A correlation to the heat transfer coefficient in nucleate boiling
International Nuclear Information System (INIS)
Ribatski, Gherhardt; Jabardo, Jose M. Saiz
1999-01-01
Nucleate boiling heat transfer is a complex phenomenon, making the development of a correlation for the heat transfer coefficient rather cumbersome due to the number of physical parameters involved in it. Some authors have followed a pragmatic approach to the problem by correlating the heat transfer coefficient in terms of reduced primitive properties. Two of the most knowledgeable authors who have followed this approach are Gorenflo and Cooper. Comparisons have been performed among results from the correlations proposed by these researchers and experimental results obtained elsewhere for refrigerants R-11, R-113 and R-114. These comparisons have shown that Cooper's correlation is best fitted for halocarbon refrigerants. The correlation proposed by Gorenflo ads the difficulty of including a numerical factor specific for each fluid. Leiner modified Gorenflo's correlation to determine the numerical factor as a function of known physical parameters of the fluid. In present study, the form of this function has been investigated for halocarbon refrigerants. The obtained correlation is written in terms of the following parameters: reduced pressure, eccentric and compressibility factors at the critical state, and a dimensionless specific heat of the vapor phase. The correlation compares well with experimental results. (author)
Correlation of heat transfer coefficient in quenching process using ABAQUS
Davare, Sandeep Kedarnath; Balachandran, G.; Singh, R. K. P.
2018-04-01
During the heat treatment by quenching in a liquid medium the convective heat transfer coefficient plays a crucial role in the extraction of heat. The heat extraction ultimately influences the cooling rate and hence the hardness and mechanical properties. A Finite Element analysis of quenching a simple flat copper sample with different orientation of sample and with different quenchant temperatures were carried out to check and verify the results obtained from the experiments. The heat transfer coefficient (HTC) was calculated from temperature history in a simple flat copper disc sample experimentally. This HTC data was further used as input to simulation software and the cooling curves were back calculated. The results obtained from software and using experimentation shows nearly consistent values.
International Nuclear Information System (INIS)
Picanco, Marco Antonio Silva; Bandarra Filho, Enio Pedone; Passos, Julio Cesar
2006-01-01
Two-phase flow heat transfer has been exhaustively studied over recent years. However, in this field several questions remain unanswered. Heat transfer coefficient prediction related to nucleate and convective boiling have been studied using different approaches, numerical, analytical and experimental. In this work, an experimental analysis, data representation and heat transfer coefficient prediction on two-phase heat transfer on nucleate and convective boiling are presented. An empirical correlation is obtained based on genetic algorithms search engine over a dimensional analysis of the two-phase flow heat transfer problem. (author)
New external convective heat transfer coefficient correlations for isolated low-rise buildings
Energy Technology Data Exchange (ETDEWEB)
Emmel, M. G.; Mendes, N. [Pontifical Catholic University of Parana, PUCPR/CCET, Thermal Systems Laboratory, LST, Curitiba (Brazil); Abadie, M. O. [Pontifical Catholic University of Parana, PUCPR/CCET, Thermal Systems Laboratory, LST, Curitiba (Brazil); Laboratoire d' Etude des Phenomenes de Transfert Appliques au batiment (LEPTAB), University of La Rochelle, La Rochelle (France)
2007-07-01
Building energy analyses are very sensitive to external convective heat transfer coefficients so that some researchers have conducted sensitivity calculations and proved that depending on the choice of those coefficients, energy demands estimation values can vary from 20% to 40%. In this context, computational fluid dynamics calculations have been performed to predict convective heat transfer coefficients at the external surfaces of a simple shape low-rise building. Effects of wind velocity and orientation have been analyzed considering four surface-to-air temperature differences. Results show that the convective heat transfer coefficient value strongly depends on the wind velocity, that the wind direction has a notable effect for vertical walls and for roofs and that the surface-to-air temperature difference has a negligible effect for wind velocity higher than 2 m/s. External convective heat transfer coefficient correlations are provided as a function of the wind free stream velocity and wind-to-surface angle. (author)
Li, Cun-Yu; Wu, Xin; Gu, Jia-Mei; Li, Hong-Yang; Peng, Guo-Ping
2018-04-01
Based on the molecular sieving and solution-diffusion effect in nanofiltration separation, the correlation between initial concentration and mass transfer coefficient of three typical phenolic acids from Salvia miltiorrhiza was fitted to analyze the relationship among mass transfer coefficient, molecular weight and concentration. The experiment showed a linear relationship between operation pressure and membrane flux. Meanwhile, the membrane flux was gradually decayed with the increase of solute concentration. On the basis of the molecular sieving and solution-diffusion effect, the mass transfer coefficient and initial concentration of three phenolic acids showed a power function relationship, and the regression coefficients were all greater than 0.9. The mass transfer coefficient and molecular weight of three phenolic acids were negatively correlated with each other, and the order from high to low is protocatechualdehyde >rosmarinic acid> salvianolic acid B. The separation mechanism of nanofiltration for phenolic acids was further clarified through the analysis of the correlation of molecular weight and nanofiltration mass transfer coefficient. The findings provide references for nanofiltration separation, especially for traditional Chinese medicine with phenolic acids. Copyright© by the Chinese Pharmaceutical Association.
Determination and correlation of mass transfer coefficients in a stirred cell
International Nuclear Information System (INIS)
Herranz, J.; Bloxom, S.R.; Keeler, J.B.; Roth, S.R.
1975-01-01
In the proposed Molten Salt Breeder Reactor flowsheet, a fraction of the rare earth fission products is removed from the fuel salt in mass transfer cells. To obtain design parameters for this extraction, the effect of cell size, blade diameter, phase volume, and agitation rate on the mass transfer for a high density ratio system (mercury/water) in nondispersing square cross section contactors was determined. Aqueous side mass transfer coefficients were measured by polarography over a wide range of operating conditions. Correlations for the experimental mass transfer coefficients as functions of the operating parameters are presented. Several techniques for measuring mercury-side mass transfer coefficients were evaluated and a new one is recommended
Comparison of boiling heat transfer coefficient and pressure drop correlations for evaporators
International Nuclear Information System (INIS)
Eskin, N.; Arslan, G.
2009-01-01
Evaporator design is an important aspect for the HVAC industry. As the demand for more efficient and compact heat exchangers increase, researches on estimation of two-phase flow heat transfer and pressure drop gain importance. Due to complexity of the hydrodynamic and heat transfer of the two-phase flow, there are many experimental studies available for refrigerants int he literature. In this study, a model for boiling heat transfer in a horizontal tube has been developed and the simulation results are compared with experimental ones published in the literature. In these comparisons, heat transfer coefficient is calculated by using Kattan-Thome-Favrat (1998), Shah (1982), Kandilikar (1990), Chaddock and Brunemann (1967) correlations under different operational conditions such as saturation pressure, mass flux, the type of refrigerant and two phase flow pattern. Besides that flow pattern has also been considered in the simulation by using Thome and El Hajal (2002) model. For pressure drop Lockhart-Martinelli (1949), Mueller-Steinhagen-Hack (1986) and Groennerund (1979) correlations are used in simulations. Local vapor quality change at each experimental condition through the model is determined. Roughness is an important parameter for frictional pressure drop. Friction coefficient is determined by using Churchill (1977) model. (author)
Fukuda, Makoto; Yoshimura, Kengo; Namekawa, Koki; Sakai, Kiyotaka
2017-06-01
The objective of the present study is to evaluate the effect of filtration coefficient and internal filtration on dialysis fluid flow and mass transfer coefficient in dialyzers using dimensionless mass transfer correlation equations. Aqueous solution of vitamin B 12 clearances were obtained for REXEED-15L as a low flux dialyzer, and APS-15EA and APS-15UA as high flux dialyzers. All the other design specifications were identical for these dialyzers except for filtration coefficient. The overall mass transfer coefficient was calculated, moreover, the exponents of Reynolds number (Re) and film mass transfer coefficient of the dialysis-side fluid (k D ) for each flow rate were derived from the Wilson plot and dimensionless correlation equation. The exponents of Re were 0.4 for the low flux dialyzer whereas 0.5 for the high flux dialyzers. Dialysis fluid of the low flux dialyzer was close to laminar flow because of its low filtration coefficient. On the other hand, dialysis fluid of the high flux dialyzers was assumed to be orthogonal flow. Higher filtration coefficient was associated with higher k D influenced by mass transfer rate through diffusion and internal filtration. Higher filtration coefficient of dialyzers and internal filtration affect orthogonal flow of dialysis fluid.
International Nuclear Information System (INIS)
Park, Sang Kyoo; Yang, Hei Cheon
2017-01-01
As stricter environmental regulation have led to an increase in the water treatment cost, it is necessary to quantitatively study the input power of the aeration process to improve the energy efficiency of the water treatment processes. The objective of this study is to propose the empirical correlations for the mass transfer coefficient with the gas hold-up and input power in order to investigate the mass transfer characteristics of the aeration process. It was found that as the input power increases, the mass transfer coefficient increases because of the decrease of gas hold-up and increase of Reynolds number, the penetration length, and dispersion of mixed flow. The correlations for the volumetric mass transfer coefficients with gas hold-up and input power were consistent with the experimental data, with the maximum deviation less than approximately ±10.0%.
Energy Technology Data Exchange (ETDEWEB)
Park, Sang Kyoo; Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)
2017-06-15
As stricter environmental regulation have led to an increase in the water treatment cost, it is necessary to quantitatively study the input power of the aeration process to improve the energy efficiency of the water treatment processes. The objective of this study is to propose the empirical correlations for the mass transfer coefficient with the gas hold-up and input power in order to investigate the mass transfer characteristics of the aeration process. It was found that as the input power increases, the mass transfer coefficient increases because of the decrease of gas hold-up and increase of Reynolds number, the penetration length, and dispersion of mixed flow. The correlations for the volumetric mass transfer coefficients with gas hold-up and input power were consistent with the experimental data, with the maximum deviation less than approximately ±10.0%.
Directory of Open Access Journals (Sweden)
Zhixian Huang
Full Text Available Abstract To investigate the mass transfer behavior of a liquid-liquid system with high density difference (∆ρ≈500 kg/m3, single drop experiments were performed by using the ternary chloroform-ethanol-water system. The mass transfer direction was from the dispersed phase to the continuous phase, while the aqueous phase was dispersed in chloroform to generate drops. The influences of drop diameter, initial solute concentration and temperature on the mass transfer were investigated. The effects of the drop diameter and initial solute concentration on interfacial instability of droplets hanging in the continuous phase were also observed. For the purpose of correlation, a mass transfer enhancement factor F was introduced and then correlated as a function of dimensionless variables. The modified correlation from the mass transfer coefficient model was found to fit well with the experimental values.
Heat transfer coefficient for boiling carbon dioxide
DEFF Research Database (Denmark)
Knudsen, Hans Jørgen Høgaard; Jensen, Per Henrik
1998-01-01
Heat transfer coefficient and pressure drop for boiling carbon dioxide (R744) flowing in a horizontal pipe has been measured. The calculated heat transfer coeeficient has been compared with the Chart correlation of Shah. The Chart Correlation predits too low heat transfer coefficient but the ratio...... between the measured and the calculated heat transfer coefficient is nearly constant and equal 1.9. With this factor the correlation predicts the measured data within 14% (RMS). The pressure drop is of the same order as the measuring uncertainty and the pressure drop has not been compared with correlation's....
Measuring of heat transfer coefficient
DEFF Research Database (Denmark)
Henningsen, Poul; Lindegren, Maria
Subtask 3.4 Measuring of heat transfer coefficient Subtask 3.4.1 Design and setting up of tests to measure heat transfer coefficient Objective: Complementary testing methods together with the relevant experimental equipment are to be designed by the two partners involved in order to measure...... the heat transfer coefficient for a wide range of interface conditions in hot and warm forging processes. Subtask 3.4.2 Measurement of heat transfer coefficient The objective of subtask 3.4.2 is to determine heat transfer values for different interface conditions reflecting those typically operating in hot...
On the Kendall Correlation Coefficient
Stepanov, Alexei
2015-01-01
In the present paper, we first discuss the Kendall rank correlation coefficient. In continuous case, we define the Kendall rank correlation coefficient in terms of the concomitants of order statistics, find the expected value of the Kendall rank correlation coefficient and show that the later is free of n. We also prove that in continuous case the Kendall correlation coefficient converges in probability to its expected value. We then propose to consider the expected value of the Kendall rank ...
Clustering Coefficients for Correlation Networks.
Masuda, Naoki; Sakaki, Michiko; Ezaki, Takahiro; Watanabe, Takamitsu
2018-01-01
Graph theory is a useful tool for deciphering structural and functional networks of the brain on various spatial and temporal scales. The clustering coefficient quantifies the abundance of connected triangles in a network and is a major descriptive statistics of networks. For example, it finds an application in the assessment of small-worldness of brain networks, which is affected by attentional and cognitive conditions, age, psychiatric disorders and so forth. However, it remains unclear how the clustering coefficient should be measured in a correlation-based network, which is among major representations of brain networks. In the present article, we propose clustering coefficients tailored to correlation matrices. The key idea is to use three-way partial correlation or partial mutual information to measure the strength of the association between the two neighboring nodes of a focal node relative to the amount of pseudo-correlation expected from indirect paths between the nodes. Our method avoids the difficulties of previous applications of clustering coefficient (and other) measures in defining correlational networks, i.e., thresholding on the correlation value, discarding of negative correlation values, the pseudo-correlation problem and full partial correlation matrices whose estimation is computationally difficult. For proof of concept, we apply the proposed clustering coefficient measures to functional magnetic resonance imaging data obtained from healthy participants of various ages and compare them with conventional clustering coefficients. We show that the clustering coefficients decline with the age. The proposed clustering coefficients are more strongly correlated with age than the conventional ones are. We also show that the local variants of the proposed clustering coefficients (i.e., abundance of triangles around a focal node) are useful in characterizing individual nodes. In contrast, the conventional local clustering coefficients were strongly
Clustering Coefficients for Correlation Networks
Directory of Open Access Journals (Sweden)
Naoki Masuda
2018-03-01
Full Text Available Graph theory is a useful tool for deciphering structural and functional networks of the brain on various spatial and temporal scales. The clustering coefficient quantifies the abundance of connected triangles in a network and is a major descriptive statistics of networks. For example, it finds an application in the assessment of small-worldness of brain networks, which is affected by attentional and cognitive conditions, age, psychiatric disorders and so forth. However, it remains unclear how the clustering coefficient should be measured in a correlation-based network, which is among major representations of brain networks. In the present article, we propose clustering coefficients tailored to correlation matrices. The key idea is to use three-way partial correlation or partial mutual information to measure the strength of the association between the two neighboring nodes of a focal node relative to the amount of pseudo-correlation expected from indirect paths between the nodes. Our method avoids the difficulties of previous applications of clustering coefficient (and other measures in defining correlational networks, i.e., thresholding on the correlation value, discarding of negative correlation values, the pseudo-correlation problem and full partial correlation matrices whose estimation is computationally difficult. For proof of concept, we apply the proposed clustering coefficient measures to functional magnetic resonance imaging data obtained from healthy participants of various ages and compare them with conventional clustering coefficients. We show that the clustering coefficients decline with the age. The proposed clustering coefficients are more strongly correlated with age than the conventional ones are. We also show that the local variants of the proposed clustering coefficients (i.e., abundance of triangles around a focal node are useful in characterizing individual nodes. In contrast, the conventional local clustering coefficients
Clustering Coefficients for Correlation Networks
Masuda, Naoki; Sakaki, Michiko; Ezaki, Takahiro; Watanabe, Takamitsu
2018-01-01
Graph theory is a useful tool for deciphering structural and functional networks of the brain on various spatial and temporal scales. The clustering coefficient quantifies the abundance of connected triangles in a network and is a major descriptive statistics of networks. For example, it finds an application in the assessment of small-worldness of brain networks, which is affected by attentional and cognitive conditions, age, psychiatric disorders and so forth. However, it remains unclear how the clustering coefficient should be measured in a correlation-based network, which is among major representations of brain networks. In the present article, we propose clustering coefficients tailored to correlation matrices. The key idea is to use three-way partial correlation or partial mutual information to measure the strength of the association between the two neighboring nodes of a focal node relative to the amount of pseudo-correlation expected from indirect paths between the nodes. Our method avoids the difficulties of previous applications of clustering coefficient (and other) measures in defining correlational networks, i.e., thresholding on the correlation value, discarding of negative correlation values, the pseudo-correlation problem and full partial correlation matrices whose estimation is computationally difficult. For proof of concept, we apply the proposed clustering coefficient measures to functional magnetic resonance imaging data obtained from healthy participants of various ages and compare them with conventional clustering coefficients. We show that the clustering coefficients decline with the age. The proposed clustering coefficients are more strongly correlated with age than the conventional ones are. We also show that the local variants of the proposed clustering coefficients (i.e., abundance of triangles around a focal node) are useful in characterizing individual nodes. In contrast, the conventional local clustering coefficients were strongly
Klöckner, Wolf; Gacem, Riad; Anderlei, Tibor; Raven, Nicole; Schillberg, Stefan; Lattermann, Clemens; Büchs, Jochen
2013-12-02
Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation. A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham's π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures. The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/- 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale.
International Nuclear Information System (INIS)
Herrera A, E.
1994-01-01
In the heat transfer studies by forced convection, we have few data about behavior of the fluids in an annular channel heated by a concentric pipe, such date is necessary to know the heat transfer coefficient that establish the interchange of energy and the thermic properties of the fluid with the geometry of the flow. In this work the objective, was to compare some empirical correlations that we needed for determinate the heat transfer coefficient for annular channels, where we obtained similar at the theoretical results of an experiment made by Miller and Benforado. It is important to know such coefficients because we can determinate the heat quantity transmitted to a probe zone, in which we simulate a nuclear fuel element that developed huge heat quantity that must be dispersed in short time. We give theoretical data of the heat forced transfer convection and we analyzed the phenomena in annular channels given some empirical correlations employed by some investigators and we analyzed each one. (Author)
Directory of Open Access Journals (Sweden)
Ismael Fernando Meza Castro
2017-07-01
Full Text Available Introduction: This project carried out an experimental research with the design, assembly, and commissioning of a convection heat transfer test bench. Objective: To determine new statistical correlations that allow knowing the heat transfer coefficients by air convection with greater accuracy in applications with different heating geometry configurations. Methodology: Three geometric configurations, such as flat plate, cylinders and tube banks were studied according to their physical properties through Reynolds and Prandtl numbers, using a data transmission interface using Arduino® controllers Measured the air temperature through the duct to obtain real-time data and to relate the heat transferred from the heating element to the fluid and to perform mathematical modeling in specialized statistical software. The study was made for the three geometries mentioned, one power per heating element and two air velocities with 10 repetitions. Results: Three mathematical correlations were obtained with regression coefficients greater than 0.972, one for each heating element, obtaining prediction errors in the heat transfer convective coefficients of 7.50% for the flat plate, 2.85% for the plate Cylindrical and 1.57% for the tube bank. Conclusions: It was observed that in geometries constituted by several individual elements, a much more accurate statistical adjustment was obtained to predict the behavior of the convection heat coefficients, since each unit reaches a stability in the surface temperature profile with Greater speed, giving the geometry in general, a more precise measurement of the parameters that govern the transfer of heat, as it is in the case of the geometry of the tube bank.
International Nuclear Information System (INIS)
Shamim, Jubair A.; Bhowmik, Palash K.; Xiangyi, Chen; Suh, Kune Y.
2016-01-01
Highlights: • Thermo-hydrodynamic properties of water–Al_2O_3 nanofluid at PWR condition is analyzed. • Details of CFD simulation and validation procedure is outlined. • Augmented heat transfer capacity of nanofluid is governed by larger pumping power. • A new correlation for nanofluid Nusselt number in subchannel geometry is proposed. - Abstract: The computational fluid dynamic (CFD) simulation is performed to determine on the thermo- and hydrodynamic performance of the water–alumina (Al_2O_3) nanofluid in a square array subchannel featuring pitch-to-diameter ratios of 1.25 and 1.35. Two fundamental aspects of thermal hydraulics, viz. heat transfer and pressure drop, are assessed under typical pressurized water reactor (PWR) conditions at various flow rates (3 × 10"5 ⩽ Re ⩽ 6 × 10"5) using pure water and differing concentrations of water–alumina nanofluid (0.5–3.0 vol.%) as coolant. Numerical results are compared against predictions made by conventional single-phase convective heat transfer and pressure loss correlations for fully developed turbulent flow. It is observed that addition of tiny nanoparticles in PWR coolant can give rise to the convective heat transfer coefficient at the expense of larger pressure drop. Nevertheless, a modified correlation as a function of nanoparticle volume fraction is proposed to estimate nanofluid Nusselt number more precisely in square array subchannel.
Energy Technology Data Exchange (ETDEWEB)
Shamim, Jubair A. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of); Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Bhowmik, Palash K. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of); Department of Nuclear Engineering, Missouri University of Science and Technology, 1201 N. State St., Rolla, MO 65409 (United States); Xiangyi, Chen [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of); Suh, Kune Y., E-mail: kysuh@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of)
2016-11-15
Highlights: • Thermo-hydrodynamic properties of water–Al{sub 2}O{sub 3} nanofluid at PWR condition is analyzed. • Details of CFD simulation and validation procedure is outlined. • Augmented heat transfer capacity of nanofluid is governed by larger pumping power. • A new correlation for nanofluid Nusselt number in subchannel geometry is proposed. - Abstract: The computational fluid dynamic (CFD) simulation is performed to determine on the thermo- and hydrodynamic performance of the water–alumina (Al{sub 2}O{sub 3}) nanofluid in a square array subchannel featuring pitch-to-diameter ratios of 1.25 and 1.35. Two fundamental aspects of thermal hydraulics, viz. heat transfer and pressure drop, are assessed under typical pressurized water reactor (PWR) conditions at various flow rates (3 × 10{sup 5} ⩽ Re ⩽ 6 × 10{sup 5}) using pure water and differing concentrations of water–alumina nanofluid (0.5–3.0 vol.%) as coolant. Numerical results are compared against predictions made by conventional single-phase convective heat transfer and pressure loss correlations for fully developed turbulent flow. It is observed that addition of tiny nanoparticles in PWR coolant can give rise to the convective heat transfer coefficient at the expense of larger pressure drop. Nevertheless, a modified correlation as a function of nanoparticle volume fraction is proposed to estimate nanofluid Nusselt number more precisely in square array subchannel.
Correlation coefficients in neutron β-decay
International Nuclear Information System (INIS)
Byrne, J.
1978-01-01
The various angular and polarisation coefficients in neutron decay are the principal sources of information on the β-interaction. Measurements of the electron-neutrino angular correlation coefficient (a), the neutron-spin-electron-momentum correlation coefficient (A), the neutron-spin-neutrino-momentum correlation coefficient (B), and the triple correlation coefficient D and time-reversal invariance are reviewed and the results discussed. (U.K.)
Local Transfer Coefficient, Smooth Channel
Directory of Open Access Journals (Sweden)
R. T. Kukreja
1998-01-01
Full Text Available Naphthalene sublimation technique and the heat/mass transfer analogy are used to determine the detailed local heat/mass transfer distributions on the leading and trailing walls of a twopass square channel with smooth walls that rotates about a perpendicular axis. Since the variation of density is small in the flow through the channel, buoyancy effect is negligible. Results show that, in both the stationary and rotating channel cases, very large spanwise variations of the mass transfer exist in he turn and in the region immediately downstream of the turn in the second straight pass. In the first straight pass, the rotation-induced Coriolis forces reduce the mass transfer on the leading wall and increase the mass transfer on the trailing wall. In the turn, rotation significantly increases the mass transfer on the leading wall, especially in the upstream half of the turn. Rotation also increases the mass transfer on the trailing wall, more in the downstream half of the turn than in the upstream half of the turn. Immediately downstream of the turn, rotation causes the mass transfer to be much higher on the trailing wall near the downstream corner of the tip of the inner wall than on the opposite leading wall. The mass transfer in the second pass is higher on the leading wall than on the trailing wall. A slower flow causes higher mass transfer enhancement in the turn on both the leading and trailing walls.
Heat transfer coefficient of cryotop during freezing.
Li, W J; Zhou, X L; Wang, H S; Liu, B L; Dai, J J
2013-01-01
Cryotop is an efficient vitrification method for cryopreservation of oocytes. It has been widely used owing to its simple operation and high freezing rate. Recently, the heat transfer performance of cryotop was studied by numerical simulation in several studies. However, the range of heat transfer coefficient in the simulation is uncertain. In this study, the heat transfer coefficient for cryotop during freezing process was analyzed. The cooling rates of 40 percent ethylene glycol (EG) droplet in cryotop during freezing were measured by ultra-fast measurement system and calculated by numerical simulation at different value of heat transfer coefficient. Compared with the results obtained by two methods, the range of the heat transfer coefficient necessary for the numerical simulation of cryotop was determined, which is between 9000 W/(m(2)·K) and 10000 W/(m (2)·K).
Transfer coefficients in ultracold strongly coupled plasma
Bobrov, A. A.; Vorob'ev, V. S.; Zelener, B. V.
2018-03-01
We use both analytical and molecular dynamic methods for electron transfer coefficients in an ultracold plasma when its temperature is small and the coupling parameter characterizing the interaction of electrons and ions exceeds unity. For these conditions, we use the approach of nearest neighbor to determine the average electron (ion) diffusion coefficient and to calculate other electron transfer coefficients (viscosity and electrical and thermal conductivities). Molecular dynamics simulations produce electronic and ionic diffusion coefficients, confirming the reliability of these results. The results compare favorably with experimental and numerical data from earlier studies.
Transfer of risk coefficients across populations
International Nuclear Information System (INIS)
Rasmussen, L.R.
1992-01-01
The variation of lifetime risk projections for a Canadian population caused by the uncertainty in the choice of method for transferring excess relative risk coefficients between populations is assessed. Site-specific projections, varied by factors up to 3.5 when excess risk coefficients of the BEIR V relative risk models were transferred to the Canadian population using an additive and multiplicative method. When the risk from all cancers are combined, differences between transfer methods were no longer significant. The Canadian projections were consistent with the ICRP-60 nominal fatal cancer risk estimates. (author)
Heat transfer direction dependence of heat transfer coefficients in annuli
Prinsloo, Francois P. A.; Dirker, Jaco; Meyer, Josua P.
2018-04-01
In this experimental study the heat transfer phenomena in concentric annuli in tube-in-tube heat exchangers at different annular Reynolds numbers, annular diameter ratios, and inlet fluid temperatures using water were considered. Turbulent flow with Reynolds numbers ranging from 15,000 to 45,000, based on the average bulk fluid temperature was tested at annular diameter ratios of 0.327, 0.386, 0.409 and 0.483 with hydraulic diameters of 17.00, 22.98, 20.20 and 26.18 mm respectively. Both heated and cooled annuli were investigated by conducting tests at a range of inlet temperatures between 10 °C to 30 °C for heating cases, and 30 °C to 50 °C for cooling cases. Of special interest was the direct measurement of local wall temperatures on the heat transfer surface, which is often difficult to obtain and evasive in data-sets. Continuous verification and re-evaluation of temperatures measurements were performed via in-situ calibration. It is shown that inlet fluid temperature and the heat transfer direction play significant roles on the magnitude of the heat transfer coefficient. A new adjusted Colburn j-factor definition is presented to describe the heating and cooling cases and is used to correlate the 894 test cases considered in this study.
Wavelet Correlation Coefficient of 'strongly correlated' financial time series
Razdan, Ashok
2003-01-01
In this paper we use wavelet concepts to show that correlation coefficient between two financial data's is not constant but varies with scale from high correlation value to strongly anti-correlation value This studies is important because correlation coefficient is used to quantify degree of independence between two variables. In econophysics correlation coefficient forms important input to evolve hierarchial tree and minimum spanning tree of financial data.
Alternatives to Pearson's and Spearman's Correlation Coefficients
Smarandache, Florentin
2008-01-01
This article presents several alternatives to Pearson's correlation coefficient and many examples. In the samples where the rank in a discrete variable counts more than the variable values, the mixtures that we propose of Pearson's and Spearman's correlation coefficients give better results.
Estimation of the simple correlation coefficient.
Shieh, Gwowen
2010-11-01
This article investigates some unfamiliar properties of the Pearson product-moment correlation coefficient for the estimation of simple correlation coefficient. Although Pearson's r is biased, except for limited situations, and the minimum variance unbiased estimator has been proposed in the literature, researchers routinely employ the sample correlation coefficient in their practical applications, because of its simplicity and popularity. In order to support such practice, this study examines the mean squared errors of r and several prominent formulas. The results reveal specific situations in which the sample correlation coefficient performs better than the unbiased and nearly unbiased estimators, facilitating recommendation of r as an effect size index for the strength of linear association between two variables. In addition, related issues of estimating the squared simple correlation coefficient are also considered.
A new proposal for Lagrangian correlation coefficient
International Nuclear Information System (INIS)
Altinsoy, N.; Tugrul, A.B.
2002-01-01
The statistical description of dispersion in turbulent flow was first considered by Taylor (Proc. London Math. Soc. 20 (1921) 196) and the statistical properties of the field were determined by Lagrangian correlation coefficient R L (τ). Frenkiel (Adv. Appl. Mech. 3 (1953) 61) has proposed several simple forms for R L (τ). Some workers have investigated for a proper form of the Lagrangian correlation coefficient. In this work, a new proposal for the Lagrangian correlation coefficient is proposed and discussed. It can be written in general form with the one of the Frenkiel's (Adv. Appl. Mech. 3 (1953) 61) Lagrangian correlation coefficient. There is very satisfactory agreement between the new correlation and the experiment
Correlation Coefficients: Appropriate Use and Interpretation.
Schober, Patrick; Boer, Christa; Schwarte, Lothar A
2018-05-01
Correlation in the broadest sense is a measure of an association between variables. In correlated data, the change in the magnitude of 1 variable is associated with a change in the magnitude of another variable, either in the same (positive correlation) or in the opposite (negative correlation) direction. Most often, the term correlation is used in the context of a linear relationship between 2 continuous variables and expressed as Pearson product-moment correlation. The Pearson correlation coefficient is typically used for jointly normally distributed data (data that follow a bivariate normal distribution). For nonnormally distributed continuous data, for ordinal data, or for data with relevant outliers, a Spearman rank correlation can be used as a measure of a monotonic association. Both correlation coefficients are scaled such that they range from -1 to +1, where 0 indicates that there is no linear or monotonic association, and the relationship gets stronger and ultimately approaches a straight line (Pearson correlation) or a constantly increasing or decreasing curve (Spearman correlation) as the coefficient approaches an absolute value of 1. Hypothesis tests and confidence intervals can be used to address the statistical significance of the results and to estimate the strength of the relationship in the population from which the data were sampled. The aim of this tutorial is to guide researchers and clinicians in the appropriate use and interpretation of correlation coefficients.
CFD Extraction of Heat Transfer Coefficient in Cryogenic Propellant Tanks
Yang, H. Q.; West, Jeff
2015-01-01
Current reduced-order thermal model for cryogenic propellant tanks is based on correlations built for flat plates collected in the 1950's. The use of these correlations suffers from inaccurate geometry representation; inaccurate gravity orientation; ambiguous length scale; and lack of detailed validation. This study uses first-principles based CFD methodology to compute heat transfer from the tank wall to the cryogenic fluids and extracts and correlates the equivalent heat transfer coefficient to support reduced-order thermal model. The CFD tool was first validated against available experimental data and commonly used correlations for natural convection along a vertically heated wall. Good agreements between the present prediction and experimental data have been found for flows in laminar as well turbulent regimes. The convective heat transfer between the tank wall and cryogenic propellant, and that between the tank wall and ullage gas were then simulated. The results showed that the commonly used heat transfer correlations for either vertical or horizontal plate over-predict heat transfer rate for the cryogenic tank, in some cases by as much as one order of magnitude. A characteristic length scale has been defined that can correlate all heat transfer coefficients for different fill levels into a single curve. This curve can be used for the reduced-order heat transfer model analysis.
Local heat transfer coefficient for turbulent flow in rod bundles
International Nuclear Information System (INIS)
Fernandez y Fernandez, E.; Carajilescov, P.
1983-03-01
The correlation of the local heat transfer coefficients in heated triangular array of rod bundles, in terms of the flow hydrodynamic parameters is presented. The analysis is made first for fluid with Prandtl numbers varying from moderated to high (Pr>0.2), and then extended to fluids with low Prandtl numbers (0.004 [pt
Temporal correlation coefficient for directed networks.
Büttner, Kathrin; Salau, Jennifer; Krieter, Joachim
2016-01-01
Previous studies dealing with network theory focused mainly on the static aggregation of edges over specific time window lengths. Thus, most of the dynamic information gets lost. To assess the quality of such a static aggregation the temporal correlation coefficient can be calculated. It measures the overall possibility for an edge to persist between two consecutive snapshots. Up to now, this measure is only defined for undirected networks. Therefore, we introduce the adaption of the temporal correlation coefficient to directed networks. This new methodology enables the distinction between ingoing and outgoing edges. Besides a small example network presenting the single calculation steps, we also calculated the proposed measurements for a real pig trade network to emphasize the importance of considering the edge direction. The farm types at the beginning of the pork supply chain showed clearly higher values for the outgoing temporal correlation coefficient compared to the farm types at the end of the pork supply chain. These farm types showed higher values for the ingoing temporal correlation coefficient. The temporal correlation coefficient is a valuable tool to understand the structural dynamics of these systems, as it assesses the consistency of the edge configuration. The adaption of this measure for directed networks may help to preserve meaningful additional information about the investigated network that might get lost if the edge directions are ignored.
Correlation and prediction of gaseous diffusion coefficients.
Marrero, T. R.; Mason, E. A.
1973-01-01
A new correlation method for binary gaseous diffusion coefficients from very low temperatures to 10,000 K is proposed based on an extended principle of corresponding states, and having greater range and accuracy than previous correlations. There are two correlation parameters that are related to other physical quantities and that are predictable in the absence of diffusion measurements. Quantum effects and composition dependence are included, but high-pressure effects are not. The results are directly applicable to multicomponent mixtures.
Ragui, Karim; Boutra, Abdelkader; Bennacer, Rachid; Labsi, Nabila; Benkahla, Youb Khaled
2018-02-01
The main purpose of our investigation is to show the impact of pertinent parameters; such Lewis and porous thermal Rayleigh numbers as well as the buoyancy and the aspect ratios; on the double-diffusive convection phenomena which occur within a porous annulus; found between a cold (and less concentric) outer circular cylinder and a hot (and concentric) inner one, to come out with global correlations which predict the mean transfer rates in such annulus. To do so, the physical model for the momentum conservation equation is made using the Brinkman extension of the classical Darcy equation. The set of coupled equations is solved using the finite volume method and the SIMPLER algorithm. Summarizing the numerical predictions, global correlations of overall transfer within the porous annulus as a function of the governing studied parameters are set forth which predict within ±2% the numerical results. These correlations may count as a complement to previous researches done in the case a Newtonian-fluid annulus. It is to note that the validity of the computing code used was ascertained by comparing our results with the experimental data and numerical ones already available in the literature.
Clustering stocks using partial correlation coefficients
Jung, Sean S.; Chang, Woojin
2016-11-01
A partial correlation analysis is performed on the Korean stock market (KOSPI). The difference between Pearson correlation and the partial correlation is analyzed and it is found that when conditioned on the market return, Pearson correlation coefficients are generally greater than those of the partial correlation, which implies that the market return tends to drive up the correlation between stock returns. A clustering analysis is then performed to study the market structure given by the partial correlation analysis and the members of the clusters are compared with the Global Industry Classification Standard (GICS). The initial hypothesis is that the firms in the same GICS sector are clustered together since they are in a similar business and environment. However, the result is inconsistent with the hypothesis and most clusters are a mix of multiple sectors suggesting that the traditional approach of using sectors to determine the proximity between stocks may not be sufficient enough to diversify a portfolio.
Analytic posteriors for Pearson's correlation coefficient.
Ly, Alexander; Marsman, Maarten; Wagenmakers, Eric-Jan
2018-02-01
Pearson's correlation is one of the most common measures of linear dependence. Recently, Bernardo (11th International Workshop on Objective Bayes Methodology, 2015) introduced a flexible class of priors to study this measure in a Bayesian setting. For this large class of priors, we show that the (marginal) posterior for Pearson's correlation coefficient and all of the posterior moments are analytic. Our results are available in the open-source software package JASP.
Analytic posteriors for Pearson's correlation coefficient
Ly, A.; Marsman, M.; Wagenmakers, E.-J.
2018-01-01
Pearson's correlation is one of the most common measures of linear dependence. Recently, Bernardo (11th International Workshop on Objective Bayes Methodology, 2015) introduced a flexible class of priors to study this measure in a Bayesian setting. For this large class of priors, we show that the (marginal) posterior for Pearson's correlation coefficient and all of the posterior moments are analytic. Our results are available in the open‐source software package JASP.
Transfer coefficients in elliptical tubes and plate fin heat exchangers
International Nuclear Information System (INIS)
Saboya, S.M.
1979-09-01
Mean transfer coefficients in elliptical tubes and plate fin heat exchangers were determined by application of heat and mass transfer analogy in conjunction with the naphthalene sublimation technique. The transfer coefficients are presented in a dimensionless form as functions of the Reynolds number. By using the least squares method analytical expressions for the transfer coefficients were determined with low scattering. (E.G.) [pt
The Evolution of Pearson's Correlation Coefficient
Kader, Gary D.; Franklin, Christine A.
2008-01-01
This article describes an activity for developing the notion of association between two quantitative variables. By exploring a collection of scatter plots, the authors propose a nonstandard "intuitive" measure of association; and by examining properties of this measure, they develop the more standard measure, Pearson's Correlation Coefficient. The…
Heat transfer coefficients during quenching of steels
Energy Technology Data Exchange (ETDEWEB)
Hasan, H.S.; Jalil, J.M. [University of Technology, Department of Electromechanical Engineering, Baghdad (Iraq); Peet, M.J.; Bhadeshia, H.K.D.H. [University of Cambridge, Department of Materials Science and Metallurgy, Cambridge (United Kingdom)
2011-03-15
Heat transfer coefficients for quenching in water have been measured as a function of temperature using steel probes for a variety of iron alloys. The coefficients were derived from measured cooling curves combined with calculated heat-capacities. The resulting data were then used to calculate cooling curves using the finite volume method for a large steel sample and these curves have been demonstrated to be consistent with measured values for the large sample. Furthermore, by combining the estimated cooling curves with time-temperature-transformation (TTT) diagrams it has been possible to predict the variation of hardness as a function of distance via the quench factor analysis. The work should prove useful in the heat treatment of the steels studied, some of which are in the development stage. (orig.)
Transfer coefficients for terrestrial foodchain: their derivation and limitations
International Nuclear Information System (INIS)
Ng, Y.C.; Colsher, C.S.; Thompson, S.E.
1979-01-01
Transfer coefficients to predict the passage of isotopes from the environment to terrestrial foods have been derived for various radionuclides of importance in the nuclear fuel cycle. These data update and extend previously recommended handbook values. We derive transfer coefficients to terrestrial foods and describe the systematics of the derived transfer coefficients. Suggestions are offered for changes in the values of transfer coefficients to terrestrial foods that now appear in federal regulatory guides. Deficiencies in our present knowledge concerning transfer coefficients and limitations in the use of these values to ensure compliance with radiation protection standards are discussed
Radionuclide transfer to animal products: revised recommended transfer coefficient values
International Nuclear Information System (INIS)
Howard, B.J.; Beresford, N.A.; Barnett, C.L.; Fesenko, S.
2009-01-01
A compilation has been undertaken of data which can be used to derive animal product transfer coefficients for radionuclides, including an extensive review of Russian language information. The resultant database has been used to provide recommended transfer coefficient values for a range of radionuclides to (i) cow, sheep and goat milk, (ii) meat (muscle) of cattle, sheep, goats, pigs and poultry and (iii) eggs. The values are used in a new IAEA handbook on transfer parameters which replaces that referred to as 'TRS 364'. The paper outlines the approaches and procedures used to identify and collate data, and assumptions used. There are notable differences between the TRS 364 'expected' values and the recommended values in the revised Handbook from the new database. Of the recommended values, three milk values are at least an order of magnitude higher than the TRS 364 values (Cr, Pu (cow) Pu (sheep)) and one milk value is lower (Ni (cow)). For meat, four values (Am, Cd, Sb (beef) I (pork)) are at least an order of magnitude higher than the TRS 364 values and eight values are at least an order of magnitude lower (Ru, Pu (beef), Ru, Sr, Zn (sheep), Ru, Sr (pork), Mn (poultry)). Many data gaps remain
Radionuclide transfer to animal products: revised recommended transfer coefficient values
Energy Technology Data Exchange (ETDEWEB)
Howard, B.J. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LAI 4AP (United Kingdom)], E-mail: bjho@ceh.ac.uk; Beresford, N.A.; Barnett, C.L. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LAI 4AP (United Kingdom); Fesenko, S. [International Atomic Energy Agency, 1400 Vienna (Austria)
2009-03-15
A compilation has been undertaken of data which can be used to derive animal product transfer coefficients for radionuclides, including an extensive review of Russian language information. The resultant database has been used to provide recommended transfer coefficient values for a range of radionuclides to (i) cow, sheep and goat milk, (ii) meat (muscle) of cattle, sheep, goats, pigs and poultry and (iii) eggs. The values are used in a new IAEA handbook on transfer parameters which replaces that referred to as 'TRS 364'. The paper outlines the approaches and procedures used to identify and collate data, and assumptions used. There are notable differences between the TRS 364 'expected' values and the recommended values in the revised Handbook from the new database. Of the recommended values, three milk values are at least an order of magnitude higher than the TRS 364 values (Cr, Pu (cow) Pu (sheep)) and one milk value is lower (Ni (cow)). For meat, four values (Am, Cd, Sb (beef) I (pork)) are at least an order of magnitude higher than the TRS 364 values and eight values are at least an order of magnitude lower (Ru, Pu (beef), Ru, Sr, Zn (sheep), Ru, Sr (pork), Mn (poultry)). Many data gaps remain.
Forecast Correlation Coefficient Matrix of Stock Returns in Portfolio Analysis
Zhao, Feng
2013-01-01
In Modern Portfolio Theory, the correlation coefficients decide the risk of a set of stocks in the portfolio. So, to understand the correlation coefficients between returns of stocks, is a challenge but is very important for the portfolio management. Usually, the stocks with small correlation coefficients or even negative correlation coefficients are preferred. One can calculate the correlation coefficients of stock returns based on the historical stock data. However, in order to control the ...
The Attenuation of Correlation Coefficients: A Statistical Literacy Issue
Trafimow, David
2016-01-01
Much of the science reported in the media depends on correlation coefficients. But the size of correlation coefficients depends, in part, on the reliability with which the correlated variables are measured. Understanding this is a statistical literacy issue.
Ghost imaging based on Pearson correlation coefficients
International Nuclear Information System (INIS)
Yu Wen-Kai; Yao Xu-Ri; Liu Xue-Feng; Li Long-Zhen; Zhai Guang-Jie
2015-01-01
Correspondence imaging is a new modality of ghost imaging, which can retrieve a positive/negative image by simple conditional averaging of the reference frames that correspond to relatively large/small values of the total intensity measured at the bucket detector. Here we propose and experimentally demonstrate a more rigorous and general approach in which a ghost image is retrieved by calculating a Pearson correlation coefficient between the bucket detector intensity and the brightness at a given pixel of the reference frames, and at the next pixel, and so on. Furthermore, we theoretically provide a statistical interpretation of these two imaging phenomena, and explain how the error depends on the sample size and what kind of distribution the error obeys. According to our analysis, the image signal-to-noise ratio can be greatly improved and the sampling number reduced by means of our new method. (paper)
Transfer coefficients for plate fin and elliptical tube heat exchangers
International Nuclear Information System (INIS)
Saboya, S.M.; Saboya, F.E.M.
1981-01-01
In order to determine transfer coefficients for plate fin and elliptical tube exchangers, mass transfer experiments have been performed using the naphthalene sublimation technique. By means of the heat-mass transfer analogy, the results can be converted to heat transfer results. The transfer coefficients were compared with those for circular tube exchangers and the comparison revealed no major differences. This is a positive outcome, since the use of elliptical tubes may reduce substantially the pressure drop, without affecting the transfer characteristics.(Author) [pt
Coefficients of tracer transfer through membranes. Pt. 7
Energy Technology Data Exchange (ETDEWEB)
Dorabialska, A; Hawlicka, E; Plonka, A [Politechnika Lodzka (Poland)
1974-01-01
The doubled value of the tracer transfer coefficient in the self-diffusion process is equal to the sum of tracer transfer coefficients in the diffusion and interfusion processes. The fundamental phenomenological relation can be deduced for the coefficients of tracer transfer between two phases of electrolyte solutions spearated by a virtual boundary. Indeed, the doubled value of the tracer mobility in the self-diffusion experiment (no concentration gradient of the traced substance) is equal to the sum of the tracer mobilities in the diffusion (tracer movement along with the concentration gradient of the traced substance) and interfusion experiments (tracer movement against the concentration gradient of the traced substance). Thus the doubled value of the tracer transfer coefficient in the self-diffusion process should be equal to the sum of tracer transfer coefficients in the diffusion and interfusion processes. The experimental verification of that fundamental relation is presented.
Yadav, Rupesh J.; Kore, Sandeep S.; Joshi, Prathamesh S.
2018-05-01
The experimental and numerical Nusselt number and friction factor investigation for turbulent flow through a non-circular duct with twisted-tape inserts have been presented. The non-circular ducts include square, hexagonal duct. The results of non-circular ducts are compared with circular duct. All the ducts have same equivalent diameter. The twist ratios used for the experiment are Y = 3.5, 4.5, 5.5 and 6.5. Experiments were carried out on square duct, hexagonal duct and circular duct. The Reynolds number lied between 10,000 and 1, 05,000. The present study is restricted to the flow of air at Pr = 0.7 only and within a narrow temperature range of 40 to 75 ΟC, within which the compressible nature of air can be neglected. The results reveal that, both Nusselt number and friction factor increases as the side of non-circular duct increases. Maximum Nusselt number and friction factor is obtained in case of circular duct with twisted tape. Further the correlations of Nu and f are given for different non circular duct with twisted tape insert for engineering applications for the turbulent regime. Since the thermal performance factor (η) is observed to be within the range of 0.8 to 1.13 for both circular and noncircular ducts, the overall benefit of using twisted tape in the flow field shall nevertheless be marginal.
On the heat transfer correlation for membrane distillation
International Nuclear Information System (INIS)
Wang, Chi-Chuan
2011-01-01
Research highlights: → Heat transfer coefficients applicable for membrane distillation. → Data reduction for heat transfer coefficient for membrane distillation method. → Uncertainty of permeate side due to large magnitude of membrane resistance. → Increase accuracy of heat transfer coefficient by modified Wilson plot technique. -- Abstract: The present study examines the heat transfer coefficients applicable for membrane distillation. In the available literatures, researchers often adopt some existing correlations and claim the suitability of these correlations to their test data or models. Unfortunately this approach is quite limited and questionable. This is subject to the influences of boundary conditions, geometrical configurations, entry flow conditions, as well as some influences from spacer or support. The simple way is to obtain the heat transfer coefficients from experimentation. However there is no direct experimental data for heat transfer coefficients being reported directly from the measurements. The main reasons are from the uncertainty of permeate side and of the comparatively large magnitude of membrane resistance. Additional minor influence is the effect of mass transfer on the heat transfer performance. In practice, the mass transfer effect is negligible provided the feed side temperature is low. To increase the accuracy of the measured feed side heat transfer coefficient, it is proposed in this study to exploit a modified Wilson plot technique. Through this approach, one can eliminate the uncertainty from permeate side and reduce the uncertainty in membrane to obtain a more reliable heat transfer coefficients at feed side from the experimentation.
Object detection by correlation coefficients using azimuthally averaged reference projections.
Nicholson, William V
2004-11-01
A method of computing correlation coefficients for object detection that takes advantage of using azimuthally averaged reference projections is described and compared with two alternative methods-computing a cross-correlation function or a local correlation coefficient versus the azimuthally averaged reference projections. Two examples of an application from structural biology involving the detection of projection views of biological macromolecules in electron micrographs are discussed. It is found that a novel approach to computing a local correlation coefficient versus azimuthally averaged reference projections, using a rotational correlation coefficient, outperforms using a cross-correlation function and a local correlation coefficient in object detection from simulated images with a range of levels of simulated additive noise. The three approaches perform similarly in detecting macromolecular views in electron microscope images of a globular macrolecular complex (the ribosome). The rotational correlation coefficient outperforms the other methods in detection of keyhole limpet hemocyanin macromolecular views in electron micrographs.
Non intrusive measurement of the convective heat transfer coefficient
Energy Technology Data Exchange (ETDEWEB)
Rebay, M.; Mebarki, G.; Padet, J. [Reims Univ., Reims (France). Faculty of Science, GRESPI Thermomechanical Lab; Arfaoui, A. [Reims Univ., Reims (France). Faculty of Science, GRESPI Thermomechanical Lab; Tunis Univ., Tunis (Tunisia). Faculty of Science, EL MANAR, LETTM; Maad, B.R. [Tunis Univ., Tunis (Tunisia). Faculty of Science, EL MANAR, LETTM
2010-07-01
The efficiency of cooling methods in thermal systems such as radiators and heat exchangers must be improved in order to enhance performance. The evaluation of the heat transfer coefficients between a solid and a fluid is necessary for the control and the dimensioning of thermal systems. In this study, the pulsed photothermal method was used to measure the convective heat transfer coefficient on a solid-fluid interface, notably between an air flow and a heated slab mounted on a PVC flat plate. This configuration simulated the electronic air-cooling inside enclosures and racks. The influence of the deflector's inclination angle on the enhancement of heat transfer was investigated using 2 newly developed identification models. The first model was based on a constant heat transfer coefficient during the pulsed experiment, while the second, improved model was based on a variable heat transfer coefficient. The heat transfer coefficient was deduced from the evolution of the transient temperature induced by a sudden deposit of a luminous energy on the front face of the slab. Temperature evolutions were derived by infrared thermography, a camera for cartography and a detector for precise measurement in specific locations. The results show the improvement of measurement accuracies when using a model that considers the temporal evolution of the convective heat transfer coefficient. The deflection of air flow on the upper surface of the heated slab demonstrated better cooling of the slab by the deflection of air flow. 11 refs., 1 tab., 8 figs.
Modified Regression Correlation Coefficient for Poisson Regression Model
Kaengthong, Nattacha; Domthong, Uthumporn
2017-09-01
This study gives attention to indicators in predictive power of the Generalized Linear Model (GLM) which are widely used; however, often having some restrictions. We are interested in regression correlation coefficient for a Poisson regression model. This is a measure of predictive power, and defined by the relationship between the dependent variable (Y) and the expected value of the dependent variable given the independent variables [E(Y|X)] for the Poisson regression model. The dependent variable is distributed as Poisson. The purpose of this research was modifying regression correlation coefficient for Poisson regression model. We also compare the proposed modified regression correlation coefficient with the traditional regression correlation coefficient in the case of two or more independent variables, and having multicollinearity in independent variables. The result shows that the proposed regression correlation coefficient is better than the traditional regression correlation coefficient based on Bias and the Root Mean Square Error (RMSE).
Overall mass-transfer coefficients in non-linear chromatography
DEFF Research Database (Denmark)
Mollerup, Jørgen; Hansen, Ernst
1998-01-01
In case of mass transfer where concentration differences in both phases must be taken into account, one may define an over-all mass-transfer coefficient basd on the apparent over-all concentration difference. If the equilibrium relationship is linear, i.e. in cases where a Henry´s law relationshi...
Measurement of heat transfer coefficient using termoanemometry methods
Dančová, P.; Sitek, P.; Vít, T.
2014-03-01
This work deals with a measurement of heat transfer from a heated flat plate on which a synthetic jet impacts perpendicularly. Measurement of a heat transfer coefficient (HTC) is carried out using the hot wire anemometry method with glue film probe Dantec 55M47. The paper brings also results of velocity profiles measurements and turbulence intensity calculations.
Measurement of heat transfer coefficient using termoanemometry methods
Directory of Open Access Journals (Sweden)
Dančová P.
2014-03-01
Full Text Available This work deals with a measurement of heat transfer from a heated flat plate on which a synthetic jet impacts perpendicularly. Measurement of a heat transfer coefficient (HTC is carried out using the hot wire anemometry method with glue film probe Dantec 55M47. The paper brings also results of velocity profiles measurements and turbulence intensity calculations.
Analytic posteriors for Pearson's correlation coefficient
Ly, A.; Marsman, M.; Wagenmakers, E.-J.
2018-01-01
Pearson's correlation is one of the most common measures of linear dependence. Recently, Bernardo (11th International Workshop on Objective Bayes Methodology, 2015) introduced a flexible class of priors to study this measure in a Bayesian setting. For this large class of priors, we show that the
A Note on the Correlated Random Coefficient Model
DEFF Research Database (Denmark)
Kolodziejczyk, Christophe
In this note we derive the bias of the OLS estimator for a correlated random coefficient model with one random coefficient, but which is correlated with a binary variable. We provide set-identification to the parameters of interest of the model. We also show how to reduce the bias of the estimator...
Testing the Difference of Correlated Agreement Coefficients for Statistical Significance
Gwet, Kilem L.
2016-01-01
This article addresses the problem of testing the difference between two correlated agreement coefficients for statistical significance. A number of authors have proposed methods for testing the difference between two correlated kappa coefficients, which require either the use of resampling methods or the use of advanced statistical modeling…
Accounting for Missing Correlation Coefficients in Fixed-Effects MASEM.
Jak, Suzanne; Cheung, Mike W-L
2018-01-01
Meta-analytic structural equation modeling (MASEM) is increasingly applied to advance theories by synthesizing existing findings. MASEM essentially consists of two stages. In Stage 1, a pooled correlation matrix is estimated based on the reported correlation coefficients in the individual studies. In Stage 2, a structural model (such as a path model) is fitted to explain the pooled correlations. Frequently, the individual studies do not provide all the correlation coefficients between the research variables. In this study, we modify the currently optimal MASEM-method to deal with missing correlation coefficients, and compare its performance with existing methods. This study is the first to evaluate the performance of fixed-effects MASEM methods under different levels of missing correlation coefficients. We found that the often used univariate methods performed very poorly, while the multivariate methods performed well overall.
Identification of MIMO systems with sparse transfer function coefficients
Qiu, Wanzhi; Saleem, Syed Khusro; Skafidas, Efstratios
2012-12-01
We study the problem of estimating transfer functions of multivariable (multiple-input multiple-output--MIMO) systems with sparse coefficients. We note that subspace identification methods are powerful and convenient tools in dealing with MIMO systems since they neither require nonlinear optimization nor impose any canonical form on the systems. However, subspace-based methods are inefficient for systems with sparse transfer function coefficients since they work on state space models. We propose a two-step algorithm where the first step identifies the system order using the subspace principle in a state space format, while the second step estimates coefficients of the transfer functions via L1-norm convex optimization. The proposed algorithm retains good features of subspace methods with improved noise-robustness for sparse systems.
Diabetic Erythrocytes Test by Correlation Coefficient
Korol, A.M; Foresto, P; Darrigo, M; Rosso, O.A
2008-01-01
Even when a healthy individual is studied, his/her erythrocytes in capillaries continually change their shape in a synchronized erratic fashion. In this work, the problem of characterizing the cell behavior is studied from the perspective of bounded correlated random walk, based on the assumption that diffractometric data involves both deterministic and stochastic components. The photometric readings are obtained by ektacytometry over several millions of shear elongated cells, using a home-made device called Erythrodeformeter. We have only a scalar signal and no governing equations; therefore the complete behavior has to be reconstructed in an artificial phase space. To analyze dynamics we used the technique of time delay coordinates suggested by Takens, May algorithm, and Fourier transform. The results suggest that on random-walk approach the samples from healthy controls exhibit significant differences from those from diabetic patients and these could allow us to claim that we have linked mathematical nonlinear tools with clinical aspects of diabetic erythrocytes’ rheological properties. PMID:19415139
Pearson's correlation coefficient in the theory of networks: A comment
Ahmed, Zafar; Kumar, Sachin
2018-01-01
In statistics, the Pearson correlation coefficient $r_{x,y}$ determines the degree of linear correlation between two variables and it is known that $-1 \\le r_{x,y} \\le 1$. In the theory of networks, a curious expression proposed in [PRL {\\bf 89} 208701 (2002)] for degree-degree correlation coefficient $r_{j_i,k_i}, i\\in [1,M]$ has been in use. We realize that the suggested form is the conventional Pearson's coefficient for $\\{(j_i,k_i), (k_i,j_i)\\}$ for $2M$ data points and hence it is rightl...
Someswara Rao, Chinta; Viswanadha Raju, S.
2016-01-01
In this paper, we consider correlation coefficient, rank correlation coefficient and cosine similarity measures for evaluating similarity between Homo sapiens and monkeys. We used DNA chromosomes of genome wide genes to determine the correlation between the chromosomal content and evolutionary relationship. The similarity among the H. sapiens and monkeys is measured for a total of 210 chromosomes related to 10 species. The similarity measures of these different species show the relationship b...
Heat transfer coefficients for particles in liquid in axially rotating cans
Hassan, B. H.
A theoretical analysis was carried out to determine the nondimensional parameters and corresponding correlations for the overall heat transfer coefficient (between the external steam and internal rotating liquid) and the liquid-particle film heat transfer coefficient for spherical particles in liquid in axially rotating 303 x 406 cans undergoing steam heating. The correlations were obtained from dimensional analysis of the equations of continuity, motion and energy, together with the thermal energy balances and the particle-fluid dynamics of the system. The theoretical solutions for the temperature distribution in spherical particles with a time varying boundary condition were presented.
Estimation of bulk transfer coefficient for latent heat flux (Ce)
Digital Repository Service at National Institute of Oceanography (India)
Sadhuram, Y.
The bulk transfer coefficient for latent heat flux (Ce) has been estimated over the Arabian Sea from the moisture budget during the pre-monsoon season of 1988. The computations have been made over two regions (A: 0-8 degrees N: 60-68 degrees E: B: 0...
[Electroencephalogram Feature Selection Based on Correlation Coefficient Analysis].
Zhou, Jinzhi; Tang, Xiaofang
2015-08-01
In order to improve the accuracy of classification with small amount of motor imagery training data on the development of brain-computer interface (BCD systems, we proposed an analyzing method to automatically select the characteristic parameters based on correlation coefficient analysis. Throughout the five sample data of dataset IV a from 2005 BCI Competition, we utilized short-time Fourier transform (STFT) and correlation coefficient calculation to reduce the number of primitive electroencephalogram dimension, then introduced feature extraction based on common spatial pattern (CSP) and classified by linear discriminant analysis (LDA). Simulation results showed that the average rate of classification accuracy could be improved by using correlation coefficient feature selection method than those without using this algorithm. Comparing with support vector machine (SVM) optimization features algorithm, the correlation coefficient analysis can lead better selection parameters to improve the accuracy of classification.
Yang, H. Q.; West, Jeff
2015-01-01
Current reduced-order thermal model for cryogenic propellant tanks is based on correlations built for flat plates collected in the 1950's. The use of these correlations suffers from: inaccurate geometry representation; inaccurate gravity orientation; ambiguous length scale; and lack of detailed validation. The work presented under this task uses the first-principles based Computational Fluid Dynamics (CFD) technique to compute heat transfer from tank wall to the cryogenic fluids, and extracts and correlates the equivalent heat transfer coefficient to support reduced-order thermal model. The CFD tool was first validated against available experimental data and commonly used correlations for natural convection along a vertically heated wall. Good agreements between the present prediction and experimental data have been found for flows in laminar as well turbulent regimes. The convective heat transfer between tank wall and cryogenic propellant, and that between tank wall and ullage gas were then simulated. The results showed that commonly used heat transfer correlations for either vertical or horizontal plate over predict heat transfer rate for the cryogenic tank, in some cases by as much as one order of magnitude. A characteristic length scale has been defined that can correlate all heat transfer coefficients for different fill levels into a single curve. This curve can be used for the reduced-order heat transfer model analysis.
Zhang, Juping; Yang, Chan; Jin, Zhen; Li, Jia
2018-07-14
In this paper, the correlation coefficients between nodes in states are used as dynamic variables, and we construct SIR epidemic dynamic models with correlation coefficients by using the pair approximation method in static networks and dynamic networks, respectively. Considering the clustering coefficient of the network, we analytically investigate the existence and the local asymptotic stability of each equilibrium of these models and derive threshold values for the prevalence of diseases. Additionally, we obtain two equivalent epidemic thresholds in dynamic networks, which are compared with the results of the mean field equations. Copyright © 2018 Elsevier Ltd. All rights reserved.
Limits of the memory coefficient in measuring correlated bursts
Jo, Hang-Hyun; Hiraoka, Takayuki
2018-03-01
Temporal inhomogeneities in event sequences of natural and social phenomena have been characterized in terms of interevent times and correlations between interevent times. The inhomogeneities of interevent times have been extensively studied, while the correlations between interevent times, often called correlated bursts, are far from being fully understood. For measuring the correlated bursts, two relevant approaches were suggested, i.e., memory coefficient and burst size distribution. Here a burst size denotes the number of events in a bursty train detected for a given time window. Empirical analyses have revealed that the larger memory coefficient tends to be associated with the heavier tail of the burst size distribution. In particular, empirical findings in human activities appear inconsistent, such that the memory coefficient is close to 0, while burst size distributions follow a power law. In order to comprehend these observations, by assuming the conditional independence between consecutive interevent times, we derive the analytical form of the memory coefficient as a function of parameters describing interevent time and burst size distributions. Our analytical result can explain the general tendency of the larger memory coefficient being associated with the heavier tail of burst size distribution. We also find that the apparently inconsistent observations in human activities are compatible with each other, indicating that the memory coefficient has limits to measure the correlated bursts.
Transfer coefficients of radionuclides from feed to livestock products
International Nuclear Information System (INIS)
1995-03-01
The accumulation of data on radionuclide transfer are poor in Japan and those are limited to 90 Sr, 137 Cs and 131 I released from the previous atomic bomb experiments. However, in Europe, intensive studies on environment RI level which affects the restriction of the intake for meats and milk products have been made as the measures against the environment radioactivity due to Chernobyl accident. The transfer coefficients of radionuclides to meats and milk products were estimated on a basis of the data published in the Science of the Total Environment vol.85(1989), Oxford University and CEC Radiation Protection, EUR 12608 EN, Luxembourg, 1990 in addition to the data on Exclusion of Radioactivity from foods, Environment Parameter, series No. 4. On the other hand, the transfer coefficients for Japanese were estimated using the concerned data from published reports and the environment radioactivity data reported by national and local government bodies. In this book, many new data of transfer coefficient are presented in tables along with the previous data collected by international nuclear energy agencies and respective national facilities concerned. (M.N.)
Energy Technology Data Exchange (ETDEWEB)
Donne, M.D.; Piazza, G. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Neutronenphysik und Reaktortechnik; Goraieb, A.; Sordon, G.
1998-01-01
The four ITER partners propose to use binary beryllium pebble bed as neutron multiplier. Recently this solution has been adopted for the ITER blanket as well. In order to study the heat transfer in the blanket the effective thermal conductivity and the wall heat transfer coefficient of the bed have to be known. Therefore at Forschungszentrum Karlsruhe heat transfer experiments have been performed with a binary bed of beryllium pebbles and the results have been correlated expressing thermal conductivity and wall heat transfer coefficients as a function of temperature in the bed and of the difference between the thermal expansion of the bed and of that of the confinement walls. The comparison of the obtained correlations with the data available from the literature show a quite good agreement. (author)
Directory of Open Access Journals (Sweden)
WANG Fang
2017-04-01
Full Text Available Aimed to insufficient heat transfer of heat exchanger, research the influence on the heat transfer coefficient impacted by velocity and heat transfer temperature difference of tube heat exchanger. According to the different heat transfer temperature difference and gas velocity，the experimental data were divided into group. Using the control variable method，the above two factors were analyzed separately. K一△T and k一:fitting curve were clone to obtain empirical function. The entire heat exchanger is as the study object，using numerical simulation methods，porous media，k一￡model，second order upwind mode，and pressure一velocity coupling with SIMPLE algorithm，the entire heat exchanger temperature field and the heat transfer coefficient distribution were given. Finally the trend of the heat transfer coefficient effected by the above two factors was gotten.
Statistical Study of Turbulence: Spectral Functions and Correlation Coefficients
Frenkiel, Francois N.
1958-01-01
In reading the publications on turbulence of different authors, one often runs the risk of confusing the various correlation coefficients and turbulence spectra. We have made a point of defining, by appropriate concepts, the differences which exist between these functions. Besides, we introduce in the symbols a few new characteristics of turbulence. In the first chapter, we study some relations between the correlation coefficients and the different turbulence spectra. Certain relations are given by means of demonstrations which could be called intuitive rather than mathematical. In this way we demonstrate that the correlation coefficients between the simultaneous turbulent velocities at two points are identical, whether studied in Lagrange's or in Euler's systems. We then consider new spectra of turbulence, obtained by study of the simultaneous velocities along a straight line of given direction. We determine some relations between these spectra and the correlation coefficients. Examining the relation between the spectrum of the turbulence measured at a fixed point and the longitudinal-correlation curve given by G. I. Taylor, we find that this equation is exact only when the coefficient is very small.
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
Heat transfer coefficient between UO2 and Zircaloy-2
International Nuclear Information System (INIS)
Ross, A.M.; Stoute, R.L.
1962-06-01
This paper provides some experimental values of the heat-transfer coefficient between UO 2 and Zircaloy-2 surfaces in contact under conditions of interfacial pressure, temperature, surface roughness and interface atmosphere, that are relevant to UO 2 /Zircaloy-2 fuel elements operating in pressurized-water power reactors. Coefficients were obtained from eight UO 2 / Zircaloy-2 pairs in atmospheres of helium, argon, krypton or xenon, at atmosphere pressure and in vacuum. Interfacial pressures were varied from 50 to 550 kgf/cm 2 while surface roughness heights were in the range 0.2 x 10 -4 to 3.5 x 10 -4 cm. The effect on the coefficients of cycling the interfacial pressure, of interface gas pressure and of temperature were examined. The experimental values of the coefficients were used to test the predictions of expressions for the heat-transfer between two solids in contact. For the particular UO 2 / Zircaloy-2 pairs examined, numerical values were assigned to several parameters that related the surface roughnesses to either the radius of solid/solid contact spots or to the mean thickness of the interface voids and that accounted for the imperfect accommodation of the void gas on the test surfaces. (author)
Someswara Rao, Chinta; Viswanadha Raju, S
2016-03-01
In this paper, we consider correlation coefficient, rank correlation coefficient and cosine similarity measures for evaluating similarity between Homo sapiens and monkeys. We used DNA chromosomes of genome wide genes to determine the correlation between the chromosomal content and evolutionary relationship. The similarity among the H. sapiens and monkeys is measured for a total of 210 chromosomes related to 10 species. The similarity measures of these different species show the relationship between the H. sapiens and monkey. This similarity will be helpful at theft identification, maternity identification, disease identification, etc.
Distributing Correlation Coefficients of Linear Structure-Activity/Property Models
Directory of Open Access Journals (Sweden)
Sorana D. BOLBOACA
2011-12-01
Full Text Available Quantitative structure-activity/property relationships are mathematical relationships linking chemical structure and activity/property in a quantitative manner. These in silico approaches are frequently used to reduce animal testing and risk-assessment, as well as to increase time- and cost-effectiveness in characterization and identification of active compounds. The aim of our study was to investigate the pattern of correlation coefficients distribution associated to simple linear relationships linking the compounds structure with their activities. A set of the most common ordnance compounds found at naval facilities with a limited data set with a range of toxicities on aquatic ecosystem and a set of seven properties was studied. Statistically significant models were selected and investigated. The probability density function of the correlation coefficients was investigated using a series of possible continuous distribution laws. Almost 48% of the correlation coefficients proved fit Beta distribution, 40% fit Generalized Pareto distribution, and 12% fit Pert distribution.
Saponification reaction system: a detailed mass transfer coefficient determination.
Pečar, Darja; Goršek, Andreja
2015-01-01
The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach.
Highlighting material structure with transmission electron diffraction correlation coefficient maps
International Nuclear Information System (INIS)
Kiss, Ákos K.; Rauch, Edgar F.; Lábár, János L.
2016-01-01
Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast. - Highlights: • We propose a novel technique to image the structure of polycrystalline TEM-samples. • Correlation coefficients maps highlights the evolution of the diffracting signal. • 3D views of grain boundaries are provided for nano-particles or polycrystals.
Effect of pressure on heat transfer coefficient at the metal/mold interface of A356 aluminum alloy
DEFF Research Database (Denmark)
Fardi Ilkhchy, A.; Jabbari, Masoud; Davami, P.
2012-01-01
The aim of this paper is to correlate interfacial heat transfer coefficient (IHTC) to applied external pressure, in which IHTC at the interface between A356 aluminum alloy and metallic mold during the solidification of casting under different pressures were obtained using the inverse heat...... conduction problem (IHCP) method. The method covers the expedient of comparing theoretical and experimental thermal histories. Temperature profiles obtained from thermocouples were used in a finite difference heat flow program to estimate the transient heat transfer coefficients. The new simple formula...... was presented for correlation between external pressure and heat transfer coefficient. Acceptable agreement with data in literature shows the accuracy of the proposed formula....
A comparison of two indices for the intraclass correlation coefficient.
Shieh, Gwowen
2012-12-01
In the present study, we examined the behavior of two indices for measuring the intraclass correlation in the one-way random effects model: the prevailing ICC(1) (Fisher, 1938) and the corrected eta-squared (Bliese & Halverson, 1998). These two procedures differ both in their methods of estimating the variance components that define the intraclass correlation coefficient and in their performance of bias and mean squared error in the estimation of the intraclass correlation coefficient. In contrast with the natural unbiased principle used to construct ICC(1), in the present study it was analytically shown that the corrected eta-squared estimator is identical to the maximum likelihood estimator and the pairwise estimator under equal group sizes. Moreover, the empirical results obtained from the present Monte Carlo simulation study across various group structures revealed the mutual dominance relationship between their truncated versions for negative values. The corrected eta-squared estimator performs better than the ICC(1) estimator when the underlying population intraclass correlation coefficient is small. Conversely, ICC(1) has a clear advantage over the corrected eta-squared for medium and large magnitudes of population intraclass correlation coefficient. The conceptual description and numerical investigation provide guidelines to help researchers choose between the two indices for more accurate reliability analysis in multilevel research.
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.
Lee, C. M.; Addy, H. E.; Bond, T. H.; Chun, K. S.; Lu, C. Y.
1987-01-01
The main objective of this report was to derive equations to estimate heat transfer coefficients in both the combustion chamber and coolant pasage of a rotary engine. This was accomplished by making detailed temperature and pressure measurements in a direct-injection stratified-charge rotary engine under a range of conditions. For each sppecific measurement point, the local physical properties of the fluids were calculated. Then an empirical correlation of the coefficients was derived by using a multiple regression program. This correlation expresses the Nusselt number as a function of the Prandtl number and Reynolds number.
Effect of design and operation parameters on heat transfer coefficient in condensers
International Nuclear Information System (INIS)
Eskin, N.; Arslan, G.; Balci, T.
2009-01-01
Accurate and optimum usage of energy sources is gaining importance all over the world due to the increase of energy need and limited energy sources. Increasing condenser efficiency, reduce both the dimensions and the material usage and also the investment cost of the devices. This can be maintained by increasing the heat transfer coefficient in condensers. Generally, tubes having plain inner surfaces are mounted horizontally in serpentine type condenser applications and due to the performance loss results from the congestion in serpentine connections, vertical tube mounting is not preferred. Due to the complexity of the two-phase flow, a single set of correlation for heat transfer cannot be used. Average and local heat transfer coefficient for condensers are determined. Moreover, for each experiments flow pattern is determined and the validity of the correlations are compared according to that flow pattern. In Table 2, some of the experiments for R134a are listed. Local heat transfer coefficient is also important for condenser design. As a result, to design effective condensers the accuracy of the correlations is very important. When all the experiments are taken into account, it is seen that deviation of the correlations differs according to the refrigerant type, tube dimensions, mass flux, saturation temperature and flow pattern. For high mass flux (>400 kg/m 2 s) Traviss (1973) correlation failed. For small diameters (<3.14 mm) Tandon (1985) correlation estimate the heat transfer coefficient with a high deviation. Most accurate results are obtained for Akers et al. (1959), M.M. Shah (1978), Cavallini and Zecchlin (1974), J.R. Thome - J. El Hajal - A. Cavallini (2003) correlations. For high mass flux and annular flow, M.M. Shah (1978) correlation estimates the heat transfer coefficient with high precision. However, as the tube diameter decrease, this deviation increases. For small tube diameter such as 0.691 mm Cavallini and Zecchlin (1974) gives the most
A new correlation for two-phase critical discharge coefficient
International Nuclear Information System (INIS)
Park, Jong Woon; Chun, Moon Hyun
1989-01-01
A new simple correlation for subcooled and two-phase critical flow discharge coefficient has been developed by stepwise regression technique. The new discharge coefficient has three independent variables and they are length to hydraulic diameter ratio, degree of subcooling, and stagnation temperature. The new discharge coefficient is applied as a multiplier to homogeneous equilibrium model and Abauf's single phase critical mass flux calculation equation. This method has been tested for its accuracy by comparing with experimental data. Results of the comparison show that the agreement between the predictions with new correlation and the experimental data is good for pipes and nozzles with vertical upward flow for subcooled upstream condition and nozzles with horizontal configuration for two-phase upstream condition
Variability, correlation and path coefficient analysis of seedling traits ...
African Journals Online (AJOL)
use
2011-12-12
Dec 12, 2011 ... Indirect selection is a useful means for improving yield in cotton crop. The objective of the present study was to determine the genetic variability, broad sense heritability, genetic advance and correlation among the six seedling traits and their direct and indirect effects on cotton yield by using path coefficient ...
Variability, correlation and path coefficient analysis of seedling traits ...
African Journals Online (AJOL)
Indirect selection is a useful means for improving yield in cotton crop. The objective of the present study was to determine the genetic variability, broad sense heritability, genetic advance and correlation among the six seedling traits and their direct and indirect effects on cotton yield by using path coefficient analysis.
On the misinterpretation of the correlation coefficient in pharmaceutical sciences
DEFF Research Database (Denmark)
Sonnergaard, Jørn
2006-01-01
The correlation coefficient is often used and more often misused as a universal parameter expressing the quality in linear regression analysis. The popularity of this dimensionless quantity is evident as it is easy to communicate and considered to be unproblematic to comprehend. However, illustra...
Time correlation functions and transport coefficients in a dilute superfluid
International Nuclear Information System (INIS)
Kirkpatrick, T.R.; Dorfman, J.R.
1985-01-01
Time correlation functions for the transport coefficients in the linear Landau-Khalatnikov equations are derived on the basis of a formal theory. These Green--Kubo expressions are then explicitly evaluated for a dilute superfluid and the resulting transport coefficiencts are shown to be identical to those obtained previously by using a distribution function method
Correlation Revelation: The Search for Meaning in Pearson's Coefficient
Huhn, Craig
2016-01-01
When the author was first charged with getting a group of students to understand the correlation coefficient, he did not anticipate the topic would challenge his own understanding, let alone cause him to eventually question the very nature of mathematics itself. On the surface, the idea seemed straightforward, one that millions of students across…
Modeling Concordance Correlation Coefficient for Longitudinal Study Data
Ma, Yan; Tang, Wan; Yu, Qin; Tu, X. M.
2010-01-01
Measures of agreement are used in a wide range of behavioral, biomedical, psychosocial, and health-care related research to assess reliability of diagnostic test, psychometric properties of instrument, fidelity of psychosocial intervention, and accuracy of proxy outcome. The concordance correlation coefficient (CCC) is a popular measure of…
Highlighting material structure with transmission electron diffraction correlation coefficient maps.
Kiss, Ákos K; Rauch, Edgar F; Lábár, János L
2016-04-01
Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast. Copyright © 2016 Elsevier B.V. All rights reserved.
Transfer coefficients of radionuclides secreted in milk of dairy cows
International Nuclear Information System (INIS)
Sam, D.; Williams, W.F.; Rockmann, D.D.; Allen, J.T.
1980-01-01
This study simulated experimentally the transfer of radionuclides to milk of dairy cows on a worst-case situation using various radionuclides known to emanate from nuclear power stations and which have been detected on particulates. Two lactating Holstein cows were administered orally one gelatin capsule containing 10 radionuclides in water-soluble form per day for 14 consecutive days. Milk samples were collected and aliquots analyzed in a germanium lithium-drifted detector coupled to a 2048-multichannel gamma-ray analyzer to measure small amounts of complex mixtures of radionuclides. The transfer coefficients of the radionuclides were calculated when their secretion in milk reached or approached a plateau of concentration. The radionuclides and their transfer coefficients to milk were: chromium 51 less than 0.01%; manganese 54 0.033 +- 0.005%; cobalt 60 0.01 +- 0.002%; iron 59 0.0048 +- 0.002%; zinc 65 0.31 +- 0.07%; selenium 75 0.29 +- 0.1%; antimony 125 0.011 +- 0.003%; iodine 131 0.88 +- 0.05%; and cesium 137 0.79 +- 0.08%
International Nuclear Information System (INIS)
Zokaei-Kadijani, S.; Safdari, J.; Mousavian, M.A.; Rashidi, A.
2013-01-01
Highlights: ► Mass transfer coefficient does not depend on biomass concentration. ► The pulp density has a negative effect on mass transfer coefficient. ► The pulp density is the unique factor that affects maximum OUR. ► In this work, Neale’s correlation is corrected for prediction of mass transfer coefficient. ► Biochemical reaction is a limiting factor in the uranium bioleaching process. - Abstract: In this work, the volumetric oxygen mass transfer coefficient and the oxygen uptake rate (OUR) were studied for uranium ore bioleaching process by Acidthiobacillus ferrooxidans in a stirred tank reactor. The Box-Bohnken design method was used to study the effect of operating parameters on the oxygen mass transfer coefficient. The investigated factors were agitation speed (rpm), aeration rate (vvm) and pulp density (% weight/volume) of the stirred tank reactor. Analysis of experimental results showed that the oxygen mass transfer coefficient had low dependence on biomass concentration but had higher dependence on the agitation speed, aeration rate and pulp density. The obtained biological enhancement factors were equal to ones in experiments. On the other hand, the obtained values for Damkohler number (Da < 0.468) indicated that the process was limited by the biochemical reaction rate. Experimental results obtained for oxygen mass transfer coefficient were correlated with the empirical relations proposed by Garcia-Ochoa and Gomez (2009) and Neale and Pinches (1994). Due to the high relative error in the correlation of Neale and Pinches, that correlation was corrected and the coefficient of determination was calculated to be 89%. The modified correlation has been obtained based on a wide range of operating conditions, which can be used to determine the mass transfer coefficient in a bioreactor
Local heat transfer coefficient in a fluidized bed
International Nuclear Information System (INIS)
Al-Busoul, A. M.
1999-01-01
This paper presents an experimental study for the local heat transfer coefficient. The experiments was conducted inside a reactor with inner diameter (I D = 142mm) at atmospheric conditions (temperature mean value = 29 deg.) The bed was heated by means of a parochial electric heater with a diameter of (d h = 29 mm) and a constant power of 5W. The following factors varied: particles type and diameter, fluid velocity, bed height and heater position inside the reactor. The results were presented and discussed. (author). 15 refs., 7 figs
Thermal properties and heat transfer coefficients in cryogenic cooling
Biddulph, M. W.; Burford, R. P.
This paper considers two aspects of the design of the cooling stage of the process known as cryogenic recycling. This process uses liquid nitrogen to embrittle certain materials before grinding and subsequent separation. It is being increasingly used in materials recycling. A simple method of establishing thermal diffusivity values of materials of interest by using cooling curves is described. These values are important for effective cooler design. In addition values of convective heat transfer coefficient have been determined in an operating inclined, rotating cylindrical cooler operating on scrap car tyres. These will also be useful for cooler design methods.
Heat Transfer Coefficient Variations in Nuclear Fuel Rod Bundles
International Nuclear Information System (INIS)
Conner, Michael E.; Holloway, Mary V.
2007-01-01
The single-phase heat transfer performance of a PWR nuclear fuel rod bundle is enhanced by the use of mixing vanes attached to the downstream edges of the support grid straps. This improved single-phase performance will delay the onset of nucleate boiling, thereby reducing corrosion and delaying crud-related issues. This paper presents the variation in measured single-phase heat transfer coefficients (HTC) for several grid designs. Then, this variation is compared with observations of actual in-core crud patterns. While crud deposition is a function of a number of parameters including rod heat flux, the HTC is assumed to be a primary factor in explaining why crud deposition is a local phenomenon on nuclear fuel rods. The data from this study will be used to examine this assumption by providing a comparison between HTC variations and crud deposition patterns. (authors)
International Nuclear Information System (INIS)
Petrasch, Joerg; Meier, Fabian; Friess, Hansmartin; Steinfeld, Aldo
2008-01-01
A computer tomography based methodology is applied to determine the transport properties of fluid flow across porous media. A 3D digital representation of a 10-ppi reticulate porous ceramic (RPC) sample was generated by X-ray tomographic scans. Structural properties such as the porosity, specific interfacial surface area, pore-size distribution, mean survival time, two-point correlation function s 2 , and local geometry distribution of the RPC sample are directly extracted from the tomographic data. Reference solutions of the fluid flow governing equations are obtained for Re = 0.2-200 by applying finite volume direct pore-level numerical simulation (DPLS) using unstructured, body-fitted, tetrahedral mesh discretization. The permeability and the Dupuit-Forchheimer coefficient are determined from the reference solutions by DPLS, and compared to the values predicted by selected porous media flow models, namely: conduit-flow, hydraulic radius theory, drag models, mean survival time bound, s 2 -bound, fibrous bed correlations, and local porosity theory-based models. DPLS is further employed to determine the interfacial heat transfer coefficient and to derive a corresponding Nu-correlation, which is compared to empirical correlations
Enhancement of pool boiling heat transfer coefficients using carbon nanotubes
International Nuclear Information System (INIS)
Park, Ki Jung; Jung, Dong Soo
2007-01-01
In this study, the effect of carbon nanotubes (CNTs) on nucleate boiling heat transfer is investigated. Three refrigerants of R22, R123, R134a, and water were used as working fluids and 1.0 vol.% of CNTs was added to the working fluids to examine the effect of CNTs. Experimental apparatus was composed of a stainless steel vessel and a plain horizontal tube heated by a cartridge heater. All data were obtained at the pool temperature of 7 .deg. C for all refrigerants and 100 .deg. C for water in the heat flux range of 10∼80 kW/m 2 . Test results showed that CNTs increase nucleate boiling heat transfer coefficients for all fluids. Especially, large enhancement was observed at low heat fluxes of less than 30 kW/m 2 . With increasing heat flux, however, the enhancement was suppressed due to vigorous bubble generation. Fouling on the heat transfer surface was not observed during the course of this study. Optimum quantity and type of CNTs and their dispersion should be examined for their commercial application to enhance nucleate boiling heat transfer in many applications
Estimation of the heat transfer coefficient in melt spinning process
International Nuclear Information System (INIS)
Tkatch, V I; Maksimov, V V; Grishin, A M
2009-01-01
Effect of the quenching wheel velocity in the range 20.7-26.5 m/s on the cooling rate as well as on the structure and microtopology of the contact surfaces of the glass-forming FeNiPB melt-spun ribbons has been experimentally studied. Both the values of the cooling rate and heat transfer coefficient at the wheel-ribbon interface estimated from the temperature vs. time curves recorded during melt spinning runs are in the ranges (1.6-5.2)x10 6 K/s and (2.8-5.2)x10 5 Wm -2 K -1 , respectively, for ribbon thicknesses of 31.4-22.0 μm. It was found that the density of the air pockets at the underside surface of ribbons decreases while its average depth remains essentially unchanged with the wheel velocity. Using the surface quality parameters the values of the heat transfer coefficient in the areas of direct ribbon-wheel contact were evaluated to be ranging from 5.75 to 6.65x10 5 Wm -2 K -1 .
The prediction of heat transfer coefficient in circulating fluidized bed combustors
International Nuclear Information System (INIS)
Hamdan, M.A.; Al-qaq, A.M.
2008-01-01
In the present work, a theoretical study is performed to modify an existing model that is used to predict the heat transfer coefficient in circulating fluidized bed combustors. In the model, certain parameters were used as being of constant values, which leads to an error in the obtained value of the heat transfer coefficient. In this study and as a first step, the model is thoroughly studied and then the variation of the coefficient with these parameters is presented. Having done that, correlation for these parameters are obtained and then used in the model. Finally the modified model was tested against previously experimental and theoretical data that is available in literature. It was found that the accuracy of the model has been improved after it has been modified
The prediction of heat transfer coefficient in circulating fluidized bed combustors
Energy Technology Data Exchange (ETDEWEB)
Hamdan, M.A.; Al-qaq, A.M. [Department of Mechanical Engineering, University of Jordan Amman, Qween Rania Street, Amman, AL Jbeeha 11942 (Jordan)
2008-11-15
In the present work, a theoretical study is performed to modify an existing model that is used to predict the heat transfer coefficient in circulating fluidized bed combustors. In the model, certain parameters were used as being of constant values, which leads to an error in the obtained value of the heat transfer coefficient. In this study and as a first step, the model is thoroughly studied and then the variation of the coefficient with these parameters is presented. Having done that, correlation for these parameters are obtained and then used in the model. Finally the modified model was tested against previously experimental and theoretical data that is available in literature. It was found that the accuracy of the model has been improved after it has been modified. (author)
Heat transfer coefficient as parameter describing ability of insulating liquid to heat transfer
Nadolny, Zbigniew; Gościński, Przemysław; Bródka, Bolesław
2017-10-01
The paper presents the results of the measurements of heat transfer coefficient of insulating liquids used in transformers. The coefficient describes an ability of the liquid to heat transport. On the basis of the coefficient, effectiveness of cooling system of electric power devices can be estimated. Following liquids were used for the measurements: mineral oil, synthetic ester and natural ester. It was assumed that surface heat load is about 2500 W·m-2, which is equal the load of transformer windings. A height of heat element was 1.6 m, because it makes possible steady distribution of temperature on its surface. The measurements of heat transfer coefficient was made as a function of various position of heat element (vertical, horizontal). In frame of horizontal position of heat element, three suppositions were analysed: top, bottom, and side.
Heat transfer coefficient as parameter describing ability of insulating liquid to heat transfer
Directory of Open Access Journals (Sweden)
Nadolny Zbigniew
2017-01-01
Full Text Available The paper presents the results of the measurements of heat transfer coefficient of insulating liquids used in transformers. The coefficient describes an ability of the liquid to heat transport. On the basis of the coefficient, effectiveness of cooling system of electric power devices can be estimated. Following liquids were used for the measurements: mineral oil, synthetic ester and natural ester. It was assumed that surface heat load is about 2500 W·m-2, which is equal the load of transformer windings. A height of heat element was 1.6 m, because it makes possible steady distribution of temperature on its surface. The measurements of heat transfer coefficient was made as a function of various position of heat element (vertical, horizontal. In frame of horizontal position of heat element, three suppositions were analysed: top, bottom, and side.
Apparent diffusion coefficient correlation with oesophageal tumour stroma and angiogenesis
Energy Technology Data Exchange (ETDEWEB)
Aoyagi, Tomoyoshi; Shuto, Kiyohiko; Okazumi, Shinichi; Hayano, Kohichi; Satoh, Asami; Saitoh, Hiroshige; Shimada, Hideaki; Nabeya, Yoshihiro; Matsubara, Hisahiro [Chiba University, Department of Frontier Surgery, Graduate School of Medicine, Chiba (Japan); Kazama, Toshiki [Chiba University, Department of Radiology, Graduate School of Medicine, Chiba (Japan)
2012-06-15
Because diffusion-weighted imaging (DWI) can predict the prognosis of patients with oesophageal squamous cell carcinoma (ESCC), we hypothesised that apparent diffusion coefficient (ADC) values might be correlated with the collagen content and tumour angiogenesis. The purpose of this study was to determine the correlation between ADC values of ESCC before treatment and oesophageal tumour stroma and angiogenesis. Seventeen patients with ESCC were enrolled. The ADC values were calculated from the DWI score. Seventeen patients who had undergone oesophagectomy were analysed for tumour stroma, vascular endothelial growth factor (VEGF) and CD34. Tissue collagen was stained with azocarmine and aniline blue to quantitatively analyse the extracellular matrix in cancer stroma. Tissues were stained with VEGF and CD34 to analyse the angiogenesis. The ADC values decreased with stromal collagen growth. We found a negative correlation between the tumour ADC and the amount of stromal collagen (r = -0.729, P = 0.001), i.e. the ADC values decreased with growth of VEGF. We also found a negative correlation between the ADC of the tumours and the amount of VEGF (r = 0.538, P = 0.026). Our results indicated that the ADC value may be a novel prognostic factor and contribute to the treatment of oesophageal cancer. circle Magnetic resonance apparent diffusion coefficient values inversely indicate tumour stromal collagen circle There is also negative correlation between ADCs and vascular endothelial growth factor circle ADC values may contribute to the treatment of oesophageal cancer. (orig.)
Apparent diffusion coefficient correlation with oesophageal tumour stroma and angiogenesis
International Nuclear Information System (INIS)
Aoyagi, Tomoyoshi; Shuto, Kiyohiko; Okazumi, Shinichi; Hayano, Kohichi; Satoh, Asami; Saitoh, Hiroshige; Shimada, Hideaki; Nabeya, Yoshihiro; Matsubara, Hisahiro; Kazama, Toshiki
2012-01-01
Because diffusion-weighted imaging (DWI) can predict the prognosis of patients with oesophageal squamous cell carcinoma (ESCC), we hypothesised that apparent diffusion coefficient (ADC) values might be correlated with the collagen content and tumour angiogenesis. The purpose of this study was to determine the correlation between ADC values of ESCC before treatment and oesophageal tumour stroma and angiogenesis. Seventeen patients with ESCC were enrolled. The ADC values were calculated from the DWI score. Seventeen patients who had undergone oesophagectomy were analysed for tumour stroma, vascular endothelial growth factor (VEGF) and CD34. Tissue collagen was stained with azocarmine and aniline blue to quantitatively analyse the extracellular matrix in cancer stroma. Tissues were stained with VEGF and CD34 to analyse the angiogenesis. The ADC values decreased with stromal collagen growth. We found a negative correlation between the tumour ADC and the amount of stromal collagen (r = -0.729, P = 0.001), i.e. the ADC values decreased with growth of VEGF. We also found a negative correlation between the ADC of the tumours and the amount of VEGF (r = 0.538, P = 0.026). Our results indicated that the ADC value may be a novel prognostic factor and contribute to the treatment of oesophageal cancer. circle Magnetic resonance apparent diffusion coefficient values inversely indicate tumour stromal collagen circle There is also negative correlation between ADCs and vascular endothelial growth factor circle ADC values may contribute to the treatment of oesophageal cancer. (orig.)
Confirmation of selected milk and meat radionuclide transfer coefficients. Progress report
International Nuclear Information System (INIS)
Ward, G.M.; Johnson, J.E.
1984-01-01
The objectives are to determine transfer coefficients to milk, beef and chicken of four radionuclides for which transfer coefficients were either indetermined or based upon secondary data. The radionuclides are 99 Mo, 99 Tc, 140 Ba, and 131 Te. The transfer coefficient for 133 I to eggs was also determined, because again only limited data was available in the literature
Laminar Mixed Convection Heat Transfer Correlation for Horizontal Pipes
International Nuclear Information System (INIS)
Chae, Myeong Seon; Chung, Bum Jin
2013-01-01
This study aimed at producing experimental results and developing a new heat transfer correlation based upon a semi-empirical buoyancy coefficient. Mixed convection mass transfers inside horizontal pipe were investigated for the pipe of various length-to-diameters with varying Re. Forced convection correlation was developed using a very short cathode. With the length of cathode increase and Re decrease, the heat transfer rates were enhanced and becomes higher than that of forced convection. An empirical buoyancy coefficient was derived from correlation of natural convection and forced convection with the addition of L/D. And the heat transfer correlation for laminar mixed convection was developed using the buoyancy coefficient, it describes not only current results, but also results of other studies. Mixed convection occurs when the driving forces of both forced and natural convections are of comparable magnitude (Gr/Re 2 ∼1). It is classical problem but is still an active area of research for various thermal applications such as flat plate solar collectors, nuclear reactors and heat exchangers. The effect of buoyancy on heat transfer in a forced flow is varied by the direction of the buoyancy force. In a horizontal pipe the direction of the forced and buoyancy forces are perpendicular. The studies on the mixed convections of the horizontal pipes were not investigated very much due to the lack of practical uses compared to those of vertical pipes. Even the definitions on the buoyancy coefficient that presents the relative influence of the forced and the natural convections, are different by scholars. And the proposed heat transfer correlations do not agree
Confirmation of selected milk and meat radionuclide-transfer coefficients
International Nuclear Information System (INIS)
Ward, G.M.; Johnson, J.E.
1983-01-01
The elements selected for study of their transfer coefficients to eggs, poultry meat, milk and beef were Mo, Tc, Te, and Ba. The radionuclides used in the study were the gamma-emitting radionuclides 99 Mo, /sup 123m/Te and 133 Ba. 133 Ba was selected because 140 Ba- 140 La is produced infrequently and availability was uncertain. 133 Ba has a great advantage for our type of experiment because of its longer physical half-life. 99 Tc is a pure beta-emitter and was used in the first three animal experiments because we could not obtain the gamma-emitting /sup 95m/Tc. A supply of this nuclide was recently obtained, however, for the second cow experiment
Generalization of Clustering Coefficients to Signed Correlation Networks
Costantini, Giulio; Perugini, Marco
2014-01-01
The recent interest in network analysis applications in personality psychology and psychopathology has put forward new methodological challenges. Personality and psychopathology networks are typically based on correlation matrices and therefore include both positive and negative edge signs. However, some applications of network analysis disregard negative edges, such as computing clustering coefficients. In this contribution, we illustrate the importance of the distinction between positive and negative edges in networks based on correlation matrices. The clustering coefficient is generalized to signed correlation networks: three new indices are introduced that take edge signs into account, each derived from an existing and widely used formula. The performances of the new indices are illustrated and compared with the performances of the unsigned indices, both on a signed simulated network and on a signed network based on actual personality psychology data. The results show that the new indices are more resistant to sample variations in correlation networks and therefore have higher convergence compared with the unsigned indices both in simulated networks and with real data. PMID:24586367
Heat transfer correlations in mantle tanks
DEFF Research Database (Denmark)
Furbo, Simon; Knudsen, Søren
2005-01-01
on calculations with a CFD-model, which has earlier been validated by means of experiments. The CFD-model is used to determine the heat transfer between the solar collector fluid in the mantle and the walls surrounding the mantle in all levels of the mantle as well as the heat transfer between the wall...... transfer correlations are suitable as input for a detailed simulation model for mantle tanks. The heat transfer correlations determined in this study are somewhat different from previous reported heat transfer correlations. The reason is that this study includes more mantle tank designs and operation......Small solar domestic hot water systems are best designed as low flow systems based on vertical mantle tanks. Theoretical investigations of the heat transfer in differently designed vertical mantle tanks during different operation conditions have been carried out. The investigations are based...
Correlation of Cadmium Distribution Coefficients to Soil Characteristics
DEFF Research Database (Denmark)
Holm, Peter Engelund; Rootzen, Helle; Borggaard, Ole K.
2003-01-01
on whole soil samples have shown that pH is the main parameter controlling the distribution. To identify further the components that are important for Cd binding in soil we measured Cd distribution coefficients (K-d) at two fixed pH values and at low Cd loadings for 49 soils sampled in Denmark. The Kd...... values for Cd ranged from 5 to 3000 L kg(-1). The soils were described pedologically and characterized in detail (22 parameters) including determination of contents of the various minerals in the clay fraction. Correlating parameters were grouped and step-wise regression analysis revealed...... interlayered clay minerals [HIM], chlorite, quartz, microcline, plagioclase) were significant in explaining the Cd distribution coefficient....
The Heat Transfer Coefficient of Recycled Concrete Bricks Combination with EPS Insulation Board Wall
Directory of Open Access Journals (Sweden)
Jianhua Li
2015-01-01
Full Text Available Four tectonic forms samples were conducted to test their heat transfer coefficients. By analyzing and comparing the test values and theoretical values of the heat transfer coefficient, a corrected-value calculation method for determining the heat transfer coefficient was proposed; the proposed method was proved to be reasonably correct. The results indicated that the recycled concrete brick wall heat transfer coefficient is higher than that of the clay brick wall, the heat transfer coefficient of recycled concrete brick wall could be effectively reduced when combined with the EPS insulation board, and the sandwich insulation type was better than that of external thermal insulation type.
Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan
2013-09-01
In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Marčenko-Pastur distribution.
A short note on jackknifing the concordance correlation coefficient.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2014-02-10
Lin's concordance correlation coefficient (CCC) is a very popular scaled index of agreement used in applied statistics. To obtain a confidence interval (CI) for the estimate of CCC, jackknifing was proposed and shown to perform well in simulation as well as in applications. However, a theoretical proof of the validity of the jackknife CI for the CCC has not been presented yet. In this note, we establish a sufficient condition for using the jackknife method to construct the CI for the CCC. Copyright © 2013 John Wiley & Sons, Ltd.
Heat transfer coefficient in pool boiling for an electrically heated tube at various inclinations
International Nuclear Information System (INIS)
Fahmy, A.S.A.; Mariy, A.H.; Mahmoud, S.I.; Ibrahim, N.A.
1987-01-01
An experimental investigation is carried out study the behaviour of heat transfer in pool boiling from a vertical and inclined heated tube at atmospheric pressure. An imperial correlation joining the different parameters affecting the heat transfer coefficient in pool boiling for an electrically heated tube at various inclinations is developed. Two test sections (zircaloy-4 and stainless steel) of 16 n n outer diameter and 120 nm length are investigated. Four levels of heat flux are used for heating the two lest sections (e.g. 381, 518, 721 and 929 k.watt/n 2). The maximum surface temperature achieved is 146.5 degree c for both materials, and the maximum bulk temperature is 95 degree C. It is found that the average heat transfer coefficient is inversely proportional with heated length l, where it reaches a constant value in the horizontal position. The heat transfer coefficient curves at various inclinations with respect to the heated tube length pass around one point which is defined as limit length
Overcoming multicollinearity in multiple regression using correlation coefficient
Zainodin, H. J.; Yap, S. J.
2013-09-01
Multicollinearity happens when there are high correlations among independent variables. In this case, it would be difficult to distinguish between the contributions of these independent variables to that of the dependent variable as they may compete to explain much of the similar variance. Besides, the problem of multicollinearity also violates the assumption of multiple regression: that there is no collinearity among the possible independent variables. Thus, an alternative approach is introduced in overcoming the multicollinearity problem in achieving a well represented model eventually. This approach is accomplished by removing the multicollinearity source variables on the basis of the correlation coefficient values based on full correlation matrix. Using the full correlation matrix can facilitate the implementation of Excel function in removing the multicollinearity source variables. It is found that this procedure is easier and time-saving especially when dealing with greater number of independent variables in a model and a large number of all possible models. Hence, in this paper detailed insight of the procedure is shown, compared and implemented.
Experimentally Determined Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments
Bue, Grant; Watts, Carly; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vonau, Walt; Vogel, Matt; Conger, Bruce
2015-01-01
A Human-In-The-Loop (HITL) Portable Life Support System 2.0 (PLSS 2.0) test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014 to December 19, 2014. These closed-loop tests of the PLSS 2.0 system integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure but effluent water vapor from the Spacesuit Water Membrane Evaporator (SWME) and the Auxiliary Membrane Evaporator (Mini-ME), and effluent carbon dioxide from the Rapid Cycle Amine (RCA) were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the heat transfer coefficient (UA) of the Liquid Cooling Garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flowrate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit (EMU) LCG, the Oceaneering Space Systems (OSS) LCG, and the OSS auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.
Correlation transfer from basal ganglia to thalamus in Parkinson's disease
Pamela, Reitsma; Brent, Doiron; Jonathan, Rubin
2011-01-01
Spike trains from neurons in the basal ganglia of parkinsonian primates show increased pairwise correlations, oscillatory activity, and burst rate compared to those from neurons recorded during normal brain activity. However, it is not known how these changes affect the behavior of downstream thalamic neurons. To understand how patterns of basal ganglia population activity may affect thalamic spike statistics, we study pairs of model thalamocortical (TC) relay neurons receiving correlated inhibitory input from the internal segment of the globus pallidus (GPi), a primary output nucleus of the basal ganglia. We observe that the strength of correlations of TC neuron spike trains increases with the GPi correlation level, and bursty firing patterns such as those seen in the parkinsonian GPi allow for stronger transfer of correlations than do firing patterns found under normal conditions. We also show that the T-current in the TC neurons does not significantly affect correlation transfer, despite its pronounced effects on spiking. Oscillatory firing patterns in GPi are shown to affect the timescale at which correlations are best transferred through the system. To explain this last result, we analytically compute the spike count correlation coefficient for oscillatory cases in a reduced point process model. Our analysis indicates that the dependence of the timescale of correlation transfer is robust to different levels of input spike and rate correlations and arises due to differences in instantaneous spike correlations, even when the long timescale rhythmic modulations of neurons are identical. Overall, these results show that parkinsonian firing patterns in GPi do affect the transfer of correlations to the thalamus. PMID:22355287
Energy Technology Data Exchange (ETDEWEB)
Beresford, N.A. [Centre for Ecology and Hydrology, CEH-Lancaster, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)], E-mail: nab@ceh.ac.uk; Mayes, R.W. [Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Barnett, C.L.; Howard, B.J. [Centre for Ecology and Hydrology, CEH-Lancaster, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)
2007-11-15
A study to measure the transfer of radiocaesium to adult female sheep through a breeding cycle is described. The transfer of radiocaesium from the diet to muscle (estimated as the equilibrium transfer coefficient) was significantly lower to pregnant, and especially lactating, animals compared to non-lactating and barren animals. High dry matter intake rates were also associated with significantly lower transfer coefficients. Known relationships between dry matter intake rates and protein turnover could credibly explain some of these differences. However, when described as the concentration ratio, radiocaesium transfer to meat was apparently highest during lactation. The apparent difference in results obtained by the two approaches of determining transfer is the consequence of daily dry matter intake being a denominator within the estimation of transfer coefficient. A wider discussion of transfer coefficients and concentration ratios leads us to suggest that the concentration ratio is the more robust and potentially generic parameter.
International Nuclear Information System (INIS)
Beresford, N.A.; Mayes, R.W.; Barnett, C.L.; Howard, B.J.
2007-01-01
A study to measure the transfer of radiocaesium to adult female sheep through a breeding cycle is described. The transfer of radiocaesium from the diet to muscle (estimated as the equilibrium transfer coefficient) was significantly lower to pregnant, and especially lactating, animals compared to non-lactating and barren animals. High dry matter intake rates were also associated with significantly lower transfer coefficients. Known relationships between dry matter intake rates and protein turnover could credibly explain some of these differences. However, when described as the concentration ratio, radiocaesium transfer to meat was apparently highest during lactation. The apparent difference in results obtained by the two approaches of determining transfer is the consequence of daily dry matter intake being a denominator within the estimation of transfer coefficient. A wider discussion of transfer coefficients and concentration ratios leads us to suggest that the concentration ratio is the more robust and potentially generic parameter
A robust bayesian estimate of the concordance correlation coefficient.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2015-01-01
A need for assessment of agreement arises in many situations including statistical biomarker qualification or assay or method validation. Concordance correlation coefficient (CCC) is one of the most popular scaled indices reported in evaluation of agreement. Robust methods for CCC estimation currently present an important statistical challenge. Here, we propose a novel Bayesian method of robust estimation of CCC based on multivariate Student's t-distribution and compare it with its alternatives. Furthermore, we extend the method to practically relevant settings, enabling incorporation of confounding covariates and replications. The superiority of the new approach is demonstrated using simulation as well as real datasets from biomarker application in electroencephalography (EEG). This biomarker is relevant in neuroscience for development of treatments for insomnia.
Fuel-to-cladding heat transfer coefficient into reactor fuel element
International Nuclear Information System (INIS)
Lassmann, K.
1979-01-01
Models describing the fuel-to-cladding heat transfer coefficient in a reactor fuel element are reviewed critically. A new model is developed with contributions from solid, fluid and radiation heat transfer components. It provides a consistent description of the transition from an open gap to the contact case. Model parameters are easily available and highly independent of different combinations of material surfaces. There are no restrictions for fast transients. The model parameters are fitted to 388 data points under reactor conditions. For model verification another 274 data points of steel-steel and aluminium-aluminium interfaces, respectively, were used. The fluid component takes into account peak-to-peak surface roughnesses and, approximatively, also the wavelengths of surface roughnesses. For minor surface roughnesses normally prevailing in reactor fuel elements the model asymptotically yields Ross' and Stoute's model for the open gap, which is thus confirmed. Experimental contact data can be interpreted in very different ways. The new model differs greatly from Ross' and Stoute's contact term and results in better correlation coefficients. The numerical algorithm provides an adequate representation for calculating the fuel-to-cladding heat transfer coefficient in large fuel element structural analysis computer systems. (orig.) [de
International Nuclear Information System (INIS)
Baburajan, P.K.; Bisht, G.S.; Gupta, S.K.; Prabhu, S.V.
2013-01-01
Highlights: ► Measured subcooled boiling pressure drop and local heat transfer coefficient in horizontal tubes. ► Infra-red thermal imaging is used for wall temperature measurement. ► Developed correlations for pressure drop and local heat transfer coefficient. -- Abstract: Horizontal flow is commonly encountered in boiler tubes, refrigerating equipments and nuclear reactor fuel channels of pressurized heavy water reactors (PHWR). Study of horizontal flow under low pressure and low flow (LPLF) conditions is important in understanding the nuclear core behavior during situations like LOCA (loss of coolant accidents). In the present work, local heat transfer coefficient and pressure drop are measured in a horizontal tube under LPLF conditions of subcooled boiling. Geometrical parameters covered in this study are diameter (5.5 mm, 7.5 mm and 9.5 mm) and length (550 mm, 750 mm and 1000 mm). The operating parameters varied are mass flux (450–935 kg/m 2 s) and inlet subcooling (29 °C, 50 °C and 70 °C). Infra-red thermography is used for the measurement of local wall temperature to estimate the heat transfer coefficient in single phase and two phase flows with water as the working medium at atmospheric pressure. Correlation for single phase diabatic pressure drop ratio (diabatic to adiabatic) as a function of viscosity ratio (wall temperature to fluid temperature) is presented. Correlation for pressure drop under subcooled boiling conditions as a function of Boiling number (Bo) and Jakob number (Ja) is obtained. Correlation for single phase heat transfer coefficient in the thermal developing region is presented as a function of Reynolds number (Re), Prandtl number (Pr) and z/d (ratio of axial length of the test section to diameter). Correlation for two phase heat transfer coefficient under subcooled boiling condition is developed as a function of boiling number (Bo), Jakob number (Ja) and Prandtl number (Pr)
Study on transfer coefficients of 90Sr, 137Cs, natural U, 226Ra and 239Pu in terrestrial food chains
International Nuclear Information System (INIS)
Qin Suyun; Qi Yong; Li Shuqin; Zhou Caiyun; Zhang Jingjuan; Li Jikai; Li Xuequn
1995-01-01
The aim of study was to provide values of transfer parameter of 90 Sr, 137 Cs, Natural U, 226 Ra and 239 Pu in terrestrial food chains, more applicable for Chinese socio-natural conditions. Data of radionuclides contents in agricultural crops and in associated soils, in sheep tissues and in associated grasses were collected in couples. The transfer coefficients in terrestrial food chains (soil-crops, grasses-sheep tissues) were calculated. On basis of statistical analysis, the representative values and 95% ranges of transfer coefficient for 5 radionuclides in 7 kind of agricultural products for southern moist areas and north dry areas were given. Regression analysis showed that relation between the transfer coefficients and the radionuclide contents in their associated soils present a negative correlation, it could be described with a equation: Y = aX -b
Shahzad, Muhammad Wakil; Burhan, Muhammad; Ng, Kim Choon
2018-01-01
In falling film evaporators, the overall heat transfer coefficient is controlled by film thickness, velocity, liquid properties and the temperature differential across the film layer. This chapter presents the heat transfer behaviour for evaporative
Feng, Dai; Svetnik, Vladimir; Coimbra, Alexandre; Baumgartner, Richard
2014-01-01
The intraclass correlation coefficient (ICC) with fixed raters or, equivalently, the concordance correlation coefficient (CCC) for continuous outcomes is a widely accepted aggregate index of agreement in settings with small number of raters. Quantifying the precision of the CCC by constructing its confidence interval (CI) is important in early drug development applications, in particular in qualification of biomarker platforms. In recent years, there have been several new methods proposed for construction of CIs for the CCC, but their comprehensive comparison has not been attempted. The methods consisted of the delta method and jackknifing with and without Fisher's Z-transformation, respectively, and Bayesian methods with vague priors. In this study, we carried out a simulation study, with data simulated from multivariate normal as well as heavier tailed distribution (t-distribution with 5 degrees of freedom), to compare the state-of-the-art methods for assigning CI to the CCC. When the data are normally distributed, the jackknifing with Fisher's Z-transformation (JZ) tended to provide superior coverage and the difference between it and the closest competitor, the Bayesian method with the Jeffreys prior was in general minimal. For the nonnormal data, the jackknife methods, especially the JZ method, provided the coverage probabilities closest to the nominal in contrast to the others which yielded overly liberal coverage. Approaches based upon the delta method and Bayesian method with conjugate prior generally provided slightly narrower intervals and larger lower bounds than others, though this was offset by their poor coverage. Finally, we illustrated the utility of the CIs for the CCC in an example of a wake after sleep onset (WASO) biomarker, which is frequently used in clinical sleep studies of drugs for treatment of insomnia.
Estimation of grass to cow's milk transfer coefficients for emergency situations
International Nuclear Information System (INIS)
Ujwal, P.; Karunakara, N.; Yashodhara, I.; Rao, Chetan; Kumara, Sudeep; Dileep, B.N.; Ravi, P.M.
2012-01-01
Several studies have been reported on soil to grass equilibrium transfer factors and grass to cow's milk transfer coefficients for 137 Cs for the environs of different nuclear power plants of both India and other parts of the world. In such studies, the activity concentration of 137 Cs is measured in grass collected from different places. Cow's milk samples are collected from nearby localities or from milk dairies and analyzed for 137 Cs and the grass to cow's milk transfer coefficient is estimated. In situation where 137 Cs is not present in measurable activity concentrations, its stable counterpart (Cs) is measured for the estimation of transfer coefficients. These transfer coefficient values are generally used in theoretical models to estimate the dose to the population for hypothetical situation of emergency. It should be noted that the transfer coefficients obtained for equilibrium conditions may not be totally applicable for emergency situation. However, studies aimed at evaluating transfer coefficients for emergency situations are sparse because nuclear power plants do not release 137 Cs during normal operating situations and therefore simulating situation of emergency release is not possible. Hence, the only method to estimate the grass to milk transfer coefficient for emergency situation is to spike the grass with small quantity of stable Cs. This paper reports the results of grass to milk transfer coefficients for stable isotope of Cesium (Cs) for emergency situation
International Nuclear Information System (INIS)
Banerjee, S.; Hassan, Y.A.
1995-01-01
Condensation in the presence of noncondensible gases plays an important role in the nuclear industry. The RELAP5/MOD3 thermal hydraulic code was used to study the ability of the code to predict this phenomenon. Two separate effects experiments were simulated using this code. These were the Massachusetts Institute of Technology's (MIT) Pressurizer Experiment, the MIT Single Tube Experiment. A new iterative approach to calculate the interface temperature and the degraded heat transfer coefficient was developed and implemented in the RELAP5/MOD3 thermal hydraulic code. This model employs the heat transfer simultaneously. This model was found to perform much better than the reduction factor approach. The calculations using the new model were found to be in much better agreement with the experimental values
Energy Technology Data Exchange (ETDEWEB)
Banerjee, S.; Hassan, Y.A. [Texas A& M Univ., College Station, TX (United States)
1995-09-01
Condensation in the presence of noncondensible gases plays an important role in the nuclear industry. The RELAP5/MOD3 thermal hydraulic code was used to study the ability of the code to predict this phenomenon. Two separate effects experiments were simulated using this code. These were the Massachusetts Institute of Technology`s (MIT) Pressurizer Experiment, the MIT Single Tube Experiment. A new iterative approach to calculate the interface temperature and the degraded heat transfer coefficient was developed and implemented in the RELAP5/MOD3 thermal hydraulic code. This model employs the heat transfer simultaneously. This model was found to perform much better than the reduction factor approach. The calculations using the new model were found to be in much better agreement with the experimental values.
Determination of the gas-to-membrane mass transfer coefficient in a catalytic membrane reactor
Veldsink, J.W.; Versteeg, G.F.; Swaaij, W.P.M. van
1995-01-01
A novel method to determine the external mass transfer coefficient in catalytic membrane reactors (Sloot et al., 1992a, b) was presented in this study. In a catalytically active membrane reactor, in which a very fast reaction occurs, the external transfer coefficient can conveniently be measured by
Semi-empirical model for heat transfer coefficient in liquid metal turbulent flow
International Nuclear Information System (INIS)
Fernandez y Fernandez, E.; Carajilescov, P.
1982-01-01
The heat transfer by forced convection in a metal liquid turbulent flow for circular ducts is analyzed. An analogy between the momentum and heat in the wall surface, is determined, aiming to determine an expression for heat transfer coefficient in function of the friction coefficient. (E.G.) [pt
Impact of External Pressure on the Heat Transfer Coefficient during Solidification of Al-A356 Alloy
DEFF Research Database (Denmark)
Jabbari, Masoud; Ilkhchy, A.Fardi; Moumani, E.
In this paper the interfacial heat transfer coefficient (IHTC) is correlated to applied external pressure, in which IHTC at the interface between A356 aluminum alloy and metallic mold during the solidification of the casting under different pressures were obtained using the Inverse Heat Conduction...... Problem (IHCP) method. The method covers the expedient of comparing theoretical and experimental thermal histories. Temperature profiles obtained from thermocouples were used in a finite difference heat flow program to estimate the transient heat transfer coefficients. The new simple formula was presented...
International Nuclear Information System (INIS)
Souza Dutra, A. de.
1985-01-01
An experimental study on forced convection in a four-cusp duct simulating a typical nuclear reactor channel degraded by accident is presented. Transfer coefficients were obtained by using the analogy between heat and mass tranfer, with the naphtalene sublimation technique. The experiment consisted in forcing air past a four-cusp naphthalene moulded duct. Mass transfer coefficients were determined in nondimensional form as Sherwood number. Experimental curves correlating the Sherwood number with a nondimensional length, x + , were obtained for Reynolds number varying from 891 to 30.374. This range covers typical flow rates that are expected to exist in a degraded nuclear reactor core. (Author) [pt
Energy Technology Data Exchange (ETDEWEB)
Goemans, M.G.E.; Gloyna, E.F. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering; Buelow, S.J. [Los Alamos National Lab., NM (United States)
1996-04-01
Molecular diffusion coefficients of lithium-, sodium-, potassium-, cesium-, calcium-, and strontium nitrate in subcritical water were determined by analysis of Taylor dispersion profiles. Pressures ranged from 300 to 500 bar at temperatures ranging from 25{degrees}C to 300{degrees}C. The reported diffusion values were determined at infinite dilution. Molecular diffusion coefficients were 10 to 20 times faster in near-critical subcritical water than in water at ambient temperature and pressure (ATP). These findings implied that the diffusion rates were more liquid like than they were gas like, hence experimental results were correlated with diffusion models for liquids. The subcritical diffusion data presented in this work, and supercritical diffusion results published elsewhere were correlated with hydrodynamic diffusion equations. Both the Wilke-Chang correlation and the Stokes-Einstein equation yielded predictions within 10% of the experimental results if the structure of the diffusing species could be estimated. The effect of the increased diffusion rates on mass transfer rates in supercritical water oxidation applications was quantified, with emphasis on heterogeneous oxidation processes. This study and results published elsewhere showed that diffusion limited conditions are much more likely to be encountered in SCWO processes than commonly acknowledged.
Reassessment of forced convection heat transfer correlations for refrigerant-12
International Nuclear Information System (INIS)
Celata, G.P.; Cuomo, M.; D'Annibale, F.; Farello, G.E.; Setaro, T.
1986-01-01
In the frame of a Refrigerant-12 experiment on postulated accidental transients in Pressurized Water Reactors under way at Heat Transfer Laboratory (ENEA Casaccia Research Center), an assessment of the main correlation available in scientific literature, for the different heat transfer regions encountered when a liquid is boiled in a confined heated channel, has been performed. Considering a vertical tube uniformly heated over its length with CHF at the exit, the following heat transfer regimes may be individuated: convective heat transfer to liquid, subcooled boiling, saturated nucleate boiling, forced convective heat transfer through liquid film (annular flow regime) and thermal crisis. From the comparison of computed values with an original ENEA dataset, the best correlations in predicting Refrigerant-12 data have been individuated. In a few cases, though preserving the original structure of the correlations, mainly developed for water, it was necessary to adjust some coefficients by means of best-fit procedures through our experimental data. The work has been performed in the frame of the ENEA Thermal Reactor Department Safety Research Project
International Nuclear Information System (INIS)
Seong-Jin Kim; Goon-Cherl Park
2005-01-01
Full text of publication follows: Models or correlations for phase interface are needed to analyze the multi-phase flow. Interfacial heat transfer coefficients are important to constitute energy equation of multi-phase flow, specially. In subcooled boiling flow, bubble condensation at the bubble-liquid interface is a major mechanism of heat transfer within bulk subcooled liquid. Bubble collapse rates and temperatures of each phase are needed to determine the interfacial heat transfer coefficient for bubble condensation. Bubble collapse rates were calculated through image processing in single direction, generally. And in case of liquid bulk temperature, which has been obtained by general temperature sensor such as thermocouple, was used. However, multi-directional images are needed to analyze images due to limitations of single directional image processing. Also, temperature sensor, which has a fast response time, must be used to obtain more accurate interfacial heat transfer coefficient. Low pressure subcooled water flow experiments using micro-thermocouple and double directional image processing with mirrors were conducted to investigate bubble condensation phenomena and to modify interfacial heat transfer correlation. Experiments were performed in a vertical subcooled boiling flow of a rectangular channel. Bubble condensing traces with respect to time were recorded by high speed camera in double direction and bubble collapse rates were calculated by processing recorded digital images. Temperatures were measured by micro-thermocouple, which is a K-type with a 12.7 μm diameter. The liquid temperature was estimated by the developed algorithm to discriminate phases and find each phase temperature in the measured temperature including both liquid and bubble temperature. The interfacial heat transfer coefficient for bubble condensation was calculated from the bubble collapse rates and the estimated liquid temperature, and its correlation was modified. The modified
Directory of Open Access Journals (Sweden)
Cieśliński Janusz T.
2016-09-01
Full Text Available This study is focused on experimental investigation of selected type of brazed plate heat exchanger (PHEx. The Wilson plot approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The results obtained revealed that Hausen and Dittus-Boelter correlations underestimated heat transfer coefficient for the tested PHEx by an order of magnitude. The Aspen Plate code overestimated heat transfer coefficient by about 50%, while Muley-Manglik correlation overestimated it from 1% to 25%, dependent on the value of Reynolds number and hot or cold liquid side.
Whitesides, R. Harold; Majumdar, Alok K.; Jenkins, Susan L.; Bacchus, David L.
1990-01-01
A series of cold flow heat transfer tests was conducted with a 7.5-percent scale model of the Space Shuttle Rocket Motor (SRM) to measure the heat transfer coefficients in the separated flow region around the nose of the submerged nozzle. Modifications were made to an existing 7.5 percent scale model of the internal geometry of the aft end of the SRM, including the gimballed nozzle in order to accomplish the measurements. The model nozzle nose was fitted with a stainless steel shell with numerous thermocouples welded to the backside of the thin wall. A transient 'thin skin' experimental technique was used to measure the local heat transfer coefficients. The effects of Reynolds number, nozzle gimbal angle, and model location were correlated with a Stanton number versus Reynolds number correlation which may be used to determine the convective heating rates for the full scale Space Shuttle Solid Rocket Motor nozzle.
Heat-transfer correlations for natural convection boiling
International Nuclear Information System (INIS)
Stephan, K.; Abdelsalam, M.
1980-01-01
To-date there exists no comprehensive theory allowing the prediction of heat-transfer coefficients in natural convection boiling, in spite of the many efforts made in this field. In order to establish correlations with wide application, the methods of regression analysis were applied to the nearly 500 existing experimental data points for natural convection boiling heat transfer. As demonstrated by the analysis, these data can best be represented by subdividing the substances into four groups (water, hydrocarbons, cryogenic fluids and refrigerants) and employing a different set of dimensionless numbers for each group of substances, because certain dimensionless numbers important for one group of substances are unimportant to another. One equation valid for all substances could be built up, but its accuracy would be less than that obtained for the individual correlations without adding undesirable complexity. (author)
Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor
Energy Technology Data Exchange (ETDEWEB)
Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno [University of Zagreb, Zagreb (Croatia)
2015-06-15
Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R{sup 2}=0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k{sub L}a=4,652-1,9807 h{sup -1}.
Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor
International Nuclear Information System (INIS)
Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno
2015-01-01
Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R 2 =0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k L a=4,652-1,9807 h -1
Shahzad, Muhammad Wakil
2018-03-07
In falling film evaporators, the overall heat transfer coefficient is controlled by film thickness, velocity, liquid properties and the temperature differential across the film layer. This chapter presents the heat transfer behaviour for evaporative film boiling on horizontal tubes, but working at low pressures of 0.93–3.60 kPa as well as seawater salinity of 15,000–90,000 mg/l or ppm. Owing to a dearth of literature on film-boiling at these conditions, the chapter is motivated by the importance of evaporative film-boiling in the process industries. It is observed that in addition to the above-mentioned parameters, evaporative heat transfer of seawater is affected by the emergence of micro-bubbles within the thin film layer, particularly when the liquid saturation temperatures drop below 25°C (3.1 kPa). Such micro-bubbles are generated near to the tube wall surfaces, and they enhanced the heat transfer by two or more folds when compared with the predictions of conventional evaporative film-boiling. The appearance of micro-bubbles is attributed to the rapid increase in the specific volume of vapour, i.e. dv/dT, at low saturation temperature conditions. A new correlation is thus proposed in this chapter and it shows good agreement to the measured data with an experimental uncertainty less than ±8%.
Ahmed, Syed Muzamil; Kazi, S. N.; Khan, Ghulamullah; Sadri, Rad; Dahari, Mahidzal; Zubir, M. N. M.; Sayuti, M.; Ahmad, Pervaiz; Ibrahim, Rushdan
2018-03-01
Heat transfer coefficients were obtained for a range of non-wood kenaf bast pulp fiber suspensions flowing through a circular pipe heat exchanger test loop. The data were produced over a selected temperature and range of flow rates from the flow loop. It was found that the magnitude of the heat transfer coefficient of a fiber suspension is dependent on characteristics, concentration and pulping method of fiber. It was observed that at low concentration and high flow rates, the heat transfer coefficient values of suspensions were observed higher than that of the heat transfer coefficient values of water, on the other hand the heat transfer coefficient values of suspensions decreases at low flow rates and with the increase of their concentration. The heat transfer were affected by varying fiber characteristics, such as fiber length, fiber flexibility, fiber chemical and mechanical treatment as well as different pulping methods used to liberate the fibers. Heat transfer coefficient was decreased with the increase of fiber flexibility which was also observed by previous researchers. In the present work, the characteristics of fibers are correlated with the heat transfer coefficient of suspensions of the fibers. Deviations in fiber properties can be monitored from the flowing fiber suspensions by measuring heat transfer coefficient to adjust the degree of fiber refining treatment so that papers made from those fibers will be more uniform, consistent, within the product specification and retard the paper production loss.
International Nuclear Information System (INIS)
Iguchi, Tadashi; Anoda, Yoshinari
2002-02-01
Authors performed post-CHF experiments under wider pressure ranges of 2 MPa - 18 MPa, wider mass flux ranges of 33 kg/m 2 s - 1651 kg/m 2 s and wider superheat of heaters up to 500 K in comparison to experimental ranges at previous post-CHF experiments. Data on boiling transition, critical heat flux and post-CHF heat transfer coefficient were obtained. Used test section was 4x4-rod bundle with heaters, which diameter and length were the same as those of BWR nuclear fuels. As the result of the experiments, it was found that the boiling transition occurred just below several grid spacers, and that the fronts of the boiling transition region proceeded lower with increase of heated power. Heat transfer was due to nucleate boiling above grid spacers, while it was due to film boiling below grid spacers. Consequently, critical heat flux is affected on the distance from the grid spacers. Critical heat flux above the grid spacers was about 15% higher than that below the grid spacers, by comparing them under the same local condition. Heat transfer by steam turbulent flow was dominant to post-CHF heat transfer, when superheat of heaters was sufficiently high. Then, post-CHF heat transfer coefficient was predicted with heat transfer correlations for single-phase flow. On the other hand, when superhead of heaters was not sufficiently high, post-CHF heat transfer coefficient was higher than the prediction with heat transfer correlations for single-phase flow. Mass flux effect on post-CHF heat transfer coefficient was described by standardization of post-CHF heat transfer coefficient with the prediction for single-phase flow. However, pressure effect, superheat effect and effect of position were not described. Authors clarified that those effects could be described with functions of heater temperature and position. Post-CHF heat transfer coefficient was lowest just blow the grid spacers, and it increased with the lower positions. It increased by about 30% in one span of the grid
Energy Technology Data Exchange (ETDEWEB)
Iguchi, Tadashi; Anoda, Yoshinari [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Iwaki, Chikako [Toshiba Corp., Tokyo (Japan)
2002-02-01
Authors performed post-CHF experiments under wider pressure ranges of 2 MPa - 18 MPa, wider mass flux ranges of 33 kg/m{sup 2}s - 1651 kg/m{sup 2}s and wider superheat of heaters up to 500 K in comparison to experimental ranges at previous post-CHF experiments. Data on boiling transition, critical heat flux and post-CHF heat transfer coefficient were obtained. Used test section was 4x4-rod bundle with heaters, which diameter and length were the same as those of BWR nuclear fuels. As the result of the experiments, it was found that the boiling transition occurred just below several grid spacers, and that the fronts of the boiling transition region proceeded lower with increase of heated power. Heat transfer was due to nucleate boiling above grid spacers, while it was due to film boiling below grid spacers. Consequently, critical heat flux is affected on the distance from the grid spacers. Critical heat flux above the grid spacers was about 15% higher than that below the grid spacers, by comparing them under the same local condition. Heat transfer by steam turbulent flow was dominant to post-CHF heat transfer, when superheat of heaters was sufficiently high. Then, post-CHF heat transfer coefficient was predicted with heat transfer correlations for single-phase flow. On the other hand, when superhead of heaters was not sufficiently high, post-CHF heat transfer coefficient was higher than the prediction with heat transfer correlations for single-phase flow. Mass flux effect on post-CHF heat transfer coefficient was described by standardization of post-CHF heat transfer coefficient with the prediction for single-phase flow. However, pressure effect, superheat effect and effect of position were not described. Authors clarified that those effects could be described with functions of heater temperature and position. Post-CHF heat transfer coefficient was lowest just blow the grid spacers, and it increased with the lower positions. It increased by about 30% in one span of
Comparison of correlations for heat transfer in sphere-pac beds
International Nuclear Information System (INIS)
Fundamenski, W.R.; Gierszewski, P.J.
1991-08-01
The design of a tritium breeding blanket for a fusion reactor requires the knowledge of heat transfer within the blanket. In this paper three models for effective bed heat transfer are compared against the experimental database in order to choose a reference correlation to be used in blanket design. Two parameters are used to describe heat transfer in a packed bed: effective thermal conductivity of the bed, and a heat transfer coefficient at the bed-solid interface
Lee, Jung Gil
2017-11-03
In order to improve water production of membrane distillation (MD), the development of high performance membrane having better mass transfer and enhancement of convection heat transfer in MD module have been continuously investigated. This paper presents the relationship between the heat and mass transfer resistance across the membrane and the performance improvement. Various ranges of mass transfer coefficient (MTC) from normal (0.3×10−6 to 2.1×10−6kg/m2sPa: currently available membranes) to high (>2.1×10−6kg/m2sPa: membranes under development) were simulated using an experimentally validated model at different ranges of convection heat transfer by varying the inlet flow rates and spacer enhancement factor. The effect of mass transfer and convection heat transfer on the MD performance parameters including temperature polarization coefficient (TPC), mean permeate flux, and specific energy consumption were investigated in a direct contact MD (DCMD) configuration. Results showed that improving the MTC at the low ranges is more important than that at the high ranges where the heat transfer resistance becomes dominant and hence the convection heat transfer coefficient must be increased. Therefore, an effort on designing MD modules using feed and permeate spacers and controlling the membrane surface roughness to increase the convection heat transfer and TPC in the channel aiming to enhance the flux is required because the currently developed mass transfer has almost reached the critical point.
Experimental evaluation of heat transfer coefficients between radiant ceiling and room
DEFF Research Database (Denmark)
Causone, Francesco; Corgnati, Stefano P.; Filippi, Marco
2009-01-01
The heat transfer coefficients between radiant surfaces and room are influenced by several parameters: surfaces temperature distributions, internal gains, air movements. The aim of this paper is to evaluate the heat transfer coefficients between radiant ceiling and room in typical conditions...... of occupancy of an office or residential building. Internal gains were therefore simulated using heated cylinders and heat losses using cooled surfaces. Evaluations were developed by means of experimental tests in an environmental chamber. Heat transfer coefficient may be expressed separately for radiation...
Ma, Wanling; Li, Na; Zhao, Weiwei; Ren, Jing; Wei, Mengqi; Yang, Yong; Wang, Yingmei; Fu, Xin; Zhang, Zhuoli; Larson, Andrew C; Huan, Yi
2016-01-01
To clarify diffusion and perfusion abnormalities and evaluate correlation between apparent diffusion coefficient (ADC), MR perfusion and histopathologic parameters of pancreatic cancer (PC). Eighteen patients with PC underwent diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Parameters of DCE-MRI and ADC of cancer and non-cancerous tissue were compared. Correlation between the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space (K, volume of the extravascular extracellular space per unit volume of tissue (Ve), and ADC of PC and histopathologic parameters were analyzed. The rate constant that represents transfer of contrast agent from the extravascular extracellular space into blood plasma, K, tissue volume fraction occupied by vascular space, and ADC of PC were significantly lower than nontumoral pancreases. Ve of PC was significantly higher than that of nontumoral pancreas. Apparent diffusion coefficient and K values of PC were negatively correlated to fibrosis content and fibroblast activation protein staining score. Fibrosis content was positively correlated to Ve. Apparent diffusion coefficient values and parameters of DCE-MRI can differentiate PC from nontumoral pancreases. There are correlations between ADC, K, Ve, and fibrosis content of PC. Fibroblast activation protein staining score of PC is negatively correlated to ADC and K. Apparent diffusion coefficient, K, and Ve may be feasible to predict prognosis of PC.
Determining convective heat transfer coefficient using phoenics software package
Energy Technology Data Exchange (ETDEWEB)
Kostikov, A; Matsevity, Y [Institute of Mechanical Engineering Problems of National Academy of Sciences of Ukraine, Kharkov (Ukraine)
1998-12-31
The two methods of determination of such important quantity of heat exchange on a body surface using PHOENICS are suggested in the presentation. The first method consists in a post-processing of results of conjugate heat transfer problem solved by PHOENICS. The second one is solving an inverse heat conduction problem for solid body using PHOENICS. Comparative characteristic of these two methods is represented. (author) 4 refs.
Determining convective heat transfer coefficient using phoenics software package
Energy Technology Data Exchange (ETDEWEB)
Kostikov, A.; Matsevity, Y. [Institute of Mechanical Engineering Problems of National Academy of Sciences of Ukraine, Kharkov (Ukraine)
1997-12-31
The two methods of determination of such important quantity of heat exchange on a body surface using PHOENICS are suggested in the presentation. The first method consists in a post-processing of results of conjugate heat transfer problem solved by PHOENICS. The second one is solving an inverse heat conduction problem for solid body using PHOENICS. Comparative characteristic of these two methods is represented. (author) 4 refs.
International Nuclear Information System (INIS)
Jeong, Gi Ho; Song, Ki Bum; Kim, Kui Soon
2001-01-01
This paper deals with the development of a new method that can obtain heat transfer coefficient and reference free stream temperature simultaneously. The method is based on transient heat transfer experiments using two narrow-band TLCs. The method is validated through error analysis in terms of the random uncertainties in the measured temperatures. It is shown how the uncertainties in heat transfer coefficient and free stream temperature can be reduced. The general method described in this paper is applicable to many heat transfer models with unknown free stream temperature
Directory of Open Access Journals (Sweden)
Mikielewicz Dariusz
2016-06-01
Full Text Available In the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of carbon dioxide. The experimental data from various researches were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house model. The results show the importance of taking into account the surface tension as the parameter exhibiting its importance in case of the flow in minichannels as well as the influence of reduced pressure. The calculations were accomplished to test the sensitivity of the heat transfer model with respect to selection of the appropriate two-phase flow multiplier, which is one of the elements of the heat transfer model. For that purpose correlations due to Müller-Steinhagen and Heck as well as the one due to Friedel were considered. Obtained results show a good consistency with experimental results, however the selection of two-phase flow multiplier does not significantly influence the consistency of calculations.
International Nuclear Information System (INIS)
Kim, Kap; Kim, Hho Jung
1986-01-01
Some studies on direct-contact condensation in cocurrent stratified flow of steam and subcooled water were reviewed. Several approaches have been performed to develop the condensation heat transfer coefficient relationship. The local Nusselt number is correlated in terms of the local water Reynolds and Prandtl numbers as well as the steam Froude number. In addition, a turbulence-centered model, developed principally for gas absorption in several geometries, is modified by using calculated interfacial parameters for the turbulent velocity and length scales. These approaches result in a fairly good agreement with the data, whereas, the turbulence-centered model is here recommended since it is based on the turbulent properties which may be closely related to the condensation phenomena. (Author)
International Nuclear Information System (INIS)
Blacker, P.T.; McLain, D.R.
1962-04-01
The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm 2 . This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable
Energy Technology Data Exchange (ETDEWEB)
Blacker, P T; McLain, D R [Reactor Development Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)
1962-04-15
The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm{sup 2}. This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable.
Estimating the workpiece-backingplate heat transfer coefficient in friction stirwelding
DEFF Research Database (Denmark)
Larsen, Anders; Stolpe, Mathias; Hattel, Jesper Henri
2012-01-01
Purpose - The purpose of this paper is to determine the magnitude and spatial distribution of the heat transfer coefficient between the workpiece and the backingplate in a friction stir welding process using inverse modelling. Design/methodology/approach - The magnitude and distribution of the heat...... in an inverse modeling approach to determine the heat transfer coefficient in friction stir welding. © Emerald Group Publishing Limited....
Genome-scale cluster analysis of replicated microarrays using shrinkage correlation coefficient.
Yao, Jianchao; Chang, Chunqi; Salmi, Mari L; Hung, Yeung Sam; Loraine, Ann; Roux, Stanley J
2008-06-18
Currently, clustering with some form of correlation coefficient as the gene similarity metric has become a popular method for profiling genomic data. The Pearson correlation coefficient and the standard deviation (SD)-weighted correlation coefficient are the two most widely-used correlations as the similarity metrics in clustering microarray data. However, these two correlations are not optimal for analyzing replicated microarray data generated by most laboratories. An effective correlation coefficient is needed to provide statistically sufficient analysis of replicated microarray data. In this study, we describe a novel correlation coefficient, shrinkage correlation coefficient (SCC), that fully exploits the similarity between the replicated microarray experimental samples. The methodology considers both the number of replicates and the variance within each experimental group in clustering expression data, and provides a robust statistical estimation of the error of replicated microarray data. The value of SCC is revealed by its comparison with two other correlation coefficients that are currently the most widely-used (Pearson correlation coefficient and SD-weighted correlation coefficient) using statistical measures on both synthetic expression data as well as real gene expression data from Saccharomyces cerevisiae. Two leading clustering methods, hierarchical and k-means clustering were applied for the comparison. The comparison indicated that using SCC achieves better clustering performance. Applying SCC-based hierarchical clustering to the replicated microarray data obtained from germinating spores of the fern Ceratopteris richardii, we discovered two clusters of genes with shared expression patterns during spore germination. Functional analysis suggested that some of the genetic mechanisms that control germination in such diverse plant lineages as mosses and angiosperms are also conserved among ferns. This study shows that SCC is an alternative to the Pearson
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)
Positive transfer operators and decay of correlations
Baladi, Viviane
2000-01-01
Although individual orbits of chaotic dynamical systems are by definition unpredictable, the average behavior of typical trajectories can often be given a precise statistical description. Indeed, there often exist ergodic invariant measures with special additional features. For a given invariant measure, and a class of observables, the correlation functions tell whether (and how fast) the system "mixes", i.e. "forgets" its initial conditions.This book, addressed to mathematicians and mathematical (or mathematically inclined) physicists, shows how the powerful technology of transfer operators,
Statistical electron correlation coefficients for the five lowest states of the heliumlike ions
International Nuclear Information System (INIS)
Thakkar, A.J.; Smith, V.H. Jr.
1981-01-01
Statistical correlation coefficients were introduced by Kutzelnigg, Del Re, and Berthier to provide overall measures of the difference between the electron pair density and the product of one-electron densities in atoms and molecules. Some properties of these coefficients are discussed, and it is shown that an angular correlation coefficient is experimentally accessible. Radial and angular correlation coefficients are computed from highly accurate wave functions for the 1 1 S, 2 3 S, 2 1 S, 2 3 P, and 2 1 P states of the heliumlike ions from He through Mg 10+ . It is found that positive angular correlation coefficients occur in the 2 1 P state of the two-electron positive ions but not in neutral helium. Moreover, the angular correlation coefficients for the 2 1 S and 2 3 S states of the positively charged two-electron ions show that a previously proposed reformulation of Hund's rule is incorrect
Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.
2014-01-01
The recuperative heat exchanger governs the overall performance of the mixed refrigerant Joule-Thomson cryocooler. In these heat exchangers, the non-azeotropic refrigerant mixture of nitrogen-hydrocarbons undergoes boiling and condensation simultaneously at cryogenic temperature. Hence, the design of such heat exchanger is crucial. However, due to lack of empirical correlations to predict two-phase heat transfer coefficients of multi-component mixtures at low temperature, the design of such heat exchanger is difficult.
Does charge transfer correlate with ignition probability?
International Nuclear Information System (INIS)
Holdstock, Paul
2008-01-01
Flammable or explosive atmospheres exist in many industrial environments. The risk of ignition caused by electrostatic discharges is very real and there has been extensive study of the incendiary nature of sparks and brush discharges. It is clear that in order to ignite a gas, an amount of energy needs to be delivered to a certain volume of gas within a comparatively short time. It is difficult to measure the energy released in an electrostatic discharge directly, but it is possible to approximate the energy in a spark generated from a well defined electrical circuit. The spark energy required to ignite a gas, vapour or dust cloud can be determined by passing such sparks through them. There is a relationship between energy and charge in a capacitive circuit and so it is possible to predict whether or not a spark discharge will cause an ignition by measuring the charge transferred in the spark. Brush discharges are in many ways less well defined than sparks. Nevertheless, some work has been done that has established a relationship between charge transferred in brush discharges and the probability of igniting a flammable atmosphere. The question posed by this paper concerns whether such a relationship holds true in all circumstances and if there is a universal correlation between charge transfer and ignition probability. Data is presented on discharges from textile materials that go some way to answering this question.
Space-dependent perfusion coefficient estimation in a 2D bioheat transfer problem
Bazán, Fermín S. V.; Bedin, Luciano; Borges, Leonardo S.
2017-05-01
In this work, a method for estimating the space-dependent perfusion coefficient parameter in a 2D bioheat transfer model is presented. In the method, the bioheat transfer model is transformed into a time-dependent semidiscrete system of ordinary differential equations involving perfusion coefficient values as parameters, and the estimation problem is solved through a nonlinear least squares technique. In particular, the bioheat problem is solved by the method of lines based on a highly accurate pseudospectral approach, and perfusion coefficient values are estimated by the regularized Gauss-Newton method coupled with a proper regularization parameter. The performance of the method on several test problems is illustrated numerically.
Modeling of the substrate and product transfer coefficients for ethanol fermentation
International Nuclear Information System (INIS)
Zerajic, S.; Grbavcic, Z.; Savkovic-Stevanovic, J.
2008-01-01
The transfer phenomena of the substrate and product for ethanol fermentation with immobilized biocatalyst were investigated. Fermentation was carried out with a biocatalyst consisting of Ca-alginate gel in the form of two-layer spherical beads in anaerobic conditions. The determination of kinetic parameters was achieved by fitting bioreaction progress curves to the experimental data. The calculation of the diffusion coefficients was performed by numerical methods for experimental conditions. Finally, the glucose and ethanol transfer coefficients are defined and determined, using the effective diffusion coefficients. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
SEPHIS and the distribution coefficients correlation in the IMPUREX system
International Nuclear Information System (INIS)
Andaur Iturrieta, Claudio
1997-01-01
The reprocessing of spent nuclear fuels by the IMPUREX process consists in uranium selective extraction, originally in aqueous nitric solution, by action of the tributyl phosphate (TBP) present in an organic phase that circulates at countercurrent of the aqueous one. In the study of such process, it is necessary to use the correlations that allows to predict the concentrations of the solutes in the equilibrium, both in the aqueous phase and in the organic one, given as data the ruling operation conditions (temperature, TBP concentration and acidity). A correlation of this kind is the Groenier-Rainey-Watson, which is forming part of the code of the SEPHIS simulation program. In the present work it is analyzed the behavior of this correlation contrasting the predicted values with experimental ones
Santo, M V; Sansinena, M; Chirife, J; Zaritzky, N
2015-01-01
The use of mathematical models describing heat transfer during the freezing process is useful for the improvement of cryopreservation protocols. A widespread practice for cryopreservation of spermatozoa of domestic animal species consists of suspending plastic straws in nitrogen vapor before plunging into liquid nitrogen. Knowledge of surface heat transfer coefficient (h) is mandatory for computational modelling; however, h values for nitrogen vapor are not available. In the present study, surface heat transfer coefficients for plastic French straws immersed in nitrogen vapor over liquid nitrogen was determined; vertical and horizontal positions were considered. Heat transfer coefficients were determined from the measurement of time-temperature curves and from numerical solution of heat transfer partial differential equation under transient conditions using finite elements. The h values experimentally obtained for horizontal and vertically placed straws were compared to those calculated using correlations based on the Nusselt number for natural convection. For horizontal straws the average obtained value was h=12.5 ± 1.2 W m(2) K and in the case of vertical straws h=16 ± 2.48 W m(2) K. The numerical simulation validated against experimental measurements, combined with accurate h values provides a reliable tool for the prediction of freezing curves of semen-filled straws immersed in nitrogen vapor. The present study contributes to the understanding of the cryopreservation techniques for sperm freezing based on engineering concepts, improving the cooling protocols and the manipulation of the straws.
Study on heat transfer coefficients during cooling of PET bottles for food beverages
Liga, Antonio; Montesanto, Salvatore; Mannella, Gianluca A.; La Carrubba, Vincenzo; Brucato, Valerio; Cammalleri, Marco
2016-08-01
The heat transfer properties of different cooling systems dealing with Poly-Ethylene-Terephthalate (PET) bottles were investigated. The heat transfer coefficient (Ug) was measured in various fluid dynamic conditions. Cooling media were either air or water. It was shown that heat transfer coefficients are strongly affected by fluid dynamics conditions, and range from 10 W/m2 K to nearly 400 W/m2 K. PET bottle thickness effect on Ug was shown to become relevant under faster fluid dynamics regimes.
Spin transfer coefficient DΛLL to Λ hyperon in semi-inclusive DIS at HERMES
International Nuclear Information System (INIS)
Belostotski, S; Veretennikov, D; Naryshkin, Yu
2011-01-01
Three components of the spin transfer coefficient from the longitudinally polarized electron/positron beam to the Λ or Λ-bar hyperon have been measured in the HERMES experiment. Kinematical dependencies of the spin-transfer have been studied. Averaged over Λ kinematics, longitudinal component of the spin transfer DΛ LL (along the virtual photon direction) to the Λ hyperon is found to be DΛ LL = 0.19 ± 0.04 stat ± 0.02 syst .
Efficient tracking of the cross-correlation coefficient
Aarts, R.M.; Irwan, R.; Janssen, A.J.E.M.
2002-01-01
In many (audio) processing algorithms, involving manipulation of discrete-time signals, the performance can vary strongly over the repertoire that is used. This may be the case when the signals from the various channels are allowed to be strongly positively or negatively correlated. We propose and
147 - 154 Genetic Variability, Heritability and Correlation Coefficient
African Journals Online (AJOL)
USER
twelve upland rice genotypes during 2013 main cropping season. ... spikelet per panicle, number of filled grains per panicle and biomass yield had a positive and significant correlation ... fertilizers were applied at the rate of 100 kg per hectare. ..... ultimate effect for selecting superior varieties (Ali et al., .... (Brassica napus L.).
Multi criteria decision making using correlation coefficient under rough neutrosophic environment
Directory of Open Access Journals (Sweden)
Surapati Pramanik
2017-09-01
Full Text Available In this paper, we define correlation coefficient measure between any two rough neutrosophic sets. We also prove some of its basic properties.. We develop a new multiple attribute group decision making method based on the proposed correlation coefficient measure.
Multi criteria decision making using correlation coefficient under rough neutrosophic environment
Pramanik, Surapati; Roy, Rumi; Roy, Tapan Kumar; Smarandache, Florentin
2017-01-01
In this paper, we define correlation coefficient measure between any two rough neutrosophic sets. We also prove some of its basic properties. We develop a new multiple attribute group decision making method based on the proposed correlation coefficient measure. An illustrative example of medical diagnosis is solved to demonstrate the applicability and effecriveness of the proposed method.
Directory of Open Access Journals (Sweden)
Zhong-xing Wang
2017-11-01
Full Text Available Correlation coefficient is one of the broadly use indexes in multi-criteria decision-making (MCDM processes. However, some important issues related to correlation coefficient utilization within probabilistic hesitant fuzzy environments remain to be addressed. The purpose of this study is introduced a MCDM method based on correlation coefficients utilize probabilistic hesitant fuzzy information. First, the covariance and correlation coefficient between two PHFEs is introduced, the properties of the proposed covariance and correlation coefficient are discussed. In addition, the northwest corner rule to obtain the expected mean related to the multiply of two PHFEs is introduced. Second, the weighted correlation coefficient is proposed to make the proposed MCDM method more applicable. And the properties of the proposed weighted correlation coefficient are also discussed. Finally, an illustrative example is demonstrated the practicality and effectiveness of the proposed method. An illustrative example is presented to demonstrate the correlation coefficient propose in this paper lies in the interval [−1, 1], which not only consider the strength of relationship between the PHFEs but also whether the PHFEs are positively or negatively related. The advantage of this method is it can avoid the inconsistency of the decision-making result due to the loss of information.
Korendijk, Elly J. H.; Moerbeek, Mirjam; Maas, Cora J. M.
2010-01-01
In the case of trials with nested data, the optimal allocation of units depends on the budget, the costs, and the intracluster correlation coefficient. In general, the intracluster correlation coefficient is unknown in advance and an initial guess has to be made based on published values or subject matter knowledge. This initial estimate is likely…
Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.
Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P
2016-06-01
We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.
Korendijk, E.J.H.; Moerbeek, M.; Maas, C.J.M.
2010-01-01
In the case of trials with nested data, the optimal allocation of units depends on the budget, the costs, and the intracluster correlation coefficient. In general, the intracluster correlation coefficient is unknown in advance and an initial guess has to be made based on published values or
Wilson, Celia M.
2010-01-01
Research pertaining to the distortion of the squared canonical correlation coefficient has traditionally been limited to the effects of sampling error and associated correction formulas. The purpose of this study was to compare the degree of attenuation of the squared canonical correlation coefficient under varying conditions of score reliability.…
Evaluation of correlations of flow boiling heat transfer of R22 in horizontal channels.
Zhou, Zhanru; Fang, Xiande; Li, Dingkun
2013-01-01
The calculation of two-phase flow boiling heat transfer of R22 in channels is required in a variety of applications, such as chemical process cooling systems, refrigeration, and air conditioning. A number of correlations for flow boiling heat transfer in channels have been proposed. This work evaluates the existing correlations for flow boiling heat transfer coefficient with 1669 experimental data points of flow boiling heat transfer of R22 collected from 18 published papers. The top two correlations for R22 are those of Liu and Winterton (1991) and Fang (2013), with the mean absolute deviation of 32.7% and 32.8%, respectively. More studies should be carried out to develop better ones. Effects of channel dimension and vapor quality on heat transfer are analyzed, and the results provide valuable information for further research in the correlation of two-phase flow boiling heat transfer of R22 in channels.
Empirical correlations for axial dispersion coefficient and Peclet number in fixed-bed columns.
Rastegar, Seyed Omid; Gu, Tingyue
2017-03-24
In this work, a new correlation for the axial dispersion coefficient was obtained using experimental data in the literature for axial dispersion in fixed-bed columns packed with particles. The Chung and Wen correlation, the De Ligny correlation are two popular empirical correlations. However, the former lacks the molecular diffusion term and the latter does not consider bed voidage. The new axial dispersion coefficient correlation in this work was based on additional experimental data in the literature by considering both molecular diffusion and bed voidage. It is more comprehensive and accurate. The Peclet number correlation from the new axial dispersion coefficient correlation on the average leads to 12% lower Peclet number values compared to the values from the Chung and Wen correlation, and in many cases much smaller than those from the De Ligny correlation. Copyright © 2017 Elsevier B.V. All rights reserved.
Measuring correlations between non-stationary series with DCCA coefficient
Czech Academy of Sciences Publication Activity Database
Krištoufek, Ladislav
2014-01-01
Roč. 402, č. 1 (2014), s. 291-298 ISSN 0378-4371 R&D Projects: GA ČR(CZ) GP14-11402P Grant - others:GA ČR(CZ) GAP402/11/0948 Program:GA Institutional support: RVO:67985556 Keywords : power-law cross-correlations * long - term memory * econophysics Subject RIV: AH - Economics Impact factor: 1.732, year: 2014 http://library.utia.cas.cz/separaty/2014/E/kristoufek-0433533.pdf
Detecting genuine multipartite correlations in terms of the rank of coefficient matrix
International Nuclear Information System (INIS)
Li Bo; Kwek, Leong Chuan; Fan Heng
2012-01-01
We propose a method to detect genuine quantum correlation for arbitrary quantum states in terms of the rank of coefficient matrices associated with the pure state. We then derive a necessary and sufficient condition for a quantum state to possess genuine correlation, namely that all corresponding coefficient matrices have rank larger than 1. We demonstrate an approach to decompose the genuine quantum correlated state with high rank coefficient matrix into the form of product states with no genuine quantum correlation for a pure state. (paper)
Heat transfer coefficient testing in nuclear fuel rod bundles with mixing vane grids
International Nuclear Information System (INIS)
Conner, Michael E.; Smith, L. David III; Holloway, Mary V.; Beasley, Donald E.
2005-01-01
An air heat transfer test facility was developed to test the heat transfer downstream of support grids in simulated PWR nuclear fuel rod bundles. The goal of this testing is to study the single-phase heat transfer coefficients downstream of grids with mixing vanes in a square-pitch rod bundle. The technique developed utilizes fully-heated grid spans and a specially designed thermocouple holder that can be moved axially down the rod bundle and aximuthally within a test rod. From this testing, the axial and aximuthally varying heat transfer coefficient can be determined. Different grid designs are tested and compared to determine the heat transfer enhancement associated with key grid features such as mixing vanes. (author)
Calculation of the mass transfer coefficient for the combustion of a carbon particle
Energy Technology Data Exchange (ETDEWEB)
Scala, Fabrizio [Istituto di Ricerche sulla Combustione - CNR, P.le Tecchio 80, 80125 Napoli (Italy)
2010-01-15
In this paper we address the calculation of the mass transfer coefficient around a burning carbon particle in an atmosphere of O{sub 2}, N{sub 2}, CO{sub 2}, CO, and H{sub 2}O. The complete set of Stefan-Maxwell equations is analytically solved under the assumption of no homogeneous reaction in the boundary layer. An expression linking the oxygen concentration and the oxygen flux at the particle surface (as a function of the bulk gas composition) is derived which can be used to calculate the mass transfer coefficient. A very simple approximate explicit expression is also given for the mass transfer coefficient, that is shown to be valid in the low oxygen flux limit or when the primary combustion product is CO{sub 2}. The results are given in terms of a correction factor to the equimolar counter-diffusion mass transfer coefficient, which is typically available in the literature for specific geometries and/or fluid-dynamic conditions. The significance of the correction factor and the accuracy of the different available expressions is illustrated for several cases of practical interest. Results show that under typical combustion conditions the use of the equimolar counter-diffusion mass transfer coefficient can lead to errors up to 10%. Larger errors are possible in oxygen-enriched conditions, while the error is generally low in oxy-combustion. (author)
Parekh, Anant; Gnanaseelan, C.; Jayakumar, A.
2011-01-01
Long time series of in situ observations from the north Indian Ocean are used to compute the momentum transfer coefficients over the north Indian Ocean. The transfer coefficients behave nonlinearly for low winds (<4 m/s), when most of the known empirical relations assume linear relations. Impact of momentum transfer coefficients on the upper ocean parameters is studied using an ocean general circulation model. The model experiments revealed that the Arabian Sea and Equatorial Indian Ocean are more sensitive to the momentum transfer coefficients than the Bay of Bengal and south Indian Ocean. The impact of momentum transfer coefficients on sea surface temperature is up to 0.3°C-0.4°C, on mixed layer depth is up to 10 m, and on thermocline depth is up to 15 m. Furthermore, the impact on the zonal current is maximum over the equatorial Indian Ocean (i.e., about 0.12 m/s in May and 0.15 m/s in October; both May and October are the period of Wyrtki jets and the difference in current has potential impact on the seasonal mass transport). The Sverdrup transport has maximum impact in the Bay of Bengal (3 to 4 Sv in August), whereas the Ekman transport has maximum impact in the Arabian Sea (4 Sv during May to July). These highlight the potential impact of accurate momentum forcing on the results from current ocean models.
Taylor, Maynard F.; Kirchgessner, Thomas A.
1959-01-01
Measurements of average heat transfer and friction coefficients and local heat transfer coefficients were made with helium flowing through electrically heated smooth tubes with length-diameter ratios of 60 and 92 for the following range of conditions: Average surface temperature from 1457 to 4533 R, Reynolds numbe r from 3230 to 60,000, heat flux up to 583,200 Btu per hr per ft2 of heat transfer area, and exit Mach numbe r up to 1.0. The results indicate that, in the turbulent range of Reynolds number, good correlation of the local heat transfer coefficients is obtained when the physical properties and density of helium are evaluated at the surface temperature. The average heat transfer coefficients are best correlated on the basis that the coefficient varies with [1 + (L/D))(sup -0,7)] and that the physical properties and density are evaluated at the surface temperature. The average friction coefficients for the tests with no heat addition are in complete agreement with the Karman-Nikuradse line. The average friction coefficients for heat addition are in poor agreement with the accepted line.
ppcor: An R Package for a Fast Calculation to Semi-partial Correlation Coefficients.
Kim, Seongho
2015-11-01
Lack of a general matrix formula hampers implementation of the semi-partial correlation, also known as part correlation, to the higher-order coefficient. This is because the higher-order semi-partial correlation calculation using a recursive formula requires an enormous number of recursive calculations to obtain the correlation coefficients. To resolve this difficulty, we derive a general matrix formula of the semi-partial correlation for fast computation. The semi-partial correlations are then implemented on an R package ppcor along with the partial correlation. Owing to the general matrix formulas, users can readily calculate the coefficients of both partial and semi-partial correlations without computational burden. The package ppcor further provides users with the level of the statistical significance with its test statistic.
Convective Heat Transfer Coefficients of the Human Body under Forced Convection from Ceiling
DEFF Research Database (Denmark)
Kurazumi, Yoshihito; Rezgals, Lauris; Melikov, Arsen Krikor
2014-01-01
The average convective heat transfer coefficient for a seated human body exposed to downward flow from above was determined. Thermal manikin with complex body shape and size of an average Scandinavian female was used. The surface temperature distribution of the manikin’s body was as the skin...... of the convective heat transfer coefficient of the whole body (hc [W/(m2•K)]) was proposed: hc=4.088+6.592V1.715 for a seated naked body at 20ºC and hc=2.874+7.427V1.345 for a seated naked body at 26ºC. Differences in the convective heat transfer coefficient of the whole body in low air velocity range, V
Diagnosing cysts with correlation coefficient images from 2-dimensional freehand elastography.
Booi, Rebecca C; Carson, Paul L; O'Donnell, Matthew; Richards, Michael S; Rubin, Jonathan M
2007-09-01
We compared the diagnostic potential of using correlation coefficient images versus elastograms from 2-dimensional (2D) freehand elastography to characterize breast cysts. In this preliminary study, which was approved by the Institutional Review Board and compliant with the Health Insurance Portability and Accountability Act, we imaged 4 consecutive human subjects (4 cysts, 1 biopsy-verified benign breast parenchyma) with freehand 2D elastography. Data were processed offline with conventional 2D phase-sensitive speckle-tracking algorithms. The correlation coefficient in the cyst and surrounding tissue was calculated, and appearances of the cysts in the correlation coefficient images and elastograms were compared. The correlation coefficient in the cysts was considerably lower (14%-37%) than in the surrounding tissue because of the lack of sufficient speckle in the cysts, as well as the prominence of random noise, reverberations, and clutter, which decorrelated quickly. Thus, the cysts were visible in all correlation coefficient images. In contrast, the elastograms associated with these cysts each had different elastographic patterns. The solid mass in this study did not have the same high decorrelation rate as the cysts, having a correlation coefficient only 2.1% lower than that of surrounding tissue. Correlation coefficient images may produce a more direct, reliable, and consistent method for characterizing cysts than elastograms.
CFD simulation of simultaneous monotonic cooling and surface heat transfer coefficient
International Nuclear Information System (INIS)
Mihálka, Peter; Matiašovský, Peter
2016-01-01
The monotonic heating regime method for determination of thermal diffusivity is based on the analysis of an unsteady-state (stabilised) thermal process characterised by an independence of the space-time temperature distribution on initial conditions. At the first kind of the monotonic regime a sample of simple geometry is heated / cooled at constant ambient temperature. The determination of thermal diffusivity requires the determination rate of a temperature change and simultaneous determination of the first eigenvalue. According to a characteristic equation the first eigenvalue is a function of the Biot number defined by a surface heat transfer coefficient and thermal conductivity of an analysed material. Knowing the surface heat transfer coefficient and the first eigenvalue the thermal conductivity can be determined. The surface heat transport coefficient during the monotonic regime can be determined by the continuous measurement of long-wave radiation heat flow and the photoelectric measurement of the air refractive index gradient in a boundary layer. CFD simulation of the cooling process was carried out to analyse local convective and radiative heat transfer coefficients more in detail. Influence of ambient air flow was analysed. The obtained eigenvalues and corresponding surface heat transfer coefficient values enable to determine thermal conductivity of the analysed specimen together with its thermal diffusivity during a monotonic heating regime.
Transfer coefficient study of Sr-90 in the soil-grass-milk chain for Cuba
International Nuclear Information System (INIS)
Zerquera, J. T.; Sarria P, R.
1996-01-01
One of the most important problems in modern radioecology is the lack of able information about the features of radionuclide migration in tropical and subtropical environment. The development of nuclear energy and the enhancing in the applications of nuclear techniques in those latitudes indicate that studies in this area are necessary. Cuba is carrying out studies on radioecological characterization of the principal food chains in the country. One of the objectives of these studies is to define the values of the transfer coefficients to be used in the evaluation programs for the assessment of the radiological impact of practices which involve ionizing radiation. This paper shows the results obtained in the determination of Sr-90 transfer coefficients in soil-grass-milk food chain in 'La Quebrada', a place near the Havana City where an important part of the milk that the citizens consume is produced. Transfer coefficients for Sr-90 were calculated on the basis of data collected during 5 years in the region. Soil-grass transfer coefficients are in the range 0.18-5 while grass-milk coefficients are in the range of 1.2x10 -4 - 6x10 -3 day/L. These values are in accordance with values reported by other authors in the literature. (authors). 4 refs., 2 tabs
International Nuclear Information System (INIS)
Moeller, S.V.
1982-09-01
The determination of the heat transfer coefficient of the pins of the Spallation Neutron Source is a very important problem for the development of this facility, as data for thermal and structural studies. For this purpose, a test apparatus was built, in scale 1:1, for the simulation of the thermal and hydraulical conditions of the Neutron Source. This apparatus is a pin bank, with one of the pins electrically heated. Performance of measurements gave the values for the heat transfer coefficient, here presented in the Nusselt Number form, and its local distribution. Results show the linear dependence of Nusselt Number on Reynolds Number, for a constant heat production. (orig.) [de
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)
Comparing two K-category assignments by a K-category correlation coefficient
DEFF Research Database (Denmark)
Gorodkin, Jan
2004-01-01
Predicted assignments of biological sequences are often evaluated by Matthews correlation coefficient. However, Matthews correlation coefficient applies only to cases where the assignments belong to two categories, and cases with more than two categories are often artificially forced into two...... categories by considering what belongs and what does not belong to one of the categories, leading to the loss of information. Here, an extended correlation coefficient that applies to K-categories is proposed, and this measure is shown to be highly applicable for evaluating prediction of RNA secondary...
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.
Statistics corner: A guide to appropriate use of correlation coefficient in medical research.
Mukaka, M M
2012-09-01
Correlation is a statistical method used to assess a possible linear association between two continuous variables. It is simple both to calculate and to interpret. However, misuse of correlation is so common among researchers that some statisticians have wished that the method had never been devised at all. The aim of this article is to provide a guide to appropriate use of correlation in medical research and to highlight some misuse. Examples of the applications of the correlation coefficient have been provided using data from statistical simulations as well as real data. Rule of thumb for interpreting size of a correlation coefficient has been provided.
Transfer coefficients of 137Cs via the forage-cow-milk pathway in Aomori Prefecture of Japan
International Nuclear Information System (INIS)
Ito, Nobuhiko; Kunugiyama, Iwao; Kiguchi, Shinji; Kubo, Moriyoshi; Kameta, Masanori; Furukawa, Yoshinori
1994-01-01
The transfer of radiocesium to foodstuff of cattle is very serious, because it contributes significantly to internal exposure resulting from the intake of 137 Cs through the feed-cow-milk pathway. The transfer coefficient from feed to milk (F m ) is widely used to predict the dose to man from the radioactivity released to the biosphere. A commercial fuel reprocessing plant is under construction in Rokkasho-mura/Aomori Prefecture, the northeastern district of Japan. To figure out F m under conventional farming conditions, therefore, transfer of 137 Cs deposited in the environment in cooperation with two daily farms in this region. Transfer factors for 137 Cs from feed to cow's milk have been obtained from data acquired from biweekly routine monitoring program under the two dissimilar farming conditions. The one dairy farm condition is mainly composed of high hay ration and the other is high concentrate ration. As a result of the experiments, 137 Cs activity of milk correlated significantly with that of feed. The mean transfer coefficients of 137 Cs to milk were calculated to be 0.0037 and 0.0063 (d/l), respectively. (author)
Krijnen, WP
De Vries (1993) discusses Pearson's product-moment correlation, Spearman's rank correlation, and Kendall's rank-correlation coefficient for assessing the association between the rows of two proximity matrices. For each of these he introduces a weighted average variant and a rowwise variant. In this
KRIJNEN, WP
De Vries (1993) discusses Pearson's product-moment correlation, Spearman's rank correlation, and Kendall's rank-correlation coefficient for assessing the association between the rows of two proximity matrices. For each of these he introduces a weighted average variant and a rowwise variant. In this
Heat transfer coefficient for lead matrixing in disposal containers for used reactor fuel
International Nuclear Information System (INIS)
Mathew, P.M.; Taylor, M.; Krueger, P.A.
1985-02-01
In the Canadian Nuclear Fuel Waste Management Program, metal matrices with low melting points are being evaluated for their potential to provide support for the shell of disposal containers for used fuel, and to act as an additional barrier to the release of radionuclides. The metal matrix would be incorporated into the container by casting. To study the heat transfer processes during solidification, a steady-state technique was used, involving lead as the cast metal, to determine the overall heat transfer coefficient between the lead and some of the candidate container materials. The existence of an air gap between the cast lead and the container material appeared to control the overall heat transfer coefficient. The experimental observations indicated that the surface topography of the container material influences the heat transfer and that a smoother surface results in a greater heat transfer than a rough surface. The experimental results also showed an increasing heat transfer coefficient with increasing temperature difference across the container base plates; a model developed to base-plate bending can explain the observed results
Beijeren, H. van; Kehr, K.W.
1986-01-01
The correlation factor, defined as the ratio between the tracer diffusion coefficient in lattice gases and the diffusion coefficient for a corresponding uncorrelated random walk, is known to assume a very simple form under certain conditions. A simple derivation of this is given with the aid of
Wang, Fang; Wang, Lin; Chen, Yuming
2017-08-31
In order to investigate the time-dependent cross-correlations of fine particulate (PM2.5) series among neighboring cities in Northern China, in this paper, we propose a new cross-correlation coefficient, the time-lagged q-L dependent height crosscorrelation coefficient (denoted by p q (τ, L)), which incorporates the time-lag factor and the fluctuation amplitude information into the analogous height cross-correlation analysis coefficient. Numerical tests are performed to illustrate that the newly proposed coefficient ρ q (τ, L) can be used to detect cross-correlations between two series with time lags and to identify different range of fluctuations at which two series possess cross-correlations. Applying the new coefficient to analyze the time-dependent cross-correlations of PM2.5 series between Beijing and the three neighboring cities of Tianjin, Zhangjiakou, and Baoding, we find that time lags between the PM2.5 series with larger fluctuations are longer than those between PM2.5 series withsmaller fluctuations. Our analysis also shows that cross-correlations between the PM2.5 series of two neighboring cities are significant and the time lags between two PM2.5 series of neighboring cities are significantly non-zero. These findings providenew scientific support on the view that air pollution in neighboring cities can affect one another not simultaneously but with a time lag.
Determining Sample Size for Accurate Estimation of the Squared Multiple Correlation Coefficient.
Algina, James; Olejnik, Stephen
2000-01-01
Discusses determining sample size for estimation of the squared multiple correlation coefficient and presents regression equations that permit determination of the sample size for estimating this parameter for up to 20 predictor variables. (SLD)
Correlation Coefficients of Extended Hesitant Fuzzy Sets and Their Applications to Decision Making
Directory of Open Access Journals (Sweden)
Na Lu
2017-03-01
Full Text Available Extended hesitant fuzzy sets (EHFSs, which allow the membership degree of an element to a set represented by several possible value-groups, can be considered as a powerful tool to express uncertain information in the process of group decision making. Therefore, we derive some correlation coefficients between EHFSs, which contain two cases, the correlation coefficients taking into account the length of extended hesitant fuzzy elements (EHFEs and the correlation coefficients without taking into account the length of EHFEs, as a new extension of existing correlation coefficients for hesitant fuzzy sets (HFSs and apply them to decision making under extended hesitant fuzzy environments. A real-world example based on the energy policy problem is employed to illustrate the actual need for dealing with the difference of evaluation information provided by different experts without information loss in decision making processes.
Observations of copolar correlation coefficient through a bright band at vertical incidence
Zrnic, D. S.; Raghavan, R.; Chandrasekar, V.
1994-01-01
This paper discusses an application of polarimetric measurements at vertical incidence. In particular, the correlation coefficients between linear copolar components are examined, and measurements obtained with the National Severe Storms Laboratory (NSSL)'s and National Center for Atmospheric Research (NCAR)'s polarimetric radars are presented. The data are from two well-defined bright bands. A sharp decrease of the correlation coefficient, confined to a height interval of a few hundred meters, marks the bottom of the bright band.
Controlling the Internal Heat Transfer Coefficient by the Characteristics of External Flows
Zhuromskii, V. M.
2018-01-01
The engineering-physical fundamentals of substance synthesis in a boiling apparatus are presented. We have modeled a system of automatic stabilization of the maximum internal heat transfer coefficient in such an apparatus by the characteristics of external flows on the basis of adaptive seeking algorithms. The results of operation of the system in the shop are presented.
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
Wall heat transfer coefficient in a molten salt bubble column: testing the experimental setup
CSIR Research Space (South Africa)
Skosana, PJ
2014-10-01
Full Text Available reactors that are highly exothermic or endothermic. This paper presents the design and operation of experimental setup used for measurement of the heat transfer coefficient in molten salt media. The experimental setup was operated with tap water, heat...
Evaluation of convective heat transfer coefficient of various crops in cyclone type dryer
International Nuclear Information System (INIS)
Akpinar, E. Kavak
2005-01-01
In this paper, an attempt was made to evaluate the convective heat transfer coefficient during drying of various crops and to investigate the influences of drying air velocity and temperature on the convective heat transfer coefficient. Drying was conducted in a convective cyclone type dryer at drying air temperatures of 60, 70 and 80 deg. C and velocities of 1 and 1.5 m/s using rectangle shaped potato and apple slices (12.5 x 12.5 x 25 mm) and cylindrical shaped pumpkin slices (35 x 5 mm). The temperature changes of the dried crops and the temperature of the drying air were measured during the drying process. It was found that the values of convective heat transfer coefficient varied from crop to crop with a range 30.21406 and 20.65470 W/m 2 C for the crops studied, and it was observed that the convective heat transfer coefficient increased in large amounts with the increase of the drying air velocity but increased in small amounts with the rise of the drying air temperature
Numerical calculation of wall-to-bed heat transfer coefficients in gas-fluidized beds
Kuipers, J.A.M.; Prins, W.; van Swaaij, W.P.M.
1992-01-01
A computer model for a hot gas-fluidized bed has been developed. The theoretical description is based on a two-fluid model (TFM) approach in which both phases are considered to be continuous and fully interpenetrating. Local wall-to-bed heat-transfer coefficients have been calculated by the
Development of a model to determine mass transfer coefficient and oxygen solubility in bioreactors
Directory of Open Access Journals (Sweden)
Johnny Lee
2017-02-01
where T is in degree Kelvin, and the subscripts refer to degree Celsius; E, ρ, σ are properties of water. Furthermore, using data from published data on oxygen solubility in water, it was found that solubility bears a linear and inverse relationship with the mass transfer coefficient.
Energy Technology Data Exchange (ETDEWEB)
Uffrecht, Wieland; Guenther, Andre [TU Dresden (Germany). Inst. fuer Stroemungsmechanik; Caspary, Volker [MAN Diesel und Turbo SE, Oberhausen (Germany)
2012-07-01
The measurement of heat transfer coefficients at rotating machine parts is a difficult measurement task and is particularily challenging for fast rotating parts with good thermal conductivity in combination with gaseous flow. This contribution reports about the test of a setup with small thermistors employed to achieve compatibility with the demands of telemetry. (orig.)
Evaluation of convective heat transfer coefficient of various crops in cyclone type dryer
Energy Technology Data Exchange (ETDEWEB)
Akpinar, E. Kavak [Mechanical Engineering Department, Firat University, 23279 Elazig (Turkey)]. E-mail: eakpinar@firat.edu.tr
2005-09-15
In this paper, an attempt was made to evaluate the convective heat transfer coefficient during drying of various crops and to investigate the influences of drying air velocity and temperature on the convective heat transfer coefficient. Drying was conducted in a convective cyclone type dryer at drying air temperatures of 60, 70 and 80 deg. C and velocities of 1 and 1.5 m/s using rectangle shaped potato and apple slices (12.5 x 12.5 x 25 mm) and cylindrical shaped pumpkin slices (35 x 5 mm). The temperature changes of the dried crops and the temperature of the drying air were measured during the drying process. It was found that the values of convective heat transfer coefficient varied from crop to crop with a range 30.21406 and 20.65470 W/m{sup 2} C for the crops studied, and it was observed that the convective heat transfer coefficient increased in large amounts with the increase of the drying air velocity but increased in small amounts with the rise of the drying air temperature.
Directory of Open Access Journals (Sweden)
Y.K.Sklifus
2012-12-01
Full Text Available The article presents the calculation of heat transfer coefficient during condensation of steam, the mathematical model of temperature distribution in the gas and liquid phases of the coolant and the model of the formation of the condensate film on the walls of the tubes.
Condensation heat transfer coefficients of flammable refrigerants on various enhanced tubes
International Nuclear Information System (INIS)
Park, Ki Jung; Jung, Dong Soo
2005-01-01
In this study, external condensation Heat Transfer Coefficients (HTCs) of six flammable refrigerants of propylene (R1270), propane (R290), isobutane (R600a), butane (R600), dimethylether (RE170), and HFC32 were measured at the vapor temperature of 39 .deg. C on a 1023 fpm low fin and turbo-C tubes. All data were taken under the heat flux of 32∼116 and 42∼142 kW/m 2 for the low fin and turbo-C tubes respectively. Flammable refrigerants' data obtained on enhanced tubes showed a typical trend that external condensation HTCs decrease with increasing wall subcooling. HFC32 and DME showed up to 30% higher HTCs than those of HCFC22 due to their excellent thermophysical properties. Propylene, propane, isobutane, and butane showed similar or lower HTCs than those of HCFC22. Beatty and Katz' correlation predicted the HTCs of the flammable refrigerants obtained on a low fin tube within a mean deviation of 7.3%. Turbo-C tube showed the best performance due to its 3 dimensional surface geometry for fast removal of condensate
DEFF Research Database (Denmark)
Rong, Li; Nielsen, Peter V.; Zhang, Guoqiang
2010-01-01
greatly along the airflow direction on the emission surface. The average mass transfer coefficient increases with higher velocity and turbulence intensity. However, the mass transfer coefficient estimated by CFD simulation is consistently larger than the calculated one by the method using dissociation...... constant and Henry's constant models. In addition, the results show that the liquid-air temperature difference has little impact on the simulated mass transfer coefficient by CFD modeling, whereas the mass transfer coefficient increases with higher liquid temperature using the other method under...... the conditions that the liquid temperature is lower than the air temperature. Although there are differences of mass transfer coefficients between these two methods, the mass transfer coefficients determined by these two methods are significantly related....
Directory of Open Access Journals (Sweden)
Bunyakan, C.
2002-04-01
Full Text Available Volatile organic compounds (VOCs have been found in wastewater of many chemical industries. Evaporation of VOCs from open water basin in waste treatment facilities causes air-pollution and has been regulated in many countries. Reduction or prevention of VOCs evaporation from open water basin is then necessary. The aim of this research was to investigate the influence of surface film generated by an insoluble surfactant on the mass transfer coefficient of VOCs evaporating from water. Hexadecanol and octadecanol were used as surfactant in this investigation with the amount in the range of 0 to 35 μg/cm2 and 0 to 25 μg/cm2, respectively. The VOCs used in this study were methanol, acetone, methyl ethyl ketone and toluene. The experimental results showed that the surfactant film can reduce the gas film and liquid coefficients by 56 and 80 %, respectively. The suitable amounts of the surfactant were 25 μg/cm2 for hexadecanol and 15 μg/cm2 for octadecanol. From this investigation we can conclude that covering the water surface with a film of hexadecanol or octadecanol could significantly reduce the VOCs evaporation rate.Finally, the empirical equations correlating gas film and liquid film coefficient to amount of surfactants were developed and verified against the experimental data. The predicted values of the overall mass transfer coefficients, obtained by using these empirical equations, were in good agreement with the measured values. Thus the empirical equations of mass transfer coefficients developed in this work can be used to predict the evaporation rates of VOCs from water surface covered by hexadecanol or octadecanol film.
Surov, Alexey; Meyer, Hans Jonas; Wienke, Andreas
2017-07-01
Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique based on measure of water diffusion that can provide information about tissue microstructure, especially about cell count. Increase of cell density induces restriction of water diffusion and decreases apparent diffusion coefficient (ADC). ADC can be divided into three sub-parameters: ADC minimum or ADC min , mean ADC or ADC mean and ADC maximum or ADC max Some studies have suggested that ADC min shows stronger correlations with cell count in comparison to other ADC fractions and may be used as a parameter for estimation of tumor cellularity. The aim of the present meta-analysis was to summarize correlation coefficients between ADC min and cellularity in different tumors based on large patient data. For this analysis, MEDLINE database was screened for associations between ADC and cell count in different tumors up to September 2016. For this work, only data regarding ADC min were included. Overall, 12 publications with 317 patients were identified. Spearman's correlation coefficient was used to analyze associations between ADC min and cellularity. The reported Pearson correlation coefficients in some publications were converted into Spearman correlation coefficients. The pooled correlation coefficient for all included studies was ρ=-0.59 (95% confidence interval (CI)=-0.72 to -0.45), heterogeneity Tau 2 =0.04 (pcorrelated moderately with tumor cellularity. The calculated correlation coefficient is not stronger in comparison to the reported coefficient for ADC mean and, therefore, ADC min does not represent a better means to reflect cellularity. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
Determination of heat transfer coefficients in plastic French straws plunged in liquid nitrogen.
Santos, M Victoria; Sansinena, M; Chirife, J; Zaritzky, N
2014-12-01
The knowledge of the thermodynamic process during the cooling of reproductive biological systems is important to assess and optimize the cryopreservation procedures. The time-temperature curve of a sample immersed in liquid nitrogen enables the calculation of cooling rates and helps to determine whether it is vitrified or undergoes phase change transition. When dealing with cryogenic liquids, the temperature difference between the solid and the sample is high enough to cause boiling of the liquid, and the sample can undergo different regimes such as film and/or nucleate pool boiling. In the present work, the surface heat transfer coefficients (h) for plastic French straws plunged in liquid nitrogen were determined using the measurement of time-temperature curves. When straws filled with ice were used the cooling curve showed an abrupt slope change which was attributed to the transition of film into nucleate pool boiling regime. The h value that fitted each stage of the cooling process was calculated using a numerical finite element program that solves the heat transfer partial differential equation under transient conditions. In the cooling process corresponding to film boiling regime, the h that best fitted experimental results was h=148.12±5.4 W/m(2) K and for nucleate-boiling h=1355±51 W/m(2) K. These values were further validated by predicting the time-temperature curve for French straws filled with a biological fluid system (bovine semen-extender) which undergoes freezing. Good agreement was obtained between the experimental and predicted temperature profiles, further confirming the accuracy of the h values previously determined for the ice-filled straw. These coefficients were corroborated using literature correlations. The determination of the boiling regimes that govern the cooling process when plunging straws in liquid nitrogen constitutes an important issue when trying to optimize cryopreservation procedures. Furthermore, this information can lead to
Soil plant transfer coefficient of 14C-carbofuran in brassica sp. vegetable agroecosystem
International Nuclear Information System (INIS)
Nashriyah Mat; Mazleha Maskin; Kubiak, R.
2006-01-01
The soil plant transfer coefficient or f factor of 14 C-carbofuran pesticide was studied in outdoor lysimeter experiment consisting of Brassica sp. vegetable crop, riverine alluvial clayey soil and Bungor series sandy loam soil. Soil transfer coefficients at 0-10 cm soil depth were 4.38 ± 0.30, 5.76 ± 1.04, 0.99 ± 0.25 and 2.66 ± 0.71; from IX recommended application rate in alluvial soil, 2X recommended application rate in alluvial soil, IX recommended application rate in Bungor soil and 2X recommended application rate in Bungor soil, respectively. At 0-25 cm soil depth, soil plant transfer coefficients were 8.96 ± 0.91, 10.40 ± 2.63, 2.34 ± 0.68 and 619 ±1.40, from IX recommended application rate in alluvial soil, 2X recommended application rate in alluvial soil, IX recommended application rate in Bungor soil and 2X recommended application rate in Bungor soil, respectively. At 77 days after treatment (DAT), the soil plant transfer coefficient was significantly higher in riverine alluvial soil than Bungor soil whereas shoot and root growth was significantly higher in Bungor soil than in riverine alluvial soil. At both 0-10 cm Brassica sp. rooting depth and 0-25 cm soil depth, the soil plant transfer coefficient was significantly higher in 2X recommended application rate of 14 C-carbofuran as compared to IX recommended application rate, in both Bungor and riverine alluvial soils. (Author)
Freche, John C; Schum, Eugene F
1951-01-01
Blade-to-coolant convective heat-transfer coefficients were obtained on a forced-convection water-cooled single-stage turbine over a large laminar flow range and over a portion of the transition range between laminar and turbulent flow. The convective coefficients were correlated by the general relation for forced-convection heat transfer with laminar flow. Natural-convection heat transfer was negligible for this turbine over the Grashof number range investigated. Comparison of turbine data with stationary tube data for the laminar flow of heated liquids showed good agreement. Calculated average midspan blade temperatures using theoretical gas-to-blade coefficients and blade-to-coolant coefficients from stationary-tube data resulted in close agreement with experimental data.
New Correlation Methods of Evaporation Heat Transfer in Horizontal Microfine Tubes
Makishi, Osamu; Honda, Hiroshi
A stratified flow model and an annular flow model of evaporation heat transfer in horizontal microfin tubes have been proposed. In the stratified flow model, the contributions of thin film evaporation and nucleate boiling in the groove above a stratified liquid were predicted by a previously reported numerical analysis and a newly developed correlation, respectively. The contributions of nucleate boiling and forced convection in the stratified liquid region were predicted by the new correlation and the Carnavos equation, respectively. In the annular flow model, the contributions of nucleate boiling and forced convection were predicted by the new correlation and the Carnavos equation in which the equivalent Reynolds number was introduced, respectively. A flow pattern transition criterion proposed by Kattan et al. was incorporated to predict the circumferential average heat transfer coefficient in the intermediate region by use of the two models. The predictions of the heat transfer coefficient compared well with available experimental data for ten tubes and four refrigerants.
Quantifying the range of cross-correlated fluctuations using a q- L dependent AHXA coefficient
Wang, Fang; Wang, Lin; Chen, Yuming
2018-03-01
Recently, based on analogous height cross-correlation analysis (AHXA), a cross-correlation coefficient ρ×(L) has been proposed to quantify the levels of cross-correlation on different temporal scales for bivariate series. A limitation of this coefficient is that it cannot capture the full information of cross-correlations on amplitude of fluctuations. In fact, it only detects the cross-correlation at a specific order fluctuation, which might neglect some important information inherited from other order fluctuations. To overcome this disadvantage, in this work, based on the scaling of the qth order covariance and time delay L, we define a two-parameter dependent cross-correlation coefficient ρq(L) to detect and quantify the range and level of cross-correlations. This new version of ρq(L) coefficient leads to the formation of a ρq(L) surface, which not only is able to quantify the level of cross-correlations, but also allows us to identify the range of fluctuation amplitudes that are correlated in two given signals. Applications to the classical ARFIMA models and the binomial multifractal series illustrate the feasibility of this new coefficient ρq(L) . In addition, a statistical test is proposed to quantify the existence of cross-correlations between two given series. Applying our method to the real life empirical data from the 1999-2000 California electricity market, we find that the California power crisis in 2000 destroys the cross-correlation between the price and the load series but does not affect the correlation of the load series during and before the crisis.
International Nuclear Information System (INIS)
Kang, Myeong Gie
2012-01-01
It is important to find a way of enhancing heat transfer coefficients if the space for heat exchanger installation is limited, as it is in advanced light water reactors. One of the effective methods to increase heat transfer coefficients ( h b ) of pool boiling is to consider a confined space. It is well known from the literature that the confined boiling is an effective technique to enhance heat transfer. Once the flow inlet at the tube bottom is closed, a very rapid increase in heat transfer coefficient is observed at low heat fluxes ( q ' ). The similar tendency is observed regardless of the geometric shape. Yao and Chang and Kang investigated a vertical annulus while Rops et al. investigated a confined plate. Fujita et al., in other wise, used parallel plates with side and bottom inflow is restricted. Around the upper region of the annulus with closed bottoms the downward liquid interrupts the upward movement of the bubble slugs. Thereafter, bubbles are coalescing into much bigger bubbles while fluctuating up and down in the annular space. As the heat flux increases (1) the isolate bubble region, (2) the coalesced big size bubble region, and (3) the dryout region is observed in series. The major causes of the heat transfer enhancement are related with the liquid film evaporation and active liquid agitation. Literature review on the previous studies about crevice effects on pool boiling denotes that heat transfer is highly dependent on the geometric parameters. Therefore, it is necessary to quantify the effect of each geometric parameter to estimate heat transfer coefficients accurately. Although some correlations were developed to predict pool boiling heat transfer in confined spaces based on open bottoms, the application of them to a confined space with closed bottoms could result in much error. To overcome the limits of the published correlations, Kang developed a correlation to predict pool boiling heat transfer in annuli with closed bottoms. However, the
Wavelet based correlation coefficient of time series of Saudi Meteorological Data
International Nuclear Information System (INIS)
Rehman, S.; Siddiqi, A.H.
2009-01-01
In this paper, wavelet concepts are used to study a correlation between pairs of time series of meteorological parameters such as pressure, temperature, rainfall, relative humidity and wind speed. The study utilized the daily average values of meteorological parameters of nine meteorological stations of Saudi Arabia located at different strategic locations. The data used in this study cover a period of 16 years between 1990 and 2005. Besides obtaining wavelet spectra, we also computed the wavelet correlation coefficients between two same parameters from two different locations and show that strong correlation or strong anti-correlation depends on scale. The cross-correlation coefficients of meteorological parameters between two stations were also calculated using statistical function. For coastal to costal pair of stations, pressure time series was found to be strongly correlated. In general, the temperature data were found to be strongly correlated for all pairs of stations and the rainfall data the least.
Efficiency analysis of straight fin with variable heat transfer coefficient and thermal conductivity
International Nuclear Information System (INIS)
Sadri, Somayyeh; Raveshi, Mohammad Reza; Amiri, Shayan
2012-01-01
In this study, one type of applicable analytical method, differential transformation method (DTM), is used to evaluate the efficiency and behavior of a straight fin with variable thermal conductivity and heat transfer coefficient. Fins are widely used to enhance heat transfer between primary surface and the environment in many industrial applications. The performance of such a surface is significantly affected by variable thermal conductivity and heat transfer coefficient, particularly for large temperature differences. General heat transfer equation related to the fin is derived and dimensionalized. The concept of differential transformation is briefly introduced, and then this method is employed to derive solutions of nonlinear equations. Results are evaluated for several cases such as: laminar film boiling or condensation, forced convection, laminar natural convection, turbulent natural convection, nucleate boiling, and radiation. The obtained results from DTM are compared with the numerical solution to verify the accuracy of the proposed method. The effects of design parameters on temperature and efficiency are evaluated by some figures. The major aim of the present study, which is exclusive for this article, is to find the effect of the modes of heat transfer on fin efficiency. It has been shown that for radiation heat transfer, thermal efficiency reaches its maximum value
Heat transfer coefficient: Medivance Arctic Sun Temperature Management System vs. water immersion.
English, M J; Hemmerling, T M
2008-07-01
To improve heat transfer, the Medivance Arctic Sun Temperature Management System (Medivance, Inc., Louisville, CO, USA) features an adhesive, water-conditioned, highly conductive hydrogel pad for intimate skin contact. This study measured and compared the heat transfer coefficient (h), i.e. heat transfer efficiency, of this pad (hPAD), in a heated model and in nine volunteers' thighs; and of 10 degrees C water (hWATER) in 33 head-out immersions by 11 volunteers. Volunteer studies had ethical approval and written informed consent. Calibrated heat flux transducers measured heat flux (W m-2). Temperature gradient (DeltaT) was measured between skin and pad or water temperatures. Temperature gradient was changed through the pad's water temperature controller or by skin cooling on immersion. The heat transfer coefficient is the slope of W m-2/DeltaT: its unit is W m-2 degrees C-1. Average with (95% CI) was: model, hPAD = 110.4 (107.8-113.1), R2 = 0.99, n = 45; volunteers, hPAD = 109.8 (95.5-124.1), R2 = 0.83, n = 51; and water immersion, hWATER = 107.1 (98.1-116), R2 = 0.86, n = 94. The heat transfer coefficient for the pad was the same in the model and volunteers, and equivalent to hWATER. Therefore, for the same DeltaT and heat transfer area, the Arctic Sun's heat transfer rate would equal water immersion. This has important implications for body cooling/rewarming rates.
Determination of the heat transfer coefficient from IRT measurement data using the Trefftz method
Directory of Open Access Journals (Sweden)
Maciejewska Beata
2016-01-01
Full Text Available The paper presents the method of heat transfer coefficient determination for boiling research during FC-72 flow in the minichannels, each 1.7 mm deep, 24 mm wide and 360 mm long. The heating element was the thin foil, enhanced on the side which comes into contact with fluid in the minichannels. Local values of the heat transfer coefficient were calculated from the Robin boundary condition. The foil temperature distribution and the derivative of the foil temperature were obtained by solving the two-dimensional inverse heat conduction problem, due to measurements obtained by IRT. Calculations was carried out by the method based on the approximation of the solution of the problem using a linear combination of Trefftz functions. The basic property of this functions is they satisfy the governing equation. Unknown coefficients of linear combination of Trefftz functions are calculated from the minimization of the functional that expresses the mean square error of the approximate solution on the boundary. The results presented as IR thermographs, two-phase flow structure images and the heat transfer coefficient as a function of the distance from the channel inlet, were analyzed.
Determination of drying kinetics and convective heat transfer coefficients of ginger slices
Akpinar, Ebru Kavak; Toraman, Seda
2016-10-01
In the present work, the effects of some parametric values on convective heat transfer coefficients and the thin layer drying process of ginger slices were investigated. Drying was done in the laboratory by using cyclone type convective dryer. The drying air temperature was varied as 40, 50, 60 and 70 °C and the air velocity is 0.8, 1.5 and 3 m/s. All drying experiments had only falling rate period. The drying data were fitted to the twelve mathematical models and performance of these models was investigated by comparing the determination of coefficient ( R 2), reduced Chi-square ( χ 2) and root mean square error between the observed and predicted moisture ratios. The effective moisture diffusivity and activation energy were calculated using an infinite series solution of Fick's diffusion equation. The average effective moisture diffusivity values and activation energy values varied from 2.807 × 10-10 to 6.977 × 10-10 m2/s and 19.313-22.722 kJ/mol over the drying air temperature and velocity range, respectively. Experimental data was used to evaluate the values of constants in Nusselt number expression by using linear regression analysis and consequently, convective heat transfer coefficients were determined in forced convection mode. Convective heat transfer coefficient of ginger slices showed changes in ranges 0.33-2.11 W/m2 °C.
Sample size for estimation of the Pearson correlation coefficient in cherry tomato tests
Directory of Open Access Journals (Sweden)
Bruno Giacomini Sari
2017-09-01
Full Text Available ABSTRACT: The aim of this study was to determine the required sample size for estimation of the Pearson coefficient of correlation between cherry tomato variables. Two uniformity tests were set up in a protected environment in the spring/summer of 2014. The observed variables in each plant were mean fruit length, mean fruit width, mean fruit weight, number of bunches, number of fruits per bunch, number of fruits, and total weight of fruits, with calculation of the Pearson correlation matrix between them. Sixty eight sample sizes were planned for one greenhouse and 48 for another, with the initial sample size of 10 plants, and the others were obtained by adding five plants. For each planned sample size, 3000 estimates of the Pearson correlation coefficient were obtained through bootstrap re-samplings with replacement. The sample size for each correlation coefficient was determined when the 95% confidence interval amplitude value was less than or equal to 0.4. Obtaining estimates of the Pearson correlation coefficient with high precision is difficult for parameters with a weak linear relation. Accordingly, a larger sample size is necessary to estimate them. Linear relations involving variables dealing with size and number of fruits per plant have less precision. To estimate the coefficient of correlation between productivity variables of cherry tomato, with a confidence interval of 95% equal to 0.4, it is necessary to sample 275 plants in a 250m² greenhouse, and 200 plants in a 200m² greenhouse.
DEFF Research Database (Denmark)
Tatomirescu, Alexandru; Buskgaard, Emil Feldborg; Pedersen, Gert Frølund
2014-01-01
. The MIMO performance is investigated in two different channel models through efficiency, branch power imbalance and envelope correlation. The proposed antennas have acceptable levels of isolation between them, even in the low-bands, while having a good efficiency. Furthermore, the correlation coefficient...
Reducing Bias and Error in the Correlation Coefficient Due to Nonnormality
Bishara, Anthony J.; Hittner, James B.
2015-01-01
It is more common for educational and psychological data to be nonnormal than to be approximately normal. This tendency may lead to bias and error in point estimates of the Pearson correlation coefficient. In a series of Monte Carlo simulations, the Pearson correlation was examined under conditions of normal and nonnormal data, and it was compared…
International Nuclear Information System (INIS)
Pathak, R.K.
1985-01-01
Statistical electron angular correlation coefficients tau = 2 2 He through 14 Si, within the Hohenberg-Kohn-Sham density-functional formalism. These are computed with use of the spectral sum rules obtained from the pseudoexcitation spectrum employing the recent formulation of the time-dependent Kohn-Sham theory due to Bartolotti. Various approximations to the exchange-correlation energy functional are used and for first-row atoms, a comparison is made with the highly accurate correlation coefficients recently obtained by Thakkar. The present tau values show closer agreement with those of Thakkar with increasing number of electrons
Cohen, S. C.
1980-01-01
A technique for fitting a straight line to a collection of data points is given. The relationships between the slopes and correlation coefficients, and between the corresponding standard deviations and correlation coefficient are given.
Toropov, Andrey A; Toropova, Alla P; Raska, Ivan; Benfenati, Emilio
2010-04-01
Three different splits into the subtraining set (n = 22), the set of calibration (n = 21), and the test set (n = 12) of 55 antineoplastic agents have been examined. By the correlation balance of SMILES-based optimal descriptors quite satisfactory models for the octanol/water partition coefficient have been obtained on all three splits. The correlation balance is the optimization of a one-variable model with a target function that provides both the maximal values of the correlation coefficient for the subtraining and calibration set and the minimum of the difference between the above-mentioned correlation coefficients. Thus, the calibration set is a preliminary test set. Copyright (c) 2009 Elsevier Masson SAS. All rights reserved.
International Nuclear Information System (INIS)
Bonneton, Michel.
1980-02-01
The main correlations likely to be suitable for describing heat transfers between the fluid and wall during decompression are analyzed. The most important experimental work on the boiling crisis in the transient regime is presented. Experimental studies are then treated. The test installation (OMEGA experiment), the instumentation used and the experiments realized are described. The purpose of these experiments was to establish heat exchange laws for decompression conditions. Local and instantaneous exchange coefficients were determined in a heated test section together with the thermohydraulic parameters of the flow. The methods used to investigate the measurements made and to analyze their validity are described. Finally, the test results are presented and discussed. It is shown that under certain conditions, the boiling crisis can be determined with a permanent regime correlation. An attempt is made to establish a correlation for the transition boiling zone from these results. A test reconstitution calculation based on a two-fluid model is presented [fr
Energy Technology Data Exchange (ETDEWEB)
Choi, Dong jae; Jang, Yeong jun; Lee, Yeon-Gun [Jeju National University, Jeju (Korea, Republic of); Kim, Sin [Chung-Ang University, Seoul (Korea, Republic of)
2015-10-15
The Passive Containment Cooling System (PCCS) to be introduced in advanced LWRs removes released energy to an external heat sink by a naturally driven flow. Containment through the condensation heat transfer phenomenon in the event of the loss of coolant accident (LOCA) or main steam line break (MSLB). As the released steam pressurizes the containment, the PCCS will activate to transport the decay heat In this study, a numerical analysis of the condensation heat transfer coefficients on the PCCS condenser tube is conducted using the MARS-KS code. The condensation heat transfer coefficients are obtained from JNU condensation tests performed on a 1000 long and 40 mm O.D. tube. The analysis condition covers 2 and 4 bar for the air mass fraction ranging from 0.1 to 0.8. The JNU single vertical condensation experimental results, Uchida's and Dehbi's correlation compared with the MARS-KS code's results at 2 and 4 bar. Experimental results and MARS-KS predicted heat transfer coefficient is different from the thermal resistances and Wall subcooling. An average relative error is 18.8% and 15% at 2 and 4 bar, respectively. Uchida's correlation is considered the noncondensable gas mass fraction only. Therefore, that is lower than MARS-KS results at 4 bar. Dehbi's correlation affected by ratio of the height-to-diameter, so its results are higher condensation heat transfer coefficient than MARS-KS predicted results.
Directory of Open Access Journals (Sweden)
Guo Zerong
2016-01-01
Full Text Available To study the effect of variable heat transfer coefficient of fireworks and crackers on thermal explosion critical ambient temperature and time to ignition, considering the heat transfer coefficient as the power function of temperature, mathematical thermal explosion steady state and unsteady-state model of finite cylindrical fireworks and crackers with complex shell structures are established based on two-dimensional steady state thermal explosion theory. The influence of variable heat transfer coefficient on thermal explosion critical ambient temperature and time to ignition are analyzed. When heat transfer coefficient is changing with temperature and in the condition of natural convection heat transfer, critical ambient temperature lessen, thermal explosion time to ignition shorten. If ambient temperature is close to critical ambient temperature, the influence of variable heat transfer coefficient on time to ignition become large. For firework with inner barrel in example analysis, the critical ambient temperature of propellant is 463.88 K and the time to ignition is 4054.9s at 466 K, 0.26 K and 450.8s less than without considering the change of heat transfer coefficient respectively. The calculation results show that the influence of variable heat transfer coefficient on thermal explosion time to ignition is greater in this example. Therefore, the effect of variable heat transfer coefficient should be considered into thermal safety evaluation of fireworks to reduce potential safety hazard.
International Nuclear Information System (INIS)
Huh, Seon Jeong; Lee, Hee Joon; Moon, Joo Hyung; Bae, Youngmin; Kim, Young In
2017-01-01
For the design purpose of air-cooled condensing heat exchanger of emergency cooldown tank, average condensation heat transfer coefficient inside a circular tube was reduced by a thermal sizing program using the experimental data of Kim et al. It was compared to the existing condensation heat transfer correlations. Moreover, a sensitivity analysis of both inside condensation and outside air natural convection correlations was performed. Although condensation heat transfer did not play a great role to design over 10 3 W/m 2 /K, the improved Shah's correlation gives the best prediction for the design. Consequently, air natural convection coefficient significantly affects the design of air-cooled condensing heat exchanger. (author)
International Nuclear Information System (INIS)
Wang, L.; Feng, S.
1989-01-01
The relation between the reflection coefficients and the Green's function for a coherent wave propagation in a disordered elastic-scattering medium is derived. The sum rule of the reflection and transmission coefficients corresponding to probability conservation is shown rigorously for an arbitrary scattering potential. The correlation function of the reflection coefficients is then calculated by using a Feynman-diagrammatic approach in the weak-localized multiple-scattering regime (L much-gt l much-gt λ). The result is in agreement with recent experiments on the so-called ''memory effect'' in reflection coefficients. A more general condition under which the memory effect can occur is derived. Differences between the the correlation functions for reflection and that for transmission are discussed
Energy Technology Data Exchange (ETDEWEB)
Biyikli, Suleyman [Okan University Tuzla Kampusu, Faculty of Engineering and Architecture (Turkey)], email: suleyman.biyikli@okan.edu.tr
2011-07-01
This article investigates the heat transfer characteristics for horizontal tubes in a freeboard region of high temperature fluidized beds. The freeboard entrainment heights are calculated by using empirical correlations described in detail and used in estimating the heat transfer coefficients from a horizontal tube occurring by radiation, gas convection, and particle contact mechanisms in high temperature a fluidized bed combustor. The total average of these coefficients around a horizontal tube carrying water in high temperature fluidized beds can be written as the sum of convective, radiative, and fluidized-particle contact heat transfer coefficients and these correlations are tested against certain published experimental measurements. In full agreement with this data, it was observed that the calculated heat transfer coefficients increased with increasing gas velocity at a given tube elevation and they decreased and approached the values of single-phase gas convection and radiation with increasing tube elevation in the freeboard region while the relative contribution of radiation increases and approaches a constant fraction of total heat transfer.
Mass Transfer Coefficients and Bubble Sizes in Oxidative Ladle Refining of Silicon
Bjørnstad, Erlend Lunnan
2016-01-01
The mass transfer of [Al] and [Ca] between three synthetic SiO_{2}-CaO-Al_{2}O_{3} slags, and 8N silicon, has been investigated to find the overall mass transfer coefficient k_{i,t} for the individual species. Samples were kept at 1873K for 5, 10, 20, 30 and 180min before quenching. The metal phase was later analyzed by ICP-MS to view how the concentrations of impurities change with respect to time. This work then compares these results to industrial data gathered from ladles used for oxidati...
Identification of the Heat Transfer Coefficient at the Charge Surface Heated on the Chamber Furnace
Directory of Open Access Journals (Sweden)
Gołdasz A.
2017-06-01
Full Text Available The inverse method was applied to determine the heat flux reaching the charge surface. The inverse solution was based upon finding the minimum of the error norm between the measured and calculated temperatures. The charge temperature field was calculated with the finite element method by solving the heat transfer equation for a square charge made of 15HM steel heated on all its surfaces. On the basis of the mean value of heat flux, the value of the heat transfer coefficient at each surface was determined depending on the surface temperature of the material heated.
Directory of Open Access Journals (Sweden)
Shumanova M.V.
2015-03-01
Full Text Available The process fish salting has been studied by the method of photon correlation spectroscopy; the distribution of salt concentration in the solution and herring flesh with skin has been found, diffusion coefficients and salt concentrations used for creating a mathematical model of the salting technology have been worked out; the possibility of determination by this method the coefficient of dynamic viscosity of solutions and different media (minced meat etc. has been considered
DEFF Research Database (Denmark)
Boesen, Lars; Chabanova, Elizaveta; Løgager, Vibeke
2015-01-01
PURPOSE: To evaluate the correlation between apparent diffusion coefficient measurements (ADCtumor and ADCratio ) and the Gleason score from radical prostatectomy specimens. MATERIALS AND METHODS: Seventy-one patients with clinically localized prostate cancer scheduled for radical prostatectomy...... correlated with the Gleason score from the prostatectomy specimens. RESULTS: The association between ADC measurements and Gleason score showed a significant negative correlation (P ... ) and 0.90 (ADCratio ) when discriminating Gleason score ≤7(3+4) from Gleason score ≥7(4+3). CONCLUSION: ADC measurements showed a significant correlation with tumor Gleason score at final pathology. The ADCratio demonstrated the best correlation compared to the ADCtumor value and radically improved...
Gas-liquid mass transfer coefficient of methane in bubble column reactor
Energy Technology Data Exchange (ETDEWEB)
Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik [Sogang University, Seoul (Korea, Republic of); Yasin, Muhammad; Park, Shinyoung; Chang, In Seop [Gwangju Institute of Science and Technology (GIST), Gwangju (Korea, Republic of); Lee, Eun Yeol [Kyung Hee University, Yongin (Korea, Republic of)
2015-06-15
Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k{sub L}a). The feasibility of the new reactor was demonstrated by measuring k{sub L}a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k{sub L}a value of 102.9 h{sup -1} was obtained.
Gas-liquid mass transfer coefficient of methane in bubble column reactor
International Nuclear Information System (INIS)
Lee, Jaewon; Ha, Kyoung-Su; Lee, Jinwon; Kim, Choongik; Yasin, Muhammad; Park, Shinyoung; Chang, In Seop; Lee, Eun Yeol
2015-01-01
Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k L a). The feasibility of the new reactor was demonstrated by measuring k L a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k L a value of 102.9 h -1 was obtained
Calculating the heat transfer coefficient of frame profiles with internal cavities
DEFF Research Database (Denmark)
Noyé, Peter Anders; Laustsen, Jacob Birck; Svendsen, Svend
2004-01-01
. The heat transfer coefficient is determined by two-dimensional numerical calculations and by measurements. Calculations are performed in Therm (LBNL (2001)), which is developed at Lawrence Berkeley National Laboratory, USA. The calculations are performed in accordance with the future European standards...... correspondence between measured and calculated values. Hence, when determining the heat transfer coefficient of frame profiles with internal cavities by calculations, it is necessary to apply a more detailed radiation exchange model than described in the prEN ISO 10077-2 standard. The ISO-standard offers......Determining the energy performance of windows requires detailed knowledge of the thermal properties of their different elements. A series of standards and guidelines exist in this area. The thermal properties of the frame can be determined either by detailed two-dimensional numerical methods...
Determination of heat transfer coefficient for an interaction of sub-cooled gas and metal
International Nuclear Information System (INIS)
Sidek, Mohd Zaidi; Kamarudin, Muhammad Syahidan
2016-01-01
Heat transfer coefficient (HTC) for a hot metal surface and their surrounding is one of the need be defined parameter in hot forming process. This study has been conducted to determine the HTC for an interaction between sub-cooled gas sprayed on a hot metal surface. Both experiments and finite element have been adopted in this work. Initially, the designated experiment was conducted to obtain temperature history of spray cooling process. Then, an inverse method was adopted to calculate the HTC value before we validate in a finite element simulation model. The result shows that the heat transfer coefficient for interaction of subcooled gas and hot metal surface is 1000 W/m 2 K. (paper)
International Nuclear Information System (INIS)
Mehrabian, M. A.; Mansouri, S. H.; Sheikhzadeh, G. A.
2002-01-01
The single-phase flow and thermal performance of a double pipe heat exchanger are examined by experimental methods. The working fluid is water at atmospheric pressure. Temperature measurements at the inlet and outlet of the two streams and also at an intermediate point half way between the inlet and outlet is made, using copper-constantan thermocouple wires. Mass flow rates for each stream are also measured using calibrated ratemeters. Heat is supplied to the inner tube stream by an immersion heater. The overall heat transfer coefficients are inferred from the measured data. The heat transfer coefficient of the inner tube flow (circular cross section) is calculated using the standard correlations. The heat transfer coefficient of the outer tube flow (annular cross section) is then deduced.Higher heat transfer coefficients are reported in the laminar flow regime in comparison to the predictions of standard correlations for straight and smooth tubes. The reasons for this discrepancy are identified and discussed. Experimental errors in measuring temperatures and mass flow rates are studied and their effects on the heat transfer coefficients are estimated. Experimental results for the range of operating conditions used in this work show that the outer tube side heat transfer coefficients are smaller than the inner side heat transfer coefficients by a factor of almost 1.5 and 3.4 in counter flow and parallel flow arrangements, respectively. The agreement with predictions is very good for the counter flow arrangement, but not very good for the parallel flow arrangement
DEFF Research Database (Denmark)
Steskens, Paul Wilhelmus Maria Hermanus; Janssen, Hans; Rode, Carsten
2009-01-01
Current models to predict heat, air and moisture (HAM) conditions in buildings assume constant boundary conditions for the temperature and relative humidity of the neighbouring air and for the surface heat and moisture transfer coefficients. These assumptions may introduce errors in the predicted...... influence on the predicted hygrothermal conditions at the surface of a building component and on the heat and vapour exchange with the indoor environment....
Liu, An-Nuo; Wang, Lu-Lu; Li, Hui-Ping; Gong, Juan; Liu, Xiao-Hong
2017-05-01
The literature on posttraumatic growth (PTG) is burgeoning, with the inconsistencies in the literature of the relationship between PTG and posttraumatic stress disorder (PTSD) symptoms becoming a focal point of attention. Thus, this meta-analysis aims to explore the relationship between PTG and PTSD symptoms through the Pearson correlation coefficient. A systematic search of the literature from January 1996 to November 2015 was completed. We retrieved reports on 63 studies that involved 26,951 patients. The weighted correlation coefficient revealed an effect size of 0.22 with a 95% confidence interval of 0.18 to 0.25. Meta-analysis provides evidence that PTG may be positively correlated with PTSD symptoms and that this correlation may be modified by age, trauma type, and time since trauma. Accordingly, people with high levels of PTG should not be ignored, but rather, they should continue to receive help to alleviate their PTSD symptoms.
Xu, Jiucheng; Mu, Huiyu; Wang, Yun; Huang, Fangzhou
2018-01-01
The selection of feature genes with high recognition ability from the gene expression profiles has gained great significance in biology. However, most of the existing methods have a high time complexity and poor classification performance. Motivated by this, an effective feature selection method, called supervised locally linear embedding and Spearman's rank correlation coefficient (SLLE-SC 2 ), is proposed which is based on the concept of locally linear embedding and correlation coefficient algorithms. Supervised locally linear embedding takes into account class label information and improves the classification performance. Furthermore, Spearman's rank correlation coefficient is used to remove the coexpression genes. The experiment results obtained on four public tumor microarray datasets illustrate that our method is valid and feasible.
International Nuclear Information System (INIS)
Prasad, Mahendra; Gaikwad, Avinash J.; Sridharan, Arunkumar; Parida, Smrutiranjan
2015-01-01
The flow of fluid in pipes cause corrosion wherein the inner surface of pipe becomes progressively thinner and susceptible to failure. This form of corrosion dependent on flow dynamics is called Flow Accelerated Corrosion (FAC) and has been observed in Nuclear Power Plants (NPPs). Mass transfer coefficient (MTC) is related to extent of wall thinning and it changes from its value in a straight pipe (with same fluid parameters) for flow in orifices, bends, junctions etc. due to gross disturbance of the velocity profile. This paper presents two-dimensional computational fluid dynamics (CFD) simulations for an orifice configuration in a straight pipe. Turbulent model K- ω with shear stress transport and transition flow was the model used for simulation studies. The mass transfer boundary layer (MTBL) thickness δ mtbl is related to the Schmidt number (Sc) and hydrodynamic boundary layer thickness δ h , as δ mtbl ~ δh/(Sc 1/3 ). MTBL is significantly smaller than δ h and hence boundary layer meshing was carried out deep into δ mtbl . Uniform velocity profile was applied at the inlet. Post orifice fluid shows large recirculating flows on the upper and lower wall. At various locations after orifice, mass transfer coefficient is calculated and compared with the value in straight pipe with fully developed turbulent flow. The MTC due to the orifice increases and it is correlated with enhanced FAC in region after orifice. (author)
Evaluation of heat transfer coefficient of tungsten filaments at low pressures and high temperatures
International Nuclear Information System (INIS)
Chondrakis, N.G.; Topalis, F.V.
2011-01-01
The paper presents an experimental method for the evaluation of the heat transfer coefficient of tungsten filaments at low pressures and high temperatures. For this purpose an electrode of a T5 fluorescent lamp was tested under low pressures with simultaneous heating in order to simulate the starting conditions in the lamp. It was placed in a sealed vessel in which the pressure was varied from 1 kM (kilo micron) to 760 kM. The voltage applied to the electrode was in the order of the filament's voltage of the lamp at the normal operation with the ballast during the preheating process. The operating frequency ranged from DC to 50 kHz. The experiment targeted on estimating the temperature of the electrode at the end of the first and the ninth second after initiating the heating process. Next, the heat transfer coefficient was calculated at the specific experimental conditions. A mathematical model based on the results was developed that estimates the heat transfer coefficient. The experiments under different pressures confirm that the filament's temperature strongly depends on the pressure.
Fuel-clad heat transfer coefficient of a defected fuel rod
International Nuclear Information System (INIS)
Bruet, M.; Stora, J.P.
1976-01-01
A special rod has been built with a stack of UO 2 pellets inside a thick zircaloy clad. The atmosphere inside the fuel rod can be changed and particularly the introduction of water is possible. The capsule was inserted in the Siloe pool reactor in a special device equipped with a neutron flux monitor. The fuel centerline temperature and the temperature at a certain radius of the clad were recorded by two thermocouples. The temperature profiles in the fuel and in the cladding have been calculated and then the heat transfer coefficient. In order to check the proper functioning of the device, two runs were successively achieved with a helium atmosphere. Then the helium atmosphere inside the fuel rod was removed and replaced by water. The heat transfer coefficients derived from the measurements at low power level are in agreement with the values given by the model based on thermal conductivity. However, for higher power levels, the heat transfer coefficients become higher than those based on the calculated gap
International Nuclear Information System (INIS)
Robinson, J.A.; Windebank, S.R.
1988-01-01
Condensation heat transfer coefficients have been measured in a pressurised chamber containing a mixture of saturated steam and air. They were determined as a function of the air-steam ratio in nominally stagnant conditions. The effect of pressure is assessed and preliminary measurements with a forced convective component of velocity are presented. A novel measurement technique was adopted, namely to use a vertical heat pipe whose conductance could easily be varied. It transported heat from an evaporator located inside the chamber to a condenser section outside, at which the heat flow was measured. Heat flux at the evaporator could then be determined and a condensation heat transfer coefficient derived. The range of coefficients covered was from 150 W/m 2 0 K at high air-steam ratios to 20,000 W/m 2 0 K in pure steam. Results show that increasing either total pressure or velocity enhances condensation heat transfer over the range of air/steam ratios considered. (author)
Quantized correlation coefficient for measuring reproducibility of ChIP-chip data
Directory of Open Access Journals (Sweden)
Kuroda Mitzi I
2010-07-01
Full Text Available Abstract Background Chromatin immunoprecipitation followed by microarray hybridization (ChIP-chip is used to study protein-DNA interactions and histone modifications on a genome-scale. To ensure data quality, these experiments are usually performed in replicates, and a correlation coefficient between replicates is used often to assess reproducibility. However, the correlation coefficient can be misleading because it is affected not only by the reproducibility of the signal but also by the amount of binding signal present in the data. Results We develop the Quantized correlation coefficient (QCC that is much less dependent on the amount of signal. This involves discretization of data into set of quantiles (quantization, a merging procedure to group the background probes, and recalculation of the Pearson correlation coefficient. This procedure reduces the influence of the background noise on the statistic, which then properly focuses more on the reproducibility of the signal. The performance of this procedure is tested in both simulated and real ChIP-chip data. For replicates with different levels of enrichment over background and coverage, we find that QCC reflects reproducibility more accurately and is more robust than the standard Pearson or Spearman correlation coefficients. The quantization and the merging procedure can also suggest a proper quantile threshold for separating signal from background for further analysis. Conclusions To measure reproducibility of ChIP-chip data correctly, a correlation coefficient that is robust to the amount of signal present should be used. QCC is one such measure. The QCC statistic can also be applied in a variety of other contexts for measuring reproducibility, including analysis of array CGH data for DNA copy number and gene expression data.
Quantized correlation coefficient for measuring reproducibility of ChIP-chip data.
Peng, Shouyong; Kuroda, Mitzi I; Park, Peter J
2010-07-27
Chromatin immunoprecipitation followed by microarray hybridization (ChIP-chip) is used to study protein-DNA interactions and histone modifications on a genome-scale. To ensure data quality, these experiments are usually performed in replicates, and a correlation coefficient between replicates is used often to assess reproducibility. However, the correlation coefficient can be misleading because it is affected not only by the reproducibility of the signal but also by the amount of binding signal present in the data. We develop the Quantized correlation coefficient (QCC) that is much less dependent on the amount of signal. This involves discretization of data into set of quantiles (quantization), a merging procedure to group the background probes, and recalculation of the Pearson correlation coefficient. This procedure reduces the influence of the background noise on the statistic, which then properly focuses more on the reproducibility of the signal. The performance of this procedure is tested in both simulated and real ChIP-chip data. For replicates with different levels of enrichment over background and coverage, we find that QCC reflects reproducibility more accurately and is more robust than the standard Pearson or Spearman correlation coefficients. The quantization and the merging procedure can also suggest a proper quantile threshold for separating signal from background for further analysis. To measure reproducibility of ChIP-chip data correctly, a correlation coefficient that is robust to the amount of signal present should be used. QCC is one such measure. The QCC statistic can also be applied in a variety of other contexts for measuring reproducibility, including analysis of array CGH data for DNA copy number and gene expression data.
Yue, Chen; Chen, Shaojie; Sair, Haris I; Airan, Raag; Caffo, Brian S
2015-09-01
Data reproducibility is a critical issue in all scientific experiments. In this manuscript, the problem of quantifying the reproducibility of graphical measurements is considered. The image intra-class correlation coefficient (I2C2) is generalized and the graphical intra-class correlation coefficient (GICC) is proposed for such purpose. The concept for GICC is based on multivariate probit-linear mixed effect models. A Markov Chain Monte Carlo EM (mcm-cEM) algorithm is used for estimating the GICC. Simulation results with varied settings are demonstrated and our method is applied to the KIRBY21 test-retest dataset.
Choosing the best index for the average score intraclass correlation coefficient.
Shieh, Gwowen
2016-09-01
The intraclass correlation coefficient (ICC)(2) index from a one-way random effects model is widely used to describe the reliability of mean ratings in behavioral, educational, and psychological research. Despite its apparent utility, the essential property of ICC(2) as a point estimator of the average score intraclass correlation coefficient is seldom mentioned. This article considers several potential measures and compares their performance with ICC(2). Analytical derivations and numerical examinations are presented to assess the bias and mean square error of the alternative estimators. The results suggest that more advantageous indices can be recommended over ICC(2) for their theoretical implication and computational ease.
Mass transfer coefficient in ginger oil extraction by microwave hydrotropic solution
Handayani, Dwi; Ikhsan, Diyono; Yulianto, Mohamad Endy; Dwisukma, Mandy Ayulia
2015-12-01
This research aims to obtain mass transfer coefficient data on the extraction of ginger oil using microwave hydrotropic solvent as an alternative to increase zingiberene. The innovation of this study is extraction with microwave heater and hydrotropic solvent,which able to shift the phase equilibrium, and the increasing rate of the extraction process and to improve the content of ginger oil zingiberene. The experiment was conducted at the Laboratory of Separation Techniques at Chemical Engineering Department of Diponegoro University. The research activities carried out in two stages, namely experimental and modeling work. Preparation of the model postulated, then lowered to obtain equations that were tested and validated using data obtained from experimental. Measurement of experimental data was performed using microwave power (300 W), extraction temperature of 90 ° C and the independent variable, i.e.: type of hydrotropic, the volume of solvent and concentration in order, to obtain zingiberen levels as a function of time. Measured data was used as a tool to validate the postulation, in order to obtain validation of models and empirical equations. The results showed that the mass transfer coefficient (Kla) on zingiberene mass transfer models ginger oil extraction at various hydrotropic solution attained more 14 ± 2 Kla value than its reported on the extraction with electric heating. The larger value of Kla, the faster rate of mass transfer on the extraction process. To obtain the same yields, the microwave-assisted extraction required one twelfth time shorter.
Barlow, Andrew L; Macleod, Alasdair; Noppen, Samuel; Sanderson, Jeremy; Guérin, Christopher J
2010-12-01
One of the most routine uses of fluorescence microscopy is colocalization, i.e., the demonstration of a relationship between pairs of biological molecules. Frequently this is presented simplistically by the use of overlays of red and green images, with areas of yellow indicating colocalization of the molecules. Colocalization data are rarely quantified and can be misleading. Our results from both synthetic and biological datasets demonstrate that the generation of Pearson's correlation coefficient between pairs of images can overestimate positive correlation and fail to demonstrate negative correlation. We have demonstrated that the calculation of a thresholded Pearson's correlation coefficient using only intensity values over a determined threshold in both channels produces numerical values that more accurately describe both synthetic datasets and biological examples. Its use will bring clarity and accuracy to colocalization studies using fluorescent microscopy.
International Nuclear Information System (INIS)
Calvar, N.; Domínguez, Á.; Macedo, E.A.
2014-01-01
Graphical abstract: - Highlights: • Osmotic coefficients of alcohols with BMpyrDCA ionic liquid are determined. • Experimental data were correlated with Extended Pitzer model of Archer and MNRTL. • Mean molal activity coefficients and excess Gibbs free energies were calculated. • The results have been interpreted in terms of interactions. - Abstract: The vapour pressure osmometry technique (VPO) has been used to obtain the osmotic coefficients of the binary mixtures of the primary and secondary alcohols 1-propanol, 2-propanol, 1-butanol, 2-butanol and 1-pentanol with the ionic liquid 1-butyl-1-methylpyrrolidinium dicyanamide, BMpyrDCA. From these coefficients, the corresponding activity coefficients and vapour pressures of the mixtures have been also determined. The results have been discussed in terms of solute–solvent and ion–ion interactions and have been compared with those taken from literature in order to analyse the influence of the anion or cation constituting the ionic liquid. For the treatment of the experimental data, the Extended Pitzer model of Archer and the MNRTL model have been applied, obtaining standard deviations from the experimental osmotic coefficients lower than 0.015 and 0.065, respectively. From the parameters obtained with the Extended Pitzer model or Archer, the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures have been calculated
Pedretti, D.; Fernàndez-Garcia, D.; Sanchez-Vila, X.; Bolster, D.; Benson, D. A.
2014-02-01
Aquifer hydraulic properties such as hydraulic conductivity (K) are ubiquitously heterogeneous and typically only a statistical characterization can be sought. Additionally, statistical anisotropy at typical characterization scales is the rule. Thus, regardless of the processes governing solute transport at the local (pore) scale, transport becomes non-Fickian. Mass-transfer models provide an efficient tool that reproduces observed anomalous transport; in some cases though, these models lack predictability as model parameters cannot readily be connected to the physical properties of aquifers. In this study, we focus on a multirate mass-transfer model (MRMT), and in particular the apparent capacity coefficient (β), which is a strong indicator of the potential of immobile zones to capture moving solute. We aim to find if the choice of an apparent β can be phenomenologically related to measures of statistical anisotropy. We analyzed an ensemble of random simulations of three-dimensional log-transformed multi-Gaussian permeability fields with stationary anisotropic correlation under convergent flow conditions. It was found that apparent β also displays an anisotropic behavior, physically controlled by the aquifer directional connectivity, which in turn is controlled by the anisotropic correlation model. A high hydraulic connectivity results in large β values. These results provide new insights into the practical use of mass-transfer models for predictive purposes.
Directory of Open Access Journals (Sweden)
Serge B. Provost
2015-07-01
Full Text Available This paper provides a simplified representation of the exact density function of R, the sample correlation coefficient. The odd and even moments of R are also obtained in closed forms. Being expressed in terms of generalized hypergeometric functions, the resulting representations are readily computable. Some numerical examples corroborate the validity of the results derived herein.
The relation between Pearson’s correlation coefficient r and Salton’s cosine measure
Egghe, L.; Leydesdorff, L.
2009-01-01
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points,
Raykov, Tenko
2011-01-01
Interval estimation of intraclass correlation coefficients in hierarchical designs is discussed within a latent variable modeling framework. A method accomplishing this aim is outlined, which is applicable in two-level studies where participants (or generally lower-order units) are clustered within higher-order units. The procedure can also be…
Speed Estimation in Geared Wind Turbines Using the Maximum Correlation Coefficient
DEFF Research Database (Denmark)
Skrimpas, Georgios Alexandros; Marhadi, Kun S.; Jensen, Bogi Bech
2015-01-01
to overcome the above mentioned issues. The high speed stage shaft angular velocity is calculated based on the maximum correlation coefficient between the 1 st gear mesh frequency of the last gearbox stage and a pure sinus tone of known frequency and phase. The proposed algorithm utilizes vibration signals...
A simple approximation to the bivariate normal distribution with large correlation coefficient
Albers, Willem/Wim; Kallenberg, W.C.M.
1994-01-01
The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the
Sample Size Calculation for Estimating or Testing a Nonzero Squared Multiple Correlation Coefficient
Krishnamoorthy, K.; Xia, Yanping
2008-01-01
The problems of hypothesis testing and interval estimation of the squared multiple correlation coefficient of a multivariate normal distribution are considered. It is shown that available one-sided tests are uniformly most powerful, and the one-sided confidence intervals are uniformly most accurate. An exact method of calculating sample size to…
International Nuclear Information System (INIS)
Peyghambarzadeh, S.M.; Hashemabadi, S.H.; Naraki, M.; Vermahmoudi, Y.
2013-01-01
Heat transfer of coolant flow through the automobile radiators is of great importance for the optimization of fuel consumption. In this study, the heat transfer performance of the automobile radiator is evaluated experimentally by calculating the overall heat transfer coefficient (U) according to the conventional ε-NTU technique. Copper oxide (CuO) and Iron oxide (Fe 2 O 3 ) nanoparticles are added to the water at three concentrations 0.15, 0.4, and 0.65 vol.% with considering the best pH for longer stability. In these experiments, the liquid side Reynolds number is varied in the range of 50–1000 and the inlet liquid to the radiator has a constant temperature which is changed at 50, 65 and 80 °C. The ambient air for cooling of the hot liquid is used at constant temperature and the air Reynolds number is varied between 500 and 700. However, the effects of these variables on the overall heat transfer coefficient are deeply investigated. Results demonstrate that both nanofluids show greater overall heat transfer coefficient in comparison with water up to 9%. Furthermore, increasing the nanoparticle concentration, air velocity, and nanofluid velocity enhances the overall heat transfer coefficient. In contrast, increasing the nanofluid inlet temperature, lower overall heat transfer coefficient was recorded. -- Highlights: ► Overall heat transfer coefficient in the car radiator measured experimentally. ► Nanofluids showed greater heat transfer performance comparing with water. ► Increasing liquid and air Re increases the overall heat transfer coefficient. ► Increasing the inlet liquid temperature decreases the overall heat transfer coefficient
Heat Transfer Coefficient at Cast-Mold Interface During Centrifugal Casting: Calculation of Air Gap
Bohacek, Jan; Kharicha, Abdellah; Ludwig, Andreas; Wu, Menghuai; Karimi-Sibaki, Ebrahim
2018-06-01
During centrifugal casting, the thermal resistance at the cast-mold interface represents a main blockage mechanism for heat transfer. In addition to the refractory coating, an air gap begins to form due to the shrinkage of the casting and the mold expansion, under the continuous influence of strong centrifugal forces. Here, the heat transfer coefficient at the cast-mold interface h has been determined from calculations of the air gap thickness d a based on a plane stress model taking into account thermoelastic stresses, centrifugal forces, plastic deformations, and a temperature-dependent Young's modulus. The numerical approach proposed here is rather novel and tries to offer an alternative to the empirical formulas usually used in numerical simulations for a description of a time-dependent heat transfer coefficient h. Several numerical tests were performed for different coating thicknesses d C, rotation rates Ω, and temperatures of solidus T sol. Results demonstrated that the scenario at the interface is unique for each set of parameters, hindering the possibility of employing empirical formulas without a preceding experiment being performed. Initial values of h are simply equivalent to the ratio of the coating thermal conductivity and its thickness ( 1000 Wm-2 K-1). Later, when the air gap is formed, h drops exponentially to values at least one order of magnitude smaller ( 100 Wm-2 K-1).
Effect of heat and mass transfer coefficients on the performance of automotive catalytic converters
Energy Technology Data Exchange (ETDEWEB)
Shamim, T. [Michigan Univ., Dept. of Mechanical Engineering, Dearborn, MI (United States)
2003-06-01
This paper numerically investigates the role of heat and mass transfer coefficients on the performance of automotive catalytic converters, which are employed to reduce engine exhaust emissions. The pollutant conversion performance of a converter is influenced by a number of physical and chemical processes that take place in gaseous and solid phases as the exhaust gases flow through the catalyst. A quantitative predictive understanding of these complex catalyst processes involving flow dynamics, heterogeneous surface reactions and heat and mass transport mechanisms is important in improving the converter design. The role of convective transport phenomena becomes important at high temperature when the mass transfer becomes rate-limiting to an increasing extent. The objective of the present study is to elucidate the influence of convective heat and mass transfer coefficients (mechanisms). The mathematical model considers the conservation of mass, momentum and energy in both gaseous and solid phases. In addition to the heterogeneous surface reactions, the model also takes into account the adsorption/desorption of oxygen in the catalyst during non-stoichiometric composition of air/fuel mixtures. The governing equations are solved by an implicit scheme using a successive line under a relaxation method. The converter performance under the transient conditions as simulated by the US Federal Test Procedure (US-FTP) is analysed. (Author)
Condition monitoring of steam generator by estimating the overall heat transfer coefficient
International Nuclear Information System (INIS)
Furusawa, Hiroaki; Gofuku, Akio
2013-01-01
This study develops a technique for monitoring in on-line the state of the steam generator of the fast-breeder reactor (FBR) “Monju”. Because the FBR uses liquid sodium as coolant, it is necessary to handle liquid sodium with caution due to its chemical characteristics. The steam generator generates steam by the heat of secondary sodium coolant. The sodium-water reaction may happen if a pinhole or crack occurs at the thin metal tube wall that separates the secondary sodium coolant and water/steam. Therefore, it is very important to detect an anomaly of the wall of heat transfer tubes at an early stage. This study aims at developing an on-line condition monitoring technique of the steam generator by estimating overall heat transfer coefficient from process signals. This paper describes simplified mathematical models of superheater and evaporator to estimate the overall heat transfer coefficient and a technique to diagnose the state of the steam generator. The applicability of the technique is confirmed by several estimations using simulated process signals with artificial noises. The results of the estimations show that the developed technique can detect the occurrence of an anomaly. (author)
Roth, Philip L; Le, Huy; Oh, In-Sue; Van Iddekinge, Chad H; Bobko, Philip
2018-06-01
Meta-analysis has become a well-accepted method for synthesizing empirical research about a given phenomenon. Many meta-analyses focus on synthesizing correlations across primary studies, but some primary studies do not report correlations. Peterson and Brown (2005) suggested that researchers could use standardized regression weights (i.e., beta coefficients) to impute missing correlations. Indeed, their beta estimation procedures (BEPs) have been used in meta-analyses in a wide variety of fields. In this study, the authors evaluated the accuracy of BEPs in meta-analysis. We first examined how use of BEPs might affect results from a published meta-analysis. We then developed a series of Monte Carlo simulations that systematically compared the use of existing correlations (that were not missing) to data sets that incorporated BEPs (that impute missing correlations from corresponding beta coefficients). These simulations estimated ρ̄ (mean population correlation) and SDρ (true standard deviation) across a variety of meta-analytic conditions. Results from both the existing meta-analysis and the Monte Carlo simulations revealed that BEPs were associated with potentially large biases when estimating ρ̄ and even larger biases when estimating SDρ. Using only existing correlations often substantially outperformed use of BEPs and virtually never performed worse than BEPs. Overall, the authors urge a return to the standard practice of using only existing correlations in meta-analysis. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.
Energy Technology Data Exchange (ETDEWEB)
Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-01-01
Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by
Moisture Transfer in Concrete: Numerical Determination of the Capillary Conductivity Coefficient
Directory of Open Access Journals (Sweden)
Simo Elie
2017-03-01
Full Text Available We numerically investigated moisture transfer in buildings made of concrete. We considered three types of concrete: normal concrete, pumice concrete and cellular concrete. We present the results of a 1-D liquid water flow in such materials. We evaluated the moisture distribution in building materials using the Runge-Kutta fourth-and-fifth-order method. The DOPRI5 code was used as an integrator. The model calculated the resulting moisture content and other moisture-dependent physical parameters. The moisture curves were plotted. The dampness data obtained was utilized for the numerical computation of the coefficient of the capillary conductivity of moisture. Different profiles of this coefficient are represented. Calculations were performed for four different values of the outdoor temperature: -5°C, 0°C, 5°C and 10°C. We determined that the curves corresponding to small time intervals of wetting are associated with great amplitudes of the capillary conductivity . The amplitudes of the coefficient of the capillary conductivity decrease as the time interval increases. High outdoor temperatures induce high amplitudes of the coefficient of the capillary conductivity.
Evaluation of icing drag coefficient correlations applied to iced propeller performance prediction
Miller, Thomas L.; Shaw, R. J.; Korkan, K. D.
1987-01-01
Evaluation of three empirical icing drag coefficient correlations is accomplished through application to a set of propeller icing data. The various correlations represent the best means currently available for relating drag rise to various flight and atmospheric conditions for both fixed-wing and rotating airfoils, and the work presented here ilustrates and evaluates one such application of the latter case. The origins of each of the correlations are discussed, and their apparent capabilities and limitations are summarized. These correlations have been made to be an integral part of a computer code, ICEPERF, which has been designed to calculate iced propeller performance. Comparison with experimental propeller icing data shows generally good agreement, with the quality of the predicted results seen to be directly related to the radial icing extent of each case. The code's capability to properly predict thrust coefficient, power coefficient, and propeller efficiency is shown to be strongly dependent on the choice of correlation selected, as well as upon proper specificatioon of radial icing extent.
Spatially varying cross-correlation coefficients in the presence of nugget effects
Kleiber, William; Genton, Marc G.
2012-01-01
We derive sufficient conditions for the cross-correlation coefficient of a multivariate spatial process to vary with location when the spatial model is augmented with nugget effects. The derived class is valid for any choice of covariance functions, and yields substantial flexibility between multiple processes. The key is to identify the cross-correlation coefficient matrix with a contraction matrix, which can be either diagonal, implying a parsimonious formulation, or a fully general contraction matrix, yielding greater flexibility but added model complexity. We illustrate the approach with a bivariate minimum and maximum temperature dataset in Colorado, allowing the two variables to be positively correlated at low elevations and nearly independent at high elevations, while still yielding a positive definite covariance matrix. © 2012 Biometrika Trust.
Spatially varying cross-correlation coefficients in the presence of nugget effects
Kleiber, William
2012-11-29
We derive sufficient conditions for the cross-correlation coefficient of a multivariate spatial process to vary with location when the spatial model is augmented with nugget effects. The derived class is valid for any choice of covariance functions, and yields substantial flexibility between multiple processes. The key is to identify the cross-correlation coefficient matrix with a contraction matrix, which can be either diagonal, implying a parsimonious formulation, or a fully general contraction matrix, yielding greater flexibility but added model complexity. We illustrate the approach with a bivariate minimum and maximum temperature dataset in Colorado, allowing the two variables to be positively correlated at low elevations and nearly independent at high elevations, while still yielding a positive definite covariance matrix. © 2012 Biometrika Trust.
Mass transfer coefficient factor in pipe bend - 3 D CFD analysis
International Nuclear Information System (INIS)
Prasad, Mahendra; Gaikwad, Avinash J.; Madasamy, P.; Krishnamohan, T.V.; Velumurugan, S.; Sridharan, Arunkumar; Parida, Smrutiranjan
2015-01-01
In power industries Flow Accelerated Corrosion (FAC) has been a concern for pipe wall thinning where high velocity fluid at elevated temperatures is used. Even straight pipes are found to have non uniform corrosion and this is enhanced in junctions such as bends, orifices etc. Mass transfer coefficient (MTC) which defines the amount of corrosion changes from its value in straight pipe (with same fluid parameters) for flow in bends, orifice etc due to changes in velocity profile in axial direction. In this paper, 3 D computational fluid dynamics (CFD) simulation is carried out for an experiment on 58° bend angle and 2D bend radius circular carbon steel pipe carrying water at 120°C under neutral pH conditions. The turbulent model K-ω with shear stress transport was used for this purpose. The mass transfer boundary layer (MTBL) thickness δ mtbl depends on Schmidt number (Sc), as δ mtbl ∼ δ h /(Sc 1/3 ). MTBL is significantly smaller than hydrodynamic boundary layer δ h for large Sc, hence boundary layer meshing was carried out deep into δ mtbl . Uniform velocity was applied at the inlet. The flow velocity was 3 m/s at room temperature while the experimental fluid velocity was 7 m/s. Lower value of fluid velocity is chosen due to the limitations of grid size since it depends inversely on fluid velocity. The ratio of MTC in bend to straight pipe is not strongly dependent on Sc. CFD simulation at lower temperature is sufficient to get approximate MTC in bends. The ratio of the mass transfer coefficient at some locations in bend to the straight pipe coefficient (MTCR) is determined through simulation. The MTC increased in the extrados of the bend towards the outlet. (author)
Heat and mass transfer coefficients and modeling of infrared drying of banana slices
Directory of Open Access Journals (Sweden)
Fernanda Machado Baptestini
Full Text Available ABSTRACT Banana is one of the most consumed fruits in the world, having a large part of its production performed in tropical countries. This product possesses a wide range of vitamins and minerals, being an important component of the alimentation worldwide. However, the shelf life of bananas is short, thus requiring procedures to prevent the quality loss and increase the shelf life. One of these procedures widely used is drying. This work aimed to study the infrared drying process of banana slices (cv. Prata and determine the heat and mass transfer coefficients of this process. In addition, effective diffusion coefficient and relationship between ripening stages of banana and drying were obtained. Banana slices at four different ripening stages were dried using a dryer with infrared heating source with four different temperatures (65, 75, 85, and 95 ºC. Midilli model was the one that best represented infrared drying of banana slices. Heat and mass transfer coefficients varied, respectively, between 46.84 and 70.54 W m-2 K-1 and 0.040 to 0.0632 m s-1 for temperature range, at the different ripening stages. Effective diffusion coefficient ranged from 1.96 to 3.59 × 10-15 m² s-1. Activation energy encountered were 16.392, 29.531, 23.194, and 25.206 kJ mol-1 for 2nd, 3rd, 5th, and 7th ripening stages, respectively. Ripening stages did not affect the infrared drying of bananas.
Directory of Open Access Journals (Sweden)
Mario Arias Zabala
2001-01-01
Full Text Available In this paper the volumetric oxygen transfer (kLa and overall heat transfer (Ua coefficients were determined in flasks which were subjected to rotary shaker action, also provided with a temperature control chamber. Likewise, it was determined the effect over such coefficients of some parameters like surrounding temperature, shaking speed, closure type, liquid volume, capacity and baffles presence or absence in each flask, to determine the optimal work conditions in the rotary shaker. The used liquid in these experiments was distilled water. The kLa and Ua coefficients were also determined in the alcoholic fermentation of glucose by Saccharomyces cerevisiae yeast, in order to establish comparison standards. The maximum and minimum values of referred coefficients to distilled water and the operation conditions were: kLa of 6.2 x 10-3 s-1, working at 25 ºC, 100 rpm, 50 ml of liquid volume, erlenmeyer of 500 ml with baffles and plastic closure. kLa of 4.107 x 10-3 s-1, working at 45 ºC, 60 rpm, 150 ml of liquid volume, erlenmeyer of 250 ml without baffles and cotton closure. Ua of 31.9963 J/min °C, working at 45 ºC, 150 rpm, 150 ml of liquid volume, erlenmeyer of 500 ml with baffles and cotton closure. Ua of 6.0179 J/min °C, working at 35 ºC, 60 rpm, 50 ml of liquid volume, erlenmeyer of 250 ml without baffles and plastic closure. The kLa and Ua values in the alcoholic fermentation and the operation conditions were: kLa of 2.6 x 10-4 s-1 and Ua of 12.8907 J/min °C, working at 35 °C, 150 rpm, 150 ml of liquid volume, Erlenmeyer of 250 ml, with baffles and cotton closure.
Kim, Heung-Kyu; Lee, Seong Hyeon; Choi, Hyunjoo
2015-01-01
Using an inverse analysis technique, the heat transfer coefficient on the die-workpiece contact surface of a hot stamping process was evaluated as a power law function of contact pressure. This evaluation was to determine whether the heat transfer coefficient on the contact surface could be used for finite element analysis of the entire hot stamping process. By comparing results of the finite element analysis and experimental measurements of the phase transformation, an evaluation was performed to determine whether the obtained heat transfer coefficient function could provide reasonable finite element prediction for workpiece properties affected by the hot stamping process. PMID:28788046
DEFF Research Database (Denmark)
Ratkovich, Nicolas Rios; Berube, P.R.; Nopens, I.
2011-01-01
by the gas flow. It was noted that coalescence of bubbles affects the MTH. Coalescence increased the “width” of the peaks (i.e. the estimate of the variability of the mass transfer coefficient) and the height of the peak (i.e. amount of time that a mass transfer coefficient of a given value is maintained......). A semi-empirical relationship based on the Lévêque relationship for the Sherwood number (mass transfer coefficient) was formulated for the laminar regime. A test case comparison between water and activated sludge was performed based on full-scale airlift MBR operational conditions. It was found...
Czech Academy of Sciences Publication Activity Database
Kárászová, Magda; Šimčík, Miroslav; Friess, K.; Randová, A.; Jansen, J. C.; Růžička, Marek; Sedláková, Zuzana; Izák, Pavel
2013-01-01
Roč. 118, 30 OCT (2013), s. 255-263 ISSN 1383-5866 R&D Projects: GA ČR GAP106/10/1194; GA MŠk(CZ) 7C11009 Grant - others:RFCS(XE) RFCR-CT-2010-00009; INP(IT) PON01_01840; HA MŠk(CZ) CZ.1.05/2.1.00/03.0071 Institutional support: RVO:67985858 Keywords : biogas purification * supported ionic liquid membranes * mass transfer coefficients Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.065, year: 2013
Effect of Mixed Working Fluid Composition on Binary Cycle Condenser Heat Transfer Coefficients
Energy Technology Data Exchange (ETDEWEB)
Dan Wendt; Greg Mines
2011-10-01
Effect of Mixed Working Fluid Composition on Binary Cycle Condenser Heat Transfer Coefficients Dan Wendt, Greg Mines Idaho National Laboratory The use of mixed working fluids in binary power plants can provide significant increases in plant performance, provided the heat exchangers are designed to take advantage of these fluids non-isothermal phase changes. In the 1980's testing was conducted at DOE's Heat Cycle Research Facility (HCRF) where mixtures of different compositions were vaporized at supercritical pressures and then condensed. This testing had focused on using the data collected to verify that Heat Transfer Research Incorporated (HTRI) codes were suitable for the design of heat exchangers that could be used with mixtures. The HCRF data includes mixture compositions varying from 0% to 40% isopentane and condenser tube orientations of 15{sup o}, 60{sup o}, and 90{sup o} from horizontal. Testing was performed over a range of working fluid and cooling fluid conditions. Though the condenser used in this testing was water cooled, the working fluid condensation occurred on the tube-side of the heat exchanger. This tube-side condensation is analogous to that in an air-cooled condenser. Tube-side condensing heat transfer coefficient information gleaned from the HCRF testing is used in this study to assess the suitability of air-cooled condenser designs for use with mixtures. Results of an air-cooled binary plant process model performed with Aspen Plus indicate that that the optimal mixture composition (producing the maximum net power for the scenario considered) is within the range of compositions for which data exist. The HCRF data is used to assess the impact of composition, tube orientation, and process parameters on the condensing heat transfer coefficients. The sensitivity of the condensing coefficients to these factors is evaluated and the suitability of air-cooled condenser designs with mixtures is assessed. This paper summarizes the evaluation
Assessment of Real Heat Transfer Coefficients through Shell and Tube and Plate Heat Exchangers
Directory of Open Access Journals (Sweden)
Dan CONSTANTINESCU
2011-07-01
Full Text Available The purpose of this paper is to present a procedure used in the assessment of the real heat transfer characteristic of shell and tube and plate heat exchangers. The theoretical fundamentals of the procedure are introduced as well as the measured data collection and processing. The theoretical analysis is focused on the adoption of criterial equations which, subjected to certain verification criteria presented in the paper, provide the most credible value of the convection heat transfer coefficients inside the circular and flat tubes. In the end two case studies are presented, one concerning a shell and tube heat exchanger operational at INCERC Thermal Substation and the other concerning a plate heat exchanger tested on the Laboratory Stand of the Department of Building Services and Efficient Use of Energy in Buildings of INCERC Bucharest.
Directory of Open Access Journals (Sweden)
Božidar Liščić
2012-02-01
Full Text Available This paper explains the need for a database of cooling intensities for liquid quenchants, in order to predict the quench hardness, microstructure, stresses and distortion, when real engineering components of complex geometry are quenched. The existing laboratory procedures for cooling intensity evaluation, using small test specimens, and Lumped-Heat-Capacity Method for calculation of heat transfer coefficient, are presented. Temperature Gradient Method for heat transfer calculation in workshop conditions, when using the Liscic/Petrofer probe, has been elaborated. Critical heat flux densities and their relation to the initial heat flux density, is explained. Specific facilities for testing quenching intensity in workshop conditions, are shown. The two phase project of the International Federation for Heat Treatment and Surface Engineering (IFHTSE, as recently approved, is mentioned.
Review of measured values of the milk transfer coefficient f/sub m/ for iodine
Energy Technology Data Exchange (ETDEWEB)
Hoffman, F O [Oak Ridge National Lab., TN (USA)
1978-08-01
Most published assessments of the environmental transport of iodine have used a value of 1 X 10/sup -2/ days per litre (d/1) for the transfer coefficient (fsub(m)) which relates the concentration per litre of milk to the daily amount of the element ingested by a cow. However, the USNRC has recommended (USNRC 77) a value of 0.6 X 10/sup -2/ d/1 for the transfer of iodine to cow's milk and 6 X 10/sup -2/ d/1 for goat's milk. A literature survey of published values of fsub(m) leads to a recommendation which deviates from the values chosen by the USNRC. An fsub(m) of 0.5 d/1 for goat's milk and an fsub(m) of 1 X 10/sup -2/ for cow's milk appear to be more appropriate.
A review of measured values of the milk transfer coefficient (fsub(m)) for iodine
International Nuclear Information System (INIS)
Hoffman, F.O.
1978-01-01
Most published assessments of the environmental transport of iodine have used a value of 1 X 10 -2 days per litre (d/1) for the transfer coefficient (fsub(m)) which relates the concentration per litre of milk to the daily amount of the element ingested by a cow. However, the USNRC has recommended (USNRC 77) a value of 0.6 X 10 -2 d/1 for the transfer of iodine to cow's milk and 6 X 10 -2 d/1 for goat's milk. A literature survey of published values of fsub(m) leads to a recommendation which deviates from the values chosen by the USNRC. An fsub(m) of 0.5 d/1 for goat's milk and an fsub(m) of 1 X 10 -2 for cow's milk appear to be more appropriate. (author)
Experimental study of convective coefficient of mass transfer of avocado (Persia americana Mill.)
Energy Technology Data Exchange (ETDEWEB)
Alves, Suerda Bezerra; Luiz, Marcia Ramos; Amorim, Joselma Araujo de; Gusmao, Rennam Pereira de; Gurgel, Jose Mauricio [Universidade Federal da Paraiba (LES/UFPB), Joao Pessoa, PB (Brazil). Lab. de Energia Solar
2010-07-01
Most of all energy consumed worldwide comes from fossil fuels derived from petroleum. With the petroleum crisis in the 70 were sought new energy sources, among them renewable. One such source is biodiesel energy, organic matter originated from animal and/or vegetable. Among the various plant species is the avocado (Persia americana Mill.) showing great potential in the production of petroleum extracted from the pulp and the alcohol removed from the seed. The main obstacle for obtaining the petroleum is the high humidity found in the pulp, being necessary to the drying process, which involves the transfer of heat and mass. The aim of this study was to use the mathematical model represented by Newton's Law of Cooling to simulate the mass transfer on the surface of the avocado pulp during the drying process. The equation of the mathematical model was solved numerically and the method of least squares was identified convective coefficient of Mass Transfer. The dryer used in the experimental process was operated with air flow in the vertical, air flow average fixed 3m/s and temperatures of 50, 60 and 70 deg C. The scheme of the dryer used in the research is composed of the following equipment: centrifugal fan, which drives the air-drying; valve, which allows control of airflow; electrical resistance, used for heating air; the drying chamber, where enables measurement of temperature and relative humidity; support for smaller trays; trays smaller, where the samples of the pulp of the avocado are placed; exit of the air of drying for the environment. The result presented shows the ratio of moisture content as a function of temperature over time, where it is possible to also observe that how much bigger the temperature of drying, greater will be the convective coefficient of mass transfer of the avocado. (author)
Ghamlouch, T.; Roux, S.; Bailleul, J.-L.; Lefèvre, N.; Sobotka, V.
2017-10-01
Today's aerospace industrial first priority is the quality improvement of the composite material parts with the reduction of the manufacturing time in order to increase their quality/cost ratio. A fabrication method that could meet these specifications especially for large parts is the autoclave curing process. In fact the autoclave molding ensures the thermal control of the composite parts during the whole curing cycle. However the geometry of the tools as well as their positioning in the autoclave induce non uniform and complex flows around composite parts. This heterogeneity implies non-uniform heat transfers which can directly impact on part quality. One of the main challenges is therefore to describe the flow field inside an autoclave as well as the convective heat transfer from the heated pressurized gas to the composite part and the mold. For this purpose, and given the technical issues associated with instrumentation and measurements in actual autoclaves, an autoclave model was designed and then manufactured based on similarity laws. This tool allows the measurement of the flow field around representative real industrial molds using the PIV technique and the characterization of the heat transfer thanks to thermal instrumentation. The experimental results are then compared with those derived from numerical simulations using a commercial RANS CFD code. This study aims at developing a semi-empirical approach for the prediction of the heat transfer coefficient around the parts and therefore predicts its thermal history during the process with a view of optimization.
Zhou, Weiqing; Hu, Shenhua; Ma, Xiangrong; Zhou, Feng
2018-04-01
Condensation heat transfer coefficient (HTC) as a function of outlet vapor quality was investigated using water-ethanol vapor mixture of different ethanol vapor concentrations (0%, 1%, 2%, 5%, 10%, 20%) under three different system pressures (31 kPa, 47 kPa, 83 kPa). A heat transfer coefficient was developed by applying multiple linear regression method to experimental data, taking into account the dimensionless numbers which represents the Marangoni condensation effects, such as Re, Pr, Ja, Ma and Sh. The developed correlation can predict the condensation performance within a deviation range from -22% to 32%. Taking PHE's characteristic into consideration and bringing in Ma number and Sh number, a new correlation was developed, which showed a much more accurate prediction, within a deviation from -3.2% to 7.9%.
Shojaeefard, Mohammad Hasan; Khalkhali, Abolfazl; Yarmohammadisatri, Sadegh
2017-06-01
The main purpose of this paper is to propose a new method for designing Macpherson suspension, based on the Sobol indices in terms of Pearson correlation which determines the importance of each member on the behaviour of vehicle suspension. The formulation of dynamic analysis of Macpherson suspension system is developed using the suspension members as the modified links in order to achieve the desired kinematic behaviour. The mechanical system is replaced with an equivalent constrained links and then kinematic laws are utilised to obtain a new modified geometry of Macpherson suspension. The equivalent mechanism of Macpherson suspension increased the speed of analysis and reduced its complexity. The ADAMS/CAR software is utilised to simulate a full vehicle, Renault Logan car, in order to analyse the accuracy of modified geometry model. An experimental 4-poster test rig is considered for validating both ADAMS/CAR simulation and analytical geometry model. Pearson correlation coefficient is applied to analyse the sensitivity of each suspension member according to vehicle objective functions such as sprung mass acceleration, etc. Besides this matter, the estimation of Pearson correlation coefficient between variables is analysed in this method. It is understood that the Pearson correlation coefficient is an efficient method for analysing the vehicle suspension which leads to a better design of Macpherson suspension system.
Cluster structure in the correlation coefficient matrix can be characterized by abnormal eigenvalues
Nie, Chun-Xiao
2018-02-01
In a large number of previous studies, the researchers found that some of the eigenvalues of the financial correlation matrix were greater than the predicted values of the random matrix theory (RMT). Here, we call these eigenvalues as abnormal eigenvalues. In order to reveal the hidden meaning of these abnormal eigenvalues, we study the toy model with cluster structure and find that these eigenvalues are related to the cluster structure of the correlation coefficient matrix. In this paper, model-based experiments show that in most cases, the number of abnormal eigenvalues of the correlation matrix is equal to the number of clusters. In addition, empirical studies show that the sum of the abnormal eigenvalues is related to the clarity of the cluster structure and is negatively correlated with the correlation dimension.
Threshold network of a financial market using the P-value of correlation coefficients
Ha, Gyeong-Gyun; Lee, Jae Woo; Nobi, Ashadun
2015-06-01
Threshold methods in financial networks are important tools for obtaining important information about the financial state of a market. Previously, absolute thresholds of correlation coefficients have been used; however, they have no relation to the length of time. We assign a threshold value depending on the size of the time window by using the P-value concept of statistics. We construct a threshold network (TN) at the same threshold value for two different time window sizes in the Korean Composite Stock Price Index (KOSPI). We measure network properties, such as the edge density, clustering coefficient, assortativity coefficient, and modularity. We determine that a significant difference exists between the network properties of the two time windows at the same threshold, especially during crises. This implies that the market information depends on the length of the time window when constructing the TN. We apply the same technique to Standard and Poor's 500 (S&P500) and observe similar results.
Thermal expansion coefficient determination of polylactic acid using digital image correlation
Botean, Adrian-Ioan
2018-02-01
This paper aims determining the linear thermal expansion coefficient (CTE) of polylactic acid (PLA) using an optical method for measuring deformations called digital image correlation method (DIC). Because PLA is often used in making many pieces with 3D printing technology, it is opportune to know this coefficient to obtain a higher degree of precision in the construction of parts and to monitor deformations when these parts are subjected to a thermal gradient. Are used two PLA discs with 20 and 40% degree of filling. In parallel with this approach was determined the linear thermal expansion coefficient (CTE) for the copper cylinder on the surface of which are placed the two discs of PLA.
Thermal expansion coefficient determination of polylactic acid using digital image correlation
Directory of Open Access Journals (Sweden)
Botean Adrian - Ioan
2018-01-01
Full Text Available This paper aims determining the linear thermal expansion coefficient (CTE of polylactic acid (PLA using an optical method for measuring deformations called digital image correlation method (DIC. Because PLA is often used in making many pieces with 3D printing technology, it is opportune to know this coefficient to obtain a higher degree of precision in the construction of parts and to monitor deformations when these parts are subjected to a thermal gradient. Are used two PLA discs with 20 and 40% degree of filling. In parallel with this approach was determined the linear thermal expansion coefficient (CTE for the copper cylinder on the surface of which are placed the two discs of PLA.
A Correlation for Forced Convective Boiling Heat Transfer of Refrigerants in a Microfin Tube
Momoki, Satoru; Yu, Jian; Koyama, Shigeru; Fujii, Tetsu; Honda, Hiroshi
The experimental study is reported on the forced convective boiling of pure refrigerants HCFC22, HFC134a and HCFC123 flowing in a horizontal microfin tube. The local heat transfer coefficient defined based on the actual inside surface area is measured in the ranges of mass velocity of 200 to 400 kg/m2s, heat flux of 5 to 64 kW/m2 and reduced pressure of 0.07 to 0.24. Using the Chen-type model, a new correlation for microfin tubes is proposed considering the enhancement effect of microfins on both the convective heat transfer and the nucleate boiling components. In the convective heat transfer component, the correlation to predict the heat transfer coefficient of liquid-only flow is determined from preliminary experiments on single-phase flow in microfin tubes, and the two-phase flow enhancement factor is determined from the present experimental data. For the nucleate boiling component, the correlation of Takamatsu et al. for smooth tube is modified. The prediction of the present correlation agrees well with present experimental data, and is available for several microfin tubes which were tested by other researchers.
Energy Technology Data Exchange (ETDEWEB)
Michel, B., E-mail: benedicte.michel@irsn.fr
2015-05-15
Highlights: • A new set of 2D convective heat transfer correlations is proposed. • It takes into account different horizontal and lateral superficial velocities. • It is based on previously established correlations. • It is validated against recent CLARA experiments. • It has to be implemented in a 0D MCCI (molten core concrete interaction) code. - Abstract: During an hypothetical Pressurized Water Reactor (PWR) or Boiling Water Reactor (BWR) severe accident with core meltdown and vessel failure, corium would fall directly on the concrete reactor pit basemat if no water is present. The high temperature of the corium pool maintained by the residual power would lead to the erosion of the concrete walls and basemat of this reactor pit. The thermal decomposition of concrete will lead to the release of a significant amount of gases that will modify the corium pool thermal hydraulics. In particular, it will affect heat transfers between the corium pool and the concrete which determine the reactor pit ablation kinetics. A new set of convective heat transfer coefficients in a pool with different lateral and horizontal superficial gas velocities is modeled and validated against the recent CLARA experimental program. 155 tests of this program, in two size configurations and a high range of investigated viscosity, have been used to validate the model. Then, a method to define different lateral and horizontal superficial gas velocities in a 0D code is proposed together with a discussion about the possible viscosity in the reactor case when the pool is semi-solid. This model is going to be implemented in the 0D ASTEC/MEDICIS code in order to determine the impact of the convective heat transfer in the concrete ablation by corium.
Simple heat transfer correlations for turbulent tube flow
Directory of Open Access Journals (Sweden)
Taler Dawid
2017-01-01
Full Text Available The paper presents three power-type correlations of a simple form, which are valid for Reynolds numbers range from 3·103 ≤ Re ≤ 106, and for three different ranges of Prandtl number: 0.1 ≤ Pr ≤ 1.0, 1.0 < Pr ≤ 3.0, and 3.0 < Pr ≤ 103. Heat transfer correlations developed in the paper were compared with experimental results available in the literature. The comparisons performed in the paper confirm the good accuracy of the proposed correlations. They are also much simpler compared with the relationship of Gnielinski, which is also widely used in the heat transfer calculations.
International Nuclear Information System (INIS)
Shin, So Min; Lee, Ki Seon; Park, Seoung Duck; Kwak, Jae Su
2009-01-01
Heat transfer coefficients were measured in a channel with one side dimpled surface. The sphere type dimples were fabricated, and the diameter (D) and the depth of dimple was 16 mm and 4 mm, respectively. Two channel heights of about 0.6D and 1.2D, two dimple configurations were tested. The Reynolds number based on the channel hydraulic diameter was varied from 30000 to 50000. The improved hue detection based transient liquid crystal technique was used in the heat transfer measurement. Heat transfer measurement results showed that high heat transfer was induced downstream of the dimples due to flow reattachment. Due to the flow recirculation on the upstream side in the dimple, the heat transfer coefficient was very low. As the Reynolds increased, the overall heat transfer coefficients also increased. With the same dimple arrangement, the heat transfer coefficients and the thermal performance factors were higher for the lower channel height. As the distance between the dimples became smaller, the overall heat transfer coefficient and the thermal performance factors increased
International Nuclear Information System (INIS)
Morais, Antony Bertie; Jayakumar, Chinnakannu; Gandhi, Nagarajan Nagendra
2013-01-01
Concentrated aqueous solutions of a large number of hydrotropic agents, urea, nicotinamide, and sodium salicylate, have been employed to enhance the aqueous solubilities of poorly water soluble organic compounds. The influence of a wide range of hydrotrope concentrations (0-3.0mol·L"−"1) and different system temperatures (303-333 K) on the solubility of ethylbenzene has been studied. The solubility of ethylbenzene increases with increase in hydrotrope concentration and also with system temperature. Consequent to the increase in the solubility of ethylbenzene, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass transfer coefficient of ethylbenzene. The Setschenow constant, K_s, a measure of the effectiveness of a hydrotrope, was determined for each case. To ascertain the hydrotropic aggregation behavior of ethylbenzene, thermodynamic parameters such as Gibb’s free energy, enthalpy, and entropy of ethylbenzene were determined
Energy Technology Data Exchange (ETDEWEB)
Morais, Antony Bertie; Jayakumar, Chinnakannu; Gandhi, Nagarajan Nagendra [Anna University, Chennai (India)
2013-04-15
Concentrated aqueous solutions of a large number of hydrotropic agents, urea, nicotinamide, and sodium salicylate, have been employed to enhance the aqueous solubilities of poorly water soluble organic compounds. The influence of a wide range of hydrotrope concentrations (0-3.0mol·L{sup −1}) and different system temperatures (303-333 K) on the solubility of ethylbenzene has been studied. The solubility of ethylbenzene increases with increase in hydrotrope concentration and also with system temperature. Consequent to the increase in the solubility of ethylbenzene, the mass transfer coefficient was also found to increase with increase in hydrotrope concentration at 303 K. The enhancement factor, which is the ratio of the value in the presence and absence of a hydrotrope, is reported for both solubility and mass transfer coefficient of ethylbenzene. The Setschenow constant, K{sub s}, a measure of the effectiveness of a hydrotrope, was determined for each case. To ascertain the hydrotropic aggregation behavior of ethylbenzene, thermodynamic parameters such as Gibb’s free energy, enthalpy, and entropy of ethylbenzene were determined.
Development of a model to calculate the overall heat transfer coefficient of greenhouse covers
Energy Technology Data Exchange (ETDEWEB)
Rasheed, A.; Lee, J. W.; Lee, H.L.
2017-07-01
A Building Energy Simulation (BES) model based on TRNSYS, was developed to investigate the overall heat transfer coefficient (U-value) of greenhouse covers including polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC), and horticultural glass (HG). This was used to determine the influences of inside-to-outside temperature difference, wind speed, and night sky radiation on the U-values of these materials. The model was calibrated using published values of the inside and outside convective heat transfer coefficients. Validation of the model was demonstrated by the agreement between the computed and experimental results for a single-layer PE film. The results from the BES model showed significant changes in U-value in response to variations in weather parameters and the use of single or double layer greenhouse covers. It was found that the U-value of PC, PVC, and HG was 9%, 4%, and 15% lower, respectively, than that for PE. In addition, by using double glazing a 34% reduction in heat loss was noted. For the given temperature U-value increases as wind speed increases. The slopes at the temperature differences of 20, 30, 40, and 50 °C, were approximately 0.3, 0.5, 0.7, and 0.9, respectively. The results agree with those put forward by other researchers. Hence, the presented model is reliable and can play a valuable role in future work on greenhouse energy modelling.
Supel'nyak, M. I.
2017-11-01
Features of calculation of temperature oscillations which are damped in a surface layer of a solid and which are having a small range in comparison with range of temperature of the fluid medium surrounding the solid at heat transfer coefficient changing in time under the periodic law are considered. For the specified case the equations for approximate definition of constant and oscillating components of temperature field of a solid are received. The possibility of use of appropriately chosen steady-state coefficient when calculating the temperature oscillations instead of unsteady heat-transfer coefficient is investigated. Dependence for definition of such equivalent constant heat-transfer coefficient is determined. With its help the research of temperature oscillations of solids with canonical form for some specific conditions of heat transfer is undertaken. Comparison of the obtained data with results of exact solutions of a problem of heat conductivity by which the limits to applicability of the offered approach are defined is carried out.
Ma, Rubao; Xu, Weichao; Zhang, Yun; Ye, Zhongfu
2014-01-01
This paper investigates the robustness properties of Pearson's rank-variate correlation coefficient (PRVCC) in scenarios where one channel is corrupted by impulsive noise and the other is impulsive noise-free. As shown in our previous work, these scenarios that frequently encountered in radar and/or sonar, can be well emulated by a particular bivariate contaminated Gaussian model (CGM). Under this CGM, we establish the asymptotic closed forms of the expectation and variance of PRVCC by means of the well known Delta method. To gain a deeper understanding, we also compare PRVCC with two other classical correlation coefficients, i.e., Spearman's rho (SR) and Kendall's tau (KT), in terms of the root mean squared error (RMSE). Monte Carlo simulations not only verify our theoretical findings, but also reveal the advantage of PRVCC by an example of estimating the time delay in the particular impulsive noise environment.
Relationship between the Kubelka-Munk scattering and radiative transfer coefficients.
Thennadil, Suresh N
2008-07-01
The relationship between the Kubelka-Munk (K-M) and the transport scattering coefficient is obtained through a semi-empirical approach. This approach gives the same result as that given by Gate [Appl. Opt.13, 236 (1974)] when the incident beam is diffuse. This result and those given by Star et al. [Phys. Med. Biol.33, 437 (1988)] and Brinkworth [Appl. Opt.11, 1434 (1972)] are compared with the exact solution of the radiative transfer equation over a large range of optical properties. It is found that the latter expressions, which include an absorption component, do not give accurate results over the range considered. Using the semi-empirical approach, the relationship between the K-M and the transport scattering coefficient is derived for the case where the incident light is collimated. It is shown that although the K-M equation is derived based on diffuse incident light, it can also represent very well the reflectance from a slab of infinite thickness when the incident light is collimated. However, in this case the relationship between the coefficients has to include a function that is dependent on the anisotropy factor. Analysis indicates that the K-M transform achieves the objective of obtaining a measure that gives the ratio of absorption to scattering effects for both diffuse and collimated incident beams over a large range of optical properties.
Ahlgren, P.; Jarneving, B.; ROUSSEAU, Ronald
2003-01-01
Author cocitation analysis (ACA), a special type of cocitation analysis, was introduced by White and Griffith in 1981. This technique is used to analyze the intellectual structure of a given scientific field. In 1990, McCain published a technical overview that has been largely adopted as a standard. Here, McCain notes that Pearson's correlation coefficient (Pearson's r) is often used as a similarity measure in ACA and presents some advantages of its use. The present article criticizes the use...
The relation between Pearson’s correlation coefficient r and Salton’s cosine measure
EGGHE, Leo; Leydesdorff, L.
2009-01-01
The relation between Pearson’s correlation coefficient and Salton’s cosine measure is revealed based on the different possible values of the division of the -norm and the norm of a vector. These different values yield a sheaf of increasingly straight lines which form together a cloud of points, being the investigated relation. These theoretical results are tested against the author co-citation relations among 24 informetricians for who two matrices can be constructed, based on co-citations: t...
Generalized Correlation Coefficient for Non-Parametric Analysis of Microarray Time-Course Data.
Tan, Qihua; Thomassen, Mads; Burton, Mark; Mose, Kristian Fredløv; Andersen, Klaus Ejner; Hjelmborg, Jacob; Kruse, Torben
2017-06-06
Modeling complex time-course patterns is a challenging issue in microarray study due to complex gene expression patterns in response to the time-course experiment. We introduce the generalized correlation coefficient and propose a combinatory approach for detecting, testing and clustering the heterogeneous time-course gene expression patterns. Application of the method identified nonlinear time-course patterns in high agreement with parametric analysis. We conclude that the non-parametric nature in the generalized correlation analysis could be an useful and efficient tool for analyzing microarray time-course data and for exploring the complex relationships in the omics data for studying their association with disease and health.
Ground reaction force analysed with correlation coefficient matrix in group of stroke patients.
Szczerbik, Ewa; Krawczyk, Maciej; Syczewska, Małgorzata
2014-01-01
Stroke is the third cause of death in contemporary society and causes many disorders. Clinical scales, ground reaction force (GRF) and objective gait analysis are used for assessment of patient's rehabilitation progress during treatment. The goal of this paper is to assess whether signal correlation coefficient matrix applied to GRF can be used for evaluation of the status of post-stroke patients. A group of patients underwent clinical assessment and instrumented gait analysis simultaneously three times. The difference between components of patient's GRF (vertical, fore/aft, med/lat) and normal ones (reference GRF of healthy subjects) was calculated as correlation coefficient. Patients were divided into two groups ("worse" and "better") based on the clinical functional scale tests done at the beginning of rehabilitation process. The results obtained by these two groups were compared using statistical analysis. An increase of median value of correlation coefficient is observed in all components of GRF, but only in non-paretic leg. Analysis of GRF signal can be helpful in assessment of post-stroke patients during rehabilitation. Improvement in stroke patients was observed in non-paretic leg of the "worse" group. GRF analysis should not be the only tool for objective validation of patient's improvement, but could be used as additional source of information.
Mikuni, Shintaro; Yamamoto, Johtaro; Horio, Takashi; Kinjo, Masataka
2017-08-25
The glucocorticoid receptor (GR) is a transcription factor, which interacts with DNA and other cofactors to regulate gene transcription. Binding to other partners in the cell nucleus alters the diffusion properties of GR. Raster image correlation spectroscopy (RICS) was applied to quantitatively characterize the diffusion properties of EGFP labeled human GR (EGFP-hGR) and its mutants in the cell nucleus. RICS is an image correlation technique that evaluates the spatial distribution of the diffusion coefficient as a diffusion map. Interestingly, we observed that the averaged diffusion coefficient of EGFP-hGR strongly and negatively correlated with its transcriptional activities in comparison to that of EGFP-hGR wild type and mutants with various transcriptional activities. This result suggests that the decreasing of the diffusion coefficient of hGR was reflected in the high-affinity binding to DNA. Moreover, the hyper-phosphorylation of hGR can enhance the transcriptional activity by reduction of the interaction between the hGR and the nuclear corepressors.
Directory of Open Access Journals (Sweden)
Havlik Jan
2017-01-01
Full Text Available This article deals with the experimental determination of heat transfer coefficients. The calculation of heat transfer coefficients constitutes a crucial issue in design and sizing of heat exchangers. The Wilson plot method and its modifications based on measured experimental data utilization provide an appropriate tool for the analysis of convection heat transfer processes and the determination of convection coefficients in complex cases. A modification of the Wilson plot method for shell-and-tube condensers is proposed. The original Wilson plot method considers a constant value of thermal resistance on the condensation side. The heat transfer coefficient on the cooling side is determined based on the change in thermal resistance for different conditions (fluid velocity and temperature. The modification is based on the validation of the Nusselt theory for calculating the heat transfer coefficient on the condensation side. A change of thermal resistance on the condensation side is expected and the value is part of the calculation. It is possible to improve the determination accuracy of the criterion equation for calculation of the heat transfer coefficient using the proposed modification. The criterion equation proposed by this modification for the tested shell-and-tube condenser achieves good agreement with the experimental results and also with commonly used theoretical methods.
DEFF Research Database (Denmark)
Edjabou, Maklawe Essonanawe; Martín-Fernández, Josep Antoni; Scheutz, Charlotte
2017-01-01
-derived food waste amounted to 2.21 ± 3.12% with a confidence interval of (−4.03; 8.45), which highlights the problem of the biased negative proportions. A Pearson’s correlation test, applied to waste fraction generation (kg mass), indicated a positive correlation between avoidable vegetable food waste...... and plastic packaging. However, correlation tests applied to waste fraction compositions (percentage values) showed a negative association in this regard, thus demonstrating that statistical analyses applied to compositional waste fraction data, without addressing the closed characteristics of these data......, have the potential to generate spurious or misleading results. Therefore, ¨compositional data should be transformed adequately prior to any statistical analysis, such as computing mean, standard deviation and correlation coefficients....
International Nuclear Information System (INIS)
Arslan, Goekhan; Ozdemir, Mustafa
2008-01-01
In this paper, heat transfer in an oscillating loop heat pipe is investigated experimentally. The oscillation of the liquid columns at the evaporator and condenser sections of the heat pipe are driven by gravitational force and the phase lag between evaporation and condensation because the dimensions of the heat pipe are large enough to neglect the effect of capillary forces. The overall heat transfer coefficient based on the temperature difference between the evaporator and condenser surfaces is introduced by a correlation function of dimensionless numbers such as kinetic Reynolds number, c p ΔT/h fg and the geometric parameters
Determination of interfacial heat transfer coefficient for TC11 titanium alloy hot forging
Lu, Baoshan; Wang, Leigang; Geng, Zhe; Huang, Yao
2017-10-01
In this paper, based on self-developed experimental apparatus, the upsetting test of TC11 titanium alloy on the hot flat die was conducted and Beck's nonlinear inverse estimation method was adopted to calculate the interfacial heat transfer coefficient (IHTC) and the change rules of IHTC following billet deformation rate, average interfacial temperature and holding time were investigated respectively. Experimental results indicate that IHTC increases with the increase of deformation rate as a whole, and the billet deformation heat and interfacial friction heat during forming that remarkably contribute to IHTC and the contributions by heat conduction to IHTC is differ from that by friction; the glass lubricant coated on the billet surface that weakens the heat transfer situation in the early stage of forging, however, this blocking effect of lubricant on IHTC soon vanishes with increasing deformation rate and it enhances the interface heat transfer later; the average interfacial temperature impacts on IHTC in many aspects and a high average interfacial temperature IHTC corresponds to a high IHTC when the deformation rate is certain, but this changing trend is not monotonous; the IHTC decreases with the increase of holding time due to oxidation. After certain holding time, the IHTC is only related to temperature and pressure in the absence of deformation rate, and the influence of pressure on IHTC is larger than that of temperature on it.
Calculation and validation of heat transfer coefficient for warm forming operations
Omer, Kaab; Butcher, Clifford; Worswick, Michael
2017-10-01
In an effort to reduce the weight of their products, the automotive industry is exploring various hot forming and warm forming technologies. One critical aspect in these technologies is understanding and quantifying the heat transfer between the blank and the tooling. The purpose of the current study is twofold. First, an experimental procedure to obtain the heat transfer coefficient (HTC) as a function of pressure for the purposes of a metal forming simulation is devised. The experimental approach was used in conjunction with finite element models to obtain HTC values as a function of die pressure. The materials that were characterized were AA5182-O and AA7075-T6. Both the heating operation and warm forming deep draw were modelled using the LS-DYNA commercial finite element code. Temperature-time measurements were obtained from both applications. The results of the finite element model showed that the experimentally derived HTC values were able to predict the temperature-time history to within a 2% of the measured response. It is intended that the HTC values presented herein can be used in warm forming models in order to accurately capture the heat transfer characteristics of the operation.
Heat transfer coefficient for flow boiling in an annular mini gap
Directory of Open Access Journals (Sweden)
Hożejowska Sylwia
2016-01-01
Full Text Available The aim of this paper was to present the concept of mathematical models of heat transfer in flow boiling in an annular mini gap between the metal pipe with enhanced exterior surface and the external glass pipe. The one- and two-dimensional mathematical models were proposed to describe stationary heat transfer in the gap. A set of experimental data governed both the form of energy equations in cylindrical coordinates and the boundary conditions. The models were formulated to minimize the number of experimentally determined constants. Known temperature distributions in the enhanced surface and in the fluid helped to determine, from the Robin condition, the local heat transfer coefficients at the enhanced surface – fluid contact. The Trefftz method was used to find two-dimensional temperature distributions for the thermal conductive filler layer, enhanced surface and flowing fluid. The method of temperature calculation depended on whether the area of single-phase convection ended with boiling incipience in the gap or the two-phase flow region prevailed, with either fully developed bubbly flow or bubbly-slug flow. In the two–phase flow, the fluid temperature was calculated by Trefftz method. Trefftz functions for the Laplace equation and for the energy equation were used in the calculations.
International Nuclear Information System (INIS)
Geetha, P.V.; Karunakara, N.; Prabhu, Ujwal; Yashodhara, I.; Ravi, P.M.; Dileep, B.N.; Karpe, Rupali
2014-01-01
Extensive studies on transfer of 131 I through grass-cow-milk pathway after the Chernobyl accident were reported. But, under nor mal operational conditions of a power reactor, 131 I is not present in measurable concentration in environmental matrices around a nuclear power generating station. Hence, database on 131 I transfer coefficients for grass-cow-milk pathway in equilibrium conditions in the environment of a nuclear power plant are sparse. One of method to estimate the equilibrium transfer coefficient is to use stable iodine, which is present naturally in very low levels in the environmental matrices. By measuring the concentration of stable iodine concentration in grass and cow milk, the grass-to-milk transfer coefficient of iodine can be estimated. Since the metabolism of stable and radioiodine is same, the data obtained for transfer coefficient of stable iodine could be used for predicting the transfer for radioiodine to cow milk. The measurement of stable iodine in the environmental sample is very challenging because of its extremely low concentration. Neutron Activation Analysis (NAA) can be used to estimate stable iodine in the environment matrices after suitably optimizing the condition to minimize interferences. This paper presents the results of a systematic study on the transfer coefficients for grass-cow milk pathway of iodine in normal (equilibrium) situations as well as for a postulated (simulated) emergency condition in Kaiga region
Leung, Juliana Y.; Srinivasan, Sanjay
2016-09-01
Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It
Ma, Chuang; Wang, Xiangfeng
2012-09-01
One of the computational challenges in plant systems biology is to accurately infer transcriptional regulation relationships based on correlation analyses of gene expression patterns. Despite several correlation methods that are applied in biology to analyze microarray data, concerns regarding the compatibility of these methods with the gene expression data profiled by high-throughput RNA transcriptome sequencing (RNA-Seq) technology have been raised. These concerns are mainly due to the fact that the distribution of read counts in RNA-Seq experiments is different from that of fluorescence intensities in microarray experiments. Therefore, a comprehensive evaluation of the existing correlation methods and, if necessary, introduction of novel methods into biology is appropriate. In this study, we compared four existing correlation methods used in microarray analysis and one novel method called the Gini correlation coefficient on previously published microarray-based and sequencing-based gene expression data in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). The comparisons were performed on more than 11,000 regulatory relationships in Arabidopsis, including 8,929 pairs of transcription factors and target genes. Our analyses pinpointed the strengths and weaknesses of each method and indicated that the Gini correlation can compensate for the shortcomings of the Pearson correlation, the Spearman correlation, the Kendall correlation, and the Tukey's biweight correlation. The Gini correlation method, with the other four evaluated methods in this study, was implemented as an R package named rsgcc that can be utilized as an alternative option for biologists to perform clustering analyses of gene expression patterns or transcriptional network analyses.
Ma, Chuang; Wang, Xiangfeng
2012-01-01
One of the computational challenges in plant systems biology is to accurately infer transcriptional regulation relationships based on correlation analyses of gene expression patterns. Despite several correlation methods that are applied in biology to analyze microarray data, concerns regarding the compatibility of these methods with the gene expression data profiled by high-throughput RNA transcriptome sequencing (RNA-Seq) technology have been raised. These concerns are mainly due to the fact that the distribution of read counts in RNA-Seq experiments is different from that of fluorescence intensities in microarray experiments. Therefore, a comprehensive evaluation of the existing correlation methods and, if necessary, introduction of novel methods into biology is appropriate. In this study, we compared four existing correlation methods used in microarray analysis and one novel method called the Gini correlation coefficient on previously published microarray-based and sequencing-based gene expression data in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). The comparisons were performed on more than 11,000 regulatory relationships in Arabidopsis, including 8,929 pairs of transcription factors and target genes. Our analyses pinpointed the strengths and weaknesses of each method and indicated that the Gini correlation can compensate for the shortcomings of the Pearson correlation, the Spearman correlation, the Kendall correlation, and the Tukey’s biweight correlation. The Gini correlation method, with the other four evaluated methods in this study, was implemented as an R package named rsgcc that can be utilized as an alternative option for biologists to perform clustering analyses of gene expression patterns or transcriptional network analyses. PMID:22797655
Energy Technology Data Exchange (ETDEWEB)
Žerovnik, Gašper, E-mail: gasper.zerovnik@ijs.si [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Trkov, Andrej, E-mail: andrej.trkov@ijs.si [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Smith, Donald L., E-mail: donald.l.smith@anl.gov [Argonne National Laboratory, 1710 Avenida del Mundo, Coronado, CA 92118-3073 (United States); Capote, Roberto, E-mail: roberto.capotenoy@iaea.org [NAPC–Nuclear Data Section, International Atomic Energy Agency, PO Box 100, Vienna-A-1400 (Austria)
2013-11-01
Inherently positive parameters with large relative uncertainties (typically ≳30%) are often considered to be governed by the lognormal distribution. This assumption has the practical benefit of avoiding the possibility of sampling negative values in stochastic applications. Furthermore, it is typically assumed that the correlation coefficients for comparable multivariate normal and lognormal distributions are equivalent. However, this ideal situation is approached only in the linear approximation which happens to be applicable just for small uncertainties. This paper derives and discusses the proper transformation of correlation coefficients between both distributions for the most general case which is applicable for arbitrary uncertainties. It is seen that for lognormal distributions with large relative uncertainties strong anti-correlations (negative correlations) are mathematically forbidden. This is due to the asymmetry that is an inherent feature of these distributions. Some implications of these results for practical nuclear applications are discussed and they are illustrated with examples in this paper. Finally, modifications to the ENDF-6 format used for representing uncertainties in evaluated nuclear data libraries are suggested, as needed to deal with this issue.
Chen, Lihua; Liu, Min; Bao, Jing; Xia, Yunbao; Zhang, Jiuquan; Zhang, Lin; Huang, Xuequan; Wang, Jian
2013-01-01
To perform a meta-analysis exploring the correlation between the apparent diffusion coefficient (ADC) and tumor cellularity in patients. We searched medical and scientific literature databases for studies discussing the correlation between the ADC and tumor cellularity in patients. Only studies that were published in English or Chinese prior to November 2012 were considered for inclusion. Summary correlation coefficient (r) values were extracted from each study, and 95% confidence intervals (CIs) were calculated. Sensitivity and subgroup analyses were performed to investigate potential heterogeneity. Of 189 studies, 28 were included in the meta-analysis, comprising 729 patients. The pooled r for all studies was -0.57 (95% CI: -0.62, -0.52), indicating notable heterogeneity (Pcorrelation between the ADC and cellularity for brain tumors. There was no notable evidence of publication bias. There is a strong negative correlation between the ADC and tumor cellularity in patients, particularly in the brain. However, larger, prospective studies are warranted to validate these findings in other cancer types.
International Nuclear Information System (INIS)
Žerovnik, Gašper; Trkov, Andrej; Smith, Donald L.; Capote, Roberto
2013-01-01
Inherently positive parameters with large relative uncertainties (typically ≳30%) are often considered to be governed by the lognormal distribution. This assumption has the practical benefit of avoiding the possibility of sampling negative values in stochastic applications. Furthermore, it is typically assumed that the correlation coefficients for comparable multivariate normal and lognormal distributions are equivalent. However, this ideal situation is approached only in the linear approximation which happens to be applicable just for small uncertainties. This paper derives and discusses the proper transformation of correlation coefficients between both distributions for the most general case which is applicable for arbitrary uncertainties. It is seen that for lognormal distributions with large relative uncertainties strong anti-correlations (negative correlations) are mathematically forbidden. This is due to the asymmetry that is an inherent feature of these distributions. Some implications of these results for practical nuclear applications are discussed and they are illustrated with examples in this paper. Finally, modifications to the ENDF-6 format used for representing uncertainties in evaluated nuclear data libraries are suggested, as needed to deal with this issue
Paech, Daniel; Burth, Sina; Windschuh, Johannes; Meissner, Jan-Eric; Zaiss, Moritz; Eidel, Oliver; Kickingereder, Philipp; Nowosielski, Martha; Wiestler, Benedikt; Sahm, Felix; Floca, Ralf Omar; Neumann, Jan-Oliver; Wick, Wolfgang; Heiland, Sabine; Bendszus, Martin; Schlemmer, Heinz-Peter; Ladd, Mark Edward; Bachert, Peter; Radbruch, Alexander
2015-01-01
To explore the correlation between Nuclear Overhauser Enhancement (NOE)-mediated signals and tumor cellularity in glioblastoma utilizing the apparent diffusion coefficient (ADC) and cell density from histologic specimens. NOE is one type of chemical exchange saturation transfer (CEST) that originates from mobile macromolecules such as proteins and might be associated with tumor cellularity via altered protein synthesis in proliferating cells. For 15 patients with newly diagnosed glioblastoma, NOE-mediated CEST-contrast was acquired at 7 Tesla (asymmetric magnetization transfer ratio (MTRasym) at 3.3ppm, B1 = 0.7 μT). Contrast enhanced T1 (CE-T1), T2 and diffusion-weighted MRI (DWI) were acquired at 3 Tesla and coregistered. The T2 edema and the CE-T1 tumor were segmented. ADC and MTRasym values within both regions of interest were correlated voxelwise yielding the correlation coefficient rSpearman (rSp). In three patients who underwent stereotactic biopsy, cell density of 12 specimens per patient was correlated with corresponding MTRasym and ADC values of the biopsy site. Eight of 15 patients showed a weak or moderate positive correlation of MTRasym and ADC within the T2 edema (0.16≤rSp≤0.53, pcorrelations were statistically insignificant (p>0.05, n = 4) or yielded rSp≈0 (pcorrelation between MTRasym and ADC was found in CE-T1 tumor (-0.310.05, n = 6). The biopsy-analysis within CE-T1 tumor revealed a strong positive correlation between tumor cellularity and MTRasym values in two of the three patients (rSppatient3 = 0.69 and rSppatient15 = 0.87, pcorrelation of ADC and cellularity was heterogeneous (rSppatient3 = 0.545 (p = 0.067), rSppatient4 = -0.021 (p = 0.948), rSppatient15 = -0.755 (p = 0.005)). NOE-imaging is a new contrast promising insight into pathophysiologic processes in glioblastoma regarding cell density and protein content, setting itself apart from DWI. Future studies might be based on the assumption that NOE-mediated CEST visualizes
Research on the Fusion of Dependent Evidence Based on Rank Correlation Coefficient
Directory of Open Access Journals (Sweden)
Fengjian Shi
2017-10-01
Full Text Available In order to meet the higher accuracy and system reliability requirements, the information fusion for multi-sensor systems is an increasing concern. Dempster–Shafer evidence theory (D–S theory has been investigated for many applications in multi-sensor information fusion due to its flexibility in uncertainty modeling. However, classical evidence theory assumes that the evidence is independent of each other, which is often unrealistic. Ignoring the relationship between the evidence may lead to unreasonable fusion results, and even lead to wrong decisions. This assumption severely prevents D–S evidence theory from practical application and further development. In this paper, an innovative evidence fusion model to deal with dependent evidence based on rank correlation coefficient is proposed. The model first uses rank correlation coefficient to measure the dependence degree between different evidence. Then, total discount coefficient is obtained based on the dependence degree, which also considers the impact of the reliability of evidence. Finally, the discount evidence fusion model is presented. An example is illustrated to show the use and effectiveness of the proposed method.
Research on the Fusion of Dependent Evidence Based on Rank Correlation Coefficient.
Shi, Fengjian; Su, Xiaoyan; Qian, Hong; Yang, Ning; Han, Wenhua
2017-10-16
In order to meet the higher accuracy and system reliability requirements, the information fusion for multi-sensor systems is an increasing concern. Dempster-Shafer evidence theory (D-S theory) has been investigated for many applications in multi-sensor information fusion due to its flexibility in uncertainty modeling. However, classical evidence theory assumes that the evidence is independent of each other, which is often unrealistic. Ignoring the relationship between the evidence may lead to unreasonable fusion results, and even lead to wrong decisions. This assumption severely prevents D-S evidence theory from practical application and further development. In this paper, an innovative evidence fusion model to deal with dependent evidence based on rank correlation coefficient is proposed. The model first uses rank correlation coefficient to measure the dependence degree between different evidence. Then, total discount coefficient is obtained based on the dependence degree, which also considers the impact of the reliability of evidence. Finally, the discount evidence fusion model is presented. An example is illustrated to show the use and effectiveness of the proposed method.
Comparison of the methods for calculating the interfacial heat transfer coefficient in hot stamping
International Nuclear Information System (INIS)
Zhao, Kunmin; Wang, Bin; Chang, Ying; Tang, Xinghui; Yan, Jianwen
2015-01-01
This paper presents a hot stamping experimentation and three methods for calculating the Interfacial Heat Transfer Coefficient (IHTC) of 22MnB5 boron steel. Comparison of the calculation results shows an average error of 7.5% for the heat balance method, 3.7% for the Beck's nonlinear inverse estimation method (the Beck's method), and 10.3% for the finite-element-analysis-based optimization method (the FEA method). The Beck's method is a robust and accurate method for identifying the IHTC in hot stamping applications. The numerical simulation using the IHTC identified by the Beck's method can predict the temperature field with a high accuracy. - Highlights: • A theoretical formula was derived for direct calculation of IHTC. • The Beck's method is a robust and accurate method for identifying IHTC. • Finite element method can be used to identify an overall equivalent IHTC
Determination of the interfacial heat transfer coefficient in the hot stamping of AA7075
Directory of Open Access Journals (Sweden)
Liu Xiaochuan
2015-01-01
Full Text Available The interfacial heat transfer coefficient (IHTC is a key parameter in hot stamping processes, in which a hot blank is formed and quenched by cold dies simultaneously. The IHTC should therefore be identified and used in FE models to improve the accuracy of simulation results of hot stamping processes. In this work, a hot stamping simulator was designed and assembled in a Gleeble 3800 thermo-mechanical testing system and a FE model was built in PAM-STAMP to determine the IHTC value between a hot aluminium alloy 7075 blank and cold dies. The IHTC was determined at different contact pressures under both dry and lubricated (Omega-35 conditions. In addition, a model to calculate the IHTC value at different contact pressures and area densities of lubricant was developed for the hot stamping process.
Determination of the Interfacial Heat Transfer Coefficient in the Hot Stamping of AA7075
Directory of Open Access Journals (Sweden)
Ji Kang
2016-01-01
Full Text Available The interfacial heat transfer coefficient (IHTC is a key parameter in hot stamping processes, in which a hot blank is formed and quenched by cold dies simultaneously. The IHTC should therefore be identified and used in FE simulations to improve the accuracy of simulation results of hot stamping processes. In this work, a hot stamping simulator was designed and assembled in a Gleeble 3800 thermo-mechanical testing system and a FE model was built in PAM-STAMP to determine the IHTC values between a hot aluminium alloy 7075 blank and cold dies. The IHTC values were determined at different contact pressures under both dry and lubricated (Omega-35 conditions. In addition, a model to calculate the IHTC value at different contact pressures and area densities of lubricant was developed for the hot stamping process, which was proved to be working well with verification tests.
Transfer coefficient of 137Cs and 40K from feed to milk in Kakrapar Gujarat site
International Nuclear Information System (INIS)
Wagh, S.S.; Patra, A.K.; John, Jaison T.; Ravi, P.M.; Tripathi, R.M.
2018-01-01
117 Cs is one of the most important contaminant from nuclear fall out because of its long physical half-life, affinity for biological systems and its uptake to man through diet. Cesium behaves like Potassium because of its similar physical and chemical properties. One of the important ingestion pathways of 137 Cs is grass to cow, cow to milk and exposed to man due to consumption of milk. Therefore it is necessary to measure the concentration of 137 Cs in grass and milk samples and to calculate the dose to human being due to the consumption of milk. This paper presents 137 Cs and 40 K concentration in feed and milk samples and the respective site-specific transfer coefficients from feed to milk for Kakrapar Gujarat Site
Characterization of the interfacial heat transfer coefficient for hot stamping processes
Luan, Xi; Liu, Xiaochuan; Fang, Haomiao; Ji, Kang; El Fakir, Omer; Wang, LiLiang
2016-08-01
In hot stamping processes, the interfacial heat transfer coefficient (IHTC) between the forming tools and hot blank is an essential parameter which determines the quenching rate of the process and hence the resulting material microstructure. The present work focuses on the characterization of the IHTC between an aluminium alloy 7075-T6 blank and two different die materials, cast iron (G3500) and H13 die steel, at various contact pressures. It was found that the IHTC between AA7075 and cast iron had values 78.6% higher than that obtained between AA7075 and H13 die steel. Die materials and contact pressures had pronounced effects on the IHTC, suggesting that the IHTC can be used to guide the selection of stamping tool materials and the precise control of processing parameters.
Directory of Open Access Journals (Sweden)
E. Hetmaniok
2012-12-01
Full Text Available A procedure based on the Artificial Bee Colony algorithm for solving the two-phase axisymmetric one-dimensional inverse Stefanproblem with the third kind boundary condition is presented in this paper. Solving of the considered problem consists in reconstruction of the function describing the heat transfer coefficient appearing in boundary condition of the third kind in such a way that the reconstructed values of temperature would be as closed as possible to the measurements of temperature given in selected points of the solid. A crucial part of the solution method consists in minimizing some functional which will be executed with the aid of one of the swarm intelligence algorithms - the ABC algorithm.
International Nuclear Information System (INIS)
Gao, W.M.; Kong, L.X.; Hodgson, P.D.
2006-01-01
The heat-transfer coefficients around a workpiece immersed in an electrically heated heat treatment fluidised bed were studied. A suspension probe designed to simulate a workpiece of complex geometry was developed to measure local total and radiative heat-transfer coefficients at a high bed temperature. The probe consisted of an energy-storage region separated by insulation from the fluidised bed, except for the measuring surface, and a multi-thermocouple measurement system. Experiments in the fluidised bed were performed for a fluidising medium of 120-mesh alumina, a wide temperature range of 110-1050 deg. C and a fluidising number range of 1.18-4.24. It was found that the workpiece surface temperature has a more significant effect on heat transfer than the bed temperature. The total heat-transfer coefficient at the upper surface of the workpiece sharply decreased at the start of heating, and then steadily increased as heating progressed, while a sharp decrease became a rapid increase and then a slow increase for the radiative heat-transfer coefficient. A great difference in the heat-transfer coefficients around the workpiece was observed
Zhao, Yu Xi; Xie, Ping; Sang, Yan Fang; Wu, Zi Yi
2018-04-01
Hydrological process evaluation is temporal dependent. Hydrological time series including dependence components do not meet the data consistency assumption for hydrological computation. Both of those factors cause great difficulty for water researches. Given the existence of hydrological dependence variability, we proposed a correlationcoefficient-based method for significance evaluation of hydrological dependence based on auto-regression model. By calculating the correlation coefficient between the original series and its dependence component and selecting reasonable thresholds of correlation coefficient, this method divided significance degree of dependence into no variability, weak variability, mid variability, strong variability, and drastic variability. By deducing the relationship between correlation coefficient and auto-correlation coefficient in each order of series, we found that the correlation coefficient was mainly determined by the magnitude of auto-correlation coefficient from the 1 order to p order, which clarified the theoretical basis of this method. With the first-order and second-order auto-regression models as examples, the reasonability of the deduced formula was verified through Monte-Carlo experiments to classify the relationship between correlation coefficient and auto-correlation coefficient. This method was used to analyze three observed hydrological time series. The results indicated the coexistence of stochastic and dependence characteristics in hydrological process.
Comparison of values of Pearson’s and Spearman’s correlation coefficient on the same sets of data
Hauke, Jan; Kossowski, Tomasz
2011-01-01
Spearman’s rank correlation coefficient is a nonparametric (distribution-free) rank statistic proposed by Charles Spearman as a measure of the strength of an association between two variables. It is a measure of a monotone association that is used when the distribution of data makes Pearson’s correlation coefficient undesirable or misleading. Spearman’s coefficient is not a measure of the linear relationship between two variables, as some “statisticians” declare. It assesses how well an arbit...
Measurement of the polarization correlation coefficient in elastic pp scattering at 610 MeV
International Nuclear Information System (INIS)
Borisov, N.S.; Glonti, L.N.; Kazarinov, M.Yu.
1977-01-01
The polarization correlation coefficient Csub(nn) for elastic pp scattering at 610+-10 MeV was measured for four scattering angles: 40, 67, 78 and 90 deg (c.m.s.). A polarized proton beam with a maximum polarization of 0.39+-0.02 and a polarized proton target of the frozen type were used. The maximum polarization of the target was 0.97+-0.04. The experimental procedure is described in detail. The Csub(nn) measured are compared with the results of a phase analysis and the findings at 575 MeV obtained elsewhere. The Csub(nn) coefficients are shown to be valuable to discriminate alternative solutions of the phase analysis. The polarized proton targets of the frozen type, no accounting the complexity of their design, are emphasized to be rather reliable and convenient devices for conducting experiments at accelerators
SPSS and SAS programs for comparing Pearson correlations and OLS regression coefficients.
Weaver, Bruce; Wuensch, Karl L
2013-09-01
Several procedures that use summary data to test hypotheses about Pearson correlations and ordinary least squares regression coefficients have been described in various books and articles. To our knowledge, however, no single resource describes all of the most common tests. Furthermore, many of these tests have not yet been implemented in popular statistical software packages such as SPSS and SAS. In this article, we describe all of the most common tests and provide SPSS and SAS programs to perform them. When they are applicable, our code also computes 100 × (1 - α)% confidence intervals corresponding to the tests. For testing hypotheses about independent regression coefficients, we demonstrate one method that uses summary data and another that uses raw data (i.e., Potthoff analysis). When the raw data are available, the latter method is preferred, because use of summary data entails some loss of precision due to rounding.
Energy Technology Data Exchange (ETDEWEB)
Ju, Yun Jae; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of); Kang, Hanok; Lee, Taeho; Park, Cheontae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2013-12-15
Recently, condensation heat exchangers have been studied for applications to the passive cooling systems of nuclear plants. To design vertical-type condensation heat exchangers in secondary passive cooling systems, TSCON (Thermal Sizing of CONdenser), a thermal sizing program for a condensation heat exchanger, was developed at KAERI (Korea Atomic Energy Research Institute). In this study, the existing condensation heat transfer correlation of TSCON was evaluated using 1,157 collected experimental data points from the heat exchanger of a secondary passive cooling system for the case of pure steam condensation. The investigation showed that the Shah correlation, published in 2009, provided the most satisfactory results for the heat transfer coefficient with a mean absolute error of 34.8%. It is suggested that the Shah correlation is appropriate for designing a condensation heat exchanger in TSCON.
Comparative analysis of heat transfer correlations for forced convection boiling
International Nuclear Information System (INIS)
Guglielmini, G.; Nannei, E.; Pisoni, C.
1978-01-01
A critical survey was conducted of the most relevant correlations of boiling heat transfer in forced convection flow. Most of the investigations carried out on partial nucleate boiling and fully developed nucleate boiling have led to the formulation of correlations that are not able to cover a wide range of operating conditions, due to the empirical approach of the problem. A comparative analysis is therefore required in order to delineate the relative accuracy of the proposed correlations, on the basis of the experimental data presently available. The survey performed allows the evaluation of the accuracy of the different calculating procedure; the results obtained, moreover, indicate the most reliable heat transfer correlations for the different operating conditions investigated. This survey was developed for five pressure range (up to 180bar) and for both saturation and subcooled boiling condition
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.
Aliya, F; Begum, H; Reddy, M T; Sivaraj, N; Pandravada, S R; Narshimulu, G
2014-05-01
Fifty genotypes of spine gourd (Momordica dioica Roxb.) were evaluated in a randomized block design with two replications at the Vegetable Research Station, Rajendranagar, Hyderabad, Andhra Pradesh, India during kharif, 2012. Correlation and path coefficient analysis were carried out to study the character association and contribution, respectively for twelve quantitative characters namely vine length (m), number of stems per plant, days to first female flower appearance, first female flowering node, days to first fruit harvest, days to last fruit harvest, fruiting period (days), fruit length (cm), fruit width (cm), fruit weight (g), number of fruits per plant and fruit yield per plant (kg) for identification of the potential selection indices. Correlation and path coefficient analyses revealed that fruiting period and number of fruits per plant not only had positively significant correlation with fruit yield but also had positively high direct effect on it and are regarded as the main determinants of fruit yield. Days to first fruit harvest had positively moderate direct effect on fruit yield and its association was negatively significant, days to last fruit harvest had negatively high direct effect on fruit yield and its association was significant positively, hence restricted simultaneous selection can be made for days to first fruit harvest and days to last fruit harvest. The improvement in fruit yield can be effective if selection is based on days to first fruit harvest, days to last fruit harvest, fruiting period and number of fruits per plant.
International Nuclear Information System (INIS)
Park, Ki Jung; Lee, Yohan; Jung, Dong Soo; Shim, Sang Eun
2011-01-01
In this study, the nucleate pool boiling heat transfer coefficients (HTCs) and critical heat flux (CHF) for a smooth and square flat heater in a pool of pure water with and without carbon nanotubes (CNTs) dispersed at 60 .deg. C were measured. Tested aqueous nanofluids were prepared using CNTs with volume concentrations of 0.0001%, 0.001%, and 0.01%. The CNTs were dispersed by chemically treating them with an acid in the absence of any polymers. The results showed that the pool boiling HTCs of the nanofluids are higher than those of pure water in the entire nucleate boiling regime. The acid-treated CNTs led to the deposition of a small amount of CNTs on the surface, and the CNTs themselves acted as heat-transfer-enhancing particles, owing to their very high thermal conductivity. There was a significant increase in the CHF- up to 150%-when compared to that of pure water containing CNTs with a volume concentration of 0.001%. This is attributed to the change in surface characteristics due to the deposition of a very thin layer of CNTs on the surface. This layer delays nucleate boiling and causes a reduction in the size of the large vapor canopy around the CHF. This results in a significant increase in the CHF
Samsudin, Hayati; Auras, Rafael; Burgess, Gary; Dolan, Kirk; Soto-Valdez, Herlinda
2018-03-01
A two-step solution based on the boundary conditions of Crank's equations for mass transfer in a film was developed. Three driving factors, the diffusion (D), partition (K p,f ) and convective mass transfer coefficients (h), govern the sorption and/or desorption kinetics of migrants from polymer films. These three parameters were simultaneously estimated. They provide in-depth insight into the physics of a migration process. The first step was used to find the combination of D, K p,f and h that minimized the sums of squared errors (SSE) between the predicted and actual results. In step 2, an ordinary least square (OLS) estimation was performed by using the proposed analytical solution containing D, K p,f and h. Three selected migration studies of PLA/antioxidant-based films were used to demonstrate the use of this two-step solution. Additional parameter estimation approaches such as sequential and bootstrap were also performed to acquire a better knowledge about the kinetics of migration. The proposed model successfully provided the initial guesses for D, K p,f and h. The h value was determined without performing a specific experiment for it. By determining h together with D, under or overestimation issues pertaining to a migration process can be avoided since these two parameters are correlated. Copyright © 2017 Elsevier Ltd. All rights reserved.
Correlation coefficient based supervised locally linear embedding for pulmonary nodule recognition.
Wu, Panpan; Xia, Kewen; Yu, Hengyong
2016-11-01
Dimensionality reduction techniques are developed to suppress the negative effects of high dimensional feature space of lung CT images on classification performance in computer aided detection (CAD) systems for pulmonary nodule detection. An improved supervised locally linear embedding (SLLE) algorithm is proposed based on the concept of correlation coefficient. The Spearman's rank correlation coefficient is introduced to adjust the distance metric in the SLLE algorithm to ensure that more suitable neighborhood points could be identified, and thus to enhance the discriminating power of embedded data. The proposed Spearman's rank correlation coefficient based SLLE (SC(2)SLLE) is implemented and validated in our pilot CAD system using a clinical dataset collected from the publicly available lung image database consortium and image database resource initiative (LICD-IDRI). Particularly, a representative CAD system for solitary pulmonary nodule detection is designed and implemented. After a sequential medical image processing steps, 64 nodules and 140 non-nodules are extracted, and 34 representative features are calculated. The SC(2)SLLE, as well as SLLE and LLE algorithm, are applied to reduce the dimensionality. Several quantitative measurements are also used to evaluate and compare the performances. Using a 5-fold cross-validation methodology, the proposed algorithm achieves 87.65% accuracy, 79.23% sensitivity, 91.43% specificity, and 8.57% false positive rate, on average. Experimental results indicate that the proposed algorithm outperforms the original locally linear embedding and SLLE coupled with the support vector machine (SVM) classifier. Based on the preliminary results from a limited number of nodules in our dataset, this study demonstrates the great potential to improve the performance of a CAD system for nodule detection using the proposed SC(2)SLLE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
On the construction of bivariate exponential distributions with an arbitrary correlation coefficient
DEFF Research Database (Denmark)
Bladt, Mogens; Nielsen, Bo Friis
In this paper we use a concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... coefficient (also negative). Secondly, the class satisfies that any linear combination (projection) of the marginal random variables is a phase {type distributions, The latter property is potentially important for the development hypothesis testing in linear models. Thirdly, it is very easy to simulate...
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2018-04-05
The concordance correlation coefficient (CCC) is a widely used scaled index in the study of agreement. In this article, we propose estimating the CCC by a unified Bayesian framework that can (1) accommodate symmetric or asymmetric and light- or heavy-tailed data; (2) select model from several candidates; and (3) address other issues frequently encountered in practice such as confounding covariates and missing data. The performance of the proposal was studied and demonstrated using simulated as well as real-life biomarker data from a clinical study of an insomnia drug. The implementation of the proposal is accessible through a package in the Comprehensive R Archive Network.
Frontal Face Detection using Haar Wavelet Coefficients and Local Histogram Correlation
Directory of Open Access Journals (Sweden)
Iwan Setyawan
2011-12-01
Full Text Available Face detection is the main building block on which all automatic systems dealing with human faces is built. For example, a face recognition system must rely on face detection to process an input image and determine which areas contain human faces. These areas then become the input for the face recognition system for further processing. This paper presents a face detection system designed to detect frontal faces. The system uses Haar wavelet coefficients and local histogram correlation as differentiating features. Our proposed system is trained using 100 training images. Our experiments show that the proposed system performed well during testing, achieving a detection rate of 91.5%.
Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J
BACKGROUND: Dry ice-ethanol bath (-78 degree C) have been widely used in low temperature biological research to attain rapid cooling of samples below freezing temperature. The prediction of cooling rates of biological samples immersed in dry ice-ethanol bath is of practical interest in cryopreservation. The cooling rate can be obtained using mathematical models representing the heat conduction equation in transient state. Additionally, at the solid cryogenic-fluid interface, the knowledge of the surface heat transfer coefficient (h) is necessary for the convective boundary condition in order to correctly establish the mathematical problem. The study was to apply numerical modeling to obtain the surface heat transfer coefficient of a dry ice-ethanol bath. A numerical finite element solution of heat conduction equation was used to obtain surface heat transfer coefficients from measured temperatures at the center of polytetrafluoroethylene and polymethylmetacrylate cylinders immersed in a dry ice-ethanol cooling bath. The numerical model considered the temperature dependence of thermophysical properties of plastic materials used. A negative linear relationship is observed between cylinder diameter and heat transfer coefficient in the liquid bath, the calculated h values were 308, 135 and 62.5 W/(m 2 K) for PMMA 1.3, PTFE 2.59 and 3.14 cm in diameter, respectively. The calculated heat transfer coefficients were consistent among several replicates; h in dry ice-ethanol showed an inverse relationship with cylinder diameter.
Koral, Korgün; Mathis, Derek; Gimi, Barjor; Gargan, Lynn; Weprin, Bradley; Bowers, Daniel C; Margraf, Linda
2013-08-01
To test whether there is correlation between cell densities and apparent diffusion coefficient (ADC) metrics of common pediatric cerebellar tumors. This study was reviewed for issues of patient safety and confidentiality and was approved by the Institutional Review Board of the University of Texas Southwestern Medical Center and was compliant with HIPAA. The need for informed consent was waived. Ninety-five patients who had preoperative magnetic resonance imaging and surgical pathologic findings available between January 2003 and June 2011 were included. There were 37 pilocytic astrocytomas, 34 medulloblastomas (23 classic, eight desmoplastic-nodular, two large cell, one anaplastic), 17 ependymomas (13 World Health Organization [WHO] grade II, four WHO grade III), and seven atypical teratoid rhabdoid tumors. ADCs of solid tumor components and normal cerebellum were measured. Tumor-to-normal brain ADC ratios (hereafter, ADC ratio) were calculated. The medulloblastomas and ependymomas were subcategorized according to the latest WHO classification, and tumor cellularity was calculated. Correlation was sought between cell densities and mean tumor ADCs, minimum tumor ADCs, and ADC ratio. When all tumors were considered together, negative correlation was found between cellularity and mean tumor ADCs (ρ = -0.737, P correlation between cellularity and ADC ratio. Negative correlation was found between cellularity and minimum tumor ADC in atypical teratoid rhabdoid tumors (ρ = -0.786, P correlation was found between cellularity and mean tumor ADC and ADC ratio. There was no correlation between the ADC metrics and cellularity of the pilocytic astrocytomas, medulloblastomas, and ependymomas. Negative correlation was found between cellularity and ADC metrics of common pediatric cerebellar tumors. Although ADC metrics are useful in the preoperative diagnosis of common pediatric cerebellar tumors and this utility is generally attributed to differences in cellularity of tumors
Sun, Xuelian; Liu, Zixian
2016-02-01
In this paper, a new estimator of correlation matrix is proposed, which is composed of the detrended cross-correlation coefficients (DCCA coefficients), to improve portfolio optimization. In contrast to Pearson's correlation coefficients (PCC), DCCA coefficients acquired by the detrended cross-correlation analysis (DCCA) method can describe the nonlinear correlation between assets, and can be decomposed in different time scales. These properties of DCCA make it possible to improve the investment effect and more valuable to investigate the scale behaviors of portfolios. The minimum variance portfolio (MVP) model and the Mean-Variance (MV) model are used to evaluate the effectiveness of this improvement. Stability analysis shows the effect of two kinds of correlation matrices on the estimation error of portfolio weights. The observed scale behaviors are significant to risk management and could be used to optimize the portfolio selection.
Systematic bias of correlation coefficient may explain negative accuracy of genomic prediction.
Zhou, Yao; Vales, M Isabel; Wang, Aoxue; Zhang, Zhiwu
2017-09-01
Accuracy of genomic prediction is commonly calculated as the Pearson correlation coefficient between the predicted and observed phenotypes in the inference population by using cross-validation analysis. More frequently than expected, significant negative accuracies of genomic prediction have been reported in genomic selection studies. These negative values are surprising, given that the minimum value for prediction accuracy should hover around zero when randomly permuted data sets are analyzed. We reviewed the two common approaches for calculating the Pearson correlation and hypothesized that these negative accuracy values reflect potential bias owing to artifacts caused by the mathematical formulas used to calculate prediction accuracy. The first approach, Instant accuracy, calculates correlations for each fold and reports prediction accuracy as the mean of correlations across fold. The other approach, Hold accuracy, predicts all phenotypes in all fold and calculates correlation between the observed and predicted phenotypes at the end of the cross-validation process. Using simulated and real data, we demonstrated that our hypothesis is true. Both approaches are biased downward under certain conditions. The biases become larger when more fold are employed and when the expected accuracy is low. The bias of Instant accuracy can be corrected using a modified formula. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Kotsalos, Efthimios; Brezovska, Boryana; Sevastos, Dimitrios; Vagena, Artemis; Koliadima, Athanasia; Kapolos, John; Karaiskakis, George
2017-11-17
This work focuses on the influences of surfactants on the activity coefficients, γ, of methanol in binary mixtures with water, as well as on the mass transfer coefficients, k c , for the evaporation of methanol, which is a ubiquitous component in the troposphere, from mixtures of methanol with water at various surfactant's and methanol's concentrations. The technique used is the Reversed-Flow Gas Chromatography (R.F.G.C.), a version of Inverse Gas Chromatography, which allows determining both parameters by performing only one experiment for the k c parameter and two experiments for the γ parameter. The k c and γ values decrease in the presence of the three surfactants used (CTAB, SDS, TRITON X-100) at all methanol's and surfactant's concentrations. The decrease in the methanol's molar fraction, at constant number of surfactant films leads to a decrease in the k c and γ values, while the decrease in the surfactant's concentration, at constant methanol's molar fraction leads to an increase in both the k c and γ parameters. Mass transfer coefficients for the evaporation of methanol at the surfactant films, are also calculated which are approximately between 4 and 5 orders of magnitude larger than the corresponding mass transfer coefficients at the liquid films. Finally, thicknesses of the boundary layer of methanol in the mixtures of methanol with water were determined. The quantities found are compared with those given in the literature or calculated theoretically using various empirical equations. The precision of the R.F.G.C. method for measuring γ and k c parameters is approximately high (94.3-98.0%), showing that R.F.G.C. can be used with success not only for the thermodynamic study of solutions, but also for the interphase transport. Copyright © 2017 Elsevier B.V. All rights reserved.
Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu
2016-07-15
The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values. Copyright © 2016 Elsevier Ltd. All rights reserved.
Supercritical heat transfer correlation for carbon dioxide flowing upward in a vertical tube
International Nuclear Information System (INIS)
Mokry, S. J.; Pioro, I. L.; Farah, A.; King, K.
2010-01-01
The objective of the current study was to analyze heat-transfer at supercritical conditions using carbon dioxide as a modeling fluid, and to develop a heat-transfer correlation based on data published in open literature. Supercritical (SC) fluids have unique properties. Beyond the critical point (22.1 MPa and 374.1 deg.C for water and 7.38 MPa and 31.0 deg.C for carbon dioxide), the fluid resembles a dense gas. The transition from single-phase liquid to single-phase gas does not involve a distinct phase change under these conditions. Phenomena such as dryout (or critical heat flux) are therefore not relevant. However, at supercritical conditions, deteriorated heat-transfer regime, (i.e., lower Heat Transfer Coefficient (HTC) values, compared to those for the normal or regular heat-transfer regime) may exist. Experiments with Supercritical Water (SCW) are very expensive due to high critical parameters. Therefore, a number of experiments are performed in modeling fluids such as carbon dioxide or/and refrigerants. However, there is no common opinion if SC modeling fluids' correlations can be applied to SCW and vice versa. Thus, the objective of this work was to generalize SC carbon dioxide data with a new correlation, and also, to compare these data with SCW correlations The experimental data was analyzed, and a new correlation was developed as part of a larger project assessing the feasibility of Generation IV SCW reactor concepts. Results are given for supercritical heat-transfer for several combinations of wall and bulk-fluid temperatures that were below, at or above the pseudo critical temperature. Uncertainties of all primary parameters were estimated. Two modes of heat transfer at supercritical pressures have been identified: (I) Normal Heat Transfer (NHT), and (2) Deteriorated Heat Transfer (DHT) characterized by lower-than-expected HTCs (i.e., higher-than-expected wall temperatures) than in the normal heat-transfer regime. These heat-transfer data are
Edjabou, Maklawe Essonanawe; Martín-Fernández, Josep Antoni; Scheutz, Charlotte; Astrup, Thomas Fruergaard
2017-11-01
Data for fractional solid waste composition provide relative magnitudes of individual waste fractions, the percentages of which always sum to 100, thereby connecting them intrinsically. Due to this sum constraint, waste composition data represent closed data, and their interpretation and analysis require statistical methods, other than classical statistics that are suitable only for non-constrained data such as absolute values. However, the closed characteristics of waste composition data are often ignored when analysed. The results of this study showed, for example, that unavoidable animal-derived food waste amounted to 2.21±3.12% with a confidence interval of (-4.03; 8.45), which highlights the problem of the biased negative proportions. A Pearson's correlation test, applied to waste fraction generation (kg mass), indicated a positive correlation between avoidable vegetable food waste and plastic packaging. However, correlation tests applied to waste fraction compositions (percentage values) showed a negative association in this regard, thus demonstrating that statistical analyses applied to compositional waste fraction data, without addressing the closed characteristics of these data, have the potential to generate spurious or misleading results. Therefore, ¨compositional data should be transformed adequately prior to any statistical analysis, such as computing mean, standard deviation and correlation coefficients. Copyright © 2017 Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Cipolla, Valentina, E-mail: valentina.cipolla@yahoo.it [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Santucci, Domiziana; Guerrieri, Daniele; Drudi, Francesco Maria [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Meggiorini, Maria Letizia [Department of Gynaecological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Felice, Carlo de [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy)
2014-12-15
Highlights: • Apparent diffusion coefficient is a quantitative parameter which reflects molecular water movement. • Grading is an independent prognostic factor which correlates with other histopathological features. • Apparent diffusion coefficient values were significantly different between G1 and G3 classes. - Abstract: Purpose: The aim of this study was to evaluate whether the apparent diffusion coefficient (ADC) provided by 3.0 T (3 T) magnetic resonance diffusion-weighted imaging (DWI) varied according to the grading of invasive breast carcinoma. Materials and methods: A total of 92 patients with 96 invasive breast cancer lesions were enrolled; all had undergone 3 T magnetic resonance imaging (MRI) for local staging. All lesions were confirmed by histological analysis, and tumor grade was established according to the Nottingham Grading System (NGS). MRI included both dynamic contrast-enhanced and DWI sequences, and ADC value was calculated for each lesion. ADC values were compared with NGS classification using the Mann–Whitney U and the Kruskal–Wallis H tests. Grading was considered as a comprehensive prognostic factor, and Rho Spearman test was performed to determine correlation between grading and tumor size, hormonal receptor status, HER2 expression and Ki67 index. Pearson's Chi square test was carried out to compare grading with the other prognostic factors. Results: ADC values were significantly higher in G1 than in G3 tumors. No significant difference was observed when G1 and G3 were compared with G2. Tumor size, hormonal receptor status, HER2 expression and Ki67 index correlated significantly with grading but there was a significant difference only between G1 and G3 related to the ER and PR status, HER2 expression and Ki67 index. There was no statistically significant difference in lesion size between the two groups. Conclusion: ADC values obtained on 3 T DWI correlated with low-grade (G1) and high-grade (G3) invasive breast carcinoma. 3
A comprehensive examination of heat transfer correlations suitable for reactor safety analysis
International Nuclear Information System (INIS)
Groeneveld, D.C.; Snoek, C.W.
1986-01-01
Due to the inadequate understanding of heat transfer mechanisms, an empirical approach is often necessary. This approach requires the derivation of empirical heat transfer correlations for each heat transfer configuration, resulting in numerous correlations for each heat transfer mode. A simplification that is frequently used is to combine these heat transfer correlations using some suitably defined local parameters to characterize the heat transfer process. These local condition correlations, usually encountered in reactor safety codes are discussed in this paper
International Nuclear Information System (INIS)
Korun, M.; Vodenik, B.; Zorko, B.
2016-01-01
Two simple methods for calculating the correlations between peaks appearing in gamma-ray spectra are described. We show how the areas are correlated when the peaks do not overlap, but the spectral regions used for the calculation of the background below the peaks do. When the peaks overlap, the correlation can be stronger than in the case of the non-overlapping peaks. The methods presented are simplified to the extent of allowing their implementation with manual calculations. They are intended for practitioners as additional tools to be used when the correlations between the areas of the peaks in the gamma-ray spectra are to be calculated. Also, the correlation coefficient between the number of counts in the peak and the number of counts in the continuous background below the peak is derived. - Highlights: • The correlation coefficients between areas of closely spaced peaks are assessed. • For isolated peaks the correlation arises from the common continuous background. • If peaks overlap the correlation coefficient depends on how much they overlap. • If peaks overlap also the background height affects the correlation coefficient. • The correlation coefficient between the peak area and its background is −1.
Directory of Open Access Journals (Sweden)
G. Srinivasa Rao
2011-12-01
Full Text Available The forced convection heat transfer coefficient and friction factor are determined for the flow of water and nanofluid in a vertical packed bed column. The analysis is undertaken in the laminar and transition Reynolds number range. The column is filled with spherical glass beads as the bed material. The heat transfer coefficients with Al2O3 nanofluid increased by 12% to 15% with the increase of volume concentration from 0.02% to 0.5% compared with water. The experimental values of axial temperature are in good agreement with the NTU-ε method proposed by Schumann’s model.
Kishimoto, Keiko; Tajima, Shinya; Maeda, Ichiro; Takagi, Masayuki; Ueno, Takahiko; Suzuki, Nao; Nakajima, Yasuo
2016-08-01
Diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) are widely used for detecting uterine endometrial cancer. The relationships between ADC values and pathological features of endometrial cancer have not yet been established. To investigate whether ADC values of endometrial cancer vary according to histologic tumor cellularity and tumor grade. We retrospectively reviewed 30 pathologically confirmed endometrial cancers. All patients underwent conventional non-enhanced magnetic resonance imaging (MRI) and DWI procedures, and ADC values were calculated. Tumor cellularity was evaluated by counting cancer cells in three high-power ( × 400) fields. The correlation between ADC values and tumor cellularity was assessed using Pearson's correlation coefficient test for statistical analysis. The mean ± standard deviation (SD) ADC value ( ×10(-3) mm(2)/s) of endometrial cancer was 0.85 ± 0.22 (range, 0.55-1.71). The mean ± SD tumor cellularity was 528.36 ± 16.89 (range, 298.0-763.6). ADC values were significantly inversely correlated with tumor cellularity. No significant relationship was observed between ADC values and tumor grade (mean ADC values: G1, 0.88 ± 0.265 × 10(-3) mm(2)/s; G2, 0.80 ± 0.178 × 10(-3) mm(2)/s; G3, 0.81 ± 0.117 × 10(-3) mm(2)/s). There is a significant inverse relationship between ADC values and tumor cellularity in endometrial cancer. No significant differences in average ADC value were observed between G1, G2, and G3 tumors. However, the lower the tumor grade, the wider the SD. © The Foundation Acta Radiologica 2015.
Zhao, Qile; Guo, Jing; Hu, Zhigang; Shi, Chuang; Liu, Jingnan; Cai, Hua; Liu, Xianglin
2011-05-01
The GRACE (Gravity Recovery And Climate Experiment) monthly gravity models have been independently produced and published by several research institutions, such as Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), Centre National d’Etudes Spatiales (CNES) and Delft Institute of Earth Observation and Space Systems (DEOS). According to their processing standards, above institutions use the traditional variational approach except that the DEOS exploits the acceleration approach. The background force models employed are rather similar. The produced gravity field models generally agree with one another in the spatial pattern. However, there are some discrepancies in the gravity signal amplitude between solutions produced by different institutions. In particular, 10%-30% signal amplitude differences in some river basins can be observed. In this paper, we implemented a variant of the traditional variational approach and computed two sets of monthly gravity field solutions using the data from January 2005 to December 2006. The input data are K-band range-rates (KBRR) and kinematic orbits of GRACE satellites. The main difference in the production of our two types of models is how to deal with nuisance parameters. This type of parameters is necessary to absorb low-frequency errors in the data, which are mainly the aliasing and instrument errors. One way is to remove the nuisance parameters before estimating the geopotential coefficients, called NPARB approach in the paper. The other way is to estimate the nuisance parameters and geopotential coefficients simultaneously, called NPESS approach. These two types of solutions mainly differ in geopotential coefficients from degree 2 to 5. This can be explained by the fact that the nuisance parameters and the gravity field coefficients are highly correlated, particularly at low degrees. We compare these solutions with the official and published ones by means of spectral analysis. It is
DEFF Research Database (Denmark)
Nielsen, Anders Michael; Nielsen, Lars Peter; Feilberg, Anders
2009-01-01
A membrane inlet mass spectrometer (MIMS) was used in combination with a developed computer model to study and improve management of a biofilter (BF) treating malodorous ventilation air from a meat rendering facility. The MIMS was used to determine percentage removal efficiencies (REs) of selected...... sulfur gases and to provide toluene retention profiles for the model to determine the air velocity and overall mass-transfer coefficient of toluene. The mass-transfer coefficient of toluene was used as a reference for determining the mass transfer of sulfur gases. By presenting the model to scenarios...... of a filter bed with a consortium of effective sulfur oxidizers, the most likely mechanism for incomplete removal of sulfur compounds from the exhaust air was elucidated. This was found to be insufficient mass transfer and not inadequate bacterial activity as anticipated by the manager of the BF. Thus...
Experimentally Determined Overall Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments
Bue, Grant; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vogel, Matt; Vonaue, Walt; Conger, Bruce; Stein, James
2015-01-01
A Human-In-The-Loop (HITL) Portable Life Support System 2.0 (PLSS 2.0) test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014 to December 19, 2014. These closed-loop tests of the PLSS 2.0 system integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure but effluent water vapor from the Spacesuit Water Membrane Evaporator (SWME) and the Auxiliary Membrane Evaporator (Mini-ME), and effluent carbon dioxide from the Rapid Cycle Amine (RCA) were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the overall heat transfer coefficient (UA) of the Liquid Cooling Garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flow rate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit (EMU) LCG, the Oceaneering Space Systems (OSS) LCG, and the OSS auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.
Noda, Nao-Aki; Hendra; Li, Wenbin; Takase, Yasushi; Ogura, Hiroki; Higashi, Yusuke
Low pressure die casting is defined as a net shape casting technology in which the molten metal is injected at high speeds and pressure into a metallic die. The low pressure die casting process plays an increasingly important role in the foundry industry as a low-cost and high-efficiency precision forming technique. In the low pressure die casting process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal, by means of a pressurized gas, to rise into a ceramic tube having protuberance, which connects the die to the furnace. The ceramics tube, called stalk, has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the stalk having protuberance is dipped into the molten aluminum. It is important to reduce the risk of fracture that may happen due to the thermal stresses. In this paper, thermo-fluid analysis is performed to calculate surface heat transfer coefficient. The finite element method is applied to calculate the thermal stresses when the stalk having protuberance is dipped into the crucible with varying dipping speeds. It is found that the stalk with or without protuberance should be dipped into the crucible slowly to reduce the thermal stress.
Er. Shivesh Kumar; Dr. Amit Kumar
2016-01-01
Since centuries steam is being used in power generating system. The steam leaving the power unit is reconverted into water in a condenser designed to transfer heat from the steam to the cooling water as rapidly and as efficiently as possible. The efficiency of condenser depends on rate of condensation and mode of condensation of steam in the condenser. The increase in efficiency of the condenser enhances the heat transfer co-efficient which in turn results in economic design of condenser and ...
Model for definition of heat transfer coefficient in an annular two-phase flow
International Nuclear Information System (INIS)
Khun, J.
1976-01-01
Near-wall heat exchange in a vertical tube at high vapor velocity in a two-phase vapor and liquid flow is investigated. The flow divides inside the tube into a near-wall liquid film and a vapor nucleus containing liquid droplets, with the boundaries being uniform. The liquid film thickness determines the main resistance during heat transfer between the wall and vapor nucleus. The theoretical model presented is verified in water vaporization experiments, the R12 cooling agent and certain hydrocarbons. The loss of friction pressure is determined by the Lockart-Martinelli method. The approximately universal Carman velocity profile is used to evaluate the velocity in film, and basing on this, film thickness is determined. The parameter ranges were: Resub(vap)=10 4 -3x10 6 , Resub(liq.)=0.9-10. The theoretical model ensures good correlation with the experiment
Chen, Yingyuan; Cai, Lihui; Wang, Ruofan; Song, Zhenxi; Deng, Bin; Wang, Jiang; Yu, Haitao
2018-01-01
Alzheimer's disease (AD) is a degenerative disorder of neural system that affects mainly the older population. Recently, many researches show that the EEG of AD patients can be characterized by EEG slowing, enhanced complexity of the EEG signals, and EEG synchrony. In order to examine the neural synchrony at multi scales, and to find a biomarker that help detecting AD in diagnosis, detrended cross-correlation analysis (DCCA) of EEG signals is applied in this paper. Several parameters, namely DCCA coefficients in the whole brain, DCCA coefficients at a specific scale, maximum DCCA coefficient over the span of all time scales and the corresponding scale of such coefficients, were extracted to examine the synchronization, respectively. The results show that DCCA coefficients have a trend of increase as scale increases, and decreases as electrode distance increases. Comparing DCCA coefficients in AD patients with healthy controls, a decrease of synchronization in the whole brain, and a bigger scale corresponding to maximum correlation is discovered in AD patients. The change of max-correlation scale may relate to the slowing of oscillatory activities. Linear combination of max DCCA coefficient and max-correlation scale reaches a classification accuracy of 90%. From the above results, it is reasonable to conclude that DCCA coefficient reveals the change of both oscillation and synchrony in AD, and thus is a powerful tool to differentiate AD patients from healthy elderly individuals.
Raykov, Tenko; Marcoulides, George A.
2015-01-01
A latent variable modeling procedure that can be used to evaluate intraclass correlation coefficients in two-level settings with discrete response variables is discussed. The approach is readily applied when the purpose is to furnish confidence intervals at prespecified confidence levels for these coefficients in setups with binary or ordinal…
Spatial correlation in 3D MIMO channels using fourier coefficients of power spectrums
Nadeem, Qurrat-Ul-Ain
2015-03-01
In this paper, an exact closed-form expression for the Spatial Correlation Function (SCF) is derived for the standardized three-dimensional (3D) multiple-input multiple-output (MIMO) channel. This novel SCF is developed for a uniform linear array of antennas with non-isotropic antenna patterns. The proposed method resorts to the spherical harmonic expansion (SHE) of plane waves and the trigonometric expansion of Legendre and associated Legendre polynomials to obtain a closed-form expression for the SCF for arbitrary angular distributions and antenna patterns. The resulting expression depends on the underlying angular distributions and antenna patterns through the Fourier Series (FS) coefficients of power azimuth and elevation spectrums. The novelty of the proposed method lies in the SCF being valid for any 3D propagation environment. Numerical results validate the proposed analytical expression and study the impact of angular spreads on the correlation. The derived SCF will help evaluate the performance of correlated 3D MIMO channels in the future. © 2015 IEEE.
Rahman, Md Mostafizur; Fattah, Shaikh Anowarul
2017-01-01
In view of recent increase of brain computer interface (BCI) based applications, the importance of efficient classification of various mental tasks has increased prodigiously nowadays. In order to obtain effective classification, efficient feature extraction scheme is necessary, for which, in the proposed method, the interchannel relationship among electroencephalogram (EEG) data is utilized. It is expected that the correlation obtained from different combination of channels will be different for different mental tasks, which can be exploited to extract distinctive feature. The empirical mode decomposition (EMD) technique is employed on a test EEG signal obtained from a channel, which provides a number of intrinsic mode functions (IMFs), and correlation coefficient is extracted from interchannel IMF data. Simultaneously, different statistical features are also obtained from each IMF. Finally, the feature matrix is formed utilizing interchannel correlation features and intrachannel statistical features of the selected IMFs of EEG signal. Different kernels of the support vector machine (SVM) classifier are used to carry out the classification task. An EEG dataset containing ten different combinations of five different mental tasks is utilized to demonstrate the classification performance and a very high level of accuracy is achieved by the proposed scheme compared to existing methods.
Kim, Mimi; Kang, Tae Wook; Kim, Young Kon; Kim, Seong Hyun; Kwon, Wooil; Ha, Sang Yun; Ji, Sang A
2016-03-01
To evaluate the correlation between grade of pancreatic neuroendocrine tumours (pNETs) based on the 2010 World Health Organization (WHO) classification and the apparent diffusion coefficient (ADC), and to assess whether the ADC value and WHO classification can predict recurrence-free survival (RFS) after surgery for pNETs. This retrospective study was approved by the Institutional Review Board. The requirement for informed consent was waived. Between March 2009 and November 2014, forty-nine patients who underwent magnetic resonance (MR) imaging with diffusion-weighted image and subsequent surgery for single pNETs were included. Correlations among qualitative MR imaging findings, quantitative ADC values, and WHO classifications were assessed. An ordered logistic regression test was used to control for tumour size as a confounding factor. The association between ADC value (or WHO classification) and RFS was analysed. All tumors (n=49) were classified as low- (n=29, grade 1), intermediate- (n=17, grade 2), and high-grade (n=3, grade 3), respectively. The mean ADC of pNETs was moderately negatively correlated with WHO classification before and after adjustment for tumour size (ρ=-0.64, pcorrelated with WHO tumour grade, regardless of tumour size. However, the WHO tumour classification of pNET may be more suitable for predicting RFS than the ADC value. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Oggioni, Marco R; Coelho, Joana Rosado; Furi, Leonardo; Knight, Daniel R; Viti, Carlo; Orefici, Graziella; Martinez, Jose-Luis; Freitas, Ana Teresa; Coque, Teresa M; Morrissey, Ian
2015-01-01
There is a growing concern by regulatory authorities for the selection of antibiotic resistance caused by the use of biocidal products. We aimed to complete the detailed information on large surveys by investigating the relationship between biocide and antibiotic susceptibility profiles of a large number of Staphylococcus aureus isolates using four biocides and antibiotics commonly used in clinical practice. The minimal inhibitory concentration (MIC) for most clinically-relevant antibiotics was determined according to the standardized methodology for over 1600 clinical S. aureus isolates and compared to susceptibility profiles of benzalkonium chloride, chlorhexidine, triclosan, and sodium hypochlorite. The relationship between antibiotic and biocide susceptibility profiles was evaluated using non-linear correlations. The main outcome evidenced was an absence of any strong or moderate statistically significant correlation when susceptibilities of either triclosan or sodium hypochlorite were compared for any of the tested antibiotics. On the other hand, correlation coefficients for MICs of benzalkonium chloride and chlorhexidine were calculated above 0.4 for susceptibility to quinolones, beta-lactams, and also macrolides. Our data do not support any selective pressure for association between biocides and antibiotics resistance and furthermore do not allow for a defined risk evaluation for some of the compounds. Importantly, our data clearly indicate that there does not involve any risk of selection for antibiotic resistance for the compounds triclosan and sodium hypochlorite. These data hence infer that biocide selection for antibiotic resistance has had so far a less significant impact than feared.
Genetic Variability, Correlation Studies and Path Coefficient Analysis in Gladiolus Alatus Cultivars
International Nuclear Information System (INIS)
Ramzan, A.; Nawab, N. N.; Tariq, M. S.; Ikram, S.; Ahad, A.
2016-01-01
A study was undertaken to find out the estimates of genetic variability, genetic parameters and character association among different flower traits between three gladiolus cultivars viz: Sancerre, Fado and Advanced Red. The experiment was repeated three times by using RCBD (Randomized complete block design) at Department of Horticulture, PMAS-UAAR, Rawalpindi. The highest genotypic coefficient variation (GCV) and phenotypic coefficient variation (PCV) magnitude was observed for spike length (16.00) and number of florets per spike (14.84) followed by number of leaves (10.00). Among the traits studied the highest heritability estimates was recorded in spike length (99.5 percent) followed by number of florets/spike (99.6 percent) and lowest in plant height (98.2 percent). The genetic advance as percent of mean was ranged from 2.8 percent to 24.75 percent. Genetic advance was highest for floret breadth (24.75 percent) and lowest for plant height (2.8 percent). High heritability combined with high genetic advance was noticed for number of florets per spike, spike length and floret breadth indicating additive gene action which suggested that improvement of these traits would be effective for further selection of superior genotypes. Plant height and number of florets per spike showed highly positive and significant association with spike length, number of leaves, leaf area, floret length and floret breadth while, spike length registered positive and significant correlation with number of leaves and floret breadth. The path coefficient analysis based on spike length, as responsible variable exposed that all of the traits exerted direct positive effect except leaf area and floret length. Spike length imparted maximum positive direct effect on the number of florets per spike. Hence, spike length and number of florets per spike may be considered for further improvement. However, Floret length and floret breadth may also be considered as a criterion for selection. (author)
Vispoel, Walter P; Morris, Carrie A; Kilinc, Murat
2018-05-02
Over the years, research in the social sciences has been dominated by reporting of reliability coefficients that fail to account for key sources of measurement error. Use of these coefficients, in turn, to correct for measurement error can hinder scientific progress by misrepresenting true relationships among the underlying constructs being investigated. In the research reported here, we addressed these issues using generalizability theory (G-theory) in both traditional and new ways to account for the three key sources of measurement error (random-response, specific-factor, and transient) that affect scores from objectively scored measures. Results from 20 widely used measures of personality, self-concept, and socially desirable responding showed that conventional indices consistently misrepresented reliability and relationships among psychological constructs by failing to account for key sources of measurement error and correlated transient errors within occasions. The results further revealed that G-theory served as an effective framework for remedying these problems. We discuss possible extensions in future research and provide code from the computer package R in an online supplement to enable readers to apply the procedures we demonstrate to their own research.
Saadat, Mostafa; Zendeh-Boodi, Zahra
2006-09-01
The aim of the study is to obtain more insight into the possible association between consanguinity and the incidence of deliberate self-burning. Data were obtained by analysis of medical records of patients hospitalized in two referral burn centers: Chormy Burn Center (Bushehr Province, south of Iran) from March 21, 1998, through March 20, 2004, and Shahid Sadoqi Center of Burns and Injuries (Yazd Province, center of Iran) from March 21, 2000, through March 20, 2004. The incidence of suicidal burns was 6.51 and 2.32/100,000 person-years for Bushehr and Yazd Provinces, respectively. The observed sex ratio of patients in both centers indicated there was a female predominance in patients with self-inflicted burns. Using patients' home addresses, patients were sorted into 16 cities. The incidence of suicide by self-burning ranged from 0.80 (for Tabas, located in Yazd Province) to 12.60/100,000 person-years (for Dilam, located in Bushehr Province). The coefficient of inbreeding defines the probability that an individual received both alleles of a pair from an identical ancestral source. There was a significant correlation between incidences of suicidal burns and mean coefficient of inbreeding (r = 0.782, df = 14, p < 0.001). In addition to other factors, consanguineous marriage may be a risk factor that influences the incidence of suicidal burns in a population.
Liang, Yunyun; Liu, Sanyang; Zhang, Shengli
2016-12-01
Apoptosis, or programed cell death, plays a central role in the development and homeostasis of an organism. Obtaining information on subcellular location of apoptosis proteins is very helpful for understanding the apoptosis mechanism. The prediction of subcellular localization of an apoptosis protein is still a challenging task, and existing methods mainly based on protein primary sequences. In this paper, we introduce a new position-specific scoring matrix (PSSM)-based method by using detrended cross-correlation (DCCA) coefficient of non-overlapping windows. Then a 190-dimensional (190D) feature vector is constructed on two widely used datasets: CL317 and ZD98, and support vector machine is adopted as classifier. To evaluate the proposed method, objective and rigorous jackknife cross-validation tests are performed on the two datasets. The results show that our approach offers a novel and reliable PSSM-based tool for prediction of apoptosis protein subcellular localization. Copyright © 2016 Elsevier Inc. All rights reserved.
Li, Yuxing; Li, Yaan; Chen, Xiao; Yu, Jing
2017-12-26
As the sound signal of ships obtained by sensors contains other many significant characteristics of ships and called ship-radiated noise (SN), research into a denoising algorithm and its application has obtained great significance. Using the advantage of variational mode decomposition (VMD) combined with the correlation coefficient for denoising, a hybrid secondary denoising algorithm is proposed using secondary VMD combined with a correlation coefficient (CC). First, different kinds of simulation signals are decomposed into several bandwidth-limited intrinsic mode functions (IMFs) using VMD, where the decomposition number by VMD is equal to the number by empirical mode decomposition (EMD); then, the CCs between the IMFs and the simulation signal are calculated respectively. The noise IMFs are identified by the CC threshold and the rest of the IMFs are reconstructed in order to realize the first denoising process. Finally, secondary denoising of the simulation signal can be accomplished by repeating the above steps of decomposition, screening and reconstruction. The final denoising result is determined according to the CC threshold. The denoising effect is compared under the different signal-to-noise ratio and the time of decomposition by VMD. Experimental results show the validity of the proposed denoising algorithm using secondary VMD (2VMD) combined with CC compared to EMD denoising, ensemble EMD (EEMD) denoising, VMD denoising and cubic VMD (3VMD) denoising, as well as two denoising algorithms presented recently. The proposed denoising algorithm is applied to feature extraction and classification for SN signals, which can effectively improve the recognition rate of different kinds of ships.
Directory of Open Access Journals (Sweden)
Yuxing Li
2017-12-01
Full Text Available As the sound signal of ships obtained by sensors contains other many significant characteristics of ships and called ship-radiated noise (SN, research into a denoising algorithm and its application has obtained great significance. Using the advantage of variational mode decomposition (VMD combined with the correlation coefficient for denoising, a hybrid secondary denoising algorithm is proposed using secondary VMD combined with a correlation coefficient (CC. First, different kinds of simulation signals are decomposed into several bandwidth-limited intrinsic mode functions (IMFs using VMD, where the decomposition number by VMD is equal to the number by empirical mode decomposition (EMD; then, the CCs between the IMFs and the simulation signal are calculated respectively. The noise IMFs are identified by the CC threshold and the rest of the IMFs are reconstructed in order to realize the first denoising process. Finally, secondary denoising of the simulation signal can be accomplished by repeating the above steps of decomposition, screening and reconstruction. The final denoising result is determined according to the CC threshold. The denoising effect is compared under the different signal-to-noise ratio and the time of decomposition by VMD. Experimental results show the validity of the proposed denoising algorithm using secondary VMD (2VMD combined with CC compared to EMD denoising, ensemble EMD (EEMD denoising, VMD denoising and cubic VMD (3VMD denoising, as well as two denoising algorithms presented recently. The proposed denoising algorithm is applied to feature extraction and classification for SN signals, which can effectively improve the recognition rate of different kinds of ships.
Tian, C.; Weng, J.; Liu, Y.
2017-11-01
The convection heat transfer coefficient is one of the evaluation indexes of the brake disc performance. The method used in this paper to calculate the convection heat transfer coefficient is a fluid-solid coupling simulation method, because the calculation results through the empirical formula method have great differences. The model, including a brake disc, a car body, a bogie and flow field, was built, meshed and simulated in the software FLUENT. The calculation models were K-epsilon Standard model and Energy model. The working condition of the brake disc was considered. The coefficient of various parts can be obtained through the method in this paper. The simulation result shows that, under 160 km/h speed, the radiating ribs have the maximum convection heat transfer coefficient and the value is 129.6W/(m2·K), the average coefficient of the whole disc is 100.4W/(m2·K), the windward of ribs is positive-pressure area and the leeward of ribs is negative-pressure area, the maximum pressure is 2663.53Pa.
Du, Yang; Xin, Ming Dao
1999-03-01
This paper developed a new type of three dimensional inner microfin tube. The experimental results of the flow patterns for the horizontal condensation inside these tubes are reported in the paper. The flow patterns for the horizontal condensation inside the new made tubes are divided into annular flow, stratified flow and intermittent flow within the test conditions. The experiments of the local heat transfer coefficients for the different flow patterns have been systematically carried out. The experiments of the local heat transfer coefficients changing with the vapor dryness fraction have also been carried out. As compared with the heat transfer coefficients of the two dimensional inner microfin tubes, those of the three dimensional inner microfin tubes increase 47-127% for the annular flow region, 38-183% for the stratified flow and 15-75% for the intermittent flow, respectively. The enhancement factor of the local heat transfer coefficients is from 1.8-6.9 for the vapor dryness fraction from 0.05 to 1.
Directory of Open Access Journals (Sweden)
Stella Crosara Lopes
2009-04-01
Full Text Available The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs of the metals and ceramics. Verabond (VB Ni-Cr-Be alloy, Verabond II (VB2, Ni-Cr alloy, Pors-on 4 (P, Pd-Ag alloy, and IPS (I and Duceram (D ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01 for the MCBS test results (MPa, with PI showing higher MCBS (67.72 than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1 differences were: VBI (0.54, VBD (1.33, VB2I (-0.14, VB2D (0.63, PI (1.84 and PD (2.62. Pearson's correlation test (r=0.17 was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.
Lopes, Stella Crosara; Pagnano, Valéria Oliveira; Rollo, João Manuel Domingos de Almeida; Leal, Mônica Barbosa; Bezzon, Osvaldo Luiz
2009-01-01
The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10(-6) oC(-1)) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.
R package to estimate intracluster correlation coefficient with confidence interval for binary data.
Chakraborty, Hrishikesh; Hossain, Akhtar
2018-03-01
The Intracluster Correlation Coefficient (ICC) is a major parameter of interest in cluster randomized trials that measures the degree to which responses within the same cluster are correlated. There are several types of ICC estimators and its confidence intervals (CI) suggested in the literature for binary data. Studies have compared relative weaknesses and advantages of ICC estimators as well as its CI for binary data and suggested situations where one is advantageous in practical research. The commonly used statistical computing systems currently facilitate estimation of only a very few variants of ICC and its CI. To address the limitations of current statistical packages, we developed an R package, ICCbin, to facilitate estimating ICC and its CI for binary responses using different methods. The ICCbin package is designed to provide estimates of ICC in 16 different ways including analysis of variance methods, moments based estimation, direct probabilistic methods, correlation based estimation, and resampling method. CI of ICC is estimated using 5 different methods. It also generates cluster binary data using exchangeable correlation structure. ICCbin package provides two functions for users. The function rcbin() generates cluster binary data and the function iccbin() estimates ICC and it's CI. The users can choose appropriate ICC and its CI estimate from the wide selection of estimates from the outputs. The R package ICCbin presents very flexible and easy to use ways to generate cluster binary data and to estimate ICC and it's CI for binary response using different methods. The package ICCbin is freely available for use with R from the CRAN repository (https://cran.r-project.org/package=ICCbin). We believe that this package can be a very useful tool for researchers to design cluster randomized trials with binary outcome. Copyright © 2017 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Lee, Youho; Lee, Jeong Ik; Cheon, Hee
2015-01-01
Accurate modeling of thermal shock induced stresses has become ever most important to emerging accident-tolerant ceramic cladding concepts, such as silicon carbide (SiC) and SiC coated zircaloy. Since fractures of ceramic (entirely ceramic or coated) occur by excessive tensile stresses with linear elasticity, modeling transient stress distribution in the material provides a direct indication of the structural integrity. Indeed, even for the current zircaloy cladding material, the oxide layer formed on the surface - where cracks starts to develop upon water quenching - essentially behaves as a brittle ceramic. Hence, enhanced understanding of thermal shock fracture of a brittle material would fundamentally contribute to safety of nuclear reactors for both the current fuel design and that of the coming future. Understanding thermal shock fracture of a brittle material requires heat transfer rate between the solid and the fluid for transient temperature fields of the solid, and structural response of the solid under the obtained transient temperature fields. In water quenching, a solid experiences dynamic time-varying heat transfer rates with phase changes of the fluid over a short quenching period. Yet, such a dynamic change of heat transfer rates during the water quenching transience has been overlooked in assessments of mechanisms, predictability, and uncertainties for thermal shock fracture. Rather, a time-constant heat transfer coefficient, named 'effective heat transfer coefficient' has become a conventional input to thermal shock fracture analysis. No single constant heat transfer could suffice to depict the actual stress evolution subject to dynamic heat transfer coefficient changes with fluid phase changes. Use of the surface temperature dependent heat transfer coefficient will remarkably increase predictability of thermal shock fracture of brittle materials and complete the picture of stress evolution in the quenched solid. The presented result
Energy Technology Data Exchange (ETDEWEB)
Lee, Youho; Lee, Jeong Ik; Cheon, Hee [KAIST, Daejeon (Korea, Republic of)
2015-05-15
Accurate modeling of thermal shock induced stresses has become ever most important to emerging accident-tolerant ceramic cladding concepts, such as silicon carbide (SiC) and SiC coated zircaloy. Since fractures of ceramic (entirely ceramic or coated) occur by excessive tensile stresses with linear elasticity, modeling transient stress distribution in the material provides a direct indication of the structural integrity. Indeed, even for the current zircaloy cladding material, the oxide layer formed on the surface - where cracks starts to develop upon water quenching - essentially behaves as a brittle ceramic. Hence, enhanced understanding of thermal shock fracture of a brittle material would fundamentally contribute to safety of nuclear reactors for both the current fuel design and that of the coming future. Understanding thermal shock fracture of a brittle material requires heat transfer rate between the solid and the fluid for transient temperature fields of the solid, and structural response of the solid under the obtained transient temperature fields. In water quenching, a solid experiences dynamic time-varying heat transfer rates with phase changes of the fluid over a short quenching period. Yet, such a dynamic change of heat transfer rates during the water quenching transience has been overlooked in assessments of mechanisms, predictability, and uncertainties for thermal shock fracture. Rather, a time-constant heat transfer coefficient, named 'effective heat transfer coefficient' has become a conventional input to thermal shock fracture analysis. No single constant heat transfer could suffice to depict the actual stress evolution subject to dynamic heat transfer coefficient changes with fluid phase changes. Use of the surface temperature dependent heat transfer coefficient will remarkably increase predictability of thermal shock fracture of brittle materials and complete the picture of stress evolution in the quenched solid. The presented result
Data Qualification Report For DTN: MO0012RIB00065.002, Parameter Values For Transfer Coefficients
International Nuclear Information System (INIS)
C.H. Tung
2001-01-01
A data-qualification evaluation was conducted on Reference Information Base (RIB) data set MOO0 12RIB00065.002, ''Parameter Values for Transfer Coefficients''. The corroborating data method was used to evaluate the data. This method was selected because it closely matches the literature-review method followed to select parameter values. Five criteria were considered when the corroborating method was used: adequacy of the corroborative literature, sufficiency of value-selection criteria, implementation of the selection criteria, documentation of the process, and whether the analysis was conducted in accordance with applicable quality assurance (QA) procedures. Three criteria were used when a literature review was not conducted: appropriate logic used to select parameters, documentation of the process, and whether the analysis was conducted in accordance with applicable QA procedures. The RIB data item, the associated Analysis and Model Report (AMR), the corroborative literature, and the results of an audit revision O/ICN--0 of the AMR were examined. All calculations and the selection process for all values were repeated and confirmed. The qualification team concluded: (1) A sufficient quantity of corroborative literature was reviewed and no additional literature was identified that should have been considered. (2) The selection criteria were sufficient and resulted in valid parameter values. (3) The process was well defined, adequately documented in the AMR, and correctly followed. (4) The analysis was developed in accordance with applicable QA procedures. No negative findings were documented that resulted in questions about the quality of the data. The qualification team therefore recommends that the qualification status of RIB data set MO0012RIB00065.002 be changed to qualified
International Nuclear Information System (INIS)
Kornienko, Y.
2000-01-01
The purpose has been to describe an approach suggested for constructing generalized closure relationships for local and subchannel wall friction, heat and mass transfer coefficients, with not only axial and transversal parameters taken into account, but azimuthal substance transfer effects as well. These constitutive relations that are primary for description of one- and two-phase one-dimensional flow models can be derived from the initial 3-D drift flux formulation. The approach is based on the Reynolds flux, boundary layer and generalized coefficient of substance transfer. One more task has been to illustrate the validity of the 'conformity principle' for the limiting cases. The method proposed is based on the similarity theory, boundary layer model, and a phenomenological description of the regularities of the substance transfer (momentum, heat, and mass), as well as on an adequate simulation of the forms of flow structure by a generalized approach to build (an integrated in form and semi-empirical in maintenance structure) analytical relationships for wall friction, heat and mass transfer coefficients. (author)
International Nuclear Information System (INIS)
Heidrich, P; Wolfersdorf, J v; Schmidt, S; Schnieder, M
2008-01-01
This paper describes a non-invasive, non-destructive, transient inverse measurement technique that allows one to determine internal heat transfer coefficients and rib positions of real gas turbine blades from outer surface temperature measurements after a sudden flow heating. The determination of internal heat transfer coefficients is important during the design process to adjust local heat transfer to spatial thermal load. The detection of rib positions is important during production to fulfill design and quality requirements. For the analysis the one-dimensional transient heat transfer problem inside of the turbine blade's wall was solved. This solution was combined with the Levenberg-Marquardt method to estimate the unknown boundary condition by an inverse technique. The method was tested with artificial data to determine uncertainties with positive results. Then experimental testing with a reference model was carried out. Based on the results, it is concluded that the presented inverse technique could be used to determine internal heat transfer coefficients and to detect rib positions of real turbine blades.
Li, Ang
2015-10-23
We present a detailed study on the transient heat transfer phenomena of powdered-adsorbent mixed with an organic binder for adherence to the fins of a heat exchangers. The transient performance of such an adsorbent-heat exchanger configuration has significant application potential in the adsorption desalination plants and chillers but seldom addressed in the literature. An experiment is designed to measure the heat transfer for several adsorption temperatures under a single vapor component environment. Analysis on the experimental data indicates that the adsorbent-adsorbate interactions contribute about 75% of the total thermal resistances throughout the uptake processes. It is found that the initial local adsorption heat transfer coefficients are significantly higher than the average values due primarily to the thermal mass effect of the adsorbent–adsorbate interaction layers. From these experiments, a correlation for the transient local adsorption heat transfer coefficients is presented at the sub-atmospheric pressures and assorted application temperatures.
Energy Technology Data Exchange (ETDEWEB)
Carvalho, Priscilla R.; Munita, Casimiro S.; Lapolli, André L., E-mail: prii.ramos@gmail.com, E-mail: camunita@ipen.br, E-mail: alapolli@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)
2017-07-01
The literature presents many methods for partitioning of data base, and is difficult choose which is the most suitable, since the various combinations of methods based on different measures of dissimilarity can lead to different patterns of grouping and false interpretations. Nevertheless, little effort has been expended in evaluating these methods empirically using an archaeological data base. In this way, the objective of this work is make a comparative study of the different cluster analysis methods and identify which is the most appropriate. For this, the study was carried out using a data base of the Archaeometric Studies Group from IPEN-CNEN/SP, in which 45 samples of ceramic fragments from three archaeological sites were analyzed by instrumental neutron activation analysis (INAA) which were determinate the mass fraction of 13 elements (As, Ce, Cr, Eu, Fe, Hf, La, Na, Nd, Sc, Sm, Th, U). The methods used for this study were: single linkage, complete linkage, average linkage, centroid and Ward. The validation was done using the cophenetic correlation coefficient and comparing these values the average linkage method obtained better results. A script of the statistical program R with some functions was created to obtain the cophenetic correlation. By means of these values was possible to choose the most appropriate method to be used in the data base. (author)
International Nuclear Information System (INIS)
Carvalho, Priscilla R.; Munita, Casimiro S.; Lapolli, André L.
2017-01-01
The literature presents many methods for partitioning of data base, and is difficult choose which is the most suitable, since the various combinations of methods based on different measures of dissimilarity can lead to different patterns of grouping and false interpretations. Nevertheless, little effort has been expended in evaluating these methods empirically using an archaeological data base. In this way, the objective of this work is make a comparative study of the different cluster analysis methods and identify which is the most appropriate. For this, the study was carried out using a data base of the Archaeometric Studies Group from IPEN-CNEN/SP, in which 45 samples of ceramic fragments from three archaeological sites were analyzed by instrumental neutron activation analysis (INAA) which were determinate the mass fraction of 13 elements (As, Ce, Cr, Eu, Fe, Hf, La, Na, Nd, Sc, Sm, Th, U). The methods used for this study were: single linkage, complete linkage, average linkage, centroid and Ward. The validation was done using the cophenetic correlation coefficient and comparing these values the average linkage method obtained better results. A script of the statistical program R with some functions was created to obtain the cophenetic correlation. By means of these values was possible to choose the most appropriate method to be used in the data base. (author)
Kunz, Cornelia U; Stallard, Nigel; Parsons, Nicholas; Todd, Susan; Friede, Tim
2017-03-01
Regulatory authorities require that the sample size of a confirmatory trial is calculated prior to the start of the trial. However, the sample size quite often depends on parameters that might not be known in advance of the study. Misspecification of these parameters can lead to under- or overestimation of the sample size. Both situations are unfavourable as the first one decreases the power and the latter one leads to a waste of resources. Hence, designs have been suggested that allow a re-assessment of the sample size in an ongoing trial. These methods usually focus on estimating the variance. However, for some methods the performance depends not only on the variance but also on the correlation between measurements. We develop and compare different methods for blinded estimation of the correlation coefficient that are less likely to introduce operational bias when the blinding is maintained. Their performance with respect to bias and standard error is compared to the unblinded estimator. We simulated two different settings: one assuming that all group means are the same and one assuming that different groups have different means. Simulation results show that the naïve (one-sample) estimator is only slightly biased and has a standard error comparable to that of the unblinded estimator. However, if the group means differ, other estimators have better performance depending on the sample size per group and the number of groups. © 2016 The Authors. Biometrical Journal Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
Xin Dai
2017-10-01
Full Text Available Maximum power transfer tracking (MPTT is meant to track the maximum power point during the system operation of wireless power transfer (WPT systems. Traditionally, MPTT is achieved by impedance matching at the secondary side when the load resistance is varied. However, due to a loosely coupling characteristic, the variation of coupling coefficient will certainly affect the performance of impedance matching, therefore MPTT will fail accordingly. This paper presents an identification method of coupling coefficient for MPTT in WPT systems. Especially, the two-value issue during the identification is considered. The identification approach is easy to implement because it does not require additional circuit. Furthermore, MPTT is easy to realize because only two easily measured DC parameters are needed. The detailed identification procedure corresponding to the two-value issue and the maximum power transfer tracking process are presented, and both the simulation analysis and experimental results verified the identification method and MPTT.
International Nuclear Information System (INIS)
Ward, G.M.; Johnson, J.E.
1985-01-01
The goat milk transfer coefficient of Tc administered as TcO 4 - was found to be 20 to 40 times that of Tc administered in a reduced form. The fraction of Tc, as TcO 4 - , transferred from gut to blood was approximately 6 to 10 times that of reduced Tc. The milk transfer coefficient of Tc administered as TcO 4 - was 6 to 8 times greater for goats than cows. The fraction of Tc, as TcO 4 - , absorbed from the gut by cows, however, was approximately twice that absorbed by goats. The mean time for loss of Tc in cows' milk based on the average values plotted in Figure 2 was approximately 10 hours. The fraction of Tc, administered as TcO 4 - , absorbed from blood to mammary gland by cows was estimated to be approximately 2% that of goats. 4 refs., 15 tabs
Directory of Open Access Journals (Sweden)
X. Y. Ji
2010-12-01
Full Text Available The gas-liquid two-phase mass transfer process in microchannels is complicated due to the special dynamical characteristics. In this work, a novel method was explored to measure the liquid side volumetric mass transfer coefficient kLa. Pressure transducers were utilized to measure the pressure variation of upward gas-liquid two-phase flow in three vertical rectangular microchannels and the liquid side volumetric mass transfer coefficient kLa was calculated through the Pressure-Volume-Temperature correlation of the gas phase. Carbon dioxide-water, carbon dioxide-ethanol and carbon dioxide-n-propanol were used as working fluids, respectively. The dimensions of the microchannels were 40 µm×240 µm (depth×width, 100 µm×800 µm and 100 µm×2000 µm, respectively. Results showed that the channel diameter and the capillary number influence kLa remarkably and that the maximum value of kLa occurs in the annular flow regime. A new correlation of kLa was proposed based on the Sherwood number, Schmidt number and the capillary number. The predicted values of kLa agreed well with the experimental data.
Heat Transfer Correlations for Free Convection from Suspended Microheaters
Directory of Open Access Journals (Sweden)
David GOSSELIN
2016-08-01
Full Text Available Portability and autonomy for biomedical diagnostic devices are two rising requirements. It is recognized that low-energy heating of such portable devices is of utmost importance for molecular recognition. This work focuses on screen-printed microheaters based on on Joule effect, which constitute an interesting solution for low-energy heating. An experimental study of the natural convection phenomena occurring with such microheaters is conducted. When they are suspended in the air, and because of the thinness of the supporting film, it is shown that the contributions of both the upward and downward faces have to be taken into account. A total Nusselt number and a total convective heat transfer coefficient have been used to describe the natural convection around these microheaters. In addition a relation between the Nusselt number and the Rayleigh number is derived, leading to an accurate prediction of the heating temperature (MRE< 2 %.
Nogueira, Bruno L; Pérez, Julio; van Loosdrecht, Mark C M; Secchi, Argimiro R; Dezotti, Márcia; Biscaia, Evaristo C
2015-09-01
In moving bed biofilm reactors (MBBR), the removal of pollutants from wastewater is due to the substrate consumption by bacteria attached on suspended carriers. As a biofilm process, the substrates are transported from the bulk phase to the biofilm passing through a mass transfer resistance layer. This study proposes a methodology to determine the external mass transfer coefficient and identify the influence of the mixing intensity on the conversion process in-situ in MBBR systems. The method allows the determination of the external mass transfer coefficient in the reactor, which is a major advantage when compared to the previous methods that require mimicking hydrodynamics of the reactor in a flow chamber or in a separate vessel. The proposed methodology was evaluated in an aerobic lab-scale system operating with COD removal and nitrification. The impact of the mixing intensity on the conversion rates for ammonium and COD was tested individually. When comparing the effect of mixing intensity on the removal rates of COD and ammonium, a higher apparent external mass transfer resistance was found for ammonium. For the used aeration intensities, the external mass transfer coefficient for ammonium oxidation was ranging from 0.68 to 13.50 m d(-1) and for COD removal 2.9 to 22.4 m d(-1). The lower coefficient range for ammonium oxidation is likely related to the location of nitrifiers deeper in the biofilm. The measurement of external mass transfer rates in MBBR will help in better design and evaluation of MBBR system-based technologies. Copyright © 2015 Elsevier Ltd. All rights reserved.
Correlation between apparent diffusion coefficients and HER2 status in gastric cancers: pilot study
International Nuclear Information System (INIS)
He, Jian; Shi, Hua; Zhou, Zhuping; Chen, Jun; Guan, Wenxian; Wang, Hao; Yu, Haiping; Liu, Song; Zhou, Zhengyang; Yang, Xiaofeng; Liu, Tian
2015-01-01
To evaluate whether apparent diffusion coefficient (ADC) value of gastric cancer obtained from diffusion weighted imaging (DWI) correlates with the HER2 status. Forty-five patients, who had been diagnosed with gastric cancer through biopsy, were enrolled in this IRB-approved study. Each patient underwent a DWI (b values: 0 and 1,000 sec/mm 2 ) prior to surgery (curative gastrectomy or palliative resection). Postoperative microscopic findings, HER2 status by immunohistochemical analysis and fluorescence in situ hybridization (FISH) were obtained. HER2 status was compared among gastric cancers with various histopathological features using the chi square test. The ADC values of gastric cancers with positive and negative HER2 were compared using the student t test. A weak yet significant correlation was observed between the mean ADC values and HER2 status (r = 0.312, P = 0.037) and scores (r = 0.419, P = 0.004). The mean ADC value of HER2-positive gastric cancers was significantly higher than those of HER2-negative tumors (1.211 vs. 0.984 mm 2 /s, P = 0.020). The minimal ADC value of HER2-positive gastric cancers was significantly higher than those of HER2-negative tumors (1.105 vs. 0.905 × 10 −3 mm 2 /s, P = 0.036). In this pilot study, we have demonstrated that the ADC values of gastric cancer correlate with the HER2 status. Future research is warranted to see if DWI can predict HER2 status and help in tailoring therapy for gastric cancer
Correlation properties of surface and percolation transfer of electrons
International Nuclear Information System (INIS)
Bakunin, O.G.
2002-01-01
In this work was received equation, connecting correlatively properties of surface with electrons distribution function. Usually for equilibrium is necessary a large number of collisions. Collisions are 'destroying' correlations. In case rare collisions large importance have correlations and 'memory' effects. Non-Markov's character of emitting particles by surface lead to strongly nonequilibrium condition of 'gas'. Here kinetic equation of diffusive form does not apply. Classical kinetic equation are described only conditions near to equilibrium. This work offers to use ideas anomal diffusion in phase-space. The correlation properties of surface describe by correlations of velocities of emitting electrons: B(t). We offer to use functional equation for probability collision instead of kinetic equation: ∫ 0 ν 0 W noncoll F(ν) dv = 1 - B(t). This functional allow to consider 'memory' effects. It is important for consideration of electrons and clusters near surfaces. Distribution function become direct connected with correlations. In classical Kubo-Mory theory of transfer is necessary to get nondivergences integral: D ∝ ∫ 0 ∞ B(t). In considering case we can use even 'power function'. It was used 'slow' correlation function as Kohlraush in calculations. The information about kinetics and correlations properties are containing in one functional equation. It was received solution of this equation in form Levy function: F(ν) ∝ 1/ν α exp(-1/ν). The solution of this form can not be get with help asymptotic methods of kinetic theory. Asymptotics of solution have scale-invariant character F(V) ∝ 1/V α . This indicate on fractal properties phase-space. (author)
International Nuclear Information System (INIS)
Baptista Filho, B.D.; Konuk, A.A.
1981-01-01
A new method to calculate pressure drop (Δp) and shell-side heat transfer coefficient (h sub(c)) in a shell-and-tube heat exchanger with segmental baffles is presented. The method is based on the solution of the equations of conservation of mass and momentum between two baffles. The calculated distributions of pressure and velocities given respectively, Δp and h sub(c). The values of Δp and h sub(c) are correlated for a given geometry whit the shell side fluid properties and flow rate. The calculated and experimental results agree very well for a U-Tube heat exchanger. (Author) [pt
MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS
Energy Technology Data Exchange (ETDEWEB)
Leishear, R.
2009-09-09
Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels.
MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS
International Nuclear Information System (INIS)
Leishear, R.
2009-01-01
Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels
HJELM, HOWARD; NORRIS, RAYMOND C.
THE STUDY EMPIRICALLY DETERMINED THE EFFECTS OF NONNORMALITY UPON SOME SAMPLING DISTRIBUTIONS OF THE PRODUCT MOMENT CORRELATION COEFFICIENT (PMCC). SAMPLING DISTRIBUTIONS OF THE PMCC WERE OBTAINED BY DRAWING NUMEROUS SAMPLES FROM CONTROL AND EXPERIMENTAL POPULATIONS HAVING VARIOUS DEGREES OF NONNORMALITY AND BY CALCULATING CORRELATION COEFFICIENTS…
Lee, Jung Gil; Jeong, Sanghyun; Alsaadi, Ahmad Salem; Ghaffour, NorEddine
2017-01-01
(>2.1×10−6kg/m2sPa: membranes under development) were simulated using an experimentally validated model at different ranges of convection heat transfer by varying the inlet flow rates and spacer enhancement factor. The effect of mass transfer
Subcooled boiling heat transfer correlation to calculate the effects of dissolved gas in a liquid
International Nuclear Information System (INIS)
Zarkasi, Amin S.; Chao, W.W.; Kunze, Jay F.
2004-01-01
The water coolant in most operating power reactor systems is kept free of dissolved gas, so as to minimize corrosion. However, in most research reactors, which operate at temperatures below 70 deg. C, and between 1 and 5 atm. pressure, the dissolved gas remains present in the water coolant system during operation. This dissolved gas can have a significant effect during accident conditions (i.e. a LOCA), when the fluid quickly reaches boiling, coincident with flow stagnation and subsequent flow reversal. A benchmark experiment was conducted, with an electrically heated, closed loop channel, modeling a research reactor fuel coolant channels (2 mm thick). The results showed 'boiling (bubble) noise' occurring before wall temperatures reached saturation, and a significant increase (up to 50%) in the heat transfer coefficient in the subcooled boiling region when in the presence of dissolved gas, compared to degassed water. Since power reactors do not involve dissolved gas, the RELAP safety analysis code does not include any provisions for the effect of dissolved gas on heat transfer. In this work, the effects of the dissolved gas are evaluated for inclusion in the RELAP code, including provision for initiating 'nucleate boiling' at a lower temperature, and a provision for enhancing the heat transfer coefficient during the subcooled boiling region. Instead of relying on Chen's correlation alone, a modification of the superposition method of Bjorge was adopted. (author)
Pal, Shyamali
2017-12-01
The presence of Macro prolactin is a significant cause of elevated prolactin resulting in misdiagnosis in all automated systems. Poly ethylene glycol (PEG) pretreatment is the preventive process but such process includes the probability of loss of a fraction of bioactive prolactin. Surprisingly, PEG treated EQAS & IQAS samples in Cobas e 411 are found out to be correlating with direct results of at least 3 immunoassay systems and treated and untreated Cobas e 411 results are comparable by a correlation coefficient. Comparison of EQAS, IQAS and patient samples were done to find out the trueness of such correlation factor. Study with patient's results have established the correlation coefficient is valid for very small concentration of prolactin also. EQAS, IQAS and 150 patient samples were treated with PEG and prolactin results of treated and untreated samples obtained from Roche Cobas e 411. 25 patient's results (treated) were compared with direct results in Advia Centaur, Architect I & Access2 systems. Correlation coefficient was obtained from trend line of the treated and untreated results. Two tailed p-value obtained from regression coefficient(r) and sample size. The correlation coefficient is in the range (0.761-0.771). Reverse correlation range is (1.289-1.301). r value of two sets of calculated results were 0.995. Two tailed p- value is zero approving dismissal of null hypothesis. The z-score of EQAS does not always assure authenticity of resultsPEG precipitation is correlated by the factor 0.761 even in very small concentrationsAbbreviationsGFCgel filtration chromatographyPEGpolyethylene glycolEQASexternal quality assurance systemM-PRLmacro prolactinPRLprolactinECLIAelectro-chemiluminescence immunoassayCLIAclinical laboratory improvement amendmentsIQASinternal quality assurance systemrregression coefficient.
The fuel to clad heat transfer coefficient in advanced MX-type fuel pins
International Nuclear Information System (INIS)
Caligara, F.; Campana, M.; Mandler, R.; Blank, H.
1979-01-01
Advanced fuels (mixed carbides, nitrides and carbonitrides) are characterised by a high thermal conductivity compared to that of oxide fuels (5 times greater) and their behaviour under irradiation (amount of swelling, fracture behaviour, restructuring) is far more sensitive to the design parameters and to the operating temperature than that of oxide fuels. The use of advanced fuels is therefore conditioned by the possibility of mastering the above phenomena, and the full exploitation of their favorable neutron characteristics depends upon a good understanding of the mutual relationships of the various parameters, which eventually affect the mechanical stability of the pin. By far the most important parameter is the radial temperature profile which controls the swelling of the fuel and the build-up of stress fields within the pin. Since the rate of fission gas swelling of these fuels is relatively large, a sufficient amount of free space has to be provided within the pin. This space originally appears as fabrication porosity and as fuel-to-clad clearance. Due to the large initial gap width and to the high fuel thermal conductivity, the range of the fuel operating temperatures is mainly determined by the fuel-to-clad heat transfer coefficient h, whose correct determination becomes one of the central points in modelling. During the many years of modelling activity in the field of oxide fuels, several theoretical models have been developed to calculate h, and a large amount of experimental data has been produced for the empirical adjustment of the parameters involved, so that the situation may be regarded as rather satisfactory. The analysis lead to the following conclusions. A quantitative comparison of experimental h-values with existing models for h requires rather sophisticated instrumented irradiation capsules, which permit the measurement of mechanical data (concerning fuel and clad) together with heat rating and temperatures. More and better well
Transfer coefficients of energy in mass for X radiation-air: the kV relation and effective energy
International Nuclear Information System (INIS)
Teixeira, G.J.; Sousa, C.H.S.; Peixoto, J.G.P.
2014-01-01
The objective was to determine, through specific software, the mass-energy transfer coefficients by X-ray beams in air between 30-150 kV. Were generated by the Spectrum Processor program, the spectra and calculated their mass coefficients. The results behaved numerically decreasing order, ranging between 0.3733 and 0.0439 cm 2 /g, inversely proportional to the voltage used and differing behavior of mono-energetic beams above 100 keV. Values align with literal definitions of the interaction of radiation with matter, being useful for dosimetry in diagnostic radiology, including for systems not using an ionization chamber. (author)
Meyer, Hans-Jonas; Ziemann, Oliver; Kornhuber, Malte; Emmer, Alexander; Quäschling, Ulf; Schob, Stefan; Surov, Alexey
2018-06-01
Background Magnetic resonance imaging (MRI) is widely used in several muscle disorders. Diffusion-weighted imaging (DWI) is an imaging modality, which can reflect microstructural tissue composition. The apparent diffusion coefficient (ADC) is used to quantify the random motion of water molecules in tissue. Purpose To investigate ADC values in patients with myositis and non-inflammatory myopathy and to analyze possible associations between ADC and laboratory parameters in these patients. Material and Methods Overall, 17 patients with several myositis entities, eight patients with non-inflammatory myopathies, and nine patients without muscle disorder as a control group were included in the study (mean age = 55.3 ± 14.3 years). The diagnosis was confirmed by histopathology in every case. DWI was obtained in a 1.5-T scanner using two b-values: 0 and 1000 s/mm 2 . In all patients, the blood sample was acquired within three days to the MRI. The following serological parameters were estimated: C-reactive protein, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, and myoglobine. Results The estimated mean ADC value for the myositis group was 1.89 ± 0.37 × 10 -3 mm 2 /s and for the non-inflammatory myopathy group was 1.79 ± 0.33 × 10 -3 mm 2 /s, respectively. The mean ADC values (1.15 ± 0.37 × 10 -3 mm 2 /s) were significantly higher to unaffected muscles (vs. myositis P = 0.0002 and vs. myopathy P = 0.0021). There were no significant correlations between serological parameters and ADC values. Conclusion Affected muscles showed statistically significantly higher ADC values than normal muscles. No linear correlations between ADC and serological parameters were identified.
Energy Technology Data Exchange (ETDEWEB)
Goshima, Satoshi [Department of Radiology, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan)], E-mail: gossy@par.odn.ne.jp; Kanematsu, Masayuki [Department of Radiology, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Kondo, Hiroshi [Department of Radiology, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Yokoyama, Ryujiro; Kajita, Kimihiro [Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Tsuge, Yusuke [Department of Radiology, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194 (Japan); Shiratori, Yoshimune [Department of Medical Informatics, Gifu University School of Medicine, Gifu (Japan); Onozuka, Minoru [Department of Physiology and Neuroscience, Kanagawa Dental College, Yokosuka (Japan); Moriyama, Noriyuki [Research Center for Cancer Prevention and Screening, National Cancer Center Hospital, Tsukiji (Japan)
2009-05-15
Purpose: To correlate hepatic hemangioma enhancement types in gadolinium-enhanced magnetic resonance (MR) images with diffusion-weighted MR findings and apparent diffusion coefficients (ADCs). Materials and methods: Respiratory-triggered diffusion-weighted MR images (TR/TE, 2422/46 ms; parallel imaging factor, 2; b factor, 500 s/mm{sup 2}; number of averaging, 6) obtained in 35 patients with 44 hepatic hemangiomas diagnosed by gadolinium-enhanced MR and by follow-up imaging were retrospectively evaluated. Hemangiomas were classified into three enhancement types based on gadolinium-enhanced MR imaging findings: type I, early-enhancement type; type II, peripheral nodular enhancement type; type III, delayed enhancement type. Two blinded readers qualitatively assessed lesion sizes and signal intensities on T2-weighted turbo spin-echo and diffusion-weighted images. The ADCs of hemangiomas were also measured. Results: No significant difference was observed between the three enhancement types in terms of signal intensities on T2-weighted images. Signal intensities on diffusion-weighted images were lower in the order type I to III (P < .01), and mean ADCs were 2.18 x 10{sup -3}, 1.86 x 10{sup -3}, and 1.71 x 10{sup -3} mm{sup 2}/s for types I, II, and III, respectively (P < .01). No correlation was found between lesion sizes and ADCs. Conclusion: Hepatic hemangiomas were found to have enhancement type dependent signal intensities and ADCs on diffusion-weighted MR images. Further studies will have to substantiate that these diffusion patterns might reflect intratumoral blood flow or perfusion.
Rana, Santosh; Dhanotia, Jitendra; Bhatia, Vimal; Prakash, Shashi
2018-04-01
In this paper, we propose a simple, fast, and accurate technique for detection of collimation position of an optical beam using the self-imaging phenomenon and correlation analysis. Herrera-Fernandez et al. [J. Opt.18, 075608 (2016)JOOPDB0150-536X10.1088/2040-8978/18/7/075608] proposed an experimental arrangement for collimation testing by comparing the period of two different self-images produced by a single diffraction grating. Following their approach, we propose a testing procedure based on correlation coefficient (CC) for efficient detection of variation in the size and fringe width of the Talbot self-images and thereby the collimation position. When the beam is collimated, the physical properties of the self-images of the grating, such as its size and fringe width, do not vary from one Talbot plane to the other and are identical; the CC is maximum in such a situation. For the de-collimated position, the size and fringe width of the self-images vary, and correspondingly the CC decreases. Hence, the magnitude of CC is a measure of degree of collimation. Using the method, we could set the collimation position to a resolution of 1 μm, which relates to ±0.25 μ radians in terms of collimation angle (for testing a collimating lens of diameter 46 mm and focal length 300 mm). In contrast to most collimation techniques reported to date, the proposed technique does not require a translation/rotation of the grating, use of complicated phase evaluation algorithms, or an intricate method for determination of period of the grating or its self-images. The technique is fully automated and provides high resolution and precision.
A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research.
Koo, Terry K; Li, Mae Y
2016-06-01
Intraclass correlation coefficient (ICC) is a widely used reliability index in test-retest, intrarater, and interrater reliability analyses. This article introduces the basic concept of ICC in the content of reliability analysis. There are 10 forms of ICCs. Because each form involves distinct assumptions in their calculation and will lead to different interpretations, researchers should explicitly specify the ICC form they used in their calculation. A thorough review of the research design is needed in selecting the appropriate form of ICC to evaluate reliability. The best practice of reporting ICC should include software information, "model," "type," and "definition" selections. When coming across an article that includes ICC, readers should first check whether information about the ICC form has been reported and if an appropriate ICC form was used. Based on the 95% confident interval of the ICC estimate, values less than 0.5, between 0.5 and 0.75, between 0.75 and 0.9, and greater than 0.90 are indicative of poor, moderate, good, and excellent reliability, respectively. This article provides a practical guideline for clinical researchers to choose the correct form of ICC and suggests the best practice of reporting ICC parameters in scientific publications. This article also gives readers an appreciation for what to look for when coming across ICC while reading an article.
Satomura, Hironori; Adachi, Kohei
2013-07-01
To facilitate the interpretation of canonical correlation analysis (CCA) solutions, procedures have been proposed in which CCA solutions are orthogonally rotated to a simple structure. In this paper, we consider oblique rotation for CCA to provide solutions that are much easier to interpret, though only orthogonal rotation is allowed in the existing formulations of CCA. Our task is thus to reformulate CCA so that its solutions have the freedom of oblique rotation. Such a task can be achieved using Yanai's (Jpn. J. Behaviormetrics 1:46-54, 1974; J. Jpn. Stat. Soc. 11:43-53, 1981) generalized coefficient of determination for the objective function to be maximized in CCA. The resulting solutions are proved to include the existing orthogonal ones as special cases and to be rotated obliquely without affecting the objective function value, where ten Berge's (Psychometrika 48:519-523, 1983) theorems on suborthonormal matrices are used. A real data example demonstrates that the proposed oblique rotation can provide simple, easily interpreted CCA solutions.
Wang, Jianji; Zheng, Nanning
2013-09-01
Fractal image compression (FIC) is an image coding technology based on the local similarity of image structure. It is widely used in many fields such as image retrieval, image denoising, image authentication, and encryption. FIC, however, suffers from the high computational complexity in encoding. Although many schemes are published to speed up encoding, they do not easily satisfy the encoding time or the reconstructed image quality requirements. In this paper, a new FIC scheme is proposed based on the fact that the affine similarity between two blocks in FIC is equivalent to the absolute value of Pearson's correlation coefficient (APCC) between them. First, all blocks in the range and domain pools are chosen and classified using an APCC-based block classification method to increase the matching probability. Second, by sorting the domain blocks with respect to APCCs between these domain blocks and a preset block in each class, the matching domain block for a range block can be searched in the selected domain set in which these APCCs are closer to APCC between the range block and the preset block. Experimental results show that the proposed scheme can significantly speed up the encoding process in FIC while preserving the reconstructed image quality well.
Aly, Sharif S; Zhao, Jianyang; Li, Ben; Jiang, Jiming
2014-01-01
The Intraclass Correlation Coefficient (ICC) is commonly used to estimate the similarity between quantitative measures obtained from different sources. Overdispersed data is traditionally transformed so that linear mixed model (LMM) based ICC can be estimated. A common transformation used is the natural logarithm. The reliability of environmental sampling of fecal slurry on freestall pens has been estimated for Mycobacterium avium subsp. paratuberculosis using the natural logarithm transformed culture results. Recently, the negative binomial ICC was defined based on a generalized linear mixed model for negative binomial distributed data. The current study reports on the negative binomial ICC estimate which includes fixed effects using culture results of environmental samples. Simulations using a wide variety of inputs and negative binomial distribution parameters (r; p) showed better performance of the new negative binomial ICC compared to the ICC based on LMM even when negative binomial data was logarithm, and square root transformed. A second comparison that targeted a wider range of ICC values showed that the mean of estimated ICC closely approximated the true ICC.
A Bayesian estimate of the concordance correlation coefficient with skewed data.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2015-01-01
Concordance correlation coefficient (CCC) is one of the most popular scaled indices used to evaluate agreement. Most commonly, it is used under the assumption that data is normally distributed. This assumption, however, does not apply to skewed data sets. While methods for the estimation of the CCC of skewed data sets have been introduced and studied, the Bayesian approach and its comparison with the previous methods has been lacking. In this study, we propose a Bayesian method for the estimation of the CCC of skewed data sets and compare it with the best method previously investigated. The proposed method has certain advantages. It tends to outperform the best method studied before when the variation of the data is mainly from the random subject effect instead of error. Furthermore, it allows for greater flexibility in application by enabling incorporation of missing data, confounding covariates, and replications, which was not considered previously. The superiority of this new approach is demonstrated using simulation as well as real-life biomarker data sets used in an electroencephalography clinical study. The implementation of the Bayesian method is accessible through the Comprehensive R Archive Network. Copyright © 2015 John Wiley & Sons, Ltd.
Wang, Jifei; Sun, Meili; Liu, Dawei; Hu, Xiaoshu; Pui, Margaret H; Meng, Quanfei; Gao, Zhenhua
2017-08-01
Background Neoadjuvant chemotherapy has made limb-salvage surgery possible for the patients with osteosarcoma. Diffusion-weighted magnetic resonance imaging (DWI) has been used to monitor chemotherapy response. Purpose To correlate the apparent diffusion coefficient (ADC) values with histopathology subtypes of osteosarcoma after neoadjuvant chemotherapy. Material and Methods Twelve patients with osteoblastic (n = 7), chondroblastic (n = 4), and fibroblastic (n = 1) osteosarcomas underwent post-chemotherapy DWI before limb-salvage surgery. ADCs corresponding to 127 histological tissue samples from the 12 resected specimens were compared to histological features. Results The mean ADC value of non-cartilaginous viable tumor (38/91, ADC = 1.22 ± 0.03 × 10 -3 mm 2 /s) was significantly ( P 0.05) different between viable cartilaginous tumor and cystic/hemorrhagic necrosis. Conclusion DWI allows assessment of tumor necrosis after neoadjuvant chemotherapy by ADC differences between viable tumor and necrosis in fibroblastic and osteoblastic osteosarcomas whereas viable chondroblastic osteosarcoma has high ADC and cannot be distinguished reliably from necrosis.
Sams, E. W.
1952-01-01
An investigation of forced-convection heat transfer and associated pressure drops was conducted with air flowing through electrically heated Inconel tubes having various degrees of square-thread-type roughness, an inside diameter of 1/2 inch, and a length of 24 inches. were obtained for tubes having conventional roughness ratios (height of thread/radius of tube) of 0 (smooth tube), 0.016, 0.025, and 0.037 over ranges of bulk Reynolds numbers up to 350,000, average inside-tube-wall temperatures up to 1950deg R, and heat-flux densities up to 115,000 Btu per hour per square foot. Data The experimental data showed that both heat transfer and friction increased with increase in surface roughness, becoming more pronounced with increase in Reynolds number; for a given roughness, both heat transfer and friction were also influenced by the tube wall-to-bulk temperature ratio. Good correlation of the heat-transfer data for all the tubes investigated was obtained by use of a modification of the conventional Nusselt correlation parameters wherein the mass velocity in the Reynolds number was replaced by the product of air density evaluated at the average film temperature and the so-called friction velocity; in addition, the physical properties of air were evaluated at the average film temperature. The isothermal friction data for the rough tubes, when plotted in the conventional manner, resulted in curves similar to those obtained by other investigators; that is, the curve for a given roughness breaks away from the Blasius line (representing turbulent flow in smooth tubes) at some value of Reynolds number, which decreases with increase in surface roughness, and then becomes a horizontal line (friction coefficient independent of Reynolds number). A comparison of the friction data for the rough tubes used herein indicated that the conventional roughness ratio is not an adequate measure of relative roughness for tubes having a square-thread-type element. The present data, as well
Wang, Fang
2016-06-01
In order to detect and quantify asymmetry of two time series, a novel cross-correlation coefficient is proposed based on recent asymmetric detrended cross-correlation analysis (A-DXA), which we called A-DXA coefficient. The A-DXA coefficient, as an important extension of DXA coefficient ρDXA, contains two directional asymmetric cross-correlated indexes, describing upwards and downwards asymmetric cross-correlations, respectively. By using the information of directional covariance function of two time series and directional variance function of each series itself instead of power-law between the covariance function and time scale, the proposed A-DXA coefficient can well detect asymmetry between the two series no matter whether the cross-correlation is significant or not. By means of the proposed A-DXA coefficient conducted over the asymmetry for California electricity market, we found that the asymmetry between the prices and loads is not significant for daily average data in 1999 yr market (before electricity crisis) but extremely significant for those in 2000 yr market (during the crisis). To further uncover the difference of asymmetry between the years 1999 and 2000, a modified H statistic (MH) and ΔMH statistic are proposed. One of the present contributions is that the high MH values calculated for hourly data exist in majority months in 2000 market. Another important conclusion is that the cross-correlation with downwards dominates over the whole 1999 yr in contrast to the cross-correlation with upwards dominates over the 2000 yr.
Wang, Fang
2016-06-01
In order to detect and quantify asymmetry of two time series, a novel cross-correlation coefficient is proposed based on recent asymmetric detrended cross-correlation analysis (A-DXA), which we called A-DXA coefficient. The A-DXA coefficient, as an important extension of DXA coefficient ρ D X A , contains two directional asymmetric cross-correlated indexes, describing upwards and downwards asymmetric cross-correlations, respectively. By using the information of directional covariance function of two time series and directional variance function of each series itself instead of power-law between the covariance function and time scale, the proposed A-DXA coefficient can well detect asymmetry between the two series no matter whether the cross-correlation is significant or not. By means of the proposed A-DXA coefficient conducted over the asymmetry for California electricity market, we found that the asymmetry between the prices and loads is not significant for daily average data in 1999 yr market (before electricity crisis) but extremely significant for those in 2000 yr market (during the crisis). To further uncover the difference of asymmetry between the years 1999 and 2000, a modified H statistic (MH) and ΔMH statistic are proposed. One of the present contributions is that the high MH values calculated for hourly data exist in majority months in 2000 market. Another important conclusion is that the cross-correlation with downwards dominates over the whole 1999 yr in contrast to the cross-correlation with upwards dominates over the 2000 yr.
Zhao, Jinping; Cao, Yong; Wang, Xin
2018-06-01
In order to study the temporal variations of correlations between two time series, a running correlation coefficient (RCC) could be used. An RCC is calculated for a given time window, and the window is then moved sequentially through time. The current calculation method for RCCs is based on the general definition of the Pearson product-moment correlation coefficient, calculated with the data within the time window, which we call the local running correlation coefficient (LRCC). The LRCC is calculated via the two anomalies corresponding to the two local means, meanwhile, the local means also vary. It is cleared up that the LRCC reflects only the correlation between the two anomalies within the time window but fails to exhibit the contributions of the two varying means. To address this problem, two unchanged means obtained from all available data are adopted to calculate an RCC, which is called the synthetic running correlation coefficient (SRCC). When the anomaly variations are dominant, the two RCCs are similar. However, when the variations of the means are dominant, the difference between the two RCCs becomes obvious. The SRCC reflects the correlations of both the anomaly variations and the variations of the means. Therefore, the SRCCs from different time points are intercomparable. A criterion for the superiority of the RCC algorithm is that the average value of the RCC should be close to the global correlation coefficient calculated using all data. The SRCC always meets this criterion, while the LRCC sometimes fails. Therefore, the SRCC is better than the LRCC for running correlations. We suggest using the SRCC to calculate the RCCs.
International Nuclear Information System (INIS)
Hyuk Kwon; Dong Un Seo; Goon-Cherl Park
2005-01-01
Full text of publication follows: Flow Accelerated Corrosion (FAC) is a corrosion mechanism that results in wall thinning in piping systems and components. FAC on carbon steels in pure water has occurred in a number of industry and power plant. A pipe wall thinning due to the FAC at nuclear power plant is just reported in confined to carbon steel pipe on the secondary system which does not equip a radioactive component. Recently, at Canadian Deuterium Uranium type reactor, it is reported that the feeder lines suffer the wall thinning on the primary system to equip 380 feeder pipes. Differently from the fast FAC rate of the secondary system on PWR, FAC rate of feeder pipes on CANDU is not more than the 0.2 mm/year. Although the FAC rate of feeder pipe is relatively slow, the narrow thickness margin of 2.6089 mm is endangered sufficiently by only the slow FAC rate. The FAC is governed by the mass transfer coefficient which is determined by the flow field. To well predict the FAC rate, mass transfer coefficient should be well measured or calculated. New measurement method of mass transfer coefficient is developed to obtain the coefficient for the complex shape like feeder pipe. The method evaluated the naphthalene sublimation method to apply it under the water flow. The naphthalene sublimation method can be used to study mass and heat transfer with confidence for a variety of applications, but with certain restrictions. At present, Plaster of paris method can modified the sublimation method to overcome the restrictions. This method is particularly useful in complex flows on geometries and for flows with large gradients in wall transport rate. The test specimen can be easily prepared by several methods, including dipping, machining, spraying, and casting. The local transfer coefficients can be determined with high accuracy and in detail by automated measurement systems that eliminate most human errors during the measurement process. To evaluate the method, the
Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L
2013-04-01
Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
İsmail Hakkı ERTEN
2008-10-01
Full Text Available This study aims to compare the appropriateness of two statistical procedures for measuring the effectiveness of vocabulary learning strategies: percentages and correlation coefficients. To do this a group of 20 learners of English were asked to study 12 words in a written list, with their pronunciations, dictionary definitions, and example sentences. Data was collected through introspection where students were asked to verbalize their mental processes as they studied the target words. A pre-test and post-test were given to measure the task achievement. The qualitative data was transcribed verbatim and content-analysed for tokens of strategy use as well as by noting whether each use of strategies led to successful recall of the words on which they were used. To calculate the strategy effectiveness, both simple percentage calculation and correlation coefficients were employed for comparison. The findings indicated that percentage calculation can give a more realistic picture of strategy effectiveness than correlation coefficients.
Bunyakan, C.; Malakarn, S.; Tongurai, C.
2002-01-01
Volatile organic compounds (VOCs) have been found in wastewater of many chemical industries. Evaporation of VOCs from open water basin in waste treatment facilities causes air-pollution and has been regulated in many countries. Reduction or prevention of VOCs evaporation from open water basin is then necessary. The aim of this research was to investigate the influence of surface film generated by an insoluble surfactant on the mass transfer coefficient of VOCs evaporating from water. Hexadeca...
Energy Technology Data Exchange (ETDEWEB)
Wanninger, Andreas; Ceuca, Sabin Cristian; Macian-Juan, Rafael [Technische Univ. Muenchen, Garching (Germany). Dept. of Nuclear Engineering
2013-07-01
Different approaches for the calculation of Direct Contact Condensation (DCC) using Heat Transfer Coefficients (HTC) based on the Surface Renewal Theory (SRT) are tested using the CFD simulation tool ANSYS CFX. The present work constitutes a preliminary study of the flow patterns and conditions observed using different HTC models. A complex 3D flow pattern will be observed in the CFD simulations as well as a strong coupling between the condensation rate and the two-phase flow dynamics. (orig.)
International Nuclear Information System (INIS)
Muzzio, A.; Niro, A.; Garaviglia, M.
1998-01-01
Saturated flow boiling and convective condensation experiments for oil-free refrigerant R22 been carried out with a micro fin tube of new design and with a smooth tube. Both tube have the same outer diameter of 9.52 mm and are horizontally operated. Two-phase flow pattern data have been obtained in addition of heat transfer coefficient and pressure drops; more-over, adiabatic tests have been also performed in order for flow pattern map to cover even adiabatic flows. Data are for mass fluxes ranging from about 90 to 400 Kg/s m 2 . In boiling tests, the nominal saturation temperature is 5 degree C, with inlet quality varying from 0.2 to 0.6 and the quality change ranging from 0.1 to 0.5. In condensation, results are for saturation temperature equal to 35 degree C, with inlet quality between 0.8 and 0.4, and quality change within 0.6 and 0.2. The comparison shows a large heat transfer augmentation with a moderate increment of pressure drops, especially in evaporation were the enhancement factor comes up to 4 while the penalty factor is about 1.4 at the most. Heat transfer coefficients both in evaporation and condensation are compared to the predictions of some recent correlations specifically proposed or modified for micro fin tube
International Nuclear Information System (INIS)
Nariai, Hideki; Kobayashi, Michiyuki; Matsuoka, Takeshi.
1982-01-01
Two-phase friction pressure drop and heat transfer coefficients in a once-through steam generator with helically coiled tubes were investigated with the model test rig of an integrated type marine water reactor. As the dimensions of the heat transfer tubes and the thermal-fluid conditions are almost the same as those of real reactors, the data applicable directly to the real reactor design were obtained. As to the friction pressure drop, modified Kozeki's prediction which is based on the experimental data by Kozeki for coiled tubes, agreed the best with the experimental data. Modified Martinelli-Nelson's prediction which is based on Martinelli-Nelson's multiplier using Ito's equation for single-phase flow in coiled tube, agreed within 30%. The effect of coiled tube on the average heat transfer coefficients at boiling region were small, and the predictions for straight tube could also be applied to coiled tube. Schrock-Grossman's correlation agreed well with the experimental data at the pressures of lower than 3.5 MPa. It was suggested that dryout should be occurred at the quality of greater than 90% within the conditions of this report. (author)
DEFF Research Database (Denmark)
Hansen, Ernst; Mollerup, Jørgen
1999-01-01
The paper describes a method of simultaneous determination of the external and the solid phase mass-transfer coefficients from frontal analysis data. The protein flux to the solid particles is determined from the slope of the breakthrough curve and the mass-transfer coefficients are determined...
Directory of Open Access Journals (Sweden)
Ryoichi Chiba
2018-01-01
Full Text Available An analytical solution is derived for one-dimensional transient heat conduction in a composite slab consisting of n layers, whose heat transfer coefficient on an external boundary is an arbitrary function of time. The composite slab, which has thermal contact resistance at n-1 interfaces, as well as an arbitrary initial temperature distribution and internal heat generation, convectively exchanges heat at the external boundaries with two different time-varying surroundings. To obtain the analytical solution, the shifting function method is first used, which yields new partial differential equations under conventional types of external boundary conditions. The solution for the derived differential equations is then obtained by means of an orthogonal expansion technique. Numerical calculations are performed for two composite slabs, whose heat transfer coefficient on the heated surface is either an exponential or a trigonometric function of time. The numerical results demonstrate the effects of temporal variations in the heat transfer coefficient on the transient temperature field of composite slabs.
Energy Technology Data Exchange (ETDEWEB)
Gurler, O. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)], E-mail: ogurler@uludag.edu.tr; Oz, H. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Yalcin, S. [Education Faculty, Kastamonu University, 37200 Kastamonu (Turkey); Gundogdu, O. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); NCCPM, Medical Physics, Royal Surrey County Hospital, GU2 7XX (United Kingdom)
2009-01-15
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature.
International Nuclear Information System (INIS)
Gurler, O.; Oz, H.; Yalcin, S.; Gundogdu, O.
2009-01-01
The mass energy absorption, the mass energy transfer and mass absorption coefficients have been widely used for problems and applications involving dose calculations. Direct measurements of the coefficients are difficult, and theoretical computations are usually employed. In this paper, analytical equations are presented for determining the mass energy transfer and mass absorption coefficients for gamma rays with an incident energy range between 0.4 and 10 MeV in nitrogen, silicon, carbon, copper and sodium iodide. The mass absorption and mass energy transfer coefficients for gamma rays were calculated, and the results obtained were compared with the values reported in the literature
Correlated linear response calculations of the C6 dispersion coefficients of hydrogen halides
Czech Academy of Sciences Publication Activity Database
Sauer, S. P. A.; Paidarová, Ivana
2007-01-01
Roč. 3, 2-4 (2007), s. 399-421 ISSN 1574-0404 R&D Projects: GA AV ČR IAA401870702 Institutional research plan: CEZ:AV0Z40400503 Keywords : hydrogen halides * C6 dospersion coefficients * van der Waals coefficients * polarizability at imaginary frequences * SOPPA Subject RIV: CF - Physical ; Theoretical Chemistry
International Nuclear Information System (INIS)
Edelmann, M.
1995-12-01
A new measurement method for measuring the mean fuel temperature as well as the fuel-to-coolant heat transfer coefficient of fast breeder reactor subassemblies (SA) is reported. The method is based on the individual heat balance of fuel SA's after fast reactor shut-downs and uses only the plants normal SA outlet temperature and neutron power signals. The method was used successfully at the french breeder prototype Super Phenix 1. The mean SA fuel temperature as well as the heat transfer coefficient of all SPX SA's have been determined at power levels between 15 and 90% of nominal power and increasing fuel burn-up from 3 to 83 EFPD (Equivalent of Full Power-Days). The measurements also provided fuel and whole SA time constants. The estimated accuracy of measured fuel parameters is in the order of 10%. Fuel temperatures and SA outlet temperature transients were also calculated with the SPX1 systems code DYN2 for exactly the same fuel and reactor operating parameters as in the experiments. Measured fuel temperatures were higher than calculated ones in all cases. The difference between measured and calculated core mean values increases from 50 K at low power to 180 K at 90% n.p. This is about the double of the experimental error margins. Measured SA heat transfer coefficients are by nearly 20% lower than corresponding heat transfer parameters used in the calculations. Discrepancies found between measured and calculated results also indicate that either the transient heat transfer in the gap between fuel and cladding (gap conductance) might not be exactly reproduced in the computer code or that the gap in the fresh fuel was larger than assumed in the calculations. (orig.) [de
Transfer of spectral weight in spectroscopies of correlated electron systems
International Nuclear Information System (INIS)
Rozenberg, M.J.; Kotliar, G.; Kajueter, H.
1996-01-01
We study the transfer of spectral weight in the photoemission and optical spectra of strongly correlated electron systems. Within the local impurity self-consistent approximation, that becomes exact in the limit of large lattice coordination, we consider and compare two models of correlated electrons, the Hubbard model and the periodic Anderson model. The results are discussed in regard to recent experiments. In the Hubbard model, we predict an anomalous enhancement optical spectral weight as a function of temperature in the correlated metallic state which is in qualitative agreement with optical measurements in V 2 O 3 . We argue that anomalies observed in the spectroscopy of the metal are connected to the proximity to a crossover region in the phase diagram of the model. In the insulating phase, we obtain excellent agreement with the experimental data, and present a detailed discussion on the role of magnetic frustration by studying the k-resolved single-particle spectra. The results for the periodic Anderson model are discussed in connection to recent experimental data of the Kondo insulators Ce 3 Bi 4 Pt 3 and FeSi. The model can successfully explain the thermal filling of the optical gap and the corresponding changes in the photoemission density of states. The temperature dependence of the optical sum rule is obtained, and its relevance to the interpretation of the experimental data discussed. Finally, we argue that the large scattering rate measured in Kondo insulators cannot be described by the periodic Anderson model. copyright 1996 The American Physical Society
Lee, Kyoung Min; Lee, Jaebong; Chung, Chin Youb; Ahn, Soyeon; Sung, Ki Hyuk; Kim, Tae Won; Lee, Hui Jong; Park, Moon Seok
2012-06-01
Intra-class correlation coefficients (ICCs) provide a statistical means of testing the reliability. However, their interpretation is not well documented in the orthopedic field. The purpose of this study was to investigate the use of ICCs in the orthopedic literature and to demonstrate pitfalls regarding their use. First, orthopedic articles that used ICCs were retrieved from the Pubmed database, and journal demography, ICC models and concurrent statistics used were evaluated. Second, reliability test was performed on three common physical examinations in cerebral palsy, namely, the Thomas test, the Staheli test, and popliteal angle measurement. Thirty patients were assessed by three orthopedic surgeons to explore the statistical methods testing reliability. Third, the factors affecting the ICC values were examined by simulating the data sets based on the physical examination data where the ranges, slopes, and interobserver variability were modified. Of the 92 orthopedic articles identified, 58 articles (63%) did not clarify the ICC model used, and only 5 articles (5%) described all models, types, and measures. In reliability testing, although the popliteal angle showed a larger mean absolute difference than the Thomas test and the Staheli test, the ICC of popliteal angle was higher, which was believed to be contrary to the context of measurement. In addition, the ICC values were affected by the model, type, and measures used. In simulated data sets, the ICC showed higher values when the range of data sets were larger, the slopes of the data sets were parallel, and the interobserver variability was smaller. Care should be taken when interpreting the absolute ICC values, i.e., a higher ICC does not necessarily mean less variability because the ICC values can also be affected by various factors. The authors recommend that researchers clarify ICC models used and ICC values are interpreted in the context of measurement.
Directory of Open Access Journals (Sweden)
Ze-Hong Fu
2017-08-01
Full Text Available Objective: To study the correlation of MRI apparent diffusion coefficient (ADC value of invasive breast cancer with tumor tissue growth and angiogenesis. Methods: Patients with breast mass who were treated in Wuhan No. 6 Hospital between March 2014 and May 2017 were selected as the research subjects and divided into group A with invasive ductal carcinoma, group B with intraductal carcinoma and group C with benign lesion according to the biopsy results, magnetic resonance diffusion-weighted imaging was conducted to determine ADC values, and biopsy tissue was taken to determine the expression of proliferation genes and angiogenesis genes. Results: USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in lesions of group A and group B were significantly higher than those of group C while ADC value as well as ALEX1 and Bax protein expression levels were significantly lower than those of group C; USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in lesions of group A were significantly higher than those of group B while ADC value as well as ALEX1 and Bax protein expression levels was significantly lower than those of group B; USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in invasive breast cancer tissue with high ADC value were significantly lower than those in invasive breast cancer tissue with low ADC value while ALEX1 and Bax protein expression levels were significantly higher than those in invasive breast cancer tissue with low ADC value. Conclusion: The decrease of ADC value of invasive breast cancer is closely related to cancer cell proliferation and angiogenesis.
Directory of Open Access Journals (Sweden)
Bahman Navidshad
2012-02-01
Full Text Available The applications of conventional culture-dependent assays to quantify bacteria populations are limited by their dependence on the inconsistent success of the different culture-steps involved. In addition, some bacteria can be pathogenic or a source of endotoxins and pose a health risk to the researchers. Bacterial quantification based on the real-time PCR method can overcome the above-mentioned problems. However, the quantification of bacteria using this approach is commonly expressed as absolute quantities even though the composition of samples (like those of digesta can vary widely; thus, the final results may be affected if the samples are not properly homogenized, especially when multiple samples are to be pooled together before DNA extraction. The objective of this study was to determine the correlation coefficients between four different methods of expressing the output data of real-time PCR-based bacterial quantification. The four methods were: (i the common absolute method expressed as the cell number of specific bacteria per gram of digesta; (ii the Livak and Schmittgen, ΔΔCt method; (iii the Pfaffl equation; and (iv a simple relative method based on the ratio of cell number of specific bacteria to the total bacterial cells. Because of the effect on total bacteria population in the results obtained using ΔCt-based methods (ΔΔCt and Pfaffl, these methods lack the acceptable consistency to be used as valid and reliable methods in real-time PCR-based bacterial quantification studies. On the other hand, because of the variable compositions of digesta samples, a simple ratio of cell number of specific bacteria to the corresponding total bacterial cells of the same sample can be a more accurate method to quantify the population.
International Nuclear Information System (INIS)
Boucher, T.J.
1987-01-01
To provide data for assessment and development of thermal-hydraulic computer codes, bottom main feedwater-line-break transient simulations were performed in a scale model (Semiscale Mod-2C) of a pressurized water reactor (PWR) with conditions typical of a PWR (15.0 MPa primary pressure, 600 K steam generator inlet plenum fluid temperatures, 6.2 MPa secondary pressure). The state-of-the-art measurements in the scale model (Type III) steam generator allow for the determination of U-tube steam generator allow for the determination of U-tube steam generator secondary component interactions, tube bundle local radial heat transfer, and tube bundle and riser vapor void fractions for steady state and transient operations. To enhance the understanding of the observed phenomena, the component interactions, local heat fluxes, local secondary convective heat transfer coefficients and local vapor void fractions are discussed for steady state, full-power and transient operations. Comparisons between the measurement-derived secondary convective heat transfer coefficients and those predicted by a number of correlations, including the Chen correlation currently used in thermal-hydraulic computer codes, show that none of the correlations adequately predict the data and points out the need for the formulation of a new correlation based on this experimental data. The unique information presented herein should be of the interest to anyone involved in modeling inverted U-tube steam generator thermal-hydraulics for forced convection boiling/vaporization heat transfer. 5 refs., 13 figs., 1 tab
Jang, Nulee; Yasin, Muhammad; Park, Shinyoung; Lovitt, Robert W; Chang, In Seop
2017-09-01
A mathematical model of microbial kinetics was introduced to predict the overall volumetric gas-liquid mass transfer coefficient (k L a) of carbon monoxide (CO) in a batch cultivation system. The cell concentration (X), acetate concentration (C ace ), headspace gas (N co and [Formula: see text] ), dissolved CO concentration in the fermentation medium (C co ), and mass transfer rate (R) were simulated using a variety of k L a values. The simulated results showed excellent agreement with the experimental data for a k L a of 13/hr. The C co values decreased with increase in cultivation times, whereas the maximum mass transfer rate was achieved at the mid-log phase due to vigorous microbial CO consumption rate higher than R. The model suggested in this study may be applied to a variety of microbial systems involving gaseous substrates. Copyright © 2017 Elsevier Ltd. All rights reserved.
Wang, T; Zhao, G; Tang, H Y; Jiang, Z D
2015-01-01
Cell survival upon cryopreservation is affected by the cooling rate. However, it is difficult to model the heat transfer process or to predict the cooling curve of a cryoprotective agent (CPA) solution due to the uncertainty of its convective heat transfer coefficient (h). To measure the h and to better understand the heat transfer process of cryovials filled with CPA solution being plunged in liquid nitrogen. The temperatures at three locations of the CPA solution in a cryovial were measured. Different h values were selected after the cooling process was modeled as natural convection heat transfer, the film boiling and the nucleate boiling, respectively. And the temperatures of the selected points are simulated based on the selected h values. h was determined when the simulated temperature best fitted the experimental temperature. When the experimental results were best fitted, according to natural convection heat transfer model, h(1) = 120 W/(m(2)·K) while due to film boiling and nucleate boiling regimes h(f) = 5 W/(m(2)·K) followed by h(n) = 245 W/(m(2)·K). These values were verified by the differential cooling rates at the three locations of a cryovial. The heat transfer process during cooling in liquid nitrogen is better modeled as film boiling followed by nucleate boiling.
Study of overall heat transfer coefficient from upper crust to overlaying water during MCCI
International Nuclear Information System (INIS)
Kondo, Masaya; Nishida, Ayumu; Sugimoto, Jun
2015-01-01
A model of the overall heat transfer between the molten core and the overlying coolant above crust during MCCI in severe accident is proposed and confirmed experimentally and analytically. The model assumes that the heat transferred from molten core to the overlaying water is proportional to the amount of water that reaches the molten core surface. The water flow to the molten core surface is assumes to be prevented by the CCFL in the porous crust. Thus, the steam flow and the non-condensable gas flow interact with the water flow. The present model describes the relationship between the overall heat transfer and the water flow, and furthermore, the CCFL effect on the water flow. The non-condensable gas effect on the overall heat transfer predicted by the present model agrees well with experiments. The effects of porosity and hole diameter on the amount of water, which reaches the molten core surface, has also been confirmed using RELAP5 code. (author)
International Nuclear Information System (INIS)
Mehta, Balkrishna; Khandekar, Sameer
2014-01-01
Highlights: • Infra-red thermographic study of Taylor bubble train flow in square mini-channel. • Design of experiments for measurement of local streamwise Nusselt number. • Minimizing conjugate heat transfer effects and resulting errors in data reduction. • Benchmarking against single-phase flow and three-dimensional computations. • Local heat transfer enhancement up to two times due to Taylor bubble train flow. -- Abstract: In mini/micro confined internal flow systems, Taylor bubble train flow takes place within specific range of respective volume flow ratios, wherein the liquid slugs get separated by elongated Taylor bubbles, resulting in an intermittent flow situation. This unique flow characteristic requires understanding of transport phenomena on global, as well as on local spatio-temporal scales. In this context, an experimental design methodology and its validation are presented in this work, with an aim of measuring the local heat transfer coefficient by employing high-resolution InfraRed Thermography. The effect of conjugate heat transfer on the true estimate of local transport coefficients, and subsequent data reduction technique, is discerned. Local heat transfer coefficient for (i) hydrodynamically fully developed and thermally developing single-phase flow in three-side heated channel and, (ii) non-boiling, air–water Taylor bubble train flow is measured and compared in a mini-channel of square cross-section (5 mm × 5 mm; D h = 5 mm, Bo ≈ 3.4) machined on a stainless steel substrate (300 mm × 25 mm × 11 mm). The design of the setup ensures near uniform heat flux condition at the solid–fluid interface; the conjugate effects arising from the axial back conduction in the substrate are thus minimized. For benchmarking, the data from single-phase flow is also compared with three-dimensional computational simulations. Depending on the employed volume flow ratio, it is concluded that enhancement of nearly 1.2–2.0 times in time
Cross correlation coefficients of turbulent boundary layer with micro-bubble injection
International Nuclear Information System (INIS)
Claudia del Carmen Gutierrez-Torres; Yassin A Hassan; Jose Alfredo Jimenez-Bernal
2005-01-01
Full text of publication follows: Injection of micro-bubbles within the turbulent boundary layer has been investigated for a several years as a method to achieve drag reduction. However, the physical mechanism of this phenomenon is not fully understood yet. Experiments in a channel flow for single phase (water) and two phase (water and micro-bubbles) flows under different void fraction conditions are reported for a Reynolds number of 5128. Particle Image Velocimetry technique is used to measure instantaneous velocity fields. Consequently the cross-correlation coefficient Ruv can be calculated along the stream-wise direction for various different y + positions and along the normal direction for the fluctuating components of the velocity obtained from the instantaneous velocity fields. The experiments were carried out in a rectangular acrylic channel, whose dimensions are 4.8 m length, 20.6 cm wide and 5.6 cm height. Water was driven trough the channel by gravity from a tank, which was located 3 m above the channel. Then, water was conducted to a lower tank; from which water was pumped to the upper thank forming a closed loop. Upper tank's water level was kept constant through the tests to ensure constant flow rate trough the channel. The velocity field in the x-y plane was obtained by particle image velocimetry (PIV) at 3.15 m downstream from the channel inlet. A Nd:YAG laser with a wavelength of 532 nm (green light) and power of 350 mJ per pulse is utilized. The particles used for seeding have a diameter that goes from 6-9 μm with a specific gravity almost identical to water s specific gravity. The laser light scattered from the seeding particles was recorded using a CCD Kodak Megaplus camera, Model ES 1.0, 1008 x 1018 pixels. The viewing area was 1.28 cm 2 and was located close to the channel wall. The system recorded 30 velocity fields per second. Each velocity field was obtained from a pair of consecutive images capturing the second image of the pair 1 ms after
Cross correlation coefficients of turbulent boundary layer with micro-bubble injection
Energy Technology Data Exchange (ETDEWEB)
Claudia del Carmen Gutierrez-Torres [LABINTHAP-SEPI-ESIME, Instituto Politecnico Nacional, U.P. Adolfo Lopez Mateos Edif. 5 3er. Piso, Col Lindavista, C.P. 07738, Mexico, D. F. (Mexico); Yassin A Hassan; Jose Alfredo Jimenez-Bernal [Texas A and M University, College Station, Tx. 77843-3133 (United States)
2005-07-01
Full text of publication follows: Injection of micro-bubbles within the turbulent boundary layer has been investigated for a several years as a method to achieve drag reduction. However, the physical mechanism of this phenomenon is not fully understood yet. Experiments in a channel flow for single phase (water) and two phase (water and micro-bubbles) flows under different void fraction conditions are reported for a Reynolds number of 5128. Particle Image Velocimetry technique is used to measure instantaneous velocity fields. Consequently the cross-correlation coefficient Ruv can be calculated along the stream-wise direction for various different y{sup +} positions and along the normal direction for the fluctuating components of the velocity obtained from the instantaneous velocity fields. The experiments were carried out in a rectangular acrylic channel, whose dimensions are 4.8 m length, 20.6 cm wide and 5.6 cm height. Water was driven trough the channel by gravity from a tank, which was located 3 m above the channel. Then, water was conducted to a lower tank; from which water was pumped to the upper thank forming a closed loop. Upper tank's water level was kept constant through the tests to ensure constant flow rate trough the channel. The velocity field in the x-y plane was obtained by particle image velocimetry (PIV) at 3.15 m downstream from the channel inlet. A Nd:YAG laser with a wavelength of 532 nm (green light) and power of 350 mJ per pulse is utilized. The particles used for seeding have a diameter that goes from 6-9 {mu}m with a specific gravity almost identical to water s specific gravity. The laser light scattered from the seeding particles was recorded using a CCD Kodak Megaplus camera, Model ES 1.0, 1008 x 1018 pixels. The viewing area was 1.28 cm{sup 2} and was located close to the channel wall. The system recorded 30 velocity fields per second. Each velocity field was obtained from a pair of consecutive images capturing the second image of
Collett, B; Bateman, F; Bauder, W K; Byrne, J; Byron, W A; Chen, W; Darius, G; DeAngelis, C; Dewey, M S; Gentile, T R; Hassan, M T; Jones, G L; Komives, A; Laptev, A; Mendenhall, M P; Nico, J S; Noid, G; Park, H; Stephenson, E J; Stern, I; Stockton, K J S; Trull, C; Wietfeldt, F E; Yerozolimsky, B G
2017-08-01
We describe an apparatus used to measure the electron-antineutrino angular correlation coefficient in free neutron decay. The apparatus employs a novel measurement technique in which the angular correlation is converted into a proton time-of-flight asymmetry that is counted directly, avoiding the need for proton spectroscopy. Details of the method, apparatus, detectors, data acquisition, and data reduction scheme are presented, along with a discussion of the important systematic effects.
Spatial correlation in 3D MIMO channels using fourier coefficients of power spectrums
Nadeem, Qurrat-Ul-Ain; Kammoun, Abla; Debbah, Mé rouane; Alouini, Mohamed-Slim
2015-01-01
for arbitrary angular distributions and antenna patterns. The resulting expression depends on the underlying angular distributions and antenna patterns through the Fourier Series (FS) coefficients of power azimuth and elevation spectrums. The novelty
DEFF Research Database (Denmark)
Christensen, Eva Arnspang; Koffman, Jennifer Skaarup; Marlar, Saw
2014-01-01
Lateral diffusion and compartmentalization of plasma membrane proteins are tightly regulated in cells and thus, studying these processes will reveal new insights to plasma membrane protein function and regulation. Recently, k-Space Image Correlation Spectroscopy (kICS)1 was developed to enable...... routine measurements of diffusion coefficients directly from images of fluorescently tagged plasma membrane proteins, that avoided systematic biases introduced by probe photophysics. Although the theoretical basis for the analysis is complex, the method can be implemented by nonexperts using a freely...... to the correlation function yields the diffusion coefficient. This paper provides a step-by-step guide to the image analysis and measurement of diffusion coefficients via kICS. First, a high frame rate image sequence of a fluorescently labeled plasma membrane protein is acquired using a fluorescence microscope Then...
Directory of Open Access Journals (Sweden)
Shengming Deng
2017-01-01
Full Text Available The objective of this meta-analysis is to explore the correlation between the apparent diffusion coefficient (ADC on diffusion-weighted MR and the standard uptake value (SUV of 18F-FDG on PET/CT in patients with cancer. Databases such as PubMed (MEDLINE included, EMBASE, and Cochrane Database of Systematic Review were searched for relevant original articles that explored the correlation between SUV and ADC in English. After applying Fisher’s r-to-z transformation, correlation coefficient (r values were extracted from each study and 95% confidence intervals (CIs were calculated. Sensitivity and subgroup analyses based on tumor type were performed to investigate the potential heterogeneity. Forty-nine studies were eligible for the meta-analysis, comprising 1927 patients. Pooled r for all studies was −0.35 (95% CI: −0.42–0.28 and exhibited a notable heterogeneity (I2 = 78.4%; P < 0.01. In terms of the cancer type subgroup analysis, combined correlation coefficients of ADC/SUV range from −0.12 (lymphoma, n = 5 to −0.59 (pancreatic cancer, n = 2. We concluded that there is an average negative correlation between ADC and SUV in patients with cancer. Higher correlations were found in the brain tumor, cervix carcinoma, and pancreas cancer. However, a larger, prospective study is warranted to validate these findings in different cancer types.
Deng, Shengming; Wu, Zhifang; Wu, Yiwei; Zhang, Wei; Li, Jihui; Dai, Na; Zhang, Bin; Yan, Jianhua
2017-01-01
The objective of this meta-analysis is to explore the correlation between the apparent diffusion coefficient (ADC) on diffusion-weighted MR and the standard uptake value (SUV) of 18 F-FDG on PET/CT in patients with cancer. Databases such as PubMed (MEDLINE included), EMBASE, and Cochrane Database of Systematic Review were searched for relevant original articles that explored the correlation between SUV and ADC in English. After applying Fisher's r -to- z transformation, correlation coefficient ( r ) values were extracted from each study and 95% confidence intervals (CIs) were calculated. Sensitivity and subgroup analyses based on tumor type were performed to investigate the potential heterogeneity. Forty-nine studies were eligible for the meta-analysis, comprising 1927 patients. Pooled r for all studies was -0.35 (95% CI: -0.42-0.28) and exhibited a notable heterogeneity ( I 2 = 78.4%; P correlation coefficients of ADC/SUV range from -0.12 (lymphoma, n = 5) to -0.59 (pancreatic cancer, n = 2). We concluded that there is an average negative correlation between ADC and SUV in patients with cancer. Higher correlations were found in the brain tumor, cervix carcinoma, and pancreas cancer. However, a larger, prospective study is warranted to validate these findings in different cancer types.
Pellis, E.P.M.; Franssen-Hal, van N.L.W.; Burema, J.; Keijer, J.
2003-01-01
We show that the intraclass correlation coefficient (ICC) can be used as a relatively simple statistical measure to assess methodological and biological variation in DNA microarray analysis. The ICC is a measure that determines the reproducibility of a variable, which can easily be calculated from
Nakagawa, Shinichi; Johnson, Paul C D; Schielzeth, Holger
2017-09-01
The coefficient of determination R 2 quantifies the proportion of variance explained by a statistical model and is an important summary statistic of biological interest. However, estimating R 2 for generalized linear mixed models (GLMMs) remains challenging. We have previously introduced a version of R 2 that we called [Formula: see text] for Poisson and binomial GLMMs, but not for other distributional families. Similarly, we earlier discussed how to estimate intra-class correlation coefficients (ICCs) using Poisson and binomial GLMMs. In this paper, we generalize our methods to all other non-Gaussian distributions, in particular to negative binomial and gamma distributions that are commonly used for modelling biological data. While expanding our approach, we highlight two useful concepts for biologists, Jensen's inequality and the delta method, both of which help us in understanding the properties of GLMMs. Jensen's inequality has important implications for biologically meaningful interpretation of GLMMs, whereas the delta method allows a general derivation of variance associated with non-Gaussian distributions. We also discuss some special considerations for binomial GLMMs with binary or proportion data. We illustrate the implementation of our extension by worked examples from the field of ecology and evolution in the R environment. However, our method can be used across disciplines and regardless of statistical environments. © 2017 The Author(s).
Energy Technology Data Exchange (ETDEWEB)
Tobajas, M.; Garcia-Calvo, E. [Dept. de Ingenieria Quimica, Univ. de Alcala, Alcala de Henares (Spain)
2000-05-01
Mass transfer in bioreactors has been examined. In the present work, dynamic methods are used for the determination of K{sub L}a values for water, model media and a fermentation broth (Candida utilis) in an airlift reactor. The conventional dynamic method is applied at the end of the microbial process in order to avoid an alteration in the metabolism of the microorganisms. New dynamic methods are used to determine K{sub L}a in an airlift reactor during the microbial growth of Candida utilis on glucose. One of the methods is based on the continuous measurement of carbon dioxide production while the other method is based on the relationship between the oxygen transfer and biomass growth rates. These methods of determining K{sub L}a does not interfere with the microorganisms action. A theoretical mass transfer model has been used for K{sub L}a estimation for the systems described above. Some differences between calculated and measured values are found for fermentation processes due to the model is developed for two-phase air-water systems. Nevertheless, the average deviation between the predicted values and those obtained from the relationship between oxygen transfer and biomass production rates are lower than 25% in any case. (orig.)
Directory of Open Access Journals (Sweden)
Josué Imbert‐González
2014-08-01
Full Text Available La transferencia de calor incrementada por métodos pasivos se emplea en diversosintercambiadores de calor de alta efectividad. El objetivo del trabajo presentado fue la evaluación del estado de las investigaciones en el campo de la transferencia de calor mejorada en espacios anulares, a partir del empleo de elementos turbulizadores helicoidales como técnicas pasivas. La revisión se centró en el empleo de láminas helicoidales y espirales, la obtención de ecuaciones de correlación del coeficiente de transferencia de calor incrementado, el coeficiente de fricción y la evaluación que se realiza de este proceso por parte de diferentes autores. El análisis crítico permitió realizar valoraciones integradas y recomendar sobre los aspectos que podrían ser analizados en el futuro en esta temática.Palabras claves: transferencia de calor incrementada, láminas helicoidales, espirales, espacios anulares, métodos pasivos._______________________________________________________________________________AbstractThe transfer enhancement by passive methods is used in several heat exchanger of high effectiveness. The objective of the presented work was the evaluation of the state of the investigations in heat transfer enhancement in annular spaces, from the employment of elements helical. The revision was centered in the employment of twisted tape and wire coil in spiral, the equations of correlation obtained of the coefficient of transfer of increased heat, the coefficient of friction and the evaluation that was carried out of this process on the part of different authors. From the critical analysis of the published results, the authors recommend on the topics that can be analyzed in the future in this area.Key words: heat transfer enhancement, twisted tape, helical springs, annular spaces, passive methods.
Lakin, B A; Grasso, D J; Shah, S S; Stewart, R C; Bansal, P N; Freedman, J D; Grinstaff, M W; Snyder, B D
2013-01-01
The aim of this study is to evaluate whether contrast-enhanced computed tomography (CECT) attenuation, using a cationic contrast agent (CA4+), correlates with the equilibrium compressive modulus (E) and coefficient of friction (μ) of ex vivo bovine articular cartilage. Correlations between CECT attenuation and E (Group 1, n = 12) and μ (Group 2, n = 10) were determined using 7 mm diameter bovine osteochondral plugs from the stifle joints of six freshly slaughtered, skeletally mature cows. The equilibrium compressive modulus was measured using a four-step, unconfined, compressive stress-relaxation test, and the coefficients of friction were determined from a torsional friction test. Following mechanical testing, samples were immersed in CA4+, imaged using μCT, rinsed, and analyzed for glycosaminoglycan (GAG) content using the 1,9-dimethylmethylene blue (DMMB) assay. The CECT attenuation was positively correlated with the GAG content of bovine cartilage (R(2) = 0.87, P coefficients of friction: CECT vs μ(static) (R(2) = 0.71, P = 0.002), CECT vs μ(static_equilibrium) (R(2) = 0.79, P coefficient of friction. Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Ng, Y.C.; Colsher, C.S.; Quinn, D.J.; Thompson, S.E.
1977-01-01
This document presents tables of diet-to-milk transfer coefficients for radioactive and stable isotopes in the cow. The values are based on an extensive literature review of the secretion of radioisotopes in milk and the concentrations of radioactive or stable isotopes in milk and feed. Transfer coefficients were compiled and tabulated for isotopes of more than 70 elements. The values are summarized in a table of elemental transfer coefficients and also organized into separate tables that reveal their elemental systematics and the effects of physical and chemical form
Energy Technology Data Exchange (ETDEWEB)
Ng, Y C; Colsher, C S; Quinn, D J; Thompson, S E
1977-07-15
This document presents tables of diet-to-milk transfer coefficients for radioactive and stable isotopes in the cow. The values are based on an extensive literature review of the secretion of radioisotopes in milk and the concentrations of radioactive or stable isotopes in milk and feed. Transfer coefficients were compiled and tabulated for isotopes of more than 70 elements. The values are summarized in a table of elemental transfer coefficients and also organized into separate tables that reveal their elemental systematics and the effects of physical and chemical form.
International Nuclear Information System (INIS)
Galanda, D.; Matel, L.
2003-01-01
The present work is devoted to an estimation of the transfer coefficient between reared oyster mushrooms and their support die, which was injected with known activity of Am-241 and Pu-242. After 2 months when we get the reared mushrooms of cane oyster mushrooms were dried and prepared by liquid extraction with Aliquat 336. The samples were measured by α-spectrometry. The results of activity Am-241 and Pu-242 in the mushrooms body and residual activity in the support were detected and calculated. (authors)
DEFF Research Database (Denmark)
Feyissa, Aberham Hailu; Christensen, Martin Gram; Pedersen, Søren Juhl
2015-01-01
This paper presents and demonstrates a novel idea of using spherical potatoes as a dispensable, cheap device for determining the fluid-to-particle heat transfer coefficient, hfp in vessel cooking processes. The transmission of heat through the potato can be traced by measuring the distance from...... that the method is rather precise at relevant values of hfp in vessel cooking (100–300 [W/m2K]), allowing a prediction of the centre temperature within ±0.6°C....
Determination of the mass-transfer coefficient in liquid phase in a stream-bubble contact device
Dmitriev, A. V.; Dmitrieva, O. S.; Madyshev, I. N.
2016-09-01
One of the most effective energy saving technologies is the improvement of existing heat and mass exchange units. A stream-bubble contact device is designed to enhance the operation efficiency of heat and mass exchange units. The stages of the stream-bubble units that are proposed by the authors for the decarbonization process comprise contact devices with equivalent sizes, whose number is determined by the required performance of a unit. This approach to the structural design eliminates the problems that arise upon the transition from laboratory samples to industrial facilities and makes it possible to design the units of any required performance without a decrease in the effectiveness of mass exchange. To choose the optimal design that provides the maximum effectiveness of the mass-exchange processes in units and their intensification, the change of the mass-transfer coefficient is analyzed with the assumption of a number of parameters. The results of the study of the effect of various structural parameters of a stream-bubble contact device on the mass-transfer coefficient in the liquid phase are given. It is proven that the mass-transfer coefficient increases in the liquid phase, in the first place, with the growth of the level of liquid in the contact element, because the rate of the liquid run-off grows in this case and, consequently, the time of surface renewal is reduced; in the second place, with an increase in the slot diameter in the downpipe, because the jet diameter and, accordingly, their section perimeter and the area of the surface that is immersed in liquid increase; and, in the third place, with an increase in the number of slots in the downpipe, because the area of the surface that is immersed in the liquid of the contact element increases. Thus, in order to increase the mass-transfer coefficient in the liquid phase, it is necessary to design the contact elements with a minimum width and a large number of slots and their increased diameter; in
International Nuclear Information System (INIS)
Stiller, W.
1985-01-01
A classical collision theory is used to describe thermal bimolecular rate coefficeints for reaction between positive and negative ions and polar molecules in a carrier gas. Special attention is paid to ion-molecule reaction in which proton transfer occurs. These reactions play an important role in terrestrial plasma devices, in ionosphere, in planetary atmospheres and in interstellar matter. The equilibrium rate coefficients of the reactions are calculated based on a microscopic reactive cross section derived from a long distance polar molecule-ion potential. The results are compared with experimental values of afterglow measurements. (D.Gy.)
On the Construction of Bivariate Exponential Distributions with an Arbitrary Correlation Coefficient
DEFF Research Database (Denmark)
Bladt, Mogens; Nielsen, Bo Friis
2010-01-01
coefficient (also negative). Secondly, the class satisfies that any linear combination (projection) of the marginal random variables is a phase-type distribution. The latter property is partially important for the development of hypothesis testing in linear models. Finally, it is easy to simulate...
De Mezquia, D Alonso; Bou-Ali, M Mounir; Larrañaga, M; Madariaga, J A; Santamaría, C
2012-03-08
In this work we have measured the molecular diffusion coefficient of the n-alkane binary series nC(i)-nC(6), nC(i)-nC(10), and nC(i)-nC(12) at 298 K and 1 atm and a mass fraction of 0.5 by using the so-called sliding symmetric tubes technique. The results show that the diffusion coefficient at this concentration is proportional to the inverse viscosity of the mixture. In addition, we have also measured the diffusion coefficient of the systems nC(12)-nC(6), nC(12)-nC(7), and nC(12)-nC(8) as a function of concentration. From the data obtained, it is shown that the diffusion coefficient of the n-alkane binary mixtures at any concentration can be calculated from the molecular weight of the components and the dynamic viscosity of the corresponding mixture at 50% mass fraction.
International Nuclear Information System (INIS)
Hodge, S.A.
1979-12-01
Because convective heat transfer is enhanced in flow past rough surfaces, much experimental and analytical effort over the past several decades has been devoted to the evaluation of artificial roughening for potential application to the heat transfer surfaces of gas-cooled reactors. Unfortunately, much of the analytical development in this field has been inadequately explained in the literature; this has led to misinterpretation of some of the subsequent experimental findings, compounding the uncertainty. This work provides a critical review of the underlying assumptions, theoretical foundations, and supporting experimental evidence for the analytical procedures in current use for the evaluation of roughness effects. It is a concise presentation of the available formulations with recommendations concerning their applicability to rough rod bundles
Steyn, Gideon; Vermeulen, Christiaan
2018-05-01
An experiment was designed to study the effect of the jet direction on convective heat-transfer coefficients in single-jet gas cooling of a small heated surface, such as typically induced by an accelerated ion beam on a thin foil or specimen. The hot spot was provided using a small electrically heated plate. Heat-transfer calculations were performed using simple empirical methods based on dimensional analysis as well as by means of an advanced computational fluid dynamics (CFD) code. The results provide an explanation for the observed turbulent cooling of a double-foil, Havar beam window with fast-flowing helium, located on a target station for radionuclide production with a 66 MeV proton beam at a cyclotron facility.
International Nuclear Information System (INIS)
Jung, B. R.; Park, H. S.; Chung, D. M.; Baik, S. J.
1999-01-01
The computer program SAFE has been used to size and analyze the performance of a steam generator which has two types of heat transfer regions in Korean Standard Nuclear Power Plants (KSNP) and Korean Next Generation Reactor (KNGR) design. The SAFE code calculates the analytical boiling heat transfer area using the modified form of the saturated nucleate pool boiling correlation suggested by Rohsenow. The predicted heat transfer area in the boiling region is multiplied by a constant to obtain a final analytical heat transfer area. The inclusion of the multiplier in the analytical calculation has some disadvantage of loss of complete correlation by the governing heat transfer equation. Several comparative analyses have been performed quantitatively to evaluate the possibility of removing the multiplier in the analytical calculation in the SAFE code. The evaluation shows that the boiling correlation and multiplier used in predicting the boiling region heat transfer area can be replaced with other correlations predicting nearly the same heat transfer area. The removal of multiplier included in the analytical calculation will facilitate a direct use of a set of concerned analytical sizing values that can be exactly correlated by the governing heat transfer equation. In addition this will provide more reasonable basis for the steam generator thermal sizing calculation and enhance the code usability without loss of any validity of the current sizing procedure. (author)
Barroso-Maldonado, J. M.; Belman-Flores, J. M.; Ledesma, S.; Aceves, S. M.
2018-06-01
A key problem faced in the design of heat exchangers, especially for cryogenic applications, is the determination of convective heat transfer coefficients in two-phase flow such as condensation and boiling of non-azeotropic refrigerant mixtures. This paper proposes and evaluates three models for estimating the convective coefficient during boiling. These models are developed using computational intelligence techniques. The performance of the proposed models is evaluated using the mean relative error (mre), and compared to two existing models: the modified Granryd's correlation and the Silver-Bell-Ghaly method. The three proposed models are distinguished by their architecture. The first is based on directly measured parameters (DMP-ANN), the second is based on equivalent Reynolds and Prandtl numbers (eq-ANN), and the third on effective Reynolds and Prandtl numbers (eff-ANN). The results demonstrate that the proposed artificial neural network (ANN)-based approaches greatly outperform available methodologies. While Granryd's correlation predicts experimental data within a mean relative error mre = 44% and the S-B-G method produces mre = 42%, DMP-ANN has mre = 7.4% and eff-ANN has mre = 3.9%. Considering that eff-ANN has the lowest mean relative error (one tenth of previously available methodologies) and the broadest range of applicability, it is recommended for future calculations. Implementation is straightforward within a variety of platforms and the matrices with the ANN weights are given in the appendix for efficient programming.
Effect of some additives on mass transfer coefficient at a vibrating horizontal screen
Energy Technology Data Exchange (ETDEWEB)
Nosier, S.A.; El-Abd, M.Z. [Chemical Engineering Dept., Faculty of Engineering, Alexandria Univ. (Egypt); Zaki, M.M. [Environmental Engineering Dept., Faculty of Engineering, Zagazig Univ. (Egypt)
1998-01-01
The addition of small amounts of high molecular weight substances, such as polymers and surface-active agents, to fluids can produce significant reduction of friction in turbulent flow. The objectiv of the present work is to study the effect of drag-reducing additives such as Polyox WSR 301 and sodium lauryl sulfate (anionic surfactant) on the rate of mass transfer at a vibrating horizontal screen. The variables studied were the concentration of polymer and surfactant, frequency of vibration and amplitude of vibration. (orig.)
Varepo, L. G.; Trapeznikova, O. V.; Panichkin, A. V.; Roev, B. A.; Kulikov, G. B.
2018-04-01
In the framework of standardizing the process of offset printing, one of the most important tasks is the correct selection of the printing system components, taking into account the features of their interaction and behavior in the printing process. The program allows to calculate the transfer of ink on the printed material between the contacting cylindrical surfaces of the sheet-fed offset printing apparatus with the boundaries deformation. A distinctive feature of this software product is the modeling of the liquid flow having free boundaries and causing deformation of solid boundaries when flowing between the walls of two cylinders.
EXPERIMENTAL DETERMINATION OF THE HEAT TRANSFER COEFFICIENT IN AN ICE SLURRY GENERATOR
EPIFANIO MAMANI TICONA
2003-01-01
Um sistema térmico de armazenamento da energia com pasta de cristais de gelo foi desenvolvido para aplicações de condicionamento de ar e resfriamento de processos. O sistema usa um evaporador orbital de haste, um trocador de calor vertical do tipo tubo e carcaça com intensificação mecânica de transferência de calor. A pasta de gelo é produzida continuamente sem acumulação no evaporador e é compatível com unidades condensadoras convencionais, tanques de a...
The momentum transfer cross section and transport coefficients for low energy electrons in mercury
International Nuclear Information System (INIS)
McEachran, R P; Elford, M T
2003-01-01
The momentum transfer cross section for electrons incident on mercury atoms has been determined from the solution of Dirac-Fock scattering equations which included both static and dynamic multipole polarization potentials as well as full anti-symmetrization to incorporate exchange effects. This cross section is in excellent agreement between 0.2 and 3.0 eV with the cross section derived from the most recent experimental measurements. The discrepancy below 0.2 eV has been investigated using two-term transport theory
Discharge coefficient correlations for circular-arc venturi flowmeters at critical /sonic/ flow
Arnberg, B. T.; Britton, C. L.; Seidl, W. F.
1973-01-01
Experimental data are analyzed to support theoretical predictions for discharge coefficients in circular-arc venturi flow meters operating in the critical sonic flow regime at throat Reynolds numbers above 150 thousand. The data tend to verify the predicted 0.25% decrease in the discharge coefficient during transition from a laminar to turbulent boundary layer. Four different test gases and three flow measurement facilities were used in the experiments with 17 venturis with throat sizes from 0.15 to 1.37 in. and Beta ratios ranging from 0.014 to 0.25. Recommendations are given as to how the effectiveness of future studies in the field could be improved.
Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere
Courtin, Regis
1988-01-01
The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.
Lipid–water partition coefficients and correlations with uptakes by algae of organic compounds
International Nuclear Information System (INIS)
Hung, Wei-Nung; Chiou, Cary T.; Lin, Tsair-Fuh
2014-01-01
Graphical abstract: - Highlights: • Partition coefficients of contaminants with lipid triolein (K tw ) are measured. • Measured K tw values are nearly the same as the respective K ow . • Sorption of the contaminants to a dry algal powder is similarly measured. • Algal uptake of a compound occurs primarily by partition into the algal lipid. - Abstract: In view of the scarcity of the lipid–water partition coefficients (K tw ) for organic compounds, the log K tw values for many environmental contaminants were measured using ultra-pure triolein as the model lipid. Classes of compounds studied include alkyl benzenes, halogenated benzenes, short-chain chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. In addition to log K tw determination, the uptakes of these compounds from water by a dry algal species were measured to evaluate the lipid effect on the algal uptake. The measured log K tw are closely related to their respective log K ow (octanol–water), with log K ow = 1.9 to 6.5. A significant difference is observed between the present and early measured log K tw for compounds with log K ow > ∼5, which is attributed to the presence and absence of a triolein microemulsion in water affecting the solute partitioning. The observed lipid-normalized algae–water distribution coefficients (log K aw/lipid ) are virtually identical to the respective log K tw values, which manifests the dominant lipid-partition effect of the compounds with algae
International Nuclear Information System (INIS)
Artursson, P.; Karlsson, J.
1991-01-01
Monolayers of a well differentiated human intestinal epithelial cell line, Caco-2, were used as a model to study passive drug absorption across the intestinal epithelium. Absorption rate constants (expressed as apparent permeability coefficients) were determined for 20 drugs and peptides with different structural properties. The permeability coefficients ranged from approximately 5 x 10 - 8 to 5 x 10 - 5 cm/s. A good correlation was obtained between data on oral absorption in humans and the results in the Caco-2 model. Drugs that are completely absorbed in humans had permeability coefficients greater than 1 x 10 - 6 cm/s. Drugs that are absorbed to greater than 1% but less than 100% had permeability coefficients of 0.1-1.0 x 10 - 6 cm/s while drugs and peptides that are absorbed to less than 1% had permeability coefficients of less than or equal to 1 x 10 - 7 cm/s. The results indicate that Caco-2 monolayers can be used as a model for studies on intestinal drug absorption
Drabik, Dominik; Przybyło, Magda; Sikorski, Aleksander; Langner, Marek
2016-03-01
Fluorescence Correlation Spectroscopy (FCS) is a technique, which allows determination of the diffusion coefficient and concentration of fluorescent objects suspended in the solution. The measured parameter is the fluctuation of the fluorescence signal emitted by diffusing molecules. When 100 nm DOPC vesicles labeled with various fluorescent dyes (Fluorescein-PE, NBD-PE, Atto488 DOPE or βBodipy FL) were measured, different values of diffusion coefficients have been obtained. These diffusion coefficients were different from the expected values measured using the dynamic light scattering method (DLS). The FCS was initially developed for solutions containing small fluorescent molecules therefore the observed inconsistency may result from the nature of vesicle suspension itself. The duration of the fluorescence signal may depend on the following factors: the exposure time of the labeled object to the excitation beam, the photo-physical properties (e.g., stability) of a fluorophore, the theoretical model used for the calculations of the diffusion coefficient and optical properties of the vesicle suspension. The diffusion coefficients determined for differently labeled liposomes show that its dependence on vesicle size and quantity of fluorescent probed used for labeling was significant demonstrating that the fluorescence properties of the fluorophore itself (bleaching and/or blinking) were critical factors for a correct outcome of FCS experiment. The new, based on combined FCS and DLS measurements, method for the determination of the focal volume prove itself to be useful for the evaluation of a fluorescence dye with respect to its applicability for FCS experiment.
Ostrowski, Ziemowit; Rojczyk, Marek
2017-11-01
The energy balance and heat exchange for newborn baby in radiant warmer environment are considered. The present study was performed to assess the body dry heat loss from an infant in radiant warmer, using copper cast anthropomorphic thermal manikin and controlled climate chamber laboratory setup. The total body dry heat losses were measured for varying manikin surface temperatures (nine levels between 32.5 °C and 40.1 °C) and ambient air temperatures (five levels between 23.5 °C and 29.7 °C). Radiant heat losses were estimated based on measured climate chamber wall temperatures. After subtracting radiant part, resulting convective heat loses were compared with computed ones (based on Nu correlations for common geometries). Simplified geometry of newborn baby was represented as: (a) single cylinder and (b) weighted sum of 5 cylinders and sphere. The predicted values are significantly overestimated relative to measured ones by: 28.8% (SD 23.5%) for (a) and 40.9% (SD 25.2%) for (b). This showed that use of adopted general purpose correlations for approximation of convective heat losses of newborn baby can lead to substantial errors. Hence, new Nu number correlating equation is proposed. The mean error introduced by proposed correlation was reduced to 1.4% (SD 11.97%), i.e. no significant overestimation. The thermal manikin appears to provide a precise method for the noninvasive assessment of thermal conditions in neonatal care.
Energy Technology Data Exchange (ETDEWEB)
Bennion, Kevin; Moreno, Gilberto
2015-09-29
Thermal management for electric machines (motors/ generators) is important as the automotive industry continues to transition to more electrically dominant vehicle propulsion systems. Cooling of the electric machine(s) in some electric vehicle traction drive applications is accomplished by impinging automatic transmission fluid (ATF) jets onto the machine's copper windings. In this study, we provide the results of experiments characterizing the thermal performance of ATF jets on surfaces representative of windings, using Ford's Mercon LV ATF. Experiments were carried out at various ATF temperatures and jet velocities to quantify the influence of these parameters on heat transfer coefficients. Fluid temperatures were varied from 50 degrees C to 90 degrees C to encompass potential operating temperatures within an automotive transaxle environment. The jet nozzle velocities were varied from 0.5 to 10 m/s. The experimental ATF heat transfer coefficient results provided in this report are a useful resource for understanding factors that influence the performance of ATF-based cooling systems for electric machines.
International Nuclear Information System (INIS)
Johnson, J.E.; Ward, G.M.; Ennis, M.E. Jr.; Boamah, K.N.
1988-01-01
The diet-milk transfer coefficient, Fm (Bq L-1 output in milk divided by Bq d-1 intake to the animal) was studied for eight radionuclides that previously had been given little attention. The Fm values for cows and goats, respectively, were: 2.3 x 10(-5) and 1.5 x 10(-4) for /sup 99m/Tc, 1.4 x 10(-4) and 8.5 x 10(-4) for /sup 95m/Tc, 1.1 x 10(-2) for 99 Tc (goats only); 1.7 x 10(-3) and 9 x 10(-3) for 99 Mo; 4.8 x 10(-4) and 4.4 x 10(-3) for /sup 123m/Te; 4.8 x 10(-4) and 4.6 x 10(-3) for 133 Ba; 5.5 x 10(-7) and 5.5 x 10(-6) for 95 Zr; and 4.1 x 10(-7) and 6.4 x 10(-6) for 95 Nb. The goat/cow transfer coefficient ratios for milk were approximately 10, but the goat/cow ratios for meat varied by three orders of magnitude
Consideration of the loss of activity in the soil for large transfer coefficients in the food chain
International Nuclear Information System (INIS)
Brenk, H.D.; Vogt, K.J.
1978-01-01
The studies have shown that in the case of large transfer coefficients there will result a considerable overestimation of the ingestion dose if nonradioactive depletion effects are neglected. This overestimation may, depending on nuclide, vegetation and transfer coefficient, amount to two orders of magnitude. There will result e.g. for the bone exposure of a grown-up person, caused by 90 Sr taken up by the consumption of root vegetables, a dose overestimation up to a factor of 50. For the dose to the kidneys of adults by 137 Cs through consumption of beef there will result an overestimation by a factor of up to 60. And for 129 I there will be obtained an infant thyroid dose from the pasture-cow-milk pathway being too large by a factor of up to 100. In order to be able to cover these cases by a sufficiently generalized formalism, too, it appears necessary therefore to modify or extend the 'Allgemeine Berechnungsgrundlagen' (German reg. guide for evaluating the exposure from environmental contamination) in the manner proposed in the paper. (orig./HP) 891 HP/orig.- 892 MB [de
Wan, Renzhi; Zu, Yunxiao; Shao, Lin
2018-04-01
The blood echo signal maintained through Medical ultrasound Doppler devices would always include vascular wall pulsation signal .The traditional method to de-noise wall signal is using high-pass filter, which will also remove the lowfrequency part of the blood flow signal. Some scholars put forward a method based on region selective reduction, which at first estimates of the wall pulsation signals and then removes the wall signal from the mixed signal. Apparently, this method uses the correlation between wavelet coefficients to distinguish blood signal from wall signal, but in fact it is a kind of wavelet threshold de-noising method, whose effect is not so much ideal. In order to maintain a better effect, this paper proposes an improved method based on wavelet coefficient correlation to separate blood signal and wall signal, and simulates the algorithm by computer to verify its validity.
Jiang, Fan; Ding, Wei
2010-10-01
A previously published new rotation function has been improved by using a dynamic correlation coefficient as well as two new scoring functions of relative entropy and mean-square-residues to make the rotation function more robust and independent of a specific set of weights for scoring and ranking. The previously described new rotation function calculates the rotation function of molecular replacement by matching the search model directly with the Patterson vector map. The signal-to-noise ratio for the correct match was increased by averaging all the matching peaks. Several matching scores were employed to evaluate the goodness of matching. These matching scores were then combined into a single total score by optimizing a set of weights using the linear regression method. It was found that there exists an optimal set of weights that can be applied to the global rotation search and the correct solution can be ranked in the top 100 or less. However, this set of optimal weights in general is dependent on the search models and the crystal structures with different space groups and cell parameters. In this work, we try to solve this problem by designing a dynamic correlation coefficient. It is shown that the dynamic correlation coefficient works for a variety of space groups and cell parameters in the global search of rotation function. We also introduce two new matching scores: relative entropy and mean-square-residues. Last but not least, we discussed a valid method for the optimization of the adjustable parameters for matching vectors.
Wu, Zi Yi; Xie, Ping; Sang, Yan Fang; Gu, Hai Ting
2018-04-01
The phenomenon of jump is one of the importantly external forms of hydrological variabi-lity under environmental changes, representing the adaption of hydrological nonlinear systems to the influence of external disturbances. Presently, the related studies mainly focus on the methods for identifying the jump positions and jump times in hydrological time series. In contrast, few studies have focused on the quantitative description and classification of jump degree in hydrological time series, which make it difficult to understand the environmental changes and evaluate its potential impacts. Here, we proposed a theatrically reliable and easy-to-apply method for the classification of jump degree in hydrological time series, using the correlation coefficient as a basic index. The statistical tests verified the accuracy, reasonability, and applicability of this method. The relationship between the correlation coefficient and the jump degree of series were described using mathematical equation by derivation. After that, several thresholds of correlation coefficients under different statistical significance levels were chosen, based on which the jump degree could be classified into five levels: no, weak, moderate, strong and very strong. Finally, our method was applied to five diffe-rent observed hydrological time series, with diverse geographic and hydrological conditions in China. The results of the classification of jump degrees in those series were closely accorded with their physically hydrological mechanisms, indicating the practicability of our method.
Lipid–water partition coefficients and correlations with uptakes by algae of organic compounds
Energy Technology Data Exchange (ETDEWEB)
Hung, Wei-Nung [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 30011, Taiwan (China); Chiou, Cary T., E-mail: carychio@mail.ncku.edu.tw [Department of Environmental Engineering and Sustainable Environment Research Laboratory, National Cheng Kung University, Tainan 70101, Taiwan (China); U.S. Geological Survey, Denver Federal Center, Denver, CO 80225 (United States); Lin, Tsair-Fuh, E-mail: tflin@mail.ncku.edu.tw [Department of Environmental Engineering and Sustainable Environment Research Laboratory, National Cheng Kung University, Tainan 70101, Taiwan (China)
2014-08-30
Graphical abstract: - Highlights: • Partition coefficients of contaminants with lipid triolein (K{sub tw}) are measured. • Measured K{sub tw} values are nearly the same as the respective K{sub ow}. • Sorption of the contaminants to a dry algal powder is similarly measured. • Algal uptake of a compound occurs primarily by partition into the algal lipid. - Abstract: In view of the scarcity of the lipid–water partition coefficients (K{sub tw}) for organic compounds, the log K{sub tw} values for many environmental contaminants were measured using ultra-pure triolein as the model lipid. Classes of compounds studied include alkyl benzenes, halogenated benzenes, short-chain chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. In addition to log K{sub tw} determination, the uptakes of these compounds from water by a dry algal species were measured to evaluate the lipid effect on the algal uptake. The measured log K{sub tw} are closely related to their respective log K{sub ow} (octanol–water), with log K{sub ow} = 1.9 to 6.5. A significant difference is observed between the present and early measured log K{sub tw} for compounds with log K{sub ow} > ∼5, which is attributed to the presence and absence of a triolein microemulsion in water affecting the solute partitioning. The observed lipid-normalized algae–water distribution coefficients (log K{sub aw/lipid}) are virtually identical to the respective log K{sub tw} values, which manifests the dominant lipid-partition effect of the compounds with algae.
Jameson, A. R.
1990-01-01
The relationship between the rainfall rate (R) obtained from radiometric brightness temperatures and the extinction coefficient (k sub e) is investigated by computing the values of k sub e over a wide range of rainfall rates, for frequencies from 3 to 25 GHz. The results show that the strength of the relation between the R and the k sub e values exhibits considerable variation for frequencies at this range. Practical suggestions are made concerning the selection of particular frequencies for rain measurements to minimize the error in R determinations.
Czech Academy of Sciences Publication Activity Database
Krištoufek, Ladislav
Roč. 406 , č. 1 (2014), s. 169-175 ISSN 0378-4371 R&D Projects: GA ČR(CZ) GP14-11402P Grant - others:GA ČR(CZ) GAP402/11/0948 Program:GA Institutional support: RVO:67985556 Keywords : correlations * econophysics * non-stationarity Subject RIV: AH - Economics Impact factor: 1.732, year: 2014 http://library.utia.cas.cz/separaty/2014/E/kristoufek-0433529.pdf
International Nuclear Information System (INIS)
Han, Xianhong; Hao, Xin; Yang, Kun; Zhong, Yaoyao
2013-01-01
Heat transfer is a crucial aspect for hot stamping process, the fully austenitized boron steel blank with temperature about 900°C is transferred to the tool, then formed rapidly and quenched in the cooled tool. The desired fully martensitic transformation will happen only if the cooling rate exceeds a critical value approximately 27 K/s. During such process, the heat transfer coefficient (abbreviated as HTC) between the tool and blank plays a decisive role for the variation of the blank temperature. In this work, a theoretical formula based on the joint-roughness model is presented to describe the law of HTC, which relies on the roughness, hardness, and other material parameters of the tool and blank. Moreover, a non-contact temperature measuring system based on the infrared thermal camera is built to catch the temperature change course, and then the HTC value is derived through the inverse analysis. Based on the theoretical and experimental results, the change rule of HTC especially its dependence on the process pressure will be discussed in detail
Surov, Alexey; Meyer, Hans Jonas; Wienke, Andreas
2017-08-29
The purpose of this meta-analysis was to provide clinical evidence regarding relationship between ADC and cellularity in different tumors based on large patient data. Medline library was screened for associations between ADC and cell count in different tumors up to September 2016. Only publications in English were extracted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA) was used for the research. Overall, 39 publications with 1530 patients were included into the analysis. The following data were extracted from the literature: authors, year of publication, number of patients, tumor type, and correlation coefficients. The pooled correlation coefficient for all studies was ρ = -0.56 (95 % CI = [-0.62; -0.50]),. Correlation coefficients ranged from ρ =-0.25 (95 % CI = [-0.63; 0.12]) in lymphoma to ρ=-0.66 (95 % CI = [-0.85; -0.47]) in glioma. Other coefficients were as follows: ovarian cancer, ρ = -0.64 (95% CI = [-0.76; -0.52]); lung cancer, ρ = -0.63 (95 % CI = [-0.78; -0.48]); uterine cervical cancer, ρ = -0.57 (95 % CI = [-0.80; -0.34]); prostatic cancer, ρ = -0.56 (95 % CI = [-0.69; -0.42]); renal cell carcinoma, ρ = -0.53 (95 % CI = [-0.93; -0.13]); head and neck squamous cell carcinoma, ρ = -0.53 (95 % CI = [-0.74; -0.32]); breast cancer, ρ = -0.48 (95 % CI = [-0.74; -0.23]); and meningioma, ρ = -0.45 (95 % CI = [-0.73; -0.17]).
CORRELATION COEFFICIENTS BETWEEN THE NUMBERS OF CATEGORIES TILLERS ON SIGNALGRASS PASTURE
Directory of Open Access Journals (Sweden)
Manoel Eduardo Rozalino Santos
2011-07-01
Full Text Available The understanding of relationship between the numbers of tillers categories allows the identification of compensatory mechanisms that ensure plants adaptation to grazing. Thus, this work was conducted to evaluate the associations between densities of various tillers categories in same Brachiaria decumbens pasture under continuous stocking with cattle. The tillers were measured with different growth sources, developmental stages, and defoliation and sizes levels in sites of same pasture with plants of 10, 20, 30 and 40 cm. Pearson linear correlation between the different tillers categories were estimated. The vegetative tillers number (VTN correlated positively with percentage of tillers with up to 20 cm. The response pattern opposite occurred with reproductive (RTN and dead (DTN tillers numbers. The correlations of number of leafless tillers were positive with the percentage of tillers with less than 20 cm and negative with the percentage of tillers with more than 20 cm. The VTN correlated positively with numbers of tillers with and without defoliation, and negatively with the RNT and DNT. The number of aerial tiller was positively correlated with the number of tillers without apical meristem. In B. decumbens pasture there are tradeoffs between percentage of longer tillers and VNT, between numbers of vegetative and leafless tillers, and between VNT and RNT.