform elongation remains the same. In this case, the product of tensile strength and total elongation is increased due to an increase in the tensile strength. Contrary to Mn, Si does not affect retained austenite content but improves the uniform elongation by increasing its stability.

  6. Food additives

    MedlinePlus

    Food additives are substances that become part of a food product when they are added during the processing or making of that food. "Direct" food additives are often added during processing to: Add nutrients ...

  7. A finite element analysis of the freeze/thaw behavior of external artery heat pipes

    NASA Technical Reports Server (NTRS)

    Lu, X. J.; Peterson, G. P.

    1993-01-01

    A two-dimensional finite element model was used to determine the freeze/thaw characteristics of an external artery heat pipe. During startup, the working fluid, which was located in the liquid channel and the circumferential wall grooves, experienced a phase transformation from a solid to a liquid state. The transient heat conduction equations with moving interfacial conditions were solved using the appropriate initial boundary conditions. The modelling results include the cross-sectional temperature distribution and the interfacial or melt front position as a function of time. A fixed grid approach was adopted in the model for the phase-change process during thawing of frozen working fluid. The interfacial position between the liquid and solid regions was found by balancing the latent heat caused by interfacial movement with the heat addition or extraction at the related grid points.

  8. Method and apparatus for enhanced heat recovery from steam generators and water heaters

    DOEpatents

    Knight, Richard A.; Rabovitser, Iosif K.; Wang, Dexin

    2006-06-27

    A heating system having a steam generator or water heater, at least one economizer, at least one condenser and at least one oxidant heater arranged in a manner so as to reduce the temperature and humidity of the exhaust gas (flue gas) stream and recover a major portion of the associated sensible and latent heat. The recovered heat is returned to the steam generator or water heater so as to increase the quantity of steam generated or water heated per quantity of fuel consumed. In addition, a portion of the water vapor produced by combustion of fuel is reclaimed for use as feed water, thereby reducing the make-up water requirement for the system.

  9. Rational molecular dynamics scheme for predicting optimum concentration loading of nano-additive in phase change materials

    NASA Astrophysics Data System (ADS)

    Rastogi, Monisha; Vaish, Rahul; Madhar, Niyaz Ahamad; Shaikh, Hamid; Al-Zahrani, S. M.

    2015-10-01

    The present study deals with the diffusion and phase transition behaviour of paraffin reinforced with carbon nano-additives namely graphene oxide (GO) and surface functionalized single walled carbon nanotubes (SWCNT). Bulk disordered systems of paraffin hydrocarbons impregnated with carbon nano-additives have been generated in realistic equilibrium conformations for potential application as latent heat storage systems. Ab initio molecular dynamics(MD) in conjugation with COMPASS forcefield has been implemented using periodic boundary conditions. The proposed scheme allows determination of optimum nano-additive loading for improving thermo-physical properties through analysis of mass, thermal and transport properties; and assists in determination of composite behaviour and related performance from microscopic point of view. It was observed that nanocomposites containing 7.8 % surface functionalised SWCNT and 55% GO loading corresponds to best latent heat storage system. The propounded methodology could serve as a by-pass route for economically taxing and iterative experimental procedures required to attain the optimum composition for best performance. The results also hint at the large unexplored potential of ab-initio classical MD techniques for predicting performance of new nanocomposites for potential phase change material applications.

  10. Development of an inverse heat conduction model and its application to determination of heat transfer coefficient during casting solidification

    NASA Astrophysics Data System (ADS)

    Zhang, Liqiang; Reilly, Carl; Li, Luoxing; Cockcroft, Steve; Yao, Lu

    2014-07-01

    The interfacial heat transfer coefficient (IHTC) is required for the accurate simulation of heat transfer in castings especially for near net-shape processes. The large number of factors influencing heat transfer renders quantification by theoretical means a challenge. Likewise experimental methods applied directly to temperature data collected from castings are also a challenge to interpret because of the transient nature of many casting processes. Inverse methods offer a solution and have been applied successfully to predict the IHTC in many cases. However, most inverse approaches thus far focus on use of in-mold temperature data, which may be a challenge to obtain in cases where the molds are water-cooled. Methods based on temperature data from the casting have the potential to be used however; the latent heat released during the solidification of the molten metal complicates the associated IHTC calculations. Furthermore, there are limits on the maximum distance the thermocouples can be placed from the interface under analysis. An inverse conduction based method have been developed, verified and applied successfully to temperature data collected from within an aluminum casting in proximity to the mold. A modified specific heat method was used to account for latent heat evolution in which the rate of change of fraction solid with temperature was held constant. An analysis conducted with the inverse model suggests that the thermocouples must be placed no more than 2 mm from the interface. The IHTC values calculated for an aluminum alloy casting were shown to vary from 1,200 to 6,200 Wm-2 K-1. Additionally, the characteristics of the time-varying IHTC have also been discussed.

  11. Food additives

    PubMed Central

    Spencer, Michael

    1974-01-01

    Food additives are discussed from the food technology point of view. The reasons for their use are summarized: (1) to protect food from chemical and microbiological attack; (2) to even out seasonal supplies; (3) to improve their eating quality; (4) to improve their nutritional value. The various types of food additives are considered, e.g. colours, flavours, emulsifiers, bread and flour additives, preservatives, and nutritional additives. The paper concludes with consideration of those circumstances in which the use of additives is (a) justified and (b) unjustified. PMID:4467857

  12. ESTIMATION OF BARE-SOIL EVAPORATION USING A CALORIMETRIC APPROACH WITH HEAT FLUX MEASURED AT MULTIPLE DEPTHS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An assumption in calorimetric methods for soil heat flux is that sensible heat terms can be balanced (i.e., if the heat flux is known at one depth, the heat flux at another depth may be determined by monitoring the change in heat storage). Latent heat from water evaporation is assigned to the energy...

  13. Higher-Order Item Response Models for Hierarchical Latent Traits

    ERIC Educational Resources Information Center

    Huang, Hung-Yu; Wang, Wen-Chung; Chen, Po-Hsi; Su, Chi-Ming

    2013-01-01

    Many latent traits in the human sciences have a hierarchical structure. This study aimed to develop a new class of higher order item response theory models for hierarchical latent traits that are flexible in accommodating both dichotomous and polytomous items, to estimate both item and person parameters jointly, to allow users to specify…

  14. A Simplified Estimation of Latent State--Trait Parameters

    ERIC Educational Resources Information Center

    Hagemann, Dirk; Meyerhoff, David

    2008-01-01

    The latent state-trait (LST) theory is an extension of the classical test theory that allows one to decompose a test score into a true trait, a true state residual, and an error component. For practical applications, the variances of these latent variables may be estimated with standard methods of structural equation modeling (SEM). These…

  15. The Latent Variable Approach as Applied to Transitive Reasoning

    ERIC Educational Resources Information Center

    Bouwmeester, Samantha; Vermunt, Jeroen K.; Sijtsma, Klaas

    2012-01-01

    We discuss the limitations of hypothesis testing using (quasi-) experiments in the study of cognitive development and suggest latent variable modeling as a viable alternative to experimentation. Latent variable models allow testing a theory as a whole, incorporating individual differences with respect to developmental processes or abilities in the…

  16. PROC LCA: A SAS Procedure for Latent Class Analysis

    ERIC Educational Resources Information Center

    Lanza, Stephanie T.; Collins, Linda M.; Lemmon, David R.; Schafer, Joseph L.

    2007-01-01

    Latent class analysis (LCA) is a statistical method used to identify a set of discrete, mutually exclusive latent classes of individuals based on their responses to a set of observed categorical variables. In multiple-group LCA, both the measurement part and structural part of the model can vary across groups, and measurement invariance across…

  17. Conducting Confirmatory Latent Class Analysis Using M"plus"

    ERIC Educational Resources Information Center

    Finch, W. Holmes; Bronk, Kendall Cotton

    2011-01-01

    Latent class analysis (LCA) is an increasingly popular tool that researchers can use to identify latent groups in the population underlying a sample of responses to categorical observed variables. LCA is most commonly used in an exploratory fashion whereby no parameters are specified a priori. Although this exploratory approach is reasonable when…

  18. Use of Latent Profile Analysis in Studies of Gifted Students

    ERIC Educational Resources Information Center

    Mammadov, Sakhavat; Ward, Thomas J.; Cross, Jennifer Riedl; Cross, Tracy L.

    2016-01-01

    To date, in gifted education and related fields various conventional factor analytic and clustering techniques have been used extensively for investigation of the underlying structure of data. Latent profile analysis is a relatively new method in the field. In this article, we provide an introduction to latent profile analysis for gifted education…

  19. A Review of the Latent and Manifest Benefits (LAMB) Scale

    ERIC Educational Resources Information Center

    Muller, Juanita; Waters, Lea

    2012-01-01

    The latent and manifest benefits (LAMB) scale (Muller, Creed, Waters & Machin, 2005) was designed to measure the latent and manifest benefits of employment and provide a single scale to test Jahoda's (1981) and Fryer's (1986) theories of unemployment. Since its publication in 2005 there have been 13 studies that have used the scale with 5692…

  20. Transforming Selected Concepts into Dimensions in Latent Semantic Analysis

    ERIC Educational Resources Information Center

    Olmos, Ricardo; Jorge-Botana, Guillermo; León, José Antonio; Escudero, Inmaculada

    2014-01-01

    This study presents a new approach for transforming the latent representation derived from a Latent Semantic Analysis (LSA) space into one where dimensions have nonlatent meanings. These meanings are based on lexical descriptors, which are selected by the LSA user. The authors present three analyses that provide examples of the utility of this…

  1. Nonlinear Latent Curve Models for Multivariate Longitudinal Data

    ERIC Educational Resources Information Center

    Blozis, Shelley A.; Conger, Katherine J.; Harring, Jeffrey R.

    2007-01-01

    Latent curve models have become a useful approach to analyzing longitudinal data, due in part to their allowance of and emphasis on individual differences in features that describe change. Common applications of latent curve models in developmental studies rely on polynomial functions, such as linear or quadratic functions. Although useful for…

  2. Nonlinear and Quasi-Simplex Patterns in Latent Growth Models

    ERIC Educational Resources Information Center

    Bianconcini, Silvia

    2012-01-01

    In the SEM literature, simplex and latent growth models have always been considered competing approaches for the analysis of longitudinal data, even if they are strongly connected and both of specific importance. General dynamic models, which simultaneously estimate autoregressive structures and latent curves, have been recently proposed in the…

  3. Intercept Centering and Time Coding in Latent Difference Score Models

    ERIC Educational Resources Information Center

    Grimm, Kevin J.

    2012-01-01

    Latent difference score (LDS) models combine benefits derived from autoregressive and latent growth curve models allowing for time-dependent influences and systematic change. The specification and descriptions of LDS models include an initial level of ability or trait plus an accumulation of changes. A limitation of this specification is that the…

  4. Hypothesis Generation in Latent Growth Curve Modeling Using Principal Components

    ERIC Educational Resources Information Center

    Davison, Mark L.

    2008-01-01

    While confirmatory latent growth curve analyses provide procedures for testing hypotheses about latent growth curves underlying data, one must first derive hypotheses to be tested. It is argued that such hypotheses should be generated from a combination of theory and exploratory data analyses. An exploratory components analysis is described and…

  5. Evaluating Latent Growth Curve Models Using Individual Fit Statistics

    ERIC Educational Resources Information Center

    Coffman, Donna L.; Millsap, Roger E.

    2006-01-01

    The usefulness of assessing individual fit in latent growth curve models was examined. The study used simulated data based on an unconditional and a conditional latent growth curve model with a linear component and a small quadratic component and a linear model was fit to the data. Then the overall fit of linear and quadratic models to these data…

  6. Spurious Latent Classes in the Mixture Rasch Model

    ERIC Educational Resources Information Center

    Alexeev, Natalia; Templin, Jonathan; Cohen, Allan S.

    2011-01-01

    Mixture Rasch models have been used to study a number of psychometric issues such as goodness of fit, response strategy differences, strategy shifts, and multidimensionality. Although these models offer the potential for improving understanding of the latent variables being measured, under some conditions overextraction of latent classes may…

  7. A latent variable transformation model approach for exploring dysphagia.

    PubMed

    Snavely, Anna C; Harrington, David P; Li, Yi

    2014-11-10

    Multiple outcomes are often collected in applications where the quantity of interest cannot be measured directly or is difficult or expensive to measure. In a head and neck cancer study conducted at Dana-Farber Cancer Institute, the investigators wanted to determine the effect of clinical and treatment factors on unobservable dysphagia through collected multiple outcomes of mixed types. Latent variable models are commonly adopted in this setting. These models stipulate that multiple collected outcomes are conditionally independent given the latent factor. Mixed types of outcomes (e.g., continuous vs. ordinal) and censored outcomes present statistical challenges, however, as a natural analog of the multivariate normal distribution does not exist for mixed data. Recently, Lin et al. proposed a semiparametric latent variable transformation model for mixed outcome data; however, it may not readily accommodate event time outcomes where censoring is present. In this paper, we extend the work of Lin et al. by proposing both semiparametric and parametric latent variable models that allow for the estimation of the latent factor in the presence of measurable outcomes of mixed types, including censored outcomes. Both approaches allow for a direct estimate of the treatment (or other covariate) effect on the unobserved latent variable, greatly enhancing the interpretability of the models. The semiparametric approach has the added advantage of allowing the relationship between the measurable outcomes and latent variables to be unspecified, rendering more robust inference. The parametric and semiparametric models can also be used together, providing a comprehensive modeling strategy for complicated latent variable problems. PMID:24974798

  8. A Bayesian Semiparametric Latent Variable Model for Mixed Responses

    ERIC Educational Resources Information Center

    Fahrmeir, Ludwig; Raach, Alexander

    2007-01-01

    In this paper we introduce a latent variable model (LVM) for mixed ordinal and continuous responses, where covariate effects on the continuous latent variables are modelled through a flexible semiparametric Gaussian regression model. We extend existing LVMs with the usual linear covariate effects by including nonparametric components for nonlinear…

  9. An Importance Sampling EM Algorithm for Latent Regression Models

    ERIC Educational Resources Information Center

    von Davier, Matthias; Sinharay, Sandip

    2007-01-01

    Reporting methods used in large-scale assessments such as the National Assessment of Educational Progress (NAEP) rely on latent regression models. To fit the latent regression model using the maximum likelihood estimation technique, multivariate integrals must be evaluated. In the computer program MGROUP used by the Educational Testing Service for…

  10. A Latent Class Approach to Estimating Test-Score Reliability

    ERIC Educational Resources Information Center

    van der Ark, L. Andries; van der Palm, Daniel W.; Sijtsma, Klaas

    2011-01-01

    This study presents a general framework for single-administration reliability methods, such as Cronbach's alpha, Guttman's lambda-2, and method MS. This general framework was used to derive a new approach to estimating test-score reliability by means of the unrestricted latent class model. This new approach is the latent class reliability…

  11. Gene Variants Associated with Antisocial Behaviour: A Latent Variable Approach

    ERIC Educational Resources Information Center

    Bentley, Mary Jane; Lin, Haiqun; Fernandez, Thomas V.; Lee, Maria; Yrigollen, Carolyn M.; Pakstis, Andrew J.; Katsovich, Liliya; Olds, David L.; Grigorenko, Elena L.; Leckman, James F.

    2013-01-01

    Objective: The aim of this study was to determine if a latent variable approach might be useful in identifying shared variance across genetic risk alleles that is associated with antisocial behaviour at age 15 years. Methods: Using a conventional latent variable approach, we derived an antisocial phenotype in 328 adolescents utilizing data from a…

  12. Latent Structure of Motor Abilities in Pre-School Children

    ERIC Educational Resources Information Center

    Vatroslav, Horvat

    2011-01-01

    The theoretical and practical knowledge which have so far been acquired through work with pre-school children pointed to the conclusion that the structures of the latent dimensions of the motor abilities differ greatly from such a structure, in pre-school children and adults alike. Establishing the latent structure of the motor abilities in…

  13. Latent laser-induced graphitization of diamond

    NASA Astrophysics Data System (ADS)

    Kononenko, V. V.; Gololobov, V. M.; Konov, V. I.

    2016-03-01

    Basic features and mechanism of femtosecond laser graphitization of diamond surface were studied in the two regimes of irradiation: (1) by an intensive (>10 J/cm2) single shot and (2) by a train of pulses with near-threshold intensity (~1-10 J/cm2). Special attention was paid to the so-called accumulative regime, when multipulse laser treatment results in prolonged delay of an appearance of crystal modification of the crystal. The light absorption mechanisms dominating in each regime are discussed. The experiments with fundamental (800 nm), second (400 nm) and third (266 nm) harmonics of Ti-sapphire laser (100 fs) have revealed that thermally stimulated processes play an essential role in latent diamond graphitization.

  14. Diagnosis of latent forms of labyrinthine affections

    NASA Technical Reports Server (NTRS)

    Vaslilyeva, V. P.

    1980-01-01

    Features and significance of individual vestibular symptoms for the diagnosis of latent labyrinthitis and limited forms of labyrinthine affections offering considerable difficulties are discussed. Vestibular symptoms are indistinct. In case of the negative fistular symptom the greatest significance is acquired by the study of posture nystagmus according to the results of electronystagmograms, changes of tonic reactions and statics, as well as data of experimental vestibular tests. The necessity of evaluation of all the vestibular symptoms from the point of view of their vector characteristics and in a complex of evidence obtained by otoneurological examination of the patient is emphasized. Delicate topic and differential diagnosis of vestibular disturbances is of great importance and significance in the choice of the conservative or surgical method of treatment.

  15. Energy-Storage Modules for Active Solar Heating and Cooling

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1982-01-01

    34 page report describes a melting salt hydrate that stores 12 times as much heat as rocks and other heavy materials. Energy is stored mostly as latent heat; that is, heat that can be stored and recovered without any significant change in temperature. Report also describes development, evaluation and testing of permanently sealed modules containing salt hydrate mixture.

  16. Latent Virus Reactivation in Space Shuttle Astronauts

    NASA Technical Reports Server (NTRS)

    Mehta, S. K.; Crucian, B. E.; Stowe, R. P.; Sams, C.; Castro, V. A.; Pierson, D. L.

    2011-01-01

    Latent virus reactivation was measured in 17 astronauts (16 male and 1 female) before, during, and after short-duration Space Shuttle missions. Blood, urine, and saliva samples were collected 2-4 months before launch, 10 days before launch (L-10), 2-3 hours after landing (R+0), 3 days after landing (R+14), and 120 days after landing (R+120). Epstein-Barr virus (EBV) DNA was measured in these samples by quantitative polymerase chain reaction. Varicella-zoster virus (VZV) DNA was measured in the 381 saliva samples and cytomegalovirus (CMV) DNA in the 66 urine samples collected from these subjects. Fourteen astronauts shed EBV DNA in 21% of their saliva samples before, during, and after flight, and 7 astronauts shed VZV in 7.4% of their samples during and after flight. It was interesting that shedding of both EBV and VZV increased during the flight phase relative to before or after flight. In the case of CMV, 32% of urine samples from 8 subjects contained DNA of this virus. In normal healthy control subjects, EBV shedding was found in 3% and VZV and CMV were found in less than 1% of the samples. The circadian rhythm of salivary cortisol measured before, during, and after space flight did not show any significant difference between flight phases. These data show that increased reactivation of latent herpes viruses may be associated with decreased immune system function, which has been reported in earlier studies as well as in these same subjects (data not reported here).

  17. Latent Herpes Viral Reactivation in Astronauts

    NASA Technical Reports Server (NTRS)

    Pierson, D. L.; Mehta, S. K.; Stowe, R.

    2008-01-01

    Latent viruses are ubiquitous and reactivate during stressful periods with and without symptoms. Latent herpes virus reactivation is used as a tool to predict changes in the immune status in astronauts and to evaluate associated health risks. Methods: Viral DNA was detected by real time polymerase chain reaction in saliva and urine from astronauts before, during and after short and long-duration space flights. Results and Discussion: EpsteinBarr virus (EBV), cytomegalovirus (CMV), and varicella zoster virus (VZV) reactivated, and viral DNA was shed in saliva (EBV and VZV) or urine (CMV). EBV levels in saliva during flight were 10fold higher than baseline levels. Elevations in EBV specific CD8+ T-cells, viral antibody titers, and specific cytokines were consistent with viral reactivation. Intracellular levels of cytokines were reduced in EBVspecific Tcells. CMV, rarely present in urine of healthy individuals, was shed in urine of 27% of astronauts during all phases of spaceflight. VZV, not found in saliva of asymptomatic individuals, was found in saliva of 50% of astronauts during spaceflight and 35 days after flight. VZV recovered from astronaut saliva was found to be live, infectious virus. DNA sequencing demonstrated that the VZV recovered from astronauts was from the common European strain of VZV. Elevation of stress hormones accompanied viral reactivation indicating involvement of the hypothalmic-pituitary-adrenal and sympathetic adrenal-medullary axes in the mechanism of viral reactivation in astronauts. A study of 53 shingles patients found that all shingles patients shed VZV DNA in their saliva and the VZV levels correlated with the severity of the disease. Lower VZV levels in shingles patients were similar to those observed in astronauts. We proposed a rapid, simple, and cost-effective assay to detect VZV in saliva of patients with suspected shingles. Early detection of VZV infection allows early medical intervention.

  18. Laser interrogation of latent vehicle registration number

    SciTech Connect

    Russo, R.E. |; Pelkey, G.E.; Grant, P.; Whipple, R.E.; Andresen, B.D.

    1994-09-01

    A recent investigation involved automobile registration numbers as important evidentiary specimens. In California, as in most states, small, thin metallic decals are issued to owners of vehicles each year as the registration is renewed. The decals are applied directly to the license plate of the vehicle and typically on top of the previous year`s expired decal. To afford some degree of security, the individual registration decals have been designed to tear easily; they cannot be separated from each other, but can be carefully removed intact from the metal license plate by using a razor blade. In September 1993, the City of Livermore Police Department obtained a blue 1993 California decal that had been placed over an orange 1992 decal. The two decals were being investigated as possible evidence in a case involving vehicle registration fraud. To confirm the suspicion and implicate a suspect, the department needed to known the registration number on the bottom (completely covered) 1992 decal. The authors attempted to use intense and directed light to interrogate the colored stickers. Optical illumination using a filtered white-light source partially identified the latent number. However, the most successful technique used a tunable dye laser pumped by a pulsed Nd:YAG laser. By selectively tuning the wavelength and intensity of the dye laser, backlit illumination of the decals permitted visualization of the underlying registration number through the surface of the top sticker. With optimally-tuned wavelength and intensity, 100% accuracy was obtained in identifying the sequence of latent characters. The advantage of optical techniques is their completely nondestructive nature, thus preserving the evidence for further interrogation or courtroom presentation.

  19. A competitive enzyme immunoassay for the quantitative detection of cocaine from banknotes and latent fingermarks.

    PubMed

    van der Heide, Susan; Garcia Calavia, Paula; Hardwick, Sheila; Hudson, Simon; Wolff, Kim; Russell, David A

    2015-05-01

    A sensitive and versatile competitive enzyme immunoassay (cEIA) has been developed for the quantitative detection of cocaine in complex forensic samples. Polyclonal anti-cocaine antibody was purified from serum and deposited onto microtiter plates. The concentration of the cocaine antibody adsorbed onto the plates, and the dilution of the cocaine-HRP hapten were both studied to achieve an optimised immunoassay. The method was successfully used to quantify cocaine in extracts taken from both paper currency and latent fingermarks. The limit of detection (LOD) of 0.162ngmL(-1) achieved with the assay compares favourably to that of conventional chromatography-mass spectroscopy techniques, with an appropriate sensitivity for the quantification of cocaine at the low concentrations present in some forensic samples. The cEIA was directly compared to LC-MS for the analysis of ten UK banknote samples. The results obtained from both techniques were statistically similar, suggesting that the immunoassay was unaffected by cross-reactivity with potentially interfering compounds. The cEIA was used also for the detection of cocaine in extracts from latent fingermarks. The results obtained were compared to the cocaine concentrations detected in oral fluid sampled from the same individual. Using the cEIA, we have shown, for the first time, that endogeneously excreted cocaine can be detected and quantified from a single latent fingermark. Additionally, it has been shown that the presence of cocaine, at similar concentrations, in more than one latent fingermark from the same individual can be linked with those concentrations found in oral fluid. These results show that detection of drugs in latent fingermarks could directly indicate whether an individual has consumed the drug. The specificity and feasibility of measuring low concentrations of cocaine in complex forensic samples demonstrate the effectiveness and robustness of the assay. The immunoassay presents a simple and cost

  20. Desiccant Humidity Control System Using Waste Heat of Water Source Heat Pump

    NASA Astrophysics Data System (ADS)

    Wada, Kazuki; Mashimo, Kouichi; Takahashi, Mikio; Tanaka, Kitoshi; Toya, Saburo; Tateyama, Ryotaro; Miyamoto, Kazuhiro; Yamaguchi, Masahiro

    The authors hope to develop an air-conditioning system that processes the latent heat load and the sensible heat load separately. This would enable the efficiency of the chilling unit to be improved because the temperature of the chilled water used for cooling would be higher than normal. However, if lukewarm water is used, there is insufficient cooling and dehumidification. Therefore, a dehumidifier such as a desiccant air-conditioning system is needed. Using the waste heat generated when the desiccant air-conditioning system is in operation increases efficiency. The authors are developing a prototype desiccant humidity control system that makes use of the waste heat generated by a water source heat pump. This paper describes the results of an experiment that was conducted for this prototype based on the assumption that it would be installed in an office building. The dehumidification performance achieved was sufficient to process the indoor latent heat load. The prototype was able to adjust the indoor relative humidity from 40% to 60% under conditions in which the indoor latent heat load varied. Humidification without the use of water was possible even in the absence of an indoor latent heat load when the outdoor absolute humidity was 3.5 g/kg' or more.

  1. Using Data Augmentation to Obtain Standard Errors and Conduct Hypothesis Tests in Latent Class and Latent Transition Analysis

    ERIC Educational Resources Information Center

    Lanza, Stephanie T.; Collins, Linda M.; Schafer, Joseph L.; Flaherty, Brian P.

    2005-01-01

    Latent class analysis (LCA) provides a means of identifying a mixture of subgroups in a population measured by multiple categorical indicators. Latent transition analysis (LTA) is a type of LCA that facilitates addressing research questions concerning stage-sequential change over time in longitudinal data. Both approaches have been used with…

  2. A Bayesian Model for the Estimation of Latent Interaction and Quadratic Effects When Latent Variables Are Non-Normally Distributed

    ERIC Educational Resources Information Center

    Kelava, Augustin; Nagengast, Benjamin

    2012-01-01

    Structural equation models with interaction and quadratic effects have become a standard tool for testing nonlinear hypotheses in the social sciences. Most of the current approaches assume normally distributed latent predictor variables. In this article, we present a Bayesian model for the estimation of latent nonlinear effects when the latent…

  3. Data on the interexaminer variation of minutia markup on latent fingerprints.

    PubMed

    Ulery, Bradford T; Hicklin, R Austin; Roberts, Maria Antonia; Buscaglia, JoAnn

    2016-09-01

    The data in this article supports the research paper entitled "Interexaminer variation of minutia markup on latent fingerprints" [1]. The data in this article describes the variability in minutia markup during both analysis of the latents and comparison between latents and exemplars. The data was collected in the "White Box Latent Print Examiner Study," in which each of 170 volunteer latent print examiners provided detailed markup documenting their examinations of latent-exemplar pairs of prints randomly assigned from a pool of 320 pairs. Each examiner examined 22 latent-exemplar pairs; an average of 12 examiners marked each latent. PMID:27294185

  4. Segmented heat exchanger

    DOEpatents

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  5. Isolation of Mycobacterium kumamotonense from a patient with pulmonary infection and latent tuberculosis.

    PubMed

    Kontos, Fanourios; Mavromanolakis, Dimitrios Nikitas; Zande, Marina Chari; Gitti, Zoe Georgios

    2016-01-01

    Mycobacterium kumamotonense is a novel, slow-growing non-chromogenic nontuberculous mycobacterium, which belongs to Mycobacterium terrae complex. We report, for the first time in Greece, the isolation of M. kumamotonense from an immunocompetent patient with pulmonary infection and latent tuberculosis. M. kumamotonense was identified by sequencing analysis of 16S rDNA and 65-kDa heat shock protein genes while by commercial molecular assays it was misidentified as Mycobacterium celatum. Antibiotic susceptibility testing was performed by the reference broth microdilution method. The strain was susceptible to amikacin, clarithromycin, rifampin, ciprofloxacin, moxifloxacin, rifabutin, ethambutol and linezolid. PMID:27080783

  6. On the Sensitivity of Atmospheric Model Implied Ocean Heat Transport to the Dominant Terms of the Surface Energy Balance

    SciTech Connect

    Gleckler, P J

    2004-11-03

    The oceanic meridional heat transport (T{sub o}) implied by an atmospheric General Circulation Model (GCM) can help evaluate a model's readiness for coupling with an ocean GCM. In this study we examine the T{sub o} from benchmark experiments of the Atmospheric Model Intercomparison Project, and evaluate the sensitivity of T{sub o} to the dominant terms of the surface energy balance. The implied global ocean TO in the Southern Hemisphere of many models is equatorward, contrary to most observationally-based estimates. By constructing a hybrid (model corrected by observations) T{sub o}, an earlier study demonstrated that the implied heat transport is critically sensitive to the simulated shortwave cloud radiative effects, which have been argued to be principally responsible for the Southern Hemisphere problem. Systematic evaluation of one model in a later study suggested that the implied T{sub o} could be equally as sensitive to a model's ocean surface latent heat flux. In this study we revisit the problem with more recent simulations, making use of estimates of ocean surface fluxes to construct two additional hybrid calculations. The results of the present study demonstrate that indeed the implied T{sub o} of an atmospheric model is very sensitive to problems in not only the surface net shortwave, but the latent heat flux as well. Many models underestimate the shortwave radiation reaching the surface in the low latitudes, and overestimate the latent heat flux in the same region. The additional hybrid transport calculations introduced here could become useful model diagnostic tests as estimates of implied ocean surface fluxes are improved.

  7. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2012-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  8. Experimental Investigation of Ice Phase Change Material Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Leimkuehler, Thomas O.; Stephan, Ryan A.

    2011-01-01

    Phase change materials (PCM) may be useful for spacecraft thermal control systems that involve cyclical heat loads or cyclical thermal environments. Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. This can result in a decreased turndown ratio for the radiator and a reduced system mass. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents an overview of the results of this investigation from the past three years.

  9. Food additives.

    PubMed

    Berglund, F

    1978-01-01

    The use of additives to food fulfils many purposes, as shown by the index issued by the Codex Committee on Food Additives: Acids, bases and salts; Preservatives, Antioxidants and antioxidant synergists; Anticaking agents; Colours; Emulfifiers; Thickening agents; Flour-treatment agents; Extraction solvents; Carrier solvents; Flavours (synthetic); Flavour enhancers; Non-nutritive sweeteners; Processing aids; Enzyme preparations. Many additives occur naturally in foods, but this does not exclude toxicity at higher levels. Some food additives are nutrients, or even essential nutritents, e.g. NaCl. Examples are known of food additives causing toxicity in man even when used according to regulations, e.g. cobalt in beer. In other instances, poisoning has been due to carry-over, e.g. by nitrate in cheese whey - when used for artificial feed for infants. Poisonings also occur as the result of the permitted substance being added at too high levels, by accident or carelessness, e.g. nitrite in fish. Finally, there are examples of hypersensitivity to food additives, e.g. to tartrazine and other food colours. The toxicological evaluation, based on animal feeding studies, may be complicated by impurities, e.g. orthotoluene-sulfonamide in saccharin; by transformation or disappearance of the additive in food processing in storage, e.g. bisulfite in raisins; by reaction products with food constituents, e.g. formation of ethylurethane from diethyl pyrocarbonate; by metabolic transformation products, e.g. formation in the gut of cyclohexylamine from cyclamate. Metabolic end products may differ in experimental animals and in man: guanylic acid and inosinic acid are metabolized to allantoin in the rat but to uric acid in man. The magnitude of the safety margin in man of the Acceptable Daily Intake (ADI) is not identical to the "safety factor" used when calculating the ADI. The symptoms of Chinese Restaurant Syndrome, although not hazardous, furthermore illustrate that the whole ADI

  10. A new methodology for the visualization of latent fingermarks on the sticky side of adhesive tapes using novel fluorescent dyes.

    PubMed

    Barros, Hélio L; Stefani, Valter

    2016-06-01

    Three novel fluorescent dyes were evaluated for the detection of latent fingermarks on different types and colors of adhesive tapes. Compared with the conventional reagents used to reveal latent fingermarks on these surfaces, these new fluorescent dyes have many advantages. They are highly selective to fingermarks, require only a simple procedure, do not need pre- or post-treatment, have high thermal and photochemical stability, are low in cost and use only water as a solvent. In addition, the emitted fluorescence creates a sharp contrast with the fingermark surface, meaning the fingermarks can be clearly visualized and photographed when excited with longwave ultraviolet light (365nm). PMID:27084980

  11. Impact of latent infection treatment in indigenous populations.

    PubMed

    Yuhara, Lucia Suemi; Sacchi, Flávia Patussi Correia; Croda, Julio

    2013-01-01

    The aims of the present study were to identify risk factors associated with latent tuberculosis (TB), examine the development of active disease among contacts, and assess the effectiveness of treating latent infection in indigenous Brazilians from January 2006 to December 2011. This was a retrospective study consisting of 1,371 tuberculosis contacts, 392 of whom underwent treatment for latent infection. Morbidity-from-TB data were obtained from the Information System for Disease Notification (SINAN) database, and the contacts' data were collected from the clinical records using forms employed by Special Department of Indigenous Health (SESAI) multidisciplinary teams, according to SESAI's instructions. The variables that were associated with latent infection among the contacts were age (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.02-1.04) and close contact with a smear-positive index case (OR: 2.26, 95% CI: 1.59-3.22). The variables associated with the development of active TB among the contacts were a tuberculin skin test (TST) ≥10 mm (relative risk [RR]: 1.12, 95% CI: 1.07-1.17), age (RR: 1.01, 95% CI: 1.00-1.03), and treatment of latent infection (RR: 0.03, 95% CI: 0.01-0.27). The estimated number of latent infection treatments needed to prevent one case of active TB among the contacts was 51 treatments (95% CI: 33-182). In contacts with TST ≥10 mm, 10 (95% CI: 6-19) latent infection treatments were necessary to prevent one case of active TB. Age and close contact with a smear-positive index case were associated with latent TB. Screening with TST is a high priority among individuals contacting smear-positive index cases. Age and TST are associated with the development of active TB among contacts, and treatment of latent infection is an effective measure to control TB in indigenous communities. PMID:23936264

  12. Association of autophagy-related IRGM polymorphisms with latent versus active tuberculosis infection in a Chinese population.

    PubMed

    Lu, Yanjun; Li, Qian; Peng, Jing; Zhu, Yaowu; Wang, Feng; Wang, Chunyu; Wang, Xiong

    2016-03-01

    The autophagy-related immunity-related GTPase family M protein, IRGM, plays an important role in the defense against tuberculosis (TB) infection. IRGM polymorphisms are associated with TB infection susceptibility, and recent studies demonstrate host genetic differences between active and latent TB. Here, we investigated the association between IRGM polymorphisms and TB infection type in a Chinese population. We recruited 268 and 321 patients with confirmed or latent TB, respectively, and 475 TB-free healthy controls. Three single nucleotide polymorphisms, rs10065172, rs10051924, and rs13361189 within IRGM were genotyped using TaqMan-based assays. Interferon-gamma release levels were tested by T-SPOT. rs10065172 (P = 0.024, OR 0.67 (95% CI 0.48-0.95)), rs10051924 (P = 0.01, OR 0.64 (95% CI 0.46-0.90)), and rs13361189 (P = 0.055, OR 0.72 (95% CI 0.51-1.01)) were associated with a protective role against latent TB progression. Haplotype analysis showed that TCC was protective for latent TB (P = 0.022, OR 0.74 (95% CI 0.57-0.96)) whereas TTC conferred a higher risk of active TB. Additionally, patients with the rs10065172 TT genotype had a higher response to TB specific antigens. Thus, IRGM polymorphism differences between latent and active TB suggests that genetic differences in autophagy might partly affect host TB infection status. PMID:26980495

  13. Assessing Unmet and Latent Demand for Pharmacists at the State Level

    PubMed Central

    Arora, Prachi; Mott, David A.; Chui, Michelle A.; Kreling, David H.

    2016-01-01

    Background Past reports suggest that a near balance has been reached in the supply and demand for pharmacists in the US. Although data on the level of supply of pharmacists is available, there is no continuous and systematic tracking of the level of demand (unmet and latent) for pharmacists at state level. Unmet demand, an established construct in pharmacy workforce, is important to measure the number of vacancies and assess pharmacist shortage consistently over time. Latent demand or potential demand is a novel construct and has never been measured in pharmacy workforce. With the increase in supply, it is important to measure the potential demand that could be budgeted in pharmacies in the near future. Objective The objective of this study was to measure the unmet and latent demand for pharmacists and explore the association between latent demand and workload characteristics in community and hospital pharmacies in Wisconsin in 2011-12. Methods The study used a cross-sectional, descriptive survey design. A sample of community pharmacies (n=1,064) and hospital pharmacies (n=126) licensed in Wisconsin in 2011-12 was identified. Key informants (managers/owners) of sampled pharmacies were sent a one-page cover letter explaining the purpose of the study and requesting participation and a three page survey form. The main outcome measures of the study were total number of FTE pharmacist positions vacant, presence of adequate staff size, additional number of FTE pharmacist positions needed to attain adequate staff size, prescription volume, daily census, hospital size and number of hours prescription department is open. Descriptive statistics were calculated for all the pharmacies collectively, then separately for community and hospital pharmacies. Pharmacy setting, vacancies and workload characteristics of pharmacies with and without latent demand were compared using chi-squared test of independence and/or t-test. Sample weights were calculated and used in all the

  14. Theoretical Design of Thermosyphon for Process Heat Transfer from NGNP to Hydrogen Plant

    SciTech Connect

    Piyush Sabharwall; Mike Patterson; Fred Gunnerson

    2008-09-01

    The Next Generation Nuclear Plant (NGNP) will most likely produce electricity and process heat, with both being considered for hydrogen production. To capture nuclear process heat, and transport it to a distant industrial facility requires a high temperature system of heat exchangers, pumps and/or compressors. The heat transfer system is particularly challenging not only due to the elevated temperatures (up to ~ 1300K) and industrial scale power transport (=50 MW), but also due to a potentially large separation distance between the nuclear and industrial plants (100+m) dictated by safety and licensing mandates. The work reported here is the preliminary analysis of two-phase thermosyphon heat transfer performance with alkali metals. A thermosyphon is a device for transporting heat from one point to another with quite extraordinary properties. In contrast to single-phased forced convective heat transfer via ‘pumping a fluid’, a thermosyphon (also called a wickless heat pipe) transfers heat through the vaporization / condensing process. The condensate is further returned to the hot source by gravity, i.e. without any requirement of pumps or compressors. With this mode of heat transfer, the thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. Two-phase heat transfer by a thermosyphon has the advantage of high enthalpy transport that includes the sensible heat of the liquid, the latent heat of vaporization, and vapor superheat. In contrast, single-phase forced convection transports only the sensible heat of the fluid. Additionally, vapor-phase velocities within a thermosyphon are much greater than single-phase liquid velocities within a forced convective loop. Thermosyphon performance can be limited by the sonic limit (choking) or vapor flow and/or by condensate entrainment. Proper thermosyphon requires analysis of both.

  15. Latent Herpes Viruses Reactivation in Astronauts

    NASA Technical Reports Server (NTRS)

    Mehta, Satish K.; Pierson, Duane L.

    2008-01-01

    Space flight has many adverse effects on human physiology. Changes in multiple systems, including the cardiovascular, musculoskeletal, neurovestibular, endocrine, and immune systems have occurred (12, 32, 38, 39). Alterations in drug pharmacokinetics and pharmacodynamics (12), nutritional needs (31), renal stone formation (40), and microbial flora (2) have also been reported. Evidence suggests that the magnitude of some changes may increase with time in space. A variety of changes in immunity have been reported during both short (.16 days) and long (>30 days) space missions. However, it is difficult to determine the medical significance of these immunological changes in astronauts. Astronauts are in excellent health and in superb physical condition. Illnesses in astronauts during space flight are not common, are generally mild, and rarely affect mission objectives. In an attempt to clarify this issue, we identified the latent herpes viruses as medically important indicators of the effects of space flight on immunity. This chapter demonstrates that space flight leads to asymptomatic reactivation of latent herpes viruses, and proposes that this results from marked changes in neuroendocrine function and immunity caused by the inherent stressfullness of human space flight. Astronauts experience uniquely stressful environments during space flight. Potential stressors include confinement in an unfamiliar, crowded environment, isolation, separation from family, anxiety, fear, sleep deprivation, psychosocial issues, physical exertion, noise, variable acceleration forces, increased radiation, and others. Many of these are intermittent and variable in duration and intensity, but variable gravity forces (including transitions from launch acceleration to microgravity and from microgravity to planetary gravity) and variable radiation levels are part of each mission and contribute to a stressful environment that cannot be duplicated on Earth. Radiation outside the Earth

  16. Optical properties of drug metabolites in latent fingermarks

    PubMed Central

    Shen, Yao; Ai, Qing

    2016-01-01

    Drug metabolites usually have structures of split-ring resonators (SRRs), which might lead to negative permittivity and permeability in electromagnetic field. As a result, in the UV-vis region, the latent fingermarks images of drug addicts and non drug users are inverse. The optical properties of latent fingermarks are quite different between drug addicts and non-drug users. This is a technic superiority for crime scene investigation to distinguish them. In this paper, we calculate the permittivity and permeability of drug metabolites using tight-binding model. The latent fingermarks of smokers and non-smokers are given as an example. PMID:26838730

  17. Optical properties of drug metabolites in latent fingermarks

    NASA Astrophysics Data System (ADS)

    Shen, Yao; Ai, Qing

    2016-02-01

    Drug metabolites usually have structures of split-ring resonators (SRRs), which might lead to negative permittivity and permeability in electromagnetic field. As a result, in the UV-vis region, the latent fingermarks images of drug addicts and non drug users are inverse. The optical properties of latent fingermarks are quite different between drug addicts and non-drug users. This is a technic superiority for crime scene investigation to distinguish them. In this paper, we calculate the permittivity and permeability of drug metabolites using tight-binding model. The latent fingermarks of smokers and non-smokers are given as an example.

  18. Eliminate background interference from latent fingerprints using ultraviolet multispectral imaging

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Xu, Xiaojing; Wang, Guiqiang

    2014-02-01

    Fingerprints are the most important evidence in crime scene. The technology of developing latent fingerprints is one of the hottest research areas in forensic science. Recently, multispectral imaging which has shown great capability in fingerprints development, questioned document detection and trace evidence examination is used in detecting material evidence. This paper studied how to eliminate background interference from non-porous and porous surface latent fingerprints by rotating filter wheel ultraviolet multispectral imaging. The results approved that background interference could be removed clearly from latent fingerprints by using multispectral imaging in ultraviolet bandwidth.

  19. Towards an HIV-1 cure: measuring the latent reservoir

    PubMed Central

    Bruner, Katherine M.; Hosmane, Nina N.; Siliciano, Robert F.

    2015-01-01

    The latent reservoir of HIV-1 in resting memory CD4+ T cells serves as a major barrier to curing HIV-1 infection. While many PCR- and culture-based assays have been used to measure the size of the latent reservoir, correlation between results of different assays is poor and recent studies indicate that no available assay provides an accurate measurement of reservoir size. The discrepancies between assays are a hurdle to clinical trials that aim to measure the efficacy of HIV-1 eradication strategies. Here we describe the advantages and disadvantages of various approaches to measure the latent reservoir. PMID:25747663

  20. A latent class analysis of adolescent adverse life events based on a Danish national youth probability sample.

    PubMed

    Shevlin, Mark; Elklit, Ask

    2008-01-01

    The aim of this study was to determine if there are meaningful clusters of individuals with similar experiences of adverse life events in a nationally representative sample of Danish adolescents. Latent class analysis (LCA) was used to identify such clusters or latent classes. In addition, the relationships between the latent classes and living arrangements and diagnosis of post-traumatic stress disorder (PTSD) were estimated. A four-class solution was found to be the best description of multiple adverse life events, and the classes were labelled "Low Risk", "Intermediate Risk", "Pregnancy" and "High Risk". Compared with the Low Risk class, the other classes were found to be significantly more likely to have a diagnosis PTSD and live with only one parent. This paper demonstrated how trauma research can focus on the individual as the unit of analysis rather than traumatic events. PMID:18609032