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Sample records for estimate latent heat

  1. 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

  2. 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...

  3. 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...

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  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. 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.

  18. 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)

  19. 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

  20. 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

  1. 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

  2. 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...

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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...

  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. 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. 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)…

  14. 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.

  15. 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.

  16. 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)

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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).

  3. 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…

  4. 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…

  5. 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

  6. 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.

  7. Localized Dictionaries Based Orientation Field Estimation for Latent Fingerprints.

    PubMed

    Xiao Yang; Jianjiang Feng; Jie Zhou

    2014-05-01

    Dictionary based orientation field estimation approach has shown promising performance for latent fingerprints. In this paper, we seek to exploit stronger prior knowledge of fingerprints in order to further improve the performance. Realizing that ridge orientations at different locations of fingerprints have different characteristics, we propose a localized dictionaries-based orientation field estimation algorithm, in which noisy orientation patch at a location output by a local estimation approach is replaced by real orientation patch in the local dictionary at the same location. The precondition of applying localized dictionaries is that the pose of the latent fingerprint needs to be estimated. We propose a Hough transform-based fingerprint pose estimation algorithm, in which the predictions about fingerprint pose made by all orientation patches in the latent fingerprint are accumulated. Experimental results on challenging latent fingerprint datasets show the proposed method outperforms previous ones markedly. PMID:26353229

  8. 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.

  9. 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.

  10. A Latent-Trait Based Reliability Estimate and Upper Bound.

    ERIC Educational Resources Information Center

    Nicewander, W. Alan

    1990-01-01

    An estimate and upper-bound estimate for the reliability of a test composed of binary items is derived from the multidimensional latent trait theory of R. D. Bock and M. Aitken (1981). The practical uses of such estimates are discussed. (SLD)

  11. [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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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...

  9. 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.

  10. 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…

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Standard Errors of Estimated Latent Variable Scores with Estimated Structural Parameters

    ERIC Educational Resources Information Center

    Hoshino, Takahiro; Shigemasu, Kazuo

    2008-01-01

    The authors propose a concise formula to evaluate the standard error of the estimated latent variable score when the true values of the structural parameters are not known and must be estimated. The formula can be applied to factor scores in factor analysis or ability parameters in item response theory, without bootstrap or Markov chain Monte…

  4. Marginal Maximum Likelihood Estimation of a Latent Variable Model with Interaction

    ERIC Educational Resources Information Center

    Cudeck, Robert; Harring, Jeffrey R.; du Toit, Stephen H. C.

    2009-01-01

    There has been considerable interest in nonlinear latent variable models specifying interaction between latent variables. Although it seems to be only slightly more complex than linear regression without the interaction, the model that includes a product of latent variables cannot be estimated by maximum likelihood assuming normality.…

  5. Estimation and Model Selection for Finite Mixtures of Latent Interaction Models

    ERIC Educational Resources Information Center

    Hsu, Jui-Chen

    2011-01-01

    Latent interaction models and mixture models have received considerable attention in social science research recently, but little is known about how to handle if unobserved population heterogeneity exists in the endogenous latent variables of the nonlinear structural equation models. The current study estimates a mixture of latent interaction…

  6. 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

  7. 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.

  8. 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.

  9. Estimating Non-Normal Latent Trait Distributions within Item Response Theory Using True and Estimated Item Parameters

    ERIC Educational Resources Information Center

    Sass, D. A.; Schmitt, T. A.; Walker, C. M.

    2008-01-01

    Item response theory (IRT) procedures have been used extensively to study normal latent trait distributions and have been shown to perform well; however, less is known concerning the performance of IRT with non-normal latent trait distributions. This study investigated the degree of latent trait estimation error under normal and non-normal…

  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. 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…

  13. LATENT DEMOGRAPHIC PROFILE ESTIMATION IN HARD-TO-REACH GROUPS

    PubMed Central

    McCormick, Tyler H.; Zheng, Tian

    2015-01-01

    The sampling frame in most social science surveys excludes members of certain groups, known as hard-to-reach groups. These groups, or sub-populations, may be difficult to access (the homeless, e.g.), camouflaged by stigma (individuals with HIV/AIDS), or both (commercial sex workers). Even basic demographic information about these groups is typically unknown, especially in many developing nations. We present statistical models which leverage social network structure to estimate demographic characteristics of these subpopulations using Aggregated relational data (ARD), or questions of the form “How many X’s do you know?” Unlike other network-based techniques for reaching these groups, ARD require no special sampling strategy and are easily incorporated into standard surveys. ARD also do not require respondents to reveal their own group membership. We propose a Bayesian hierarchical model for estimating the demographic characteristics of hard-to-reach groups, or latent demographic profiles, using ARD. We propose two estimation techniques. First, we propose a Markov-chain Monte Carlo algorithm for existing data or cases where the full posterior distribution is of interest. For cases when new data can be collected, we propose guidelines and, based on these guidelines, propose a simple estimate motivated by a missing data approach. Using data from McCarty et al. [Human Organization 60 (2001) 28–39], we estimate the age and gender profiles of six hard-to-reach groups, such as individuals who have HIV, women who were raped, and homeless persons. We also evaluate our simple estimates using simulation studies. PMID:26966475

  14. 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.

  15. 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).

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. The characteristic of correspondence analysis estimator to estimate latent variable model method using high-dimensional AIC

    NASA Astrophysics Data System (ADS)

    Bambang Avip Priatna, M.; Lukman, Sumiaty, Encum

    2016-02-01

    This paper aims to determine the properties of Correspondence Analysis (CA) estimator to estimate latent variable models. The method used is the High-Dimensional AIC (HAIC) method with simulation of Bernoulli distribution data. Stages are: (1) determine the matrix CA; (2) create a model of the CA estimator to estimate the latent variables by using HAIC; (3) simulated the Bernoulli distribution data with repetition 1,000,748 times. The simulation results show the CA estimator models work well.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Towards Improved Estimates of Ocean Heat Flux

    NASA Astrophysics Data System (ADS)

    Bentamy, Abderrahim; Hollman, Rainer; Kent, Elisabeth; Haines, Keith

    2014-05-01

    Recommendations and priorities for ocean heat flux research are for instance outlined in recent CLIVAR and WCRP reports, eg. Yu et al (2013). Among these is the need for improving the accuracy, the consistency, and the spatial and temporal resolution of air-sea fluxes over global as well as at region scales. To meet the main air-sea flux requirements, this study is aimed at obtaining and analyzing all the heat flux components (latent, sensible and radiative) at the ocean surface over global oceans using multiple satellite sensor observations in combination with in-situ measurements and numerical model analyses. The fluxes will be generated daily and monthly for the 20-year (1992-2011) period, between 80N and 80S and at 0.25deg resolution. Simultaneous estimates of all surface heat flux terms have not yet been calculated at such large scale and long time period. Such an effort requires a wide range of expertise and data sources that only recently are becoming available. Needed are methods for integrating many data sources to calculate energy fluxes (short-wave, long wave, sensible and latent heat) across the air-sea interface. We have access to all the relevant, recently available satellite data to perform such computations. Yu, L., K. Haines, M. Bourassa, M. Cronin, S. Gulev, S. Josey, S. Kato, A. Kumar, T. Lee, D. Roemmich: Towards achieving global closure of ocean heat and freshwater budgets: Recommendations for advancing research in air-sea fluxes through collaborative activities. INTERNATIONAL CLIVAR PROJECT OFFICE, 2013: International CLIVAR Publication Series No 189. http://www.clivar.org/sites/default/files/ICPO189_WHOI_fluxes_workshop.pdf

  15. Applying a Weighted Maximum Likelihood Latent Trait Estimator to the Generalized Partial Credit Model

    ERIC Educational Resources Information Center

    Penfield, Randall D.; Bergeron, Jennifer M.

    2005-01-01

    This article applies a weighted maximum likelihood (WML) latent trait estimator to the generalized partial credit model (GPCM). The relevant equations required to obtain the WML estimator using the Newton-Raphson algorithm are presented, and a simulation study is described that compared the properties of the WML estimator to those of the maximum…

  16. The Impact of Fallible Item Parameter Estimates on Latent Trait Recovery

    ERIC Educational Resources Information Center

    Cheng, Ying; Yuan, Ke-Hai

    2010-01-01

    In this paper we propose an upward correction to the standard error (SE) estimation of theta[subscript ML], the maximum likelihood (ML) estimate of the latent trait in item response theory (IRT). More specifically, the upward correction is provided for the SE of theta[subscript ML] when item parameter estimates obtained from an independent pretest…

  17. Hui and Walter’s latent-class model extended to estimate diagnostic test properties from surveillance data: a latent model for latent data

    PubMed Central

    Bermingham, Mairead L.; Handel, Ian G.; Glass, Elizabeth J.; Woolliams, John A.; Bronsvoort, B. Mark de Clare; McBride, Stewart H.; Skuce, Robin A.; Allen, Adrian R.; McDowell, Stanley W. J.; Bishop, Stephen C.

    2015-01-01

    Diagnostic test sensitivity and specificity are probabilistic estimates with far reaching implications for disease control, management and genetic studies. In the absence of ‘gold standard’ tests, traditional Bayesian latent class models may be used to assess diagnostic test accuracies through the comparison of two or more tests performed on the same groups of individuals. The aim of this study was to extend such models to estimate diagnostic test parameters and true cohort-specific prevalence, using disease surveillance data. The traditional Hui-Walter latent class methodology was extended to allow for features seen in such data, including (i) unrecorded data (i.e. data for a second test available only on a subset of the sampled population) and (ii) cohort-specific sensitivities and specificities. The model was applied with and without the modelling of conditional dependence between tests. The utility of the extended model was demonstrated through application to bovine tuberculosis surveillance data from Northern and the Republic of Ireland. Simulation coupled with re-sampling techniques, demonstrated that the extended model has good predictive power to estimate the diagnostic parameters and true herd-level prevalence from surveillance data. Our methodology can aid in the interpretation of disease surveillance data, and the results can potentially refine disease control strategies. PMID:26148538

  18. 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

  19. 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

  20. 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}.

  1. 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.

  2. 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.

  3. Item Response Theory with Estimation of the Latent Population Distribution Using Spline-Based Densities

    ERIC Educational Resources Information Center

    Woods, Carol M.; Thissen, David

    2006-01-01

    The purpose of this paper is to introduce a new method for fitting item response theory models with the latent population distribution estimated from the data using splines. A spline-based density estimation system provides a flexible alternative to existing procedures that use a normal distribution, or a different functional form, for the…

  4. Item Response Theory with Estimation of the Latent Density Using Davidian Curves

    ERIC Educational Resources Information Center

    Woods, Carol M.; Lin, Nan

    2009-01-01

    Davidian-curve item response theory (DC-IRT) is introduced, evaluated with simulations, and illustrated using data from the Schedule for Nonadaptive and Adaptive Personality Entitlement scale. DC-IRT is a method for fitting unidimensional IRT models with maximum marginal likelihood estimation, in which the latent density is estimated,…

  5. Accuracy of Estimating Two Parameter Logistic Latent Trait Parameters and Implications for Classroom Tests.

    ERIC Educational Resources Information Center

    Kolen, Michael J.; Whitney, Douglas R.

    The application of latent trait theory to classroom tests necessitates the use of small sample sizes for parameter estimation. Computer generated data were used to assess the accuracy of estimation of the slope and location parameters in the two parameter logistic model with fixed abilities and varying small sample sizes. The maximum likelihood…

  6. 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...

  7. 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)

  8. 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

  9. Estimation of diagnostic test accuracy without full verification: a review of latent class methods

    PubMed Central

    Collins, John; Huynh, Minh

    2014-01-01

    The performance of a diagnostic test is best evaluated against a reference test that is without error. For many diseases, this is not possible, and an imperfect reference test must be used. However, diagnostic accuracy estimates may be biased if inaccurately verified status is used as the truth. Statistical models have been developed to handle this situation by treating disease as a latent variable. In this paper, we conduct a systematized review of statistical methods using latent class models for estimating test accuracy and disease prevalence in the absence of complete verification. PMID:24910172

  10. Rasch Model Parameter Estimation in the Presence of a Nonnormal Latent Trait Using a Nonparametric Bayesian Approach

    ERIC Educational Resources Information Center

    Finch, Holmes; Edwards, Julianne M.

    2016-01-01

    Standard approaches for estimating item response theory (IRT) model parameters generally work under the assumption that the latent trait being measured by a set of items follows the normal distribution. Estimation of IRT parameters in the presence of nonnormal latent traits has been shown to generate biased person and item parameter estimates. A…

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. A Direct Latent Variable Modeling Based Method for Point and Interval Estimation of Coefficient Alpha

    ERIC Educational Resources Information Center

    Raykov, Tenko; Marcoulides, George A.

    2015-01-01

    A direct approach to point and interval estimation of Cronbach's coefficient alpha for multiple component measuring instruments is outlined. The procedure is based on a latent variable modeling application with widely circulated software. As a by-product, using sample data the method permits ascertaining whether the population discrepancy…

  16. Consequences of Ignoring Guessing when Estimating the Latent Density in Item Response Theory

    ERIC Educational Resources Information Center

    Woods, Carol M.

    2008-01-01

    In Ramsay-curve item response theory (RC-IRT), the latent variable distribution is estimated simultaneously with the item parameters. In extant Monte Carlo evaluations of RC-IRT, the item response function (IRF) used to fit the data is the same one used to generate the data. The present simulation study examines RC-IRT when the IRF is imperfectly…

  17. Accuracy of Estimates and Statistical Power for Testing Meditation in Latent Growth Curve Modeling

    ERIC Educational Resources Information Center

    Cheong, JeeWon

    2011-01-01

    The latent growth curve modeling (LGCM) approach has been increasingly utilized to investigate longitudinal mediation. However, little is known about the accuracy of the estimates and statistical power when mediation is evaluated in the LGCM framework. A simulation study was conducted to address these issues under various conditions including…

  18. 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.

  19. 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.

  20. 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.

  1. Robust Estimation of Latent Ability in Item Response Models

    ERIC Educational Resources Information Center

    Schuster, Christof; Yuan, Ke-Hai

    2011-01-01

    Because of response disturbances such as guessing, cheating, or carelessness, item response models often can only approximate the "true" individual response probabilities. As a consequence, maximum-likelihood estimates of ability will be biased. Typically, the nature and extent to which response disturbances are present is unknown, and, therefore,…

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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).

  15. 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.

  16. Mixture Item Response Theory-MIMIC Model: Simultaneous Estimation of Differential Item Functioning for Manifest Groups and Latent Classes

    ERIC Educational Resources Information Center

    Bilir, Mustafa Kuzey

    2009-01-01

    This study uses a new psychometric model (mixture item response theory-MIMIC model) that simultaneously estimates differential item functioning (DIF) across manifest groups and latent classes. Current DIF detection methods investigate DIF from only one side, either across manifest groups (e.g., gender, ethnicity, etc.), or across latent classes…

  17. Prevalence Estimation and Validation of New Instruments in Psychiatric Research: An Application of Latent Class Analysis and Sensitivity Analysis

    ERIC Educational Resources Information Center

    Pence, Brian Wells; Miller, William C.; Gaynes, Bradley N.

    2009-01-01

    Prevalence and validation studies rely on imperfect reference standard (RS) diagnostic instruments that can bias prevalence and test characteristic estimates. The authors illustrate 2 methods to account for RS misclassification. Latent class analysis (LCA) combines information from multiple imperfect measures of an unmeasurable latent condition to…

  18. 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.

  19. 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

  20. 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.

  1. Estimating heat capacity and heat content of rocks

    USGS Publications Warehouse

    Robertson, Eugene C.; Hemingway, Bruch S.

    1995-01-01

    Our measured heat-capacity values for rocks and other measurements of heat capacity or heat content of rocks found in the literature have been compared with estimated rock heat capacities calculated from the summation of heat capacities of both minerals and oxide components. The validity of calculating the heat content or heat capacity of rocks to better than about ± 3% from its mineral or chemical composition is well demonstrated by the data presented here.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Climatic indicators for estimating residential heating and cooling loads

    SciTech Connect

    Huang, Y.J.; Ritschard, R.; Bull, J.; Chang, L.

    1986-11-01

    An extensive data base of residential energy use generated with the DOE-2.1A simulation code provides an opportunity for correlating building loads predicted by an hourly simulation model to commonly used climatic parameters such as heating and cooling degree-days, and to newer parameters such as insolation-days and latent enthalpy-days. The identification of reliable climatic parameters for estimating cooling loads and the incremental loads for individual building components, such as changing ceiling and wall R-values, infiltration rates or window areas is emphasized.

  9. 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.

  10. Abstract: Inference and Interval Estimation for Indirect Effects With Latent Variable Models.

    PubMed

    Falk, Carl F; Biesanz, Jeremy C

    2011-11-30

    Models specifying indirect effects (or mediation) and structural equation modeling are both popular in the social sciences. Yet relatively little research has compared methods that test for indirect effects among latent variables and provided precise estimates of the effectiveness of different methods. This simulation study provides an extensive comparison of methods for constructing confidence intervals and for making inferences about indirect effects with latent variables. We compared the percentile (PC) bootstrap, bias-corrected (BC) bootstrap, bias-corrected accelerated (BC a ) bootstrap, likelihood-based confidence intervals (Neale & Miller, 1997), partial posterior predictive (Biesanz, Falk, and Savalei, 2010), and joint significance tests based on Wald tests or likelihood ratio tests. All models included three reflective latent variables representing the independent, dependent, and mediating variables. The design included the following fully crossed conditions: (a) sample size: 100, 200, and 500; (b) number of indicators per latent variable: 3 versus 5; (c) reliability per set of indicators: .7 versus .9; (d) and 16 different path combinations for the indirect effect (α = 0, .14, .39, or .59; and β = 0, .14, .39, or .59). Simulations were performed using a WestGrid cluster of 1680 3.06GHz Intel Xeon processors running R and OpenMx. Results based on 1,000 replications per cell and 2,000 resamples per bootstrap method indicated that the BC and BC a bootstrap methods have inflated Type I error rates. Likelihood-based confidence intervals and the PC bootstrap emerged as methods that adequately control Type I error and have good coverage rates. PMID:26736127

  11. Estimates of Tropical Diabatic Heating Profiles: Commonalities and Uncertainties

    SciTech Connect

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

    2010-02-01

    This study aims to evaluate the consistency and discrepancies in estimates of diabatic heating profiles associated with precipitation based on satellite observations and microphysics and those derived from the thermodynamics of the large-scale environment. It presents a survey of diabatic heating profile estimates from four Tropical Rainfall Measuring Mission (TRMM) products, four global reanalyses, and in situ sounding measurements from eight field campaigns at various tropical locations. Common in most of the estimates are the following: (i) bottom-heavy profiles, ubiquitous over the oceans, are associated with relatively low rain rates, while top-heavy profiles are generally associated with high rain rates; (ii) temporal variability of latent heating profiles is dominated by two modes, a deep mode with a peak in the upper troposphere and a shallow mode with a low-level peak; and (iii) the structure of the deep modes is almost the same in different estimates and different regions in the tropics. The primary uncertainty is in the amount of shallow heating over the tropical oceans, which differs substantially among the estimates.

  12. 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 .

  13. 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.

  14. A Flexible Latent Class Approach to Estimating Test-Score Reliability

    ERIC Educational Resources Information Center

    van der Palm, Daniël W.; van der Ark, L. Andries; Sijtsma, Klaas

    2014-01-01

    The latent class reliability coefficient (LCRC) is improved by using the divisive latent class model instead of the unrestricted latent class model. This results in the divisive latent class reliability coefficient (DLCRC), which unlike LCRC avoids making subjective decisions about the best solution and thus avoids judgment error. A computational…

  15. 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.

  16. 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

  17. 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

  18. Estimation of Contextual Effects through Nonlinear Multilevel Latent Variable Modeling with a Metropolis-Hastings Robbins-Monro Algorithm

    ERIC Educational Resources Information Center

    Yang, Ji Seung; Cai, Li

    2014-01-01

    The main purpose of this study is to improve estimation efficiency in obtaining maximum marginal likelihood estimates of contextual effects in the framework of nonlinear multilevel latent variable model by adopting the Metropolis-Hastings Robbins-Monro algorithm (MH-RM). Results indicate that the MH-RM algorithm can produce estimates and standard…

  19. 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.

  20. 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

  1. A Bayesian Approach to Latent Class Modeling for Estimating the Prevalence of Schizophrenia Using Administrative Databases

    PubMed Central

    Laliberté, Vincent; Joseph, Lawrence; Gold, Ian

    2015-01-01

    Estimating the incidence and the prevalence of psychotic disorders in the province of Quebec has been the object of some interest in recent years as a contribution to the epidemiological study of the causes of psychotic disorders being carried out primarily in UK and Scandinavia. A number of studies have used administrative data from the Régie de l’assurance maladie du Québec (RAMQ) that includes nearly all Quebec citizens to obtain geographical and temporal prevalence estimates for the illness. However, there has been no investigation of the validity of RAMQ diagnoses for psychotic disorders, and without a measure of the sensitivity and the specificity of these diagnoses, it is impossible to be confident in the accuracy of the estimates obtained. This paper proposes the use of latent class analysis to ascertain the validity of a diagnosis of schizophrenia using RAMQ data. PMID:26217241

  2. Accuracy of Estimates and Statistical Power for Testing Meditation in Latent Growth Curve Modeling

    PubMed Central

    Cheong, JeeWon

    2016-01-01

    The latent growth curve modeling (LGCM) approach has been increasingly utilized to investigate longitudinal mediation. However, little is known about the accuracy of the estimates and statistical power when mediation is evaluated in the LGCM framework. A simulation study was conducted to address these issues under various conditions including sample size, effect size of mediated effect, number of measurement occasions, and R2 of measured variables. In general, the results showed that relatively large samples were needed to accurately estimate the mediated effects and to have adequate statistical power, when testing mediation in the LGCM framework. Guidelines for designing studies to examine longitudinal mediation and ways to improve the accuracy of the estimates and statistical power were discussed.

  3. Satellite estimates of ocean-air heat fluxes during cold air outbreaks

    NASA Technical Reports Server (NTRS)

    Chou, S.-H.; Atlas, D.

    1982-01-01

    A method for estimating the heat and moisture fluxes of coastal waters using the cloud free path, the sea surface temperature, and the saturation water vapor mixing ratio is presented. Generalized nomograms for the surface sensible and latent heat fluxes are developed using the Stage and Businger (1981) mixed-layer model. The fluxes are found to be slightly dependent on wind speed. The results are found to be applicable to any path within the cloud-free region, with heat fluxes obtainable by multiplication of the mean heating by the mean wind speed in the boundary layer. Higher stability causes lowered heating. It is shown that the latent heat flux is linear. Applications of the method to lake-effect snowstorms and for verification of boundary-layer models are indicated.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. The Sensitivity of Parameter Estimates to the Latent Ability Distribution. Research Report. ETS RR-11-40

    ERIC Educational Resources Information Center

    Xu, Xueli; Jia, Yue

    2011-01-01

    Estimation of item response model parameters and ability distribution parameters has been, and will remain, an important topic in the educational testing field. Much research has been dedicated to addressing this task. Some studies have focused on item parameter estimation when the latent ability was assumed to follow a normal distribution,…

  12. Anthropogenic heat flux estimation from space: first results

    NASA Astrophysics Data System (ADS)

    Chrysoulakis, Nektarios; Heldens, Wieke; Gastellu-Etchegorry, Jean-Philippe; Grimmond, Sue; Feigenwinter, Christian; Lindberg, Fredrik; Del Frate, Fabio; Klostermann, Judith; Mitraka, Zina; Esch, Thomas; Albitar, Ahmad; Gabey, Andrew; Parlow, Eberhard; Olofson, Frans

    2016-04-01

    While Earth Observation (EO) has made significant advances in the study of urban areas, there are several unanswered science and policy questions to which it could contribute. To this aim the recently launched Horizon 2020 project URBANFLUXES (URBan ANthrpogenic heat FLUX from Earth observation Satellites) investigates the potential of EO to retrieve anthropogenic heat flux, as a key component in the urban energy budget. The anthropogenic heat flux is the heat flux resulting from vehicular emissions, space heating and cooling of buildings, industrial processing and the metabolic heat release by people. Optical, thermal and SAR data from existing satellite sensors are used to improve the accuracy of the radiation balance spatial distribution calculation, using also in-situ reflectance measurements of urban materials are for calibration. EO-based methods are developed for estimating turbulent sensible and latent heat fluxes, as well as urban heat storage flux and anthropogenic heat flux spatial patterns at city scale and local scale by employing an energy budget closure approach. Independent methods and models are engaged to evaluate the derived products and statistical analyses provide uncertainty measures as well. Ultimate goal of the URBANFLUXES is to develop a highly automated method for estimating urban energy budget components to use with Copernicus Sentinel data, enabling its integration into applications and operational services. Thus, URBANFLUXES prepares the ground for further innovative exploitation of European space data in scientific activities (i.e. Earth system modelling and climate change studies in cities) and future and emerging applications (i.e. sustainable urban planning) by exploiting the improved data quality, coverage and revisit times of the Copernicus data. The URBANFLUXES products will therefore have the potential to support both sustainable planning strategies to improve the quality of life in cities, as well as Earth system models to

  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. 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.

  16. Spectral estimates of net radiation and soil heat flux

    USGS Publications Warehouse

    Daughtry, C.S.T.; Kustas, W.P.; Moran, M.S.; Pinter, P. J., Jr.; Jackson, R. D.; Brown, P.W.; Nichols, W.D.; Gay, L.W.

    1990-01-01

    Conventional methods of measuring surface energy balance are point measurements and represent only a small area. Remote sensing offers a potential means of measuring outgoing fluxes over large areas at the spatial resolution of the sensor. The objective of this study was to estimate net radiation (Rn) and soil heat flux (G) using remotely sensed multispectral data acquired from an aircraft over large agricultural fields. Ground-based instruments measured Rn and G at nine locations along the flight lines. Incoming fluxes were also measured by ground-based instruments. Outgoing fluxes were estimated using remotely sensed data. Remote Rn, estimated as the algebraic sum of incoming and outgoing fluxes, slightly underestimated Rn measured by the ground-based net radiometers. The mean absolute errors for remote Rn minus measured Rn were less than 7%. Remote G, estimated as a function of a spectral vegetation index and remote Rn, slightly overestimated measured G; however, the mean absolute error for remote G was 13%. Some of the differences between measured and remote values of Rn and G are associated with differences in instrument designs and measurement techniques. The root mean square error for available energy (Rn - G) was 12%. Thus, methods using both ground-based and remotely sensed data can provide reliable estimates of the available energy which can be partitioned into sensible and latent heat under nonadvective conditions. ?? 1990.

  17. 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.

  18. 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.

  19. 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.

  20. Identifying victims of workplace bullying by integrating traditional estimation approaches into a latent class cluster model.

    PubMed

    Leon-Perez, Jose M; Notelaers, Guy; Arenas, Alicia; Munduate, Lourdes; Medina, Francisco J

    2014-05-01

    Research findings underline the negative effects of exposure to bullying behaviors and document the detrimental health effects of being a victim of workplace bullying. While no one disputes its negative consequences, debate continues about the magnitude of this phenomenon since very different prevalence rates of workplace bullying have been reported. Methodological aspects may explain these findings. Our contribution to this debate integrates behavioral and self-labeling estimation methods of workplace bullying into a measurement model that constitutes a bullying typology. Results in the present sample (n = 1,619) revealed that six different groups can be distinguished according to the nature and intensity of reported bullying behaviors. These clusters portray different paths for the workplace bullying process, where negative work-related and person-degrading behaviors are strongly intertwined. The analysis of the external validity showed that integrating previous estimation methods into a single measurement latent class model provides a reliable estimation method of workplace bullying, which may overcome previous flaws. PMID:24257593

  1. 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.

  2. 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

  3. Estimating Correlates of Growth between Mathematics and Science Achievement via a Multivariate Multilevel Design with Latent Variables

    ERIC Educational Resources Information Center

    Ma, Lingling; Ma, Xin

    2005-01-01

    The purpose of the present study was to improve a multivariate multilevel model in the research literature which estimates the consistency in the rates of growth between mathematics and science achievement among students and schools. We introduced a new multivariate multilevel model via a latent variable approach. Data from the Longitudinal Study…

  4. Estimating the Latent Number of Types in Growing Corpora with Reduced Cost-Accuracy Trade-Off

    ERIC Educational Resources Information Center

    Hidaka, Shohei

    2016-01-01

    The number of unique words in children's speech is one of most basic statistics indicating their language development. We may, however, face difficulties when trying to accurately evaluate the number of unique words in a child's growing corpus over time with a limited sample size. This study proposes a novel technique to estimate the latent number…

  5. 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

  6. 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.

  7. 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.

  8. Visualizing Confidence Bands for Semiparametrically Estimated Nonlinear Relations among Latent Variables

    ERIC Educational Resources Information Center

    Pek, Jolynn; Chalmers, R. Philip; Kok, Bethany E.; Losardo, Diane

    2015-01-01

    Structural equation mixture models (SEMMs), when applied as a semiparametric model (SPM), can adequately recover potentially nonlinear latent relationships without their specification. This SPM is useful for exploratory analysis when the form of the latent regression is unknown. The purpose of this article is to help users familiar with structural…

  9. Estimating Latent Variable Interactions with Nonnormal Observed Data: A Comparison of Four Approaches

    ERIC Educational Resources Information Center

    Cham, Heining; West, Stephen G.; Ma, Yue; Aiken, Leona S.

    2012-01-01

    A Monte Carlo simulation was conducted to investigate the robustness of 4 latent variable interaction modeling approaches (Constrained Product Indicator [CPI], Generalized Appended Product Indicator [GAPI], Unconstrained Product Indicator [UPI], and Latent Moderated Structural Equations [LMS]) under high degrees of nonnormality of the observed…

  10. Advanced Nonlinear Latent Variable Modeling: Distribution Analytic LMS and QML Estimators of Interaction and Quadratic Effects

    ERIC Educational Resources Information Center

    Kelava, Augustin; Werner, Christina S.; Schermelleh-Engel, Karin; Moosbrugger, Helfried; Zapf, Dieter; Ma, Yue; Cham, Heining; Aiken, Leona S.; West, Stephen G.

    2011-01-01

    Interaction and quadratic effects in latent variable models have to date only rarely been tested in practice. Traditional product indicator approaches need to create product indicators (e.g., x[superscript 2] [subscript 1], x[subscript 1]x[subscript 4]) to serve as indicators of each nonlinear latent construct. These approaches require the use of…

  11. Planned Missing Designs to Optimize the Efficiency of Latent Growth Parameter Estimates

    ERIC Educational Resources Information Center

    Rhemtulla, Mijke; Jia, Fan; Wu, Wei; Little, Todd D.

    2014-01-01

    We examine the performance of planned missing (PM) designs for correlated latent growth curve models. Using simulated data from a model where latent growth curves are fitted to two constructs over five time points, we apply three kinds of planned missingness. The first is item-level planned missingness using a three-form design at each wave such…

  12. Estimation of the latent mediated effect with ordinal data using the limited-information and Bayesian full-information approaches.

    PubMed

    Chen, Jinsong; Zhang, Dake; Choi, Jaehwa

    2015-12-01

    It is common to encounter latent variables with ordinal data in social or behavioral research. Although a mediated effect of latent variables (latent mediated effect, or LME) with ordinal data may appear to be a straightforward combination of LME with continuous data and latent variables with ordinal data, the methodological challenges to combine the two are not trivial. This research covers model structures as complex as LME and formulates both point and interval estimates of LME for ordinal data using the Bayesian full-information approach. We also combine weighted least squares (WLS) estimation with the bias-corrected bootstrapping (BCB; Efron Journal of the American Statistical Association, 82, 171-185, 1987) method or the traditional delta method as the limited-information approach. We evaluated the viability of these different approaches across various conditions through simulation studies, and provide an empirical example to illustrate the approaches. We found that the Bayesian approach with reasonably informative priors is preferred when both point and interval estimates are of interest and the sample size is 200 or above. PMID:25361865

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Estimating Generalizability to a Latent Variable Common to All of a Scale's Indicators: A Comparison of Estimators for Omega[subscript h

    ERIC Educational Resources Information Center

    Zinbarg, Richard E.; Yovel, Iftah; Revelle, William; McDonald, Roderick P.

    2006-01-01

    The extent to which a scale score generalizes to a latent variable common to all of the scale's indicators is indexed by the scale's general factor saturation. Seven techniques for estimating this parameter--omega[hierarchical] (omega[subscript h])--are compared in a series of simulated data sets. Primary comparisons were based on 160 artificial…

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Estimation of spatially distributed latent energy flux over complex terrain using a scanning water-vapor Raman lidar

    SciTech Connect

    Cooper, D.I.; Eichinger, W.; Archuleta, J.; Cottingame, W.; Osborne, M.; Tellier, L.

    1995-09-01

    Evapotranspiration is one of the critical variables in both water and energy balance models of the hydrological system. The hydrologic system is driven by the soil-plant-atmosphere continuum, and as such is a spatially distributed process. Traditional techniques rely on point sensors to collect information that is then averaged over a region. The assumptions involved in spatially average point data is of limited value (1) because of limited sensors in the arrays, (2) the inability to extend and interpret the Measured scalars and estimated fluxes at a point over large areas in complex terrain, and (3) the limited understanding of the relationship between point measurements of spatial processes. Remote sensing technology offers the ability to collect detailed spatially distributed data. However, the Los Alamos National Laboratory`s volume-imaging, scanning water-vapor Raman lidar has been shown to be able to estimate the latent energy flux at a point. The extension of this capability to larger scales over complex terrain represents a step forward. This abstract Outlines the techniques used to estimate the spatially resolved latent energy flux. The following sections describe the site, model, data acquired, and lidar estimated latent energy ``map``.

  7. Estimating ocean-air heat fluxes during cold air outbreaks by satellite

    NASA Technical Reports Server (NTRS)

    Chou, S. H.; Atlas, D.

    1981-01-01

    Nomograms of mean column heating due to surface sensible and latent heat fluxes were developed. Mean sensible heating of the cloud free region is related to the cloud free path (CFP, the distance from the shore to the first cloud formation) and the difference between land air and sea surface temperatures, theta sub 1 and theta sub 0, respectively. Mean latent heating is related to the CFP and the difference between land air and sea surface humidities q sub 1 and q sub 0 respectively. Results are also applicable to any path within the cloud free region. Corresponding heat fluxes may be obtained by multiplying the mean heating by the mean wind speed in the boundary layer. The sensible heating estimated by the present method is found to be in good agreement with that computed from the bulk transfer formula. The sensitivity of the solutions to the variations in the initial coastal soundings and large scale subsidence is also investigated. The results are not sensitive to divergence but are affected by the initial lapse rate of potential temperature; the greater the stability, the smaller the heating, other things being equal. Unless one knows the lapse rate at the shore, this requires another independent measurement. For this purpose the downwind slope of the square of the boundary layer height is used, the mean value of which is also directly proportional to the mean sensible heating. The height of the boundary layer should be measurable by future spaceborn lidar systems.

  8. 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.…

  9. 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

    averages identify biases in air specific humidity exceeding 1 g/kg within the subtropical northern hemisphere. To the contrary, misrepresentations of wind speeds among HOAPS exhibit less priority. Southern hemispheric extratropics represent an exception, in as much as positive LHF biases are associated with a concurrent overestimation of HOAPS wind speeds. Away from coastal waters, where especially wind speed is fraught with uncertainty, it is presumed that HOAPS surface air temperature estimates largely contribute to this deficiency, as relative humidities and air-sea temperature differences are prescribed to be 80% and 1K, respectively, which may represent an area-wide tropical bias source. Comparing ERA-Interim reanalysis data with OCEANET it was found that ERA-Interim wind speeds are generally too low, while specific humidities tend to be too low in the tropics. This results in an underestimation of latent heat fluxes at high latitudes and an overestimation at low latitudes. Reference Bumke, K., M. Schlundt, J. Kalisch, A. Macke, and H. Kleta, 2013: Measured and Parameterized Energy Fluxes for Atlantic Transects of R/V Polarstern. J. Phys. Oceanogr. doi:10.1175/JPO-D-13-0152.1, in press.

  10. Latent Class Models for Diary Method Data: Parameter Estimation by Local Computations

    ERIC Educational Resources Information Center

    Rijmen, Frank; Vansteelandt, Kristof; De Boeck, Paul

    2008-01-01

    The increasing use of diary methods calls for the development of appropriate statistical methods. For the resulting panel data, latent Markov models can be used to model both individual differences and temporal dynamics. The computational burden associated with these models can be overcome by exploiting the conditional independence relations…

  11. Comparison of Approaches in Estimating Interaction and Quadratic Effects of Latent Variables

    ERIC Educational Resources Information Center

    Lee, Sik-Yum; Song, Xin Yuan; Poon, Wai-Yin

    2004-01-01

    Various approaches using the maximum likelihood (ML) option of the LISREL program and products of indicators have been proposed to analyze structural equation models with non-linear latent effects on the basis of Kenny and Judd's formulation. Recently, some methods based on the Bayesian approach and the exact ML approaches have been developed.…

  12. Multivariate Effect Size Estimation: Confidence Interval Construction via Latent Variable Modeling

    ERIC Educational Resources Information Center

    Raykov, Tenko; Marcoulides, George A.

    2010-01-01

    A latent variable modeling method is outlined for constructing a confidence interval (CI) of a popular multivariate effect size measure. The procedure uses the conventional multivariate analysis of variance (MANOVA) setup and is applicable with large samples. The approach provides a population range of plausible values for the proportion of…

  13. Estimating latent time of maturation and survival costs of reproduction in continuous time from capture-recapture data

    USGS Publications Warehouse

    Ergon, T.; Yoccoz, N.G.; Nichols, J.D.

    2009-01-01

    In many species, age or time of maturation and survival costs of reproduction may vary substantially within and among populations. We present a capture-mark-recapture model to estimate the latent individual trait distribution of time of maturation (or other irreversible transitions) as well as survival differences associated with the two states (representing costs of reproduction). Maturation can take place at any point in continuous time, and mortality hazard rates for each reproductive state may vary according to continuous functions over time. Although we explicitly model individual heterogeneity in age/time of maturation, we make the simplifying assumption that death hazard rates do not vary among individuals within groups of animals. However, the estimates of the maturation distribution are fairly robust against individual heterogeneity in survival as long as there is no individual level correlation between mortality hazards and latent time of maturation. We apply the model to biweekly capture?recapture data of overwintering field voles (Microtus agrestis) in cyclically fluctuating populations to estimate time of maturation and survival costs of reproduction. Results show that onset of seasonal reproduction is particularly late and survival costs of reproduction are particularly large in declining populations.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Latent class regression models for simultaneously estimating test accuracy, true prevalence and risk factors for Brucella abortus.

    PubMed

    Campe, A; Abernethy, D; Menzies, F; Greiner, M

    2016-07-01

    In 2003/2004 a field trial was conducted in Northern Ireland to assess the diagnostic accuracy of six serological tests for bovine brucellosis caused by Brucella abortus. Whereas between-test comparisons have been used to calculate test performances so far, the present study used a latent class approach to estimate diagnostic test accuracy parameters in the absence of a gold standard for these six tests simultaneously and to estimate the true prevalence, while accounting for clustering in the study population and risk factors for true prevalence. Results obtained in this study with regard to prevalence, sensitivity and specificity were largely in accordance with previous findings. Screening tests (SAT and EDTA) appeared to be the most sensitive; however, at low prevalences the EDTA and CFT showed the highest positive predictive values of all investigated tests. The specificities and negative predictive values of all diagnostic tests were found to be very high. Differences of prevalence between three groups of the study population with different risk of exposure could be attributed to the mode of sampling indicating that a more risk-based sampling will result in a higher prevalence than a cross-sectional sampling mode. Age, dairy status and history of abortion were shown to influence the prediction of the latent true infection status. PMID:27245291

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Estimation of Contextual Effects through Nonlinear Multilevel Latent Variable Modeling with a Metropolis-Hastings Robbins-Monro Algorithm. CRESST Report 833

    ERIC Educational Resources Information Center

    Yang, Ji Seung; Cai, Li

    2013-01-01

    The main purpose of this study is to improve estimation efficiency in obtaining full-information maximum likelihood (FIML) estimates of contextual effects in the framework of a nonlinear multilevel latent variable model by adopting the Metropolis-Hastings Robbins-Monro algorithm (MH-RM; Cai, 2008, 2010a, 2010b). Results indicate that the MH-RM…

  6. Effects of Initial Values and Convergence Criterion in the Two-Parameter Logistic Model When Estimating the Latent Distribution in BILOG-MG 3

    PubMed Central

    Nader, Ingo W.; Tran, Ulrich S.; Voracek, Martin

    2015-01-01

    Parameters of the two-parameter logistic model are generally estimated via the expectation-maximization algorithm, which improves initial values for all parameters iteratively until convergence is reached. Effects of initial values are rarely discussed in item response theory (IRT), but initial values were recently found to affect item parameters when estimating the latent distribution with full non-parametric maximum likelihood. However, this method is rarely used in practice. Hence, the present study investigated effects of initial values on item parameter bias and on recovery of item characteristic curves in BILOG-MG 3, a widely used IRT software package. Results showed notable effects of initial values on item parameters. For tighter convergence criteria, effects of initial values decreased, but item parameter bias increased, and the recovery of the latent distribution worsened. For practical application, it is advised to use the BILOG default convergence criterion with appropriate initial values when estimating the latent distribution from data. PMID:26452264

  7. 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.

  8. Evaluation of estimation, prediction and inference for autocorrelated latent variable modeling of binary data-a simulation study.

    PubMed

    Hutmacher, Matthew M

    2016-06-01

    Longitudinal models of binary or ordered categorical data are often evaluated for adequacy by the ability of these to characterize the transition frequency and type between response states. Drug development decisions are often concerned with accurate prediction and inference of the probability of response by time and dose. A question arises on whether the transition probabilities need to be characterized adequately to ensure accurate response prediction probabilities unconditional on the previous response state. To address this, a simulation study was conducted to assess bias in estimation, prediction and inferences of autocorrelated latent variable models (ALVMs) when the transition probabilities are misspecified due to ill-posed random effects structures, inadequate likelihood approximation or omission of the autocorrelation component. The results may be surprising in that these suggest that characterizing autocorrelation in ALVMs is not as important as specifying a suitably rich random effects structure. PMID:27007275

  9. 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.

  10. 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.

  11. 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…

  12. Direct retrieval of ocean surface evaporation and latent heat flux from the spacebased observations

    NASA Technical Reports Server (NTRS)

    Liu, W. T.; Tang, W.

    2000-01-01

    The Tropical Rain Measuring Mission (TRMM) provides the opportunity to improve the spacebased estimation of evaporation. An algorithm for retrieving evaporation directly from the radiances observed by the TRMM Microwave Imager and its validation results are described.

  13. A spatio-temporal latent atlas for semi-supervised learning of fetal brain segmentations and morphological age estimation.

    PubMed

    Dittrich, Eva; Riklin Raviv, Tammy; Kasprian, Gregor; Donner, René; Brugger, Peter C; Prayer, Daniela; Langs, Georg

    2014-01-01

    Prenatal neuroimaging requires reference models that reflect the normal spectrum of fetal brain development, and summarize observations from a representative sample of individuals. Collecting a sufficiently large data set of manually annotated data to construct a comprehensive in vivo atlas of rapidly developing structures is challenging but necessary for large population studies and clinical application. We propose a method for the semi-supervised learning of a spatio-temporal latent atlas of fetal brain development, and corresponding segmentations of emerging cerebral structures, such as the ventricles or cortex. The atlas is based on the annotation of a few examples, and a large number of imaging data without annotation. It models the morphological and developmental variability across the population. Furthermore, it serves as basis for the estimation of a structures' morphological age, and its deviation from the nominal gestational age during the assessment of pathologies. Experimental results covering the gestational period of 20-30 gestational weeks demonstrate segmentation accuracy achievable with minimal annotation, and precision of morphological age estimation. Age estimation results on fetuses suffering from lissencephaly demonstrate that they detect significant differences in the age offset compared to a control group. PMID:24080527

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. An Algorithm to Estimate the Heating Budget from Vertical Hydrometeor Profiles.

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Simpson, Joanne; Lang, Stephen; McCumber, Michael; Adler, Robert; Penc, Richard

    1990-12-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometer profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a non-hydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algorithm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  19. An algorithm to estimate the heating budget from vertical hydrometeor profiles

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Simpson, Joanne; Mccumber, Michael; Adler, Robert; Lang, Stephen

    1990-01-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometeor profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a nonhydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algoritm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  20. A Three Component Model to Estimate Sensible Heat Flux Over Sparse Shrubs in Nevada

    USGS Publications Warehouse

    Chehbouni, A.; Nichols, W.D.; Njoku, E.G.; Qi, J.; Kerr, Y.H.; Cabot, F.

    1997-01-01

    It is now recognized that accurate partitioning of available energy into sensible and latent heat flux is crucial to understanding surface-atmosphere interactions. This issue is more complicated in arid and semi-arid regions where the relative contribution to surface fluxes from the soil and vegetation may vary significantly throughout the day and throughout the season. The objective of this paper is to present a three-component model to estimate sensible heat flux over heterogeneous surfaces. The surface was represented with two adjacent compartments. The first compartment is made up of two components, shrubs and shaded soil; the second compartment consists of bare, unshaded soil. Data collected at two different sites in Nevada during the summers of 1991 and 1992 were used to evaluate model performance. The results show that the present model is sufficiently general to yield satisfactory results for both sites.

  1. Parallel Analysis Criteria: Revised Equations for Estimating the Latent Roots of Random Data Correlation Matrices.

    ERIC Educational Resources Information Center

    Lautenschlager, Gary J.; And Others

    1989-01-01

    A method for estimating the first eigenvalue of random data correlation matrices is reported, and its precision is demonstrated via comparison to the method of S. J. Allen and R. Hubbard (1986). Data generated in Monte Carlo simulations with 10 sample sizes reaching up to 1,000 were used. (SLD)

  2. The Biasing Effects of Unmodeled ARMA Time Series Processes on Latent Growth Curve Model Estimates

    ERIC Educational Resources Information Center

    Sivo, Stephen; Fan, Xitao; Witta, Lea

    2005-01-01

    The purpose of this study was to evaluate the robustness of estimated growth curve models when there is stationary autocorrelation among manifest variable errors. The results suggest that when, in practice, growth curve models are fitted to longitudinal data, alternative rival hypotheses to consider would include growth models that also specify…

  3. On the Estimation of Hierarchical Latent Regression Models for Large-Scale Assessments

    ERIC Educational Resources Information Center

    Li, Deping; Oranje, Andreas; Jiang, Yanlin

    2009-01-01

    To find population proficiency distributions, a two-level hierarchical linear model may be applied to large-scale survey assessments such as the National Assessment of Educational Progress (NAEP). The model and parameter estimation are developed and a simulation was carried out to evaluate parameter recovery. Subsequently, both a hierarchical and…

  4. 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

  5. Spatial and temporal variations of CO2, sensible and latent heat fluxes over the FIFE site

    NASA Technical Reports Server (NTRS)

    Desjardins, R. L.; Schuepp, P. H.; Macpherson, J. I.

    1990-01-01

    The temporal and spatial variations of mass and energy exchanges are characterized by data taken from grid flights at a constant pressure altitude. Data from two separate studies are presented to demonstrate that the correlation coefficients increase with improved estimates of the origin of mass and energy exchange. Measurements taken from aircraft can effectively describe relationships between surface processes and vegetation characteristics on a regional scale.

  6. Estimation of Contextual Effects through Nonlinear Multilevel Latent Variable Modeling with a Metropolis-Hastings Robbins-Monro Algorithm

    ERIC Educational Resources Information Center

    Yang, Ji Seung

    2012-01-01

    Nonlinear multilevel latent variable modeling has been suggested as an alternative to traditional hierarchical linear modeling to more properly handle measurement error and sampling error issues in contextual effects modeling. However, a nonlinear multilevel latent variable model requires significant computational effort because the estimation…

  7. Comparison of heat flux estimations from two turbulent exchange models based on thermal UAV data.

    NASA Astrophysics Data System (ADS)

    Hoffmann, Helene; Nieto, Hector; Jensen, Rasmus; Friborg, Thomas

    2015-04-01

    Advantages of UAV (Unmanned Aerial Vehicle) data-collection, compared to more traditional data-collections are numerous and already well-discussed (Berni et al., 2009; Laliberte et al., 2011; Turner et al., 2012). However studies investigating the quality and applications of UAV-data are crucial if advantages are to be beneficial for scientific purposes. In this study, thermal data collected over an agricultural site in Denmark have been obtained using a fixed-wing UAV and investigated for the estimation of heat fluxes. Estimation of heat fluxes requires high precision data and careful data processing. Latent, sensible and soil heat fluxes are estimates through two models of the two source energy modelling scheme driven by remotely sensed observations of land surface temperature; the original TSEB (Norman et al., 1995) and the DTD (Norman et al., 2000) which builds on the TSEB. The DTD model accounts for errors arising when deriving radiometric temperatures and can to some extent compensate for the fact that thermal cameras rarely are accurate. The DTD model requires an additional set of remotely sensed data during morning hours of the day at which heat fluxes are to be determined. This makes the DTD model ideal to use when combined with UAV data, because acquisition of data is not limited by fixed time by-passing tracks like satellite images (Guzinski et al., 2013). Based on these data, heat fluxes are computed from the two models and compared with fluxes from an eddy covariance station situated within the same designated agricultural site. This over-all procedure potentially enables an assessment of both the collected thermal UAV-data and of the two turbulent exchange models. Results reveal that both TSEB and DTD models compute heat fluxes from thermal UAV data that is within a very reasonable range and also that estimates from the DTD model is in best agreement with the eddy covariance system.

  8. Recent improvements in ocean heat content estimation

    NASA Astrophysics Data System (ADS)

    Abraham, J. P.

    2015-12-01

    Increase of ocean heat content is an outcome of a persistent and ongoing energy imbalance to the Earth's climate system. This imbalance, largely caused by human emissions of greenhouse gases, has engendered a multi-decade increase in stored thermal energy within the Earth system, manifest principally as an increase in ocean heat content. Consequently, in order to quantify the rate of global warming, it is necessary to measure the rate of increase of ocean heat content. The historical record of ocean heat content is extracted from a history of various devices and spatial/temporal coverage across the globe. One of the most important historical devices is the eXpendable BathyThermograph (XBT) which has been used for decades to measure ocean temperatures to depths of 700m and deeper. Here, recent progress in improving the XBT record of upper ocean heat content is described including corrections to systematic biases, filling in spatial gaps where data does not exist, and the selection of a proper climatology. In addition, comparisons of the revised historical record and CMIP5 climate models are made. It is seen that there is very good agreement between the models and measurements, with the models slightly under-predicting the increase of ocean heat content in the upper water layers over the past 45 years.

  9. Estimating land surface heat flux using radiometric surface temperature without the need for an extra resistance

    NASA Astrophysics Data System (ADS)

    Su, H.; Yang, Y.; Liu, S.

    2015-12-01

    Remotely-sensed land surface temperature (LST) is a key variable in energy balance and is widely used for estimating regional heat flux. However, the inequality between LST and aerodynamic surface temperature (Taero) poses a great challenge for regional heat flux estimation in one -source energy balance models. In this study, a one-source model for land (OSML) was proposed to estimate regional surface heat flux without a need for an empirical extra resistance. The proposed OSML employs both a conceptual VFC/LST trapezoid model and the electrical analogue formula of sensible heat flux (H) to estimate the radiometric-convective resistance (rae) by using a quartic equation. To evaluate the performance of OSML, the model was applied to the Soil Moisture-Atmosphere Coupling Experiment (SMACEX), using a remotely-sensed data set at a regional scale. Validated against tower observations, the root mean square deviation (RMSD) of H and latent heat flux (LE) from OSML was 47 W/m2 and 51 W/m2, which is comparable to other published studies. OSML and SEBS (Surface Energy Balance System) compared under the same available energy indicated that LE estimated by OSML is comparable to that derived from the SEBS model. In conducting further inter-comparisons of rae, the aerodynamic resistance derived from SEBS (ra_SEBS), and aerodynamic resistance (ra) derived from Brutsaert et al. (2005) in corn and soybean fields, we found that rae and ra_SEBS are comparable. Most importantly, our study indicates that the OSML method is applicable without having to acquire wind speed or to specify aerodynamic surface characteristics and that it is applicable to heterogeneous areas.

  10. Bayesian Estimation of Latently-grouped Parameters in Undirected Graphical Models

    PubMed Central

    Liu, Jie; Page, David

    2014-01-01

    In large-scale applications of undirected graphical models, such as social networks and biological networks, similar patterns occur frequently and give rise to similar parameters. In this situation, it is beneficial to group the parameters for more efficient learning. We show that even when the grouping is unknown, we can infer these parameter groups during learning via a Bayesian approach. We impose a Dirichlet process prior on the parameters. Posterior inference usually involves calculating intractable terms, and we propose two approximation algorithms, namely a Metropolis-Hastings algorithm with auxiliary variables and a Gibbs sampling algorithm with “stripped” Beta approximation (Gibbs_SBA). Simulations show that both algorithms outperform conventional maximum likelihood estimation (MLE). Gibbs_SBA’s performance is close to Gibbs sampling with exact likelihood calculation. Models learned with Gibbs_SBA also generalize better than the models learned by MLE on real-world Senate voting data. PMID:25404848

  11. 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

  12. 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.

  13. Dynamics of heat storage in evapotranspiration estimate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the widely discussed reasons for a lack of surface energy balance closure when using eddy covariance is neglect of storage term elements. Storage as related to the surface energy balance refers to all heat stored below the observation level of eddies. It represents the sum of several componen...

  14. 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

  15. 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.

  16. On the study of energy imbalance and its influence on estimation of heat fluxes using energy balance based models

    NASA Astrophysics Data System (ADS)

    Jia, L.; Zhang, T.; Su, Z.

    2003-04-01

    The modeling of evapotranspiration from land surface has long been an important issue in many research fields, e.g. the energy partition and water cycles of the global climate system. Two methods are widely used to estimate evapotranspiration in hydrology and climatology. In the residual method the latent heat flux is estimated as the residual of energy balance equation, while in the combination equation the energy balance is combined with a transfer equation to calculate the evaporative fraction. Both methods are built up on the basis of energy balance between the available energy and the sum of sensible and latent heat fluxes if photosynthesis, the heat storage and the advection are neglected. However, the imbalance between the available energy (the residual of net radiation and the soil heat flux) and the sum of sensible and latent heat fluxes has been often observed during several field experiments, such as FIFE, HEIFE, and GAME-Tibet and the TIPEX. The reasons of the lack of closure in energy balance may attribute to various sources and can be put into two categories: (1) incompleteness in measurements including inadequate instrumentation and less representative fetch and insufficient sampling and too short averaging time; (2) incompleteness in the consideration of energy balance terms because many other processes may have non negligible contributions to the energy budget to some degrees depending on the complexity of the land surface. These may bring problem both to the evaluation of energy balance based models and to the framework on which the model is constructed. In this study, the imbalance problem is investigated by the analysis of the data collected in the filed measurements during GAME-Tibet and TIPEX. As a further study, a validated model SEBS using many other datasets is used to clarify the impact of such imbalance to the energy-balance based models. A correction method is proposed to solve the imbalance problems existing in collected data.

  17. 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...

  18. 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

  19. 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.

  20. Application of the Combination Approach for Estimating Evapotranspiration in Puerto Rico

    NASA Technical Reports Server (NTRS)

    Harmsen, Eric; Luvall, Jeffrey; Gonzalez, Jorge

    2005-01-01

    The ability to estimate short-term fluxes of water vapor from the land surface is important for validating latent heat flux estimates from high resolution remote sensing techniques. A new, relatively inexpensive method is presented for estimating t h e ground-based values of the surface latent heat flux or evapotranspiration.

  1. Estimating Regional Surface Heat and Moisture Fluxes above Prairie Cropland from Surface and Upper-Air Measurements.

    NASA Astrophysics Data System (ADS)

    Barr, Alan G.; Strong, G. S.

    1996-10-01

    Upper-air budget methods can be used to estimate the surface sensible and latent heat flux densities on a regional scale. This study assesses the application of radiosonde-based budget methods above homogeneous cropland. Serial daytime soundings were released from Kenaston and Saskatoon, Canada, on fair-weather days between 24 June and 31 July 1991.Two independent methods were used to establish ground truth: surface-layer Bowen ratio-energy balance and Priestley-Taylor. This study was the fist to extend the surface-layer Bowen ratio method to conventional upper-air soundings. The two ground-truth methods agreed to within 20% at both locations and gave mean daytime Bowen ratios of 0.33.The upper-air budget surface flux estimates agreed most consistently with ground truth when the budget was integrated over the atmospheric boundary layer (BL) and used parameterized entrainment with a value for the entrainment parameter AR of 0.4. The BL budget with AR of 0.4 closed the daytime surface energy balance to within 4% at Kenaston and 7% at Saskatoon and gave a mean estimate for the Bowen ratio that agreed to within 20% of the mean ground-truth estimates. However, the BL budget estimates for 2-3-h periods were quite variable, and it was necessary to average the budget estimates over periods of 12 days or longer to produce credible values. Random sampling errors and uncertainty in horizontal advection were partly responsible for the high variability of the budget estimates, but these terms averaged to zero over extended periods. More seriously, the BL budget estimates for the surface latent heat flux were quite sensitive to the method for estimating entrainment. Because the authors were unable to establish a preferred entrainment estimate a priori, the BL budget estimates for the surface latent heat flux were considered to be unreliable. Further study is needed to develop a reliable and independent method for specifying the value for AR.

  2. 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

  3. 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.

  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. Space Heating Load Estimation Procedure for CHP Systems sizing

    NASA Astrophysics Data System (ADS)

    Vocale, P.; Pagliarini, G.; Rainieri, S.

    2015-11-01

    Due to its environmental and energy benefits, the Combined Heat and Power (CHP) represents certainly an important measure to improve energy efficiency of buildings. Since the energy performance of the CHP systems strongly depends on the fraction of the useful cogenerated heat (i.e. the cogenerated heat that is actually used to meet building thermal demand), in building applications of CHP, it is necessary to know the space heating and cooling loads profile to optimise the system efficiency. When the heating load profile is unknown or difficult to calculate with a sufficient accuracy, as may occur for existing buildings, it can be estimated from the cumulated energy uses by adopting the loads estimation procedure (h-LEP). With the aim to evaluate the useful fraction of the cogenerated heat for different operating conditions in terms of buildings characteristics, weather data and system capacity, the h-LEP is here implemented with a single climate variable: the hourly average dry- bulb temperature. The proposed procedure have been validated resorting to the TRNSYS simulation tool. The results, obtained by considering a building for hospital use, reveal that the useful fraction of the cogenerated heat can be estimated with an average accuracy of ± 3%, within the range of operative conditions considered in the present study.

  7. Inferring Latent States and Refining Force Estimates via Hierarchical Dirichlet Process Modeling in Single Particle Tracking Experiments.

    PubMed

    Calderon, Christopher P; Bloom, Kerry

    2015-01-01

    Understanding the basis for intracellular motion is critical as the field moves toward a deeper understanding of the relation between Brownian forces, molecular crowding, and anisotropic (or isotropic) energetic forcing. Effective forces and other parameters used to summarize molecular motion change over time in live cells due to latent state changes, e.g., changes induced by dynamic micro-environments, photobleaching, and other heterogeneity inherent in biological processes. This study discusses limitations in currently popular analysis methods (e.g., mean square displacement-based analyses) and how new techniques can be used to systematically analyze Single Particle Tracking (SPT) data experiencing abrupt state changes in time or space. The approach is to track GFP tagged chromatids in metaphase in live yeast cells and quantitatively probe the effective forces resulting from dynamic interactions that reflect the sum of a number of physical phenomena. State changes can be induced by various sources including: microtubule dynamics exerting force through the centromere, thermal polymer fluctuations, and DNA-based molecular machines including polymerases and protein exchange complexes such as chaperones and chromatin remodeling complexes. Simulations aiming to show the relevance of the approach to more general SPT data analyses are also studied. Refined force estimates are obtained by adopting and modifying a nonparametric Bayesian modeling technique, the Hierarchical Dirichlet Process Switching Linear Dynamical System (HDP-SLDS), for SPT applications. The HDP-SLDS method shows promise in systematically identifying dynamical regime changes induced by unobserved state changes when the number of underlying states is unknown in advance (a common problem in SPT applications). We expand on the relevance of the HDP-SLDS approach, review the relevant background of Hierarchical Dirichlet Processes, show how to map discrete time HDP-SLDS models to classic SPT models, and

  8. Inferring Latent States and Refining Force Estimates via Hierarchical Dirichlet Process Modeling in Single Particle Tracking Experiments

    PubMed Central

    Calderon, Christopher P.; Bloom, Kerry

    2015-01-01

    Understanding the basis for intracellular motion is critical as the field moves toward a deeper understanding of the relation between Brownian forces, molecular crowding, and anisotropic (or isotropic) energetic forcing. Effective forces and other parameters used to summarize molecular motion change over time in live cells due to latent state changes, e.g., changes induced by dynamic micro-environments, photobleaching, and other heterogeneity inherent in biological processes. This study discusses limitations in currently popular analysis methods (e.g., mean square displacement-based analyses) and how new techniques can be used to systematically analyze Single Particle Tracking (SPT) data experiencing abrupt state changes in time or space. The approach is to track GFP tagged chromatids in metaphase in live yeast cells and quantitatively probe the effective forces resulting from dynamic interactions that reflect the sum of a number of physical phenomena. State changes can be induced by various sources including: microtubule dynamics exerting force through the centromere, thermal polymer fluctuations, and DNA-based molecular machines including polymerases and protein exchange complexes such as chaperones and chromatin remodeling complexes. Simulations aiming to show the relevance of the approach to more general SPT data analyses are also studied. Refined force estimates are obtained by adopting and modifying a nonparametric Bayesian modeling technique, the Hierarchical Dirichlet Process Switching Linear Dynamical System (HDP-SLDS), for SPT applications. The HDP-SLDS method shows promise in systematically identifying dynamical regime changes induced by unobserved state changes when the number of underlying states is unknown in advance (a common problem in SPT applications). We expand on the relevance of the HDP-SLDS approach, review the relevant background of Hierarchical Dirichlet Processes, show how to map discrete time HDP-SLDS models to classic SPT models, and

  9. Coupling heat and chemical tracer experiments for estimating heat transfer parameters in shallow alluvial aquifers.

    PubMed

    Wildemeersch, S; Jamin, P; Orban, P; Hermans, T; Klepikova, M; Nguyen, F; Brouyère, S; Dassargues, A

    2014-11-15

    Geothermal energy systems, closed or open, are increasingly considered for heating and/or cooling buildings. The efficiency of such systems depends on the thermal properties of the subsurface. Therefore, feasibility and impact studies performed prior to their installation should include a field characterization of thermal properties and a heat transfer model using parameter values measured in situ. However, there is a lack of in situ experiments and methodology for performing such a field characterization, especially for open systems. This study presents an in situ experiment designed for estimating heat transfer parameters in shallow alluvial aquifers with focus on the specific heat capacity. This experiment consists in simultaneously injecting hot water and a chemical tracer into the aquifer and monitoring the evolution of groundwater temperature and concentration in the recovery well (and possibly in other piezometers located down gradient). Temperature and concentrations are then used for estimating the specific heat capacity. The first method for estimating this parameter is based on a modeling in series of the chemical tracer and temperature breakthrough curves at the recovery well. The second method is based on an energy balance. The values of specific heat capacity estimated for both methods (2.30 and 2.54MJ/m(3)/K) for the experimental site in the alluvial aquifer of the Meuse River (Belgium) are almost identical and consistent with values found in the literature. Temperature breakthrough curves in other piezometers are not required for estimating the specific heat capacity. However, they highlight that heat transfer in the alluvial aquifer of the Meuse River is complex and contrasted with different dominant process depending on the depth leading to significant vertical heat exchange between upper and lower part of the aquifer. Furthermore, these temperature breakthrough curves could be included in the calibration of a complex heat transfer model for

  10. Heat Load Estimator for Smoothing Pulsed Heat Loads on Supercritical Helium Loops

    NASA Astrophysics Data System (ADS)

    Hoa, C.; Lagier, B.; Rousset, B.; Bonnay, P.; Michel, F.

    Superconducting magnets for fusion are subjected to large variations of heat loads due to cycling operation of tokamaks. The cryogenic system shall operate smoothly to extract the pulsed heat loads by circulating supercritical helium into the coils and structures. However the value of the total heat loads and its temporal variation are not known before the plasma scenario starts. A real-time heat load estimator is of interest for the process control of the cryogenic system in order to anticipate the arrival of pulsed heat loads to the refrigerator and finally to optimize the operation of the cryogenic system. The large variation of the thermal loads affects the physical parameters of the supercritical helium loop (pressure, temperature, mass flow) so those signals can be used for calculating instantaneously the loads deposited into the loop. The methodology and algorithm are addressed in the article for estimating the heat load deposition before it reaches the refrigerator. The CEA patented process control has been implemented in a Programmable Logic Controller (PLC) and has been successfully validated on the HELIOS test facility at CEA Grenoble. This heat load estimator is complementary to pulsed load smoothing strategies providing an estimation of the optimized refrigeration power. It can also effectively improve the process control during the transient between different operating modes by adjusting the refrigeration power to the need. This way, the heat load estimator participates to the safe operation of the cryogenic system.

  11. Estimates of heat stress relief needs for Holstein dairy cows.

    PubMed

    Berman, A

    2005-06-01

    Estimates of environmental heat stress are required for heat stress relief measures in cattle. Heat stress is commonly assessed by the temperature-humidity index (THI), the sum of dry and wet bulb temperatures. The THI does not include an interaction between temperature and humidity, although evaporative heat loss increases with rising air temperature. Coat, air velocity, and radiation effects also are not accounted for in the THI. The Holstein dairy cow is the primary target of heat stress relief, followed by feedlot cattle. Heat stress may be estimated for a variety of conditions by thermal balance models. The models consist of animal-specific data (BW, metabolic heat production, tissue and coat insulation, skin water loss, coat depth, and minimal and maximal tidal volumes) and of general heat exchange equations. A thermal balance simulation model was modified to adapt it for Holstein cows by using Holstein data for the animal characteristics in the model, and was validated by comparing its outputs to experimental data. Model outputs include radiant, convective, skin evaporative, respiratory heat loss and rate of change of body temperature. Effects of milk production (35 and 45 kg/d), hair coat depth (3 and 6 mm), air temperature (20 to 45 degrees C), air velocity (0.2 to 2.0 m/s), air humidity (0.8 to 3.9 kPa), and exposed body surface (100, 75, and 50%) on thermal balance outputs were examined. Environmental conditions at which respiratory heat loss attained approximately 50% of its maximal value were defined as thresholds for intermediate heat stress. Air velocity increased and humidity significantly decreased threshold temperatures, particularly at higher coat depth. The effect of air velocity was amplified at high humidity. Increasing milk production from 35 to 45 kg/d decreased threshold temperature by 5 degrees C. In the lying cow, the lower air velocity in the proximity of body surface and the smaller exposed surface markedly decrease threshold

  12. Heat Transfer Mechanism of a Vertical Wall Inside a Two-Phase Closed Thermosiphon Evaporator and Its Estimation

    NASA Astrophysics Data System (ADS)

    O-Uchi, Masaki; Hirose, Koichi; Saito, Futami

    The inside heat transfer coefficient, overall heat transfer coefficient, and heat flow rate at the heating section of the thermosiphon were determined for each heating method. In order to observe the heat transfer mechanism in the evaporator, a thermosiphon unit made of glass was assembled and conducted separately. The results of these experiments with these two units are summarized as follows. (1) Nucleate boiling due to the internal heat transfer mechanism improves the heat transfer characteristics of the thermosiphon unit. Under the specific heating conditions with dropwise condensation, there are two types of heat transfer mechanism occur in the evaporator accompanying nucleate boiling, i. e. latent heat transfer and sensible heat transfer. (2) In the case of latent heat transfer, the inside heat transfer coefficient has an upper limit which can be used as a criterion to determine the type of internal heat transfer mechanism.

  13. Estimation of spatially distributed turbulent heat fluxes using thermal information captured from an UAS

    NASA Astrophysics Data System (ADS)

    Brenner, Claire; Thiem, Christina Elisabeth; Bernhardt, Matthias; Schulz, Karsten

    2016-04-01

    Evapotranspiration is a key component of the Earth's water and energy cycle. However, measuring evapotranspiration is difficult and distributed information with high spatial resolution is rare. Land surface temperature (LST) is often used as source of data for the estimation of evapotranspiration. Actual LST is mainly controlled by the amount of incoming radiation, surface albedo, water availability, ventilation of the surface and in case of vegetation stands also by the intensity of the transpiration process. Thus it contains valuable information on the actual state of the soil-vegetation-atmosphere system. Typically LST information is available from satellite imagery or from radiometers installed at experimental sites. Thus, measured LST is either representative for areas of hundreds of square meters (satellites), or for certain points (radiometers). Thermal imaging from unmanned aerial systems (UAS) can be used for addressing this scale gap and is a trade-off between flexibility and ease of use on the one hand and spatial coverage on the other hand. In this study we have measured surface temperatures at a grassland site in Luxemburg in July 2015 by means of a thermal infrared camera mounted on an octocopter drone. At the same time scintillometer measurements were made at the same field. The experimental set-up was completed by meteorological and radiation measurements. UAS flights were conducted on a sequence of days over a time period of 2 weeks and with up to ten flights a day in order to monitor diurnal variation of LST. The observed spatially distributed surface temperatures were then used to estimate sensible and latent heat fluxes using three algorithms. All of them make use of observed vertical temperature gradients between surface and atmosphere but do show a different complexity. Two of them are single-source models while one is a dual-source representation of the soil-vegetation system. Although the experimental site was fully covered by grass, LST

  14. 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.…

  15. Comparative estimates of anthropogenic heat emission in relation to surface energy balance of a subtropical urban neighborhood

    NASA Astrophysics Data System (ADS)

    Park, Changhyoun; Schade, Gunnar W.; Werner, Nicholas D.; Sailor, David J.; Kim, Cheol-Hee

    2016-02-01

    Long-term eddy covariance measurements have been conducted in a subtropical urban area, an older neighborhood north of downtown Houston. The measured net radiation (Q*), sensible heat flux (H) and latent heat flux (LE) showed typical seasonal diurnal variations in urban areas: highest in summer; lowest in winter. From an analysis of a subset of the first two years of measurements, we find that approximately 42% of Q* is converted into H, and 22% into LE during daytime. The local anthropogenic heat emissions were estimated conventionally using the long-term residual method and the heat emission inventory approach. We also developed a footprint-weighted inventory approach, which combines the inventory approach with flux footprint calculations. The results show a range of annual anthropogenic heat fluxes from 20 W m-2 to 30 W m-2 within the study domain. Possibly as a result of local radiation versus heat flux footprint mismatches, the mean value of surface heat storage (ΔQs) was relatively large, approximately 43% and 34% of Q* in summer and winter, respectively, during daytime.

  16. Global Intercomparison of 12 Land Surface Heat Flux Estimates

    NASA Technical Reports Server (NTRS)

    Jimenez, C.; Prigent, C.; Mueller, B.; Seneviratne, S. I.; McCabe, M. F.; Wood, E. F.; Rossow, W. B.; Balsamo, G.; Betts, A. K.; Dirmeyer, P. A.; Fisher, J. B.; Jung, M.; Kanamitsu, M.; Reichle, R. H.; Reichstein, M.; Rodell, M.; Sheffield, J.; Tu, K.; Wang, K.

    2011-01-01

    A global intercomparison of 12 monthly mean land surface heat flux products for the period 1993-1995 is presented. The intercomparison includes some of the first emerging global satellite-based products (developed at Paris Observatory, Max Planck Institute for Biogeochemistry, University of California Berkeley, University of Maryland, and Princeton University) and examples of fluxes produced by reanalyses (ERA-Interim, MERRA, NCEP-DOE) and off-line land surface models (GSWP-2, GLDAS CLM/ Mosaic/Noah). An intercomparison of the global latent heat flux (Q(sub le)) annual means shows a spread of approx 20 W/sq m (all-product global average of approx 45 W/sq m). A similar spread is observed for the sensible (Q(sub h)) and net radiative (R(sub n)) fluxes. In general, the products correlate well with each other, helped by the large seasonal variability and common forcing data for some of the products. Expected spatial distributions related to the major climatic regimes and geographical features are reproduced by all products. Nevertheless, large Q(sub le)and Q(sub h) absolute differences are also observed. The fluxes were spatially averaged for 10 vegetation classes. The larger Q(sub le) differences were observed for the rain forest but, when normalized by mean fluxes, the differences were comparable to other classes. In general, the correlations between Q(sub le) and R(sub n) were higher for the satellite-based products compared with the reanalyses and off-line models. The fluxes were also averaged for 10 selected basins. The seasonality was generally well captured by all products, but large differences in the flux partitioning were observed for some products and basins.

  17. Data concurrency is required for estimating urban heat island intensity.

    PubMed

    Zhao, Shuqing; Zhou, Decheng; Liu, Shuguang

    2016-01-01

    Urban heat island (UHI) can generate profound impacts on socioeconomics, human life, and the environment. Most previous studies have estimated UHI intensity using outdated urban extent maps to define urban and its surrounding areas, and the impacts of urban boundary expansion have never been quantified. Here, we assess the possible biases in UHI intensity estimates induced by outdated urban boundary maps using MODIS Land surface temperature (LST) data from 2009 to 2011 for China's 32 major cities, in combination with the urban boundaries generated from urban extent maps of the years 2000, 2005 and 2010. Our results suggest that it is critical to use concurrent urban extent and LST maps to estimate UHI at the city and national levels. Specific definition of UHI matters for the direction and magnitude of potential biases in estimating UHI intensity using outdated urban extent maps. PMID:26243476

  18. Estimation of radiative heat transfer using a geometric human model.

    PubMed

    Kakuta, N; Yokoyama, S; Nakamura, M; Mabuchi, K

    2001-03-01

    In order to provide a detailed estimate of radiative heat transfer between a human body and its surrounding environment, we have developed a geometric model of a human form and an algorithm. The model closely resembles the actual shape of a human body and is composed of small quadrilateral surfaces. Dealing with an object or a space with an arbitrary shape, the developed algorithm can judge efficiently whether there is an obstruction between a pair of surfaces. As a result, the angle factors between a pair of surfaces that only occur during radiative heat transfer can be defined. The distribution of the radiative heat transfer rates shows the characteristics of body shape and variations in posture. PMID:11327500

  19. A fast Monte Carlo EM algorithm for estimation in latent class model analysis with an application to assess diagnostic accuracy for cervical neoplasia in women with AGC

    PubMed Central

    Kang, Le; Carter, Randy; Darcy, Kathleen; Kauderer, James; Liao, Shu-Yuan

    2013-01-01

    In this article we use a latent class model (LCM) with prevalence modeled as a function of covariates to assess diagnostic test accuracy in situations where the true disease status is not observed, but observations on three or more conditionally independent diagnostic tests are available. A fast Monte Carlo EM (MCEM) algorithm with binary (disease) diagnostic data is implemented to estimate parameters of interest; namely, sensitivity, specificity, and prevalence of the disease as a function of covariates. To obtain standard errors for confidence interval construction of estimated parameters, the missing information principle is applied to adjust information matrix estimates. We compare the adjusted information matrix based standard error estimates with the bootstrap standard error estimates both obtained using the fast MCEM algorithm through an extensive Monte Carlo study. Simulation demonstrates that the adjusted information matrix approach estimates the standard error similarly with the bootstrap methods under certain scenarios. The bootstrap percentile intervals have satisfactory coverage probabilities. We then apply the LCM analysis to a real data set of 122 subjects from a Gynecologic Oncology Group (GOG) study of significant cervical lesion (S-CL) diagnosis in women with atypical glandular cells of undetermined significance (AGC) to compare the diagnostic accuracy of a histology-based evaluation, a CA-IX biomarker-based test and a human papillomavirus (HPV) DNA test. PMID:24163493

  20. 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.

  1. 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.

  2. Estimating Antarctic Geothermal Heat Flux using Gravity Inversion

    NASA Astrophysics Data System (ADS)

    Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; Golynsky, A. V.; Sasha Rogozhina, Irina

    2013-04-01

    Geothermal heat flux (GHF) in Antarctica is very poorly known. We have determined (Vaughan et al. 2012) top basement heat-flow for Antarctica and adjacent rifted continental margins using gravity inversion mapping of crustal thickness and continental lithosphere thinning (Chappell & Kusznir 2008). Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental and oceanic lithosphere. The sensitivity of present-day Antarctic top basement heat-flow to initial continental radiogenic heat productivity, continental rift and margin breakup age has been examined. Knowing GHF distribution for East Antarctica and the Gamburtsev Subglacial Mountains (GSM) region in particular is critical because: 1) The GSM likely acted as key nucleation point for the East Antarctic Ice Sheet (EAIS); 2) the region may contain the oldest ice of the EAIS - a prime target for future ice core drilling; 3) GHF is important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology (Bell et al. 2011). An integrated multi-dataset-based GHF model for East Antarctica is planned that will resolve the wide range of estimates previously published using single datasets. The new map and existing GHF distribution estimates available for Antarctica will be evaluated using direct ice temperature measurements obtained from deep ice cores, estimates of GHF derived from subglacial lakes, and a thermodynamic ice-sheet model of the Antarctic Ice Sheet driven by past climate reconstructions and each of analysed heat flow maps, as has recently been done for the Greenland region (Rogozhina et al. 2012). References Bell, R.E., Ferraccioli, F., Creyts, T.T., Braaten, D., Corr, H., Das, I., Damaske, D., Frearson, N

  3. Simulation of fluid, heat transport to estimate desert stream infiltration.

    PubMed

    Kulongoski, Justin T; Izbicki, John A

    2008-01-01

    In semiarid regions, the contribution of infiltration from intermittent streamflow to ground water recharge may be quantified by comparing simulations of fluid and heat transport beneath stream channels to observed ground temperatures. In addition to quantifying natural recharge, streamflow infiltration estimates provide a means to characterize the physical properties of stream channel sediments and to identify suitable locations for artificial recharge sites. Rates of winter streamflow infiltration along stream channels are estimated based on the cooling effect of infiltrated water on streambed sediments, combined with the simulation of two-dimensional fluid and heat transport using the computer program VS2DH. The cooling effect of ground water is determined by measuring ground temperatures at regular intervals beneath stream channels and nearby channel banks in order to calculate temperature-depth profiles. Additional data inputs included the physical, hydraulic, and thermal properties of unsaturated alluvium, and monthly ground temperatures measurements over an annual cycle. Observed temperatures and simulation results can provide estimates of the minimum threshold for deep infiltration, the variability of infiltration along stream channels, and also the frequency of infiltration events. PMID:18194325

  4. Simulation of fluid, heat transport to estimate desert stream infiltration

    USGS Publications Warehouse

    Kulongoski, J.T.; Izbicki, J.A.

    2008-01-01

    In semiarid regions, the contribution of infiltration from intermittent streamflow to ground water recharge may be quantified by comparing simulations of fluid and heat transport beneath stream channels to observed ground temperatures. In addition to quantifying natural recharge, streamflow infiltration estimates provide a means to characterize the physical properties of stream channel sediments and to identify suitable locations for artificial recharge sites. Rates of winter streamflow infiltration along stream channels are estimated based on the cooling effect of infiltrated water on streambed sediments, combined with the simulation of two-dimensional fluid and heat transport using the computer program VS2DH. The cooling effect of ground water is determined by measuring ground temperatures at regular intervals beneath stream channels and nearby channel banks in order to calculate temperature-depth profiles. Additional data inputs included the physical, hydraulic, and thermal properties of unsaturated alluvium, and monthly ground temperatures measurements over an annual cycle. Observed temperatures and simulation results can provide estimates of the minimum threshold for deep infiltration, the variability of infiltration along stream channels, and also the frequency of infiltration events.

  5. 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…

  6. A New Model for Heat Flow in Extensional Basins: Estimating Radiogenic Heat Production

    SciTech Connect

    Waples, Douglas W.

    2002-06-15

    Radiogenic heat production (RHP) represents a significant fraction of surface heat flow, both on cratons and in sedimentary basins. RHP within continental crust-especially the upper crust-is high. RHP at any depth within the crust can be estimated as a function of crustal age. Mantle RHP, in contrast, is always low, contributing at most 1 to 2 mW/m{sup 2} to total heat flow. Radiogenic heat from any noncrystalline basement that may be present also contributes to total heat flow. RHP from metamorphic rocks is similar to or slightly lower than that from their precursor sedimentary rocks. When extension of the lithosphere occurs-as for example during rifting-the radiogenic contribution of each layer of the lithosphere and noncrystalline basement diminishes in direct proportion to the degree of extension of that layer. Lithospheric RHP today is somewhat less than in the distant past, as a result of radioactive decay. In modeling, RHP can be varied through time by considering the half lives of uranium, thorium, and potassium, and the proportional contribution of each of those elements to total RHP from basement. RHP from sedimentary rocks ranges from low for most evaporites to high for some shales, especially those rich in organic matter. The contribution to total heat flow of radiogenic heat from sediments depends strongly on total sediment thickness, and thus differs through time as subsidence and basin filling occur. RHP can be high for thick clastic sections. RHP in sediments can be calculated using ordinary or spectral gamma-ray logs, or it can be estimated from the lithology.

  7. Methods to Estimate Acclimatization to Urban Heat Island Effects on Heat- and Cold-Related Mortality

    PubMed Central

    Milojevic, Ai; Armstrong, Ben G.; Gasparrini, Antonio; Bohnenstengel, Sylvia I.; Barratt, Benjamin; Wilkinson, Paul

    2016-01-01

    Background: Investigators have examined whether heat mortality risk is increased in neighborhoods subject to the urban heat island (UHI) effect but have not identified degrees of difference in susceptibility to heat and cold between cool and hot areas, which we call acclimatization to the UHI. Objectives: We developed methods to examine and quantify the degree of acclimatization to heat- and cold-related mortality in relation to UHI anomalies and applied these methods to London, UK. Methods: Case–crossover analyses were undertaken on 1993–2006 mortality data from London UHI decile groups defined by anomalies from the London average of modeled air temperature at a 1-km grid resolution. We estimated how UHI anomalies modified excess mortality on cold and hot days for London overall and displaced a fixed-shape temperature-mortality function (“shifted spline” model). We also compared the observed associations with those expected under no or full acclimatization to the UHI. Results: The relative risk of death on hot versus normal days differed very little across UHI decile groups. A 1°C UHI anomaly multiplied the risk of heat death by 1.004 (95% CI: 0.950, 1.061) (interaction rate ratio) compared with the expected value of 1.070 (1.057, 1.082) if there were no acclimatization. The corresponding UHI interaction for cold was 1.020 (0.979, 1.063) versus 1.030 (1.026, 1.034) (actual versus expected under no acclimatization, respectively). Fitted splines for heat shifted little across UHI decile groups, again suggesting acclimatization. For cold, the splines shifted somewhat in the direction of no acclimatization, but did not exclude acclimatization. Conclusions: We have proposed two analytical methods for estimating the degree of acclimatization to the heat- and cold-related mortality burdens associated with UHIs. The results for London suggest relatively complete acclimatization to the UHI effect on summer heat–related mortality, but less clear evidence for

  8. Redescending M-Type Estimators of Latent Ability. Program Statistics Research, Technical Report No. 82-30.

    ERIC Educational Resources Information Center

    Jones, Douglas H.

    New ability estimators have been proposed by Wainer and Wright (1980) and Mislevy and Bock (1981) that are resistant against guessing and careless behaviors exhibited by some examinees. This paper presents another class of ability estimators that are resistant to departures from the underlying assumptions concerning guessing and carelessness. In…

  9. Using Gravity Inversion to Estimate Antarctic Geothermal Heat Flux

    NASA Astrophysics Data System (ADS)

    Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; (Sasha) Golynsky, A. V.; Rogozhina, Irina

    2014-05-01

    New modelling studies for Greenland have recently underlined the importance of GHF for long-term ice sheet behaviour (Petrunin et al. 2013). Revised determinations of top basement heat-flow for Antarctica and adjacent rifted continental margins using gravity inversion mapping of crustal thickness and continental lithosphere thinning (Chappell & Kusznir 2008), using BedMap2 data have provided improved estimates of geothermal heat flux (GHF) in Antarctica where it is very poorly known. Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental and oceanic lithosphere. The sensitivity of present-day Antarctic top basement heat-flow to initial continental radiogenic heat productivity, continental rift and margin breakup age has been examined. Recognition of the East Antarctic Rift System (EARS), a major Permian to Cretaceous age rift system that appears to extend from the continental margin at the Lambert Rift to the South Pole region, a distance of 2500 km (Ferraccioli et al. 2011) and is comparable in scale to the well-studied East African rift system, highlights that crustal variability in interior Antarctica is much greater than previously assumed. GHF is also important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology (Bell et al. 2011). References Bell, R.E., Ferraccioli, F., Creyts, T.T., Braaten, D., Corr, H., Das, I., Damaske, D., Frearson, N., Jordan, T., Rose, K., Studinger, M. & Wolovick, M. 2011. Widespread persistent thickening of the East Antarctic Ice Sheet by freezing from the base. Science, 331 (6024), 1592-1595. Chappell, A.R. & Kusznir, N.J. 2008. Three-dimensional gravity inversion for Moho depth at rifted continental margins

  10. Estimation of water flux in urban area using eddy covariance measurements in Riverside, Southern California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Micrometeorological methods can direct measure the sensible and latent heat flux in specific sites and provide robust estimates of the evaporative fraction (EF), which is the fraction of available surface energy contained in latent heat. Across a vegetation coverage gradient in urban area, an empir...

  11. Cost Estimates of Electricity from a TPV Residential Heating System

    NASA Astrophysics Data System (ADS)

    Palfinger, Günther; Bitnar, Bernd; Durisch, Wilhelm; Mayor, Jean-Claude; Grützmacher, Detlev; Gobrecht, Jens

    2003-01-01

    A thermophotovoltaic (TPV) system was built using a 12 to 20 kWth methane burner which should be integrated into a conventional residential heating system. The TPV system is cylindrical in shape and consists of a selective Yb2O3 emitter, a quartz glass tube to prevent the exhaust gases from heating the cells and a 0.2 m2 monocrystalline silicon solar cell module which is water cooled. The maximum system efficiency of 1.0 % was obtained at a thermal input power of 12 kWth. The electrical power suffices to run a residential heating system in the full power range (12 to 20 kWth) independently of the grid. The end user costs of the TPV components - emitter, glass tube, photocells and cell cooling circuit - were estimated considering 4 different TPV scenarios. The existing technique was compared with an improved system currently under development, which consists of a flexible photocell module that can be glued into the boiler housing and with systems with improved system efficiency (1.5 to 5 %) and geometry. Prices of the electricity from 2.5 to 22 EURcents/kWhel (excl. gas of about 3.5 EURcents/kWh), which corresponds to system costs of 340 to 3000 EUR/kWel,peak, were calculated. The price of electricity by TPV was compared with that of fuel cells and gas engines. While fuel cells are still expensive, gas engines have the disadvantage of maintenance, noise and bulkiness. TPV, in contrast, is a cost efficient alternative to produce heat and electricity, particularly in small peripheral units.

  12. 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

  13. Estimation of respiratory heat flows in prediction of heat strain among Taiwanese steel workers

    NASA Astrophysics Data System (ADS)

    Chen, Wang-Yi; Juang, Yow-Jer; Hsieh, Jung-Yu; Tsai, Perng-Jy; Chen, Chen-Peng

    2016-06-01

    International Organization for Standardization 7933 standard provides evaluation of required sweat rate (RSR) and predicted heat strain (PHS). This study examined and validated the approximations in these models estimating respiratory heat flows (RHFs) via convection (C res) and evaporation (E res) for application to Taiwanese foundry workers. The influence of change in RHF approximation to the validity of heat strain prediction in these models was also evaluated. The metabolic energy consumption and physiological quantities of these workers performing at different workloads under elevated wet-bulb globe temperature (30.3 ± 2.5 °C) were measured on-site and used in the calculation of RHFs and indices of heat strain. As the results show, the RSR model overestimated the C res for Taiwanese workers by approximately 3 % and underestimated the E res by 8 %. The C res approximation in the PHS model closely predicted the convective RHF, while the E res approximation over-predicted by 11 %. Linear regressions provided better fit in C res approximation (R 2 = 0.96) than in E res approximation (R 2 ≤ 0.85) in both models. The predicted C res deviated increasingly from the observed value when the WBGT reached 35 °C. The deviations of RHFs observed for the workers from those predicted using the RSR or PHS models did not significantly alter the heat loss via the skin, as the RHFs were in general of a level less than 5 % of the metabolic heat consumption. Validation of these approximations considering thermo-physiological responses of local workers is necessary for application in scenarios of significant heat exposure.

  14. Regional heat flow variations in the northern Michigan and Lake Superior region determined using the silica heat flow estimator

    USGS Publications Warehouse

    Vugrinovich, R.

    1987-01-01

    Conventional heat flow data are sparse for northern Michigan. The groundwater silica heat flow estimator expands the database sufficiently to allow regional variations in heat flow to be examined. Heat flow shows a pattern of alternating highs and lows trending ESE across the Upper Peninsula and Lake Superior. The informal names given to these features, their characteristic heat flow and inferred causes are listed: {A table is presented} The results suggest that, for the study area, regional variations in heat flow cannot be interpreted solely in terms of regional variations of the heat generation rate of basement rocks. ?? 1987.

  15. 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

  16. 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.

  17. Using estimated factor scores from a bifactor analysis to examine the unique effects of the latent variables measured by the WAIS-IV on academic achievement.

    PubMed

    Kranzler, John H; Benson, Nicholas; Floyd, Randy G

    2015-12-01

    This study used estimated factor scores from a bifactor analysis of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) to examine the unique effects of its latent variables on academic achievement. In doing so, we addressed the potential limitation of multicollinearity in previous studies of the incremental validity of the WAIS-IV. First, factor scores representing psychometric g and 4 group factors representing the WAIS-IV index scales were computed from a bifactor model. Subtest and composite scores for the Wechsler Individual Achievement Test-Third Edition (WIAT-II) were then predicted from these estimated factor scores in simultaneous multiple regression. Results of this study only partially replicated the findings of previous research on the incremental validity of scores that can be derived from performance on the WAIS-IV. Although we found that psychometric g is the most important underlying construct measured by the WAIS-IV for the prediction of academic achievement in general, results indicated that the unique effect of Verbal Comprehension is also important for predicting achievement in reading, spelling, and oral communication skills. Based on these results, measures of both psychometric g and Verbal Comprehension could be cautiously interpreted when considering high school students' performance in these areas of achievement. PMID:25844532

  18. 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

  19. 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

  20. 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,…

  1. Tracer Testing for Estimating Heat Transfer Area in Fractured Reservoirs

    SciTech Connect

    Pruess, Karsten; van Heel, Ton; Shan, Chao

    2004-05-12

    A key parameter governing the performance and life-time of a Hot Fractured Rock (HFR) reservoir is the effective heat transfer area between the fracture network and the matrix rock. We report on numerical modeling studies into the feasibility of using tracer tests for estimating heat transfer area. More specifically, we discuss simulation results of a new HFR characterization method which uses surface-sorbing tracers for which the adsorbed tracer mass is proportional to the fracture surface area per unit volume. Sorption in the rock matrix is treated with the conventional formulation in which tracer adsorption is volume-based. A slug of solute tracer migrating along a fracture is subject to diffusion across the fracture walls into the adjacent rock matrix. Such diffusion removes some of the tracer from the fluid in the fractures, reducing and retarding the peak in the breakthrough curve (BTC) of the tracer. After the slug has passed the concentration gradient reverses, causing back-diffusion from the rock matrix into the fracture, and giving rise to a long tail in the BTC of the solute. These effects become stronger for larger fracture-matrix interface area, potentially providing a means for estimating this area. Previous field tests and modeling studies have demonstrated characteristic tailing in BTCs for volatile tracers in vapor-dominated reservoirs. Simulated BTCs for solute tracers in single-phase liquid systems show much weaker tails, as would be expected because diffusivities are much smaller in the aqueous than in the gas phase, by a factor of order 1000. A much stronger signal of fracture-matrix interaction can be obtained when sorbing tracers are used. We have performed simulation studies of surface-sorbing tracers by implementing a model in which the adsorbed tracer mass is assumed proportional to the fracture-matrix surface area per unit volume. The results show that sorbing tracers generate stronger tails in BTCs, corresponding to an effective

  2. 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.

  3. 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…

  4. 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.

  5. Estimation of low-potential heat recuperation efficiency of smoke fumes in a condensation heat utilizer under various operation conditions of a boiler and a heating system

    NASA Astrophysics Data System (ADS)

    Ionkin, I. L.; Ragutkin, A. V.; Luning, B.; Zaichenko, M. N.

    2016-06-01

    For enhancement of the natural gas utilization efficiency in boilers, condensation heat utilizers of low-potential heat, which are constructed based on a contact heat exchanger, can be applied. A schematic of the contact heat exchanger with a humidifier for preheating and humidifying of air supplied in the boiler for combustion is given. Additional low-potential heat in this scheme is utilized for heating of the return delivery water supplied from a heating system. Preheating and humidifying of air supplied for combustion make it possible to use the condensation utilizer for heating of a heat-transfer agent to temperature exceeding the dewpoint temperature of water vapors contained in combustion products. The decision to mount the condensation heat utilizer on the boiler was taken based on the preliminary estimation of the additionally obtained heat. The operation efficiency of the condensation heat utilizer is determined by its structure and operation conditions of the boiler and the heating system. The software was developed for the thermal design of the condensation heat utilizer equipped by the humidifier. Computation investigations of its operation are carried out as a function of various operation parameters of the boiler and the heating system (temperature of the return delivery water and smoke fumes, air excess, air temperature at the inlet and outlet of the condensation heat utilizer, heating and humidifying of air in the humidifier, and portion of the circulating water). The heat recuperation efficiency is estimated for various operation conditions of the boiler and the condensation heat utilizer. Recommendations on the most effective application of the condensation heat utilizer are developed.

  6. Estimative of energy budget in Brazilian Savanna

    NASA Astrophysics Data System (ADS)

    Santanna, F. B.; Arruda, P. H.; Pinto-Jr, O. B.; Nogueira, J. D.

    2013-12-01

    The main goal of this work was to estimate the sensible (H) and latent (LE) heat flux using the eddy covariance method in a Cerrado "Campo Sujo" area, basically with herb-shrub physiognomy, sparse woody vegetation and approximately 2m height. The geographical position of the Cerrado, altitude, latitude, longitude, climate and weather conditions are determined by the dynamics of the atmosphere that affects the whole South America and consequently influence the ecological framework of ecosystems. The results shown by the components considered in the energy balance were more significant during the day, which the atmospheric boundary layer extends from the ground to about 50 or 100 meters height, showing greater instability and turbulence (u* > 0.2 m / s), and this turbulence is what justifies the use of the eddy covariance method to estimate the sensible and latent heat flux. The Cerrado presents seasonal difference between the densities estimates of sensible (H) and latent (LE) heat flux. During the rainy season the sensible heat flux (H) was 25% and the latent heat flux (LE) 54%. During the dry season the sensible heat flux (H) was 42% and the latent heat flux (LE) 30% of the energy budget.

  7. Estimation of surface heat flux for ablation and charring of thermal protection material

    NASA Astrophysics Data System (ADS)

    Qian, Wei-qi; He, Kai-feng; Zhou, Yu

    2016-07-01

    Ablation of the thermal protection material of the reentry hypersonic flight vehicle is a complex physical and chemical process. To estimate the surface heat flux from internal temperature measurement is much more complex than the conventional inverse heat conduction problem case. In the paper, by utilizing a two-layer pyrogeneration-plane ablation model to model the ablation and charring of the material, modifying the finite control volume method to suit for the numerical simulation of the heat conduction equation with variable-geometry, the CGM along with the associated adjoint problem is developed to estimate the surface heat flux. This estimation method is verified with a numerical example at first, the results show that the estimation method is feasible and robust. The larger is the measurement noise, the greater is the deviation of the estimated result from the exact value, and the measurement noise of ablated surface position has a significant and more direct influence on the estimated result of surface heat flux. Furthermore, the estimation method is used to analyze the experimental data of ablation of blunt Carbon-phenolic material Narmco4028 in an arc-heater. It is shown that the estimated surface heat flux agrees with the heating power value of the arc-heater, and the estimation method is basically effective and potential to treat the engineering heat conduction problem with ablation.

  8. A framework for estimating causal effects in latent class analysis: is there a causal link between early sex and subsequent profiles of delinquency?

    PubMed

    Butera, Nicole M; Lanza, Stephanie T; Coffman, Donna L

    2014-06-01

    Prevention scientists use latent class analysis (LCA) with increasing frequency to characterize complex behavior patterns and profiles of risk. Often, the most important research questions in these studies involve establishing characteristics that predict membership in the latent classes, thus describing the composition of the subgroups and suggesting possible points of intervention. More recently, prevention scientists have begun to adopt modern methods for drawing causal inference from observational data because of the bias that can be introduced by confounders. This same issue of confounding exists in any analysis of observational data, including prediction of latent class membership. This study demonstrates a straightforward approach to causal inference in LCA that builds on propensity score methods. We demonstrate this approach by examining the causal effect of early sex on subsequent delinquency latent classes using data from 1,890 adolescents in 11th and 12th grade from wave I of the National Longitudinal Study of Adolescent Health. Prior to the statistical adjustment for potential confounders, early sex was significantly associated with delinquency latent class membership for both genders (p = 0.02). However, the propensity score adjusted analysis indicated no evidence for a causal effect of early sex on delinquency class membership (p = 0.76) for either gender. Sample R and SAS code is included in an Appendix in the ESM so that prevention scientists may adopt this approach to causal inference in LCA in their own work. PMID:23839479

  9. 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…

  10. 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…

  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. 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)

  13. Estimating surface turbulent heat fluxes from land surface temperature and soil moisture using the particle batch smoother

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Dong, Jianzhi; Steele-Dunne, Susan; van de Giesen, Nick

    2016-04-01

    This study is focused on estimating surface sensible and latent heat fluxes from land surface temperature (LST) time series and soil moisture observations. Surface turbulent heat fluxes interact with the overlying atmosphere and play a crucial role in meteorology, hydrology and other climate-related fields, but in-situ measurements are costly and difficult. It has been demonstrated that the time series of LST contains information of energy partitioning and that surface turbulent heat fluxes can be determined from assimilation of LST. These studies are mainly based on two assumptions: (1) a monthly value of bulk heat transfer coefficient under neutral conditions (CHN) which scales the sum of the fluxes, and (2) an evaporation fraction (EF) which stays constant during the near-peak hours of the day. Previous studies have applied variational and ensemble approaches to this problem. Here the newly developed particle batch smoother (PBS) algorithm is adopted to test its capability in this application. The PBS can be seen as an extension of the standard particle filter (PF) in which the states and parameters within a fix window are updated in a batch using all observations in the window. The aim of this study is two-fold. First, the PBS is used to assimilate only LST time series into the force-restore model to estimate fluxes. Second, a simple soil water transfer scheme is introduced to evaluate the benefit of assimilating soil moisture observations simultaneously. The experiments are implemented using the First ISLSCP (International Satellite Land Surface Climatology Project) (FIFE) data. It is shown that the restored LST time series using PBS agrees very well with observations, and that assimilating LST significantly improved the flux estimation at both daily and half-hourly time scales. When soil moisture is introduced to further constrain EF, the accuracy of estimated EF is greatly improved. Furthermore, the RMSEs of retrieved fluxes are effectively reduced at both

  14. Estimation of human heat loss in five Mediterranean regions.

    PubMed

    Bilgili, M; Simsek, E; Sahin, B; Yasar, A; Ozbek, A

    2015-10-01

    This study investigates the effects of seasonal weather differences on the human body's heat losses in the Mediterranean region of Turkey. The provinces of Adana, Antakya, Osmaniye, Mersin and Antalya were chosen for the research, and monthly atmospheric temperatures, relative humidity, wind speed and atmospheric pressure data from 2007 were used. In all these provinces, radiative, convective and evaporative heat losses from the human body based on skin surface and respiration were analyzed from meteorological data by using the heat balance equation. According to the results, the rate of radiative, convective and evaporative heat losses from the human body varies considerably from season to season. In all the provinces, 90% of heat loss was caused by heat transfer from the skin, with the remaining 10% taking place through respiration. Furthermore, radiative and convective heat loss through the skin reached the highest values in the winter months at approximately between 110 and 140W/m(2), with the lowest values coming in the summer months at roughly 30-50W/m(2). PMID:26025784

  15. Estimation of the average surface heat flux over an inhomogeneous terrain from the vertical velocity variance

    NASA Technical Reports Server (NTRS)

    Eilts, M. D.; Sundara-Rajan, A.; Evans, R. J.

    1987-01-01

    An indirect method of estimating the surface heat flux from observations of vertical velocity variance at the lower mid-levels of the convective atmospheric boundary layer is described. Comparison of surface heat flux estimates with those from boundary-layer heating rates is good, and this method seems to be especially suitable for inhomogeneous terrain for which the surface-layer profile method cannot be used.

  16. 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)

  17. Combining Heat and Mass Flux Methods for Estimating Real-Time Evaporation from a Water Surface

    NASA Astrophysics Data System (ADS)

    Mathis, T. J.; Schladow, G.; Hook, S. J.

    2015-12-01

    Quantifying the heat and mass fluxes associated with evaporation from lakes and reservoirs is achallenge for hydrologists and water managers. This is in large part due to a lack of comprehensivemeasurement data for most systems, which is itself related to the inherent difficulties associated withmeasuring turbulent quantities. An alternative to direct measurement is to develop better models for theevaporative flux, based on the mean terms (as opposed to the turbulent terms) that drive evaporation.Algorithms for the evaporative heat and mass flux must reflect changes in heat storage in the system aswell as the other components of a mass balance (inflow, outflow, and precipitation). The energy budget basedapproach requires records of all the other energy fluxes across the air-water interface to separateout the latent heat component. Other approaches utilize the similarity between atmospheric velocity,temperature and humidity profiles. This study seeks to combine these approaches to build and calibrateheat flux models that can be used to accurately recreate a long-term record of mass storage changefrom a sub-set of meteorological data, lake surface temperature data, and hydrologic observations. Highfrequency lake level data are used to check that the mass balance is in fact achieved. Good agreement isshown between the heat flux methods and the mass balance results through comparison with a three-yearrecord of lake level. The results demonstrate that a combination of mass and heat flux approaches canbe used to generate accurate values of evaporation on daily or even sub-daily time-scales.

  18. Uncertainty analysis of heat flux measurements estimated using a one-dimensional, inverse heat-conduction program.

    SciTech Connect

    Nakos, James Thomas; Figueroa, Victor G.; Murphy, Jill E.

    2005-02-01

    The measurement of heat flux in hydrocarbon fuel fires (e.g., diesel or JP-8) is difficult due to high temperatures and the sooty environment. Un-cooled commercially available heat flux gages do not survive in long duration fires, and cooled gages often become covered with soot, thus changing the gage calibration. An alternate method that is rugged and relatively inexpensive is based on inverse heat conduction methods. Inverse heat-conduction methods estimate absorbed heat flux at specific material interfaces using temperature/time histories, boundary conditions, material properties, and usually an assumption of one-dimensional (1-D) heat flow. This method is commonly used at Sandia.s fire test facilities. In this report, an uncertainty analysis was performed for a specific example to quantify the effect of input parameter variations on the estimated heat flux when using the inverse heat conduction method. The approach used was to compare results from a number of cases using modified inputs to a base-case. The response of a 304 stainless-steel cylinder [about 30.5 cm (12-in.) in diameter and 0.32-cm-thick (1/8-in.)] filled with 2.5-cm-thick (1-in.) ceramic fiber insulation was examined. Input parameters of an inverse heat conduction program varied were steel-wall thickness, thermal conductivity, and volumetric heat capacity; insulation thickness, thermal conductivity, and volumetric heat capacity, temperature uncertainty, boundary conditions, temperature sampling period; and numerical inputs. One-dimensional heat transfer was assumed in all cases. Results of the analysis show that, at the maximum heat flux, the most important parameters were temperature uncertainty, steel thickness and steel volumetric heat capacity. The use of a constant thermal properties rather than temperature dependent values also made a significant difference in the resultant heat flux; therefore, temperature-dependent values should be used. As an example, several parameters were varied to

  19. Estimating interfacial thermal conductivity in metamaterials through heat flux mapping

    SciTech Connect

    Canbazoglu, Fatih M.; Vemuri, Krishna P.; Bandaru, Prabhakar R.

    2015-04-06

    The variability of the thickness as well as the thermal conductivity of interfaces in composites may significantly influence thermal transport characteristics and the notion of a metamaterial as an effective medium. The consequent modulations of the heat flux passage are analytically and experimentally examined through a non-contact methodology using radiative imaging, on a model anisotropic thermal metamaterial. It was indicated that a lower Al layer/silver interfacial epoxy ratio of ∼25 compared to that of a Al layer/alumina interfacial epoxy (of ∼39) contributes to a smaller deviation of the heat flux bending angle.

  20. Estimation of test characteristics of real-time PCR and bacterial culture for diagnosis of subclinical intramammary infections with Streptococcus agalactiae in Danish dairy cattle in 2012 using latent class analysis.

    PubMed

    Mahmmod, Yasser S; Toft, Nils; Katholm, Jørgen; Grønbæk, Carsten; Klaas, Ilka C

    2013-05-01

    The misdiagnosis of intramammary infections (IMI) with Streptococcus agalactiae (S. agalactiae) could lead farmers to treat or cull animals unnecessarily. The objective of this field study was to estimate the sensitivity (Se) and specificity (Sp) of real-time PCR at different cut-offs for cycle threshold (Ct) values against bacterial culture (BC) for diagnosis of S. agalactiae IMI using latent class analysis to avoid the assumption of a perfect reference test. A total of 614 dairy cows were randomly selected from 6 herds with bulk tank PCR Ct value ≤ 39 for S. agalactiae and S. aureus. At milk recording, 2456 quarter milk samples were taken aseptically for BC and the routinely taken cow level milk samples were analyzed by PCR. Results showed that 53 cows (8.6%) were positive for S. agalactiae IMI by BC. Sensitivity of PCR at cut-offs; ≤ 39, ≤ 37, ≤ 34, and ≤ 32, was 96.2%, 91.9%, 87.2% and 73.9%, while Se of BC was 25.7%, 29.9%, 59.9% and 72.1%. Specificity of PCR at cut-offs; ≤ 39, ≤ 37, ≤ 34, and ≤ 32, was 96.8%, 96.9%, 96.7%, and 97.22%, while Sp of BC was 99.7%, 99.5%, 99.2%, and 98.9%. The estimated prevalence of S. agalactiae IMI by PCR was higher than the apparent prevalence at the tested cut-offs, indicating under estimation of S. agalactiae IMI in the examined dairy cows. In conclusion, Se of PCR is always higher than Se of BC at all tested cut-offs. The lower cut-off, the more comparable becomes Se of PCR and Se of BC. The changes in Se in both PCR and BC at different Ct-value cut-offs may indicate a change in the definition of the latent infection. The similar Se of both tests at cut-off ≤ 32 may indicate high concentrations of S. agalactiae viable cells, representing a cow truly/heavily infected with S. agalactiae and thus easier to detect with BC. At cut-off ≤ 39 the latent definition of infection may reflect a more general condition of cows being positive for S. agalactiae. Our findings indicate that PCR Ct-value cut-offs should

  1. Multi Function Heat Pulse Probes (MFHPP) to Estimate Ground Heat Flux and Reduce Surface Energy Budget Errors

    NASA Astrophysics Data System (ADS)

    Ciocca, Francesco; Sharma, Varun; Lunati, Ivan; Parlange, Marc B.

    2013-04-01

    Ground heat flux plays a crucial role in surface energy budget: an incorrect estimation of energy storage and heat fluxes in soils occur when probes such as heat flux plates are adopted, and these mistakes can account for up to 90% of the residual variance (Higgins, GRL, 2012). A promising alternative to heat flux plates is represented by Multi Function Heat Pulse Probes (MFHPP). They have proven to be accurate in thermal properties and heat fluxes estimation (e.g. Cobos, VZJ, 2003) and can be used to monitor and quantify subsurface evaporation in field experiments (Xiao et al., VZJ, 2011). We perform a laboratory experiment with controlled temperature in a small Plexiglas column (20cm diameter and 40cm height). The column is packed with homogeneously saturated sandy soil and equipped with three MFHPPs in the upper 4cm and thermocouples and dielectric soil moisture probes deeper. This configuration allows for accurate and simultaneous ground heat flux, soil moisture and subsurface evaporation measurements. Total evaporation is monitored using a precision scale, while an infrared gun and a long wave radiometer measure the soil skin temperature and the outgoing long-short wave radiation, respectively. A fan and a heat lamp placed above the column allow to mimick on a smaller and more controlled scale the field conditions induced by the diurnal cycle. At a reference height above the column relative humidity, wind speed and air temperature are collected. Results are interpreted by means of numerical simulations performed with an ad-hoc-developed numerical model that simulates coupled heat and moisture transfer in soils and is used to match and interpolate the temperature and soil moisture values got at finite depths within the column. Ground heat fluxes are then estimated by integrating over almost continuous, numerically simulated temperature profiles, which avoids errors due to use of discrete data (Lunati et al., WRR, 2012) and leads to a more reliable estimate of

  2. Estimation of the heat capacity of CdTe semiconductor

    NASA Astrophysics Data System (ADS)

    Koç, Hüseyin; Eser, Erhan

    2016-01-01

    The aim of this paper is to provide a simple and reliable analytical expression for the thermodynamic properties calculated in terms of the Debye model using the binomial coefficient, and examine specific heat capacity of CdTe in the 300-1400 K temperature range. The obtained results have been compared with the corresponding experimental and theoretical results. The calculated results are in good agreement with the other results over the entire temperature range.

  3. Estimating Heat and Mass Transfer Processes in Green Roof Systems: Current Modeling Capabilities and Limitations (Presentation)

    SciTech Connect

    Tabares Velasco, P. C.

    2011-04-01

    This presentation discusses estimating heat and mass transfer processes in green roof systems: current modeling capabilities and limitations. Green roofs are 'specialized roofing systems that support vegetation growth on rooftops.'

  4. Estimation of boundary heat flux using experimental temperature data in turbulent forced convection flow

    NASA Astrophysics Data System (ADS)

    Parwani, Ajit K.; Talukdar, Prabal; Subbarao, P. M. V.

    2014-09-01

    Heat flux at the boundary of a duct is estimated using the inverse technique based on conjugate gradient method (CGM) with an adjoint equation. A two-dimensional inverse forced convection hydrodynamically fully developed turbulent flow is considered. The simulations are performed with temperature data measured in the experimental test performed on a wind tunnel. The results show that the present numerical model with CGM is robust and accurate enough to estimate the strength and position of boundary heat flux.

  5. Estimation of boundary heat flux using experimental temperature data in turbulent forced convection flow

    NASA Astrophysics Data System (ADS)

    Parwani, Ajit K.; Talukdar, Prabal; Subbarao, P. M. V.

    2015-03-01

    Heat flux at the boundary of a duct is estimated using the inverse technique based on conjugate gradient method (CGM) with an adjoint equation. A two-dimensional inverse forced convection hydrodynamically fully developed turbulent flow is considered. The simulations are performed with temperature data measured in the experimental test performed on a wind tunnel. The results show that the present numerical model with CGM is robust and accurate enough to estimate the strength and position of boundary heat flux.

  6. Toward a Quantitative Estimate of Future Heat Wave Mortality under Global Climate Change

    PubMed Central

    Peng, Roger D.; Bobb, Jennifer F.; Tebaldi, Claudia; McDaniel, Larry; Bell, Michelle L.; Dominici, Francesca

    2011-01-01

    Background Climate change is anticipated to affect human health by changing the distribution of known risk factors. Heat waves have had debilitating effects on human mortality, and global climate models predict an increase in the frequency and severity of heat waves. The extent to which climate change will harm human health through changes in the distribution of heat waves and the sources of uncertainty in estimating these effects have not been studied extensively. Objectives We estimated the future excess mortality attributable to heat waves under global climate change for a major U.S. city. Methods We used a database comprising daily data from 1987 through 2005 on mortality from all nonaccidental causes, ambient levels of particulate matter and ozone, temperature, and dew point temperature for the city of Chicago, Illinois. We estimated the associations between heat waves and mortality in Chicago using Poisson regression models. Results Under three different climate change scenarios for 2081–2100 and in the absence of adaptation, the city of Chicago could experience between 166 and 2,217 excess deaths per year attributable to heat waves, based on estimates from seven global climate models. We noted considerable variability in the projections of annual heat wave mortality; the largest source of variation was the choice of climate model. Conclusions The impact of future heat waves on human health will likely be profound, and significant gains can be expected by lowering future carbon dioxide emissions. PMID:21193384

  7. Importance of Salinity Measurements in the Heat Storage Estimation from Topex/Poseidon

    NASA Technical Reports Server (NTRS)

    Sato, O.; Polito, P.; Liu, W.

    1999-01-01

    Sea surface height anomaly signals from satellite altimeter data are used to estimate heat storage. Since variability in sea surface height is mostly due to expansion and contraction of the water column it can be correlated with variations in the heat and salt content.

  8. Sensible heat balance estimates of transient soil ice contents for freezing and thawing conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil ice content is an important component for winter soil hydrology. The sensible heat balance (SHB) method using measurements from heat pulse probes (HPP) is a possible way to determine transient soil ice content. In a previous study, in situ soil ice contents estimates with the SHB method were in...

  9. Best estimate radiation heat transfer model developed for TRAC-BD1

    SciTech Connect

    Spore, J.W.; Giles, M.M.; Shumway, R.W.

    1981-01-01

    A best estimate radiation heat transfer model for analysis of BWR fuel bundles has been developed and compared with 8 x 8 fuel bundle data. The model includes surface-to-surface and surface-to-two-phase fluid radiation heat transfer. A simple method of correcting for anisotropic reflection effects has been included in the model.

  10. Estimation of Surface Heat Flux and Surface Temperature during Inverse Heat Conduction under Varying Spray Parameters and Sample Initial Temperature

    PubMed Central

    Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong

    2014-01-01

    An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface heat flux, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface heat flux and surface temperature. Inlet pressure has a positive effect on surface heat flux (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface heat flux as high as 0.4024 MW/m2 was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface heat flux and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface heat flux and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa. PMID:24977219

  11. Estimation of surface heat flux and surface temperature during inverse heat conduction under varying spray parameters and sample initial temperature.

    PubMed

    Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong; Zubair, Muhammad

    2014-01-01

    An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface heat flux, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface heat flux and surface temperature. Inlet pressure has a positive effect on surface heat flux (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface heat flux as high as 0.4024 MW/m(2) was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface heat flux and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface heat flux and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa. PMID:24977219

  12. 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

  13. Combined parameter and function estimation in heat transfer with application to contact conductance

    NASA Astrophysics Data System (ADS)

    Beck, J. V.

    1988-11-01

    This paper discusses parameter estimation, function estimation, and a combination of the two. An example of parameter estimation is the determination of thermal conductivity of solids from transient temperature measurements. An example of function estimation is the inverse heat conduction problem, which uses transient temperature measurements to determine the surface heat flux history. The examples used herein involve the determination of the thermal contact conductance. Two sets of very good data are analyzed. One set of steady-state data was obtained by Antonetti and Eid (1987). The other set was obtained by Moses and Johnson (1986) under transient conditions for periodic contact. Both sets of data are used to illustrate parameter, function, and combined estimation. It is demonstrated that the proposed methods are more powerful then commonly accepted methods. Many other heat transfer problems can be treated using the proposed techniques.

  14. Estimation of Surface Temperature and Heat Flux by Inverse Heat Transfer Methods Using Internal Temperatures Measured While Radiantly Heating a Carbon/Carbon Specimen up to 1920 F

    NASA Technical Reports Server (NTRS)

    Pizzo, Michelle; Daryabeigi, Kamran; Glass, David

    2015-01-01

    The ability to solve the heat conduction equation is needed when designing materials to be used on vehicles exposed to extremely high temperatures; e.g. vehicles used for atmospheric entry or hypersonic flight. When using test and flight data, computational methods such as finite difference schemes may be used to solve for both the direct heat conduction problem, i.e., solving between internal temperature measurements, and the inverse heat conduction problem, i.e., using the direct solution to march forward in space to the surface of the material to estimate both surface temperature and heat flux. The completed research first discusses the methods used in developing a computational code to solve both the direct and inverse heat transfer problems using one dimensional, centered, implicit finite volume schemes and one dimensional, centered, explicit space marching techniques. The developed code assumed the boundary conditions to be specified time varying temperatures and also considered temperature dependent thermal properties. The completed research then discusses the results of analyzing temperature data measured while radiantly heating a carbon/carbon specimen up to 1920 F. The temperature was measured using thermocouple (TC) plugs (small carbon/carbon material specimens) with four embedded TC plugs inserted into the larger carbon/carbon specimen. The purpose of analyzing the test data was to estimate the surface heat flux and temperature values from the internal temperature measurements using direct and inverse heat transfer methods, thus aiding in the thermal and structural design and analysis of high temperature vehicles.

  15. Elastic thickness and heat flux estimates for the uranian satellite Ariel

    NASA Astrophysics Data System (ADS)

    Peterson, G.; Nimmo, F.; Schenk, P.

    2015-04-01

    The surface of Ariel, an icy satellite orbiting Uranus, shows extensional tectonic features suggesting an episode of endogenic heating in the satellite's past. Using topography derived from stereo-photoclinometry, we identified flexural uplift at a rift zone suggesting elastic thickness values in the range 3.8-4.4 km. We estimate the temperature at the base of the lithosphere to be in the range 99-146 K, depending on the strain rate assumed, with corresponding heat fluxes of 28-92 mW/m2. Neither tidal heating, assuming Ariel's current eccentricity, nor radiogenic heat production from the silicate core are enough to cause the inferred heat fluxes. None of three proposed ancient mean-motion resonances produce equilibrium tidal heating values in excess of 4.3 mW/m2. Thus, the origin of the inferred high heat fluxes is currently mysterious.

  16. Geothermal hydrothermal direct heat use: US market size and market penetration estimates

    SciTech Connect

    El Sawy, A.H.; Entingh, D.J.

    1980-09-01

    This study estimates the future regional and national market penetration path of hydrothermal geothermal direct heat applications in the United States. A Technology Substitution Model (MARPEN) is developed and used to estimate the energy market shares captured by low-temperature (50 to 150/sup 0/C) hydrothermal geothermal energy systems over the period 1985 to 2020. The sensitivity of hydrothermal direct heat market shares to various government hydrothermal commercialization policies is examined. Several substantive recommendations to help accelerate commercialization of geothermal direct heat utilization in the United States are indicated and possible additional analyses are discussed.

  17. 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…

  18. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil heat flux (G) is one of the terms required for estimating evapotranspiration (ET) rates using an energy balance. Numerous reflectance-based models are available in the literature for estimating G fluxes. However, these models have shown wide variation in their performance. Therefore, operationa...

  20. Estimation of the Relationship Between Remotely Sensed Anthropogenic Heat Discharge and Building Energy Use

    NASA Technical Reports Server (NTRS)

    Zhou, Yuyu; Weng, Qihao; Gurney, Kevin R.; Shuai, Yanmin; Hu, Xuefei

    2012-01-01

    This paper examined the relationship between remotely sensed anthropogenic heat discharge and energy use from residential and commercial buildings across multiple scales in the city of Indianapolis, Indiana, USA. The anthropogenic heat discharge was estimated with a remote sensing-based surface energy balance model, which was parameterized using land cover, land surface temperature, albedo, and meteorological data. The building energy use was estimated using a GIS-based building energy simulation model in conjunction with Department of Energy/Energy Information Administration survey data, the Assessor's parcel data, GIS floor areas data, and remote sensing-derived building height data. The spatial patterns of anthropogenic heat discharge and energy use from residential and commercial buildings were analyzed and compared. Quantitative relationships were evaluated across multiple scales from pixel aggregation to census block. The results indicate that anthropogenic heat discharge is consistent with building energy use in terms of the spatial pattern, and that building energy use accounts for a significant fraction of anthropogenic heat discharge. The research also implies that the relationship between anthropogenic heat discharge and building energy use is scale-dependent. The simultaneous estimation of anthropogenic heat discharge and building energy use via two independent methods improves the understanding of the surface energy balance in an urban landscape. The anthropogenic heat discharge derived from remote sensing and meteorological data may be able to serve as a spatial distribution proxy for spatially-resolved building energy use, and even for fossil-fuel CO2 emissions if additional factors are considered.

  1. RF-sheath heat flux estimates on Tore Supra and JET ICRF antennae. Extrapolation to ITER

    SciTech Connect

    Colas, L.; Portafaix, C.; Goniche, M.; Jacquet, Ph.

    2009-11-26

    RF-sheath induced heat loads are identified from infrared thermography measurements on Tore Supra ITER-like prototype and JET A2 antennae, and are quantified by fitting thermal calculations. Using a simple scaling law assessed experimentally, the estimated heat fluxes are then extrapolated to the ITER ICRF launcher delivering 20 MW RF power for several plasma scenarios. Parallel heat fluxes up to 6.7 MW/m{sup 2} are expected very locally on ITER antenna front face. The role of edge density on operation is stressed as a trade-off between easy RF coupling and reasonable heat loads. Sources of uncertainty on the results are identified.

  2. Estimates of land surface heat fluxes of the Mt. Everest region over the Tibetan Plateau utilizing ASTER data

    NASA Astrophysics Data System (ADS)

    Han, Cunbo; Ma, Yaoming; Chen, Xuelong; Su, Zhongbo

    2016-02-01

    Regional land surface albedo, land surface temperature, net radiation flux, ground heat flux, sensible heat flux, and latent heat flux were derived in the Mt. Everest area utilizing topographical enhanced surface energy balance system (TESEBS) model and nine scenes of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data under clear-sky and in-situ measurements at the QOMS station (the Qomolangma Station for Atmospheric Environmental Observation and Research, Chinese Academy of Sciences). The parameterization schemes for diffused and reflected downward shortwave radiation flux of the TESEBS model were improved by introducing the parameters sky-view factor (SVF) and terrain configuration factor (Ct). Then, a so-called C-correction method for land surface albedo was coupled into the TESEBS model to reduce the influences of topography. After topographical correction, the albedo of the dark tilted surface facing away from the Sun was compensated and albedo of the brightness surface facing the Sun was restrained. The downward shortwave radiation flux was broken down into three components including solar direct radiation flux, solar diffused radiation flux, and reflected solar radiation flux by surrounding terrain. The solar diffused radiation flux ranges from about 30 to 60 W/m2 at the satellite passing time on 6 January 2008. The reflected solar radiation flux changes from 0 to more than 100 W/m2 in the area covered by glaciers and snows. Thus, it is important to take the topographical effects into account in estimation of surface radiation balance in the mountainous area, especially in the glacier area. The retrieved land surface parameters, land surface radiation balance components, and the land surface energy balance components were evaluated by the field measurements in the QOMS station. The estimated results were very close to the in-situ observations with low mean bias errors, low root mean square errors and high correlation coefficients

  3. Utilizing thermal isostasy to estimate sub-lithospheric heat flow and anomalous crustal radioactivity

    NASA Astrophysics Data System (ADS)

    Hasterok, D.; Gard, M.

    2016-09-01

    While surface heat flow relates to the heat loss through the lithosphere, it can be difficult to quantify and separate the heat produced internally through radiogenic decay from the heat transferred across the base of the lithosphere by mantle convection. In this study, we apply a thermo-isostatic analysis to Australia and estimate the sub-lithospheric and radiogenic heat flow components by employing a simple 1-D conservation of energy model. We estimate an anomalous radiogenic heat production across much of eastern Australia generally accounting for >50 mW m-2, while western Australia appears to have high crustal compositionally corrected elevation, possibly related to chemical buoyancy of the mantle lithosphere. A moderately high sub-lithospheric heat flow (∼40 mW m-2) along the eastern and southeastern coast, including Tasmania, is coincident with locations of Cenozoic volcanism and supports an edge-driven convection hypothesis. However, the pattern of sub-lithospheric heat flow along the margin does not support the existence of hotspot tracks. Thermo-isostatic models such as these improve our ability to identify and quantify crustal from mantle sources of heat loss and add valuable constraints on tectonic and geodynamic models of the continental lithosphere's physical state and evolution.

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

    SciTech Connect

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

    1993-12-01

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

  5. Estimating Risks of Heat Strain by Age and Sex: A Population-Level Simulation Model

    PubMed Central

    Glass, Kathryn; Tait, Peter W.; Hanna, Elizabeth G.; Dear, Keith

    2015-01-01

    Individuals living in hot climates face health risks from hyperthermia due to excessive heat. Heat strain is influenced by weather exposure and by individual characteristics such as age, sex, body size, and occupation. To explore the population-level drivers of heat strain, we developed a simulation model that scales up individual risks of heat storage (estimated using Myrup and Morgan’s man model “MANMO”) to a large population. Using Australian weather data, we identify high-risk weather conditions together with individual characteristics that increase the risk of heat stress under these conditions. The model identifies elevated risks in children and the elderly, with females aged 75 and older those most likely to experience heat strain. Risk of heat strain in males does not increase as rapidly with age, but is greatest on hot days with high solar radiation. Although cloudy days are less dangerous for the wider population, older women still have an elevated risk of heat strain on hot cloudy days or when indoors during high temperatures. Simulation models provide a valuable method for exploring population level risks of heat strain, and a tool for evaluating public health and other government policy interventions. PMID:25993102

  6. The validation of the robust input estimation approach to two-dimensional inverse heat conduction problems

    SciTech Connect

    Tuan, P.C.; Ju, M.C.

    2000-03-01

    A novel adaptive and robust input estimation inverse methodology of estimating the time-varying unknown heat flux, named as the input, on the two active boundaries of a 2-D inverse heat conduction problem is presented. The algorithm includes using the Kalman filter to propose a regression model between the residual innovation and the two thermal unknown boundaries flux through given 2-D heat conduction state-space models and noisy measurement sequence. Based on this regression equation, a recursive least-square estimator (RLSE) weighted by the forgetting factor is proposed to on-line estimate these unknowns. The adaptive and robust weighting technique is essential since unknowns input are time-varied and have unpredictable changing status. In this article, the authors provide the bandwidth analysis together with bias and variance tests to construct an efficient and robust forgetting factor as the ratio between the standard deviation of measurement and observable bias innovation at each time step. Herein, the unknowns are robustly and adaptively estimated under the system involving measurement noise, process error, and unpredictable change status of time-varying unknowns. The capabilities of the proposed algorithm are demonstrated through the comparison with the conventional input estimation algorithm and validated by two benchmark performance tests in 2-D cases. Results show that the proposed algorithm not only exhibits superior robust capability but also enhances the estimation performance and highly facilitates practical implementation.

  7. Fundamental mechanisms that influence the estimate of heat transfer to gas turbine blades

    NASA Technical Reports Server (NTRS)

    Graham, R. W.

    1979-01-01

    Estimates of the heat transfer from the gas to stationary (vanes) or rotating blades poses a major uncertainty due to the complexity of the heat transfer processes. The gas flow through these blade rows is three dimensional with complex secondary viscous flow patterns that interact with the endwalls and blade surfaces. In addition, upstream disturbances, stagnation flow, curvature effects, and flow acceleration complicate the thermal transport mechanisms in the boundary layers. Some of these fundamental heat transfer effects are discussed. The chief purpose of the discussion is to acquaint those in the heat transfer community, not directly involved in gas turbines, of the seriousness of the problem and to recommend some basic research that would improve the capability for predicting gas-side heat transfer on turbine blades and vanes.

  8. A FIDAP and an empirical estimate of conjugate heat transfer of a graphite crucible

    SciTech Connect

    Bateman, K.J.; Clarksean, R.L.

    1995-05-01

    A set of thermal analyses has been conducted to conservatively predict the heat transfer of a graphite crucible. The study used conjugate heat transfer to determine the cooling characteristics of a graphite crucible. Natural convection and conduction through the casting charge and the graphite crucible are examined. All of the analyses were conducted in non-dimensional form up to a Rayleigh number of 1 x 10{sup 8}. The parametric study examined the effect of increasing the internal heat generation of the casting charge. Data derived from an empirical estimate are compared to the FIDAP simulations. The two models are found to have good correlation.

  9. Estimation of the relationship between remotely sensed anthropogenic heat discharge and building energy use

    SciTech Connect

    Zhou, Yuyu; Weng, Qihao; Gurney, Kevin R.; Shuai, Yanmin; Hu, Xuefei

    2012-01-01

    This paper examined the relationship between remotely sensed anthropogenic heat discharge and energy use from residential and commercial buildings across multiple scales in the city of Indianapolis, Indiana, USA. Anthropogenic heat discharge was estimated based on a remote sensing-based surface energy balance model, which was parameterized using land cover, land surface temperature, albedo, and meteorological data. Building energy use was estimated using a GIS-based building energy simulation model in conjunction with Department of Energy/ Energy Information Administration survey data, Assessor's parcel data, GIS floor areas data, and remote sensing-derived building height data.

  10. An estimate of the heat flow on the Meteor Rise, subantarctic South Atlantic

    SciTech Connect

    Nobes, D.C. ); Mienert, J. ); Mwenifumbo, C.J. )

    1991-04-10

    Heat flow determinations require more than one reliable temperature measurment to obtain an estimate of the temperature gradient, and subsequently the heat flow. Two temperature readings were taken on leg 114 of the Ocean Drilling Program, both in hole 704B on the Meteor Rise in the subantarctic South Atlantic. One of these readings appears to be reliable, but the other appears to be invalid. Because any temperature gradient and estimate of heat flow derived using these two readings will be questionable, the authors suggest a different approach to determine heat flow. They use the one reliable temperature measurement to calibrate the temperature derived from the induction resistivity log and the laboratory porosity measurements. The temperature and heat flow depend on the shape factor used in the modified Archie's law. The temperature gradient empirically obtained from the resistivity and porosity is 38 {plus minus} mK/m and the average heat flow is 64 {plus minus} 8 mW/m{sup 2}, which is consistent with the age of the Meteor Rise (approximately 60 to 65 Ma). These values are in agreement with the computed heat flow when they assume a simple linear temperature gradient through the sediment section.

  11. Respiratory heat loss in the sheep: a comprehensive model

    NASA Astrophysics Data System (ADS)

    Gomes da Silva, Roberto; LaScala, Newton; Lima Filho, Alvaro Edison; Catharin, Marcelo Carlos

    2002-06-01

    A model is presented for the respiratory heat loss in sheep, considering both the sensible heat lost by convection (CR) and the latent heat eliminated by evaporation (ER). A practical method is described for the estimation of the tidal volume as a function of the respiratory rate. Equations for CR and ER are developed and the relative importance of both heat transfer mechanisms is discussed. At air temperatures up to 30 °C sheep have the least respiratory heat loss at air vapour pressures above 1.6 kPa. At an ambient temperature of 40 °C respiratory loss of sensible heat can be nil; for higher temperatures the transfer by convection is negative and thus heat is gained. Convection is a mechanism of minor importance for the respiratory heat transfer in sheep at environmental temperatures above 30 °C. These observations show the importance of respiratory latent heat loss for thermoregulation of sheep in hot climates.

  12. Heat as a tracer to estimate dissolved organic carbon flux from a restored wetland

    USGS Publications Warehouse

    Burow, K.R.; Constantz, J.; Fujii, R.

    2005-01-01

    Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch. Copyright ?? 2005 National Ground Water Association.

  13. Numerical estimation of heat transfer characteristics for two-row plate-finned tube heat exchangers with experimental data

    NASA Astrophysics Data System (ADS)

    Chen, Han-Taw; Lu, Chih-Han; Huang, Yao-Sheng; Liu, Kuo-Chi

    2016-05-01

    This study applies a three-dimensional computational fluid dynamics commercial software in conjunction with various flow models to estimate the heat transfer and fluid flow characteristics of the two-row plate-finned tube heat exchanger in staggered arrangement. The effect of air speed and fin spacing on the results obtained is investigated. Temperature and velocity distributions of air between the two fins and heat transfer coefficient on the fins are determined using the laminar flow and RNG k-ɛ turbulence models. More accurate results can be obtained, if the heat transfer coefficient obtained is close to the inverse results and matches existing correlations. Furthermore, the fin temperature measured at the selected locations also coincides with the experimental temperature data. The results obtained using the RNG k-ɛ turbulence model are more accurate than those using the laminar flow model. An interesting finding is the number of grid points may also need to change with fin spacing and air speed.

  14. Elastic thickness and heat flux estimates for the Uranian satellite Ariel

    NASA Astrophysics Data System (ADS)

    Peterson, G.; Nimmo, F.; Schenk, P.

    2013-12-01

    The exterior of Ariel, an icy satellite orbiting Uranus, shows tectonic features suggesting an episode of endogenic heating in the satellite's past [1]. Using topography derived from stereo images, we identified flexural uplift at two different rift zones. The elastic thickness is estimated using the wavelength of the deformation [2], yielding elastic thickness values of 2-4 km for the first region and 5-8 km for the second region. Using creep parameters for ice [3] and the approach of [4], we estimate the temperature at the base of the lithosphere to be in the range 110 to 140 K, depending on the strain rate assumed. The corresponding heat fluxes are 40-120 mW/m^2 and 20-50 mW/m^2, respectively. Neither tidal heating assuming Ariel's current eccentricity nor radiogenic heat production from the silicate core are enough to cause the inferred heat flux. Unstable resonant configurations of the Uranian satellites may have occurred in the past [5], including a 2:1 mean-motion resonance between Ariel and Umbriel. This resonance would have generated a higher eccentricity, possibly explaining the endogenic heat source. However, the maximum equilibrium heating rate in Ariel due to this resonance [1] is 2.9 GW (0.6 mW/m2), inadequate to cause the inferred heat flux. The origin of the inferred high heat fluxes is thus currently mysterious. [1] Peale 1999 [2] Turcotte and Schubert 2002 [3] Goldsby and Kohlstedt 2001 [4] Nimmo et al. 2002 [5] Dermott et al. 1988

  15. Shallow subsurface temperatures and some estimates of heat flow from the Colorado Plateau of northeastern Arizona

    SciTech Connect

    Sass, J.H.; Stone, C.; Bills, D.J.

    1982-01-01

    Temperature data to depths of a few hundred meters were obtained from 29 wells in northeastern Arizona; 12 in the region surrounding the San Francisco Volcanic Field, 8 in the Black Mesa area, and 9 in the south-central Colorado Plateau which includes the White Mountains. Although there was evidence for local hydrologic disturbances in many temperature profiles, most wells provided an estimate of the conductive thermal gradient at the site. A few thermal conductivities were measured and were combined with published regional averages for the north-central part of the Colorado Plateau to produce crude estimates of regional heat flux. None of the wells was accessible below the regional aquifers. To these depths, heat flow in the area of the San Francisco Volcanic Field appears to be controlled primarily by regional lateral water movement having a significant downward vertical component of velocity. The mean heat flow of 27 +- 5 mWm/sup -2/ is only a third to a quarter of what we would expect in this tectonic setting. The heat that is being carried laterally and downward probably is being discharged at low enthalpy and low elevation in springs and streams of the Colorado Plateau and Mogollon Rim. In the vicinity of Black Mesa, heat-flow averages about 60 mWm/sup -2/, characteristics of the coal interior of the Colorado Plateau. North of the White Mountain Volcanic Field, the average heat flow is about 95 mWm/sup -2/.

  16. ESTIMATION OF HRW WHEAT HEAT DAMAGE BY DSC, CAPILLARY ZONE ELECTROPHORESIS, PHOTOACOUSTIC SPECTROSCOPY AND RHEOMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of heat damage was estimated using Hard Red Winter (HRW) wheat varieties grown in Oklahoma. The testing was done on wheat kernels, flour, and isolated starch. Whole-wheat kernels were analyzed by Photoacoustic Spectroscopy (PAS). Flour was analyzed by DSC, Capillary Electrophoresis (CE...

  17. Heat flux estimates from the Gakkel Ridge 85E vent field from the AGAVE 2007 expedition

    NASA Astrophysics Data System (ADS)

    Stranne, C.; Winsor, P.; Sohn, R. A.; Liljebladh, B.

    2009-04-01

    During the Arctic Gakkel Vents Expedition (AGAVE) 2007, abundant hydrothermal venting was discovered on the Gakkel Ridge at 85E. Hydrothermal vents on the sea floor give rise to buoyant plumes which, when reaching neutral buoyancy, spreads horizontally over areas with length scales on the order of several kilometres and are therefore easily detected with a CTD rosette. The detected anomalies are consistent with the findings 6 years earlier during the Arctic Mid-Ocean Ridge Expedition (AMORE) 2001. The horizontal and vertical distribution of the anomalies is considered in order to establish the number of individual plumes detected. The objective of this paper is to estimate the minimum heat input required to reproduce the observed plumes, using a turbulent entrainment model. The model was run with a large number of combinations of boundary conditions (nozzle area, vertical velocity and temperature) in order to see which combinations that give rise to the observed plume characteristics (level of neutral buoyancy and temperature anomaly). For each individual plume, we estimate the minimum heat flux required to obtain the observed temperature anomaly. Adding the minimum heat flux from each vent together, the total heat flux for the vent field is estimated to be ~ 2 GW. The estimated value is comparable or larger than any other known vent field.

  18. Estimation of anthropogenic heat emission over South Korea using a statistical regression method

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Hyun; Kim, Soon-Tae

    2015-05-01

    Anthropogenic heating by human activity is one of the key contributing factors in forming urban heat islands, thus inclusion of the heat source plays an important role in urban meteorological and environmental modeling. In this study, gridded anthropogenic heat flux (AHF) with high spatial (1-km) and temporal (1-hr) resolution is estimated for the whole South Korea region in year 2010 using a statistical regression method which derives based on similarity of anthropogenic air pollutant emissions and AHF in their emission inventories. The bottom-up anthropogenic pollutant emissions required for the regression method are produced using the intensive Korean air pollutants emission inventories. The calculated regression-based AHF compares well with the inventory-based AHF estimation for the Gyeong-In region, demonstrating that the statistical regression method can reasonably represent spatio-temporal variation of the AHF within the region. The estimated AHF shows that for major Korean cities (Seoul, Busan, Daegu, Gwangju, Daejeon, and Ulsan) the annual mean AHF range 10-50 Wm-2 on a grid scale and 20-30W m-2 on a city-scale. The winter AHF are larger by about 22% than that in summer, while the weekday AHF are larger by 4-5% than the weekend AHF in the major Korean cities. The gridded AHF data estimated in this study can be used in mesoscale meteorological and environmental modeling for the South Korea region.

  19. 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…

  20. 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…

  1. 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…

  2. Probabilistic approach for decay heat uncertainty estimation using URANIE platform and MENDEL depletion code

    NASA Astrophysics Data System (ADS)

    Tsilanizara, A.; Gilardi, N.; Huynh, T. D.; Jouanne, C.; Lahaye, S.; Martinez, J. M.; Diop, C. M.

    2014-06-01

    The knowledge of the decay heat quantity and the associated uncertainties are important issues for the safety of nuclear facilities. Many codes are available to estimate the decay heat. ORIGEN, FISPACT, DARWIN/PEPIN2 are part of them. MENDEL is a new depletion code developed at CEA, with new software architecture, devoted to the calculation of physical quantities related to fuel cycle studies, in particular decay heat. The purpose of this paper is to present a probabilistic approach to assess decay heat uncertainty due to the decay data uncertainties from nuclear data evaluation like JEFF-3.1.1 or ENDF/B-VII.1. This probabilistic approach is based both on MENDEL code and URANIE software which is a CEA uncertainty analysis platform. As preliminary applications, single thermal fission of uranium 235, plutonium 239 and PWR UOx spent fuel cell are investigated.

  3. How to estimate the heat production of a 'hidden' reservoir in Earth's mantle

    NASA Astrophysics Data System (ADS)

    Korenaga, J.

    2008-12-01

    The possibility of a hidden geochemical reservoir in the deep mantle has long been debated in geophysics and geochemistry, because of its bearings on the structure of the core-mantle boundary region, the origin of hotspots, the style of mantle convection, the history of the geomagnetic field, and the thermal evolution of Earth. The geochemical nature of a hidden reservoir, however, has been estimated based on composition models for the bulk silicate Earth, although these models preclude, in principle, the presence of such reservoir. Here we present a new self-consistent framework to estimate the neodymium and samarium concentration of a hidden reservoir and also constrain the heat production of the bulk silicate Earth, based on the notion of early global differentiation. Our geochemical inference is formulated as a nonlinear inverse problem, and the permissible solution space, delineated by Markov chain Monte Carlo simulations, indicates that an early enriched reservoir may occupy ~13% of the mantle with internal heat production of ~6~TW. If a hidden reservoir corresponds to the D" layer instead, its heat production would be only ~4~TW. The heat production of the bulk silicate Earth is estimated to be 18.9±3.8~TW, which is virtually independent of the likely reservoir size.

  4. A novel cortical thickness estimation method based on volumetric Laplace-Beltrami operator and heat kernel.

    PubMed

    Wang, Gang; Zhang, Xiaofeng; Su, Qingtang; Shi, Jie; Caselli, Richard J; Wang, Yalin

    2015-05-01

    Cortical thickness estimation in magnetic resonance imaging (MRI) is an important technique for research on brain development and neurodegenerative diseases. This paper presents a heat kernel based cortical thickness estimation algorithm, which is driven by the graph spectrum and the heat kernel theory, to capture the gray matter geometry information from the in vivo brain magnetic resonance (MR) images. First, we construct a tetrahedral mesh that matches the MR images and reflects the inherent geometric characteristics. Second, the harmonic field is computed by the volumetric Laplace-Beltrami operator and the direction of the steamline is obtained by tracing the maximum heat transfer probability based on the heat kernel diffusion. Thereby we can calculate the cortical thickness information between the point on the pial and white matter surfaces. The new method relies on intrinsic brain geometry structure and the computation is robust and accurate. To validate our algorithm, we apply it to study the thickness differences associated with Alzheimer's disease (AD) and mild cognitive impairment (MCI) on the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset. Our preliminary experimental results on 151 subjects (51 AD, 45 MCI, 55 controls) show that the new algorithm may successfully detect statistically significant difference among patients of AD, MCI and healthy control subjects. Our computational framework is efficient and very general. It has the potential to be used for thickness estimation on any biological structures with clearly defined inner and outer surfaces. PMID:25700360

  5. A Novel Cortical Thickness Estimation Method based on Volumetric Laplace-Beltrami Operator and Heat Kernel

    PubMed Central

    Wang, Gang; Zhang, Xiaofeng; Su, Qingtang; Shi, Jie; Caselli, Richard J.; Wang, Yalin

    2015-01-01

    Cortical thickness estimation in magnetic resonance imaging (MRI) is an important technique for research on brain development and neurodegenerative diseases. This paper presents a heat kernel based cortical thickness estimation algorithm, which is driven by the graph spectrum and the heat kernel theory, to capture the grey matter geometry information from the in vivo brain magnetic resonance (MR) images. First, we construct a tetrahedral mesh that matches the MR images and reflects the inherent geometric characteristics. Second, the harmonic field is computed by the volumetric Laplace-Beltrami operator and the direction of the steamline is obtained by tracing the maximum heat transfer probability based on the heat kernel diffusion. Thereby we can calculate the cortical thickness information between the point on the pial and white matter surfaces. The new method relies on intrinsic brain geometry structure and the computation is robust and accurate. To validate our algorithm, we apply it to study the thickness differences associated with Alzheimer’s disease (AD) and mild cognitive impairment (MCI) on the Alzheimer’s Disease Neuroimaging Initiative (ADNI) dataset. Our preliminary experimental results on 151 subjects (51 AD, 45 MCI, 55 controls) show that the new algorithm may successfully detect statistically significant difference among patients of AD, MCI and healthy control subjects. Our computational framework is efficient and very general. It has the potential to be used for thickness estimation on any biological structures with clearly defined inner and outer surfaces. PMID:25700360

  6. Estimation of the standard molal heat capacities, entropies and volumes of 2:1 clay minerals

    NASA Astrophysics Data System (ADS)

    Ransom, Barbara; Helgeson, Harold C.

    1994-11-01

    The dearth of accurate values of the thermodynamic properties of 2:1 clay minerals severely hampers interpretation of their phase relations, the design of critical laboratory experiments and geologically realistic computer calculations of mass transfer in weathering, diagenetic and hydrothermal systems. Algorithms and strategies are described below for estimating to within 2% the standard molal heat capacities, entropies, and volumes of illites, smectites and other 2:1 clay minerals. These techniques can also be used to estimate standard molal thermodynamic properties of fictive endmembers of clay mineral solid solutions. Because 2:1 clay minerals like smectite and vermiculite are always hydrated to some extent in nature, contribution of interlayer H 2O to their thermodynamic properties is considered explicitly in the estimation of the standard molal heat capacities, entropies, and volumes of these minerals. Owing to the lack of accurate calorimetric data from which reliable values of the standard molal heat capacity and entropy of interlayer H 2O can be retrieved, these properties were taken in a first approximation to be equal to those of zeolitic H 2O in analcite. The resulting thermodynamic contributions per mole of interlayer H 2O to the standard molal heat capacity, entropy, and volume of hydrous clay minerals at 1 bar and 25°C are 11.46 cal mol -1, 13.15 cal mol -1 K -1 and 17.22 cm 3 mol, respectively. Estimated standard molal heat capacities, entropies and volumes are given for a suite of smectites and illites commonly used in models of clay mineral and shale diagenesis.

  7. Estimating the burden of heat illness in England during the 2013 summer heatwave using syndromic surveillance

    PubMed Central

    Smith, Sue; Elliot, Alex J; Hajat, Shakoor; Bone, Angie; Smith, Gillian E; Kovats, Sari

    2016-01-01

    Background The burden of heat illness on health systems is not well described in the UK. Although the UK generally experiences mild summers, the frequency and intensity of hot weather is likely to increase due to climate change, particularly in Southern England. We investigated the impact of the moderate heatwave in 2013 on primary care and emergency department (ED) visits using syndromic surveillance data in England. Methods General practitioner in hours (GPIH), GP out of hours (GPOOH) and ED syndromic surveillance systems were used to monitor the health impact of heat/sun stroke symptoms (heat illness). Data were stratified by age group and compared between heatwave and non-heatwave years. Incidence rate ratios were calculated for GPIH heat illness consultations. Results GP consultations and ED attendances for heat illness increased during the heatwave period; GPIH consultations increased across all age groups, but the highest rates were in school children and those aged ≥75 years, with the latter persisting beyond the end of the heatwave. Extrapolating to the English population, we estimated that the number of GPIH consultations for heat illness during the whole summer (May to September) 2013 was 1166 (95% CI 1064 to 1268). This was double the rate observed during non-heatwave years. Conclusions These findings support the monitoring of heat illness (symptoms of heat/sun stroke) as part of the Heatwave Plan for England, but also suggest that specifically monitoring heat illness in children, especially those of school age, would provide additional early warning of, and situation awareness during heatwaves. PMID:26873949

  8. 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

  9. Estimating concentrations of heat producing elements in the crust near the Sudbury Neutrino Observatory, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Phaneuf, Catherine; Mareschal, Jean-Claude

    2014-05-01

    Because the concentrations of uranium and thorium in the crust must be determined precisely for the future geoneutrino observations planned at the Sudbury Neutrino Observatory, we investigate whether airborne radiometric surveys can be used to constrain crustal radioactivity. The regional airborne surveys cover a wide area with high spatial resolution (< 250 m), but are only sensitive to a very thin (25 cm) surficial layer. We calculate crustal heat production in the Sudbury region from airborne radiometric surveys and compare with measurements on outcrop and core samples, and with heat flow data. The concentrations of uranium, thorium, and potassium from radiometric surveys are correlated with geology, but heat production estimates are lower than values from rock samples. The radiometric surveys give a mean heat production of 0.8 ± 0.6 (σ) μW m- 3 for more than 176,000 values. The outcrop samples collected along a transect in the Superior Province yield an average heat production of 2.9 ± 2.4 (σ) μW m- 3 and core samples from drill holes yield an average of 2.5 ± 0.8 (σ) μW m- 3. The high heat production in the rock samples is consistent with surface heat flux measurements near Sudbury with a mean value that is 12 mW m- 2 higher than the average Canadian Shield. The study shows that airborne aeromagnetic surveys give useful information on lateral variations in surface heat production but are unlikely to provide the reliable values of heat production needed to calculate the crustal geoneutrino flux. Crustal heat production will be best calculated from heat flux data complemented by heat production measurements on rock samples. The high mean heat production in Sudbury Igneous Complex samples (≈ 1.5 μW m- 3) suggests that the main source of the melt sheet was the very radioactive upper crust of the Superior Province or that the melt sheet was extremely enriched relative to a lower crustal source.

  10. In situ Raman estimation of irradiation-induced heating of UO2

    NASA Astrophysics Data System (ADS)

    Guimbretière, G.; Canizarès, A.; Desgranges, L.; Caraballo, R.; Duval, F.; Jegou, C.; Magnin, M.; Simon, P.

    2016-09-01

    We present an in situ Raman estimation of the temperature increase of UO2 pellets induced by cyclotron He2+ ionic irradiation in different environments (Ar gas or water): For instance, in the Ar gas environment, the sample is heated to a temperature 150-200 °C (i.e., below the annealing temperature of UO2 defects). For water, the sample is heated from 30 to 80 °C, just below the range of the studtite/metastudtite and the schoepite/metaschoepite transitions.

  11. Estimating sensitivity and specificity of a PCR for boot socks to detect Campylobacter in broiler primary production using Bayesian latent class analysis.

    PubMed

    Matt, Monika; Nordentoft, Steen; Kopacka, Ian; Pölzler, Thomas; Lassnig, Heimo; Jelovcan, Sandra; Stüger, Hans Peter

    2016-06-01

    The present study compares three different assays for sample collection and detection of Campylobacter spp. in broiler flocks, based on (i) the collection of faecal samples from intestinal organs (caecum), (ii) individual faecal droppings collected from the bedding and (iii) faecal material collected by socks placed on the outside of a pair of boots (boot socks) and used for walking around in the flock. The two first methods are examined for Campylobacter using a culture method (ISO-10272-2:2006), while the boot socks are tested using PCR. The PCR-assay is a genus specific multiplex PCR with primers targeting 16S rDNA in Campylobacter and primers targeting Yersinia ruckerii. Sixty-seven broiler flocks from Austria and 83 broiler flocks from Denmark were included in this prospective study and 89 of these were found to be positive in at least one method (AT: 49 samples, DK: 40 samples) whereas 61 of these were negative in all assays. In Austria samples for the three assays were collected simultaneously, which facilitates a direct comparison of the diagnostic test performance. In Denmark, however, boot socks and faecal droppings were collected three days before slaughter while caecum samples were collected at slaughter. The results were evaluated in the absence of a gold standard using a Bayesian latent class model. Austrian results showed higher sensitivity for PCR detection in sock samples (0.98; Bayesian credible interval (BCI) [0.93-1]) than for culture of faecal droppings (0.86; BCI [0.76-0.91]) or caecal samples (0.92; BCI [0.85-0.97]). The potential impact of Campylobacter introduction within the final three days before slaughter was observed in Denmark, where four flocks were tested negative three days before slaughter, but were detected positive at the slaughterhouse. Therefore the model results for the PCR sensitivity (0.88; BCI [0.83-0.97]) and cultural ISO-method in faecal samples (0.84; BCI [0.76-0.92]) are lower than for caecal samples (0.93; BCI [0

  12. Dynamics of Soil Heat Flux in Lowland Area: Estimating the Soil Thermal Conductivy

    NASA Astrophysics Data System (ADS)

    Zimmer, T.; Silveira, M. V.; Roberti, D. R.

    2013-05-01

    In this work, it is shown soil thermal conductivity estimates in a flooded irrigated rice culture located at the Paraíso do Sul city for two distinct periods. The thermal conductivity is higher when the heat storage is higher and the soil surface temperature is lower. The soil thermal conductivity is also dependant on the soil texture, porosity and moisture. Therefore, it varies from soil to soil and in the same soil, depending on its soil moisture. For approximately 80% of its growing season, lowland flooded irrigated rice ecosystems stay under a 5 - 10 cm water layer. It affects the partitioning of the energy and water balance components. Furthermore this planting technique differs substantially from any other upland non-irrigated or irrigated crop ecosystems where the majority of observational studies have been conducted. In the present work, the dynamic of soil heat flux (G) is analyzed and the soil thermal conductivity (Ks) is estimated using experimental data form soil heat flux and soil temperature in a rice paddy farm in a subtropical location in Southern Brazil. In this region, rice grows once a year at river lowlands and wetlands while the ground is kept bare during the remaining of the year. The soil type is Planossolo Hidromórfico Distrófico, characterized as a mix between sandy and clay soil. The soil heat flux (G) was experimentally estimated with the sensor Hukseflux (HFP01SC-L) at 7 cm bellow the soil surface. The soil temperature at 5 cm and 10 cm was experimentally estimated using the sensor STP01. The experimental soil heat flux was compared with estimated soil heat flux by two forms: (1) using a know Ks from literature for this type of soil in saturated conditions (Ks=1.58); (2) using Ks estimated using the inversion of the equation Qg=-ks* ((T10-T5)/ (Z2-Z1)), where T10 and T5 are the temperature in 10 and 5 cm above the soil and Z2-Z1 is the difference between the positions in temperature measurement. The study period for estimating the Ks

  13. Scaling Variances of Latent Variables by Standardizing Loadings: Applications to Working Memory and the Position Effect

    ERIC Educational Resources Information Center

    Schweizer, Karl

    2011-01-01

    The standardization of loadings gives a metric to the corresponding latent variable and thus scales the variance of this latent variable. By assigning an appropriately estimated weight to all the loadings on the same latent variable it can be achieved that the average squared loading is 1 as the result of standardization. As a consequence, there…

  14. Stochastic Approximation Methods for Latent Regression Item Response Models. Research Report. ETS RR-09-09

    ERIC Educational Resources Information Center

    von Davier, Matthias; Sinharay, Sandip

    2009-01-01

    This paper presents an application of a stochastic approximation EM-algorithm using a Metropolis-Hastings sampler to estimate the parameters of an item response latent regression model. Latent regression models are extensions of item response theory (IRT) to a 2-level latent variable model in which covariates serve as predictors of the…

  15. 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…

  16. 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…

  17. Understanding fast heat transfer in the shallow subsurface

    NASA Astrophysics Data System (ADS)

    Rutten, Martine; Steele-Dunne, Susan; Judge, Jasmeet; van de Giesen, Nick

    2010-05-01

    Understanding the temperature profile of the shallow subsurface is of great importance for interpreting remote sensing observations and modeling land-atmosphere interaction. Remote sensing observations are translated to surface characteristics, such as vegetation and soil moisture, using radiative transfer schemes that are sensitive to skin temperature estimation. The surface temperature is also a key variable in the heat partitioning of net radiation into sensible, latent and soil heat flux at the interface between land and atmosphere. The temperature profile of the soil is determined by the processes of radiative, convective and conductive heat transfer. Whereas radiative and convective heat transfer are dominant at the soil-air interface, heat transfer within the soil is typically assumed to be governed by conduction and as such is described with a diffusion model. The thermal diffusivity of the soil depends mainly on mineral composition and moisture content and is described in many empirical models. Using temperature data from experiments conducted in Florida (MicroWex 2) and the Netherlands (Monster), we show that diffusion cannot describe heat transfer within approximately the upper ten centimeters of the soil. The heat transfer is significantly faster than would be predicted with a diffusion equation. Diffusivity values, estimated using an inversion approach to the diffusion equation, fall outside the physically reasonable range, which is defined by available soil diffusivity models. The extent of this strongly thermally active layer depends on vegetation conditions, and possibly moisture conditions. We investigate mechanisms that may explain the fast heat transfer in the shallow subsurface. Possible mechanisms include heat transfer by convective heat transfer processes such as latent heat formation and heat transfer due to water percolation. We estimated the size of the heat sink-source at depth and compared these to observations of latent heat and

  18. Estimation from Soil Temperature of Soil Thermal Diffusivity and Heat Flux in Sub-surface Layers

    NASA Astrophysics Data System (ADS)

    An, Kedong; Wang, Wenke; Zhao, Yaqian; Huang, Wenfeng; Chen, Li; Zhang, Zaiyong; Wang, Qiangmin; Li, Wanxin

    2016-03-01

    Soil thermal parameters are important for calculating the surface energy balance and mass transfer. Previous studies have proposed methods to estimate thermal parameters using field data; however, the application of these methods lacks validation and comprehensive evaluation under different climatic conditions. Here, we evaluate four methods (amplitude, phase shift, conduction-convection and harmonic) to estimate thermal diffusivity ( k) under different climatic conditions. Heat flux was simulated and compared with data from heat-flux plates to validate the application of the four methods. The results indicated that, under clear-sky conditions, the harmonic method had the greatest accuracy in estimating k, though it generated large errors on rainy days or under overcast conditions. The conduction-convection method (CCM) provided a reliable estimate of k on rainy days, or under overcast skies, coinciding with increased water movement in the soil profile. The amplitude method, although a simple calculation, had poor accuracy for rainy and overcast conditions. Finally, the phase shift method was shown to be a suitable alternative for CCM to estimate k under overcast conditions, though only when soil moisture content was high.

  19. Finite Element A Posteriori Error Estimation for Heat Conduction. Degree awarded by George Washington Univ.

    NASA Technical Reports Server (NTRS)

    Lang, Christapher G.; Bey, Kim S. (Technical Monitor)

    2002-01-01

    This research investigates residual-based a posteriori error estimates for finite element approximations of heat conduction in single-layer and multi-layered materials. The finite element approximation, based upon hierarchical modelling combined with p-version finite elements, is described with specific application to a two-dimensional, steady state, heat-conduction problem. Element error indicators are determined by solving an element equation for the error with the element residual as a source, and a global error estimate in the energy norm is computed by collecting the element contributions. Numerical results of the performance of the error estimate are presented by comparisons to the actual error. Two methods are discussed and compared for approximating the element boundary flux. The equilibrated flux method provides more accurate results for estimating the error than the average flux method. The error estimation is applied to multi-layered materials with a modification to the equilibrated flux method to approximate the discontinuous flux along a boundary at the material interfaces. A directional error indicator is developed which distinguishes between the hierarchical modeling error and the finite element error. Numerical results are presented for single-layered materials which show that the directional indicators accurately determine which contribution to the total error dominates.

  20. Estimation and harvesting of human heat power for wearable electronic devices

    NASA Astrophysics Data System (ADS)

    Dziurdzia, P.; Brzozowski, I.; Bratek, P.; Gelmuda, W.; Kos, A.

    2016-01-01

    The paper deals with the issue of self-powered wearable electronic devices that are capable of harvesting free available energy dissipated by the user in the form of human heat. The free energy source is intended to be used as a secondary power source supporting primary battery in a sensor bracelet. The main scope of the article is a presentation of the concept for a measuring setup used to quantitative estimation of heat power sources in different locations over the human body area. The crucial role in the measurements of the human heat plays a thermoelectric module working in the open circuit mode. The results obtained during practical tests are confronted with the requirements of the dedicated thermoelectric generator. A prototype design of a human warmth energy harvester with an ultra-low power DC-DC converter based on the LTC3108 circuit is analysed.

  1. Estimation of Metabolism Characteristics for Heat-Injured Bacteria Using Dielectrophoretic Impedance Measurement Method

    NASA Astrophysics Data System (ADS)

    Amako, Eri; Enjoji, Takaharu; Uchida, Satoshi; Tochikubo, Fumiyoshi

    Constant monitoring and immediate control of fermentation processes have been required for advanced quality preservation in food industry. In the present work, simple estimation of metabolic states for heat-injured Escherichia coli (E. coli) in a micro-cell was investigated using dielectrophoretic impedance measurement (DEPIM) method. Temporal change in the conductance between micro-gap (ΔG) was measured for various heat treatment temperatures. In addition, the dependence of enzyme activity, growth capacity and membrane situation for E. coli on heat treatment temperature was also analyzed with conventional biological methods. Consequently, a correlation between ΔG and those biological properties was obtained quantitatively. This result suggests that DEPIM method will be available for an effective monitoring technique for complex change in various biological states of microorganisms.

  2. Sharp Two-Sided Heat Kernel Estimates of Twisted Tubes and Applications

    NASA Astrophysics Data System (ADS)

    Grillo, Gabriele; Kovařík, Hynek; Pinchover, Yehuda

    2014-07-01

    We prove on-diagonal bounds for the heat kernel of the Dirichlet Laplacian in locally twisted three-dimensional tubes Ω. In particular, we show that for any fixed x the heat kernel decays for large times as , where E 1 is the fundamental eigenvalue of the Dirichlet Laplacian on the cross section of the tube. This shows that any, suitably regular, local twisting speeds up the decay of the heat kernel with respect to the case of straight (untwisted) tubes. Moreover, the above large time decay is valid for a wide class of subcritical operators defined on a straight tube. We also discuss some applications of this result, such as Sobolev inequalities and spectral estimates for Schrödinger operators.

  3. Estimation of time of death with a fourier series unsteady-state heat transfer model.

    PubMed

    Smart, Jimmy L

    2010-11-01

    The purpose of this study was to return to fundamental principles of heat transfer and derive a suitable model to establish a firm basis for constructing a postmortem human cooling curve. A Fourier Series Model was successfully applied to unsteady heat transfer within a wooden cylinder in controlled laboratory conditions. Wood has similar thermal diffusivity properties as human tissue. By manipulation of the model, sensitivity analyses were performed to observe the impact of changes in values of input variables. Variables of initial temperature of the cylinder and ambient surrounding temperature were shown to be very sensitive and have the most impact upon predictive results of the model. The model was also used to demonstrate the existence of an initial temperature plateau, which is often the subject of controversy in estimating time of death. Finally, it was demonstrated how the Fourier Series Model can be applied to estimate time of death for humans. PMID:20533983

  4. A Conceptual Design Study on the Application of Liquid Metal Heat Transfer Technology to the Solar Thermal Power Plant

    NASA Technical Reports Server (NTRS)

    Zimmerman, W. F.; Robertson, C. S.; Ehde, C. L.; Divakaruni, S. M.; Stacy, L. E.

    1979-01-01

    Alkali metal heat transfer technology was used in the development of conceptual designs for the transport and storage of sensible and latent heat thermal energy in distributed concentrator, solar Stirling power conversion systems at a power level of 15 kWe per unit. Both liquid metal pumped loop and heat pipe thermal transport were considered; system configurations included: (1) an integrated, focal mounted sodium heat pipe solar receiver (HPSR) with latent heat thermal energy storage; (2) a liquid sodium pumped loop with the latent heat storage, Stirling engine-generator, pump and valves located on the back side of the concentrator; and (3) similar pumped loops serving several concentrators with more centralized power conversion and storage. The focus mounted HPSR was most efficient, lightest and lowest in estimated cost. Design confirmation testing indicated satisfactory performance at all angles of inclination of the primary heat pipes to be used in the solar receiver.

  5. Vertical heat flux in the ocean: Estimates from observations and from a coupled general circulation model

    NASA Astrophysics Data System (ADS)

    Cummins, Patrick F.; Masson, Diane; Saenko, Oleg A.

    2016-06-01

    The net heat uptake by the ocean in a changing climate involves small imbalances between the advective and diffusive processes that transport heat vertically. Generally, it is necessary to rely on global climate models to study these processes in detail. In the present study, it is shown that a key component of the vertical heat flux, namely that associated with the large-scale mean vertical circulation, can be diagnosed over extra-tropical regions from global observational data sets. This component is estimated based on the vertical velocity obtained from the geostrophic vorticity balance, combined with estimates of absolute geostrophic flow. Results are compared with the output of a non-eddy resolving, coupled atmosphere-ocean general circulation model. Reasonable agreement is found in the latitudinal distribution of the vertical heat flux, as well as in the area-integrated flux below about 250 m depth. The correspondence with the coupled model deteriorates sharply at depths shallower than 250 m due to the omission of equatorial regions from the calculation. The vertical heat flux due to the mean circulation is found to be dominated globally by the downward contribution from the Southern Hemisphere, in particular the Southern Ocean. This is driven by the Ekman vertical velocity which induces an upward transport of seawater that is cold relative to the horizontal average at a given depth. The results indicate that the dominant characteristics of the vertical transport of heat due to the mean circulation can be inferred from simple linear vorticity dynamics over much of the ocean.

  6. Estimating uncertainty caused by ocean heat transport to the North Sea: experiments downscaling EC-Earth

    NASA Astrophysics Data System (ADS)

    Tian, T.; Su, J.; Boberg, F.; Yang, S.; Schmith, T.

    2016-01-01

    The heat content of the North Sea is determined by the surface heat flux and the ocean heat transport into the region. The uncertainty in the projected warming in the North Sea caused by ocean heat transport has rarely been quantified. The difference in the estimates using regional ocean models is known to arise from the poorly prescribed temperature boundary forcing, either provided by global models at coarse grid resolutions, or from anomaly correction (using difference of the simulation from observed climatology) without interannual variation. In this study, two marine downscaling experiments were performed using boundary temperature forcings prepared with the two above mentioned strategies: one interpolated from a global model simulation (MI: model incl. interannual variation), and the other from observed climatology with warming trends in the future ocean derived from the global model simulation (OT: observed climatol. plus trend). The comparative experiments allowed us to estimate the uncertainty caused by ocean heat transport to the North Sea. The global climate model EC-Earth CMIP5 simulations of historical and future scenarios were used to provide lateral boundary forcing for regional models. The OT boundary was found to affect deep water temperatures (below 50 m) in the North Sea because of reduced interannual variability. The difference of mean temperature changes by 2100 (MI - OT) was up to 0.5 °C near the bottom across 58°N. While the deep water temperature in the North Sea did not directly link to the large-scale atmospheric circulation, the Norwegian outflow was highly correlated with the NAO index and heat transport of the Atlantic inflow provided by EC-Earth. It was found that model uncertainty due to the choice of lateral boundary forcing could be significant in the interannual variation of thermal stratification in the northern North Sea in a long-term simulation.

  7. Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

    USGS Publications Warehouse

    Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

    2006-01-01

    Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

  8. 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

  9. Real-Time Personalized Monitoring to Estimate Occupational Heat Stress in Ambient Assisted Working.

    PubMed

    Pancardo, Pablo; Acosta, Francisco D; Hernández-Nolasco, José Adán; Wister, Miguel A; López-de-Ipiña, Diego

    2015-01-01

    Ambient Assisted Working (AAW) is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers' comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. Occupational heat stress (OHS) happens when a worker is in an uninterrupted physical activity and in a hot environment. OHS can produce strain on the body, which leads to discomfort and eventually to heat illness and even death. Related ISO standards contain methods to estimate OHS and to ensure the safety and health of workers, but they are subjective, impersonal, performed a posteriori and even invasive. This paper focuses on the design and development of real-time personalized monitoring for a more effective and objective estimation of OHS, taking into account the individual user profile, fusing data from environmental and unobtrusive body sensors. Formulas employed in this work were taken from different domains and joined in the method that we propose. It is based on calculations that enable continuous surveillance of physical activity performance in a comfortable and healthy manner. In this proposal, we found that OHS can be estimated by satisfying the following criteria: objective, personalized, in situ, in real time, just in time and in an unobtrusive way. This enables timely notice for workers to make decisions based on objective information to control OHS. PMID:26184218

  10. Real-Time Personalized Monitoring to Estimate Occupational Heat Stress in Ambient Assisted Working

    PubMed Central

    Pancardo, Pablo; Acosta, Francisco D.; Hernández-Nolasco, José Adán; Wister, Miguel A.; López-de-Ipiña, Diego

    2015-01-01

    Ambient Assisted Working (AAW) is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers' comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. Occupational heat stress (OHS) happens when a worker is in an uninterrupted physical activity and in a hot environment. OHS can produce strain on the body, which leads to discomfort and eventually to heat illness and even death. Related ISO standards contain methods to estimate OHS and to ensure the safety and health of workers, but they are subjective, impersonal, performed a posteriori and even invasive. This paper focuses on the design and development of real-time personalized monitoring for a more effective and objective estimation of OHS, taking into account the individual user profile, fusing data from environmental and unobtrusive body sensors. Formulas employed in this work were taken from different domains and joined in the method that we propose. It is based on calculations that enable continuous surveillance of physical activity performance in a comfortable and healthy manner. In this proposal, we found that OHS can be estimated by satisfying the following criteria: objective, personalized, in situ, in real time, just in time and in an unobtrusive way. This enables timely notice for workers to make decisions based on objective information to control OHS. PMID:26184218

  11. Estimation of ground heat flux from soil temperature over a bare soil

    NASA Astrophysics Data System (ADS)

    An, Kedong; Wang, Wenke; Wang, Zhoufeng; Zhao, Yaqian; Yang, Zeyuan; Chen, Li; Zhang, Zaiyong; Duan, Lei

    2016-05-01

    Ground soil heat flux, G 0, is a difficult-to-measure but important component of the surface energy budget. Over the past years, many methods were proposed to estimate G 0; however, the application of these methods was seldom validated and assessed under different weather conditions. In this study, three popular models (force-restore, conduction-convection, and harmonic) and one widely used method (plate calorimetric), which had well performance in publications, were investigated using field data to estimate daily G 0 on clear, cloudy, and rainy days, while the gradient calorimetric method was regarded as the reference for assessing the accuracy. The results showed that harmonic model was well reproducing the G 0 curve for clear days, but it yielded large errors on cloudy and rainy days. The force-restore model worked well only under rainfall condition, but it was poor to estimate G 0 under rain-free conditions. On the contrary, the conduction-convection model was acceptable to determine G 0 under rain-free conditions, but it generated large errors on rainfall days. More importantly, the plate calorimetric method was the best to estimate G 0 under different weather conditions compared with the three models, but the performance of this method is affected by the placement depth of the heat flux plate. As a result, the heat flux plate was recommended to be buried as close as possible to the surface under clear condition. But under cloudy and rainy conditions, the plate placed at depth of around 0.075 m yielded G 0 well. Overall, the findings of this paper provide guidelines to acquire more accurate estimation of G 0 under different weather conditions, which could improve the surface energy balance in field.

  12. Direct Measurement of the Adsorbed Film Volume for Estimating Heats of Adsorption

    NASA Astrophysics Data System (ADS)

    Gillespie, Andrew; Dohnke, Elmar; Rash, Tyler; Stalla, David; Knight, Ernest; Seydel, Florian; Sweany, Mark; Pfeifer, Peter

    Compressed hydrogen and methane require extremely high pressures or low temperatures in order to compete with the energy density of conventional fossil fuels. Adsorbent materials provide a means to increase the energy density of these gasses up to 6 times that of compressed gas at the same temperature and pressure. One major concern in engineering adsorbed gas systems is thermal management during charging and discharging. Adsorption is an exothermic process, releasing heat during charging and absorbing heat during discharging. To estimate the heat of adsorption, it is common to analyze excess adsorption isotherms by converting to absolute adsorption and employ the Clausius Clapeyron relation. However, this method requires an assumed volume of the adsorbed state. It is common for researchers to assume that the adsorbed film occupies the entire pore volume of the adsorbent material. However, the adsorbed film only occupies a fraction of the total pore volume. This yields heats of adsorption that are underestimated by as much as 10kJ/mol at high coverage. In this talk, we present a method to directly measure the adsorbed film volume as a function of temperature and present the resulting heats of adsorption for both methane and hydrogen.

  13. An Improved Heat Budget Estimation Including Bottom Effects for General Ocean Circulation Models

    NASA Technical Reports Server (NTRS)

    Carder, Kendall; Warrior, Hari; Otis, Daniel; Chen, R. F.

    2001-01-01

    This paper studies the effects of the underwater light field on heat-budget calculations of general ocean circulation models for shallow waters. The presence of a bottom significantly alters the estimated heat budget in shallow waters, which affects the corresponding thermal stratification and hence modifies the circulation. Based on the data collected during the COBOP field experiment near the Bahamas, we have used a one-dimensional turbulence closure model to show the influence of the bottom reflection and absorption on the sea surface temperature field. The water depth has an almost one-to-one correlation with the temperature rise. Effects of varying the bottom albedo by replacing the sea grass bed with a coral sand bottom, also has an appreciable effect on the heat budget of the shallow regions. We believe that the differences in the heat budget for the shallow areas will have an influence on the local circulation processes and especially on the evaporative and long-wave heat losses for these areas. The ultimate effects on humidity and cloudiness of the region are expected to be significant as well.

  14. Precipitation rates and atmospheric heat transport during the Cenomanian greenhouse warming in North America: Estimates from a stable isotope mass-balance model

    USGS Publications Warehouse

    Ufnar, David F.; Ludvigson, Greg A.; Gonzalez, L.; Grocke, D.R.

    2008-01-01

    correlate with a mean annual average heat loss of 48??W/m2 at 10??N paleolatitude (present, 8??W/m2 at 15??N). The increased precipitation flux and moisture surplus in the mid-latitudes corresponds to a mean average annual heat gain of 180??W/m2 at 50??N paleolatitude (present, 17??W/m2 at 50??N). The Cenomanian low-latitude moisture deficit is similar to that of the Albian, however the mid-latitude (40-60??N) precipitation flux values and precipitation rates are significantly higher (Albian: 2200??mm/yr at 45??N; Cenomanian: 3600??mm/yr at 45??N). Furthermore, the heat transferred to the atmosphere via latent heat of condensation was approximately 10.6?? that of the present at 50??N. The intensified hydrologic cycle of the mid-Cretaceous greenhouse warming may have played a significant role in the poleward transfer of heat and more equable global conditions. Paleoclimatological reconstructions from multiple time periods during the mid-Cretaceous will aid in a better understanding of the dynamics of the hydrologic cycle and latent heat flux during greenhouse world conditions.

  15. Estimation of anthropogenic heat emissions in urban Taiwan and their spatial patterns.

    PubMed

    Koralegedara, Suranjith Bandara; Lin, Chuan-Yao; Sheng, Yang-Fan; Kuo, Ching-Huei

    2016-08-01

    High energy consumption in the urban environment impacts the urban surface energy budget and causes the emission of anthropogenic heat fluxes (AHFs) into the atmosphere. AHFs vary over time and space. Thus, a reliable estimation of AHF is needed for mesoscale meteorological modeling. This study used a statistical regression method to estimate the annual mean gridded AHF with high spatial (1-km) resolution. Compared with current methods for AHF estimation, the statistical regression method is straightforward and can be easily incorporated with meteorological modeling. AHF of the highly populated urban areas in Taiwan were estimated using data from the anthropogenic pollutant emission inventory of CO and NOx for year 2010. Over 40% of the total AHF values in Taiwan main island fell within the range of 10-40 Wm(-2). When the study domain was confined to urban land, the percentage contributions from AHF values were increased, with over 68% of the total AHF values within the range of 10-40 Wm(-2). AHF values > 40 Wm(-2) were more abundant in the Southern region, followed by the Central and Northern regions. An assessment of the heat emissions by the large scale urban consumption of energy (LUCY) model revealed that the mean AHFs are reasonably close to those produced while the maximum AHFs are underestimated. The results obtained evidence the impact of spatial distribution of land use types, particularly population densities, main highways and industries on AHF generation in Taiwan. PMID:27179327

  16. Streambed Temperatures and Heat Budget Estimates in Groundwater-fed Streams

    NASA Astrophysics Data System (ADS)

    Middleton, M.; Allen, D. M.; Whitfield, P. H.

    2013-12-01

    A streambed temperature monitoring network was installed in a groundwater-fed stream in the Lower Fraser Valley of British Columbia. A network of fifteen temperature loggers was installed in a short reach (<40 m) of Fishtrap Creek to characterize the spatial and temporal variability in streambed temperatures and identify potential mechanisms for localized cooling based on heat exchanges during the summer low flow period. This reach has uniform channel form and water depth, and consistent bed material. Streambed temperature data were collected hourly for the period of July 2008 through October 2012, spanning five summer low flow periods. Nearby climate, stream discharge, and groundwater monitoring stations provided the data to estimate the heat budget components. Over the five summer low flow periods, the network of dataloggers recorded a mean streambed temperature of 13.8oC, with a range of 10.2oC to 20.0oC across the streambed. In order to assess controls on streambed temperature at individual datalogger locations, the incoming heat from sources acting across the entire reach had to be removed from the observed temperature signals. The incoming heat was calculated for the air-water interface to estimate the energy flux into the reach using a heat balance. Incoming solar radiation dominates the heat balance, and evaporative heat fluxes were noticeable as small amplitude variations at a daily scale. Precipitation occurrence, or absence, was not an important component of the heat balance during the summer low flow period. Since incoming solar radiation dominates both air and water temperatures, air temperature (Ta) can be used as a proxy for streambed temperature (Ts). The actual lag time between the air and streambed temperature for this site was 30 hours; however, for the calculation of stream temperature at a daily time step, a lag of 24 hours was used. The relationship between daily streambed temperature and daily air temperature, at a lag of one day, was

  17. Estimating Heat Transfer from Grotto Mound, NEPTUNE Canada Cabled Observatory, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Bemis, K. G.; Xu, G.

    2012-12-01

    Heat flux is a fundamental property of a seafloor hydrothermal system that relates to magnitude of sub-seafloor heat source and biosphere conditions, to distribution and style of seafloor venting and benthic biota, to chemical flux, plume formation, and dispersal of biological matter in the water column. We are working to estimate heat flux from Grotto mound, the site of the NEPTUNE Canada Cabled Observatory in the Main Endeavour Field on the Juan de Fuca Ridge. The mound is formed of two sulfide edifices that lie between ~2190 and 2180 m isobaths: 1) an elliptical edifice with major NE-SW-trending axis ~30 m long and minor axis ~ 14 m wide (area ~ 330 m2); 2) a columnar edifice ~ 10 m in diameter and 10 m high (area ~80 m2) named the North Tower, situated across a narrow (~5 m wide) saddle (area ~40 m2) at the W end of the elliptical edifice. Several black smokers discharge relatively small plumes at the E end of the elliptical edifice. A cluster of vigorous black smokers discharge from the top of North Tower and merge to form a large plume. Patchy diffuse flow occurs in areas around all of the black smokers and in the saddle between the two edifices. We are in process of measuring heat flux from components of hydrothermal discharge on Grotto mound, as follows: 1) for smokers on the North Tower an integrated heat flux of 28-55 MW is calculated based on temperature measurements in the initial 20 m rise of the plume assuming that the highest temperatures measured are closest to those of the plume centerline ; 2) for smokers on the E end of the elliptical edifice based on measurements of flow rate from video and acoustic Doppler phase shift, video of vent diameters, and in situ temperature measurements; 3) for discharge from flanges on some chimneys based on video of flow and in situ temperature measurements; 4) for diffuse flow based on area measured by Acoustic Scintillation Thermography and direct measurements of temperature and flow rate. We are evaluating

  18. Estimating Energy Expenditure Using Heat Flux Measured at Single Body Site

    PubMed Central

    Lyden, Kate; Swibas, Tracy; Catenacci, Victoria; Guo, Ruixin; Szuminsky, Neil; Melanson, Edward L.

    2014-01-01

    Introduction The Personal Calorie Monitor (PCM) is a portable direct calorimeter that estimates energy expenditure (EE) from measured heat flux (i.e. the sum of conductive, convective, radiative, and evaporative). Purpose The primary aim of this study was to compare EE estimated from measures of heat flux to indirect calorimetry in a thermoneutral environment (26°C). A secondary aim was to determine if exposure to ambient temperature below thermoneutral (19°C) influences the accuracy of the PCM. Methods 34 Adults (mean±SD, age = 28±5 y, body mass index = 22.9±2.6 kg.m2) were studied for 5 h in a whole-room indirect calorimeter (IC) in thermoneutral and cool conditions. Participants wore the PCM on their upper arm and completed two, 20-minute treadmill-walking bouts (0% grade, 3 mph). The remaining time was spent sedentary (e.g., watching television, using a computer). Results In thermoneutral, EE (mean (95% CI)) measured by IC and PCM was 560.0 (526.5, 593.5) and 623.3 (535.5, 711.1) kcals, respectively. In cool, EE measured by IC and PCM was 572.5 (540.9, 604.0) and 745.5 (668.1, 822.8) kcals, respectively. Under thermoneutral conditions, mean PCM minute-by-minute EE tracked closely with IC, resulting in a small, non-significant bias (63 kcals (−5.8, 132.4)). During cool conditions, mean PCM minute-by-minute EE did not track IC, resulting in a large bias (173.0 (93.9, 252.1)) (p<0.001). Conclusion This study demonstrated the validity of using measured heat flux to estimate EE. However, accuracy may be impaired in cool conditions, possibly due to excess heat loss from the exposed limbs. PMID:24811326

  19. Estimation of lacustrine groundwater discharge using heat as a tracer and vertical hydraulic gradients - a comparison

    NASA Astrophysics Data System (ADS)

    Rudnick, S.; Lewandowski, J.; Nützmann, G.

    2015-03-01

    Lacustrine groundwater discharge (LGD) can play a major role in water and nutrient balances of lakes. Unfortunately, studies often neglect this input path due to methodological difficulties in the determination. In a previous study we described a method which allows the estimation of LGD and groundwater recharge using hydraulic head data and groundwater net balances based on meteorological data. The aim of this study is to compare these results with discharge rates estimated by inverse modelling of heat transport using temperature profiles measured in lake bed sediments. We were able to show a correlation between the fluxes obtained with the different methods, although the time scales of the methods differ substantially. As a consequence, we conclude that the use of hydraulic head data and meteorologically-based groundwater net balances to estimate LGD is limited to time scales similar to the calibration period.

  20. Estimation of surface heat and moisture fluxes over a prairie grassland 3. Design of a hybrid physical/remote sensing biosphere model

    SciTech Connect

    Smith, E.A.; Cooper, H.J.; Weng Hengyi ); Crosson, W.L. )

    1993-03-20

    This is the third in a series of papers describing a measurement program and modeling approach to the estimation of surface heat and moisture fluxes over a tallgrass prairie. The authors describe the design and formulation of an experimental biosphere model (Ex-BATS) which follows the development of Dickinson's biosphere-atmosphere transfer scheme (BATS). Ex-BATS has been designed to incorporate in situ measurements and satellite parameterizations of certain canopy variables which are slowly varying in the course of a growing season. All components of a multistage biosphere process model used to simulate the exchange of heat and moisture between the canopy and the atmosphere are presented here. The remote sensing aspects of the model are described in a companion paper. The procedures used to optimize the model and the validation of the model against First ISLSCP Field Experiment (FIFE) observations taken during 1987 are described. Validation was carried out for three of the four intensive field campaigns (IFC): 1,2 and 3. The validation intercomparison shows that the Ex-BATS model reproduces the diurnal behavior of the surface fluxes very closely. The rms differences between in situ measurements of sensible and latent heat fluxes and their model counterparts are of the order of 35 W m[sup [minus]2]. Biases over the three IFCs, which ranged in duration from 10 to 17 days, are typically less than 20 W m[sup [minus]2]. The overall bias for the 44 days within the first three IFCs is less than 10 W m[sup [minus]2]. The biases and rms differences are of the same order as the accuracy and precision uncertainties of the measured fluxes, therefore the model provides a useful experimental tool to explain radiative, hydrological, and physiological controls on surface fluxes over vegetated canopies and the explicit sources of water flux to the atmosphere from transpiration, foliage evaporation, and soil evaporation. 37 refs., 12 figs., 7 tabs.

  1. 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).

  2. The implications for climate sensitivity of AR5 forcing and heat uptake estimates

    NASA Astrophysics Data System (ADS)

    Lewis, Nicholas; Curry, Judith A.

    2015-08-01

    Energy budget estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) are derived using the comprehensive 1750-2011 time series and the uncertainty ranges for forcing components provided in the Intergovernmental Panel on Climate Change Fifth Assessment Working Group I Report, along with its estimates of heat accumulation in the climate system. The resulting estimates are less dependent on global climate models and allow more realistically for forcing uncertainties than similar estimates based on forcings diagnosed from simulations by such models. Base and final periods are selected that have well matched volcanic activity and influence from internal variability. Using 1859-1882 for the base period and 1995-2011 for the final period, thus avoiding major volcanic activity, median estimates are derived for ECS of 1.64 K and for TCR of 1.33 K. ECS 17-83 and 5-95 % uncertainty ranges are 1.25-2.45 and 1.05-4.05 K; the corresponding TCR ranges are 1.05-1.80 and 0.90-2.50 K. Results using alternative well-matched base and final periods provide similar best estimates but give wider uncertainty ranges, principally reflecting smaller changes in average forcing. Uncertainty in aerosol forcing is the dominant contribution to the ECS and TCR uncertainty ranges.

  3. 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

  4. 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.

  5. Daily evapotranspiration estimates from extrapolating instantaneous airborne remote sensing ET values

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, six extrapolation methods have been compared for their ability to estimate daily crop evapotranspiration (ETd) from instantaneous latent heat flux estimates derived from digital airborne multispectral remote sensing imagery. Data used in this study were collected during an experiment...

  6. Estimation and Uncertainty Analysis of Impacts of Future Heat Waves on Mortality in the Eastern United States

    SciTech Connect

    Wu, Jianyong; Zhou, Ying; Gao, Yang; Fu, Joshua S.; Johnson, Brent; Huang, Cheng; Kim, Young-Min; Liu, Yang

    2014-01-01

    Background: It is anticipated that climate change will influence heat-related mortality in the future. However, the estimation of excess mortality attributable to future heat waves is subject to large uncertainties, which have not been examined under the latest greenhouse gas emission scenarios. Objectives: We estimated the future heat wave impact on mortality in the eastern United States (~ 1,700 counties) under two Representative Concentration Pathways (RCPs) and analyzed the sources of uncertainties. Methods Using dynamically downscaled hourly temperature projections in 2057-2059, we calculated heat wave days and episodes based on four heat wave metrics, and estimated the excess mortality attributable to them. The sources of uncertainty in estimated excess mortality were apportioned using a variance-decomposition method. Results: In the eastern U.S., the excess mortality attributable to heat waves could range from 200-7,807 with the mean of 2,379 persons/year in 2057-2059. The projected average excess mortality in RCP 4.5 and 8.5 scenarios was 1,403 and 3,556 persons/year, respectively. Excess mortality would be relatively high in the southern and eastern coastal areas. The major sources of uncertainty in the estimates are relative risk of heat wave mortality, the RCP scenarios, and the heat wave definitions. Conclusions: The estimated mortality risks from future heat waves are likely an order of magnitude higher than its current level and lead to thousands of deaths each year under the RCP8.5 scenario. The substantial spatial variability in estimated county-level heat mortality suggests that effective mitigation and adaptation measures should be developed based on spatially resolved data.

  7. Estimated heats of fusion of fluoride salt mixtures suitable for thermal energy storage applications

    NASA Technical Reports Server (NTRS)

    Misra, A. K.; Whittenberger, J. D.

    1986-01-01

    The heats of fusion of several fluoride salt mixtures with melting points greater than 973 K were estimated from a coupled analysis of the available thermodynamic data and phase diagrams. Simple binary eutectic systems with and without terminal solid solutions, binary eutectics with congruent melting intermediate phases, and ternary eutectic systems were considered. Several combinations of salts were identified, most notable the eutectics LiF-22CaF2 and NaF-60MgF2 which melt at 1039 and 1273 K respectively which posses relatively high heats of fusion/gm (greater than 0.7 kJ/g). Such systems would seemingly be ideal candidates for the light weight, high energy storage media required by the thermal energy storage unit in advanced solar dynamic power systems envisioned for the future space missions.

  8. Thermostatistical estimations of vapor-state molecules affected by gravity in a heat pipe

    NASA Astrophysics Data System (ADS)

    Etori, Kanji

    1988-03-01

    Some thermodynamical properties of vapor state molecules in a heat pipe are analytically examined in an unsteady quasi-thermoequilibrium state. First, as a analytical procedure, the Hamiltonian of a gas molecule is formulated as the sum of those energies of the translation, the intermolecular interaction, the rotation, the vibration and the work with respect to the ensemble average of an unsteady velocity of a vapor state molecule in a gravity. The partition function and the free energy in this system are secondly introduced by using the Hamiltonian. According to the thermodynamical relations, the entropy and the specific heat per mol of the vapor state molecules are derived from the free energy and are finally estimated to examine the shifts affected by the gravity from the conventional values which do not include any gravitational term.

  9. Study of Nuclear Decay Data Contribution to Uncertainties in Heat Load Estimations for Spent Fuel Pools

    NASA Astrophysics Data System (ADS)

    Ferroukhi, H.; Leray, O.; Hursin, M.; Vasiliev, A.; Perret, G.; Pautz, A.

    2014-04-01

    At the Paul Scherrer Institut (PSI), a methodology for nuclear data uncertainty propagation in CASMO-5M (C5M) assembly calculations is under development. This paper presents a preliminary application of this methodology to C5M decay heat calculations. Applying a stochastic sampling method, nuclear decay data uncertainties are first propagated for the cooling phase only. Thereafter, the uncertainty propagation is enlarged to gradually account for cross-section as well as fission yield uncertainties during the depletion phase. On that basis, assembly heat load uncertainties as well as total uncertainty for the entire pool are quantified for cooling times up to one year. The relative contributions from the various types of nuclear data uncertainties are in this context also estimated.

  10. The global response to vertical diabatic heating structures associated with the Madden-Julian oscillation derived from TRMM estimates

    NASA Astrophysics Data System (ADS)

    Taylor, J.; Woolnough, S.; Inness, P.

    2013-12-01

    The anomalous global atmospheric circulation associated with the Madden-Julian oscillation (MJO) is examined using composite vertical anomalous diabatic heating structures based on Tropical Rainfall Measuring Mission (TRMM) estimates and reanalysis datasets and integrating a primitive equations model. Variations in the dynamical response from the observational and reanalysis products are investigated in relation to the detailed structure of the vertical structure of heating of the MJO, with specific focus of the role of the westward tilting with altitude in the heating, clearly evident in three reanalysis heating structures but is less well pronounced in the TRMM heating structures. It was found that the atmospheric response to the reanalysis heatings were far more consistent compared to the responses from the TRMM heating estimates. Examination of the moisture flux during the main active phase of the MJO revealed a surplus in moisture convergence ahead of the anomalous heating from each of the reanalysis integrations, which was found to be directly attributed to the vertical tilt in heating structure. In contrast, the response to the TRMM heatings showed no phase shift in moisture convergence in relation to the convective heating and was understood to be a consequence of the weaker representation of vertical tilting in heating structure. It was suggested that the westward tilt in heating could therefore play an important role in promoting convection east of the main heating region. The dynamical response to composite vertical diabatic heating structures associated with the MJO from simulations with Unified Model (UM) HadGEM3 with standard and enhanced (x1.5) entrainment rates are also examined to investigate the relationship between the dynamical response to the heating profile and quality of MJO simulations.

  11. Heat flow and heat generation estimates for the Churchill basement of the Western Canadian Basin in Alberta, Canada

    SciTech Connect

    Beach, R.D.W.; Jones, F.W.; Majorowicz, J.A.

    1987-01-01

    Heat flow through the sediments and temperatures of the Churchill province basement under the sedimentary cover are determined for 24 locations in the central part of the Prairies basin in Alberta where the vertical heat flux is approximately constant from the base of the sediments to the surface. The contribution to heat flow from heat generation in the sediments is also considered. The average heat flow through the sediments is found to be 71 mWm/sup -2/ +- 12mWm/sup -2/ which is about 30 mWm/sup -2/ higher than in the neighbouring shield area of the Churchill province, and the contribution from heat generation in the sediments to the surface heat flow is only approximately 2.5 mWm/sup -2/. The relationship between basement heat generation and heat flow is investigated, and it is found that the platform heat flow/heat generation values are in general higher than those from the Churchill province of the shield found by Drury (1985). Although for the platform and shield data, the reduced heat flow is about 40 mWm/sup -2/ and the slope is about 8km, it is apparent that the platform data alone are not good enough to establish a precise relationship.

  12. A Penalized Latent Class Model for Ordinal Data

    PubMed Central

    Houseman, E. Andrés; Coull, Brent A.; Stemmer-Rachamimov, Anat; Betensky, Rebecca A.

    2016-01-01

    Latent class models provide a useful framework for clustering observations based on several features. Application of latent class methodology to correlated, high-dimensional ordinal data poses many challenges. Unconstrained analyses may not result in an estimable model. Thus, information contained in ordinal variables may not be fully exploited by researchers. We develop a penalized latent class model to facilitate analysis of high-dimensional ordinal data. By stabilizing maximum likelihood estimation, we are able to fit an ordinal latent class model that would otherwise not be identifiable without application of strict constraints. We illustrate our methodology in a study of schwannoma, a peripheral nerve sheath tumor, that included three clinical subtypes and 23 ordinal histological measures. PMID:17626225

  13. TRANSITIONS IN DRUG USE AMONG HIGH-RISK WOMEN: AN APPLICATION OF LATENT CLASS AND LATENT TRANSITION ANALYSIS

    PubMed Central

    Lanza, Stephanie T.; Bray, Bethany C.

    2010-01-01

    Latent class analysis (LCA) is a statistical approach to identifying underlying subgroups (i.e. latent classes) of individuals based on their responses to a set of observed categorical variables. Latent transition analysis (LTA) extends this framework to longitudinal data in order to estimate the incidence of transitions over time in latent class membership. This study provides an introduction to LCA and LTA, including the use of grouping variables and covariates, and demonstrates the use of two SAS ® procedures (PROC LCA and PROC LTA) to fit these models. The empirical demonstration involved data from 457 women who participated in the Women's Interagency HIV Study (WIHS). First, LCA was used to identify drug use latent classes based on reported use of tobacco, alcohol, marijuana, crack/cocaine/heroin and other drugs. Second, LTA was used to estimate the incidence of transitions in drug use latent classes over a one-year period. Third, racial differences in initial drug use and transitions over time were examined using multiple-groups LTA. Fourth, the effect of participation in an alcohol or drug treatment program on initial latent class membership and transitions over time were examined using LTA with covariates. Measurement invariance across time and groups is examined. PMID:21921977

  14. An improved model for sensible heat flux estimation based on landcover classification

    NASA Astrophysics Data System (ADS)

    Zhou, Ti; Xin, Xiaozhou; Jiao, Jingjun; Peng, Zhiqing

    2014-10-01

    Remote sensing (RS) has been recognized as the most feasible means to provide spatially distributed regional evapotranspiration (ET). However, classical RS flux algorithms (SEBS, S-SEBI, SEBAL, etc.) can hardly be used with coarser resolution RS data from sensors like MODIS or AVHRR for no consideration of surface heterogeneity in mixed pixels even they are suitable for assessing the surface fluxes with high resolution RS data.A new model named FAFH is developed in this study to enhance the accuracy of flux estimation in mixed pixels based on high resolution landcover classification data. The area fraction and relative sensible heat fraction of each heterogeneous land use type calculated within coarse resolution pixels are calculated firstly, and then used for the weighted average of modified sensible heat. The study is carried out in the core agricultural land of Zhangye, the middle reaches of Heihe river based on the flux and landcover classification product of HJ-1B in our earlier work. The result indicates that FAFH increases the accuracy of sensible heat by 5% absolutely, 10.64% relatively in the whole research area.

  15. 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

  16. 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

  17. 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…

  18. Estimating the health benefits from natural gas use in transport and heating in Santiago, Chile.

    PubMed

    Mena-Carrasco, Marcelo; Oliva, Estefania; Saide, Pablo; Spak, Scott N; de la Maza, Cristóbal; Osses, Mauricio; Tolvett, Sebastián; Campbell, J Elliott; Tsao, Tsao Es Chi-Chung; Molina, Luisa T

    2012-07-01

    Chilean law requires the assessment of air pollution control strategies for their costs and benefits. Here we employ an online weather and chemical transport model, WRF-Chem, and a gridded population density map, LANDSCAN, to estimate changes in fine particle pollution exposure, health benefits, and economic valuation for two emission reduction strategies based on increasing the use of compressed natural gas (CNG) in Santiago, Chile. The first scenario, switching to a CNG public transportation system, would reduce urban PM2.5 emissions by 229 t/year. The second scenario would reduce wood burning emissions by 671 t/year, with unique hourly emission reductions distributed from daily heating demand. The CNG bus scenario reduces annual PM2.5 by 0.33 μg/m³ and up to 2 μg/m³ during winter months, while the residential heating scenario reduces annual PM2.5 by 2.07 μg/m³, with peaks exceeding 8 μg/m³ during strong air pollution episodes in winter months. These ambient pollution reductions lead to 36 avoided premature mortalities for the CNG bus scenario, and 229 for the CNG heating scenario. Both policies are shown to be cost-effective ways of reducing air pollution, as they target high-emitting area pollution sources and reduce concentrations over densely populated urban areas as well as less dense areas outside the city limits. Unlike the concentration rollback methods commonly used in public policy analyses, which assume homogeneous reductions across a whole city (including homogeneous population densities), and without accounting for the seasonality of certain emissions, this approach accounts for both seasonality and diurnal emission profiles for both the transportation and residential heating sectors. PMID:22595553

  19. A new thermo-hydrodynamic method for estimating convective heat flux associated with vertical fluid migration.

    NASA Astrophysics Data System (ADS)

    Fialko, O.; Kovalchuk, L.

    2002-12-01

    Ample field observations in areas of known oil and gas deposists reveal an existence of excess temperature anomalies associated with the hydrocarbon-bearing structures. These observations are explained in terms of upward migration of heated fluids. In this case there is a deviation from a linear temperature distribution with depth due to a convective component of the heat flux. We propose a new method based on in situ measurements of the thermal field that allows one to take into account both conductive and convective components of the heat flow. In addition to the usual measurements of temperature, we determine the the curvature of the geothermograms, which characterizes the degree of deviation of the heat transfer from a conductive regime. Correspondingly, in addition to the commonly used geothermal gradient, we introduce new parameters, such as the radius of curvature of the geotherms (R), the coefficient of curvature of the geotherms (K), the Knudsen criterion (Kn), and parameter F. We present analytic expressions for the determination of these parameters, and evaluate these parameters for several natural objects. We demonstrate the usefulness of the proposed method for 1) forecasts of the presence of the deep-seated hydrocarbon deposits; 2) estimates of the abnornally elevated gas content in the deep-seated coal deposits, and determination of zones with high risk of methane bursts; 3) studies of the hydro-geothermal conditions of the geothermal areas; 4) determination and localization of leaks along the buried industrial pipelines. We present examples illustrating the application of our method for the abovementioned tasks.

  20. Daytime sensible heat flux estimation over heterogeneous surfaces using multitemporal land-surface temperature observations

    NASA Astrophysics Data System (ADS)

    Castellví, F.; Cammalleri, C.; Ciraolo, G.; Maltese, A.; Rossi, F.

    2016-05-01

    Equations based on surface renewal (SR) analysis to estimate the sensible heat flux (H) require as input the mean ramp amplitude and period observed in the ramp-like pattern of the air temperature measured at high frequency. A SR-based method to estimate sensible heat flux (HSR-LST) requiring only low-frequency measurements of the air temperature, horizontal mean wind speed, and land-surface temperature as input was derived and tested under unstable conditions over a heterogeneous canopy (olive grove). HSR-LST assumes that the mean ramp amplitude can be inferred from the difference between land-surface temperature and mean air temperature through a linear relationship and that the ramp frequency is related to a wind shear scale characteristic of the canopy flow. The land-surface temperature was retrieved by integrating in situ sensing measures of thermal infrared energy emitted by the surface. The performance of HSR-LST was analyzed against flux tower measurements collected at two heights (close to and well above the canopy top). Crucial parameters involved in HSR-LST, which define the above mentioned linear relationship, were explained using the canopy height and the land surface temperature observed at sunrise and sunset. Although the olive grove can behave as either an isothermal or anisothermal surface, HSR-LST performed close to H measured using the eddy covariance and the Bowen ratio energy balance methods. Root mean square differences between HSR-LST and measured H were of about 55 W m-2. Thus, by using multitemporal thermal acquisitions, HSR-LST appears to bypass inconsistency between land surface temperature and the mean aerodynamic temperature. The one-source bulk transfer formulation for estimating H performed reliable after calibration against the eddy covariance method. After calibration, the latter performed similar to the proposed SR-LST method.

  1. 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.

  2. 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 ...

  3. Comparison of measured and modeled radiation, heat and water vapor fluxes: FIFE pilot study

    NASA Technical Reports Server (NTRS)

    Blad, Blaine L.; Hubbard, Kenneth G.; Verma, Shashi B.; Starks, Patrick; Norman, John M.; Walter-Shea, Elizabeth

    1987-01-01

    The feasibility of using radio frequency receivers to collect data from automated weather stations to model fluxes of latent heat, sensible heat, and radiation using routine weather data collected by automated weather stations was tested and the estimated fluxes were compared with fluxes measured over wheat. The model Cupid was used to model the fluxes. Two or more automated weather stations, interrogated by radio frequency and other means, were utilized to examine some of the climatic variability of the First ISLSCP (International Satellite Land-Surface Climatology Project) Field Experiment (FIFE) site, to measure and model reflected and emitted radiation streams from various locations at the site and to compare modeled latent and sensible heat fluxes with measured values. Some bidirectional reflected and emitted radiation data were collected from 23 locations throughout the FIFE site. Analysis of these data along with analysis of the measured sensible and latent heat fluxes is just beginning.

  4. A new method for the estimation of high temperature radiant heat emittance by means of aero-acoustic levitation

    NASA Astrophysics Data System (ADS)

    Greffrath, Fabian; Prieler, Robert; Telle, Rainer

    2014-11-01

    A new method for the experimental estimation of radiant heat emittance at high temperatures has been developed which involves aero-acoustic levitation of samples, laser heating and contactless temperature measurement. Radiant heat emittance values are determined from the time dependent development of the sample temperature which requires analysis of both the radiant and convective heat transfer towards the surroundings by means of fluid dynamics calculations. First results for the emittance of a corundum sample obtained with this method are presented in this article and found in good agreement with literature values.

  5. A study of aggregation bias in estimating the market for home heating and cooling equipment

    SciTech Connect

    Wood, D.J.; Ruderman, H.; McMahon, J.E.

    1989-05-01

    Econometricians frequently propose parametric models which are contingent on an underlying assumption of rational economic agents maximizing their utility. Accurate estimation of the parameters of these models depends on using data disaggregated to the level of the actual agents, usually individual consumers or firms. Using data at some other level of aggregation introduces bias into the inferences made from the data. Unfortunately, properly disaggregated data is often unavailable, or at least, much more costly to obtain than aggregate data. Research on consumer choice of home heating equipment has long depended on state-level cross-sectional data. Only recently have investigators been able to build up and successfully use data on consumer attributes and choices at the household level. A study estimated for the Electric Power Research Institute REEPS model is currently one of the best of these. This paper examines the degree of bias that would be introduced in that study if only average data across SMSAs or states were used at several points in the investigation. We examine the market shares and elasticities estimated from that model using only the mean values of the exogenous variables, and find severe errors to be possible. However, if the models were calibrated on only aggregate data originally, we find that proper treatment allows market shares and elasticities to be found with little error relative to the disaggregate models. 22 refs., 4 figs., 10 tabs.

  6. Estimating uncertainties on a Gulf Stream mixed-layer heat budget from stochastic modeling

    NASA Astrophysics Data System (ADS)

    Ayoub, Nadia K.; Lucas, Marc; De Mey, Pierre

    2015-10-01

    This study aims to explore the robustness of the mixed-layer heat budget as estimated from an eddy-permitting model with respect to uncertainties in atmospheric forcing. We illustrate how statistics from an ensemble can be used in a first step towards the calculation of error bars of any simulated quantity, such as the mixed-layer heat budget. The statistics from an ensemble of 33 simulations are derived in order to infer information on the model errors space and time variability of the main terms of the heat budget. The ensemble is generated by perturbing the wind forcing and the incoming solar radiation as uncertainties on these fields are expected to be a main source of errors for the surface layer representation in the model at monthly to seasonal scales. We focus on the mixed-layer in the Gulf Stream system during the deepening period (Sept.-March). The results indicate that large errors are expected at the Gulf Stream front location and just north of it. The largest errors are found on the zonal and meridional advection and vertical diffusion terms: they can locally reach values that are larger than the terms themselves. We observe a rapid increase with time of the errors for both these terms. The error growth is mainly due to the mesoscale decorrelation. The impact of wind errors on southward Ekman transport and surface turbulence generates uncertainties on the vertical diffusion term just north of the Gulf Stream front. We work with an eddy-permitting configuration similar to those used in ocean reanalysis projects (e.g. SODA, and GLORYS). Our results suggest that for such configurations, at monthly to seasonal time scales, the impact of uncertainties in the atmospheric forcing is weak on the mixed-layer cooling but very large on the zonal and meridional advection and vertical diffusion heat budget terms. In consequence, the estimate of these quantities from ocean reanalyses is not robust with respect to the atmospheric forcing and should be provided with

  7. Sample Sizes for Two-Group Second-Order Latent Growth Curve Models

    ERIC Educational Resources Information Center

    Wanstrom, Linda

    2009-01-01

    Second-order latent growth curve models (S. C. Duncan & Duncan, 1996; McArdle, 1988) can be used to study group differences in change in latent constructs. We give exact formulas for the covariance matrix of the parameter estimates and an algebraic expression for the estimation of slope differences. Formulas for calculations of the required sample…

  8. Magnetic Depth Estimates and Their Potential for Constraining Crustal Composition and Heat Flow in Antarctica

    NASA Astrophysics Data System (ADS)

    Finn, C. A.; Ravat, D.

    2004-12-01

    Crustal composition, temperature, and heat flow, key parameters in ice sheet and tectonic models, are difficult to measure in largely ice-covered Antarctica. Aeromagnetic data have been used on other continents to determine depths to the bottom of magnetic sources from which heat flow has been calculated. However, these depths can also reflect compositional variations, and the consistency of results from various depth determination methods has not been tested. Present spectral magnetic depth determination methods require 1) large window sizes (roughly 10 times the depth to the bottom of the magnetic layer), 2) statistical random or fractal behavior of sources, and 3) datasets free of intermediate to long-wavelength problems stemming from datum shifts or warping of surveys. Depths to both the top (Spector and Grant, 1970, as revised by Fedi et al., 1998) and bottom (Bhattachharyya and Leu, 1975; Shuey et al., 1977; Connard et al., 1983; Okubo et al., 1985; and Blakely, 1988) of magnetic units were calculated. Cross-checking the results by modeling the spectral slopes and locations of peaks ensures reasonable results. Consistency of results from the different methods leads to confidence in the derived estimates. Application of these methods helps determine depths to the top and bottom of magnetic units from several regions in east and west Antarctica using single surveys flown in short periods. Assuming the spectra are obtained from sufficiently large window sizes, comparison of the aeromagnetically-determined layer thicknesses and positions from those computed with other data yield information on crustal composition, and possibly, depth to the Curie isotherm and in turn, heat flow. For example, preliminary results show that a primary magnetic layer thins from ~15-20 km in inferred Precambrian crystalline shield beneath the polar plateau to ~7 km in reworked and juvenile crust of the central Transantarctic Mountains. If the 7 km depth represents the Curie isotherm

  9. 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…

  10. Estimation of surface heat and moisture fluxes over a prairie grassland. 4. Impact of satellite remote sensing of slow canopy variables on performance of a hybrid biosphere model

    NASA Astrophysics Data System (ADS)

    Crosson, William L.; Smith, Eric A.; Cooper, Harry J.

    1993-03-01

    -2 of the rms differences obtained for the simulations performed using measured albedo and leaf area index. Measured stomatal resistance values were obtained using an inversion form of the model. The resulting stomatal resistances were used to perform a control experiment simulating an ideal satellite retrieval scenario involving one observation per day. The control experiment resulted in improvements of approximately 20 W m-2 in the rms flux differences over the model using a purely hypothetical formulation for stomatal resistance. Simulations using the remotely retrieved stomatal resistances produced significantly reduced rms differences for latent and sensible heat fluxes over the model using the hypothetical formulation. Based on a 55-day composite involving all days from the four FIFE intensive field campaigns, the sensible and latent heat flux improvements are approximately 25 and 20%, respectively (11 and 8 W m-2). The satellite retrievals are only 20 and 30% less accurate (7 and 10 W m-2) than the idealized results of the control experiment.

  11. Comparison of interfacial heat transfer coefficient estimated by two different techniques during solidification of cylindrical aluminum alloy casting

    NASA Astrophysics Data System (ADS)

    Rajaraman, R.; Velraj, R.

    2008-07-01

    The interfacial heat transfer coefficient (IHTC) is necessary for accurate simulation of the casting process. In this study, a cylindrical geometry is selected for the determination of the IHTC between aluminum alloy casting and the surrounding sand mold. The mold surface heat flux and temperature are estimated by two inverse heat conduction techniques, namely Beck’s algorithm and control volume technique. The instantaneous cast and mold temperatures are measured experimentally and these values are used in the theoretical investigations. In the control volume technique, partial differential heat conduction equation is reduced to ordinary differential equations in time, which are then solved sequentially. In Beck’s method, solution algorithm is developed under the function specification method to solve the inverse heat conduction equations. The IHTC was determined from the surface heat flux and the mold surface temperature by both the techniques and the results are compared.

  12. A first-order estimate of shock heating and vaporization in oceanic impacts

    NASA Technical Reports Server (NTRS)

    Croft, S. K.

    1982-01-01

    The vaporization of water in oceanic impacts of asteroids or comets of multikilometer dimensions is estimated by a semianalytical modeling of impact heating and shock isobar geometry that is based on computer code calculations. The mass of water vaporized in an infinitely deep ocean by the impact of a 10 km diameter asteroid at 25 km/sec (these values have been proposed for the Cretaceous/Tertiary extinction bolide) is approximately equal to the total mass of water vapor present in the earth's atmosphere, and 3-4 orders of magnitude larger than the mass of water vapor in the stratosphere. For projectiles of this size, however, the finite depth of the ocean becomes significant and may considerably reduce the amount of water vapor initially generated by the impact. Climatological models and extinction scenarios invoking the effects of impact-generated water vapor may critically depend on the a priori ambiguous details of the hypothesized impact.

  13. Estimation of yield capacity of fractured rock aquifer for multi-well groundwater heat pump system

    NASA Astrophysics Data System (ADS)

    Bak, Hyeongmin; Yeo, In Wook

    2015-04-01

    Geothermal heat pump system is classified as closed loop and open loop. Closed loop uses a refrigerant as a heat source. For the reason, when using it for a long time, there is a possibility that the refrigerant pipe is corroded. Accordingly, soil and groundwater can be contaminated. Whereas the open loop system uses a eco-friendly groundwater as a heat source. Thermal circulation of standing column well (SCW) occurs in one well. In contrast, thermal circulation of multi-well groundwater heat pump system (MGHP) occurs through fractured rock aquifer between extraction and injection wells. Therefore, temperature efficiency of MGHP appears to be better than that of SCW. However, the MGHP has problems such as the overflowing in the injection well and the clogging, which restricts the wide use of MGHP. This study aims at how to to array the extraction and injection wells for stable circulating of groundwater and at evaluating the sustainable yield capacity of groundwater circulation between the two wells. The study site is located in Chuncheon, Republic of Korea. Pumping tests were conducted to estimate transmissivity of the two wells (W3, W4). In addition, the step-circulation tests were conducted to estimate the sustainable yield capacity. Transmissivity of W3 and W4 was estimated to be 5.81 x 10^-5 m^2/s and 2.57 x 10^-5 m^2/s, respectively. Preliminary groundwater circulation tests were conducted to figure out the array of the extraction and injection wells. Circulation tests were performed for two cases: first, extraction well was set at the well with higher transmissivity and injection well set at the well with lower transmissivity, and the opposite array was set for the second case. In the first case, when flow rate was set at 70.47 m^3/day, the water level of W3 fell 0.61m and that of W4 rose 1.89m. In the second case, when flow rate was set at 67.70 m^3/day, the water level of W4 fell 2.17m and that of W3 rose 0.5m. Preliminary groundwater

  14. Heat as a Tracer for Estimation of Soil Drainage Following Irrigation Above a Tile Drain System

    NASA Astrophysics Data System (ADS)

    Callaghan, M. V.; Bentley, L. R.; Cey, E. E.

    2009-05-01

    Salt-affected soil is one of the most common environmental issues facing the petroleum hydrocarbon industry. Large quantities of brines are often co-produced with gas and oil and have been introduced into the environment through, for example, flare pits, drilling operations and pipe line breaks. Salt must be flushed from the soil and tile drain systems can be used to collect salt water which is then be routed for disposal. An accelerated remediation experiment by soil flushing over a 2 m deep tile drain system was monitored by tensiometers, and thermocouples. Water table elevation was monitored with pressure transducers. A 20 m by 20 m experimental plot was irrigated with 10 m3 of water on each of three consecutive days for an approximate total of 75 mm of water. The irrigation event was repeated three times over a period of 4 weeks. Due to a lack of access to the individual tile drains, direct measurement of drainage rates was not possible. One component of evaluating the success of the accelerated remediation experiment is the fraction of applied irrigation water that infiltrated to depth. Drainage rates beneath the irrigated plot were estimated by heat transport modeling using HYDRUS-1D, a numerical code for the solution of Richards unsaturated flow equation and the heat equation. Temperature and soil matric potential time series were recorded beneath the irrigated plot and at a control location at four depths, 0.3, 0.6, 1.0, and 1.5 m, at 15 minute intervals. Data was recorded for the duration of the irrigation period and for 8 weeks following. The temperature time series beneath the irrigated plot shows a broad increase relative to the control and shorter duration increases in direct response to the irrigation events. Heat modelling results are compared to field measurements.

  15. 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

  16. Latent class instrumental variables: a clinical and biostatistical perspective.

    PubMed

    Baker, Stuart G; Kramer, Barnett S; Lindeman, Karen S

    2016-01-15

    In some two-arm randomized trials, some participants receive the treatment assigned to the other arm as a result of technical problems, refusal of a treatment invitation, or a choice of treatment in an encouragement design. In some before-and-after studies, the availability of a new treatment changes from one time period to this next. Under assumptions that are often reasonable, the latent class instrumental variable (IV) method estimates the effect of treatment received in the aforementioned scenarios involving all-or-none compliance and all-or-none availability. Key aspects are four initial latent classes (sometimes called principal strata) based on treatment received if in each randomization group or time period, the exclusion restriction assumption (in which randomization group or time period is an instrumental variable), the monotonicity assumption (which drops an implausible latent class from the analysis), and the estimated effect of receiving treatment in one latent class (sometimes called efficacy, the local average treatment effect, or the complier average causal effect). Since its independent formulations in the biostatistics and econometrics literatures, the latent class IV method (which has no well-established name) has gained increasing popularity. We review the latent class IV method from a clinical and biostatistical perspective, focusing on underlying assumptions, methodological extensions, and applications in our fields of obstetrics and cancer research. PMID:26239275

  17. Inverse heat transfer problem of thermal contact conductance estimation in periodically contacting surfaces

    NASA Astrophysics Data System (ADS)

    Shojaeefard, M. H.; Goudarzi, K.; Mazidi, M. Sh.

    2009-06-01

    The problems involving periodic contacting surfaces have different practical applications. An inverse heat conduction problem for estimating the periodic Thermal Contact Conductance (TCC) between one-dimensional, constant property contacting solids has been investigated with conjugate gradient method (CGM) of function estimation. This method converges very rapidly and is not so sensitive to the measurement errors. The advantage of the present method is that no a priori information is needed on the variation of the unknown quantities, since the solution automatically determines the functional form over the specified domain. A simple, straight forward technique is utilized to solve the direct, sensitivity and adjoint problems, in order to overcome the difficulties associated with numerical methods. Two general classes of results, the results obtained by applying inexact simulated measured data and the results obtained by using data taken from an actual experiment are presented. In addition, extrapolation method is applied to obtain actual results. Generally, the present method effectively improves the exact TCC when exact and inexact simulated measurements input to the analysis. Furthermore, the results obtained with CGM and the extrapolation results are in agreement and the little deviations can be negligible.

  18. Modeling and Syndromic Surveillance for Estimating Weather-Induced Heat-Related Illness

    PubMed Central

    Perry, Alexander G.; Korenberg, Michael J.; Hall, Geoffrey G.; Moore, Kieran M.

    2011-01-01

    This paper compares syndromic surveillance and predictive weather-based models for estimating emergency department (ED) visits for Heat-Related Illness (HRI). A retrospective time-series analysis of weather station observations and ICD-coded HRI ED visits to ten hospitals in south eastern Ontario, Canada, was performed from April 2003 to December 2008 using hospital data from the National Ambulatory Care Reporting System (NACRS) database, ED patient chief complaint data collected by a syndromic surveillance system, and weather data from Environment Canada. Poisson regression and Fast Orthogonal Search (FOS), a nonlinear time series modeling technique, were used to construct models for the expected number of HRI ED visits using weather predictor variables (temperature, humidity, and wind speed). Estimates of HRI visits from regression models using both weather variables and visit counts captured by syndromic surveillance as predictors were slightly more highly correlated with NACRS HRI ED visits than either regression models using only weather predictors or syndromic surveillance counts. PMID:21647355

  19. Estimation of the fragility index of indomethacin by DSC using the heating and cooling rate dependency of the glass transition.

    PubMed

    Ramos, Joaquim J Moura; Taveira-Marques, Raquel; Diogo, Hermínio P

    2004-06-01

    In this study we have investigated the features of the glass transition relaxation of indomethacin using Differential Scanning Calorimetry (DSC). The purpose of this work is to provide an estimation of the activation energy at the glass transition temperature, as well as of the fragility index, of amorphous indomethacin from DSC data. To do so, the glass transition temperature region of amorphous indomethacin was characterized in both cooling and heating regimes. The activation energy for structural relaxation (directly related to glass fragility) was estimated from the heating and cooling rate dependence of the location of the DSC profile of the glass transition. The obtained results were similar in the heating and in the cooling modes. The results on the fragility index of indomethacin obtained in the present study, m = 60 in the cooling mode and m = 56 in the heating mode, are compared with other values previously published in the literature. PMID:15124208

  20. Heat discharge estimation using satellite remote sensing data on the Iwodake volcano in Satsuma-Iwojima, Japan

    NASA Astrophysics Data System (ADS)

    Urai, Minoru

    2002-03-01

    A series of heat discharges from the Iwodake volcano was estimated using nighttime Landsat TM data. The data includes heat discharge only from steaming ground and excludes fumarole, hot spring activities and others. The heat discharge was estimated at 40-80 MW from 1989 to 1993 using temperature distributions derived from Landsat TM band 6, and started to increase since 1995. From the error analysis, the true heat discharge will be in the range from -60% to +20% of the calculated discharge of this method. Two hot spots in the northeast to southwest direction correspond to the high temperature fumaroles seen in the temperature distributions derived from band 7. A new hot spot corresponds to a new degassing vent has been observed on the southern end of the summit crater since January 1992, and expanded to the same size as the other two hot spots since December 1993.

  1. Estimation of the magmatic gas and heat flux through the Etnean volcanic aquifer

    NASA Astrophysics Data System (ADS)

    D'Alessandro, Walter

    2010-05-01

    Etna volcano, Italy, hosts one of the major groundwater systems of the island of Sicily. Waters circulate within highly permeable fractured, mainly hawaiitic, volcanic rocks. Aquifers are limited downwards by the underlying impermeable sedimentary terrains. Thickness of the volcanic rocks generally does not exceed some 300 m, preventing the waters to reach great depths. This is faced by short travel times (years to tens of years) and low thermalisation of the Etnean groundwaters. Measured temperatures are, in fact, generally lower than 25 °C. But the huge annual meteoric recharge (about 0.97 km^3) with a high actual infiltration coefficient (0.75) implies a great underground circulation. During their travel from the summit area to the periphery of the volcano, waters acquire magmatic heat together with volcanic gases and solutes through water-rock interaction processes. In the last 20 years the Etnean aquifers has been extensively studied. Their waters were analysed for dissolved major, minor and trace element, O, H, C, S, B, Sr and He isotopes, and dissolved gas composition. These data have been published in several articles. Here, after a summary of the obtained results, the estimation of the magmatic heat flux through the aquifer will be discussed. To calculate heat uptake during subsurface circulation, for each sampling point (spring, well or drainage gallery) the following data have been considered: flow rate, water temperature, and oxygen isotopic composition. The latter was used to calculate the mean recharge altitude through the measured local isotopic lapse rate. Mean recharge temperatures, weighted for rain amount throughout the year, were obtained from the local weather station network. Calculations were made for a representative number of sampling points (216) including all major issues and corresponding to a total water flow of about 0.315 km^3/a, which is 40% of the effective meteoric recharge. Results gave a total energy output of about 140 MW/a the

  2. Analysis of the surface heat balance over the world ocean

    NASA Technical Reports Server (NTRS)

    Esbensen, S. K.

    1981-01-01

    It is possible to estimate long term monthly mean latent and sensible heat fluxes over the ocean to within or approximately 20% relative accuracy of the bulk aerodynamic formulas, by using observations of the monthly mean surface wind speed and the monthly mean sea air temperature and humidity differences. It is possible to make an estimate of the fluxes on a month to month basis from monthly averaged surface data.

  3. Estimation of surface energy balance from radiant surface temperature and NOAA AVHRR sensor reflectances over agricultural and native vegetation. [AVHRR (advanced very high resolution radiometer)

    SciTech Connect

    Huang Xinmei; Lyons, T.J. ); Smith, R.C.G. ); Hacker, J.M.; Schwerdtfeger, P. )

    1993-08-01

    A model is developed to evaluate surface heat flux densities using the radiant surface temperature and red and near-infrared reflectances from the NOAA Advanced Very High Resolution Radiometer sensor. Net radiation is calculated from an empirical formulation and albedo estimated from satellite observations. Infrared surface temperature is corrected to aerodynamic surface temperature in estimating the sensible heat flux and the latent flux is evaluated as the residual of the surface energy balance. When applied to relatively homogeneous agricultural and native vegetation, the model yields realistic estimates of sensible and latent heat flux density in the surface layer for cases where either the sensible or latent flux dominates. 29 refs., 10 figs., 3 tabs.

  4. 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

  5. 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

  6. 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

  7. Influence of paleo-heat flow variations on estimates of exhumation rates

    NASA Astrophysics Data System (ADS)

    von Hagke, Christoph; Luijendijk, Elco

    2016-04-01

    Deriving exhumation estimates from thermochronological data requires assumptions on the paleo-thermal field of the Earth's crust. Existing thermal models take into account heat transfer by diffusion and advection caused by the movement of the crust and erosion as well as changes in geothermal gradient over time caused by changes in structure or thermal properties of the crust, surface temperature and elevation. However, temperature field of mountain belts and basins may vary not only due to tectonic activity or landscape evolution. We present a high-resolution thermochronology data set from the foreland fold-and-thrust belt of the European Alps that shows substantial variation of cooling rates probably caused by hydrothermal flow in the subsurface in the past. Tectonic blocks with uniform exhumation history show variations in cooling of up to 50°C. In addition, changes in cooling between two different fault blocks show opposite trend than expected by models of their tectonic history. The observed historic changes in paleo-geothermal gradients are equal in magnitude to a present-day thermal anomaly caused by the upward flow of warm fluids in the distal part of the foreland basin. The strong variations in geothermal gradients by fluid flow imply that straightforward interpretation of landscape evolution rates using thermochronology is not possible, unless the thermal effects of fluid flow are taken into account. This is of particular importance to studies where the amount of thermochronology data is limited and local hydrothermal anomalies could easily be interpreted as regional exhumation signals. On the other hand, our findings suggest that thermochronology offers new opportunities to constrain magnitude and timing of paleo-heat flow variations in the upper crust.

  8. Realistic Probability Estimates For Destructive Overpressure Events In Heated Center Wing Tanks Of Commercial Jet Aircraft

    SciTech Connect

    Alvares, N; Lambert, H

    2007-02-07

    The Federal Aviation Administration (FAA) identified 17 accidents that may have resulted from fuel tank explosions on commercial aircraft from 1959 to 2001. Seven events involved JP 4 or JP 4/Jet A mixtures that are no longer used for commercial aircraft fuel. The remaining 10 events involved Jet A or Jet A1 fuels that are in current use by the commercial aircraft industry. Four fuel tank explosions occurred in center wing tanks (CWTs) where on-board appliances can potentially transfer heat to the tank. These tanks are designated as ''Heated Center Wing Tanks'' (HCWT). Since 1996, the FAA has significantly increased the rate at which it has mandated airworthiness directives (ADs) directed at elimination of ignition sources. This effort includes the adoption, in 2001, of Special Federal Aviation Regulation 88 of 14 CFR part 21 (SFAR 88 ''Fuel Tank System Fault Tolerance Evaluation Requirements''). This paper addresses SFAR 88 effectiveness in reducing HCWT ignition source probability. Our statistical analysis, relating the occurrence of both on-ground and in-flight HCWT explosions to the cumulative flight hours of commercial passenger aircraft containing HCWT's reveals that the best estimate of HCWT explosion rate is 1 explosion in 1.4 x 10{sup 8} flight hours. Based on an analysis of SFAR 88 by Sandia National Laboratories and our independent analysis, SFAR 88 reduces current risk of historical HCWT explosion by at least a factor of 10, thus meeting an FAA risk criteria of 1 accident in billion flight hours. This paper also surveys and analyzes parameters for Jet A fuel ignition in HCWT's. Because of the paucity of in-flight HCWT explosions, we conclude that the intersection of the parameters necessary and sufficient to result in an HCWT explosion with sufficient overpressure to rupture the HCWT is extremely rare.

  9. Single-ion heat capacities, C(p)(298)ion, of solids: with a novel route to heat-capacity estimation of complex anions.

    PubMed

    Glasser, Leslie; Jenkins, H Donald Brooke

    2012-06-01

    Single-ion heat capacities, C(p)(298)(ion), are additive values for the estimation of room-temperature (298 K) heat capacities of ionic solids. They may be used for inferring the heat capacities of ionic solids for which values are unavailable and for checking reported values, thus complementing our independent method of estimation from formula unit volumes (termed volume-based thermodynamics, VBT). Analysis of the reported heat-capacity data presented here provides a new self-consistent set of heat capacities for both cations and anions that is compatible (and thus may be combined) with an extensive set developed by Spencer. The addition of a large range of silicate species permits the estimation of the heat capacities of many silicate minerals. The single-ion heat capacities of individual silicate anions are observed to be strictly proportional to the total number of atoms (Si plus O), n, contained within the silicate anion complex itself (e.g., for the anion Si(2)O(7)(2-), n = 9, for SiO(4)(2-), n = 5), C(p)(silicate anion)/J K(-1) mol(-1) = 13.8n, in a new rule that is an extension of the Neumann-Kopp relationship. The same linear relationship applies to other homologous anion series (for example, oxygenated heavy-metal anion complexes such as niobates, bismuthates, and tantalates), although with a different proportionality constant. A similar proportionality, C(p)(complex anion)/J K(-1) mol(-1) ≈ 17.5n, which may be regarded as a convenient "rule of thumb", also applies, although less strictly, to complex anions in general. The proportionality constants reflect the rigidity of the complex anion, being always less than the Dulong-Petit value of 25 J K(-1) mol(-1). An emergent feature of our VBT and single-ion approaches to an estimation of the thermodynamic properties is the identification of anomalies in measured values, as is illustrated in this paper. PMID:22583202

  10. Thermographic imaging in the beating heart: a method for coronary flow estimation based on a heat transfer model.

    PubMed

    Gordon, N; Rispler, S; Sideman, S; Shofty, R; Beyar, R

    1998-09-01

    Intraoperative thermographic imaging in open-chest conditions can provide the surgeon with important qualitative information regarding coronary flow by utilizing heat transfer analysis following injection of cold saline into the aortic root. The heat transfer model is based on the assumption that the epicardial temperature changes are mainly due to convection of heat by the blood flow, which may, therefore, be estimated by measuring the temperature variations. Hearts of eight dogs were exposed and imaged by a thermographic camera. Flow in the left arterial descending (LAD) coronary branch was measured by a transit-time flowmeter. 20 ml of cold saline were injected into the aortic root (just after the aortic valve) and the epicardial temperature images were recorded at end-diastole, for 20-30 s. Different flow rates were achieved by 1 min occlusion of the LAD, which affected a reactive hyperemic response. The dynamics of the temperature in the arterial coronary tree was obtained by averaging the temperature over an edge-detected arterial segment for each frame. The heat transfer equation was curve-fitted, and the flow-dependent heat transfer index was correlated with the experimentally determined coronary flow (r = 0.69, p < 0.001). In summary: a method for quantitative estimation of coronary blood flow by thermography and heat transfer analysis was developed and tested in animal experiments. This method can provide important information regarding coronary blood flow during open-chest surgical procedures. PMID:9796950

  11. Estimating Water and Heat Fluxes with a Four-dimensional Weak-constraint Variational Data Assimilation Approach

    NASA Astrophysics Data System (ADS)

    Bateni, S. M.; Xu, T.

    2015-12-01

    Accurate estimation of water and heat fluxes is required for irrigation scheduling, weather prediction, and water resources planning and management. A weak-constraint variational data assimilation (WC-VDA) scheme is developed to estimate water and heat fluxes by assimilating sequences of land surface temperature (LST) observations. The commonly used strong-constraint VDA systems adversely affect the accuracy of water and heat flux estimates as they assume the model is perfect. The WC-VDA approach accounts for structural and model errors and generates more accurate results via adding a model error term into the surface energy balance equation. The two key unknown parameters of the WC-VDA system (i.e., CHN, the bulk heat transfer coefficient and EF, evaporative fraction) and the model error term are optimized by minimizing the cost function. The WC-VDA model was tested at two sites with contrasting hydrological and vegetative conditions: the Daman site (a wet site located in an oasis area and covered by seeded corn) and the Huazhaizi site (a dry site located in a desert area and covered by sparse grass) in middle stream of Heihe river basin, northwest China. Compared to the strong-constraint VDA system, the WC-VDA method generates more accurate estimates of water and energy fluxes over the desert and oasis sites with dry and wet conditions.

  12. Effects of Spontaneous Heating on Estimates of TDN for Alfalfa-Orchardgrass Hays Packaged in Large-Round Bales

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large-round or large-square hay packages are more likely to heat spontaneously during storage than hay packaged in conventional (45-kg) bales, and the consequences of this phenomenon on the resulting forage energy estimates for these hays can be severe. Our objectives for this project were to assess...

  13. The Surface Heat Flux as a Function of Ground Cover for Climate Models

    NASA Technical Reports Server (NTRS)

    Vukovich, Fred M.; Wayland, Robert; Toll, David

    1997-01-01

    Surface heat fluxes were examined as a function of surface properties and meteorological conditions in a 100 km x 100 km grid square at 1-km spatial resolution centered at the location of the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE), the Forest Ecosystem Dynamics site in central Maine, and a semiarid rangeland site around Walnut Gulch, Arizona. This investigation treats the surface heat flux variability within a GCM grid box to provide insight into methods for treating that variability in climate models. The heat fluxes were calculated using NOAA AVHRR and available meteorological data. The average heat fluxes that were estimated using the various area ground-cover representations were compared with the ensemble average heat fluxes for the entire area, which were assumed to be the best representation of the heat fluxes for the areas. Average beat fluxes were estimated for the entire 100 km x 100 km area based on a single ground-cover representation, and the mean error for the area sensible heat flux was about 10% and for the area latent heat flux, 21%. The estimation error was reduced, and in some cases significantly reduced, when the area heat fluxes were estimated by partitioning the area according to significant ground cover. The most significant effect of the partitioning was on the latent heat flux estimates.

  14. Interpretation of lunar heat flow data. [for estimating bulk uranium abundance

    NASA Technical Reports Server (NTRS)

    Conel, J. E.; Morton, J. B.

    1975-01-01

    Lunar heat flow observations at the Apollo 15 and 17 sites can be interpreted to imply bulk U concentrations for the moon of 5 to 8 times those of normal chondrites and 2 to 4 times terrestrial values inferred from the earth's heat flow and the assumption of thermal steady state between surface heat flow and heat production. A simple model of nearsurface structure that takes into account the large difference in (highly insulating) regolith thickness between mare and highland provinces is considered. This model predicts atypically high local values of heat flow near the margins of mare regions - possibly a factor of 10 or so higher than the global average. A test of the proposed model using multifrequency microwave techniques appears possible wherein heat flow traverse measurements are made across mare-highland contacts. The theoretical considerations discussed here urge caution in attributing global significance to point heat-flow measurements on the moon.

  15. A multi-method and multi-scale approach for estimating city-wide anthropogenic heat fluxes

    NASA Astrophysics Data System (ADS)

    Chow, Winston T. L.; Salamanca, Francisco; Georgescu, Matei; Mahalov, Alex; Milne, Jeffrey M.; Ruddell, Benjamin L.

    2014-12-01

    A multi-method approach estimating summer waste heat emissions from anthropogenic activities (QF) was applied for a major subtropical city (Phoenix, AZ). These included detailed, quality-controlled inventories of city-wide population density and traffic counts to estimate waste heat emissions from population and vehicular sources respectively, and also included waste heat simulations derived from urban electrical consumption generated by a coupled building energy - regional climate model (WRF-BEM + BEP). These component QF data were subsequently summed and mapped through Geographic Information Systems techniques to enable analysis over local (i.e. census-tract) and regional (i.e. metropolitan area) scales. Through this approach, local mean daily QF estimates compared reasonably versus (1.) observed daily surface energy balance residuals from an eddy covariance tower sited within a residential area and (2.) estimates from inventory methods employed in a prior study, with improved sensitivity to temperature and precipitation variations. Regional analysis indicates substantial variations in both mean and maximum daily QF, which varied with urban land use type. Average regional daily QF was ∼13 W m-2 for the summer period. Temporal analyses also indicated notable differences using this approach with previous estimates of QF in Phoenix over different land uses, with much larger peak fluxes averaging ∼50 W m-2 occurring in commercial or industrial areas during late summer afternoons. The spatio-temporal analysis of QF also suggests that it may influence the form and intensity of the Phoenix urban heat island, specifically through additional early evening heat input, and by modifying the urban boundary layer structure through increased turbulence.

  16. Tests of a robust eddy correlation system for sensible heat flux

    NASA Astrophysics Data System (ADS)

    Blanford, J. H.; Gay, L. W.

    1992-03-01

    Sensible heat flux estimates from a simple, one-propeller eddy correlation system (OPEC) were compared with those from a sonic anemometer eddy correlation system (SEC). In accordance with similarity theory, the performance of the OPEC system improved with increasing height of the sensor above the surface. Flux totals from the two systems at sites with adequate fetch were in excellent agreement after frequency response corrections were applied. The propeller system appears suitable for long periods of unattended measurement. The sensible heat flux measurements can be combined with net radiation and soil heat flux measurements to estimate latent heat as a residual in the surface energy balance.

  17. A Composite Likelihood Inference in Latent Variable Models for Ordinal Longitudinal Responses

    ERIC Educational Resources Information Center

    Vasdekis, Vassilis G. S.; Cagnone, Silvia; Moustaki, Irini

    2012-01-01

    The paper proposes a composite likelihood estimation approach that uses bivariate instead of multivariate marginal probabilities for ordinal longitudinal responses using a latent variable model. The model considers time-dependent latent variables and item-specific random effects to be accountable for the interdependencies of the multivariate…

  18. Causal Latent Markov Model for the Comparison of Multiple Treatments in Observational Longitudinal Studies

    ERIC Educational Resources Information Center

    Bartolucci, Francesco; Pennoni, Fulvia; Vittadini, Giorgio

    2016-01-01

    We extend to the longitudinal setting a latent class approach that was recently introduced by Lanza, Coffman, and Xu to estimate the causal effect of a treatment. The proposed approach enables an evaluation of multiple treatment effects on subpopulations of individuals from a dynamic perspective, as it relies on a latent Markov (LM) model that is…

  19. Using Design-Based Latent Growth Curve Modeling with Cluster-Level Predictor to Address Dependency

    ERIC Educational Resources Information Center

    Wu, Jiun-Yu; Kwok, Oi-Man; Willson, Victor L.

    2014-01-01

    The authors compared the effects of using the true Multilevel Latent Growth Curve Model (MLGCM) with single-level regular and design-based Latent Growth Curve Models (LGCM) with or without the higher-level predictor on various criterion variables for multilevel longitudinal data. They found that random effect estimates were biased when the…

  20. Confidence Intervals for a Semiparametric Approach to Modeling Nonlinear Relations among Latent Variables

    ERIC Educational Resources Information Center

    Pek, Jolynn; Losardo, Diane; Bauer, Daniel J.

    2011-01-01

    Compared to parametric models, nonparametric and semiparametric approaches to modeling nonlinearity between latent variables have the advantage of recovering global relationships of unknown functional form. Bauer (2005) proposed an indirect application of finite mixtures of structural equation models where latent components are estimated in the…

  1. Multilevel Latent Class Models with Dirichlet Mixing Distribution

    PubMed Central

    Di, Chong-Zhi; Bandeen-Roche, Karen

    2010-01-01

    Summary Latent class analysis (LCA) and latent class regression (LCR) are widely used for modeling multivariate categorical outcomes in social science and biomedical studies. Standard analyses assume data of different respondents to be mutually independent, excluding application of the methods to familial and other designs in which participants are clustered. In this paper, we consider multilevel latent class models, in which subpopulation mixing probabilities are treated as random effects that vary among clusters according to a common Dirichlet distribution. We apply the Expectation-Maximization (EM) algorithm for model fitting by maximum likelihood (ML). This approach works well, but is computationally intensive when either the number of classes or the cluster size is large. We propose a maximum pairwise likelihood (MPL) approach via a modified EM algorithm for this case. We also show that a simple latent class analysis, combined with robust standard errors, provides another consistent, robust, but less efficient inferential procedure. Simulation studies suggest that the three methods work well in finite samples, and that the MPL estimates often enjoy comparable precision as the ML estimates. We apply our methods to the analysis of comorbid symptoms in the Obsessive Compulsive Disorder study. Our models' random effects structure has more straightforward interpretation than those of competing methods, thus should usefully augment tools available for latent class analysis of multilevel data. PMID:20560936

  2. Estimating the Heat and Mass Flux at the ASHES Hydrothermal Vent Field with the Sentry Autonomous Underwater Vehicle

    NASA Astrophysics Data System (ADS)

    Kinsey, J. C.; Crone, T. J.; Mittelstaedt, E. L.; Medagoda, L.; Fourie, D.; Nakamura, K.

    2014-12-01

    Hydrothermal venting influences ocean chemistry, the thermal and chemical structure of the oceanic crust, the style of accretion at mid-ocean ridges, and the evolution of unique and diverse chemosynthetic ecosystems. Surprisingly, only a few studies have attempted to constrain the volume and heat flux of entire hydrothermal vent fields given that axially-hosted hydrothermal systems are estimated to be responsible for ~20-25% of the total heat flux out of the Earth's interior, as well as potentially playing a large role in global and local biogeochemical cycles. However, same-site estimates can vary greatly, such as at the Lucky Strike Field where estimates range from 100 MW to 3800 MW. We report a July 2014 field program with the Sentry AUV that obtains the water velocity and heat measurements necessary to estimate the total heat and mass flux emanating from the ASHES hydrothermal vent field. We equipped Sentry with a Nortek acoustic Doppler velocimeter (ADV) with an inertial measurement unit attached, two acoustic Doppler current profilers (ADCPs), and two SBE3 temperature probes, to measure the temperature and water velocity. This sensing suite provided more accurate measurements than previous AUV based studies. A control volume approach was employed in which Sentry was pre-programmed to survey a 150m by 150m box centered over the vent field flying a "mowing the lawn" pattern at 5m trackline spacing followed by a survey of the perimeter. During a 40 hour survey, the pattern was repeated 9 times allowing us to obtain observations over multiple tidal cycles. Concurrent lowered ADCP (LADCP) measurements were also obtained. Water velocity data obtained with Sentry was corrected for platform motion and then combined with the temperature measurements to estimate heat flux. Analysis of this data is on-going, however these experiments permit us to quantify the heat and mass exiting the control volume, and potentially provide the most accurate and highest resolution heat

  3. On the estimation of heating effects in the atmosphere because of seismic activities

    NASA Astrophysics Data System (ADS)

    Meister, Claudia-Veronika; Hoffmann, Dieter H. H.

    2014-05-01

    The dielectric model for waves in the Earth's ionosphere is further developed and applied to possible electro-magnetic phenomena in seismic regions. In doing so, in comparison to the well-known dielectric wave model by R.O. Dendy [Plasma dynamics, Oxford University Press, 1990] for homogeneous systems, the stratification of the atmosphere is taken into account. Moreover, within the frame of many-fluid magnetohydrodynamics also the momentum transfer between the charged and neutral particles is considered. Discussed are the excitation of Alfvén and magnetoacoustic waves, but also their variations by the neutral gas winds. Further, also other current driven waves like Farley-Buneman ones are studied. In the work, models of the altitudinal scales of the plasma parameters and the electromagnetic wave field are derived. In case of the electric wave field, a method is given to calculate the altitudinal scale based on the Poisson equation for the electric field and the magnetohydrodynamic description of the particles. Further, expressions are derived to estimate density, pressure, and temperatur changes in the E-layer because of the generation of the electromagnetic waves. Last not least, formulas are obtained to determine the dispersion and polarisation of the excited electromagnetic waves. These are applied to find quantitative results for the turbulent heating of the ionospheric E-layer. Concerning the calculation of the dispersion relation, in comparison to a former work by Meister et al. [Contr. Plasma Phys. 53 (4-5), 406-413, 2013], where a numerical double-iteration method was suggested to obtain results for the wave dispersion relations, now further analytical calculations are performed. In doing so, different polynomial dependencies of the wave frequencies from the wave vectors are treated. This helped to restrict the numerical calculations to only one iteration process.

  4. Estimation of surface temperature distributions during heating of particles in fluidized bed

    SciTech Connect

    Dincer, I.; Dost, S.

    1996-10-01

    Unsteady heat transfer with internal heat generation takes place during the heating of solid particles in a fluidized bed combustor before the initiation of shrinkages due to burning, i.e., during the period before the inside temperature in the solid particle reaches the medium temperature. The analysis of heat transfer occurring in such particles is essential for accurate predictions of optimum heating requirements, leading to energy savings. Such analysis requires an accurate measurement of the surface temperatures of these particles, which is very difficult to achieve in practice. Therefore an analytical model determining surface temperature distributions using either center temperature measurements or other available heat transfer parameters, such as Biot and Fourier numbers is desirable. Such an analytical technique is presented in this article. The present approach is illustrated by an example using two different experimental temperature data sets. Obtained center and surface temperature distributions are plotted for comparison.

  5. An Assessment of Transport Property Estimation Methods for Ammonia-Water Mixtures and Their Influence on Heat Exchanger Size

    NASA Astrophysics Data System (ADS)

    Kærn, M. R.; Modi, A.; Jensen, J. K.; Haglind, F.

    2015-07-01

    Transport properties of fluids are indispensable for heat exchanger design. The methods for estimating the transport properties of ammonia-water mixtures are not well established in the literature. The few existent methods are developed from none or limited, sometimes inconsistent experimental datasets, conducted for the liquid phase only. These datasets are usually confined to low concentrations and temperatures, which are much less than those occurring in Kalina cycle boilers. This paper presents a comparison of various methods used to estimate the viscosity and the thermal conductivity of ammonia-water mixtures. Firstly, the different methods are introduced and compared at various temperatures and pressures. Secondly, their individual influence on the required heat exchanger size (surface area) is investigated. For this purpose, two case studies related to the use of the Kalina cycle are considered: a flue-gas-based heat recovery boiler for a combined cycle power plant and a hot-oil-based boiler for a solar thermal power plant. The different transport property methods resulted in larger differences at high pressures and temperatures, and a possible discontinuous first derivative, when using the interpolative methods in contrast to the corresponding state methods. Nevertheless, all possible mixture transport property combinations used herein resulted in a heat exchanger size within 4.3 % difference for the flue-gas heat recovery boiler, and within 12.3 % difference for the oil-based boiler.

  6. Estimated Moho Temperature from Observed Heat Flow and Comparison with P-Wave Velocity in the East Sea, Korea

    NASA Astrophysics Data System (ADS)

    Jung, W. Y.; Wood, W. T.

    2014-12-01

    We have estimated temperatures at the Moho surface by employing a published empirical relationship of Perry et al's work (JGR, doi:10.1029/2005JB003921) to the observed heat flow measurements in the East Sea (Sea of Japan), Korea. We assumed in our computation that the parameter values are all the same although the Perry et al's relationship between crustal thickness and heat flows to compute Moho temperature was derived for the Canadian Shield. For the heat flow data, we used the published global heat flow data (http://www.heatflow.und.edu) augmented with some recent heat flow measurements from Korea, and the LLN3_G3Dv3 for P-wave tomography model (JGR, doi:10.1029/2012JB009525). Preliminary results do not show a significant correlation between the computed Moho temperature and the P-wave velocity model perhaps due to uncertainty in the parameter values used in the computation as well as the empirical relation. An empirical relationship between the observed heat flow and the Moho temperature for the Canadian shield might be different for a backarec basin area like the East Sea, Korea. However, we noted that there exists a moderate negative correlation between the total crustal thickness and heat flow - less heat flows with increasing crustal thickness with a relation of Heat_Flow (mW/m2) = 205 - 18.3 * Crustal_Thickness (km). The modeled Moho temperature displays a trend of higher values (900o K -1400o K) from Japan toward the beneath of Yamato Basin and Rise in the NW direction, and beneath the Ulleung Basin area. Another higher Moho temperature (>1000o K) contour band is observed in the area north of Japan Basin, approximately centered along the 139.5o E.

  7. 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…

  8. On Latent Change Model Choice in Longitudinal Studies

    ERIC Educational Resources Information Center

    Raykov, Tenko; Zajacova, Anna

    2012-01-01

    An interval estimation procedure for proportion of explained observed variance in latent curve analysis is discussed, which can be used as an aid in the process of choosing between linear and nonlinear models. The method allows obtaining confidence intervals for the R[squared] indexes associated with repeatedly followed measures in longitudinal…

  9. A MCMC-Method for Models with Continuous Latent Responses.

    ERIC Educational Resources Information Center

    Maris, Gunter; Maris, Eric

    2002-01-01

    Introduces a new technique for estimating the parameters of models with continuous latent data. To streamline presentation of this Markov Chain Monte Carlo (MCMC) method, the Rasch model is used. Also introduces a new sampling-based Bayesian technique, the DA-T-Gibbs sampler. (SLD)

  10. Diagnostic Procedures for Detecting Nonlinear Relationships between Latent Variables

    ERIC Educational Resources Information Center

    Bauer, Daniel J.; Baldasaro, Ruth E.; Gottfredson, Nisha C.

    2012-01-01

    Structural equation models are commonly used to estimate relationships between latent variables. Almost universally, the fitted models specify that these relationships are linear in form. This assumption is rarely checked empirically, largely for lack of appropriate diagnostic techniques. This article presents and evaluates two procedures that can…

  11. Latent Growth Curves within Developmental Structural Equation Models.

    ERIC Educational Resources Information Center

    McArdle, J. J.; Epstein, David

    1987-01-01

    Uses structural equation modeling to combine traditional ideas from repeated-measures ANOVA with some traditional ideas from longitudinal factor analysis. The model describes a latent growth curve model that permits the estimation of parameters representing individual and group dynamics. (Author/RH)

  12. Linking Academic Entitlement and Student Incivility Using Latent Means Modeling

    ERIC Educational Resources Information Center

    Kopp, Jason P.; Finney, Sara J.

    2013-01-01

    Academic entitlement has been theoretically linked with uncivil student behavior; however, this relationship has not been tested. To address this gap in the literature, the authors used latent means modeling to estimate the relationship between the Academic Entitlement Questionnaire and uncivil student behavior. The authors gathered scores on the…

  13. 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.

  14. Estimation of sediment friction coefficient from heating upon APC penetration during the IODP NanTroSEIZE

    NASA Astrophysics Data System (ADS)

    Kinoshita, M.; Kawamura, K.; Lin, W.

    2015-12-01

    During the Nankai Trough Seismogenic Zone Experiments (NanTroSEIZE) of the Integrated Ocean Drilling Program (IODP), the advanced piston corer temperature (APC-T) tool was used to determine in situ formation temperatures while piston coring down to ~200 m below sea floor. When the corer is fired into the formation, temperature around the shoe abruptly increases due to the frictional heating. The temperature rise due to the frictional heat at the time of penetration is 10 K or larger. We found that the frictional temperature rise (=maximum temperature) increases with increasing depth, and that its intersection at the seafloor seems non-zero. Frictional heat energy is proportional to the maximum temperature rise, which is confirmed by a FEM numerical simulation of 2D cylindrical system. Here we use the result of numerical simulation to convert the observed temperature rise into the frictional heat energy. The frictional heat energy is represented as the product of the shooting length D and the shear stress (τ) between the pipe and the sediment. Assuming a coulomb slip regime, the shear stress is shows as: τ= τ0 + μ*(Sv-Pp), where τ0 is the cohesive stress, μ the dynamic frictional coefficient between the pipe and the sediment, Sv the normal stress at the pipe, and Pp the pore pressure. This can explain the non-zero intersection as well as depth-dependent increase for the frictional heating observed in the APC-T data. Assuming a hydrostatic state and by using the downhole bulk density data, we estimated the friction coefficient for each APC-T measurement. For comparison, we used the vane-shear strength measured on core samples to estimate the friction coefficients. The frictional coefficients μ were estimated as ranging 0.01 - 0.06, anomalously lower than expected for shallow marine sediments. They were lower than those estimated from vane-shear data, which range 0.05 to 0.2. Still, both estimates exhibit a significant increase in the friction coefficient at

  15. Using MODIS and AVHRR data to determine regional surface heating field and heat flux distributions over the heterogeneous landscape of the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Ma, Yaoming; Han, Cunbo; Zhong, Lei; Wang, Binbin; Zhu, Zhikun; Wang, Yongjie; Zhang, Lang; Meng, Chunchun; Xu, Chao; Amatya, Pukar Man

    2014-08-01

    In this study, a parameterization methodology based on Advanced Very High-Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), and in situ data is proposed and tested for deriving the regional surface heating field, sensible heat flux, and latent heat flux over a heterogeneous landscape. In this case study, this method is applied to the whole Tibetan Plateau (TP) area. Four sets of AVHRR data and four sets of MODIS data (collected on 17 January 2003, 14 April 2003, 23 July 2003, and 16 October 2003) were used in this study to make comparisons between winter, spring, summer, and autumn values. The satellite-derived results were also validated using the "ground truth" as measured in the stations of CAMP/Tibet (Coordinated Enhanced Observing Period (CEOP) and Asia-Australia Monsoon Project on the Tibetan Plateau). The results show that the surface heating field, sensible heat flux, and latent heat flux in the four seasons across the TP are in close accordance with its land surface status. These parameters range widely due to the strongly contrasting surface features found within the TP region. Also, the estimated surface heating field, sensible heat flux, and latent heat flux all agree with the ground truth data, and usually, the absolute percentage difference between the two sets of data is less than 10 % at the validation stations. The AVHRR results were also in agreement with the MODIS data, with the latter usually displaying a higher level of accuracy. We have thus concluded that the proposed method was successful in retrieving surface heating field, sensible heat flux, and latent heat flux values using AVHRR, MODIS, and in situ data over the heterogeneous land surface of the TP. Shortcomings and possible further improvements in the method are also discussed.

  16. 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

  17. Structural properties of magnetic nanoparticles determine their heating behavior - an estimation of the in vivo heating potential

    PubMed Central

    2014-01-01

    Magnetically induced heating of magnetic nanoparticles (MNP) in an alternating magnetic field (AMF) is a promising minimally invasive tool for localized tumor treatment by sensitizing or killing tumor cells with the help of thermal stress. Therefore, the selection of MNP exhibiting a sufficient heating capacity (specific absorption rate, SAR) to achieve satisfactory temperatures in vivo is necessary. Up to now, the SAR of MNP is mainly determined using ferrofluidic suspensions and may distinctly differ from the SAR in vivo due to immobilization of MNP in tissues and cells. The aim of our investigations was to study the correlation between the SAR and the degree of MNP immobilization in dependence of their physicochemical features. In this study, the included MNP exhibited varying physicochemical properties and were either made up of single cores or multicores. Whereas the single core MNP exhibited a core size of approximately 15 nm, the multicore MNP consisted of multiple smaller single cores (5 to 15 nm) with 65 to 175 nm diameter in total. Furthermore, different MNP coatings, including dimercaptosuccinic acid (DMSA), polyacrylic acid (PAA), polyethylenglycol (PEG), and starch, wereinvestigated. SAR values were determined after the suspension of MNP in water. MNP immobilization in tissues was simulated with 1% agarose gels and 10% polyvinyl alcohol (PVA) hydrogels. The highest SAR values were observed in ferrofluidic suspensions, whereas a strong reduction of the SAR after the immobilization of MNP with PVA was found. Generally, PVA embedment led to a higher immobilization of MNP compared to immobilization in agarose gels. The investigated single core MNP exhibited higher SAR values than the multicore MNP of the same core size within the used magnetic field parameters. Multicore MNP manufactured via different synthesis routes (fluidMAG-D, fluidMAG/12-D) showed different SAR although they exhibited comparable core and hydrodynamic sizes. Additionally, no

  18. Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

    NASA Astrophysics Data System (ADS)

    Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

    2016-07-01

    The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

  19. Two Experiments for Estimating Free Convection and Radiation Heat Transfer Coefficients

    ERIC Educational Resources Information Center

    Economides, Michael J.; Maloney, J. O.

    1978-01-01

    This article describes two simple undergraduate heat transfer experiments which may reinforce a student's understanding of free convection and radiation. Apparatus, experimental procedure, typical results, and discussion are included. (Author/BB)

  20. Route Planning and Estimate of Heat Loss of Hot Water Transportation Piping for Fuel Cell Local Energy Network

    NASA Astrophysics Data System (ADS)

    Obara, Shinya; Kudo, Kazuhiko

    The method of supplying the electric power and heat energy for the energy demand of buildings by Centralized system type and distributed system type of fuel cell network is studied. The hot-water piping route planning program of fuel cell network was developed by using genetic algorithm based on the view of TSP ( Traveling salesman problem) . In this program, the piping route planning which minimizes the quantity of heat loss in hot-water piping can be performed. The residential section model of Sapporo city of 74 buildings was analyzed, and the quantity of heat loss from the hot-water piping of both systems was estimated. Consequently, the ratio of the quantity of heat loss of a distributed system to a centralized system was about 50% in the full year average. This program is introduced into the route planning of hot- Water piping system of the fuel cell network, and plan to reduce the quantity of heat loss in a distributed system will be made.