Multiple Scattering Principal Component-based Radiative Transfer Model (PCRTM) from Far IR to UV-Vis
Liu, X.; Wu, W.; Yang, Q.
2017-12-01
Modern satellite hyperspectral satellite remote sensors such as AIRS, CrIS, IASI, CLARREO all require accurate and fast radiative transfer models that can deal with multiple scattering of clouds and aerosols to explore the information contents. However, performing full radiative transfer calculations using multiple stream methods such as discrete ordinate (DISORT), doubling and adding (AD), successive order of scattering order of scattering (SOS) are very time consuming. We have developed a principal component-based radiative transfer model (PCRTM) to reduce the computational burden by orders of magnitudes while maintain high accuracy. By exploring spectral correlations, the PCRTM reduce the number of radiative transfer calculations in frequency domain. It further uses a hybrid stream method to decrease the number of calls to the computational expensive multiple scattering calculations with high stream numbers. Other fast parameterizations have been used in the infrared spectral region reduce the computational time to milliseconds for an AIRS forward simulation (2378 spectral channels). The PCRTM has been development to cover spectral range from far IR to UV-Vis. The PCRTM model have been be used for satellite data inversions, proxy data generation, inter-satellite calibrations, spectral fingerprinting, and climate OSSE. We will show examples of applying the PCRTM to single field of view cloudy retrievals of atmospheric temperature, moisture, traces gases, clouds, and surface parameters. We will also show how the PCRTM are used for the NASA CLARREO project.
Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region
Liu, Xu; Yang, Qiguang; Li, Hui; Jin, Zhonghai; Wu, Wan; Kizer, Susan; Zhou, Daniel K.; Yang, Ping
2016-01-01
A fast and accurate principal component-based radiative transfer model in the solar spectral region (PCRTMSOLAR) has been developed. The algorithm is capable of simulating reflected solar spectra in both clear sky and cloudy atmospheric conditions. Multiple scattering of the solar beam by the multilayer clouds and aerosols are calculated using a discrete ordinate radiative transfer scheme. The PCRTM-SOLAR model can be trained to simulate top-of-atmosphere radiance or reflectance spectra with spectral resolution ranging from 1 cm(exp -1) resolution to a few nanometers. Broadband radiances or reflectance can also be calculated if desired. The current version of the PCRTM-SOLAR covers a spectral range from 300 to 2500 nm. The model is valid for solar zenith angles ranging from 0 to 80 deg, the instrument view zenith angles ranging from 0 to 70 deg, and the relative azimuthal angles ranging from 0 to 360 deg. Depending on the number of spectral channels, the speed of the current version of PCRTM-SOLAR is a few hundred to over one thousand times faster than the medium speed correlated-k option MODTRAN5. The absolute RMS error in channel radiance is smaller than 10(exp -3) mW/cm)exp 2)/sr/cm(exp -1) and the relative error is typically less than 0.2%.
Training and Validation of the Fast PCRTM_Solar Model
Yang, Q.; Liu, X.; Wu, W.; Yang, P.; Wang, C.
2015-12-01
Fast and accurate radiative transfer model is the key for satellite data assimilation for remote sensing application. The simulation of the satellite remote sensing radiances is very complicated since many physical processes, such as absorption, emission, and scattering, are involved due to the interactions between electromagnetic radiation and earth surface, water vapor, clouds, aerosols, and gas molecules in the sky. The principal component-based radiative transfer model (PCRTM) has been developed for various passive IR and MW instruments. In this work, we extended PCRTM to including the contribution from solar radiation. The cloud/aerosol bidirectional reflectances have been carefully calculated using the well-known Discrete-Ordinate-Method Radiative Transfer (DISORT) model under over 10 millions of diverse conditions with varying cloud particle size, wavelength, satellite viewing direction, and solar angles. The obtained results were compressed significantly using principal component analysis and used in the mono domain radiance calculation. We used 1352 different atmosphere profiles, each of them has different surface skin temperatures and surface pressures in our training. Different surface emissivity spectra were derived from ASTER database and emissivity models. Some artificially generated emissivity spectra were also used to account for diverse surface types of the earth. Concentrations of sixteen trace gases were varied systematically in the training and the remaining trace gas contributions were accounted for as a fixed gas. Training was done in both clear and cloudy skies conditions. Finally the nonlocal thermal equilibrium (NLTE) induced radiance change was included for daytime conditions. We have updated the PCRTM model for instruments such as IASI, NASTI, CrIS, AIRS, and SHIS. The training results show that the PCRTM model can calculate thousands of channel radiances by computing only a few hundreds of mono radiances. This greatly increased the
Yang, Q.; Liu, X.; Wu, W.; Kizer, S.; Baize, R. R.
2016-12-01
Fast and accurate radiative transfer model is the key for satellite data assimilation and observation system simulation experiments for numerical weather prediction and climate study applications. We proposed and developed a dual stream PCRTM-SOLAR model which may simulate radiative transfer in the cloudy atmosphere with solar radiation quickly and accurately. Multi-scattering of multiple layers of clouds/aerosols is included in the model. The root-mean-square errors are usually less than 5x10-4 mW/cm2.sr.cm-1. The computation speed is 3 to 4 orders of magnitude faster than the medium speed correlated-k option MODTRAN5. This model will enable a vast new set of scientific calculations that were previously limited due to the computational expenses of available radiative transfer models.
Evaluation of Palm PCRTM G1-12 System: a portable battery-operated PCR thermal cycler
Directory of Open Access Journals (Sweden)
Siti Aminah Ahmed
2016-08-01
Full Text Available Polymerase chain reaction (PCR is the basis of recombinant and other molecular biological techniques. Availability of cheap and robust PCR platforms enables the tests to be performed easily, even in resource constrained settings. Herein we compared the efficacy of a portable thermal cycler ( Palm PCRTM G1-12 System for rapid DNA amplification against the standard Peltier-based thermal cycler using plasmid DNA and genomic DNA in single and multiplex PCR experiments. Our study revealed that the Palm PCRTM G1-12 System could be a portable DNA amplification system to conduct various molecular techniques, especially in places where resources are limited.
Yang, Qiguang; Liu, Xu; Wu, Wan; Kizer, Susan; Baize, Rosemary R.
2016-01-01
A hybrid stream PCRTM-SOLAR model has been proposed for fast and accurate radiative transfer simulation. It calculates the reflected solar (RS) radiances with a fast coarse way and then, with the help of a pre-saved matrix, transforms the results to obtain the desired high accurate RS spectrum. The methodology has been demonstrated with the hybrid stream discrete ordinate (HSDO) radiative transfer (RT) model. The HSDO method calculates the monochromatic radiances using a 4-stream discrete ordinate method, where only a small number of monochromatic radiances are simulated with both 4-stream and a larger N-stream (N = 16) discrete ordinate RT algorithm. The accuracy of the obtained channel radiance is comparable to the result from N-stream moderate resolution atmospheric transmission version 5 (MODTRAN5). The root-mean-square errors are usually less than 5x10(exp -4) mW/sq cm/sr/cm. The computational speed is three to four-orders of magnitude faster than the medium speed correlated-k option MODTRAN5. This method is very efficient to simulate thousands of RS spectra under multi-layer clouds/aerosols and solar radiation conditions for climate change study and numerical weather prediction applications.
Nonparametric Transfer Function Models
Liu, Jun M.; Chen, Rong; Yao, Qiwei
2009-01-01
In this paper a class of nonparametric transfer function models is proposed to model nonlinear relationships between ‘input’ and ‘output’ time series. The transfer function is smooth with unknown functional forms, and the noise is assumed to be a stationary autoregressive-moving average (ARMA) process. The nonparametric transfer function is estimated jointly with the ARMA parameters. By modeling the correlation in the noise, the transfer function can be estimated more efficiently. The parsimonious ARMA structure improves the estimation efficiency in finite samples. The asymptotic properties of the estimators are investigated. The finite-sample properties are illustrated through simulations and one empirical example. PMID:20628584
Prospects for Money Transfer Models
Yougui Wang; Ning Ding; Ning Xi
2005-01-01
Recently, in order to explore the mechanism behind wealth or income distribution, several models have been proposed by applying principles of statistical mechanics. These models share some characteristics, such as consisting of a group of individual agents, a pile of money and a specific trading rule. Whatever the trading rule is, the most noteworthy fact is that money is always transferred from one agent to another in the transferring process. So we call them money transfer models. Besides e...
Technology Transfer Issues and a New Technology Transfer Model
Choi, Hee Jun
2009-01-01
The following are major issues that should be considered for efficient and effective technology transfer: conceptions of technology, technological activity and transfer, communication channels, factors affecting transfer, and models of transfer. In particular, a well-developed model of technology transfer could be used as a framework for…
Modeling of atmospheric pollutant transfers
International Nuclear Information System (INIS)
Jourdain, F.
2007-01-01
Modeling is today a common tool for the evaluation of the environmental impact of atmospheric pollution events, for the design of air monitoring networks or for the calculation of pollutant concentrations in the ambient air. It is even necessary for the a priori evaluation of the consequences of a pollution plume. A large choice of atmospheric transfer codes exist but no ideal tool is available which allows to model all kinds of situations. The present day approach consists in combining different types of modeling according to the requested results and simulations. The CEA has a solid experience in this domain and has developed independent tools for the impact and safety studies relative to industrial facilities and to the management of crisis situations. (J.S.)
BUSINESS MODELS FOR INCREASING TECHNOLOGICAL TRANSFER EFFECTIVENESS
Directory of Open Access Journals (Sweden)
Simina FULGA
2016-05-01
Full Text Available The present paper is devoted to analyze the appropriate recommendations to increase the effectiveness of technology transfer organizations (centers from ReNITT, by using the specific instruments of Business Model Canvas, associated to the technological transfer value chain for the value added services addressed to their clients and according to a continuously improved competitive strategy over competition analysis.
Supporting Students' Knowledge Transfer in Modeling Activities
Piksööt, Jaanika; Sarapuu, Tago
2014-01-01
This study investigates ways to enhance secondary school students' knowledge transfer in complex science domains by implementing question prompts. Two samples of students applied two web-based models to study molecular genetics--the model of genetic code (n = 258) and translation (n = 245). For each model, the samples were randomly divided into…
Geomigration model of uranium transfer
International Nuclear Information System (INIS)
Vasil'ev, I.A.; Ovchinnikov, N.A.; Chernov, V.V.; Shestakov, A.A.
2007-01-01
Data on geologic structure and radiation environment in the vicinity of the tailings storage facility (TSF) of Kara-Balta uranium hydrometallurgical factory in Kyrgyzstan were used to design a mathematical model of physical processes of wind erosion from the surface of TSF. Numerical calculations have been performed to describe prevalence of contamination due to wind erosion in the environs of Kara-Balta [ru
Modeling microscale heat transfer using Calore.
Energy Technology Data Exchange (ETDEWEB)
Gallis, Michail A.; Rader, Daniel John; Wong, Chung-Nin Channy; Bainbridge, Bruce L.; Torczynski, John Robert; Piekos, Edward Stanley
2005-09-01
Modeling microscale heat transfer with the computational-heat-transfer code Calore is discussed. Microscale heat transfer problems differ from their macroscopic counterparts in that conductive heat transfer in both solid and gaseous materials may have important noncontinuum effects. In a solid material, three noncontinuum effects are considered: ballistic transport of phonons across a thin film, scattering of phonons from surface roughness at a gas-solid interface, and scattering of phonons from grain boundaries within the solid material. These processes are modeled for polycrystalline silicon, and the thermal-conductivity values predicted by these models are compared to experimental data. In a gaseous material, two noncontinuum effects are considered: ballistic transport of gas molecules across a thin gap and accommodation of gas molecules to solid conditions when reflecting from a solid surface. These processes are modeled for arbitrary gases by allowing the gas and solid temperatures across a gas-solid interface to differ: a finite heat transfer coefficient (contact conductance) is imposed at the gas-solid interface so that the temperature difference is proportional to the normal heat flux. In this approach, the behavior of gas in the bulk is not changed from behavior observed under macroscopic conditions. These models are implemented in Calore as user subroutines. The user subroutines reside within Sandia's Source Forge server, where they undergo version control and regression testing and are available to analysts needing these capabilities. A Calore simulation is presented that exercises these models for a heated microbeam separated from an ambient-temperature substrate by a thin gas-filled gap. Failure to use the noncontinuum heat transfer models for the solid and the gas causes the maximum temperature of the microbeam to be significantly underpredicted.
Multistate cohort models with proportional transfer rates
DEFF Research Database (Denmark)
Schoen, Robert; Canudas-Romo, Vladimir
2006-01-01
of transfer rates. The two living state case and hierarchical multistate models with any number of living states are analyzed in detail. Applying our approach to 1997 U.S. fertility data, we find that observed rates of parity progression are roughly proportional over age. Our proportional transfer rate...... approach provides trajectories by parity state and facilitates analyses of the implications of changes in parity rate levels and patterns. More women complete childbearing at parity 2 than at any other parity, and parity 2 would be the modal parity in models with total fertility rates (TFRs) of 1.40 to 2......We present a new, broadly applicable approach to summarizing the behavior of a cohort as it moves through a variety of statuses (or states). The approach is based on the assumption that all rates of transfer maintain a constant ratio to one another over age. We present closed-form expressions...
Towards an Integrative Model of Knowledge Transfer
DEFF Research Database (Denmark)
Turcan, Romeo V.; Heslop, Ben
This paper aims to contribute towards the advancement of an efficient architecture of a single market for knowledge through the development of an integrative model of knowledge transfer. Within this aim, several points of departure can be singled out. One, the article builds on the call of the Eu......This paper aims to contribute towards the advancement of an efficient architecture of a single market for knowledge through the development of an integrative model of knowledge transfer. Within this aim, several points of departure can be singled out. One, the article builds on the call...... business and academia, and implementing the respective legislature are enduring. The research objectives were to explore (i) the process of knowledge transfer in universities, including the nature of tensions, obstacles and incentives, (ii) the relationships between key stakeholders in the KT market...... of the emergent integrative model of knowledge transfer. In an attempt to bring it to a higher level of generalizability, the integrative model of KT is further conceptualized from a ‘sociology of markets’ perspective resulting in an emergent architecture of a single market for knowledge. Future research...
Numerical Modeling of Ablation Heat Transfer
Ewing, Mark E.; Laker, Travis S.; Walker, David T.
2013-01-01
A unique numerical method has been developed for solving one-dimensional ablation heat transfer problems. This paper provides a comprehensive description of the method, along with detailed derivations of the governing equations. This methodology supports solutions for traditional ablation modeling including such effects as heat transfer, material decomposition, pyrolysis gas permeation and heat exchange, and thermochemical surface erosion. The numerical scheme utilizes a control-volume approach with a variable grid to account for surface movement. This method directly supports implementation of nontraditional models such as material swelling and mechanical erosion, extending capabilities for modeling complex ablation phenomena. Verifications of the numerical implementation are provided using analytical solutions, code comparisons, and the method of manufactured solutions. These verifications are used to demonstrate solution accuracy and proper error convergence rates. A simple demonstration of a mechanical erosion (spallation) model is also provided to illustrate the unique capabilities of the method.
Heat transfer modeling an inductive approach
Sidebotham, George
2015-01-01
This innovative text emphasizes a "less-is-more" approach to modeling complicated systems such as heat transfer by treating them first as "1-node lumped models" that yield simple closed-form solutions. The author develops numerical techniques for students to obtain more detail, but also trains them to use the techniques only when simpler approaches fail. Covering all essential methods offered in traditional texts, but with a different order, Professor Sidebotham stresses inductive thinking and problem solving as well as a constructive understanding of modern, computer-based practice. Readers learn to develop their own code in the context of the material, rather than just how to use packaged software, offering a deeper, intrinsic grasp behind models of heat transfer. Developed from over twenty-five years of lecture notes to teach students of mechanical and chemical engineering at The Cooper Union for the Advancement of Science and Art, the book is ideal for students and practitioners across engineering discipl...
Stochastic Modelling of Wireless Energy Transfer
Veilleux, Shaun; Almaghasilah, Ahmed; Abedi, Ali; Wilkerson, DeLisa
2017-01-01
This study investigates the efficiency of a new method of powering remote sensors by the means of wireless energy transfer. The increased use of sensors for data collection comes with the inherent cost of supplying power from sources such as power cables or batteries. Wireless energy transfer technology eliminates the need for power cables or periodic battery replacement. The time and cost of setting up or expanding a sensor network will be reduced while allowing sensors to be placed in areas where running power cables or battery replacement is not feasible. This paper models wireless channels for power and data separately. Smart scheduling for the data channel is proposed to avoid transmitting data on a noisy channel where the probability of data loss is high to improve power efficiency. Analytical models have been developed and verified using simulations.
Heat transfer model for quenching by submerging
International Nuclear Information System (INIS)
Passarella, D N; Varas, F; MartIn, E B
2011-01-01
In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.
Heat transfer model for quenching by submerging
Energy Technology Data Exchange (ETDEWEB)
Passarella, D N; Varas, F [Departamento de Matematica Aplicada II, E.T.S. de Ing. de Telecomunicacion, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain); MartIn, E B, E-mail: diego@dma.uvigo.es, E-mail: fvaras@uvigo.es, E-mail: emortega@uvigo.es [Area de Mecanica de Fluidos, E.T.S. de Ing. Industriales, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain)
2011-05-01
In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.
RRTM: A rapid radiative transfer model
Energy Technology Data Exchange (ETDEWEB)
Mlawer, E.J.; Taubman, S.J.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)
1996-04-01
A rapid radiative transfer model (RRTM) for the calculation of longwave clear-sky fluxes and cooling rates has been developed. The model, which uses the correlated-k method, is both accurate and computationally fast. The foundation for RRTM is the line-by-line radiative transfer model (LBLRTM) from which the relevant k-distributions are obtained. LBLRTM, which has been extensively validated against spectral observations e.g., the high-resolution sounder and the Atmospheric Emitted Radiance Interferometer, is used to validate the flux and cooling rate results from RRTM. Validations of RRTM`s results have been performed for the tropical, midlatitude summer, and midlatitude winter atmospheres, as well as for the four Intercomparison of Radiation Codes in Climate Models (ICRCCM) cases from the Spectral Radiance Experiment (SPECTRE). Details of some of these validations are presented below. RRTM has the identical atmospheric input module as LBLRTM, facilitating intercomparisons with LBLRTM and application of the model at the Atmospheric Radiation Measurement Cloud and Radiation Testbed sites.
Energy Technology Data Exchange (ETDEWEB)
Dyrboel, Susanne
1998-05-01
Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For lager thickness dimensions the resulting heat transfer through the
Comparison of biospheric models of radionuclides transfer
International Nuclear Information System (INIS)
Garcia-Olivares, A.; Carrasco, E.
1992-01-01
The international BIOMOVS A4 exercise has made possible that a set of biospheric transfer models could predict the daily radionuclide concentration in soils, forage and some animal products (cow milk and beef) after the Chernobyl accident. The aim was to compare these predictions with experimental results in 13 locations around the world. The data provided were essentially the daily air contamination and precipitation and some site-dependent parameters. It was a blind test, the locations and experimental measures were not revealed in advance. Twenty-three models (quasi-steady state and time-dependent models) were involved in the study. In this paper an explicit criterion has been used in order to select the models that better fitted the experimental results. In nine selected locations a comparative analysis between these models has been carried out for obtaining the structural and parametric coincidences that could explain their relatively good performance. The first evidence obtained has been that a wide set of models were able to predict the order of magnitude of the nuclides time-integrated concentrations in several important biospheric comportments. But only a few models, all of them with a 'dynamical' structure, fitted the daily behavior with the reasonable agreement. The dynamical structure of the five most successful models at predicting for Caesium 137 (CIRCLE, ECOSYS, PATHWAY, PRYMA and RAGTIME) shows some common patterns that may be relevant for a better modelling of nuclear accident scenarios. (author)
Validation of the community radiative transfer model
International Nuclear Information System (INIS)
Ding Shouguo; Yang Ping; Weng Fuzhong; Liu Quanhua; Han Yong; Delst, Paul van; Li Jun; Baum, Bryan
2011-01-01
To validate the Community Radiative Transfer Model (CRTM) developed by the U.S. Joint Center for Satellite Data Assimilation (JCSDA), the discrete ordinate radiative transfer (DISORT) model and the line-by-line radiative transfer model (LBLRTM) are combined in order to provide a reference benchmark. Compared with the benchmark, the CRTM appears quite accurate for both clear sky and ice cloud radiance simulations with RMS errors below 0.2 K, except for clouds with small ice particles. In a computer CPU run time comparison, the CRTM is faster than DISORT by approximately two orders of magnitude. Using the operational MODIS cloud products and the European Center for Medium-range Weather Forecasting (ECMWF) atmospheric profiles as an input, the CRTM is employed to simulate the Atmospheric Infrared Sounder (AIRS) radiances. The CRTM simulations are shown to be in reasonably close agreement with the AIRS measurements (the discrepancies are within 2 K in terms of brightness temperature difference). Furthermore, the impact of uncertainties in the input cloud properties and atmospheric profiles on the CRTM simulations has been assessed. The CRTM-based brightness temperatures (BTs) at the top of the atmosphere (TOA), for both thin (τ 30) clouds, are highly sensitive to uncertainties in atmospheric temperature and cloud top pressure. However, for an optically thick cloud, the CRTM-based BTs are not sensitive to the uncertainties of cloud optical thickness, effective particle size, and atmospheric humidity profiles. On the contrary, the uncertainties of the CRTM-based TOA BTs resulting from effective particle size and optical thickness are not negligible in an optically thin cloud.
Heat Transfer Model for Hot Air Balloons
Lladó Gambín, Adriana
2016-01-01
A heat transfer model and analysis for hot air balloons is presented in this work, backed with a flow simulation using SolidWorks. The objective is to understand the major heat losses in the balloon and to identify the parameters that affect most its flight performance. Results show that more than 70% of the heat losses are due to the emitted radiation from the balloon envelope and that convection losses represent around 20% of the total. A simulated heating source is also included in the mod...
Electricity price forecasting through transfer function models
International Nuclear Information System (INIS)
Nogales, F.J.; Conejo, A.J.
2006-01-01
Forecasting electricity prices in present day competitive electricity markets is a must for both producers and consumers because both need price estimates to develop their respective market bidding strategies. This paper proposes a transfer function model to predict electricity prices based on both past electricity prices and demands, and discuss the rationale to build it. The importance of electricity demand information is assessed. Appropriate metrics to appraise prediction quality are identified and used. Realistic and extensive simulations based on data from the PJM Interconnection for year 2003 are conducted. The proposed model is compared with naive and other techniques. Journal of the Operational Research Society (2006) 57, 350-356.doi:10.1057/palgrave.jors.2601995; published online 18 May 2005. (author)
sdg Interacting boson model: two nucleon transfer
International Nuclear Information System (INIS)
Devi, Y.D.; Kota, V.K.B.
1996-01-01
A brief overview of the sdg interacting boson model (sdg IBM) is given. The two examples: (i) spectroscopic properties (spectra, B(E2)s, B(E4)s etc) of the rotor-γ unstable transitional Os-Pt isotopes and (ii) the analytical formulation of two nucleon transfer spectroscopic factors and sum-rule quantities are described in detail. They demonstrate that sdg IBM can be employed for systematic description of spectroscopic properties of nuclei and that large number of analytical formulas, which facilitate rapid analysis of data and provide a clear insight into the underlying structures, can be derived using sdg IBM dynamical symmetries respectively. (author). 24 refs., 5 figs., 3 tabs
Energy Technology Data Exchange (ETDEWEB)
Schoeling, L.G.
1993-09-01
This report describes the development and testing of the Kansas Technology Transfer Model (KTTM) which is to be utilized as a regional model for the development of other technology transfer programs for independent operators throughout oil-producing regions in the US. It describes the linkage of the regional model with a proposed national technology transfer plan, an evaluation technique for improving and assessing the model, and the methodology which makes it adaptable on a regional basis. The report also describes management concepts helpful in managing a technology transfer program. The original Tertiary Oil Recovery Project (TORP) activities, upon which the KTTM is based, were developed and tested for Kansas and have proved to be effective in assisting independent operators in utilizing technology. Through joint activities of TORP and the Kansas Geological Survey (KGS), the KTTM was developed and documented for application in other oil-producing regions. During the course of developing this model, twelve documents describing the implementation of the KTTM were developed as deliverables to DOE. These include: (1) a problem identification (PI) manual describing the format and results of six PI workshops conducted in different areas of Kansas, (2) three technology workshop participant manuals on advanced waterflooding, reservoir description, and personal computer applications, (3) three technology workshop instructor manuals which provides instructor material for all three workshops, (4) three technologies were documented as demonstration projects which included reservoir management, permeability modification, and utilization of a liquid-level acoustic measuring device, (5) a bibliography of all literature utilized in the documents, and (6) a document which describes the KTTM.
Heat Transfer Model for Hot Air Balloons
Llado-Gambin, Adriana
A heat transfer model and analysis for hot air balloons is presented in this work, backed with a flow simulation using SolidWorks. The objective is to understand the major heat losses in the balloon and to identify the parameters that affect most its flight performance. Results show that more than 70% of the heat losses are due to the emitted radiation from the balloon envelope and that convection losses represent around 20% of the total. A simulated heating source is also included in the modeling based on typical thermal input from a balloon propane burner. The burner duty cycle to keep a constant altitude can vary from 10% to 28% depending on the atmospheric conditions, and the ambient temperature is the parameter that most affects the total thermal input needed. The simulation and analysis also predict that the gas temperature inside the balloon decreases at a rate of -0.25 K/s when there is no burner activity, and it increases at a rate of +1 K/s when the balloon pilot operates the burner. The results were compared to actual flight data and they show very good agreement indicating that the major physical processes responsible for balloon performance aloft are accurately captured in the simulation.
Effect of different heat transfer models on HCCI engine simulation
International Nuclear Information System (INIS)
Neshat, Elaheh; Saray, Rahim Khoshbakhti
2014-01-01
Highlights: • A new multi zone model is developed for HCCI combustion modeling. • New heat transfer model is used for prediction of heat transfer in HCCI engines. • Model can predict engine combustion, performance and emission characteristics well. • Appropriate mass and heat transfer models cause to accurate prediction of CO, UHC and NOx. - Abstract: Heat transfer from engine walls has an important role on engine combustion, performance and emission characteristics. The main focus of this study is offering a new relation for calculation of convective heat transfer from in-cylinder charge to combustion chamber walls of HCCI engines and providing the ability of new model in comparison with the previous models. Therefore, a multi zone model is developed for homogeneous charge compression ignition engine simulation. Model consists of four different types of zones including core zone, boundary layer zone, outer zones, which are between core and boundary layer, and crevice zone. Conductive heat transfer and mass transfer are considered between neighboring zones. For accurate calculation of initial conditions at inlet valve closing, multi zone model is coupled with a single zone model, which simulates gas exchange process. Various correlations are used as convective heat transfer correlations. Woschni, modified Woschni, Hohenberg and Annand correlations are used as convective heat transfer models. The new convection model, developed by authors, is used, too. Comparative analyses are done to recognize the accurate correlation for prediction of engine combustion, performance and emission characteristics in a wide range of operating conditions. The results indicate that utilization of various heat transfer models, except for new convective heat transfer model, leads to significant differences in prediction of in-cylinder pressure and exhaust emissions. Using Woschni, Chang and new model, convective heat transfer coefficient increases near top dead center, sharply
Transfer Function Identification Using Orthogonal Fourier Transform Modeling Functions
Morelli, Eugene A.
2013-01-01
A method for transfer function identification, including both model structure determination and parameter estimation, was developed and demonstrated. The approach uses orthogonal modeling functions generated from frequency domain data obtained by Fourier transformation of time series data. The method was applied to simulation data to identify continuous-time transfer function models and unsteady aerodynamic models. Model fit error, estimated model parameters, and the associated uncertainties were used to show the effectiveness of the method for identifying accurate transfer function models from noisy data.
Visual prosthesis wireless energy transfer system optimal modeling.
Li, Xueping; Yang, Yuan; Gao, Yong
2014-01-16
Wireless energy transfer system is an effective way to solve the visual prosthesis energy supply problems, theoretical modeling of the system is the prerequisite to do optimal energy transfer system design. On the basis of the ideal model of the wireless energy transfer system, according to visual prosthesis application condition, the system modeling is optimized. During the optimal modeling, taking planar spiral coils as the coupling devices between energy transmitter and receiver, the effect of the parasitic capacitance of the transfer coil is considered, and especially the concept of biological capacitance is proposed to consider the influence of biological tissue on the energy transfer efficiency, resulting in the optimal modeling's more accuracy for the actual application. The simulation data of the optimal model in this paper is compared with that of the previous ideal model, the results show that under high frequency condition, the parasitic capacitance of inductance and biological capacitance considered in the optimal model could have great impact on the wireless energy transfer system. The further comparison with the experimental data verifies the validity and accuracy of the optimal model proposed in this paper. The optimal model proposed in this paper has a higher theoretical guiding significance for the wireless energy transfer system's further research, and provide a more precise model reference for solving the power supply problem in visual prosthesis clinical application.
A model technology transfer program for independent operators
Energy Technology Data Exchange (ETDEWEB)
Schoeling, L.G.
1996-08-01
In August 1992, the Energy Research Center (ERC) at the University of Kansas was awarded a contract by the US Department of Energy (DOE) to develop a technology transfer regional model. This report describes the development and testing of the Kansas Technology Transfer Model (KTTM) which is to be utilized as a regional model for the development of other technology transfer programs for independent operators throughout oil-producing regions in the US. It describes the linkage of the regional model with a proposed national technology transfer plan, an evaluation technique for improving and assessing the model, and the methodology which makes it adaptable on a regional basis. The report also describes management concepts helpful in managing a technology transfer program.
Atmospheric radiative transfer modeling: a summary of the AER codes
Energy Technology Data Exchange (ETDEWEB)
Clough, S.A. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Shephard, M.W. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States)]. E-mail: mshephar@aer.com; Mlawer, E.J. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Delamere, J.S. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Iacono, M.J. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Cady-Pereira, K. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Boukabara, S. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Brown, P.D. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States)
2005-03-01
The radiative transfer models developed at AER are being used extensively for a wide range of applications in the atmospheric sciences. This communication is intended to provide a coherent summary of the various radiative transfer models and associated databases publicly available from AER (http://www.rtweb.aer.com). Among the communities using the models are the remote sensing community (e.g. TES, IASI), the numerical weather prediction community (e.g. ECMWF, NCEP GFS, WRF, MM5), and the climate community (e.g. ECHAM5). Included in this communication is a description of the central features and recent updates for the following models: the line-by-line radiative transfer model (LBLRTM); the line file creation program (LNFL); the longwave and shortwave rapid radiative transfer models, RRTM{sub L}W and RRTM{sub S}W; the Monochromatic Radiative Transfer Model (MonoRTM); the MT{sub C}KD Continuum; and the Kurucz Solar Source Function. LBLRTM and the associated line parameter database (e.g. HITRAN 2000 with 2001 updates) play a central role in the suite of models. The physics adopted for LBLRTM has been extensively analyzed in the context of closure experiments involving the evaluation of the model inputs (e.g. atmospheric state), spectral radiative measurements and the spectral model output. The rapid radiative transfer models are then developed and evaluated using the validated LBLRTM model.
Approaches to modelling radionuclide transfer in agricultural systems
International Nuclear Information System (INIS)
Mitchell, N. G.
1995-01-01
Radiological dose assessment requires information describing the concentration and distribution of radionuclides in the environment. This information can be obtained from monitoring but is also evaluated with the aid of mathematical models. In such models the pathways of radionuclides from the release point to man are described in terms of transfer between compartments. The main pathways to be considered include: deposition to vegetation and soils; transfer from soil-to-plant; uptake and turnover in domestic animals; and, intake by man. The development of mathematical models for simulating transfer via these pathways depends on: an understanding of the system under study, in particular for those processes that are most important in the overall transfer to man; the availability of data to determine the structure and parameters for the model; the computing systems available; the knowledge of the user of the model; and, the application of the model. (author)
Comparison of heat transfer models for reciprocating compressor
International Nuclear Information System (INIS)
Tuhovcak, J.; Hejcik, J.; Jicha, M.
2016-01-01
Highlights: • Comparison of integral heat transfer models. • Influence of heat transfer model on volumetric and isentropic efficiency. • Various gases used as working fluid. - Abstract: One of the main factors affecting the efficiency of reciprocating compressor is heat transfer inside the cylinder. An analysis of heat transfer could be done using numerical models or integral correlations developed mainly from approaches used in combustion engines; however their accuracy is not completely verified due to the complicated experimental set up. The goal of this paper is to analyse the effect of heat transfer on compressor efficiency. Various integral correlations were compared for different compressor settings and fluids. CoolProp library was used in the code to obtain the properties of common coolants and gases. A comparison was done using the in-house code developed in Matlab, based on 1st Law of Thermodynamics.
A Privacy Model for RFID Tag Ownership Transfer
Directory of Open Access Journals (Sweden)
Xingchun Yang
2017-01-01
Full Text Available The ownership of RFID tag is often transferred from one owner to another in its life cycle. To address the privacy problem caused by tag ownership transfer, we propose a tag privacy model which captures the adversary’s abilities to get secret information inside readers, to corrupt tags, to authenticate tags, and to observe tag ownership transfer processes. This model gives formal definitions for tag forward privacy and backward privacy and can be used to measure the privacy property of tag ownership transfer scheme. We also present a tag ownership transfer scheme, which is privacy-preserving under the proposed model and satisfies the other common security requirements, in addition to achieving better performance.
Two dimensional finite element heat transfer models for softwood
Hongmei Gu; John F. Hunt
2004-01-01
The anisotropy of wood creates a complex problem for solving heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential directions and have not differentiated the effects of cellular alignment, earlywood/latewood...
A Model of the Antecedents of Training Transfer
Mohammed Turab, Ghaneemah; Casimir, Gian
2015-01-01
Many organizations have invested heavily in training. However, only a small percentage of what is learnt from training is applied or transferred to the workplace. This study examines factors that influence training transfer. A conceptual model based on the Theory of Reasoned Action is hypothesized and tested. The sample consisted of 123 full-time…
Improved Wave-vessel Transfer Functions by Uncertainty Modelling
DEFF Research Database (Denmark)
Nielsen, Ulrik Dam; Fønss Bach, Kasper; Iseki, Toshio
2016-01-01
This paper deals with uncertainty modelling of wave-vessel transfer functions used to calculate or predict wave-induced responses of a ship in a seaway. Although transfer functions, in theory, can be calculated to exactly reflect the behaviour of the ship when exposed to waves, uncertainty in inp...
Challenges of transferring models of fish abundance between coral reefs.
Sequeira, Ana M M; Mellin, Camille; Lozano-Montes, Hector M; Meeuwig, Jessica J; Vanderklift, Mathew A; Haywood, Michael D E; Babcock, Russell C; Caley, M Julian
2018-01-01
Reliable abundance estimates for species are fundamental in ecology, fisheries, and conservation. Consequently, predictive models able to provide reliable estimates for un- or poorly-surveyed locations would prove a valuable tool for management. Based on commonly used environmental and physical predictors, we developed predictive models of total fish abundance and of abundance by fish family for ten representative taxonomic families for the Great Barrier Reef (GBR) using multiple temporal scenarios. We then tested if models developed for the GBR (reference system) could predict fish abundances at Ningaloo Reef (NR; target system), i.e., if these GBR models could be successfully transferred to NR. Models of abundance by fish family resulted in improved performance (e.g., 44.1% fish abundance (9% fish species richness from the GBR to NR, transferability for these fish abundance models was poor. When compared with observations of fish abundance collected in NR, our transferability results had low validation scores ( R 2 0.05). High spatio-temporal variability of patterns in fish abundance at the family and population levels in both reef systems likely affected the transferability of these models. Inclusion of additional predictors with potential direct effects on abundance, such as local fishing effort or topographic complexity, may improve transferability of fish abundance models. However, observations of these local-scale predictors are often not available, and might thereby hinder studies on model transferability and its usefulness for conservation planning and management.
Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation
Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.
2012-01-01
Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.
Heat Transfer Modelling of Glass Media within TPV Systems
Bauer, Thomas; Forbes, Ian; Penlington, Roger; Pearsall, Nicola
2004-11-01
Understanding and optimisation of heat transfer, and in particular radiative heat transfer in terms of spectral, angular and spatial radiation distributions is important to achieve high system efficiencies and high electrical power densities for thermophtovoltaics (TPV). This work reviews heat transfer models and uses the Discrete Ordinates method. Firstly one-dimensional heat transfer in fused silica (quartz glass) shields was examined for the common arrangement, radiator-air-glass-air-PV cell. It has been concluded that an alternative arrangement radiator-glass-air-PV cell with increased thickness of fused silica should have advantages in terms of improved transmission of convertible radiation and enhanced suppression of non-convertible radiation.
Evaluation of multivariate calibration models transferred between spectroscopic instruments
DEFF Research Database (Denmark)
Eskildsen, Carl Emil Aae; Hansen, Per W.; Skov, Thomas
2016-01-01
In a setting where multiple spectroscopic instruments are used for the same measurements it may be convenient to develop the calibration model on a single instrument and then transfer this model to the other instruments. In the ideal scenario, all instruments provide the same predictions for the ......In a setting where multiple spectroscopic instruments are used for the same measurements it may be convenient to develop the calibration model on a single instrument and then transfer this model to the other instruments. In the ideal scenario, all instruments provide the same predictions...... for the same samples using the transferred model. However, sometimes the success of a model transfer is evaluated by comparing the transferred model predictions with the reference values. This is not optimal, as uncertainties in the reference method will impact the evaluation. This paper proposes a new method...... for calibration model transfer evaluation. The new method is based on comparing predictions from different instruments, rather than comparing predictions and reference values. A total of 75 flour samples were available for the study. All samples were measured on ten near infrared (NIR) instruments from two...
Modeling Transfer of Vibrio Parahaemolyticus During Peeling of Raw Shrimp.
Xiao, Xingning; Pang, Haiying; Wang, Wen; Fang, Weihuan; Fu, Yingchun; Li, Yanbin
2018-03-01
This study aimed to qualify the transfer of Vibrio parahaemolyticus during the shrimp peeling process via gloves under 3 different scenarios. The 1st 2 scenarios provided quantitative information for the probability distribution of bacterial transfer rates from (i) contaminated shrimp (6 log CFU/g) to non-contaminated gloves (Scenario 1) and (ii) contaminated gloves (6 log CFU/per pair) to non-contaminated shrimp (Scenario 2). In Scenario 3, bacterial transfer from contaminated shrimp to non-contaminated shrimp in the shrimp peeling process via gloves was investigated to develop a predictive model for describing the successive bacterial transfer. The range of bacterial transfer rate (%) in Scenarios 1 and 2 was 7% to 91.95% and 0.04% to 12.87%, respectively, indicating that the bacteria can be transferred from shrimp to gloves much easier than that from gloves to shrimp. A Logistic (1.59, 0.14) and Triangle distribution (-1.61, 0.12, 1.32) could be used to describe the bacterial transfer rate in Scenarios 1 and 2, respectively. In Scenario 3, a continuously decay patterning with fluctuations as the peeling progressed has been observed at all inoculation levels of the 1st shrimp (5, 6, and 7 log CFU/g). The bacteria could be transferred easier at 1st few peels, and the decreasing bacterial transfer was found in later phase. Two models (exponential and Weibull) could describe the successive bacterial transfer satisfactorily (pseudo-R 2 > 0.84, RMSE peeling process. The bacterial transfer rate distribution and predictive model derived from this work could be used in risk assessment of V. parahaemolyticus to ensure peeled shrimp safety. © 2018 Institute of Food Technologists®.
Can spatial statistical river temperature models be transferred between catchments?
Jackson, Faye L.; Fryer, Robert J.; Hannah, David M.; Malcolm, Iain A.
2017-09-01
There has been increasing use of spatial statistical models to understand and predict river temperature (Tw) from landscape covariates. However, it is not financially or logistically feasible to monitor all rivers and the transferability of such models has not been explored. This paper uses Tw data from four river catchments collected in August 2015 to assess how well spatial regression models predict the maximum 7-day rolling mean of daily maximum Tw (Twmax) within and between catchments. Models were fitted for each catchment separately using (1) landscape covariates only (LS models) and (2) landscape covariates and an air temperature (Ta) metric (LS_Ta models). All the LS models included upstream catchment area and three included a river network smoother (RNS) that accounted for unexplained spatial structure. The LS models transferred reasonably to other catchments, at least when predicting relative levels of Twmax. However, the predictions were biased when mean Twmax differed between catchments. The RNS was needed to characterise and predict finer-scale spatially correlated variation. Because the RNS was unique to each catchment and thus non-transferable, predictions were better within catchments than between catchments. A single model fitted to all catchments found no interactions between the landscape covariates and catchment, suggesting that the landscape relationships were transferable. The LS_Ta models transferred less well, with particularly poor performance when the relationship with the Ta metric was physically implausible or required extrapolation outside the range of the data. A single model fitted to all catchments found catchment-specific relationships between Twmax and the Ta metric, indicating that the Ta metric was not transferable. These findings improve our understanding of the transferability of spatial statistical river temperature models and provide a foundation for developing new approaches for predicting Tw at unmonitored locations across
Fast and simple model for atmospheric radiative transfer
Seidel, F.C.; Kokhanovsky, A.A.; Schaepman, M.E.
2010-01-01
Radiative transfer models (RTMs) are of utmost importance for quantitative remote sensing, especially for compensating atmospheric perturbation. A persistent trade-off exists between approaches that prefer accuracy at the cost of computational complexity, versus those favouring simplicity at the
Radiation heat transfer model for the SCDAP code
International Nuclear Information System (INIS)
Sohal, M.S.
1984-01-01
A radiation heat transfer model has been developed for severe fuel damage analysis which accounts for anisotropic effects of reflected radiation. The model simplifies the view factor calculation which results in significant savings in computational cost with little loss of accuracy. Radiation heat transfer rates calculated by the isotropic and anisotropic models compare reasonably well with those calculated by other models. The model is applied to an experimental nuclear rod bundle during a slow boiloff of the coolant liquid, a situation encountered during a loss of coolant accident with severe fuel damage. At lower temperatures and also lower temperature gradients in the core, the anisotropic effect was not found to be significant
Laplace transform analysis of a multiplicative asset transfer model
Sokolov, Andrey; Melatos, Andrew; Kieu, Tien
2010-07-01
We analyze a simple asset transfer model in which the transfer amount is a fixed fraction f of the giver’s wealth. The model is analyzed in a new way by Laplace transforming the master equation, solving it analytically and numerically for the steady-state distribution, and exploring the solutions for various values of f∈(0,1). The Laplace transform analysis is superior to agent-based simulations as it does not depend on the number of agents, enabling us to study entropy and inequality in regimes that are costly to address with simulations. We demonstrate that Boltzmann entropy is not a suitable (e.g. non-monotonic) measure of disorder in a multiplicative asset transfer system and suggest an asymmetric stochastic process that is equivalent to the asset transfer model.
Facial Performance Transfer via Deformable Models and Parametric Correspondence.
Asthana, Akshay; de la Hunty, Miles; Dhall, Abhinav; Goecke, Roland
2012-09-01
The issue of transferring facial performance from one person's face to another's has been an area of interest for the movie industry and the computer graphics community for quite some time. In recent years, deformable face models, such as the Active Appearance Model (AAM), have made it possible to track and synthesize faces in real time. Not surprisingly, deformable face model-based approaches for facial performance transfer have gained tremendous interest in the computer vision and graphics community. In this paper, we focus on the problem of real-time facial performance transfer using the AAM framework. We propose a novel approach of learning the mapping between the parameters of two completely independent AAMs, using them to facilitate the facial performance transfer in a more realistic manner than previous approaches. The main advantage of modeling this parametric correspondence is that it allows a "meaningful" transfer of both the nonrigid shape and texture across faces irrespective of the speakers' gender, shape, and size of the faces, and illumination conditions. We explore linear and nonlinear methods for modeling the parametric correspondence between the AAMs and show that the sparse linear regression method performs the best. Moreover, we show the utility of the proposed framework for a cross-language facial performance transfer that is an area of interest for the movie dubbing industry.
Numerical Modeling of Conjugate Heat Transfer in Fluid Network
Majumdar, Alok
2004-01-01
Fluid network modeling with conjugate heat transfer has many applications in Aerospace engineering. In modeling unsteady flow with heat transfer, it is important to know the variation of wall temperature in time and space to calculate heat transfer between solid to fluid. Since wall temperature is a function of flow, a coupled analysis of temperature of solid and fluid is necessary. In cryogenic applications, modeling of conjugate heat transfer is of great importance to correctly predict boil-off rate in propellant tanks and chill down of transfer lines. In TFAWS 2003, the present author delivered a paper to describe a general-purpose computer program, GFSSP (Generalized Fluid System Simulation Program). GFSSP calculates flow distribution in complex flow circuit for compressible/incompressible, with or without heat transfer or phase change in all real fluids or mixtures. The flow circuit constitutes of fluid nodes and branches. The mass, energy and specie conservation equations are solved at the nodes where as momentum conservation equations are solved at the branches. The proposed paper describes the extension of GFSSP to model conjugate heat transfer. The network also includes solid nodes and conductors in addition to fluid nodes and branches. The energy conservation equations for solid nodes solves to determine the temperatures of the solid nodes simultaneously with all conservation equations governing fluid flow. The numerical scheme accounts for conduction, convection and radiation heat transfer. The paper will also describe the applications of the code to predict chill down of cryogenic transfer line and boil-off rate of cryogenic propellant storage tank.
Modelling radiative heat transfer inside a basin type solar still
International Nuclear Information System (INIS)
Madhlopa, A.
2014-01-01
Radiative heat transfer inside a basin type solar still has been investigated using two models with (model 1) and without (model 2) taking into account optical view factors. The coefficient of radiative heat exchange (h r,w-gc ) between the water and cover surfaces of a practical solar still was computed using the two models. Simulation results show that model 1 yields lower values of h r,w-gc and the root mean square error than model 2. It is therefore concluded that the accuracy of modelling the performance of a basin-type solar still can be improved by incorporating view factors. - Highlights: • Radiative heat transfer in a basin type solar still has been investigated. • Two models with and without view factors were used. • The model with view factors exhibits a lower magnitude of root mean square error. • View factors affect the accuracy of modelling the performance of the solar still
Verification and Validation of Heat Transfer Model of AGREE Code
Energy Technology Data Exchange (ETDEWEB)
Tak, N. I. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seker, V.; Drzewiecki, T. J.; Downar, T. J. [Department of Nuclear Engineering and Radiological Sciences, Univ. of Michigan, Michigan (United States); Kelly, J. M. [US Nuclear Regulatory Commission, Washington (United States)
2013-05-15
The AGREE code was originally developed as a multi physics simulation code to perform design and safety analysis of Pebble Bed Reactors (PBR). Currently, additional capability for the analysis of Prismatic Modular Reactor (PMR) core is in progress. Newly implemented fluid model for a PMR core is based on a subchannel approach which has been widely used in the analyses of light water reactor (LWR) cores. A hexagonal fuel (or graphite block) is discretized into triangular prism nodes having effective conductivities. Then, a meso-scale heat transfer model is applied to the unit cell geometry of a prismatic fuel block. Both unit cell geometries of multi-hole and pin-in-hole types of prismatic fuel blocks are considered in AGREE. The main objective of this work is to verify and validate the heat transfer model newly implemented for a PMR core in the AGREE code. The measured data in the HENDEL experiment were used for the validation of the heat transfer model for a pin-in-hole fuel block. However, the HENDEL tests were limited to only steady-state conditions of pin-in-hole fuel blocks. There exist no available experimental data regarding a heat transfer in multi-hole fuel blocks. Therefore, numerical benchmarks using conceptual problems are considered to verify the heat transfer model of AGREE for multi-hole fuel blocks as well as transient conditions. The CORONA and GAMMA+ codes were used to compare the numerical results. In this work, the verification and validation study were performed for the heat transfer model of the AGREE code using the HENDEL experiment and the numerical benchmarks of selected conceptual problems. The results of the present work show that the heat transfer model of AGREE is accurate and reliable for prismatic fuel blocks. Further validation of AGREE is in progress for a whole reactor problem using the HTTR safety test data such as control rod withdrawal tests and loss-of-forced convection tests.
Simplified analytical model for thermal transfer in vertical hollow brick
Energy Technology Data Exchange (ETDEWEB)
Lorente, S [Lab. d` Etudes Thermiques et Mecaniques, INSA, UPS, Toulouse (France); Petit, M [Lab. d` Etudes Thermiques et Mecaniques, INSA, UPS, Toulouse (France); Javelas, R [Lab. d` Etudes Thermiques et Mecaniques, INSA, UPS, Toulouse (France)
1996-12-01
A modern building envelope has a lot of little cavities. Most of them are vertical with a high height to thickness ratio. We present here the conception of a software to determine heat transfer through terra-cotta bricks full of large vertical cavities. After a bibliographic study on convective heat transfer in such cavities, we made an analytical model based on Karman-Polhausen`s method for convection and on the radiosity method for radiative heat transfer. We used a test apparatus of a single cavity to determine the temperature field inside the cavity. Using these experimental results, we showed that the exchange was two-dimensional. We also realised heat flux measurements. Then we expose our theoretical study: We propose relations between central core temperatures and active face temperatures, then between outside and inside active face temperatures. We calculate convective superficial heat transfer because we noticed we have boundary layers along the active faces. We realise a heat flux balance between convective plus radiative heat transfer and conductive heat transfer, so we propose an algorithm to calculate global heat transfer through a single cavity. Finally, we extend our model to a whole hollow brick with lined-up cavities and propose an algorithm to calculate heat flux and thermal resistance with a good accuracy ({approx}7.5%) compared to previous experimental results. (orig.)
Soil-vegetation-atmosphere transfer modeling
Energy Technology Data Exchange (ETDEWEB)
Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)
1996-12-31
In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method
Soil-vegetation-atmosphere transfer modeling
Energy Technology Data Exchange (ETDEWEB)
Ikonen, J P; Sucksdorff, Y [Finnish Environment Agency, Helsinki (Finland)
1997-12-31
In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method
HTCC - a heat transfer model for gas-steam mixtures
International Nuclear Information System (INIS)
Papadimitriou, P.
1983-01-01
The mathematical model HTCC (Heat Transfer Coefficient in Containment) has been developed for RALOC after a loss-of-coolant accident in order to determine the local heat transfer coefficients for transfer between the containment atmosphere and the walls of the reactor building. The model considers the current values of room and wall temperature, the concentration of steam and non-condensible gases, geometry data and those of fluid dynamics together with thermodynamic parameters and from these determines the heat transfer mechanisms due to convection, radiation and condensation. The HTCC is implemented in the RALOC program. Comparative analyses of computed temperature profiles, for HEDL Standard problems A and B on hydrogen distribution, and of computed temperature profiles determined during the heat-up phase in the CSE-A5 experiment show a good agreement with experimental data. (orig.) [de
Model Transport: Towards Scalable Transfer Learning on Manifolds
DEFF Research Database (Denmark)
Freifeld, Oren; Hauberg, Søren; Black, Michael J.
2014-01-01
We consider the intersection of two research fields: transfer learning and statistics on manifolds. In particular, we consider, for manifold-valued data, transfer learning of tangent-space models such as Gaussians distributions, PCA, regression, or classifiers. Though one would hope to simply use...... ordinary Rn-transfer learning ideas, the manifold structure prevents it. We overcome this by basing our method on inner-product-preserving parallel transport, a well-known tool widely used in other problems of statistics on manifolds in computer vision. At first, this straightforward idea seems to suffer...... “commutes” with learning. Consequently, our compact framework, applicable to a large class of manifolds, is not restricted by the size of either the training or test sets. We demonstrate the approach by transferring PCA and logistic-regression models of real-world data involving 3D shapes and image...
Heat transfer modelling in thermophotovoltaic cavities using glass media
Energy Technology Data Exchange (ETDEWEB)
Bauer, T.; Forbes, I.; Penlington, R.; Pearsall, N. [Northumbria University, Newcastle upon Tyne (United Kingdom). School of Engineering and Technology
2005-08-15
Optimisation of heat transfer, and in particular radiative heat transfer in terms of the spectral, angular and spatial radiation distributions, is required to achieve high efficiencies and high electrical power densities for thermophotovoltaic (TPV) conversion. This work examines heat transfer from the radiator to the PV cell in an infinite plate arrangement using three different arrangements of participating dielectric media. The modelling applies the Discrete Ordinates method and assumes fused silica (quartz glass) as the dielectric medium. The arrangement radiator-glass-PV cell (also termed dielectric photon concentration) was found to be superior in terms of efficiency and power density. (author)
A Systematic Modelling Framework for Phase Transfer Catalyst Systems
DEFF Research Database (Denmark)
Anantpinijwatna, Amata; Sales-Cruz, Mauricio; Hyung Kim, Sun
2016-01-01
Phase-transfer catalyst systems contain two liquid phases, with a catalyst (PTC) that transfers between the phases, driving product formation in one phase and being regenerated in the other phase. Typically the reaction involves neutral species in an organic phase and regeneration involves ions i....... The application of the framework is made to two cases in order to highlight the performance and issues of activity coefficient models for predicting design and operation and the effects when different organic solvents are employed....
Modelling aerosol transfer in a ventilated room
International Nuclear Information System (INIS)
Nerisson, Ph.
2009-02-01
When particulate radioactive contamination is likely to become airborne in a ventilated room, assessment of aerosol concentration in every point of this room is important, in order to ensure protection of operators and supervision of workspaces. Thus, a model of aerosol transport and deposition has been developed as part of a project started with IRSN, EDF and IMFT. A simplified Eulerian model, called 'diffusion-inertia model' is used for particle transport. It contains a single transport equation of aerosol concentration. The specific study of deposition on walls has permitted to develop a boundary condition approach, which determines precisely the particle flux towards the wall in the boundary layer, for any deposition regime and surface orientation.The final transport and deposition models retained have been implemented in a CFD code called Code-Saturne. These models have been validated according to literature data in simple geometries and tracing experiments in ventilated rooms, which have been carried out in 30 m 3 and 1500 m 3 laboratory rooms. (author)
Radiative transfer model for contaminated rough slabs.
Andrieu, François; Douté, Sylvain; Schmidt, Frédéric; Schmitt, Bernard
2015-11-01
We present a semi-analytical model to simulate the bidirectional reflectance distribution function (BRDF) of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze massive hyperspectral data by a Bayesian approach. We designed it for planetary surface ice studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are assumed to be close to spherical and constituted of any type of material other than the ice matrix. It can be any other type of ice, mineral, or even bubbles defined by their optical constants. We assume a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and thus is suitable for high-resolution hyperspectral data analysis.
Dynamic Heat Transfer Model of Refrigerated Foodstuff
DEFF Research Database (Denmark)
Cai, Junping; Risum, Jørgen; Thybo, Claus
2006-01-01
happens to the food inside during this period, when we look at the quality factor? This paper discusses quality model of foodstuff, different scenarios of defrost scheme are simulated, questions such as how the defrost temperature and duration influence the food temperature, thus the food quality, as well...
Following the Template: Transferring Modeling Skills to Nonstandard Problems
Tyumeneva, Yu. A.; Goncharova, M. V.
2017-01-01
This study seeks to analyze how students apply a mathematical modeling skill that was previously learned by solving standard word problems to the solution of word problems with nonstandard contexts. During the course of an experiment involving 106 freshmen, we assessed how well they were able to transfer the mathematical modeling skill that is…
A Rotating Plug Model of Friction Stir Welding Heat Transfer
Raghulapadu J. K.; Peddieson, J.; Buchanan, G. R.; Nunes, A. C.
2006-01-01
A simplified rotating plug model is employed to study the heat transfer phenomena associated with the fiction stir welding process. An approximate analytical solution is obtained based on this idealized model and used both to demonstrate the qualitative influence of process parameters on predictions and to estimate temperatures produced in typical fiction stir welding situations.
A DYNAMICAL SYSTEM APPROACH IN MODELING TECHNOLOGY TRANSFER
Directory of Open Access Journals (Sweden)
Hennie Husniah
2016-05-01
Full Text Available In this paper we discuss a mathematical model of two parties technology transfer from a leader to a follower. The model is reconstructed via dynamical system approach from a known standard Raz and Assa model and we found some important conclusion which have not been discussed in the original model. The model assumes that in the absence of technology transfer from a leader to a follower, both the leader and the follower have a capability to grow independently with a known upper limit of the development. We obtain a rich mathematical structure of the steady state solution of the model. We discuss a special situation in which the upper limit of the technological development of the follower is higher than that of the leader, but the leader has started earlier than the follower in implementing the technology. In this case we show a paradox stating that the follower is unable to reach its original upper limit of the technological development could appear whenever the transfer rate is sufficiently high. We propose a new model to increase realism so that any technological transfer rate could only has a positive effect in accelerating the rate of growth of the follower in reaching its original upper limit of the development.
Geometric data transfer between CAD systems: solid models
DEFF Research Database (Denmark)
Kroszynski, Uri; Palstroem, Bjarne; Trostmann, Erik
1989-01-01
The first phase of the ESPRIT project CAD*I resulted in a specification for the exchange of solid models as well as in some pilot implementations of processors based on this specification. The authors summarize the CAD*I approach, addressing the structure of neutral files for solids, entities......, and attributes supporting three kinds of representations: facilities for the transfer of parametric designs; referencing library components; and other general mechanisms. They also describe the current state of the specification and processor implementations and include an example of a CAD*I neutral file....... Results from cycle and intersystem solid model transfer tests are presented, showing the practicality of the CAD*I proposal. B-rep model transfer results are discussed in some detail. The relationship of this work to standardization efforts is outlined...
Linearized vector radiative transfer model MCC++ for a spherical atmosphere
International Nuclear Information System (INIS)
Postylyakov, O.V.
2004-01-01
Application of radiative transfer models has shown that optical remote sensing requires extra characteristics of radiance field in addition to the radiance intensity itself. Simulation of spectral measurements, analysis of retrieval errors and development of retrieval algorithms are in need of derivatives of radiance with respect to atmospheric constituents under investigation. The presented vector spherical radiative transfer model MCC++ was linearized, which allows the calculation of derivatives of all elements of the Stokes vector with respect to the volume absorption coefficient simultaneously with radiance calculation. The model MCC++ employs Monte Carlo algorithm for radiative transfer simulation and takes into account aerosol and molecular scattering, gas and aerosol absorption, and Lambertian surface albedo. The model treats a spherically symmetrical atmosphere. Relation of the estimated derivatives with other forms of radiance derivatives: the weighting functions used in gas retrieval and the air mass factors used in the DOAS retrieval algorithms, is obtained. Validation of the model against other radiative models is overviewed. The computing time of the intensity for the MCC++ model is about that for radiative models treating sphericity of the atmosphere approximately and is significantly shorter than that for the full spherical models used in the comparisons. The simultaneous calculation of all derivatives (i.e. with respect to absorption in all model atmosphere layers) and the intensity is only 1.2-2 times longer than the calculation of the intensity only
Modelling of heat and mass transfer processes in neonatology
Energy Technology Data Exchange (ETDEWEB)
Ginalski, Maciej K [FLUENT Europe, Sheffield Business Park, Europa Link, Sheffield S9 1XU (United Kingdom); Nowak, Andrzej J [Institute of Thermal Technology, Silesian University of Technology, Konarskiego 22, 44-100 Gliwice (Poland); Wrobel, Luiz C [School of Engineering and Design, Brunel University, Uxbridge UB8 3PH (United Kingdom)], E-mail: maciej.ginalski@ansys.com, E-mail: Andrzej.J.Nowak@polsl.pl, E-mail: luiz.wrobel@brunel.ac.uk
2008-09-01
This paper reviews some of our recent applications of computational fluid dynamics (CFD) to model heat and mass transfer problems in neonatology and investigates the major heat and mass transfer mechanisms taking place in medical devices such as incubators and oxygen hoods. This includes novel mathematical developments giving rise to a supplementary model, entitled infant heat balance module, which has been fully integrated with the CFD solver and its graphical interface. The numerical simulations are validated through comparison tests with experimental results from the medical literature. It is shown that CFD simulations are very flexible tools that can take into account all modes of heat transfer in assisting neonatal care and the improved design of medical devices.
Modelling of heat and mass transfer processes in neonatology
International Nuclear Information System (INIS)
Ginalski, Maciej K; Nowak, Andrzej J; Wrobel, Luiz C
2008-01-01
This paper reviews some of our recent applications of computational fluid dynamics (CFD) to model heat and mass transfer problems in neonatology and investigates the major heat and mass transfer mechanisms taking place in medical devices such as incubators and oxygen hoods. This includes novel mathematical developments giving rise to a supplementary model, entitled infant heat balance module, which has been fully integrated with the CFD solver and its graphical interface. The numerical simulations are validated through comparison tests with experimental results from the medical literature. It is shown that CFD simulations are very flexible tools that can take into account all modes of heat transfer in assisting neonatal care and the improved design of medical devices
Widlowski, J.L.; Taberner, M.; Pinty, B.; Bruniquel-Pinel, V.; Disney, M.I.; Fernandes, R.; Gastellu-Etchegorry, J.P.; Gobron, N.; Kuusk, A.; Lavergne, T.; LeBlanc, S.; Lewis, P.E.; Martin, E.; Mõttus, M.; North, P.R.J.; Qin, W.; Robustelli, M.; Rochdi, N.; Ruiloba, R.; Thompson, R.; Verhoef, W.; Verstraete, M.M.; Xie, D.
2007-01-01
[1] The Radiation Transfer Model Intercomparison ( RAMI) initiative benchmarks canopy reflectance models under well-controlled experimental conditions. Launched for the first time in 1999, this triennial community exercise encourages the systematic evaluation of canopy reflectance models on a
Widlowski, J.-L.; Taberner, M.; Pinty, B.; Bruniquel-Pinel, V.; Disney, M.; Fernandes, R.; Gastellu-Etchegorry, J.P.; Gobron, N.; Kuusk, A.; Lavergne, T.; Leblanc, S.; Lewis, P.E.; Martin, E.; Mottus, M.; North, P.R.J.; Qin, W.; Robustelli, M.; Rochdi, N.; Ruiloba, R.; Soler, C.; Thompson, R.; Verhoef, W.; Xie, D.; Thompson, R.
2007-01-01
The Radiation Transfer Model Intercomparison (RAMI) initiative benchmarks canopy reflectance models under well‐controlled experimental conditions. Launched for the first time in 1999, this triennial community exercise encourages the systematic evaluation of canopy reflectance models on a voluntary
A Summary of Interfacial Heat Transfer Models and Correlations
Energy Technology Data Exchange (ETDEWEB)
Bae, Sung Won; Cho, Hyung Kyu; Lee, Young Jin; Kim, Hee Chul; Jung, Young Jong; Kim, K. D. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2007-10-15
A long term project has been launched in October 2006 to develop a plant safety analysis code. 5 organizations are joining together for the harmonious coworking to build up the code. In this project, KAERI takes the charge of the building up the physical models and correlations about the transport phenomena. The momentum and energy transfer terms as well as the mass are surveyed from the RELAP5/MOD3, RELAP5-3D, CATHARE, and TRAC-M does. Also the recent papers are surveyed. Among these resources, most of the CATHARE models are based on their own experiment and test results. Thus, the CATHARE models are only used as the comparison purposes. In this paper, a summary of the models and the correlations about the interfacial heat transfer are represented. These surveyed models and correlations will be tested numerically and one correlation is selected finally.
Radiative transfer model for heterogeneous 3-D scenes
Kimes, D. S.; Kirchner, J. A.
1982-01-01
A general mathematical framework for simulating processes in heterogeneous 3-D scenes is presented. Specifically, a model was designed and coded for application to radiative transfers in vegetative scenes. The model is unique in that it predicts (1) the directional spectral reflectance factors as a function of the sensor's azimuth and zenith angles and the sensor's position above the canopy, (2) the spectral absorption as a function of location within the scene, and (3) the directional spectral radiance as a function of the sensor's location within the scene. The model was shown to follow known physical principles of radiative transfer. Initial verification of the model as applied to a soybean row crop showed that the simulated directional reflectance data corresponded relatively well in gross trends to the measured data. However, the model can be greatly improved by incorporating more sophisticated and realistic anisotropic scattering algorithms
Modelling toluene oxidation : Incorporation of mass transfer phenomena
Hoorn, J.A.A.; van Soolingen, J.; Versteeg, G. F.
The kinetics of the oxidation of toluene have been studied in close interaction with the gas-liquid mass transfer occurring in the reactor. Kinetic parameters for a simple model have been estimated on basis of experimental observations performed under industrial conditions. The conclusions for the
New radiative transfer models for obscuring tori in active galaxies
van Bemmel, IM; Dullemond, CP
Two-dimensional radiative transfer is employed to obtain the broad-band infrared spectrum of active galaxies. In the models we vary the geometry and size of the obscuring medium, the surface density, the opacity and the grain size distribution. Resulting spectral energy distributions are constructed
Towards model-based testing of electronic funds transfer systems
Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.; Arbab, F.; Sirjani, M.
2012-01-01
We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the
Towards model-based testing of electronic funds transfer systems
Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.
2010-01-01
We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the
Transferring the Malaria Epidemic Prediction Model to Users in East ...
International Development Research Centre (IDRC) Digital Library (Canada)
Transferring the Malaria Epidemic Prediction Model to Users in East Africa. In the highlands of East Africa, epidemic malaria is an emerging climate-related hazard that urgently needs addressing. Malaria incidence increased by 337% during the 1987 epidemic in Rwanda. In Tanzania, Uganda and Kenya, malaria incidence ...
Modeling charge transfer at organic donor-acceptor semiconductor interfaces
Cakir, Deniz; Bokdam, Menno; de Jong, Machiel Pieter; Fahlman, M.; Brocks, G.
2012-01-01
We develop an integer charge transfer model for the potential steps observed at interfaces between donor and acceptor molecular semiconductors. The potential step can be expressed as the difference between the Fermi energy pinning levels of electrons on the acceptor material and holes on the donor
Validation of heat transfer models for gap cooling
International Nuclear Information System (INIS)
Okano, Yukimitsu; Nagae, Takashi; Murase, Michio
2004-01-01
For severe accident assessment of a light water reactor, models of heat transfer in a narrow annular gap between overheated core debris and a reactor pressure vessel are important for evaluating vessel integrity and accident management. The authors developed and improved the models of heat transfer. However, validation was not sufficient for applicability of the gap heat flux correlation to the debris cooling in the vessel lower head and applicability of the local boiling heat flux correlations to the high-pressure conditions. Therefore, in this paper, we evaluated the validity of the heat transfer models and correlations by analyses for ALPHA and LAVA experiments where molten aluminum oxide (Al 2 O 3 ) at about 2700 K was poured into the high pressure water pool in a small-scale simulated vessel lower head. In the heating process of the vessel wall, the calculated heating rate and peak temperature agreed well with the measured values, and the validity of the heat transfer models and gap heat flux correlation was confirmed. In the cooling process of the vessel wall, the calculated cooling rate was compared with the measured value, and the validity of the nucleate boiling heat flux correlation was confirmed. The peak temperatures of the vessel wall in ALPHA and LAVA experiments were lower than the temperature at the minimum heat flux point between film boiling and transition boiling, so the minimum heat flux correlation could not be validated. (author)
DEFF Research Database (Denmark)
Wahlgren, Bjarne; Aarkrog, Vibe
Bogen er den første samlede indføring i transfer på dansk. Transfer kan anvendes som praksis-filosofikum. Den giver en systematisk indsigt til den studerende, der spørger: Hvordan kan teoretisk viden bruges til at reflektere over handlinger i situationer, der passer til min fremtidige arbejdsplads?...
FARMLAND: model for transfer of radionuclides through terrestrial foodchains
International Nuclear Information System (INIS)
Brown, John
1995-01-01
Models to stimulate the transfer of radionuclides through terrestrial foodchains have been developed at the Board and regularly used over the last 20 years. The foodchain model is named FARMLAND (Food Activity from Radionuclide Movement on LAND) and it contains a suite of submodels, each of which simulates radionuclide transfer through a different part of the foodchain. These models can be combined in various orders so that they can be used for different situations of radiological interest. The main foods considered are: green vegetables; grain products; root vegetables; fruit; milk, meat and offal from cattle; meat and offal from sheep. A large variety of elements can be considered, although the degree of complexity with which some are modelled is greater than that for others; isotopes of caesium, strontium and iodine are treated in greatest detail. (Author)
A new energy transfer model for turbulent free shear flow
Liou, William W.-W.
1992-01-01
A new model for the energy transfer mechanism in the large-scale turbulent kinetic energy equation is proposed. An estimate of the characteristic length scale of the energy containing large structures is obtained from the wavelength associated with the structures predicted by a weakly nonlinear analysis for turbulent free shear flows. With the inclusion of the proposed energy transfer model, the weakly nonlinear wave models for the turbulent large-scale structures are self-contained and are likely to be independent flow geometries. The model is tested against a plane mixing layer. Reasonably good agreement is achieved. Finally, it is shown by using the Liapunov function method, the balance between the production and the drainage of the kinetic energy of the turbulent large-scale structures is asymptotically stable as their amplitude saturates. The saturation of the wave amplitude provides an alternative indicator for flow self-similarity.
A fast infrared radiative transfer model for overlapping clouds
International Nuclear Information System (INIS)
Niu Jianguo; Yang Ping; Huang Hunglung; Davies, James E.; Li Jun; Baum, Bryan A.; Hu, Yong X.
2007-01-01
A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-layered and overlapping cloud situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of cloud reflectance and transmittance values is employed to account for one or two cloud layers, whereas the background atmospheric optical thickness due to gaseous absorption can be computed from a clear-sky radiative transfer model. FIRTM2 is applicable to three atmospheric conditions: (1) clear-sky (2) single-layered ice or water cloud, and (3) two simultaneous cloud layers in a column (e.g., ice cloud overlying water cloud). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to cloud optical thickness and effective particle size. Sensitivity analyses have been carried out to assess the performance of FIRTM2 for two spectral regions, namely the longwave (LW) band (587.3-1179.5 cm -1 ) and the short-to-medium wave (SMW) band (1180.1-2228.9 cm -1 ). The assessment is carried out in terms of brightness temperature differences (BTD) between FIRTM2 and the well-known discrete ordinates radiative transfer model (DISORT), henceforth referred to as BTD (F-D). The BTD (F-D) values for single-layered clouds are generally less than 0.8 K. For the case of two cloud layers (specifically ice cloud over water cloud), the BTD (F-D) values are also generally less than 0.8 K except for the SMW band for the case of a very high altitude (>15 km) cloud comprised of small ice particles. Note that for clear-sky atmospheres, FIRTM2 reduces to the clear-sky radiative transfer model that is incorporated into FIRTM2, and the errors in this case are essentially those of the clear-sky radiative transfer model
Alpha-transfer reactions and the pairing-vibration model
International Nuclear Information System (INIS)
Betts, R.R.
1977-01-01
The pairing-vibration model with isospin is extended to include α-transfer reactions. Selection rules and expressions for transition strengths are derived and compared with experimental results for A = 40--66 nuclei. The selection rules are found to be followed quite well in the examples studied. The systematics of ground-state transition strengths are qualitatively quite well reproduced although the quantitative agreement is poor. When the changing nature of the pairing quanta is incorporated using two-particle transfer data the agreement becomes quantitatively good. Evidence is presented for clustering other than that due to pairing in 40 Ca and 44 Ti
SMRT: A new, modular snow microwave radiative transfer model
Picard, Ghislain; Sandells, Melody; Löwe, Henning; Dumont, Marie; Essery, Richard; Floury, Nicolas; Kontu, Anna; Lemmetyinen, Juha; Maslanka, William; Mätzler, Christian; Morin, Samuel; Wiesmann, Andreas
2017-04-01
Forward models of radiative transfer processes are needed to interpret remote sensing data and derive measurements of snow properties such as snow mass. A key requirement and challenge for microwave emission and scattering models is an accurate description of the snow microstructure. The snow microwave radiative transfer model (SMRT) was designed to cater for potential future active and/or passive satellite missions and developed to improve understanding of how to parameterize snow microstructure. SMRT is implemented in Python and is modular to allow easy intercomparison of different theoretical approaches. Separate modules are included for the snow microstructure model, electromagnetic module, radiative transfer solver, substrate, interface reflectivities, atmosphere and permittivities. An object-oriented approach is used with carefully specified exchanges between modules to allow future extensibility i.e. without constraining the parameter list requirements. This presentation illustrates the capabilities of SMRT. At present, five different snow microstructure models have been implemented, and direct insertion of the autocorrelation function from microtomography data is also foreseen with SMRT. Three electromagnetic modules are currently available. While DMRT-QCA and Rayleigh models need specific microstructure models, the Improved Born Approximation may be used with any microstructure representation. A discrete ordinates approach with stream connection is used to solve the radiative transfer equations, although future inclusion of 6-flux and 2-flux solvers are envisioned. Wrappers have been included to allow existing microwave emission models (MEMLS, HUT, DMRT-QMS) to be run with the same inputs and minimal extra code (2 lines). Comparisons between theoretical approaches will be shown, and evaluation against field experiments in the frequency range 5-150 GHz. SMRT is simple and elegant to use whilst providing a framework for future development within the
Heat and Mass Transfer Model in Freeze-Dried Medium
Alfat, Sayahdin; Purqon, Acep
2017-07-01
There are big problems in agriculture sector every year. One of the major problems is abundance of agricultural product during the peak of harvest season that is not matched by an increase in demand of agricultural product by consumers, this causes a wasted agricultural products. Alternative way was food preservation by freeze dried method. This method was already using heat transfer through conduction and convection to reduce water quality in the food. The main objective of this research was to design a model heat and mass transfer in freeze-dried medium. We had two steps in this research, the first step was design of medium as the heat injection site and the second was simulate heat and mass transfer of the product. During simulation process, we use physical property of some agriculture product. The result will show how temperature and moisture distribution every second. The method of research use finite element method (FEM) and will be illustrated in three dimensional.
Fuel element transfer cask modelling using MCNP technique
International Nuclear Information System (INIS)
Rosli Darmawan
2009-01-01
Full text: After operating for more than 25 years, some of the Reaktor TRIGA PUSPATI (RTP) fuel elements would have been depleted. A few addition and fuel reconfiguration exercises have to be conducted in order to maintain RTP capacity. Presently, RTP spent fuels are stored at the storage area inside RTP tank. The need to transfer the fuel element outside of RTP tank may be prevalence in the near future. The preparation shall be started from now. A fuel element transfer cask has been designed according to the recommendation by the fuel manufacturer and experience of other countries. A modelling using MCNP code has been conducted to analyse the design. The result shows that the design of transfer cask fuel element is safe for handling outside the RTP tank according to recent regulatory requirement. (author)
Fuel Element Transfer Cask Modelling Using MCNP Technique
International Nuclear Information System (INIS)
Darmawan, Rosli; Topah, Budiman Naim
2010-01-01
After operating for more than 25 years, some of the Reaktor TRIGA Puspati (RTP) fuel elements would have been depleted. A few addition and fuel reconfiguration exercises have to be conducted in order to maintain RTP capacity. Presently, RTP spent fuels are stored at the storage area inside RTP tank. The need to transfer the fuel element outside of RTP tank may be prevalence in the near future. The preparation shall be started from now. A fuel element transfer cask has been designed according to the recommendation by the fuel manufacturer and experience of other countries. A modelling using MCNP code has been conducted to analyse the design. The result shows that the design of transfer cask fuel element is safe for handling outside the RTP tank according to recent regulatory requirement.
Fluid mechanics and heat transfer advances in nonlinear dynamics modeling
Asli, Kaveh Hariri
2015-01-01
This valuable new book focuses on new methods and techniques in fluid mechanics and heat transfer in mechanical engineering. The book includes the research of the authors on the development of optimal mathematical models and also uses modern computer technology and mathematical methods for the analysis of nonlinear dynamic processes. It covers technologies applicable to both fluid mechanics and heat transfer problems, which include a combination of physical, mechanical, and thermal techniques. The authors develop a new method for the calculation of mathematical models by computer technology, using parametric modeling techniques and multiple analyses for mechanical system. The information in this book is intended to help reduce the risk of system damage or failure. Included are sidebar discussions, which contain information and facts about each subject area that help to emphasize important points to remember.
Pollinators, geitonogamy and a model of pollen transfer
International Nuclear Information System (INIS)
Di Pasquale, C.
1995-12-01
A model of pollination that considers the amount of geitonogamous pollen transfer in different flowers and plants is presented. We assumed in this work self-incompatible plant species and we studied how pollination is affected by different round trips described by pollinator from its nest, taking into account the fraction geitonogamy and the fraction pollen export. A deterministic model and a stochastic model of pollen transfer were developed from which we found that when pollinators describe a uniform sequence (visit the same number of flowers in each plant), individuals receive the maximum outcross pollen or minimum self pollen. That is, from the point of view of fertilization, the optimal number of flowers visited in each plant depends on the number of flowers of the plant, the length of the visit and the number of individuals. (author). 18 refs, 1 fig
Analytical heat transfer modeling of a new radiation calorimeter
Energy Technology Data Exchange (ETDEWEB)
Obame Ndong, Elysée [Department of Industrial Engineering and Maintenance, University of Sciences and Technology of Masuku (USTM), BP 941 Franceville (Gabon); Grenoble Electrical Engineering Laboratory (G2Elab), University Grenoble Alpes and CNRS, G2Elab, F38000 Grenoble (France); Gallot-Lavallée, Olivier [Grenoble Electrical Engineering Laboratory (G2Elab), University Grenoble Alpes and CNRS, G2Elab, F38000 Grenoble (France); Aitken, Frédéric, E-mail: frederic.aitken@g2elab.grenoble-inp.fr [Grenoble Electrical Engineering Laboratory (G2Elab), University Grenoble Alpes and CNRS, G2Elab, F38000 Grenoble (France)
2016-06-10
Highlights: • Design of a new calorimeter for measuring heat power loss in electrical components. • The calorimeter can operate in a temperature range from −50 °C to 150 °C. • An analytical model of heat transfers for this new calorimeter is presented. • The theoretical sensibility of the new apparatus is estimated at ±1 mW. - Abstract: This paper deals with an analytical modeling of heat transfers simulating a new radiation calorimeter operating in a temperature range from −50 °C to 150 °C. The aim of this modeling is the evaluation of the feasibility and performance of the calorimeter by assessing the measurement of power losses of some electrical devices by radiation, the influence of the geometry and materials. Finally a theoretical sensibility of the new apparatus is estimated at ±1 mW. From these results the calorimeter has been successfully implemented and patented.
Analytical heat transfer modeling of a new radiation calorimeter
International Nuclear Information System (INIS)
Obame Ndong, Elysée; Gallot-Lavallée, Olivier; Aitken, Frédéric
2016-01-01
Highlights: • Design of a new calorimeter for measuring heat power loss in electrical components. • The calorimeter can operate in a temperature range from −50 °C to 150 °C. • An analytical model of heat transfers for this new calorimeter is presented. • The theoretical sensibility of the new apparatus is estimated at ±1 mW. - Abstract: This paper deals with an analytical modeling of heat transfers simulating a new radiation calorimeter operating in a temperature range from −50 °C to 150 °C. The aim of this modeling is the evaluation of the feasibility and performance of the calorimeter by assessing the measurement of power losses of some electrical devices by radiation, the influence of the geometry and materials. Finally a theoretical sensibility of the new apparatus is estimated at ±1 mW. From these results the calorimeter has been successfully implemented and patented.
Advanced k-epsilon modeling of heat transfer
Kwon, Okey; Ames, Forrest E.
1995-01-01
This report describes two approaches to low Reynolds-number k-epsilon turbulence modeling which formulate the eddy viscosity on the wall-normal component of turbulence and a length scale. The wall-normal component of turbulence is computed via integration of the energy spectrum based on the local dissipation rate and is bounded by the isotropic condition. The models account for the anisotropy of the dissipation and the reduced mixing length due to the high strain rates present in the near-wall region. The turbulent kinetic energy and its dissipation rate were computed from the k and epsilon transport equations of Durbin. The models were tested for a wide range of turbulent flows and proved to be superior to other k-epsilon models, especially for nonequilibrium anisotropic flows. For the prediction of airfoil heat transfer, the models included a set of empirical correlations for predicting laminar-turbulent transition and laminar heat transfer augmentation due to the presence of freestream turbulence. The predictions of surface heat transfer were generally satisfactory.
Transfer prices assignment with integrated production and marketing optimization models
Directory of Open Access Journals (Sweden)
Enrique Parra
2018-04-01
Full Text Available Purpose: In decentralized organizations (today a great majority of the large multinational groups, much of the decision-making power is in its individual business units-BUs-. In these cases, the management control system (MCS uses transfer prices to coordinate actions of the BUs and to evaluate their performance with the goal of guaranteeing the whole corporation optimum. The purpose of the investigation is to design transfer prices that suit this goal. Design/methodology/approach: Considering the results of the whole company supply chain optimization models (in the presence of seasonality of demand the question is to design a mechanism that creates optimal incentives for the managers of each business unit to drive the corporation to the optimal performance. Mathematical programming models are used as a start point. Findings: Different transfer prices computation methods are introduced in this paper for decentralised organizations with two divisions (production and marketing. The methods take into account the results of the solution of the whole company supply chain optimization model, if exists, and can be adapted to the type of information available in the company. It is mainly focused on transport costs assignment. Practical implications: Using the methods proposed in this paper a decentralized corporation can implement more accurate transfer prices to drive the whole organization to the global optimum performance. Originality/value: The methods proposed are a new contribution to the literature on transfer prices with special emphasis on the practical and easy implementation in a modern corporation with several business units and with high seasonality of demand. Also, the methods proposed are very flexible and can be tuned depending on the type of information available in the company.
Mass transfer models analysis for the structured packings
International Nuclear Information System (INIS)
Suastegui R, A.O.
1997-01-01
The models that have been developing, to understand the mechanism of the mass transfer through the structured packings, present limitations for their application, existing then uncertainty in order to use them in the chemical industrial processes. In this study the main parameters used in the mass transfer are: the hydrodynamic of the bed of the column, the geometry of the bed, physical-chemical properties of the mixture and the flow regime of the operation between the flows liquid-gas. The sensibility of each one of these parameters generate an arduous work to develop right proposals and good interpretation of the phenomenon. With the purpose of showing the importance of these parameters mentioned in the mass transfer, this work is analyzed the process of absorption for the system water-air, using the models to the structured packings in packed columns. The models selected were developed by Bravo and collaborators in 1985 and 1992, in order to determine the parameters previous mentioned for the system water-air, using a structured packing built in the National Institute of Nuclear Research. In this work is showed the results of the models application and their discussion. (Author)
A review of {sup 137}Cs transfer to fungi and consequences for modelling environmental transfer
Energy Technology Data Exchange (ETDEWEB)
Gillett, A.G. E-mail: andy.gillett@nottingham.ac.uk; Crout, N.M.J
2000-03-01
A review of the published literature describing {sup 137}Cs transfer to fungi was carried out, summarising the collated data to determine factors controlling transfer and identify an appropriate modelling approach to predict future contamination. {sup 137}Cs transfer ratios (TR) are derived for fungi species collected within Europe and the CIS. Considerable variability in TRs is demonstrated, with TRs varying between <0.001 and >10 m{sup 2} kg{sup -1} across all species and over three orders of magnitude for individual species (e.g. Boletus badius). Generally, meta-information (such as habitat and soil attributes) is poorly reported in the literature so that classification of the TR is limited to the effect of nutritional type (P<0.025) in the order mycorrhizal>saprophytic{approx}parasitic. Analysis of the literature data set (a heterogeneous source) suggests that there is no statistical evidence to indicate a decrease in TRs for 10 years after the Chernobyl accident. Spatial analysis of a data set for Belgium indicates variability in {sup 137}Cs transfer within a sampling location, such that fruitbodies collected over a scale of approximately 5 km would show activities as variable as those collected over a much larger scale ({approx} or>50 km). Therefore, it is proposed that the collated data sets for individual species can be used to derive 'best estimates' for the parameters describing the distribution of TRs. These can then be used to estimate an 'effective' TR, which, when combined with local soil deposition level and frequency and effect of culinary practices, can give an estimate of the activity of fungi consumed by the general population.
A review of 137Cs transfer to fungi and consequences for modelling environmental transfer
International Nuclear Information System (INIS)
Gillett, A.G.; Crout, N.M.J.
2000-01-01
A review of the published literature describing 137 Cs transfer to fungi was carried out, summarising the collated data to determine factors controlling transfer and identify an appropriate modelling approach to predict future contamination. 137 Cs transfer ratios (TR) are derived for fungi species collected within Europe and the CIS. Considerable variability in TRs is demonstrated, with TRs varying between 10 m 2 kg -1 across all species and over three orders of magnitude for individual species (e.g. Boletus badius). Generally, meta-information (such as habitat and soil attributes) is poorly reported in the literature so that classification of the TR is limited to the effect of nutritional type (P saprophytic∼parasitic. Analysis of the literature data set (a heterogeneous source) suggests that there is no statistical evidence to indicate a decrease in TRs for 10 years after the Chernobyl accident. Spatial analysis of a data set for Belgium indicates variability in 137 Cs transfer within a sampling location, such that fruitbodies collected over a scale of approximately 5 km would show activities as variable as those collected over a much larger scale (∼ or>50 km). Therefore, it is proposed that the collated data sets for individual species can be used to derive 'best estimates' for the parameters describing the distribution of TRs. These can then be used to estimate an 'effective' TR, which, when combined with local soil deposition level and frequency and effect of culinary practices, can give an estimate of the activity of fungi consumed by the general population
Application of flexibility model in modeling of flow boiling heat transfer
International Nuclear Information System (INIS)
Peng Jinfeng; Zhao Fuyu
2009-01-01
The mathematical modeling and computer simulation have been widely used in the analysis of system's dynamic characteristics, and often useful for system control. One of the popular methods for this purpose is the lumped parameter method. For flow boiling heat transfer system, the traditional lumped parameter modeling method has a problem that the heat transfer coefficients change suddenly at the boundary of coolant phase change. It can cause error. In this paper, an idea of flexibility model is developed to deal with the boundary problem and to improve the model of flow boiling heat transfer. The segments of coolant phase change's boundary are identified, and the membership functions which are derived from Fuzzy Mathematics are used to derive approximate expressions of heat transfer coefficient in those regions. The continuity of heat transfer coefficient can be described by those expressions. The membership functions are derived from mathematical analysis and transformation. The result shows that this idea is feasible and the conclusion is practicable.
Measurement and modeling of interface heat transfer coefficients
International Nuclear Information System (INIS)
Rollett, A.D.; Lewis, H.D.; Dunn, P.S.
1985-01-01
The results of preliminary work on the modeling and measurement of the heat transfer coefficients of metal/mold interfaces is reported. The system investigated is the casting of uranium in graphite molds. The motivation for the work is primarily to improve the accuracy of process modeling of prototype mold designs at the Los Alamos Foundry. The evolution in design of a suitable mold for unidirectional solidification is described, illustrating the value of simulating mold designs prior to use. Experiment indicated a heat transfer coefficient of 2 kW/m 2 /K both with and without superheat. It was possible to distinguish between solidification due to the mold and that due to radiative heat loss. This permitted an experimental estimate of the emissivity, epsilon = 0.2, of the solidified metal
New radiative transfer models for obscuring tori in active galaxies
van Bemmel, I. M.; Dullemond, C. P.
2003-01-01
Two-dimensional radiative transfer is employed to obtain the broad-band infrared spectrum of active galaxies. In the models we vary the geometry and size of the obscuring medium, the surface density, the opacity and the grain size distribution. Resulting spectral energy distributions are constructed for different orientations of the toroid. Colour-colour comparisons with observational data are consistent with previous observations that the emission longward of 60 micron is produced by star-fo...
Transient Heat Transfer Model for Car Body Primer Curing
D. Zabala; N. Sánchez; J. Pinto
2010-01-01
A transient heat transfer mathematical model for the prediction of temperature distribution in the car body during primer baking has been developed by considering the thermal radiation and convection in the furnace chamber and transient heat conduction governing equations in the car framework. The car cockpit is considered like a structure with six flat plates, four vertical plates representing the car doors and the rear and front panels. The other two flat plates are the...
Fires involving radioactive materials : transference model; operative recommendations
International Nuclear Information System (INIS)
Rodriguez, C.E.; Puntarulo, L.J.; Canibano, J.A.
1988-01-01
In all aspects related to the nuclear activity, the occurrence of an explosion, fire or burst type accident, with or without victims, is directly related to the characteristics of the site. The present work analyses the different parameters involved, describing a transference model and recommendations for evaluation and control of the radiological risk for firemen. Special emphasis is placed on the measurement of the variables existing in this kind of operations
Models for fluid flows with heat transfer in mixed convection
International Nuclear Information System (INIS)
Mompean Munhoz da Cruz, G.
1989-06-01
Second order models were studied in order to predict turbulent flows with heat transfer. The equations used correspond to the characteristic scale of turbulent flows. The order of magnitude of the terms of the equation is analyzed by using Reynolds and Peclet numbers. The two-equation model (K-ε) is applied in the hydrodynamic study. Two models are developed for the heat transfer analysis: the Prt + teta 2 and the complete model. In the first model, the turbulent thermal diffusivity is calculated by using the Prandtl number for turbulent flow and an equation for the variance of the temperature fluctuation. The second model consists of three equations concerning: the turbulent heat flow, the variance of the temperature fluctuation and its dissipation ratio. The equations were validated by four experiments, which were characterized by the analysis of: the air flow after passing through a grid of constant average temperature and with temperature gradient, an axysymmetric air jet submitted to high and low heating temperature, the mixing (cold-hot) of two coaxial jets of sodium at high Peclet number. The complete model is shown to be the most suitable for the investigations presented [fr
Approximate models for broken clouds in stochastic radiative transfer theory
International Nuclear Information System (INIS)
Doicu, Adrian; Efremenko, Dmitry S.; Loyola, Diego; Trautmann, Thomas
2014-01-01
This paper presents approximate models in stochastic radiative transfer theory. The independent column approximation and its modified version with a solar source computed in a full three-dimensional atmosphere are formulated in a stochastic framework and for arbitrary cloud statistics. The nth-order stochastic models describing the independent column approximations are equivalent to the nth-order stochastic models for the original radiance fields in which the gradient vectors are neglected. Fast approximate models are further derived on the basis of zeroth-order stochastic models and the independent column approximation. The so-called “internal mixing” models assume a combination of the optical properties of the cloud and the clear sky, while the “external mixing” models assume a combination of the radiances corresponding to completely overcast and clear skies. A consistent treatment of internal and external mixing models is provided, and a new parameterization of the closure coefficient in the effective thickness approximation is given. An efficient computation of the closure coefficient for internal mixing models, using a previously derived vector stochastic model as a reference, is also presented. Equipped with appropriate look-up tables for the closure coefficient, these models can easily be integrated into operational trace gas retrieval systems that exploit absorption features in the near-IR solar spectrum. - Highlights: • Independent column approximation in a stochastic setting. • Fast internal and external mixing models for total and diffuse radiances. • Efficient optimization of internal mixing models to match reference models
Stress transfer modeling in CNT reinforced composites using continuum mechanics
International Nuclear Information System (INIS)
Chaboki Khiabani, A.; Sadrnejad, S. A.; Yahyaeii, M.
2008-01-01
Because of the substantial difference in stiffness between matrix and nano tube in CNT composite, the stress transfer between them controls their mechanical properties. This paper investigates the said issue, analytically and numerically, in axial load using representative volume element. The analytical model was established based on the modified Cox's shear lag model with the use of some simplified assumptions. Some, in the developed shear lag model, the CNT assumes hollow fiber. Solving the governing differential equation. led the high shear stress, in interface especially in the CNT cap. In addition, some finite element models were performed with different aspect ratios and the shear stress pattern especially in interface was calculated numerically. Despite some simplified assumptions that were performed with these two models such as elastic behavior and full connectivity, and the comparison of their results with other numerical models show adequate agreement
A rapid radiative transfer model for reflection of solar radiation
Xiang, X.; Smith, E. A.; Justus, C. G.
1994-01-01
A rapid analytical radiative transfer model for reflection of solar radiation in plane-parallel atmospheres is developed based on the Sobolev approach and the delta function transformation technique. A distinct advantage of this model over alternative two-stream solutions is that in addition to yielding the irradiance components, which turn out to be mathematically equivalent to the delta-Eddington approximation, the radiance field can also be expanded in a mathematically consistent fashion. Tests with the model against a more precise multistream discrete ordinate model over a wide range of input parameters demonstrate that the new approximate method typically produces average radiance differences of less than 5%, with worst average differences of approximately 10%-15%. By the same token, the computational speed of the new model is some tens to thousands times faster than that of the more precise model when its stream resolution is set to generate precise calculations.
Modelling the radioecological transfer of radiocaesium to three Swedish populations
International Nuclear Information System (INIS)
Raeaef, C.L.
2005-01-01
UNSCEAR has presented a terrestrial transfer model for predicting the annual average concentrations of radionuclides in important diet components and in humans based on the annual ground deposition from atmospheric fallout. The model is composed of three components, the principal component representing the direct contamination of fodder and crops, and the two remaining ones reflecting delayed transfer from previous fallout accumulated in soils. The model is intended to be used for protracted deposition of radionuclides and has been applied to observed time-patterns of 137 Cs body burdens in three different Swedish populations subjected to transfer from continuous nuclear weapons fallout during the 1960s and 1970s. The results show that the best agreement with observed body burden data is obtained by applying an effective ecological half-time, T eco,eff , for nuclear weapons fallout 137 Cs of 0.8 years for urban individuals in the South of Sweden, 2 years for urbans living in the Stockholm area and 4 years for reindeer herders in the middle of Sweden. When compared with the ecological half-times observed in the urban population after the Chernobyl fallout these values appear to be shorter
The thermodynamics of enhanced heat transfer: a model study
International Nuclear Information System (INIS)
Hovhannisyan, Karen; Allahverdyan, Armen E
2010-01-01
Situations where a spontaneous process of energy or matter transfer is enhanced by an external device are widespread in nature (the human sweating system, enzyme catalysis, facilitated diffusion across biomembranes, industrial heat-exchangers and so on). The thermodynamics of such processes remains, however, open. Here we study enhanced heat transfer by using a model junction immersed between two thermal baths at different temperatures T h and T c (T h > T c ). The transferred heat power is enhanced via controlling the junction by means of external time-dependent fields. Provided that the spontaneous heat flow process is optimized over the junction Hamiltonian, any enhancement of this spontaneous process demands consumption and subsequent dissipation of work. The efficiency of the enhancement is defined via the increment in the heat power divided by the amount of work done. We show that this efficiency is bounded from above by T c /(T h − T c ). Formally this is identical to the Carnot bound for the efficiency of ordinary refrigerators which transfer heat from cold to hot bodies. It also shares some (but not all) physical features of the Carnot bound
Massenberg, Ann-Christine; Spurk, Daniel; Kauffeld, Simone
2015-01-01
Supervisor support, peer support and transfer motivation have been identified as important predictors of training transfer. Transfer motivation is thought to mediate the support-training transfer relationship. Especially after team training interventions that include all team members (i.e. whole-team training), individual perception of these…
Fluid flow and heat transfer modeling for castings
International Nuclear Information System (INIS)
Domanus, H.M.; Liu, Y.Y.; Sha, W.T.
1986-01-01
Casting is fundamental to manufacturing of many types of equipment and products. Although casting is a very old technology that has been in existence for hundreds of years, it remains a highly empirical technology, and production of new castings requires an expensive and time-consuming trial-and-error approach. In recent years, mathematical modeling of casting has received increasing attention; however, a majority of the modeling work has been in the area of heat transfer and solidification. Very little work has been done in modeling fluid flow of the liquid melt. This paper presents a model of fluid flow coupled with heat transfer of a liquid melt for casting processes. The model to be described in this paper is an extension of the COMMIX code and is capable of handling castings with any shape, size, and material. A feature of this model is the ability to track the liquid/gas interface and liquid/solid interface. The flow of liquid melt through the sprue and runners and into the mold cavity is calculated as well as three-dimensional temperature and velocity distributions of the liquid melt throughout the casting process. 14 refs., 13 figs
Recent validation studies for two NRPB environmental transfer models
International Nuclear Information System (INIS)
Brown, J.; Simmonds, J.R.
1991-01-01
The National Radiological Protection Board (NRPB) developed a dynamic model for the transfer of radionuclides through terrestrial food chains some years ago. This model, now called FARMLAND, predicts both instantaneous and time integrals of concentration of radionuclides in a variety of foods. The model can be used to assess the consequences of both accidental and routine releases of radioactivity to the environment; and results can be obtained as a function of time. A number of validation studies have been carried out on FARMLAND. In these the model predictions have been compared with a variety of sets of environmental measurement data. Some of these studies will be outlined in the paper. A model to predict external radiation exposure from radioactivity deposited on different surfaces in the environment has also been developed at NRPB. This model, called EXPURT (EXPosure from Urban Radionuclide Transfer), can be used to predict radiation doses as a function of time following deposition in a variety of environments, ranging from rural to inner-city areas. This paper outlines validation studies and future extensions to be carried out on EXPURT. (12 refs., 4 figs.)
African Journals Online (AJOL)
This paper reports on further studies on long range energy transfer between curcumine as donor and another thiazine dye, thionine, which is closely related to methylene blue as energy harvester (Figure 1). Since thionine is known to have a higher quantum yield of singlet oxygen sensitization than methylene blue [8], it is ...
Modelling of heat transfer to fluids at a supercritical pressure
International Nuclear Information System (INIS)
Shuisheng, He
2014-01-01
A key feature of Supercritical Water-cooled Reactor (SCWR) is that, by raising the pressure of the reactor coolant fluid above the critical value, a phase change crisis is avoided. However, the changes in water density as it flows through the core of an SCWR are actually much higher than in the current water-cooled reactors. In a typical design, the ratio of the density of water at the core inlet to that at exit is as high as 7:1. Other fluid properties also vary significantly, especially around the pseudo-critical temperature (at which the specific heat capacity peaks). As a result, turbulent flow and heat transfer behaviour in the core is extremely complex and under certain conditions, significant heat transfer deterioration can potentially occur. Consequently, understanding and being able to predict flow and heat transfer phenomena under normal steady operation conditions and in start-up and hypothetical fault conditions are fundamental to the design of SCWR. There have been intensive studies on flow and heat transfer to fluids at supercritical pressure recently and several excellent review papers have been published. In the talk, we will focus on some turbulence modelling issues encountered in CFD simulations. The talk will first discuss some flow and heat transfer issues related to fluids at supercritical pressures and their potential implications in SCWR, and some recent developments in the understanding and modelling techniques of such problems, which will be followed by an outlook for some future developments.Factors which have a major influence on the flow and will be discussed are buoyancy and flow acceleration due to thermal expansion (both are due to density variations but involve different mechanisms) and the nonuniformity of other fluid properties. In addition, laminar-turbulent flow transition coupled with buoyancy and flow acceleration plays an important role in heat transfer effectiveness and wall temperature in the entrance region but such
Stochastic radiative transfer model for mixture of discontinuous vegetation canopies
International Nuclear Information System (INIS)
Shabanov, Nikolay V.; Huang, D.; Knjazikhin, Y.; Dickinson, R.E.; Myneni, Ranga B.
2007-01-01
Modeling of the radiation regime of a mixture of vegetation species is a fundamental problem of the Earth's land remote sensing and climate applications. The major existing approaches, including the linear mixture model and the turbid medium (TM) mixture radiative transfer model, provide only an approximate solution to this problem. In this study, we developed the stochastic mixture radiative transfer (SMRT) model, a mathematically exact tool to evaluate radiation regime in a natural canopy with spatially varying optical properties, that is, canopy, which exhibits a structured mixture of vegetation species and gaps. The model solves for the radiation quantities, direct input to the remote sensing/climate applications: mean radiation fluxes over whole mixture and over individual species. The canopy structure is parameterized in the SMRT model in terms of two stochastic moments: the probability of finding species and the conditional pair-correlation of species. The second moment is responsible for the 3D radiation effects, namely, radiation streaming through gaps without interaction with vegetation and variation of the radiation fluxes between different species. We performed analytical and numerical analysis of the radiation effects, simulated with the SMRT model for the three cases of canopy structure: (a) non-ordered mixture of species and gaps (TM); (b) ordered mixture of species without gaps; and (c) ordered mixture of species with gaps. The analysis indicates that the variation of radiation fluxes between different species is proportional to the variation of species optical properties (leaf albedo, density of foliage, etc.) Gaps introduce significant disturbance to the radiation regime in the canopy as their optical properties constitute major contrast to those of any vegetation species. The SMRT model resolves deficiencies of the major existing mixture models: ignorance of species radiation coupling via multiple scattering of photons (the linear mixture model
Towards model-based testing of electronic funds transfer systems
Asaadi, H.R.; Khosravi, R.; Mousavi, M.R.; Noroozi, N.
2010-01-01
We report on our first experience with applying model-based testing techniques to an operational Electronic Funds Transfer (EFT) switch. The goal is to test the conformance of the EFT switch to the standard flows described by the ISO 8583 standard. To this end, we first make a formalization of the transaction flows specified in the ISO 8583 standard in terms of a Labeled Transition System (LTS). This formalization paves the way for model-based testing based on the formal notion of Input-Outpu...
A meshless method for modeling convective heat transfer
Energy Technology Data Exchange (ETDEWEB)
Carrington, David B [Los Alamos National Laboratory
2010-01-01
A meshless method is used in a projection-based approach to solve the primitive equations for fluid flow with heat transfer. The method is easy to implement in a MATLAB format. Radial basis functions are used to solve two benchmark test cases: natural convection in a square enclosure and flow with forced convection over a backward facing step. The results are compared with two popular and widely used commercial codes: COMSOL, a finite element model, and FLUENT, a finite volume-based model.
Evaluating the reliability of predictions made using environmental transfer models
International Nuclear Information System (INIS)
1989-01-01
The development and application of mathematical models for predicting the consequences of releases of radionuclides into the environment from normal operations in the nuclear fuel cycle and in hypothetical accident conditions has increased dramatically in the last two decades. This Safety Practice publication has been prepared to provide guidance on the available methods for evaluating the reliability of environmental transfer model predictions. It provides a practical introduction of the subject and a particular emphasis has been given to worked examples in the text. It is intended to supplement existing IAEA publications on environmental assessment methodology. 60 refs, 17 figs, 12 tabs
Mass transfer model for two-layer TBP oxidation reactions
International Nuclear Information System (INIS)
Laurinat, J.E.
1994-01-01
To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments. Three cases were investigated: (1) transfer of water into the TBP layer with sparging of both the aqueous and TBP layers, (2) transfer of water into the TBP layer with sparging of just the TBP layer, and (3) transfer of butanol into the aqueous layer with sparging of both layers. The TBP layer was comprised of 99% pure TBP (spiked with butanol for the butanol transfer experiments), and the aqueous layer was comprised of either water or an aluminum nitrate solution. The liquid layers were air sparged to simulate the mixing due to the evolution of gases generated by oxidation reactions. A plastic tube and a glass frit sparger were used to provide different size bubbles. Rates of mass transfer were measured using infrared spectrophotometers provided by SRTC/Analytical Development
Lattice Boltzmann heat transfer model for permeable voxels
Pereira, Gerald G.; Wu, Bisheng; Ahmed, Shakil
2017-12-01
We develop a gray-scale lattice Boltzmann (LB) model to study fluid flow combined with heat transfer for flow through porous media where voxels may be partially solid (or void). Heat transfer in rocks may lead to deformation, which in turn can modulate the fluid flow and so has significant contribution to rock permeability. The LB temperature field is compared to a finite difference solution of the continuum partial differential equations for fluid flow in a channel. Excellent quantitative agreement is found for both Poiseuille channel flow and Brinkman flow. The LB model is then applied to sample porous media such as packed beds and also more realistic sandstone rock sample, and both the convective and diffusive regimes are recovered when varying the thermal diffusivity. It is found that while the rock permeability can be comparatively small (order milli-Darcy), the temperature field can show significant variation depending on the thermal convection of the fluid. This LB method has significant advantages over other numerical methods such as finite and boundary element methods in dealing with coupled fluid flow and heat transfer in rocks which have irregular and nonsmooth pore spaces.
Challenges of model transferability to data-scarce regions (Invited)
Samaniego, L. E.
2013-12-01
Developing the ability to globally predict the movement of water on the land surface at spatial scales from 1 to 5 km constitute one of grand challenges in land surface modelling. Copying with this grand challenge implies that land surface models (LSM) should be able to make reliable predictions across locations and/or scales other than those used for parameter estimation. In addition to that, data scarcity and quality impose further difficulties in attaining reliable predictions of water and energy fluxes at the scales of interest. Current computational limitations impose also seriously limitations to exhaustively investigate the parameter space of LSM over large domains (e.g. greater than half a million square kilometers). Addressing these challenges require holistic approaches that integrate the best techniques available for parameter estimation, field measurements and remotely sensed data at their native resolutions. An attempt to systematically address these issues is the multiscale parameterisation technique (MPR) that links high resolution land surface characteristics with effective model parameters. This technique requires a number of pedo-transfer functions and a much fewer global parameters (i.e. coefficients) to be inferred by calibration in gauged basins. The key advantage of this technique is the quasi-scale independence of the global parameters which enables to estimate global parameters at coarser spatial resolutions and then to transfer them to (ungauged) areas and scales of interest. In this study we show the ability of this technique to reproduce the observed water fluxes and states over a wide range of climate and land surface conditions ranging from humid to semiarid and from sparse to dense forested regions. Results of transferability of global model parameters in space (from humid to semi-arid basins) and across scales (from coarser to finer) clearly indicate the robustness of this technique. Simulations with coarse data sets (e.g. EOBS
Mass Transfer Model for a Breached Waste Package
International Nuclear Information System (INIS)
Hsu, C.; McClure, J.
2004-01-01
The degradation of waste packages, which are used for the disposal of spent nuclear fuel in the repository, can result in configurations that may increase the probability of criticality. A mass transfer model is developed for a breached waste package to account for the entrainment of insoluble particles. In combination with radionuclide decay, soluble advection, and colloidal transport, a complete mass balance of nuclides in the waste package becomes available. The entrainment equations are derived from dimensionless parameters such as drag coefficient and Reynolds number and based on the assumption that insoluble particles are subjected to buoyant force, gravitational force, and drag force only. Particle size distributions are utilized to calculate entrainment concentration along with geochemistry model abstraction to calculate soluble concentration, and colloid model abstraction to calculate colloid concentration and radionuclide sorption. Results are compared with base case geochemistry model, which only considers soluble advection loss
Modeling of condensation heat transfer in a reactor containment
International Nuclear Information System (INIS)
Kim, M.H.; Corradini, M.L.
1990-01-01
This paper proposes a set of condensation models for forced and natural convection in the presence of a noncondensable gas. A simple model is derived by using the analogy between mass, momentum and energy transfer. The effects of a wavy interface are implemented in this model by using correlations for a rough wall surface. A two-dimensional condensation model using a k-ε model for the turbulent vapor-air flow was also developed to investigate the effect of two-dimensional flow and to provide a sound theoretical basis for the simple model. Each model is compared with the available 'separate effects' experimental data. The forced convection model is then compared to the Carolinas Virginia Tube Reactor (CVTR) integral test by using the vapor-air velocity predicted by a separate two-dimensional fluid dynamics model. The effect of counter-current flow is also considered in this comparison. The natural convection model is also compared to the steady-state integral data of Tagami. The comparison shows good agreement with both sets of experimental data. (orig.)
Species distribution model transferability and model grain size - finer may not always be better.
Manzoor, Syed Amir; Griffiths, Geoffrey; Lukac, Martin
2018-05-08
Species distribution models have been used to predict the distribution of invasive species for conservation planning. Understanding spatial transferability of niche predictions is critical to promote species-habitat conservation and forecasting areas vulnerable to invasion. Grain size of predictor variables is an important factor affecting the accuracy and transferability of species distribution models. Choice of grain size is often dependent on the type of predictor variables used and the selection of predictors sometimes rely on data availability. This study employed the MAXENT species distribution model to investigate the effect of the grain size on model transferability for an invasive plant species. We modelled the distribution of Rhododendron ponticum in Wales, U.K. and tested model performance and transferability by varying grain size (50 m, 300 m, and 1 km). MAXENT-based models are sensitive to grain size and selection of variables. We found that over-reliance on the commonly used bioclimatic variables may lead to less accurate models as it often compromises the finer grain size of biophysical variables which may be more important determinants of species distribution at small spatial scales. Model accuracy is likely to increase with decreasing grain size. However, successful model transferability may require optimization of model grain size.
Radiative Transfer Modeling in Proto-planetary Disks
Kasper, David; Jang-Condell, Hannah; Kloster, Dylan
2016-01-01
Young Stellar Objects (YSOs) are rich astronomical research environments. Planets form in circumstellar disks of gas and dust around YSOs. With ever increasing capabilities of the observational instruments designed to look at these proto-planetary disks, most notably GPI, SPHERE, and ALMA, more accurate interfaces must be made to connect modeling of the disks with observation. PaRTY (Parallel Radiative Transfer in YSOs) is a code developed previously to model the observable density and temperature structure of such a disk by self-consistently calculating the structure of the disk based on radiative transfer physics. We present upgrades we are implementing to the PaRTY code to improve its accuracy and flexibility. These upgrades include: creating a two-sided disk model, implementing a spherical coordinate system, and implementing wavelength-dependent opacities. These upgrades will address problems in the PaRTY code of infinite optical thickness, calculation under/over-resolution, and wavelength-independent photon penetration depths, respectively. The upgraded code will be used to better model disk perturbations resulting from planet formation.
Parallel family trees for transfer matrices in the Potts model
Navarro, Cristobal A.; Canfora, Fabrizio; Hitschfeld, Nancy; Navarro, Gonzalo
2015-02-01
The computational cost of transfer matrix methods for the Potts model is related to the question in how many ways can two layers of a lattice be connected? Answering the question leads to the generation of a combinatorial set of lattice configurations. This set defines the configuration space of the problem, and the smaller it is, the faster the transfer matrix can be computed. The configuration space of generic (q , v) transfer matrix methods for strips is in the order of the Catalan numbers, which grows asymptotically as O(4m) where m is the width of the strip. Other transfer matrix methods with a smaller configuration space indeed exist but they make assumptions on the temperature, number of spin states, or restrict the structure of the lattice. In this paper we propose a parallel algorithm that uses a sub-Catalan configuration space of O(3m) to build the generic (q , v) transfer matrix in a compressed form. The improvement is achieved by grouping the original set of Catalan configurations into a forest of family trees, in such a way that the solution to the problem is now computed by solving the root node of each family. As a result, the algorithm becomes exponentially faster than the Catalan approach while still highly parallel. The resulting matrix is stored in a compressed form using O(3m ×4m) of space, making numerical evaluation and decompression to be faster than evaluating the matrix in its O(4m ×4m) uncompressed form. Experimental results for different sizes of strip lattices show that the parallel family trees (PFT) strategy indeed runs exponentially faster than the Catalan Parallel Method (CPM), especially when dealing with dense transfer matrices. In terms of parallel performance, we report strong-scaling speedups of up to 5.7 × when running on an 8-core shared memory machine and 28 × for a 32-core cluster. The best balance of speedup and efficiency for the multi-core machine was achieved when using p = 4 processors, while for the cluster
Modeling of heat and mass transfer in lateritic building envelopes
International Nuclear Information System (INIS)
Meukam, Pierre
2004-10-01
The aim of the present work is to investigate the behavior of building envelopes made of local lateritic soil bricks subjected to different climatic conditions. The analysis is developed for the prediction of the temperature, relative humidity and water content behavior within the walls. The building envelopes studied in this work consist of lateritic soil bricks with incorporation of natural pozzolan or sawdust in order to obtain small thermal conductivity and low-density materials, and limit the heat transfer between the atmospheric climate and the inside environment. In order to describe coupled heat and moisture transfer in wet porous materials, the coupled equations were solved by the introduction of diffusion coefficients. A numerical model HMtrans, developed for prediction of beat and moisture transfer in multi-layered building components, was used to simulate the temperature, water content and relative humidity profiles within the building envelopes. The results allow the prediction of the duration of the exposed building walls to the local weather conditions. They show that for any of three climatic conditions considered, relative humidity and water content do not exceed 87% and 5% respectively. There is therefore minimum possibility of water condensation in the materials studied. The durability of building envelopes made of lateritic soil bricks with incorporation of natural pozzolan or sawdust is not strongly affected by the climatic conditions in tropical and equatorial regions. (author)
Heat transfer modeling of double-side arc welding
International Nuclear Information System (INIS)
Sun Junsheng; Wu Chuansong
2002-01-01
If a plasma arc and a TIG arc are connected in serial and with the plasma arc placed on the obverse side and the TIG arc on the opposite side of the workpiece, a special double-side arc welding (DSAW) system will be formed, in which the PAW current is forced to flow through the keyhole along the thickness direction so as to compensate the energy consumed for melting the workpiece and improve the penetration capacity of the PAW arc. By considering the mechanics factors which influence the DSAW pool geometric shape, the control equations of the pool surface deformation are derived, and the mathematics mode for DSAW heat transfer is established by using boundary-fitted non-orthogonal coordinate systems. With this model, the difference between DSAW and PAW heat transfer is analyzed and the reason for the increase of DSAW penetration is explained from the point of heat transfer. The welding process experiments show that calculated results are in good agreement with measured ones
Recent developments in the modeling of boiling heat transfer mechanisms
International Nuclear Information System (INIS)
Podowski, M.Z.
2009-01-01
Due to the importance of boiling for the analysis of operation and safety of nuclear reactors, extensive efforts have been made in the past to develop a variety of methods and tools to study boiling heat transfer for various geometries and operating conditions. Recent progress in the computational multiphase fluid dynamics (CMFD) methods of two- and multiphase flows has already started opening up new exciting possibilities for using complete multidimensional models to predict the operation of boiling systems under both steady-state and transient conditions. However, such models still require closure laws and boundary conditions, the accuracy of which determines the predictive capabilities of the overall models and the associated CMFD simulations. Because of the complexity of the underlying physical phenomena, boiling heat transfer has traditionally been quantified using phenomenological models and correlations obtained by curve-fitting extensive experimental data. Since simple heuristic formulae are not capable of capturing the effect of various specific experimental conditions and the associated wide scattering of data points, most existing correlations are characterized by large uncertainties which are typically hidden behind the 'logarithmic scale' format of plots. Furthermore, such an approach provides only limited insight into the local phenomena of: nucleation, heated surface material properties, temperature fluctuations, and others. The objectives of this paper are two-fold. First, the state of the art is reviewed in the area of modeling concepts for both pool boiling and forced-convection (bulk and subcooled) boiling. Then, new results are shown concerning the development of new mechanistic models and their validation against experimental data. It is shown that a combination of the proposed theoretical approach with advanced computational methods leads to a dramatic improvement in both our understanding of the physics of boiling and the predictive
Heat transfer modelling of pulsed laser-tissue interaction
Urzova, J.; Jelinek, M.
2018-03-01
Due to their attributes, the application of medical lasers is on the rise in numerous medical fields. From a biomedical point of view, the most interesting applications are the thermal interactions and the photoablative interactions, which effectively remove tissue without excessive heat damage to the remaining tissue. The objective of this work is to create a theoretical model for heat transfer in the tissue following its interaction with the laser beam to predict heat transfer during medical laser surgery procedures. The dimensions of the ablated crater (shape and ablation depth) were determined by computed tomography imaging. COMSOL Multiphysics software was used for temperature modelling. The parameters of tissue and blood, such as density, specific heat capacity, thermal conductivity and diffusivity, were calculated from the chemical ratio. The parameters of laser-tissue interaction, such as absorption and reflection coefficients, were experimentally determined. The parameters of the laser beam were power density, repetition frequency, pulse length and spot dimensions. Heat spreading after laser interaction with tissue was captured using a Fluke thermal camera. The model was verified for adipose tissue, skeletal muscle tissue and heart muscle tissue.
A moving subgrid model for simulation of reflood heat transfer
International Nuclear Information System (INIS)
Frepoli, Cesare; Mahaffy, John H.; Hochreiter, Lawrence E.
2003-01-01
In the quench front and froth region the thermal-hydraulic parameters experience a sharp axial variation. The heat transfer regime changes from single-phase liquid, to nucleate boiling, to transition boiling and finally to film boiling in a small axial distance. One of the major limitations of all the current best-estimate codes is that a relatively coarse mesh is used to solve the complex fluid flow and heat transfer problem in proximity of the quench front during reflood. The use of a fine axial mesh for the entire core becomes prohibitive because of the large computational costs involved. Moreover, as the mesh size decreases, the standard numerical methods based on a semi-implicit scheme, tend to become unstable. A subgrid model was developed to resolve the complex thermal-hydraulic problem at the quench front and froth region. This model is a Fine Hydraulic Moving Grid (FHMG) that overlies a coarse Eulerian mesh in the proximity of the quench front and froth region. The fine mesh moves in the core and follows the quench front as it advances in the core while the rods cool and quench. The FHMG software package was developed and implemented into the COBRA-TF computer code. This paper presents the model and discusses preliminary results obtained with the COBRA-TF/FHMG computer code
Mathematical models of the theory of the radiative transfer
International Nuclear Information System (INIS)
Lin, Ch.
2007-06-01
We are interested in various different models arising in radiative transfer, which describe the interactions between the medium and the photons. The radiation is described in terms of energy and energy flux in the macroscopic view, the material being described by the Euler equations (radiative hydrodynamic model). In another way, the radiation can be seen as a collection of photons, in the microscopic view point; the photons can be absorbed or emitted by the material. The absorption and the emission of photons depend on the internal excitation and ionization state of the material. We begin with the local existence (in time) of smooth solutions to a system coupling the Euler equations and the transfer equation. This system describes the exchange of energy and moment between the radiation and the material. Next, we give an asymptotic discussion for this model in the NON-LTE regime and get a simple system: coupling the Euler equations with an elliptic equation. We show the existence of (smooth) shock profiles to this system and the regularity of the shock profile as a function of the strength of the shock. Then we study the asymptotic stability of the shock profile. Finally, we study a system describing the radiation and the internal state of the material, in the microscopic view point. We prove the existence of the solution to this system and study the convergence towards the statistical equilibrium. The theoretical results are illustrated by numerical simulations. (author)
Transfer Learning for Collaborative Filtering Using a Psychometrics Model
Directory of Open Access Journals (Sweden)
Haijun Zhang
2016-01-01
Full Text Available In a real e-commerce website, usually only a small number of users will give ratings to the items they purchased, and this can lead to the very sparse user-item rating data. The data sparsity issue will greatly limit the recommendation performance of most recommendation algorithms. However, a user may register accounts in many e-commerce websites. If such users’ historical purchasing data on these websites can be integrated, the recommendation performance could be improved. But it is difficult to align the users and items between these websites, and thus how to effectively borrow the users’ rating data of one website (source domain to help improve the recommendation performance of another website (target domain is very challenging. To this end, this paper extended the traditional one-dimensional psychometrics model to multidimension. The extended model can effectively capture users’ multiple interests. Based on this multidimensional psychometrics model, we further propose a novel transfer learning algorithm. It can effectively transfer users’ rating preferences from the source domain to the target domain. Experimental results show that the proposed method can significantly improve the recommendation performance.
A model for transfer baggage handling at airports
DEFF Research Database (Denmark)
Barth, Torben C.; Timler Holm, Janus; Lindorff Larsen, Jakob
This work deals with the handling of baggage from passengers changing aircraft at an airport. The transfer baggage problem is to assign the bags from each arriving aircraft to an infeed area into the airport infrastructure. The infrastructure will then distribute the bags to the handling faciliti...... is studied and future approaches for improving robustness are discussed. The presented solution approach runs successfully as part of the operation control systems at Frankfurt Airport since 2008.......This work deals with the handling of baggage from passengers changing aircraft at an airport. The transfer baggage problem is to assign the bags from each arriving aircraft to an infeed area into the airport infrastructure. The infrastructure will then distribute the bags to the handling facilities...... and robustness. The model can be solved with a commercial MIP-solver. Furthermore, the use of the model in the dynamic environment during daily operations is introduced. The model includes two different approaches for increasing the robustness of the generated solutions. The uncertainty of the input data...
Analyzing availability using transfer function models and cross spectral analysis
International Nuclear Information System (INIS)
Singpurwalla, N.D.
1980-01-01
The paper shows how the methods of multivariate time series analysis can be used in a novel way to investigate the interrelationships between a series of operating (running) times and a series of maintenance (down) times of a complex system. Specifically, the techniques of cross spectral analysis are used to help obtain a Box-Jenkins type transfer function model for the running times and the down times of a nuclear reactor. A knowledge of the interrelationships between the running times and the down times is useful for an evaluation of maintenance policies, for replacement policy decisions, and for evaluating the availability and the readiness of complex systems
Modeling and design of reacting systems with phase transfer catalysis
DEFF Research Database (Denmark)
Piccolo, Chiara; Hodges, George; Piccione, Patrick M.
2011-01-01
Issues related to the design of biphasic (liquid) catalytic reaction operations are discussed. A chemical system involving the reaction of an organic-phase soluble reactant (A) with an aqueous-phase soluble reactant (B) in the presence of phase transfer catalyst (PTC) is modeled and based on it......, some of the design issues related to improved reaction operation are analyzed. Since the solubility of the different forms of the PTC in the organic solvent affects ultimately the catalyst partition coefficients, therefore, the organic solvent plays an important role in the design of PTC-based reacting...
Assessment of interfacial heat transfer models under subcooled flow boiling
Energy Technology Data Exchange (ETDEWEB)
Ribeiro, Guilherme B.; Braz Filho, Francisco A., E-mail: gbribeiro@ieav.cta.br, E-mail: fbraz@ieav.cta.br [Instituto de Estudos Avançados (DCTA/IEAv), São José dos Campos, SP (Brazil). Div. de Energia Nuclear
2017-07-01
The present study concerns a detailed analysis of subcooled flow boiling characteristics under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. An uniform heat flux of 570 kW/m2 and saturation pressure of 4.5 MPa were applied to the channel wall, whereas water mass flux of 900 kg/m2s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of CFD technique for the estimation of wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Different sub-models of interfacial heat transfer coefficient were applied and compared, allowing a better prediction of void fraction along the heated channel. (author)
BUSINESS MODELS FOR TAX AND TRANSFER PRICING PURPOSES
Directory of Open Access Journals (Sweden)
Corlaciu Alexandra
2013-07-01
Full Text Available In order to remain competitive, the multinational enterprises (MNEs are forced by the globalization phenomenon (which manifestation has became more and more stringent to analyze continuously its effectiveness. In this respect, the structure of the business represents an element which might have an important impact for the enterprise’s overall results. This is why, in the last decades, the MNEs granted special attention to business structures and put significant efforts in business restructurings, where the case, with the scope to keep the efficiency and to remain on the market. Generally, the operational business restructuring process follows one of the business model globally developed, namely manufacturer or sales business models. Thus, according to the functions performed, assets used and risks assumed, the entities within the group are labeled into limited risk units (such as toll manufacturer or commission agent, medium risk (contract manufacturer, commissionaire, stripped distributor or high risk units (fully fledged manufacturer, fully fledged distributor. Notwithstanding the above, there should be emphasized that the operational business restructuring has to be undertaken with maximal care, as it might have important fiscal impact. Having this regard, the purpose of the present investigation is to provide, from a tax and transfer pricing point of view, a systematic and structured analysis of the generally characteristics of business models (manufacturer and sales business models used by multinational enterprises in the process of business reorganization, with the scope to increase their performance and the sustainable competitive advantages. Thus, by using the fundamental (theoretical and qualitative research type, this paper is aiming to present the most important characteristics of each business model (general overview of each model, the principal risk assumed, the usual transfer pricing method used for the remuneration of intra
The transferability of hydrological models under nonstationary climatic conditions
Directory of Open Access Journals (Sweden)
C. Z. Li
2012-04-01
Full Text Available This paper investigates issues involved in calibrating hydrological models against observed data when the aim of the modelling is to predict future runoff under different climatic conditions. To achieve this objective, we tested two hydrological models, DWBM and SIMHYD, using data from 30 unimpaired catchments in Australia which had at least 60 yr of daily precipitation, potential evapotranspiration (PET, and streamflow data. Nash-Sutcliffe efficiency (NSE, modified index of agreement (d_{1} and water balance error (WBE were used as performance criteria. We used a differential split-sample test to split up the data into 120 sub-periods and 4 different climatic sub-periods in order to assess how well the calibrated model could be transferred different periods. For each catchment, the models were calibrated for one sub-period and validated on the other three. Monte Carlo simulation was used to explore parameter stability compared to historic climatic variability. The chi-square test was used to measure the relationship between the distribution of the parameters and hydroclimatic variability. The results showed that the performance of the two hydrological models differed and depended on the model calibration. We found that if a hydrological model is set up to simulate runoff for a wet climate scenario then it should be calibrated on a wet segment of the historic record, and similarly a dry segment should be used for a dry climate scenario. The Monte Carlo simulation provides an effective and pragmatic approach to explore uncertainty and equifinality in hydrological model parameters. Some parameters of the hydrological models are shown to be significantly more sensitive to the choice of calibration periods. Our findings support the idea that when using conceptual hydrological models to assess future climate change impacts, a differential split-sample test and Monte Carlo simulation should be used to quantify uncertainties due to
Mass balance model parameter transferability on a tropical glacier
Gurgiser, Wolfgang; Mölg, Thomas; Nicholson, Lindsey; Kaser, Georg
2013-04-01
The mass balance and melt water production of glaciers is of particular interest in the Peruvian Andes where glacier melt water has markedly increased water supply during the pronounced dry seasons in recent decades. However, the melt water contribution from glaciers is projected to decrease with appreciable negative impacts on the local society within the coming decades. Understanding mass balance processes on tropical glaciers is a prerequisite for modeling present and future glacier runoff. As a first step towards this aim we applied a process-based surface mass balance model in order to calculate observed ablation at two stakes in the ablation zone of Shallap Glacier (4800 m a.s.l., 9°S) in the Cordillera Blanca, Peru. Under the tropical climate, the snow line migrates very frequently across most of the ablation zone all year round causing large temporal and spatial variations of glacier surface conditions and related ablation. Consequently, pronounced differences between the two chosen stakes and the two years were observed. Hourly records of temperature, humidity, wind speed, short wave incoming radiation, and precipitation are available from an automatic weather station (AWS) on the moraine near the glacier for the hydrological years 2006/07 and 2007/08 while stake readings are available at intervals of between 14 to 64 days. To optimize model parameters, we used 1000 model simulations in which the most sensitive model parameters were varied randomly within their physically meaningful ranges. The modeled surface height change was evaluated against the two stake locations in the lower ablation zone (SH11, 4760m) and in the upper ablation zone (SH22, 4816m), respectively. The optimal parameter set for each point achieved good model skill but if we transfer the best parameter combination from one stake site to the other stake site model errors increases significantly. The same happens if we optimize the model parameters for each year individually and transfer
MODELING OF TRANSIENT HEAT TRANSFER IN FOAMED CONCRETE SLAB
Directory of Open Access Journals (Sweden)
MD AZREE OTHUMAN MYDIN
2013-06-01
Full Text Available This paper reports the basis of one-dimensional Finite Difference method to obtain thermal properties of foamed concrete in order to solve transient heat conduction problems in multi-layer panels. In addition, this paper also incorporates the implementation of the method and the validation of thermal properties model of foamed concrete. A one-dimensional finite difference heat conduction programme has been developed to envisage the temperature development through the thickness of the foamed concrete slab, based on an initial estimate of the thermal conductivity-temperature relationship as a function of porosity and radiation within the voids. The accuracy of the model was evaluated by comparing predicted and experimental temperature profiles obtained from small scale heat transfer test on foamed concrete slabs, so that the temperature history of the specimen calculated by the programme closely matches those recorded during the experiment. Using the thermal properties of foamed concrete, the validated heat transfer program predicts foamed concrete temperatures in close agreement with experimental results obtained from a number of high temperature tests. The proposed numerical and thermal properties are simple yet efficient and can be utilised to aid manufacturers to develop their products without having to conduct numerous large-scale fire tests.
The Mathematical Modelling of Heat Transfer in Electrical Cables
Directory of Open Access Journals (Sweden)
Bugajev Andrej
2014-05-01
Full Text Available This paper describes a mathematical modelling approach for heat transfer calculations in underground high voltage and middle voltage electrical power cables. First of the all typical layout of the cable in the sand or soil is described. Then numerical algorithms are targeted to the two-dimensional mathematical models of transient heat transfer. Finite Volume Method is suggested for calculations. Different strategies of nonorthogonality error elimination are considered. Acute triangles meshes were applied in two-dimensional domain to eliminate this error. Adaptive mesh is also tried. For calculations OpenFOAM open source software which uses Finite Volume Method is applied. To generate acute triangles meshes aCute library is used. The efficiency of the proposed approach is analyzed. The results show that the second order of convergence or close to that is achieved (in terms of sizes of finite volumes. Also it is shown that standard strategy, used by OpenFOAM is less efficient than the proposed approach. Finally it is concluded that for solving real problem a spatial adaptive mesh is essential and adaptive time steps also may be needed.
An interdisciplinary approach to modeling tritium transfer into the environment
International Nuclear Information System (INIS)
Galeriu, D; Melintescu, A.
2005-01-01
More robust radiological assessment models are required to support the safety case for the nuclear industry. Heavy water reactors, fuel processing plants, radiopharmaceutical factories, and the future fusion reactor, all have large tritium loads. While of low probability, large accidental tritium releases cannot be ignored. For Romania that uses CANDU600 for nuclear energy, tritium is the national radionuclide. Tritium enters directly into the life cycle in many physicochemical forms. Tritiated water (HTO) is leaked from most nuclear installations but is partially converted into organically bound tritium (OBT) through plant and animal metabolic processes. Hydrogen and carbon are elemental components of major nutrients and animal tissues and their radioisotopes must be modeled differently from those of most other radionuclides. Tritium transfer from atmosphere to plant and conversion into organically bound tritium strongly depend on plant characteristics, season, and weather conditions. In order to cope with this large variability and avoid expensive calibration experiments, we developed a model using knowledge of plant physiology, agrometeorology, soil sciences, hydrology, and climatology. The transfer of tritiated water to plant was modeled with resistance approach including sparse canopy. The canopy resistance was modeled using the Jarvis-Calvet approach modified in order to make direct use of the canopy photosynthesis rate. The crop growth model WOFOST was used for photosynthesis rate both for canopy resistance and formation of organically bound tritium. Using this formalism, the tritium transfer parameters were directly linked to processes and parameters known from agricultural sciences. Model predictions for tritium in wheat were close to a factor two, according to experimental data without any calibration. The model was also tested on rice and soybean and can be applied for various plants and environmental conditions. For sparse canopy, the model used coupled
International Nuclear Information System (INIS)
Boyer, B.D.; Parlatan, Y.; Slovik, G.C.
1995-01-01
RELAP5 MOD3.1.1 is being used to simulate Loss of Coolant Accidents (LOCA) for the Simplified Boiling Water Reactor (SBWR) being proposed by General Electric (GE). One of the major components associated with the SBWR is the Passive Containment Cooling System (PCCS) which provides the long-term heat sink to reject decay heat. The RELAP5 MOD3.1.1 code is being assessed for its ability to represent accurately the PCCS. Data from the Phase 1, Step 1 Heat Transfer Tests performed at Toshiba's Gravity-Driven Integral Full-Height Test for Passive Heat Removal (GIRAFFE) facility will be used for assessing the ability of RELAP5 to model condensation in the presence of noncondensables. The RELAP5 MOD3.1.1 condensation model uses the University of California at Berkeley (UCB) correlation developed by Vierow and Schrock. The RELAP5 code uses this heat transfer coefficient with the gas velocity effect multiplier being limited to 2. This heat transfer option was used to analyze the condensation heat transfer in the GIRAFFE PCCS heat exchanger tubes in the Phase 1, Step 1 Heat Transfer Tests which were at a pressure of 3 bar and had a range of nitrogen partial pressure fractions from 0.0 to 0.10. The results of a set of RELAP5 calculations at these conditions were compared with the GIRAFFE data. The effects of PCCS cell noding on the heat transfer process were also studied. The UCB correlation, as implemented in RELAP5, predicted the heat transfer to ±5% of the data with a three--node model. The three-node model has a large cell in the entrance region which smeared out the entrance effects on the heat transfer, which tend to overpredict the condensation. Hence, the UCB correlation predicts condensation heat transfer correlation implemented in the code must be removed to allow for accurate calculations with smaller cell sizes
Energy Technology Data Exchange (ETDEWEB)
Boyer, B.D.; Parlatan, Y.; Slovik, G.C. [and others
1995-09-01
RELAP5 MOD3.1.1 is being used to simulate Loss of Coolant Accidents (LOCA) for the Simplified Boiling Water Reactor (SBWR) being proposed by General Electric (GE). One of the major components associated with the SBWR is the Passive Containment Cooling System (PCCS) which provides the long-term heat sink to reject decay heat. The RELAP5 MOD3.1.1 code is being assessed for its ability to represent accurately the PCCS. Data from the Phase 1, Step 1 Heat Transfer Tests performed at Toshiba`s Gravity-Driven Integral Full-Height Test for Passive Heat Removal (GIRAFFE) facility will be used for assessing the ability of RELAP5 to model condensation in the presence of noncondensables. The RELAP5 MOD3.1.1 condensation model uses the University of California at Berkeley (UCB) correlation developed by Vierow and Schrock. The RELAP5 code uses this heat transfer coefficient with the gas velocity effect multiplier being limited to 2. This heat transfer option was used to analyze the condensation heat transfer in the GIRAFFE PCCS heat exchanger tubes in the Phase 1, Step 1 Heat Transfer Tests which were at a pressure of 3 bar and had a range of nitrogen partial pressure fractions from 0.0 to 0.10. The results of a set of RELAP5 calculations at these conditions were compared with the GIRAFFE data. The effects of PCCS cell noding on the heat transfer process were also studied. The UCB correlation, as implemented in RELAP5, predicted the heat transfer to {plus_minus}5% of the data with a three--node model. The three-node model has a large cell in the entrance region which smeared out the entrance effects on the heat transfer, which tend to overpredict the condensation. Hence, the UCB correlation predicts condensation heat transfer correlation implemented in the code must be removed to allow for accurate calculations with smaller cell sizes.
Modelling of complex heat transfer systems by the coupling method
Energy Technology Data Exchange (ETDEWEB)
Bacot, P.; Bonfils, R.; Neveu, A.; Ribuot, J. (Centre d' Energetique de l' Ecole des Mines de Paris, 75 (France))
1985-04-01
The coupling method proposed here is designed to reduce the size of matrices which appear in the modelling of heat transfer systems. It consists in isolating the elements that can be modelled separately, and among the input variables of a component, identifying those which will couple it to another component. By grouping these types of variable, one can thus identify a so-called coupling matrix of reduced size, and relate it to the overall system. This matrix allows the calculation of the coupling temperatures as a function of external stresses, and of the state of the overall system at the previous instant. The internal temperatures of the components are determined from for previous ones. Two examples of applications are presented, one concerning a dwelling unit, and the second a solar water heater.
A TRANSFERABLE MODEL FOR INNOVATIVE JOINT POSTGRADUATE DEGREE PROGRAMME DEVELOPMENT
DEFF Research Database (Denmark)
Maclachlan, Ross; Ion, William; Kochanowska, Rowena
2009-01-01
aim of the programme is to produce graduates with an expanded perspective of innovation management to meet the needs of global industry. In particular this is to be achieved through a curriculum that integrates design based modules with progressive innovation and technology management education....... The collaboration brings depth and breadth to the innovation curriculum, and the student experience, through student mobility and the complementary expertise of partners. However, for higher education institutions to effectively collaborate at both administrative and academic levels, a number of new challenges must...... be overcome. This paper reflects on specific challenges met during development of the GIM programme and presents a programme model addressing these. The model is presented as transferable to other consortia and as basis for a set of tentative principles for joint programme development with particular...
Heat transfer corrected isothermal model for devolatilization of thermally-thick biomass particles
DEFF Research Database (Denmark)
Luo, Hao; Wu, Hao; Lin, Weigang
Isothermal model used in current computational fluid dynamic (CFD) model neglect the internal heat transfer during biomass devolatilization. This assumption is not reasonable for thermally-thick particles. To solve this issue, a heat transfer corrected isothermal model is introduced. In this model......, two heat transfer corrected coefficients: HT-correction of heat transfer and HR-correction of reaction, are defined to cover the effects of internal heat transfer. A series of single biomass devitalization case have been modeled to validate this model, the results show that devolatilization behaviors...... of both thermally-thick and thermally-thin particles are predicted reasonable by using heat transfer corrected model, while, isothermal model overestimate devolatilization rate and heating rate for thermlly-thick particle.This model probably has better performance than isothermal model when it is coupled...
Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method
Eluszkiewicz, J.; Cady-Pereira, K.; Uymin, G.; Moncet, J.-L.
2005-01-01
The large volume of existing and planned infrared observations of Mars have prompted the development of a new martian radiative transfer model that could be used in the retrievals of atmospheric and surface properties. The model is based on the Optimal Spectral Sampling (OSS) method [1]. The method is a fast and accurate monochromatic technique applicable to a wide range of remote sensing platforms (from microwave to UV) and was originally developed for the real-time processing of infrared and microwave data acquired by instruments aboard the satellites forming part of the next-generation global weather satellite system NPOESS (National Polarorbiting Operational Satellite System) [2]. As part of our on-going research related to the radiative properties of the martian polar caps, we have begun the development of a martian OSS model with the goal of using it to perform self-consistent atmospheric corrections necessary to retrieve caps emissivity from the Thermal Emission Spectrometer (TES) spectra. While the caps will provide the initial focus area for applying the new model, it is hoped that the model will be of interest to the wider Mars remote sensing community.
Transferability of SWAT Models between SWAT2009 and SWAT2012.
Seo, Mijin; Yen, Haw; Kim, Min-Kyeong; Jeong, Jaehak
2014-05-01
In recent years, the Soil and Water Assessment Tool (SWAT) has experienced upgrades with enhanced functionalities and modeling capacities as it gets to the current version, SWAT2012. Changes in the SWAT code on a specific process may result in propagating influences in the output of other related processes. In this study, the characteristic significance of the enhancements in SWAT code was investigated using the two recent versions, SWAT2009 and SWAT2012. Using a global optimization technique, each model was calibrated for flow, sediment, and nutrient and then tested for transferability of parameters between the models. Results indicate that flow and water quality output were well calibrated with both models. However, the calibrated parameters determined by SWAT2009 and SWAT2012 were noticeably different, due mostly to the enhancements made in SWAT2012. Our results indicate that only the stream flow result was reliable when the models were upgraded or downgraded between the two versions after calibration. Sediment prediction was marginally reliable. SWAT parameters were nontransferrable if nutrient was the main output. The differences are due to various reasons, such as disparities in algorithms at the process level and propagation of the resulting uncertainty into higher-order processes. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
Modelling of heat transfer during torrefaction of large lignocellulosic biomass
Regmi, Bharat; Arku, Precious; Tasnim, Syeda Humaira; Mahmud, Shohel; Dutta, Animesh
2018-07-01
Preparation of feedstock is a major energy intensive process for the thermochemical conversion of biomass into fuel. By eliminating the need to grind biomass prior to the torrefaction process, there would be a potential gain in the energy requirements as the entire step would be eliminated. In regards to a commercialization of torrefaction technology, this study has examined heat transfer inside large cylindrical biomass both numerically and experimentally during torrefaction. A numerical axis-symmetrical 2-D model for heat transfer during torrefaction at 270°C for 1 h was created in COMSOL Multiphysics 5.1 considering heat generation evaluated from the experiment. The model analyzed the temperature distribution within the core and on the surface of biomass during torrefaction for various sizes. The model results showed similarities with experimental results. The effect of L/D ratio on temperature distribution within biomass was observed by varying length and diameter and compared with experiments in literature to find out an optimal range of cylindrical biomass size suitable for torrefaction. The research demonstrated that a cylindrical biomass sample of 50 mm length with L/D ratio of 2 can be torrefied with a core-surface temperature difference of less than 30 °C. The research also demonstrated that sample length has a negligible effect on core-surface temperature difference during torrefaction when the diameter is fixed at 25 mm. This information will help to design a torrefaction processing system and develop a value chain for biomass supply without using an energy-intensive grinding process.
Modelling of heat transfer during torrefaction of large lignocellulosic biomass
Regmi, Bharat; Arku, Precious; Tasnim, Syeda Humaira; Mahmud, Shohel; Dutta, Animesh
2018-02-01
Preparation of feedstock is a major energy intensive process for the thermochemical conversion of biomass into fuel. By eliminating the need to grind biomass prior to the torrefaction process, there would be a potential gain in the energy requirements as the entire step would be eliminated. In regards to a commercialization of torrefaction technology, this study has examined heat transfer inside large cylindrical biomass both numerically and experimentally during torrefaction. A numerical axis-symmetrical 2-D model for heat transfer during torrefaction at 270°C for 1 h was created in COMSOL Multiphysics 5.1 considering heat generation evaluated from the experiment. The model analyzed the temperature distribution within the core and on the surface of biomass during torrefaction for various sizes. The model results showed similarities with experimental results. The effect of L/D ratio on temperature distribution within biomass was observed by varying length and diameter and compared with experiments in literature to find out an optimal range of cylindrical biomass size suitable for torrefaction. The research demonstrated that a cylindrical biomass sample of 50 mm length with L/D ratio of 2 can be torrefied with a core-surface temperature difference of less than 30 °C. The research also demonstrated that sample length has a negligible effect on core-surface temperature difference during torrefaction when the diameter is fixed at 25 mm. This information will help to design a torrefaction processing system and develop a value chain for biomass supply without using an energy-intensive grinding process.
Modelling of convective heat and mass transfer in rotating flows
Shevchuk, Igor V
2016-01-01
This monograph presents results of the analytical and numerical modeling of convective heat and mass transfer in different rotating flows caused by (i) system rotation, (ii) swirl flows due to swirl generators, and (iii) surface curvature in turns and bends. Volume forces (i.e. centrifugal and Coriolis forces), which influence the flow pattern, emerge in all of these rotating flows. The main part of this work deals with rotating flows caused by system rotation, which includes several rotating-disk configurations and straight pipes rotating about a parallel axis. Swirl flows are studied in some of the configurations mentioned above. Curvilinear flows are investigated in different geometries of two-pass ribbed and smooth channels with 180° bends. The author demonstrates that the complex phenomena of fluid flow and convective heat transfer in rotating flows can be successfully simulated using not only the universal CFD methodology, but in certain cases by means of the integral methods, self-similar and analyt...
Transferability of polarizable models for ion-water electrostatic interaction
International Nuclear Information System (INIS)
Masia, Marco
2009-01-01
Studies of ion-water systems at condensed phase and at interfaces have pointed out that molecular and ionic polarization plays an important role for many phenomena ranging from hydrogen bond dynamics to water interfaces' structure. Classical and ab initio Molecular Dynamics simulations reveal that induced dipole moments at interfaces (e.g. air-water and water-protein) are usually high, hinting that polarizable models to be implemented in classical force fields should be very accurate in reproducing the electrostatic properties of the system. In this paper the electrostatic properties of three classical polarizable models for ion-water interaction are compared with ab initio results both at gas and condensed phase. For Li + - water and Cl - -water dimers the reproducibility of total dipole moments obtained with high level quantum chemical calculations is studied; for the same ions in liquid water, Car-Parrinello Molecular Dynamics simulations are used to compute the time evolution of ionic and molecular dipole moments, which are compared with the classical models. The PD2-H2O model developed by the author and coworkers [Masia et al. J. Chem. Phys. 2004, 121, 7362] together with the gaussian intermolecular damping for ion-water interaction [Masia et al. J. Chem. Phys. 2005, 123, 164505] showed to be the fittest in reproducing the ab initio results from gas to condensed phase, allowing for force field transferability.
Using CASE to Exploit Process Modeling in Technology Transfer
Renz-Olar, Cheryl
2003-01-01
A successful business will be one that has processes in place to run that business. Creating processes, reengineering processes, and continually improving processes can be accomplished through extensive modeling. Casewise(R) Corporate Modeler(TM) CASE is a computer aided software engineering tool that will enable the Technology Transfer Department (TT) at NASA Marshall Space Flight Center (MSFC) to capture these abilities. After successful implementation of CASE, it could then go on to be applied in other departments at MSFC and other centers at NASA. The success of a business process is dependent upon the players working as a team and continuously improving the process. A good process fosters customer satisfaction as well as internal satisfaction in the organizational infrastructure. CASE provides a method for business process success through functions consisting of systems and processes business models; specialized diagrams; matrix management; simulation; report generation and publishing; and, linking, importing, and exporting documents and files. The software has an underlying repository or database to support these functions. The Casewise. manual informs us that dynamics modeling is a technique used in business design and analysis. Feedback is used as a tool for the end users and generates different ways of dealing with the process. Feedback on this project resulted from collection of issues through a systems analyst interface approach of interviews with process coordinators and Technical Points of Contact (TPOCs).
Dynamic model for tritium transfer in an aquatic food chain.
Melintescu, A; Galeriu, D
2011-08-01
Tritium ((3)H) is released from some nuclear facilities in relatively large quantities. It is a ubiquitous isotope because it enters straight into organisms, behaving essentially identically to its stable analogue (hydrogen). Tritium is a key radionuclide in the aquatic environment, in some cases, contributing significantly to the doses received by aquatic, non-human biota and by humans. The updated model presented here is based on more standardized, comprehensive assessments than previously used for the aquatic food chain, including the benthic flora and fauna, with an explicit application to the Danube ecosystem, as well as an extension to the special case of dissolved organic tritium (DOT). The model predicts the organically bound tritium (OBT) in the primary producers (the autotrophs, such as phytoplankton and algae) and in the consumers (the heterotrophs) using their bioenergetics, which involves the investigation of energy expenditure, losses, gains and efficiencies of transformations in the body. The model described in the present study intends to be more specific than a screening-level model, by including a metabolic approach and a description of the direct uptake of DOT in marine phytoplankton and invertebrates. For a better control of tritium transfer into the environment, not only tritiated water must be monitored, but also the other chemical forms and most importantly OBT, in the food chain.
Porosity model for simultaneous radionuclide transfer in compact clay
International Nuclear Information System (INIS)
Grambow, B.; Ribet, S.; Landesman, C.; Altman, S.
2010-01-01
Document available in extended abstract form only. Both, a mono and a dual porosity model have been developed to describe diffusion in bentonite as function of compaction, which give similar results for the diffusion coefficients. There are little advantages but more computation time for the dual porosity model compared to the mono-porosity model. A significant change in paradigm has been proposed to describe diffusion accessible porosity in bentonite: Only a single micro-porosity value is considered for anions, cations and neutral species. Hydration water in the interlayers is considered as part of the solid phase and is not considered as a constitutive part of overall porosity. Since hydration water takes part of the solid phase, it is now possible to explicitly account for retention of HTO by formulating exchange between HTO and water in the interlayers. In the adaptation of the model to experimental data, a single fit constant, the geometric factor G = 7 was used, common to all ions and neutral species and for densities between 0.2 and 1.8 kg.dm -3 . The only input parameters to describe the effect of dry density on diffusion coefficients are the micro porosity (total porosity minus interlayer porosity) and the hydration numbers of exchanging cations in the interlayers, both of which can be measured by independent means (DRX, water sorption isotherms). The modelling of simultaneous mass transfer of HTO, Cs, Br and Ni has been undertaken. From the results apparent diffusion coefficients were obtained. Effective diffusion coefficients can of course only be compared to literature data if the the same porosity hypothesis is used for Da-De conversion as used in literature (total porosity for anions and HTO, micro-porosity for anions). Then, the calculated apparent diffusion coefficients for HTO match closely the measured values in the mentioned density range. Considering large experimental data uncertainty the agreement between anion diffusion data and calculations
Transferable coarse-grained model for perfluorosulfonic acid polymer membranes
Kuo, An-Tsung; Okazaki, Susumu; Shinoda, Wataru
2017-09-01
Perfluorosulfonic acid (PFSA) polymer membranes are widely used as proton exchange membranes. Because the structure of the aqueous domain within the PFSA membrane is expected to directly influence proton conductance, many coarse-grained (CG) simulation studies have been performed to investigate the membrane morphology; these studies mostly used phenomenological models, such as dissipative particle dynamics. However, a chemically accurate CG model is required to investigate the morphology in realistic membranes and to provide a concrete molecular design. Here, we attempt to construct a predictive CG model for the structure and morphology of PFSA membranes that is compatible with the Sinoda-DeVane-Klein (SDK) CG water model [Shinoda et al., Mol. Simul. 33, 27 (2007)]. First, we extended the parameter set for the SDK CG force field to examine a hydrated PFSA membrane based on thermodynamic and structural data from experiments and all-atom (AA) molecular dynamics (MD) simulations. However, a noticeable degradation of the morphology motivated us to improve the structural properties by using the iterative Boltzmann inversion (IBI) approach. Thus, we explored a possible combination of the SDK and IBI approaches to describe the nonbonded interaction. The hybrid SDK/IBI model improved the structural issues of SDK, showing a better agreement with AA-MD in the radial distribution functions. The hybrid SDK/IBI model was determined to reasonably reproduce both the thermodynamic and structural properties of the PFSA membrane for all examined water contents. In addition, the model demonstrated good transferability and has considerable potential for application to realistic long-chained PFSA membranes.
Energy Technology Data Exchange (ETDEWEB)
Dyrboel, Susanne
1998-05-01
Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For large thickness dimensions the resulting heat transfer through the
On Two-Scale Modelling of Heat and Mass Transfer
International Nuclear Information System (INIS)
Vala, J.; Stastnik, S.
2008-01-01
Modelling of macroscopic behaviour of materials, consisting of several layers or components, whose microscopic (at least stochastic) analysis is available, as well as (more general) simulation of non-local phenomena, complicated coupled processes, etc., requires both deeper understanding of physical principles and development of mathematical theories and software algorithms. Starting from the (relatively simple) example of phase transformation in substitutional alloys, this paper sketches the general formulation of a nonlinear system of partial differential equations of evolution for the heat and mass transfer (useful in mechanical and civil engineering, etc.), corresponding to conservation principles of thermodynamics, both at the micro- and at the macroscopic level, and suggests an algorithm for scale-bridging, based on the robust finite element techniques. Some existence and convergence questions, namely those based on the construction of sequences of Rothe and on the mathematical theory of two-scale convergence, are discussed together with references to useful generalizations, required by new technologies.
On Two-Scale Modelling of Heat and Mass Transfer
Vala, J.; Št'astník, S.
2008-09-01
Modelling of macroscopic behaviour of materials, consisting of several layers or components, whose microscopic (at least stochastic) analysis is available, as well as (more general) simulation of non-local phenomena, complicated coupled processes, etc., requires both deeper understanding of physical principles and development of mathematical theories and software algorithms. Starting from the (relatively simple) example of phase transformation in substitutional alloys, this paper sketches the general formulation of a nonlinear system of partial differential equations of evolution for the heat and mass transfer (useful in mechanical and civil engineering, etc.), corresponding to conservation principles of thermodynamics, both at the micro- and at the macroscopic level, and suggests an algorithm for scale-bridging, based on the robust finite element techniques. Some existence and convergence questions, namely those based on the construction of sequences of Rothe and on the mathematical theory of two-scale convergence, are discussed together with references to useful generalizations, required by new technologies.
Modelization of tritium transfer into the organic compartments of algae
International Nuclear Information System (INIS)
Bonotto, S.; Gerber, G.B.; Arapis, G.; Kirchmann, R.
1982-01-01
Uptake of tritium oxide and its conversion into organic tritium was studied in four different types of algae with widely varying size and growth characteristics (Acetabularia acetabulum, Boergesenia forbesii, two strains of Chlamydomonas and Dunaliella bioculata). Water in the cell and the vacuales equilibrates rapidly with external tritium water. Tritium is actively incorporated into organically bound form as the organisms grow. During the stationary phase, incorporation of tritium is slow. There exists a discrimination against the incorporation of tritium into organically bound form. A model has been elaborated taking in account these different factors. It appears that transfer of organic tritium by algae growing near the sites of release would be significant only for actively growing algae. Algae growing slowly may, however, be useful as cumulative indicators of discontinuous tritium release. (author)
Turbulence model for melt pool natural convection heat transfer
International Nuclear Information System (INIS)
Kelkar, K.M.; Patankar, S.V.
1994-01-01
Under severe reactor accident scenarios, pools of molten core material may form in the reactor core or in the hemispherically shaped lower plenum of the reactor vessel. Such molten pools are internally heated due to the radioactive decay heat that gives rise to buoyant flows in the molten pool. The flow in such pools is strongly influenced by the turbulent mixing because the expected Rayleigh numbers under accidents scenarios are very high. The variation of the local heat flux over the boundaries of the molten pools are important in determining the subsequent melt progression behavior. This study reports results of an ongoing effort towards providing a well validated mathematical model for the prediction of buoyant flow and heat transfer in internally heated pool under conditions expected in severe accident scenarios
Mass transfer inside oblate spheroidal solids: modelling and simulation
Directory of Open Access Journals (Sweden)
J. E. F. Carmo
2008-03-01
Full Text Available A numerical solution of the unsteady diffusion equation describing mass transfer inside oblate spheroids, considering a constant diffusion coefficient and the convective boundary condition, is presented. The diffusion equation written in the oblate spheroidal coordinate system was used for a two-dimensional case. The finite-volume method was employed to discretize the basic equation. The linear equation set was solved iteratively using the Gauss-Seidel method. As applications, the effects of the Fourier number, the Biot number and the aspect ratio of the body on the drying rate and moisture content during the process are presented. To validate the methodology, results obtained in this work are compared with analytical results of the moisture content encountered in the literature and good agreement was obtained. The results show that the model is consistent and it may be used to solve cases such as those that include disks and spheres and/or those with variable properties with small modifications.
Emerge - A Python environment for the modeling of subsurface transfers
Lopez, S.; Smai, F.; Sochala, P.
2014-12-01
The simulation of subsurface mass and energy transfers often relies on specific codes that were mainly developed using compiled languages which usually ensure computational efficiency at the expense of relatively long development times and relatively rigid software. Even if a very detailed, possibly graphical, user-interface is developed the core numerical aspects are rarely accessible and the smallest modification will always need a compilation step. Thus, user-defined physical laws or alternative numerical schemes may be relatively difficult to use. Over the last decade, Python has emerged as a popular and widely used language in the scientific community. There already exist several libraries for the pre and post-treatment of input and output files for reservoir simulators (e.g. pytough). Development times in Python are considerably reduced compared to compiled languages, and programs can be easily interfaced with libraries written in compiled languages with several comprehensive numerical libraries that provide sequential and parallel solvers (e.g. PETSc, Trilinos…). The core objective of the Emerge project is to explore the possibility to develop a modeling environment in full Python. Consequently, we are developing an open python package with the classes/objects necessary to express, discretize and solve the physical problems encountered in the modeling of subsurface transfers. We heavily relied on Python to have a convenient and concise way of manipulating potentially complex concepts with a few lines of code and a high level of abstraction. Our result aims to be a friendly numerical environment targeting both numerical engineers and physicist or geoscientists with the possibility to quickly specify and handle geometries, arbitrary meshes, spatially or temporally varying properties, PDE formulations, boundary conditions…
Turbulence Modeling and Computation of Turbine Aerodynamics and Heat Transfer
Lakshminarayana, B.; Luo, J.
1996-01-01
The objective of the present research is to develop improved turbulence models for the computation of complex flows through turbomachinery passages, including the effects of streamline curvature, heat transfer and secondary flows. Advanced turbulence models are crucial for accurate prediction of rocket engine flows, due to existance of very large extra strain rates, such as strong streamline curvature. Numerical simulation of the turbulent flows in strongly curved ducts, including two 180-deg ducts, one 90-deg duct and a strongly concave curved turbulent boundary layer have been carried out with Reynolds stress models (RSM) and algebraic Reynolds stress models (ARSM). An improved near-wall pressure-strain correlation has been developed for capturing the anisotropy of turbulence in the concave region. A comparative study of two modes of transition in gas turbine, the by-pass transition and the separation-induced transition, has been carried out with several representative low-Reynolds number (LRN) k-epsilon models. Effects of blade surface pressure gradient, freestream turbulence and Reynolds number on the blade boundary layer development, and particularly the inception of transition are examined in detail. The present study indicates that the turbine blade transition, in the presence of high freestream turbulence, is predicted well with LRN k-epsilon models employed. The three-dimensional Navier-Stokes procedure developed by the present authors has been used to compute the three-dimensional viscous flow through the turbine nozzle passage of a single stage turbine. A low Reynolds number k-epsilon model and a zonal k-epsilon/ARSM (algebraic Reynolds stress model) are utilized for turbulence closure. An assessment of the performance of the turbulence models has been carried out. The two models are found to provide similar predictions for the mean flow parameters, although slight improvement in the prediction of some secondary flow quantities has been obtained by the
Reinhold, Sarah; Gegenfurtner, Andreas; Lewalter, Doris
2018-01-01
Social support and motivation to transfer are important components in conceptual models on transfer of training. Previous research indicates that both support and motivation influence transfer. To date, however, it is not yet clear if social support influences transfer of training directly, or if this influence is mediated by motivation to…
Efficient transfer of sensitivity information in multi-component models
International Nuclear Information System (INIS)
Abdel-Khalik, Hany S.; Rabiti, Cristian
2011-01-01
In support of adjoint-based sensitivity analysis, this manuscript presents a new method to efficiently transfer adjoint information between components in a multi-component model, whereas the output of one component is passed as input to the next component. Often, one is interested in evaluating the sensitivities of the responses calculated by the last component to the inputs of the first component in the overall model. The presented method has two advantages over existing methods which may be classified into two broad categories: brute force-type methods and amalgamated-type methods. First, the presented method determines the minimum number of adjoint evaluations for each component as opposed to the brute force-type methods which require full evaluation of all sensitivities for all responses calculated by each component in the overall model, which proves computationally prohibitive for realistic problems. Second, the new method treats each component as a black-box as opposed to amalgamated-type methods which requires explicit knowledge of the system of equations associated with each component in order to reach the minimum number of adjoint evaluations. (author)
Advanced Machine Learning Emulators of Radiative Transfer Models
Camps-Valls, G.; Verrelst, J.; Martino, L.; Vicent, J.
2017-12-01
Physically-based model inversion methodologies are based on physical laws and established cause-effect relationships. A plethora of remote sensing applications rely on the physical inversion of a Radiative Transfer Model (RTM), which lead to physically meaningful bio-geo-physical parameter estimates. The process is however computationally expensive, needs expert knowledge for both the selection of the RTM, its parametrization and the the look-up table generation, as well as its inversion. Mimicking complex codes with statistical nonlinear machine learning algorithms has become the natural alternative very recently. Emulators are statistical constructs able to approximate the RTM, although at a fraction of the computational cost, providing an estimation of uncertainty, and estimations of the gradient or finite integral forms. We review the field and recent advances of emulation of RTMs with machine learning models. We posit Gaussian processes (GPs) as the proper framework to tackle the problem. Furthermore, we introduce an automatic methodology to construct emulators for costly RTMs. The Automatic Gaussian Process Emulator (AGAPE) methodology combines the interpolation capabilities of GPs with the accurate design of an acquisition function that favours sampling in low density regions and flatness of the interpolation function. We illustrate the good capabilities of our emulators in toy examples, leaf and canopy levels PROSPECT and PROSAIL RTMs, and for the construction of an optimal look-up-table for atmospheric correction based on MODTRAN5.
Improved heat transfer modeling of the eye for electromagnetic wave exposures.
Hirata, Akimasa
2007-05-01
This study proposed an improved heat transfer model of the eye for exposure to electromagnetic (EM) waves. Particular attention was paid to the difference from the simplified heat transfer model commonly used in this field. From our computational results, the temperature elevation in the eye calculated with the simplified heat transfer model was largely influenced by the EM absorption outside the eyeball, but not when we used our improved model.
Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model
International Nuclear Information System (INIS)
Park, Jehun; Lee, Jae W.
2016-01-01
This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 .deg. C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.
International Nuclear Information System (INIS)
Boyer, B.D.; Parlatan, Y.; Slovik, G.C.; Rohatgi, U.S.
1995-01-01
RELAP5 MOD3.1.1 is being used to simulate Loss of Coolant Accidents (LOCA) for the Simplified Boiling Water Reactor (SBWR) being proposed by General Electric (GE). One of the major components associated with the SBWR is the Passive Containment Cooling System (PCCS) which provides the long-term heat sink to reject decay heat. The RELAP5 MOD3.1.1 code is being assessed for its ability to represent accurately the PCCS. Data from the Phase 1, Step 1 Heat Transfer Tests performed at Toshiba's Gravity-Driven Integral Full-Height Test for Passive Heat Removal (GIRAFFE) facility will be used for assessing the ability of RELAP5 to model condensation in the presence of noncondensables. The RELAP5 MOD3.1.1 condensation model uses the University of California at Berkeley (UCB) correlation developed by Vierow and Schrock. The RELAP5 code uses this heat transfer coefficient with the gas velocity effect multiplier being limited to 2. This heat transfer option was used to analyze the condensation heat transfer in the GIRAFFE PCCS heat exchanger tubes in the Phase 1, Step 1 Heat Transfer Tests which were at a pressure of 3 bar and had a range of nitrogen partial pressure fractions from 0.0 to 0.10. The results of a set of RELAP5 calculations al these conditions were compared with the GIRAFFE data. The effects of PCCS cell nodings on the heat transfer process were also studied. The UCB correlation, as implemented in RELAP5, predicted the heat transfer to ±5% of the data with a three-node model. The three-node model has a large cell in the entrance region which smeared out the entrance effects on the heat transfer, which tend to overpredict the condensation. Hence, the UCB correlation predicts condensation heat transfer in the presence of noncondensable gases with only a coarse mesh. The cell length term in the condensation heat transfer correlation implemented in the code must be removed to allow for accurate calculations with smaller cell sizes
Development of heat transfer models for gap cooling
Energy Technology Data Exchange (ETDEWEB)
Kohriyama, Tamio; Murase, Michio; Tamaki, Tomohiko [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)
2001-09-01
In a severe accident of a light water reactor (LWR), heat transfer models in a narrow annular gap between superheated core debris and a reactor pressure vessel (RPV) are important to evaluate the integrity of RPV and emergency procedures. This paper discusses the effects of superheat on the heat flux based on existing data. In low superheat conditions, the heat flux in the narrow gap is higher than the heat flux in pool nucleate boiling due to restricted flow area. It approaches the nucleate boiling heat flux as superheat increasing and reaches a critical value subject to the counter-current flow limiting (CCFL) at the top end of the gap. A heat transfer correlation was derived as a function of dimensionless superheat and a Kutateladze-type CCFL correlation was deduced for critical heat flux (CHF) restricted by CCFL, which gave good prediction for a wide range of the CHF data. Effect of an angle of inclination of the gap could also be incorporated in the CCFL correlation. In high superheat conditions, the heat flux in the narrow gap maintains a similar shape to the pool boiling curve but shifts the position to a higher superheated side than the pool boiling except film boiling, which could be expressed by the typical pool film boiling correlation. Incorporating quench test data, the heat flux correlation was derived as a function of dimensionless superheat using the same formula for the low superheat and the Kutateladze-type CCFL correlation was deduced for CHF. The CHF at the high superheat was 3-4 times as large as CHF at the low superheat and this difference was well predicted by different flow patterns in the gap and the balance of pressure gradients between gas and liquid phases. (author)
One dimensional analysis model for condensation heat transfer in feed water heater
International Nuclear Information System (INIS)
Murase, Michio; Takamori, Kazuhide; Aihara, Tsuyoshi
1998-01-01
In order to simplify condensation heat transfer calculations for feed water heaters, one dimensional (1D) analyses were compared with three dimensional (3D) analyses. The results showed that average condensation heat transfer coefficients by 1D analyses with 1/2 rows of heat transfer tubes agreed with those by 3D analyses within 7%. Using the 1D analysis model, effects of the pitch of heat transfer tubes were evaluated. The results showed that the pitch did not affect much on heat transfer rates and that the size of heat transfer tube bundle could be decreased by a small pitch. (author)
A conceptual model of transference and its psychotherapeutic application.
Corradi, Richard B
2006-01-01
The tendency to repeat formative human relationships in later life, a universal developmental characteristic, is referred to as transference when it occurs in the doctor-patient relationship. Its systematic therapeutic application in psychiatry has historically been associated with classical psychoanalysis. As psychoanalysis has lost its cachet, and as drug treatment has replaced psychotherapy as psychiatry's major treatment modality, the therapeutic potential of transference risks being neglected. This is to the great detriment of psychiatric patients. Knowledge of the power of transference and expertise in its clinical use in psychotherapy should be the most powerful tool in the psychiatric therapeutic armamentarium. This article discusses a concept of transference that the author has found effective, both in clinical practice and in teaching about transference to psychiatric residents. The article delineates a psychology of transference, discusses its universal applicability to the whole of the psychotherapeutic process, and utilizes case material to illustrate principles of its application.
An analytical model for annular flow boiling heat transfer in microchannel heat sinks
International Nuclear Information System (INIS)
Megahed, A.; Hassan, I.
2009-01-01
An analytical model has been developed to predict flow boiling heat transfer coefficient in microchannel heat sinks. The new analytical model is proposed to predict the two-phase heat transfer coefficient during annular flow regime based on the separated model. Opposing to the majority of annular flow heat transfer models, the model is based on fundamental conservation principles. The model considers the characteristics of microchannel heat sink during annular flow and eliminates using any empirical closure relations. Comparison with limited experimental data was found to validate the usefulness of this analytical model. The model predicts the experimental data with a mean absolute error 8%. (author)
Best estimate radiation heat transfer model developed for TRAC-BD1
International Nuclear Information System (INIS)
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
Modeling Force Transfer around Openings in Wood-Frame Shear Walls
Minghao Li; Frank Lam; Borjen Yeh; Tom Skaggs; Doug Rammer; James Wacker
2012-01-01
This paper presented a modeling study on force transfer around openings (FTAO) in wood-frame shear walls detailed for FTAO. To understand the load transfer in the walls, this study used a finite-element model WALL2D, which is able to model individual wall components, including framing members, sheathing panels, oriented panel-frame nailed connections, framing...
CO2 Mass transfer model for carbonic anhydrase-enhanced aqueous MDEA solutions
DEFF Research Database (Denmark)
Gladis, Arne Berthold; Deslauriers, Maria Gundersen; Neerup, Randi
2018-01-01
In this study a CO2 mass transfer model was developed for carbonic anhydrase-enhanced MDEA solutions based on a mechanistic kinetic enzyme model. Four different enzyme models were compared in their ability to predict the liquid side mass transfer coefficient at temperatures in the range of 298...
Modelling Graduate Skill Transfer from University to the Workplace
Jackson, Denise
2016-01-01
This study explores skill transfer in graduates as they transition from university to the workplace. Graduate employability continues to dominate higher education agendas yet the transfer of acquired skills is often assumed. The study is prompted by documented concern with graduate performance in certain employability skills, and prevalent skill…
Wireless digital information transfer : Modelling, prediction and assessment
Lager, I.E.; De Hoop, A.T.; Kikkawa, T.
2013-01-01
The loop-to-loop pulsed electromagnetic field wireless signal transfer is investigated with a view on its application in wireless digital information transfer. Closed-form expressions are derived for the emitted magnetic field and for the open-circuit voltage of the receiving loop in dependence on
Zhang, Yaning; Xu, Fei; Li, Bingxi; Kim, Yong-Song; Zhao, Wenke; Xie, Gongnan; Fu, Zhongbin
2018-04-01
This study aims to validate the three-phase heat and mass transfer model developed in the first part (Three phase heat and mass transfer model for unsaturated soil freezing process: Part 1 - model development). Experimental results from studies and experiments were used for the validation. The results showed that the correlation coefficients for the simulated and experimental water contents at different soil depths were between 0.83 and 0.92. The correlation coefficients for the simulated and experimental liquid water contents at different soil temperatures were between 0.95 and 0.99. With these high accuracies, the developed model can be well used to predict the water contents at different soil depths and temperatures.
[Single embryo transfer: is Scandinavian model valuable in France?].
Belaisch-Allart, J; Mayenga, J-M; Grefenstette, I; Chouraqui, A; Serkine, A-M; Abirached, F; Kulski, O
2008-11-01
The aim of infertility treatment is clearly to obtain one healthy baby. If the transfer of a top quality single embryo could provide a baby to all the patients, there would be no more discussion. The problem is that, nowadays, French pregnancy rates after fresh embryo or frozen embryo transfer are not the same as in Nordic countries. All studies show that in unselected patients, single embryo transfer decreases twin pregnancy rate but decreases pregnancy rate too. Pregnancy rate is dependent on embryo quality, women's age, rank of IVF attempt (clear data) but also on body mass index, ovarian reserve, smoking habits. All these data cannot be taken into account in a law. That is the reason why a flexible policy of transfer adapted to each couple is preferable. Each couple and each IVF team are unique and must keep the freedom to choose how many embryos must be transferred to obtain healthy babies, and to avoid twin pregnancies but without demonizing them.
Modelling of flow and heat transfer in PV cooling channels
Energy Technology Data Exchange (ETDEWEB)
Diarra, D.C.; Harrison, S.J. [Queen' s Univ., Kingston, ON (Canada). Dept. of Mechanical and Materials Engineering Solar Calorimetry Lab; Akuffo, F.O. [Kwame Nkrumah Univ. of Science and Technology, Kumasi (Ghana). Dept. of Mechanical Engineering
2005-07-01
Under sunny conditions, the temperature of photovoltaic (PV) modules can be 20 to 30 degrees C above the ambient air temperature. This affects the performance of PV modules, particularly in regions with hot climates. For silicon solar cells, the maximum power decreases between 0.4 and 0.5 per cent for every degree C of temperature increase above a reference value. In an effort to address this issue, this experimental and numerical study examined an active PV panel evaporative cooling scheme that is typically used in hot arid climates. The cooling system circulated cool air behind the PV modules, extracting heat and lowering solar cell temperature. A fluid dynamic and thermal model of the combined system was developed using the EES program in order to study the configuration of the cooling channel and the characteristics of the cooling flow. Heat transfer and flow characteristics in the cooling channel were then calculated along with pressure drop and fan power associated with the air-circulation. The net power output was also calculated. The objective was to design a cost efficient cooling system and to optimize its flow and pressure drop in order to maximize power output. The study demonstrated how the performance of the PV panel is influenced by the geometry of the cooling channel, the inlet air temperature and the air flow rate. 2 refs.
Heat transfer modelling and stability analysis of selective laser melting
International Nuclear Information System (INIS)
Gusarov, A.V.; Yadroitsev, I.; Bertrand, Ph.; Smurov, I.
2007-01-01
The process of direct manufacturing by selective laser melting basically consists of laser beam scanning over a thin powder layer deposited on a dense substrate. Complete remelting of the powder in the scanned zone and its good adhesion to the substrate ensure obtaining functional parts with improved mechanical properties. Experiments with single-line scanning indicate, that an interval of scanning velocities exists where the remelted tracks are uniform. The tracks become broken if the scanning velocity is outside this interval. This is extremely undesirable and referred to as the 'balling' effect. A numerical model of coupled radiation and heat transfer is proposed to analyse the observed instability. The 'balling' effect at high scanning velocities (above ∼20 cm/s for the present conditions) can be explained by the Plateau-Rayleigh capillary instability of the melt pool. Two factors stabilize the process with decreasing the scanning velocity: reducing the length-to-width ratio of the melt pool and increasing the width of its contact with the substrate
Assessment of reflood heat transfer model of COBRA-TIF against ABB-CE evaluation model
Energy Technology Data Exchange (ETDEWEB)
Lee, S. I.; Lee, S. Y.; Park, C. E.; Choi, H. R.; Choi, C. J. [Korea Power Engineering Company Inc., Taejon (Korea, Republic of)
2000-05-01
According to 10 CFR 50 Appendix K, ECCS performance evaluation model should be based on the experimental data of FLECHT and have the conservatism compared with experimental data. To meet this requirement ABB-CE has the complicate code structure as follows: COMPERC-II calculates three reflood rates, and FLELAPC and HTCOF calculate the reflood heat transfer coefficients, and finally STRIKIN-II calculates the cladding temperature using the reflood heat transfer calculated in previous stage. In this paper, to investigate whether or not COBRA-TF satisfies the requirement of Appendix K, the reflood heat transfer coefficient of COBRA-TF was assessed against ABB-CE MOD-2C model. It was found out that COBRA-TF predicts properly the experimental data and has more conservatism than the results of ABB-CE MOD-2C model. Based on these results, it can be concluded that the reflood heat transfer coefficients calculated by COBRA-TF meet the requirement of Appendix K.
Shang, De-Yi
2012-01-01
This book presents recent developments in our systematic studies of hydrodynamics and heat and mass transfer in laminar free convection, accelerating film boiling and condensation of Newtonian fluids, as well as accelerating film flow of non-Newtonian power-law fluids (FFNF). These new developments provided in this book are (i) novel system of analysis models based on the developed New Similarity Analysis Method; (ii) a system of advanced methods for treatment of gas temperature- dependent physical properties, and liquid temperature- dependent physical properties; (iii) the organically combined models of the governing mathematical models with those on treatment model of variable physical properties; (iv) rigorous approach of overcoming a challenge on accurate solution of three-point boundary value problem related to two-phase film boiling and condensation; and (v) A pseudo-similarity method of dealing with thermal boundary layer of FFNF for greatly simplifies the heat-transfer analysis and numerical calculati...
Modeling of heat transfer within porous multi-constituent materials
International Nuclear Information System (INIS)
Niezgoda, M.
2012-01-01
The CEA works a great deal with porous materials - carbon composites, ceramics - and aims to optimize their properties for specific uses. These materials can be composed of several constituents and generally has a complex structure with pore size of several tens of micrometers. It is used in large-scale systems that are bigger than its own characteristic scale in which they are considered as equivalent to a homogeneous medium for the simulation of its behavior in its using environment without taking into account its local morphology. We are especially interested in the effective thermal diffusivity of heterogeneous materials that we estimate as a function of temperature with the help of an inverse method by considering they are homogeneous. The identification of the diffusivity of porous and/or semi-transparent materials is made difficult because of the strong conducto-radiative coupling can quickly occur when the temperature increases. We have thus modeled the coupled conductive and radiative heat transfer as a function of the temperature within porous multi-constituent materials from their morphology discretized into a set of homogeneous voxels. We have developed a methodology that consists in starting from a 3D-microstructure of the studied materials obtained by tomography. The microstructures constitute the numerical support to this modeling that renders it possible, on the one hand, to simulate any kind of numerical thermal experiments, especially the flash method whose the results render it possible to estimate the thermal diffusivity, and on the other hand, to reproduce the thermal behavior of our materials in their using conditions. (author) [fr
Monovalent cations transfer through isolated human amnion: a new pharmacological model
Energy Technology Data Exchange (ETDEWEB)
Bara, M.; Guiet-Bara, A.; Durlach, J.
1985-04-01
Transfer of monovalent cations through the isolated human amnion consists of different factors: paracellular, coupling, ATPase dependent cellular transfer, leak cellular transfer. Understanding this transfer permits testing of the action of various substances. Physiological substances (Mg, taurine) increase ionic transfer and there is a vicarious effect between Mg and taurine. The tocolytic agents MgSO/sub 4/ and ethanol do not exhibit a good effect on the transfer: decrease with ethanol; equality between entry and exit fluxes with MgSO/sub 4/. On the other hand, amphotericin B increases mother-to-fetus transfer. Polluting metals (Pb, Cd, Hg, As) dramatically reduce exchanges and almost completely inhibit amnion permeability. Ingestion of ethanol also exhibits a dramatic effect on the exchange between mother and fetus through the amnion. Study of ionic transfer in vitro can be considered a pharmacological model to investigate the modifications of mother-fetus exchanges by various substances.
A Conceptual Model of Technology Transfer for Public Universities in Mexico
Directory of Open Access Journals (Sweden)
Hugo Necoechea
2013-12-01
Full Text Available Technology transfer from academic and scientific institutions has been transformed into a strategic variable for companies and nations who wish to cope with the challenges of a global economy. Since the early 1970s, many technology transfer models have tried to introduce key factors in the process. Previous studies have shown that technology transfer is influenced by various elements. This study is based on a review of two recent technology transfer models that we have used as basic concepts for developing our own conceptual model. Researcher–firm networks have been considered as key elements in the technology transfer process between public universities and firms. The conceptual model proposed could be useful to improve the efficiency of existing technology transfer mechanisms.
SCDAP/RELAP5 Modeling of Heat Transfer and Flow Losses in Lower Head Porous Debris
International Nuclear Information System (INIS)
Coryell, E.W.; Siefken, L.J.; Paik, S.
1998-01-01
Designs are described for implementing models for calculating the heat transfer and flow losses in porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and non-porous debris that results from core material slumping into the lower head. Currently, the COUPLE model has the capability to model convective and radiative heat transfer from the surfaces of non-porous debris in a detailed manner and to model only in a simplistic manner the heat transfer from porous debris. In order to advance beyond the simplistic modeling for porous debris, designs are developed for detailed calculations of heat transfer and flow losses in porous debris. Correlations are identified for convective heat transfer in porous debris for the following modes of heat transfer; (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, and (5) film boiling. Interphase heat transfer is modeled in an approximate manner. A design is also described for implementing a model of heat transfer by radiation from debris to the interstitial fluid. A design is described for implementation of models for flow losses and interphase drag in porous debris. Since the models for heat transfer and flow losses in porous debris in the lower head are designed for general application, a design is also described for implementation of these models to the analysis of porous debris in the core region. A test matrix is proposed for assessing the capability of the implemented models to calculate the heat transfer and flow losses in porous debris. The implementation of the models described in this report is expected to improve the COUPLE code calculation of the temperature distribution in porous debris and in the lower head that supports the debris. The implementation of these models is also expected to improve the calculation of the temperature and flow distribution in porous debris in the core region
Heterogeneous studies in pulping of wood: Modelling mass transfer of alkali
Simão, João P. F.; Egas, Ana P. V.; Carvalho, M. Graça; Baptista, Cristina M. S. G.; Castro, José Almiro A. M.
2008-01-01
In this paper a heterogeneous lumped parameter model is proposed to describe the mass transfer of effective alkali during the kraft pulping of wood. This model, based on the spatial mean of the concentration profile of effective alkali along the chip thickness, enables the estimation of the effective diffusion coefficient that characterizes the internal resistance to mass transfer and the contribution of the external resistance to mass transfer which has often been neglected. http://www.sc...
Energy Technology Data Exchange (ETDEWEB)
Bouvier, A. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches; Trenty, L.; Guillot, J.B. [Ecole Centrale de Paris, Laboratoire EM2C. CNRS, 92 - Chatenay-Malabry (France); Delalondre, C. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches
1997-12-31
This paper presents the modeling of a transferred electric arc inside a bath of melted metal. After a recall of the context of the study, the problem of the modeling, which involves magnetohydrodynamic coupling inside the arc and the bath, is described. The equations that govern the phenomena inside the arc and the bath are recalled and the approach used for the modeling of the anode region of the arc is explained using a 1-D sub-model. The conditions of connection between arc and bath calculations are explained and calculation results obtained with a 200 kW laboratory furnace geometry are presented. (J.S.) 8 refs.
Transfer prices assignment with integrated production and marketing optimization models
Enrique Parra
2018-01-01
Purpose: In decentralized organizations (today a great majority of the large multinational groups), much of the decision-making power is in its individual business units-BUs-. In these cases, the management control system (MCS) uses transfer prices to coordinate actions of the BUs and to evaluate their performance with the goal of guaranteeing the whole corporation optimum. The purpose of the investigation is to design transfer prices that suit this goal. Design/methodology/approach: Cons...
A Mathematical Model of Heat Transfer in Spheroplastic
Directory of Open Access Journals (Sweden)
V. S. Zarubin
2016-01-01
Full Text Available Spheroplastics are composite materials composed of a polymer or organosilicate binder and hollow spherical inclusions (mostly, of glass, but there are also of carbon, phenol, and epoxy, which are called microspheres and have a diameter within a millimeter with the wall thickness of several micrometers. To reduce the material density in watercraft constructions sometimes are used so called macrospheres of up to 40 mm in diameter and shell thickness of 0,5--1,5 mm from spheroplastic with microspheres.Microspheres may contain inert gases such as nitrogen. Many countries have commercialised quartz microspheres. The USA, in particular, produces Q-Gel microspheres with density of 300 kg / m3, the bulk density - 100 kg / m3 and the average diameter of 75 microns,characterized by a high mechanical strength and low cost. Carbon microspheres having low mechanical properties can absorb radio waves in certain frequency ranges. Spheroplastic with silicone microspheres combine relatively high mechanical and dielectric properties.In virtue of low thermal conductivity spheroplastics are used in various heat-insulating structures. As the thermal insulation coatings, the spheroplastic covers the outer surface of the pipes, in particular oil and gas pipelines in the permafrost zones, regions of swampy ground, and underwater. The effective heat conductivity factor, primarily, determines the specific application of spheroplastic as a thermal insulation material. To quantify the value of this factor is necessary to have a mathematical model describing heat ransfer in spheroplastic.The paper presents a four-phase mathematical model of the heat transfer in a representative element of a spheroplastic structure placed in an unlimited array of homogeneous material, the thermal conductivity of which is to be determined as desired characteristics of spheroplastic. This model in combination with a dual variational formulation of stationary heat conduction problem in the
A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers
de Jong, Anne; Wijnant, Ysbrand H.; de Boer, Andries
2014-01-01
A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic
Carmeliet, J.; Descamps, F.; Houvenaghel, G.
1999-01-01
A multiscale network model is presented to model unsaturated moisture transfer in hygroscopic capillary-porous materials showing a broad pore-size distribution. Both capillary effects and water sorption phenomena, water vapour and liquid water transfer are considered. The multiscale approach is
International Nuclear Information System (INIS)
Corradini, M.; Sonin, A.A.; Todreas, N.
1976-12-01
In 1971-72, the Stanford Research Institute conducted a series of scaled experiments which simulated a sodium-vapor expansion in a hypothetical core disruptive accident (HCDA) for the Fast Flux Test Facility. A non-condensible explosive source was used to model the pressure-volume expansion characteristics of sodium vapor as predicted by computer code calculations. Rigid piston-cylinder experiments ( 1 / 10 and 1 / 30 scale) were undertaken to determine these expansion characteristics. The results showed that the pressure-volume characteristics depend significantly on the presence of water in the cylinder reducing the work output by about 50 percent when a sufficient water depth was present. The study presented proposes that the mechanism of heat transfer between the water and high temperature gas was due to area enhancement by Taylor instabilities at the gas-liquid interface. A simple heat transfer model is proposed which describes this energy transport process and agrees well with the experimental data from both scaled experiments. The consequences of this analysis suggest that an estimate of the heat transfer to the cold slug during a full-scale HCDA due to sodium vapor expansion and the accompanying reduction in mechanical work energy warrants further investigation. The implication of this analysis is that for either sodium or fuel vapor expansion in an HCDA, there is an inherent heat transfer mechanism which significantly reduces the work output of the expanding bubble
Modeling of heat transfer into a heat pipe for a localized heat input zone
International Nuclear Information System (INIS)
Rosenfeld, J.H.
1987-01-01
A general model is presented for heat transfer into a heat pipe using a localized heat input. Conduction in the wall of the heat pipe and boiling in the interior structure are treated simultaneously. The model is derived from circumferential heat transfer in a cylindrical heat pipe evaporator and for radial heat transfer in a circular disk with boiling from the interior surface. A comparison is made with data for a localized heat input zone. Agreement between the theory and the model is good. This model can be used for design purposes if a boiling correlation is available. The model can be extended to provide improved predictions of heat pipe performance
Modelling of Multi Input Transfer Function for Rainfall Forecasting in Batu City
Priska Arindya Purnama
2017-01-01
The aim of this research is to model and forecast the rainfall in Batu City using multi input transfer function model based on air temperature, humidity, wind speed and cloud. Transfer function model is a multivariate time series model which consists of an output series (Yt) sequence expected to be effected by an input series (Xt) and other inputs in a group called a noise series (Nt). Multi input transfer function model obtained is (b1,s1,r1) (b2,s2,r2) (b3,s3,r3) (b4,s4,r4)(pn,qn) = (0,0,0)...
Development of a UF{sub 6} cylinder transient heat transfer/stress analysis model
Energy Technology Data Exchange (ETDEWEB)
Williams, W.R. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)
1991-12-31
A heat transfer/stress analysis model is being developed to simulate the heating to a point of rupture of a cylinder containing UF{sub 6} when it is exposed to a fire. The assumptions underlying the heat transfer portion of the model, which has been the focus of work to date, will be discussed. A key aspect of this model is a lumped parameter approach to modeling heat transfer. Preliminary results and future efforts to develop an integrated thermal/stress model will be outlined.
International Nuclear Information System (INIS)
Bai, Peng; Fan, Kaigong; Guo, Xianghai; Zhang, Haocui
2016-01-01
Highlights: • We propose a non-equilibrium mass transfer absorption model instead of a distillation equilibrium model to calculate boron isotopes separation. • We apply the model to calculate the needed column height to meet prescribed separation requirements. - Abstract: To interpret the phenomenon of chemical exchange in boron isotopes separation accurately, the process is specified as an absorption–reaction–desorption hybrid process instead of a distillation equilibrium model, the non-equilibrium mass transfer absorption model is put forward and a mass transfer enhancement factor E is introduced to find the packing height needed to meet the specified separation requirements with MATLAB.
Post-dryout heat transfer analysis model with droplet Lagrangian simulation
International Nuclear Information System (INIS)
Keizo Matsuura; Isao Kataoka; Kaichiro Mishima
2005-01-01
Post-dryout heat transfer analysis was carried out considering droplet behavior by using the Lagrangian simulation method. Post-dryout heat transfer is an important heat transfer mechanism in many industrial appliances. Especially in recent Japanese BWR licensing, the standard for assessing the integrity of fuel that has experienced boiling transition is being examined. Although post-dryout heat transfer analysis is important when predicting wall temperature, it is difficult to accurately predict the heat transfer coefficient in the post-dryout regime because of the many heat transfer paths and non-equilibrium status between droplet and vapor. Recently, an analysis model that deals with many heat transfer paths including droplet direct contact heat transfer was developed and its results showed good agreement with experimental results. The model also showed that heat transfer by droplet could not be neglected in the low mass flux condition. However, the model deals with droplet deposition behavior by experimental droplet deposition correlation, so it cannot estimate the effect of droplet flow on turbulent flow field and heat transfer. Therefore, in this study we deal with many droplets separately by using the Lagrangian simulation method and hence estimate the effect of droplet flow on the turbulent flow field. We analyzed post-dryout experimental results and found that they correlated well with the analysis results. (authors)
SCDAP/RELAP5 Modeling of Heat Transfer and Flow Losses in Lower Head Porous Debris
International Nuclear Information System (INIS)
Siefken, Larry James; Coryell, Eric Wesley; Paik, Seungho; Kuo, Han Hsiung
1999-01-01
Designs are described for implementing models for calculating the heat transfer and flow losses in porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and nonporous debris that results from core material slumping into the lower head. Currently, the COUPLE model has the capability to model convective and radiative heat transfer from the surfaces of nonporous debris in a detailed manner and to model only in a simplistic manner the heat transfer from porous debris. In order to advance beyond the simplistic modeling for porous debris, designs are developed for detailed calculations of heat transfer and flow losses in porous debris. Correlations are identified for convective heat transfer in porous debris for the following modes of heat transfer; (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, and (5) film boiling. Interphase heat transfer is modeled in an approximate manner. Designs are described for models to calculate the flow losses and interphase drag of fluid flowing through the interstices of the porous debris, and to apply these variables in the momentum equations in the RELAP5 part of the code. Since the models for heat transfer and flow losses in porous debris in the lower head are designed for general application, a design is also described for implementation of these models to the analysis of porous debris in the core region. A test matrix is proposed for assessing the capability of the implemented models to calculate the heat transfer and flow losses in porous debris. The implementation of the models described in this report is expected to improve the COUPLE code calculation of the temperature distribution in porous debris and in the lower head that supports the debris. The implementation of these models is also expected to improve the calculation of the temperature and flow distribution in porous debris in the core region
A CONCEPTUAL MODEL OF ASSESSMENT OF KNOWLEDGE TRANSFER TO CONSUMER
Directory of Open Access Journals (Sweden)
Jurgita Raudeliūnienė
2017-12-01
Full Text Available Due to changing needs of knowledge consumers in the context of globalization organizations find it important to search out the way of effective application of the process of knowledge sharing and distribution in their activity in order to create and/or select proper means of communication with consumers on purpose of effective satisfaction of their knowledge needs. In order to address the problems of such nature it is important to assess the process of knowledge transfer and consumer purchase, knowledge needs, knowledge transferred to meet of consumer needs, channels and means of knowledge transfer. Also, to select purposefully channels of communication with consumers and tools of e-marketing that are suitable for satisfaction of consumer needs, i.e. channels and tools that affect self-determination of consumer to take a decision to acquire a product or service of specific organization.
Data-Driven Model Reduction and Transfer Operator Approximation
Klus, Stefan; Nüske, Feliks; Koltai, Péter; Wu, Hao; Kevrekidis, Ioannis; Schütte, Christof; Noé, Frank
2018-06-01
In this review paper, we will present different data-driven dimension reduction techniques for dynamical systems that are based on transfer operator theory as well as methods to approximate transfer operators and their eigenvalues, eigenfunctions, and eigenmodes. The goal is to point out similarities and differences between methods developed independently by the dynamical systems, fluid dynamics, and molecular dynamics communities such as time-lagged independent component analysis, dynamic mode decomposition, and their respective generalizations. As a result, extensions and best practices developed for one particular method can be carried over to other related methods.
A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.
de Jong, J A; Wijnant, Y H; de Boer, A
2014-03-01
A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.
Evaluation of heat transfer correlations for HCCI engine modeling
Soyhan, H.S.; Yasar, H.; Walmsley, H.; Head, B.; Kalghatgi, G.T.; Sorusbay, C.
2009-01-01
Combustion in HCCI engines is a controlled auto-ignition of well-mixed fuel, air and residual gas. The thermal conditions of the combustion chamber are governed by chemical kinetics strongly coupled with heat transfer from the hot gas to the walls. The heat losses have a critical effect on HCCI
Discrete vessel heat transfer in perfused tissue - model comparison
Stanczyk, M.; Leeuwen, van G.M.J.; Steenhoven, van A.A.
2007-01-01
The aim of this paper is to compare two methods of calculating heat transfer in perfused biological tissue using a discrete vessel description. The methods differ in two important aspects: the representation of the vascular system and the algorithm for calculating the heat flux between tissue and
International Nuclear Information System (INIS)
Seiler, J.M.; Bonnet, J.M.; Bernaz, L.
2001-01-01
Extensive studies have been performed to investigate the heat transfer within a molten corium pool (homogeneous, stratified and with miscibility gap): Synthesis of heat transfer correlations in molten pool (homogeneous and stratified), Focusing effect in stratified metal layer, DNS analysis of Rayleigh Benard instabilities at the top boundary; interpretation of the different convection regimes and exponents affecting the Rayleigh number in the heat transfer correlations, Molten pool model for corium presenting a miscibility gap. Condition for de-stratification. (authors)
Modeling Transfer of Knowledge in an Online Platform of a Cluster
Schmidt, Danilo Marcello; Böttcher, Lena; Wilberg, Julian; Kammerl, Daniel; Lindemann, Udo
2016-01-01
Dealing with knowledge as a relevant resource and factor for production has become increasingly important in the course of globalization. This work focuses on questions about transferring knowledge when many companies work together in a cluster of enterprises. We developed a model of this transfer based on the theory of clusters from the New Institutional Economics’ point of view and based on existing theories about knowledge and knowledge transfer. This theoretical construct is evaluated and...
Energy Technology Data Exchange (ETDEWEB)
Seiler, J.M.; Bonnet, J.M.; Bernaz, L. [CEA Grenoble (France)
2001-07-01
Extensive studies have been performed to investigate the heat transfer within a molten corium pool (homogeneous, stratified and with miscibility gap): Synthesis of heat transfer correlations in molten pool (homogeneous and stratified), Focusing effect in stratified metal layer, DNS analysis of Rayleigh Benard instabilities at the top boundary; interpretation of the different convection regimes and exponents affecting the Rayleigh number in the heat transfer correlations, Molten pool model for corium presenting a miscibility gap. Condition for de-stratification. (authors)
Validation of the TASS/SMR-S Code for the PRHRS Condensation Heat Transfer Model
International Nuclear Information System (INIS)
Jun, In Sub; Yang, Soo Hyoung; Chung, Young Jong; Lee, Won Jae
2011-01-01
When some accidents or events are occurred in the SMART, the secondary system is used to remove the core decay heat for the long time such as a feedwater system. But if the feedwater system can't remove the residual core heat because of its malfunction, the core decay heat is removed using the Passive Residual Heat Removal System (PRHRS). The PRHRS is passive type safety system adopted to enhance the safety of the SMART. It can fundamentally eliminate the uncertainty of operator action. TASS/SMR-S (Transient And Setpoint Simulation/ System-integrated Modular Reactor-Safety) code has various heat transfer models reflecting the design features of the SMART. One of the heat transfer models is the PRHRS condensation heat transfer model. The role of this model is to calculate the heat transfer coefficient in the heat exchanger (H/X) tube side using the relevant heat transfer correlations for all of the heat transfer modes. In this paper, the validation of the condensation heat transfer model was carried out using the POSTECH H/X heat transfer test
Discussion on the Heat and Mass Transfer Model on the Pool Surface
International Nuclear Information System (INIS)
Hong, Soon-Joon; Choo, Yeon-Jun; Ha, Sang-Jun
2016-01-01
Heat transfer on the pool surface involves the evaporation and condensation of steam in the presence of non-condensable gas. It is a kind of inter-phase heat transfer. This phenomenon has been regarded as less important on the thermal hydraulic behaviors such as pressure, temperature, hydrogen distribution, and so on in the nuclear reactor containment building. As a matter of fact, several RAIs (requests for additional information) during the licensing review of the developed CAP have been presented. And early in 2000s the steam condensation on the water surface of IRWST was a concern of APR1400 design. Such an increased concern is believed because it is a newly adopted system. This study discusses the pool surface heat transfer by reviewing the models of several well-known containment analysis codes, and conducting the sensitivities. This study discussed the pool surface heat transfer. The related models of CAP, GOTHIC, CONTEMPT-LT, and CONTEMPT4 were compared. The sensitivity of heat transfer coefficient for SKN3 and 4 using conventional code CONTEMPT-LT/028-A showed little effect. And the sensitivity of relative humidity and heat transfer area for latent heat transfer shows that CAP locates between GOTHIC and CONTEMPT4/MOD. The sensitivity for sensible heat transfer also shows similar trend. Conclusively, current CAP model of pool surface heat transfer has no fatal defect
Discussion on the Heat and Mass Transfer Model on the Pool Surface
Energy Technology Data Exchange (ETDEWEB)
Hong, Soon-Joon; Choo, Yeon-Jun [FNC Tech., Yongin (Korea, Republic of); Ha, Sang-Jun [KHNP Central Research Institute, Daejeon (Korea, Republic of)
2016-10-15
Heat transfer on the pool surface involves the evaporation and condensation of steam in the presence of non-condensable gas. It is a kind of inter-phase heat transfer. This phenomenon has been regarded as less important on the thermal hydraulic behaviors such as pressure, temperature, hydrogen distribution, and so on in the nuclear reactor containment building. As a matter of fact, several RAIs (requests for additional information) during the licensing review of the developed CAP have been presented. And early in 2000s the steam condensation on the water surface of IRWST was a concern of APR1400 design. Such an increased concern is believed because it is a newly adopted system. This study discusses the pool surface heat transfer by reviewing the models of several well-known containment analysis codes, and conducting the sensitivities. This study discussed the pool surface heat transfer. The related models of CAP, GOTHIC, CONTEMPT-LT, and CONTEMPT4 were compared. The sensitivity of heat transfer coefficient for SKN3 and 4 using conventional code CONTEMPT-LT/028-A showed little effect. And the sensitivity of relative humidity and heat transfer area for latent heat transfer shows that CAP locates between GOTHIC and CONTEMPT4/MOD. The sensitivity for sensible heat transfer also shows similar trend. Conclusively, current CAP model of pool surface heat transfer has no fatal defect.
Directory of Open Access Journals (Sweden)
G. Hartmann
2005-01-01
Full Text Available In order to find a model parameterization such that the hydrological model performs well even under different conditions, appropriate model performance measures have to be determined. A common performance measure is the Nash Sutcliffe efficiency. Usually it is calculated comparing observed and modelled daily values. In this paper a modified version is suggested in order to calibrate a model on different time scales simultaneously (days up to years. A spatially distributed hydrological model based on HBV concept was used. The modelling was applied on the Upper Neckar catchment, a mesoscale river in south western Germany with a basin size of about 4000 km2. The observation period 1961-1990 was divided into four different climatic periods, referred to as "warm", "cold", "wet" and "dry". These sub periods were used to assess the transferability of the model calibration and of the measure of performance. In a first step, the hydrological model was calibrated on a certain period and afterwards applied on the same period. Then, a validation was performed on the climatologically opposite period than the calibration, e.g. the model calibrated on the cold period was applied on the warm period. Optimal parameter sets were identified by an automatic calibration procedure based on Simulated Annealing. The results show, that calibrating a hydrological model that is supposed to handle short as well as long term signals becomes an important task. Especially the objective function has to be chosen very carefully.
Kinetic Monte Carlo modeling of chemical reactions coupled with heat transfer.
Castonguay, Thomas C; Wang, Feng
2008-03-28
In this paper, we describe two types of effective events for describing heat transfer in a kinetic Monte Carlo (KMC) simulation that may involve stochastic chemical reactions. Simulations employing these events are referred to as KMC-TBT and KMC-PHE. In KMC-TBT, heat transfer is modeled as the stochastic transfer of "thermal bits" between adjacent grid points. In KMC-PHE, heat transfer is modeled by integrating the Poisson heat equation for a short time. Either approach is capable of capturing the time dependent system behavior exactly. Both KMC-PHE and KMC-TBT are validated by simulating pure heat transfer in a rod and a square and modeling a heated desorption problem where exact numerical results are available. KMC-PHE is much faster than KMC-TBT and is used to study the endothermic desorption of a lattice gas. Interesting findings from this study are reported.
The transfer function model for dynamic response of wet cooling coils
International Nuclear Information System (INIS)
Yao Ye; Liu Shiqing
2008-01-01
This paper mainly concerned about the dynamic response model of wet cooling coils that is developed by the Laplace transform method. The theoretic equations are firstly established based on the theory of energy conservation. Then, the transfer functions on the transient responses of wet cooling coils have been deduced using the method of Laplace transform. The transfer functions reveal the dynamic relationships between the inlet variables and the outlet ones of the cooling coils. Partial-fraction method and Newton-Raphson method are both used in the inversion of the transfer functions from the s-domain to τ-domain. To make the dynamic model of wet cooling coils more adaptive, RBFNN method is employed to determine the coefficients of heat and mass transfer. Experiments have been done and manifested that the coefficients of heat and mass transfer by RBFNN will be of great value to the validity of the transient response model of wet cooling coils in this study
Model of two-temperature convective transfer in porous media
Gruais, Isabelle; Poliševski, Dan
2017-12-01
In this paper, we study the asymptotic behaviour of the solution of a convective heat transfer boundary problem in an ɛ -periodic domain which consists of two interwoven phases, solid and fluid, separated by an interface. The fluid flow and its dependence with respect to the temperature are governed by the Boussinesq approximation of the Stokes equations. The tensors of thermal diffusion of both phases are ɛ -periodic, as well as the heat transfer coefficient which is used to describe the first-order jump condition on the interface. We find by homogenization that the two-scale limits of the solutions verify the most common system used to describe local thermal non-equilibrium phenomena in porous media (see Nield and Bejan in Convection in porous media, Springer, New York, 1999; Rees and Pop in Transport phenomena in porous media III, Elsevier, Oxford, 2005). Since now, this system was justified only by volume averaging arguments.
Turbulence modeling and surface heat transfer in a stagnation flow region
Wang, C. R.; Yeh, F. C.
1987-01-01
Analysis for the turbulent flow field and the effect of freestream turbulence on the surface heat transfer rate of a stagnation flow is presented. The emphasis is on modeling and its augmentation of surface heat transfer rate. The flow field considered is the region near the forward stagnation point of a circular cylinder in a uniform turbulent mean flow.
John F. Hunt; Hongmei Gu
2006-01-01
The anisotropy of wood complicates solution of heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential direction and do not differentiate the effects of cellular alignment, earlywood/latewood differences, or...
CSIR Research Space (South Africa)
Herselman, ME
2010-11-01
Full Text Available The purpose of this article is to indicate how skills can be transferred through the application of the Digital Doorway (DD) design research model. Skills transfer takes place between the initiators of Digital Doorway (CSIR Meraka Institute) project...
Deviations from mass transfer equilibrium and mathematical modeling of mixer-settler contactors
International Nuclear Information System (INIS)
Beyerlein, A.L.; Geldard, J.F.; Chung, H.F.; Bennett, J.E.
1980-01-01
This paper presents the mathematical basis for the computer model PUBG of mixer-settler contactors which accounts for deviations from mass transfer equilibrium. This is accomplished by formulating the mass balance equations for the mixers such that the mass transfer rate of nuclear materials between the aqueous and organic phases is accounted for. 19 refs
Marcelis, C.L.M.; Leeuwen, van M.; Polderman, H.G.; Janssen, A.J.H.; Lettinga, G.
2003-01-01
A mathematical model was developed in order to describe the mass transfer rate of dibenzothiophene within the oil droplet to the oil/water interface of droplets created in a stirred tank reactor. The mass transfer rate of dibenzothiophene was calculated for various complex hydrocarbon distillates
Blocking layer modeling for temperature analysis of electron transfer ...
African Journals Online (AJOL)
In this article, we simulate thermal effects on the electron transfer rate from three quantum dots CdSe, CdS and CdTe to three metal oxides TiO2, SnO2 and ZnO2 in the presence of four blocking layers ZnS, ZnO, TiO2 and Al2O3, in a porous quantum dot sensitized solar cell (QDSSC) structure, using Marcus theory.
Dynamic model for the transfer of CS-137 through the soil-grass-lamb foodchain
DEFF Research Database (Denmark)
Nielsen, S.P.
1994-01-01
A dynamic radioecological model for the transfer of radiocaesium through the soil-grass-lamb foodchain was constructed on the basis of field data collected in 1990–1993 from the Nordic countries: Denmark, Faroe Islands, Finland, Iceland, Norway and Sweden. The model assumes an initial soil...... contamination of one kilobecquerel of 137Cs per square metre and simulates the transfer to grass through root uptake in addition to direct contamination from resuspended activity. The model covers two different soil types: clay-loam and organic, with significantly different transfers of radiocaesium to grass...
Nere, Nandkishor K; Allen, Kimberley C; Marek, James C; Bordawekar, Shailendra V
2012-10-01
Drying an early stage active pharmaceutical ingredient candidate required excessively long cycle times in a pilot plant agitated filter dryer. The key to faster drying is to ensure sufficient heat transfer and minimize mass transfer limitations. Designing the right mixing protocol is of utmost importance to achieve efficient heat transfer. To this order, a composite model was developed for the removal of bound solvent that incorporates models for heat transfer and desolvation kinetics. The proposed heat transfer model differs from previously reported models in two respects: it accounts for the effects of a gas gap between the vessel wall and solids on the overall heat transfer coefficient, and headspace pressure on the mean free path length of the inert gas and thereby on the heat transfer between the vessel wall and the first layer of solids. A computational methodology was developed incorporating the effects of mixing and headspace pressure to simulate the drying profile using a modified model framework within the Dynochem software. A dryer operational protocol was designed based on the desolvation kinetics, thermal stability studies of wet and dry cake, and the understanding gained through model simulations, resulting in a multifold reduction in drying time. Copyright © 2012 Wiley-Liss, Inc.
A transfer function model of the BEPO reactor for control studies
Energy Technology Data Exchange (ETDEWEB)
Cummins, J D [Dynamics Group, Control and Instrumentation Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)
1962-09-15
A spatially independent (one point) transfer function model of the BEPO reactor is presented. Perturbations in control rod reactivity and coolant flow are considered and transfer functions deduced for variations about four steady states namely zero power, one sixth full power and one sixth full flow, one sixth full power and full flow and also full power and full flow. The transfer functions are presented in pole-zero form. The use of the transfer functions in verifying experimental frequency responses, in automatic control studies and in multi-variable non-interacting control design are briefly considered. (author)
Modelling current transfer to cathodes in metal halide plasmas
International Nuclear Information System (INIS)
Benilov, M S; Cunha, M D; Naidis, G V
2005-01-01
This work is concerned with investigation of the main features of current transfer to cathodes under conditions characteristic of metal halide (MH) lamps. It is found that the presence of MHs in the gas phase results in a small decrease of the cathode surface temperature and of the near-cathode voltage drop in the diffuse mode of current transfer; the range of stability of the diffuse mode expands. Effects caused by a variation of the work function of the cathode surface owing to formation of a monolayer of alkali metal atoms on the surface are studied for particular cases where the monolayer is composed of sodium or caesium. It is found that the formation of the sodium monolayer affects the diffuse mode of current transfer only moderately and in the same direction that the presence of metal atoms in the gas phase affects it. Formation of the caesium monolayer produces a dramatic effect: the cathode surface temperature decreases very strongly, the diffuse-mode current-voltage characteristic becomes N-S-shaped
A passive and active microwave-vector radiative transfer (PAM-VRT) model
International Nuclear Information System (INIS)
Yang, Jun; Min, Qilong
2015-01-01
A passive and active microwave vector radiative transfer (PAM-VRT) package has been developed. This fast and accurate forward microwave model, with flexible and versatile input and output components, self-consistently and realistically simulates measurements/radiation of passive and active microwave sensors. The core PAM-VRT, microwave radiative transfer model, consists of five modules: gas absorption (two line-by-line databases and four fast models); hydrometeor property of water droplets and ice (spherical and nonspherical) particles; surface emissivity (from Community Radiative Transfer Model (CRTM)); vector radiative transfer of successive order of scattering (VSOS); and passive and active microwave simulation. The PAM-VRT package has been validated against other existing models, demonstrating good accuracy. The PAM-VRT not only can be used to simulate or assimilate measurements of existing microwave sensors, but also can be used to simulate observation results at some new microwave sensors. - Highlights: • A novel microwave vector radiative transfer model is developed. • It can simulate passive and active microwave radiative transfer simultaneously. • It can be applied to simulate measurements for different types of viewing geometry. • The accuracy of this model has been validated against other existing models
Modeling of Heat Transfer in Rooms in the Modelica "Buildings" Library
Energy Technology Data Exchange (ETDEWEB)
Wetter, Michael [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zuo, Wangda [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nouidui, Thierry Stephane [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2011-11-01
This paper describes the implementation of the room heat transfer model in the free open-source Modelica \\Buildings" library. The model can be used as a single room or to compose a multizone building model. We discuss how the model is decomposed into submodels for the individual heat transfer phenomena. We also discuss the main physical assumptions. The room model can be parameterized to use different modeling assumptions, leading to linear or non-linear differential algebraic systems of equations. We present numerical experiments that show how these assumptions affect computing time and accuracy for selected cases of the ANSI/ASHRAE Standard 140- 2007 envelop validation tests.
Separate effects tests for GOTHIC condensation and evaporative heat transfer models
International Nuclear Information System (INIS)
George, T.L.; Singh, A.
1994-01-01
The GOTHIC computer program, under development at EPRI/NAI, is a general purpose thermal hydraulics computer program for design, licensing, safety and operating analysis of nuclear containments and other confinement buildings. The code solves a nine equation model for three dimensional multiphase flow with separate mass, momentum and energy equations for vapor, liquid and drop phases. The vapor phase can be a gas mixture of steam and non-condensing gases. The phase balance equations are coupled by mechanistic and empirical models for interface mass, energy and momentum transfer that cover the entire flow regime from bubbly flow to film/drop flow. A variety of heat transfer correlations are available to model the fluid coupling to active and passive solid conductors. This paper focuses on the application of GOTHIC to two separate effects tests; condensation heat transfer on a vertical flat plate with varying bulk velocity, steam concentration and temperature, and evaporative heat transfer from a hot pool to a dry (superheated) atmosphere. Comparisons with experimental data is included for both tests. Results show the validity of two condensation heat transfer correlations as incorporated into GOTHIC and the interfacial heat and mass transfer models for the range of the experimental test conditions. Comparisons are also made for lumped versus multidimensional modeling for buoyancy controlled flow with evaporative heat transfer. (author). 13 refs., 1 tab., 10 figs
Separate effects tests for GOTHIC condensation and evaporative heat transfer models
International Nuclear Information System (INIS)
George, T.L.; Singh, A.
1996-01-01
The GOTHIC computer program, under development at NAI for EPRI, is a general purpose thermal hydraulics computer program for design, licensing, safety and operating analysis of nuclear containments and other confinement buildings. The code solves a nine-equation model for three-dimensional multiphase flow with separate mass, momentum and energy equations for vapor, liquid and drop phases. The vapor phase can be a gas mixture of steam and non-condensing gases. The phase balance equations are coupled by mechanistic and empirical models for interface mass, energy and momentum transfer that cover the entire flow regime from bubbly flow to film-drop flow. A variety of heat transfer correlations are available to model the fluid coupling to active and passive solid conductors. This paper focuses on the application of GOTHIC to two separate effects tests: condensation heat transfer on a vertical flat plate with varying bulk velocity, steam concentration and temperature, and evaporative heat transfer from a hot pool to a dry (superheated) atmosphere. Comparisons with experimental data are included for both tests. Results show the validity of two condensation heat transfer correlations as incorporated into GOTHIC and the interfacial heat and mass transfer models for the range of the experimental test conditions. Comparisons are also made for lumped vs. multidimensional modeling for buoyancy-controlled flow with evaporative heat transfer. (orig.)
A model for dispersed flow heat transfer in rod bundles during reflood
International Nuclear Information System (INIS)
Wong, S.
1980-01-01
The present model calculates the heat transfer characteristics of the non-equilibrium dispersed droplet flow regime above the quench front during reflood by solving simultaneously the wall-to-vapor interactions, wall-to-droplet interactions and vapor-to-droplet interactions by an iterative numerical method. The unique feature in the present study is various heat transfer mechanisms are combined in an overall energy balance equation, and the convective heat transfer to vapor is obtained by calculating the vapor temperature distributions at the heated walls. The reactor rod bundle geometry, axial variations of vapor temperature and flow properties, radiative heat transfers, and enhancement of heat transfer due to turbulence are considered carefully, so that the present model could be used to predict PWR (Pressurized Water Reactor) reflood heat transfers, and hence the fuel cladding wall temperature transients. In order to achieve closure of the problem formulations, the droplet size and its motion are determined from the FLECHT (Full Length Emergency Cooling Heat Transfer Program) low flooding rate series consine axial power shape test data. The model is then verified by comparing the heat transfer predictions with FLECHT low flooding rate series skewed axial power shape test data. Comparisons of predictions with data show satisfactory agreements
Xu, Fei; Zhang, Yaning; Jin, Guangri; Li, Bingxi; Kim, Yong-Song; Xie, Gongnan; Fu, Zhongbin
2018-04-01
A three-phase model capable of predicting the heat transfer and moisture migration for soil freezing process was developed based on the Shen-Chen model and the mechanisms of heat and mass transfer in unsaturated soil freezing. The pre-melted film was taken into consideration, and the relationship between film thickness and soil temperature was used to calculate the liquid water fraction in both frozen zone and freezing fringe. The force that causes the moisture migration was calculated by the sum of several interactive forces and the suction in the pre-melted film was regarded as an interactive force between ice and water. Two kinds of resistance were regarded as a kind of body force related to the water films between the ice grains and soil grains, and a block force instead of gravity was introduced to keep balance with gravity before soil freezing. Lattice Boltzmann method was used in the simulation, and the input variables for the simulation included the size of computational domain, obstacle fraction, liquid water fraction, air fraction and soil porosity. The model is capable of predicting the water content distribution along soil depth and variations in water content and temperature during soil freezing process.
DEFF Research Database (Denmark)
Souza da Conceição, Carolina; Broberg, Ole; Paravizo, Esdras
2017-01-01
of knowledge registered in the systems without standards to categorise and store this knowledge, to being difficult to access and retrieve the knowledge in the systems. Discussion: Transferring knowledge and experiences from users brings human factors into play and modelling the knowledge transfer process...... and workwise distance between operations and engineering design teams, integrating human factors and transferring knowledge are key aspects when designing for better performance systems. Research Objective: Based on an in-depth empirical investigation in an offshore oil company, this study aims to provide......Summative Statement: Integrating human factors and users’ experiences in design projects is a well-known challenge. This study focus on the specific challenges for transferring these experiences and how using a knowledge transfer model can help this integration on the design of high-risk productive...
Measurements for modeling radionuclide transfer in the aquatic environment
International Nuclear Information System (INIS)
Kahn, B.
1976-01-01
Analytical methods for measuring radionuclides in the aquatic environment are discussed for samples of fresh water and seawater, fish and shellfish, biota such as algae, plankton, seaweed, and aquatic plants, and sediment. Consideration is given to radionuclide collection and concentration, sample preservation, radiochemical and instrumental analysis, and quality assurance. Major problems are the very low environmental levels of the radionuclides of interest, simultaneous occurrence of radionuclides in several chemical and physical forms and the numerous factors that affect radionuclide levels in and transfers among media. Some radionuclides of importance in liquid effluents from nuclear power stations are listed, and sources of radiochemical analytical methods are recommended
The improvement of the heat transfer model for sodium-water reaction jet code
International Nuclear Information System (INIS)
Hashiguchi, Yoshirou; Yamamoto, Hajime; Kamoshida, Norio; Murata, Shuuichi
2001-02-01
For confirming the reasonable DBL (Design Base Leak) on steam generator (SG), it is necessary to evaluate phenomena of sodium-water reaction (SWR) in an actual steam generator realistically. The improvement of a heat transfer model on sodium-water reaction (SWR) jet code (LEAP-JET ver.1.40) and application analysis to the water injection tests for confirmation of propriety for the code were performed. On the improvement of the code, the heat transfer model between a inside fluid and a tube wall was introduced instead of the prior model which was heat capacity model including both heat capacity of the tube wall and inside fluid. And it was considered that the fluid of inside the heat exchange tube was able to treat as water or sodium and typical heat transfer equations used in SG design were also introduced in the new heat transfer model. Further additional work was carried out in order to improve the stability of the calculation for long calculation time. The test calculation using the improved code (LEAP-JET ver.1.50) were carried out with conditions of the SWAT-IR·Run-HT-2 test. It was confirmed that the SWR jet behavior on the result and the influence to the result of the heat transfer model were reasonable. And also on the improved code (LEAP-JET ver.1.50), user's manual was revised with additional I/O manual and explanation of the heat transfer model and new variable name. (author)
International Nuclear Information System (INIS)
Guo, Jinxin; Gleeson, Michael R; Liu, Shui; Sheridan, John T
2011-01-01
The non-local photopolymerization driven diffusion (NPDD) model predicts that a reduction in the non-local response length within a photopolymer material will improve its high spatial frequency response. The introduction of a chain transfer agent reduces the average molecular weight of polymer chains formed during free radical polymerization. Therefore a chain transfer agent (CTA) provides a practical method to reduce the non-local response length. An extended NPDD model is presented, which includes the chain transfer reaction and most major photochemical processes. The addition of a chain transfer agent into an acrylamide/polyvinyl alcohol photopolymer material is simulated and the predictions of the model are examined. The predictions of the model are experimentally examined in part II of this paper
New Integrals Arising in the Samara-Valencia Heat Transfer Model in Grinding
Directory of Open Access Journals (Sweden)
J. L. González-Santander
2017-01-01
Full Text Available The Samara-Valencia model for heat transfer in grinding has been recently used for calculating nontabulated integrals. Based on these results, new infinite integrals can be calculated, involving the Macdonald function and the modified Struve function.
DEFF Research Database (Denmark)
Janssen, Hans; Blocken, Bert; Carmeliet, Jan
2007-01-01
While the transfer equations for moisture and heat in building components are currently undergoing standardisation, atmospheric boundary conditions, conservative modelling and numerical efficiency are not addressed. In a first part, this paper adds a comprehensive description of those boundary...
Economical analyses of build-operate-transfer model in establishing alternative power plants
Energy Technology Data Exchange (ETDEWEB)
Yumurtaci, Zehra [Yildiz Technical University, Department of Mechanical Engineering, Y.T.U. Mak. Fak. Mak. Muh. Bolumu, Besiktas, 34349 Istanbul (Turkey)]. E-mail: zyumur@yildiz.edu.tr; Erdem, Hasan Hueseyin [Yildiz Technical University, Department of Mechanical Engineering, Y.T.U. Mak. Fak. Mak. Muh. Bolumu, Besiktas, 34349 Istanbul (Turkey)
2007-01-15
The most widely employed method to meet the increasing electricity demand is building new power plants. The most important issue in building new power plants is to find financial funds. Various models are employed, especially in developing countries, in order to overcome this problem and to find a financial source. One of these models is the build-operate-transfer (BOT) model. In this model, the investor raises all the funds for mandatory expenses and provides financing, builds the plant and, after a certain plant operation period, transfers the plant to the national power organization. In this model, the object is to decrease the burden of power plants on the state budget. The most important issue in the BOT model is the dependence of the unit electricity cost on the transfer period. In this study, the model giving the unit electricity cost depending on the transfer of the plants established according to the BOT model, has been discussed. Unit electricity investment cost and unit electricity cost in relation to transfer period for plant types have been determined. Furthermore, unit electricity cost change depending on load factor, which is one of the parameters affecting annual electricity production, has been determined, and the results have been analyzed. This method can be employed for comparing the production costs of different plants that are planned to be established according to the BOT model, or it can be employed to determine the appropriateness of the BOT model.
Economical analyses of build-operate-transfer model in establishing alternative power plants
International Nuclear Information System (INIS)
Yumurtaci, Zehra; Erdem, Hasan Hueseyin
2007-01-01
The most widely employed method to meet the increasing electricity demand is building new power plants. The most important issue in building new power plants is to find financial funds. Various models are employed, especially in developing countries, in order to overcome this problem and to find a financial source. One of these models is the build-operate-transfer (BOT) model. In this model, the investor raises all the funds for mandatory expenses and provides financing, builds the plant and, after a certain plant operation period, transfers the plant to the national power organization. In this model, the object is to decrease the burden of power plants on the state budget. The most important issue in the BOT model is the dependence of the unit electricity cost on the transfer period. In this study, the model giving the unit electricity cost depending on the transfer of the plants established according to the BOT model, has been discussed. Unit electricity investment cost and unit electricity cost in relation to transfer period for plant types have been determined. Furthermore, unit electricity cost change depending on load factor, which is one of the parameters affecting annual electricity production, has been determined, and the results have been analyzed. This method can be employed for comparing the production costs of different plants that are planned to be established according to the BOT model, or it can be employed to determine the appropriateness of the BOT model
Numerical Modeling of Transient Heat Transfer in Longitudinal Fin
Directory of Open Access Journals (Sweden)
Farshad Panahizadeh
2017-11-01
Full Text Available The main objective of the present numerical study is to investigate the transient heat transfer in one kind of all-purpose longitudinal fin with the triangular profile. The lateral surface of the concerned fin and the tip of it are subjected to general situations included heat flux at the base and insulation on the tip. For this study developed a one dimensional in house code written by Fortran 90 programming language by using finite difference method with an implicit scheme in unsteady state condition. Generally, the result of this study in time variation state after 700 seconds is steady. The results also show the fin efficiency by increasing the time of study decreases due to a reduction in the total heat transfer which is happened in the fin. The grid independence study shows that for the number of nodes greater than 20 the result will not be changed and same as before. Finally, the result of Fortran code verified by commercial CFD code which relies on finite difference method and it was shown have a consistent agreement
CFD evaluation of turbulence model on heat transfer in 5 × 5 rod bundles
International Nuclear Information System (INIS)
Chao Yanmeng; Yang Lixin; Zhang Yuxiang; Pang Zhengzheng
2014-01-01
Different turbulence models may lead to different results when analyzing fuel assemblies using computational fluid dynamics (CFD) method. In this paper, a 5 × 5 rod bundle model was built to analyze the relationship between flow and heat transfer. The pressure drop and Nu were calculated using ANSYS CFX. Three factors evaluating swirling flow and cross-flow were used to analyze the inner relationship between flow field and heat transfer. The performances of various turbulence models, including eddy viscosity model and Reynold stress model, were evaluated. The comparison between numerical and similar experimental results indicates that Reynold stress model is more appropriate for modeling flow features and heat transfer in spacer grids discussed in this paper. (authors)
Analytical expressions for two-nucleon transfer spectroscopic factors in sdg interacting boson model
International Nuclear Information System (INIS)
Devi, Y.D.; Kota, V.K.B.
1991-01-01
Analytical expressions for two-nucleon (l = 0,2 and 4) transfer spectroscopic factors are derived in the SU sdg (3) limit of the sdg interacting boson model. In addition, large N (boson number) limit expressions for the ratio of summed l = 0 transfer strength to excited 0 + states to that of ground state are derived in all the symmetry limits of the sdg model. Some comparisons with data are made. (author)
Analytical expressions for two-nucleon transfer spectroscopic factors in sdg interacting boson model
Energy Technology Data Exchange (ETDEWEB)
Devi, Y.D.; Kota, V.K.B. (Physical Research Lab., Ahmedabad (India))
1991-11-01
Analytical expressions for two-nucleon (l = 0,2 and 4) transfer spectroscopic factors are derived in the SU{sub sdg}(3) limit of the sdg interacting boson model. In addition, large N (boson number) limit expressions for the ratio of summed l = 0 transfer strength to excited 0{sup +} states to that of ground state are derived in all the symmetry limits of the sdg model. Some comparisons with data are made. (author).
van Soest, Johan; Meldolesi, Elisa; van Stiphout, Ruud; Gatta, Roberto; Damiani, Andrea; Valentini, Vincenzo; Lambin, Philippe; Dekker, Andre
2017-09-01
Multiple models have been developed to predict pathologic complete response (pCR) in locally advanced rectal cancer patients. Unfortunately, validation of these models normally omit the implications of cohort differences on prediction model performance. In this work, we will perform a prospective validation of three pCR models, including information whether this validation will target transferability or reproducibility (cohort differences) of the given models. We applied a novel methodology, the cohort differences model, to predict whether a patient belongs to the training or to the validation cohort. If the cohort differences model performs well, it would suggest a large difference in cohort characteristics meaning we would validate the transferability of the model rather than reproducibility. We tested our method in a prospective validation of three existing models for pCR prediction in 154 patients. Our results showed a large difference between training and validation cohort for one of the three tested models [Area under the Receiver Operating Curve (AUC) cohort differences model: 0.85], signaling the validation leans towards transferability. Two out of three models had a lower AUC for validation (0.66 and 0.58), one model showed a higher AUC in the validation cohort (0.70). We have successfully applied a new methodology in the validation of three prediction models, which allows us to indicate if a validation targeted transferability (large differences between training/validation cohort) or reproducibility (small cohort differences). © 2017 American Association of Physicists in Medicine.
Principles of the radiosity method versus radiative transfer for canopy reflectance modeling
Gerstl, Siegfried A. W.; Borel, Christoph C.
1992-01-01
The radiosity method is introduced to plant canopy reflectance modeling. We review the physics principles of the radiosity method which originates in thermal radiative transfer analyses when hot and cold surfaces are considered within a given enclosure. The radiosity equation, which is an energy balance equation for discrete surfaces, is described and contrasted with the radiative transfer equation, which is a volumetric energy balance equation. Comparing the strengths and weaknesses of the radiosity method and the radiative transfer method, we conclude that both methods are complementary to each other. Results of sample calculations are given for canopy models with up to 20,000 discrete leaves.
New flow boiling heat transfer model for hydrocarbons evaporating inside horizontal tubes
International Nuclear Information System (INIS)
Chen, G. F.; Gong, M. Q.; Wu, J. F.; Zou, X.; Wang, S.
2014-01-01
Hydrocarbons have high thermodynamic performances, belong to the group of natural refrigerants, and they are the main components in mixture Joule-Thomson low temperature refrigerators (MJTR). New evaluations of nucleate boiling contribution and nucleate boiling suppression factor in flow boiling heat transfer have been proposed for hydrocarbons. A forced convection heat transfer enhancement factor correlation incorporating liquid velocity has also been proposed. In addition, the comparisons of the new model and other classic models were made to evaluate its accuracy in heat transfer prediction
Oxygen Transfer Model for a Flow-Through Hollow-Fiber Membrane Biofilm Reactor
DEFF Research Database (Denmark)
Gilmore, K. R.; Little, J. C.; Smets, Barth F.
2009-01-01
overpredicted the oxygen transfer by a factor of 1.3 relative to the result calculated from the outlet gas oxygen concentration, which was considered the most accurate of the measured benchmarks. A mass transfer coefficient derived from the clean water testing with oxygen sensors at the membrane......-liquid interface was the most accurate of the predictive models (overpredicted by a factor of 1.1) while a coefficient determined by measuring bulk liquid dissolved oxygen underpredicted the oxygen transfer by a factor of 3. The mechanistic model was found to be an adequate tool for design because it used...
A research program on radiative transfer model development in support of the ARM program
International Nuclear Information System (INIS)
Clough, S.A.
1993-01-01
The objective of this research effort is to develop radiative transfer models that are consistent with ARM spectral radiance measurements for clear and cloudy atmospheres. Our approach is to develop the model physics and related databases with a line-by-line model in the context of available spectral radiance measurements. The line-by-line model then functions as an intermediate standard to both develop and validate rapid radiative transfer models appropriate to GCM applications. A preprint of an extended abstract for the 1994 AMS volume describing a Quality Measurement Experiment using the ARM spectral data is included as an attachment
Tian, Ran; Dai, Xiaoye; Wang, Dabiao; Shi, Lin
2018-06-01
In order to improve the prediction performance of the numerical simulations for heat transfer of supercritical pressure fluids, a variable turbulent Prandtl number (Prt) model for vertical upward flow at supercritical pressures was developed in this study. The effects of Prt on the numerical simulation were analyzed, especially for the heat transfer deterioration conditions. Based on the analyses, the turbulent Prandtl number was modeled as a function of the turbulent viscosity ratio and molecular Prandtl number. The model was evaluated using experimental heat transfer data of CO2, water and Freon. The wall temperatures, including the heat transfer deterioration cases, were more accurately predicted by this model than by traditional numerical calculations with a constant Prt. By analyzing the predicted results with and without the variable Prt model, it was found that the predicted velocity distribution and turbulent mixing characteristics with the variable Prt model are quite different from that predicted by a constant Prt. When heat transfer deterioration occurs, the radial velocity profile deviates from the log-law profile and the restrained turbulent mixing then leads to the deteriorated heat transfer.
Implementation of a new interfacial mass and energy transfer model in RETRAN-3D
International Nuclear Information System (INIS)
Macian, R.; Cebulh, P.; Coddington, P.; Paulsen, M.
1999-01-01
The RETRAN-3D MOD002.0 best estimate code includes a five-equation flow field model developed to deal with situations in which thermodynamic non-equilibrium phenomena are important. Several applications of this model to depressurization and pressurization transients showed serious convergence problems. An analysis of the causes for the numerical instabilities identified the models for interfacial heat and mass transfer as the source of the problems. A new interfacial mass and energy transfer model has thus been developed and implemented in RETRAN-3D. The heat transfer for each phase is equal to the product of the interfacial area density, a heat transfer coefficient and the temperature difference between the interface at saturation and the bulk temperature of the respective phase. However, in the context of RETRAN-3D, the vapor remains saturated in a two-phase volume, and no vapor heat transfer is thus calculated. The values of interfacial area density and heat transfer coefficient are obtained based on correlations appropriate for different flow regimes. A flow regime map, based on the work of Taitel and Dukler, with void fraction and mixture mass flux as map coordinates, is used to identify the flow regime present in a given volume. The new model has performed well when assessed against data from four experimental facilities covering depressurization, condensation and steady state void distribution. The results also demonstrate the viability of the approach followed to develop the new model for a five-equation based code. (author)
Predicting soil-to-plant transfer of radionuclides with a mechanistic model (BioRUR)
Energy Technology Data Exchange (ETDEWEB)
Casadesus, J. [Servei de Camps Experimentals, Universitat de Barcelona, Avda Diagonal 645, 08028 Barcelona (Spain); Sauras-Yera, T. [Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avda Diagonal 645, 08028 Barcelona (Spain)], E-mail: msauras@ub.edu; Vallejo, V.R. [Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avda Diagonal 645, 08028 Barcelona (Spain); Centro de Estudios Ambientales del Mediterraneo, Charles Darwin 14, Parc Tecnologic, 46980 Paterna, Valencia (Spain)
2008-05-15
BioRUR model has been developed for the simulation of radionuclide (RN) transfer through physical and biological compartments, based on the available information on the transfer of their nutrient analogues. The model assumes that radionuclides are transferred from soil to plant through the same pathways as their nutrient analogues, where K and Ca are the analogues of Cs and Sr, respectively. Basically, the transfer of radionuclide between two compartments is calculated as the transfer of nutrient multiplied by the ratio of concentrations of RN to nutrient, corrected by a selectivity coefficient. Hydroponic experiments showed the validity of this assumption for root uptake of Cs and Sr and reported a selectivity coefficient around 1.0 for both. However, the application of this approach to soil-to-plant transfer raises some questions on which are the effective concentrations of RN and nutrient detected by the plant uptake mechanism. This paper describes the evaluation of two configurations of BioRUR, one which simplifies the soil as an homogeneous pool, and the other which considers that some concentration gradients develop around roots and therefore ion concentrations at the root surface are different from those of the bulk soil. The results show a good fit between the observed Sr transfer and the mechanistic simulations, even when a homogeneous soil is considered. On the other hand, Cs transfer is overestimated by two orders of magnitude if the development of a decreasing K profile around roots is not taken into account.
Predicting soil-to-plant transfer of radionuclides with a mechanistic model (BioRUR)
International Nuclear Information System (INIS)
Casadesus, J.; Sauras-Yera, T.; Vallejo, V.R.
2008-01-01
BioRUR model has been developed for the simulation of radionuclide (RN) transfer through physical and biological compartments, based on the available information on the transfer of their nutrient analogues. The model assumes that radionuclides are transferred from soil to plant through the same pathways as their nutrient analogues, where K and Ca are the analogues of Cs and Sr, respectively. Basically, the transfer of radionuclide between two compartments is calculated as the transfer of nutrient multiplied by the ratio of concentrations of RN to nutrient, corrected by a selectivity coefficient. Hydroponic experiments showed the validity of this assumption for root uptake of Cs and Sr and reported a selectivity coefficient around 1.0 for both. However, the application of this approach to soil-to-plant transfer raises some questions on which are the effective concentrations of RN and nutrient detected by the plant uptake mechanism. This paper describes the evaluation of two configurations of BioRUR, one which simplifies the soil as an homogeneous pool, and the other which considers that some concentration gradients develop around roots and therefore ion concentrations at the root surface are different from those of the bulk soil. The results show a good fit between the observed Sr transfer and the mechanistic simulations, even when a homogeneous soil is considered. On the other hand, Cs transfer is overestimated by two orders of magnitude if the development of a decreasing K profile around roots is not taken into account
Economic modeling and energy policy planning. [technology transfer, market research
Thompson, R. G.; Schwartz, A., Jr.; Lievano, R. J.; Stone, J. C.
1974-01-01
A structural economic model is presented for estimating the demand functions for natural gas and crude oil in industry and in steam electric power generation. Extensions of the model to other commodities are indicated.
Knowledge transfer for learning robot models via local procrustes analysis
CSIR Research Space (South Africa)
Makondo, N
2015-11-01
Full Text Available Learning of robot kinematic and dynamic models from data has attracted much interest recently as an alternative to manually defined models. However, the amount of data required to learn these models becomes large when the number of degrees...
Mechanism and models for collisional energy transfer in highly excited large polyatomic molecules
International Nuclear Information System (INIS)
Gilbert, R. G.
1995-01-01
Collisional energy transfer in highly excited molecules (say, 200-500 kJ mol -1 above the zero-point energy of reactant, or of product, for a recombination reaction) is reviewed. An understanding of this energy transfer is important in predicting and interpreting the pressure dependence of gas-phase rate coefficients for unimolecular and recombination reactions. For many years it was thought that this pressure dependence could be calculated from a single energy-transfer quantity, such as the average energy transferred per collision. However, the discovery of 'super collisions' (a small but significant fraction of collisions which transfer abnormally large amounts of energy) means that this simplistic approach needs some revision. The 'ordinary' (non-super) component of the distribution function for collisional energy transfer can be quantified either by empirical models (e.g., an exponential-down functional form) or by models with a physical basis, such as biased random walk (applicable to monatomic or diatomic collision partners) or ergodic (for polyatomic collision partners) treatments. The latter two models enable approximate expressions for the average energy transfer to be estimated from readily available molecular parameters. Rotational energy transfer, important for finding the pressure dependence for recombination reactions, can for these purposes usually be taken as transferring sufficient energy so that the explicit functional form is not required to predict the pressure dependence. The mechanism of 'ordinary' energy transfer seems to be dominated by low-frequency modes of the substrate, whereby there is sufficient time during a vibrational period for significant energy flow between the collision partners. Super collisions may involve sudden energy flow as an outer atom of the substrate is squashed between the substrate and the bath gas, and then is moved away from the interaction by large-amplitude motion such as a ring vibration or a rotation; improved
Markovian approach: From Ising model to stochastic radiative transfer
International Nuclear Information System (INIS)
Kassianov, E.; Veron, D.
2009-01-01
The origin of the Markovian approach can be traced back to 1906; however, it gained explicit recognition in the last few decades. This overview outlines some important applications of the Markovian approach, which illustrate its immense prestige, respect, and success. These applications include examples in the statistical physics, astronomy, mathematics, computational science and the stochastic transport problem. In particular, the overview highlights important contributions made by Pomraning and Titov to the neutron and radiation transport theory in a stochastic medium with homogeneous statistics. Using simple probabilistic assumptions (Markovian approximation), they have introduced a simplified, but quite realistic, representation of the neutron/radiation transfer through a two-component discrete stochastic mixture. New concepts and methodologies introduced by these two distinguished scientists allow us to generalize the Markovian treatment to the stochastic medium with inhomogeneous statistics and demonstrate its improved predictive performance for the down-welling shortwave fluxes. (authors)
MODEL OF REGIONAL KNOWLEDGE TRANSFER: MAIN ACTORS, FRAMEWORK AND THEORY.
Directory of Open Access Journals (Sweden)
Alla LEVITSKAIA
2016-02-01
Full Text Available This paper analyses potential mechanism of regional knowledge transfer in region with poorly developed innovation infrastructure (the Autonomous Territorial Unit Gagauzia, Republic of Moldova through interactions between regional major players of the Regional Innovation System - the educational and research institutions, small and medium enterprises (SMEs and local authorities. Solution of this problem can be found in modern studies of territories innovation development through the clustering processes. Through the empirical study - innovation potential analysis of local SMEs - we proposed advantage mechanism which focused on the one type of knowledge cluster – Innovation and Educational Cluster. The symbiosis of entrepreneurs, government agencies, educational institutions and business service providers with the regional core - University, allows to increasing exchange flows of innovative knowledge between all members of the cluster and distributing them to the entire region and beyond. The results and proposals of this study formed the basis of the “Program of increasing the innovation potential of Gagauz SMEs”.
International Nuclear Information System (INIS)
Tateda, Yutaka; Tsumune, Daisuke; Tsubono, Takaki
2013-01-01
The Fukushima Dai-ichi Nuclear Power Plant (1F NPP) accident occurred on 11 March 2011. The accident introduced 137 Cs into the coastal waters which was subsequently transferred to the local coastal biota thereby elevating the concentration of this radionuclide in coastal organisms. In this study, the radioactive cesium levels in coastal biota from the southern Fukushima area were simulated using a dynamic biological compartment model. The simulation derived the possible maximum radioactive cesium levels in organisms, indicating that the maximum 137 Cs concentrations in invertebrates, benthic fish and predator fish occurred during late April, late May and late July, respectively in the studied area where the source was mainly the direct leakage of 137 Cs effluent from the 1F NPP. The delay of a 137 Cs increase in fish was explained by the gradual food chain transfer of 137 Cs introduced to the ecosystem from the initial contamination of the seawater. The model also provided the degree of radionuclide depuration in organisms, and it demonstrated the latest start of the decontamination phase in benthic fish. The ecological half-lives, derived both from model simulation and observation, were 1–4 months in invertebrates, and 2–9 months in plankton feeding fish and coastal predator fish from the studied area. In contrast, it was not possible to similarly calculate these parameters in benthic fish because of an unidentified additional radionuclide source which was deduced from the biological compartment model. To adequately reconstruct the in-situ depuration of radiocesium in benthic fish in the natural ecosystem, a contamination source associated with the bottom sediments is necessary. -- Highlights: • Cs-137 in the southern Fukushima coastal biota were simulated using a dynamic biological compartment model. • Simulation derived contamination phase of marine biota was completed until late April to July 2011. • The delay of Cs-137 concentration increase in fish
Research Strategy for Modeling the Complexities of Turbine Heat Transfer
Simoneau, Robert J.
1996-01-01
The subject of this paper is a NASA research program, known as the Coolant Flow Management Program, which focuses on the interaction between the internal coolant channel and the external film cooling of a turbine blade and/or vane in an aircraft gas turbine engine. The turbine gas path is really a very complex flow field. The combination of strong pressure gradients, abrupt geometry changes and intersecting surfaces, viscous forces, rotation, and unsteady blade/vane interactions all combine to offer a formidable challenge. To this, in the high pressure turbine, we add the necessity of film cooling. The ultimate goal of the turbine designer is to maintain or increase the high level of turbine performance and at the same time reduce the amount of coolant flow needed to achieve this end. Simply stated, coolant flow is a penalty on the cycle and reduces engine thermal efficiency. Accordingly, understanding the flow field and heat transfer associated with the coolant flow is a priority goal. It is important to understand both the film cooling and the internal coolant flow, particularly their interaction. Thus, the motivation for the Coolant Flow Management Program. The paper will begin with a brief discussion of the management and research strategy, will then proceed to discuss the current attack from the internal coolant side, and will conclude by looking at the film cooling effort - at all times keeping sight of the primary goal the interaction between the two. One of the themes of this paper is that complex heat transfer problems of this nature cannot be attacked by single researchers or even groups of researchers, each working alone. It truly needs the combined efforts of a well-coordinated team to make an impact. It is important to note that this is a government/industry/university team effort.
Theoretical study of evaporation heat transfer in horizontal microfin tubes: stratified flow model
Energy Technology Data Exchange (ETDEWEB)
Honda, H; Wang, Y S [Kyushu Univ., Inst. for Materials Chemistry and Engineering, Kasuga, Fukuoka (Japan)
2004-08-01
The stratified flow model of evaporation heat transfer in helically grooved, horizontal microfin tubes has been developed. The profile of stratified liquid was determined by a theoretical model previously developed for condensation in horizontal microfin tubes. For the region above the stratified liquid, the meniscus profile in the groove between adjacent fins was determined by a force balance between the gravity and surface tension forces. The thin film evaporation model was applied to predict heat transfer in the thin film region of the meniscus. Heat transfer through the stratified liquid was estimated by using an empirical correlation proposed by Mori et al. The theoretical predictions of the circumferential average heat transfer coefficient were compared with available experimental data for four tubes and three refrigerants. A good agreement was obtained for the region of Fr{sub 0}<2.5 as long as partial dry out of tube surface did not occur. (Author)
The Model of Lake Operation in Water Transfer Projects Based on the Theory of Water- right
Bi-peng, Yan; Chao, Liu; Fang-ping, Tang
the lake operation is a very important content in Water Transfer Projects. The previous studies have not any related to water-right and water- price previous. In this paper, water right is divided into three parts, one is initialization waterright, another is by investment, and the third is government's water- right re-distribution. The water-right distribution model is also build. After analyzing the cost in water transfer project, a model and computation method for the capacity price as well as quantity price is proposed. The model of lake operation in water transfer projects base on the theory of water- right is also build. The simulation regulation for the lake was carried out by using historical data and Genetic Algorithms. Water supply and impoundment control line of the lake was proposed. The result can be used by south to north water transfer projects.
Selection of heat transfer model for describing short-pulse laser heating silica-based sensor
International Nuclear Information System (INIS)
Hao Xiangnan; Nie Jinsong; Li Hua; Bian Jintian
2012-01-01
The fundamental equations of Fourier heat transfer model and non-Fourier heat transfer model were numerically solved, with the finite difference method. The relative changes between temperature curves of the two heat transfer models were analyzed under laser irradiation with different pulse widths of 10 ns, 1 ns, 100 ps, 10 ps. The impact of different thermal relaxation time on non-Fourier model results was discussed. For pulses of pulse width less than or equal to 100 ps irradiating silicon material, the surface temperature increases slowly and carrier effect happens, which the non-Fourier model can reflect properly. As for general material, when the pulse width is less than or equal to the thermal relaxation time of material, carrier effect occurs. In this case, the non-Fourier model should be used. (authors)
Modeling and Simulation of Bus Dispatching Policy for Timed Transfers on Signalized Networks
Cho, Hsun-Jung; Lin, Guey-Shii
2007-12-01
The major work of this study is to formulate the system cost functions and to integrate the bus dispatching policy with signal control. The integrated model mainly includes the flow dispersion model for links, signal control model for nodes, and dispatching control model for transfer terminals. All such models are inter-related for transfer operations in one-center transit network. The integrated model that combines dispatching policies with flexible signal control modes can be applied to assess the effectiveness of transfer operations. It is found that, if bus arrival information is reliable, an early dispatching decision made at the mean bus arrival times is preferable. The costs for coordinated operations with slack times are relatively low at the optimal common headway when applying adaptive route control. Based on such findings, a threshold function of bus headway for justifying an adaptive signal route control under various time values of auto drivers is developed.
Metro passengers’ route choice model and its application considering perceived transfer threshold
Jin, Fanglei; Zhang, Yongsheng; Liu, Shasha
2017-01-01
With the rapid development of the Metro network in China, the greatly increased route alternatives make passengers’ route choice behavior and passenger flow assignment more complicated, which presents challenges to the operation management. In this paper, a path sized logit model is adopted to analyze passengers’ route choice preferences considering such parameters as in-vehicle time, number of transfers, and transfer time. Moreover, the “perceived transfer threshold” is defined and included in the utility function to reflect the penalty difference caused by transfer time on passengers’ perceived utility under various numbers of transfers. Next, based on the revealed preference data collected in the Guangzhou Metro, the proposed model is calibrated. The appropriate perceived transfer threshold value and the route choice preferences are analyzed. Finally, the model is applied to a personalized route planning case to demonstrate the engineering practicability of route choice behavior analysis. The results show that the introduction of the perceived transfer threshold is helpful to improve the model’s explanatory abilities. In addition, personalized route planning based on route choice preferences can meet passengers’ diversified travel demands. PMID:28957376
Image-Based Modeling of Blood Flow and Oxygen Transfer in Feto-Placental Capillaries.
Directory of Open Access Journals (Sweden)
Philip Pearce
Full Text Available During pregnancy, oxygen diffuses from maternal to fetal blood through villous trees in the placenta. In this paper, we simulate blood flow and oxygen transfer in feto-placental capillaries by converting three-dimensional representations of villous and capillary surfaces, reconstructed from confocal laser scanning microscopy, to finite-element meshes, and calculating values of vascular flow resistance and total oxygen transfer. The relationship between the total oxygen transfer rate and the pressure drop through the capillary is shown to be captured across a wide range of pressure drops by physical scaling laws and an upper bound on the oxygen transfer rate. A regression equation is introduced that can be used to estimate the oxygen transfer in a capillary using the vascular resistance. Two techniques for quantifying the effects of statistical variability, experimental uncertainty and pathological placental structure on the calculated properties are then introduced. First, scaling arguments are used to quantify the sensitivity of the model to uncertainties in the geometry and the parameters. Second, the effects of localized dilations in fetal capillaries are investigated using an idealized axisymmetric model, to quantify the possible effect of pathological placental structure on oxygen transfer. The model predicts how, for a fixed pressure drop through a capillary, oxygen transfer is maximized by an optimal width of the dilation. The results could explain the prevalence of fetal hypoxia in cases of delayed villous maturation, a pathology characterized by a lack of the vasculo-syncytial membranes often seen in conjunction with localized capillary dilations.
Simultaneous Heat and Mass Transfer Model for Convective Drying of Building Material
Upadhyay, Ashwani; Chandramohan, V. P.
2018-04-01
A mathematical model of simultaneous heat and moisture transfer is developed for convective drying of building material. A rectangular brick is considered for sample object. Finite-difference method with semi-implicit scheme is used for solving the transient governing heat and mass transfer equation. Convective boundary condition is used, as the product is exposed in hot air. The heat and mass transfer equations are coupled through diffusion coefficient which is assumed as the function of temperature of the product. Set of algebraic equations are generated through space and time discretization. The discretized algebraic equations are solved by Gauss-Siedel method via iteration. Grid and time independent studies are performed for finding the optimum number of nodal points and time steps respectively. A MATLAB computer code is developed to solve the heat and mass transfer equations simultaneously. Transient heat and mass transfer simulations are performed to find the temperature and moisture distribution inside the brick.
Liu, Yan; Cai, Wensheng; Shao, Xueguang
2016-12-01
Calibration transfer is essential for practical applications of near infrared (NIR) spectroscopy because the measurements of the spectra may be performed on different instruments and the difference between the instruments must be corrected. For most of calibration transfer methods, standard samples are necessary to construct the transfer model using the spectra of the samples measured on two instruments, named as master and slave instrument, respectively. In this work, a method named as linear model correction (LMC) is proposed for calibration transfer without standard samples. The method is based on the fact that, for the samples with similar physical and chemical properties, the spectra measured on different instruments are linearly correlated. The fact makes the coefficients of the linear models constructed by the spectra measured on different instruments are similar in profile. Therefore, by using the constrained optimization method, the coefficients of the master model can be transferred into that of the slave model with a few spectra measured on slave instrument. Two NIR datasets of corn and plant leaf samples measured with different instruments are used to test the performance of the method. The results show that, for both the datasets, the spectra can be correctly predicted using the transferred partial least squares (PLS) models. Because standard samples are not necessary in the method, it may be more useful in practical uses.
Evaluation of Advanced Models for PAFS Condensation Heat Transfer in SPACE Code
Energy Technology Data Exchange (ETDEWEB)
Bae, Byoung-Uhn; Kim, Seok; Park, Yu-Sun; Kang, Kyung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ahn, Tae-Hwan; Yun, Byong-Jo [Pusan National University, Busan (Korea, Republic of)
2015-10-15
The PAFS (Passive Auxiliary Feedwater System) is operated by the natural circulation to remove the core decay heat through the PCHX (Passive Condensation Heat Exchanger) which is composed of the nearly horizontal tubes. For validation of the cooling and operational performance of the PAFS, PASCAL (PAFS Condensing Heat Removal Assessment Loop) facility was constructed and the condensation heat transfer and natural convection phenomena in the PAFS was experimentally investigated at KAERI (Korea Atomic Energy Research Institute). From the PASCAL experimental result, it was found that conventional system analysis code underestimated the condensation heat transfer. In this study, advanced condensation heat transfer models which can treat the heat transfer mechanisms with the different flow regimes in the nearly horizontal heat exchanger tube were analyzed. The models were implemented in a thermal hydraulic safety analysis code, SPACE (Safety and Performance Analysis Code for Nuclear Power Plant), and it was evaluated with the PASCAL experimental data. With an aim of enhancing the prediction capability for the condensation phenomenon inside the PCHX tube of the PAFS, advanced models for the condensation heat transfer were implemented into the wall condensation model of the SPACE code, so that the PASCAL experimental result was utilized to validate the condensation models. Calculation results showed that the improved model for the condensation heat transfer coefficient enhanced the prediction capability of the SPACE code. This result confirms that the mechanistic modeling for the film condensation in the steam phase and the convection in the condensate liquid contributed to enhance the prediction capability of the wall condensation model of the SPACE code and reduce conservatism in prediction of condensation heat transfer.
Modelling of Multi Input Transfer Function for Rainfall Forecasting in Batu City
Directory of Open Access Journals (Sweden)
Priska Arindya Purnama
2017-11-01
Full Text Available The aim of this research is to model and forecast the rainfall in Batu City using multi input transfer function model based on air temperature, humidity, wind speed and cloud. Transfer function model is a multivariate time series model which consists of an output series (Yt sequence expected to be effected by an input series (Xt and other inputs in a group called a noise series (Nt. Multi input transfer function model obtained is (b1,s1,r1 (b2,s2,r2 (b3,s3,r3 (b4,s4,r4(pn,qn = (0,0,0 (23,0,0 (1,2,0 (0,0,0 ([5,8],2 and shows that air temperature on t-day affects rainfall on t-day, rainfall on t-day is influenced by air humidity in the previous 23 days, rainfall on t-day is affected by wind speed in the previous day , and rainfall on day t is affected by clouds on day t. The results of rainfall forecasting in Batu City with multi input transfer function model can be said to be accurate, because it produces relatively small RMSE value. The value of RMSE data forecasting training is 7.7921 while forecasting data testing is 4.2184. Multi-input transfer function model is suitable for rainfall in Batu City.
Analytical modeling for heat transfer in sheared flows of nanofluids
Ferrari, C.; Kaoui, B.; L'vov, V.S.; Procaccia, I.; Rudenko, O.; Thije Boonkkamp, ten J.H.M.; Toschi, F.
2012-01-01
We developed a model for the enhancement of the heat flux by spherical and elongated nanoparticles in sheared laminar flows of nanofluids. Besides the heat flux carried by the nanoparticles, the model accounts for the contribution of their rotation to the heat flux inside and outside the particles.
Fostering Transfer of Study Strategies: A Spiral Model.
Davis, Denise M.; Clery, Carolsue
1994-01-01
Describes the design and implementation of a Spiral Model for the introduction and repeated practice of study strategies, based on Taba's model for social studies. In a college reading and studies strategies course, key strategies were introduced early and used through several sets of humanities and social and physical sciences readings. (Contains…
Mouse Xenograft Model for Mesothelioma | NCI Technology Transfer Center | TTC
The National Cancer Institute is seeking parties interested in collaborative research to co-develop, evaluate, or commercialize a new mouse model for monoclonal antibodies and immunoconjugates that target malignant mesotheliomas. Applications of the technology include models for screening compounds as potential therapeutics for mesothelioma and for studying the pathology of mesothelioma.
Transfer Learning for OCRopus Model Training on Early Printed Books
Directory of Open Access Journals (Sweden)
Christian Reul
2017-12-01
Full Text Available A method is presented that significantly reduces the character error rates for OCR text obtained from OCRopus models trained on early printed books when only small amounts of diplomatic transcriptions are available. This is achieved by building from already existing models during training instead of starting from scratch. To overcome the discrepancies between the set of characters of the pretrained model and the additional ground truth the OCRopus code is adapted to allow for alphabet expansion or reduction. The character set is now capable of flexibly adding and deleting characters from the pretrained alphabet when an existing model is loaded. For our experiments we use a self-trained mixed model on early Latin prints and the two standard OCRopus models on modern English and German Fraktur texts. The evaluation on seven early printed books showed that training from the Latin mixed model reduces the average amount of errors by 43% and 26%, compared to training from scratch with 60 and 150 lines of ground truth, respectively. Furthermore, it is shown that even building from mixed models trained on standard data unrelated to the newly added training and test data can lead to significantly improved recognition results.
Analytical modeling for heat transfer in sheared flows of nanofluids.
Ferrari, Claudio; Kaoui, Badr; L'vov, Victor S; Procaccia, Itamar; Rudenko, Oleksii; ten Thije Boonkkamp, J H M; Toschi, Federico
2012-07-01
We developed a model for the enhancement of the heat flux by spherical and elongated nanoparticles in sheared laminar flows of nanofluids. Besides the heat flux carried by the nanoparticles, the model accounts for the contribution of their rotation to the heat flux inside and outside the particles. The rotation of the nanoparticles has a twofold effect: it induces a fluid advection around the particle and it strongly influences the statistical distribution of particle orientations. These dynamical effects, which were not included in existing thermal models, are responsible for changing the thermal properties of flowing fluids as compared to quiescent fluids. The proposed model is strongly supported by extensive numerical simulations, demonstrating a potential increase of the heat flux far beyond the Maxwell-Garnett limit for the spherical nanoparticles. The road ahead, which should lead toward robust predictive models of heat flux enhancement, is discussed.
Zhou, Jianlong; Takatsuka, Masahiro
2009-01-01
Transfer functions facilitate the volumetric data visualization by assigning optical properties to various data features and scalar values. Automation of transfer function specifications still remains a challenge in volume rendering. This paper presents an approach for automating transfer function generations by utilizing topological attributes derived from the contour tree of a volume. The contour tree acts as a visual index to volume segments, and captures associated topological attributes involved in volumetric data. A residue flow model based on Darcy's Law is employed to control distributions of opacity between branches of the contour tree. Topological attributes are also used to control color selection in a perceptual color space and create harmonic color transfer functions. The generated transfer functions can depict inclusion relationship between structures and maximize opacity and color differences between them. The proposed approach allows efficient automation of transfer function generations, and exploration on the data to be carried out based on controlling of opacity residue flow rate instead of complex low-level transfer function parameter adjustments. Experiments on various data sets demonstrate the practical use of our approach in transfer function generations.
Radionuclide transfer from soil to agricultural plants: measurements and modelling
International Nuclear Information System (INIS)
Sabbarese, C; Terrasi, F.; D'Onofrio, A.D.; Stellato, L.; Lubritto, C.; Ermice, A.; Cotrufo, M.F.
2002-01-01
To assess the internal doses to humans from ingestion of radionuclides present in agricultural products it is necessary to know the main processes which determine the transport of radionuclides in the environment (Russel, 1966; Peterson, 1983; IAEA, 1995). The available data, generally, do not reflect natural conditions, and the mechanisms of translocation and mobility of radionuclides within the soil-plant system are still not fully understood (Coughtrey and Thorne, 1983; Fresquez et a., 1998; Krouglov et al., 1997; Frissel, 1992; Roca and Vallejo, 1995; Desmet et al., 1990). The knowledge of the contributions of direct contamination of plant fruits and of the process of root to fruit transfer can improve the understanding of exposure through ingestion and of the mechanisms determining sorption and translocation. Several studies on the relations among specific activities of various radionuclides in different environmental compartments have been performed in the last decades (Coughtrey and Thorne, 1983; Fresquez et al., 1998; Krouglov et al., 1997; Howard et al., 1995; Strand et al., 1994; Konshin, 1992; Frissel, 1992; Alexakhin and Korneev, 1992; Desmet et al., 1990)
Modelling and experimental studies on the transfer of radionuclides to fruit
International Nuclear Information System (INIS)
Carini, F.; Atkinson, C.J.; Collins, C.; Coughtrey, P.J.; Eged, K.; Fulker, M.; Green, N.; Kinnersley, R.; Linkov, I.; Mitchell, N.G.; Mourlon, C.; Ould-Dada, Z.; Quinault, J.M.; Robles, B.; Stewart, A.; Sweeck, L.; Venter, A.
2005-01-01
Although fruit is an important component of the diet, the extent to which it contributes to radiological exposure remains unclear, partially as a consequence of uncertainties in models and data used to assess transfer of radionuclides in the food chain. A Fruits Working Group operated as part of the IAEA BIOMASS (BIOsphere Modelling and ASSessment) programme from 1997 to 2000, with the aim of improving the robustness of the models that are used for radiological assessment. The Group completed a number of modelling and experimental activities including: (i) a review of experimental, field and modelling information on the transfer of radionuclides to fruit; (ii) discussion of recently completed or ongoing experimental studies; (iii) development of a database on the transfer of radionuclides to fruit; (iv) development of a conceptual model for fruit and (v) two model intercomparison studies and a model validation study. The Group achieved significant advances in understanding the processes involved in transfer of radionuclides to fruit. The work demonstrated that further experimental and modelling studies are required to ensure that the current generation of models can be applied to a wide range of scenarios
Vanreusel, Wouter; Maes, Dirk; Van Dyck, Hans
2007-02-01
Numerous models for predicting species distribution have been developed for conservation purposes. Most of them make use of environmental data (e.g., climate, topography, land use) at a coarse grid resolution (often kilometres). Such approaches are useful for conservation policy issues including reserve-network selection. The efficiency of predictive models for species distribution is usually tested on the area for which they were developed. Although highly interesting from the point of view of conservation efficiency, transferability of such models to independent areas is still under debate. We tested the transferability of habitat-based predictive distribution models for two regionally threatened butterflies, the green hairstreak (Callophrys rubi) and the grayling (Hipparchia semele), within and among three nature reserves in northeastern Belgium. We built predictive models based on spatially detailed maps of area-wide distribution and density of ecological resources. We used resources directly related to ecological functions (host plants, nectar sources, shelter, microclimate) rather than environmental surrogate variables. We obtained models that performed well with few resource variables. All models were transferable--although to different degrees--among the independent areas within the same broad geographical region. We argue that habitat models based on essential functional resources could transfer better in space than models that use indirect environmental variables. Because functional variables can easily be interpreted and even be directly affected by terrain managers, these models can be useful tools to guide species-adapted reserve management.
Bridging the Radiative Transfer Models for Meteorology and Solar Energy Applications
Xie, Y.; Sengupta, M.
2017-12-01
Radiative transfer models are used to compute solar radiation reaching the earth surface and play an important role in both meteorology and solar energy studies. Therefore, they are designed to meet the needs of specialized applications. For instance, radiative transfer models for meteorology seek to provide more accurate cloudy-sky radiation compared to models used in solar energy that are geared towards accuracy in clear-sky conditions associated with the maximum solar resource. However, models for solar energy applications are often computationally faster, as the complex solution of the radiative transfer equation is parameterized by atmospheric properties that can be acquired from surface- or satellite-based observations. This study introduces the National Renewable Energy Laboratory's (NREL's) recent efforts to combine the advantages of radiative transfer models designed for meteorology and solar energy applictions. A fast all-sky radiation model, FARMS-NIT, was developed to efficiently compute narrowband all-sky irradiances over inclined photovoltaic (PV) panels. This new model utilizes the optical preperties from a solar energy model, SMARTS, to computes surface radiation by considering all possible paths of photon transmission and the relevent scattering and absorption attenuation. For cloudy-sky conditions, cloud bidirectional transmittance functions (BTDFs) are provided by a precomputed lookup table (LUT) by LibRadtran. Our initial results indicate that FARMS-NIT has an accuracy that is similar to LibRadtran, a highly accurate multi-stream model, but is significantly more efficient. The development and validation of this model will be presented.
Numerical transfer-matrix study of a model with competing metastable states
DEFF Research Database (Denmark)
Fiig, T.; Gorman, B.M.; Rikvold, P.A.
1994-01-01
transition. A recently developed transfer-matrix formalism is applied to the model to obtain complex-valued ''constrained'' free-energy densities f(alpha). For particular eigenvectors of the transfer matrix, the f(alpha) exhibit finite-rangescaling behavior in agreement with the analytically continued...... 'metastable free-energy density This transfer-matrix approach gives a free-energy cost of nucleation that supports the proportionality relation for the decay rate of the metastable phase T proportional to\\Imf alpha\\, even in cases where two metastable states compete. The picture that emerges from this study...
Modeling of Tilting-Pad Journal Bearings with Transfer Functions
Directory of Open Access Journals (Sweden)
J. A. Vázquez
2001-01-01
Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.
Dynamic modeling system for the transfer of radioactivity in terrestrial food chains
International Nuclear Information System (INIS)
Simmonds, J.R.; Linsley, G.S.
1981-01-01
A dynamic modeling system is described for the transfer of radionuclides in terrestrial food chains. The main features of the system are its ability to predict the time dependence of the major transfer processes and its flexibility and applicability to a range of contamination scenarios. The modeling system is regarded as a basic framework on which more realistic models can be based, given the availability of reliable environmental transfer data. An example of such a development is included for 90 Sr in the pasture-cow-milk pathway. The model predicts annual average concentrations of 90 Sr in milk caused by fallout in the United Kingdom to within 15% of measured values for over most of the 20-y period for which data exist. It makes possible the evaluation of the time dependence of the contributions of various transfer processes. Following acute releases to the atmosphere or releases in any other contamination scenario where direct deposition is absent, certain pathways often not considered in food-chain models, such as the external contamination of plants caused by resuspension processes or the ingestion of contaminants together with soil by grazing animals, are shown to be potentially important in the transfer of activity to man. The main application of dynamic food-chain models is the prediction of the consequences of accidental releases to the terrestrial environment. The predictions can be used in planning countermeasures and in assessing the health, economic, and social impacts of accidental release
Challenges in land model representation of heat transfer in snow and frozen soils
Musselman, K. N.; Clark, M. P.; Nijssen, B.; Arnold, J.
2017-12-01
Accurate model simulations of soil thermal and moisture states are critical for realistic estimates of exchanges of energy, water, and biogeochemical fluxes at the land-atmosphere interface. In cold regions, seasonal snow-cover and organic soils form insulating barriers, modifying the heat and moisture exchange that would otherwise occur between mineral soils and the atmosphere. The thermal properties of these media are highly dynamic functions of mass, water and ice content. Land surface models vary in their representation of snow and soil processes, and thus in the treatment of insulation and heat exchange. For some models, recent development efforts have improved representation of heat transfer in cold regions, such as with multi-layer snow treatment, inclusion of soil freezing and organic soil properties, yet model deficiencies remain prevalent. We evaluate models that participated in the Protocol for the Analysis of Land Surface Models (PALS) Land Surface Model Benchmarking Evaluation Project (PLUMBER) experiment for proficiency in simulating heat transfer between the soil through the snowpack to the atmosphere. Using soil observations from cold region sites and a controlled experiment with Structure for Unifying Multiple Modeling Alternatives (SUMMA), we explore the impact of snow and soil model decisions and parameter values on heat transfer model skill. Specifically, we use SUMMA to mimic the spread of behaviors exhibited by the models that participated in PLUMBER. The experiment allows us to isolate relationships between model skill and process representation. The results are aimed to better understand existing model challenges and identify potential advances for cold region models.
Three-dimensional modelling of a dc non-transferred arc plasma torch
International Nuclear Information System (INIS)
Li Heping; Chen Xi
2001-01-01
Three-dimensional (3D) modelling results are presented concerning a direct current (dc) non-transferred arc plasma torch with axisymmetrical geometrical configuration and axisymmetrical boundary conditions. It is shown that the arc is locally attached at the anode surface of the plasma torch, and the heat transfer and plasma flow within the torch are of 3D features. The predicted arc root location at the anode surface and arc voltage of the torch are very consistent with corresponding experimental results. (author)
Model studies of the transfer of radionuclides in the Finnish environment
International Nuclear Information System (INIS)
Korhonen, R.
1991-01-01
Environmental modelling of the effects of radionuclide releases was studied. A computer model DETl2A was developed for evaluation of radionuclide transfer. The flexible structure of the model made it suitable for a wide range of applications. The model was employed to evaluate the biospheric transfer of radionuclides in two situations: 1) release cases from planned waste repositories in Finland, and 2) deposition due to the Chernobyl accident. The Chernobyl accident provided a good opportunity to test the DETRA model, originally constructed for waste disposal applications. A study was made of some biospheric local, regional and global scale scenarios, to which releases from repositories were assumed. Drinking water from a local well and consumption of fish were the most important dose pathways. The transfer of the Chernobyl deposition in some important Finnish transfer environments was evaluated. Especially the transfer of Cs-137 in the Kymijoki watercourse, including dynamic transfer to non-predatory and predatory fish species was studied. The calculated behaviour was compared with the measured behaviour. Nuclear weapon testing fallout was also considered in the comparison studies. On the basis of validation studies it was concluded that part of the Cs-137 deposition was in insoluble form. These model assumptions give that deposition consisting of soluble Cs-l37 could cause fourfold contamination of fish per unit deposition than deposition due to the Chernobyl accident in the modelled case. Model validation was also performed within international projects, in particular by participating in the BIOMOVS project. This participation will be continued in the VAMP program. In the summary part of the thesis the main attention is paid to modelling questions, whereas in the accompanying publications the results are presented in greater detail
International Nuclear Information System (INIS)
Park, Hyun Sik; Choi, Ki Yong; Moon, Sang Ki; Kim, Jung Woo; Kim, Kyung Doo
2009-01-01
The wall condensation heat transfer models are developed for the SPACE code and are assessed for various condensation conditions. Both default and alternative models were selected through an extensive literature survey. For a pure steam condensation, a maximum value among the Nusselt, Chato, and Shah's correlations is used in order to consider the geometric and turbulent effects. In the presence of non-condensable gases, the Colburn-Hougen's diffusion model was used as a default model and a non-iterative condensation model proposed by No and Park was selected as an alternative model. The wall condensation heat transfer models were assessed preliminarily by using arbitrary test conditions. Both wall condensation models could simulate the heat transfer coefficients and heat fluxes in the vertical, horizontal and turbulent conditions quite reasonably for a pure steam condensation. Both the default and alternative wall condensation models were also verified for the condensation heat transfer coefficient and heat flux in the presence of noncondensable gas. However, some improvements and further detailed verification are necessary for the condensation phenomena in the presence of noncondensable gas
International Nuclear Information System (INIS)
Saito, Masahiro; Ishida, M.R.
1987-01-01
To evaluate the accumulated dose in human bodies due to the environmental tritium, it is of required to establish an adequate model for the tritium transfer from the environment to man and to obtain enough information on the metabolic behaviour of tritium in animal bodies using model animal system. In this report, first we describe about a proposed model for the transfer of environmental tritium to man and secondly mention briefly about the recent works on the tritium metabolism in newborn animals which have been treated as a model system of tritium intake through food chain. (author)
SCIATRAN 3.1: A new radiative transfer model and retrieval package
Rozanov, Alexei; Rozanov, Vladimir; Kokhanovsky, Alexander; Burrows, John P.
The SCIATRAN 3.1 package is a result of further development of the SCIATRAN 2.X software family which, similar to previous versions, comprises a radiative transfer model and a retrieval block. After an implementation of the vector radiative transfer model in SCIATRAN 3.0 the spectral range covered by the model has been extended into the thermal infrared ranging to approximately 40 micrometers. Another major improvement has been done accounting for the underlying surface effects. Among others, a sophisticated representation of the water surface with a bidirectional reflection distribution function (BRDF) has been implemented accounting for the Fresnel reflection of the polarized light and for the effect of foam. A newly developed representation for a snow surface allows radiative transfer calculations to be performed within an unpolluted or soiled snow layer. Furthermore, a new approach has been implemented allowing radiative transfer calculations to be performed for a coupled atmosphere-ocean system. This means that, the underlying ocean is not considered as a purely reflecting surface any more. Instead, full radiative transfer calculations are performed within the water allowing the user to simulate the radiance within both the atmosphere and the ocean. Similar to previous versions, the simulations can be performed for any viewing geometry typi-cal for atmospheric observations in the UV-Vis-NIR-TIR spectral range (nadir, limb, off-axis, etc.) as well as for any observer location within or outside the Earth's atmosphere including underwater observations. Similar to the precursor version, the new model is freely available for non-commercial use via the web page of the University of Bremen. In this presentation a short description of the software package, especially of the new features of the radiative transfer model is given, including remarks on the availability for the scientific community. Furthermore, some application examples of the radiative transfer model are
Basilevsky, M. V.; Odinokov, A. V.; Titov, S. V.; Mitina, E. A.
2013-12-01
The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ξ0 = ℏω0/kBT where ω0 is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (ξ0 conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the kinetic regimes, which are usually postulated in the existing theories of the ET. Our alternative dynamic ET model for local modes immersed in the continuum harmonic medium is formulated for both classical and quantum regimes, and accounts explicitly for the mode/medium interaction. The kinetics of the energy exchange between the local ET subsystem and the surrounding environment essentially determine the total ET rate. The efficient computer code for rate computations is elaborated on. The computations are available for a wide range of system parameters, such as the temperature, external field, local mode frequency, and characteristics of mode/medium interaction. The relation of the
Heat Transfer Modeling and Validation for Optically Thick Alumina Fibrous Insulation
Daryabeigi, Kamran
2009-01-01
Combined radiation/conduction heat transfer through unbonded alumina fibrous insulation was modeled using the diffusion approximation for modeling the radiation component of heat transfer in the optically thick insulation. The validity of the heat transfer model was investigated by comparison to previously reported experimental effective thermal conductivity data over the insulation density range of 24 to 96 kg/cu m, with a pressure range of 0.001 to 750 torr (0.1 to 101.3 x 10(exp 3) Pa), and test sample hot side temperature range of 530 to 1360 K. The model was further validated by comparison to thermal conductivity measurements using the transient step heating technique on an insulation sample at a density of 144 kg/cu m over a pressure range of 0.001 to 760 torr, and temperature range of 290 to 1090 K.
Review of Bose-Fermi and ''Supersymmetry'' models; problems in particle transfer tests
International Nuclear Information System (INIS)
Vergnes, M.
1986-01-01
The first case suggested for a supersymmetry in nuclei was that of a j = 3/2 particle coupled to an 0(6) core. A more recent and elaborate scheme is the ''multi-j'' supersymmetry, describing the coupling of a particle in more than just one orbital, with the three possible cores of the interacting boson model. A general survey of the particle transfer tests of these different models is presented and the results summarized. A comparison of IBFM-2 calculations with experimental data is discussed, as well as results of sum rules analysis. Present and future tests concerning extensions of the above mentioned models, particularly to odd-odd nuclei, are briefly indicated. It appears necessary to clearly determine if the origin of the difficulties outlined for transfer reactions indeed lies -as often suggested- in the simplified form of the transfer operator used in deriving the selection rules, and not in the models themselves
Numerical study on identification of transfer functions in a feedback system and model reduction
International Nuclear Information System (INIS)
Kishida, Kuniharu
1997-01-01
Identification of transfer function matrices in a feedback system is discussed by using the singular value decomposition of Hankel matrix from the viewpoint of inverse problems. A method of model reduction is considered, and selection criteria are proposed for identification of them. Transformation formula between open loop and closed loop transfer function matrices are determined from the feedback loop structure, and they are needed for identification of open loop transfer function matrices under such a condition where the feedback system is in a minimum phase. Though the identifiability of open loop transfer function matrices can be examined in the framework of innovation model equivalent to the feedback system, there are pole-zero cancellations in the identification of them. The method to reduce a model order of an open loop transfer function is discussed by using the singular value decomposition of a gramian given by the open loop transfer function with higher degree. To check reliability of the present algorithm, a simulation study is performed for an example. (author)
Energy Technology Data Exchange (ETDEWEB)
He, Zhixia; Zhang, Liang; Saha, Kaushik; Som, Sibendu; Duan, Lian; Wang, Qian
2017-12-01
The super high fuel injection pressure and micro size of nozzle orifice has been an important development trend for the fuel injection system. Accordingly, cavitation transient process, fuel compressibility, amount of noncondensable gas in the fuel and cavitation erosion have attracted more attention. Based on the fact of cavitation in itself is a kind of thermodynamic phase change process, this paper takes the perspective of the cavitation phase change mass transfer process to analyze above mentioned phenomenon. The two-phase cavitating turbulent flow simulations with VOF approach coupled with HRM cavitation model and U-RANS of standard k-ε turbulence model were performed for investigations of cavitation phase change mass transfer process. It is concluded the mass transfer time scale coefficient in the Homogenous Relaxation Model (HRM) representing mass transfer rate should tend to be as small as possible in a condition that ensured the solver stable. At very fast mass transfer rate, the phase change occurs at very thin interface between liquid and vapor phase and condensation occurs more focused and then will contribute predictably to a more serious cavitation erosion. Both the initial non-condensable gas in fuel and the fuel compressibility can accelerate the cavitation mass transfer process.
Experimental study of interfacial shear stress for an analogy model of evaporative heat transfer
International Nuclear Information System (INIS)
Kwon, Hyuk; Park, GoonCherl; Min, ByungJoo
2008-01-01
In this study, we conducted measurements of an evaporative interfacial shear stress in a passive containment cooling system (PCCS). An interfacial shear stress for a counter-current flow was measured from a momentum balance equation and the interfacial friction factor for evaporation was evaluated by using experimental data. A model for the evaporative heat transfer coefficient of a vertical evaporative flat surface was developed based on an analogy between heat and momentum transfer. It was found that the interfacial shear stress increases with the Jacob number, which incorporates the evaporation rate, and the air and water Reynolds numbers. The relationship between the evaporative heat transfer and the interfacial shear stress was evaluated by using the experimental results. This relationship was used to develop a model for an evaporative heat transfer coefficient by using an analogy between heat and mass transfer. The prediction of this model were found to be in good agreement with the experimental data obtained for evaporative heat transfer by Kang and Park. (author)
Radiative transfer modeling of upwelling light field in coastal waters
International Nuclear Information System (INIS)
Sundarabalan, Balasubramanian; Shanmugam, Palanisamy; Manjusha, Sadasivan
2013-01-01
Numerical simulations of the radiance distribution in coastal waters are a complex problem, but playing a growingly important role in optical oceanography and remote sensing applications. The present study attempts to modify the Inherent Optical Properties (IOPs) to allow the phase function to vary with depth, and the bottom boundary to take into account a sloping/irregular surface and the effective reflectance of the bottom material. It then uses the Hydrolight numerical model to compute Apparent Optical Properties (AOPs) for modified IOPs and bottom boundary conditions compared to the default values available in the standard Hydrolight model. The comparison of the profiles of upwelling radiance simulated with depth-dependent IOPs as well as modified bottom boundary conditions for realistic cases of coastal waters off Point Calimere of southern India shows a good match between the simulated and measured upwelling radiance profile data, whereas there is a significant drift between the upwelling radiances simulated from the standard Hydrolight model (with default values) and measured data. Further comparison for different solar zenith conditions at a coastal station indicates that the upwelling radiances simulated with the depth-dependent IOPs and modified bottom boundary conditions are in good agreement with the measured radiance profile data. This simulation captures significant changes in the upwelling radiance field influenced by the bottom boundary layer as well. These results clearly emphasize the importance of using realistic depth-dependent IOPs as well as bottom boundary conditions as input to Hydrolight in order to obtain more accurate AOPs in coastal waters. -- Highlights: ► RT model with depth-dependent IOPs and modified bottom boundary conditions provides accurate L u profiles in coastal waters. ► The modified phase function model will be useful for coastal waters. ► An inter-comparison with measured upwelling radiance gives merits of the
3D modelling of coupled mass and heat transfer of a convection-oven roasting process
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu; Adler-Nissen, Jens; Gernaey, Krist
2013-01-01
A 3D mathematical model of coupled heat and mass transfer describing oven roasting of meat has been developed from first principles. The proposed mechanism for the mass transfer of water is modified and based on a critical literature review of the effect of heat on meat. The model equations...... are based on a conservation of mass and energy, coupled through Darcy's equations of porous media - the water flow is mainly pressure-driven. The developed model together with theoretical and experimental assessments were used to explain the heat and water transport and the effect of the change...
Application of New Electrolyte Model to Phase Transfer Catalyst (PTC) Systems
DEFF Research Database (Denmark)
Hyung Kim, Sun; Anantpinijwatna, Amata; Kang, Jeong Won
2015-01-01
Abstract Phase transfer catalyst (PTC) is used to transfer the desirable active form of an anion from the aqueous phase to organic phase where the reaction occurs. One of major challenges for process design of the PTC system is to establish a reliable thermodynamic model capable of describing pha...... in PTC systems, thereby, extending the application range of the PTC-system model. The solubility of PTC in organic solvents, which is a key factor for strategy of PTC and solvent selection, has been calculated using the e-NRTL-SAC model....
Modelling transfer of Salmonella Typhimurium DT104 during simulation of grinding of pork
DEFF Research Database (Denmark)
Møller, Cleide; Nauta, Maarten; Christensen, B. B.
2012-01-01
Aims: The aim of this study was to develop a model to predict cross‐contamination of Salmonella during grinding of pork. Methods and Results: Transfer rates of Salmonella were measured in three experiments, where between 10 and 20 kg meat was ground into 200‐g portions. In each experiment, five...... during a small‐scale grinding process. It was, therefore, hypothesized that transfer occurred from two environmental matrices inside the grinder and a model was developed. The developed model satisfactorily predicted the observed concentrations of Salmonella during its cross‐contamination in the grinding...
International Nuclear Information System (INIS)
Attwood, C.; Barraclough, I.; Brown, J.
1998-06-01
There is a wide range of models available at NRPB to predict the transfer of radionuclides through the environment. Such models form an essential part of assessments of the radiological impact of releases of radionuclides into the environment. These models cover: the atmosphere; the aquatic environment; the geosphere; the terrestrial environment including foodchains. It is important that the models used for radiological impact assessments are robust, reliable and suitable for the assessment being undertaken. During model development it is, therefore, important that the model is both verified and validated. Verification of a model involves ensuring that it has been implemented correctly, while validation consists of demonstrating that the model is an adequate representation of the real environment. The extent to which a model can be verified depends on its complexity and whether similar models exist. For relatively simple models verification is straightforward, but for more complex models verification has to form part of the development, coding and testing of the model within quality assurance procedures. Validation of models should ideally consist of comparisons between the results of the models and experimental or environmental measurement data that were not used to develop the model. This is more straightforward for some models than for others depending on the quantity and type of data available. Validation becomes increasingly difficult for models which are intended to predict environmental transfer at long times or at great distances. It is, therefore, necessary to adopt qualitative validation techniques to ensure that the model is an adequate representation of the real environment. This report summarises the models used at NRPB to predict the transfer of radionuclides through the environment as part of a radiological impact assessment. It outlines the work carried out to verify and validate the models. The majority of these models are not currently available
Sky-Radiance Models for Monte Carlo Radiative Transfer Applications
Santos, I.; Dalimonte, D.; Santos, J. P.
2012-04-01
Photon-tracing can be initialized through sky-radiance (Lsky) distribution models when executing Monte Carlo simulations for ocean color studies. To be effective, the Lsky model should: 1) properly represent sky-radiance features of interest; 2) require low computing time; and 3) depend on a limited number of input parameters. The present study verifies the satisfiability of these prerequisite by comparing results from different Lsky formulations. Specifically, two Lsky models were considered as reference cases because of their different approach among solutions presented in the literature. The first model, developed by the Harrisson and Coombes (HC), is based on a parametric expression where the sun geometry is the unique input. The HC model is one of the sky-radiance analytical distribution applied in state-of-art simulations for ocean optics. The coefficients of the HC model were set upon broad-band field measurements and the result is a model that requires a few implementation steps. The second model, implemented by Zibordi and Voss (ZV), is based on physical expressions that accounts for the optical thickness of permanent gases, aerosol, ozone and water vapour at specific wavelengths. Inter-comparisons between normalized ^LskyZV and ^LskyHC (i.e., with unitary scalar irradiance) are discussed by means of individual polar maps and percent difference between sky-radiance distributions. Sky-radiance cross-sections are presented as well. Considered cases include different sun zenith values and wavelengths (i.e., λ=413, 490 and 665 nm, corresponding to selected center-bands of the MEdium Resolution Imaging Spectrometer MERIS). Results have shown a significant convergence between ^LskyHC and ^LskyZV at 665 nm. Differences between models increase with the sun zenith and mostly with wavelength. For Instance, relative differences up to 50% between ^ L skyHC and ^ LskyZV can be observed in the antisolar region for λ=665 nm and θ*=45°. The effects of these
Modeling of heat transfer in wall-cooled tubular reactors
Koning, G.W.; Westerterp, K.R.
1999-01-01
In a pilot scale wall-cooled tubular reactor, temperature profiles have been measured with and without reaction. As a model reaction oxidation of carbon monoxide in air over a copper chromite catalyst has been used. The kinetics of this reaction have been determined separately in two kinetic
Heat transfer modelling of first walls subject to plasma disruption
International Nuclear Information System (INIS)
Fillo, J.A.; Makowitz, H.
1981-01-01
A brief description of the plasma disruption problem and potential thermal consequences to the first wall is given. Thermal models reviewed include: a) melting of a solid with melt layer in place; b) melting of a solid with complete removal of melt (ablation); c) melting/vaporization of a solid; and d) vaporization of a solid but no phase change affecting the temperature profile
DEFF Research Database (Denmark)
Jabbari, Masoud; Hosseinzadeh, Azin
2013-01-01
In the present study the numerical model in 2D is used to study the solidification bahavior of the gray cast iron. The conventional heat transfer is coupled with the proposed micro-model to predict the amount of different phases, i.e. total austenite (c) phase, graphite (G) and cementite (C...
Bond, Barbara J.; Peterson, David L.
1999-01-01
This project was a collaborative effort by researchers at ARC, OSU and the University of Arizona. The goal was to use a dataset obtained from a previous study to "empirically validate a new canopy radiative-transfer model (SART) which incorporates a recently-developed leaf-level model (LEAFMOD)". The document includes a short research summary.
Effects of creating video-based modeling examples on learning and transfer
Hoogerheide, Vincent; Loyens, Sofie M M; van Gog, Tamara
2014-01-01
Two experiments investigated whether acting as a peer model for a video-based modeling example, which entails studying a text with the intention to explain it to others and then actually explaining it on video, would foster learning and transfer. In both experiments, novices were instructed to study
Modelling Wireless Power Transfer Using an Array of Tesla Coils
Pierson, Casey Thomas
Wireless power transmission, or WPT, is a well-demonstrated property in electrical science and physics. Coil-and-wave transmission (CWT) consists of two Tesla coils, one powered by a controlled voltage source v src and one connected across a generic load Z 0 , at a mid- to long range distance apart with spherical capacitors at each of their top loads. The literature on the different methods of WPT varies widely, but research of CWT is sparse, lacking especially in the area of computer simulation. Recently, a physical experiment was conducted by Marzolf et al. in [1], and yielded surprising resonant frequencies in the high frequency range. The goal of this research is to answer the question of whether these reosnant frequencies originate in unexplained field effects or in non-ideal circuit behavior, and establish a formal model to indicate at what frequencies the resonant peaks occur as a first approximation. By carefully constructing a simulation of the most geometrically simple, power efficient design in the work of Marzolf et al. using the scientific software Octave, we investigate these frequencies computationally: first, an ideal scenario that has no flux leakage or exterior losses is modelled mathematically and simulated, and then, a non-ideal scenario that accounts for losses in the coils and surroundings is modelled mathematically and simulated. Both models utilize a simple formula for spherical capacitance for the top loads. After running these simulations through detailed sampling up to 4 MHz, the ideal model could not account for the resonant peaks, while the non-ideal model indicated the resonant peaks near the exact frequency ranges that were observed. An unexpected characteristic of these results was that coupling coefficients between the coils of the transmitter and receiver played a noticeable part in the indication of resonant peaks. This demonstrates that unknown field effects are not the primary driver of resonance in the ideal or non
Nonlinear transfer of elements from soil to plants: impact on radioecological modeling
Energy Technology Data Exchange (ETDEWEB)
Tuovinen, Tiina S.; Kolehmainen, Mikko; Roivainen, Paeivi; Kumlin, Timo; Makkonen, Sari; Holopainen, Toini; Juutilainen, Jukka [University of Eastern Finland, Department of Environmental and Biological Sciences, P.O. Box 1627, Kuopio (Finland)
2016-08-15
In radioecology, transfer of radionuclides from soil to plants is typically described by a concentration ratio (CR), which assumes linearity of transfer with soil concentration. Nonlinear uptake is evidenced in many studies, but it is unclear how it should be taken into account in radioecological modeling. In this study, a conventional CR-based linear model, a nonlinear model derived from observed uptake into plants, and a new simple model based on the observation that nonlinear uptake leads to a practically constant concentration in plant tissues are compared. The three models were used to predict transfer of {sup 234}U, {sup 59}Ni and {sup 210}Pb into spruce needles. The predictions of the nonlinear and the new model were essentially similar. In contrast, plant radionuclide concentration was underestimated by the linear model when the total element concentration in soil was relatively low, but within the range commonly observed in nature. It is concluded that the linear modeling could easily be replaced by a new approach that more realistically reflects the true processes involved in the uptake of elements into plants. The new modeling approach does not increase the complexity of modeling in comparison with CR-based linear models, and data needed for model parameters (element concentrations) are widely available. (orig.)
Heat transfer models for fusion blanket first walls
International Nuclear Information System (INIS)
Fillo, J.A.
1977-01-01
In the development of magnetically confined fusion reactors, the ability to cool the first wall, i.e., the first material surface interfacing the plasma, appears to be a critical factor involved in establishing the wall load limit. In order to understand the thermal behavior of the first wall time-dependent, one-dimensional heat conduction models are reviewed with differing modes of heat extraction and cooling
System modeling of spent fuel transfers at EBR-II
International Nuclear Information System (INIS)
Imel, G.R.; Houshyar, A.
1994-01-01
The unloading of spent fuel from the Experimental Breeder Reactor-II (EBR-II) for interim storage and subsequent processing in the Fuel Cycle Facility (FCF) is a multi-stage process, involving complex operations at a minimum of four different facilities at the Argonne National Laboratory-West (ANL-W) site. Each stage typically has complicated handling and/or cooling equipment that must be periodically maintained, leading to both planned and unplanned downtime. A program was initiated in October, 1993 to replace the 330 depleted uranium blanket subassemblies (S/As) with stainless steel reflectors. Routine operation of the reactor for fuels performance and materials testing occurred simultaneously in FY 1994 with the blanket unloading. In the summer of 1994, Congress dictated the October 1, 1994 shutdown of EBR-2. Consequently, all blanket S/As and fueled drivers will be removed from the reactor tank and replaced with stainless steel assemblies (which are needed to maintain a precise configuration within the grid so that the under sodium fuel handling equipment can function). A system modeling effort was conducted to determine the means to achieve the objective for the blanket and fuel unloading program, which under the current plan requires complete unloading of the primary tank of all fueled assemblies in 2 1/2 years. A simulation model of the fuel handling system at ANL-W was developed and used to analyze different unloading scenarios; the model has provided valuable information about required resources and modifications to equipment and procedures. This paper reports the results of this modeling effort
Modeling the factors that influence knowledge transfer in mergers and acquisitions
Institute of Scientific and Technical Information of China (English)
YU Haiyan; LIANG Zhanping
2010-01-01
This paper constructs a model on the factors that influence knowledge transfer in mergers and acquisitions (M&A) and validates it via questionnaire surveys.Using 125 valid collected questionnaires,multiple linear regression analysis and hierarchical regression analysis showed that five out of the ten factors had a positive effect on knowledge transfer effect.The ranking of factor importance,from high to low,was knowledge explicitness,relationship quality,learning intent,advanced transfer activities,and learning capability,which is fairly consistent with positive factors observed in other interorganizational knowledge transfer researches.Our results also showed that one of the control variables (size of acquired firm) had neither a direct or indirect effect on knowledge transfer in M&A.Additionally,our research found that knowledge distance and degree of M&A integration had a positive influence on knowledge transfer effect at the early stage after M&A,but had a negative influence at the late stage.Based on this research,several suggestions for knowledge transfer in M&A are proposed.
Modeling the factors that influence knowledge transfer in mergers and acquisitions
Institute of Scientific and Technical Information of China (English)
YU; Haiyan; LIANG; Zhanping
2010-01-01
This paper constructs a model on the factors that influence knowledge transfer in mergers and acquisitions(M&A)and validates it via questionnaire surveys.Using 125valid collected questionnaires,multiple linear regression analysis and hierarchical regression analysis showed that five out of the ten factors had a positive effect on knowledge transfer effect.The ranking of factor importance,from high to low,was knowledge explicitness,relationship quality,learning intent,advanced transfer activities,and learning capability,which is fairly consistent with positive factors observed in other interorganizational knowledge transfer researches.Our results also showed that one of the control variables(size of acquired firm)had neither a direct or indirect effect on knowledge transfer in M&A.Additionally,our research found that knowledge distance and degree of M&A integration had a positive influence on knowledge transfer effect at the early stage after M&A,but had a negative influence at the late stage.Based on this research,several suggestions for knowledge transfer in M&A are proposed.
A mass transfer model of ammonia volatilisation from anaerobic digestate
International Nuclear Information System (INIS)
Whelan, M.J.; Everitt, T.; Villa, R.
2010-01-01
Anaerobic digestion (AD) is becoming increasingly popular for treating organic waste. The methane produced can be burned to generate electricity and the digestate, which is high in mineral nitrogen, can be used as a fertiliser. In this paper we evaluate potential losses of ammonia via volatilisation from food waste anaerobic digestate using a closed chamber system equipped with a sulphuric acid trap. Ammonia losses represent a pollution source and, over long periods could reduce the agronomic value of the digestate. Observed ammonia losses from the experimental system were linear with time. A simple non-steady-state partitioning model was developed to represent the process. After calibration, the model was able to describe the behaviour of ammonia in the digestate and in the trap very well. The average rate of volatilisation was approximately 5.2 g N m -2 week -1 . The model was used to extrapolate the findings of the laboratory study to a number of AD storage scenarios. The simulations highlight that open storage of digestate could result in significant losses of ammonia to the atmosphere. Losses are predicted to be relatively minor from covered facilities, particularly if depth to surface area ratio is high.
A forced convective heat transfer model for two-phase hydrogen systems
International Nuclear Information System (INIS)
Pasch, J.; Anghaie, S.
2007-01-01
A consistent event in the use of hydrogen in nuclear thermal propulsion is film boiling, in which the wall heat is so large that liquid can not exist at the wall. Instead, vapor interfaces with the wall and liquid flows in the core of the duct. To better understand heat transfer under these conditions, a select set of hydrogen test data from these conditions are analyzed. This paper presents the results of an extensive literature search for film boiling heat transfer models. A representative cross-section of these models is then applied to the data. The heat transfer coefficient data were found difficult to predict and highly dependent upon the flow regime. Pre-critical heat flux correlations completely fail to predict the heat transfer of inverted film boiling conditions. Pool boiling models for inverted film boiling also are inappropriate. Current force convection models for inverted film boiling, while far better than the previous two classes of models, still generate large predictive errors. It is recommended that for the inverted annular film boiling flow regime the modified equilibrium bulk Dittus-Boelter model be used. For agitated inverted annular film boiling and dispersed film boiling regimes associated with positive equilibrium qualities, the Hendricks model should be used. (A.C.)
A mechanistic model of heat transfer for gas-liquid flow in vertical wellbore annuli.
Yin, Bang-Tang; Li, Xiang-Fang; Liu, Gang
2018-01-01
The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow conditions which have significant effects on liquid holdup, pressure gradient and heat transfer. Gas-liquid two-phase flow in an annulus can be found in a variety of practical situations. In high rate oil and gas production, it may be beneficial to flow fluids vertically through the annulus configuration between well tubing and casing. The flow patterns in annuli are different from pipe flow. There are both casing and tubing liquid films in slug flow and annular flow in the annulus. Multiphase heat transfer depends on the hydrodynamic behavior of the flow. There are very limited research results that can be found in the open literature for multiphase heat transfer in wellbore annuli. A mechanistic model of multiphase heat transfer is developed for different flow patterns of upward gas-liquid flow in vertical annuli. The required local flow parameters are predicted by use of the hydraulic model of steady-state multiphase flow in wellbore annuli recently developed by Yin et al. The modified heat-transfer model for single gas or liquid flow is verified by comparison with Manabe's experimental results. For different flow patterns, it is compared with modified unified Zhang et al. model based on representative diameters.
International Nuclear Information System (INIS)
Zach, R.
1980-09-01
Transfer coefficients have become virtually indispensible in the study of the fate of radioisotopes released from nuclear installations. These coefficients are used in equilibrium assessment models where they specify the degree of transfer in food chains of individual radioisotopes from soil to plant products and from feed or forage and drinking water to animal products and ultimately to man. Information on transfer coefficients for terrestrial food chain models is very piecemeal and occurs in a wide variety of journals and reports. To enable us to choose or determine suitable values for assessments, we have addressed the following aspects of transfer coefficients on a very broad scale: (1) definitions, (2) equilibrium assumption, which stipulates that transfer coefficients be restricted to equilibrium or steady rate conditions, (3) assumption of linearity, that is the idea that radioisotope concentrations in food products increase linearly with contamination levels in the soil or animal feed, (4) methods of determination, (5) variability, (6) generic versus site-specific values, (7) statistical aspects, (8) use, (9) sources of currently used values, (10) criteria for revising values, (11) establishment and maintenance of files on transfer coefficients, and (12) future developments. (auth)
Directory of Open Access Journals (Sweden)
Balla Hyder H.
2015-01-01
Full Text Available Cu and Zn-water nanofluid is a suspension of the Cu and Zn nanoparticles with the size 50 nm in the water base fluid for different volume fractions to enhance its Thermophysical properties. The determination and measuring the enhancement of Thermophysical properties depends on many limitations. Nanoparticles were suspended in a base fluid to prepare a nanofluid. A coated transient hot wire apparatus was calibrated after the building of the all systems. The vibro-viscometer was used to measure the dynamic viscosity. The measured dynamic viscosity and thermal conductivity with all parameters affected on the measurements such as base fluids thermal conductivity, volume factions, and the temperatures of the base fluid were used as input to the Artificial Neural Fuzzy inference system to modeling both dynamic viscosity and thermal conductivity of the nanofluids. Then, the ANFIS modeling equations were used to calculate the enhancement in heat transfer coefficient using CFD software. The heat transfer coefficient was determined for flowing flow in a circular pipe at constant heat flux. It was found that the thermal conductivity of the nanofluid was highly affected by the volume fraction of nanoparticles. A comparison of the thermal conductivity ratio for different volume fractions was undertaken. The heat transfer coefficient of nanofluid was found to be higher than its base fluid. Comparisons of convective heat transfer coefficients for Cu and Zn nanofluids with the other correlation for the nanofluids heat transfer enhancement are presented. Moreover, the flow demonstrates anomalous enhancement in heat transfer nanofluids.
Modeling heat transfer in supercritical fluid using the lattice Boltzmann method.
Házi, Gábor; Márkus, Attila
2008-02-01
A lattice Boltzmann model has been developed to simulate heat transfer in supercritical fluids. A supercritical viscous fluid layer between two plates heated from the bottom has been studied. It is demonstrated that the model can be used to study heat transfer near the critical point where the so-called piston effect speeds up the transfer of heat and results in homogeneous heating in the bulk of the layer. We have also studied the onset of convection in a Rayleigh-Bénard configuration. It is shown that our model can well predict qualitatively the onset of convection near the critical point, where there is a crossover between the Rayleigh and Schwarzschild criteria.
Analytical modeling of heat transfer during the reflooding phase of the LOCA: the UCFLOOD code
International Nuclear Information System (INIS)
Yadigaroglu, G.; Arrieta, L.A.
1980-01-01
A mechanistic model of bottom-reflooding heat transfer is described. From the hydrodynamic point of view the flow channel is divided into a single-phase liquid region, a continuous-liquid two-phase region, and a dispersed-liquid region. The void fraction is obtained from drift flux models. The onset of liquid entrainment is determined using a criterion based on the instability of the liquid core in the inverted-annular flow regime. For heat transfer calculations, the channel is also divided into a number of regions. The heat transfer coefficients are functions of the local flow conditions. Quench front propagation is treated separately by a model including the effects of axial conduction. Good agreement of calculated and experimental results has been obtained
DEFF Research Database (Denmark)
Smed, Marie; Schultz, Carsten; Getz, Kenneth A.
2015-01-01
The collaboration with medical professionals in pharmaceutical clinical trials facilitates opportunities to gain valuable market information concerning product functionality issues, as well as issues related to market implementation and adoption. However, previous research on trial management lacks......’ information transfer ability, their methods of communicating, are included. The model is studied on a unique dataset of 395 medical site representatives by applying Rasch scale modeling to differentiate the stickiness of the heterogenic information issues. The results reveal that economic measures...... a differentiated perspective on the potential for information transfer from site to producer. An exploration of the variation in stickiness of information, and therefore the complexity of information transfer in clinical trials, is the main aim of this study. To further enrich the model of the dispersed sites...
Modeling and validating tritium transfer in a grassland ecosystem in response to {sup 3}H releases
Energy Technology Data Exchange (ETDEWEB)
Le Dizes, S. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS/LM2E, Centre de Cadarache, Saint-Paul-lez-Durance (France); Maro, D.; Rozet, M.; Hebert, D. [IRSN/PRP-ENV/SERIS/LRC, Cherbourg-Octeville (France)
2015-03-15
In this paper a radioecological model (TOCATTA) for tritium transfer in a grassland ecosystem developed on an hourly time-step basis is proposed and compared with the first data set obtained in the vicinity of the AREVA-NC reprocessing plant of La Hague (France). The TOCATTA model aims at simulating dynamics of tritium transfer in agricultural soil and plant ecosystems exposed to time-varying HTO concentrations in air water vapour and possibly in irrigation and rain water. In the present study, gaseous releases of tritium from the AREVA NC nuclear reprocessing plant in normal operation can be intense and intermittent over a period of less than 24 hours. A first comparison of the model predictions with the field data has shown that TOCATTA should be improved in terms of kinetics of tritium transfer.
Investigation of the fittest shear transfer model used to FEM analysis of RC structures
International Nuclear Information System (INIS)
Endo, Tatumi; Aoyagi, Masao; Endo, Takao
1988-01-01
In order to rationalize the design method of reinforced concrete (RC) structures in the nuclear power plant, the structural analysis, which is able to simulate the seismic behavior of RC structures, should be established. In this report, the investigation of shear transfer model at shear plane to be applied to FEM analysis is performed. Main conclusions obtained within the limit of the study are as follows. 1. Development of the shear transfer model at shear plane. 1) Two shear transfer models are developed to be used to the 2-dimensional nonlinear FEM analysis. 2) In one model suggested, reinforcements are modeled by plate elements and the nonlinearity of concrete surrounding reinforcement but the properties of bond-slip relation between concrete and reinforcements is also considered. 3) In another model, reinforcements are modeled by equivalent concrete properties, in which axial regidity and dowel effects of reinforcements are considered. 2. Verification of the suggested model. 1) It is confirmed that the computational results using the above-mentioned model could simulate the experimental ones fairly well. 2) Considering the application to the analysis of RC structures in the design, the model, in which reinforcement are modeled by equivalent concrete properties, is useful in view point of accuracy and simplicity. (author)
Quantum state transfer via a two-qubit Heisenberg XXZ spin model
Energy Technology Data Exchange (ETDEWEB)
Liu Jia; Zhang Guofeng [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Chen Ziyu [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)], E-mail: chenzy@buaa.edu.cn
2008-04-14
Transfer of quantum states through a two-qubit Heisenberg XXZ spin model with a nonuniform magnetic field b is investigated by means of quantum theory. The influences of b, the spin exchange coupling J and the effective transfer time T=Jt on the fidelity have been studied for some different initial states. Results show that fidelity of the transferred state is determined not only by J, T and b but also by the initial state of this quantum system. Ideal information transfer can be realized for some kinds of initial states. We also found that the interactions of the z-component J{sub z} and uniform magnetic field B do not have any contribution to the fidelity. These results may be useful for quantum information processing.
Quantum state transfer via a two-qubit Heisenberg XXZ spin model
International Nuclear Information System (INIS)
Liu Jia; Zhang Guofeng; Chen Ziyu
2008-01-01
Transfer of quantum states through a two-qubit Heisenberg XXZ spin model with a nonuniform magnetic field b is investigated by means of quantum theory. The influences of b, the spin exchange coupling J and the effective transfer time T=Jt on the fidelity have been studied for some different initial states. Results show that fidelity of the transferred state is determined not only by J, T and b but also by the initial state of this quantum system. Ideal information transfer can be realized for some kinds of initial states. We also found that the interactions of the z-component J z and uniform magnetic field B do not have any contribution to the fidelity. These results may be useful for quantum information processing
Radiation heat transfer model in a spent fuel pool by TRACE code
International Nuclear Information System (INIS)
Sanchez-Saez, F.; Carlos, S.; Villanueva, J.F.; Martorell, S.
2014-01-01
Nuclear policies have experienced an important change since Fukushima Daiichi nuclear plant accident and the safety of spent fuels has been in the spot issue among all the safety concerns. The work presented consists of the thermohydraulic simulation of spent fuel pool behavior after a loss of coolant throughout transfer channel with loss of cooling transient is produced. The simulation is done with the TRACE code. One of the most important variables that define the behavior of the pool is cladding temperature, which evolution depends on the heat emission. In this work convection and radiation heat transfer is considered. When both heat transfer models are considered, a clear delay in achieving the maximum peak cladding temperature (1477 K) is observed compared with the simulation in which only convection heat transfer is considered. (authors)
Model of tritium transfer into environment by the personnel of nuclear enterprises
International Nuclear Information System (INIS)
Batalin, J.; Krechetova, A.
2004-01-01
One of the ways of radionuclide transfer from a nuclear enterprise into an environment is analysed. This way of transfer is the transport of radionuclides by the personnel of a nuclear enterprise. During an active work in a nuclear enterprise the personnel accumulate radionuclides from the air of industrial premises. Accumulated radionuclides are released from the organism into an environment according to the effective period of half-draw. The main part of radionuclides is transferred from the organism of professional workers into an environment: first of all into the air and on furniture of their dwellings and later - into the organisms of their family members. In this way contamination of workers' dwellings and irradiation of their family members exceed the contamination through air and water. The model is confirmed as an example of tritium transfer from nuclear enterprises. (author)
Modeling transient heat transfer in nuclear waste repositories.
Yang, Shaw-Yang; Yeh, Hund-Der
2009-09-30
The heat of high-level nuclear waste may be generated and released from a canister at final disposal sites. The waste heat may affect the engineering properties of waste canisters, buffers, and backfill material in the emplacement tunnel and the host rock. This study addresses the problem of the heat generated from the waste canister and analyzes the heat distribution between the buffer and the host rock, which is considered as a radial two-layer heat flux problem. A conceptual model is first constructed for the heat conduction in a nuclear waste repository and then mathematical equations are formulated for modeling heat flow distribution at repository sites. The Laplace transforms are employed to develop a solution for the temperature distributions in the buffer and the host rock in the Laplace domain, which is numerically inverted to the time-domain solution using the modified Crump method. The transient temperature distributions for both the single- and multi-borehole cases are simulated in the hypothetical geological repositories of nuclear waste. The results show that the temperature distributions in the thermal field are significantly affected by the decay heat of the waste canister, the thermal properties of the buffer and the host rock, the disposal spacing, and the thickness of the host rock at a nuclear waste repository.
Energy Technology Data Exchange (ETDEWEB)
Lee, Youho, E-mail: euo@kaist.ac.kr; Lee, Jeong Ik, E-mail: jeongiklee@kaist.ac.kr; NO, Hee Cheon, E-mail: hcno@kaist.ac.kr
2016-03-15
Highlights: • Use of constant heat transfer coefficient for fracture analysis is not sound. • On-time heat transfer coefficient should be used for thermal fracture prediction. • ∼90% of the actual fracture stresses were predicted with the on-time transient h. • Thermal-hydraulic codes can be used to better predict brittle cladding fracture. • Effects of surface oxides on thermal shock fracture should be accounted by h. - Abstract: This study presents the importance of coherency in modeling thermal-hydraulics and mechanical behavior of a solid for an advanced prediction of cladding thermal shock fracture. In water quenching, a solid experiences dynamic heat transfer rate evolutions with phase changes of the fluid over a short quenching period. Yet, such a dynamic change of heat transfer rates has been overlooked in the analysis of thermal shock fracture. In this study, we are presenting quantitative evidence against the prevailing use of a constant heat transfer coefficient for thermal shock fracture analysis in water. We conclude that no single constant heat transfer could suffice to depict the actual stress evolution subject to dynamic fluid phase changes. Use of the surface temperature dependent heat transfer coefficient will remarkably increase predictability of thermal shock fracture of brittle materials. The presented results show a remarkable stress prediction improvement up to 80–90% of the actual stress with the use of the surface temperature dependent heat transfer coefficient. For thermal shock fracture analysis of brittle fuel cladding such as oxidized zirconium-based alloy or silicon carbide during LWR reflood, transient subchannel heat transfer coefficients obtained from a thermal-hydraulics code should be used as input for stress analysis. Such efforts will lead to a fundamental improvement in thermal shock fracture predictability over the current experimental empiricism for cladding fracture analysis during reflood.
Darmana, D.; Deen, N.G.; Kuipers, J.A.M.
2005-01-01
A 3D discrete bubble model is adopted to investigate complex behavior involving hydrodynamics, mass transfer and chemical reactions in a gas¿liquid bubble column reactor. In this model a continuum description is adopted for the liquid phase and additionally each individual bubble is tracked in a
Darmana, D.; Deen, N.G.; Kuipers, J.A.M.
2004-01-01
A 3D discrete bubble model is adopted to investigate complex behavior involving hydrodynamics, mass transfer and chemical reactions in a gas-liquid bubble column reactor. In this model a continuum description is adopted for the liquid phase and additionally each individual bubble is tracked in a
Darmana, D.; Deen, N.G.; Kuipers, J.A.M.
2005-01-01
A 3D discrete bubble model is adopted to investigate complex behavior involving hydrodynamics, mass transfer and chemical reactions in a gas–liquid bubble column reactor. In this model a continuum description is adopted for the liquid phase and additionally each individual bubble is tracked in a
DEFF Research Database (Denmark)
Jespersen, Henrik; Lindberg, Mattias F; Donia, Marco
2017-01-01
Immune checkpoint inhibitors and adoptive cell transfer (ACT) of autologous tumor-infiltrating T cells have shown durable responses in patients with melanoma. To study ACT and immunotherapies in a humanized model, we have developed PDXv2.0 - a melanoma PDX model where tumor cells and tumor...
International Nuclear Information System (INIS)
Tourniaire, B. . E-mail bruno.tourniaire@cea.fr
2006-01-01
The prediction of heat transfer between corium pool and concrete basemat is of particular significance in the framework of the study of PWR's severe accident. Heat transfer directly governs the ablation velocity of concrete in case of molten core concrete interaction (MCCI) and, consequently, the time delay when the reactor cavity may fail. From a restricted hydrodynamic point of view, this issue is related to heat transfer between a heated bubbling pool and a porous wall with gas injection. Several experimental studies have been performed with simulant materials and many correlations have been provided to address this issue. The comparisons of the results of these correlations with the measurements and their extrapolation to reactor materials show that strong discrepancies between the results of these models are obtained which probably means that some phenomena are not well taken into account. The main purpose of this paper is to present an alternative heat transfer model which was originally developed for chemical engineering applications (bubble columns) by Deckwer. A part of this work is devoted to the presentation of this model, which is based on a surface renewal assumption. Comparison of the results of this model with available experimental data in different systems are presented and discussed. These comparisons clearly show that this model can be used to deal with the particular problem of MCCI. The analyses also lead to enrich the original model by taking into account the thermal resistance of the wall: a new formulation of the Deckwer's correlation is finally proposed
International Nuclear Information System (INIS)
Basilevsky, M. V.; Mitina, E. A.; Odinokov, A. V.; Titov, S. V.
2013-01-01
The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ξ 0 =ℏω 0 /k B T where ω 0 is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (ξ 0 0 ≫ 1) temperature ranges. For the first (quasi-classical) kinetic regime, the Redfield approximation to the solution of the relaxation equation proved to be sufficient and efficient in practical applications. The study of the essentially quantum-mechanical low-temperature kinetic regime in its asymptotic limit requires the implementation of the exact relaxation equation. The coherent mechanism providing a non-vanishing reaction rate has been revealed when T→ 0. An accurate computational methodology for the cross-over kinetic regime needs a further elaboration. The original model of the hopping mechanism for electronic conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the kinetic regimes, which are usually postulated in the
Energy Technology Data Exchange (ETDEWEB)
Basilevsky, M. V.; Mitina, E. A. [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation); Odinokov, A. V. [Photochemistry Center, Russian Academy of Sciences, 7a, Novatorov ul., Moscow (Russian Federation); National Research Nuclear University “MEPhI,” 31, Kashirskoye shosse, Moscow (Russian Federation); Titov, S. V. [Karpov Institute of Physical Chemistry, 3-1/12, Building 6, Obuha pereulok, Moscow (Russian Federation)
2013-12-21
The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ξ{sub 0}=ℏω{sub 0}/k{sub B}T where ω{sub 0} is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (ξ{sub 0} < 1 − 3) and for low (ξ{sub 0}≫ 1) temperature ranges. For the first (quasi-classical) kinetic regime, the Redfield approximation to the solution of the relaxation equation proved to be sufficient and efficient in practical applications. The study of the essentially quantum-mechanical low-temperature kinetic regime in its asymptotic limit requires the implementation of the exact relaxation equation. The coherent mechanism providing a non-vanishing reaction rate has been revealed when T→ 0. An accurate computational methodology for the cross-over kinetic regime needs a further elaboration. The original model of the hopping mechanism for electronic conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the
Basilevsky, M V; Odinokov, A V; Titov, S V; Mitina, E A
2013-12-21
The algorithm for a theoretical calculation of transfer reaction rates for light quantum particles (i.e., the electron and H-atom transfers) in non-polar solid matrices is formulated and justified. The mechanism postulated involves a local mode (an either intra- or inter-molecular one) serving as a mediator which accomplishes the energy exchange between the reacting high-frequency quantum mode and the phonon modes belonging to the environment. This approach uses as a background the Fermi golden rule beyond the usually applied spin-boson approximation. The dynamical treatment rests on the one-dimensional version of the standard quantum relaxation equation for the reduced density matrix, which describes the frequency fluctuation spectrum for the local mode under consideration. The temperature dependence of a reaction rate is controlled by the dimensionless parameter ξ0 = ℏω0/k(B)T where ω0 is the frequency of the local mode and T is the temperature. The realization of the computational scheme is different for the high/intermediate (ξ0 regime, the Redfield approximation to the solution of the relaxation equation proved to be sufficient and efficient in practical applications. The study of the essentially quantum-mechanical low-temperature kinetic regime in its asymptotic limit requires the implementation of the exact relaxation equation. The coherent mechanism providing a non-vanishing reaction rate has been revealed when T → 0. An accurate computational methodology for the cross-over kinetic regime needs a further elaboration. The original model of the hopping mechanism for electronic conduction in photosensitive organic materials is considered, based on the above techniques. The electron transfer (ET) in active centers of such systems proceeds via local intra- and intermolecular modes. The active modes, as a rule, operate beyond the kinetic regimes, which are usually postulated in the existing theories of the ET. Our alternative dynamic ET model for local
Dynamic modeling of the cesium, strontium, and ruthenium transfer to grass and vegetables
International Nuclear Information System (INIS)
Renaud, P.; Real, J.; Maubert, H.; Roussel-Debet, S.
1999-01-01
From 1988 to 1993, the Nuclear Safety and Protection Institute (Institut de Protection et de Surete Nucleaire -- IPSN) conducted experimental programs focused on transfers to vegetation following accidental localized deposits of radioactive aerosols. In relation to vegetable crops (fruit, leaves, and root vegetables) and meadow grass these experiments have enabled a determination of the factors involved in the transfer of cesium, strontium, and ruthenium at successive harvests, or cuttings, in respect of various time lags after contamination. The dynamic modeling given by these results allows an evaluation of changes in the mass activity of vegetables and grass during the months following deposit. It constitutes part of the ASTRAL post-accident radioecology model
Continuous-variable protocol for oblivious transfer in the noisy-storage model
DEFF Research Database (Denmark)
Furrer, Fabian; Gehring, Tobias; Schaffner, Christian
2018-01-01
for oblivious transfer for optical continuous-variable systems, and prove its security in the noisy-storage model. This model allows us to establish security by sending more quantum signals than an attacker can reliably store during the protocol. The security proof is based on uncertainty relations which we...... derive for continuous-variable systems, that differ from the ones used in quantum key distribution. We experimentally demonstrate in a proof-of-principle experiment the proposed oblivious transfer protocol for various channel losses by using entangled two-mode squeezed states measured with balanced...
International Nuclear Information System (INIS)
Hallstadius, L.
1986-01-01
In many investigations concerning transport/exchange of matter in a natural system, e.g. functional studies in nuclear medicine, it is advantageous to relate experimental results to a model of the system. A new computer program is presented for the determination of linear transfer coefficients in a compartment model from experimentally observed time-compartment content curves. The program performs a least-square fit with the specified precision of the observed values as weight factors. The resulting uncertainty in the calculated transfer coefficients may also be assessed. The application of the program in nuclear medicine is demonstrated and discussed. (author)
Thermosyphon analysis of a repository: A simplified model for vapor flow and heat transfer
International Nuclear Information System (INIS)
Manteufel, R.D.; Powell, M.W.
1994-01-01
A simplified model is developed for thermally-driven buoyant gas flow in an unsaturated repository such as that anticipated at Yucca Mountain. Based on a simplified thermosyphon model, the strength of buoyant gas flow is related to key thermal-hydraulic parameters (e.g., bulk permeability and maximum repository temperature). The effects of buoyant gas flow on vapor flow and heat transport near the repository horizon are assessed, namely: (i) the strength of buoyant flow through the repository, (ii) the effect of buoyant flow on vapor transfer, and (iii) the effect of buoyant flow on heat transfer
International Nuclear Information System (INIS)
Bolstad, J.W.; Foster, R.D.; Gregory, W.S.
1983-01-01
A package of physical models simulating the heat transfer processes occurring between combustion gases and ducts in ventilation systems is described. The purpose of the numerical model is to predict how the combustion gas in a system heats up or cools down as it flows through the ducts in a ventilation system under fire conditions. The model treats a duct with (forced convection) combustion gases flowing on the inside and stagnant ambient air on the outside. The model is composed of five submodels of heat transfer processes along with a numerical solution procedure to evaluate them. Each of these quantities is evaluated independently using standard correlations based on experimental data. The details of the physical assumptions, simplifications, and ranges of applicability of the correlations are described. A typical application of this model to a full-scale fire test is discussed, and model predictions are compared with selected experimental data
Heat and mass transfer effects in a direct methanol fuel cell: A 1D model
Energy Technology Data Exchange (ETDEWEB)
Oliveira, V.B.; Falcao, D.S.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [INETI - Unidade de Electroquimica e Materiais, Paco do Lumiar, 22,1649-038 (Portugal)
2008-07-15
Models are a fundamental tool for the design process of fuel cells and fuel cell systems. In this work, a steady-state, one-dimensional model accounting for coupled heat and mass transfer, along with the electrochemical reactions occurring in the DMFC, is presented. The model output is the temperature profile through the cell and the water balance and methanol crossover between the anode and the cathode. The model predicts the correct trends for the influence of current density and methanol feed concentration on both methanol and water crossover. The model estimates the net water transfer coefficient through the membrane, {alpha}, a very important parameter to describe water management in the DMFC. Suitable operating ranges can be set up for different MEA structures maintaining the crossover of methanol and water within acceptable levels. The model is rapidly implemented and is therefore suitable for inclusion in real-time system level DMFC calculations. (author)
International Nuclear Information System (INIS)
Rozanov, V.V.; Dinter, T.; Rozanov, A.V.; Wolanin, A.; Bracher, A.; Burrows, J.P.
2017-01-01
SCIATRAN is a comprehensive software package which is designed to model radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared (0.18–40 μm). It accounts for multiple scattering processes, polarization, thermal emission and ocean–atmosphere coupling. The main goal of this paper is to present a recently developed version of SCIATRAN which takes into account accurately inelastic radiative processes in both the atmosphere and the ocean. In the scalar version of the coupled ocean–atmosphere radiative transfer solver presented by Rozanov et al. we have implemented the simulation of the rotational Raman scattering, vibrational Raman scattering, chlorophyll and colored dissolved organic matter fluorescence. In this paper we discuss and explain the numerical methods used in SCIATRAN to solve the scalar radiative transfer equation including trans-spectral processes, and demonstrate how some selected radiative transfer problems are solved using the SCIATRAN package. In addition we present selected comparisons of SCIATRAN simulations with those published benchmark results, independent radiative transfer models, and various measurements from satellite, ground-based, and ship-borne instruments. The extended SCIATRAN software package along with a detailed User's Guide is made available for scientists and students, who are undertaking their own research typically at universities, via the web page of the Institute of Environmental Physics (IUP), University of Bremen: (http://www.iup.physik.uni-bremen.de). - Highlights: • A new version of the software package SCIATRAN is presented. • Inelastic scattering in water and atmosphere is implemented in SCIATRAN. • Raman scattering and fluorescence can be included in radiative transfer calculations. • Comparisons to other radiative transfer models show excellent agreement. • Comparisons to observations show consistent results.
Modeling the scooping phenomenon for the heat transfer in liquid–gas horizontal slug flows
International Nuclear Information System (INIS)
Bassani, Carlos L.; Pereira, Fernando H.G.; Barbuto, Fausto A.A.; Morales, Rigoberto E.M.
2016-01-01
Highlights: • A low computational tool for heat transfer prediction on slug flows is presented. • The scooping phenomenon is modeled on a stationary approach. • The scooping phenomenon improved in 8% the heat transfer results. - Abstract: The heat transfer between the deep sea waters and the oil and gas mixtures flowing through production lines is a common situation in the petroleum industry. The optimum prediction of the liquid–gas flow parameters along those lines, when the intermittent flow pattern known as slug flow is dominant, has extreme importance in facilities' design. The mixture temperature drop caused by the colder sea waters, which can be regarded as an infinite medium with constant temperature, directly affects physical properties of the fluids such as the viscosity and specific mass. Gas expansion may also occur due to pressure and temperature gradients, thus changing the flow hydrodynamics. Finally, the temperature gradient affects the thermodynamic equilibrium between the phases, favoring wax deposition and thus increasing pressure drops or even blocking the production line. With those issues in mind, the present work proposes a stationary model to predict the mixture temperature distribution and the two-phase flow heat transfer coefficient based on the mass, momentum and energy conservation equations applied to different unit cell regions. The main contribution of the present work is the modeling of the thermal scooping phenomenon, i.e., the heat transfer between two adjacent unit cells due to the mass flux known as scooping. The model was implemented as a structured Fortran95 code with an upwind difference scheme. The results were compared to experimental data and presented good agreement. The analysis showed that the inclusion of the scooping phenomenon into the model resulted in an averaged 8% improvement in the temperature gradient calculation and heat transfer coefficient prediction for the flowing mixture.
Emde, Claudia; Barlakas, Vasileios; Cornet, Céline; Evans, Frank; Wang, Zhen; Labonotte, Laurent C.; Macke, Andreas; Mayer, Bernhard; Wendisch, Manfred
2018-04-01
Initially unpolarized solar radiation becomes polarized by scattering in the Earth's atmosphere. In particular molecular scattering (Rayleigh scattering) polarizes electromagnetic radiation, but also scattering of radiation at aerosols, cloud droplets (Mie scattering) and ice crystals polarizes. Each atmospheric constituent produces a characteristic polarization signal, thus spectro-polarimetric measurements are frequently employed for remote sensing of aerosol and cloud properties. Retrieval algorithms require efficient radiative transfer models. Usually, these apply the plane-parallel approximation (PPA), assuming that the atmosphere consists of horizontally homogeneous layers. This allows to solve the vector radiative transfer equation (VRTE) efficiently. For remote sensing applications, the radiance is considered constant over the instantaneous field-of-view of the instrument and each sensor element is treated independently in plane-parallel approximation, neglecting horizontal radiation transport between adjacent pixels (Independent Pixel Approximation, IPA). In order to estimate the errors due to the IPA approximation, three-dimensional (3D) vector radiative transfer models are required. So far, only a few such models exist. Therefore, the International Polarized Radiative Transfer (IPRT) working group of the International Radiation Commission (IRC) has initiated a model intercomparison project in order to provide benchmark results for polarized radiative transfer. The group has already performed an intercomparison for one-dimensional (1D) multi-layer test cases [phase A, 1]. This paper presents the continuation of the intercomparison project (phase B) for 2D and 3D test cases: a step cloud, a cubic cloud, and a more realistic scenario including a 3D cloud field generated by a Large Eddy Simulation (LES) model and typical background aerosols. The commonly established benchmark results for 3D polarized radiative transfer are available at the IPRT website (http
Saito, L.; Johnson, B.M.; Bartholow, J.; Hanna, R.B.
2001-01-01
We investigated the effects on the reservoir food web of a new temperature control device (TCD) on the dam at Shasta Lake, California. We followed a linked modeling approach that used a specialized reservoir water quality model to forecast operation-induced changes in phytoplankton production. A food web–energy transfer model was also applied to propagate predicted changes in phytoplankton up through the food web to the predators and sport fishes of interest. The food web–energy transfer model employed a 10% trophic transfer efficiency through a food web that was mapped using carbon and nitrogen stable isotope analysis. Stable isotope analysis provided an efficient and comprehensive means of estimating the structure of the reservoir's food web with minimal sampling and background data. We used an optimization procedure to estimate the diet proportions of all food web components simultaneously from their isotopic signatures. Some consumers were estimated to be much more sensitive than others to perturbations to phytoplankton supply. The linked modeling approach demonstrated that interdisciplinary efforts enhance the value of information obtained from studies of managed ecosystems. The approach exploited the strengths of engineering and ecological modeling methods to address concerns that neither of the models could have addressed alone: (a) the water quality model could not have addressed quantitatively the possible impacts to fish, and (b) the food web model could not have examined how phytoplankton availability might change due to reservoir operations.
Directory of Open Access Journals (Sweden)
Mahood Hameed B.
2016-01-01
Full Text Available An analytical model for the convective heat transfer coefficient and the two-phase bubble size of a three-phase direct contact heat exchanger was developed. Until the present, there has only been a theoretical model available that deals with a single two-phase bubble and a bubble train condensation in an immiscible liquid. However, to understand the actual heat transfer process within the three-phase direct contact condenser, characteristic models are required. A quasi - steady energy equation in a spherical coordinate system with a potential flow assumption and a cell model configuration has been simplified and solved analytically. The convective heat transfer in terms of Nu number has been derived, and it was found to be a function to Pe number and a system void fraction. In addition, the two-phase bubble size relates to the system void fraction and has been developed by solving a simple energy balance equation and using the derived convective heat transfer coefficient expression. Furthermore, the model correlates well with previous experimental data and theoretical results.
A general model for the transfer of radioactive materials in terrestrial food chains
International Nuclear Information System (INIS)
Simmonds, J.R.; Linsley, G.S.; Jones, J.A.
1979-09-01
A general methodology for modelling the transfer of radionuclides in the food chains to man is described. The models are dynamic in nature so that the long-term time dependence of processes in environmental materials can be represented, for example, the build-up of activity concentrations in soils during continuous deposition from atmosphere. Modules for radionuclide migration are described in well-mixed (cultivated) soil and undisturbed soil (pasture). The methods by which the transfer coefficients used in plant and animal modules are derived are also given. The foodstuffs considered are those derived from green vegetables, grain, and root vegetables together with meat and liver products from the cow and sheep and cow dairy products. The dynamic model permits the time dependence of food chain transfer processes to be represented for different land contamination scenarios; in particular, the model can be adapted to represent behaviour following a single deposit. Using the sensitivity of results to the variation of transfer parameters the model can be used to determine the parts of the food chain where improved data would be most effective in increasing the reliability of radiological assessments; a worked example is given. (author)
Energy Technology Data Exchange (ETDEWEB)
Hu, Rui, E-mail: rhu@anl.gov; Yu, Yiqi
2016-11-15
Highlights: • Developed a computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors. • Applied fully-coupled JFNK solution scheme to avoid the operator-splitting errors. • The accuracy and efficiency of the method is confirmed with a 7-assembly test problem. • The effects of different spatial discretization schemes are investigated and compared to the RANS-based CFD simulations. - Abstract: For efficient and accurate temperature predictions of sodium fast reactor structures, a 3-D full-core conjugate heat transfer modeling capability is developed for an advanced system analysis tool, SAM. The hexagon lattice core is modeled with 1-D parallel channels representing the subassembly flow, and 2-D duct walls and inter-assembly gaps. The six sides of the hexagon duct wall and near-wall coolant region are modeled separately to account for different temperatures and heat transfer between coolant flow and each side of the duct wall. The Jacobian Free Newton Krylov (JFNK) solution method is applied to solve the fluid and solid field simultaneously in a fully coupled fashion. The 3-D full-core conjugate heat transfer modeling capability in SAM has been demonstrated by a verification test problem with 7 fuel assemblies in a hexagon lattice layout. Additionally, the SAM simulation results are compared with RANS-based CFD simulations. Very good agreements have been achieved between the results of the two approaches.
Heat and mass transfer models to understand the drying mechanisms of a porous substrate.
Songok, Joel; Bousfield, Douglas W; Gane, Patrick A C; Toivakka, Martti
2016-02-01
While drying of paper and paper coatings is expensive, with significant energy requirements, the rate controlling mechanisms are not currently fully understood. Two two-dimensional models are used as a first approximation to predict the heat transfer during hot air drying and to evaluate the role of various parameters on the drying rates of porous coatings. The models help determine the structural limiting factors during the drying process, while applying for the first time the recently known values of coating thermal diffusivity. The results indicate that the thermal conductivity of the coating structure is not the controlling factor, but the drying rate is rather determined by the thermal transfer process at the structure surface. This underlines the need for ensuring an efficient thermal transfer from hot air to coating surface during drying, before considering further measures to increase the thermal conductivity of porous coatings.
Energy Technology Data Exchange (ETDEWEB)
Naruse, Makoto, E-mail: naruse@nict.go.jp [Photonic Network Research Institute, National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795 (Japan); Nanophotonics Research Center, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Akahane, Kouichi; Yamamoto, Naokatsu [Photonic Network Research Institute, National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei, Tokyo 184-8795 (Japan); Holmström, Petter [Laboratory of Photonics and Microwave Engineering, Royal Institute of Technology (KTH), SE-164 40 Kista (Sweden); Thylén, Lars [Laboratory of Photonics and Microwave Engineering, Royal Institute of Technology (KTH), SE-164 40 Kista (Sweden); Hewlett-Packard Laboratories, Palo Alto, California 94304 (United States); Huant, Serge [Institut Néel, CNRS and Université Joseph Fourier, 25 rue des Martyrs BP 166, 38042 Grenoble Cedex 9 (France); Ohtsu, Motoichi [Nanophotonics Research Center, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)
2014-04-21
We theoretically and experimentally demonstrate energy transfer mediated by optical near-field interactions in a multi-layer InAs quantum dot (QD) structure composed of a single layer of larger dots and N layers of smaller ones. We construct a stochastic model in which optical near-field interactions that follow a Yukawa potential, QD size fluctuations, and temperature-dependent energy level broadening are unified, enabling us to examine device-architecture-dependent energy transfer efficiencies. The model results are consistent with the experiments. This study provides an insight into optical energy transfer involving inherent disorders in materials and paves the way to systematic design principles of nanophotonic devices that will allow optimized performance and the realization of designated functions.
International Nuclear Information System (INIS)
Naruse, Makoto; Akahane, Kouichi; Yamamoto, Naokatsu; Holmström, Petter; Thylén, Lars; Huant, Serge; Ohtsu, Motoichi
2014-01-01
We theoretically and experimentally demonstrate energy transfer mediated by optical near-field interactions in a multi-layer InAs quantum dot (QD) structure composed of a single layer of larger dots and N layers of smaller ones. We construct a stochastic model in which optical near-field interactions that follow a Yukawa potential, QD size fluctuations, and temperature-dependent energy level broadening are unified, enabling us to examine device-architecture-dependent energy transfer efficiencies. The model results are consistent with the experiments. This study provides an insight into optical energy transfer involving inherent disorders in materials and paves the way to systematic design principles of nanophotonic devices that will allow optimized performance and the realization of designated functions
One-neutron transfer reaction: a toy model in one dimension
International Nuclear Information System (INIS)
G. Galilei, Padova, Italy INFN, Sezione di Padova, Padova (Italy))" data-affiliation=" (Dipartimento di Fisica e Astronomia G. Galilei, Padova, Italy INFN, Sezione di Padova, Padova (Italy))" >Moschini, L
2014-01-01
A simple 1D toy model to study one-neutron transfer reactions is developed. It is based on the solution of the time dependent Schroedinger equation for a particle initially bound by a fixed potential well, perturbed by a second moving potential, which accounts for the second partner of the reaction. At the end of the time evolution it is possible to evaluate the probability of the transfer of the particle from a potential to the other, as well as the transfer to continuum states in the case of weakly-bound systems. Although rather simple, the model accounts for most of the physical characteristics of these kind of reactions: such as the existence of an optimum Q-value and the dependence on the parameters defining the relative motion of the two potentials
Analytical model for bottom reflooding heat transfer in light water reactors (the UCFLOOD code)
International Nuclear Information System (INIS)
Arrieta, L.; Yadigaroglu, G.
1978-08-01
The UCFLOOD code is based on mechanistic models developed to analyze bottom reflooding of a single flow channel and its associated fuel rod, or a tubular test section with internal flow. From the hydrodynamic point of view the flow channel is divided into a single-phase liquid region, a continuous-liquid two-phase region, and a dispersed-liquid region. The void fraction is obtained from drift flux models. For heat transfer calculations, the channel is divided into regions of single-phase-liquid heat transfer, nucleate boiling and forced-convection vaporization, inverted-annular film boiling, and dispersed-flow film boiling. The heat transfer coefficients are functions of the local flow conditions. Good agreement of calculated and experimental results has been obtained. A code user's manual is appended
Robust Modelling of Heat and Mass Transfer in Processing of Solid Foods
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu
The study is focused on combined heat and mass transfer during processing of solid foods such as baking and frying processes. Modelling of heat and mass transfer during baking and frying is a significant scientific challenge. During baking and frying, the food undergoes several changes...... in microstructure and other physical properties of the food matrix. The heat and water transport inside the food is coupled in a complex way, which for some food systems it is not yet fully understood. A typical example of the latter is roasting of meat in convection oven, where the mechanism of water transport...... is unclear. Establishing the robust mathematical models describing the main mechanisms reliably is of great concern. A quantitative description of the heat and mass transfer during the solid food processing, in the form of mathematical equations, implementation of the solution techniques, and the value...
On the transfer matrix of the supersymmetric eight-vertex model. I. Periodic boundary conditions
Hagendorf, Christian; Liénardy, Jean
2018-03-01
The square-lattice eight-vertex model with vertex weights a, b, c, d obeying the relation (a^2+ab)(b^2+ab) = (c^2+ab)(d^2+ab) and periodic boundary conditions is considered. It is shown that the transfer matrix of the model for L = 2n + 1 vertical lines and periodic boundary conditions along the horizontal direction possesses the doubly degenerate eigenvalue \\Thetan = (a+b){\\hspace{0pt}}2n+1 . This proves a conjecture by Stroganov from 2001. The proof uses the supersymmetry of a related XYZ spin-chain Hamiltonian. The eigenstates of the transfer matrix corresponding to \\Thetan are shown to be the ground states of the spin-chain Hamiltonian. Moreover, for positive vertex weights \\Thetan is the largest eigenvalue of the transfer matrix.
Modeling of the heat transfer performance of plate-type dispersion nuclear fuel elements
Ding, Shurong; Huo, Yongzhong; Yan, XiaoQing
2009-08-01
Considering the mutual actions between fuel particles and the metal matrix, the three-dimensional finite element models are developed to simulate the heat transfer behaviors of dispersion nuclear fuel plates. The research results indicate that the temperatures of the fuel plate might rise more distinctly with considering the particle swelling and the degraded surface heat transfer coefficients with increasing burnup; the local heating phenomenon within the particles appears when their thermal conductivities are too low. With rise of the surface heat transfer coefficients, the temperatures within the fuel plate decrease; the temperatures of the fuel plate are sensitive to the variations of the heat transfer coefficients whose values are lower, but their effects are weakened and slight when the heat transfer coefficients increase and reach a certain extent. Increasing the heat generation rate leads to elevating the internal temperatures. The temperatures and the maximum temperature differences within the plate increase along with the particle volume fractions. The surface thermal flux goes up along with particle volume fractions and heat generation rates, but the effects of surface heat transfer coefficients are not evident.
International Nuclear Information System (INIS)
Xiong Jinbiao; Koshizuka, Seiichi; Sakai, Mikio
2011-01-01
Highlights: → We selected and evaluated five two-equation eddy-viscosity turbulence models for modeling the separated and reattaching flow. → The behavior of the models in the simple flow is not consistent with that in the separated and reattaching flow. → The Abe-Kondoh-Nagano model is the best one among the selected model. → Application of the stress limiter and the Kato-Launder modification in the Abe-Kondoh-Nagano model helps to improve prediction of the peak mass transfer coefficient in the orifice flow. → The value of turbulent Schmidt number is investigated. - Abstract: The prediction of mass transfer rate is one of the key elements for estimation of the flow accelerated corrosion (FAC) rate. Three low Reynolds number (LRN) k-ε models (Lam-Bremhorst (LB), Abe-Kondoh-Nagano (AKN) and Hwang-Lin (HL)), one LRN k-ω (Wilcox, WX) model and the k-ω SST model are tested for the computation of the high Schmidt number mass transfer, especially in the flow through an orifice. The models are tested in the computation of three types of flow: (1) the fully developed pipe flow, (2) the flow over a backward facing step, (3) the flow through an orifice. The HL model shows a good performance in predicting mass transfer in the fully developed pipe flow but fails to give reliable prediction in the flow through an orifice. The WX model and the k-ω SST model underpredict the mass transfer rate in the flow types 1 and 3. The LB model underestimates the mass transfer in the flow type 1, but shows abnormal behavior at the reattaching point in type 3. Synthetically evaluating all the models in all the computed case, the AKN model is the best one; however, the prediction is still not satisfactory. In the evaluation in the flow over a backward facing step shows k-ω SST model shows superior performance. This is interpreted as an implication that the combination of the k-ε model and the stress limiter can improve the model behavior in the recirculation bubble. Both the
Comparison of Two Models for Radiative Heat Transfer in High Temperature Thermal Plasmas
Directory of Open Access Journals (Sweden)
Matthieu Melot
2011-01-01
Full Text Available Numerical simulation of the arc-flow interaction in high-voltage circuit breakers requires a radiation model capable of handling high-temperature participating thermal plasmas. The modeling of the radiative transfer plays a critical role in the overall accuracy of such CFD simulations. As a result of the increase of computational power, CPU intensive methods based on the radiative transfer equation, leading to more accurate results, are now becoming attractive alternatives to current approximate models. In this paper, the predictive capabilities of the finite volume method (RTE-FVM and the P1 model are investigated. A systematic comparison between these two models and analytical solutions are presented for a variety of relevant test cases. Two implementations of each approach are compared, and a critical evaluation is presented.
Transferable tight-binding model for strained group IV and III-V materials and heterostructures
Tan, Yaohua; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy B.; Klimeck, Gerhard
2016-07-01
It is critical to capture the effect due to strain and material interface for device level transistor modeling. We introduce a transferable s p3d5s* tight-binding model with nearest-neighbor interactions for arbitrarily strained group IV and III-V materials. The tight-binding model is parametrized with respect to hybrid functional (HSE06) calculations for varieties of strained systems. The tight-binding calculations of ultrasmall superlattices formed by group IV and group III-V materials show good agreement with the corresponding HSE06 calculations. The application of the tight-binding model to superlattices demonstrates that the transferable tight-binding model with nearest-neighbor interactions can be obtained for group IV and III-V materials.
International Nuclear Information System (INIS)
Jeanne, T.
1990-03-01
A conduction model and a radiation model are proposed for the calculation of heat transfer. A multiphase multicomponent medium is considered. The conduction model allows the calculation of heat exchanges between two configurations. The heat flow from each component can be obtained. This model is well adapted to the calculation of thermal shocks in an ensemble of materials. The radiation model shows how the radiative transfers can be calculated in a cylinder composed of two opaque surfaces, with the same axis of rotation, and separated by a transparent medium. The form factors are obtained from Herman and Nusselt methods. The parts of the face-to-face surfaces which are seen and not seen are evaluated [fr
RADAL: a dynamic model for the transfer of radionuclides through agricultural food chains
International Nuclear Information System (INIS)
Jerez Vegueria, S.F.; Frometa Suarez, I.; Jerez Vegueria, P.F.
1996-01-01
The contamination of agricultural products by radionuclides is a mechanism which results in radiation dose commitment to the population, following fallout deposits from the atmosphere to the landscape. This paper describes the structure of the dynamic food chain model RADAL. This model simulates an acute environmental transport of fallout radionuclides through agricultural food chains to man and estimates the levels of radiation doses resulting from consumption of contaminated food. The development of RADAL was based on different existing models. For mathematical representation the transport of radionuclides was modeled through compartments representing environmental elements and/or food products. The model solves a set of linear, first-order, differential equations to estimate the concentrations of radionuclides in soil, vegetation, animal tissues and animal products as a function of time following their deposition. Dynamic physico-chemical processes of the model include the following: deposition and foliar interception, weathering, foliar absorption, soil resuspension, transfer from soil surface to the root zone, absorption by plant roots, transfer to deep soil, transfer to animal products, and human consumption of agricultural products. A parameter sensitivity analyses, performed for the main parameters of the model, showed that the foliar interception constant and resuspension factor are the most influential parameters over the radiation doses / model output. (author)
A versatile model for tritium transfer from atmosphere to plant and soil
International Nuclear Information System (INIS)
Melintescu, A.; Galeriu, D.
2004-01-01
The need to increase the predictive power of risk assessment for large tritium releases implies a process level approach for model development. Tritium transfer for atmosphere to plant and the conversion in organically bound tritium depend strongly on plant characteristics, season, and meteorological conditions.In order to cope with this large variability and to avoid also, expensive calibration experiments, we developed a model using knowledge of plant physiology, agro-meteorology, soil sciences, hydrology, and climatology. The transfer of tritiated water to plant is modelled with resistance approach including sparse canopy. The canopy resistance is modelled using Jarvis-Calvet approach modified in order to directly use the canopy photosynthesis rate.The crop growth model WOFOST is used for photosynthesis rate both for canopy resistance and formation of organically bound tritium, also. Using this formalism, the tritium transfer parameters are directly linked to known processes and parameters from agricultural sciences. The model predictions for tritium in wheat are closed to a factor two to experimental data without any calibration. The model also is tested for rice and soya bean and can be applied for various plants and environmental conditions. For sparse canopy the model uses coupled equations between soil and plants. (author)
Modelling heat transfer during flow through a random packed bed of spheres
Burström, Per E. C.; Frishfelds, Vilnis; Ljung, Anna-Lena; Lundström, T. Staffan; Marjavaara, B. Daniel
2018-04-01
Heat transfer in a random packed bed of monosized iron ore pellets is modelled with both a discrete three-dimensional system of spheres and a continuous Computational Fluid Dynamics (CFD) model. Results show a good agreement between the two models for average values over a cross section of the bed for an even temperature profiles at the inlet. The advantage with the discrete model is that it captures local effects such as decreased heat transfer in sections with low speed. The disadvantage is that it is computationally heavy for larger systems of pellets. If averaged values are sufficient, the CFD model is an attractive alternative that is easy to couple to the physics up- and downstream the packed bed. The good agreement between the discrete and continuous model furthermore indicates that the discrete model may be used also on non-Stokian flow in the transitional region between laminar and turbulent flow, as turbulent effects show little influence of the overall heat transfer rates in the continuous model.
DEFF Research Database (Denmark)
Bøje, Rikke Buus; Bland, Andrew; Sutton, Andrew
2017-01-01
of the study were to develop a model to educate the educators who deliver simulation-based learning and to test to which extent this model could be transferred to education providers in different national settings. METHODS: This model, its transferability and feasibility, was tested across three European...
Roberts, Sa; McGowan, L; Hirst, Wm; Brison, Dr; Vail, A; Lieberman, Ba
2010-07-01
In vitro fertilisation (IVF) treatments involve an egg retrieval process, fertilisation and culture of the resultant embryos in the laboratory, and the transfer of embryos back to the mother over one or more transfer cycles. The first transfer is usually of fresh embryos and the remainder may be cryopreserved for future frozen cycles. Most commonly in UK practice two embryos are transferred (double embryo transfer, DET). IVF techniques have led to an increase in the number of multiple births, carrying an increased risk of maternal and infant morbidity. The UK Human Fertilisation and Embryology Authority (HFEA) has adopted a multiple birth minimisation strategy. One way of achieving this would be by increased use of single embryo transfer (SET). To collate cohort data from treatment centres and the HFEA; to develop predictive models for live birth and twinning probabilities from fresh and frozen embryo transfers and predict outcomes from treatment scenarios; to understand patients' perspectives and use the modelling results to investigate the acceptability of twin reduction policies. A multidisciplinary approach was adopted, combining statistical modelling with qualitative exploration of patients' perspectives: interviews were conducted with 27 couples at various stages of IVF treatment at both UK NHS and private clinics; datasets were collated of over 90,000 patients from the HFEA registry and nearly 9000 patients from five clinics, both over the period 2000-5; models were developed to determine live birth and twin outcomes and predict the outcomes of policies for selecting patients for SET or DET in the fresh cycle following egg retrieval and fertilisation, and the predictions were used in simulations of treatments; two focus groups were convened, one NHS and one web based on a patient organisation's website, to present the results of the statistical analyses and explore potential treatment policies. The statistical analysis revealed no characteristics that
Prediction of transpiration effects on heat and mass transfer by different turbulence models
International Nuclear Information System (INIS)
Bucci, M.; Sharabi, M.; Ambrosini, W.; Forgione, N.; Oriolo, F.; He, S.
2008-01-01
The paper reports the results of a study related to transpirating flows, stimulated by the interest that these phenomena, occurring in the presence of simultaneous heat and mass transfer, have for nuclear reactor applications. The work includes a summary and the follow-up of previous experimental and numerical investigations on filmwise condensation and falling film evaporation and of a recent review of different forms of the heat and mass transfer analogy. The particular objective here pursued is to compare transpiration effects as predicted by different turbulence models with classical suction and blowing multipliers based on stagnant layer theories, in the attempt to clarify their quantitative implications on the predicted mass transfer rates. A commercial and an in-house CFD code have been adopted for evaluating the heat and mass transfer rates occurring over a flat plate exposed to an air-vapour stream, with uniform bulk steam mass fraction and temperature boundary conditions at the wall. This simple configuration was purposely selected since it is a simplified representation of the test section of an experimental facility presently in operation at the University of Pisa. This allows a direct comparison between the heat and mass transfer coefficients predicted by CFD models and classical correlations for Nusselt and Sherwood numbers
Rozanov, V. V.; Dinter, T.; Rozanov, A. V.; Wolanin, A.; Bracher, A.; Burrows, J. P.
2017-06-01
SCIATRAN is a comprehensive software package which is designed to model radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared (0.18-40 μm). It accounts for multiple scattering processes, polarization, thermal emission and ocean-atmosphere coupling. The main goal of this paper is to present a recently developed version of SCIATRAN which takes into account accurately inelastic radiative processes in both the atmosphere and the ocean. In the scalar version of the coupled ocean-atmosphere radiative transfer solver presented by Rozanov et al. [61] we have implemented the simulation of the rotational Raman scattering, vibrational Raman scattering, chlorophyll and colored dissolved organic matter fluorescence. In this paper we discuss and explain the numerical methods used in SCIATRAN to solve the scalar radiative transfer equation including trans-spectral processes, and demonstrate how some selected radiative transfer problems are solved using the SCIATRAN package. In addition we present selected comparisons of SCIATRAN simulations with those published benchmark results, independent radiative transfer models, and various measurements from satellite, ground-based, and ship-borne instruments. The extended SCIATRAN software package along with a detailed User's Guide is made available for scientists and students, who are undertaking their own research typically at universities, via the web page of the Institute of Environmental Physics (IUP), University of Bremen: http://www.iup.physik.uni-bremen.de.
A numerical model for boiling heat transfer coefficient of zeotropic mixtures
Barraza Vicencio, Rodrigo; Caviedes Aedo, Eduardo
2017-12-01
Zeotropic mixtures never have the same liquid and vapor composition in the liquid-vapor equilibrium. Also, the bubble and the dew point are separated; this gap is called glide temperature (Tglide). Those characteristics have made these mixtures suitable for cryogenics Joule-Thomson (JT) refrigeration cycles. Zeotropic mixtures as working fluid in JT cycles improve their performance in an order of magnitude. Optimization of JT cycles have earned substantial importance for cryogenics applications (e.g, gas liquefaction, cryosurgery probes, cooling of infrared sensors, cryopreservation, and biomedical samples). Heat exchangers design on those cycles is a critical point; consequently, heat transfer coefficient and pressure drop of two-phase zeotropic mixtures are relevant. In this work, it will be applied a methodology in order to calculate the local convective heat transfer coefficients based on the law of the wall approach for turbulent flows. The flow and heat transfer characteristics of zeotropic mixtures in a heated horizontal tube are investigated numerically. The temperature profile and heat transfer coefficient for zeotropic mixtures of different bulk compositions are analysed. The numerical model has been developed and locally applied in a fully developed, constant temperature wall, and two-phase annular flow in a duct. Numerical results have been obtained using this model taking into account continuity, momentum, and energy equations. Local heat transfer coefficient results are compared with available experimental data published by Barraza et al. (2016), and they have shown good agreement.
SKIRT: The design of a suite of input models for Monte Carlo radiative transfer simulations
Baes, M.; Camps, P.
2015-09-01
The Monte Carlo method is the most popular technique to perform radiative transfer simulations in a general 3D geometry. The algorithms behind and acceleration techniques for Monte Carlo radiative transfer are discussed extensively in the literature, and many different Monte Carlo codes are publicly available. On the contrary, the design of a suite of components that can be used for the distribution of sources and sinks in radiative transfer codes has received very little attention. The availability of such models, with different degrees of complexity, has many benefits. For example, they can serve as toy models to test new physical ingredients, or as parameterised models for inverse radiative transfer fitting. For 3D Monte Carlo codes, this requires algorithms to efficiently generate random positions from 3D density distributions. We describe the design of a flexible suite of components for the Monte Carlo radiative transfer code SKIRT. The design is based on a combination of basic building blocks (which can be either analytical toy models or numerical models defined on grids or a set of particles) and the extensive use of decorators that combine and alter these building blocks to more complex structures. For a number of decorators, e.g. those that add spiral structure or clumpiness, we provide a detailed description of the algorithms that can be used to generate random positions. Advantages of this decorator-based design include code transparency, the avoidance of code duplication, and an increase in code maintainability. Moreover, since decorators can be chained without problems, very complex models can easily be constructed out of simple building blocks. Finally, based on a number of test simulations, we demonstrate that our design using customised random position generators is superior to a simpler design based on a generic black-box random position generator.
Directory of Open Access Journals (Sweden)
Gabriele Scheler
Full Text Available We present a novel formulation for biochemical reaction networks in the context of protein signal transduction. The model consists of input-output transfer functions, which are derived from differential equations, using stable equilibria. We select a set of "source" species, which are interpreted as input signals. Signals are transmitted to all other species in the system (the "target" species with a specific delay and with a specific transmission strength. The delay is computed as the maximal reaction time until a stable equilibrium for the target species is reached, in the context of all other reactions in the system. The transmission strength is the concentration change of the target species. The computed input-output transfer functions can be stored in a matrix, fitted with parameters, and even recalled to build dynamical models on the basis of state changes. By separating the temporal and the magnitudinal domain we can greatly simplify the computational model, circumventing typical problems of complex dynamical systems. The transfer function transformation of biochemical reaction systems can be applied to mass-action kinetic models of signal transduction. The paper shows that this approach yields significant novel insights while remaining a fully testable and executable dynamical model for signal transduction. In particular we can deconstruct the complex system into local transfer functions between individual species. As an example, we examine modularity and signal integration using a published model of striatal neural plasticity. The modularizations that emerge correspond to a known biological distinction between calcium-dependent and cAMP-dependent pathways. Remarkably, we found that overall interconnectedness depends on the magnitude of inputs, with higher connectivity at low input concentrations and significant modularization at moderate to high input concentrations. This general result, which directly follows from the properties of
Introduction to the development of models of radionuclides transfer in the environment
International Nuclear Information System (INIS)
Garcia-Olivares, A.
1994-01-01
This work explores the foundations of radioecological modelization with environmental assessment pourposes. In particular its relation with the theory of dynamic systems, and the basic hypothesis underlying the modelization practices. Some very theoretical considerations are followed by some guidelines for the application of the concepts to specific problems of radiological modelization in assessment of consequences. In particular, the report studies the mechanisms most frequently involved in the radionuclide transfer through the environment, the steps to generate a predictive model, the obtaining of generic parameters and finally the uncertainty analysis of the model. (Author) 41 refs
Introduction to the development of models of radionuclides transfer in the environment
International Nuclear Information System (INIS)
Garcia-Olivares, A.
1994-01-01
This work explores the foundations of radioecological modelization with environmental assessment purposes. In particular its relation with the theory of dynamic systems, and the basic hypothesis underlying the modelization practices. Some very theoretical considerations are followed by some guidelines for the application of the concepts to specific problems of radiological modelization in assessment of consequences. In particular, the report studies the mechanisms most frequently involved in the radionuclide transfer through the environment, the steps to generate a predictive model, the obtaining of generic parameters and finally the uncertainty analysis of the model. (Author) 41 refs
Introduction to the development of models of radionuclides transfer in the environment
Energy Technology Data Exchange (ETDEWEB)
Garcia-Olivares, A
1994-07-01
This work explores the foundations of radioecological modelization with environmental assessment purposes. In particular its relation with the theory of dynamic systems, and the basic hypothesis underlying the modelization practices. Some very theoretical considerations are followed by some guidelines for the application of the concepts to specific problems of radiological modelization in assessment of consequences. In particular, the report studies the mechanisms most frequently involved in the radionuclide transfer through the environment, the steps to generate a predictive model, the obtaining of generic parameters and finally the uncertainty analysis of the model. (Author) 41 refs.
Numerical Problems and Agent-Based Models for a Mass Transfer Course
Murthi, Manohar; Shea, Lonnie D.; Snurr, Randall Q.
2009-01-01
Problems requiring numerical solutions of differential equations or the use of agent-based modeling are presented for use in a course on mass transfer. These problems were solved using the popular technical computing language MATLABTM. Students were introduced to MATLAB via a problem with an analytical solution. A more complex problem to which no…
Robustness of a cross contamination model describing transfer of pathogens during grinding of meat
DEFF Research Database (Denmark)
Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm
2016-01-01
This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were...
Modelling water evaporation during frying with an evaporation dependent heat transfer coefficient
Koerten, van K.N.; Somsen, D.; Boom, R.M.; Schutyser, M.A.I.
2017-01-01
In this study a cylindrical crust-core frying model was developed including an evaporation rate dependent heat transfer coefficient. For this, we applied a Nusselt relation for cylindrical bodies and view the release of vapour bubbles during the frying process as a reversed fluidised bed. The
An adult passive transfer mouse model to study desmoglein 3 signaling in pemphigus vulgaris.
Schulze, Katja; Galichet, Arnaud; Sayar, Beyza S; Scothern, Anthea; Howald, Denise; Zymann, Hillard; Siffert, Myriam; Zenhäusern, Denise; Bolli, Reinhard; Koch, Peter J; Garrod, David; Suter, Maja M; Müller, Eliane J
2012-02-01
Evidence has accumulated that changes in intracellular signaling downstream of desmoglein 3 (Dsg3) may have a significant role in epithelial blistering in the autoimmune disease pemphigus vulgaris (PV). Currently, most studies on PV involve passive transfer of pathogenic antibodies into neonatal mice that have not finalized epidermal morphogenesis, and do not permit analysis of mature hair follicles (HFs) and stem cell niches. To investigate Dsg3 antibody-induced signaling in the adult epidermis at defined stages of the HF cycle, we developed a model with passive transfer of AK23 (a mouse monoclonal pathogenic anti-Dsg3 antibody) into adult 8-week-old C57Bl/6J mice. Validated using histopathological and molecular methods, we found that this model faithfully recapitulates major features described in PV patients and PV models. Two hours after AK23 transfer, we observed widening of intercellular spaces between desmosomes and EGFR activation, followed by increased Myc expression and epidermal hyperproliferation, desmosomal Dsg3 depletion, and predominant blistering in HFs and oral mucosa. These data confirm that the adult passive transfer mouse model is ideally suited for detailed studies of Dsg3 antibody-mediated signaling in adult skin, providing the basis for investigations on novel keratinocyte-specific therapeutic strategies.
Robustness of a cross contamination model describing transfer of pathogens during grinding of meat
DEFF Research Database (Denmark)
Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm
2016-01-01
This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were a...... that grinding was influenced by sharpness of grinder knife, specific grinder and grinding temperature....
A three-dimensional model of solar radiation transfer in a non-uniform plant canopy
Levashova, N. T.; Mukhartova, Yu V.
2018-01-01
A three-dimensional (3D) model of solar radiation transfer in a non-uniform plant canopy was developed. It is based on radiative transfer equations and a so-called turbid medium assumption. The model takes into account the multiple scattering contributions of plant elements in radiation fluxes. These enable more accurate descriptions of plant canopy reflectance and transmission in different spectral bands. The model was applied to assess the effects of plant canopy heterogeneity on solar radiation transmission and to quantify the difference in a radiation transfer between photosynthetically active radiation PAR (=0.39-0.72 μm) and near infrared solar radiation NIR (Δλ = 0.72-3.00 μm). Comparisons of the radiative transfer fluxes simulated by the 3D model within a plant canopy consisted of sparsely planted fruit trees (plant area index, PAI - 0.96 m2 m-2) with radiation fluxes simulated by a one-dimensional (1D) approach, assumed horizontal homogeneity of plant and leaf area distributions, showed that, for sunny weather conditions with a high solar elevation angle, an application of a simplified 1D approach can result in an underestimation of transmitted solar radiation by about 22% for PAR, and by about 26% for NIR.
CSIR Research Space (South Africa)
Malan, AG
2011-08-01
Full Text Available to modelling both forced convection as well as heat transfer and fluid flow through heterogeneous saturated porous materials via an edge-based finite volume discretization scheme. A volume-averaged set of local thermal disequilibrium governing equations...
Turbomachinery Heat Transfer and Loss Modeling for 3D Navier-Stokes Codes
DeWitt, Kenneth; Ameri, Ali
2005-01-01
This report's contents focus on making use of NASA Glenn on-site computational facilities,to develop, validate, and apply models for use in advanced 3D Navier-Stokes Computational Fluid Dynamics (CFD) codes to enhance the capability to compute heat transfer and losses in turbomachiney.
Small- and large-signal modeling of InP HBTs in transferred-substrate technology
DEFF Research Database (Denmark)
Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas
2014-01-01
In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing...
Finite element modeling of the neuron-electrode interface: stimulus transfer and geometry
Buitenweg, Jan R.; Rutten, Wim; Marani, Enrico
1999-01-01
The relation between stimulus transfer and the geometry of the neuron-electrode interface can not be determined properly using electrical equivalent circuits, since current that flows from the sealing gap through the neuronal membrane is difficult to model in these circuits. Therefore, finite
International Nuclear Information System (INIS)
Hummel, E.; Tjon, J.A.
1989-01-01
Using the one-boson-exchange model a relativistic covariant analysis is carried out of the elastic electromagnetic form factors of the deuteron including the ρπγ and ωεγ mesonic-exchange-current contributions. The theoretical predictions are compared with the recent experimental data at high momentum transfer
Solid foam packings for multiphase reactors: Modelling of liquid holdup and mass transfer
Stemmet, C.P.; Schaaf, van der J.; Kuster, B.F.M.; Schouten, J.C.
2006-01-01
In this paper, experimental and modeling results are presented of the liquid holdup and gas–liquid mass transfer characteristics of solid foam packings. Experiments were done in a semi-2D transparent bubble column with solid foam packings of aluminum in the range of 5–40 pores per inch (ppi). The
Modeling of InP HBTs in Transferred-Substrate Technology for Millimeter-Wave Applications
DEFF Research Database (Denmark)
Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas
2013-01-01
In this paper, the modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. At first, a direct parameter extraction methodology dedicated to III-V based HBTs is employed to determine the small-signal equivalent circuit parameters from...
EM simulation assisted parameter extraction for the modeling of transferred-substrate InP HBTs
DEFF Research Database (Denmark)
Johansen, Tom Keinicke; Weimann, Nils; Doerner, Ralf
2017-01-01
In this paper an electromagnetic (EM) simulation assisted parameters extraction procedure is demonstrated for accurate modeling of down-scaled transferred-substrate InP HBTs. The external parasitic network associated with via transitions and device electrodes is carefully extracted from calibrate...
A Model for the Transfer of Perceptual-Motor Skill Learning in Human Behaviors
Rosalie, Simon M.; Muller, Sean
2012-01-01
This paper presents a preliminary model that outlines the mechanisms underlying the transfer of perceptual-motor skill learning in sport and everyday tasks. Perceptual-motor behavior is motivated by performance demands and evolves over time to increase the probability of success through adaptation. Performance demands at the time of an event…
Chitescu, C.L.; Nicolau, A.I.; Romkens, P.F.A.M.; Fels-Klerx, van der H.J.
2014-01-01
Use of pharmaceuticals in animal production may cause an indirect route of contamination of food products of animal origin. This study aimed to assess, through mathematical modelling, the transfer of pharmaceuticals from contaminated soil, through plant uptake, into the dairy food production chain.
The fourth phase of the radiative transfer model imtercomparison (RAMI) exercise
Czech Academy of Sciences Publication Activity Database
Widlowski, J. L.; Mio, C.; Disney, M.; Adams, J.; Andredakis, I.; Atzberger, C.; Brennan, J.; Busetto, L.; Chelle, M.; Ceccherini, G.; Colombo, R.; Coté, J. F.; Eenmäe, A.; Essery, R.; Gastellu-Etchegory, J.P.; Gobron, N.; Grau, E.; Haverd, V.; Homolová, Lucie; Huang, H.; Hunt, L.; Kobayashi, H.; Koetz, B.; Kuusk, A.; Kuusk, J.; Lang, M.; Lewis, P. E.; Lovell, J. L.; Malenovský, Z.; Michele, M.; Mordsorf, F.; Mottus, M.; Ni-Meister, W.; Pinty, B.; Rautianien, M.; Schlerf, M.; Somers, B.; Stuckens, J.; Vestraete, M. M.; Yang, W.; Zhao, F.; Zenone, T.
2015-01-01
Roč. 169, nov (2015), s. 418-437 ISSN 0034-4257 Institutional support: RVO:67179843 Keywords : conformity testing * radiative transfer * model benchmarking * 3D virtual plant canopy * digital hemispherical photography * optical remote sensing * shared risk * guarded acceptance * GCOS * ISO -13528 Subject RIV: EH - Ecology, Behaviour Impact factor: 5.881, year: 2015
The mathematical model of vertical solt transfer on mine dumps Western Donbass
Directory of Open Access Journals (Sweden)
H. P. Yevhrashkina,
2011-11-01
Full Text Available On the based theory of physical-chemical hydrodynamics of porous media offer a range of mathematical models of vertical salt transfer on mine dumps Western Donbass. designed several variants of dumps free overgrowth for the optimal performance for transpiration of wild plants.
Efficient micromagnetic modelling of spin-transfer torque and spin-orbit torque
Abert, Claas; Bruckner, Florian; Vogler, Christoph; Suess, Dieter
2018-05-01
While the spin-diffusion model is considered one of the most complete and accurate tools for the description of spin transport and spin torque, its solution in the context of dynamical micromagnetic simulations is numerically expensive. We propose a procedure to retrieve the free parameters of a simple macro-spin like spin-torque model through the spin-diffusion model. In case of spin-transfer torque the simplified model complies with the model of Slonczewski. A similar model can be established for the description of spin-orbit torque. In both cases the spin-diffusion model enables the retrieval of free model parameters from the geometry and the material parameters of the system. Since these parameters usually have to be determined phenomenologically through experiments, the proposed method combines the strength of the diffusion model to resolve material parameters and geometry with the high performance of simple torque models.
CFD modeling of heat transfer performance of MgO-water nanofluid under turbulent flow
Directory of Open Access Journals (Sweden)
Reza Davarnejad
2015-12-01
Full Text Available In this paper, Computational fluid dynamics (CFD modeling of turbulent heat transfer behavior of Magnesium Oxide-water nanofluid in a circular tube was studied. The modeling was two dimensional under k–ε turbulence model. The base fluid was pure water and the volume fraction of nanoparticles in the base fluid was 0.0625%, 0.125%, 0.25%, 0.5% and 1%. The applied Reynolds number range was 3000–19000. Three individual models including single phase, Volume of Fluid (VOF and mixture were used. The results showed that the simulated data were in good agreement with the experimental ones available in the literature. According to the experimental work (literature and simulation (this research, Nusselt number (Nu increased with increasing the volume fraction of nanofluid. However friction factor of nanofluid increased but its effect was ignorable compared with the Nu on heat transfer increment. It was concluded that two phase models were more accurate than the others for heat transfer prediction particularly in the higher volume fractions of nanoparticle. The average deviation from experimental data for single phase model was about 11% whereas it was around 2% for two phase models.
CFD modelling wall heat transfer inside a combustion chamber using ANSYS forte
Plengsa-ard, C.; Kaewbumrung, M.
2018-01-01
A computational model has been performed to analyze a wall heat transfer in a single cylinder, direct injection and four-stroke diesel engine. A direct integration using detailed chemistry CHEMKIN is employed in a combustion model and the Reynolds Averaged Navier Stokes (RANS) turbulence model is used to simulate the flow in the cylinder. To obtain heat flux results, a modified classical variable-density wall heat transfer model is also performed. The model is validated using experimental data from a CUMMINs engine operated with a conventional diesel combustion. One operating engine condition is simulated. Comparisons of simulated in-cylinder pressure and heat release rates with experimental data shows that the model predicts the cylinder pressure and heat release rates reasonably well. The contour plot of instantaneous temperature are presented. Also, the contours of predicted heat flux results are shown. The magnitude of peak heat fluxes as predicted by the wall heat transfer model is in the range of the typical measure values in diesel combustion.
The experimental study of heat transfer around molds inside a model autoclave
Ghamlouch, Taleb; Roux, Stéphane; Lefèvre, Nicolas; Bailleul, Jean-Luc; Sobotka, Vincent
2018-05-01
The temperature distribution within composite parts manufactured inside autoclaves plays a key role in determining the parts quality at the end of the curing cycle. Indeed, heat transfer between the parts and the surroundings inside an autoclave is strongly coupled with the flow field around the molds and can be modeled through the convective heat transfer coefficient (HTC). The aerodynamically unsuitable geometry of the molds generates complex turbulent non-uniform flows around them accompanied with the presence of dead zones. This heterogeneity can imply non-uniform convective heat transfers leading to temperature gradients inside parts that can be prejudicial. Given this fact, the purpose of this study is to perform experimental measurements in order to describe the flow field and the convective heat transfer behavior around representative industrial molds installed inside a home-made model. A key point of our model autoclave is the ease of use of non-intrusive measuring instruments: the Particle Image Velocimetry (PIV) technique and infrared imaging camera for the study of the flow field and the heat transfer coefficient distribution around the molds respectively. The experimental measurements are then compared to computational fluid dynamics (CFD) calculations performed on the computer code ANSYS Fluent 16.0®. This investigation has revealed, as expected, a non-uniform distribution of the convective heat transfer coefficient around the molds and therefore the presence of thermal gradients which can reduce the composite parts quality during an autoclave process. A good agreement has been achieved between the experimental and the numerical results leading then to the validation of the performed numerical simulations.
Modulation transfer function cascade model for a sampled IR imaging system.
de Luca, L; Cardone, G
1991-05-01
The performance of the infrared scanning radiometer (IRSR) is strongly stressed in convective heat transfer applications where high spatial frequencies in the signal that describes the thermal image are present. The need to characterize more deeply the system spatial resolution has led to the formulation of a cascade model for the evaluation of the actual modulation transfer function of a sampled IR imaging system. The model can yield both the aliasing band and the averaged modulation response for a general sampling subsystem. For a line scan imaging system, which is the case of a typical IRSR, a rule of thumb that states whether the combined sampling-imaging system is either imaging-dependent or sampling-dependent is proposed. The model is tested by comparing it with other noncascade models as well as by ad hoc measurements performed on a commercial digitized IRSR.
A multi-fluid model to simulate heat and mass transfer in a PEM fuel cell
DEFF Research Database (Denmark)
Berning, Torsten; Odgaard, Madeleine; Kær, Søren Knudsen
2011-01-01
This article summarizes a multi-phase model of a polymer electrolyte membrane fuel cell based on the formerly commercial CFD code CFX-4. It is three-dimensional in nature and includes multiphase heat and mass transfer in porous media. An overview is given and some numerical issues are discussed...... heat and mass transfer properties are superior. Another important aspect of this study is the wetting status of the electrolyte menbrane and the effective drag of water through the menbrane, which indicates what fraction of the product water created at the cathode side diffuses through the membrane...
Mathematical modeling of heat transfer in production premises heated by gas infrared emitters
Directory of Open Access Journals (Sweden)
Maksimov Vyacheslav I.
2017-01-01
Full Text Available The results of numerical modeling of the process of free convective heat transfer in the regime of turbulent convection in a closed rectangular region heated by an infrared radiator are presented. The system of Navier-Stokes equations in the Boussinesq approximation is solved, the energy equation for the gas and the heat conduction equations for the enclosing vertical and horizontal walls. A comparative analysis of the heat transfer regimes in the considered region for different Grashof numbers is carried out. The features of the formation of heated air flows relative to the infrared emitter located at some distance from the upper horizontal boundary of the region are singled out.
Two-dimensional finite element heat transfer model of softwood. Part II, Macrostructural effects
Hongmei Gu; John F. Hunt
2006-01-01
A two-dimensional finite element model was used to study the effects of structural features on transient heat transfer in softwood lumber with various orientations. Transient core temperature was modeled for lumber samples âcutâ from various locations within a simulated log. The effects of ring orientation, earlywood to latewood (E/L) ratio, and ring density were...
Modulated mass-transfer model for superhumps in SU Ursae Majoris stars
Mineshige, Shin
1988-01-01
The response of a circular accretion disk to rapid modulation of the mass-transfer rate into the disk is explored in order to model superhumps in SU UMa stars. It is proposed that periodically enhanced flow may disrupt or heat up the outer disk and produce the dips noted just before the superhump peaks. The elliptical accretion-disk model with extended vertical disk structure can account for the observed characteristics of superhumps in these stars.
NitroScape: A model to integrate nitrogen transfers and transformations in rural landscapes
Energy Technology Data Exchange (ETDEWEB)
Duretz, S. [INRA-AgroParisTech, UMR 1091 Environnement et Grandes Cultures (EGC), 78850 Thiverval-Grignon (France); Drouet, J.L., E-mail: Jean-Louis.Drouet@grignon.inra.fr [INRA-AgroParisTech, UMR 1091 Environnement et Grandes Cultures (EGC), 78850 Thiverval-Grignon (France); Durand, P. [INRA-AgroCampus, UMR 1069 Sol Agro et hydrosysteme Spatialisation (SAS), 35042 Rennes cedex (France); Hutchings, N.J. [Department of Agroecology, Faculty of Agricultural Sciences, University of Aarhus (AU), Blichers Alle, 8830 Tjele (Denmark); Theobald, M.R. [Department of Chemistry and Agricultural Analysis, Technical University of Madrid (UPM), 28040 Madrid (Spain); Centre for Ecology and Hydrology (CEH), Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Salmon-Monviola, J. [INRA-AgroCampus, UMR 1069 Sol Agro et hydrosysteme Spatialisation (SAS), 35042 Rennes cedex (France); Dragosits, U. [Centre for Ecology and Hydrology (CEH), Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Maury, O. [INRA-AgroParisTech, UMR 1091 Environnement et Grandes Cultures (EGC), 78850 Thiverval-Grignon (France); Sutton, M.A. [Centre for Ecology and Hydrology (CEH), Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Cellier, P. [INRA-AgroParisTech, UMR 1091 Environnement et Grandes Cultures (EGC), 78850 Thiverval-Grignon (France)
2011-11-15
Modelling nitrogen transfer and transformation at the landscape scale is relevant to estimate the mobility of the reactive forms of nitrogen (N{sub r}) and the associated threats to the environment. Here we describe the development of a spatially and temporally explicit model to integrate N{sub r} transfer and transformation at the landscape scale. The model couples four existing models, to simulate atmospheric, farm, agro-ecosystem and hydrological N{sub r} fluxes and transformations within a landscape. Simulations were carried out on a theoretical landscape consisting of pig-crop farms interspersed with unmanaged ecosystems. Simulation results illustrated the effect of spatial interactions between landscape elements on N{sub r} fluxes and losses to the environment. More than 10% of the total N{sub 2}O emissions were due to indirect emissions. The nitrogen budgets and transformations of the unmanaged ecosystems varied considerably, depending on their location within the landscape. The model represents a new tool for assessing the effect of changes in landscape structure on N{sub r} fluxes. - Highlights: > The landscape scale is relevant to study how spatial interactions affect N{sub r} fate. > The NitroScape model integrates N{sub r} transfer and transformation at landscape scale. > NitroScape couples existing atmospheric, farm, agro-ecosystem and hydrological models. > Data exchanges within NitroScape are dynamic and spatially distributed. > More than 10% of the simulated N{sub 2}O emissions are due to indirect emissions. - A model integrating terrestrial, hydrological and atmospheric processes of N{sub r} transfer and transformation at the landscape scale has been developed to simulate the effect of spatial interactions between landscape elements on N{sub r} fate.
Mathematical model of heat transfer to predict distribution of hardness through the Jominy bar
International Nuclear Information System (INIS)
Lopez, E.; Hernandez, J. B.; Solorio, G.; Vergara, H. J.; Vazquez, O.; Garnica, F.
2013-01-01
The heat transfer coefficient was estimated at the bottom surface at Jominy bar end quench specimen by solution of the heat inverse conduction problem. A mathematical model based on the finite-difference method was developed to predict thermal paths and volume fraction of transformed phases. The mathematical model was codified in the commercial package Microsoft Visual Basic v. 6. The calculated thermal path and final phase distribution were used to evaluate the hardness distribution along the AISI 4140 Jominy bar. (Author)
Modulated mass-transfer model for superhumps in SU Ursae Majoris stars
International Nuclear Information System (INIS)
Mineshige, S.
1988-01-01
The response of a circular accretion disk to rapid modulation of the mass-transfer rate into the disk is explored in order to model superhumps in SU UMa stars. It is proposed that periodically enhanced flow may disrupt or heat up the outer disk and produce the dips noted just before the superhump peaks. The elliptical accretion-disk model with extended vertical disk structure can account for the observed characteristics of superhumps in these stars. 52 references
NitroScape: A model to integrate nitrogen transfers and transformations in rural landscapes
International Nuclear Information System (INIS)
Duretz, S.; Drouet, J.L.; Durand, P.; Hutchings, N.J.; Theobald, M.R.; Salmon-Monviola, J.; Dragosits, U.; Maury, O.; Sutton, M.A.; Cellier, P.
2011-01-01
Modelling nitrogen transfer and transformation at the landscape scale is relevant to estimate the mobility of the reactive forms of nitrogen (N r ) and the associated threats to the environment. Here we describe the development of a spatially and temporally explicit model to integrate N r transfer and transformation at the landscape scale. The model couples four existing models, to simulate atmospheric, farm, agro-ecosystem and hydrological N r fluxes and transformations within a landscape. Simulations were carried out on a theoretical landscape consisting of pig-crop farms interspersed with unmanaged ecosystems. Simulation results illustrated the effect of spatial interactions between landscape elements on N r fluxes and losses to the environment. More than 10% of the total N 2 O emissions were due to indirect emissions. The nitrogen budgets and transformations of the unmanaged ecosystems varied considerably, depending on their location within the landscape. The model represents a new tool for assessing the effect of changes in landscape structure on N r fluxes. - Highlights: → The landscape scale is relevant to study how spatial interactions affect N r fate. → The NitroScape model integrates N r transfer and transformation at landscape scale. → NitroScape couples existing atmospheric, farm, agro-ecosystem and hydrological models. → Data exchanges within NitroScape are dynamic and spatially distributed. → More than 10% of the simulated N 2 O emissions are due to indirect emissions. - A model integrating terrestrial, hydrological and atmospheric processes of N r transfer and transformation at the landscape scale has been developed to simulate the effect of spatial interactions between landscape elements on N r fate.
SAR in human head model due to resonant wireless power transfer system.
Zhang, Chao; Liu, Guoqiang; Li, Yanhong; Song, Xianjin
2016-04-29
Efficient mid-range wireless power transfer between transmitter and the receiver has been achieved based on the magnetic resonant coupling method. The influence of electromagnetic field on the human body due to resonant wireless power transfer system (RWPT) should be taken into account during the design process of the system. To analyze the transfer performance of the RWPT system and the change rules of the specific absorption rate (SAR) in the human head model due to the RWPT system. The circuit-field coupling method for a RWPT system with consideration of the displacement current was presented. The relationship between the spiral coil parameters and transfer performance was studied. The SAR in the human head model was calculated under two different exposure conditions. A system with output power higher than 10 W at 0.2 m distance operating at a frequency of approximately 1 MHz was designed. The FEM simulation results show the peak SAR value is below the safety limit which appeared when the human head model is in front of the transmitter. The simulation results agreed well with the experimental results, which verified the validity of the analysis and design.
Inter-subchannel heat transfer modeling for a subchannel analysis of liquid metal-cooled reactors
International Nuclear Information System (INIS)
Hae-Yong, Jeong; Kwi-Seok, Ha; Young-Min, Kwon; Yong-Bum, Lee; Dohee, Hahn
2007-01-01
In a subchannel approach, the temperature, pressure and velocity in a subchannel are averaged, and one representative thermal-hydraulic condition specifies the state of a subchannel. To enhance the predictability of a subchannel analysis code, it is required to model the inter-subchannel heat transfer between the adjacent subchannels as accurately as possible. One of the critical parameters which determine the thermal-hydraulic behavior of the coolant in subchannels is the heat conduction between two neighboring sub-channels. This portion of a heat transfer becomes more important in the design of an LMR (Liquid Metal-cooled Reactor) because of the high heat capacity of the liquid metal coolant. The other important part of heat transfer is the mixing of flow as a form of cross flow. Especially, the turbulent mixing caused by the eddy motion of fluid across the gap between the subchannels enhances the exchange of the momentum and the energy through the gap with no net transport of the mass. Major results of recent efforts on these modeling have been implemented in a subchannel analysis code MATRA-LMR-FB. The analysis shows that the accuracy of a subchannel analysis code is improved by enhancing the models describing the conduction heat transfer and the cross-flow mixing, especially at low flow rate. (authors)
Energy transfer modelling of active thermoacoustic engines via Lagrangian thermoacoustic dynamics
International Nuclear Information System (INIS)
Hong, Boe-Shong; Chou, Chia-Yu
2014-01-01
Highlights: • Resonant control on thermoacoustic engines to amplify power rating. • Least-action principle of thermoacoustic dynamics to shape engine chamber. • Spatiotemporal transfer function into feedback systems. • Conservation law of thermoacoustic storage to figure out engine cycles. • Robin boundary condition to identify flow leakage. - Abstract: This paper develops energy-transfer modelling of active thermoacoustic engines resonantly controlled on boundary for amplification of power rating toward satisfaction of renewable industry. Therein the wave equation of thermoacoustic dynamics in resonators with non-uniform media and boundary actuations is derived and then turned into a least-action principle. With this least-action principle, we obtain the governing equation of longitudinal resonators with spatially variant cross-section areas to investigate how to shape the resonator for boosting piston stroke and power-transmission efficiency. It is followed by spatiotemporal transfer-function modelling that functionally represents the dynamics and interprets the boundary actuations into internal inputs. This helps formulate the overall dynamics into feedback-interconnection between the thermoacoustic dynamics in the resonator and the mechatronic dynamics of the alternative current generator, so that synthesis of feedback systems can be applied to design the entire engine. Transfer-function modelling following least-action principle leads to the conservation law of thermoacoustic storage, which figures out engine cycles, the most fundamental principle in designing active thermoacoustic engines. Based on such feedback realization, digital signal processing is programmed to numerically assess power ratings of active designs
Evaluation of Interfacial Heat Transfer Models for Flashing Flow with Two-Fluid CFD
Directory of Open Access Journals (Sweden)
Yixiang Liao
2018-06-01
Full Text Available The complexity of flashing flows is increased vastly by the interphase heat transfer as well as its coupling with mass and momentum transfers. A reliable heat transfer coefficient is the key in the modelling of such kinds of flows with the two-fluid model. An extensive literature survey on computational modelling of flashing flows has been given in previous work. The present work is aimed at giving a brief review on available theories and correlations for the estimation of interphase heat transfer coefficient, and evaluating them quantitatively based on computational fluid dynamics simulations of bubble growth in superheated liquid. The comparison of predictions for bubble growth rate obtained by using different correlations with the experimental as well as direct numerical simulation data reveals that the performance of the correlations is dependent on the Jakob number and Reynolds number. No generally applicable correlations are available. Both conduction and convection are important in cases of bubble rising and translating in stagnant liquid at high Jakob numbers. The correlations combining the analytical solution for heat diffusion and the theoretical relation for potential flow give the best agreement.
International Nuclear Information System (INIS)
Engelhardt, G.; Urquidi-Macdonald, M.; Sikora, J.; Macdonald, D.D.
1995-01-01
A predictive and self-consistent mathematical model has been developed to describe the localized corrosion in steam generators. The model recognizes that the internal and external environment are coupled by the need to conserve charge in the system. Thus, solution of Laplace's equation for the external environment (outside the crevice) provides the boundary condition for the electric potential at the crevice mouth, which is needed for solving the system of mass transfer equations for the internal environment (inside the crevice). Mass transfer by diffusion, ion migration, and convection was considered. Heat and momentum transfer equations are solved simultaneously, with the mass balance equation for each species and the condition of electroneutrality inside the cavity being considered. The model takes into account the porosity and tortuosity in the corrosion product deposit in the crevice. The homogeneous chemical reactions (hydrolysis of the products of the anodic reaction and the autoprotolysis of water) are included in the model. The model, in this preliminary form predicts the solution chemistry, potential drop, and temperature distribution inside the crevice. An order of magnitude estimate of the crevice corrosion rate also obtained. At this point, the model predicts only the steady state solution, but it is recognized that a steady state may not exist under normal conditions
Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations.
Kim, Kyunghan; Guo, Zhixiong
2007-05-01
A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent.
Transferable tight binding model for strained group IV and III-V heterostructures
Tan, Yaohua; Povolotskyi, Micheal; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard
Modern semiconductor devices have reached critical device dimensions in the range of several nanometers. For reliable prediction of device performance, it is critical to have a numerical efficient model that are transferable to material interfaces. In this work, we present an empirical tight binding (ETB) model with transferable parameters for strained IV and III-V group semiconductors. The ETB model is numerically highly efficient as it make use of an orthogonal sp3d5s* basis set with nearest neighbor inter-atomic interactions. The ETB parameters are generated from HSE06 hybrid functional calculations. Band structures of strained group IV and III-V materials by ETB model are in good agreement with corresponding HSE06 calculations. Furthermore, the ETB model is applied to strained superlattices which consist of group IV and III-V elements. The ETB model turns out to be transferable to nano-scale hetero-structure. The ETB band structures agree with the corresponding HSE06 results in the whole Brillouin zone. The ETB band gaps of superlattices with common cations or common anions have discrepancies within 0.05eV.
Directory of Open Access Journals (Sweden)
Tao Zhi
2016-10-01
Full Text Available A variety of turbulence models were used to perform numerical simulations of heat transfer for hydrocarbon fuel flowing upward and downward through uniformly heated vertical pipes at supercritical pressure. Inlet temperatures varied from 373 K to 663 K, with heat flux ranging from 300 kW/m2 to 550 kW/m2. Comparative analyses between predicted and experimental results were used to evaluate the ability of turbulence models to respond to variable thermophysical properties of hydrocarbon fuel at supercritical pressure. It was found that the prediction performance of turbulence models is mainly determined by the damping function, which enables them to respond differently to local flow conditions. Although prediction accuracy for experimental results varied from condition to condition, the shear stress transport (SST and launder and sharma models performed better than all other models used in the study. For very small buoyancy-influenced runs, the thermal-induced acceleration due to variations in density lead to the impairment of heat transfer occurring in the vicinity of pseudo-critical points, and heat transfer was enhanced at higher temperatures through the combined action of four thermophysical properties: density, viscosity, thermal conductivity and specific heat. For very large buoyancy-influenced runs, the thermal-induced acceleration effect was over predicted by the LS and AB models.
Modelling transfer of Salmonella Typhimurium DT104 during simulation of grinding of pork.
Møller, C O A; Nauta, M J; Christensen, B B; Dalgaard, P; Hansen, T B
2012-01-01
The aim of this study was to develop a model to predict cross-contamination of Salmonella during grinding of pork. Transfer rates of Salmonella were measured in three experiments, where between 10 and 20 kg meat was ground into 200-g portions. In each experiment, five pork slices of about 200 g per slice were inoculated with 8-9 log-units of Salmonella Typhimurium DT104 and used for building up the contamination in the grinder. Subsequently, Salmonella-free slices were ground and collected as samples of c. 200 g minced pork. Throughout the process, representative samples were quantitatively analysed for Salmonella. A model suggested by Nauta et al. (2005) predicting cross-contamination of Campylobacter in poultry processing and two modified versions of this model were tested. The present study observed a tailing phenomenon of transfer of Salmonella during a small-scale grinding process. It was, therefore, hypothesized that transfer occurred from two environmental matrices inside the grinder and a model was developed. The developed model satisfactorily predicted the observed concentrations of Salmonella during its cross-contamination in the grinding of up to 110 pork slices. The proposed model provides an important tool to examine the effect of cross-contamination in quantitative microbial risk assessments and might also be applied to various other food processes where cross-contamination is involved. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.
Directory of Open Access Journals (Sweden)
Jae Chung Park
2017-06-01
Full Text Available The Andong and Imha reservoirs in South Korea are connected by a water transfer tunnel. The turbidity of the Imha reservoir is much higher than that of the Andong reservoir. Thus, it is necessary to examine the movement of turbidity between the two reservoirs via the water transfer tunnel. The aim of this study was to investigate the effect of the water transfer tunnel on the turbidity behavior of the two connecting reservoirs and to further understand the effect of reservoir turbidity distribution as a function of the selective withdrawal depth. This study applied the CE-QUAL-W2, a water quality and 2-dimensional hydrodynamic model, for simulating the hydrodynamic processes of the two reservoirs. Results indicate that, in the Andong reservoir, the turbidity of the released water with the water transfer tunnel was similar to that without the tunnel. However, in the Imha reservoir, the turbidity of the released water with the water transfer tunnel was lower than that without the tunnel. This can be attributed to the higher capacity of the Andong reservoir, which has double the storage of the Imha reservoir. Withdrawal turbidity in the Imha reservoir was investigated using the water transfer tunnel. This study applied three withdrawal selections as elevation (EL. 141.0 m, 146.5 m, and 152.0 m. The highest withdrawal turbidity resulted in EL. 141.0 m, which indicates that the high turbidity current is located at a vertical depth of about 20–30 m because of the density difference. These results will be helpful for understanding the release and selective withdrawal turbidity behaviors for a water transfer tunnel between two reservoirs.
The role of a convective surface in models of the radiative heat transfer in nanofluids
Energy Technology Data Exchange (ETDEWEB)
Rahman, M.M., E-mail: mansurdu@yahoo.com; Al-Mazroui, W.A.; Al-Hatmi, F.S.; Al-Lawatia, M.A.; Eltayeb, I.A.
2014-08-15
Highlights: • The role of a convective surface in modelling with nanofluids is investigated over a wedge. • Surface convection significantly controls the rate of heat transfer in nanofluid. • Increased volume fraction of nanoparticles to the base-fluid may not always increase the rate of heat transfer. • Effect of nanoparticles solid volume fraction depends on the types of constitutive materials. • Higher heat transfer in nanofluids is found in a moving wedge rather than in a static wedge. - Abstract: Nanotechnology becomes the core of the 21st century. Nanofluids are important class of fluids which help advancing nanotechnology in various ways. Convection in nanofluids plays a key role in enhancing the rate of heat transfer either for heating or cooling nanodevices. In this paper, we investigate theoretically the role of a convective surface on the heat transfer characteristics of water-based nanofluids over a static or moving wedge in the presence of thermal radiation. Three different types of nanoparticles, namely copper Cu, alumina Al{sub 2}O{sub 3} and titanium dioxide TiO{sub 2} are considered in preparation of nanofluids. The governing nonlinear partial differential equations are made dimensionless with the similarity transformations. Numerical simulations are carried out through the very robust computer algebra software MAPLE 13 to investigate the effects of various pertinent parameters on the flow field. The obtained results presented graphically as well as in tabular form and discussed from physical and engineering points of view. The results show that the rate of heat transfer in a nanofluid in the presence of thermal radiation significantly depends on the surface convection parameter. If the hot fluid side surface convection resistance is lower than the cold fluid side surface convection resistance, then increased volume fraction of the nanoparticles to the base fluid may reduces the heat transfer rate rather than increases from the surface of
Worthington, Thomas A.; Zhang, T.; Logue, Daniel R.; Mittelstet, Aaron R.; Brewer, Shannon K.
2016-01-01
Truncated distributions of pelagophilic fishes have been observed across the Great Plains of North America, with water use and landscape fragmentation implicated as contributing factors. Developing conservation strategies for these species is hindered by the existence of multiple competing flow regime hypotheses related to species persistence. Our primary study objective was to compare the predicted distributions of one pelagophil, the Arkansas River Shiner Notropis girardi, constructed using different flow regime metrics. Further, we investigated different approaches for improving temporal transferability of the species distribution model (SDM). We compared four hypotheses: mean annual flow (a baseline), the 75th percentile of daily flow, the number of zero-flow days, and the number of days above 55th percentile flows, to examine the relative importance of flows during the spawning period. Building on an earlier SDM, we added covariates that quantified wells in each catchment, point source discharges, and non-native species presence to a structured variable framework. We assessed the effects on model transferability and fit by reducing multicollinearity using Spearman’s rank correlations, variance inflation factors, and principal component analysis, as well as altering the regularization coefficient (β) within MaxEnt. The 75th percentile of daily flow was the most important flow metric related to structuring the species distribution. The number of wells and point source discharges were also highly ranked. At the default level of β, model transferability was improved using all methods to reduce collinearity; however, at higher levels of β, the correlation method performed best. Using β = 5 provided the best model transferability, while retaining the majority of variables that contributed 95% to the model. This study provides a workflow for improving model transferability and also presents water-management options that may be considered to improve the
Review and assessment of the database and numerical modeling for turbine heat transfer
Gladden, H. J.; Simoneau, R. J.
1989-01-01
The objectives of the NASA Hot Section Technology (HOST) Turbine Heat Transfer subproject were to obtain a better understanding of the physics of the aerothermodynamic phenomena and to assess and improve the analytical methods used to predict the flow and heat transfer in high-temperature gas turbines. At the time the HOST project was initiated, an across-the-board improvement in turbine design technology was needed. A building-block approach was utilized and the research ranged from the study of fundamental phenomena and modeling to experiments in simulated real engine environments. Experimental research accounted for approximately 75 percent of the funding while the analytical efforts were approximately 25 percent. A healthy government/industry/university partnership, with industry providing almost half of the research, was created to advance the turbine heat transfer design technology base.
Homogenization of some radiative heat transfer models: application to gas-cooled reactor cores
International Nuclear Information System (INIS)
El Ganaoui, K.
2006-09-01
In the context of homogenization theory we treat some heat transfer problems involving unusual (according to the homogenization) boundary conditions. These problems are defined in a solid periodic perforated domain where two scales (macroscopic and microscopic) are to be taken into account and describe heat transfer by conduction in the solid and by radiation on the wall of each hole. Two kinds of radiation are considered: radiation in an infinite medium (non-linear problem) and radiation in cavity with grey-diffuse walls (non-linear and non-local problem). The derived homogenized models are conduction problems with an effective conductivity which depend on the considered radiation. Thus we introduce a framework (homogenization and validation) based on mathematical justification using the two-scale convergence method and numerical validation by simulations using the computer code CAST3M. This study, performed for gas cooled reactors cores, can be extended to other perforated domains involving the considered heat transfer phenomena. (author)
Heat transfer and pressure drop of a reactor fuel element model with polyzonal spiral finning
Energy Technology Data Exchange (ETDEWEB)
Oka, S; Becirspahic, S [Institute of Nuclear Sciences Boris Kidric, Heat Transfer Department, Vinca, Beograd (Serbia and Montenegro)
1964-10-15
Heat transfer and pressure drop of a reactor fuel element model with polyzonal spiral finning have been investigated. The St-number distribution over length and perimeter of he finning are given. The mean and minimum St{sub k}-number are plotted against the Re-number. The influence of the gap between two fuel elements upon heat transfer and pressure drop, in dependence on the Re-number, and the influence of the length of the fuel element on pressure drop across the gap are shown. The influence of the relative position of the splitters of two neighboring fuel elements on pressure drop and heat transfer is shown. The investigations were performed in the Re-number range 15,000 to 100,000 (author)
Directory of Open Access Journals (Sweden)
Sergeev Daniil
2017-01-01
Full Text Available The processes of momentum and heat transfer between ocean and atmosphere in the boundary layer were investigated within laboratory modeling for a wide range of wind speed and surface wave including hurricane conditions. Experiments were carried out on the Wind-Wave Flume of the Large Thermostratified Tank of IAP RAS. A special net located under the surface at different depths allows to vary parameters of surface waves independently on wind parameters. Theory of self-similarity of air flow parameters in the flume was used to calculate values aerodynamic and heat transfer coefficients from the measured velocity and temperature profiles by Pito and hotfilm gauges respectively. Simultaneous measurements of surface elevation with system wire allow to obtain spectra and integral parameters of waves. It was demonstrated that in contrast to the drag coefficient, heat transfer coefficient is virtually independent of wind speed and wave parameters to the moment of the beginning of spray generation and then increases rapidly.
A fractal model for heat transfer of nanofluids by convection in a pool
Energy Technology Data Exchange (ETDEWEB)
Xiao Boqi, E-mail: xiaoboqi2006@126.co [Department of Physics and Electromechanical Engineering, Sanming University, 25 Jingdong Road, Sanming 365004 (China); Yu Boming [School of Physics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074 (China); Wang Zongchi; Chen Lingxia [Department of Physics and Electromechanical Engineering, Sanming University, 25 Jingdong Road, Sanming 365004 (China)
2009-11-02
Based on the fractal distribution of nanoparticles, a fractal model for heat transfer of nanofluids is presented in the Letter. Considering heat convection between nanoparticles and liquids due to the Brownian motion of nanoparticles in fluids, the formula of calculating heat flux of nanofluids by convection is given. The proposed model is expressed as a function of the average size of nanoparticle, concentration of nanoparticle, fractal dimension of nanoparticle, temperature and properties of fluids. It is shown that the fractal model is effectual according to a good agreement between the model predictions and experimental data.
A fractal model for heat transfer of nanofluids by convection in a pool
International Nuclear Information System (INIS)
Xiao Boqi; Yu Boming; Wang Zongchi; Chen Lingxia
2009-01-01
Based on the fractal distribution of nanoparticles, a fractal model for heat transfer of nanofluids is presented in the Letter. Considering heat convection between nanoparticles and liquids due to the Brownian motion of nanoparticles in fluids, the formula of calculating heat flux of nanofluids by convection is given. The proposed model is expressed as a function of the average size of nanoparticle, concentration of nanoparticle, fractal dimension of nanoparticle, temperature and properties of fluids. It is shown that the fractal model is effectual according to a good agreement between the model predictions and experimental data.
CFD modeling of heat transfer performance of MgO-water nanofluid under turbulent flow
Davarnejad, Reza; Jamshidzadeh, Maryam
2015-01-01
In this paper, Computational fluid dynamics (CFD) modeling of turbulent heat transfer behavior of Magnesium Oxide-water nanofluid in a circular tube was studied. The modeling was two dimensional under k–ε turbulence model. The base fluid was pure water and the volume fraction of nanoparticles in the base fluid was 0.0625%, 0.125%, 0.25%, 0.5% and 1%. The applied Reynolds number range was 3000–19000. Three individual models including single phase, Volume of Fluid (VOF) and mixture were used. T...
International Nuclear Information System (INIS)
Christensen, Kristi; Rutledge, Veronica; Garn, Troy
2011-01-01
In support of the Nuclear Energy Advanced Modeling Simulation Safeguards and Separations (NEAMS SafeSep) program, the Idaho National Laboratory (INL) worked in collaboration with Los Alamos National Laboratory (LANL) to further a modeling effort designed to predict mass transfer behavior for selected metal species between individual dispersed drops and a continuous phase in a two phase liquid-liquid extraction (LLE) system. The purpose of the model is to understand the fundamental processes of mass transfer that occur at the drop interface. This fundamental understanding can be extended to support modeling of larger LLE equipment such as mixer settlers, pulse columns, and centrifugal contactors. The work performed at the INL involved gathering the necessary experimental data to support the modeling effort. A custom experimental apparatus was designed and built for performing drop contact experiments to measure mass transfer coefficients as a function of contact time. A high speed digital camera was used in conjunction with the apparatus to measure size, shape, and velocity of the drops. In addition to drop data, the physical properties of the experimental fluids were measured to be used as input data for the model. Physical properties measurements included density, viscosity, surface tension and interfacial tension. Additionally, self diffusion coefficients for the selected metal species in each experimental solution were measured, and the distribution coefficient for the metal partitioning between phases was determined. At the completion of this work, the INL has determined the mass transfer coefficient and a velocity profile for drops rising by buoyancy through a continuous medium under a specific set of experimental conditions. Additionally, a complete set of experimentally determined fluid properties has been obtained. All data will be provided to LANL to support the modeling effort.
Visible spectroscopy calibration transfer model in determining pH of Sala mangoes
International Nuclear Information System (INIS)
Yahaya, O.K.M.; MatJafri, M.Z.; Aziz, A.A.; Omar, A.F.
2015-01-01
The purpose of this study is to compare the efficiency of calibration transfer procedures between three spectrometers involving two Ocean Optics Inc. spectrometers, namely, QE65000 and Jaz, and also, ASD FieldSpec 3 in measuring the pH of Sala mango by visible reflectance spectroscopy. This study evaluates the ability of these spectrometers in measuring the pH of Sala mango by applying similar calibration algorithms through direct calibration transfer. This visible reflectance spectroscopy technique defines a spectrometer as a master instrument and another spectrometer as a slave. The multiple linear regression (MLR) of calibration model generated using the QE65000 spectrometer is transferred to the Jaz spectrometer and vice versa for Set 1. The same technique is applied for Set 2 with QE65000 spectrometer is transferred to the FieldSpec3 spectrometer and vice versa. For Set 1, the result showed that the QE65000 spectrometer established a calibration model with higher accuracy than that of the Jaz spectrometer. In addition, the calibration model developed on Jaz spectrometer successfully predicted the pH of Sala mango, which was measured using QE65000 spectrometer, with a root means square error of prediction RMSEP = 0.092 pH and coefficients of determination R 2 = 0.892. Moreover, the best prediction result is obtained for Set 2 when the calibration model developed on QE65000 spectrometer is successfully transferred to FieldSpec 3 with R 2 = 0.839 and RMSEP = 0.16 pH
Gas transfer under breaking waves: experiments and an improved vorticity-based model
Directory of Open Access Journals (Sweden)
V. K. Tsoukala
2008-07-01
Full Text Available In the present paper a modified vorticity-based model for gas transfer under breaking waves in the absence of significant wind forcing is presented. A theoretically valid and practically applicable mathematical expression is suggested for the assessment of the oxygen transfer coefficient in the area of wave-breaking. The proposed model is based on the theory of surface renewal that expresses the oxygen transfer coefficient as a function of both the wave vorticity and the Reynolds wave number for breaking waves. Experimental data were collected in wave flumes of various scales: a small-scale experiments were carried out using both a sloping beach and a rubble-mound breakwater in the wave flume of the Laboratory of Harbor Works, NTUA, Greece; b large-scale experiments were carried out with a sloping beach in the wind-wave flume of Delft Hydraulics, the Netherlands, and with a three-layer rubble mound breakwater in the Schneideberg Wave Flume of the Franzius Institute, University of Hannover, Germany. The experimental data acquired from both the small- and large-scale experiments were in good agreement with the proposed model. Although the apparent transfer coefficients from the large-scale experiments were lower than those determined from the small-scale experiments, the actual oxygen transfer coefficients, as calculated using a discretized form of the transport equation, are in the same order of magnitude for both the small- and large-scale experiments. The validity of the proposed model is compared to experimental results from other researchers. Although the results are encouraging, additional research is needed, to incorporate the influence of bubble mediated gas exchange, before these results are used for an environmental friendly design of harbor works, or for projects involving waste disposal at sea.
Complete heat transfer solutions of an insulated regular polygonal pipe by using a PWTR model
International Nuclear Information System (INIS)
Wong, K.-L.; Chou, H.-M.; Li, Y.-H.
2004-01-01
The heat transfer characteristics for insulated long regular polygonal (including circular) pipes are analyzed by using the same PWRT model in the present study as that used by Chou and Wong previously [Energy Convers. Manage. 44 (4) (2003) 629]. The thermal resistance of the inner convection term and the pipe conduction term in the heat transfer rate are not neglected in the present study. Thus, the complete heat transfer solution will be obtained. The present results can be applied more extensively to practical situations, such as heat exchangers. The results of the critical thickness t cr and the neutral thickness t e are independent of the values of J (generated by the combined effect of the inner convection term and the pipe conduction term). However, the heat transfer rates are dependent on the values of J. The present study shows that the thermal resistance of the inner convection term and the pipe conduction term cannot be neglected in the heat transfer equation in situations of low to medium inner convection coefficients h i and/or low to medium pipe conductivities K, especially in situations with large pipe sizes or/and great outer convection coefficients h 0
Evaluation of empirical heat transfer models using TFG heat flux sensors
International Nuclear Information System (INIS)
De Cuyper, T.; Broekaert, S.; Chana, K.; De Paepe, M.; Verhelst, S.
2017-01-01
Thermodynamic engine cycle models are used to support the development of the internal combustion engine (ICE) in a cost and time effective manner. The sub model which describes the in-cylinder heat transfer from the working gases to the combustion chamber walls plays an important role in the accuracy of these simulation tools. The heat transfer affects the power output, engine efficiency and emissions of the engine. The most common heat transfer models in engine research are the models of Annand and Woschni. These models provide an instantaneous spatial averaged heat flux. In this research, prototype thin film gauge (TFG) heat flux sensors are used to capture the transient in-cylinder heat flux behavior within a production spark ignition (SI) engine as they are small, robust and able to capture the highly transient temperature swings. An inlet valve and two different zones of the cylinder head are instrumented with multiple TFG sensors. The heat flux traces are used to calculate the convection coefficient which includes all information of the convective heat transfer phenomena inside the combustion chamber. The implementation of TFG sensors inside the combustion chamber and the signal processing technique are discussed. The heat transfer measurements are used to analyze the spatial variation in heat flux under motored and fired operation. Spatial variation in peak heat flux was observed even under motored operation. Under fired operation the observed spatial variation is mainly driven by the flame propagation. Next, the paper evaluates the models of Annand and Woschni. These models fail to predict the total heat loss even with calibration of the models coefficients using a reference motored operating condition. The effect of engine speed and inlet pressure is analyzed under motored operation after calibration of the models. The models are able to predict the trend in peak heat flux value for a varying engine speed and inlet pressure. Next, the accuracy of the
Research on heat and mass transfer model for passive containment cooling system
International Nuclear Information System (INIS)
Jiang Xiaowei; Yu Hongxing; Sun Yufa; Huang Daishun
2013-01-01
Different with the traditional dry style containment design without external cooling, the PCCS design increased the temperature difference between the wall and the containment atmosphere significantly, and also the absolute temperature of the containment surfaces will be lower, affecting properties relevant in the condensation process. A research on the heat and mass transfer model has been done in this paper, especially the improvement on the condensation and evaporation model in the presence of noncondensable gases. Firstly, the Peterson's diffusion layer model was proved to equivalent to the stagnant film model adopted by CONTAIN code using the Clausius-Clapeyron equation, then a factor which can be used to stagnant film model was derived from the comparison between the Y.Liao's generalized diffusion layer model and the Peterson's diffusion layer model. Finally, the model in CONTAIN code used to compute the condensation and evaporation mass flux was modified using the factor, and the Wisconsin condensation tests and Westinghouse film evaporation on heated plate tests were simulated which had proved the improved model can predict more closer value of the heat and mass transfer coefficient to experimental value than original model. (authors)
Process-level model evaluation: a snow and heat transfer metric
Slater, Andrew G.; Lawrence, David M.; Koven, Charles D.
2017-04-01
Land models require evaluation in order to understand results and guide future development. Examining functional relationships between model variables can provide insight into the ability of models to capture fundamental processes and aid in minimizing uncertainties or deficiencies in model forcing. This study quantifies the proficiency of land models to appropriately transfer heat from the soil through a snowpack to the atmosphere during the cooling season (Northern Hemisphere: October-March). Using the basic physics of heat diffusion, we investigate the relationship between seasonal amplitudes of soil versus air temperatures due to insulation from seasonal snow. Observations demonstrate the anticipated exponential relationship of attenuated soil temperature amplitude with increasing snow depth and indicate that the marginal influence of snow insulation diminishes beyond an effective snow depth of about 50 cm. A snow and heat transfer metric (SHTM) is developed to quantify model skill compared to observations. Land models within the CMIP5 experiment vary widely in SHTM scores, and deficiencies can often be traced to model structural weaknesses. The SHTM value for individual models is stable over 150 years of climate, 1850-2005, indicating that the metric is insensitive to climate forcing and can be used to evaluate each model's representation of the insulation process.
Modelling air pollution transfers in the Fos-Sur-Mer area
International Nuclear Information System (INIS)
Dibi, Niagne Martin
1985-01-01
A 'puff' gaussian model with determined standard deviations based on transfer times of two classes of vertical stability of the atmosphere was developed in order to evaluate the atmospheric dispersion of industrial discharges in the Fos-sur-Mer area. This research was carried out within the framework of a large study for the processing of the data obtained during the measurement campaign organized by the European Communities. The model in its analytic form allows consideration of the main phenomena which modify the puff content during the transfer: reflectance, wet and dry deposition, physical-chemical transformation of the pollutant SO 2 . The model includes the site meteorological parameters measured in three dimensions (wind speed and direction at ground level and in altitude) and the characteristics of the different stacks. It can also calculate pollutions resulting from a short emission or from continuous emissions. Examples are presented. (author) [fr
Discussion of heat transfer phenomena in fluids at supercritical pressure with the aid of CFD models
International Nuclear Information System (INIS)
Sharabi, Medhat; Ambrosini, Walter
2009-01-01
The paper discusses heat transfer enhancement and deterioration phenomena observed in experimental data for fluids at supercritical pressure. The results obtained by the application of various CFD turbulence models in the prediction of experimental data for water and carbon dioxide flowing in circular tubes are firstly described. On this basis, the capabilities of the addressed models in predicting the observed phenomena are shortly discussed. Then, the analysis focuses on further results obtained by a low-Reynolds number k - ε model addressing one of the considered experimental apparatuses by changing the operating conditions. In particular, the usual imposed heat flux boundary condition is changed to assigned wall temperature, in order to highlight effects otherwise impossible to point out. The obtained results, supported by considerations drawn from experimental information, allow comparing the trends observed for heat transfer deterioration at supercritical pressure with those typical of the thermal crisis in boiling systems, clarifying old concepts of similarity among them
Predictive Modelling of Phase-Transfer Catalyst Systems for Improved and Innovative Design
DEFF Research Database (Denmark)
Anantpinijwatna, Amata; Hyung Kim, Sun; Sales-Cruz, Mauricio
2016-01-01
Phase-transfer catalyst (PTC) systems contain two immiscible liquid phases with a heterogeneous PTC transferring active ion from one phase to the other for converting the reactant to the desired product, and in the process generating the inactive ion. This type of reacting systems is receiving...... increasing attention as a novel organic synthesis option due to its flexible and easier operation, higher production yield, and ability to eliminate expensive solvents, although, not eliminating the use of solvents. New mathematical models of the PTC system, which includes physical and chemical equilibrium......, reaction mechanism and unit operation has been developed. In the developed model, the PTC system is divided into four sub-systems of aqueous-organic solvent partition, inorganic salt in aqueous phase, PTC in aqueous phase, and PTC in aqueous phase. Each subsystem requires an appropriate thermodynamic model...
[Modeling of processes of heat transfer in whole-body hyperthermia].
Kinsht, D N
2006-01-01
The method of whole-body hyperthermia in which the body temperature for a short time reaches values up to 43-44 degrees C holds currently much promise. However, at body temperatures above 42 degrees C, the risks associated with the hemodynamic instability and the appearance of arrhythmia in the patient increase. A model of heat transfer has been created to increase the efficiency and safety of the immersion-convectional method of whole-body hyperthermia. This model takes into account changes in the skin blood flow and the dynamics of pulse rate depending on body temperature. The model of heat transfer adequately reflects processes of heating of the organism and can form a basis for the calculation of distribution of heat inside the organism.
A one-dimensional material transfer model for HECTR version 1.5
International Nuclear Information System (INIS)
Geller, A.S.; Wong, C.C.
1991-08-01
HECTR (Hydrogen Event Containment Transient Response) is a lumped-parameter computer code developed for calculating the pressure-temperature response to combustion in a nuclear power plant containment building. The code uses a control-volume approach and subscale models to simulate the mass, momentum, and energy transfer occurring in the containment during a loss-of-collant-accident (LOCA). This document describes one-dimensional subscale models for mass and momentum transfer, and the modifications to the code required to implement them. Two problems were analyzed: the first corresponding to a standard problem studied with previous HECTR versions, the second to experiments. The performance of the revised code relative to previous HECTR version is discussed as is the ability of the code to model the experiments. 8 refs., 5 figs., 3 tabs
A coupled model on fluid flow, heat transfer and solidification in continuous casting mold
Directory of Open Access Journals (Sweden)
Xu-bin Zhang
2017-11-01
Full Text Available Fluid flow, heat transfer and solidification of steel in the mold are so complex but crucial, determining the surface quality of the continuous casting slab. In the current study, a 2D numerical model was established by Fluent software to simulate the fluid flow, heat transfer and solidification of the steel in the mold. The VOF model and k-ε model were applied to simulate the flow field of the three phases (steel, slag and air, and solidification model was used to simulate the solidification process. The phenomena at the meniscus were also explored through interfacial tension between the liquid steel and slag as well as the mold oscillation. The model included a 20 mm thick mold to clarify the heat transfer and the temperature distribution of the mold. The simulation results show that the liquid steel flows as upper backflow and lower backflow in the mold, and that a small circulation forms at the meniscus. The liquid slag flows away from the corner at the meniscus or infiltrates into the gap between the mold and the shell with the mold oscillating at the negative strip stage or at the positive strip stage. The simulated pitch and the depth of oscillation marks approximate to the theoretical pitch and measured depth on the slab.
Cross-Species Extrapolation of Models for Predicting Lead Transfer from Soil to Wheat Grain.
Directory of Open Access Journals (Sweden)
Ke Liu
Full Text Available The transfer of Pb from the soil to crops is a serious food hygiene security problem in China because of industrial, agricultural, and historical contamination. In this study, the characteristics of exogenous Pb transfer from 17 Chinese soils to a popular wheat variety (Xiaoyan 22 were investigated. In addition, bioaccumulation prediction models of Pb in grain were obtained based on soil properties. The results of the analysis showed that pH and OC were the most important factors contributing to Pb uptake by wheat grain. Using a cross-species extrapolation approach, the Pb uptake prediction models for cultivar Xiaoyan 22 in different soil Pb levels were satisfactorily applied to six additional non-modeled wheat varieties to develop a prediction model for each variety. Normalization of the bioaccumulation factor (BAF to specific soil physico-chemistry is essential, because doing so could significantly reduce the intra-species variation of different wheat cultivars in predicted Pb transfer and eliminate the influence of soil properties on ecotoxicity parameters for organisms of interest. Finally, the prediction models were successfully verified against published data (including other wheat varieties and crops and used to evaluate the ecological risk of Pb for wheat in contaminated agricultural soils.
Numerical Modeling of the Transient Chilldown Process of a Cryogenic Propellant Transfer Line
Hartwig, Jason; Vera, Jerry
2015-01-01
Before cryogenic fuel depots can be fully realized, efficient methods with which to chill down the spacecraft transfer line and receiver tank are required. This paper presents numerical modeling of the chilldown of a liquid hydrogen tank-to-tank propellant transfer line using the Generalized Fluid System Simulation Program (GFSSP). To compare with data from recently concluded turbulent LH2 chill down experiments, seven different cases were run across a range of inlet liquid temperatures and mass flow rates. Both trickle and pulse chill down methods were simulated. The GFSSP model qualitatively matches external skin mounted temperature readings, but large differences are shown between measured and predicted internal stream temperatures. Discrepancies are attributed to the simplified model correlation used to compute two-phase flow boiling heat transfer. Flow visualization from testing shows that the initial bottoming out of skin mounted sensors corresponds to annular flow, but that considerable time is required for the stream sensor to achieve steady state as the system moves through annular, churn, and bubbly flow. The GFSSP model does adequately well in tracking trends in the data but further work is needed to refine the two-phase flow modeling to better match observed test data.
A new vector radiative transfer model as a part of SCIATRAN 3.0 software package.
Rozanov, Alexei; Rozanov, Vladimir; Burrows, John P.
The SCIATRAN 3.0 package is a result of further development of the SCIATRAN 2.x software family which, similar to previous versions, comprises a radiative transfer model and a retrieval block. A major improvement was achieved in comparison to previous software versions by adding the vector mode to the radiative transfer model. Thus, the well-established Discrete Ordinate solver can now be run in the vector mode to calculate the scattered solar radiation including polarization, i.e., to simulate all four components of the Stockes vector. Similar to the scalar version, the simulations can be performed for any viewing geometry typical for atmospheric observations in the UV-Vis-NIR spectral range (nadir, limb, off-axis, etc.) as well as for any observer position within or outside the Earth's atmosphere. Similar to the precursor version, the new model is freely available for non-commercial use via the web page of the University of Bremen. In this presentation a short description of the software package, especially of the new vector radiative transfer model will be given, including remarks on the availability for the scientific community. Furthermore, comparisons to other vector models will be shown and some example problems will be considered where the polarization of the observed radiation must be accounted for to obtain high quality results.
Multiregional coupled conduction--convection model for heat transfer in an HTGR core
International Nuclear Information System (INIS)
Giles, G.E. Jr.; Childs, K.W.; Sanders, J.P.
1978-01-01
HEXEREI is a three-dimensional, coupled conduction-convection heat transfer and multichannel fluid dynamic analysis computer code with both steady-state and transient capabilities. The program was developed to provide thermal-fluid dynamic analysis of a core following the general design for high-temperature gas-cooled reactors (HTGRs); its purpose was to provide licensing evaluations for the U.S. Nuclear Regulatory Commission. In order to efficiently model the HTGR core, the nodal geometry of HEXEREI was chosen as a regular hexagonal array perpendicular to the axis of and bounded by a right circular cylinder. The cylindrical nodal geometry surrounds the hexagonal center portion of the mesh; these two different types of nodal geometries must be connected by interface nodes to complete the accurate modeling of the HTGR core. HEXEREI will automatically generate a nodal geometry that will accurately model a complex assembly of hexagonal and irregular prisms. The accuracy of the model was proven by a comparison of computed values with analytical results for steady-state and transient heat transfer problems. HEXEREI incorporates convective heat transfer to the coolant in many parallel axial flow channels. Forced and natural convection (which permits different flow directions in parallel channels) is included in the heat transfer and fluid dynamic models. HEXEREI incorporates a variety of steady-state and transient solution techniques that can be matched with a particular problem to minimize the computational time. HEXEREI was compared with a code of similar capabilities that was based on a Cartesian mesh. This code modeled only one specific core design, and the mesh spacing was closer than that generated by HEXEREI. Good agreement was obtained with the detail provided by the representations
International Nuclear Information System (INIS)
Le Fur, J.
1989-01-01
The paper examines a method of evaluation, using numerical techniques, of the fate of radioelements released by chronic or accidental discharge into the ecosystem of the English Channel. In areas close to the reprocessing center at La Hague, a statistical study is used to establish a direct relation between quantities of ruthenium-106 released by the discharge source and concentrations of the radioelement in marine algae. A multidisciplinary model is developed for general case. The constituents studied are the liquid environment (radioelement vector), particulate matter (radioelement trap) and live macroorganisms (radioelement receptors). Dispersion of radioelements in the liquid environment is calculated using different models for estimating tidal currents (resolution of the Saint-Venant system), the transport of bodies of water and radioelement diffusion. Radioelement fixing in particulate matter is formalized using and adjustment coefficient integrated into the diffusion equation. Transfers of radioelements between the liquid phase and the organisms are modelized using a system of compartments; fluctuations in the discharge source are taken into account in the formulation. All the models are integrated into a calculation system which enables them to be used automatically in sequence. Estimates for currents and trajectories are in agreement with observations and enable short term applications of the system to be contemplated. The model of radioelement transfer to organisms is validated using a pair of experiments carried out in situ. Points remaining to be specified mainly concern the transfer to particulate matter, the calibration of the system for long term studies and certain factors to be included in the model of radioelement transfer to organisms [fr
Lute, A. C.; Luce, Charles H.
2017-11-01
The related challenges of predictions in ungauged basins and predictions in ungauged climates point to the need to develop environmental models that are transferable across both space and time. Hydrologic modeling has historically focused on modelling one or only a few basins using highly parameterized conceptual or physically based models. However, model parameters and structures have been shown to change significantly when calibrated to new basins or time periods, suggesting that model complexity and model transferability may be antithetical. Empirical space-for-time models provide a framework within which to assess model transferability and any tradeoff with model complexity. Using 497 SNOTEL sites in the western U.S., we develop space-for-time models of April 1 SWE and Snow Residence Time based on mean winter temperature and cumulative winter precipitation. The transferability of the models to new conditions (in both space and time) is assessed using non-random cross-validation tests with consideration of the influence of model complexity on transferability. As others have noted, the algorithmic empirical models transfer best when minimal extrapolation in input variables is required. Temporal split-sample validations use pseudoreplicated samples, resulting in the selection of overly complex models, which has implications for the design of hydrologic model validation tests. Finally, we show that low to moderate complexity models transfer most successfully to new conditions in space and time, providing empirical confirmation of the parsimony principal.
Verstegen, Loes; Meijdam, Lex
2016-01-01
In this paper, we incorporate a transfer mechanism into a DSGE model with a rich fiscal sector to assess the effectiveness of fiscal transfers for a monetary union, in particular for the Economic and Monetary Union. Using a heterogeneous setup, the model is estimated for the North and the South of
DEFF Research Database (Denmark)
Gunabalan, R.; Sanjeevikumar, P.; Blaabjerg, Frede
2015-01-01
This paper presents the transfer function modeling and stability analysis of two induction motors of same ratings and parameters connected in parallel. The induction motors are controlled by a single inverter and the entire drive system is modeled using transfer function in LabView. Further...
Energy Technology Data Exchange (ETDEWEB)
Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R. [Royal Institute of Technology, Stockholm (Sweden)] [and others
1995-09-01
The objective of the paper is to study heat and mass transfer processes related to core melt discharge from a reactor vessel is a severe light water reactor accident. The phenomenology of the issue includes (1) melt convection in and heat transfer from the melt pool in contact with the vessel lower head wall; (2) fluid dynamics and heat transfer of the melt flow in the growing discharge hole; and (3) multi-dimensional heat conduction in the ablating lower head wall. A program of model development, validation and application is underway (i) to analyse the dominant physical mechanisms determining characteristics of the lower head ablation process; (ii) to develop and validate efficient analytic/computational methods for estimating heat and mass transfer under phase-change conditions in irregular moving-boundary domains; and (iii) to investigate numerically the melt discharge phenomena in a reactor-scale situation, and, in particular, the sensitivity of the melt discharge transient to structural differences and various in-vessel melt progression scenarios. The paper presents recent results of the analysis and model development work supporting the simulant melt-structure interaction experiments.
Carbon dioxide stripping in aquaculture -- part II: development of gas transfer models
Colt, John; Watten, Barnaby; Pfeiffer, Tim
2012-01-01
The basic mass transfer equation for gases such as oxygen and carbon dioxide can be derived from integration of the driving force equation. Because of the physical characteristics of the gas transfer processes, slightly different models are used for aerators tested under the non steady-state procedures, than for packed columns, or weirs. It is suggested that the standard condition for carbon dioxide should be 20 °C, 1 atm, CCO2=20 mg/kg, and XCO2=0.000285. The selection of the standard condition for carbon dioxide based on a fixed mole fraction ensures that standardized carbon dioxide transfer rates will be comparable even though the value of C*CO2 in the atmosphere is increasing with time. The computation of mass transfer for carbon dioxide is complicated by the impact of water depth and gas phase enrichment on the saturation concentration within the unit, although the importance of either factor depends strongly on the specific type of aerator. For some types of aerators, the most accurate gas phase model remains to be determined for carbon dioxide. The assumption that carbon dioxide can be treated as a non-reactive gas in packed columns may apply for cold acidic waters but not for warm alkaline waters.
International Nuclear Information System (INIS)
Dauvois, Yann
2016-01-01
In the present work, the effective heat transfer properties of fibrous medium are determined by taking into account a coupling of heat conduction and radiation. A virtual, statistically homogeneous, two-phase fibrous sample has been built by stacking finite absorbing cylinders in vacuum. These cylinders are dispersed according to prescribed distribution functions defining the cylinder positions and orientations. Cylinder overlappings are allowed. Extinction, absorption and scattering are characterised by radiative statistical functions which allow the Beerian behaviour of a medium to be assessed (or not). They are accurately determined with a Monte Carlo method. Whereas the gaseous phase exhibits a Beerian behaviour, the fibre phase is strongly non Beerian. The radiative power field deposited within the fibrous material is calculated by resolving a model which couples a Generalized Radiative Transfer Equation (GRTE) and a classic Radiative Transfer Equation (RTE). The model of conduction transfer is based on a random walk method without meshing. The simulation of Brownian motion of walkers in fibres allows the energy equation to be solved. The idea of the method is to characterize the temperature in an elementary volume by the density of walkers, which roam the medium. The problem is governed by boundary conditions; A constant concentration of walkers (or a constant flux) is associated with a fixed temperature (or flux). (author) [fr
Potential for PET scanning as an aid to heat transfer modeling
International Nuclear Information System (INIS)
Samulski, T.V.; Harris, C.; Winget, J.M.; Dewhirst, M.W.
1987-01-01
Positron Emission Tomography (PET) using /sup 68/Ga labelled microspheres (15μ diam.) for quantitative imaging of perfusion is being investigated for its potential to aid in verification of parameter estimation techniques. Such techniques have been used in bioheat transfer modeling where direct measurement of perfusion has not been possible. Perfusion is needed, to utilize bioheat transfer to predict temperatures between measured points during hyperthermia therapy. A preliminary study showing that PET could be used for verification of parameter estimation was done by heating a melanoma in a dog in which multiple thermometry catheters were placed in a central plane. Microspheres were injected at the end of a one hour heat treatment session before power down. CT and PET images of the same plane were aligned so that relative counts/pixel in 2 cm regions of interest of the PET image were measured along several catheter tracks. In all tracks measured an inverse correlation was shown between relative perfusion and temperature along the catheter during thermal steady state. These data strongly imply that PET scans obtained in the manner described bear relevance to bioheat transfer and for verification of perfusion in heated tissues as estimated by heat transfer modeling
Intramolecular energy transfer at donor-acceptor interactions in model and biological membranes
International Nuclear Information System (INIS)
Umarova, Fatima T.
2011-01-01
Intramolecular triplet-triplet energy transfer between molecules of sensibilisator and photochrome for registration of protein interactions in the membrane preparation of Na,K-ATPase was investigated. Erythrosinithiocyanate (ERITC) was used as the triplet label of sensibilisator, and 4-acetoamido-4 -isothiocyanatostilbene-2,2 disullfonic acid (SITS) was used as the photochrome label. Na,K-ATPase preparations were covalently bound with ERITC in active centre of enzyme, and SITS molecules were covalently bound by NH2-groups. In model system, in chymotrypsinogene molecule, SITS and ERITC labels were used also. The cis-trans-isomerization of SITS was initiated by triplet-triplet energy transfer from light excited ERITC molecule to photochrome. The kinetics of isomerization was recorded by the SITS fluorescence measurements. The constant of rate of triplet-triplet energy transfer from ERITC to cis-isomers of SITS in Na,K-ATPase was determined as (3-7)x10 3 M -1 s -1 , and in model system it equals 1x 10 7 M 1 s -1 . The value of energy transfer between loos molecules of erythrosine and SITS in buffer solution equaled to 7x10 7 M -1 s -1 . This drop of R m y in the membrane preparation of Na,K-ATPase at 10 4 reflected the decrease in the frequency of label collisions caused by the increase in the media viscosity and steric hindrances. (author)
A finite element method based microwave heat transfer modeling of frozen multi-component foods
Pitchai, Krishnamoorthy
Microwave heating is fast and convenient, but is highly non-uniform. Non-uniform heating in microwave cooking affects not only food quality but also food safety. Most food industries develop microwavable food products based on "cook-and-look" approach. This approach is time-consuming, labor intensive and expensive and may not result in optimal food product design that assures food safety and quality. Design of microwavable food can be realized through a simulation model which describes the physical mechanisms of microwave heating in mathematical expressions. The objective of this study was to develop a microwave heat transfer model to predict spatial and temporal profiles of various heterogeneous foods such as multi-component meal (chicken nuggets and mashed potato), multi-component and multi-layered meal (lasagna), and multi-layered food with active packages (pizza) during microwave heating. A microwave heat transfer model was developed by solving electromagnetic and heat transfer equations using finite element method in commercially available COMSOL Multiphysics v4.4 software. The microwave heat transfer model included detailed geometry of the cavity, phase change, and rotation of the food on the turntable. The predicted spatial surface temperature patterns and temporal profiles were validated against the experimental temperature profiles obtained using a thermal imaging camera and fiber-optic sensors. The predicted spatial surface temperature profile of different multi-component foods was in good agreement with the corresponding experimental profiles in terms of hot and cold spot patterns. The root mean square error values of temporal profiles ranged from 5.8 °C to 26.2 °C in chicken nuggets as compared 4.3 °C to 4.7 °C in mashed potatoes. In frozen lasagna, root mean square error values at six locations ranged from 6.6 °C to 20.0 °C for 6 min of heating. A microwave heat transfer model was developed to include susceptor assisted microwave heating of a
Modeling and validating tritium transfer in a grassland ecosystem in response to {sup 3}H releases
Energy Technology Data Exchange (ETDEWEB)
Le Dizes, S.; Maro, D.; Rozet, M.; Hebert, D.; Solier, L.; Nicoulaud, V. [Institut de radioportection et de surete nucleaire - IRSN (France); Vermorel, F.; Aulagnier, C. [Electricite de France - EDF (France)
2014-07-01
Tritium ({sup 3}H) is a major radionuclide released in several forms (HTO, HT) by nuclear facilities under normal operating conditions. In terrestrial ecosystems, tritium can be found under two forms: tritium in tissue free water (TFWT) following absorption of tritiated water by leaves or roots and Organically Bound Tritium (OBT) resulting from TFWT incorporation by the plant organic matter during photosynthesis. In order to study transfers of tritium from atmospheric releases to terrestrial ecosystem such as grasslands, an in-situ laboratory has been set up by IRSN on a ryegrass field plot located 2 km downwind the AREVA NC La Hague nuclear reprocessing plant (North-West of France), as was done in the past for the assessment of transfer of radiocarbon in grasslands. The objectives of this experimental field are: (i) to better understand the OBT formation in plant by photosynthesis, (ii) to evaluate transfer processes of tritium in several forms (HT, HTO) from the atmosphere (air and rainwater) to grass and soil, (iii) to develop a modeling allowing to reproduce the dynamic response of the ecosystem to tritium atmospheric releases depending of variable environmental conditions. For this purpose, tritium activity measurements will be carried out in grass (monthly measurements of HTO, OBT), in air, rainwater, soil (daily measurements of HT, HTO) and CO{sub 2}, H{sub 2}O fluxes between soil and air compartments will be carried out. Then, the TOCATTA-c model previously developed to simulate {sup 14}C transfers to pasture on a hourly time-step basis will be adapted to take account for processes specific to tritium. The model will be tested by a comparison between simulated results and measurements. The objectives of this presentation are (1) to present the organization of the experimental design of the VATO study (Validation of TOCATTA) dedicated to transfers of tritium in a grassland ecosystem, (2) to document the major assumptions, conceptual modelling and
Analysis of mass transfer characteristics in a tubular membrane using CFD modeling.
Yang, Jixiang; Vedantam, Sreepriya; Spanjers, Henri; Nopens, Ingmar; van Lier, Jules B
2012-10-01
In contrast to the large amount of research into aerobic membrane bioreactors, little work has been reported on anaerobic membrane bioreactors (AMBRs). As to the application of membrane bioreactors, membrane fouling is a key issue. Membrane fouling generally occurs more seriously in AMBRs than in aerobic membrane bioreactors. However, membrane fouling could be managed through the application of suitable shear stress that can be introduced by the application of a two-phase flow. When the two-phase flow is applied in AMBRs, little is known about the mass transfer characteristics, which is of particular importance, in tubular membranes of AMBRs. In our present work, we have employed fluid dynamic modeling to analyze the mass transfer characteristics in the tubular membrane of a side stream AMBR in which, gas-lift two-phase flow was applied. The modeling indicated that the mass transfer capacity at the membrane surface at the noses of gas bubbles was higher than the mass transfer capacity at the tails of the bubbles, which is in contrast to the results when water instead of sludge is applied. At the given mass transfer rate, the filterability of the sludge was found to have a strong influence on the transmembrane pressure at a steady flux. In addition, the model also showed that the shear stress in the internal space of the tubular membrane was mainly around 20 Pa but could be as high as about 40 Pa due to gas bubble movements. Nonetheless, at these shear stresses a stable particle size distribution was found for sludge particles. Copyright © 2012 Elsevier Ltd. All rights reserved.
CFD modelling of convective heat transfer from a window with adjacent venetian blinds
Energy Technology Data Exchange (ETDEWEB)
Marjanovic, L. [Belgrade Univ., Belgrade (Yugoslavia). Faculty of Mechanical Engineering]|[DeMontfort Univ. (United Kingdom). Inst. of Energy and Sustainable Development; Cook, M; Hanby, V.; Rees, S. [DeMontfort Univ. (United Kingdom). Inst. of Energy and Sustainable Development
2005-07-01
There is a limited amount of 3-dimensional modeling information on the performance of glazing systems with blinds. Two-dimensional flow modeling has indicated that 1-dimensional heat transfer can lead to invalid results where 2- and 3-dimensional effects are present. In this study, a 3-dimensional numerical solution was obtained on the effect of a venetian blind on the conjugate heat transfer from an indoor window glazing system. The solution was obtained for the coupled laminar free convection and radiation heat transfer problem, including conduction along the blind slats. Continuity, momentum and energy equations for buoyant flow were solved using Computational Fluid Dynamics (CFD) software. Grey diffuse radiation exchange between the window, blind and air were considered using the Monte Carlo method. All thermophysical properties of air were assumed to be constant with the exception of density, which was modeled using the Bousinesq approximation. Both winter and summer conditions were considered. In the computational domain, the window represented an isothermal type boundary condition with no slip. The height of the domain was extended beyond the blinds to allow for inflow and outflow regions. Fluid was allowed to entrain into the domain at an ambient temperature in a direction perpendicular to the window. The results indicated that heat transfer between window and indoor air is influenced both quantitatively and qualitatively by the presence of an aluminium venetian blind, and that the cellular flow between the blind slats can have a significant effect on the convective heat transfer from the window surface that is more fully recognized and analyzed in 3 dimensions. refs., 2 tabs., 13 figs.
International Nuclear Information System (INIS)
Betchen, L.J.; Straatman, A.G.
2005-01-01
A mathematical and numerical model for the treatment of conjugate fluid flow and heat transfer problems in domains containing pure fluid, porous, and pure solid regions has been developed. The model is general and physically reasoned, and allows for local thermal non-equilibrium in the porous region. The model is developed for implementation on a simple collocated finite volume grid. Of particular novelty are the conditions implemented at the interfaces between porous regions, and those containing a pure solid or pure fluid. The model is validated by simulation of a three-dimensional porous plug problem for which experimental results are available. (author)
Modelling heat and mass transfer in bread baking with mechanical deformation
International Nuclear Information System (INIS)
Nicolas, V; Glouannec, P; Ploteau, J-P; Salagnac, P; Jury, V; Boillereaux, L
2012-01-01
In this paper, the thermo-hydric behaviour of bread during baking is studied. A numerical model has been developed with Comsol Multiphysics© software. The model takes into account the heat and mass transfers in the bread and the phenomenon of swelling. This model predicts the evolution of temperature, moisture, gas pressure and deformation in French 'baguette' during baking. Local deformation is included in equations using solid phase conservation and, global deformation is calculated using a viscous mechanic model. Boundary conditions are specified with the sole temperature model and vapour pressure estimation of the oven during baking. The model results are compared with experimental data for a classic baking. Then, the model is analysed according to physical properties of bread and solicitations for a better understanding of the interactions between different mechanisms within the porous matrix.
Marin, Pricila; Borba, Carlos Eduardo; Módenes, Aparecido Nivaldo; Espinoza-Quiñones, Fernando R; de Oliveira, Silvia Priscila Dias; Kroumov, Alexander Dimitrov
2014-01-01
Reactive blue 5G dye removal in a fixed-bed column packed with Dowex Optipore SD-2 adsorbent was modelled. Three mathematical models were tested in order to determine the limiting step of the mass transfer of the dye adsorption process onto the adsorbent. The mass transfer resistance was considered to be a criterion for the determination of the difference between models. The models contained information about the external, internal, or surface adsorption limiting step. In the model development procedure, two hypotheses were applied to describe the internal mass transfer resistance. First, the mass transfer coefficient constant was considered. Second, the mass transfer coefficient was considered as a function of the dye concentration in the adsorbent. The experimental breakthrough curves were obtained for different particle diameters of the adsorbent, flow rates, and feed dye concentrations in order to evaluate the predictive power of the models. The values of the mass transfer parameters of the mathematical models were estimated by using the downhill simplex optimization method. The results showed that the model that considered internal resistance with a variable mass transfer coefficient was more flexible than the other ones and this model described the dynamics of the adsorption process of the dye in the fixed-bed column better. Hence, this model can be used for optimization and column design purposes for the investigated systems and similar ones.
Numerical analysis of thermal response tests with a groundwater flow and heat transfer model
Energy Technology Data Exchange (ETDEWEB)
Raymond, J.; Therrien, R. [Departement de Geologie et de Genie Ggeologique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Gosselin, L. [Departement de Genie Mecanique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Lefebvre, R. [Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, 490 de la Couronne, Quebec (Qc) G1K 9A9 (Canada)
2011-01-15
The Kelvin line-source equation, used to analyze thermal response tests, describes conductive heat transfer in a homogeneous medium with a constant temperature at infinite boundaries. The equation is based on assumptions that are valid for most ground-coupled heat pump environments with the exception of geological settings where there is significant groundwater flow, heterogeneous distribution of subsurface properties, a high geothermal gradient or significant atmospheric temperature variations. To address these specific cases, an alternative method to analyze thermal response tests was developed. The method consists in estimating parameters by reproducing the output temperature signal recorded during a test with a numerical groundwater flow and heat transfer model. The input temperature signal is specified at the entrance of the ground heat exchanger, where flow and heat transfer are computed in 2D planes representing piping and whose contributions are added to the 3D porous medium. Results obtained with this method are compared to those of the line-source model for a test performed under standard conditions. A second test conducted in waste rock at the South Dump of the Doyon Mine, where conditions deviate from the line-source assumptions, is analyzed with the numerical model. The numerical model improves the representation of the physical processes involved during a thermal response test compared to the line-source equation, without a significant increase in computational time. (author)
Modelling mass and heat transfer in nano-based cancer hyperthermia.
Nabil, M; Decuzzi, P; Zunino, P
2015-10-01
We derive a sophisticated mathematical model for coupled heat and mass transport in the tumour microenvironment and we apply it to study nanoparticle delivery and hyperthermic treatment of cancer. The model has the unique ability of combining the following features: (i) realistic vasculature; (ii) coupled capillary and interstitial flow; (iii) coupled capillary and interstitial mass transfer applied to nanoparticles; and (iv) coupled capillary and interstitial heat transfer, which are the fundamental mechanisms governing nano-based hyperthermic treatment. This is an improvement with respect to previous modelling approaches, where the effect of blood perfusion on heat transfer is modelled in a spatially averaged form. We analyse the time evolution and the spatial distribution of particles and temperature in a tumour mass treated with superparamagnetic nanoparticles excited by an alternating magnetic field. By means of numerical experiments, we synthesize scaling laws that illustrate how nano-based hyperthermia depends on tumour size and vascularity. In particular, we identify two distinct mechanisms that regulate the distribution of particle and temperature, which are characterized by perfusion and diffusion, respectively.
Macroscopic modeling for heat and water vapor transfer in dry snow by homogenization.
Calonne, Neige; Geindreau, Christian; Flin, Frédéric
2014-11-26
Dry snow metamorphism, involved in several topics related to cryospheric sciences, is mainly linked to heat and water vapor transfers through snow including sublimation and deposition at the ice-pore interface. In this paper, the macroscopic equivalent modeling of heat and water vapor transfers through a snow layer was derived from the physics at the pore scale using the homogenization of multiple scale expansions. The microscopic phenomena under consideration are heat conduction, vapor diffusion, sublimation, and deposition. The obtained macroscopic equivalent model is described by two coupled transient diffusion equations including a source term arising from phase change at the pore scale. By dimensional analysis, it was shown that the influence of such source terms on the overall transfers can generally not be neglected, except typically under small temperature gradients. The precision and the robustness of the proposed macroscopic modeling were illustrated through 2D numerical simulations. Finally, the effective vapor diffusion tensor arising in the macroscopic modeling was computed on 3D images of snow. The self-consistent formula offers a good estimate of the effective diffusion coefficient with respect to the snow density, within an average relative error of 10%. Our results confirm recent work that the effective vapor diffusion is not enhanced in snow.
International Nuclear Information System (INIS)
Janecky, D.R.
1988-01-01
A computational modeling code (EQPSreverse arrowS) has been developed to examine sulfur isotopic distribution pathways coupled with calculations of chemical mass transfer pathways. A post processor approach to EQ6 calculations was chosen so that a variety of isotopic pathways could be examined for each reaction pathway. Two types of major bounding conditions were implemented: (1) equilibrium isotopic exchange between sulfate and sulfide species or exchange only accompanying chemical reduction and oxidation events, and (2) existence or lack of isotopic exchange between solution species and precipitated minerals, parallel to the open and closed chemical system formulations of chemical mass transfer modeling codes. All of the chemical data necessary to explicitly calculate isotopic distribution pathways is generated by most mass transfer modeling codes and can be input to the EQPS code. Routines are built in to directly handle EQ6 tabular files. Chemical reaction models of seafloor hydrothermal vent processes and accompanying sulfur isotopic distribution pathways illustrate the capabilities of coupling EQPSreverse arrowS with EQ6 calculations, including the extent of differences that can exist due to the isotopic bounding condition assumptions described above. 11 refs., 2 figs
Wang, Da-Lin; Qi, Hong
Semi-transparent materials (such as IR optical windows) are widely used for heat protection or transfer, temperature and image measurement, and safety in energy , space, military, and information technology applications. They are used, for instance, ceramic coatings for thermal barriers of spacecrafts or gas turbine blades, and thermal image observation under extreme or some dangerous environments. In this paper, the coupled conduction and radiation heat transfer model is established to describe temperature distribution of semitransparent thermal barrier medium within the aerothermal environment. In order to investigate this numerical model, one semi-transparent sample with black coating was considered, and photothermal properties were measured. At last, Finite Volume Method (FVM) was used to solve the coupled model, and the temperature responses from the sample surfaces were obtained. In addition, experiment study was also taken into account. In the present experiment, aerodynamic heat flux was simulated by one electrical heater, and two experiment cases were designed in terms of the duration of aerodynamic heating. One case is that the heater irradiates one surface of the sample continually until the other surface temperature up to constant, and the other case is that the heater works only 130 s. The surface temperature responses of these two cases were recorded. Finally, FVM model of the coupling conduction-radiation heat transfer was validated based on the experiment study with relative error less than 5%.
Two-temperature chemically non-equilibrium modelling of transferred arcs
International Nuclear Information System (INIS)
Baeva, M; Kozakov, R; Gorchakov, S; Uhrlandt, D
2012-01-01
A two-temperature chemically non-equilibrium model describing in a self-consistent manner the heat transfer, the plasma chemistry, the electric and magnetic field in a high-current free-burning arc in argon has been developed. The model is aimed at unifying the description of a thermionic tungsten cathode, a flat copper anode, and the arc plasma including the electrode sheath regions. The heat transfer in the electrodes is coupled to the plasma heat transfer considering the energy fluxes onto the electrode boundaries with the plasma. The results of the non-equilibrium model for an arc current of 200 A and an argon flow rate of 12 slpm are presented along with results obtained from a model based on the assumption of local thermodynamic equilibrium (LTE) and from optical emission spectroscopy. The plasma shows a near-LTE behaviour along the arc axis and in a region surrounding the axis which becomes wider towards the anode. In the near-electrode regions, a large deviation from LTE is observed. The results are in good agreement with experimental findings from optical emission spectroscopy. (paper)
A model for the transfer of alkaline earth elements to the fetus
International Nuclear Information System (INIS)
Fell, T.P.; Harrison, J.D.; Leggett, R.W.
2001-01-01
A biokinetic model has been developed for the transfer of calcium, strontium, barium and radium to the human fetus. For the mother, ICRP models were adapted for pregnancy to include increases in gastrointestinal absorption, urinary excretion and bone turnover rates. The fetus was modelled with blood, soft tissue and bone compartments. Fetal requirements for Ca were determined by skeletal calcification, and recycling between fetal and maternal blood was included. Daily transfer of Sr, Ba and Ra to the fetus was taken to be lower than for Ca by factors of 0.6 for Sr and 0.4 for Ba and Ra. For acute intakes in late pregnancy at 35 weeks after conception, when maximum transfer occurs, the model predicts whole-body fetus:mother concentration ratios (C F :C M ) of 18 for Ca, 8 for Sr and 2 for Ba and Ra, respectively. Estimates of committed equivalent doses to the red bone marrow of offspring, including in utero and postnatal dose, after maternal ingestion in late pregnancy, were greater than corresponding doses in adults by factors of 20-30 for 45 Ca, 2-3 for 90 Sr and 3-4 for 226 Ra but slightly lower (0.8-0.9) for 133 Ba. (author)
Probability theory for 3-layer remote sensing radiative transfer model: univariate case.
Ben-David, Avishai; Davidson, Charles E
2012-04-23
A probability model for a 3-layer radiative transfer model (foreground layer, cloud layer, background layer, and an external source at the end of line of sight) has been developed. The 3-layer model is fundamentally important as the primary physical model in passive infrared remote sensing. The probability model is described by the Johnson family of distributions that are used as a fit for theoretically computed moments of the radiative transfer model. From the Johnson family we use the SU distribution that can address a wide range of skewness and kurtosis values (in addition to addressing the first two moments, mean and variance). In the limit, SU can also describe lognormal and normal distributions. With the probability model one can evaluate the potential for detecting a target (vapor cloud layer), the probability of observing thermal contrast, and evaluate performance (receiver operating characteristics curves) in clutter-noise limited scenarios. This is (to our knowledge) the first probability model for the 3-layer remote sensing geometry that treats all parameters as random variables and includes higher-order statistics. © 2012 Optical Society of America
A CFD model for determining mixing and mass transfer in a high power agitated bioreactor
DEFF Research Database (Denmark)
Bach, Christian; Albæk, Mads O.; Stocks, Stuart M.
performance of a high power agitated pilot scale bioreactor has been characterized using a novel combination of computational fluid dynamics (CFD) and experimental investigations. The effect of turbulence inside the vessel was found to be most efficiently described by using the k-ε model with regards...... simulations, and the overall mass transfer coefficient was found to be in accordance with experimental data. This work illustrates the possibility of predicting the hydrodynamic performance of an agitated bioreactor using validated CFD models. These models can be applied in the testing of new bioreactor...
Directory of Open Access Journals (Sweden)
Zeeshan Nawaz
2009-04-01
Full Text Available The present research focuses to develop mathematical model for the removal of iron (magnetite by ion-exchange resin from primary heat transfer loop of process industries. This mathematical model is based on operating capacities (that’s provide more effective design as compared to loading capacity from static laboratory tests. Results showed non-steady state distribution of external Fe2+ and limitations imposed on operating conditions, these conditions includes; loading and elution cycle time, flow rate, concentration of both loading and removal, volume of resin required. Number of generalized assumptions was made under shortcut modeling techniques to overcome the gap of theoretical and actual process design.
Heat transfer optimization of SCO2 porous flow based on Brinkman model
Directory of Open Access Journals (Sweden)
Lin David T.W.
2016-01-01
Full Text Available The purpose of this study is to obtain the optimal operating condition in order to find the maximum supercritical CO2 heat extraction in the enhanced geothermal system (EGS. In this study, the heat transfer model conjugated with the Brinkman model is used to evaluate the thermal behavior in the reservoir of the EGS. This numerical model is validated by experiment. Optimization is processed based on the Nelder-Mead approach. The optimal operating conditions are proposed with different pressure, porosity. This study will build the optimal platform of heat source of geothermal power plant.
Modelling of the processes of heat and mass transfer in adiabatic steam and drop flows
International Nuclear Information System (INIS)
Andrizhievskij, A.A.; Mikhalevich, A.A.; Nesterenko, V.B.; Trifonov, A.G.
1983-01-01
The mathematical models for investigating the local and integral characteristics of heat and mass transfer processes during simultaneous motion of adiabatic steam and drop flow and a flux of impurity particles are given. The mathematical model is constrUcted on the basis of one-dimensional stationary eqUations of conservation of mass, thermal energy and momentum of liquid and vapor phases. Dispersion composition of condensed moisture is described by the Nukiyama-Tanasava distribution function formed taking into account the Veber number critical value. Equations of motion and mass balance conservation for impurity particles are included into the mathematical model. These equations are considered as additional inactive phase
MODELLING OF SCENARIOS OF THE CRISIS PHENOMENA TRANSFER AMONG FINANCIAL MARKETS
Directory of Open Access Journals (Sweden)
Inna Strelchenko
2017-11-01
Full Text Available The phenomenon of crisis transference among financial markets in different countries is especially evident during the global financial crisis of 2007-2009. Abnormal imbalances emerged in the market of secondary financial instruments in the United States in the second half of 2006 and quickly spread to the financial markets of most countries of the world. However, the rate of fall of the main macroeconomic indicators, the duration of the latent period (the time between the date of the beginning of the financial crisis in the source country and date of the recorded fall in GDP of the country that is subjected to “contagion” (Strelchenko, 2016, and recovery period are substantially different. To generate an effective economic policy actually, there is a task of determining the possible scenarios of transferring crisis. The research subject is a process of transfer of the crisis phenomena among the financial markets of countries with different levels of economic development. Methodology. The paper presents the results of a study on the differentiation of the financial markets reactions to the crisis transfer. To build the corresponding classification model, self-organization Kohonen neural networks are used. The purpose of this work is to build a neural network model for clustering economies according to the response to external financial shocks. This model allows predicting the scenarios of transferring crisis among financial markets. Conclusion. As a result of the study, there is built a neural network with the architecture of the Kohonen map. The neural network has one hidden layer consisting of six neurons and has a hexagonal structure. Six clusters describe six possible scenarios of the economy dynamics under the impact of the transfer of crises. Cluster number one and two unite countries characterized by a short period of economic recovery and return of the main macroeconomic indicators to the precrisis levels. A longer recovery period and
SCDAP/RELAP5 modeling of heat transfer and flow losses in lower head porous debris. Rev. 1
International Nuclear Information System (INIS)
Siefken, L.J.; Coryell, E.W.; Paik, S.; Kuo, H.
1999-01-01
Designs are described for implementing models for calculating the heat transfer and flow losses in porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and nonporous debris that results from core material slumping into the lower head. Currently, the COUPLE model has the capability to model convective and radiative heat transfer from the surfaces of nonporous debris in a detailed manner and to model only in a simplistic manner the heat transfer from porous debris. In order to advance beyond the simplistic modeling for porous debris, designs are developed for detailed calculations of heat transfer and flow losses in porous debris. Correlations are identified for convective heat transfer in porous debris for the following modes of heat transfer; (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, and (5) film boiling. Interphase heat transfer is modeled in an approximate ma nner. Designs are described for models to calculate the flow losses and interphase drag of fluid flowing through the interstices of the porous debris, and to apply these variables in the momentum equations in the RELAP5 part of the code. Since the models for heat transfer and flow losses in porous debris in the lower head are designed for general application, a design is also described for implementation of these models to the analysis of porous debris in the core region. A test matrix is proposed for assessing the capability of the implemented models to calculate the heat transfer and flow losses in porous debris. The implementation of the models described in this report is expected to improve the COUPLE code calculation of the temperature distribution in porous debris and in the lower head that supports the debris. The implementation of these models is also expected to improve the calculation of the temperature and flow distribution in porous debris in the core region
Broderick, Ciaran; Matthews, Tom; Wilby, Robert L.; Bastola, Satish; Murphy, Conor
2016-10-01
Understanding hydrological model predictive capabilities under contrasting climate conditions enables more robust decision making. Using Differential Split Sample Testing (DSST), we analyze the performance of six hydrological models for 37 Irish catchments under climate conditions unlike those used for model training. Additionally, we consider four ensemble averaging techniques when examining interperiod transferability. DSST is conducted using 2/3 year noncontinuous blocks of (i) the wettest/driest years on record based on precipitation totals and (ii) years with a more/less pronounced seasonal precipitation regime. Model transferability between contrasting regimes was found to vary depending on the testing scenario, catchment, and evaluation criteria considered. As expected, the ensemble average outperformed most individual ensemble members. However, averaging techniques differed considerably in the number of times they surpassed the best individual model member. Bayesian Model Averaging (BMA) and the Granger-Ramanathan Averaging (GRA) method were found to outperform the simple arithmetic mean (SAM) and Akaike Information Criteria Averaging (AICA). Here GRA performed better than the best individual model in 51%-86% of cases (according to the Nash-Sutcliffe criterion). When assessing model predictive skill under climate change conditions we recommend (i) setting up DSST to select the best available analogues of expected annual mean and seasonal climate conditions; (ii) applying multiple performance criteria; (iii) testing transferability using a diverse set of catchments; and (iv) using a multimodel ensemble in conjunction with an appropriate averaging technique. Given the computational efficiency and performance of GRA relative to BMA, the former is recommended as the preferred ensemble averaging technique for climate assessment.
Energy Technology Data Exchange (ETDEWEB)
Busigin, A. [NITEK USA Inc., Ocala, FL (United States)
2015-03-15
Liquid Phase Catalytic Exchange (LPCE) is a key technology used in water detritiation systems. Rigorous simulation of LPCE is complicated when a column may have both hydrogen and deuterium present in significant concentrations in different sections of the column. This paper presents a general mass transfer model for a homogenous packed bed LPCE column as a set of differential equations describing composition change, and equilibrium equations to define the mass transfer driving force within the column. The model is used to show the effect of deuterium buildup in the bottom of an LPCE column from non-negligible D atom fraction in the bottom feed gas to the column. These types of calculations are important in the design of CECE (Combined Electrolysis and Catalytic Exchange) water detritiation systems.
Numerical modeling of heat transfer and pasteurizing value during thermal processing of intact egg.
Abbasnezhad, Behzad; Hamdami, Nasser; Monteau, Jean-Yves; Vatankhah, Hamed
2016-01-01
Thermal Pasteurization of Eggs, as a widely used nutritive food, has been simulated. A three-dimensional numerical model, computational fluid dynamics codes of heat transfer equations using heat natural convection, and conduction mechanisms, based on finite element method, was developed to study the effect of air cell size and eggshell thickness. The model, confirmed by comparing experimental and numerical results, was able to predict the temperature profiles, the slowest heating zone, and the required heating time during pasteurization of intact eggs. The results showed that the air cell acted as a heat insulator. Increasing the air cell volume resulted in decreasing of the heat transfer rate, and the increasing the required time of pasteurization (up to 14%). The findings show that the effect on thermal pasteurization of the eggshell thickness was not considerable in comparison to the air cell volume.
Stochastic modelling of conjugate heat transfer in near-wall turbulence
International Nuclear Information System (INIS)
Pozorski, Jacek; Minier, Jean-Pierre
2006-01-01
The paper addresses the conjugate heat transfer in turbulent flows with temperature assumed to be a passive scalar. The Lagrangian approach is applied and the heat transfer is modelled with the use of stochastic particles. The intensity of thermal fluctuations in near-wall turbulence is determined from the scalar probability density function (PDF) with externally provided dynamical statistics. A stochastic model for the temperature field in the wall material is proposed and boundary conditions for stochastic particles at the solid-fluid interface are formulated. The heated channel flow with finite-thickness walls is considered as a validation case. Computation results for the mean temperature profiles and the variance of thermal fluctuations are presented and compared with available DNS data
Stochastic modelling of conjugate heat transfer in near-wall turbulence
Energy Technology Data Exchange (ETDEWEB)
Pozorski, Jacek [Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80952 Gdansk (Poland)]. E-mail: jp@imp.gda.pl; Minier, Jean-Pierre [Research and Development Division, Electricite de France, 6 quai Watier, 78400 Chatou (France)
2006-10-15
The paper addresses the conjugate heat transfer in turbulent flows with temperature assumed to be a passive scalar. The Lagrangian approach is applied and the heat transfer is modelled with the use of stochastic particles. The intensity of thermal fluctuations in near-wall turbulence is determined from the scalar probability density function (PDF) with externally provided dynamical statistics. A stochastic model for the temperature field in the wall material is proposed and boundary conditions for stochastic particles at the solid-fluid interface are formulated. The heated channel flow with finite-thickness walls is considered as a validation case. Computation results for the mean temperature profiles and the variance of thermal fluctuations are presented and compared with available DNS data.
Ramella-Roman, Jessica C.; Stoff, Susan; Chue-Sang, Joseph; Bai, Yuqiang
2016-03-01
The extra-cellular space in connective tissue of animals and humans alike is comprised in large part of collagen. Monitoring of collagen arrangement and cross-linking has been utilized to diagnose a variety of medical conditions and guide surgical intervention. For example, collagen monitoring is useful in the assessment and treatment of cervical cancer, skin cancer, myocardial infarction, and non-arteritic anterior ischemic optic neuropathy. We have developed a suite of tools and models based on polarized light transfer for the assessment of collagen presence, cross-linking, and orientation in living tissue. Here we will present some example of such approach applied to the human cervix. We will illustrate a novel Mueller Matrix (MM) imaging system for the study of cervical tissue; furthermore we will show how our model of polarized light transfer through cervical tissue compares to the experimental findings. Finally we will show validation of the methodology through histological results and Second Harmonic imaging microscopy.
Netcher, Andrea C; Duranceau, Steven J
2016-03-01
In surface water treatment, ultrafiltration (UF) membranes are widely used because of their ability to supply safe drinking water. Although UF membranes produce high-quality water, their efficiency is limited by fouling. Improving UF filtrate productivity is economically desirable and has been attempted by incorporating sustainable biofiltration processes as pretreatment to UF with varying success. The availability of models that can be applied to describe the effectiveness of biofiltration on membrane mass transfer are lacking. In this work, UF water productivity was empirically modeled as a function of biofilter feed water quality using either a quadratic or Gaussian relationship. UF membrane mass transfer variability was found to be governed by the dimensionless mass ratio between the alkalinity (ALK) and dissolved organic carbon (DOC). UF membrane productivity was optimized when the biofilter feed water ALK to DOC ratio fell between 10 and 14. Copyright © 2015 Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Heng, Kevin; Mendonça, João M.; Lee, Jae-Min, E-mail: kevin.heng@csh.unibe.ch, E-mail: joao.mendonca@csh.unibe.ch, E-mail: lee@physik.uzh.ch [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland)
2014-11-01
We present a comprehensive analytical study of radiative transfer using the method of moments and include the effects of non-isotropic scattering in the coherent limit. Within this unified formalism, we derive the governing equations and solutions describing two-stream radiative transfer (which approximates the passage of radiation as a pair of outgoing and incoming fluxes), flux-limited diffusion (which describes radiative transfer in the deep interior), and solutions for the temperature-pressure profiles. Generally, the problem is mathematically underdetermined unless a set of closures (Eddington coefficients) is specified. We demonstrate that the hemispheric (or hemi-isotropic) closure naturally derives from the radiative transfer equation if energy conservation is obeyed, while the Eddington closure produces spurious enhancements of both reflected light and thermal emission. We concoct recipes for implementing two-stream radiative transfer in stand-alone numerical calculations and general circulation models. We use our two-stream solutions to construct toy models of the runaway greenhouse effect. We present a new solution for temperature-pressure profiles with a non-constant optical opacity and elucidate the effects of non-isotropic scattering in the optical and infrared. We derive generalized expressions for the spherical and Bond albedos and the photon deposition depth. We demonstrate that the value of the optical depth corresponding to the photosphere is not always 2/3 (Milne's solution) and depends on a combination of stellar irradiation, internal heat, and the properties of scattering in both the optical and infrared. Finally, we derive generalized expressions for the total, net, outgoing, and incoming fluxes in the convective regime.
Heat Transfer Model of a Small-Scale Waste Glass Melter with Cold Cap Layer
Energy Technology Data Exchange (ETDEWEB)
Abboud, Alexander; Guillen, Donna Post; Pokorny, Richard
2016-09-01
At the Hanford site in the state of Washington, more than 56 million gallons of radioactive waste is stored in underground tanks. The cleanup plan for this waste is vitrification at the Waste Treatment Plant (WTP), currently under construction. At the WTP, the waste will be blended with glass-forming materials and heated to 1423K, then poured into stainless steel canisters to cool and solidify. A fundamental understanding of the glass batch melting process is needed to optimize the process to reduce cost and decrease the life cycle of the cleanup effort. The cold cap layer that floats on the surface of the glass melt is the primary reaction zone for the feed-to-glass conversion. The conversion reactions include water release, melting of salts, evolution of batch gases, dissolution of quartz and the formation of molten glass. Obtaining efficient heat transfer to this region is crucial to achieving high rates of glass conversion. Computational fluid dynamics (CFD) modeling is being used to understand the heat transfer dynamics of the system and provide insight to optimize the process. A CFD model was developed to simulate the DM1200, a pilot-scale melter that has been extensively tested by the Vitreous State Laboratory (VSL). Electrodes are built into the melter to provide Joule heating to the molten glass. To promote heat transfer from the molten glass into the reactive cold cap layer, bubbling of the molten glass is used to stimulate forced convection within the melt pool. A three-phase volume of fluid approach is utilized to model the system, wherein the molten glass and cold cap regions are modeled as separate liquid phases, and the bubbling gas and plenum regions are modeled as one lumped gas phase. The modeling of the entire system with a volume of fluid model allows for the prescription of physical properties on a per-phase basis. The molten glass phase and the gas phase physical properties are obtained from previous experimental work. Finding representative
Kalman Filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry.
Zhang, Yuxin; Chen, Shuo; Deng, Kexin; Chen, Bingyao; Wei, Xing; Yang, Jiafei; Wang, Shi; Ying, Kui
2017-01-01
To develop a self-adaptive and fast thermometry method by combining the original hybrid magnetic resonance thermometry method and the bio heat transfer equation (BHTE) model. The proposed Kalman filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry, abbreviated as KalBHT hybrid method, introduced the BHTE model to synthesize a window on the regularization term of the hybrid algorithm, which leads to a self-adaptive regularization both spatially and temporally with change of temperature. Further, to decrease the sensitivity to accuracy of the BHTE model, Kalman filter is utilized to update the window at each iteration time. To investigate the effect of the proposed model, computer heating simulation, phantom microwave heating experiment and dynamic in-vivo model validation of liver and thoracic tumor were conducted in this study. The heating simulation indicates that the KalBHT hybrid algorithm achieves more accurate results without adjusting λ to a proper value in comparison to the hybrid algorithm. The results of the phantom heating experiment illustrate that the proposed model is able to follow temperature changes in the presence of motion and the temperature estimated also shows less noise in the background and surrounding the hot spot. The dynamic in-vivo model validation with heating simulation demonstrates that the proposed model has a higher convergence rate, more robustness to susceptibility problem surrounding the hot spot and more accuracy of temperature estimation. In the healthy liver experiment with heating simulation, the RMSE of the hot spot of the proposed model is reduced to about 50% compared to the RMSE of the original hybrid model and the convergence time becomes only about one fifth of the hybrid model. The proposed model is able to improve the accuracy of the original hybrid algorithm and accelerate the convergence rate of MR temperature estimation.
Directory of Open Access Journals (Sweden)
Yang Xiao-Jun
2017-01-01
Full Text Available In this paper, we address a class of the fractional derivatives of constant and variable orders for the first time. Fractional-order relaxation equations of constants and variable orders in the sense of Caputo type are modeled from mathematical view of point. The comparative results of the anomalous relaxation among the various fractional derivatives are also given. They are very efficient in description of the complex phenomenon arising in heat transfer.
Pharmacological Evaluation of the SCID T Cell Transfer Model of Colitis
DEFF Research Database (Denmark)
Lindebo Holm, Thomas; Poulsen, Steen Seier; Markholst, Helle
2012-01-01
the SCID adoptive transfer colitis model, we have evaluated the effect of currently used IBD drugs and IBD drug candidates, that is, anti-TNF-α, TNFR-Fc, anti-IL-12p40, anti-IL-6, CTLA4-Ig, anti-α4β7 integrin, enrofloxacin/metronidazole, and cyclosporine. We found that anti-TNF-α, antibiotics, anti-IL-12p...
Model for heat and mass transfer in freeze-drying of pellets.
Trelea, Ioan Cristian; Passot, Stéphanie; Marin, Michèle; Fonseca, Fernanda
2009-07-01
Lyophilizing frozen pellets, and especially spray freeze-drying, have been receiving growing interest. To design efficient and safe freeze-drying cycles, local temperature and moisture content in the product bed have to be known, but both are difficult to measure in the industry. Mathematical modeling of heat and mass transfer helps to determine local freeze-drying conditions and predict effects of operation policy, and equipment and recipe changes on drying time and product quality. Representative pellets situated at different positions in the product slab were considered. One-dimensional transfer in the slab and radial transfer in the pellets were assumed. Coupled heat and vapor transfer equations between the temperature-controlled shelf, the product bulk, the sublimation front inside the pellets, and the chamber were established and solved numerically. The model was validated based on bulk temperature measurement performed at two different locations in the product slab and on partial vapor pressure measurement in the freeze-drying chamber. Fair agreement between measured and calculated values was found. In contrast, a previously developed model for compact product layer was found inadequate in describing freeze-drying of pellets. The developed model represents a good starting basis for studying freeze-drying of pellets. It has to be further improved and validated for a variety of product types and freeze-drying conditions (shelf temperature, total chamber pressure, pellet size, slab thickness, etc.). It could be used to develop freeze-drying cycles based on product quality criteria such as local moisture content and glass transition temperature.
Temperature modulation with an esophageal heat transfer device- a pediatric swine model study
Kulstad, Erik B; Naiman, Melissa; Shanley, Patrick; Garrett, Frank; Haryu, Todd; Waller, Donald; Azarafrooz, Farshid; Courtney, Daniel Mark
2015-01-01
Background An increasing number of conditions appear to benefit from control and modulation of temperature, but available techniques to control temperature often have limitations, particularly in smaller patients with high surface to mass ratios. We aimed to evaluate a new method of temperature modulation with an esophageal heat transfer device in a pediatric swine model, hypothesizing that clinically significant modulation in temperature (both increases and decreases of more than 1?C) would ...
Heat transfer modeling in exhaust systems of high-performance two-stroke engines
Lujan Martinez, José Manuel; Climent Puchades, Héctor; Olmeda González, Pablo Cesar; JIMENEZ MACEDO, VICTOR DANIEL
2014-01-01
Heat transfer from the hot gases to the wall in exhaust systems of high-performance two-stroke engines is underestimated using steady state with fully developed flow empirical correlations. This fact is detected when comparing measured and modeled pressure pulses in different positions in the exhaust system. This can be explained taking into account that classical expressions have been validated for fully developed flows, a situation that is far from the flow behavior in reciprocating interna...
International Nuclear Information System (INIS)
Shahab, S; Erturk, A
2014-01-01
There are several applications of wireless electronic components with little or no ambient energy available to harvest, yet wireless battery charging for such systems is still of great interest. Example applications range from biomedical implants to sensors located in hazardous environments. Energy transfer based on the propagation of acoustic waves at ultrasonic frequencies is a recently explored alternative that offers increased transmitter-receiver distance, reduced loss and the elimination of electromagnetic fields. As this research area receives growing attention, there is an increased need for fully coupled model development to quantify the energy transfer characteristics, with a focus on the transmitter, receiver, medium, geometric and material parameters. We present multiphysics modeling and case studies of the contactless ultrasonic energy transfer for wireless electronic components submerged in fluid. The source is a pulsating sphere, and the receiver is a piezoelectric bar operating in the 33-mode of piezoelectricity with a fundamental resonance frequency above the audible frequency range. The goal is to quantify the electrical power delivered to the load (connected to the receiver) in terms of the source strength. Both the analytical and finite element models have been developed for the resulting acoustic-piezoelectric structure interaction problem. Resistive and resistive–inductive electrical loading cases are presented, and optimality conditions are discussed. Broadband power transfer is achieved by optimal resistive-reactive load tuning for performance enhancement and frequency-wise robustness. Significant enhancement of the power output is reported due to the use of a hard piezoelectric receiver (PZT-8) instead of a soft counterpart (PZT-5H) as a result of reduced material damping. The analytical multiphysics modeling approach given in this work can be used to predict and optimize the coupled system dynamics with very good accuracy and
Heat transfer modelling in a spent-fuel dry storage system
International Nuclear Information System (INIS)
Ritz, J.B.; Le Bonhomme, S.
2001-01-01
The purpose of this paper is to present a numerical modelling of heat transfers in a Spent-Fuel horizontal dry storage. The horizontal dry storage is an interesting issue to momentary store spent fuel containers before the final storage. From a thermal point of view, the cooling of spent fuel container by natural convection is a suitable and inexpensive process but it necessitates to well define the dimensions of the concept due to the difficulty to control the thermal environment. (author)
Tong, Guo-qing; Heng, Boon-chin; Ng, Soon-chye
2007-01-01
This study investigated whether four cumulus-specific genes: follicular stimulating hormone receptor (FSHr), hyaluronan synthase 2 (Has2), prostaglandin synthase 2 (Ptgs2) and steroidogenic acute regulator protein (Star), were correctly reprogrammed to be transcriptionally silent following somatic cell nuclear transfer (SCNT) in a murine model. Cumulus cells of C57×CBA F1 female mouse were injected into enucleated oocytes, followed by activation in 10 µmol/L strontium chloride for 5 h and sub...
FARMLAND. A dynamic model for the transfer of radionuclides through terrestrial food chains
International Nuclear Information System (INIS)
Brown, J.; Simmonds, J.R.
1995-07-01
Models to simulate the transfer of radionuclides through terrestrial foods have been developed at NRPB and regularly used over the last 20 years. The foodchain model is named FARMLAND (Food Activity from Radionuclide Movement on LAND) and it contains a suite of submodels, each of which simulates radionuclide transfer through a different part of the foodchain. These models can be combined in various orders so that they can be used for different situations of radiological interest. The main foods considered are green vegetables, grain products, root vegetables, milk, meat and offal from cattle, and meat and offal from sheep. A large variety of elements can be considered, although the degree of complexity with which some are modelled is greater than that for others; isotopes of caesium, strontium and iodine are treated in greatest detail. This report gives an overview of the FARMLAND model with the aim of consolidating all the information on the model available in past NRPB publications. In addition, recent model developments are described. The use of FARMLAND for different applications is addressed. In particular, the generation of a set of parameter values and assumptions for use in general applications in countries in the European Union are discussed. Activity concentrations in foods are presented for a few important radionuclides for both routine and accidental release applications. The conclusions of verification and validation studies performed using FARMLAND are also outlined. (author)
FARMLAND. A dynamic model for the transfer of radionuclides through terrestrial foodchains
International Nuclear Information System (INIS)
Brown, J.; Simmonds, J.R.
1995-01-01
Models to simulate the transfer of radionuclides through terrestrial foods have been developed at NRPB and regularly used over the last 20 years. The foodchain model is named FARMLAND (Food Activity from Radionuclide Movement on LAND) and it contains a suite of submodels, each of which simulates radionuclide transfer through a different part of the foodchain. These models can be combined in various orders so that they can be used for different situations of radiological interest. The main foods considered are green vegetables, grain products, root vegetables, milk, meat and offal from cattle, and meat and offal from sheep. A large variety of elements can be considered, although the degree of complexity with which some are modelled is greater than that for others: isotopes of caesium, strontium and iodine are treated in greatest detail. This report gives an overview of the FARMLAND model with the aim of consolidating all the information on the model available in past NRPB publications. In addition, recent model developments are described. (Author)
A computer simulation model to compute the radiation transfer of mountainous regions
Li, Yuguang; Zhao, Feng; Song, Rui
2011-11-01
In mountainous regions, the radiometric signal recorded at the sensor depends on a number of factors such as sun angle, atmospheric conditions, surface cover type, and topography. In this paper, a computer simulation model of radiation transfer is designed and evaluated. This model implements the Monte Carlo ray-tracing techniques and is specifically dedicated to the study of light propagation in mountainous regions. The radiative processes between sun light and the objects within the mountainous region are realized by using forward Monte Carlo ray-tracing methods. The performance of the model is evaluated through detailed comparisons with the well-established 3D computer simulation model: RGM (Radiosity-Graphics combined Model) based on the same scenes and identical spectral parameters, which shows good agreements between these two models' results. By using the newly developed computer model, series of typical mountainous scenes are generated to analyze the physical mechanism of mountainous radiation transfer. The results show that the effects of the adjacent slopes are important for deep valleys and they particularly affect shadowed pixels, and the topographic effect needs to be considered in mountainous terrain before accurate inferences from remotely sensed data can be made.
A simplified kinetic and mass transfer modelling of the thermal hydrolysis of vegetable oils
DEFF Research Database (Denmark)
Forero-Hernandez, Hector Alexander; Jones, Mark Nicholas; Sarup, Bent
2017-01-01
This work presents a combined modelling approach to investigate the kinetics and masstransfer effects on the hydrolysis of vegetable oils under subcritical conditions. The primary purpose of this simplified model is to interpret experimental data collected from typical batch tests and to estimate...... parameters for the proposed model. Due to its heterogeneous nature, the hydrolysis reaction is affected not only by the chemical kinetics but also by the rate of mass transfer between the oil and water as well as their specific contact area in this two phase emulsion. Considering these properties, a model...... and improvement accompanied by Monte Carlo uncertainty analysis. Since the lack of experimental data is a crucial issue in the hydrolysis of vegetable oils, this model-based analysis of data is of substantial value to provide necessary information for detailed modeling and characterization of the process....
Analytical Modelling of Wireless Power Transfer (WPT) Systems for Electric Vehicle Application
Energy Technology Data Exchange (ETDEWEB)
Chinthavali, Madhu Sudhan [ORNL; Campbell, Steven L [ORNL
2016-01-01
This paper presents an analytical model for wireless power transfer system used in electric vehicle application. The equivalent circuit model for each major component of the system is described, including the input voltage source, resonant network, transformer, nonlinear diode rectifier load, etc. Based on the circuit model, the primary side compensation capacitance, equivalent input impedance, active / reactive power are calculated, which provides a guideline for parameter selection. Moreover, the voltage gain curve from dc output to dc input is derived as well. A hardware prototype with series-parallel resonant stage is built to verify the developed model. The experimental results from the hardware are compared with the model predicted results to show the validity of the model.
Directory of Open Access Journals (Sweden)
Herrick Jason R
2009-12-01
Full Text Available Abstract Background Somatic cell nuclear transfer in cats offers a useful tool for the generation of valuable research models. However, low birth rates after nuclear transfer hamper exploitation of the full potential of the technology. Poor embryo development after activation of the reconstructed oocytes seems to be responsible, at least in part, for the low efficiency. The objective of this study was to characterize the response of cat oocytes to various stimuli in order to fine-tune existing and possibly develop new activation methods for the generation of cat disease models by somatic cell nuclear transfer. Methods First, changes in the intracellular free calcium concentration [Ca2+]i in the oocytes induced by a number of artificial stimuli were characterized. The stimuli included electroporation, ethanol, ionomycin, thimerosal, strontium-chloride and sodium (Na+-free medium. The potential of the most promising treatments (with or without subsequent incubation in the presence of cycloheximide and cytochalasin B to stimulate oocyte activation and support development of the resultant parthenogenetic embryos was then evaluated. Finally, the most effective methods were selected to activate oocytes reconstructed during nuclear transfer with fibroblasts from mucopolysaccharidosis I- and alpha-mannosidosis-affected cats. Results All treatments were able to elicit a [Ca2+]i elevation in the ooplasm with various characteristics. Pronuclear formation and development up to the blastocyst stage was most efficiently triggered by electroporation (60.5 +/- 2.9 and 11.5 +/- 1.7% and the combined thimerosal/DTT treatment (67.7 +/- 1.8 and 10.6 +/- 1.9%; incubation of the stimulated oocytes with cycloheximide and cytochalasin B had a positive effect on embryo development. When these two methods were used to activate oocytes reconstructed during nuclear transfer, up to 84.9% of the reconstructed oocytes cleaved. When the 2 to 4-cell embryos (a total of 220 were