Determination of surface tension coefficient of liquids by diffraction of light on capillary waves
International Nuclear Information System (INIS)
Nikolić, D; Nešić, Lj
2012-01-01
This paper describes a simple technique for determining the coefficient of the surface tension of liquids, based on laser light diffraction on capillary waves. Capillary waves of given frequency are created by an exciter needle acting on the surface of liquid and represent a reflective diffraction grating, the constant of which (the wavelength of capillary waves) can be determined based on a known incidence angle of light (grazing angle). We obtain the coefficient of the surface tension of liquids by applying the dispersion relation for capillary waves and analyze the difficulties that arise when setting up and conducting the experiment in detail. (paper)
Ferreira, D. J. S.; Bezerra, B. N.; Collyer, M. N.; Garcia, A.; Ferreira, I. L.
2018-04-01
The simulation of casting processes demands accurate information on the thermophysical properties of the alloy; however, such information is scarce in the literature for multicomponent alloys. Generally, metallic alloys applied in industry have more than three solute components. In the present study, a general solution of Butler's formulation for surface tension is presented for multicomponent alloys and is applied in quaternary Al-Cu-Si-Fe alloys, thus permitting the Gibbs-Thomson coefficient to be determined. Such coefficient is a determining factor to the reliability of predictions furnished by microstructure growth models and by numerical computations of solidification thermal parameters, which will depend on the thermophysical properties assumed in the calculations. The Gibbs-Thomson coefficient for ternary and quaternary alloys is seldom reported in the literature. A numerical model based on Powell's hybrid algorithm and a finite difference Jacobian approximation has been coupled to a Thermo-Calc TCAPI interface to assess the excess Gibbs energy of the liquid phase, permitting liquidus temperature, latent heat, alloy density, surface tension and Gibbs-Thomson coefficient for Al-Cu-Si-Fe hypoeutectic alloys to be calculated, as an example of calculation capabilities for multicomponent alloys of the proposed method. The computed results are compared with thermophysical properties of binary Al-Cu and ternary Al-Cu-Si alloys found in the literature and presented as a function of the Cu solute composition.
International Nuclear Information System (INIS)
Mohammad, Abubaker A.; Alkhaldi, Khaled H.A.E.; AlTuwaim, Mohammad S.; Al-Jimaz, Adel S.
2013-01-01
Highlights: ► Physical properties of binary mixtures of DMF+1-pentanol, 1-hexanol, or 1-heptanol. ► Viscosity and surface tension were measured. ►Δη, Δσ σ and G ∗E were calculated using the experimental data. ► H σ and S σ were determined using the surface tension data. ► Semi-empirical relations were used to estimate the viscosity of liquid mixtures. - Abstract: Viscosity η and surface tension σ were measured for binary mixtures of N,N-dimethylformamide DMF with pentan-1-ol, hexan-1-ol, and heptan-1-ol at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure over the entire mole fraction range. Deviations in viscosity Δη and surface tension Δσ were calculated using experimental results. Moreover, the values of the excess Gibbs free energy of activation G ∗E , surface enthalpy H σ and surface entropy S σ of these mixtures were determined. Viscosity measurements of the binary systems were correlated with Grunberg and Nissan, the three-body and four-body McAllister expressions. Viscosity deviation, surface tension deviation and excess Gibbs energy of activation functions were fitted to the method of Redlich–Kister (R–K) polynomial to estimate the coefficients and standard deviations. The effects of chain length of alkan-1-ols and temperature on the thermodynamic properties of binary systems were studied.
New sensitive micro-measurements of dynamic surface tension and diffusion coefficients
DEFF Research Database (Denmark)
Kinoshita, Koji; Ortiz, Elisa Parra; Needham, David
2017-01-01
Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain “dead time” at initial measurement....... These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the “micropipette interfacial area-expansion method” was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion...... for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2 ± 0.8 × 10−6 cm2/s, showed excellent agreement with the result from an alternative method, “single microdroplet catching method”, to measure the diffusion coefficient from diffusion-controlled microdroplet...
International Nuclear Information System (INIS)
Kim, Jae Kwan; Cho, Hye Sung; Jung, Ho-Sup; Suh, Kahp-Yang; Lim, Kipil; Kim, Ki-Bum; Choi, Dae-Geun; Jeong, Jun-Ho
2012-01-01
We report on nanoimprinting of polymer thin films at 30 nm scale resolution using two types of ultraviolet (UV)-curable, flexible polymer molds: perfluoropolyether (PFPE) and polyurethane acrylate (PUA). It was found that the quality of nanopatterning at the 30 nm scale is largely determined by the combined effects of surface tension and the coefficient of thermal expansion of the polymer mold. In particular, the polar component of surface tension may play a critical role in clean release of the mold, as evidenced by much reduced delamination or broken structures for the less polarized PFPE mold when patterning a relatively hydrophilic PMMA film. In contrast, such problems were not notably observed with a relatively hydrophobic PS film for both polymer molds. In addition, the demolding characteristic was also influenced by the coefficient of thermal expansion so that no delamination or uniformity problems were observed when patterning a UV-curable polymer film at room temperature. These results suggest that a proper polymeric mold material needs to be chosen for patterning polymer films under different surface properties and processing conditions, providing insights into how a clean demolding characteristic can be obtained at 30 nm scale nanopatterning. (paper)
Surface tension anomalies in room temperature ionic liquids-acetone solutions
Abe, Hiroshi; Murata, Keisuke; Kiyokawa, Shota; Yoshimura, Yukihiro
2018-05-01
Surface tension anomalies were observed in room temperature ionic liquid (RTIL)-acetone solutions. The RTILs are 1-alkyl-3-methylimidazorium iodide with [Cnmim][I] in a [Cnmim][I]-x mol% acetone. The maximum value of the surface tension appeared at 40 mol% acetone, although density decreased monotonically with an increase in acetone concentration. A small alkyl chain length effect of the Cnmim+ cations was observed in the surface tension. By the Gibbs adsorption isotherm, it was found that I- anion-mediated surface structure became dominant above 40 mol%. In the different [Cnmim][TFSI]-acetone mixtures, normal decay of the surface tension was observed on the acetone concentration scale, where TFSI- is bis(trifluoromethanesulfonyl)imide.
Surface tension estimation of high temperature melts of the binary alloys Ag-Au
Dogan, Ali; Arslan, Hüseyin
2017-11-01
Surface tension calculation of the binary alloys Ag-Au at the temperature of 1381 K, where Ag and Au have similar electronic structures and their atomic radii are comparable, are carried out in this study using several equations over entire composition range of Au. Apparently, the deviations from ideality of the bulk solutions, such as activities of Ag and Au are small and the maximum excess Gibbs free energy of mixing of the liquid phase is for instance -4500 J/mol at XAu = 0.5. Besides, the results obtained in Ag-Au alloys that at a constant temperature the surface tension increases with increasing composition while the surface tension decreases as the temperature increases for entire composition range of Au. Although data about surface tension of the Ag-Au alloy are limited, it was possible to make a comparison for the calculated results for the surface tension in this study with the available experimental data. Taken together, the average standard error analysis that especially the improved Guggenheim model in the other models gives the best agreement along with the experimental results at temperature 1383 K although almost all models are mutually in agreement with the other one.
Directory of Open Access Journals (Sweden)
Yizhak Marcus
2018-01-01
Full Text Available The critical temperatures of two dozen deep eutectic solvents, for only some of which these have been estimated previously, were estimated from the temperature dependences of their surface tensions and densities available in the literature according to the Eötvös and the Guggenheim expressions.
International Nuclear Information System (INIS)
Maroto, J A; Nieves, F J de las; Quesada-Perez, M
2004-01-01
A classical experience in a physics student laboratory is to determine the surface tension of a liquid versus the temperature and to check the linear appearance of the obtained graph. In this work we show a simple method to estimate the critical temperature of three liquids by using experimental data of surface tension at different temperatures. By a logarithm fitting between surface tension and temperature, the critical temperature can be determined and compared with data from the literature. For two liquids (butanol and nitrobenzene) the comparison is acceptable but the differences are too high for the third liquid (water). By discussing the results it seems to be clear that the difference between the critical temperature of the liquid and the maximum temperature of the surface tension measurements is the determining factor in obtaining acceptable results. From this study it is possible to obtain more information on the liquid characteristics from surface tension measurements that are currently carried out in a student laboratory. Besides, in this paper it is shown how to select the most suitable liquids which provide both acceptable values for the critical temperature and measurements of the surface tension at moderate temperatures. The complementary use of numerical methods permits us to offer a complete experience for the students with a simple laboratory experiment which we recommend for physics students in advanced university courses
Brosius, Nevin; Ward, Kevin; Matsumoto, Satoshi; SanSoucie, Michael; Narayanan, Ranga
2018-01-01
In this work, a method for the measurement of surface tension using continuous periodic forcing is presented. To reduce gravitational effects, samples are electrostatically levitated prior to forcing. The method, called Faraday forcing, is particularly well suited for fluids that require high temperature measurements such as liquid metals where conventional surface tension measurement methods are not possible. It offers distinct advantages over the conventional pulse-decay analysis method when the sample viscosity is high or the levitation feedback control system is noisy. In the current method, levitated drops are continuously translated about a mean position at a small, constant forcing amplitude over a range of frequencies. At a particular frequency in this range, the drop suddenly enters a state of resonance, which is confirmed by large executions of prolate/oblate deformations about the mean spherical shape. The arrival at this resonant condition is a signature that the parametric forcing frequency is equal to the drop's natural frequency, the latter being a known function of surface tension. A description of the experimental procedure is presented. A proof of concept is given using pure Zr and a Ti 39.5 Zr 39.5 Ni 21 alloy as examples. The results compare favorably with accepted literature values obtained using the pulse-decay method.
Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy
Directory of Open Access Journals (Sweden)
Deng Zhenghua
2013-03-01
Full Text Available Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%Al alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method (MBPM. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%Al alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is 1wt.%. The surface tension of the molten Mg-9wt.%Al alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%Al alloy decreases exponentially with the increase of temperature.
Núñez-Rojas, Edgar; Aguilar-Pineda, Jorge Alberto; Pérez de la Luz, Alexander; de Jesús González, Edith Nadir; Alejandre, José
2018-02-08
The transferable potential for a phase equilibria force field in its united-atom version, TraPPE_UA, is evaluated for 41 polar liquids that include alcohols, thiols, ethers, sulfides, aldehydes, ketones, and esters to determine its ability to reproduce experimental properties that were not included in the parametrization procedure. The intermolecular force field parameters for pure components were fit to reproduce experimental boiling temperature, vapor-liquid coexisting densities, and critical point (temperature, density, and pressure) using Monte Carlo simulations in different ensembles. The properties calculated in this work are liquid density, heat of vaporization, dielectric constant, surface tension, volumetric expansion coefficient, and isothermal compressibility. Molecular dynamics simulations were performed in the gas and liquid phases, and also at the liquid-vapor interface. We found that relative error between calculated and experimental data is 1.2% for density, 6% for heat of vaporization, and 6.2% for surface tension, in good agreement with the experimental data. The dielectric constant is systematically underestimated, and the relative error is 37%. Evaluating the performance of the force field to reproduce the volumetric expansion coefficient and isothermal compressibility requires more experimental data.
The law of corresponding states and surface tension of metals
International Nuclear Information System (INIS)
Digilov, R.
2001-01-01
Full Text: Surface tension of liquid metals is one of fundamental and most important quantities in theory and practice of material processing and its temperature dependence leads to the well-known Marangoni convection. Although currently methods are sufficiently precise to measure the surface tension, there are uncertainties in experimental data and its temperature dependence mainly due to impurity, which even a trace of it strongly affects the results of measurements. The theoretical treatment from the first principles is unwieldy and not always permits one to calculate the surface tension with certainty. Another active research field deals with empirical correlation between the surface tension and bulk thermodynamic properties, which we interpret as a simple consequence of the law of corresponding states. In order to relate the surface tension and to bulk properties of liquid metals the reduced formula is derived by scaling with the melting point T m (0) at p = 0 and atomic volume Ω 0 2/3 at T = 0 K as macroscopic parameters for scaling ε and a characterizing the interatomic potential in metals. The reduced surface tension and the reduced surface entropy obtained in high temperature limit are discussed and compared with the experiment. The reduced temperature coefficient of the surface tension found is a universal constant for the metals of the same structure. It is shown that pressure dependence of the surface tension, so called baric coefficient of the surface tension, can be described by pressure dependence of scaling parameters T m (p) and Ω 0 (p). (author)
Directory of Open Access Journals (Sweden)
Ali Khazaei
2014-07-01
Full Text Available In this work, artificial neural network (ANN has been employed to propose a practical model for predicting the surface tension of multi-component mixtures. In order to develop a reliable model based on the ANN, a comprehensive experimental data set including 15 ternary liquid mixtures at different temperatures was employed. These systems consist of 777 data points generally containing hydrocarbon components. The ANN model has been developed as a function of temperature, critical properties, and acentric factor of the mixture according to conventional corresponding-state models. 80% of the data points were employed for training ANN and the remaining data were utilized for testing the generated model. The average absolute relative deviations (AARD% of the model for the training set, the testing set, and the total data points were obtained 1.69, 1.86, and 1.72 respectively. Comparing the results with Flory theory, Brok-Bird equation, and group contribution theory has proved the high prediction capability of the attained model.
Kozhevnikov, Danil A.; Sheremet, Mikhail A.
2018-01-01
The effect of surface tension on laminar natural convection in a vertical cylindrical cavity filled with a weak evaporating liquid has been analyzed numerically. The cylindrical enclosure is insulated at the bottom, heated by a constant heat flux from the side, and cooled by a non-uniform evaporative heat flux from the top free surface having temperature-dependent surface tension. Governing equations with corresponding boundary conditions formulated in dimensionless stream function, vorticity, and temperature have been solved by finite difference method of the second-order accuracy. The influence of Rayleigh number, Marangoni number, and aspect ratio on the liquid flow and heat transfer has been studied. Obtained results have revealed that the heat transfer rate at free surface decreases with Marangoni number and increases with Rayleigh number, while the average temperature inside the cavity has an opposite behavior; namely, it growths with Marangoni number and reduces with Rayleigh number.
International Nuclear Information System (INIS)
Jacome, Paulo A.D.; Landim, Mariana C.; Garcia, Amauri; Furtado, Alexandre F.; Ferreira, Ivaldo L.
2011-01-01
Highlights: → Surface tension and the Gibbs-Thomson coefficient are computed for Al-based alloys. → Butler's scheme and ThermoCalc are used to compute the thermophysical properties. → Predictive cell/dendrite growth models depend on accurate thermophysical properties. → Mechanical properties can be related to the microstructural cell/dendrite spacing. - Abstract: In this paper, a solution for Butler's formulation is presented permitting the surface tension and the Gibbs-Thomson coefficient of Al-based binary alloys to be determined. The importance of Gibbs-Thomson coefficient for binary alloys is related to the reliability of predictions furnished by predictive cellular and dendritic growth models and of numerical computations of solidification thermal variables, which will be strongly dependent on the thermophysical properties assumed for the calculations. A numerical model based on Powell hybrid algorithm and a finite difference Jacobian approximation was coupled to a specific interface of a computational thermodynamics software in order to assess the excess Gibbs energy of the liquid phase, permitting the surface tension and Gibbs-Thomson coefficient for Al-Fe, Al-Ni, Al-Cu and Al-Si hypoeutectic alloys to be calculated. The computed results are presented as a function of the alloy composition.
Energy Technology Data Exchange (ETDEWEB)
Jacome, Paulo A.D.; Landim, Mariana C. [Department of Mechanical Engineering, Fluminense Federal University, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil); Garcia, Amauri, E-mail: amaurig@fem.unicamp.br [Department of Materials Engineering, University of Campinas, UNICAMP, PO Box 6122, 13083-970 Campinas, SP (Brazil); Furtado, Alexandre F.; Ferreira, Ivaldo L. [Department of Mechanical Engineering, Fluminense Federal University, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil)
2011-08-20
Highlights: {yields} Surface tension and the Gibbs-Thomson coefficient are computed for Al-based alloys. {yields} Butler's scheme and ThermoCalc are used to compute the thermophysical properties. {yields} Predictive cell/dendrite growth models depend on accurate thermophysical properties. {yields} Mechanical properties can be related to the microstructural cell/dendrite spacing. - Abstract: In this paper, a solution for Butler's formulation is presented permitting the surface tension and the Gibbs-Thomson coefficient of Al-based binary alloys to be determined. The importance of Gibbs-Thomson coefficient for binary alloys is related to the reliability of predictions furnished by predictive cellular and dendritic growth models and of numerical computations of solidification thermal variables, which will be strongly dependent on the thermophysical properties assumed for the calculations. A numerical model based on Powell hybrid algorithm and a finite difference Jacobian approximation was coupled to a specific interface of a computational thermodynamics software in order to assess the excess Gibbs energy of the liquid phase, permitting the surface tension and Gibbs-Thomson coefficient for Al-Fe, Al-Ni, Al-Cu and Al-Si hypoeutectic alloys to be calculated. The computed results are presented as a function of the alloy composition.
Caleman, Carl; van Maaren, Paul J; Hong, Minyan; Hub, Jochen S; Costa, Luciano T; van der Spoel, David
2012-01-10
The chemical composition of small organic molecules is often very similar to amino acid side chains or the bases in nucleic acids, and hence there is no a priori reason why a molecular mechanics force field could not describe both organic liquids and biomolecules with a single parameter set. Here, we devise a benchmark for force fields in order to test the ability of existing force fields to reproduce some key properties of organic liquids, namely, the density, enthalpy of vaporization, the surface tension, the heat capacity at constant volume and pressure, the isothermal compressibility, the volumetric expansion coefficient, and the static dielectric constant. Well over 1200 experimental measurements were used for comparison to the simulations of 146 organic liquids. Novel polynomial interpolations of the dielectric constant (32 molecules), heat capacity at constant pressure (three molecules), and the isothermal compressibility (53 molecules) as a function of the temperature have been made, based on experimental data, in order to be able to compare simulation results to them. To compute the heat capacities, we applied the two phase thermodynamics method (Lin et al. J. Chem. Phys.2003, 119, 11792), which allows one to compute thermodynamic properties on the basis of the density of states as derived from the velocity autocorrelation function. The method is implemented in a new utility within the GROMACS molecular simulation package, named g_dos, and a detailed exposé of the underlying equations is presented. The purpose of this work is to establish the state of the art of two popular force fields, OPLS/AA (all-atom optimized potential for liquid simulation) and GAFF (generalized Amber force field), to find common bottlenecks, i.e., particularly difficult molecules, and to serve as a reference point for future force field development. To make for a fair playing field, all molecules were evaluated with the same parameter settings, such as thermostats and barostats
International Nuclear Information System (INIS)
Moosavi, Majid; Khashei, Fatemeh; Sharifi, Ali; Mirzaei, Mojtaba
2017-01-01
Highlights: • Surface tension and density of three GDILs were measured at different temperatures. • Surface entropy and surface enthalpy indicate the surface ordering in these GDILs. • Parachors and critical temperatures of these systems were estimated. • Results of GDILs were compared with the results of corresponding traditional MILs. • Relations between surface tension, density and viscosity of GDILs were demonstrated. - Abstract: Surface tensions and densities of three imidazolium-based geminal dicationic ionic liquids (GDILs) with the bis(trifluoromethylsulfonyl)imide, [NTf 2 ] − , as a common anion, have been measured at ambient pressure at different temperatures in the range from 296.00 to 353.15 K. The surface thermodynamic functions such as surface entropy and surface enthalpy were derived from the temperature dependence of surface tension which indicated the surface ordering in these GDILs. As well as the parachor, the critical temperatures of these systems have been estimated using the Guggenheim and Eotvos correlations. In each case, the results of GDILs have been compared with the results of corresponding traditional monocationic ILs (MILs). Also, the relations between the surface tension and density and also surface tension and viscosity data have been demonstrated and discussed.
International Nuclear Information System (INIS)
Bagheri, Ahmad; Moradian, Zohreh
2014-01-01
Highlights: • Surface tension of non-ideal binary systems of alcohol/DMSO determined. • The surface tension data of binary mixtures were correlated with five equations. • The interaction energy values were calculated by using LWW model. • The U 12 value shows different behavior for two systems with increasing temperature. - Abstract: Surface tension of binary mixtures of tert-butyl alcohol (TBA) and iso-amyl alcohol (IAA) with DMSO (dimethyl sulfoxide) were measured over the entire concentration range at pressure of 82.5 kPa at temperatures between (298.15 and 328.15) K. Correlating the surface tension and surface tension deviation of the above mentioned binary systems was performed with empirical and thermodynamic based models. The average relative error obtained from the comparison of experimental and calculated surface tension values for the two binary systems with five models at various temperatures is less than 2%. The effect of temperature on the interaction energy values in binary mixtures has been used to obtain information about solute structural effects on DMSO. Also, the experimental data were used to evaluate the nature and type of intermolecular interactions in binary mixtures
Analysis of effect of temperature gradients on surface-tension phenomena in gas-tungsten-arc welds
International Nuclear Information System (INIS)
Lee, H.A.; Chien, P.S.J.
1982-10-01
Fluid motion directed by surface tension is considered as a contributor to heat penetration in a weld pool. The potential phenomena at the gas-liquid interface were analyzed, and the dependence of surface motion on temperature in the gas-tungsten-arc (GTA) welding process was examined. An existing heat-transfer model was used and was able to predict weld size to +- 50% of the actual value. A momentum-transfer equation was derived by considering the contribution of Lorentz force. The momentum boundary condition was developed and was able to predict the Marangoni effect. The magnitude of surface-tension-driven force is comparable to the gravitational force on one gram. An empirical approach was proposed to couple heat-transfer and momentum-transfer phenomena. A dimensional analysis identified the pertinent dimensionless groups as Reynolds, Weber, Froude, Peclet, and Power numbers and a dimensionless velocity. A simplified form of the correction was developed by combining dimensionless groups to yield a correlation with the Bond, Prandtl, and modified power numbers. Future experimental work was proposed to test the functionality of the dimensionless groups
International Nuclear Information System (INIS)
Bagheri, Ahmad; Fazli, Mostafa; Bakhshaei, Malihe
2016-01-01
Highlights: • Surface tension of DMSO + alcohol (methanol, ethanol and isopropanol) at various temperatures was measured. • The surface tension data of binary mixtures were correlated with four equations. • Intermolecular interaction of DMSO with alcohol was discussed. • The surface mole fraction of alcohol increase with increasing the length of alcohol chain. - Abstract: Surface tension of binary mixtures of methanol, ethanol and isopropanol with DMSO (dimethyl sulfoxide) was measured over the whole range of composition at atmospheric pressure of 82.5 kPa within the temperatures between (298.15 and 328.15) K. The experimental measurements were used to calculate in surface tension deviations (Δσ). The sign of Δσ for all temperatures is negative (except of methanol/DMSO system) because of the factors of hydrogen bonding and dipole–dipole interactions in the DMSO-alcohol systems. Surface tension values of the binary systems were correlated with FLW, MS, RK and LWW models. The mean standard deviation obtained from the comparison of experimental and calculated surface tension values for binary systems with three models (FLW, MS and RK) at various temperatures is less than 0.83. Also, the results of the LWW model were used to account for the interaction energy between alcohols and DMSO in binary mixtures. The temperature dependence of σ (surface tension) at fixed composition of solutions was used to estimate surface enthalpy, H s , and surface entropy, S s . The results obtained show that the values of the thermodynamic parameters for alcohol/DMSO mixtures decrease with increasing alkyl chain length of alcohol. Finally, the results are discussed in terms of surface mole fraction and lyophobicity using the extended Langmuir (EL) isotherm.
Manjunatha, N.; Sumithra, R.
2018-04-01
The problem of surface tension driven two component magnetoconvection is investigated in a Porous-Fluid system, consisting of anincompressible two component electrically conducting fluid saturatedporous layer above which lies a layer of the same fluid in the presence of a uniform vertical magnetic field. The lower boundary of the porous layeris rigid and the upper boundary of the fluid layer is free with surfacetension effects depending on both temperature and concentration, boththese boundaries are insulating to heat and mass. At the interface thevelocity, shear and normal stress, heat and heat flux, mass and mass fluxare assumed to be continuous suitable for Darcy-Brinkman model. Theeigenvalue problem is solved in linear, parabolic and inverted parabolictemperature profiles and the corresponding Thermal Marangoni Numberis obtained for different important physical parameters.
International Nuclear Information System (INIS)
Siewert, E; Schein, J; Forster, G
2013-01-01
The metal transfer is a fundamental process in gas metal arc welding, which substantially determines the shape of the weld seam and strongly influences arc formation and stability. In this investigation the material transfer from the wire electrode (anode) to the workpiece (cathode) is analysed experimentally with high accuracy using various innovative diagnostic techniques for a pulsed gas metal arc welding (PGMAW) process. A high-speed two-colour pyrometer, a calorimeter, thermocouples, a stereo optical setup and a droplet oscillation technique are used to analyse a precisely defined PGMAW process. Thus, results obtained are verified by different measurement techniques and enable a comprehensive description of the material transfer procedure. The surface temperature of both electrodes as well as the droplet temperature, enthalpy and surface tension were determined. Furthermore, the geometry of the arc, wire, droplets and weld pool were extracted in three dimensions in order to describe the interaction between the material transfer and the formation of the weld seam. The experiments are performed using argon as shielding gas and pure iron as filler and base material to reduce complex chemical processes. It turned out that the wire feed rate has the biggest influence on droplet temperature and detachment. A correlation between weld pool formation and weld pool surface temperature gradient was observed, which is mainly a function of welding speed and wire feed rate. The experimental results obtained provide a detailed data pool for use in modelling. (paper)
Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy
Deng Zhenghua; Li Huaji; Zhao Wanjun
2013-01-01
Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in...
Sarma, Rajkumar; Mondal, Pranab Kumar
2018-04-01
We investigate Marangoni instability in a thin liquid film resting on a substrate of low thermal conductivity and separated from the surrounding gas phase by a deformable free surface. Considering a nonmonotonic variation of surface tension with temperature, here we analytically derive the neutral stability curve for the monotonic and oscillatory modes of instability (for both the long-wave and short-wave perturbations) under the framework of linear stability analysis. For the long-wave instability, we derive a set of amplitude equations using the scaling k ˜(Bi) 1 /2 , where k is the wave number and Bi is the Biot number. Through this investigation, we demonstrate that for such a fluid layer upon heating from below, both monotonic and oscillatory instability can appear for a certain range of the dimensionless parameters, viz., Biot number (Bi ) , Galileo number (Ga ) , and inverse capillary number (Σ ) . Moreover, we unveil, through this study, the influential role of the above-mentioned parameters on the stability of the system and identify the critical values of these parameters above which instability initiates in the liquid layer.
International Nuclear Information System (INIS)
Mohammad, Abubaker A.; Alkhaldi, Khaled H.A.E.; AlTuwaim, Mohammad S.; Al-Jimaz, Adel S.
2014-01-01
Highlights: • Effect of temperature and chain length on η and σ of DMF + 1-alkanol binary systems. • Viscosity and surface tension were obtained. • Δη, Δσ and G ∗E were calculated using the experimental data. • H σ and S σ were determined using the surface tension data. • Semi-empirical relations were used to estimate the viscosity of liquid mixtures. - Abstract: Viscosity and surface tension of binary systems of N,N-dimethylformamide DMF with higher 1-alkanols (C 8 –C 10 ) were measured at atmospheric pressure and four different temperatures over the entire range of mole fraction. The experimental measurements were used to calculate the deviations in viscosity and surface tension. Furthermore, the excess Gibbs free energy of activation, surface enthalpy and surface entropy of the (DMF + 1-alkanols) binary mixtures were determined. In addition, the deviation and excess properties were fitted to the method of Redlich–Kister (R–K) polynomial. Viscosity data of the binary systems were correlated with three different expressions (Grunberg and Nissan, the three-body, and four-body McAllister). The effects of the chain length of the higher 1-alkanols and temperature were investigated
Galan Sanchez, L.M.; Espel, J.R.; Onink, S.A.F.; Meindersma, G.W.; Haan, de A.B.
2009-01-01
Density, viscosity, and surface tension data sets of 13 ionic liquids formed by imidazolium, pyridinium, or pyrrolidinium cations paired with dicyanamide (DCA), tetrafluoroborate (BF4¯), thiocyanate (SCN¯),methylsulfate (MeSO4¯), and trifluoroacetate (TFA) anions are reported. The properties were
Surface Tension Confines Cryogenic Liquid
Castles, Stephen H.; Schein, Michael E.
1989-01-01
New type of Dewar provides passive, constant-temperature cryogenic cooling for scientific instruments under normal-to low-gravity conditions. Known as Surface-Tension-Contained Liquid Cryogen Cooler (STCLCC), keeps liquid cryogen in known location inside the Dewar by trapping liquid inside spongelike material. Unique sponge material fills most of volume of inner tank. Sponge is all-silica, open-cell material similar to that used for Space Shuttle thermal-protection tiles.
Surface tension of H2O and D2O
International Nuclear Information System (INIS)
Vargaftik, N.B.; Voljak, L.D.; Volkov, B.N.
1975-01-01
There is a great number of works on surface tension of clean water (H 2 O) at temperatures up to 100 deg C and very few above the boiling point. Works on surface tension of heavy water (D 2 O) are insufficient. A review of works on surface tension of both kinds of water is given
Energy Technology Data Exchange (ETDEWEB)
Gharaei, R.; Hadikhani, A. [Hakim Sabzevari University, Department of Physics, Sciences Faculty, Sabzevar (Iran, Islamic Republic of)
2017-07-15
For the first time the influence of the surface energy coefficient γ and temperature T on the parameterization of the fusion barriers is systematically analyzed within the framework of the proximity formalism, namely proximity 1977, proximity 1988 and proximity 2010 models. A total of 114 fusion reactions with the condition 39 ≤ Z{sub 1}Z{sub 2} ≤ 1520 for the charge product of their participant nuclei have been studied. We present γ-dependent and T -dependent pocket formulas which reproduce the theoretical and empirical data of the fusion barrier height and position for our considered reactions with good accuracy. It is shown that the quality of the γ-dependent formula enhances by increasing the strength of the surface energy coefficient. Moreover, the obtained results confirm that imposing the thermal effects improves the agreement between the parameterized and empirical data of the barrier characteristics. (orig.)
Surface tension of normal and heavy water
International Nuclear Information System (INIS)
Straub, J.; Rosner, N.; Grigull, V.
1980-01-01
A Skeleton Table and simple interpolation equation for the surface tension of light water was developed by the Working Group III of the International Association for the Properties of Steam and is recommended as an International Standard. The Skeleton Table is based on all known measurements of the surface tension and individual data were weighted corresponding to the accuracy of the measurements. The form of the interpolation equation is based on a physical concept. It represents an extension of van der Waals-equation, where the exponent conforms to the 'Scaling Laws'. In addition for application purposes simple relations for the Laplace-coefficient and for the density difference between the liquid and gaseous phases of light water are given. The same form of interpolation equation for the surface tension can be used for heavy water, for which the coefficients are given. However, this equation is based only on a single set of data. (orig.) [de
Surface tension of liquid Al-Cu binary alloys.
Schmitz, Julianna; Brillo, Jürgen; Egry, Ivan; Schmid-Fetzer, Rainer
2009-01-01
Surface tension data of liquid Al–Cu binary alloys have been measured contactlessly using the technique of electromagnetic levitation. A digital CMOS-camera (400 fps) recorded image sequences of the oscillating liquid sample and surface tensions were determined from analysis of the frequency spectra. Measurements were performed for samples covering the entire range of composition and precise data were obtained in a broad temperature range. It was found that the surface tensions can ...
International Nuclear Information System (INIS)
Rukavishnikova, I.V.; Lokett, V.N.; Burukhin, A.S.; Stepanov, V.P.
2006-01-01
The density and interphase tension of molten mixtures of lithium fluoride with potassium, rubidium, and cesium bromides were measured over the temperature range 1120-1320 K in the region of limited mutual solubility by the hydrostatic weighing and meniscus weight methods. The dependences of properties on the size ratio between the mixed ions were determined. The critical order parameters for systems with the predominantly ionic character of interparticle interactions were estimated [ru
Measurement for Surface Tension of Aqueous Inorganic Salt
Directory of Open Access Journals (Sweden)
Jiming Wen
2018-03-01
Full Text Available Bubble columns are effective means of filtration in filtered containment venting systems. Here, the surface tension has a significant influence on bubble size distribution and bubble deformation, which have a strong impact on the behavior of the bubble column. The influence of aqueous inorganic compounds on the surface tension depends on the electrolytic activity, Debye length, entropy of ion hydration, and surface deficiencies or excess. In this work, the surface tensions of same specific aqueous solutions have been measured by different methods including platinum plate method, platinum ring method, and maximum bubble pressure method. The measured surface tensions of both sodium hydroxide and sodium thiosulfate are less than that of water. As solution temperature ranges from 20 to 75°C, the surface tension of 0.5 mol/L sodium hydroxide solution decreases from 71 to 55 mN/m while that of 1 mol/L solution decreases from 60 to 45 mN/m. Similarly during the same temperature range, the surface tension of 0.5 mol/L sodium thiosulfate decreases from 70 to 38 mN/m, and that of 1 mol/L sodium thiosulfate is between 68 and 36 mN/m. The analysis for the influence mechanism of aqueous inorganic on surface tension is provided. In addition, experimental results show that the surface tension of solid aerosol suspension liquid has no obvious difference from that of distilled water.
Stemmet, C.P.; Bartelds, F.; Schaaf, van der J.; Kuster, B.F.M.; Schouten, J.C.
2008-01-01
The gas–liquid mass transfer coefficient and other hydrodynamic parameters such as liquid holdup and frictional pressure drop are presented for gas and liquid moving in co-current upflow and downflow through solid foam packings of 10 and of 40 pores per linear inch (ppi). The effect of increasing
Kinoshita, Koji; Parra, Elisa; Needham, David
2017-02-15
Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain "dead time" at initial measurement. These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the "micropipette interfacial area-expansion method" was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion controlled molecular adsorption at the air-water interfaces. To validate the new technique, the diffusion coefficient of 1-Octanol in water was investigated with existing models: the Ward Tordai model for the long time adsorption regime (1-100s), and the Langmuir and Frumkin adsorption isotherm models for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2±0.8×10 -6 cm 2 /s, showed excellent agreement with the result from an alternative method, "single microdroplet catching method", to measure the diffusion coefficient from diffusion-controlled microdroplet dissolution, 7.3±0.1×10 -6 cm 2 /s. These new techniques for determining adsorption and diffusion coefficients can apply for a range of surface active molecules, especially the less-characterized ionic surfactants, and biological compounds such as lipids, peptides, and proteins. Copyright Â© 2016 Elsevier Inc. All rights reserved.
Surface tension confined liquid cryogen cooler
Castles, Stephen H. (Inventor); Schein, Michael E. (Inventor)
1989-01-01
A cryogenic cooler is provided for use in craft such as launch, orbital, and space vehicles subject to substantial vibration, changes in orientation, and weightlessness. The cooler contains a small pore, large free volume, low density material to restrain a cryogen through surface tension effects during launch and zero-g operations and maintains instrumentation within the temperature range of 10 to 140 K. The cooler operation is completely passive, with no inherent vibration or power requirements.
Directory of Open Access Journals (Sweden)
Xiaolu Li
2016-01-01
Full Text Available As fuel temperature increases, both its viscosity and surface tension decrease, and this is helpful to improve fuel atomization and then better combustion and emission performances of engine. Based on the self-regulated temperature property of positive temperature coefficient material, this article used a positive temperature coefficient material as electric heating element to heat diesel fuel in fuel pipeline of diesel engine. A kind of BaTiO3-based positive temperature coefficient material, with the Curie temperature of 230°C and rated voltage of 24 V, was developed, and its micrograph and element compositions were also analyzed. By the fuel pipeline wrapped in six positive temperature coefficient ceramics, its resistivity–temperature and heating characteristics were tested on a fuel pump bench. The experiments showed that in this installation, the surface temperature of six positive temperature coefficient ceramics rose to the equilibrium temperature only for 100 s at rated voltage. In rated power supply for six positive temperature coefficient ceramics, the temperature of injection fuel improved for 21°C–27°C within 100 s, and then could keep constant. Using positive temperature coefficient material to heat diesel in fuel pipeline of diesel engine, the injection mass per cycle had little change, approximately 0.3%/°C. This study provides a beneficial reference for improving atomization of high-viscosity liquids by employing positive temperature coefficient material without any control methods.
Czech Academy of Sciences Publication Activity Database
Klomfar, Jaroslav; Součková, Monika; Pátek, Jaroslav
2011-01-01
Roč. 56, č. 8 (2011), s. 3454-3462 ISSN 0021-9568 R&D Projects: GA ČR GA101/09/0010; GA AV ČR IAA200760701 Institutional research plan: CEZ:AV0Z20760514 Keywords : surface tension * density * dicyanamide * experimental data Subject RIV: BJ - Thermodynamics Impact factor: 1.693, year: 2011 http://pubs.acs.org/doi/abs/10.1021/je200502j
Nonzero Ideal Gas Contribution to the Surface Tension of Water.
Sega, Marcello; Fábián, Balázs; Jedlovszky, Pál
2017-06-15
Surface tension, the tendency of fluid interfaces to behave elastically and minimize their surface, is routinely calculated as the difference between the lateral and normal components of the pressure or, invoking isotropy in momentum space, of the virial tensor. Here we show that the anisotropy of the kinetic energy tensor close to a liquid-vapor interface can be responsible for a large part of its surface tension (about 15% for water, independent from temperature).
Fuel Temperature Coefficient of Reactivity
Energy Technology Data Exchange (ETDEWEB)
Loewe, W.E.
2001-07-31
A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.
Axelrod's model with surface tension
Pace, Bruno; Prado, Carmen P. C.
2014-06-01
In this work we propose a subtle change in Axelrod's model for the dissemination of culture. The mechanism consists of excluding from the set of potentially interacting neighbors those that would never possibly exchange. Although the alteration proposed does not alter the state space topologically, it yields significant qualitative changes, specifically the emergence of surface tension, driving the system in some cases to metastable states. The transient behavior is considerably richer, and cultural regions become stable leading to the formation of different spatiotemporal patterns. A metastable "glassy" phase emerges between the globalized phase and the disordered, multicultural phase.
Dynamical modeling of surface tension
International Nuclear Information System (INIS)
Brackbill, J.U.; Kothe, D.B.
1996-01-01
In a recent review it is said that free-surface flows ''represent some of the difficult remaining challenges in computational fluid dynamics''. There has been progress with the development of new approaches to treating interfaces, such as the level-set method and the improvement of older methods such as the VOF method. A common theme of many of the new developments has been the regularization of discontinuities at the interface. One example of this approach is the continuum surface force (CSF) formulation for surface tension, which replaces the surface stress given by Laplace's equation by an equivalent volume force. Here, we describe how CSF might be made more useful. Specifically, we consider a derivation of the CSF equations from a minimization of surface energy as outlined by Jacqmin. This reformulation suggests that if one eliminates the computation of curvature in terms of a unit normal vector, parasitic currents may be eliminated For this reformulation to work, it is necessary that transition region thickness be controlled. Various means for this, in addition to the one discussed by Jacqmin are discussed
Surface tension and density of Si-Ge melts
Ricci, Enrica; Amore, Stefano; Giuranno, Donatella; Novakovic, Rada; Tuissi, Ausonio; Sobczak, Natalia; Nowak, Rafal; Korpala, Bartłomiej; Bruzda, Grzegorz
2014-06-01
In this work, the surface tension and density of Si-Ge liquid alloys were determined by the pendant drop method. Over the range of measurements, both properties show a linear temperature dependence and a nonlinear concentration dependence. Indeed, the density decreases with increasing silicon content exhibiting positive deviation from ideality, while the surface tension increases and deviates negatively with respect to the ideal solution model. Taking into account the Si-Ge phase diagram, a simple lens type, the surface tension behavior of the Si-Ge liquid alloys was analyzed in the framework of the Quasi-Chemical Approximation for the Regular Solutions model. The new experimental results were compared with a few data available in the literature, obtained by the containerless method.
Contact Angles and Surface Tension of Germanium-Silicon Melts
Croell, A.; Kaiser, N.; Cobb, S.; Szofran, F. R.; Volz, M.; Rose, M. Franklin (Technical Monitor)
2001-01-01
Precise knowledge of material parameters is more and more important for improving crystal growth processes. Two important parameters are the contact (wetting) angle and the surface tension, determining meniscus shapes and surface-tension driven flows in a variety of methods (Czochralski, EFG, floating-zone, detached Bridgman growth). The sessile drop technique allows the measurement of both parameters simultaneously and has been used to measure the contact angles and the surface tension of Ge(1-x)Si(x) (0 less than or equal to x less than or equal to 1.3) alloys on various substrate materials. Fused quartz, Sapphire, glassy carbon, graphite, SiC, carbon-based aerogel, pyrolytic boron nitride (pBN), AIN, Si3N4, and polycrystalline CVD diamond were used as substrate materials. In addition, the effect of different cleaning procedures and surface treatments on the wetting behavior were investigated. Measurements were performed both under dynamic vacuum and gas atmospheres (argon or forming gas), with temperatures up to 1100 C. In some experiments, the sample was processed for longer times, up to a week, to investigate any changes of the contact angle and/or surface tension due to slow reactions with the substrate. For pure Ge, stable contact angles were found for carbon-based substrates and for pBN, for Ge(1-x)Si(x) only for pBN. The highest wetting angles were found for pBN substrates with angles around 170deg. For the surface tension of Ge, the most reliable values resulted in gamma(T) = (591- 0.077 (T-T(sub m)) 10(exp -3)N/m. The temperature dependence of the surface tension showed similar values for Ge(1-x)Si(x), around -0.08 x 10(exp -3)N/m K, and a compositional dependence of 2.2 x 10(exp -3)N/m at%Si.
Density and surface tension of ionic liquids.
Kolbeck, C; Lehmann, J; Lovelock, K R J; Cremer, T; Paape, N; Wasserscheid, P; Fröba, A P; Maier, F; Steinrück, H-P
2010-12-30
We measured the density and surface tension of 9 bis[(trifluoromethyl)sulfonyl]imide ([Tf(2)N](-))-based and 12 1-methyl-3-octylimidazolium ([C(8)C(1)Im](+))-based ionic liquids (ILs) with the vibrating tube and the pendant drop method, respectively. This comprehensive set of ILs was chosen to probe the influence of the cations and anions on density and surface tension. When the alkyl chain length in the [C(n)C(1)Im][Tf(2)N] series (n = 1, 2, 4, 6, 8, 10, 12) is increased, a decrease in density is observed. The surface tension initially also decreases but reaches a plateau for alkyl chain lengths greater than n = 8. Functionalizing the alkyl chains with ethylene glycol groups results in a higher density as well as a higher surface tension. For the dependence of density and surface tension on the chemical nature of the anion, relations are only found for subgroups of the studied ILs. Density and surface tension values are discussed with respect to intermolecular interactions and surface composition as determined by angle-resolved X-ray photoelectron spectroscopy (ARXPS). The absence of nonvolatile surface-active contaminants was proven by ARXPS.
On relation between the quark-gluon bag surface tension and the colour tube string tension
International Nuclear Information System (INIS)
Bugaev, K.A.; Zinovjev, G.M.
2010-01-01
We revisit the bag phenomenology of deconfining phase transition aiming to replenish it by introducing systematically the bag surface tension. Comparing the free energies of such bags and the strings confining the static quark-antiquark pair, we express the string tension in terms of the bag surface tension and the bulk pressure in order to estimate the bag characteristics using the lattice QCD (LQCD) data. Our analysis of the bag entropy density demonstrates that the surface tension coefficient is amazingly negative at the cross-over (continuous transition). The approach developed allows us to naturally account for an origin of a pronounced maximum (observed in the LQCD studies) in the behaviour of heavy quark-antiquark pair entropy. The vicinity of the (tri-)critical endpoint is also analyzed to clarify the meaning of vanishing surface tension coefficient.
Surface Tension Measurements with a Smartphone
Goy, Nicolas-Alexandre; Denis, Zakari; Lavaud, Maxime; Grolleau, Adrian; Dufour, Nicolas; Deblais, Antoine; Delabre, Ulysse
2017-01-01
Smartphones are increasingly used in higher education and at university in mechanics, acoustics, and even thermodynamics as they offer a unique way to do simple science experiments. In this article, we show how smartphones can be used in fluid mechanics to measure surface tension of various liquids, which could help students understand the concept…
Exact analytical density profiles and surface tension
Indian Academy of Sciences (India)
journal of. May 2005 physics pp. 785–801. Classical charged fluids at equilibrium near ... is provided by the excess surface tension for an air–water interface, which is determined ... the potential drop created by the electric layer which appears as soon as the fluid has ...... radii, by symmetry, the charge density profile is flat,.
Theoretical calculations of the surface tension of Ag(1-x)-Cu(x) liquid alloys
International Nuclear Information System (INIS)
Aqra, Fathi; Ayyad, Ahmed
2011-01-01
Highlights: → A thermodynamic model for calculating the surface tension, and its temperature and composition dependences, of liquid binary alloys is described. → The model does not require the prior knowledge of the surface concentration and Gibbs energy. → The surface tension of the liquid Ag-Cu binary alloys has been calculated as a function of temperature and concentration. → The calculated values agree well with existing experimental data. - Abstract: The surface tension of silver-copper binary liquid alloys is calculated, in the frame work of Eyring theory. The calculations were made for different compositions (mole fraction, x Cu = 0, 0.2, 0.4, 0.6, 0.8 and 1), in the temperature range 1100-1800 K. The surface tension decreases with temperature increase, at a fixed copper fraction x Cu , and increases with increasing copper content. The calculated results are appropriately compared with existing literature data.
The interfacial surface tension of a quark-gluon plasma fireball in a ...
Indian Academy of Sciences (India)
surface tension with the cube of the critical transition temperature is in overall ... more rigorous structures may be built depending on the phenomenological success .... k +dk in a spherically symmetric situation, and gi is the degeneracy factor ( ...
Surface tension and Wulff shape for a lattice model without spin flip symmetry.
Bodineau, T
2003-01-01
We propose a new definition of surface tension and check it in a spin model of the Pirogov-Sinai class where the spin flip symmetry is broken. We study the model at low temperatures on the phase transitions line and prove: (i) existence of the surface tension in the thermodynamic limit, for any orientation of the surface and in all dimensions $d\\ge 2$; (ii) the Wulff shape constructed with such a surface tension coincides with the equilibrium shape of the cluster which appears when fixing the total spin magnetization (Wulff problem).
Surface tension, hydrophobicity, and black holes: The entropic connection
International Nuclear Information System (INIS)
Callaway, D.J.
1996-01-01
The geometric entropy arising from partitioning space in a fluid open-quote open-quote field theory close-quote close-quote is shown to be linearly proportional to the area of an excluded region. The coefficient of proportionality is related to surface tension by a thermodynamic argument. Good agreement with experimental data is obtained for a number of fluids. The calculation employs a density-matrix formalism developed previously for studying the origin of black hole entropy. This approach may lead to a practical technique for the evaluation of thermodynamic quantities with important entropic components. copyright 1996 The American Physical Society
Quantum surface tension in ideal gases
International Nuclear Information System (INIS)
Sisman, A.
2005-01-01
Due to wave character of atoms, an ideal gas confined in a finite domain exhibits Casimir like size effects. These effects become appreciable in a domain with at least one dimension in the order of micron. On this scale, thermodynamic state functions of an ideal gas become shape and size dependent and some new effects appear. In the literature, only some domains of regular shapes have been considered. In this study, the results are generalized to a domain of an arbitrary shape by using Weyl s conjecture for density of states. It is seen that free energy expression of an ideal Maxwellian gas consists of a classical volume dependent term and also a quantum originated surface dependent term, which causes a quantum surface tension. In a rectangular box filled by an ideal gas and separated by a movable wall into two parts, it is shown that a lateral force appears on the movable wall due to quantum surface tension
Generalized surface tension bounds in vacuum decay
Masoumi, Ali; Paban, Sonia; Weinberg, Erick J.
2018-02-01
Coleman and De Luccia (CDL) showed that gravitational effects can prevent the decay by bubble nucleation of a Minkowski or AdS false vacuum. In their thin-wall approximation this happens whenever the surface tension in the bubble wall exceeds an upper bound proportional to the difference of the square roots of the true and false vacuum energy densities. Recently it was shown that there is another type of thin-wall regime that differs from that of CDL in that the radius of curvature grows substantially as one moves through the wall. Not only does the CDL derivation of the bound fail in this case, but also its very formulation becomes ambiguous because the surface tension is not well defined. We propose a definition of the surface tension and show that it obeys a bound similar in form to that of the CDL case. We then show that both thin-wall bounds are special cases of a more general bound that is satisfied for all bounce solutions with Minkowski or AdS false vacua. We discuss the limit where the parameters of the theory attain critical values and the bound is saturated. The bounce solution then disappears and a static planar domain wall solution appears in its stead. The scalar field potential then is of the form expected in supergravity, but this is only guaranteed along the trajectory in field space traced out by the bounce.
Prediction of surface tension of binary mixtures with the parachor method
Directory of Open Access Journals (Sweden)
Němec Tomáš
2015-01-01
Full Text Available The parachor method for the estimation of the surface tension of binary mixtures is modified by considering temperature-dependent values of the parachor parameters. The temperature dependence is calculated by a least-squares fit of pure-solvent surface tension data to the binary parachor equation utilizing the Peng-Robinson equation of state for the calculation of equilibrium densities. A very good agreement between experimental binary surface tension data and the predictions of the modified parachor method are found for the case of the mixtures of carbon dioxide and butane, benzene, and cyclohexane, respectively. The surface tension is also predicted for three refrigerant mixtures, i.e. propane, isobutane, and chlorodifluoromethane, with carbon dioxide.
Surface tension and related thermodynamic parameters of alcohols using the Traube stalagmometer
International Nuclear Information System (INIS)
Dilmohamud, B A; Seeneevassen, J; Rughooputh, S D D V; Ramasami, P
2005-01-01
An apparatus was devised using the Traube Stalagmometer for the determination of the surface tension of the alcohols methanol, ethanol, propan-1-ol and butan-1-ol. Measurements were made under atmospheric pressure at temperatures between 288.15 K and 313.15 K. The surface tension values were correlated with temperature and surface thermodynamic parameters, namely surface entropy and surface enthalpy, were also calculated. The results obtained are in agreement with the literature and they are promising for the use of this low cost arrangement for accurate measurement of surface tension. Surface tension values were obtained with a maximum error of 0.5 mN m -1 and a maximum standard deviation of 0.8 mN m -1 . We recommend this arrangement for students in advanced university courses and it can also be used for research work
Using the surface tension to estimate the condensate density of superfluid 4He
International Nuclear Information System (INIS)
Campbell, L.J.
1983-01-01
Distortion of the condensate wavefunction at the free surface of superfluid 4 He contributes to the surface tension in proportion to the condensate fraction n 0 (T). Using this to resolve the present discrepancy between the measured and predicted temperature dependencies of the surface tension gives n 0 (T) in good agreement with results from neutron and x-ray scattering measurements. This picture is also consistent with the measured 3 He- 4 He interfacial tension
Critical Assessment of the Surface Tension determined by the Maximum Pressure Bubble Method
Benedetto, Franco Emmanuel; Zolotucho, Hector; Prado, Miguel Oscar
2015-01-01
The main factors that influence the value of surface tension of a liquid measured with the Maximum Pressure Bubble Method are critically evaluated. We present experimental results showing the effect of capillary diameter, capillary depth, bubble spheroidicity and liquid density at room temperature. We show that the decrease of bubble spheroidicity due to increase of capillary immersion depth is not sufficient to explain the deviations found in the measured surface tension values. Thus, we pro...
Experiment and model for the surface tension of amine–ionic liquids aqueous solutions
International Nuclear Information System (INIS)
Zhang, Pan; Du, LeiXia; Fu, Dong
2014-01-01
Highlights: • The surface tensions of MEA/DEA–ionic liquids aqueous solutions were measured. • The experiments were modeled satisfactorily by using a thermodynamic equation. • The temperature dependence of the surface tension was illustrated. • The effects of the mass fractions of MEA/DEA and ionic liquids were demonstrated. - Abstract: The surface tension (γ) of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF 4 ])–monoethanolamine (MEA), 1-butyl-3-methylimidazolium bromide ([Bmim][Br])–MEA, [Bmim][BF 4 ]–diethanolamine (DEA) and [Bmim][Br]–DEA aqueous solutions was measured by using the BZY-1 surface tension meter. The temperature ranged from (293.2 to 323.2) K. The mass fraction of amines and ionic liquids (ILS) respectively ranged from 0.15 to 0.30 and 0.05 to 0.10. A thermodynamic equation was proposed to model the surface tension of amines–ILS aqueous solutions and the calculated results agreed well with the experiments. The effects of temperature, mass fraction of amines and ILS on the surface tension were demonstrated on the basis of experiments and calculations
Revised Mark 22 coolant temperature coefficients
International Nuclear Information System (INIS)
Graves, W.E.
1987-01-01
Coolant temperature coefficients for the Mark 22 charge published previously are non-conservative because of the neglect of a significant mechanism which has a positive contribution to reactivity. Even after correcting for this effect, dynamic tests made on a Mark VIB charge in the early 60's suggest the results are still non-conservative. This memorandum takes both of these sources of information into account in making a best estimate of the prompt (coolant plus metal) temperature coefficient. Although no safety issues arise from this work (the overall temperature coefficient still strongly contributes to reactor stability), it is obviously desirable to use best estimates for prompt coefficients in limits and other calculations
Czech Academy of Sciences Publication Activity Database
Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav
2012-01-01
Roč. 48, MAY 2012 (2012), s. 267-275 ISSN 0021-9614 R&D Projects: GA ČR GA101/09/0010 Institutional research plan: CEZ:AV0Z20760514 Keywords : ionic liquid s * tris(pentafluoroethyl)trifluorophosphate * surface tension * group contribution method * density Subject RIV: BJ - Thermodynamics Impact factor: 2.297, year: 2012 http://www.sciencedirect.com/science/article/pii/S0021961411004770
Czech Academy of Sciences Publication Activity Database
Klomfar, Jaroslav; Součková, Monika; Pátek, Jaroslav
2014-01-01
Roč. 59, July (2014), s. 2263-2274 ISSN 0021-9568 R&D Projects: GA ČR GA13-00145S; GA ČR GA101/09/0010 Institutional support: RVO:61388998 Keywords : trihexyl(tetradecyl)phosphonium cation * 1-hexyl-3-methylimidazolium hexafluorophosphate * bis(trifluoromethylsulfonyl)imide anion * dicyanamide anion * experimental pvT data * surface tension * internal pressure Subject RIV: BJ - Thermodynamics Impact factor: 2.037, year: 2014
International Nuclear Information System (INIS)
Rafati, Amir Abbas; Ghasemian, Ensieh
2009-01-01
Surface properties of binary mixtures of (n-alkyl acetates + heptane, benzene, and toluene) have been measured by surface tension method at T = 298.15 K and atmospheric pressure. Also, the surface tension has been predicted based on the Suarez method. This method combines a model for the description of surface tension of liquid mixtures with a group contribution method for the calculation of activity coefficient. The mean relative standard deviations obtained from the comparison of experimental (measured) and calculated surface tension values for the eight binary systems are less than 1.5%, which leads to concluding that the model shows a good accuracy in different situations in comparison with other predicted equations. In addition, the relative Gibbs adsorption and the surface mole fraction have been evaluated using this model. The surface tension deviations were calculated from experimental results and have been fitted to the Redlich-Kister type polynomial relation
DEFF Research Database (Denmark)
Gharagheizi, Farhad; Eslamimanesh, Ali; Sattari, Mehdi
2013-01-01
include critical temperature or temperature/critical volume/acentric factor/critical pressure/reduced temperature/reduced normal boiling point temperature/molecular weight of the compounds. Around 1,300 surface tension data of 118 random compounds are used for developing the first model (a four...
Moderator temperature coefficient in BWR core
International Nuclear Information System (INIS)
Naito, Yoshitaka
1977-01-01
Temperature dependences of infinite multiplication factor k sub(infinity) and neutron leakage from the core must be examined for estimation of moderator temperature coefficient. Temperature dependence on k sub(infinity) has been investigated by many researchers, however, the dependence on neutron leakage of a BWR with cruciformed control rods has hardly been done. Because there are difficulties and necessity on calculations of three space dimensional and multi-energy groups neutron distribution in a BWR core. In this study, moderator temperature coefficients of JPDR-II (BWR) core were obtained by calculation with DIFFUSION-ACE, which is newly developed three-dimensional multi-group computer code. The results were compared with experimental data measured from 20 to 275 0 C of the moderator temperature and the good agreement was obtained between calculation and measurement. In order to evaluate neutron leakage from the core, the other two calculations were carried out, adjusting criticality by uniform absorption rate and by material buckling. The former underestimated neutron leakage and the latter overestimated it. Discussion on the results shows that in order to estimate the temperature coefficient of BWR, neutron leakage must be evaluated precisely, therefore the calculation at actual pattern of control rods is necessary. (auth.)
International Nuclear Information System (INIS)
Ishikawa, Takehiko; Paradis, Paul-Francois; Yoda, Shinichi
2004-01-01
Surface tension and viscosity of liquid rhenium, which have hardly been measured due to the extremely high melting temperature of rhenium, were measured using an electrostatic levitation method combined with the oscillation drop technique. Sample position instability problems caused by the photon pressure of the heating lasers and by sample evaporation were solved by modifying the electrodes design. Good sample stability allowed the measurements of the surface tension and the viscosity over wide temperature ranges including the undercooled states. Over the 2800-3600 K interval, the surface tension of rhenium was measured as σ(T)=2.71x10 3 -0.23(T-T m ), where T m is the melting temperature, 3453 K. At T m , the datum agrees well with the literature values. Similarly, on the same temperature range, the viscosity was determined as η(T)=0.08 exp[1.33x10 5 /(RT)] (mPa s)
Liquid metal actuator driven by electrochemical manipulation of surface tension
Russell, Loren; Wissman, James; Majidi, Carmel
2017-12-01
We examine the electrocapillary properties of a fluidic actuator composed of a liquid metal droplet that is submerged in electrolytic solution and attached to an elastic beam. The beam deflection is controlled by electrochemically driven changes in the surface energy of the droplet. The metal is a eutectic gallium-indium alloy that is liquid at room temperature and forms an nm-thin Ga2O3 skin when oxidized. The effective surface tension of the droplet changes dramatically with oxidation and reduction, which are reversibly controlled by applying low voltage to the electrolytic bath. Wetting the droplet to two copper pads allows for a controllable tensile force to be developed between the opposing surfaces. We demonstrate the ability to reliably control force by changing the applied oxidizing voltage. Actuator forces and droplet geometries are also examined by performing a computational fluid mechanics simulation using Surface Evolver. The theoretical predictions are in qualitative agreement with the experimental measurements and provide additional confirmation that actuation is driven by surface tension.
Rehner, Philipp; Gross, Joachim
2018-04-01
The curvature dependence of interfacial properties has been discussed extensively over the last decades. After Tolman published his work on the effect of droplet size on surface tension, where he introduced the interfacial property now known as Tolman length, several studies were performed with varying results. In recent years, however, some consensus has been reached about the sign and magnitude of the Tolman length of simple model fluids. In this work, we re-examine Tolman's equation and how it relates the Tolman length to the surface tension and we apply non-local classical density functional theory (DFT) based on the perturbed chain statistical associating fluid theory (PC-SAFT) to characterize the curvature dependence of the surface tension of real fluids as well as mixtures. In order to obtain a simple expression for the surface tension, we use a first-order expansion of the Tolman length as a function of droplet radius Rs, as δ(Rs) = δ0 + δ1/Rs, and subsequently expand Tolman's integral equation for the surface tension, whereby a second-order expansion is found to give excellent agreement with the DFT result. The radius-dependence of the surface tension of increasingly non-spherical substances is studied for n-alkanes, up to icosane. The infinite diameter Tolman length is approximately δ0 = -0.38 Å at low temperatures. For more strongly non-spherical substances and for temperatures approaching the critical point, however, the infinite diameter Tolman lengths δ0 turn positive. For mixtures, even if they contain similar molecules, the extrapolated Tolman length behaves strongly non-ideal, implying a qualitative change of the curvature behavior of the surface tension of the mixture.
Design of an experimental apparatus for measurement of the surface tension of metastable fluids
Vinš, V.; Hrubý, J.; Hykl, J.; Blaha, J.; Šmíd, B.
2013-04-01
A unique experimental apparatus for measurement of the surface tension of aqueous mixtures has been designed, manufactured, and tested in our laboratory. The novelty of the setup is that it allows measurement of surface tension by two different methods: a modified capillary elevation method in a long vertical capillary tube and a method inspired by the approach of Hacker (National Advisory Committee for Aeronautics, Technical Note 2510, 1-20, 1951), i.e. in a short horizontal capillary tube. Functionality of all main components of the apparatus, e.g., glass chamber with the capillary tube, temperature control unit consisting of two thermostatic baths with special valves for rapid temperature jumps, helium distribution setup allowing pressure variation above the liquid meniscus inside the capillary tube, has been successfully tested. Preliminary results for the surface tension of the stable and metastable supercooled water measured by the capillary elevation method at atmospheric pressure are provided. The surface tension of water measured at temperatures between +26 °C and -11 °C is in good agreement with the extrapolated IAPWS correlation (IAPWS Release on Surface Tension of Ordinary Water Substance, September 1994); however it disagrees with data by Hacker.
Surface Tension of Multi-phase Flow with Multiple Junctions Governed by the Variational Principle
International Nuclear Information System (INIS)
Matsutani, Shigeki; Nakano, Kota; Shinjo, Katsuhiko
2011-01-01
We explore a computational model of an incompressible fluid with a multi-phase field in three-dimensional Euclidean space. By investigating an incompressible fluid with a two-phase field geometrically, we reformulate the expression of the surface tension for the two-phase field found by Lafaurie et al. (J Comput Phys 113:134–147, 1994) as a variational problem related to an infinite dimensional Lie group, the volume-preserving diffeomorphism. The variational principle to the action integral with the surface energy reproduces their Euler equation of the two-phase field with the surface tension. Since the surface energy of multiple interfaces even with singularities is not difficult to be evaluated in general and the variational formulation works for every action integral, the new formulation enables us to extend their expression to that of a multi-phase (N-phase, N ≥ 2) flow and to obtain a novel Euler equation with the surface tension of the multi-phase field. The obtained Euler equation governs the equation for motion of the multi-phase field with different surface tension coefficients without any difficulties for the singularities at multiple junctions. In other words, we unify the theory of multi-phase fields which express low dimensional interface geometry and the theory of the incompressible fluid dynamics on the infinite dimensional geometry as a variational problem. We apply the equation to the contact angle problems at triple junctions. We computed the fluid dynamics for a two-phase field with a wall numerically and show the numerical computational results that for given surface tension coefficients, the contact angles are generated by the surface tension as results of balances of the kinematic energy and the surface energy.
International Nuclear Information System (INIS)
Amore, S.; Brillo, J.; Egry, I.; Novakovic, R.
2011-01-01
The surface tension of liquid Cu-Ti alloys has been measured by using the containerless technique of electromagnetic levitation and theoretically calculated in the framework of the compound formation model. Measurements have been carried out on alloys covering the entire range of composition and over the temperature range 1275-2050 K. For all investigated alloys the surface tension can be described by a linear function of the temperature with negative slope. Due to the presence of different intermetallic compounds in the solid state the surface properties of liquid Cu-Ti alloys are satisfactory described by the compound formation model.
International Nuclear Information System (INIS)
Tsuji, Masashi; Aoki, Yukinori; Shimazu, Yoichiro; Yamasaki, Masatoshi; Hanayama, Yasushi
2006-01-01
A method to evaluate the moderator coefficient (MTC) and the Doppler coefficient through experimental procedures performed during reactor physics tests of PWR power plants is proposed. This method combines isothermal temperature coefficient (ITC) measurement experiments and reactor power transient experiments at low power conditions for dynamic identification. In the dynamic identification, either one of temperature coefficients can be determined in such a way that frequency response characteristics of the reactivity change observed by a digital reactivity meter is reproduced from measured data of neutron count rate and the average coolant temperature. The other unknown coefficient can also be determined by subtracting the coefficient obtained from the dynamic identification from ITC. As the proposed method can directly estimate the Doppler coefficient, the applicability of the conventional core design codes to predict the Doppler coefficient can be verified for new types of fuels such as mixed oxide fuels. The digital simulation study was carried out to show the feasibility of the proposed method. The numerical analysis showed that the MTC and the Doppler coefficient can be estimated accurately and even if there are uncertainties in the parameters of the reactor kinetics model, the accuracies of the estimated values are not seriously impaired. (author)
A thermodynamical model for the surface tension of silicate melts in contact with H2O gas
Colucci, Simone; Battaglia, Maurizio; Trigila, Raffaello
2016-01-01
Surface tension plays an important role in the nucleation of H2O gas bubbles in magmatic melts and in the time-dependent rheology of bubble-bearing magmas. Despite several experimental studies, a physics based model of the surface tension of magmatic melts in contact with H2O is lacking. This paper employs gradient theory to develop a thermodynamical model of equilibrium surface tension of silicate melts in contact with H2O gas at low to moderate pressures. In the last decades, this approach has been successfully applied in studies of industrial mixtures but never to magmatic systems. We calibrate and verify the model against literature experimental data, obtained by the pendant drop method, and by inverting bubble nucleation experiments using the Classical Nucleation Theory (CNT). Our model reproduces the systematic decrease in surface tension with increased H2O pressure observed in the experiments. On the other hand, the effect of temperature is confirmed by the experiments only at high pressure. At atmospheric pressure, the model shows a decrease of surface tension with temperature. This is in contrast with a number of experimental observations and could be related to microstructural effects that cannot be reproduced by our model. Finally, our analysis indicates that the surface tension measured inverting the CNT may be lower than the value measured by the pendant drop method, most likely because of changes in surface tension controlled by the supersaturation.
Superfluid 3He A-B surface tension
International Nuclear Information System (INIS)
Bartkowiak, M.; Haley, R.P.; Fisher, S.N.; Guenault, A.M.; Pickett, G.R.; Skyba, P.
2003-01-01
We have made two different measurements of interfacial energies below 300 μK, at zero pressure and in magnetic fields up to 400 mT. A variable magnetic field profile allows us to stabilize and precisely manipulate the position of the A-B interface. First, we can derive the difference in wall wetting energies from the behaviour of the phase boundary as it enters and exits a stack of glass capillary tubes. Secondly, we can measure the surface tension from the level of over- or under-magnetization needed to force the interface through an aperture. These are the first surface energy measurements in high magnetic fields in the zero-temperature limit. Our results are in surprising agreement with earlier measurements at high pressure close to T c
Surface tension in soap films: revisiting a classic demonstration
International Nuclear Information System (INIS)
Behroozi, F
2010-01-01
We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)
Surface tension in soap films: revisiting a classic demonstration
Energy Technology Data Exchange (ETDEWEB)
Behroozi, F [Department of Physics, University of Northern Iowa, Cedar Falls, IA 50614 (United States)], E-mail: behroozi@uni.edu
2010-01-15
We revisit a classic demonstration for surface tension in soap films and introduce a more striking variation of it. The demonstration shows how the film, pulling uniformly and normally on a loose string, transforms it into a circular arc under tension. The relationship between the surface tension and the string tension is analysed and presented in a useful graphical form. (letters and comments)
Density, viscosity and surface tension of liquid phase Beckmann rearrangement mixtures
Zuidhof, K.T.; Croon, de M.H.J.M.; Schouten, J.C.; Tinge, J.T.
2015-01-01
We have determined the density, dynamic viscosity, and surface tension of liquid phase Beckmann rearrangement mixtures, consisting of e-caprolactam and fuming oleum. These important properties have been measured in wide ranges of both temperature and molar ratios of acid and e-caprolactam, covering
Surface tension of heptane, decane, hexadecane, eicosane, and some of their binary mixtures
DEFF Research Database (Denmark)
Rolo, Lara I.; Caco, Ana I.; Queimada, Antonio
2002-01-01
Surface tension measurements were performed by the Wilhelmy plate method. Measured systems included pure heptane, decane, hexadecane, eicosane, and some of their binary mixtures at temperatures from 293.15 K to 343.15 K with an average absolute deviation of 1.6%. The results were compared with a ...
Annotated bibliography for liquid metal surface tensions of groups III-A, IV-A, and V-A metals
International Nuclear Information System (INIS)
Murtha, M.J.; Burnet, G.
1976-04-01
An annotated bibliography has been prepared which includes summaries of 82 publications dating from 1920 and dealing with the measurement of the surface tensions of Groups III-A, IV-A, and V-A metals in the liquid state. The bibliography is organized by key element investigated, and contains a tabulation of correlations for surface tension as a function of temperature. A brief discussion dealing with variables and methods has been included
Surface tension modelling of liquid Cd-Sn-Zn alloys
Fima, Przemyslaw; Novakovic, Rada
2018-06-01
The thermodynamic model in conjunction with Butler equation and the geometric models were used for the surface tension calculation of Cd-Sn-Zn liquid alloys. Good agreement was found between the experimental data for limiting binaries and model calculations performed with Butler model. In the case of ternary alloys, the surface tension variation with Cd content is better reproduced in the case of alloys lying on vertical sections defined by high Sn to Zn molar fraction ratio. The calculated surface tension is in relatively good agreement with the available experimental data. In addition, the surface segregation of liquid ternary Cd-Sn-Zn and constituent binaries has also been calculated.
In situ droplet surface tension and viscosity measurements in gas metal arc welding
International Nuclear Information System (INIS)
Bachmann, B; Siewert, E; Schein, J
2012-01-01
In this paper, we present an adaptation of a drop oscillation technique that enables in situ measurements of thermophysical properties of an industrial pulsed gas metal arc welding (GMAW) process. Surface tension, viscosity, density and temperature were derived expanding the portfolio of existing methods and previously published measurements of surface tension in pulsed GMAW. Natural oscillations of pure liquid iron droplets are recorded during the material transfer with a high-speed camera. Frame rates up to 30000 fps were utilized to visualize iron droplet oscillations which were in the low kHz range. Image processing algorithms were employed for edge contour extraction of the droplets and to derive parameters such as oscillation frequencies and damping rates along different dimensions of the droplet. Accurate surface tension measurements were achieved incorporating the effect of temperature on density. These are compared with a second method that has been developed to accurately determine the mass of droplets produced during the GMAW process which enables precise surface tension measurements with accuracies up to 1% and permits the study of thermophysical properties also for metals whose density highly depends on temperature. Thermophysical properties of pure liquid iron droplets formed by a wire with 1.2 mm diameter were investigated in a pulsed GMAW process with a base current of 100 A and a pulse current of 600 A. Surface tension and viscosity of a sample droplet were 1.83 ± 0.02 N m -1 and 2.9 ± 0.3 mPa s, respectively. The corresponding droplet temperature and density are 2040 ± 50 K and 6830 ± 50 kg m -3 , respectively. (paper)
Surface tension and related thermodynamic quantities of aqueous electrolyte solutions
Matubayasi, Norihiro
2013-01-01
Surface tension provides a thermodynamic avenue for analyzing systems in equilibrium and formulating phenomenological explanations for the behavior of constituent molecules in the surface region. While there are extensive experimental observations and established ideas regarding desorption of ions from the surfaces of aqueous salt solutions, a more successful discussion of the theory has recently emerged, which allows the quantitative calculation of the distribution of ions in the surface region. Surface Tension and Related Thermodynamic Quantities of Aqueous Electrolyte Solutions provides a d
Account for the surface tension in hydraulic modeling of the weir with a sharp threshold
Directory of Open Access Journals (Sweden)
Medzveliya Manana Levanovna
Full Text Available In the process of calculating and simulating water discharge in free channels it is necessary to know the flow features in case of small values of Reynolds and Weber numbers. The article considers the influence of viscosity and surface tension on the coefficient of a weir flow with sharp threshold. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure over a spillway threshold, threshold height over a course bottom, speed of liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, unit discharge, the width of the course. The surface tension and liquid density for the applied liquids changed a little. In the rectangular tray (6000x100x200 spillway with a sharp threshold was established. It is shown that weir flow coefficient depends on Reynolds number (in case Re < ~ 2000 and Webers number. A generalized expression for determining weir flow coefficient considering the influence of the forces of viscosity and surface tension is received.
Wetting and surface tension of bismate glass melt
International Nuclear Information System (INIS)
Shim, Seung-Bo; Kim, Dong-Sun; Hwang, Seongjin; Kim, Hyungsun
2009-01-01
Lead oxide glass frits are used widely in the electronics industry for low-temperature firing. On the other hand, one of the low-sintering and low-melting lead-free glass systems available, the bismate glass system, is considered to be an alternative to lead oxide glass. In order to extend the applications of Bi 2 O 3 glasses, this study examined the thermophysical properties of low-melting Bi 2 O 3 -B 2 O 3 -ZnO-BaO-Al 2 O 3 -SiO 2 glass frits with various ZnO/B 2 O 3 ratios. The fundamental thermal properties, such as glass transition temperature and softening point, were examined by differential thermal analysis and a glass softening point determination system. The wetting angles, viscosities and surface tension of the various bismate glasses on an alumina substrate were measured using hot-stage microscopy and the sessile drop method. These thermophysical properties will be helpful in understanding the work of adhesion and the liquid spread kinetics of glass frits.
Surface tension and density of liquid In-Sn-Zn alloys
Pstruś, Janusz
2013-01-01
Using the dilatometric method, measurements of the density of liquid alloys of the ternary system In-Sn-Zn in four sections with a constant ratio Sn:In = 24:1, 3:1, 1:1, 1:3, for various Zn additions (5, 10, 14, 20, 3 5, 50 and 75 at.% Zn) were performed at the temperature ranges of 500-1150 K. Density decreases linearly for all compositions. The molar volume calculated from density data exhibits close to ideal dependence on composition. Measurements of the surface tension of liquid alloys have been conducted using the method of maximum pressure in the gas bubbles. There were observed linear dependences on temperature with a negative gradients dσ/dT. Generally, with two exceptions, there was observed the increase of surface tension with increasing content of zinc. Using the Butler's model, the surface tension isotherms were calculated for temperatures T = 673 and 1073 K. Calculations show that only for high temperatures and for low content of zinc (up to about 35 at.%), the modeling is in very good agreement with experiment. Using the mentioned model, the composition of the surface phase was defined at two temperatures T = 673 and 973 K. Regardless of the temperature and of the defined section, the composition of the bulk is very different in comparison with the composition of the surface.
Effects of surface tension on tray point efficiencies
Energy Technology Data Exchange (ETDEWEB)
Chen, G.X.; Afacan, A.; Chuang, K.T. (Alberta Univ., Edmonton, AB (Canada))
1994-08-01
Sieve tray efficiencies for the distillation of methanol/water, acetic acid/water, and cyclohexane/n-heptane mixtures were measured as a function of composition under fixed vapor and liquid rates in a 0.15 m diameter distillation column. The three binary distillation systems used in the study had a wide range of surface tensions measured as a function of composition. From the efficiencies measured, the number of vapor- and liquid-phase transfer units (Ng and Nl) was determined and the effects of surface tension on Ng and Nl were identified. To further verify the results obtained from the distillation column, bubble sizes in froths for air/water, air/methanol, and air/(water + surfactant) systems with different surface tensions were measured. The results show that surface tension has a significant effect on tray efficiency and the number of transfer units. Bubble sizes in the tray froths were mainly determined by surface tension, and bubble breakup and coalescence occur in the froths. 45 refs., 15 figs., 1 tab.
A density gradient theory based method for surface tension calculations
DEFF Research Database (Denmark)
Liang, Xiaodong; Michelsen, Michael Locht; Kontogeorgis, Georgios
2016-01-01
The density gradient theory has been becoming a widely used framework for calculating surface tension, within which the same equation of state is used for the interface and bulk phases, because it is a theoretically sound, consistent and computationally affordable approach. Based on the observation...... that the optimal density path from the geometric mean density gradient theory passes the saddle point of the tangent plane distance to the bulk phases, we propose to estimate surface tension with an approximate density path profile that goes through this saddle point. The linear density gradient theory, which...... assumes linearly distributed densities between the two bulk phases, has also been investigated. Numerical problems do not occur with these density path profiles. These two approximation methods together with the full density gradient theory have been used to calculate the surface tension of various...
Modeling of surface tension effects in venturi scrubbing
Ott, Robert M.; Wu, Tatsu K. L.; Crowder, Jerry W.
A modified model of venturi scrubber performance has been developed that addresses two effects of liquid surface tension: its effect on droplet size and its effect on particle penetration into the droplet. The predictions of the model indicate that, in general, collection efficiency increases with a decrease in liquid surface tension, but the range over which this increase is significant depends on the particle size and on the scrubber operating parameters. The predictions further indicate that the increases in collection efficiency are almost totally due to the effect of liquid surface tension on the mean droplet size, and that the collection efficiency is not significantly affected by the ability of the particle to penetrate the droplet.
Surface tension in microsystems engineering below the capillary length
Lambert, Pierre
2014-01-01
This book describes how surface tension effects can be used by engineers to provide mechanical functions in miniaturized products (<1 mm). Even if precursors of this field such as Jurin or Laplace already date back to the 18th century, describing surface tension effects from a mechanical perspective is very recent. The originality of this book is to consider the effects of capillary bridges on solids, including forces and torques exerted both statically and dynamically by the liquid along the 6 degrees-of-freedom. It provides a comprehensive approach to various applications, such as capillary adhesion (axial force), centering force in packaging and micro-assembly (lateral force) and recent developments such as a capillary motor (torque). It devises how surface tension can be used to provide mechanical functions such as actuation (bubble-actuated compliant table), sealing and tightness, energy harvesting, nanodispending.
The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids
Hu, Bin; Kieweg, Sarah L.
2012-01-01
Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability. PMID:23687391
Surface tension alteration on calcite, induced by ion substitution
DEFF Research Database (Denmark)
Sakuma, Hiroshi; Andersson, Martin Peter; Bechgaard, Klaus
2014-01-01
The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale...... preferentially as ion pairs at solution-calcite interfaces. Mg2+ incorporation weakens organic molecule adhesion while strengthening water adsorption so Mg2+ substitution renders calcite more water wet. When Mg2+ replaces 10% of surface Ca2+, the contact angle changes dramatically, by 40 to 70, converting...
Surface tension mediated conversion of light to work
Okawa, David; Pastine, Stefan J; Zettl, Alexander K; Frechet, Jean M. J
2014-12-02
Disclosed are a method and apparatus for converting light energy to mechanical energy by modification of surface tension on a supporting fluid. The apparatus comprises an object which may be formed as a composite object comprising a support matrix and a highly light absorptive material. The support matrix may comprise a silicon polymer. The highly light absorptive material may comprise vertically aligned carbon nanotubes (VANTs) embedded in the support matrix. The composite object is supported on a fluid. By exposing the highly light absorptive material to light, heat is generated, which changes the surface tension of the composite object, causing it to move physically within the fluid.
Chen, Ming-Wen; Li, Lin-Yan; Guo, Hui-Min
2017-08-28
The dynamics of nucleation and growth of a particle affected by anisotropic surface tension in the ternary alloy melt is studied. The uniformly valid asymptotic solution for temperature field, concentration field, and interface evolution of nucleation and particle growth is obtained by means of the multiple variable expansion method. The asymptotic solution reveals the critical radius of nucleation in the ternary alloy melt and an inward melting mechanism of the particle induced by the anisotropic effect of surface tension. The critical radius of nucleation is dependent on isotropic surface tension, temperature undercooling, and constitutional undercooling in the ternary alloy melt, and the solute diffusion melt decreases the critical radius of nucleation. Immediately after a nucleus forms in the initial stage of solidification, the anisotropic effect of surface tension makes some parts of its interface grow inward while some parts grow outward. Until the inward melting attains a certain distance (which is defined as "the melting depth"), these parts of interface start to grow outward with other parts. The interface of the particle evolves into an ear-like deformation, whose inner diameter may be less than two times the critical radius of nucleation within a short time in the initial stage of solidification. The solute diffusion in the ternary alloy melt decreases the effect of anisotropic surface tension on the interface deformation.
A finite-volume HLLC-based scheme for compressible interfacial flows with surface tension
Energy Technology Data Exchange (ETDEWEB)
Garrick, Daniel P. [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States); Owkes, Mark [Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, MT (United States); Regele, Jonathan D., E-mail: jregele@iastate.edu [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States)
2017-06-15
Shock waves are often used in experiments to create a shear flow across liquid droplets to study secondary atomization. Similar behavior occurs inside of supersonic combustors (scramjets) under startup conditions, but it is challenging to study these conditions experimentally. In order to investigate this phenomenon further, a numerical approach is developed to simulate compressible multiphase flows under the effects of surface tension forces. The flow field is solved via the compressible multicomponent Euler equations (i.e., the five equation model) discretized with the finite volume method on a uniform Cartesian grid. The solver utilizes a total variation diminishing (TVD) third-order Runge–Kutta method for time-marching and second order TVD spatial reconstruction. Surface tension is incorporated using the Continuum Surface Force (CSF) model. Fluxes are upwinded with a modified Harten–Lax–van Leer Contact (HLLC) approximate Riemann solver. An interface compression scheme is employed to counter numerical diffusion of the interface. The present work includes modifications to both the HLLC solver and the interface compression scheme to account for capillary force terms and the associated pressure jump across the gas–liquid interface. A simple method for numerically computing the interface curvature is developed and an acoustic scaling of the surface tension coefficient is proposed for the non-dimensionalization of the model. The model captures the surface tension induced pressure jump exactly if the exact curvature is known and is further verified with an oscillating elliptical droplet and Mach 1.47 and 3 shock-droplet interaction problems. The general characteristics of secondary atomization at a range of Weber numbers are also captured in a series of simulations.
Density and surface tension of melts of zirconium and hafnium fluorides with lithium fluoride
International Nuclear Information System (INIS)
Katyshev, S.F.; Artemov, V.V.; Desyatnik, V.N.
1988-01-01
A study was conducted to determine the temperature dependence of the density and surface tension of melts of LiF-ZrF 4 and LiF-HfF 4 . Density and surface tension were determined by the method of maximum pressure in an argon bubble. On the basis of experimental data over the entire concentration range the molar volumes and their relative deviations from the additive molar volumes were calculated for 1100 0 K. The positive deviations of the molar volumes from additivity in the LiF-HfF 4 system (22.45%) were greater than in the LiF-ZrF 4 system (15.75%). This indicated that the reaction with lithium fluoride is intensified with the switch to the hafnium fluoride. Results also demonstrated that the fluorides are surface-active components in the molten mixtures
The Role of Surface Tension in the Crystallization of Metal Halide Perovskites
Zhumekenov, Ayan A.
2017-07-06
The exciting intrinsic properties discovered in single crystals of metal halide perovskites still await their translation into optoelectronic devices. The poor understanding and control of the crystallization process of these materials are current bottlenecks retarding the shift towards single crystal-based optoelectronics. Here we theoretically and experimentally elucidate the role of surface tension in the rapid synthesis of perovskite single crystals by inverse temperature crystallization (ITC). Understanding the nucleation and growth mechanisms enabled us to exploit surface tension to direct the growth of monocrystalline films of perovskites (AMX3, where A = CH3NH3+ or MA; M = Pb2+, Sn2+; X = Br-, I-) on the solution surface. We achieve up to 1 cm2-sized monocrystalline films with thickness on the order of the charge carrier diffusion length (~5-10 µm). Our work paves the way to control the crystallization process of perovskites, including thin film deposition, which is essential to advance the performance benchmarks of perovskite optoelectronics.
Surface tension of compositions of polyhexametyleneguanidine hydrochloride - surfactants
Directory of Open Access Journals (Sweden)
S. Kumargaliyeva
2012-12-01
Full Text Available We made up songs bactericidal polyhexamethyleneguanidine hydrochloride (metacyde with the surface-active substances - anionic sodium dodecylsulfate, cationic cetylpyridinium bromide, and nonionic Tween-80 and measured the surface tension of water solutions. The study showed that the composition metacyde with surface-active agents have a greater surface activity than the individual components.
Nanofluidic bubble pump using surface tension directed gas injection
Tas, Niels Roelof; Berenschot, Johan W.; Lammerink, Theodorus S.J.; Elwenspoek, Michael Curt; van den Berg, Albert
2002-01-01
A new concept for liquid manipulation has been developed and implemented in surface-micromachined fluid channels. It is based on the surface tension directed injection of a gas into the liquid flow through micrometer-sized holes in the microchannel wall. The injected gas is directed to an exhaust by
Measuring device for the temperature coefficient of reactor moderators
International Nuclear Information System (INIS)
Nakano, Yuzo.
1987-01-01
Purpose: To rapidly determine by automatic calculation the temperature coefficient for moderators which has been determined so far by a log of manual processings. Constitution: Each of signals from a control rod position indicator, a reactor reactivity, instrument and moderator temperature meter are inputted, and each of the signals and designed valued for the doppler temperature coefficients are stored. Recurling calculation is conducted based on the reactivity and the moderator temperature at an interval where the temperature changes of the moderators are equalized at an identical control rod position, to determine isothermic coefficient. Then, the temperature coefficient for moderator are calculated from the isothermic coefficient and the doppler temperature coefficient. The relationship between the reactivity and the moderator temperature is plotted on a X-Y recorder. The stored signals and the calculated temperature coefficient for moderators are sequentially displayed and the results are printed out when the measurement is completed. According to the present device, since the real time processing is conducted, the processing time can be shortened remarkably. Accordingly, it is possible to save the man power for the test of the nuclear reactor and improve the reactor operation performance. (Kamimura, M.)
Modelling of tandem cell temperature coefficients
Energy Technology Data Exchange (ETDEWEB)
Friedman, D.J. [National Renewable Energy Lab., Golden, CO (United States)
1996-05-01
This paper discusses the temperature dependence of the basic solar-cell operating parameters for a GaInP/GaAs series-connected two-terminal tandem cell. The effects of series resistance and of different incident solar spectra are also discussed.
Contact angle and surface tension measurements of a five-ring polyphenyl ether
Jones, W. R., Jr.
1986-01-01
Contact angle measurements were performed for a five-ring polyphenyl ether isomeric mixture on M-50 steel in a dry nitrogen atmosphere. Two different techniques were used: (1) a tilting plate apparatus, and (2) a sessile drop apparatus. Measurements were made for the temperature range 25 to 190 C. Surface tension was measured by a differential maximum bubble pressure technique over the range 23 to 220 C in room air. The critical surface energy of spreading (gamma /sub c/) was determined for the polyphenyl ether by plotting the cosine of the contact angle (theta) versus the surface tension (gamma /sub LV/). The straight line intercept at cosine theta = 1 is defined as gamma (sub c). Gamma (sub c) was found to be 30.1 dyn/cm for the tilting plate technique and 31.3 dyn/cm for the sessile drop technique. These results indicate that the polyphenyl ether is inherently autophobic (i.e., it will not spread on its own surface film until its surface tension is less than gamma /sub c/). This phenomenon is discussed in light of the wettability and wear problems encountered with this fluid.
Improvement of gas entrainment prediction method. Introduction of surface tension effect
International Nuclear Information System (INIS)
Ito, Kei; Sakai, Takaaki; Ohshima, Hiroyuki; Uchibori, Akihiro; Eguchi, Yuzuru; Monji, Hideaki; Xu, Yongze
2010-01-01
A gas entrainment (GE) prediction method has been developed to establish design criteria for the large-scale sodium-cooled fast reactor (JSFR) systems. The prototype of the GE prediction method was already confirmed to give reasonable gas core lengths by simple calculation procedures. However, for simplification, the surface tension effects were neglected. In this paper, the evaluation accuracy of gas core lengths is improved by introducing the surface tension effects into the prototype GE prediction method. First, the mechanical balance between gravitational, centrifugal, and surface tension forces is considered. Then, the shape of a gas core tip is approximated by a quadratic function. Finally, using the approximated gas core shape, the authors determine the gas core length satisfying the mechanical balance. This improved GE prediction method is validated by analyzing the gas core lengths observed in simple experiments. Results show that the analytical gas core lengths calculated by the improved GE prediction method become shorter in comparison to the prototype GE prediction method, and are in good agreement with the experimental data. In addition, the experimental data under different temperature and surfactant concentration conditions are reproduced by the improved GE prediction method. (author)
Amide temperature coefficients in the protein G B1 domain
International Nuclear Information System (INIS)
Tomlinson, Jennifer H.; Williamson, Mike P.
2012-01-01
Temperature coefficients have been measured for backbone amide 1 H and 15 N nuclei in the B1 domain of protein G (GB1), using temperatures in the range 283–313 K, and pH values from 2.0 to 9.0. Many nuclei display pH-dependent coefficients, which were fitted to one or two pK a values. 1 H coefficients showed the expected behaviour, in that hydrogen-bonded amides have less negative values, but for those amides involved in strong hydrogen bonds in regular secondary structure there is a negative correlation between strength of hydrogen bond and size of temperature coefficient. The best correlation to temperature coefficient is with secondary shift, indicative of a very approximately uniform thermal expansion. The largest pH-dependent changes in coefficient are for amides in loops adjacent to sidechain hydrogen bonds rather than the amides involved directly in hydrogen bonds, indicating that the biggest determinant of the temperature coefficient is temperature-dependent loss of structure, not hydrogen bonding. Amide 15 N coefficients have no clear relationship with structure.
Isothermal temperature reactivity coefficient measurement in TRIGA reactor
International Nuclear Information System (INIS)
Zagar, T.; Ravnik, M.; Trkov, A.
2002-01-01
Direct measurement of an isothermal temperature reactivity coefficient at room temperatures in TRIGA Mark II research reactor at Jozef Stefan Institute in Ljubljana is presented. Temperature reactivity coefficient was measured in the temperature range between 15 o C and 25 o C. All reactivity measurements were performed at almost zero reactor power to reduce or completely eliminate nuclear heating. Slow and steady temperature decrease was controlled using the reactor tank cooling system. In this way the temperatures of fuel, of moderator and of coolant were kept in equilibrium throughout the measurements. It was found out that TRIGA reactor core loaded with standard fuel elements with stainless steel cladding has small positive isothermal temperature reactivity coefficient in this temperature range.(author)
A micro surface tension pump (MISPU) in a glass microchip.
Peng, Xing Yue Larry
2011-01-07
A non-membrane micro surface tension pump (MISPU) was fabricated on a glass microchip by one-step glass etching. It needs no material other than glass and is driven by digital gas pressure. The MISPU can be seen working like a piston pump inside the glass microchip under a microscope. The design of the valves (MISVA) and pistons (MISTON) was based on the surface tension theory of the micro surface tension alveolus (MISTA). The digital gas pressure controls the moving gas-liquid interface to open or close the input and output MISVAs to refill or drive the MISTON for pumping a liquid. Without any moving parts, a MISPU is a kind of long-lasting micro pump for micro chips that does not lose its water pumping efficiency over a 20-day period. The volumetric pump output varied from 0 to 10 nl s(-1) when the pump cycle time decreased from 5 min to 15 s. The pump head pressure was 1 kPa.
Measurement and analysis of reactivity temperature coefficient of CEFR
International Nuclear Information System (INIS)
Chen Yiyu; Hu Yun; Yang Xiaoyan; Fan Zhendong; Zhang Qiang; Zhao Jinkun; Li Zehua
2013-01-01
The reactivity temperature coefficient of CEFR was calculated by CITATION program and compared with the results calculated by correlative programs and measured from experiments for temperature effects. It is indicated that the calculation results from CITATION agree well with measured values. The reactivity temperature coefficient of CEFR is about -4 pcm/℃. The deviation of the measured values between the temperature increasing and decreasing processes is about 11%, which satisfies the experiment acceptance criteria. The measured results can validate the calculation ones by program and can provide important reference data for the safety operation of CEFR and the analysis of the reactivity balance in the reactor refueling situation. (authors)
Effect of potential attraction term on surface tension of ionic liquids
Vaziri, N.; Khordad, R.; Rezaei, G.
2018-03-01
In this work, we have studied the effect of attraction term of molecular potential on surface tension of ionic liquids (ILs). For this purpose, we have introduced two different potential models to obtain analytical expressions for the surface tension of ILs. The introduced potential models have different attraction terms. The obtained surface tensions in this work have been compared with other theoretical methods and also experimental data. Using the calculated surface tension, the sound velocity is also estimated. We have studied the structural effects on the surface tensions of imidazolium-based ionic liquids. It is found that the cation alkyl chain length and the anion size play important roles to the surface tension of the selected ionic liquids. The calculated surface tensions show a good harmony with experimental data. It is clear that the attraction term of molecular potential has an important role on surface tension and sound velocity of our system.
Amide proton temperature coefficients as hydrogen bond indicators in proteins
International Nuclear Information System (INIS)
Cierpicki, Tomasz; Otlewski, Jacek
2001-01-01
Correlations between amide proton temperature coefficients (Δσ HN /ΔT) and hydrogen bonds were investigated for a data set of 793 amides derived from 14 proteins. For amide protons showing temperature gradients more positive than -4.6 ppb/K there is a hydrogen bond predictivity value exceeding 85%. It increases to over 93% for amides within the range between -4 and -1 ppb/K. Detailed analysis shows an inverse proportionality between amide proton temperature coefficients and hydrogen bond lengths. Furthermore, for hydrogen bonds of similar bond lengths, values of temperature gradients in α-helices are on average 1 ppb/K more negative than in β-sheets. In consequence, a number of amide protons in α-helices involved in hydrogen bonds shorter than 2 A show Δσ HN /ΔT 10 helices and 98% in β-turns have temperature coefficients more positive than -4.6ppb/K. Ring current effect also significantly influences temperature coefficients of amide protons. In seven out of eight cases non-hydrogen bonded amides strongly deshielded by neighboring aromatic rings show temperature coefficients more positive than -2 ppb/K. In general, amide proton temperature gradients do not change with pH unless they correspond to conformational changes. Three examples of pH dependent equilibrium showing hydrogen bond formation at higher pH were found. In conclusion, amide proton temperature coefficients offer an attractive and simple way to confirm existence of hydrogen bonds in NMR determined structures
Short-Time Structural Stability of Compressible Vortex Sheets with Surface Tension
Stevens, Ben
2016-11-01
Assume we start with an initial vortex-sheet configuration which consists of two inviscid fluids with density bounded below flowing smoothly past each other, where a strictly positive fixed coefficient of surface tension produces a surface tension force across the common interface, balanced by the pressure jump. We model the fluids by the compressible Euler equations in three space dimensions with a very general equation of state relating the pressure, entropy and density such that the sound speed is positive. We prove that, for a short time, there exists a unique solution of the equations with the same structure. The mathematical approach consists of introducing a carefully chosen artificial viscosity-type regularisation which allows one to linearise the system so as to obtain a collection of transport equations for the entropy, pressure and curl together with a parabolic-type equation for the velocity which becomes fairly standard after rotating the velocity according to the interface normal. We prove a high order energy estimate for the non-linear equations that is independent of the artificial viscosity parameter which allows us to send it to zero. This approach loosely follows that introduced by Shkoller et al. in the setting of a compressible liquid-vacuum interface. Although already considered by Coutand et al. [10] and Lindblad [17], we also make some brief comments on the case of a compressible liquid-vacuum interface, which is obtained from the vortex sheets problem by replacing one of the fluids by vacuum, where it is possible to obtain a structural stability result even without surface tension.
Santos, Cherry S; Baldelli, Steven
2009-01-29
The gas-liquid interface of halide-free 1,3-dialkylimidazolium alkyl sulfates [RMIM][R-OSO(3)] with R chain length from C(1)-C(4) and C(8) has been studied systematically using the surface-specific sum frequency generation (SFG) vibrational spectroscopy and surface tension measurements. From the SFG spectra, vibrational modes from the methyl group of both cation and anion are observed for all ionic liquid samples considered in the present study. These results suggest the presence of both ions at the gas-liquid interface, which is further supported by surface tension measurements. Surface tension data show a decreasing trend as the alkyl chain in the imidazolium cation is varied from methyl to butyl chain, with a specific anion. A similar trend is observed when the alkyl chain of the anion is modified and the cation is fixed.
Study of Temperature Coefficients for Parameters of Photovoltaic Cells
Directory of Open Access Journals (Sweden)
Daniel Tudor Cotfas
2018-01-01
Full Text Available The temperature is one of the most important factors which affect the performance of the photovoltaic cells and panels along with the irradiance. The current voltage characteristics, I-V, are measured at different temperatures from 25°C to 87°C and at different illumination levels from 400 to 1000 W/m2, because there are locations where the upper limit of the photovoltaic cells working temperature exceeds 80°C. This study reports the influence of the temperature and the irradiance on the important parameters of four commercial photovoltaic cell types: monocrystalline silicon—mSi, polycrystalline silicon—pSi, amorphous silicon—aSi, and multijunction InGaP/InGaAs/Ge (Emcore. The absolute and normalized temperature coefficients are determined and compared with their values from the related literature. The variation of the absolute temperature coefficient function of the irradiance and its significance to accurately determine the important parameters of the photovoltaic cells are also presented. The analysis is made on different types of photovoltaics cells in order to understand the effects of technology on temperature coefficients. The comparison between the open-circuit voltage and short-circuit current was also performed, calculated using the temperature coefficients, determined, and measured, in various conditions. The measurements are realized using the SolarLab system, and the photovoltaic cell parameters are determined and compared using the LabVIEW software created for SolarLab system.
The HD+ dissociative recombination rate coefficient at low temperature
Directory of Open Access Journals (Sweden)
Wolf A.
2015-01-01
Full Text Available The effect of the rotational temperature of the ions is considered for low-energy dissociative recombination (DR of HD+. Merged beams measurements with HD+ ions of a rotational temperature near 300 K are compared to multichannel quantum defect theory calculations. The thermal DR rate coefficient for a Maxwellian electron velocity distribution is derived from the merged-beams data and compared to theoretical results for a range of rotational temperatures. Good agreement is found for the theory with 300 K rotational temperature. For a low-temperature plasma environment where also the rotational temperature assumes 10 K, theory predicts a considerably higher thermal DR rate coefficient. The origin of this is traced to predicted resonant structures of the collision-energy dependent DR cross section at few-meV collision energies for the particular case of HD+ ions in the rotational ground state.
Surface tension propulsion of fungal spores by use of microdroplets
Noblin, Xavier; Yang, Sylvia; Dumais, Jacques
2010-01-01
Many edible mushrooms eject their spores (about 10 microns in size) at high speed (about 1 m/s) using surface tension forces in a few microseconds. Basically the coalescence of a droplet with the spore generates the necessary momentum to eject the spore. We have detailed this mechanism in \\cite{noblin2}. In this article, we give some details about the high speed movies (up to 250000 fps) of mushrooms' spores ejection attached to this submission. This video was submitted as part of the Gallery...
Static pressure and temperature coefficients of laboratory standard microphones
DEFF Research Database (Denmark)
Rasmussen, Knud
1996-01-01
of the microphone. The static pressure and temperature coefficients were determined experimentally for about twenty samples of type BK 4160 and BK 4180 microphones. The results agree almost perfectly with the predictions for BK 4160, while some modifications of the lumped parameter values are called for to make......-order approximation of resonances in the back cavity. It was found that each of the coefficients, for a given type of microphone, can be expressed by a single function when the coefficients are normalized by their low-frequency value and the frequency axis normalized by the individual resonance frequency...
International Nuclear Information System (INIS)
Ghasemian, Ensieh; Najafi, Mojgan; Rafati, Amir Abbas; Felegari, Zahra
2010-01-01
Surface and bulk properties of 1-hexyl-3-methylimidazolium chloride [C 6 mim][Cl] as an ionic liquid (IL) have been investigated by surface tension and electrical conductivity techniques at various temperatures. Results reveal that the ionic liquid behaves as surfactant-like and aggregates in aqueous solution. Critical aggregation concentration (cac) values obtained by conductivity and surface tension measurements are in good agreement with values found in the literature. A series of important and useful adsorption parameters including cac, surface excess concentration (Γ), and minimum surface area per molecule (A min ) at the air + water interface were estimated from surface tension in the presence and absence of different electrolytes. Obtained data show that the surface tension as well as the cac of [C 6 mim][Cl] is reduced by electrolytes. Also, values of surface excess concentration (Γ) show that the IL ions in the presence of electrolyte have much larger affinity to adsorption at the surface and this affinity increased in aqueous electrolyte solution in the order of I - > Br - > Cl - for counter ion of salts that was explained in terms of a larger repulsion of chloride anions from interface to the bromide and iodide anion as well as difference in their excess polarizability.
International Nuclear Information System (INIS)
Mjalli, Farouq S.; Vakili-Nezhaad, Gholamreza; Shahbaz, Kaveh; AlNashef, Inas M.
2014-01-01
Highlights: • Critical temperatures of eight common DES were calculated using two methods. • Density and surface tension were calculated using the Rackett and Guggenheim equations. • The Rackett method should be used in the low temperature range only. • The Eötvos and Guggenheim methods gave best density and surface tension predictions. - Abstract: The recent continuing interest in deep eutectic solvents (DES) as ionic liquids analogues and their successful applications in different areas of separation necessities the existence of reliable physical and thermodynamic properties database. The scarcity of data on the physical properties of such solvents, increases the need for their prediction using reliable methods. In this study, first the critical temperatures of eight DES systems have been calculated based on the Eötvos empirical equation using the experimental data of the density and surface tension at various temperatures, then the density and surface tension values of these systems were predicted from the calculated critical temperatures. For the density prediction the Eötvos and Guggenheim equations were combined to introduce a simple power law equation using the estimated critical temperatures from the Eötvos and the Modified Lydersen–Joback–Reid group contribution methods. Finally, the estimated critical temperatures by these two methods were used in the Guggenheim empirical equation to calculate the surface tension of the DES systems. The prediction quality of the two physical properties under investigation were compared and proper recommendations were postulated
Energy Technology Data Exchange (ETDEWEB)
Mjalli, Farouq S., E-mail: farouqsm@yahoo.com [Petroleum and Chemical Engineering Department, Sultan Qaboos University, 123 Sultanate of Oman (Oman); Vakili-Nezhaad, Gholamreza; Shahbaz, Kaveh [School of Engineering, Taylor' s University, 47500 Selangor (Malaysia); AlNashef, Inas M. [Chemical Engineering Department, King Saud University, Riyadh 11421 (Saudi Arabia)
2014-01-10
Highlights: • Critical temperatures of eight common DES were calculated using two methods. • Density and surface tension were calculated using the Rackett and Guggenheim equations. • The Rackett method should be used in the low temperature range only. • The Eötvos and Guggenheim methods gave best density and surface tension predictions. - Abstract: The recent continuing interest in deep eutectic solvents (DES) as ionic liquids analogues and their successful applications in different areas of separation necessities the existence of reliable physical and thermodynamic properties database. The scarcity of data on the physical properties of such solvents, increases the need for their prediction using reliable methods. In this study, first the critical temperatures of eight DES systems have been calculated based on the Eötvos empirical equation using the experimental data of the density and surface tension at various temperatures, then the density and surface tension values of these systems were predicted from the calculated critical temperatures. For the density prediction the Eötvos and Guggenheim equations were combined to introduce a simple power law equation using the estimated critical temperatures from the Eötvos and the Modified Lydersen–Joback–Reid group contribution methods. Finally, the estimated critical temperatures by these two methods were used in the Guggenheim empirical equation to calculate the surface tension of the DES systems. The prediction quality of the two physical properties under investigation were compared and proper recommendations were postulated.
Distribution of temperature coefficient density for muons in the atmosphere
Directory of Open Access Journals (Sweden)
Kuzmenko V.S.
2017-12-01
Full Text Available To date, several dozens of new muon detectors have been built. When studying cosmic-ray intensity variations with these detectors, located deep in the atmosphere, it is necessary to calculate all characteristics, including the distribution of temperature coefficient density for muons in the atmosphere, taking into account their specific geometry. For this purpose, we calculate the density of temperature coefficients of muon intensity in the atmosphere at various zenith angles of detection at sea level and at various depths underground for different absorption ranges of primary protons and pions in the atmosphere.
Dynamic Bubble Surface Tension Measurements in Northwest Atlantic Seawater
Kieber, D. J.; Long, M. S.; Keene, W. C.; Kinsey, J. D.; Frossard, A. A.; Beaupre, S. R.; Duplessis, P.; Maben, J. R.; Lu, X.; Chang, R.; Zhu, Y.; Bisgrove, J.
2017-12-01
Numerous reports suggest that most organic matter (OM) associated with newly formed primary marine aerosol (PMA) originates from the sea-surface microlayer. However, surface-active OM rapidly adsorbs onto bubble surfaces in the water column and is ejected into the atmosphere when bubbles burst at the air-water interface. Here we present dynamic surface tension measurements of bubbles produced in near surface seawater from biologically productive and oligotrophic sites and in deep seawater collected from 2500 m in the northwest Atlantic. In all cases, the surface tension of bubble surfaces decreased within seconds after the bubbles were exposed to seawater. These observations demonstrate that bubble surfaces are rapidly saturated by surfactant material scavenged from seawater. Spatial and diel variability in bubble surface evolution indicate corresponding variability in surfactant concentrations and/or composition. Our results reveal that surface-active OM is found throughout the water column, and that at least some surfactants are not of recent biological origin. Our results also support the hypothesis that the surface microlayer is a minor to negligible source of OM associated with freshly produced PMA.
Temperature coefficients in the Dragon low-enriched power reactor
Energy Technology Data Exchange (ETDEWEB)
Hansen, U
1972-05-15
The temperature coefficient of the fuel and of the moderator have been evaluated for the Dragon HTR design for different stages in reactor life, initial core, end of no-refuelling period and equilibrium conditions. The investigation has shown the low-enriched HTR to have a strong, positive moderator coefficient. In some cases and for special operating conditions, even leading to a positive total temperature coefficient. This does not imply, however, that the HTR is an unsafe reactor system. By adequate design of the control system, safe and reliable operating characteristics can be achieved. This has already been proved satisfactory through many years of operation of other graphite moderated systems, such as the Magnox stations.
International Nuclear Information System (INIS)
Oliveira, M.B.; Domínguez-Pérez, M.; Cabeza, O.; Lopes-da-Silva, J.A.; Freire, M.G.; Coutinho, J.A.P.
2013-01-01
Highlights: • Novel data for the surface tensions of mixtures [C 4 mim][NTf 2 ] + [C 4 C 1 mim]/[C 3 mpy]/[C 3 mpyr]/[C 3 mpip][NTf 2 ] are presented. • γ were determined at a fixed temperature, 298.2 K, and at atmospheric pressure, for the whole composition range. • Surface tension deviations showed the near ideal behavior of the selected mixtures. • Gibbs adsorption isotherms showed the surface preferential adsorption of one ionic liquid over the other. -- Abstract: While values for thermophysical properties of ionic liquids are becoming widely available, data for ionic liquid mixtures are still scarce. In an effort to overcome this limitation and understand the behavior of ionic liquid mixtures, novel data for the surface tension of mixtures composed of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C 4 mim][NTf 2 ], with other ionic liquids with a common anion, namely 1-butyl-2,3-dimethylimidazolium, [C 4 C 1 mim] + , 3-methyl-1-propylpyridinium, [C 3 mpy] + , 1-methyl-1-propylpyrrolidinium, [C 3 mpyr] + , and 1-methyl-1-propylpiperidinium, [C 3 mpip] + , were measured at T = 298.2 K and atmospheric pressure over the entire composition range. From the surface tension deviations derived from the experimental results, it was possible to infer that the cation alkyl chain length of the second ionic liquid constituting the mixture has a stronger influence in the ideal mixture behavior than the type of family the ionic liquid cation belongs to. The Gibbs adsorption isotherms, estimated from the experimental values, show that the composition of the vapor–liquid interface is not the same as that of the bulk and that the interface is richer in the ionic liquid with the lowest surface tension, [C 4 mim][NTf 2
Temperature coefficients of reactivity in the fourth loading of ZENITH
International Nuclear Information System (INIS)
Caro Manso, R.; Freemantle, R.G.; Rogers, J.D.
1962-10-01
Measurements have been made of the temperature coefficients of reactivity associated with the core plus end reflectors and the side reflector of the fourth core loading of ZENITH, which had a carbon/U235 atomic ratio of 7788 and no other absorber. (author)
Temperature coefficients of reactivity in the fourth loading of ZENITH
Energy Technology Data Exchange (ETDEWEB)
Caro Manso, R; Freemantle, R G; Rogers, J D [Graphite Reactor Physics Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)
1962-10-15
Measurements have been made of the temperature coefficients of reactivity associated with the core plus end reflectors and the side reflector of the fourth core loading of ZENITH, which had a carbon/U235 atomic ratio of 7788 and no other absorber. (author)
Influence of Zinc on the Surface Tension, Density and Molar Volume of (Ag-Sneut +Zn Liquid Alloys
Directory of Open Access Journals (Sweden)
Gąsior W.
2016-03-01
Full Text Available The dilatometric and maximum bubble pressure methods were applied for the measurements of the density and surface tension of liquid (Ag-Sneut +Zn lead-free solders. The experiments were carried out in the temperature range from 515 to 1223 K for the alloys of the zinc concentration equaling 0.01, 0.02, 0.04, 0.05, 0.1 and 0.2 of the mole fraction. It was found that the temperature dependence of both the density and the surface tension could be thought as linear, so they were interpreted by straight line equations. The experimental data of the molar volume of the investigated alloys were described by the polynomial dependent on the composition and temperature.
Energy Technology Data Exchange (ETDEWEB)
Melchior, Tobias
2011-10-26
In the context of CO{sub 2}-emission-induced global warming, greenhouse gases resulting from the production of electricity in coal-fired power plants gain increasing attention. One possible way to reduce such emissions is to gasify coal instead of burning it. The corresponding process is referred to as Integrated Gasification Combined Cycle and allows for the separation of CO{sub 2} before converting a synthesis gas into electrical energy. However, further improvements in efficiency and availability of this plant technology are needed to render the alternative generation of electricity sensible from an economic point of view. One corresponding approach introduces hot gas cleaning facilities to the gasification plant which guarantee a removal of slag particles from the synthesis gas at high temperatures. The development of such filters depends on the availability of data on the material properties of the coal ash slags to be withdrawn. In this respect, the surface tension is a relevant characteristic. Currently, the surface tension of real coal ash slags as well as of synthetic model systems was measured successfully by means of the sessile drop and the maximum bubble pressure method. With regard to the sessile drop technique, those experiments were conducted in a gasification-like atmosphere at temperatures of up to 1500 C. Furthermore, the pressure inside the experimental vessel was raised to 10 bar in order to allow for deriving the influence of this variable on the surface tension. In contrast, maximum bubble pressure trials were realised at atmospheric pressure while the gas atmosphere assured inert conditions. For performing sessile drop measurements, a corresponding apparatus was set up and is described in detail in this thesis. Three computer algorithms were employed to calculate surface tensions out of the photos of sessile drops and their individual performance was evaluated. A very good agreement between two of the codes was found while the third one
Backward flow in a surface tension driven micropump
International Nuclear Information System (INIS)
Ju, Jongil; Park, Joong Yull; Lee, Sang-Hoon; Kim, Kyung Chun; Kim, Hyundong; Berthier, Erwin; Beebe, David J
2008-01-01
A surface tension driven micropump harnessing the pressure difference generated by drops of different curvature radii proves to be a simple and attractive passive method to drive fluid flow in microdevices. Here we observed the appearance of backward flow when the initial sizes of the droplets at the inlet and outlet ports are similar. To explain this phenomenon several hypotheses have been investigated. Consideration of the inertia of the fluid in the channel revealed that it alone is insufficient to explain the observed backward flow. We discovered that rotational flow inside the outlet droplet could be a source of inertia, explaining the generation of the backward flow. In addition, we have experimentally determined that the ratio of the volumes of the initial outlet drop and inlet drop correlates with the occurrence of the backward flow. (note)
International Nuclear Information System (INIS)
Bowring, R.W.; Garton, D.A.; Kinneir, J.H.
1961-09-01
Values of surface tension were obtained over the temperature range from near the melting point to near the normal boiling point of each substance. A capillary rise method was used employing a closed glass U-tube apparatus. The accuracy was ± 3% near the melting point falling to ± 5% near the normal boiling point. Values of the parachor calculated from the experimental data were in excellent agreement with those calculated from the molecular structure using the method proposed by Sugden. The surface tension in each case decreased with ascending temperature from near 30 to 40 dynes/cm close to the melting point to 13 to 15 dynes/cm near the normal boiling point. (author)
International Nuclear Information System (INIS)
Ghatee, Mohammad Hadi; Bahrami, Maryam; Khanjari, Neda
2013-01-01
Highlights: • Characterization of high purity synthesized alkyl quaternary ammonium ionic liquids. • Measurement of temperature dependent surface tension, density, viscosity and critical point. • Systematic increase of surface energy and surface entropy having plateau at high chain length. • Accurate application of VFT and fluidity equations to temperature dependent viscosities. • Particular variation of fluidity exponent with a plateau at high alkyl chain length. -- Abstract: In this work five quaternary ammonium-based ionic liquids with bis(trifluoromethylsulfonyl)imide anion were synthesized and their density, viscosity and surface tensions were measured in the temperature range (298 to 373) K. Surface tensions were measured by capillary rise method using a homemade capillary apparatus, in which the liquid/vapor can be brought into equilibrium practically. Measurements of viscosities and surface tensions were performed under water–vapor free atmosphere. The surface tension of quaternary ammonium-based ILs decreases as the alkyl chain length increases. Also surface energy and surface entropy are found as increasing functions of alkyl chain length with a plateau at high lengths in the surface. The viscosities measured by capillary viscometer fit in VFT equation, indication of non-Arrhenius ionic liquids. Viscosities are also fitted quite accurately in the relation we have developed recently as the fluidity equation with the characteristics exponent ϕ. Values of ϕ for ionic liquids are close to one another and tend to the limiting value, almost 0.328, asymptotically as the alkyl chain length increases. The critical temperatures predicted via the temperature dependent surface tensions decrease with increasing alkyl chain length of the cation. The trend of predicted critical temperature of these ionic liquids conforms to those of imidazolium-based ILs
Kou, Jisheng
2015-08-01
Surface tension significantly impacts subsurface flow and transport, and it is the main cause of capillary effect, a major immiscible two-phase flow mechanism for systems with a strong wettability preference. In this paper, we consider the numerical simulation of the surface tension of multi-component mixtures with the gradient theory of fluid interfaces. Major numerical challenges include that the system of the Euler-Lagrange equations is solved on the infinite interval and the coefficient matrix is not positive definite. We construct a linear transformation to reduce the Euler-Lagrange equations, and naturally introduce a path function, which is proven to be a monotonic function of the spatial coordinate variable. By using the linear transformation and the path function, we overcome the above difficulties and develop the efficient methods for calculating the interface and its interior compositions. Moreover, the computation of the surface tension is also simplified. The proposed methods do not need to solve the differential equation system, and they are easy to be implemented in practical applications. Numerical examples are tested to verify the efficiency of the proposed methods. © 2014 Elsevier B.V.
Surface tension and wetting behaviour of Bi-In-Sn alloys
International Nuclear Information System (INIS)
Ervina Efzan Mohd Noor; Ahmad Badri Ismail; Soong, T.K.; Chin, Y.T.; Luay Bakir Hussain
2007-01-01
Concerns about possible landfill contamination, influent discharge from production process are one of the reasons convert from lead-containing electronics to lead-free containing. The surface and interfacial properties of Bi-In-Sn lead-free solder system as a basic system of multicomponent alloys proposed as lead-free solder materials have been studied. The surface tension of Bi-In-Sn lead-free solder system of melting temperature 60 degree Celsius has been measured the temperature range 80 degree Celsius and 140 degree Celsius. The study of the wetting behaviour of Bi-In-Sn lead-free solder system on a Cu substrate has been performed by measuring contact angle on various metal substrates by Optical Microscopy with software. (author)
Surface Tension Driven Instability in the Regime of Stokes Flow
Yao, Zhenwei; Bowick, Mark; Xing, Xiangjun
2010-03-01
A cylinder of liquid inside another liquid is unstable towards droplet formation. This instability is driven by minimization of surface tension energy and was analyzed first by [1,2] and then by [3]. We revisit this problem in the limit of small Laplace number, where the inertial of liquids can be completely ignored. The stream function is found to obey biharmonic equation, and its analytic solutions are found. We rederive Tomotika's main results, and also obtain many new analytic results about the velocity fields. We also apply our formalism to study the recent experiment on toroidal liquid droplet[4]. Our framework shall have many applications in micro-fluidics. [1] L.Rayleigh, On The Instability of A Cylinder of Viscous Liquid Under Capillary Force, Scientific Papers, Cambridge, Vol.III, 1902. [2] L.Rayleigh, On The Instability of Cylindrical Fluid Surfaces, Scientific Papers, Cambridge, Vol.III, 1902. [3] S.Tomotika, On the Instability of a Cylindrical Thread of a Viscous Liquid surround by Another Viscous Fluid, Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, Volume 150, Issue 870, pp. 322-337. [4] E.Pairam and A.Fern'andez-Nieves, Generation and Stability of Toroidal Droplets in a Viscous Liquid, Physical Review Letters 102, 234501 (2009).
Temperature dependence of the dispersion of single crystals SrCl/sub 2/. [Temperature coefficient
Energy Technology Data Exchange (ETDEWEB)
Kuzin, M P [L' vovskij Gosudarstvennyj Univ. (Ukrainian SSR)
1976-01-01
The dispersion of the refractive index of SrCl/sub 2/ monocrystals in the spectral range 300-700 nm at temperatures of 223, 295 adn 373 K has been studied. The temperature coefficient of the refractive index as a function of the wave length has been determined for the room temperature. The function resembles the corresponding dependence for alkali-halide crystals.
Mapping surface tension induced menisci with application to tensiometry and refractometry.
Mishra, Avanish; Kulkarni, Varun; Khor, Jian-Wei; Wereley, Steve
2015-07-28
In this work, we discuss an optical method for measuring surface tension induced menisci. The principle of measurement is based upon the change in the background pattern produced by the curvature of the meniscus acting as a lens. We measure the meniscus profile over an inclined glass plate and utilize the measured meniscus for estimation of surface tension and refractive index.
Schroeder, Craig; Zheng, Wen; Fedkiw, Ronald
2012-01-01
-implicit and fully-coupled viscosity, pressure, and Lagrangian forces. We apply our new framework for forces on a Lagrangian mesh to the case of a surface tension force, which when treated explicitly leads to a tight time step restriction. By applying surface tension
Prediction of viscosities and surface tensions of fuels using a new corresponding states model
DEFF Research Database (Denmark)
Queimada, A.J.; Rolo, L.I.; Caco, A.I.
2006-01-01
While some properties of diesels are cheap, easy and fast to measure, such as densities, others such as surface tensions and viscosities are expensive and time consuming. A new approach that uses some basic information such as densities to predict viscosities and surface tensions is here proposed......) 2005 Elsevier Ltd. All rights reserved....
Measurement of the temperature coefficient of ratio transformers
Briggs, Matthew E.; Gammon, Robert W.; Shaumeyer, J. N.
1993-01-01
We have measured the temperature coefficient of the output of several ratio transformers at ratios near 0.500,000 using an ac bridge and a dual-phase, lock-in amplifier. The two orthogonal output components were each resolved to +/- ppb of the bridge drive signal. The results for three commercial ratio transformers between 20 and 50 C range from 0.5 to 100 ppb/K for the signal component in phase with the bridge drive, and from 4 to 300 ppb/K for the quadrature component.
Energy Technology Data Exchange (ETDEWEB)
Mosteiro, Laura; Casas, Lidia M. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain); Legido, Jose L. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain)], E-mail: xllegido@uvigo.es
2009-05-15
This paper reports the results of a new experimental study of thermophysical properties for the ternary mixture of {l_brace}diethyl carbonate + p-xylene + decane{r_brace}. Surface tension has been measured at 298.15 K and, density and speed of sound have been measured in the temperature range T = (288.15 to 308.15) K. Excess molar volumes, excess isentropic compressibilities, and surface tension deviations, have been calculated from experimental data. Surface tension deviations have been correlated with Cibulka equation and Nagata and Tamura equation was used for the other excess properties. Good accuracy has been obtained. These excess magnitudes are discussed qualitatively in terms of the nature and type of intermolecular interactions of the components involved.
Dynamic surface tension measurements of ionic surfactants using maximum bubble pressure tensiometry
Ortiz, Camilla U.; Moreno, Norman; Sharma, Vivek
Dynamic surface tension refers to the time dependent variation in surface tension, and is intimately linked with the rate of mass transfer of a surfactant from liquid sub-phase to the interface. The diffusion- or adsorption-limited kinetics of mass transfer to interfaces is said to impact the so-called foamability and the Gibbs-Marangoni elasticity of surfaces. Dynamic surface tension measurements carried out with conventional methods like pendant drop analysis, Wilhelmy plate, etc. are limited in their temporal resolution (>50 ms). In this study, we describe design and application of maximum bubble pressure tensiometry for the measurement of dynamic surface tension effects at extremely short (1-50 ms) timescales. Using experiments and theory, we discuss the overall adsorption kinetics of charged surfactants, paying special attention to the influence of added salt on dynamic surface tension.
Improved cryo-resistors with low temperature coefficients
International Nuclear Information System (INIS)
Warnecke, P.; Braun, E.
1989-01-01
A new type of 10- and 12.9κΩ cryo-resistors operating in a liquid helium bath with small temperature coefficient of resistivity have been built. Details for the fabrication of these improved cryo-resistors are reported. Experimental evidence of their drift rates are on the order of a few parts in 10 9 per day. A reduction of the mean pressure of 98.7 kPa in the helium dewar to 86.1 kPa, corresponding to a temperature decrease from 4.19 to 4.07 Κ, did not change the resistance value by more than the experimental resolution of 4 parts in 10 8
Compilation report of VHTRC temperature coefficient benchmark calculations
Energy Technology Data Exchange (ETDEWEB)
Yasuda, Hideshi; Yamane, Tsuyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1995-11-01
A calculational benchmark problem has been proposed by JAERI to an IAEA Coordinated Research Program, `Verification of Safety Related Neutronic Calculation for Low-enriched Gas-cooled Reactors` to investigate the accuracy of calculation results obtained by using codes of the participating countries. This benchmark is made on the basis of assembly heating experiments at a pin-in block type critical assembly, VHTRC. Requested calculation items are the cell parameters, effective multiplication factor, temperature coefficient of reactivity, reaction rates, fission rate distribution, etc. Seven institutions from five countries have joined the benchmark works. Calculation results are summarized in this report with some remarks by the authors. Each institute analyzed the problem by applying the calculation code system which was prepared for the HTGR development of individual country. The values of the most important parameter, k{sub eff}, by all institutes showed good agreement with each other and with the experimental ones within 1%. The temperature coefficient agreed within 13%. The values of several cell parameters calculated by several institutes did not agree with the other`s ones. It will be necessary to check the calculation conditions again for getting better agreement. (J.P.N.).
Directory of Open Access Journals (Sweden)
H. Hammami
2017-08-01
experiment the vegetable oils application on diffusion of sethoxydim was conducted also based on a completely randomized design. A K100 tensiometer was used to measure the surface tension of water and sethoxydim solution containing vegetable oils. For measuring the diffusion of sethoxydim solution containing vegetable oils, water sensitive paper was used. The surface changing color was evaluated by using MIP software. Wild oat seeds were collected from plants in the field near the research greenhouse at Ferdowsi University of Mashhad, Iran. They were dehulled and placed in 11 cm diameter Petri dishes on top of a single layer of filter paper (Whatman International, Maidstone, UK. Then, 10 mL of 0.2% KNO3 solution were added to each Petri dish and the seeds were incubated for 48 h at 4–5°C in the dark. The seeds then were germinated under temperature and relative humidity control conditions in the dark (16 h at 20°C and 8 h at 10°C, with 45% and 65% relative humidity, respectively. By this method, 92–98.5% of the seeds germinated. Ten germinated seed were planted in each 1.5 L plastic pot that was filled with a mixture of sand, clay loam soil, and peat (1:1:1; v/v/v. The pots were sub irrigated every 3 days. The seedlings were thinned to four per pot at the one leaf stage and 40 mL of a water-soluble N: P: K (20:20:20 fertilizer, at a concentration of 3 g of fertilizer per liter of tap water, were supplied to each pot. Results and Discussion: The results showed that the use of vegetable oils except castor oil caused reduction in the surface tension of distilled water. About the surface tension of the sethoxydim solution, all vegetable oils significantly reduced surface tension. There is anegative relationship between surface tension of sethoxydim solution and efficiency of sethoxydim. Regression analysis results of the surface tension and spray deposit distribution on sensitive paper percent showed strong negative relationship them. Effects of adjuvants on herbicide
Surface tension effects on vertical upward annular flows in a small diameter pipe
Energy Technology Data Exchange (ETDEWEB)
Sadatomi, Michio, E-mail: sadatomi@mech.kumamoto-u.ac.jp [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Kawahara, Akimaro [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Suzuki, Aruta [Plant Design & Engineering Dept., Environment, Energy & Plant Headquarters, Hitachi Zosen Corporation, 7-89, Nankokita 1-chome, Suminoe-ku, Osaka, 559-8559 (Japan)
2016-12-15
Highlights: • Surface tension effects were clarified on annular flow in a small diameter pipe. • The mean liquid film thickness became thinner with decreasing of surface tension. • The liquid droplet fraction and the interfacial shear stress became higher with it. • New prediction methods for the above parameters were developed and validated. - Abstract: Experiments were conducted to study the surface tension effects on vertical upward annular flows in a 5 mm I.D. pipe using water and low surface tension water with a little surfactant as the test liquid and air as the test gas. Firstly, the experimental results on the mean liquid film thickness, the liquid droplet fraction and the interfacial shear stress in annular flows together with some flow pictures are presented to clarify the surface tension effects. From these, the followings are clarified: In the low surface tension case, the liquid film surface becomes rough, the liquid film thickness thin, the liquid droplet fraction high, and the interfacial shear stress high. Secondary, correlations in literatures for the respective parameters are tested against the present data. The test results show that no correlation for the respective parameters could predict well the present data. Thus, correlations are revised by accounting for the surface tension effects. The results of the experiments, the correlations tests and their revisions mentioned above are presented in the present paper.
Density functional theory of simple polymers in a slit pore. III. Surface tension
International Nuclear Information System (INIS)
Hooper, Justin B.; McCoy, John D.; Curro, John G.; Swol, Frank van
2000-01-01
In a previous study of tangent hard-site chains near a surface, the inhomogeneous density profiles were found through density functional theory. In the current study, the surface tensions of these systems are found from the results of the previous study through a thermodynamic integration. The calculated surface tensions are then compared to those found directly through computer simulation. Both the surface tension and surface excess for polymeric systems are shown to differ qualitatively from those of atomic systems, although certain similarities are seen at high densities. (c) 2000 American Institute of Physics
A Computational Study of Richtmyer-Meshkov Instability with Surface Tension
Francois, Marianne; Velechovsky, Jan; Jibben, Zach; Masser, Thomas; LANL Collaboration
2017-11-01
We have added the capability to model surface tension in our adaptive mesh refinement compressible flow solver, xRage. Our surface tension capability employs the continuum surface force to model surface tension and the height function method to compute curvatures. We have verified our model implementation for the static and oscillating droplets test cases and the linear regime of the Rayleigh-Taylor instability. With this newly added capability, we have performed a numerical study of the effects of surface tension on single-mode and multi-mode Richtmyer-Meshkov instability. This work was performed under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory under Contract No. DE-AC52 - 06NA25396.
Directory of Open Access Journals (Sweden)
Qieni Lu
2015-08-01
Full Text Available We measure temperature dependence on Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal simultaneously in this work, based on digital holographic interferometry (DHI. And the spatial distribution of the field-induced refractive index change can also be visualized and estimated by numerically retrieving sequential phase maps of Mn:Fe:KTN crystal from recording digital holograms in different states. The refractive indices decrease with increasing temperature and quadratic polarized optical coefficient is insensitive to temperature. The experimental results suggest that the DHI method presented here is highly applicable in both visualizing the temporal and spatial behavior of the internal electric field and accurately measuring electro-optic coefficient for electrooptical media.
Density-functional calculations of the surface tension of liquid Al and Na
Stroud, D.; Grimson, M. J.
1984-01-01
Calculations of the surface tensions of liquid Al and Na are described using the full ionic density functional formalism of Wood and Stroud (1983). Surface tensions are in good agreement with experiment in both cases, with results substantially better for Al than those found previously in the gradient approximation. Preliminary minimization with respect to surface profile leads to an oscillatory profile superimposed on a nearly steplike ionic density disribution; the oscillations have a wavellength of about a hardsphere diameter.
Kalantarian, Ali; Ninomiya, Hiromasa; Saad, Sameh M.I.; David, Robert; Winklbauer, Rudolf; Neumann, A. Wilhelm
2009-01-01
Biological tissues behave in certain respects like liquids. Consequently, the surface tension concept can be used to explain aspects of the in vitro and in vivo behavior of multicellular aggregates. Unfortunately, conventional methods of surface tension measurement cannot be readily applied to small cell aggregates. This difficulty can be overcome by an experimentally straightforward method consisting of centrifugation followed by axisymmetric drop shape analysis (ADSA). Since the aggregates ...
Static pressure and temperature coefficients of working standard microphones
DEFF Research Database (Denmark)
Barrera Figueroa, Salvador; Cutanda Henriquez, Vicente; Torras Rosell, Antoni
2016-01-01
be a significant contribution to the uncertainty of the measurement. Determining the environmental coefficients of individual specimens of measurement microphones can be a straightforward though time-consuming procedure provided the appropriate facilities are available. An alternative is to determine them using...... coefficients. For this purpose, the environmental coefficients of some commercially available microphones have been determined experimentally, and whenever possible, compared with the coefficients determined numerically using the Boundary Element Method....... for these coefficients which are used for calibration purposes. Working standard microphones are not exempt of these influences. However, manufacturers usually provide a low frequency value of the environmental coefficient. While in some applications the influence of this coefficient may be negligible, in others it may...
Evaluation on Dorsey Method in Surface Tension Measurement of Solder Liquids Containing Surfactants
Zhao, Xingke; Xie, Feiming; Fan, Jinsheng; Liu, Dayong; Huang, Jihua; Chen, Shuhai
2018-06-01
With the purpose of developing a feasible approach for measuring the surface tension of solders containing surfactants, the surface tension of Sn-3Ag-0.5Cu-xP solder alloys, with various drop sizes as well as different phosphorus (P) content, was evaluated using the Dorsey method based on the sessile drop test. The results show that the accuracy of the surface tension calculations depends on both of sessile drop size and the liquid metal composition. With a proper drop size, in the range of 4.5 mm to 5.3 mm in equivalent spherical diameters, the deviation of the surface tension calculation can be limited to 1.43 mN·m-1 and 6.30 mN·m-1 for SnAgCu and SnAgCu-P, respectively. The surface tension of SnAgCu-xP solder alloys decreases quickly to a minimum value when the P content reaches 0.5 wt% and subsequently increases slowly with the P content further increasing. The formation of a P-enriched surface layer and Sn4P3 intermetallic phases is regarded to be responsible for the decreasing and subsequent increasing of surface tension, respectively.
Bechert, M.; Scheid, B.
2017-11-01
The draw resonance effect appears in fiber spinning processes if the ratio of take-up to inlet velocity, the so-called draw ratio, exceeds a critical value and manifests itself in steady oscillations of flow velocity and fiber diameter. We study the effect of surface tension on the draw resonance behavior of Newtonian fiber spinning in the presence of inertia and gravity. Utilizing an alternative scaling makes it possible to visualize the results in stability maps of highly practical relevance. The interplay of the destabilizing effect of surface tension and the stabilizing effects of inertia and gravity lead to nonmonotonic stability behavior and local stability maxima with respect to the dimensionless fluidity and the dimensionless inlet velocity. A region of unconditional instability caused by the influence of surface tension is found in addition to the region of unconditional stability caused by inertia, which was described in previous works [M. Bechert, D. W. Schubert, and B. Scheid, Eur. J. Mech B 52, 68 (2015), 10.1016/j.euromechflu.2015.02.005; Phys. Fluids 28, 024109 (2016), 10.1063/1.4941762]. Due to its importance for a particular group of fiber spinning applications, a viscous-gravity-surface-tension regime, i.e., negligible effect of inertia, is analyzed separately. The mechanism underlying the destabilizing effect of surface tension is discussed and established stability criteria are tested for validity in the presence of surface tension.
The effect of surface tension on the contraction coefficient of a jet
International Nuclear Information System (INIS)
Gasmi, A; Mekias, H
2003-01-01
Two-dimensional free surface potential flow issued from an opening of a container is considered. The flow is assumed to be inviscid and incompressible. The mathematical problem, which is characterized by the nonlinear boundary condition on the free surface of an unknown equation, is solved via a series truncation. We computed solutions for all Weber numbers. Our problem is an extension of the work done by Ackerberg and Liu (1987 Phys. Fluids 30 289-96), the results confirm and extend their results
International Nuclear Information System (INIS)
Li, Lihua; Zhang, Jianbin; Li, Qiang; Guo, Bo; Zhao, Tianxiang; Sha, Feng
2014-01-01
Graphical abstract: Excess property of the binary system 1,2-ethanediamine (EDA) + diethylene glycol (DEG). - Highlights: • Densities and viscosities of EDA + DEG at 298.15–318.150 K were listed. • Thermodynamics data of EDA + DEG at 298.15–318.15 K were calculated. • Surface tension of EDA + DEG at 298.15 K was measured. • Intermolecular interaction of EDA with DEG was discussed. - Abstract: This paper reports density and viscosity data at T = 298.15, 303.15, 308.15, 313.15, and 318.15 K and surface tension data at 298.15 K for the binary system 1,2-ethanediamine (EDA) + diethylene glycol (DEG) as a function of composition under atmospheric pressure. From the experimental density and viscosity data, the excess molar volume and viscosity deviation were calculated, and the results were fitted to a Redlich–Kister equation to obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities. Based on the kinematic viscosity data, enthalpy of activation for viscous flow, entropy of activation for the viscous flow, and Gibbs energies of activation of viscous flow were calculated. In addition, based on Fourier transform infrared spectra, UV–vis spectra, and electrical conductivity for the system EDA + DEG with various concentrations, intermolecular interaction of EDA with DEG was discussed
Corsetti, James A; Green, William E; Ellis, Jonathan D; Schmidt, Greg R; Moore, Duncan T
2016-10-10
Characterizing the thermal properties of optical materials is necessary for understanding how to design an optical system for changing environmental conditions. A method is presented for simultaneously measuring both the linear coefficient of thermal expansion and the temperature-dependent refractive index coefficient of a sample interferometrically in air. Both the design and fabrication of the interferometer is presented as well as a discussion of the results of measuring both a steel and a CaF2 sample.
Czech Academy of Sciences Publication Activity Database
Klomfar, Jaroslav; Součková, Monika; Pátek, Jaroslav
2017-01-01
Roč. 431, January (2017), s. 24-33 ISSN 0378-3812 R&D Projects: GA ČR GA13-00145S Institutional support: RVO:61388998 Keywords : ionic liquid * pyridinium-based cation * bis(triﬂuoromethylsulfonyl)imide anion * density-temperature relation * surface tension-temperature relation * recommended property values Subject RIV: BJ - Thermodynamics OBOR OECD: Thermodynamics Impact factor: 2.473, year: 2016
The static pressure and temperature coefficients of laboratory standard microphones
DEFF Research Database (Denmark)
Rasmussen, Knud
1999-01-01
, for a given type of microphone, can be described by a single function when the coefficients are normalized by their low-frequency value and the frequency is normalized with respect to the individual resonance frequency of the microphone. The theoretical results are supported by experimentally determined...... on an extended lumped parameter representation of the mechanical and acoustic elements of the microphone. The extension involves the frequency dependency of the dynamic diaphragm mass and stiffness as well as a first-order approximation of resonances in the back cavity. It was found that each coefficient...... coefficients for about twenty samples of microphone types B&K 4160 and B&K 4180....
Vinš, Václav; Hošek, Jan; Hykl, Jiří; Hrubý, Jan
2015-05-01
New experimental apparatus for measurement of the surface tension of liquids under the metastable supercooled state has been designed and assembled in the study. The measuring technique is similar to the method employed by P.T. Hacker [NACA TN 2510] in 1951. A short liquid thread of the liquid sample was sucked inside a horizontal capillary tube partly placed in a temperature-controlled glass chamber. One end of the capillary tube was connected to a setup with inert gas which allowed for precise tuning of the gas overpressure in order of hundreds of Pa. The open end of the capillary tube was precisely grinded and polished before the measurement in order to assure planarity and perpendicularity of the outer surface. The liquid meniscus at the open end was illuminated by a laser beam and observed by a digital camera. Application of an increasing overpressure of the inert gas at the inner meniscus of the liquid thread caused variation of the outer meniscus such that it gradually changed from concave to flat and subsequently convex shape. The surface tension at the temperature of the inner meniscus could be evaluated from the overpressure corresponding to exactly planar outer meniscus. Detailed description of the new setup together with results of the preliminary tests is provided in the study.
Bubble extinction in Hele-Shaw flow with surface tension and kinetic undercooling regularization
International Nuclear Information System (INIS)
Dallaston, Michael C; McCue, Scott W
2013-01-01
We perform an analytic and numerical study of an inviscid contracting bubble in a two-dimensional Hele-Shaw cell, where the effects of both surface tension and kinetic undercooling on the moving bubble boundary are not neglected. In contrast to expanding bubbles, in which both boundary effects regularize the ill-posedness arising from the viscous (Saffman–Taylor) instability, we show that in contracting bubbles the two boundary effects are in competition, with surface tension stabilizing the boundary, and kinetic undercooling destabilizing it. This competition leads to interesting bifurcation behaviour in the asymptotic shape of the bubble in the limit it approaches extinction. In this limit, the boundary may tend to become either circular, or approach a line or ‘slit’ of zero thickness, depending on the initial condition and the value of a nondimensional surface tension parameter. We show that over a critical range of surface tension values, both these asymptotic shapes are stable. In this regime there exists a third, unstable branch of limiting self-similar bubble shapes, with an asymptotic aspect ratio (dependent on the surface tension) between zero and one. We support our asymptotic analysis with a numerical scheme that utilizes the applicability of complex variable theory to Hele-Shaw flow. (paper)
International Nuclear Information System (INIS)
Behroozi, F.; Mohazzabi, P.; McCrickard, J.
1995-01-01
The familiar catenary is the shape assumed by a chain or string as it hangs from two points. The mathematical equation of the catenary was first published more than three hundred years ago by Leibnitz and Huygen, among others. Here we consider the shapes assumed by a hanging string in the presence of gravity and surface tension. The surface tension is introduced by suspending the string from a thin horizontal rod while the area bounded by the string and the rod is covered with a soap film. The string then assumes new and wonderful shapes depending on the relative strength of the surface tension and the weight per unit length of the string. When surface tension dominates, the string is pulled inward, assuming a convex shape similar to the Greek letter γ. On the other hand, when gravity is dominant the string is pulled outward and assumes a concave shape best described as a distorted catenary. However, when the gravitational force normal to the string matches the surface tension, the string takes a linear configuration similar to the letter V. Under suitable conditions, the string can be made to assume any of the three configurations by adjusting the separation of its end points. The equations that describe the shape of the string are derived by minimizing the total energy of the system and are presented for the three principal configurations
Kalantarian, Ali; Ninomiya, Hiromasa; Saad, Sameh M I; David, Robert; Winklbauer, Rudolf; Neumann, A Wilhelm
2009-02-18
Biological tissues behave in certain respects like liquids. Consequently, the surface tension concept can be used to explain aspects of the in vitro and in vivo behavior of multicellular aggregates. Unfortunately, conventional methods of surface tension measurement cannot be readily applied to small cell aggregates. This difficulty can be overcome by an experimentally straightforward method consisting of centrifugation followed by axisymmetric drop shape analysis (ADSA). Since the aggregates typically show roughness, standard ADSA cannot be applied and we introduce a novel numerical method called ADSA-IP (ADSA for imperfect profile) for this purpose. To examine the new methodology, embryonic tissues from the gastrula of the frog, Xenopus laevis, deformed in the centrifuge are used. It is confirmed that surface tension measurements are independent of centrifugal force and aggregate size. Surface tension is measured for ectodermal cells in four sample batches, and varies between 1.1 and 7.7 mJ/m2. Surface tension is also measured for aggregates of cells expressing cytoplasmically truncated EP/C-cadherin, and is approximately half as large. In parallel, such aggregates show a reduction in convergent extension-driven elongation after activin treatment, reflecting diminished intercellular cohesion.
Modeling the surface tension of complex, reactive organic-inorganic mixtures
Schwier, A. N.; Viglione, G. A.; Li, Z.; McNeill, V. Faye
2013-11-01
Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2-6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski-Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic-inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (χ2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.
A study of temperature coefficients of reactivity for a Savannah River Site tritium-producing charge
International Nuclear Information System (INIS)
George, D.L.; Frost, R.L.
1991-01-01
Temperature coefficients of reactivity have been calculated for the Mark 22 assembly in the K-14 charge at the Savannah River Site. Temperature coefficients are the most important reactivity feedback mechanism in SRS reactors; they are used in all safety analyses performed in support of the Safety Analysis Report, and in operations to predict reactivity changes with control rod moves. The effects of the radial location of the assembly in the reactor, isotope depletion, and thermal expansion of the metal components on the temperature coefficients have also been investigated. With the exception of the dead space coefficient, all of the regional temperature coefficients were found to be negative or zero. All of the temperature coefficients become more negative with isotopic depletion over the fuel cycle. Coefficients also become more negative with increasing radial distance of the assembly from the center of the core; this is proven from first principles and confirmed by calculations. It was found that axial and radial thermal expansion effects on the metal fuel and target tubes counteract one another, indicating these effects do not need to be considered in future temperature coefficient calculations for the Mark 22 assembly. The moderator coefficient was found to be nonlinear with temperature; thus, the values derived for accidents involving increases in moderator temperature are significantly different than those for decreases in moderator temperature, although the moderator coefficient is always negative
Surface tension driven shaping of adhesive microfluidic channel walls
DEFF Research Database (Denmark)
Janting, Jakob; Storm, Elisabeth K.; Geschke, Oliver
2005-01-01
, line height and distance, and temperature. Focus of the work has been on predicting the equilibrium geometries with FEM simulations using as input measured adhesive wetting angles, different adhesive line distances and height. The studied substrates are glass microscope slides, PEEK and PMMA...
Sauer, Dorothea; McGinity, James W
2009-06-01
Limited information on thermally cured dry-powder coatings used for solid dosage forms has been available in the literature. The aim of this study was to characterize the film formation process of Eudragit L 100-55 dry-powder coatings and to investigate the influence of film additives on melt viscosity and surface tension. The coating process employed no liquids and the plasticizer was combined with the polymer using hot melt extrusion. Thermoanalytical methods including differential scanning calorimetry and thermogravimetric analysis (TGA) were used to investigate the thermal properties of the dry-coating formulations. The rheological behavior of the coating formulations were characterized with the extrusion torque, and the surface energy parameters were determined from contact angle measurements. The influence of the level of triethyl citrate (TEC) as plasticizer and polyethylene glycol (PEG) 3350 in the polymer film on film formation was investigated using a digital force tester. TGA confirmed thermal stability of all coating excipients at the investigated curing conditions. Increasing TEC levels and the addition of PEG 3350 as a low melting excipient in the coating reduced the viscosity of the polymer. Plasticization of the polymer with TEC increased the surface free energy, whereas the admixture of 10% PEG 3350 did not affect the surface free energy of Eudragit L 100-55. The spreading coefficient of the polymers over two sample tablet formulations was reduced with increasing surface free energy. During the curing process, puncture strength, and elongation of powder-cast films increased. The effect of curing time on the mechanical properties was dependent on the plasticizer content. The incorporation of TEC and PEG 3350 into the Eudragit L 100-55 powder coating formulation improved film formation. Mechanical testing of powder-cast films showed an increase of both elongation and puncture strength over the curing process as criterion for polymer particle fusion
International Nuclear Information System (INIS)
Goto, Minoru; Takamatsu, Kuniyoshi
2007-03-01
The HTTR temperature coefficients required for the core dynamics calculations had been calculated from the HTTR core calculation results by the diffusion code with which the corrections had been performed using the core calculation results by the Monte-Carlo code MVP. This calculation method for the temperature coefficients was considered to have some issues to be improved. Then, the calculation method was improved to obtain the temperature coefficients in which the corrections by the Monte-Carlo code were not required. Specifically, from the point of view of neutron spectrum calculated by lattice calculations, the lattice model was revised which had been used for the calculations of the temperature coefficients. The HTTR core calculations were performed by the diffusion code with the group constants which were generated by the lattice calculations with the improved lattice model. The core calculations and the lattice calculations were performed by the SRAC code system. The HTTR core dynamics calculation was performed with the temperature coefficient obtained from the core calculation results. In consequence, the core dynamics calculation result showed good agreement with the experimental data and the valid temperature coefficient could be calculated only by the diffusion code without the corrections by Monte-Carlo code. (author)
A hybrid model to predict the onset of gas entrainment with surface tension effects
International Nuclear Information System (INIS)
Saleh, W.; Bowden, R.C.; Hassan, I.G.; Kadem, L.
2008-01-01
The onset of gas entrainment, in a single downward oriented discharge from a stratified gas-liquid region with was modeled. The assumptions made in the development of the model reduced the problem to that of a potential flow. The discharge was modeled as a point-sink. Through use of the Kelvin-Laplace equation the model included the effects of surface tension. The resulting model required further knowledge of the flow field, specifically the dip radius of curvature prior to the onset of gas entrainment. The dip shape and size was investigated experimentally and correlations were provided to characterize the dip in terms of the discharge Froude number. The experimental correlation was used in conjunction with the theoretical model to predict the critical height. The results showed that by including surface tension effects the predicted critical height showed excellent agreement with experimental data. Surface tension reduces the critical height through the Bond number
Modeling maximum daily temperature using a varying coefficient regression model
Han Li; Xinwei Deng; Dong-Yum Kim; Eric P. Smith
2014-01-01
Relationships between stream water and air temperatures are often modeled using linear or nonlinear regression methods. Despite a strong relationship between water and air temperatures and a variety of models that are effective for data summarized on a weekly basis, such models did not yield consistently good predictions for summaries such as daily maximum temperature...
A new corresponding state-based correlation for the surface tension of organic fatty acids
Zhang, Cuihua; Tian, Jianxiang; Zheng, Mengmeng; Yi, Huili; Zhang, Laibin; Liu, Shuzhen
2018-01-01
In this paper, we proposed a new corresponding state-based correlation for organic fatty (aliphatic, carboxylic and polyfunctional) acids. By using the recently published surface tension data of the 99 acids [A. Mulero and I. Cachadiña, J. Phys. Chem. Ref. Data 45 (2016) 033105] and comparing with the recently published other corresponding state correlations, we found that this correlation reproduces the lowest absolute average deviation (AAD) values for 82 acids out of the 99 acids. It can reproduce the surface tension data with AAD less than 10% for 89 out of the 99 acids.
Cuenot, Stéphane; Frétigny, Christian; Demoustier-Champagne, Sophie; Nysten, Bernard
2004-04-01
The effect of reduced size on the elastic properties measured on silver and lead nanowires and on polypyrrole nanotubes with an outer diameter ranging between 30 and 250 nm is presented and discussed. Resonant-contact atomic force microscopy (AFM) is used to measure their apparent elastic modulus. The measured modulus of the nanomaterials with smaller diameters is significantly higher than that of the larger ones. The latter is comparable to the macroscopic modulus of the materials. The increase of the apparent elastic modulus for the smaller diameters is attributed to surface tension effects. The surface tension of the probed material may be experimentally determined from these AFM measurements.
Predicting the minimum liquid surface tension activity of pseudomonads expressing biosurfactants.
Mohammed, I U; Deeni, Y; Hapca, S M; McLaughlin, K; Spiers, A J
2015-01-01
Bacteria produce a variety of biosurfactants capable of significantly reducing liquid (aqueous) surface tension (γ) with a range of biological roles and biotechnological uses. To determine the lowest achievable surface tension (γMin ), we tested a diverse collection of Pseudomonas-like isolates from contaminated soil and activated sludge and identified those expressing biosurfactants by drop-collapse assay. Liquid surface tension-reducing ability was quantitatively determined by tensiometry, with 57 isolates found to significantly lower culture supernatant surface tensions to 24·5-49·1 mN m(-1) . Differences in biosurfactant behaviour determined by foaming, emulsion and oil-displacement assays were also observed amongst isolates producing surface tensions of 25-27 mN m(-1) , suggesting that a range of structurally diverse biosurfactants were being expressed. Individual distribution identification (IDI) analysis was used to identify the theoretical probability distribution that best fitted the surface tension data, which predicted a γMin of 24·24 mN m(-1) . This was in agreement with predictions based on earlier work of published mixed bacterial spp. data, suggesting a fundamental limit to the ability of bacterial biosurfactants to reduce surface tensions in aqueous systems. This implies a biological restriction on the synthesis and export of these agents or a physical-chemical restriction on their functioning once produced. Numerous surveys of biosurfactant-producing bacteria have been conducted, but only recently has an attempt been made to predict the minimum liquid surface tension these surface-active agents can achieve. Here, we determine a theoretical minimum of 24 mN m(-1) by statistical analysis of tensiometry data, suggesting a fundamental limit for biosurfactant activity in bacterial cultures incubated under standard growth conditions. This raises a challenge to our understanding of biosurfactant expression, secretion and function, as well as
Kou, Jisheng; Sun, Shuyu
2014-01-01
The gradient theory for the surface tension of simple fluids and mixtures is rigorously analyzed based on mathematical theory. The finite element approximation of surface tension is developed and analyzed, and moreover, an adaptive finite element method based on a physical-based estimator is proposed and it can be coupled efficiently with Newton's method as well. The numerical tests are carried out both to verify the proposed theory and to demonstrate the efficiency of the proposed method. © 2013 Elsevier B.V. All rights reserved.
Temporal instability of viscous liquid microjets with spatially varying surface tension
Energy Technology Data Exchange (ETDEWEB)
Furlani, E P [Integrated Materials and Microstructures Laboratory, Electronic Imaging Products, Eastman Kodak Company, Rochester, NY 14650-2121 (United States)
2005-01-07
A linear theory is developed for the temporal instability of a viscous liquid microjet of Newtonian fluid with a spatially periodic variation of surface tension imposed along its length. The variation of surface tension induces Marangoni flow within the jet that leads to breakup and drop formation. An analytical expression is derived for the behaviour of the free surface of the microjet. This expression is useful for parametric analysis of jet instability and breakup as a function of jet radius, wavelength and fluid properties.
Temporal instability of viscous liquid microjets with spatially varying surface tension
International Nuclear Information System (INIS)
Furlani, E P
2005-01-01
A linear theory is developed for the temporal instability of a viscous liquid microjet of Newtonian fluid with a spatially periodic variation of surface tension imposed along its length. The variation of surface tension induces Marangoni flow within the jet that leads to breakup and drop formation. An analytical expression is derived for the behaviour of the free surface of the microjet. This expression is useful for parametric analysis of jet instability and breakup as a function of jet radius, wavelength and fluid properties
Kou, Jisheng
2014-01-01
The gradient theory for the surface tension of simple fluids and mixtures is rigorously analyzed based on mathematical theory. The finite element approximation of surface tension is developed and analyzed, and moreover, an adaptive finite element method based on a physical-based estimator is proposed and it can be coupled efficiently with Newton\\'s method as well. The numerical tests are carried out both to verify the proposed theory and to demonstrate the efficiency of the proposed method. © 2013 Elsevier B.V. All rights reserved.
A simple laboratory experiment to measure the surface tension of a liquid in contact with air
International Nuclear Information System (INIS)
Riba, Jordi-Roger; Esteban, Bernat
2014-01-01
A simple and accurate laboratory experiment to measure the surface tension of liquids has been developed, which is well suited to teach the behaviour of liquids to first- or second-year students of physics, engineering or chemistry. The experimental setup requires relatively inexpensive equipment usually found in physics and chemistry laboratories, since it consists of a used or recycled burette, an analytical balance and a stereoscopic microscope or a micrometer. Experimental data and error analysis show that the surface tension of distilled water, 1-butanol and glycerol can be determined with accuracy better than 1.4%. (paper)
Interrelation of surface tension, optical turbidity, and color of operational transformer oils
International Nuclear Information System (INIS)
L’vov, S. Yu.; Lyut’ko, E. O.; Lankau, Ya. V.; Komarov, V. B.; Seliverstov, A. F.; Bondareva, V. N.; L’vov, Yu. N.; L’vov, M. Yu.; Ershov, B. G.
2011-01-01
Measurements of the acidity, optical turbidity, surface tension, and color of transformer oil from 54 power transformers, autotransformers, and shunt reactors are reported. Changes in surface tension, optical turbidity, and color are found to obey adequate linear correlations, while the acidity has no correlation with any of these properties. Numerical criteria for the maximum permissible state (quality) of the oil with respect to optical turbidity and color are obtained. Recommendations to operating staff are provided for cases in which the criteria for optical turbidity and color are exceeded.
Dadashev, R. Kh.; Dzhambulatov, R. S.; Mezhidov, V. Kh.; Elimkhanov, D. Z.
2018-05-01
Concentration dependences of the surface tension and density of solutions of three-component acetone-ethanol-water systems and the bounding binary systems at 273 K are studied. The molar volume, adsorption, and composition of surface layers are calculated. Experimental data and calculations show that three-component solutions are close to ideal ones. The surface tensions of these solutions are calculated using semi-empirical and theoretical equations. Theoretical equations qualitatively convey the concentration dependence of surface tension. A semi-empirical method based on the Köhler equation allows us to predict the concentration dependence of surface tension within the experimental error.
Rhim, W. K.; Ishikawa, T.
1998-01-01
Thermophysical properties of molten germanium such as the density, the thermal expansion coefficient, the hemisphereical total emissivity, the constant pressure specific heat capacity, the surface tension, and the electrical resistivity have been measured using the High Temperature Electrostatic Levitator at JPL.
On the second-order temperature jump coefficient of a dilute gas
Radtke, Gregg A.; Hadjiconstantinou, N. G.; Takata, S.; Aoki, K.
2012-09-01
We use LVDSMC simulations to calculate the second-order temperature jump coefficient for a dilute gas whose temperature is governed by the Poisson equation with a constant forcing term. Both the hard sphere gas and the BGK model of the Boltzmann equation are considered. Our results show that the temperature jump coefficient is different from the well known linear and steady case where the temperature is governed by the homogeneous heat conduction (Laplace) equation.
DEFF Research Database (Denmark)
Queimada, Antonio; Silva, Filipa A. E.; Caco, Ana I.
2003-01-01
To extend the surface tension database for heavy or asymmetric n-alkane mixtures, measurements were performed using the Wilhelmy plate method. Measured systems included the binary mixtures heptane + eicosane, heptane + docosane and heptane + tetracosane and the ternary mixture heptane + eicosane ...
DEFF Research Database (Denmark)
Queimada, Antonio; Silva, Filipa A.E; Caco, Ana I.
2003-01-01
To extend the surface tension database for heavy or asymmetric n-alkane mixtures, measurements were performed using the Wilhelmy plate method. Measured systems included the binary mixtures heptane + eicosane, heptane + docosane and heptane + tetracosane and the ternary mixture heptane + eicosane...
Generation of Recommendable Values for the Surface Tension of Water Using a Nonparametric Regression
Czech Academy of Sciences Publication Activity Database
Pátek, Jaroslav; Součková, Monika; Klomfar, Jaroslav
2016-01-01
Roč. 61, č. 2 (2016), s. 928-935 ISSN 0021-9568 R&D Projects: GA ČR GA13-00145S Institutional support: RVO:61388998 Keywords : water * surface tension * experimental data * recommended data Subject RIV: BJ - Thermodynamics Impact factor: 2.323, year: 2016
Standard reference data for the air-liquid and vapor-liquid surface tension of benzene
Czech Academy of Sciences Publication Activity Database
Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav
2013-01-01
Roč. 356, October (2013), s. 329-337 ISSN 0378-3812 R&D Projects: GA ČR GA101/09/0010 Institutional support: RVO:61388998 Keywords : benzene * surface tension * experimental data * standard reference data Subject RIV: BJ - Thermodynamics Impact factor: 2.241, year: 2013 http://www.sciencedirect.com/science/article/pii/S0378381213004196
Shapes of an Air Taylor Bubble in Stagnant Liquids Influenced by Different Surface Tensions
Lertnuwat, B.
2018-02-01
The aim of this work is to propose an empirical model for predicting shapes of a Taylor bubble, which is a part of slug flows, under different values of the surface tension in stagnant liquids by employing numerical simulations. The k - Ɛ turbulence model was used in the framework of finite volume method for simulating flow fields in a unit of slug flow and also the pressure distribution on a Taylor bubble surface. Assuming that an air pressure distribution inside the Taylor bubble must be uniform, a grid search method was exploited to find an appropriate shape of a Taylor bubble for six values of surface tension. It was found that the shape of a Taylor bubble would be blunter if the surface tension was increased. This was because the surface tension affected the Froude number, controlling the flow around a Taylor bubble. The simulation results were also compared with the Taylor bubble shape, created by the Dumitrescu-and-Taylor model and former studies in order to ensure that they were consistent. Finally, the empirical model was presented from the simulation results.
Surface tension phenomena in the xylem sap of three diffuse porous temperate tree species
K. K. Christensen-Dalsgaard; M. T. Tyree; P. G. Mussone
2011-01-01
In plant physiology models involving bubble nucleation, expansion or elimination, it is typically assumed that the surface tension of xylem sap is equal to that of pure water, though this has never been tested. In this study we collected xylem sap from branches of the tree species Populus tremuloides, Betula papyrifera and Sorbus...
On the theory of type-I superconductor surface tension and twinning-plane-superconductivity
International Nuclear Information System (INIS)
Mishonov, T.M.
1990-01-01
A correction is found to the surface tension in type-I superconductors which is proportional to the square root of the Ginsburg-Landau parameter. This correction is essential for obtaining the phase diagram and other thermodynamical variables of the narrow superconducting layer arising near the twinning plane in some metals
Sresht, Vishnu; Lewandowski, Eric P; Blankschtein, Daniel; Jusufi, Arben
2017-08-22
A molecular modeling approach is presented with a focus on quantitative predictions of the surface tension of aqueous surfactant solutions. The approach combines classical Molecular Dynamics (MD) simulations with a molecular-thermodynamic theory (MTT) [ Y. J. Nikas, S. Puvvada, D. Blankschtein, Langmuir 1992 , 8 , 2680 ]. The MD component is used to calculate thermodynamic and molecular parameters that are needed in the MTT model to determine the surface tension isotherm. The MD/MTT approach provides the important link between the surfactant bulk concentration, the experimental control parameter, and the surfactant surface concentration, the MD control parameter. We demonstrate the capability of the MD/MTT modeling approach on nonionic alkyl polyethylene glycol surfactants at the air-water interface and observe reasonable agreement of the predicted surface tensions and the experimental surface tension data over a wide range of surfactant concentrations below the critical micelle concentration. Our modeling approach can be extended to ionic surfactants and their mixtures with both ionic and nonionic surfactants at liquid-liquid interfaces.
Relationship between surface tension and refractive index in binary non-electrolyte mixtures
International Nuclear Information System (INIS)
Acevedo, I.L.; Pedrosa, G.C.; Katz, M.
1990-01-01
Lorentz-Lorenz equation for molecular refraction has been combined with Sugden's parachor equation for binary non-electrolyte mixtures at 298.15 K. The obtained equation has been shown successful in calculating values of surface tensions, by measuring refractive indices of the binary mixtures at the same mole fractions. The estimated error decreases when the mixtures present possible isorefractives. (Author) [es
Surface tension and density of fusible metal melt with sulphur and selenium
International Nuclear Information System (INIS)
Najdich, Yu.V.; Krasovskij, Yu.P.; Chuvashov, Yu.N.
1990-01-01
Surface tension and density at 970 K have been determined for melts of Ga, In, Sn and Pb with S and Se. High surface activity of chalcogens in the melts has been found. A maximal adsorption of the active components and their ultimate surface activity that correlate with thermodinamical strength of the corresponding sulfides and selenides have been calculated
On Surface Tension for Compact Stars R. Sharma & S. D. Maharaj
Indian Academy of Sciences (India)
Abstract. In an earlier analysis it was demonstrated that general rel- ativity gives higher values of surface tension in strange stars with quark matter than neutron stars.We generate the modified Tolman–Oppenheimer–. Volkoff equation to incorporate anisotropic matter and use this to show that pressure anisotropy provides ...
Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited
International Nuclear Information System (INIS)
Mulero, A; Galan, C; Cuadros, F
2003-01-01
We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs
International Nuclear Information System (INIS)
Rahul Banerjee; Khan, M.; Mandal, L.K.; Roy, S.; Gupta, M.R.
2010-01-01
Complete text of publication follows. The Rayleigh-Taylor (R-T) instability and Richtmyer-Meshkov (R-M) instability are well known problems in the formation of some astrophysical structures such as the supernova remnants in the Eagle and Crab nebula. A core collapse supernova is driven by an externally powerful shock, and strong shocks are the breeding ground of hydrodynamic instability such as Rayleigh-Taylor instability or Richtmyer-Meshkov instability. These instabilities are also important issues in the design of targets for inertial confinement fusion (ICF). In an ICF target, a high density fluid is frequently accelerated by the pressure of a low density fluid and after ablation the density quickly decays. So, small ripples at such an interface will grow. Under potential flow model, the perturbed interface between heavier fluid and lighter fluid form bubble and spike like structures. The bubbles are in the form of columns of lighter fluid interleaved by falling spike of heavy fluid. In this paper, we like to presented the effect of viscosity and surface tension on Rayleigh-Taylor instability and Richtmyer-Meshkov instability under the non-linear Layzer's approach and described the displacement curvature, growth and velocity of the tip of the bubble as well as spike. It is seen that, in absence of surface tension the lowering of the asymptotic velocity of the tip of the bubble which is formed when the lighter fluid penetrates into the denser fluid and thus encounters the viscous drag due to the denser fluid, which depends only on the denser fluid's viscosity coefficient. On the other hand the asymptotic velocity of the tip of the spike formed as the denser fluid penetrates into the lighter fluid is reduced by an amount which depends only on the viscosity coefficient of the lighter fluid and the spike is resisted by the viscous drag due to the lighter fluid. However, in presence of surface tension the asymptotic velocity of the tip of the bubble (spike) and
Czech Academy of Sciences Publication Activity Database
Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav
2015-01-01
Roč. 406, November (2015), s. 181-193 ISSN 0378-3812 R&D Projects: GA ČR GA13-00145S Institutional support: RVO:61388998 Keywords : ionic liquid * surface tension-temperature relation * density -temperature relation * cyano-funcionalized anion Subject RIV: BJ - Thermodynamics Impact factor: 1.846, year: 2015
International Nuclear Information System (INIS)
Cheng, Wen-long; Yuan, Shuai; Song, Jia-liang
2014-01-01
PTC (positive temperature coefficient) material is a kind of thermo-sensitive material. In this study, a series of novel PTC materials adapted to thermal control of electron devices are prepared. By adding different low-melting-point blend matrixes into GP (graphite powder)/LDPE (low density polyethylene) composite, the Curie temperatures are adjusted to 9 °C, 25 °C, 34 °C and 41 °C, and the resistance–temperature coefficients are enhanced to 1.57/°C–2.15/°C. These PTC materials remain solid in the temperature region of PTC effect, which makes it possible to be used as heating element to achieve adaptive temperature control. In addition, the adaptive thermal control performances of this kind of materials are investigated both experimentally and theoretically. The result shows that the adaptive effect becomes more significant while the resistance–temperature coefficient increases. A critical heating power defined as the initial heating power which makes the equilibrium temperature reach terminal temperature is presented. The adaptive temperature control will be effective only if the initial power is below this value. The critical heating power is determined by the Curie temperature and resistance–temperature coefficient of PTC materials, and a higher Curie temperature or resistance–temperature coefficient will lead to a larger critical heating power. - Highlights: • A series of novel PTC (positive temperature coefficient) materials were prepared. • The Curie point of PTC material can be adjusted by choosing different blend matrixes. • The resistance–temperature coefficient of PTC materials is enhanced to 2.15/°C. • The material has good adaptive temperature control ability with no auxiliary method. • A mathematical model is established to analyze the performance and applicability
Energy Technology Data Exchange (ETDEWEB)
Pazirandeh, Ali [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Science and Research Branch; Hooshyar Mobaraki, Almas
2017-07-15
The safe operation of a reactor is based on feedback models. In this paper we attempted to discuss the influence of a non-uniform radial temperature distribution on the fuel rod temperature coefficient of reactivity. The paper demonstrates that the neutron properties of a reactor core is based on effective temperature of the fuel to obtain the correct fuel temperature feedback. The value of volume-averaged temperature being used in the calculations of neutron physics with feedbacks would result in underestimating the probable event. In the calculation it is necessary to use the effective temperature of the fuel in order to provide correct accounting of the fuel temperature feedback. Fuel temperature changes in different zones of the core and consequently reactivity coefficient change are an important parameter for analysis of transient conditions. The restricting factor that compensates the inserted reactivity is the temperature reactivity coefficient and effective delayed neutron fraction.
Some remarks on the solid surface tension determination from contact angle measurements
Energy Technology Data Exchange (ETDEWEB)
Zdziennicka, Anna; Szymczyk, Katarzyna; Krawczyk, Joanna; Jańczuk, Bronisław, E-mail: bronislaw.janczuk@poczta.umcs.lublin.pl
2017-05-31
Graphical abstract: Surface tension of PE, nylon 6 and quartz from different approaches to the interface tension. - Highlights: • New values of water and formamide surface tension components were established. • Quartz surface tension depends on its crystal face. • Usefulness of different approaches for solid surface tension determination was tested. - Abstract: The measurements of water, formamide and diiodomethane contact angle (θ) on polytetrafluoroethylene (PTFE), polyethylene (PE), polymethyl methacrylate (PMMA), nylon 6, quartz and silica were performed. Based on the θ values of these liquids obtained on PTFE, the Lifshitz-van der Waals and acid-base and/or dispersion and polar components of their surface tension (ST) were determined. In turn, the θ values for water, formamide and diiodomethane on PMMA were applied to calculate the electron-acceptor and electron-donor parameters of the Lewis acid-base component of the formamide ST. For this calculation the same values of the electron-acceptor and electron-donor parameters for water ST were used. Taking into account the values of components and parameters of water, formamide and diiodomethane ST obtained by us, van Oss et al. and from the water(formamide)-n-alkane and water-diiodomethane interface tension, the components and parameters of studied solids ST were calculated. To this end different approaches to the interface tension were considered. The obtained values were compared with those in the literature. It was concluded that for determination of solid ST components and parameters, those of water, formamide and diiodomethane ST obtained from the θ measurements on the model solids should be used.
Kremer, J.; Kilzer, A.; Petermann, M.
2018-01-01
Oscillations of small liquid drops around a spherical shape have been of great interest to scientists measuring physical properties such as interfacial tension and viscosity, over the last few decades. A powerful tool for contactless positioning is acoustic levitation, which has been used to simultaneously determine the surface tension and viscosity of liquids at ambient pressure. In order to extend this acoustic levitation measurement method to high pressure systems, the method is first evaluated under ambient pressure. To measure surface tension and viscosity using acoustically levitated oscillating drops, an image analysis method has to be developed and factors which may affect measurement, such as sound field or oscillation amplitude, have to be analyzed. In this paper, we describe the simultaneous measurement of surface tension and viscosity using freely decaying shape oscillations of acoustically levitated droplets of different liquids (silicone oils AK 5 and AK 10, squalane, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) in air. These liquids vary in viscosity from 2 to about 30 mPa s. An acoustic levitation system, including an optimized standing wave acoustic levitator and a high-speed camera, was used for this study. An image analysis was performed with a self-written Matlab® code. The frequency of oscillation and the damping constant, required for the determination of surface tension and viscosity, respectively, were calculated from the evolution of the equatorial and polar radii. The results and observations are compared to data from the literature in order to analyze the accuracy of surface tension and viscosity determination, as well as the effect of non-spherical drop shape or amplitude of oscillation on measurement.
Temperature dependence of transport coefficients of 'simple liquid ...
African Journals Online (AJOL)
... has been investigated. The study carried out at two densities, r* = 0.60 and r* = 0.95. Result shows erratic variations of the shear viscosity in the two lattices structures. KeyWords: Temperature effect, face centred, simple cubic, transport properties, simple liquid. [Global Jnl Pure & Appl. Sci. Vol.9(3) 2003: 403-406] ...
International Nuclear Information System (INIS)
Newman, D.F.; Leonard, B.R. Jr.; Trapp, T.J.; Gore, B.F.; Kottwitz, D.A.; Thompson, J.K.; Purcell, W.L.; Stewart, K.B.
1977-05-01
A comparison of calculated and measured neutron multiplication factors as a function of temperature was made for three graphite-moderated lattices in the High Temperature Lattice Test Reactor (HTLTR) using 233 UO 2 --ThO 2 fuels in varying amounts and configurations. Correlation of neutronic analysis methods and cross section data with the experimental measurements forms the basis for assessing the accuracy of the methods and data and developing confidence in the ability to predict the temperature coefficient of reactivity for various High Temperature Gas-Cooled Reactor (HTGR) conditions in which 233 U and thorium are present in the fuel. The calculated values of k/sub infinity/(T) were correlated with measured values using two least-squares-fitted correlation coefficients: (1) a normalization factor, and (2) a temperature coefficient bias factor. These correlations indicate the existence of a negative (nonconservative) bias in temperature coefficients of reactivity calculated using ENDF/B-IV cross section data
Temperature and Doppler coefficients of various space nuclear reactors
International Nuclear Information System (INIS)
Mughabghab, S.F.; Ludewig, H. Schmidt, E.
1993-01-01
Temperature and Doppler feedback effects for a Particle Bed Reactor (PBR) designed to operate as a propulsion reactor are investigated. Several moderator types and compositions fuel enrichments and reactor sizes are considered in this study. From this study it could be concluded that a PBR can be configured which has a negative prompt feedback, zero coolant worth, and a small positive to zero moderator worth. This reactor would put the lowest demands on the control system
Temperature and Doppler Coefficients of Various Space Nuclear Reactors
Mughabghab, Said F.; Ludewig, Hans; Schmidt, Eldon
1994-07-01
Temperature and Doppler feedback effects for a Particle Bed Reactor (PBR) designed to operate as a propulsion reactor are investigated. Several moderator types and compositions fuel enrichments and reactor sizes are considered in this study. From this study it could be concluded that a PBR can be configured which has a negative prompt feedback, zero coolant worth, and a small positive to zero moderator worth. This reactor would put the lowest demands on the control system.
Monitoring of the temperature reactivity coefficient at the PWR nuclear plant
International Nuclear Information System (INIS)
Kostic, Lj.
1996-01-01
For monitoring temperature coefficient of reactivity of pressurized water reactor a method based on the correction of fluctuation in signals of i-core neutron detectors and core-exit thermocouples and neural network paradigm is used it is shown that the moderator temperature coefficient of relativity can be predicted with the aid of the back propagation neural network technique by measuring the frequency response function between the in-core neutron flux and the core-exit coolant temperature
Tong, Jing; Yang, Hong-Xu; Liu, Ru-Jing; Li, Chi; Xia, Li-Xin; Yang, Jia-Zhen
2014-11-13
With the use of isothermogravimetrical analysis, the enthalpies of vaporization, Δ(g)lH(o)m(T(av)), at the average temperature, T(av) = 445.65 K, for the ionic liquids (ILs) 1-alkyl-3-methylimidazolium propionate [C(n)mim][Pro](n = 4, 5, 6) were determined. Using Verevkin's method, the difference of heat capacities between the vapor phase and the liquid phase, Δ(g)lC(p)(o)m, for [C(n)mim][Pro](n = 2, 3, 4, 5, 6), were calculated based on the statistical thermodynamics. Therefore, with the use of Δ(g)lC(p)(o)m, the values of Δ(g)lH(o)m(T(av)) were transformed into Δ(g)lH(o)m(298), 126.8, 130.3, and 136.5 for [C(n)mim][Pro](n = 4, 5, 6), respectively. In terms of the new scale of polarity for ILs, the order of the polarity of [C(n)mim][Pro](n = 2, 3, 4, 5, 6) was predicted, that is, the polarity decreases with increasing methylene. A new model of the relationship between the surface tension and the enthalpy of vaporization for aprotic ILs was put forward and used to predict the surface tension for [C(n)mim][Pro](n = 2, 3, 4, 5, 6) and others. The predicted surface tension for the ILs is in good agreement with the experimental one.
International Nuclear Information System (INIS)
Tokuhara, K.; Nakata, T.; Murata, I.; Yamashita, K.; Shindo, R.
1991-01-01
This report describes the calculational methods which were employed to determine the temperature coefficients and the kinetic parameters for the safety analysis in the HTTR (High Temperature Engineering Test Reactor). The temperature coefficients (doppler, moderator temperature) and the kinetic parameters (prompt neutron life time; l, effective delayed neutron fraction; β eff) are important for the point model core dynamic analysis and should be evaluated properly. The temperature coefficients were calculated by the whole core model. Doppler coefficient was evaluated under the conditions of all control rods withdrawn and the uniform change of fuel temperature. The minimum and the maximum value of the evaluated doppler coefficients in a burnup cycle are -4.6x10 -5 and -1.5x10 -5 ΔK/K/deg. C respectively. The moderator temperature coefficient was evaluated under the conditions of all control rods withdrawn and the uniform change of moderator temperature. The minimum and the maximum value of the evaluated moderator temperature coefficients in a burnup cycle are -17.1x10 -5 and 0.99x10 -5 ΔK/K/deg. C respectively. In spite of positive moderator temperature coefficient, the power coefficient is always negative. Therefore the HTTR possesses inherent power-suppressing feed back characteristic in all operating condition. We surveyed the effects of the Xe existence, the control rods existence, the fuel temperature and the region in which the temperature was changed on the moderator temperature coefficients. The kinetic parameters were calculated by the perturbation method with the whole core model. The minimum and the maximum value of the evaluated effective delayed neutron fraction (β eff) are 0.0047 and 0.0065 respectively. These of the evaluated prompt neutron life time (l) are 0.67 and 0.78 ms respectively. We have surveyed the effects of the fuel depletion and the core power level on these parameters, and considered these effects on the kinetic parameters. From
International Nuclear Information System (INIS)
Wang Dongsheng; Wang Jinglan
2003-01-01
The good linear relationship with significance level α = 0.01 exists between isotope in precipitation and surface air temperature with multi-year average in 32 stations of China, and the yearly δD-temperature coefficient = 3.1‰/1℃ and the yearly δ 18 O-temperature coefficient = 0.36‰/1℃, and its determination coefficient R 2 = 0.67 and 0.64 respectively. So the isotope-temperature coefficient with yearly average can serve as the temperature yearly measure. But the monthly average isotope-temperature coefficient in each station is variable according to both of space and time, and its repeatability is determined by the meteorological regimes. According to the monthly isotope-temperature coefficient (B) and the coefficient of determination (R 2 ) and its α, all of China can be zoned the following three belts: (1) In the North Belt, B>O, R 2 ≈ 0.3-0.65, α = 0.01, the relation between monthly isotope in precipitation and surface air temperature (RMIT) belongs to a direct correlation and is closer in 99% probability; (2) In the South Belt, B
Transport coefficients in high-temperature ionized air flows with electronic excitation
Istomin, V. A.; Oblapenko, G. P.
2018-01-01
Transport coefficients are studied in high-temperature ionized air mixtures using the modified Chapman-Enskog method. The 11-component mixture N2/N2+/N /N+/O2/O2+/O /O+/N O /N O+/e- , taking into account the rotational and vibrational degrees of freedom of molecules and electronic degrees of freedom of both atomic and molecular species, is considered. Using the PAINeT software package, developed by the authors of the paper, in wide temperature range calculations of the thermal conductivity, thermal diffusion, diffusion, and shear viscosity coefficients for an equilibrium ionized air mixture and non-equilibrium flow conditions for mixture compositions, characteristic of those in shock tube experiments and re-entry conditions, are performed. For the equilibrium air case, the computed transport coefficients are compared to those obtained using simplified kinetic theory algorithms. It is shown that neglecting electronic excitation leads to a significant underestimation of the thermal conductivity coefficient at temperatures higher than 25 000 K. For non-equilibrium test cases, it is shown that the thermal diffusion coefficients of neutral species and the self-diffusion coefficients of all species are strongly affected by the mixture composition, while the thermal conductivity coefficient is most strongly influenced by the degree of ionization of the flow. Neglecting electronic excitation causes noticeable underestimation of the thermal conductivity coefficient at temperatures higher than 20 000 K.
Directory of Open Access Journals (Sweden)
Maria de Fátima Carvalho Costa
1998-06-01
Full Text Available Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac of polymer-surfactant complexes and the critical micellar concentration (cmc of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS mixtures, solutions containing poly(ethylene oxide-SDS, poly(vinylpyrrolidone-SDS and poly(acrylic acid-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.
Light Meets Water in Nonlocal Media: Surface Tension Analogue in Optics
Horikis, Theodoros P.; Frantzeskakis, Dimitrios J.
2017-06-01
Shallow water wave phenomena find their analogue in optics through a nonlocal nonlinear Schrödinger (NLS) model in 2 +1 dimensions. We identify an analogue of surface tension in optics, namely, a single parameter depending on the degree of nonlocality, which changes the sign of dispersion, much like surface tension does in the shallow water wave problem. Using multiscale expansions, we reduce the NLS model to a Kadomtsev-Petviashvili (KP) equation, which is of the KPII (KPI) type, for strong (weak) nonlocality. We demonstrate the emergence of robust optical antidark solitons forming Y -, X -, and H -shaped wave patterns, which are approximated by colliding KPII line solitons, similar to those observed in shallow waters.
International Nuclear Information System (INIS)
Sun Zhongguo; Xi Guang; Chen Xi
2009-01-01
The binary collision of liquid droplets is of both practical importance and fundamental value in computational fluid mechanics. We present a modified surface tension model within the moving particle semi-implicit (MPS) method, and carry out two-dimensional simulations to investigate the mechanisms of coalescence and separation of the droplets during binary collision. The modified surface tension model improves accuracy and convergence. A mechanism map is established for various possible deformation pathways encountered during binary collision, as the impact speed is varied; a new pathway is reported when the collision speed is critical. In addition, eccentric collisions are simulated and the effect of the rotation of coalesced particle is explored. The results qualitatively agree with experiments and the numerical protocol may find applications in studying free surface flows and interface deformation
On the Problem of Determining Aggregation Numbers from Surface Tension Measurements.
Rusanov, Anatoly I
2017-11-07
In view of the recent discovery of variable aggregation numbers in the vicinity of the critical micelle concentration (CMC), the mass-action-law theory of the surface tension isotherm of a micellar solution with variable aggregation numbers is formulated both for nonionic and ionic surfactants. It is shown that the shape of the surface tension isotherm should be concave in the logarithmic scale above the CMC. Considering a change in the isotherm slope at the CMC apparent break point, the problems of determining the aggregation number for nonionic micelles and the degree of counterion binding for ionic micelles are discussed. In case of the aggregation number variability near the CMC, finding the aggregation number above the CMC apparent break point is considered and a computational scheme is elaborated, requiring a higher precision for experiment. Some experimental data from the literature are analyzed, and the method of estimating the degree of counterion binding is improved.
Theory of the surface dipole layer and of surface tension in liquids of charged particles
International Nuclear Information System (INIS)
Senatore, G.; Tosi, M.P.
1980-01-01
The problem of the surface density profiles and of the surface tension of a two-component liquid of charged particles in equilibrium with its vapour is examined. The exact equilibrium conditions for the profiles are given in terms of the inverse response functions of the inhomogeneous fluid, and alternative exact expressions for the surface tension are derived. The use of a density gradient expansion reduces the problem to knowledge of properties of a homogeneous charged fluid on a uniform neutralizing background, in which the total particle density and the charge density are independent variables. Additional simplifications are discussed for special cases for which a perturbative treatment of the surface charge density profile can be developed, and in particular for nearly symmetric ionic liquids and for simple liquid metals. (author)
A waveless free surface flow past a submerged triangular obstacle in presence of surface tension
Directory of Open Access Journals (Sweden)
Hakima Sekhri
2016-07-01
Full Text Available We consider the Free surface flows passing a submerged triangular obstacle at the bottom of a channel. The problem is characterized by a nonlinear boundary condition on the surface of unknown configuration. The analytical exact solutions for these problems are not known. Following Dias and Vanden Broeck [6], we computed numerically the solutions via a series truncation method. These solutions depend on two parameters: the Weber number $\\alpha$ characterizing the strength of the surface tension and the angle $\\beta$ at the base characterizing the shape of the apex. Although free surface flows with surface tension admit capillary waves, it is found that solution exist only for values of the Weber number greater than $\\alpha_0$ for different configurations of the triangular obstacle.
Schroeder, Craig
2012-02-01
We present a method for applying semi-implicit forces on a Lagrangian mesh to an Eulerian discretization of the Navier Stokes equations in a way that produces a sparse symmetric positive definite system. The resulting method has semi-implicit and fully-coupled viscosity, pressure, and Lagrangian forces. We apply our new framework for forces on a Lagrangian mesh to the case of a surface tension force, which when treated explicitly leads to a tight time step restriction. By applying surface tension as a semi-implicit Lagrangian force, the resulting method benefits from improved stability and the ability to take larger time steps. The resulting discretization is also able to maintain parasitic currents at low levels. © 2011.
Corsetti, James A.; Green, William E.; Ellis, Jonathan D.; Schmidt, Greg R.; Moore, Duncan T.
2017-01-01
A system combining an interferometer with an environmental chamber for measuring both coefficient of thermal expansion (CTE) and temperature-dependent refractive index (dn/dT) simultaneously is presented. The operation and measurement results of this instrument are discussed.
Positive Temperature Coefficient of Breakdown Voltage in 4H-SiC PN Junction Rectifiers
National Research Council Canada - National Science Library
Neudeck, Philip
1998-01-01
...-suited SiC polytype for power device implementation. This paper reports the first experimental measurements of stable positive temperature coefficient behavior observed in 4H-SiC pn junction rectifiers...
Chapter 10: Calculation of the temperature coefficient of reactivity of a graphite-moderated reactor
International Nuclear Information System (INIS)
Brown, G.; Richmond, R.; Stace, R.H.W.
1963-01-01
The temperature coefficients of reactivity of the BEPO, Windscale and Calder reactors are calculated, using the revised methods given by Lockey et al. (1956) and by Campbell and Symonds (1962). The results are compared with experimental values. (author)
Invar hardening under keeping of low values of temperature coefficient of linear expansion
International Nuclear Information System (INIS)
Bashnin, Yu.A.; Shiryaeva, A.N.; Omel'chenko, A.V.
1982-01-01
Complex invar alloying with chromium, zirconium and nitrogen is conducted for increasing hardness and assuring low values of the temperature coefficient of linear expansion. It is shown that alloying with nitride-forming elements-chromium, zirconium and the following high-temperature saturation under high pressure with nitrogen provides the invar hardening at assuring a low temperature coefficient of linear expansion. Saturation with nitrogen under 100 MPa pressure at 1050 deg C during 3 hours permits to prepare an invar containing up to 0.2% N 2 uniformly distributed over the whole cross section of samples with 4 mm diameter. Nitrogen in invar alloys alloyed with chromium and zirconium affects the Curie point similarly to carbon and nickel shifting it towards higher temperatures, it slightly changes the value of the temperature coefficient of linear expansion and provides linear character of thermal expansion dependence on temperature in the +100 deg C - -180 deg C range
A finite-density calculation of the surface tension of isotropic-nematic interfaces
International Nuclear Information System (INIS)
Moore, B.G.; McMullen, W.E.
1992-01-01
The surface tension of the isotropic-nematic interface in a fluid of intermediate-sized hard particles is studied and calculated. The transition from isotropic to nematic is fixed to occur in a continuous fashion by varying the biaxiality of the model particles. A reversal in the preferred orientation of the bulk nematic relative to the isotropic-nematic interface suggests an oblique orientation of the bulk nematic. 32 refs., 8 figs
Single-Step Fabrication of High-Density Microdroplet Arrays of Low-Surface-Tension Liquids.
Feng, Wenqian; Li, Linxian; Du, Xin; Welle, Alexander; Levkin, Pavel A
2016-04-01
A facile approach for surface patterning that enables single-step fabrication of high-density arrays of low-surface-tension organic-liquid microdroplets is described. This approach enables miniaturized and parallel high-throughput screenings in organic solvents, formation of homogeneous arrays of hydrophobic nanoparticles, polymer micropads of specific shapes, and polymer microlens arrays. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Kato, H.; Chen, H.-S.; Inoue, A.
2008-01-01
The thermal expansion coefficients of 13 metallic glasses were measured using a thermo-mechanical analyser. A unique correlation was found between the linear thermal expansion coefficient and the glass transition temperature-their product is nearly constant ∼8.24 x 10 -3 . If one assumes the Debye expression for thermal activation, the total linear thermal expansion up to glass transition temperature (T g ) is reduced to 6 x 10 -3 , nearly 25% of that at the fusion of pure metals
Energy Technology Data Exchange (ETDEWEB)
Mounier, C.
1994-05-01
In this work, we looked for the error sources in the calculation of the isothermal temperature coefficient for light water lattices. We studied three fields implied: the nuclear data, the calculation methods and the temperature coefficient measurement. About the measurement, we pointed out the difficulties of he interpretation. So we used an indirect approach by the mean of critical states at various temperatures. In that way, we can say that if the errors in the effective multiplication factor are constants with temperature then the temperature coefficient is correctly calculated. We studied the neutronic influence of light water models which are used in the thermal scattering cross-section computation. This cross-section determines the thermalization process of neutrons. We showed that the actual model (JEF2) is satisfactory of the needs of the reactors physics. Concerning the majors isotopes ({sup 235}U, {sup 238}U, {sup 239}Pu), the uncertainties on the nuclear data do not seem as a preponderant cause of errors, without to be totally negligible. We also studied, with the neutron transport code Apollo-2, the influence of difference approximations for cell calculation . The new possibilities of the code has been used to represent the critical experiments, particularly the improvement of the resonance self-shielding formalism. The calculation scheme adopted permits to remove partially the fundamental mode approximation by the mean of a two-dimensional transport calculation with the SN method, the axial leakage being treated as an absorption in DB{sup 2}{sub Z}. The agreement between theory and experiment is good both for the reactivity and the temperature coefficient. (author). 114 refs., 40 figs., 163 tabs., 1 append.
Effect of liquid surface tension on circular and linear hydraulic jumps; theory and experiments
Bhagat, Rajesh Kumar; Jha, Narsing Kumar; Linden, Paul F.; Wilson, David Ian
2017-11-01
The hydraulic jump has attracted considerable attention since Rayleigh published his account in 1914. Watson (1964) proposed the first satisfactory explanation of the circular hydraulic jump by balancing the momentum and hydrostatic pressure across the jump, but this solution did not explain what actually causes the jump to form. Bohr et al. (1992) showed that the hydraulic jump happens close to the point where the local Froude number equals to one, suggesting a balance between inertial and hydrostatic contributions. Bush & Aristoff (2003) subsequently incorporated the effect of surface tension and showed that this is important when the jump radius is small. In this study, we propose a new account to explain the formation and evolution of hydraulic jumps under conditions where the jump radius is strongly influenced by the liquid surface tension. The theory is compared with experiments employing liquids of different surface tension and different viscosity, in circular and linear configurations. The model predictions and the experimental results show excellent agreement. Commonwealth Scholarship Commission, St. John's college, University of Cambridge.
Surface tension and wetting properties of rapeseed oil to biofuel conversion by-products
Muszyński, Siemowit; Sujak, Agnieszka; Stępniewski, Andrzej; Kornarzyński, Krzysztof; Ejtel, Marta; Kowal, Natalia; Tomczyk-Warunek, Agnieszka; Szcześniak, Emil; Tomczyńska-Mleko, Marta; Mleko, Stanisław
2018-04-01
This work presents a study on the surface tension, density and wetting behaviour of distilled glycerol, technical grade glycerol and the matter organic non-glycerin fraction. The research was conducted to expand the knowledge about the physical properties of wastes from the rapeseed oil biofuel production. The results show that the densities of technical grade glycerol (1.300 g cm-3) and distilled glycerol (1.267 g cm-3) did not differ and were significantly lower than the density of the matter organic non-glycerin fraction (1.579 g cm-3). Furthermore, the surface tension of distilled glycerol (49.6 mN m-1) was significantly higher than the matter organic non-glycerin fraction (32.7 mN m-1) and technical grade glycerol (29.5 mN m-1). As a result, both technical grade glycerol and the matter organic non-glycerin fraction had lower contact angles than distilled glycerol. The examined physical properties of distilled glycerol were found to be very close to that of the commercially available pure glycerol. The results suggest that technical grade glycerol may have potential application in the production of glycerol/fuel blends or biosurfactants. The presented results indicate that surface tension measurements are more useful when examining the quality of biofuel wastes than is density determination, as they allow for a more accurate analysis of the effects of impurities on the physical properties of the biofuel by-products.
International Nuclear Information System (INIS)
Evans, R.; Kumaravadivel, R.
1976-01-01
A simple scheme for determining the ion density profile and the surface tension of a liquid metal is described. Assuming that the interaction between metallic pseudo-ions is of the form introduced by Evans, an approximate expression for the excess free energy of the system is derived using the thermodynamic perturbation theory of Weeks, Chandler and Anderson. This excess free energy is then minimized with respect to a parameter which specifies the ion density profile, and the surface tension is given directly. From a consideration of the dependence of the interionic forces on the electron density it is predicted that the ions should take up a very steep density profile at the liquid metal surface. This behaviour is contrasted with that to be expected for rare-gas fluids in which the interatomic forces are density-independent. The values of the surface tension calculated for liquid Na, K and Al from a simplified version of the theory are in reasonable agreement with experiment. (author)
Novel method for the simultaneous estimation of density and surface tension of liquids
International Nuclear Information System (INIS)
Thirunavukkarasu, G.; Srinivasan, G.J.
2003-01-01
The conventional Hare's apparatus generally used for the determination of density of liquids has been modified by replacing its vertical arms (glass tubes) with capillary tubes of 30 cm length and 0.072 cm diameter. When the columns of liquids are drawn through the capillary tubes with reduced pressure at the top of the liquid columns and kept at equilibrium with the atmospheric pressure acting on the liquid surface outside the capillary tubes, the downward pressure due to gravity of the liquid columns has to be coupled with the pressure arising due to the effect of surface tension of the liquids. A fresh expression for the density and surface tension of liquids has been arrived at while equating the pressure balancing system for the two individual liquid columns of the modified Hare's apparatus. The experimental results showed that the proposed method is precise and accurate in the simultaneous estimation of density and surface tension of liquids, with an error of less than 5%
Amrhein, Sven; Bauer, Katharina Christin; Galm, Lara; Hubbuch, Jürgen
2015-12-01
The surface hydrophobicity of a protein is an important factor for its interactions in solution and thus the outcome of its production process. Yet most of the methods are not able to evaluate the influence of these hydrophobic interactions under natural conditions. In the present work we have established a high resolution stalagmometric method for surface tension determination on a liquid handling station, which can cope with accuracy as well as high throughput requirements. Surface tensions could be derived with a low sample consumption (800 μL) and a high reproducibility (content. The protein influence on the solutions' surface tension was correlated to the hydrophobicity of lysozyme, human lysozyme, BSA, and α-lactalbumin. Differences in proteins' hydrophobic character depending on pH and species could be resolved. Within this work we have developed a pH dependent hydrophobicity ranking, which was found to be in good agreement with literature. For the studied pH range of 3-9 lysozyme from chicken egg white was identified to be the most hydrophilic. α-lactalbumin at pH 3 exhibited the most pronounced hydrophobic character. The stalagmometric method occurred to outclass the widely used spectrophotometric method with bromophenol blue sodium salt as it gave reasonable results without restrictions on pH and protein species. © 2015 Wiley Periodicals, Inc.
The behavior of surface tension on steady-state rotating fluids in the low gravity environments
Hung, R. J.; Leslie, Fred W.
1987-01-01
The effect of surface tension on steady-state rotating fluids in a low gravity environment is studied. All the values of the physical parameters used in these calculations, except in the low gravity environments, are based on the measurements carried out by Leslie (1985) in the low gravity environment of a free-falling aircraft. The profile of the interface of two fluids is derived from Laplace's equation relating the pressure drop across an interface to the radii of curvature which has been applied to a low gravity rotating bubble that contacts the container boundary. The interface shape depends on the ratio of gravity to surface tension forces, the ratio of centrifugal to surface tension forces, the contact radius of the interface to the boundary, and the contact angle. The shape of the bubble is symmetric about its equator in a zero-gravity environment. This symmetry disappears and gradually shifts to parabolic profiles as the gravity environment becomes non-zero. The location of the maximum radius of the bubble moves upward from the center of the depth toward the top boundary of the cylinder as gravity increases. The contact radius of interface to the boundary r0 at the top side of cylinder increases and r0 at the bottom side of the cylinder decreases as the gravity environment increases from zero to 1 g.
Analytical description of concentration dependence of surface tension in multicomponent systems
Energy Technology Data Exchange (ETDEWEB)
Dadashev, R; Kutuev, R [Complex Science Research Institute of the Science Academy of the Chechen Republic, 21 Staropromisl. shosse, Grozny 364096 (Russian Federation); Elimkhanov, D [Science Academy of the Chechen Republic (Russian Federation)], E-mail: edzhabrail@mail.ru
2008-02-15
From the basic fundamental thermodynamic expressions the equation of isotherms of the surface tension of a ternary system is received. Various assumptions concerning the concentration dependence of molar areas are usually made when the equation is derived. The dependence of the molar areas is calculated as an additive function of the structure of a volumetric phase or the structure of a surface layer. To define the concentration dependence of the molar areas we used a stricter thermodynamic expression offered by Butler. In the received equation the dependence of molar areas on the structure of the solution is taken into account. Therefore, the equation can be applied for the calculation of surface tension over a wide concentration range of the components. Unlike the known expressions, the equation includes the surface tension properties of lateral binary systems, which makes the accuracy of the calculated values considerably higher. Thus, among the advantages of the offered equation we can point out the mathematical simplicity of the received equation and the fact that the equation includes physical parameters the experimental definition of which does not present any special difficulties.
Two Surface-Tension Formulations For The Level Set Interface-Tracking Method
International Nuclear Information System (INIS)
Shepel, S.V.; Smith, B.L.
2005-01-01
The paper describes a comparative study of two surface-tension models for the Level Set interface tracking method. In both models, the surface tension is represented as a body force, concentrated near the interface, but the technical implementation of the two options is different. The first is based on a traditional Level Set approach, in which the surface tension is distributed over a narrow band around the interface using a smoothed Delta function. In the second model, which is based on the integral form of the fluid-flow equations, the force is imposed only in those computational cells through which the interface passes. Both models have been incorporated into the Finite-Element/Finite-Volume Level Set method, previously implemented into the commercial Computational Fluid Dynamics (CFD) code CFX-4. A critical evaluation of the two models, undertaken in the context of four standard Level Set benchmark problems, shows that the first model, based on the smoothed Delta function approach, is the more general, and more robust, of the two. (author)
On the modelling of semi-insulating GaAs including surface tension and bulk stresses
Energy Technology Data Exchange (ETDEWEB)
Dreyer, W.; Duderstadt, F.
2004-07-01
Necessary heat treatment of single crystal semi-insulating Gallium Arsenide (GaAs), which is deployed in micro- and opto- electronic devices, generate undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid/solid interface and deviatoric stresses in the solid. The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant-Kirchhoff law which gives an appropriate stress/strain relation for many solids in the small strain regime. We establish criteria, which allow the correct replacement of the St. Venant-Kirchhoff law by the simpler Hooke law. The main objectives of this study are: (i) We develop a thermo-mechanical model that describes diffusion and interface motion, which both are strongly influenced by surface tension effects and deviatoric stresses. (ii) We give an overview and outlook on problems that can be posed and solved within the framework of the model. (iii) We calculate non-standard phase diagrams, i.e. those that take into account surface tension and non-deviatoric stresses, for GaAs above 786 C, and we compare the results with classical phase diagrams without these phenomena. (orig.)
Temperature and current coefficients of lasing wavelength in tunable diode laser spectroscopy.
Fukuda, M; Mishima, T; Nakayama, N; Masuda, T
2010-08-01
The factors determining temperature and current coefficients of lasing wavelength are investigated and discussed under monitoring CO(2)-gas absorption spectra. The diffusion rate of Joule heating at the active layer to the surrounding region is observed by monitoring the change in the junction voltage, which is a function of temperature and the wavelength (frequency) deviation under sinusoidal current modulation. Based on the experimental results, the time interval of monitoring the wavelength after changing the ambient temperature or injected current (scanning rate) has to be constant at least to eliminate the monitoring error induced by the deviation of lasing wavelength, though the temperature and current coefficients of lasing wavelength differ with the rate.
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
International Nuclear Information System (INIS)
Volkov, A.G.; Kortov, S.V.; Povzner, A.A.
1996-01-01
The low temperature measurements of thermal coefficient of linear expansion of strong paramagnet FeSi are carried out. The results obtained are discussed with in the framework of spin-fluctuation theory. It is shown that electronic part of the thermal coefficient of linear expansion is negative in the range of temperatures lower that of the semiconductor-metal phase transition. In metal phase it becomes positive. This specific features of the thermal coefficient is explained by the spin-fluctuation renormalization of d-electronic states density
Energy Technology Data Exchange (ETDEWEB)
Raisic, N; Strugar, P; Dobrosavljevic, N [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)
1961-12-15
Temperature reactivity coefficient of the RA reactor was determined as follows. Stabilization of moderator temperature and graphite reflector was achieved in the reactor operated at power levels of 20, 100, 500, 1000, 3000 and 5000 kW. Temperature change of the moderator was achieved by changing the water flow rate in the secondary cooling system. The fuel temperature was changed simultaneously. During the measurement at each power level the temperature change was between 30 - 50 deg C. Changing the position of the automated regulator is registered during moderator temperature change, and these changes were used for determining the total reactivity change by using the calibration curves for the automated regulator. In the measured temperature range the the reactivity change was linear and it was possible to determine the total temperature coefficient.
NdFeB magnets with zero temperature coefficient of induction
International Nuclear Information System (INIS)
Ma, B.M.; Narasimhan, K.S.V.L.; Hurt, J.C.
1986-01-01
Temperature compensation for the induction of NdFeB type magnets has been investigated. A computer assisted alloy selection method was adopted to identify composition of zero temperature coefficient of induction over -50 to 200 0 C. Selected alloys were processed into magnet by the conventional powder metallurgy method. The experimental temperature coefficient on the sintered magnet correlated with the prediction satisfactory. Holmium is an essential ingredient required for temperature compensation of NdFeB magnets. A magnet, (Nd/sub 0.23/Ho/sub 0.64/Dy/sub 0.13/)/sub 15/Fe/sub 79/B/sub 6/ with B/sub r/ of 7,700 Gauss, H/sub c/ of 7,700 Oe, H/sub ci/ of 20,600 Oe, Bh/sub max/ of 14.8 MGOe and temperature coefficient of -0.029% per 0 C over -50 to +150 was obtained
Directory of Open Access Journals (Sweden)
M. Živković
2016-12-01
Full Text Available Experimental investigations static coefficient of friction in lubricated conditions and pre-heating of the sample pin at high temperatures is discussed in this paper. The static coefficient of friction was measured in the sliding steel copper pins per cylinder of polyvinylchloride. Pins are previously heated in a special chamber from room temperature to a temperature of 800 oC with a step of 50 °C. Tribological changes in the surface layer of the pins caused by pre-heating the pins at high temperatures and cooling systems have very significantly influenced the increase in the coefficient of static friction. The results indicate the possibility of improving the friction characteristics of metal materials based on their thermal treatment at elevated temperatures.
The Merkel coefficient and its dependence on the temperature position of the cooling tower process
International Nuclear Information System (INIS)
Klenke, W.
1977-01-01
The Merkel coefficient, or evaporation coefficient, is still being used as a characteristic factor for the cooling tower process. Its dependence on the cooling range or on the warm water temperature of the process is often considered a disadvantage of the theory of evaporation cooling. This is also the reason for the suggestion to change the theory in such a way that the Merkel coefficient becomes independent of the temperature. The present investigation, however, leads to the result that the dependence of the Merkel coefficient on the temperature must be considered as a remarkable confirmation for the evidence of the theory of heat and mass transfer, as the experimental statements agree fully with the results of the theoretical considerations. (orig.) [de
A study of the irradiation temperature coefficient for L-alanine and DL-alanine dosemeters
International Nuclear Information System (INIS)
Desrosiers, M. F.; Lin, M.; Cooper, S. L.; Cui, Y.; Chen, K.
2006-01-01
Alanine dosimetry is now well established both as a reference and routine dosemeter for industrial irradiation processing. Accurate dosimetry under the relatively harsh conditions of industrial processing requires a characterisation of the parameters that influence the dosemeter response. The temperature of the dosemeter during irradiation is a difficult quantity to measure so that the accuracy of the temperature coefficient that governs the dosemeter response becomes a critical factor. Numerous publications have reported temperature coefficients for several types of alanine dosemeters. The observed differences in the measured values were commonly attributed to the differences in the polymer binder or the experimental design of the measurement. However, the data demonstrated a consistent difference in the temperature coefficients between L-alanine and DL-alanine. Since there were no commonalities in the dosemeter composition or the measurement methods applied, a clear conclusion is not possible. To resolve this issue, the two isomeric forms of alanine dosemeters were prepared and irradiated in an identical manner. The results indicated that the DL-alanine temperature coefficient is more than 50% higher than the L-alanine temperature coefficient. (authors)
CH3Cl self-broadening coefficients and their temperature dependence
International Nuclear Information System (INIS)
Dudaryonok, A.S.; Lavrentieva, N.N.; Buldyreva, J.V.
2013-01-01
CH 3 35 Cl self-broadening coefficients at various temperatures of atmospheric interest are computed by a semi-empirical method particularly suitable for molecular systems with strong dipole–dipole interactions. In order to probe the dependence on the rotational number K, the model parameters are adjusted on extensive room-temperature measurements for K≤7 and allow reproducing fine features of J-dependences observed for K≤3; for higher K up to 20, the fitting is performed on specially calculated semi-classical values. The temperature exponents for the standard power law are extracted and validated by calculation of low-temperature self-broadening coefficients comparing very favorably with available experimental data. An extensive line-list of self-broadening coefficients at the reference temperature 296 K and associated temperature exponents for 0≤J≤70, 0≤K≤20 is provided as Supplementary material for their use in atmospheric applications and spectroscopic databases. -- Highlights: • We calculated methyl chloride self-broadening coefficients using two methods. • Rotational quantum numbers were J from 0 till 70 and K from 0 till 20. • The temperature exponents were calculated for every mentioned line
Ilia Anisa, Nor; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio
2014-04-01
6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10-11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10-11 m2/s.
International Nuclear Information System (INIS)
Anisa, Nor Ilia; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio
2014-01-01
6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10 −11 m 2 /s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10 −11 m 2 /s.
Liu, Yiwei; Wang, Baomin; Zhan, Qingfeng; Tang, Zhenhua; Yang, Huali; Liu, Gang; Zuo, Zhenghu; Zhang, Xiaoshan; Xie, Yali; Zhu, Xiaojian; Chen, Bin; Wang, Junling; Li, Run-Wei
2014-01-01
The magnetic anisotropy is decreased with increasing temperature in normal magnetic materials, which is harmful to the thermal stability of magnetic devices. Here, we report the realization of positive temperature coefficient of magnetic anisotropy in a novel composite combining β-phase polyvinylidene fluoride (PVDF) with magnetostrictive materials (magnetostrictive film/PVDF bilayer structure). We ascribe the enhanced magnetic anisotropy of the magnetic film at elevated temperature to the st...
Temperature dependence of the hydrogen-broadening coefficient for the nu 9 fundamental of ethane
Halsey, G. W.; Hillman, J. J.; Nadler, Shacher; Jennings, D. E.
1988-01-01
Experimental results for the temperature dependence of the H2-broadening coefficient for the nu 9 fundamental of ethane are reported. Measurements were made over the temperature range 95-300 K using a novel low-temperature absorption cell. These spectra were recorded with the Doppler-limited diode laser spectrometer at NASA Goddard. The results are compared with recent measurements and model predictions.
Monitoring temperature reactivity coefficient by noise method in a NPP at full power
International Nuclear Information System (INIS)
Aguilar, O.; Por, G.
1987-04-01
A new method based on noise measurement was used to estimate the temperature reactivity coefficient of the PAKS-2 reactor during the entire fuel cycle. Based on the measurements it is possible to measure the dependence of reactivity coefficient on boron concentration. Good agreement was found between the results obtained by the new method and by the conventional ones. Based on this method a new equipment can be develop which assures permanent measurements during operation. (author)
Energy Technology Data Exchange (ETDEWEB)
Silvester, Leonard F.; Pitzer, Kenneth S.
1977-11-01
Heat of dilution and of solution data are fitted to the form of equation corresponding to that used successfully for activity and osmotic coefficients over a wide range of concentration. The resulting parameters give the change with temperature of the activity and osmotic coefficients. Results are reported for 84 electrolytes of 1-1, 2-1, 3-1, and 2-2 valence types.
Measurement of reactivity temperature coefficient by noise method in a power reactor
International Nuclear Information System (INIS)
Aguilar, O.
1986-07-01
The temperature reactivity coefficient was estimated on the basis of noise measurements performed in a PWR. The magnitude of the coefficient was evaluated by relating the values of the APSD and CPSD between ex-core neutron detector signals and fuel assembly outlet thermocouple in the low frequency range. Comparison with δρ/δT measurements performed in PWR by standard methods supports the validity of the results. (author)
On a Hele-Shaw flow with a time-dependent gap in the presence of surface tension
International Nuclear Information System (INIS)
Savina, T V; Nepomnyashchy, A A
2015-01-01
The introduction of surface tension into a Hele-Shaw problem makes it more realistic from the physical viewpoint, but more difficult from the mathematical viewpoint. In this paper we discuss a Hele-Shaw flow with a time-dependent gap taking into account the surface tension of the free boundary. We use the Schwarz function method to find asymptotic solutions for the interior problem in the case when the initial shape of the droplet is a weakly distorted circle. (paper)
A waveless two-dimensional flow in a channel against an inclined wall with surface tension effect
International Nuclear Information System (INIS)
Merzougui, Abdelkrim; Mekias, Hocine; Guechi, Fairouz
2007-01-01
Surface tension effect on a two-dimensional channel flow against an inclined wall is considered. The flow is assumed to be steady, irrotational, inviscid and incompressible. The effect of surface tension is taken into account and the effect of gravity is neglected. Numerical solutions are obtained via series truncation procedure. The problem is solved numerically for various values of the Weber number α and for various values of the inclination angle β between the horizontal bottom and the inclined wall
A waveless two-dimensional flow in a channel against an inclined wall with surface tension effect
Energy Technology Data Exchange (ETDEWEB)
Merzougui, Abdelkrim [Departement de Mathematiques, Faculte des sciences, Universite Mohamed Boudiaf, M' sila, 28000 (Algeria); Mekias, Hocine [Departement de Mathematiques, Faculte des sciences, Universite Farhat Abbas Setif 19000 (Algeria); Guechi, Fairouz [Departement de Mathematiques, Faculte des sciences, Universite Farhat Abbas Setif 19000 (Algeria)
2007-11-23
Surface tension effect on a two-dimensional channel flow against an inclined wall is considered. The flow is assumed to be steady, irrotational, inviscid and incompressible. The effect of surface tension is taken into account and the effect of gravity is neglected. Numerical solutions are obtained via series truncation procedure. The problem is solved numerically for various values of the Weber number {alpha} and for various values of the inclination angle {beta} between the horizontal bottom and the inclined wall.
Effect of increased surface tension and assisted ventilation on /sup 99m/Tc-DTPA clearance
International Nuclear Information System (INIS)
Jefferies, A.L.; Kawano, T.; Mori, S.; Burger, R.
1988-01-01
Experiments were performed to determine the effects of conventional mechanical ventilation (CMV) and high-frequency oscillation (HFO) on the clearance of technetium-99m-labeled diethylenetriamine pentaacetate (/sup 99m/Tc-DTPA) from lungs with altered surface tension properties. A submicronic aerosol of /sup 99m/Tc-DTPA was insufflated into the lungs of anesthetized, tracheotomized rabbits before and 1 h after the administration of the aerosolized detergent dioctyl sodium sulfosuccinate (OT). Rabbits were ventilated by one of four methods: 1) spontaneous breathing; 2) CMV at 12 cmH2O mean airway pressure (MAP); 3) HFO at 12 cmH2O MAP; 4) HFO at 16 cmH2O MAP. Administration of OT resulted in decreased arterial PO2 (PaO2), increased lung wet-to-dry weight ratios, and abnormal lung pressure-volume relationships, compatible with increased surface tension. /sup 99m/Tc-DTPA clearance was accelerated after OT in all groups. The post-OT rate of clearance (k) was significantly faster (P less than 0.05) in the CMV at 12 cmH2O MAP [k = 7.57 +/- 0.71%/min (SE)] and HFO at 16 cmH2O MAP (k = 6.92 +/- 0.61%/min) groups than in the spontaneously breathing (k = 4.32 +/- 0.55%/min) and HFO at 12 cmH2O MAP (4.68 +/- 0.63%/min) groups. The clearance curves were biexponential in the former two groups. We conclude that pulmonary clearance of /sup 99m/Tc-DTPA is accelerated in high surface tension pulmonary edema, and this effect is enhanced by both conventional ventilation and HFO at high mean airway pressure
Energy Technology Data Exchange (ETDEWEB)
Kikuchi, T.; Hayasaka, K.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science
1996-10-28
The behavior and properties of associated bodies were studied through measurement of surface tension considering acetone-soluble fraction relatively light among various solvent extracts of coal. In experiment, the acetone-soluble fraction was extracted from the substances extracted from Upper Freeport coal as standard specimen using the mixed solvent of carbon disulfide (CS2) and N-methyl-2-pyrrolidinone (NMP), and it was dissolved into NMP after drying. Surface tension was measured by Wilhelmy method. The experimental results are as follows. Equilibrium surface tension is equal to the surface tension of pure solvent in a low concentration range of solution, and decreases with an increase in concentration approaching a fixed value at 0 in log concentration, nearly showing an S curve. Adsorption of species with non-polar aromatic ring of the acetone-soluble fraction on a solution surface probably decreases surface tension. Change with time in surface tension is observed which suggests fast initial reaction and slow subsequent reaction. 4 figs.
Zhang, Zhen-yu; Zhang, Hui-sheng
2004-11-01
Surface tension effects on the behavior of a pure vapor cavity or a cavity containing some noncondensible contents, which is growing, collapsing, and rebounding axisymmetrically near a rigid wall, are investigated numerically by the boundary integral method for different values of dimensionless stand-off parameter gamma, buoyancy parameter delta, and surface tension parameter beta. It is found that at the late stage of the collapse, if the resultant action of the Bjerknes force and the buoyancy force is not small, surface tension will not have significant effects on bubble behavior except that the bubble collapse time is shortened and the liquid jet becomes wider. If the resultant action of the two force is small enough, surface tension will have significant and in some cases substantial effects on bubble behavior, such as changing the direction of the liquid jet, making a new liquid jet appear, in some cases preventing the bubble from rebound before jet impact, and in other cases causing the bubble to rebound or even recollapse before jet impact. The mechanism of surface tension effects on the collapsing behavior of a cavity has been analyzed. The mechanisms of some complicated phenomena induced by surface tension effects are illustrated by analysis of the computed velocity fields and pressure contours of the liquid flow outside the bubble at different stages of the bubble evolution.
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.
International Nuclear Information System (INIS)
Komarov, V.E.; Borodina, N.P.
1981-01-01
Diffusion coefficients of U 3+ ions are measured by chronopotentiometric method in chloride 3LiCl-2KCl and in mixed chloride fluoride 3LiCl(LiF)-2KCl melts in the temperature range 633-1235 K. It is shown It is shown that experimental values of diffusion-coefficients are approximated in a direct line in lg D-1/T coordinate in chloride melt in the whole temperature range and in chloride-fluoride melt in the range of 644-1040 K. Experimental values of diffusion coefficients diviate from Arrhenius equation in the direction of large values in chloride-fluoride melt at further increase of temperature up to 1235 K. Possible causes of such a diviation are considered [ru
Estimation of moderator temperature coefficient of actual PWRs using wavelet transform
International Nuclear Information System (INIS)
Katsumata, Ryosuke; Shimazu, Yoichiro
2001-01-01
Recently, an applicability of wavelet transform for estimation of moderator temperature coefficient was shown in numerical simulations. The basic concept of the wavelet transform is to eliminate noise in the measured signals. The concept is similar to that of Fourier transform method in which the analyzed reactivity component is divided by the analyzed component of relevant parameter. In order to apply the method to analyze measured data in actual PWRs, we carried out numerical simulations on the data that were more similar to actual data and proposed a method for estimation of moderator temperature coefficient using the wavelet transform. In the numerical simulations we obtained moderator temperature coefficients with the relative error of less than 4%. Based on this result we applied this method to analyze measured data in actual PWRs and the results have proved that the method is applicable for estimation of moderator temperature coefficients in the actual PWRs. It is expected that this method can reduce the required data length during the measurement. We expect to expand the applicability of this method to estimate the other reactivity coefficients with the data of short transient. (author)
Energy Technology Data Exchange (ETDEWEB)
Nasirabadi, P. Shojaee; Jabbari, M.; Hattel, J. H. [Process Modelling Group, Department of Mechanical Engineering, Technical University of Denmark, Nils Koppels Allé, 2800 Kgs. Lyngby (Denmark)
2016-06-08
Nowadays, many electronic systems are exposed to harsh conditions of relative humidity and temperature. Mass transport properties of electronic packaging materials are needed in order to investigate the influence of moisture and temperature on reliability of electronic devices. Polycarbonate (PC) is widely used in the electronics industry. Thus, in this work the water diffusion coefficient into PC is investigated. Furthermore, numerical methods used for estimation of the diffusion coefficient and their assumptions are discussed. 1D and 3D numerical solutions are compared and based on this, it is shown how the estimated value can be different depending on the choice of dimensionality in the model.
International Nuclear Information System (INIS)
Bai, Byong Chol; Kang, Seok Chang; Im, Ji Sun; Lee, Se Hyun; Lee, Young-Seak
2011-01-01
Graphical abstract: The electrical properties of MWCNT-filled HDPE polymeric switches and their effect on oxyfluorination. Highlights: → Oxyfluorinated MWCNTs were used to reduce the PTC/NTC phenomenon in MWCNT-filled HDPE polymeric switches. → Electron mobility is difficult in MWCNT particles when the number of oxygen functional groups (C-O, C=O) increases by oxyfluorination. → A mechanism of improved electrical properties of oxyfluorinated MWCNT-filled HDPE polymeric switches was suggested. -- Abstract: Multi-walled carbon nanotubes (MWCNTs) were embedded into high-density polyethylene (HDPE) to improve the electrical properties of HDPE polymeric switches. The MWCNT surfaces were modified by oxyfluorination to improve their positive temperature coefficient (PTC) and negative temperature coefficient (NTC) behaviors in HDPE polymeric switches. HDPE polymeric switches exhibit poor electron mobility between MWCNT particles when the number of oxygen functional groups is increased by oxyfluorination. Thus, the PTC intensity of HDPE polymeric switches was increased by the destruction of the electrical conductivity network. The oxyfluorination of MWCNTs also leads to weak NTC behavior in the MWCNT-filled HDPE polymeric switches. This result is attributed to the reduction of the mutual attraction between the MWCNT particles at the melting temperature of HDPE, which results from a decrease in the surface free energy of the C-F bond in MWCNT particles.
Control rod position and temperature coefficients in HTTR power-rise tests. Interim report
International Nuclear Information System (INIS)
Fujimoto, Nozomu; Nojiri, Naoki; Takada, Eiji; Saito, Kenji; Kobayashi, Shoichi; Sawahata, Hiroaki; Kokusen, Sigeru
2001-03-01
Power-rise tests of the High Temperature Engineering Test Reactor (HTTR) have been carried out aiming to achieve 100% power. So far, 50% of power operation and many tests have been carried out. In the HTTR, temperature change in core is so large to achieve the outlet coolant temperature of 950degC. To improve the calculation accuracy of the HTTR reactor physics characteristics, control rod positions at criticality and temperature coefficients were measured at each step to achieve 50% power level. The calculations were carried out using Monte Carlo code and diffusion theory with temperature distributions in the core obtained by reciprocal calculation of thermo-hydraulic code and diffusion theory. Control rod positions and temperature coefficients were calculated by diffusion theory and Monte Carlo method. The test results were compared to calculation results. The control rod positions at criticality showed good agreement with calculation results by Monte Carlo method with error of 50 mm. The control position at criticality at 100% was predicted around 2900mm. Temperature coefficients showed good agreement with calculation results by diffusion theory. The improvement of calculation will be carried out comparing the measured results up to 100% power level. (author)
Energy Technology Data Exchange (ETDEWEB)
Fechter, Stefan, E-mail: stefan.fechter@iag.uni-stuttgart.de [Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70569 Stuttgart (Germany); Munz, Claus-Dieter, E-mail: munz@iag.uni-stuttgart.de [Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70569 Stuttgart (Germany); Rohde, Christian, E-mail: Christian.Rohde@mathematik.uni-stuttgart.de [Institut für Angewandte Analysis und Numerische Simulation, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany); Zeiler, Christoph, E-mail: Christoph.Zeiler@mathematik.uni-stuttgart.de [Institut für Angewandte Analysis und Numerische Simulation, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany)
2017-05-01
The numerical approximation of non-isothermal liquid–vapor flow within the compressible regime is a difficult task because complex physical effects at the phase interfaces can govern the global flow behavior. We present a sharp interface approach which treats the interface as a shock-wave like discontinuity. Any mixing of fluid phases is avoided by using the flow solver in the bulk regions only, and a ghost-fluid approach close to the interface. The coupling states for the numerical solution in the bulk regions are determined by the solution of local two-phase Riemann problems across the interface. The Riemann solution accounts for the relevant physics by enforcing appropriate jump conditions at the phase boundary. A wide variety of interface effects can be handled in a thermodynamically consistent way. This includes surface tension or mass/energy transfer by phase transition. Moreover, the local normal speed of the interface, which is needed to calculate the time evolution of the interface, is given by the Riemann solution. The interface tracking itself is based on a level-set method. The focus in this paper is the description of the two-phase Riemann solver and its usage within the sharp interface approach. One-dimensional problems are selected to validate the approach. Finally, the three-dimensional simulation of a wobbling droplet and a shock droplet interaction in two dimensions are shown. In both problems phase transition and surface tension determine the global bulk behavior.
Chen, Shulei; Liu, Kun; Liu, Cunbin; Wang, Dongyang; Ba, Dechun; Xie, Yuanhua; Du, Guangyu; Ba, Yaoshuai; Lin, Qiao
2016-12-01
Surface tension and viscosity act as important roles on the fluid flow in microchannel channels. In order to understand the influencing mechanism, three dimensional numerical simulations as well as experimental investigations were carried out on the slug formation and transfer in a rectangle T-junction microchannel. The simulation showed that the increasing Capillary number (Ca) resulted in the decreasing slug volume. Due to the existence of film thickness and corner flow, the characteristic length of slug was not the same trend completely. The results also showed that the pressure of junction point fluctuated periodically in the process of slug formation, which can reflect the slug formation period and the effect of the various conditions on pressure change. Two other pressure monitoring points were located in vertical channel and main channel and they monitored the pressure of two phase flow respectively. The increasing surface tension resulted in an increasing of total pressure, the interface pressure drop of two phases and the period of slug formation. The frequency of slug formation and two phases total pressure increased with the viscosity of continuous phase.
Incorporating contact angles in the surface tension force with the ACES interface curvature scheme
Owkes, Mark
2017-11-01
In simulations of gas-liquid flows interacting with solid boundaries, the contact line dynamics effect the interface motion and flow field through the surface tension force. The surface tension force is directly proportional to the interface curvature and the problem of accurately imposing a contact angle must be incorporated into the interface curvature calculation. Many commonly used algorithms to compute interface curvatures (e.g., height function method) require extrapolating the interface, with defined contact angle, into the solid to allow for the calculation of a curvature near a wall. Extrapolating can be an ill-posed problem, especially in three-dimensions or when multiple contact lines are near each other. We have developed an accurate methodology to compute interface curvatures that allows for contact angles to be easily incorporated while avoiding extrapolation and the associated challenges. The method, known as Adjustable Curvature Evaluation Scale (ACES), leverages a least squares fit of a polynomial to points computed on the volume-of-fluid (VOF) representation of the gas-liquid interface. The method is tested by simulating canonical test cases and then applied to simulate the injection and motion of water droplets in a channel (relevant to PEM fuel cells).
An accessible micro-capillary electrophoresis device using surface-tension-driven flow
Mohanty, Swomitra K.; Warrick, Jay; Gorski, Jack; Beebe, David J.
2010-01-01
We present a rapidly fabricated micro-capillary electrophoresis chip that utilizes surface-tension-driven flow for sample injection and extraction of DNA. Surface-tension-driven flow (i.e. passive pumping) injects a fixed volume of sample that can be predicted mathematically. Passive pumping eliminates the need for tubing, valves, syringe pumps, and other equipment typically needed for interfacing with microelectrophoresis chips. This method requires a standard micropipette to load samples before separation, and remove the resulting bands after analysis. The device was made using liquid phase photopolymerization to rapidly fabricate the chip without the need of special equipment typically associated with the construction of microelectrophoresis chips (e.g. cleanroom). Batch fabrication time for the device presented here was 1.5 h including channel coating time to suppress electroosmotic flow. Devices were constructed out of poly-isobornyl acrylate and glass. A standard microscope with a UV source was used for sample detection. Separations were demonstrated using Promega BenchTop 100 bp ladder in hydroxyl ethyl cellulose (HEC) and oligonucleotides of 91 and 118 bp were used to characterize sample injection and extraction of DNA bands. The end result was an inexpensive micro-capillary electrophoresis device that uses tools (e.g. micropipette, electrophoretic power supplies, and microscopes) already present in most labs for sample manipulation and detection, making it more accessible for potential end users. PMID:19425002
Surface tension driven aggregation of organic nanowires via lab in a droplet.
Gu, Jianmin; Yin, Baipeng; Fu, Shaoyan; Feng, Man; Zhang, Ziming; Dong, Haiyun; Gao, Faming; Zhao, Yong Sheng
2018-06-05
Directing the architecture of complex organic nanostructures is desirable and still remains a challenge in areas of materials science due to their structure-dependent collective optoelectronic properties. Herein, we demonstrate a simple and versatile solution strategy that allows surface tension to drive low-dimensional nanostructures to aggregate into complex structures via a lab in a droplet technique. By selecting a suitable combination of a solvent and an anti-solvent with controllable surface tension difference, the droplets can be automatically cracked into micro-droplets, which provides an aggregation force directed toward the centre of the droplet to drive the low-dimensional building blocks to form the special aggregations during the self-assembly process. This synthetic strategy has been shown to be universal for organic materials, which is beneficial for further optimizing the optoelectronic properties. These results contribute to gaining an insightful understanding on the detailed growth mechanism of complex organic nanostructures and greatly promoting the development of organic nanophotonics.
Measurements of fuel temperature coefficient of reactivity on a commercial AGR
International Nuclear Information System (INIS)
Telford, A.; Bridge, M.J.
1978-01-01
Tests have been carried out on the commercial AGR at Hikley Point to determine the fuel temperature coefficient of reactivity, an important safety related parameter. Reactor neutron flux was measured during transients induced by movement of a bank of control rods from one steady position to another. An inverse kinetics analysis was applied to the measured flux to determine the change which occured in core reactivity as the fuel temperature changed. The variation of mean fuel temperature was deduced from the flux transient by means of a nine-plane thermal hydraulics representation of the AGR fuel channel. Results so far obtained confirm the predicted variation of fuel temperature coefficient with butn-up. (author)
Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells
Energy Technology Data Exchange (ETDEWEB)
Aho, Arto; Isoaho, Riku; Tukiainen, Antti; Polojärvi, Ville; Aho, Timo; Raappana, Marianna; Guina, Mircea [Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)
2015-09-28
We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37–39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be −7.5 mV/°C, 0.040 mA/cm{sup 2}/°C, and −0.09%/°C, respectively.
Self-consistent transport coefficients for average collective motion at moderately high temperatures
International Nuclear Information System (INIS)
Yamaji, Shuhei; Hofmann, H.; Samhammer, R.
1987-01-01
Linear response theory is applied to compute the coefficients for inertia, friction and local stiffness for slow, large scale nuclear collective motion. It is shown how these coefficients can be defined within a locally harmonic approximation. The latter allows to study the implications arising from a finite local collective frequency. It is only for temperatures around 2 MeV that the zero frequency limit becomes a fair approximation. Friction is found to have a marked temperature dependence. The numerical computations are performed on the basis of a two-center shell model, but allowing the particles and holes to become dressed through effects of the medium. The dependence of the transport coefficients on the parameters of these self-energies is studied. It is argued that the uncertainties are smaller than a factor of 2. (orig.)
AUTHOR|(CDS)2084596; Papastergiou, Konstantinos; Bongiorno, M; Thiringer, T
2016-01-01
This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.
International Nuclear Information System (INIS)
Raffaelle, R.P.; Parris, P.E.; Anderson, H.U.; Sparlin, D.M.
1991-01-01
Thermoelectric power measurements are presented for the (La,Sr)(Cr,Mn)O 3 series. The nonlinear temperature dependence of the Seebeck coefficient is analyzed in terms of a random distribution of energetically equivalent hopping sites. The limitations of Heikes' formula, which has been traditionally used to calculate small polaron carrier densities in these systems, are discussed. Recent theoretical developments in the interpretation of Seebeck measurements in substitutionally-disordered high-temperature hopping conductors are reviewed
Measuring temperature coefficient of TRIGA MARK I reactor by noise analysis
International Nuclear Information System (INIS)
Soares, P.A.
1975-01-01
The transfer function of TRIGA MARK I Reactor is measured at power zero (5w) and power 118Kw, in the frequency range of 0.02 to 0.5 rd/s. The method of intercorrelation between a pseudostochasticbinary signal is used. A simple dynamic model of the reactor is developed and the coefficient of temperature is estimated [pt
Temperature dependence of the absorption coefficient of water for midinfrared laser radiation
Jansen, E. D.; van Leeuwen, T. G.; Motamedi, M.; Borst, C.; Welch, A. J.
1994-01-01
The dynamics of the water absorption peak around 1.94 microns was examined. This peak is important for the absorption of holmium and thulium laser radiation. To examine the effect of temperature on the absorption coefficient, the transmission of pulsed Ho:YAG, Ho:YAG, Ho:YSGG, and Tm:YAG laser
International Nuclear Information System (INIS)
Adam, E.; Knorr, J.
1982-01-01
Approximate formulas are derived for determining the temperature coefficient of reactivity of the training and research reactor (AKR) of the Dresden Technical University. Values calculated on the basis of these approximations show good agreement with experimentally obtained results, thus confirming the applicability of the formulas to simple systems
Monte Carlo calculation of the nuclear temperature coefficient in fast reactors
Energy Technology Data Exchange (ETDEWEB)
Matthes, W.
1974-04-15
A Monte Carlo program for the calculation of the nuclear temperature coefficient for fast reactors is described. The special difficulties for this problem are the energy and space dependence of the cross sections and the calculation of differential eifects. These difficulties are discussed in detail and the way for their solution chosen in this program is described. (auth)
International Nuclear Information System (INIS)
Silva, Rubens C. da; Bitelli, Ulysses D.; Mura, Luiz Ernesto C.
2017-01-01
The aim of this article is to present the procedure for the experimental estimation of the Moderator Temperature Coefficient of Reactivity of the IPEN/MB-01 Research Reactor, a parameter that has an important role in the physics and the control operations of any reactor facility. At the experiment, the IPEN/MB-01 reactor went critical at the power of 1W (1% of its total power), and whose core configuration was 28 x 26 rectangular array of UO_2 fuel rods, inside a light water (moderator) tank. In addition, there was a heavy water (D_2O) reflector installed in the West side of the core to obtain an adequate neutron reflection along the experiment. The moderator temperature was increased in steps of 4 °C, and the measurement of the mean moderator temperature was acquired using twelve calibrated thermocouples, placed around the reactor core. As a result, the mean value of -4.81 pcm/°C was obtained for such coefficient. The curves of ρ(T) (Reactivity x Temperature) and α"M_T(T)(Moderator Temperature Coefficient of Reactivity x Temperature) were developed using data from an experimental measurement of the integral reactivity curves through the Stable Period and Inverse Kinetics Methods, that was carried out at the reactor with the same core configuration. Such curves were compared and showed a very similar behavior between them. (author)
Energy Technology Data Exchange (ETDEWEB)
Silva, Rubens C. da; Bitelli, Ulysses D.; Mura, Luiz Ernesto C., E-mail: rubensrcs@usp.br, E-mail: ubitelli@ipen.br, E-mail: credidiomura@gmail.com [Universidade de Sao Paulo (PNV/POLI/USP), SP (Brazil). Arquitetura Naval e Departamento de Engenharia Oceanica; Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2017-07-01
The aim of this article is to present the procedure for the experimental estimation of the Moderator Temperature Coefficient of Reactivity of the IPEN/MB-01 Research Reactor, a parameter that has an important role in the physics and the control operations of any reactor facility. At the experiment, the IPEN/MB-01 reactor went critical at the power of 1W (1% of its total power), and whose core configuration was 28 x 26 rectangular array of UO{sub 2} fuel rods, inside a light water (moderator) tank. In addition, there was a heavy water (D{sub 2}O) reflector installed in the West side of the core to obtain an adequate neutron reflection along the experiment. The moderator temperature was increased in steps of 4 °C, and the measurement of the mean moderator temperature was acquired using twelve calibrated thermocouples, placed around the reactor core. As a result, the mean value of -4.81 pcm/°C was obtained for such coefficient. The curves of ρ(T) (Reactivity x Temperature) and α{sup M}{sub T}(T)(Moderator Temperature Coefficient of Reactivity x Temperature) were developed using data from an experimental measurement of the integral reactivity curves through the Stable Period and Inverse Kinetics Methods, that was carried out at the reactor with the same core configuration. Such curves were compared and showed a very similar behavior between them. (author)
Elasticity moduli, thermal expansion coefficients and Debye temperature of titanium alloys
International Nuclear Information System (INIS)
Beletskij, V.M.; Glej, V.A.; Maksimyuk, P.A.; Tabachnik, V.I.; Opanasenko, V.F.
1979-01-01
Studied are the characteristics of titanium alloys which reflect best the bonding forces for atoms in a crystal lattice: elastic modules, their temperature dependences, thermal expansion coefficient and Debye temperatures. For the increase of the accuracy of measuring modules and especially their changes with temperature an ultrasonic echo-impulse method of superposition has been used. The temperature dependences of Young modulus of the VT1-0, VT16 and VT22 titanium alloys are plotted. The Young module and its change with temperature depend on the content of alloying elements. The Young module decrease with temperature may be explained within the framework of the inharmonic effect theory. The analysis of the results obtained permits to suppose that alloying of titanium alloys with aluminium results in an interatomic interaction increase that may be one of the reasons of their strength increase
Measurement of the Thermal Expansion Coefficient for Ultra-High Temperatures up to 3000 K
Kompan, T. A.; Kondratiev, S. V.; Korenev, A. S.; Puhov, N. F.; Inochkin, F. M.; Kruglov, S. K.; Bronshtein, I. G.
2018-03-01
The paper is devoted to a new high-temperature dilatometer, a part of the State Primary Standard of the thermal expansion coefficient (TEC) unit. The dilatometer is designed for investigation and certification of materials for TEC standards in the range of extremely high temperatures. The critical review of existing methods of TEC measurements is given. Also, the design, principles of operation and metrological parameters of the new device are described. The main attention is paid to the system of machine vision that allows accurate measurement of elongation at high temperatures. The results of TEC measurements for graphite GIP-4, single crystal Al2O3, and some other materials are also presented.
The accommodation coefficient of the liquid at temperatures below the boiling
Directory of Open Access Journals (Sweden)
Bulba Elena E.
2015-01-01
Full Text Available Are carried out experimental investigation of the laws of vaporization at temperatures below the boiling point. Is determined the mass rate of evaporation of distilled water in large intervals of time at different temperatures in order to sound conclusions about the stationarity of the process of evaporation of the liquid in the conditions of the experiments performed, and also studied the effect of temperature on the rate of evaporation. Accommodation coefficient is defined in the mathematical expression of the law of Hertz-Knudsen for standart substance used in the experiments.
International Nuclear Information System (INIS)
Jee, Madan; Prasad, Vijay; Singh, Amita
1995-01-01
The electrical resistivity, Hall coefficient and electronic mobility of n-type and p-type crystals of indium antimonide have been measured from 25 degC-100 degC temperature range. It has been found by this measurement that indium antimonide is a compound semiconductor with a high mobility 10 6 cm 2 /V.S. The Hall coefficient R H was measured as a function of magnetic field strength H for a number of samples of both p and n-type using fields up to 12 kilo gauss. The Hall coefficient R h decreases with increasing magnetic fields as well as with increase in temperature of the sample. The electric field is more effective on samples with high mobilities and consequently the deviations from linearity are manifested at comparatively low values of the electric field. The measurement of R H in weak and strong magnetic fields makes it possible to determine the separate concentration of heavy and light holes. Measured values of Hall coefficient and electrical resistivity show that there is a little variation of ρ and R h with temperatures as well as with magnetic fields. (author). 12 refs., 5 tabs
A new kind of shape-stabilized PCMs with positive temperature coefficient (PTC) effect
International Nuclear Information System (INIS)
Cheng, Wen-long; Wu, Wan-fan; Song, Jia-liang; Liu, Yi; Yuan, Shuai; Liu, Na
2014-01-01
Highlights: • A new kind of shape-stabilized PCMs with PTC effect is first prepared. • It provides a potential means for the thermal control of the electronic devices. • The switching temperature of the materials is about 25 °C. • The most appropriate component of the material is found out by experimental study. • The NTC effect of the new PCMs is eliminated effectively by heat treatment. - Abstract: A new kind of shape-stabilized phase change materials (PCMs) with positive temperature coefficient (PTC) effect was prepared in this paper. The materials were prepared by adding graphite powder (GP) to the paraffin/low density polyethylene (LDPE) composite and the PTC characteristic was found by adjusting the component ratio of the material. Then the physical structures and thermal properties of the materials were investigated and the effect of various GP mass fractions and paraffin/LDPE mass proportions on the PTC behavior of the materials was studied experimentally. The results showed that the switching temperature of the materials was about 25 °C (room temperature) which approached to the first phase change temperature of paraffin dispersed in the materials. The PTC behavior of the materials was the best when the GP mass fraction and the mass proportion of LDPE/paraffin were 40 wt% and 30:70, respectively. Furthermore, the negative temperature coefficient (NTC) effect of the materials could be eliminated effectively with heat treatment. This new kind of materials is different from the former PTC materials which the switching temperatures focus on high temperature ranges. It makes up for the defect of previous materials that the switching temperatures only range in high temperature rather than room temperature and provides a potential means for the thermal control of the electronic devices or other room temperature thermal control applications
Bakhshi, Nafiseh; Soleimanian-Zad, Sabihe; Sheikh-Zeinoddin, Mahmoud
2017-06-01
Currently, screening of microbial biosurfactants (BSs) is based on their equilibrium surface tension values obtained using static surface tension measurement. However, a good surfactant should not only have a low equilibrium surface tension, but its dynamic surface tension (DST) should also decrease rapidly with time. In this study, screening of BSs produced by Lactobacillus plantarum subsp. plantarum PTCC 1896 (probiotic) was performed based on their DST values measured by Wilhelmy plate tensiometry. The relationship between DST and structural and functional properties (anti-adhesive activity) of the BSs was investigated. The results showed that the changes in the yield, productivity and structure of the BSs were growth medium and incubation time dependent (p<0.05). Structurally different BSs produced exhibited identical equilibrium surface tension values. However, differences among the structure/yield of the BSs were observed through the measurement of their DST. The considerable dependence of DST on the concentration and composition of the BS proteins was observed (p<0.05). Moreover, the anti-adhesive activity of the BS was found to be positively correlated with its DST. The results suggest that the DST measurement could serve as an efficient method for the clever screening of BSs producer/production condition, and consequently, for the investigation of probiotic features of bacteria, since the anti-adhesive activity is an important criterion of probiotics. Copyright © 2017 Elsevier Inc. All rights reserved.
Tice, Ian
2018-04-01
This paper concerns the dynamics of a layer of incompressible viscous fluid lying above a rigid plane and with an upper boundary given by a free surface. The fluid is subject to a constant external force with a horizontal component, which arises in modeling the motion of such a fluid down an inclined plane, after a coordinate change. We consider the problem both with and without surface tension for horizontally periodic flows. This problem gives rise to shear-flow equilibrium solutions, and the main thrust of this paper is to study the asymptotic stability of the equilibria in certain parameter regimes. We prove that there exists a parameter regime in which sufficiently small perturbations of the equilibrium at time t=0 give rise to global-in-time solutions that return to equilibrium exponentially in the case with surface tension and almost exponentially in the case without surface tension. We also establish a vanishing surface tension limit, which connects the solutions with and without surface tension.
Zuhair; Suwoto; Setiadipura, T.; Bakhri, S.; Sunaryo, G. R.
2018-02-01
As a part of the solution searching for possibility to control the plutonium, a current effort is focused on mechanisms to maximize consumption of plutonium. Plutonium core solution is a unique case in the high temperature reactor which is intended to reduce the accumulation of plutonium. However, the safety performance of the plutonium core which tends to produce a positive temperature coefficient of reactivity should be examined. The pebble bed inherent safety features which are characterized by a negative temperature coefficient of reactivity must be maintained under any circumstances. The purpose of this study is to investigate the characteristic of temperature coefficient of reactivity for plutonium core of pebble bed reactor. A series of calculations with plutonium loading varied from 0.5 g to 1.5 g per fuel pebble were performed by the MCNPX code and ENDF/B-VII library. The calculation results show that the k eff curve of 0.5 g Pu/pebble declines sharply with the increase in fuel burnup while the greater Pu loading per pebble yields k eff curve declines slighter. The fuel with high Pu content per pebble may reach long burnup cycle. From the temperature coefficient point of view, it is concluded that the reactor containing 0.5 g-1.25 g Pu/pebble at high burnup has less favorable safety features if it is operated at high temperature. The use of fuel with Pu content of 1.5 g/pebble at high burnup should be considered carefully from core safety aspect because it could affect transient behavior into a fatal accident situation.
DEFF Research Database (Denmark)
Shojaee Nasirabadi, Parizad; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri
2016-01-01
) is widely used in the electronics industry. Thus, in this work the water diffusion coefficient into PC is investigated. Furthermore, numerical methods used for estimation of the diffusion coefficient and their assumptions are discussed. 1D and 3D numerical solutions are compared and based on this, itis......Nowadays, many electronic systems are exposed to harsh conditions of relative humidity and temperature. Masstransport properties of electronic packaging materials are needed in order to investigate the influence of moisture andtemperature on reliability of electronic devices. Polycarbonate (PC...... shown how the estimated value can be different depending on the choice of dimensionality in the model....
High temperature electrical resistivity and Seebeck coefficient of Ge2Sb2Te5 thin films
Adnane, L.; Dirisaglik, F.; Cywar, A.; Cil, K.; Zhu, Y.; Lam, C.; Anwar, A. F. M.; Gokirmak, A.; Silva, H.
2017-09-01
High-temperature characterization of the thermoelectric properties of chalcogenide Ge2Sb2Te5 (GST) is critical for phase change memory devices, which utilize self-heating to quickly switch between amorphous and crystalline states and experience significant thermoelectric effects. In this work, the electrical resistivity and Seebeck coefficient are measured simultaneously as a function of temperature, from room temperature to 600 °C, on 50 nm and 200 nm GST thin films deposited on silicon dioxide. Multiple heating and cooling cycles with increasingly maximum temperature allow temperature-dependent characterization of the material at each crystalline state; this is in contrast to continuous measurements which return the combined effects of the temperature dependence and changes in the material. The results show p-type conduction (S > 0), linear S(T), and a positive Thomson coefficient (dS/dT) up to melting temperature. The results also reveal an interesting linearity between dS/dT and the conduction activation energy for mixed amorphous-fcc GST, which can be used to estimate one parameter from the other. A percolation model, together with effective medium theory, is adopted to correlate the conductivity of the material with average grain sizes obtained from XRD measurements. XRD diffraction measurements show plane-dependent thermal expansion for the cubic and hexagonal phases.
Spreading of oil on water in the surface-tension regime
Energy Technology Data Exchange (ETDEWEB)
Camp, D.W.; Berg, J.C.
1987-11-01
Data which describe the unidirectional spreading of several pure oils and oil-surfactant mixtures on water in the surface-tension regime are reported. Leading-edge position and profiles of velocity, thickness and film tension are given as functions of time. The data are consistent with the numerical similarity solution of Foda and Cox (1980), although the measured dependence of the film tension on the film thickness often differs from the equilibrium relationship. The configuration of the oil film near the spreading origin may be either a coherent multimolecular layer or a multitude of thinning, outward-moving lenses surrounded by monolayer. The pure oils show an acceleration zone connecting the slow-moving inner region to a fast-moving outer region, while the oil-surfactant mixtures show a much more gradual increase in film velocity.
Modeling of a Curvilinear Planar Crack with a Curvature-Dependent Surface Tension
Zemlyanova, A. Y.; Walton, J. R.
2012-01-01
An approach to modeling fracture incorporating interfacial mechanics is applied to the example of a curvilinear plane strain crack. The classical Neumann boundary condition is augmented with curvature-dependent surface tension. It is shown that the considered model eliminates the integrable crack-tip stress and strain singularities of order 1/2 present in the classical linear fracture mechanics solutions, and also leads to the sharp crack opening that is consistent with empirical observations. Unlike for the case of a straight crack, for a general curvilinear crack some components of the stresses and the derivatives of the displacements may still possess weaker singularities of a logarithmic type. Generalizations of the present study that lead to complete removal of all crack-tip singularities, including logarithmic, are the subject of a future paper. © 2012 Society for Industrial and Applied Mathematics.
Directory of Open Access Journals (Sweden)
M.C. Teixeira
2017-02-01
Full Text Available The aim of this study was the assessment of the physicochemical stability of d-α-tocopherol formulated in medium chain triglyceride nanoemulsions, stabilized with Tween®80 and Lipoid®S75 as surfactant and co-surfactant, respectively. d-α-tocopherol was selected as active ingredient because of its well-recognized interesting anti-oxidant properties (such as radical scavenger for food and pharmaceutical industries. A series of nanoemulsions of mean droplet size below 90 nm (polydispersity index < 0.15 have been produced by high-pressure homogenization, and their surface electrical charge (zeta potential, pH, surface tension, osmolarity, and rheological behavior, were characterized as a function of the d-α-tocopherol loading. In vitro studies in Caco-2 cell lines confirmed the safety profile of the developed nanoemulsions with percentage of cell viability above 90% for all formulations.
A novel technique for including surface tension in PLIC-VOF methods
Energy Technology Data Exchange (ETDEWEB)
Meier, M.; Yadigaroglu, G. [Swiss Federal Institute of Technology, Nuclear Engineering Lab. ETH-Zentrum, CLT, Zurich (Switzerland); Smith, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. for Thermal-Hydraulics
2002-02-01
Various versions of Volume-of-Fluid (VOF) methods have been used successfully for the numerical simulation of gas-liquid flows with an explicit tracking of the phase interface. Of these, Piecewise-Linear Interface Construction (PLIC-VOF) appears as a fairly accurate, although somewhat more involved variant. Including effects due to surface tension remains a problem, however. The most prominent methods, Continuum Surface Force (CSF) of Brackbill et al. and the method of Zaleski and co-workers (both referenced later), both induce spurious or 'parasitic' currents, and only moderate accuracy in regards to determining the curvature. We present here a new method to determine curvature accurately using an estimator function, which is tuned with a least-squares-fit against reference data. Furthermore, we show how spurious currents may be drastically reduced using the reconstructed interfaces from the PLIC-VOF method. (authors)
Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips
Li, Huawei
2013-04-01
This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.
Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips
Li, Huawei; Fan, Yiqiang; Yi, Ying; Foulds, Ian G.
2013-01-01
This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.
A multiscale method for compressible liquid-vapor flow with surface tension*
Directory of Open Access Journals (Sweden)
Jaegle Felix
2013-01-01
Full Text Available Discontinuous Galerkin methods have become a powerful tool for approximating the solution of compressible flow problems. Their direct use for two-phase flow problems with phase transformation is not straightforward because this type of flows requires a detailed tracking of the phase front. We consider the fronts in this contribution as sharp interfaces and propose a novel multiscale approach. It combines an efficient high-order Discontinuous Galerkin solver for the computation in the bulk phases on the macro-scale with the use of a generalized Riemann solver on the micro-scale. The Riemann solver takes into account the effects of moderate surface tension via the curvature of the sharp interface as well as phase transformation. First numerical experiments in three space dimensions underline the overall performance of the method.
Measurement of the surface tension by the method of maximum gas bubble pressure
International Nuclear Information System (INIS)
Dugne, Jean
1971-01-01
A gas bubble method for measuring surface tension was studied. Theoretical investigations demonstrated that the maximum pressure can be represented by the envelope of a certain family of curves and that the physical nature of the capillary tube imposes an upper limit to its useful radius. With a given tube and a specified liquid, the dynamic evolution of the gas bubble depends only upon the variation of the mass of gas contained with time; this fact may restrict the choice of tubes. The use of one single tube requires important corrections. Computer treatment of the problem led to some accurate equations for calculating γ. Schroedinger equations and Sudgen's table are examined. The choice of tubes, the necessary corrections, density measurement, and the accuracy attainable are discussed. Experiments conducted with water and mercury using the sessile drop method and continuous recording of the pressure verified the theoretical ideas. (author) [fr
Beatrici, Anderson; Santos Baptista, Leandra; Mauro Granjeiro, José
2018-03-01
Regenerative Medicine comprises the Biotechnology, Tissue Engineering and Biometrology for stem cell therapy. Starting from stem cells extracted from the patient, autologous implant, these cells are cultured and differentiated into other tissues, for example, articular cartilage. These cells are reorganized into microspheres (cell spheroids). Such tissue units are recombined into functional tissues constructs that can be implanted in the injured region for regeneration. It is necessary the biomechanical characterization of these constructed to determine if their properties are similar to native tissue. In this study was carried out the modeling of the calculation of uncertainty of the surface tension of cellular spheroids with the use of the Young-Laplace equation. We obtained relative uncertainties about 10%.
Investigations of surface-tension effects due to small-scale complex boundaries
Feng, Jiansheng
In this Ph.D. dissertation, we have investigated some important surface-tension phenomena including capillarity, wetting, and wicking. We mainly focus on the geometric aspects of these problems, and to learn about how structures affect properties. . In the first project (Chapter 2), we used numerical simulations and experiments to study the meniscus of a fluid confined in capillaries with complicated cross-sectional geometries. In the simulations, we computed the three-dimensional shapes of the menisci formed in polygonal and star-shaped capillaries with sharp or rounded corners. Height variations across the menisci were used to quantify the effect of surface tension. Analytical solutions were derived for all the cases where the cross-sectional geometry was a regular polygon or a regular star-shape. Power indices that characterize the effects of corner rounding were extracted from simulation results. These findings can serve as guide for fabrications of unconventional three-dimensional structures in Capillary Force Lithography experiments. Experimental demonstrations of the working principle was also performed. Although quantitative matching between simulation and experimental results was not achieved due to the limitation of material properties, clear qualitative trends were observed and interesting three-dimensional nano-structures were produced. A second project (Chapter 3) focused on developing techniques to produce three-dimensional hierarchically structured superhydrophobic surfaces with high aspect ratios. We experimented with two different high-throughput electron-beam-lithography processes featuring single and dual electron-beam exposures. After a surface modification procedure with a hydrophobic silane, the structured surfaces exhibited two distinct superhydrophobic behaviors---high and low adhesion. While both types of superhydrophobic surfaces exhibited very high (approximately 160° water advancing contact angles, the water receding contact angles on
Bogan, Denis
1999-01-01
Laboratory measurements have been carried out to determine low temperature chemical rate coefficients of ethynyl radical (C2H) for the atmospheres of the outer planets and their satellites. This effort is directly related to the Cassini mission which will explore Saturn and Titan. A laser-based photolysis/infrared laser probe setup was used to measure the temperature dependence of kinetic rate coefficients from approx. equal to 150 to 350 K for C2H radicals with H2, C2H2, CH4, CD4, C2H4, C2H6, C3H8, n-C4H10, i-C4H10, neo-C5H12, C3H4 (methylacetylene and allene), HCN, and CH3CN. The results revealed discrepancies of an order of magnitude or more compared with the low temperature rate coefficients used in present models. A new Laval nozzle, low Mach number supersonic expansion kinetics apparatus has been constructed, resulting in the first measurements of neutral C2H radical kinetics at 90 K and permitting studies on condensable gases with insufficient vapor pressure at low temperatures. New studies of C 2H with acetylene have been completed.
Spreading of oil films on water in the surface tension regime
Energy Technology Data Exchange (ETDEWEB)
Camp, D.W.
1985-01-01
Surface tension forces will cause an oil to spread over water if the tension of the oil film (the summed surface and interfacial tensions for bulk oil films, or the equilibrium spreading tension for monomolecular films) is less than the surface tension of water. For oil films spreading in a 40 cm long channel, measurements are made of leading edge position and lateral profiles of film thickness, velocity, and tension as a function of time. Measurements of the tension profiles, important for evaluating proposed theories, is made possible by the development of a new technique based on the Wilhelmy method. The oils studied were silicones, fatty acids and alcohols, and mixtures of surfactants in otherwise nonspreading oils. The single-component oils show an acceleration zone connecting a slow-moving inner region with a fast-moving leading monolayer. The dependence of film tension on film thickness for spreading single-component oils often differs from that at equilibrium. The mixtures show a bulk oil film configuration which extends to the leading edge and have velocity profiles which increase smoothly. The theoretical framework, similarity transformation, and asymptotic solutions of Foda and Cox for single-component oils were shown to be valid. An analysis of spreading surfactant-oil mixtures is developed which allows them to be treated under this framework. An easily-used semi-empirical model is proposed which allows them to be treated under this framework. An easily-used semi-empirical model is proposed which allows accurate prediction of detailed spreading behavior for any spreading oil.
Directory of Open Access Journals (Sweden)
Shantonu Biswas
2016-03-01
Full Text Available This publication provides an overview and discusses some challenges of surface tension directed fluidic self-assembly of semiconductor chips which are transported in a liquid medium. The discussion is limited to surface tension directed self-assembly where the capture, alignment, and electrical connection process is driven by the surface free energy of molten solder bumps where the authors have made a contribution. The general context is to develop a massively parallel and scalable assembly process to overcome some of the limitations of current robotic pick and place and serial wire bonding concepts. The following parts will be discussed: (2 Single-step assembly of LED arrays containing a repetition of a single component type; (3 Multi-step assembly of more than one component type adding a sequence and geometrical shape confinement to the basic concept to build more complex structures; demonstrators contain (3.1 self-packaging surface mount devices, and (3.2 multi-chip assemblies with unique angular orientation. Subsequently, measures are discussed (4 to enable the assembly of microscopic chips (10 μm–1 mm; a different transport method is introduced; demonstrators include the assembly of photovoltaic modules containing microscopic silicon tiles. Finally, (5 the extension to enable large area assembly is presented; a first reel-to-reel assembly machine is realized; the machine is applied to the field of solid state lighting and the emerging field of stretchable electronics which requires the assembly and electrical connection of semiconductor devices over exceedingly large area substrates.
Zhelezny, Vitaly; Geller, Vladimir; Semenyuk, Yury; Nikulin, Artem; Lukianov, Nikolai; Lozovsky, Taras; Shymchuk, Mykola
2018-03-01
This paper presents results of an experimental study of the density, saturated vapor pressure, surface tension and viscosity of Al_2O_3 nanoparticle colloidal solutions in isopropyl alcohol. Studies of the thermophysical properties of nanofluids were performed at various temperatures and concentrations of Al_2O_3 nanoparticles. The paper gives considerable attention to a turbidimetric analysis of the stability of nanofluid samples. Samples of nanofluids remained stable over the range of parameters of the experiments, ensuring the reliability of the thermophysical property data for the Al_2O_3 nanoparticle colloidal solutions in isopropyl alcohol. The studies show that the addition of Al_2O_3 nanoparticles leads to an increase of the density, saturated vapor pressure and viscosity, as well as a decrease for the surface tension of isopropyl alcohol. The information reported in this paper on the various thermophysical properties for the isopropyl alcohol/Al_2O_3 nanoparticle model system is useful for the development of thermodynamically consistent models for predicting properties of nanofluids and correct modeling of the heat exchange processes.
Effect of surface tension on the behavior of adhesive contact based on Lennard-Jones potential law
Zhu, Xinyao; Xu, Wei
2018-02-01
The present study explores the effect of surface tension on adhesive contact behavior where the adhesion is interpreted by long-range intermolecular forces. The adhesive contact is analyzed using the equivalent system of a rigid sphere and an elastic half space covered by a membrane with surface tension. The long-range intermolecular forces are modeled with the Lennard‒Jones (L‒J) potential law. The current adhesive contact issue can be represented by a nonlinear integral equation, which can be solved by Newton‒Raphson method. In contrast to previous studies which consider intermolecular forces as short-range, the present study reveals more details of the features of adhesive contact with surface tension, in terms of jump instabilities, pull-off forces, pressure distribution within the contact area, etc. The transition of the pull-off force is not only consistent with previous studies, but also presents some new interesting characteristics in the current situation.
Yu, Fengyi; Wei, Yanhong
2018-05-01
The effects of surface tension anisotropy and welding parameters on initial instability dynamics during gas tungsten arc welding of an Al-alloy are investigated by a quantitative phase-field model. The results show that the surface tension anisotropy and welding parameters affect the initial instability dynamics in different ways during welding. The surface tension anisotropy does not influence the solute diffusion process but does affect the stability of the solid/liquid interface during solidification. The welding parameters affect the initial instability dynamics by varying the growth rate and thermal gradient. The incubation time decreases, and the initial wavelength remains stable as the welding speed increases. When welding power increases, the incubation time increases and the initial wavelength slightly increases. Experiments were performed for the same set of welding parameters used in modeling, and the results of the experiments and simulations were in good agreement.
Khalil, Omar S; Yeh, Shu-Jen; Lowery, Michael G; Wu, Xiaomao; Hanna, Charles F; Kantor, Stanislaw; Jeng, Tzyy-Wen; Kanger, Johannes S; Bolt, Rene A; de Mul, Frits F
2003-04-01
We determine temperature effect on the absorption and reduced scattering coefficients (mu(a) and mu(s)(')) of human forearm skin. Optical and thermal simulation data suggest that mu( a) and mu(s)(') are determined within a temperature-controlled depth of approximately 2 mm. Cutaneous mu(s)(') change linearly with temperature. Change in mu(a) was complex and irreversible above body normal temperatures. Light penetration depth (delta) in skin increased on cooling, with considerable person-to-person variations. We attribute the effect of temperature on mu(s)(') to change in refractive index mismatch, and its effect on mu(a) to perfusion changes. The reversible temperature effect on mu (s)(' ) was maintained during more than 90 min. contact between skin and the measuring probe, where temperature was modulated between 38 and 22 degrees C for multiple cycles While temperature modulated mu(s)(' ) instantaneously and reversibly, mu(a) exhibited slower response time and consistent drift. There was a statistically significant upward drift in mu(a) and a mostly downward drift in mu( s)(') over the contact period. The drift in temperature-induced fractional change in mu(s)(') was less statistically significant than the drift in mu(s)('). Deltamu( s)(') values determined under temperature modulation conditions may have less nonspecific drift than mu(s)(') which may have significance for noninvasive determination of analytes in human tissue.
Assessment of the crossflow loss coefficient in Very High Temperature Reactor core - 15338
International Nuclear Information System (INIS)
Lee, S.N.; Tak, N.I.; Kim, M.H.; Noh, J.M.
2015-01-01
The Very High Temperature Reactor (VHTR) is a helium gas cooled and graphite moderated reactor. It was chosen as one of the Gen-4 reactors owing to its inherent safety. Various researches for prismatic gas-cooled reactors have been conducted for efficient and safe use. The prismatic VHTR consists of vertically stacked fuel blocks. Between the vertical fuel blocks, there is cross gap because of manufacturing tolerance or graphite change during the operation. This cross gap changes the coolant flow path, called a crossflow, which may affect the fuel temperature. Various tests and numerical studies have been conducted to predict the crossflow and loss coefficient. In the present study, the CFD calculation is conducted to draw the loss coefficient, and compared with Groehn, Kaburaki and General Atomics (GA) correlations. The results of the Groehn and Kaburaki correlations tend to decrease as the gap size increases, whereas the data of GA show the opposite. The loss coefficient given by the CFD calculation tends to maintain the regular value without regard to the gap size for the standard fuel block, like the Groehn correlation. However, the loss coefficient of the control fuel block increases as the gap size widens, like the GA results
Energy Technology Data Exchange (ETDEWEB)
Zou, C.Y.; Cai, X.Z.; Jiang, D.Z.; Yu, C.G.; Li, X.X.; Ma, Y.W.; Han, J.L. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); CAS Center for Excellence in TMSR Energy System, Chinese Academy of Sciences, Shanghai 201800 (China); Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Chinese Academy of Sciences, Shanghai 201800 (China); Chen, J.G., E-mail: chenjg@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); CAS Center for Excellence in TMSR Energy System, Chinese Academy of Sciences, Shanghai 201800 (China); Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Chinese Academy of Sciences, Shanghai 201800 (China)
2015-01-15
Highlights: • The temperature feedback coefficient with different moderation ratios for TMSR in thermal neutron region is optimized. • The breeding ratio and doubling time of a thermal TMSR with three different reprocessing schemes are analyzed. • The smaller hexagon size and larger salt fraction with more negative feedback coefficient can better satisfy the safety demands. • A shorter reprocessing time can achieve a better breeding ratio in a thermal TMSR. • The graphite moderator lifespan is compared with other MSRs and discussed. - Abstract: Molten salt reactor (MSR) has fascinating features: inherent safety, no fuel fabrication, online fuel reprocessing, etc. However, the graphite moderated MSR may present positive feedback coefficient which has severe implications for the transient behavior during operation. In this paper, the feedback coefficient and the breeding ratio are optimized based on the fuel-to-graphite ratio variation for a thorium based MSR (TMSR). A certain thermal core with negative feedback coefficient and relative high initial breeding ratio is chosen for the reprocessing scheme analysis. The breeding performances for the TMSR under different online fuel reprocessing efficiencies and frequencies are evaluated and compared with other MSR concepts. The results indicate that the thermal TMSR can get a breeding ratio greater than 1.0 with appropriate reprocessing scheme. The low fissile inventory in thermal TMSR leads to a short doubling time and low transuranic (TRU) inventory. The lifetime of graphite used for the TMSR is also discussed.
Calculation of fuel and moderator temperature coefficients in APR1400 nuclear reactor by MVP code
International Nuclear Information System (INIS)
Pham Tuan Nam; Le Thi Thu; Nguyen Huu Tiep; Tran Viet Phu
2014-01-01
In this project, these fuel and moderator temperature coefficients were calculated in APR1400 nuclear reactor by MVP code. APR1400 is an advanced water pressurized reactor, that was researched and developed by Korea Experts, its electric power is 1400 MW. The neutronics calculations of full core is very important to analysis and assess a reactor. Results of these calculation is input data for thermal-hydraulics calculations, such as fuel and moderator temperature coefficients. These factors describe the self-safety characteristics of nuclear reactor. After obtaining these reactivity parameters, they were used to re-run the thermal hydraulics calculations in LOCA and RIA accidents. These thermal-hydraulics results were used to analysis effects of reactor physics parameters to thermal hydraulics situation in nuclear reactors. (author)
RADIAL FORCE IMPACT ON THE FRICTION COEFFICIENT AND TEMPERATURE OF A SELF-LUBRICATING PLAIN BEARING
Directory of Open Access Journals (Sweden)
Nada Bojić
2017-12-01
Full Text Available Self-lubricating bearings are available in spherical, plain, flanged journal, and rod end bearing configurations. They were originally developed to eliminate the need for re-lubrication, to provide lower torque and to solve application problems where the conventional metal-to-metal bearings would not perform satisfactorily, for instance, in the presence of high frequency vibrations. Among the dominant tribological parameters of the self-lubricating bearing, two could be singled out: the coefficient of friction and temperature. To determine these parameters, an experimental method was applied in this paper. By using this method, the coefficient of friction and temperature were identified and their correlation was established. The aim of this research was to determine the effect of radial force on tribological parameters in order to predict the behavior of sliding bearings with graphite in real operating conditions.
Directory of Open Access Journals (Sweden)
Ramalingam Anantharaj
2011-01-01
Full Text Available Density, surface tension and refractive index were determined for the binary mixture of catalytic deactivated compounds with 1-ethyl-3-methylimidazolium thiocyanate {[EMIM][SCN]} at temperature of (298.15 to 323.15 K. For all the compounds with ILs, the densities varied linearly in the entire mole fraction with increasing temperature. From the obtained data, the excess molar volume and deviation of surface tension and refractive index have been calculated. A strong interaction was found between similar (cation-thiophene or cation-pyrrole compounds. The interaction of IL with dissimilar compounds such as indoline and quinoline and other multiple ring compounds was found to strongly depend on the composition of IL at any temperatures. For the mixtures, the surface tension decreases in the order of: thiophene > quinoline > pyridine > indoline > pyrrole > water. In general from the excess volume studies, the IL-sulphur/nitrogen mixture has stronger interaction as compared to IL-IL, thiophene-thiophene or pyrrole-pyrrole interaction. The deviation of surface tension was found to be inversely proportional to deviation of refractive index. The quantum chemical based COSMO-RS was used to predict the non-ideal liquid phase activity coefficient for all mixtures. It indicated an inverse relation between activity coefficient and excess molar volumes.
International Nuclear Information System (INIS)
Thomas, J.R. Jr.; Adams, J.T.
1994-01-01
A neural network was trained with data for the frequency response function between in-core neutron noise and core-exit thermocouple noise in a pressurized water reactor, with the moderator temperature coefficient (MTC) as target. The trained network was subsequently used to predict the MTC at other points in the same fuel cycle. Results support use of the method for operating pressurized water reactors provided noise data can be accumulated for several fuel cycles to provide a training base
International Nuclear Information System (INIS)
Engle, W.W. Jr.; Williams, L.R.
1994-07-01
This report provides documentation of a series of calculations performed in 1991 in order to provide input for the High Flux Isotope Reactor Safety Analysis Report. In particular, temperature and void reactivity coefficients were calculated for beginning-of-life, end-of-life, and xenon equilibrium (29 h) conditions. Much of the data used to prepare the computer models for these calculations was derived from the original HFIR nuclear design study
Pendent_Drop: An ImageJ Plugin to Measure the Surface Tension from an Image of a Pendent Drop
Directory of Open Access Journals (Sweden)
Adrian Daerr
2016-01-01
Full Text Available The pendent drop method for surface tension measurement consists in analysing the shape of an axisymmetric drop hanging from a capillary tube. This software is an add-on for the public domain image processing software ImageJ which matches a theoretical profile to the contour of a pendent drop, either interactively or by automatically minimising the mismatch. It provides an estimate of the surface tension, drop volume and surface area from the best matching parameters. It can be used in a headless setup. It is hosted on http://fiji.sc/List_of_update_sites with the source code on https://github.com/adaerr/pendent-drop
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.
Temperature-Dependent Rate Coefficients for the Reaction of CH2OO with Hydrogen Sulfide.
Smith, Mica C; Chao, Wen; Kumar, Manoj; Francisco, Joseph S; Takahashi, Kaito; Lin, Jim Jr-Min
2017-02-09
The reaction of the simplest Criegee intermediate CH 2 OO with hydrogen sulfide was measured with transient UV absorption spectroscopy in a temperature-controlled flow reactor, and bimolecular rate coefficients were obtained from 278 to 318 K and from 100 to 500 Torr. The average rate coefficient at 298 K and 100 Torr was (1.7 ± 0.2) × 10 -13 cm 3 s -1 . The reaction was found to be independent of pressure and exhibited a weak negative temperature dependence. Ab initio quantum chemistry calculations of the temperature-dependent reaction rate coefficient at the QCISD(T)/CBS level are in reasonable agreement with the experiment. The reaction of CH 2 OO with H 2 S is 2-3 orders of magnitude faster than the reaction with H 2 O monomer. Though rates of CH 2 OO scavenging by water vapor under atmospheric conditions are primarily controlled by the reaction with water dimer, the H 2 S loss pathway will be dominated by the reaction with monomer. The agreement between experiment and theory for the CH 2 OO + H 2 S reaction lends credence to theoretical descriptions of other Criegee intermediate reactions that cannot easily be probed experimentally.
Lankford, Jr., James
1988-01-01
A method for producing a stable ceramic composition having a surface with a low friction coefficient and high wear resistance at high operating temperatures. A first deposition of a thin film of a metal ion is made upon the surface of the ceramic composition and then a first ion implantation of at least a portion of the metal ion is made into the near surface region of the composition. The implantation mixes the metal ion and the ceramic composition to form a near surface composite. The near surface composite is then oxidized sufficiently at high oxidizing temperatures to form an oxide gradient layer in the surface of the ceramic composition.
The temperature coefficient of the resonance integral for uranium metal and oxide
Energy Technology Data Exchange (ETDEWEB)
Blomberg, P; Hellstrand, E; Homer, S
1960-06-15
The temperature coefficient of the resonance integral in uranium metal and oxide has been measured over a wide temperature range for rods with three different diameters. The results for metal agree with most earlier results from activation measurements but differ as much as a factor of two from results obtained with reactivity methods. For oxide only one measurement has been reported recently. Our value is considerably lower than the result of that measurement. The experiments will continue in order to find the reason for the large discrepancy mentioned above.
The temperature coefficient of the resonance integral for uranium metal and oxide
International Nuclear Information System (INIS)
Blomberg, P.; Hellstrand, E.; Homer, S.
1960-06-01
The temperature coefficient of the resonance integral in uranium metal and oxide has been measured over a wide temperature range for rods with three different diameters. The results for metal agree with most earlier results from activation measurements but differ as much as a factor of two from results obtained with reactivity methods. For oxide only one measurement has been reported recently. Our value is considerably lower than the result of that measurement. The experiments will continue in order to find the reason for the large discrepancy mentioned above
Leone, Stephen R.
1995-01-01
The objectives of the research are to measure low temperature laboratory rate coefficients for key reactions relevant to the atmospheres of Titan and Saturn. These reactions are, for example, C2H + H2, CH4, C2H2, and other hydrocarbons which need to be measured at low temperatures, down to approximately 150 K. The results of this work are provided to NASA specialists who study modeling of the hydrocarbon chemistry of the outer planets. The apparatus for this work consists of a pulsed laser photolysis system and a tunable F-center probe laser to monitor the disappearance of C2H. A low temperature cell with a cryogenic circulating fluid in the outer jacket provides the gas handling system for this work. These elements have been described in detail in previous reports. Several new results are completed and the publications are just being prepared. The reaction of C2H with C2H2 has been measured with an improved apparatus down to 154 K. An Arrhenius plot indicates a clear increase in the rate coefficient at the lowest temperatures, most likely because of the long-lived (C4H3) intermediate. The capability to achieve the lowest temperatures in this work was made possible by construction of a new cell and addition of a multipass arrangement for the probe laser, as well as improvements to the laser system.
The effect of core configuration on temperature coefficient of reactivity in IRR-1
Energy Technology Data Exchange (ETDEWEB)
Bettan, M.; Silverman, I.; Shapira, M.; Nagler, A. [Soreq Nuclear Research Center, Yavne (Israel)
1997-08-01
Experiments designed to measure the effect of coolant moderator temperature on core reactivity in an HEU swimming pool type reactor were performed. The moderator temperature coefficient of reactivity ({alpha}{sub {omega}}) was obtained and found to be different in two core loadings. The measured {alpha}{sub {omega}} of one core loading was {minus}13 pcm/{degrees}C at the temperature range of 23-30{degrees}C. This value of {alpha}{sub {omega}} is comparable to the data published by the IAEA. The {alpha}{sub {omega}} measured in the second core loading was found to be {minus}8 pcm/{degrees}C at the same temperature range. Another phenomenon considered in this study is core behavior during reactivity insertion transient. The results were compared to a core simulation using the Dynamic Simulator for Nuclear Power Plants. It was found that in the second core loading factors other than the moderator temperature influence the core reactivity more than expected. These effects proved to be extremely dependent on core configuration and may in certain core loadings render the reactor`s reactivity coefficient undesirable.
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.
Re-evaluation of SiC permeation coefficients at high temperatures
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Yasushi, E-mail: yama3707@kansai-u.ac.jp [Faculty of Engineering Science, Kansai Univ., Yamate-cho, Suita, Osaka 564-8680 (Japan); Murakami, Yuichiro; Yamaguchi, Hirosato; Yamamoto, Takehiro; Yonetsu, Daigo [Faculty of Engineering Science, Kansai Univ., Yamate-cho, Suita, Osaka 564-8680 (Japan); Noborio, Kazuyuki [Hydrogen Isotope Research Center, Univ. of Toyama, Toyama, Toyama 930-8555 (Japan); Konishi, Satoshi [Institute of Advanced Energy, Kyoto Univ., Gokasho, Uji, Kyoto 611-0011 (Japan)
2016-11-01
Highlights: • The deuterium permeation coefficients of CVD-SiC at 600–950 °C were evaluated. • The wraparound flow was reduced to less than 1/100th of the permeation flow. • CVD-SiC materials are very effective as hydrogen isotope permeation barriers. - Abstract: Since 2007, our group has studied the deuterium permeation and diffusion coefficients for SiC materials at temperatures above 600 °C as a means of evaluating the tritium inventory and permeation in fusion blankets. During such measurements, control and evaluation of the wraparound flow through the sample holder are important, and so the heated sample holder is enclosed by a glass tube and kept under vacuum during experimental trials. However, detailed studies regarding the required degree of vacuum based on model calculations have shown that the wraparound flow is much larger than expected, and so can affect measurements at high temperatures. We therefore modified the measurement apparatus based on calculations involving reduced pressure in the glass tube, and are now confident that the measurement error is only several percent, even at 950 °C. In this paper, recent experimental results obtained with a chemical vapor deposition (CVD)-SiC sample over the temperature range of 600–950 °C are presented, showing that the permeation coefficient for CVD-SiC is more than three orders of magnitude smaller than that for stainless steel (SS316) at 600 °C, and that at 950 °C, the coefficient for CVD-SiC is almost equal to that for SUS316 at 550 °C.
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)
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.
Two-temperature transport coefficients of SF6–N2 plasma
International Nuclear Information System (INIS)
Yang, Fei; Chen, Zhexin; Wu, Yi; Rong, Mingzhe; Wang, Chunlin; Guo, Anxiang; Liu, Zirui
2015-01-01
Sulfur hexafluoride (SF 6 ) is widely adopted in electric power industry, especially in high-voltage circuit breakers and gas-insulated switchgear. However, the use of SF 6 is limited by its high liquidation temperature and high global warming potential. Recently, research shows SF 6 –N 2 mixture, which shows environmental friendliness and good electrical properties, may be a feasible substitute for pure SF 6 . This paper is devoted to the calculation of and transport coefficients of SF 6 –N 2 mixture under both LTE (local thermodynamic equilibrium) and non-LTE condition. The two–temperature mass action law was used to determine the composition. The transport coefficients were calculated by classical Chapman–Enskog method simplified by Devoto. The thermophysical properties are presented for electron temperatures of 300–40 000 K, ratios of electron to heavy species temperature of 1–10 and N 2 mole fraction of 0%–100% at atmospheric pressure. The ionization processes under both LTE and non-LTE have been discussed. The results show that deviations from local thermodynamic equilibrium significantly affect the properties of SF 6 –N 2 plasma, especially before the plasma is fully ionized. The different influence of N 2 on properties for SF 6 –N 2 plasma in and out of LTE has been found. The results will serve as reliable reference data for computational simulation of the behavior of SF 6 –N 2 plasmas
Pishkar, Leila; Taheri, Saba; Makarem, Somayeh; Alizadeh Zeinabad, Hojjat; Rahimi, Arash; Saboury, Ali Akbar; Falahati, Mojtaba
2017-02-01
In this study, a novel method to probe molecular interactions and binding of human hemoglobin (Hb) with nanodiamond (ND) was introduced based on the surface tension measurement. This method complements conventional techniques, which are basically done by zeta potential and dynamic light scattering (DLS) measurements, near and far circular dichroism (CD) spectroscopy, intrinsic and extrinsic fluorescence spectroscopy. Addition of ND to Hb solution increased the surface tension value of Hb-ND complex relative to those of Hb and ND molecules. The zeta potential values reveled that Hb and ND provide identical charge distribution at pH 7.5. DLS measurements demonstrated that Hb, ND, and ND-Hb complex have hydrodynamic radiuses of 98.37 ± 4.57, 122.07 ± 7.88 nm and 62.27 ± 3.70 at pH of 7.5 respectively. Far and near UV-CD results indicated the loss of α-helix structure and conformational changes of Hb, respectively. Intrinsic fluorescence data demonstrated that the fluorescence quenching of Hb by ND was the result of the static quenching. The hydrophobic interaction plays a pivotal role in the interaction of ND with Hb. Fluorescence intensity changes over time revealed conformational change of Hb continues after the mixing of the components (Hb-ND) till 15 min, which is indicative of the denaturation of the Hb relative to the protein control. Extrinsic fluorescence data showed a considerable enhancement of the ANS fluorescence intensity of Hb-ND system relative to the Hb till 60 nM of ND, likely persuaded by greater exposure of nonpolar residues of Hb hydrophobic pocket. The remarkable decrease in T m value of Hb in Hb-ND complex exhibits interaction of Hb with ND conducts to conformational changes of Hb. This study offers consequential discrimination into the interaction of ND with proteins, which may be of significance for further appeal of these nanoparticles in biotechnology prosecution.
Zehnder, Matthias; Schicht, Olivier; Sener, Beatrice; Schmidlin, Patrick
2005-08-01
The aim of this study was to evaluate the effect of reducing surface tension in endodontic chelator solutions on their ability to remove calcium from instrumented root canals. Aqueous solutions containing 15.5% EDTA, 10% citric acid, or 18% 1- hydroxyethylidene-1, 1-bisphosphonate (HEBP) were prepared with and without 1% (wt/wt) polysorbate (Tween) 80 and 9% propylene glycol. Surface tension in these solutions was measured using the Wilhelmy method. Sixty-four extracted, single-rooted human teeth of similar length were instrumented and irrigated with a 1% sodium hypochlorite solution and then randomly assigned (n = 8 per group) to receive a final one-minute rinse with 5 ml of test solutions, water, or the pure aqueous Tween/propylene glycol solution. Calcium concentration in eluates was measured using atomic absorption spectrometry. Incorporation of wetting agents resulted in a reduction of surface tension values by approximately 50% in all tested solutions. However, none of the solutions with reduced surface tension chelated more calcium from canals than their pure counterparts (p > 0.05).
Danov, Krassimir D.; Stanimirova, Rumyana D.; Kralchevsky, Peter A.; Marinova, Krastanka G.; Stoyanov, Simeon D.; Blijdenstein, Theodorus B.J.; Cox, Andrew R.; Pelan, Eddie G.
2016-01-01
Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are
Huck-Iriart, Cristia´n; De-Candia, Ariel; Rodriguez, Javier; Rinaldi, Carlos
2016-01-01
In this work, we described an image processing procedure for the measurement of surface tension of the air-liquid interface using isothermal capillary action. The experiment, designed for an undergraduate course, is based on the analysis of a series of solutions with diverse surfactant concentrations at different ionic strengths. The objective of…
Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited
Energy Technology Data Exchange (ETDEWEB)
Mulero, A [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Galan, C [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Cuadros, F [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain)
2003-04-16
We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs.
Rate coefficients for the reactions of ions with polar molecules at interstellar temperatures
International Nuclear Information System (INIS)
Adams, N.G.; Smith, D.; Clary, D.C.
1985-01-01
A theory has been developed recently which predicts that the rate coefficients, k, for the reactions of ions with polar molecules at low temperatures will be much greater than the canonical value of 10 -9 cm 3 s -1 . The new theory indicates that k is greatest for low-lying rotational sates and increases rapidly with decreasing temperature. We refer to recent laboratory measurements which validate the theory, present calculated values of k for the reactions of H + 3 ions with several polar molecules, and discuss their significance to interstellar chemistry. For the reactions of ions with molecules having large dipole moments, we recommend that k values as large as 10 -7 cm 3 s -1 should be used in ion-chemical models of low-temperature interstellar clouds
International Nuclear Information System (INIS)
Povar, I.G.
1995-01-01
Equations describing the relation between temperature coefficient of ∂lnα/∂T complexing degree and the sum of changes in the enthalpy of complex formation of the composition M m L n δH mn multiplied by the weight coefficients k mm , are presented. A method to determine changes in the enthalpy of certain ΔH mm reactions from ∂lnα/∂T derivatives has been suggested. The best approximating equation from lnα/(T) dependence has been found. Errors of thus determined δH mm values are estimated and the results of calculation experiment for the system In 3+ -F - are provided. 10 refs., 2 figs., 3 tabs
International Nuclear Information System (INIS)
Seo, M; Shimamura, T; Furutani, T; Hasuo, M; Bahrim, C; Fujimoto, T
2003-01-01
Disalignment of neon excited atoms in the fine-structure 2p i levels (in Paschen notation) of the 2p 5 3p configuration is investigated in a helium-neon glow discharge at temperatures between 15 and 77 K. At several temperatures, we plot the disalignment rate as a function of the helium atom density for Ne* (2p 2 or 2p 7 ) + He(1s 2 ) collisions. The slope of this dependence gives the disalignment rate coefficient. For both collisions, the experimental data for the disalignment rate coefficient show a more rapid decrease with the decrease in temperature below 40 K than our quantum close-coupling calculations based on the model potential of Hennecart and Masnou-Seeuws (1985 J. Phys. B: At. Mol. Phys. 18 657). This finding suggests that the disalignment cross section rapidly decreases below a few millielectronvolts, in disagreement with our theoretical quantum calculations which predict a strong increase below 1 meV. The disagreement suggests that the long-range electrostatic potentials are significantly more repulsive than in the aforementioned model
The negative temperature coefficient resistivities of Ag2S-Ag core–shell structures
International Nuclear Information System (INIS)
Yu, Mingming; Liu, Dongzhi; Li, Wei; Zhou, Xueqin
2014-01-01
In this paper, the conductivity of silver nanoparticle films protected by 3-mercaptopropionic acid (Ag/MPA) has been investigated. When the nanoparticles were annealed in air at 200 °C, they converted to stable Ag 2 S-Ag core–shell structures. The mechanism for the formation of the Ag 2 S-Ag core–shell structures along with the compositional changes and the microstructural evolution of the Ag/MPA nanoparticles during the annealing process are discussed. It is proposed that the Ag 2 S-Ag core–shell structure was formed through a solid-state reduction reaction, in which the Ag + ions coming from Ag 2 S were reduced by sulfonate species and sulfur ions. The final Ag 2 S-Ag films display an exponentially decreased resistivity with increasing temperature from 25 to 170 °C. The negative temperature coefficient resistivity of Ag 2 S-Ag films can be adjusted by changing the S/Ag molar ratio used for the synthesis of the Ag/MPA nanoparticles, paving the way for the preparation of negative temperature-coefficient thermistors via printing technology for use in the electronics.
International Nuclear Information System (INIS)
Hussein, S.A.
1989-01-01
Conductivity type, carrier concentration and carrier mobility of InTe samples grown by Bridgman technique were determined by the Hall effect and electrical conductivity measurements. The study was performed in the temperature range 150-480 K. Two samples with different growth rate were used in the investigation. The samples under test were P-type conducting, in accordance with previous measurements of undoped material. The Hall coefficient was found to be isotropic yielding room temperature hole concentration in the range 10 15 -10 16 cm -3 . The hole mobilities of InTe samples were in the range 1.17 x 10 3 -2.06 x 10 3 cm 2 /V · sec at room temperature. The band-gap of InTe determined from Hall coefficient studies has been obtained equal to 0.34 eV. The scattering mechanism was checked, and the electrical properties were found to be sensitive to the crystal growth rate. (author)
Dynamics of two-phase interfaces and surface tensions: A density-functional theory perspective
Yatsyshin, Petr; Sibley, David N.; Duran-Olivencia, Miguel A.; Kalliadasis, Serafim
2016-11-01
Classical density functional theory (DFT) is a statistical mechanical framework for the description of fluids at the nanoscale, where the inhomogeneity of the fluid structure needs to be carefully accounted for. By expressing the grand free-energy of the fluid as a functional of the one-body density, DFT offers a theoretically consistent and computationally accessible way to obtain two-phase interfaces and respective interfacial tensions in a ternary solid-liquid-gas system. The dynamic version of DFT (DDFT) can be rigorously derived from the Smoluchowsky picture of the dynamics of colloidal particles in a solvent. It is generally agreed that DDFT can capture the diffusion-driven evolution of many soft-matter systems. In this context, we use DDFT to investigate the dynamic behaviour of two-phase interfaces in both equilibrium and dynamic wetting and discuss the possibility of defining a time-dependent surface tension, which still remains in debate. We acknowledge financial support from the European Research Council via Advanced Grant No. 247031 and from the Engineering and Physical Sciences Research Council of the UK via Grants No. EP/L027186 and EP/L020564.
Pressure and surface tension of solid-liquid interface using Tara zona density functional theory
International Nuclear Information System (INIS)
Moradi, M.; Kavosh Tehrani, M.
2001-01-01
The weighted density functional theory proposed by Tara zona is applied to study the solid-liquid interface. In the last two decades the weighted density functional became a useful tool to consider the properties of inhomogeneous liquids. In this theory, the role of the size of molecules or the particles of which the matter is composed, was found to be important. In this research we study a hard sphere fluid beside a hard wall. For this study the liquid is an inhomogeneous system. We use the definition of the direct correlation function as a second derivative of free energy with respect to the density. We use this definition and the definition of the weighting function, then we minimize the grand potential with respect to the density to get the Euler Lagrange equation and we obtain an integral equation to find the inhomogeneous density profile. The obtained density profile as a function of the distance from the wall, for different bulk density is pitted in three dimensions. We also calculate the pressure and compare it with the Carnahan-Starling results, and finally we obtained the surface tension at liquid-solid interface and compared it with the results of Monte Carlo simulation
Energy Technology Data Exchange (ETDEWEB)
Sing, Charles E. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Zwanikken, Jos W.; Olvera de la Cruz, Monica [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)
2015-01-21
Polymer mixtures such as blends or block copolymers are of great interest in energy applications and functional materials, and often, one or more of these species contain charges. The traditional fashion in which such materials are studied uses Self-Consistent Field Theory (SCFT) methods that incorporate electrostatics using Poisson-Boltzmann (PB) theory. We adapt a new and rigorous approach that does not rely on the mean-field assumptions inherent in the PB theory and instead uses Liquid State (LS) integral equation theory to articulate charge correlations that are completely neglected in PB. We use this theory to calculate phase diagrams for both blends and block copolyelectrolytes using SCFT-LS and demonstrate how their phase behavior is highly dependent on chain length, charge fraction, charge size, and the strength of Coulombic interactions. Beyond providing phase behavior of blends and block copolyelectrolytes, we can use this theory to investigate the interfacial properties such as surface tension and block copolyelectrolyte lamellar spacing. Lamellar spacing provides a way to directly compare the SCFT-LS theory to the results of experiments. SCFT-LS will provide conceptual and mathematical clarification of the role of charge correlations in these systems and aid in the design of materials based on charge polymers.
International Nuclear Information System (INIS)
Sing, Charles E.; Zwanikken, Jos W.; Olvera de la Cruz, Monica
2015-01-01
Polymer mixtures such as blends or block copolymers are of great interest in energy applications and functional materials, and often, one or more of these species contain charges. The traditional fashion in which such materials are studied uses Self-Consistent Field Theory (SCFT) methods that incorporate electrostatics using Poisson-Boltzmann (PB) theory. We adapt a new and rigorous approach that does not rely on the mean-field assumptions inherent in the PB theory and instead uses Liquid State (LS) integral equation theory to articulate charge correlations that are completely neglected in PB. We use this theory to calculate phase diagrams for both blends and block copolyelectrolytes using SCFT-LS and demonstrate how their phase behavior is highly dependent on chain length, charge fraction, charge size, and the strength of Coulombic interactions. Beyond providing phase behavior of blends and block copolyelectrolytes, we can use this theory to investigate the interfacial properties such as surface tension and block copolyelectrolyte lamellar spacing. Lamellar spacing provides a way to directly compare the SCFT-LS theory to the results of experiments. SCFT-LS will provide conceptual and mathematical clarification of the role of charge correlations in these systems and aid in the design of materials based on charge polymers
Pressure and surface tension of soild-liquid interface using Tarazona density functional theory
Directory of Open Access Journals (Sweden)
M. M.
2000-12-01
Full Text Available The weighted density functional theory proposed by Tarazona is applied to study the solid-liquid interface. In the last two decades the weighted density functional became a useful tool to consider the properties of inhomogeneous liquids. In this theory, the role of the size of molecules or the particles of which the matter is composed, was found to be important. In this resarch we study a hard sphere fluid beside a hard wall. For this study the liquid is an inhomogeneous system. We use the definition of the direct correlation function as a second derivative of free energy with respect to the density. We use this definition and the definition of the weighting function, then we minimize the grand potential with respect to the density to get the Euler Lagrange equation and we obtain an integral equation to find the inhomogeneous density profile. The obtained density profile as a function of the distance from the wall, for different bulk density is plotted in three dimensions. We also calculate the pressure and compare it with the Carnahan-starling results, and finally we obtained the surface tension at liquid-solid interface and compared it with the results of Monte Carlo simulation.
Pline, Alexander D.; Werner, Mark P.; Hsieh, Kwang-Chung
1991-01-01
The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the United States Microgravity Laboratory-1 (USML-1) Spacelab mission planned for June, 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electric, two dimensional Particle Image Velocimetry (PIV) technique called Particle Displacement Tracking (PDT), which uses a simple space domain particle tracking algorithm. Results using the ground based STDCE hardware, with a radiant flux heating mode, and the PDT system are compared to numerical solutions obtained by solving the axisymmetric Navier Stokes equations with a deformable free surface. The PDT technique is successful in producing a velocity vector field and corresponding stream function from the raw video data which satisfactorily represents the physical flow. A numerical program is used to compute the velocity field and corresponding stream function under identical conditions. Both the PDT system and numerical results were compared to a streak photograph, used as a benchmark, with good correlation.
A method for estimating the diffuse attenuation coefficient (KdPAR)from paired temperature sensors
Read, Jordan S.; Rose, Kevin C.; Winslow, Luke A.; Read, Emily K.
2015-01-01
A new method for estimating the diffuse attenuation coefficient for photosynthetically active radiation (KdPAR) from paired temperature sensors was derived. We show that during cases where the attenuation of penetrating shortwave solar radiation is the dominant source of temperature changes, time series measurements of water temperatures at multiple depths (z1 and z2) are related to one another by a linear scaling factor (a). KdPAR can then be estimated by the simple equation KdPAR ln(a)/(z2/z1). A suggested workflow is presented that outlines procedures for calculating KdPAR according to this paired temperature sensor (PTS) method. This method is best suited for conditions when radiative temperature gains are large relative to physical noise. These conditions occur frequently on water bodies with low wind and/or high KdPARs but can be used for other types of lakes during time periods of low wind and/or where spatially redundant measurements of temperatures are available. The optimal vertical placement of temperature sensors according to a priori knowledge of KdPAR is also described. This information can be used to inform the design of future sensor deployments using the PTS method or for campaigns where characterizing sub-daily changes in temperatures is important. The PTS method provides a novel method to characterize light attenuation in aquatic ecosystems without expensive radiometric equipment or the user subjectivity inherent in Secchi depth measurements. This method also can enable the estimation of KdPAR at higher frequencies than many manual monitoring programs allow.
Posa, Mihalj; Pilipović, Ana; Lalić, Mladena; Popović, Jovan
2011-02-15
Linear dependence between temperature (t) and retention coefficient (k, reversed phase HPLC) of bile acids is obtained. Parameters (a, intercept and b, slope) of the linear function k=f(t) highly correlate with bile acids' structures. Investigated bile acids form linear congeneric groups on a principal component (calculated from k=f(t)) score plot that are in accordance with conformations of the hydroxyl and oxo groups in a bile acid steroid skeleton. Partition coefficient (K(p)) of nitrazepam in bile acids' micelles is investigated. Nitrazepam molecules incorporated in micelles show modified bioavailability (depo effect, higher permeability, etc.). Using multiple linear regression method QSAR models of nitrazepams' partition coefficient, K(p) are derived on the temperatures of 25°C and 37°C. For deriving linear regression models on both temperatures experimentally obtained lipophilicity parameters are included (PC1 from data k=f(t)) and in silico descriptors of the shape of a molecule while on the higher temperature molecular polarisation is introduced. This indicates the fact that the incorporation mechanism of nitrazepam in BA micelles changes on the higher temperatures. QSAR models are derived using partial least squares method as well. Experimental parameters k=f(t) are shown to be significant predictive variables. Both QSAR models are validated using cross validation and internal validation method. PLS models have slightly higher predictive capability than MLR models. Copyright © 2010 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Kusy, A.
1987-01-01
Two types of elementary resistances in thick resistive films have been considered: (i) constriction resistance R/sub C/ determined by the bulk properties of conducting material and by the geometry of constriction, and (ii) barrier resistance R/sub B/ determined by the parameters of a thermally activated type of tunneling process and by the geometry of the metal-insulator-metal unit. On this basis a resistance network composed of a large number of the two types of resistances has been defined. The network has been considered as being equivalent to thick resistive film (TRF) from the point of view of the resistance and temperature coefficient of resistance (TCR). The parameters of this network have been evaluated by the computer-aided approximation of the experimental data found for RuO 2 -based TRFs. On the basis of the equations derived for the network as well as the results of the approximation process, it can be concluded that the small values of the network TCR result from the superposition of the TCR of the conducting component β/sub C/ and of the temperature coefficient of barrier resistance α/sub B/. In this superposition β/sub C/ is attenuated (by 1--2 orders of magnitude), while α/sub B/ is attenuated by only few percentages. The network has been found to be strongly barrier dominated
Two-temperature transport coefficients of SF{sub 6}–N{sub 2} plasma
Energy Technology Data Exchange (ETDEWEB)
Yang, Fei; Chen, Zhexin; Wu, Yi, E-mail: wuyic51@mail.xjtu.edu.cn; Rong, Mingzhe; Wang, Chunlin [State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Guo, Anxiang; Liu, Zirui [Electric Power Research Institute of State Grid Shaanxi Electric Power Company, Xian (China)
2015-10-15
Sulfur hexafluoride (SF{sub 6}) is widely adopted in electric power industry, especially in high-voltage circuit breakers and gas-insulated switchgear. However, the use of SF{sub 6} is limited by its high liquidation temperature and high global warming potential. Recently, research shows SF{sub 6}–N{sub 2} mixture, which shows environmental friendliness and good electrical properties, may be a feasible substitute for pure SF{sub 6}. This paper is devoted to the calculation of and transport coefficients of SF{sub 6}–N{sub 2} mixture under both LTE (local thermodynamic equilibrium) and non-LTE condition. The two–temperature mass action law was used to determine the composition. The transport coefficients were calculated by classical Chapman–Enskog method simplified by Devoto. The thermophysical properties are presented for electron temperatures of 300–40 000 K, ratios of electron to heavy species temperature of 1–10 and N{sub 2} mole fraction of 0%–100% at atmospheric pressure. The ionization processes under both LTE and non-LTE have been discussed. The results show that deviations from local thermodynamic equilibrium significantly affect the properties of SF{sub 6}–N{sub 2} plasma, especially before the plasma is fully ionized. The different influence of N{sub 2} on properties for SF{sub 6}–N{sub 2} plasma in and out of LTE has been found. The results will serve as reliable reference data for computational simulation of the behavior of SF{sub 6}–N{sub 2} plasmas.
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.
International Nuclear Information System (INIS)
Shieh, D.J.; Upadhyaya, B.R.; Sweeney, F.J.
1987-01-01
A new technique, based on the noise analysis of neutron detector and core-exit coolant temperature signals, is developed for monitoring the moderator temperature coefficient of reactivity in pressurized water reactors (PWRs). A detailed multinodal model is developed and evaluated for the reactor core subsystem of the loss-of-fluid test (LOFT) reactor. This model is used to study the effect of changing the sign of the moderator temperature coefficient of reactivity on the low-frequency phase angle relationship between the neutron detector and the core-exit temperature noise signals. Results show that the phase angle near zero frequency approaches - 180 deg for negative coefficients and 0 deg for positive coefficients when the perturbation source for the noise signals is core coolant flow, inlet coolant temperature, or random heat transfer
Directory of Open Access Journals (Sweden)
Cui X.G.
2009-01-01
Full Text Available To decrease the temperature coefficients of sintered Nd-Fe-B magnets, the influencing factors on temperature coefficients, especially the reversible temperature coefficient β of intrinsic coercivity Hcj, were analyzed. The results showed that the absolute value of β decreased with increasing Hcj and also the ratio of microstructure parameter c to Neff, indicating that the increase of magnetocrystalline anisotropy field HA and c/Neff can effectively decrease the absolute value of β. On the basis of this analysis, a sintered Nd-Fe-B magnet with a low temperature coefficient of Hcj was fabricated through composition design, and the value of β was only -0.385%/ºC in the temperature interval of 20-150ºC.
Analysis of Moderator Temperature Reactivity Coefficient of the PWR Core Using WIMS-ANL
International Nuclear Information System (INIS)
Tukiran; Rokhmadi
2007-01-01
The Moderator Temperature Reactivity Coefficient (MTRC) is an important parameter in design, control and safety, particularly in PWR reactor. It is then very important to validate any new processed library for an accurate prediction of this parameter. The objective of this work is to validate the newly WIMS library based on ENDF/B-VI nuclear data files, especially for the prediction of the MTRC parameter. For this purpose, it is used a set of light water moderated lattice experiments as the NORA experiment and R1-100H critical reactors, both of reactors using UO 2 fuel pellet. Analysis is used with WIMSD/4 lattice code with original cross section libraries and WIMS-ANL with ENDF/B-VI cross section libraries. The results showed that the moderator temperatures reactivity coefficients for the NORA reactor using original libraries is - 5.039E-04 %Δk/k/℃ but for ENDF/B-VI libraries is - 2.925E-03 %Δk/k/℃. Compared to the designed value of the reactor core, the difference is in the range of 1.8 - 3.8 % for ENDF/B-IV libraries. It can be concluded that for reactor safety and control analysis, it has to be used ENDF/B- VI libraries because the original libraries is not accurate any more. (author)
Olszacki, M.; Maj, C.; Bahri, M. Al; Marrot, J.-C.; Boukabache, A.; Pons, P.; Napieralski, A.
2010-06-01
Many today's microsystems like strain-gauge-based piezoresistive pressure sensors contain doped resistors. If one wants to predict correctly the temperature impact on the performance of such devices, the accurate data about the temperature coefficients of resistance (TCR) are essential. Although such data may be calculated using one of the existing mobility models, our experiments showed that we can observe the huge mismatch between the calculated and measured values. Thus, in order to investigate the TCR values, a set of the test structures that contained doped P-type resistors was fabricated. As the TCR value also depends on the doping profile shape, we decided to use the very thin, 340 nm thick SOI wafers in order to fabricate the quasi-uniformly doped silicon layers ranging from 2 × 1017 at cm-3 to 1.6 × 1019 at cm-3. The results showed that the experimental data for the first-order TCR are quite far from the calculated ones especially over the doping range of 1018-1019 at cm-3 and quite close to the experimental ones obtained by Bullis about 50 years ago for bulk silicon. Moreover, for the first time, second-order coefficients that were not very consistent with the calculations were obtained.
International Nuclear Information System (INIS)
Olszacki, M; Maj, C; Al Bahri, M; Marrot, J-C; Boukabache, A; Pons, P; Napieralski, A
2010-01-01
Many today's microsystems like strain-gauge-based piezoresistive pressure sensors contain doped resistors. If one wants to predict correctly the temperature impact on the performance of such devices, the accurate data about the temperature coefficients of resistance (TCR) are essential. Although such data may be calculated using one of the existing mobility models, our experiments showed that we can observe the huge mismatch between the calculated and measured values. Thus, in order to investigate the TCR values, a set of the test structures that contained doped P-type resistors was fabricated. As the TCR value also depends on the doping profile shape, we decided to use the very thin, 340 nm thick SOI wafers in order to fabricate the quasi-uniformly doped silicon layers ranging from 2 × 10 17 at cm −3 to 1.6 × 10 19 at cm −3 . The results showed that the experimental data for the first-order TCR are quite far from the calculated ones especially over the doping range of 10 18 –10 19 at cm −3 and quite close to the experimental ones obtained by Bullis about 50 years ago for bulk silicon. Moreover, for the first time, second-order coefficients that were not very consistent with the calculations were obtained.
Measurements of the fuel temperature coefficient of reactivity at Hinkley Point 'B': 1981
International Nuclear Information System (INIS)
George, T.A.
1982-03-01
Measurements of the fuel temperature coefficient of reactivity made at Hinkley Point 'B' AGR in 1981 are described. These measurements follow earlier tests reported in e.g. RD/B/N4846 and are part of a series of measurements designed to support theoretical estimates of the change of fuel temperature coefficient as a function of core irradiation. Low and high power measurements were made at a mean core irradiation of 1170GWD. As previously, the measurements at both power levels show agreement with theoretical predictions to within the estimated experimental errors. Recent measurements (mean core irradiation >500GWD) show evidence of a small systematic difference between measured and theoretical values with the experimental values being approximately equal to 0.1mN/ 0 C more positive than the theoretical ones. The measured value of αsub(U) at high power was -0.64+-0.10mN/ 0 C and the low power value, corrected theoretically to normal operating conditions, was also -0.64+-0.10mN/ 0 C. (author)
Directory of Open Access Journals (Sweden)
Ibrahim S. Khattab
2017-02-01
Full Text Available Density, viscosity, surface tension and molar volume of propylene glycol + water mixtures at 293, 298, 303, 308, 313, 318, and 323 K are reported, compared with the available literature data and the Jouyban–Acree model was used for mathematical correlation of the data. The mean relative deviation (MRD was used as an error criterion and the MRD values for data correlation of density, viscosity, surface tension and molar volume at different investigated temperatures are 0.1 ± 0.1%, 7.6 ± 6.4%, 3.4 ± 3.7%, and 0.4 ± 0.4%, respectively. The corresponding MRDs for the predicted properties after training the model using the experimental data at 298 K are 0.1 ± 0.2%, 12.8 ± 9.3%, 4.7 ± 4.1% and 0.6 ± 0.5%, respectively for density, viscosity, surface tension, and molar volume data.
Analytical method for estimating the thermal expansion coefficient of metals at high temperature
International Nuclear Information System (INIS)
Takamoto, S; Izumi, S; Nakata, T; Sakai, S; Oinuma, S; Nakatani, Y
2015-01-01
In this paper, we propose an analytical method for estimating the thermal expansion coefficient (TEC) of metals at high-temperature ranges. Although the conventional method based on quasiharmonic approximation (QHA) shows good results at low temperatures, anharmonic effects caused by large-amplitude thermal vibrations reduces its accuracy at high temperatures. Molecular dynamics (MD) naturally includes the anharmonic effect. However, since the computational cost of MD is relatively high, in order to make an interatomic potential capable of reproducing TEC, an analytical method is essential. In our method, analytical formulation of the radial distribution function (RDF) at finite temperature realizes the estimation of the TEC. Each peak of the RDF is approximated by the Gaussian distribution. The average and variance of the Gaussian distribution are formulated by decomposing the fluctuation of interatomic distance into independent elastic waves. We incorporated two significant anharmonic effects into the method. One is the increase in the averaged interatomic distance caused by large amplitude vibration. The second is the variation in the frequency of elastic waves. As a result, the TECs of fcc and bcc crystals estimated by our method show good agreement with those of MD. Our method enables us to make an interatomic potential that reproduces the TEC at high temperature. We developed the GEAM potential for nickel. The TEC of the fitted potential showed good agreement with experimental data from room temperature to 1000 K. As compared with the original potential, it was found that the third derivative of the wide-range curve was modified, while the zeroth, first and second derivatives were unchanged. This result supports the conventional theory of solid state physics. We believe our analytical method and developed interatomic potential will contribute to future high-temperature material development. (paper)
International Nuclear Information System (INIS)
Li Fei; Xu Zhuo; Wei Xiaoyong; Yao Xi
2009-01-01
The piezoelectric coefficients (d 33 , -d 31 , d 15 , g 33 , -g 31 , g 15 ) of soft and hard lead zirconate titanate ceramics were measured by the quasi-static and resonance methods, at temperatures from 20 to 300 0 C. The results showed that the piezoelectric coefficients d 33 , -d 31 and d 15 obtained by these two methods increased with increasing temperature for both hard and soft PZT ceramics, while the piezoelectric coefficients g 33 , -g 31 and g 15 decreased with increasing temperature for both hard and soft PZT ceramics. In this paper, the observed results were also discussed in terms of intrinsic and extrinsic contributions to piezoelectric response.
Evaluation of salivary surface tension in a cohort of young healthy adults.
Foglio-Bonda, P L; Laguini, E; Davoli, C; Pattarino, F; Foglio-Bonda, A
2018-03-01
To determine salivary pH, flow rate (FR) and surface tension (γs) in a cohort of 30 healthy young adults. To acquire cohort biological independent variables (age, gender, weight, height, medications, smoking, pathologies, and allergies) and to correlate them with pH, FR and γs obtained values. Evaluate the possible variation of the γs values during the time after the withdrawal and the influence of the operational abilities of the experimenting operators. Evaluate the relationship between γs, pH and FR and the dependence between pH and FR. Non-stimulated saliva samples were taken in four different time span, for three days, with a drooling method for 15 minutes. The saliva sample was analyzed, in terms of γs, by two different operators (OP1 and OP2), twice consecutive (γs-1 and γs-2) for a total of 360 measurements. The γs was calculated using the du Noüy method. The FR was evaluated by weighing technique and pH by pH indicator papers. The measurements of γs performed by two different operators (OP1, OP2) showed respectively average values of 46.46 mN/m and 43.45 mN/m, while the mean FR was 0.29 ± 0.13 mL/min and the average pH was 7.1 ± 0.43. There were no significant correlations between γs and the biological variables analyzed. We can consider as reference values, in a sample of young adults, γs 45.56 ± 6.51 mN/m.
Onaizi, Sagheer A
2018-03-01
The dynamic adsorption of the anionic biosurfactant, surfactin, at the air-water interface has been investigated in this work and compared to those of two synthetic surfactants: the anionic sodium dodecylbenzenesulfonate (SDBS) and the nonionic octaethylene glycol monotetradecyl ether (C 14 E 8 ). The results revealed that surfactin adsorption at the air-water interface is purely controlled by diffusion mechanism at the initial stage of the adsorption process (i.e., [Formula: see text]), but shifts towards a mixed diffusion-barrier mechanism when surface tension approaches equilibrium (i.e., [Formula: see text]) due to the development of an energy barrier for adsorption. Such energy barrier has been found to be a function of the surfactin bulk concentration (increases with increasing surfactin concentration) and it is estimated to be in the range of 1.8-9.5 kJ/mol. Interestingly, such a trend (pure diffusion-controlled mechanism at [Formula: see text] and mixed diffusion-barrier mechanism at [Formula: see text]) has been also observed for the nonionic C 14 E 8 surfactant. Unlike the pure diffusion-controlled mechanism of the initial surfactin adsorption, which was the case in the presence and the absence of the sodium ion (Na + ), SDBS showed a mixed diffusion-barrier controlled at both short and long time, with an energy barrier of 3.0-9.0 and 3.8-18.0 kJ/mol, respectively. Such finding highlights the nonionic-like adsorption mechanism of surfactin despite its negative charge.
Wu, You; Kharge, Angana Banerjee; Perlman, Carrie E
2014-10-01
With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0-20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7-10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity. Copyright © 2014 the American Physiological Society.
International Nuclear Information System (INIS)
M.S. Gruszkiewicz; D.A. Palmer
2006-01-01
While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl 2 , LiCl, and NaCl used as references, precise direct
Zemlyanova, A. Y.
2013-03-08
A problem of an interface crack between two semi-planes made out of different materials under an action of an in-plane loading of general tensile-shear type is treated in a semi-analytical manner with the help of Dirichlet-to-Neumann mappings. The boundaries of the crack and the interface between semi-planes are subjected to a curvature-dependent surface tension. The resulting system of six singular integro-differential equations is reduced to the system of three Fredholm equations. It is shown that the introduction of the curvature-dependent surface tension eliminates both classical integrable power singularity of the order 1/2 and an oscillating singularity present in a classical linear elasticity solutions. The numerical results are obtained by solving the original system of singular integro-differential equations by approximating unknown functions with Taylor polynomials. © 2013 The Author.
Estimation of Temperature Conductivity Coefficient Impact upon Fatigue Damage of Material
International Nuclear Information System (INIS)
Bibik, V; Galeeva, A
2015-01-01
In the paper we consider the peculiarities of adhesive wear of cutting tools. Simulation of heat flows in the cutting zone showed that, as thermal conduction and heat conductivity of tool material grow, the heat flows from the front and back surfaces to tool holder will increase and so, the temperature of the contact areas of the tool will lower. When estimating the adhesive wear rate of cemented-carbide tool under the cutting rates corresponding to the cutting temperature of up to 900 °C, it is necessary to take the fatigue character of adhesive wear into consideration. The process of accumulation and development of fatigue damage is associated with micro- and macroplastic flowing of material, which is determined by the processes of initiation, motion, generation, and elimination of line defects - dislocations. Density of dislocations grows with increase of the loading cycles amount and increase of load amplitude. Growth of dislocations density leads to loosening of material, formation of micro- and macrocracks. The heat capacity of material grows as the loosening continues. In the given paper the authors prove theoretically that temperature conductivity coefficient which is associated with heat capacity of material, decreases as fatigue wear grows. (paper)
Energy Technology Data Exchange (ETDEWEB)
Pitzer, K.S.
1979-09-01
It is shown that the properties of fully ionized aqueous electrolyte systems can be represented by relatively simple equations over wide ranges of composition. There are only a few systems for which data are available over the full range to fused salt. A simple equation commonly used for nonelectrolytes fits the measured vapor pressure of water reasonably well and further refinements are clearly possible. Over the somewhat more limited composition range up to saturation of typical salts such as NaCl, the equations representing thermodynamic properties with a Debye-Hueckel term plus second and third virial coefficients are very successful and these coefficients are known for nearly 300 electrolytes at room temperature. These same equations effectively predict the properties of mixed electrolytes. A stringent test is offered by the calculation of all of the solubility relationships of the system Na-K-Mg-Ca-Cl-So{sub 4}-H{sub 2}0 and the calculated results of Harvie and Weare show excellent agreement with
New proposal of moderator temperature coefficient estimation method using gray-box model in NPP, (1)
International Nuclear Information System (INIS)
Mori, Michitsugu; Kagami, Yuichi; Kanemoto, Shigeru; Enomoto, Mitsuhiro; Tamaoki, Tetsuo; Kawamura, Shinichiro
2004-01-01
The purpose of the present paper is to establish a new void reactivity coefficient (VRC) estimation method based on gray box modeling concept. The gray box model consists of a point kinetics model as the first principle model and a fitting model of moderator temperature kinetics. Applying Kalman filter and maximum likehood estimation algorithms to the gray box model, MTC can be estimated. The verification test is done by Monte Carlo simulation, and, it is shown that the present method gives the best estimation results comparing with the conventional methods from the viewpoints of non-biased and smallest scattering estimation performance. Furthermore, the method is verified via real plant data analysis. The reason of good performance of the present method is explained by proper definition of likelihood function based on explicit expression of observation and system noise in the gray box model. (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.
Rate Coefficients of the Reaction of OH with Allene and Propyne at High Temperatures
Es-sebbar, Et-touhami
2016-09-28
Allene (H2C═C═CH2; a-C3H4) and propyne (CH3C≡CH; p-C3H4) are important species in various chemical environments. In combustion processes, the reactions of hydroxyl radicals with a-C3H4 and p-C3H4 are critical in the overall fuel oxidation system. In this work, rate coefficients of OH radicals with allene (OH + H2C═C═CH2 → products) and propyne (OH + CH3C≡CH → products) were measured behind reflected shock waves over the temperature range of 843–1352 K and pressures near 1.5 atm. Hydroxyl radicals were generated by rapid thermal decomposition of tert-butyl hydroperoxide ((CH3)3–CO–OH), and monitored by narrow line width laser absorption of the well-characterized R1(5) electronic transition of the OH A–X (0,0) electronic system near 306.7 nm. Results show that allene reacts faster with OH radicals than propyne over the temperature range of this study. Measured rate coefficients can be expressed in Arrhenius form as follows: kallene+OH(T) = 8.51(±0.03) × 10–22T3.05 exp(2215(±3)/T), T = 843–1352 K; kpropyne+OH(T) = 1.30(±0.07) × 10–21T3.01 exp(1140(±6)/T), T = 846–1335 K.
Alekseenko, Elena; Kuznetsov, Konstantin; Roux, Bernard
2016-04-01
Wind stress on the free surface is the main driving force behind the circulation of the upper part of the ocean, which in hydrodynamic models are usually defined in terms of the coefficient of surface tension (Zhang et al., 2009, Davies et al., 2003). Moreover, wave motion impacts local currents and changes sea level, impacts the transport and the stratification of the entire water column. Influence of surface waves at the bottom currents is particularly pronounced in the shallow coastal systems. However, existing methods of parameterization of the surface tension have significant limits, especially in strong wind waves (Young et al., 2001, Jones et al., 2004) due to the difficulties of measuring the characteristics of surface waves in stormy conditions. Thus, the formula for calculating the coefficient of surface tension in our day is the actual problem in modeling fluid dynamics, particularly in the context of strong surface waves. In the hydrodynamic models usually a coefficient of surface tension is calculated once at the beginning of computation as a constant that depends on the averaged wind waves characteristic. Usually cases of strongly nonlinear wind waves are not taken into account, what significantly reduces the accuracy of the calculation of the flow structures and further calculation of the other processes in water basins, such as the spread of suspended matter and pollutants. Thus, wave motion influencing the pressure on the free surface and at the bottom must be considered in hydrodynamic models particularly in shallow coastal systems. A method of reconstruction of a free-surface drag coefficient based on the measured in-situ bottom pressure fluctuations is developed and applied in a three-dimensional hydrodynamic model MARS3D, developed by the French laboratory of IFREMER (IFREMER - French Research Institute for Marine Dynamics). MARS3D solves the Navier-Stokes equations for incompressible fluid in the Boussinesq approximation and with the
Directory of Open Access Journals (Sweden)
D. A. Goncharov
2015-01-01
Full Text Available In this paper we investigate small axisymmetric oscillations of a liquid in an elastic tank. We also take into account the influence of surface tension forces. For this, we turn to the mechanical analogue of the considered mechanical system. To realize the transition to mechanical analogue we use the energy method: postulating the equality of kinetic and potential energy for the investigated mechanical system and the mechanical system analog. Due to this transition we can further investigate the oscillations of a mechanical analogue. As a mechanical analogue, we consider the oscillator in the spring. The mass of the oscillator is calculated as the weight of the fluid to make oscillations. The oscillator spring constant is calculated using the identity of equations, namely, equation of free small oscillations of the oscillator and equation of free small oscillations of the system under investigation: the fluid in the elastic tank. The identity of equations allows us to draw conclusion about the identity of the natural frequencies for the source mechanical system and the system of a mechanical analogue. Next, we take into consideration the action of the surface tension. We record the Laplace condition for excess pressure because of the forces of surface tension. Then we compile the expression for the generalized force, taking into account the phenomenon of the surface tension. Next, we write the equation of oscillations of a mechanical analogue. The surface tension, due to the introduction of the generalized force in the equation for small oscillations of the mechanical analogue will change the natural frequency of the mechanical analogue. The paper presents the appropriate dependencies. The abovementioned allows us to investigate the stability of small motions of fluid in microgravity or low gravity by studying the stability of small motions of mechanical analogue. The latter is especially important due to the design and development of advanced
Sassi, U; Parret, R; Nanot, S; Bruna, M; Borini, S; De Fazio, D; Zhao, Z; Lidorikis, E; Koppens, F H L; Ferrari, A C; Colli, A
2017-01-31
There is a growing number of applications demanding highly sensitive photodetectors in the mid-infrared. Thermal photodetectors, such as bolometers, have emerged as the technology of choice, because they do not need cooling. The performance of a bolometer is linked to its temperature coefficient of resistance (TCR, ∼2-4% K -1 for state-of-the-art materials). Graphene is ideally suited for optoelectronic applications, with a variety of reported photodetectors ranging from visible to THz frequencies. For the mid-infrared, graphene-based detectors with TCRs ∼4-11% K -1 have been demonstrated. Here we present an uncooled, mid-infrared photodetector, where the pyroelectric response of a LiNbO 3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene. This is achieved by fabricating a floating metallic structure that concentrates the pyroelectric charge on the top-gate capacitor of the graphene channel, leading to TCRs up to 900% K -1 , and the ability to resolve temperature variations down to 15 μK.
Comparative evaluation of fuel temperature coefficient of standard and CANFLEX fuels in CANDU 6
International Nuclear Information System (INIS)
Kim, Woosong; Hartant, Donny; Kim, Yonghee
2012-01-01
The fuel temperature reactivity coefficient (FTC) of CANDU 6 has become a concerning issue. The FTC was found to be slightly positive for the operating condition of CANDU 6. Since CANDU 6 has unique fuel arrangement and very soft neutron spectrum, its Doppler reactivity feedback of U 238 is rather weak. The upscattering by oxygen in fuel and Pu 239 buildup with fuel depletion are responsible for the positive FTC value at high temperature. In this study, FTC of both standard CANDU and CANFLEX fuel lattice are re evaluated. A Monte Carlo code Serpent2 was chosen as the analysis tool because of its high calculational speed and it can account for the thermal motion of heavy nuclides in fuel by using the Doppler Broadening Rejection Correction (DBRC) method. It was reported that the fuel Doppler effect is noticeably enhanced by accounting the target thermal motion. Recently, it was found that the FTC of the CANDU 6 standard fuel is noticeably enhanced by the DBRC
Temperature Dependence of the Seebeck Coefficient in Zinc Oxide Thin Films
Noori, Amirreza; Masoumi, Saeed; Hashemi, Najmeh
2017-12-01
Thermoelectric devices are reliable tools for converting waste heat into electricity as they last long, produce no noise or vibration, have no moving elements, and their light weight makes them suitable for the outer space usage. Materials with high thermoelectric figure of merit (zT) have the most important role in the fabrication of efficient thermoelectric devices. Metal oxide semiconductors, specially zinc oxide has recently received attention as a material suitable for sensor, optoelectronic and thermoelectric device applications because of their wide direct bandgap, chemical stability, high-energy radiation endurance, transparency and acceptable zT. Understanding the thermoelectric properties of the undoped ZnO thin films can help design better ZnO-based devices. Here, we report the results of our experimental work on the thermoelectric properties of the undoped polycrystalline ZnO thin films. These films are deposited on alumina substrates by thermal evaporation of zinc in vacuum followed by a controlled oxidation process in air carried out at the 350-500 °C temperature range. The experimental setup including gradient heaters, thermometry system and Seebeck voltage measurement equipment for high resistance samples is described. Seebeck voltage and electrical resistivity of the samples are measured at different conditions. The observed temperature dependence of the Seebeck coefficient is discussed.
Holsgrove, Kristina M.; Kepaptsoglou, Demie M.; Douglas, Alan M.; Ramasse, Quentin M.; Prestat, Eric; Haigh, Sarah J.; Ward, Michael B.; Kumar, Amit; Gregg, J. Marty; Arredondo, Miryam
2017-06-01
Despite being of wide commercial use in devices, the orders of magnitude increase in resistance that can be seen in some semiconducting BaTiO3-based ceramics, on heating through the Curie temperature (TC), is far from well understood. Current understanding of the behavior hinges on the role of grain boundary resistance that can be modified by polarization discontinuities which develop in the ferroelectric state. However, direct nanoscale resistance mapping to verify this model has rarely been attempted, and the potential approach to engineer polarization states at the grain boundaries, that could lead to optimized positive temperature coefficient (PTC) behavior, is strongly underdeveloped. Here we present direct visualization and nanoscale mapping in a commercially optimized BaTiO3-PbTiO3-CaTiO3 PTC ceramic using Kelvin probe force microscopy, which shows that, even in the low resistance ferroelectric state, the potential drop at grain boundaries is significantly greater than in grain interiors. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy reveal new evidence of Pb-rich grain boundaries symptomatic of a higher net polarization normal to the grain boundaries compared to the purer grain interiors. These results validate the critical link between optimized PTC performance and higher local polarization at grain boundaries in this specific ceramic system and suggest a novel route towards engineering devices where an interface layer of higher spontaneous polarization could lead to enhanced PTC functionality.
Directory of Open Access Journals (Sweden)
Kristina M. Holsgrove
2017-06-01
Full Text Available Despite being of wide commercial use in devices, the orders of magnitude increase in resistance that can be seen in some semiconducting BaTiO3-based ceramics, on heating through the Curie temperature (TC, is far from well understood. Current understanding of the behavior hinges on the role of grain boundary resistance that can be modified by polarization discontinuities which develop in the ferroelectric state. However, direct nanoscale resistance mapping to verify this model has rarely been attempted, and the potential approach to engineer polarization states at the grain boundaries, that could lead to optimized positive temperature coefficient (PTC behavior, is strongly underdeveloped. Here we present direct visualization and nanoscale mapping in a commercially optimized BaTiO3–PbTiO3–CaTiO3 PTC ceramic using Kelvin probe force microscopy, which shows that, even in the low resistance ferroelectric state, the potential drop at grain boundaries is significantly greater than in grain interiors. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy reveal new evidence of Pb-rich grain boundaries symptomatic of a higher net polarization normal to the grain boundaries compared to the purer grain interiors. These results validate the critical link between optimized PTC performance and higher local polarization at grain boundaries in this specific ceramic system and suggest a novel route towards engineering devices where an interface layer of higher spontaneous polarization could lead to enhanced PTC functionality.
Directory of Open Access Journals (Sweden)
Boping Li
2015-01-01
Full Text Available At present, studies on the surface tension of air tunnel terrazzo under wind load and how regularly it is affected by temperature are relatively less, and the measured results of the thermal expansion coefficient of terrazzo have not yet been given. In this paper, based on the top terrazzo surface structure of the inner wall of the wind tunnel, the tensile performance tests of terrazzo surface layer are conducted, while the thermal expansion coefficient of the six terrazzo test blocks were tested. The tests and analysis show that the construction of terrazzo surface, based on the proposed construction process, can effectively guarantee the reliable cement performance for the binding layer between mortar and concrete base layer, terrazzo surface layer and the cement mortar layer. And the thermal expansion coefficient of terrazzo can be valued at 1.06e-5/ºC.
International Nuclear Information System (INIS)
Richards, Guy A.; Serfontein, Dawid E.
2014-01-01
This article investigates advanced fuel cycles containing thorium and reactor grade plutonium (Pu(PWR)) in a 400 MW th Pebble Bed Modular Reactor (PBMR) Demonstration Power Plant. Results presented were determined from coupled neutronics and thermo-hydraulic simulations of the VSOP 99/05 diffusion codes. In a previous study impressive burn-ups (601 MWd/kg heavy metal (HM)) and thus plutonium destruction rates (69.2 %) were obtained with pure plutonium fuel with mass loadings of 3 g Pu(PWR)/fuel sphere or less. However the safety performance was poor in that the limit on the maximum fuel temperature during equilibrium operation was exceeded and positive Uniform Temperature Reactivity Coefficients (UTCs) were obtained. In the present study fuel cycles containing mixtures of thorium and plutonium achieved negative maximum UTCs. Plutonium only fuel cycles also achieved negative maximum UTCs, provided that much higher mass loadings are used. It is proposed that the lower thermal neutron flux was responsible for this effect. The plutonium only fuel cycle with 12 g Pu(PWR)/fuel sphere also achieved the adopted safety limits for the PBMR DPP-400 in that the maximum fuel temperature and the maximum power density did not exceed 1130°C or 4.5 kW/sphere respectively. This design would thus be licensable and could potentially be economically feasible. However the burn-up was much lower at 181 MWd/kgHM and thus the plutonium destruction fraction was also much lower at 24.5%, which may be sub-optimal with respect to proliferation and waste disposal objectives and therefore further optimisation studies are proposed. (author)
Adjustment of activity coefficients as a function of changes in temperature, using the SIT
International Nuclear Information System (INIS)
Giffaut, E.; Vitorge, P.; Capdevila, H.
1993-11-01
The aim of this work is to propose and to check approximations to calculate from only a few experimental measurements, ionic strength, I, and temperature, T, influences on Gibbs energy, G, redox formal potential, E, and standard equilibrium constant, K. Series expansions versus T are first used: S and Cp/2T a are typically the -G first and second order terms. In the same way, -ΔH and T 2 ΔCp/2 are the first and second order terms of R in K expansions versus 1/T. This type of approximation is discussed for the E of the M 4+ /M 3+ , MO 2 2+ /MO 2 + and MO 2 (CO 3 ) 3 4- /MO 2 (CO 3 ) 3 5- couples (M = U or Pu) measured from 5 to 70 deg C, for the standard ΔG of some solid U compounds, calculated from 17 to 117 deg C, and for ΔCp, ΔG and Ig K of the CO 2 (aq)/HCO 3 - equilibrium from 0 to 150 deg C. Excess functions, X ex , are then calculated from activity coefficients, γ: enthalpy, H, or heat capacity, Cp, adjustment as a function of I changes is needed only when the γ adjustment as a function of T changes is needed. The SIT coefficient, ε, variations with T, are small and roughly linear for the above redox equilibria and for chloride electrolytes mean γ: first order expansion seems enough to deduce ε, and then the excess functions G ex , S ex and H ex , in this T range; but second order expansion is more consistent to estimate Cp ex . (authors). 25 refs., 3 tabs., 1 fig
Walker, R. D., Jr.
1973-01-01
Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.
Positron annihilation lifetime study of positive temperature coefficient BaTiO3 samples
International Nuclear Information System (INIS)
Ling Chen; Mingkang Teng; Guanghou Wang; Xiaoyun Li; Tianchang Lu
1989-01-01
In order to investigate the doped vacancies in BaTiO 3 samples as well as their influence on the positive temperature coefficient (PTC) the positron annihilation lifetime spectroscopy was applied. Two groups of BaTiO 3 samples with BaO excess were prepared by doping different concentrations of La 2 O 3 and Nb 2 O 5 , respectively in the range from 0.1 to 3 at%. A third group of samples of two Sb-doped PTC BaTiO 3 semiconductors with excess BaO or TiO 2 were studied by the aid of positron technique before and after being reduced. It is shown that the positron lifetime parameters are sensitive to changes in the vacancy concentration in BaTiO 3 ceramics near the 0.1 mol% region. But they are almost unchanged during reduction processing; the resistivity of samples changed by one to two orders of magnitude through the reduction. It can be concluded that the PTC effect is due to oxygen on the grain boundary rather than vacancies, and that the Heywang-Jonker model is more reasonable
Wang, Conan K.; Northfield, Susan E.; Colless, Barbara; Chaousis, Stephanie; Hamernig, Ingrid; Lohman, Rink-Jan; Nielsen, Daniel S.; Schroeder, Christina I.; Liras, Spiros; Price, David A.; Fairlie, David P.; Craik, David J.
2014-01-01
Enhancing the oral bioavailability of peptide drug leads is a major challenge in drug design. As such, methods to address this challenge are highly sought after by the pharmaceutical industry. Here, we propose a strategy to identify appropriate amides for N-methylation using temperature coefficients measured by NMR to identify exposed amides in cyclic peptides. N-methylation effectively caps these amides, modifying the overall solvation properties of the peptides and making them more membrane permeable. The approach for identifying sites for N-methylation is a rapid alternative to the elucidation of 3D structures of peptide drug leads, which has been a commonly used structure-guided approach in the past. Five leucine-rich peptide scaffolds are reported with selectively designed N-methylated derivatives. In vitro membrane permeability was assessed by parallel artificial membrane permeability assay and Caco-2 assay. The most promising N-methylated peptide was then tested in vivo. Here we report a novel peptide (15), which displayed an oral bioavailability of 33% in a rat model, thus validating the design approach. We show that this approach can also be used to explain the notable increase in oral bioavailability of a somatostatin analog. PMID:25416591
Shizgal, Bernie D.; Chikhaoui, Aziz
2006-06-01
The present paper considers a detailed analysis of the nonequilibrium effects for a model reactive system with the Chapman-Eskog (CE) solution of the Boltzmann equation as well as an explicit time dependent solution. The elastic cross sections employed are a hard sphere cross section and the Maxwell molecule cross section. Reactive cross sections which model reactions with and without activation energy are used. A detailed comparison is carried out with these solutions of the Boltzmann equation and the approximation introduced by Cukrowski and coworkers [J. Chem. Phys. 97 (1992) 9086; Chem. Phys. 89 (1992) 159; Physica A 188 (1992) 344; Chem. Phys. Lett. A 297 (1998) 402; Physica A 275 (2000) 134; Chem. Phys. Lett. 341 (2001) 585; Acta Phys. Polonica B 334 (2003) 3607.] based on the temperature of the reactive particles. We show that the Cukrowski approximation has limited applicability for the large class of reactive systems studied in this paper. The explicit time dependent solutions of the Boltzmann equation demonstrate that the CE approach is valid only for very slow reactions for which the corrections to the equilibrium rate coefficient are very small.
Ramu, Ashok T; Mages, Phillip; Zhang, Chong; Imamura, Jeffrey T; Bowers, John E
2012-09-01
The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.
Energy Technology Data Exchange (ETDEWEB)
Li Fei; Xu Zhuo; Wei Xiaoyong; Yao Xi, E-mail: lifei1216@gmail.co [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi' an Jiaotong University, Xi' an 710049 (China)
2009-05-07
The piezoelectric coefficients (d{sub 33}, -d{sub 31}, d{sub 15}, g{sub 33}, -g{sub 31}, g{sub 15}) of soft and hard lead zirconate titanate ceramics were measured by the quasi-static and resonance methods, at temperatures from 20 to 300 {sup 0}C. The results showed that the piezoelectric coefficients d{sub 33}, -d{sub 31} and d{sub 15} obtained by these two methods increased with increasing temperature for both hard and soft PZT ceramics, while the piezoelectric coefficients g{sub 33}, -g{sub 31} and g{sub 15} decreased with increasing temperature for both hard and soft PZT ceramics. In this paper, the observed results were also discussed in terms of intrinsic and extrinsic contributions to piezoelectric response.
Kabir, Kamaluddeen; Deeni, Yusuf Y; Hapca, Simona M; Moore, Luke; Spiers, Andrew J
2018-02-01
Bacterial biosurfactants have a wide range of biological functions and biotechnological applications. Previous analyses had suggested a limit to their reduction of aqueous liquid surface tensions (γMin), and here we confirm this in an analysis of 25 Pseudomonas spp. strains isolated from soil which produce high-strength surfactants that reduce surface tensions to 25.2 ± 0.1-26.5 ± 0.2 mN m-1 (the surface tension of sterile growth medium and pure water was 52.9 ± 0.4 mN m-1 and 72.1 ± 1.2 mN m-1, respectively). Comparisons of culture supernatants produced using different growth media and semi-purified samples indicate that the limit of 24.2-24.7 mN m-1 is not greatly influenced by culture conditions, pH or NaCl concentrations. We have used foam, emulsion and oil-displacement behavioural assays as a simple and cost-effective proxy for in-depth biochemical characterisation, and these suggest that there is significant structural diversity amongst these surfactants that may reflect different biological functions and offer new biotechnological opportunities. Finally, we obtained a draft genome for the strain producing the highest strength surfactant, and identified a cluster of non-ribosomal protein synthase genes that may produce a cyclic lipopeptide (CLP)-like surfactant. Further investigation of this group of related bacteria recovered from the same site will allow a better understanding of the significance of the great variety of surfactants produced by bacterial communities found in soil and elsewhere. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
International Nuclear Information System (INIS)
Zakova, Jitka; Talamo, Alberto
2008-01-01
The conceptual design of the advanced high-temperature reactor (AHTR) has recently been proposed by the Oak Ridge National Laboratory, with the intention to provide and alternative energy source for very high temperature applications. In the present study, we focused on the analyses of the reactivity coefficients of the AHTR core fueled with two types of fuel: enriched uranium and plutonium from the reprocessing of light water reactors irradiated fuel. More precisely, we investigated the influence of the outer graphite reflectors on the multiplication factor of the core, the fuel and moderator temperature reactivity coefficients and the void reactivity coefficient for five different molten salts: NaF, BeF 2 , LiF, ZrF 4 and Li 2 BeF 4 eutectic. In order to better illustrate the behavior of the previous parameters for different core configurations, we evaluated the moderating ratio of the molten salts and the absorption rate of the key fuel nuclides, which, of course, are driven by the neutron spectrum. The results show that the fuel and moderator temperature reactivity coefficients are always negative, whereas the void reactivity coefficient can be set negative provided that the fuel to moderator ratio is optimized (the core is undermoderated) and the moderating ratio of the coolant is large
Energy Technology Data Exchange (ETDEWEB)
Zakova, Jitka [Department of Nuclear and Reactor Physics, Royal Institute of Technology, KTH, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)], E-mail: jitka.zakova@neutron.kth.se; Talamo, Alberto [Nuclear Engineering Division, Argonne National Laboratory, ANL, 9700 South Cass Avenue, Argonne, IL 60439 (United States)], E-mail: alby@anl.gov
2008-05-15
The conceptual design of the advanced high-temperature reactor (AHTR) has recently been proposed by the Oak Ridge National Laboratory, with the intention to provide and alternative energy source for very high temperature applications. In the present study, we focused on the analyses of the reactivity coefficients of the AHTR core fueled with two types of fuel: enriched uranium and plutonium from the reprocessing of light water reactors irradiated fuel. More precisely, we investigated the influence of the outer graphite reflectors on the multiplication factor of the core, the fuel and moderator temperature reactivity coefficients and the void reactivity coefficient for five different molten salts: NaF, BeF{sub 2}, LiF, ZrF{sub 4} and Li{sub 2}BeF{sub 4} eutectic. In order to better illustrate the behavior of the previous parameters for different core configurations, we evaluated the moderating ratio of the molten salts and the absorption rate of the key fuel nuclides, which, of course, are driven by the neutron spectrum. The results show that the fuel and moderator temperature reactivity coefficients are always negative, whereas the void reactivity coefficient can be set negative provided that the fuel to moderator ratio is optimized (the core is undermoderated) and the moderating ratio of the coolant is large.
International Nuclear Information System (INIS)
Park, Jung Eun; Yang, Sung Mo; Han, Jae Hee; Yu, Hyo Sun
2011-01-01
High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipment. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously
International Nuclear Information System (INIS)
Carter, J.G.; Hunter, S.R.; Christophorou, L.G.
1987-01-01
Measurements of the electron drift velocity, w, attachment coefficient, eta/N/sub a/, and ionization coefficient, α/N, have been made in C 2 F 6 /Ar and C 2 F 6 /CH 4 gas mixtures at gas temperatures, T, of 300 and 500 0 K over the concentration range of 0.1 to 100% of the C 2 F 6 . These measurements are useful for modeling the expected behavior of repetitively operated electron-beam sustained diffuse gas discharge opening switches where gas temperatures within the switch are anticipated to rise several hundred degrees during switch operation
Onischuk, A A; Purtov, P A; Baklanov, A M; Karasev, V V; Vosel, S V
2006-01-07
Zinc and silver vapor homogeneous nucleations are studied experimentally at the temperature from 600 to 725 and 870 K, respectively, in a laminar flow diffusion chamber with Ar as a carrier gas at atmospheric pressure. The size, shape, and concentration of aerosol particles outcoming the diffusion chamber are analyzed by a transmission electron microscope and an automatic diffusion battery. The wall deposit is studied by a scanning electron microscope (SEM). Using SEM data the nucleation rate for both Zn and Ag is estimated as 10(10) cm(-3) s(-1). The dependence of critical supersaturation on temperature for Zn and Ag measured in this paper as well as Li, Na, Cs, Ag, Mg, and Hg measured elsewhere is analyzed. To this aim the classical nucleation theory is extended by the dependence of surface tension on the nucleus radius. The preexponent in the formula for the vapor nucleation rate is derived using the formula for the work of formation of noncritical embryo [obtained by Nishioka and Kusaka [J. Chem. Phys. 96, 5370 (1992)] and later by Debenedetti and Reiss [J. Chem. Phys. 108, 5498 (1998)
Durand, O.; Jaouen, S.; Soulard, L.; Heuzé, O.; Colombet, L.
2017-10-01
We compare, at similar scales, the processes of microjetting and ejecta production from shocked roughened metal surfaces by using atomistic and continuous approaches. The atomistic approach is based on very large scale molecular dynamics (MD) simulations with systems containing up to 700 × 106 atoms. The continuous approach is based on Eulerian hydrodynamics simulations with adaptive mesh refinement; the simulations take into account the effects of viscosity and surface tension, and the equation of state is calculated from the MD simulations. The microjetting is generated by shock-loading above its fusion point a three-dimensional tin crystal with an initial sinusoidal free surface perturbation, the crystal being set in contact with a vacuum. Several samples with homothetic wavelengths and amplitudes of defect are simulated in order to investigate the influence of viscosity and surface tension of the metal. The simulations show that the hydrodynamic code reproduces with very good agreement the profiles, calculated from the MD simulations, of the ejected mass and velocity along the jet. Both codes also exhibit a similar fragmentation phenomenology of the metallic liquid sheets ejected, although the fragmentation seed is different. We show in particular, that it depends on the mesh size in the continuous approach.
Energy Technology Data Exchange (ETDEWEB)
Behroozi, F [Department of Physics, University of Northern Iowa, Cedar Falls, IA 50614 (United States); Behroozi, P S, E-mail: behroozi@uni.edu [Department of Physics, Stanford University, Stanford, CA 94305 (United States)
2011-09-15
A chain assumes the well-known shape known as a catenary when it hangs loosely from two points in a gravitational field. The correct solution of the catenary was one of the early triumphs of the newly invented calculus of variations at the end of the 17th century. Here we revisit the catenary and show that, for a chain hanging from a horizontal rod, three new and distinct configurations are possible if a soap film covers the area bounded by the chain and the rod. We first review the general problem and discuss the conditions under which the chain assumes a concave, triangular or convex configuration. The deciding factor is the strength of surface tension relative to the gravitational force per unit length of the chain. The conditions under which the chain assumes the shape of a perfect triangle are discussed in greater detail and analysed to obtain the tension along the chain. The triangular configuration is especially intriguing to undergraduates and may be used as a simple experiment to obtain the surface tension of the soap solution by measuring just one angle of the triangle.
International Nuclear Information System (INIS)
Behroozi, F; Behroozi, P S
2011-01-01
A chain assumes the well-known shape known as a catenary when it hangs loosely from two points in a gravitational field. The correct solution of the catenary was one of the early triumphs of the newly invented calculus of variations at the end of the 17th century. Here we revisit the catenary and show that, for a chain hanging from a horizontal rod, three new and distinct configurations are possible if a soap film covers the area bounded by the chain and the rod. We first review the general problem and discuss the conditions under which the chain assumes a concave, triangular or convex configuration. The deciding factor is the strength of surface tension relative to the gravitational force per unit length of the chain. The conditions under which the chain assumes the shape of a perfect triangle are discussed in greater detail and analysed to obtain the tension along the chain. The triangular configuration is especially intriguing to undergraduates and may be used as a simple experiment to obtain the surface tension of the soap solution by measuring just one angle of the triangle.
Directory of Open Access Journals (Sweden)
Griese Matthias
2007-10-01
Full Text Available Abstract Background Deleted in Malignant Brain Tumors 1 (DMBT1 is a secreted scavenger receptor cysteine-rich protein that binds various bacteria and is thought to participate in innate pulmonary host defense. We hypothesized that pulmonary DMBT1 could contribute to respiratory distress syndrome in neonates by modulating surfactant function. Methods DMBT1 expression was studied by immunohistochemistry and mRNA in situ hybridization in post-mortem lungs of preterm and full-term neonates with pulmonary hyaline membranes. The effect of human recombinant DMBT1 on the function of bovine and porcine surfactant was measured by a capillary surfactometer. DMBT1-levels in tracheal aspirates of ventilated preterm and term infants were determined by ELISA. Results Pulmonary DMBT1 was localized in hyaline membranes during respiratory distress syndrome. In vitro addition of human recombinant DMBT1 to the surfactants increased surface tension in a dose-dependent manner. The DMBT1-mediated effect was reverted by the addition of calcium depending on the surfactant preparation. Conclusion Our data showed pulmonary DMBT1 expression in hyaline membranes during respiratory distress syndrome and demonstrated that DMBT1 increases lung surface tension in vitro. This raises the possibility that DMBT1 could antagonize surfactant supplementation in respiratory distress syndrome and could represent a candidate target molecule for therapeutic intervention in neonatal lung disease.
Directory of Open Access Journals (Sweden)
Jyh Jian Chen
2014-03-01
Full Text Available Filling of liquid samples is realized in a microfluidic device with applications including analytical systems, biomedical devices, and systems for fundamental research. The filling of a disk-shaped polydimethylsiloxane (PDMS microchamber by liquid is analyzed with reference to microstructures with inlets and outlets. The microstructures are fabricated using a PDMS molding process with an SU-8 mold. During the filling, the motion of the gas-liquid interface is determined by the competition among inertia, adhesion, and surface tension. A single ramp model with velocity-dependent contact angles is implemented for the accurate calculation of surface tension forces in a three-dimensional volume-of-fluid based model. The effects of the parameters of this functional form are investigated. The influences of non-dimensional parameters, such as the Reynolds number and the Weber number, both determined by the inlet velocity, on the flow characteristics are also examined. An oxygen-plasma-treated PDMS substrate is utilized, and the microstructure is modified to be hydrophilic. Flow experiments are conducted into both hydrophilic and hydrophobic PDMS microstructures. Under a hydrophobic wall condition, numerical simulations with imposed boundary conditions of static and dynamic contact angles can successfully predict the moving of the meniscus compared with experimental measurements. However, for a hydrophilic wall, accurate agreement between numerical and experimental results is obvious as the dynamic contact angles were implemented.
Directory of Open Access Journals (Sweden)
A. D. Pataraya
1997-01-01
Full Text Available Non-linear α-ω; dynamo waves existing in an incompressible medium with the turbulence dissipative coefficients depending on temperature are studied in this paper. We investigate of α-ω solar non-linear dynamo waves when only the first harmonics of magnetic induction components are included. If we ignore the second harmonics in the non-linear equation, the turbulent magnetic diffusion coefficient increases together with the temperature, the coefficient of turbulent viscosity decreases, and for an interval of time the value of dynamo number is greater than 1. In these conditions a stationary solution of the non-linear equation for the dynamo wave's amplitude exists; meaning that the magnetic field is sufficiently excited. The amplitude of the dynamo waves oscillates and becomes stationary. Using these results we can explain the existence of Maunder's minimum.
Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.
2009-01-01
The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."
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.
H. Li; X. Deng; Andy Dolloff; E. P. Smith
2015-01-01
A novel clustering method for bivariate functional data is proposed to group streams based on their waterâair temperature relationship. A distance measure is developed for bivariate curves by using a time-varying coefficient model and a weighting scheme. This distance is also adjusted by spatial correlation of streams via the variogram. Therefore, the proposed...
Gonzales, Matthew Alejandro
The calculation of the thermal neutron Doppler temperature reactivity feedback co-efficient, a key parameter in the design and safe operation of advanced reactors, using first order perturbation theory in continuous energy Monte Carlo codes is challenging as the continuous energy adjoint flux is not readily available. Traditional approaches of obtaining the adjoint flux attempt to invert the random walk process as well as require data corresponding to all temperatures and their respective temperature derivatives within the system in order to accurately calculate the Doppler temperature feedback. A new method has been developed using adjoint-weighted tallies and On-The-Fly (OTF) generated continuous energy cross sections within the Monte Carlo N-Particle (MCNP6) transport code. The adjoint-weighted tallies are generated during the continuous energy k-eigenvalue Monte Carlo calculation. The weighting is based upon the iterated fission probability interpretation of the adjoint flux, which is the steady state population in a critical nuclear reactor caused by a neutron introduced at that point in phase space. The adjoint-weighted tallies are produced in a forward calculation and do not require an inversion of the random walk. The OTF cross section database uses a high order functional expansion between points on a user-defined energy-temperature mesh in which the coefficients with respect to a polynomial fitting in temperature are stored. The coefficients of the fits are generated before run- time and called upon during the simulation to produce cross sections at any given energy and temperature. The polynomial form of the OTF cross sections allows the possibility of obtaining temperature derivatives of the cross sections on-the-fly. The use of Monte Carlo sampling of adjoint-weighted tallies and the capability of computing derivatives of continuous energy cross sections with respect to temperature are used to calculate the Doppler temperature coefficient in a research
Modelling global fresh surface water temperature
Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.
2011-01-01
Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment
H2 line-mixing coefficients in the ν2 and ν4 bands of PH3 at low temperature
International Nuclear Information System (INIS)
Salem, Jamel; Blanquet, Ghislain; Lepère, Muriel; Aroui, Hassen
2016-01-01
Using a tunable diode-laser spectrometer adapted with a low temperature cell, we have measured the H 2 line-mixing coefficients for 21 lines in the Q R branch of the ν 2 band and in the P P and R P branches of the ν 4 band of phosphine (PH 3 ) at low temperature. These coefficients were determined using a multi-pressure fitting procedure that accounts for the apparatus function, the Doppler and the collisional effects. These lines with J values ranging from 2 to 11 and K from 0 to 9 are located in the spectral range from 1016 to 1093 cm −1 . The variations of these parameters with the temperature, and the ro-vibrational quantum numbers are discussed. - Graphical abstract: Comparisons of the determined line-mixing coefficients (in atm −1 ) obtained in this study in the ν 2 and ν 4 bands of PH 3 at T=173.2 K with those measured at T=298 K for different values of the J quantum number. - Highlights: • The spectra have been recorded with a tunable diode-laser spectrometer at 173.2 K. • The line-mixing coefficients are determined by a multi-pressure fitting procedure. • The effect of the line-mixing in the spectra, appear to be important.
DEFF Research Database (Denmark)
He, Zeming; Ma, J.; Qu, Yuanfang
2009-01-01
discussed. Using these special processes, the prepared composite with 20 wt% Cr possessed low room-temperature resistivity (2.96 Ω cm at 25 °C) and exhibited PTC effect (resistivity jump of 10), which is considered as a promising candidate for over-current protector when working at low voltage. The grain......Low room-temperature resistivity positive temperature coefficient (PTC) Cr/(Ba0.85Pb0.15)TiO3 composites were produced via a reducing sintering and a subsequent oxidation treatment. The effects of metallic content and processing conditions on materials resistivity–temperature properties were...
Danov, Krassimir D; Stanimirova, Rumyana D; Kralchevsky, Peter A; Marinova, Krastanka G; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Cox, Andrew R; Pelan, Eddie G
2016-07-01
Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are based on a new data analysis protocol, which allows one to decouple the two components of non-isotropic surface tension. For an axisymmetric non-fluid interface (e.g. bubble or drop covered by a protein adsorption layer with shear elasticity), the CMD determines the two different components of the anisotropic surface tension, σs and σφ, which are acting along the "meridians" and "parallels", and vary throughout the interface. The method uses data for the instantaneous bubble (drop) profile and capillary pressure, but the procedure for data processing is essentially different from that of the conventional drop shape analysis (DSA) method. In the case of bubble or drop pressed against a substrate, which forms a capillary bridge, the CBD method allows one to determine also the capillary-bridge force for both isotropic (fluid) and anisotropic (solidified) adsorption layers. The experiments on bubble (drop) detachment from the substrate show the existence of a maximal pulling force, Fmax, that can be resisted by an adherent fluid particle. Fmax can be used to quantify the strength of adhesion of bubbles and drops to solid surfaces. Its value is determined by a competition of attractive transversal tension and repulsive disjoining pressure forces. The greatest Fmax values have been measured for bubbles adherent to glass substrates in pea-protein solutions. The bubble/wall adhesion is lower in solutions containing the protein HFBII hydrophobin, which could be explained with the effect of sandwiched protein aggregates. The applicability of the CBD method to emulsion systems is illustrated by experiments with soybean-oil drops adherent to hydrophilic and hydrophobic substrates in
Shear piezoelectric coefficients of PZT, LiNbO3 and PMN-PT at cryogenic temperatures
International Nuclear Information System (INIS)
Bukhari, Syed; Islam, Md; Haziot, Ariel; Beamish, John
2014-01-01
Piezoelectric transducers are used to detect stress and to generate nanometer scale displacements but their piezoelectric coefficients decrease with temperature, limiting their performance in cryogenic applications. We have developed a capacitive technique and directly measured the temperature dependence of the shear coefficient d 15 for ceramic lead zirconium titanate (PZT), 41° X-cut lithium niobate (LiNbO 3 ) and single crystal lead magnesium niobium-lead titanate (PMN-PT). In PZT, d 15 decreases nearly linearly with temperature, dropping by factor of about 4 by 1.3 K. LiNbO3 has the smallest room temperature d15, but its value decreased by only 6% at the lowest temperatures. PMN-PT had the largest value of d15 at room temperature (2.9 × 10 −9 m/V, about 45 times larger than for LiNbO 3 ) but it decreased rapidly below 75 K; at 1.3 K, d 15 was only about 8% of its room temperature value
International Nuclear Information System (INIS)
Tomar, Monika; Gupta, Vinay; Sreenivas, K
2003-01-01
The influence of sputtered SiO 2 over-layer on the SAW propagation characteristics of a 128 deg. rotated Y-cut X-propagating lithium niobate SAW filter has been studied. Experimentally measured SAW phase velocity and temperature coefficient of delay (TCD), with varying SiO 2 over-layer thickness, show a significant deviation from the theoretically calculated values using the bulk material parameters of SiO 2 . The observed deviation is attributed to the differences in the material parameters (density, elastic and dielectric constants and their temperature coefficient) of the deposited SiO 2 over-layer. The density and the dielectric constant of the deposited SiO 2 layer were determined separately, and the elastic constants and their temperature coefficients were estimated by fitting the experimental velocity and TCD data, respectively. The deviation in the dielectric constant and the density in comparison to the bulk was insignificant, and the estimated values of the elastic constants (C 11 = 0.75x10 11 N m -2 and C 44 0.225x10 11 N m -2 ) were found to be lower, and the respective temperature coefficients (5.0x10 -4 deg C -1 and 2.0x10 -4 deg C -1 ) were high in comparison to the bulk material parameters
Energy Technology Data Exchange (ETDEWEB)
Tomar, Monika; Gupta, Vinay; Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)
2003-08-07
The influence of sputtered SiO{sub 2} over-layer on the SAW propagation characteristics of a 128 deg. rotated Y-cut X-propagating lithium niobate SAW filter has been studied. Experimentally measured SAW phase velocity and temperature coefficient of delay (TCD), with varying SiO{sub 2} over-layer thickness, show a significant deviation from the theoretically calculated values using the bulk material parameters of SiO{sub 2}. The observed deviation is attributed to the differences in the material parameters (density, elastic and dielectric constants and their temperature coefficient) of the deposited SiO{sub 2} over-layer. The density and the dielectric constant of the deposited SiO{sub 2} layer were determined separately, and the elastic constants and their temperature coefficients were estimated by fitting the experimental velocity and TCD data, respectively. The deviation in the dielectric constant and the density in comparison to the bulk was insignificant, and the estimated values of the elastic constants (C{sub 11} = 0.75x10{sup 11} N m{sup -2} and C{sub 44} 0.225x10{sup 11} N m{sup -2}) were found to be lower, and the respective temperature coefficients (5.0x10{sup -4} deg C{sup -1} and 2.0x10{sup -4} deg C{sup -1}) were high in comparison to the bulk material parameters.
Influence of Contact Angle, Growth Angle and Melt Surface Tension on Detached Solidification of InSb
Wang, Yazhen; Regel, Liya L.; Wilcox, William R.
2000-01-01
We extended the previous analysis of detached solidification of InSb based on the moving meniscus model. We found that for steady detached solidification to occur in a sealed ampoule in zero gravity, it is necessary for the growth angle to exceed a critical value, the contact angle for the melt on the ampoule wall to exceed a critical value, and the melt-gas surface tension to be below a critical value. These critical values would depend on the material properties and the growth parameters. For the conditions examined here, the sum of the growth angle and the contact angle must exceed approximately 130, which is significantly less than required if both ends of the ampoule are open.
Denisova, Irina Vlad.
2015-03-01
The paper deals with the motion of two immiscible viscous fluids in a container, one of the fluids being compressible while another one being incompressible. The interface between the fluids is an unknown closed surface where surface tension is neglected. We assume the compressible fluid to be barotropic, the pressure being given by an arbitrary smooth increasing function. This problem is considered in anisotropic Sobolev-Slobodetskiǐ spaces. We show that the L 2-norms of the velocity and deviation of compressible fluid density from the mean value decay exponentially with respect to time. The proof is based on a local existence theorem (Denisova, Interfaces Free Bound 2:283-312, 2000) and on the idea of constructing a function of generalized energy, proposed by Padula (J Math Fluid Mech 1:62-77, 1999). In addition, we eliminate the restrictions for the viscosities which appeared in Denisova (Interfaces Free Bound 2:283-312, 2000).
Energy Technology Data Exchange (ETDEWEB)
Dreyer, Wolfgang [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany); Kimmerle, Sven-Joachim [Humboldt-Univ. Berlin (Germany). Dept. of Mathematics
2009-07-01
Based on a thermodynamically consistent model for precipitation in gallium arsenide crystals including surface tension and bulk stresses by Dreyer and Duderstadt, we propose different mathematical models to describe the size evolution of liquid droplets in a crystalline solid. The first class of models treats the diffusion-controlled regime of interface motion, while the second class is concerned with the interface-controlled regime of interface motion. Our models take care of conservation of mass and substance. We consider homogenised models, where different length scales of the experimental situation have been exploited in order to simplify the equations. These homogenised models generalise the well-known Lifshitz-Slyozov-Wagner model for Ostwald ripening. Mean field models capture the main properties of our system and are well adapted for numerics and further analysis. Numerical evidence suggests in which case which one of the two regimes might be appropriate to the experimental situation. (orig.)
Curtis, H. B.; Hart, R. E., Jr.
1982-01-01
Gallium arsenide solar cells are considered for several high temperature missions in space. Both near-Sun and concentrator missions could involve cell temperatures on the order of 200 C. Performance measurements of cells at elevated temperatures are usually made using simulated sunlight and a matched reference cell. Due to the change in bandgap with increasing temperature at portions of the spectrum where considerable simulated irradiance is present, there are significant differences in measured short circuit current at elevated temperatures among different simulators. To illustrate this, both experimental and theoretical data are presented for gallium arsenide cells.
International Nuclear Information System (INIS)
Mohsen-Nia, M.; Ebrahimabadi, A.H.; Niknahad, B.
2012-01-01
Highlights: ► n-Octanol/water partition coefficients of propranolol and atenolol were measured. ► The effect of temperature on the partition coefficient was studied. ► The equilibrium data were correlated using the NRTL and UNIQUAC activity models. ► The binary interaction parameters of the activity models were reported. ► It is concluded that propranolol is more hydrophobic than the atenolol at 298.15 K. - Abstract: The n-octanol/water partition coefficients of propranolol and atenolol were experimentally determined by ultraviolet (UV) spectroscopy at T = (298.15, 310.15 and 314.15) K. All measurements were made at the maximum wavelength corresponding to maximum absorption. The results showed that the n-octanol/water partition coefficients of propranolol and atenolol increase with the increase of temperature. The experimental data of this work were also used to examine the phase equilibrium correlating capability of some liquid-phase models. The equilibrium experimental data were correlated using the NRTL and UNIQUAC activity coefficient models and the binary interaction parameters were reported. The average root-mea n-square deviations (RMSD) between the experimental and calculated mass fractions of the (n-octanol + propranolol + water) and (n-octanol + atenolol + water) systems were determined. From the partition coefficients obtained, it is concluded that propranolol (log P ow = 3.12 ± 0.14) is more hydrophobic than the atenolol (log P ow = 0.16 ± 0.01) at T = 298.15 K.
The surface tension of pure liquids. Thermodynamic components and corresponding states
Lyklema, J.
1999-01-01
From the temperature dependency of surface and interfacial tensions the surface excess energy and entropy per unit area can be obtained. The excess energy is a liquid-specific property; it varies over about three decades between liquid helium and molten metals. On the other hand, the excess entropy
Energy Technology Data Exchange (ETDEWEB)
Gordillo-Vazquez, F J [Instituto de Astrofisica de Andalucia (IAA), CSIC, PO Box 3004, 18080 Granada (Spain); Donko, Z [Research Institute for Solid State Physics and Optics, H-1525 Budapest, PO Box, 49 (Hungary)
2009-08-15
A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25 deg. S and +25 deg. N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, {approx}215 K (at 11 km) and {approx}198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N {<=} 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas
International Nuclear Information System (INIS)
Gordillo-Vazquez, F J; Donko, Z
2009-01-01
A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25 deg. S and +25 deg. N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, ∼215 K (at 11 km) and ∼198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N ≤ 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas temperature is only slightly
Dobosz, Alexandra; Gancarz, Tomasz
2018-03-01
The data for the physicochemical properties viscosity, density, and surface tension obtained by different experimental techniques have been analyzed for liquid Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn eutectic alloys. All experimental data sets have been categorized and described by the year of publication, the technique used to obtain the data, the purity of the samples and their compositions, the quoted uncertainty, the number of data in the data set, the form of data, and the temperature range. The proposed standard deviations of liquid eutectic Al-Zn, Ag-Sn, Bi-Sn, Cu-Sn, and Sn-Zn alloys are 0.8%, 0.1%, 0.5%, 0.2%, and 0.1% for the density, 8.7%, 4.1%, 3.6%, 5.1%, and 4.0% for viscosity, and 1.0%, 0.5%, 0.3%, N/A, and 0.4% for surface tension, respectively, at a confidence level of 95%.
Energy Technology Data Exchange (ETDEWEB)
Suzuki, K [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H [Toyo Construction Co. Ltd., Tokyo (Japan)
1997-12-31
The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.
Energy Technology Data Exchange (ETDEWEB)
Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)
1996-12-31
The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.
Sasaki, Satoshi; Iida, Yoshinori
2009-06-01
The effect of kinematic viscosity and surface tension of the solution was investigated by adding catalase, glucose oxidase, or glucose on the bubble movement in a catalase-hydrogen peroxide system. The kinematic viscosity was measured using a Cannon-Fenske kinematic viscometer. The surface tension of the solution was measured by the Wilhelmy method using a self-made apparatus. The effects of the hole diameter/cell wall thickness, catalase concentration, glucose concentration, and glucose oxidase concentration on the kinematic viscosity, surface tension, and bubble take-off period were investigated. With our system, the effects of the changes in the solution materiality on the bubble take-off period were proven to be very small in comparison to the change in the oxygen-producing rate.
Boudys, M
1991-01-01
Variations of temperature coefficients of permittivity epsilon(33)(T), elastic compliances at constant electric fields s(11)(E), and constant polarization s(11)(P) with a Zr/Ti ratio of Pb(Zr(x)Ti(1-x))O(3) and Pb[(Sb(1/3)Mn(2/3))(0.05)Zr(x)Ti (0.95-x)]O(3) solid solutions, were investigated. Relations between temperature coefficients of epsilon(33)(T ), S(11)(E), and S(11) (P) were theoretically derived; a discrepancy was found between theoretical relations and experimental results. On the basis of the observed discrepancy, it is proposed that some extrinsic effects arising from the motion of interphase boundaries between the tetragonal and the rhombohedral phases which exist in grains contribute to values of both elastic compliances.
International Nuclear Information System (INIS)
Raisic, N.; Klinc, T.
1968-11-01
The ratio of the reactivity changes of a nuclear reactor produced by successive introduction of two different neutron absorbers in the reactor core, has been measured and information on effective neutron temperature at a particular point obtained. Boron was used as a l/v absorber and cadmium as an absorber sensiti ve to neutron temperature. Effective neutron temperature distribution has been deduced by moving absorbers across the reactor core and observing the corresponding reactivity changes. (author)
Copolovici, Lucian O; Niinemets, Ulo
2005-12-01
To model the emission dynamics and changes in fractional composition of monoterpenoids from plant leaves, temperature dependencies of equilibrium coefficients must be known. Henry's law constants (H(pc), Pa m3 mol(-1) and octanol/water partition coefficients (K(OW), mol mol(-1)) were determined for 10 important plant monoterpenes at physiological temperature ranges (25-50 degrees C for H(pc) and 20-50 degrees C for K(OW)). A standard EPICS procedure was established to determine H(pc) and a shake flask method was used for the measurements of K(OW). The enthalpy of volatilization (deltaH(vol)) varied from 18.0 to 44.3 kJ mol(-1) among the monoterpenes, corresponding to a range of temperature-dependent increase in H(pc) between 1.3- and 1.8-fold per 10 degrees C rise in temperature. The enthalpy of water-octanol phase change varied from -11.0 to -23.8 kJ mol(-1), corresponding to a decrease of K(OW) between 1.15- and 1.32-fold per 10 degrees C increase in temperature. Correlations among physico-chemical characteristics of a wide range of monoterpenes were analyzed to seek the ways of derivation of H(pc) and K(OW) values from other monoterpene physico-chemical characteristics. H(pc) was strongly correlated with monoterpene saturated vapor pressure (P(v)), and for lipophilic monoterpenes, deltaH(vol) scaled positively with the enthalpy of vaporization that characterizes the temperature dependence of P(v) Thus, P(v) versus temperature relations may be employed to derive the temperature relations of H(pc) for these monoterpenes. These data collectively indicate that monoterpene differences in H(pc) and K(OW) temperature relations can importantly modify monoterpene emissions from and deposition on plant leaves.
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
Directory of Open Access Journals (Sweden)
Li Benkai
2016-08-01
Full Text Available Vegetable oil can be used as a base oil in minimal quantity of lubrication (MQL. This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force, and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grinding temperature, and energy ratio coefficient of MQL grinding were compared among the seven vegetable oil types. Results revealed that (1 castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient; (2 palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient; (3 MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil; (4 viscosity significantly influences grinding force and grinding temperature to a greater extent than fatty acid varieties and contents in vegetable oils; (5 although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less viscous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature; (6 saturated fatty acid is a more efficient lubricant than unsaturated fatty acid; and (7 a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force, 87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7% energy
International Nuclear Information System (INIS)
Moh, Jeong Hah; Cho, Y. I.
2014-01-01
This paper presents the theoretical analysis of a flow driven by surface tension and gravity in an inclined circular tube. A governing equation is developed for describing the displacement of a non-Newtonian fluid(Power-law model) that continuously flows into a circular tube owing to surface tension, which represents a second-order, nonlinear, non-homogeneous, and ordinary differential form. It was found that quantitatively, the theoretical predictions of the governing equation were in excellent agreement with the solutions of the equation for horizontal tubes and the past experimental data. In addition, the predictions compared very well with the results of the force balance equation for steady
Negative temperature coefficient of the action of DDT in a sense organ
Bercken, J. van den; Akkermans, L.M.A.
1972-01-01
DDT induced repetitive spontaneuos activity inthe afferent nerve fibers of the lateral-line organ of the clawed toad, Xenopus laevis. The action of DDT increased markedly with lowered temperature. This temperature-effect was easily reversible. The results demonstrate that DDT has a definite negative
International Nuclear Information System (INIS)
Lesnaya, M.I.; Volokitin, G.G.; Kashchuk, V.A.
1976-01-01
Results are reported of an experimental research into the influence of small additions of α-transition metals on the temperature coefficient of linear expansion of titanium and vanadium. Using the configuration model of substance as the basis, expeained are the lowering of the critical liquefaction temperature or the melting point of vanadium and the raising of it, as caused by the addition of metals of the 6 group of the periodic chart and by the addition of metals of the 8 group, respectively, and also a shift in the temperature of the polymorphic α-β-transformation of titanium. Suggested as the best alloying metal for vanadium are tungsten and tantalum; for titaniums is vanadium whose admixtures lower the melting point and shift the polymorphic transformation temperature by as much as 100 to 120 degrees
Trinh, E. H.
1995-01-01
Non-contact methods have been implemented in conjunction with levitation techniques to carry out the measurement of the macroscopic properties of liquids significantly cooled below their nominal melting point. Free suspension of the sample and remote methods allow the deep excursion into the metastable liquid state and the determination of its thermophysical properties. We used this approach to investigate common substances such as water, o-terphenyl, succinonitrile, as well as higher temperature melts such as molten indium, aluminum and other metals. Although these techniques have thus far involved ultrasonic, electromagnetic, and more recently electrostatic levitation, we restrict our attention to ultrasonic methods in this paper. The resulting magnitude of maximum thermal supercooling achieved have ranged between 10 and 15% of the absolute temperature of the melting point for the materials mentioned above. The physical properties measurement methods have been mostly novel approaches, and the typical accuracy achieved have not yet matched their standard equivalent techniques involving contained samples and invasive probing. They are currently being refined, however, as the levitation techniques become more widespread, and as we gain a better understanding of the physics of levitated liquid samples.
International Nuclear Information System (INIS)
Talamo, Alberto
2007-01-01
We analytically evaluated the fuel coefficient of temperature both for pebble bed and prismatic high temperature reactors when they utilize as fuel plutonium and minor actinides from light water reactors spent fuel or a mixture of 50% uranium, enriched 20% in 235 U, and 50% thorium. In both cores the calculation involves the evaluation of the resonances integrals of the high absorbers fuel nuclides 240 Pu, 238 U and 232 Th and it requires the esteem of the Dancoff-Ginsburg factor for a pebble bed or prismatic core. The Dancoff-Ginsburg factor represents the only discriminating parameter in the results for the two different reactors types; in fact, both the pebble bed and the prismatic reactors share the same the pseudo-cross-section describing an infinite medium made of graphite filled by TRISO particles. We considered only the resolved resonances with a statistical spin factor equal to one and we took into account 267, 72, 212 resonances in the range 1.057-5692, 6.674-14485, 21.78-3472 eV for 240 Pu, 238 U and 232 Th, respectively, for investigating the influence on the fuel temperature reactivity coefficient of the variation of the TRISO kernel radius and TRISO particles packing fraction from 100, 200 to 300 μm and from 10% to 50%, respectively. Finally, in the pebble bed core, we varied the radius of the pebble for setting a fuel temperature reactivity coefficient similar to the one of a prismatic core
Schmidtke, B; Petzold, N; Kahlau, R; Hofmann, M; Rössler, E A
2012-10-01
The phenomenon of the glass transition is an unresolved problem in condensed matter physics. Its prominent feature, the super-Arrhenius temperature dependence of the transport coefficients, remains a challenge to be described over the full temperature range. For a series of molecular glass formers, we combined τ(T) collected from dielectric spectroscopy and dynamic light scattering covering a range 10(-12) s < τ(T) < 10(2) s. Describing the dynamics in terms of an activation energy E(T), we distinguish a high-temperature regime characterized by an Arrhenius law with a constant activation energy E(∞) and a low-temperature regime for which E(coop)(T) ≡ E(T)-E(∞) increases exponentially while cooling. A scaling is introduced, specifically E(coop)(T)/E(∞) [proportionality] exp[-λ(T/T(A)-1)], where λ is a fragility parameter and T(A) a reference temperature proportional to E(∞). In order to describe τ(T) still the attempt time τ(∞) has to be specified. Thus, a single interaction parameter E(∞) describing the high-temperature regime together with λ controls the temperature dependence of low-temperature cooperative dynamics.
Surface tension of decane binary and ternary mixtures with eicosane, docosane, and tetracosane
DEFF Research Database (Denmark)
Queimada, Antonio; Cao, A.I.; Marrucho, I.M.
2005-01-01
-C24H50 and the ternary n-C10H22 + n-C20H42 + n-C24H50 were measured from 293.15 K (or above the solution melting temperature) up to 343.15 K. An average absolute deviation of 1.3% was obtained in comparison with pure component literature data. No mixture information for the reported systems was found......A tensiometer operating on the Wilhelmy plate method was employed to measure liquid-vapor interfacial tensions of three binary mixtures and one ternary mixture of decane with eicosane, docosane, and tetracosane. Tensions of binary mixtures n-C10H22 + n-C20H42, n-C10H22 + n-C22H46, and n-C10H22 + n...
Gao, Zhiqiang; Wu, Ruixuan; Wang, Yuteng; Gao, Yuan; Liu, Xiaowei; Zhu, Jiaqi
2018-05-01
Quartz oscillator has been widely used as reference clock source in the microsystems due to its good performance. But a good crystal oscillator costs too much and its bulky size is not desired. This paper aims at designing an alternative integrated oscillator to replace the external quartz oscillator. The proposed circuit used maneatis delay cell to construct a ring oscillator for its superior linear I-V characteristic. As for a frequency reference clock, its frequency stability over temperature is required at first. After detailed mathematical deducing and careful analysis, a formula is proposed to describe the relationship between desired control voltage and temperature by assuming the frequency as constant. This paper utilized bipolar transistor as the temperature sensor, combining it with CTAT current source and resistor to create a first-order temperature compensation control voltage. The chip with typical frequency of 10 MHz was fabricated in a 0.35 μm CMOS technology and occupied 0.45 mm2. The measured results show that the frequency variation is ±0.2% for supply changes from 4.8 V to 5 V, and frequency variation is 48 ppm when the temperature change is from ‑40∘C to 85∘C, while the average current of the tested chip consumes 50 μA from 5 V.
International Nuclear Information System (INIS)
Messina, M.; Schenter, G.K.; Garrett, B.C.
1995-01-01
The low temperature behavior of the centroid density method of Voth, Chandler, and Miller (VCM) [J. Chem. Phys. 91, 7749 (1989)] is investigated for tunneling through a one-dimensional barrier. We find that the bottleneck for a quantum activated process as defined by VCM does not correspond to the classical bottleneck for the case of an asymmetric barrier. If the centroid density is constrained to be at the classical bottleneck for an asymmetric barrier, the centroid density method can give transmission coefficients that are too large by as much as five orders of magnitude. We follow a variational procedure, as suggested by VCM, whereby the best transmission coefficient is found by varying the position of the centroid until the minimum value for this transmission coefficient is obtained. This is a procedure that is readily generalizable to multidimensional systems. We present calculations on several test systems which show that this variational procedure greatly enhances the accuracy of the centroid density method compared to when the centroid is constrained to be at the barrier top. Furthermore, the relation of this procedure to the low temperature periodic orbit or ''instanton'' approach is discussed. copyright 1995 American Institute of Physics
Mid-infrared response of reduced graphene oxide and its high-temperature coefficient of resistance
Directory of Open Access Journals (Sweden)
Haifeng Liang
2014-10-01
Full Text Available Much effort has been made to study the formation mechanisms of photocurrents in graphene and reduced graphene oxide films under visible and near-infrared light irradiation. A built-in field and photo-thermal electrons have been applied to explain the experiments. However, much less attention has been paid to clarifying the mid-infrared response of reduced graphene oxide films at room temperature. Thus, mid-infrared photoresponse and annealing temperature-dependent resistance experiments were carried out on reduced graphene oxide films. A maximum photocurrent of 75 μA was observed at room temperature, which was dominated by the bolometer effect, where the resistance of the films decreased as the temperature increased after they had absorbed light. The electrons localized in the defect states and the residual oxygen groups were thermally excited into the conduction band, forming a photocurrent. In addition, a temperature increase of 2 °C for the films after light irradiation for 2 minutes was observed using absorption power calculations. This work details a way to use reduced graphene oxide films that contain appropriate defects and residual oxygen groups as bolometer-sensitive materials in the mid-infrared range.
Liu, W.; Xu, J.; Smith, A. K.; Yuan, W.
2017-12-01
Ground-based observations of the OH(9-4, 8-3, 6-2, 5-1, 3-0) band airglows over Xinglong, China (40°24'N, 117°35'E) from December 2011 to 2014 are used to calculate rotational temperatures. The temperatures are calculated using five commonly used Einstein coefficient datasets. The kinetic temperature from TIMED/SABER is completely independent of the OH rotational temperature. SABER temperatures are weighted vertically by weighting functions calculated for each emitting vibrational state from two SABER OH volume emission rate profiles. By comparing the ground-based OH rotational temperature with SABER's, five Einstein coefficient datasets are evaluated. The results show that temporal variations of the rotational temperatures are well correlated with SABER's; the linear correlation coefficients are higher than 0.72, but the slopes of the fit between the SABER and rotational temperatures are not equal to 1. The rotational temperatures calculated using each set of Einstein coefficients produce a different bias with respect to SABER; these are evaluated over each of vibrational levels to assess the best match. It is concluded that rotational temperatures determined using any of the available Einstein coefficient datasets have systematic errors. However, of the five sets of coefficients, the rotational temperature derived with the Langhoff et al.'s (1986) set is most consistent with SABER. In order to get a set of optimal Einstein coefficients for rotational temperature derivation, we derive the relative values from ground-based OH spectra and SABER temperatures statistically using three year data. The use of a standard set of Einstein coefficients will be beneficial for comparing rotational temperatures observed at different sites.
Czech Academy of Sciences Publication Activity Database
Klomfar, Jaroslav; Součková, Monika; Pátek, Jaroslav
2015-01-01
Roč. 385, January (2015), s. 62-71 ISSN 0378-3812 R&D Projects: GA ČR GA13-00145S Institutional support: RVO:61388998 Keywords : ionic liquid * density * surface tension * odd-even effect Subject RIV: BJ - Thermodynamics Impact factor: 1.846, year: 2015
Wit, PJ; vanderMei, HC; Busscher, HJ
1997-01-01
By allowing an air-bubble to pass through a parallel plate flow chamber with negatively charged, colloidal polystyrene particles adhering to the bottom collector plate of the chamber, the detachment of adhering particles stimulated by surface tension forces induced by the passage of a liquid-air
Tao, Tao
2018-03-20
Acetaldehyde is an observed emission species and a key intermediate produced during the combustion and low-temperature oxidation of fossil and bio-derived fuels. Investigations into the low-temperature oxidation chemistry of acetaldehyde are essential to develop a better core mechanism and to better understand auto-ignition and cool flame phenomena. Here, the oxidation of acetaldehyde was studied at low-temperatures (528–946 K) in a jet-stirred reactor (JSR) with the corrected residence time of 2.7 s at 700 Torr. This work describes a detailed set of experimental results that capture the negative temperature coefficient (NTC) behavior in the low-temperature oxidation of acetaldehyde. The mole fractions of 28 species were measured as functions of the temperature by employing a vacuum ultra-violet photoionization molecular-beam mass spectrometer. To explain the observed NTC behavior, an updated mechanism was proposed, which well reproduces the concentration profiles of many observed peroxide intermediates. The kinetic analysis based on the updated mechanism reveals that the NTC behavior of acetaldehyde oxidation is caused by the competition between the O-addition to and the decomposition of the CHCO radical.
Tao, Tao; Sun, Wenyu; Hansen, Nils; Jasper, Ahren W.; Moshammer, Kai; Chen, Bingjie; Wang, Zhandong; Huang, Can; Dagaut, Philippe; Yang, Bin
2018-01-01
Acetaldehyde is an observed emission species and a key intermediate produced during the combustion and low-temperature oxidation of fossil and bio-derived fuels. Investigations into the low-temperature oxidation chemistry of acetaldehyde are essential to develop a better core mechanism and to better understand auto-ignition and cool flame phenomena. Here, the oxidation of acetaldehyde was studied at low-temperatures (528–946 K) in a jet-stirred reactor (JSR) with the corrected residence time of 2.7 s at 700 Torr. This work describes a detailed set of experimental results that capture the negative temperature coefficient (NTC) behavior in the low-temperature oxidation of acetaldehyde. The mole fractions of 28 species were measured as functions of the temperature by employing a vacuum ultra-violet photoionization molecular-beam mass spectrometer. To explain the observed NTC behavior, an updated mechanism was proposed, which well reproduces the concentration profiles of many observed peroxide intermediates. The kinetic analysis based on the updated mechanism reveals that the NTC behavior of acetaldehyde oxidation is caused by the competition between the O-addition to and the decomposition of the CHCO radical.
Directory of Open Access Journals (Sweden)
D. O. Topping
2007-01-01
Full Text Available In order to predict the physical properties of aerosol particles, it is necessary to adequately capture the behaviour of the ubiquitous complex organic components. One of the key properties which may affect this behaviour is the contribution of the organic components to the surface tension of aqueous particles in the moist atmosphere. Whilst the qualitative effect of organic compounds on solution surface tensions has been widely reported, our quantitative understanding on mixed organic and mixed inorganic/organic systems is limited. Furthermore, it is unclear whether models that exist in the literature can reproduce the surface tension variability for binary and higher order multi-component organic and mixed inorganic/organic systems of atmospheric significance. The current study aims to resolve both issues to some extent. Surface tensions of single and multiple solute aqueous solutions were measured and compared with predictions from a number of model treatments. On comparison with binary organic systems, two predictive models found in the literature provided a range of values resulting from sensitivity to calculations of pure component surface tensions. Results indicate that a fitted model can capture the variability of the measured data very well, producing the lowest average percentage deviation for all compounds studied. The performance of the other models varies with compound and choice of model parameters. The behaviour of ternary mixed inorganic/organic systems was unreliably captured by using a predictive scheme and this was dependent on the composition of the solutes present. For more atmospherically representative higher order systems, entirely predictive schemes performed poorly. It was found that use of the binary data in a relatively simple mixing rule, or modification of an existing thermodynamic model with parameters derived from binary data, was able to accurately capture the surface tension variation with concentration. Thus
Zhang, Xi; Zheng, Shaodi; Zheng, Xiaofang; Liu, Zhengying; Yang, Wei; Yang, Mingbo
2016-03-21
In this article, the positive temperature coefficient (PTC) effect was studied for high-density polyethylene (HDPE)/carbon fiber (CF) composites. All of the samples showed a significant PTC effect during the heating processes without a negative temperature coefficient (NTC) effect, even at a temperature much higher than the melting point of the polymer matrix. An ever-increasing PTC intensity with increasing thermal cycles was observed in our study that had never been reported in previous research. The absence of a NTC effect resulted from the increased binding force between the matrix and fillers that contributed to the very special structure of CF surface. We incorporated thermal expansion theory and quantum tunneling effects to explain PTC effect. From the SEM micrographs for the HDPE/CF composites before and after the different thermal cycles, we found that the surface of CF was covered with a layer of polymer which resulted in a change in the gap length between CF and HDPE and its distribution. We believed that the gap change induced by polymer absorption on the fiber surface had a great effect on the PTC effect.
Experimental determination of the K_{oo} fuel temperature coefficient for an HTGR lattice
Energy Technology Data Exchange (ETDEWEB)
Agostini, P.; Benedetti, F.; Brighenti, G.; Chiodi, P. L.; Dell' Oro, P.; Giuliani, C.; Tassan, S.
1974-10-15
This paper describes temperature-dependent k-infinity measurements conducted using an assembly of loose HTGR coated particles in the BR-2 reactor by means of null reactivity oscillating method comparing the effect of poisoned and unpoisoned lattices like tests performed in the Physical Constants Test Reactor (PCTR) at Hanford. The RB-2 reactor was the property of the Italian firm AGIP NUCLEARE and operated at the Montecuccolino Center in Bologna.
Energy Technology Data Exchange (ETDEWEB)
Izquierdo, M [Consejo Superior de Investigaciones Cientificas, Madrid (ES). Inst. de Optica; Aroca, S [Escuela Tecnica Superior de Ingenieros Industriales, Valladolid (ES). Catedratico de Ingenieria Termica
1990-04-01
A theoretical study of a lithium bromide absorption heat pump, used as a machine type I and aimed to produce heat at 120{sup 0}C via waste heat sources at 60{sup 0}C, is given. Real performance conditions are stated for each component of the machine. By means of thermodynamic diagrams (p, t, x) and (h, x), the required data are obtained for calculation of the heat recovered in the evaporator Q{sub e}, the heat delivered to the absorber Q{sub a} and to the condenser Q{sub c}, and the heat supplied to the generator Q{sub g}. The heat delivered by the hot solution to the cold solution in the heat recovered Q{sub r}, and the work W{sub p} done by the solution pump are calculated. The probable COP is calculated as close to 1.4 and the working temperature in the generator ranges from 178 to 200{sup 0}C. The heat produced by the heat pump is 22% cheaper than that obtained from a cogeneration system comprising a natural gas internal combustion engine and high temperature heat pump with mechanical compression. Compared with a high temperature heat pump with mechanical compression, the heat produced by the absorption heat pump is 31% cheaper. From (h, x) and (s, x) diagrams, exergy losses for each component can be determined leading to an exergetic efficiency of 75% which provides the quality index of the absorption cycle. (author).
International Nuclear Information System (INIS)
Makai, M.; Kalya, Z.; Nemes, I.; Pos, I.; Por, G.
2007-01-01
Moderator temperature coefficient of reactivity is not monitored during fuel cycles in WWER reactors, because it is not very easy or impossible to measure it without disturbing the normal operation. Two new methods were tested in our WWER type nuclear power plant to try methodologies, which enable to measure that important to safety parameter during the fuel cycle. One is based on small perturbances, and only small changes are requested in operation, the other is based on noise methods, which means it is without interference with reactor operation. Both method is new that aspects that they uses the plant computer data(VERONA) based signals calculated by C P ORCA diffusion code (Authors)
International Nuclear Information System (INIS)
Erradi, L.; Chetaine, A.; Chakir, E.; Kharchaf, A.; Elbardouni, T.; Elkhoukhi, T.
2005-01-01
In a previous work, we have analysed the main French experiments available on the reactivity temperature coefficient (RTC): CREOLE and MISTRAL experiments. In these experiments, the RTC has been measured in both UO 2 and UO 2 -PuO 2 PWR type lattices. Our calculations, using APOLLO2 code with CEA93 library based on JEF2.2 evaluation, have shown that the calculation error in UO 2 lattices is less than 1 pcm/C degrees which is considered as the target accuracy. On the other hand the calculation error in the MOX lattices is more significant in both low and high temperature ranges: an average error of -2 ± 0.5 pcm/C degrees is observed in low temperatures and an error of +3 ± 2 pcm/C degrees is obtained for temperatures higher than 250 C degrees. In the present work, we analysed additional experimental benchmarks on the RTC of UO 2 and MOX light water moderated lattices. To analyze these benchmarks and with the aim of minimizing uncertainties related to modelling of the experimental set up, we chose the Monte Carlo method which has the advantage of taking into account in the most exact manner the geometry of the experimental configurations. This analysis shows for the UO 2 lattices, a maximum experiment-calculation deviation of about 0,7 pcm/C degrees, which is below the target accuracy for this type of lattices. For the KAMINI experiment, which relates to the measurement of the RTC in a light water moderated lattice using U-233 as fuel our analysis shows that the ENDF/B6 library gives the best result, with an experiment-calculation deviation of the order of -0,16 pcm/C degrees. The analysis of the benchmarks using MOX fuel made it possible to highlight a discrepancy between experiment and calculation on the RTC of about -0.7 pcm/C degrees (for a range of temperatures going from 20 to 248 C degrees) and -1,2 pcm/C degrees (for a range of temperatures going from 20 to 80 C degrees). This result, in particular the tendency which has the error to decrease when the
Strotman, Lindsay N; Lin, Guangyun; Berry, Scott M; Johnson, Eric A; Beebe, David J
2012-09-07
Extraction and purification of DNA is a prerequisite to detection and analytical techniques. While DNA sample preparation methods have improved over the last few decades, current methods are still time consuming and labor intensive. Here we demonstrate a technology termed IFAST (Immiscible Filtration Assisted by Surface Tension), that relies on immiscible phase filtration to reduce the time and effort required to purify DNA. IFAST replaces the multiple wash and centrifugation steps required by traditional DNA sample preparation methods with a single step. To operate, DNA from lysed cells is bound to paramagnetic particles (PMPs) and drawn through an immiscible fluid phase barrier (i.e. oil) by an external handheld magnet. Purified DNA is then eluted from the PMPs. Here, detection of Clostridium botulinum type A (BoNT/A) in food matrices (milk, orange juice), a bioterrorism concern, was used as a model system to establish IFAST's utility in detection assays. Data validated that the DNA purified by IFAST was functional as a qPCR template to amplify the bont/A gene. The sensitivity limit of IFAST was comparable to the commercially available Invitrogen ChargeSwitch® method. Notably, pathogen detection via IFAST required only 8.5 μL of sample and was accomplished in five-fold less time. The simplicity, rapidity and portability of IFAST offer significant advantages when compared to existing DNA sample preparation methods.
Energy Technology Data Exchange (ETDEWEB)
Boogar, Rahman Sadeghi; Gheshlaghi, Reza; Mahdavi, Mahmood Akhavan [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)
2013-01-15
A microchannel was fabricated with glass tubes to investigate the effect of viscosity, surface tension, and flow rate on the liquid-liquid two-phase flow regime. Water and gasoil were selected as aqueous and organic working fluids, respectively. The two fluids were injected into the microchannel and created either slug or parallel profile depending on the applied conditions. The range of Reynolds and capillary numbers was chosen in such a way that neither inertia nor interfacial tension forces were negligible. Xanthan gum was used to increase viscosity and Triton X-100 (TX-100) and Sodium Dodecyl Sulfate (SDS) were used to reduce the interfacial tension. The results demonstrated that higher value of viscosity and flow rate increased interfacial area, but slug flow regime remained unchanged. The two surfactants showed different effects on the flow regime and interfacial area. Addition of TX-100 did not change the slug flow but decreased the interfacial area. In contrast, addition of SDS increased interfacial area by decreasing the slug’s length in the low concentrations and by switching from slug to parallel regime at high concentrations.
Temperature-related changes in respiration and Q10 coefficient of Guava
Directory of Open Access Journals (Sweden)
Bron Ilana Urbano
2005-01-01
Full Text Available Guava (Psidium guajava L. is a tropical fruit that presents fast post-harvest ripening; therefore it is a very perishable product. Inappropriate storage temperature and retail practices can accelerate fruit quality loss. The objective of this study was to evaluate the respiratory activity (RA, the ethylene production (EP and Q10 of guava fruit at different storage temperatures. 'Paluma' guava fruits were harvested at maturity stage 1 (dark-green skin and stored at either 1, 11, 21, 31 or 41ºC; RA and EP were determined after 12, 36, 84 and 156 h of storage. RA and EP rates at 1 and 11ºC were the lowest - 0.16 and 0.43 mmol CO2 kg-1 h-1 and 0.003 and 0.019 µmol C2H4 kg-1 h-1, respectively. When guavas were stored at 21ºC, a gradual increase occurred in RA and EP, reaching 2.24 mmol CO2 kg-1 h-1 and 0.20 µmol C2H4 kg-1 h-1, after 156 h of storage. The highest RA and EP were recorded for guavas stored at 31ºC. In spite of high RA, guavas stored at 41ºC presented EP similar to guavas stored at 11ºC, an indicator of heat-stress injury. Considering the 1-11ºC range, the mean Q10 value was around 3.0; the Q10 value almost duplicated at 11-21ºC range (5.9. At 21-31ºC and 31-41ºC, Q10 was 1.5 and 0.8, respectively. Knowing Q10, respiratory variation and ripening behavior in response to different temperatures, fruit storage and retail conditions can be optimized to reduce quality losses.
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.
Wang, Haiyan; Wang, Weizong; Yan, Joseph D.; Qi, Haiyang; Geng, Jinyue; Wu, Yaowu
2017-10-01
Ablation-controlled plasmas have been used in a range of technical applications where local thermodynamic equilibrium (LTE) is often violated near the wall due to the strong cooling effect caused by the ablation of wall materials. The thermodynamic and transport properties of ablated polytetrafluoroethylene (PTFE) vapor, which determine the flowing plasma behavior in such applications, are calculated based on a two-temperature model at atmospheric pressure. To our knowledge, no data for PTFE have been reported in the literature. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and the Guldberg-Waage equation according to van de Sanden et al’s derivation. The transport coefficients, including viscosity, thermal conductivity and electrical conductivity, are calculated with the most recent collision interaction potentials using Devoto’s electron and heavy-particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of the Chapman-Enskog method. Results are computed for different degrees of thermal non-equilibrium, i.e. the ratio of electron to heavy-particle temperatures, from 1 to 10, with electron temperature ranging from 300 to 40 000 K. Plasma transport properties in the LTE state obtained from the present work are compared with existing published results and the causes for the discrepancy analyzed. The two-temperature plasma properties calculated in the present work enable the modeling of wall ablation-controlled plasma processes.
International Nuclear Information System (INIS)
Wang, Haiyan; Qi, Haiyang; Wang, Weizong; Yan, Joseph D; Geng, Jinyue; Wu, Yaowu
2017-01-01
Ablation-controlled plasmas have been used in a range of technical applications where local thermodynamic equilibrium (LTE) is often violated near the wall due to the strong cooling effect caused by the ablation of wall materials. The thermodynamic and transport properties of ablated polytetrafluoroethylene (PTFE) vapor, which determine the flowing plasma behavior in such applications, are calculated based on a two-temperature model at atmospheric pressure. To our knowledge, no data for PTFE have been reported in the literature. The species composition and thermodynamic properties are numerically determined using the two-temperature Saha equation and the Guldberg–Waage equation according to van de Sanden et al ’s derivation. The transport coefficients, including viscosity, thermal conductivity and electrical conductivity, are calculated with the most recent collision interaction potentials using Devoto’s electron and heavy-particle decoupling approach but expanded to the third-order approximation (second-order for viscosity) in the frame of the Chapman–Enskog method. Results are computed for different degrees of thermal non-equilibrium, i.e. the ratio of electron to heavy-particle temperatures, from 1 to 10, with electron temperature ranging from 300 to 40 000 K. Plasma transport properties in the LTE state obtained from the present work are compared with existing published results and the causes for the discrepancy analyzed. The two-temperature plasma properties calculated in the present work enable the modeling of wall ablation-controlled plasma processes. (paper)
Energy Technology Data Exchange (ETDEWEB)
Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology - KTH, Roslagstullsbacken 21, S-10691 Stockholm (Sweden)]. E-mail: alby@anl.gov
2007-01-15
We analytically evaluated the fuel coefficient of temperature both for pebble bed and prismatic high temperature reactors when they utilize as fuel plutonium and minor actinides from light water reactors spent fuel or a mixture of 50% uranium, enriched 20% in {sup 235}U, and 50% thorium. In both cores the calculation involves the evaluation of the resonances integrals of the high absorbers fuel nuclides {sup 240}Pu, {sup 238}U and {sup 232}Th and it requires the esteem of the Dancoff-Ginsburg factor for a pebble bed or prismatic core. The Dancoff-Ginsburg factor represents the only discriminating parameter in the results for the two different reactors types; in fact, both the pebble bed and the prismatic reactors share the same the pseudo-cross-section describing an infinite medium made of graphite filled by TRISO particles. We considered only the resolved resonances with a statistical spin factor equal to one and we took into account 267, 72, 212 resonances in the range 1.057-5692, 6.674-14485, 21.78-3472 eV for {sup 240}Pu, {sup 238}U and {sup 232}Th, respectively, for investigating the influence on the fuel temperature reactivity coefficient of the variation of the TRISO kernel radius and TRISO particles packing fraction from 100, 200 to 300 {mu}m and from 10% to 50%, respectively. Finally, in the pebble bed core, we varied the radius of the pebble for setting a fuel temperature reactivity coefficient similar to the one of a prismatic core.
Directory of Open Access Journals (Sweden)
Natthaphon Raengthon
2016-03-01
Full Text Available The temperature coefficient of permittivity (TCε of BaTiO3–Bi(MeO3 solid solutions were investigated. It was determined that as the tolerance factor was decreased with the addition of Bi(MeO3, the TCε shifted from large negative values to TCε values approaching zero. It is proposed that the different bonding nature of the dopant cation affects the magnitude and temperature stability of the permittivity. This study suggests that the relationship between tolerance factor and TCε can be used as a guide to design new dielectric compounds exhibiting temperature-stable high permittivity characteristics, which is similar to past research on perovskite and pyrochlore-based microwave dielectrics.
Directory of Open Access Journals (Sweden)
Pinheiro Cleber
2008-07-01
Full Text Available Abstract Background One of the current shortcomings of radiofrequency (RF tumor ablation is its limited performance in regions close to large blood vessels, resulting in high recurrence rates at these locations. Computer models have been used to determine tissue temperatures during tumor ablation procedures. To simulate large vessels, either constant wall temperature or constant convective heat transfer coefficient (h have been assumed at the vessel surface to simulate convection. However, the actual distribution of the temperature on the vessel wall is non-uniform and time-varying, and this feature makes the convective coefficient variable. Methods This paper presents a realistic time-varying model in which h is a function of the temperature distribution at the vessel wall. The finite-element method (FEM was employed in order to model RF hepatic ablation. Two geometrical configurations were investigated. The RF electrode was placed at distances of 1 and 5 mm from a large vessel (10 mm diameter. Results When the ablation procedure takes longer than 1–2 min, the attained coagulation zone obtained with both time-varying h and constant h does not differ significantly. However, for short duration ablation (5–10 s and when the electrode is 1 mm away from the vessel, the use of constant h can lead to errors as high as 20% in the estimation of the coagulation zone. Conclusion For tumor ablation procedures typically lasting at least 5 min, this study shows that modeling the heat sink effect of large vessels by applying constant h as a boundary condition will yield precise results while reducing computational complexity. However, for other thermal therapies with shorter treatment using a time-varying h may be necessary.
Elastic scattering and transport coefficients for a quark plasma in SUf(3) at finite temperatures
Rehberg, P.; Klevansky, S. P.; Hüfner, J.
1996-02-01
The temperature dependence of the elastic-scattering processes qq' → qq' and q overlineq' → q overlineq' , with q, q' = u, d, s is studied as a function of the scattering angle and the center-of-mass energy of the collision within the framework of the SUf(3) Nambu-Jona-Lasinio model. Critical scattering at threshold is observed in the q overlineq' → q overlineq' process, leading to an enhancement of the cross section as occurs in the phenomenon of critical opalescence. Transport properties such as viscosity, mean free paths and thermal relaxation times are calculated. Strangeness enhancement is investigated via the chemical relaxation times, which are found to be considerably higher than those calculated via perturbative QCD. A comparison with the experimental values for the strangeness enhancement in S + S collisions leads to an upper limit of 4 fm/ c for the lifetime of the plasma.
Reilly, J.; Abdel-Jaber, H.; Yarnold, M.; Glisic, B.
2017-04-01
Structural Health Monitoring aims to characterize the performance of a structure from a combination of recorded sensor data and analytic techniques. Many methods are concerned with quantifying the elastic response of the structure, treating temperature changes as noise in the analysis. While these elastic profiles do demonstrate a portion of structural behavior, thermal loads on a structure can induce comparable strains to elastic loads. Understanding this relationship between the temperature of the structure and the resultant strain and displacement can provide in depth knowledge of the structural condition. A necessary parameter for this form of analysis is the Coefficient of Thermal Expansion (CTE). The CTE of a material relates the amount of expansion or contraction a material undergoes per degree change in temperature, and can be determined from temperature-strain relationship given that the thermal strain can be isolated. Many times with concrete, the actual amount of expansion with temperature in situ varies from the given values for the CTE due to thermally generated elastic strain, which complicates evaluation of the CTE. To accurately characterize the relationship between temperature and strain on a structure, the actual thermal behavior of the structure needs to be analyzed. This rate can vary for different parts of a structure, depending on boundary conditions. In a case of unrestrained structures, the strain in the structure should be linearly related to the temperature change. Thermal gradients in a structure can affect this relationship, as they induce curvature and deplanations in the cross section. This paper proposes a method that addresses these challenges in evaluating the CTE.
The impact of fuel temperature reactivity coefficient on loss of reactivity control accident
International Nuclear Information System (INIS)
Park, J. H.; Ryu, E. H.; Song, Y. M.; Jung, J. Y.
2012-01-01
Nuclear reactors experience small power fluctuations or anticipated operational transients during even normal power operation. During normal operation, the reactivity is mainly controlled by liquid zone controllers, adjuster rods, mechanical control absorbers, and moderator poison. Even when the reactor power is increased abruptly and largely from an accident and when reactor control systems cannot be actuated quickly due to a fast transient, the reactor should be controlled and stabilized by its inherent safety parameter, such as a negative PCR (Power Coefficient of Reactivity) feedback. A PWR (Pressurized Water Reactor), it is well designed for the reactor to have a negative PCR so that the reactor can be safely shut down or stabilized whenever an abrupt reactivity insertion into the reactor core occurs or the reactor power is abruptly increased. However, it is known that a CANDU reactor has a small amount of PCR, as either negative or positive, because of the different design basis and safety concepts from a PWR. CNSC's regulatory and safety regime has stated that; The PCR of CANDU reactors does not pose a significant risk. Consistent with Canadian nuclear safety requirements, nuclear power plants must have an appropriate combination of inherent and engineered safety features incorporated into the design of the reactor safety and control systems. A reactor design that has a PCR is quite acceptable provided that the reactor is stable against power fluctuations, and that the probability and consequences of any potential accidents that would be aggravated by a positive reactivity feedback are maintained within CNSCprescribed limits. Recently, it was issued licensing the refurbished Wolsong unit 1 in Korea to be operated continuously after its design lifetime in which the calculated PCR was shown to have a small positive value by applying the recent physics code systems, which are composed of WIMS IST, DRAGON IST, and RFSP IST. These code systems were transferred
Subramaniam, Shankar; Sun, Bo
2015-11-01
The presence of solid particles in a steady laminar flow generates velocity fluctuations with respect to the mean fluid velocity that are termed pseudo-turbulence. The level of these pseudo-turbulent velocity fluctuations has been characterized in statistically homogeneous fixed particle assemblies and freely evolving suspensions using particle-resolved direct numerical simulation (PR-DNS) by Mehrabadi et al. (JFM, 2015), and it is found to be a significant contribution to the total kinetic energy associated with the flow. The correlation of these velocity fluctuations with temperature (or a passive scalar) generates a flux term that appears in the transport equation for the average fluid temperature (or average scalar concentration). The magnitude of this transport of temperature-velocity covariance is quantified using PR-DNS of thermally fully developed flow past a statistically homogeneous fixed assembly of particles, and the budget of the average fluid temperature equation is presented. The relation of this transport term to the axial dispersion coefficient (Brenner, Phil. Trans. Roy. Soc. A, 1980) is established. The simulation results are then interpreted in the context of our understanding of axial dispersion in gas-solid flow. NSF CBET 1336941.
Wu, Jie; Yu, Sheng-Tao; Jiang, Bo-nan
1996-01-01
In this paper a numerical procedure for simulating two-fluid flows is presented. This procedure is based on the Volume of Fluid (VOF) method proposed by Hirt and Nichols and the continuum surface force (CSF) model developed by Brackbill, et al. In the VOF method fluids of different properties are identified through the use of a continuous field variable (color function). The color function assigns a unique constant (color) to each fluid. The interfaces between different fluids are distinct due to sharp gradients of the color function. The evolution of the interfaces is captured by solving the convective equation of the color function. The CSF model is used as a means to treat surface tension effect at the interfaces. Here a modified version of the CSF model, proposed by Jacqmin, is used to calculate the tension force. In the modified version, the force term is obtained by calculating the divergence of a stress tensor defined by the gradient of the color function. In its analytical form, this stress formulation is equivalent to the original CSF model. Numerically, however, the use of the stress formulation has some advantages over the original CSF model, as it bypasses the difficulty in approximating the curvatures of the interfaces. The least-squares finite element method (LSFEM) is used to discretize the governing equation systems. The LSFEM has proven to be effective in solving incompressible Navier-Stokes equations and pure convection equations, making it an ideal candidate for the present applications. The LSFEM handles all the equations in a unified manner without any additional special treatment such as upwinding or artificial dissipation. Various bench mark tests have been carried out for both two dimensional planar and axisymmetric flows, including a dam breaking, oscillating and stationary bubbles and a conical liquid sheet in a pressure swirl atomizer.
Nguyen, Phuc Nghia; Trinh Dang, Thuan Thao; Waton, Gilles; Vandamme, Thierry; Krafft, Marie Pierre
2011-10-04
The adsorption dynamics of a series of phospholipids (PLs) at the interface between an aqueous solution or dispersion of the PL and a gas phase containing the nonpolar, nonamphiphilic linear perfluorocarbon perfluorohexane (PFH) was studied by bubble profile analysis tensiometry. The PLs investigated were dioctanoylphosphatidylcholine (DiC(8)-PC), dilaurylphosphatidylcholine, dimyristoylphosphatidylcholine, and dipalmitoylphosphatidylcholine. The gas phase consisted of air or air saturated with PFH. The perfluorocarbon gas was found to have an unexpected, strong effect on both the adsorption rate and the equilibrium interfacial tension (γ(eq)) of the PLs. First, for all of the PLs, and at all concentrations investigated, the γ(eq) values were significantly lower (by up to 10 mN m(-1)) when PFH was present in the gas phase. The efficacy of PFH in decreasing γ(eq) depends on the ability of PLs to form micelles or vesicles in water. For vesicles, it also depends on the gel or fluid state of the membranes. Second, the adsorption rates of all the PLs at the interface (as assessed by the time required for the initial interfacial tension to be reduced by 30%) are significantly accelerated (by up to fivefold) by the presence of PFH for the lower PL concentrations. Both the surface-tension reducing effect and the adsorption rate increasing effect establish that PFH has a strong interaction with the PL monolayer and acts as a cosurfactant at the interface, despite the absence of any amphiphilic character. Fitting the adsorption profiles of DiC(8)-PC at the PFH-saturated air/aqueous solution interface with the modified Frumkin model indicated that the PFH molecule lay horizontally at the interface. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Mosteller, R.D.; Hall, R.A.; Lancaster, D.B.; Young, E.H.; Gavin, P.H.; Robertson, S.T.
1998-01-01
The contents of ANS 19.11, the standard for ''Calculation and Measurement of the Moderator Temperature Coefficient of Reactivity in Water-Moderated Power Reactors,'' are described. The standard addresses the calculation of the moderator temperature coefficient (MTC) both at standby conditions and at power. In addition, it describes several methods for the measurement of the at-power MTC and assesses their relative advantages and disadvantages. Finally, it specifies a minimum set of documentation requirements for compliance with the standard
International Nuclear Information System (INIS)
Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; Ji, Wei
2015-01-01
Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections
Strnat, R. M. W.; Liu, S.; Strnat, K. J.
1982-03-01
Flux-loss characteristics during long-term air aging of four rare-earth-cobalt matrix magnet types were measured. Irreversible losses and reversible temperature coefficients on heating above room temperature are reported. Purely magnetic and permanent microstructure-related changes during aging were differentiated by measuring hysteresis curves before and after long-term exposure. Three commercial polymer-bonded magnets using different rare-earth-cobalt-transition metal alloys and a solder-matrix magnet with Sm(Co, Cu, Fe, Zr)7.4 were studied. They were cycled between 25 °C and maximum temperatures to 150 °C (25 ° intervals) as applicable. Aging data at 50 and 125 °C for an exposure time of 3300 h are reported. The 2-17 samples have a stability far superior to bonded 1-5. The soft metal binder imparts significantly better aging behavior on precipitation-hardened 2-17 magnet alloys above 100 °C than an epoxy resin matrix.
Scholz, Norman; Behnke, Thomas; Resch-Genger, Ute
2018-01-01
Micelles are of increasing importance as versatile carriers for hydrophobic substances and nanoprobes for a wide range of pharmaceutical, diagnostic, medical, and therapeutic applications. A key parameter indicating the formation and stability of micelles is the critical micelle concentration (CMC). In this respect, we determined the CMC of common anionic, cationic, and non-ionic surfactants fluorometrically using different fluorescent probes and fluorescence parameters for signal detection and compared the results with conductometric and surface tension measurements. Based upon these results, requirements, advantages, and pitfalls of each method are discussed. Our study underlines the versatility of fluorometric methods that do not impose specific requirements on surfactants and are especially suited for the quantification of very low CMC values. Conductivity and surface tension measurements yield smaller uncertainties particularly for high CMC values, yet are more time- and substance consuming and not suitable for every surfactant.
Leong, Kai-Yang; Wang, Feng
2018-04-01
The surface tension of nanoscale droplets of water was studied with molecular dynamics simulations using the BLYPSP-4F water potential. The internal pressure of the droplet was measured using an empirical correlation between the pressure and density, established through a series of bulk simulations performed at pressures from 1 to 1000 bars. Such a procedure allows for reliable determination of internal pressure without the need to calculate the local virial. The surface tension, estimated with the Young-Laplace relation, shows good agreement with the Tolman equation with a Tolman length of -0.48 Å. The interface of a liquid water droplet is shown to be around 1.1-1.3 nm thick depending on radii. The fairly thick interface region puts a lower limit on the size of droplets that still have a bulk-like interior.
International Nuclear Information System (INIS)
Chakir, E.; Erradi, L.; Bardouni, T El.; Khoukhi, T El.; Boukhal, H.; Meroun, O.; Bakkari, B El
2007-01-01
Full text: In a previous work, we have analysed the main french experiments available on the reactivity temperature coefficient (RTC) : CREAOLE and Mistral experiments. In these experiments, the RTC has been measured in both UO2 and UO2-PuO2 PWR type lattices. Our calculations, using APPOLO2 code with CEA93 library based on JEF2.2 evaluation, have shown that the calculation error in UO2 lattices is less than 1 pcm/Deg C which is considered as the target accuracy. On the other hand the calculation error in the MOX lattices is more significant in both low and high temperature ranges : an average error of -2 ± 0.5 pcm/Deg C is observed in low temperatures and an error of +3±2 pcm/Deg C is obtained for temperature higher than 250Deg C. In the present work, we analysed additional experimental benchmarks on the RTC of UO2 and MOX light water moderated lattices. To analyze these benchmarks and with the aim of minimizing uncertainties related to modelling of the experimental set up, we chose the Monte Carlo Method which has the advantage of taking into account in the most exact manner the geometry of the experimental configurations. Thus we have used the code MCNP5, for its recognized power and its availability. This analysis shows for the UO2 lattices, an average experiment-calculation deviation of about 0,5 pcm/Deg C, which is largely below the target accuracy for this type of lattices, that we estimate at approximately 1 pcm/Deg C. For the KAMINI experiment, which relates to the measurement of the RTC in light water moderated lattice using U-233 as fuel our analysis shows that the Endf/B6 library gives the best result, with an experiment -calculation deviation of the order of -0,16 pcm/Deg C. The analysis of the benchmarks using MOX fuel made it possible to highlight a discrepancy between experiment and calculation on the RTC of about -0.7pcm/Deg C ( for a range of temperature going from 20 to 248 Deg C) and -1.2 pcm/Deg C ( for a range of temperature going from 20 to
Czech Academy of Sciences Publication Activity Database
Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav
2012-01-01
Roč. 333, NOV 15 2012 (2012), s. 38-46 ISSN 0378-3812 R&D Projects: GA ČR GA101/09/0010 Institutional research plan: CEZ:AV0Z20760514 Keywords : ionic liquid * tris(pentaﬂuoroethyl)triﬂuorophosphate * density * surface tension Subject RIV: BJ - Thermodynamics Impact factor: 2.379, year: 2012 http://www.sciencedirect.com/science/article/pii/S037838121200310X
Energy Technology Data Exchange (ETDEWEB)
Wei, Wenjuan, E-mail: Wenjuan.Wei@cstb.fr [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others
2016-09-01
The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.
International Nuclear Information System (INIS)
Demaziere, C.
2000-01-01
The Moderator Temperature Coefficient of reactivity (MTC) plays an important role in the feedback mechanism and thus in the inherent stability of Pressurised Water Reactors (PWRs). Due to the inaccuracy of the traditional at-power MTC measurement techniques, many power utilities nowadays only measure the zero-power MTC since its determination is relatively straightforward and accurate. For the at-power MTC determination during the remaining fuel cycle, core calculations are assumed to be reliable enough. Nevertheless, these calculations were never benchmarked and most importantly, the use of high burnup fuel might induce a slightly positive MTC at Beginning Of Cycle (BOC) due to the high initial boron concentration. Even if in such a case the Doppler effect would still insure a negative reactivity feedback, monitoring the MTC throughout the cycle could become crucial. In this respect, not only the sign of the MTC is of importance, but also its magnitude. Consequently, developing a method that would permit monitoring the MTC during the fuel cycle is of great interest. One of the main disadvantages of the traditional at-power MTC measurement techniques is that the reactor has to be perturbed in order to induce a change of the moderator temperature. The modification of other parameters that can only be estimated by core calculation represents also a severe drawback of these methods, both for their precision and their reliability. A measurement performed at Ringhals-4 by using the so-called boron dilution method revealed that the uncertainty associated to the MTC estimation could even be much larger than previously expected due to the calculated reactivity corrections. These corrections are very sensitive to the input parameters chosen for the core simulation, and slight mis-estimations of these have large reactivity effects. It is known that if the reactivity noise and the moderator temperature noise could be measured, the MTC could be determined without disturbing
Energy Technology Data Exchange (ETDEWEB)
Demaziere, C
2000-07-01
The Moderator Temperature Coefficient of reactivity (MTC) plays an important role in the feedback mechanism and thus in the inherent stability of Pressurised Water Reactors (PWRs). Due to the inaccuracy of the traditional at-power MTC measurement techniques, many power utilities nowadays only measure the zero-power MTC since its determination is relatively straightforward and accurate. For the at-power MTC determination during the remaining fuel cycle, core calculations are assumed to be reliable enough. Nevertheless, these calculations were never benchmarked and most importantly, the use of high burnup fuel might induce a slightly positive MTC at Beginning Of Cycle (BOC) due to the high initial boron concentration. Even if in such a case the Doppler effect would still insure a negative reactivity feedback, monitoring the MTC throughout the cycle could become crucial. In this respect, not only the sign of the MTC is of importance, but also its magnitude. Consequently, developing a method that would permit monitoring the MTC during the fuel cycle is of great interest. One of the main disadvantages of the traditional at-power MTC measurement techniques is that the reactor has to be perturbed in order to induce a change of the moderator temperature. The modification of other parameters that can only be estimated by core calculation represents also a severe drawback of these methods, both for their precision and their reliability. A measurement performed at Ringhals-4 by using the so-called boron dilution method revealed that the uncertainty associated to the MTC estimation could even be much larger than previously expected due to the calculated reactivity corrections. These corrections are very sensitive to the input parameters chosen for the core simulation, and slight mis-estimations of these have large reactivity effects. It is known that if the reactivity noise and the moderator temperature noise could be measured, the MTC could be determined without disturbing
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.
Energy Technology Data Exchange (ETDEWEB)
Tsierkezos, Nikos G. [Institut fuer Chemie, Humboldt-Universitaet zu Berlin, Brook-Taylor-Strasse 2, D-12489 Berlin (Germany)]. E-mail: tsierkezos@chemie.hu-berlin.de; Molinou, Ioanna E. [Physical Chemistry Laboratory, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771 (Greece)]. E-mail: imolinou@chem.uoa.gr
2007-08-15
Densities ({rho}), speeds of sound (u), isentropic compressibilities (k{sub s}), refractive indices (n{sub D}), and surface tensions ({sigma}) of binary mixtures of methyl salicylate (MSL) with 1-pentanol (PEN) have been measured over the entire composition range at the temperatures of 278.15K, 288.15K, and 303.15K. The excess molar volumes (V{sup E}), excess surface tensions ({sigma}{sup E}), deviations in speed of sound ({delta}u), deviations in isentropic compressibility ({delta}k{sub s}), and deviations in molar refraction ({delta}R) have been calculated. The excess thermodynamic properties V{sup E}, {sigma}{sup E}, {delta}u, {delta}k{sub s}, and {delta}R were fitted to the Redlich-Kister polynomial equation and the A{sub k} coefficients as well as the standard deviations (d) between the calculated and experimental values have been derived. The surface tension ({sigma}) values have been further used for the calculation of the surface entropy (S{sup S}) and the surface enthalpy (H{sup S}) per unit surface area. The lyophobicity ({beta}) and the surface mole fraction (x{sub 2}{sup S}) of the surfactant component PEN have been also derived using the extended Langmuir model. The results provide information on the molecular interactions between the unlike molecules that take place at the surface and the bulk.
International Nuclear Information System (INIS)
Tsierkezos, Nikos G.; Molinou, Ioanna E.
2007-01-01
Densities (ρ), speeds of sound (u), isentropic compressibilities (k s ), refractive indices (n D ), and surface tensions (σ) of binary mixtures of methyl salicylate (MSL) with 1-pentanol (PEN) have been measured over the entire composition range at the temperatures of 278.15K, 288.15K, and 303.15K. The excess molar volumes (V E ), excess surface tensions (σ E ), deviations in speed of sound (Δu), deviations in isentropic compressibility (Δk s ), and deviations in molar refraction (ΔR) have been calculated. The excess thermodynamic properties V E , σ E , Δu, Δk s , and ΔR were fitted to the Redlich-Kister polynomial equation and the A k coefficients as well as the standard deviations (d) between the calculated and experimental values have been derived. The surface tension (σ) values have been further used for the calculation of the surface entropy (S S ) and the surface enthalpy (H S ) per unit surface area. The lyophobicity (β) and the surface mole fraction (x 2 S ) of the surfactant component PEN have been also derived using the extended Langmuir model. The results provide information on the molecular interactions between the unlike molecules that take place at the surface and the bulk
International Nuclear Information System (INIS)
Jindaratsamee, Pinyarat; Shimoyama, Yusuke; Morizaki, Hironobu; Ito, Akira
2011-01-01
The permeability of carbon dioxide (CO 2 ) through imidazolium-based ionic liquid membranes was measured by a sweep gas method. Six species of ionic liquids were studied in this work as follows: [emim][BF 4 ], [bmim][BF 4 ], [bmim][PF 6 ], [bmim][Tf 2 N], [bmim][OTf], and [bmim][dca]. The ionic liquids were supported with a polyvinylidene fluoride porous membrane. The measurements were performed at T = (303.15 to 343.15) K. The partial pressure difference between feed and permeate sides was 0.121 MPa. The permeability of the CO 2 increases with temperature for the all ionic liquid species. Base on solution diffusion theory, it can be explained that the diffusion coefficient of CO 2 in an ionic liquid affects the temperature dependence more strongly than the solubility coefficient. The greatest permeability was obtained with the [bmim][Tf 2 N] membrane. The membrane of [bmim][PF 6 ] presents the lowest permeability. The separation coefficient between CO 2 and N 2 through the ionic liquid membranes was also investigated at the volume fraction of CO 2 at feed side 0.10. The separation coefficient decreases with the increase of temperature for the all ionic liquid species. The membrane of [emim][BF 4 ] and [bmim][BF 4 ] gives the highest separation coefficient at constant temperature. The lowest separation coefficient was obtained from [bmim][Tf 2 N] membrane which presents the highest permeability of CO 2 .
Energy Technology Data Exchange (ETDEWEB)
Feng Fuzhou; Chu Fulei; Guo Dan; Lu Wenxiu [Tsinghua Univ., Beijing, BJ (China). Dept. of Precision Instruments
2001-07-01
From data collected by an online condition monitoring and fault diagnosis system, a higher pad temperature at the upper guide bearing in a pumped storage power generator unit installed in Guangdong province(GPSPS), China, was found. And also a relatively intensive shaft vibration occurred at the lower guide bearing. By calculating the Reynolds equation and viscosity-temperature equation of the lubricant, a curve between the pre-load coefficient and the increment of pad temperature is obtained, which shows that the larger, the pre-load coefficient, the bigger, the increment of pad temperature. For a practical unit in GPSPS, by employing Transfer matrix method and Wilson-{theta} method to analyze shaft vibration at different pre-load coefficients of the whole bearing or ''pad pair'' bearings, the results show that the larger the pre-load coefficient is, the smaller the vibration amplitude is, the shorter the time for vibration to become steady is. And an uneven pre-load coefficient of the ''pad pair'' bearings will cause shaft orbit from a circle to an ellipse whose long axes is at the direction of the ''pad pair'' with the lowest pre-load coefficient. Finally, reasons of higher pad temperature of the upper guide bearing and larger shaft vibration at the lower guide bearing are due to the inconsistent relation of bearing assembling clearance or pre-load coefficient of the upper and lower guide bearing, and also due to the too small, uneven pre-load coefficient of ''pad pair'' bearings. After a scheme for adjusting the bearing clearance is given, data measured show that the analysis and simulation methods are correct and the adjustment scheme to the assembling clearance of the upper and lower guide bearings is feasible and can be used to guide the field maintenance conveniently. (orig.)
Sinev, Leonid S.; Petrov, Ivan D.
2017-01-01
Processing results of measurements of linear thermal expansion coefficients and linear thermal expansion of two brands of borosilicate glasses --- LK5 and Borofloat 33 --- are presented. The linear thermal expansion of glass samples have been determined in the temperature range 130 to 800 K (minus 143 to 526 $\\deg$C) using thermomechanical analyzer TMA7100. Relative imprecision of indirectly measured linear thermal expansion coefficients and linear thermal expansion of both glass brands is le...
Energy Technology Data Exchange (ETDEWEB)
Pyeon, Cheol Ho [Research Reactor Institute, Kyoto Univ., Osaka (Japan); Shim, Hyung Jin; Choi, Sung Hoon; Jeon, Byoung Kyu [Seoul National Univ., Seoul (Korea, Republic of); Ryu, Eun Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2012-10-15
The Kyoto University Critical Assembly (KUCA) is a multi-core type critical assembly consisting of three independent cores in the Kyoto University Research Reactor Institute. The light-water-moderated core (Ccore) is a tank type reactor, and the experiments of the isothermal temperature reactivity coefficient (ITRC) of C-core with a D{sub 2}O tank were carried out with the use of six 10 kW heaters and a radiator system in a dump tank, one 10 kW heater in a core tank, and one 5 kW heater in the D{sub 2}O tank. The ITRCs of the C-core with the D{sub 2}O tank immersed in the core tank are considered important to investigate the mechanism of moderation and reflection effects of H{sub 2}O and D{sub 2}O in the core on the evaluation by numerical simulations. The objectives of this paper are to report the ITRC measurements for C-core with D{sub 2}O tank ranging between 26.7 .deg. C and 58.5 .deg. C, and to examine the accuracy of the numerical simulations by the Seoul National University Monte Carlo code, McCARD, through the comparison between measured and calculated results.
Czech Academy of Sciences Publication Activity Database
Jungwirth, Pavel; Tobias, D. J.
2015-01-01
Roč. 448, Jun 15 (2015), s. 593 ISSN 0021-9797 Institutional support: RVO:61388963 Keywords : surface tension * Gibbs adsorption equation * hydroxide * water Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.782, year: 2015
Energy Technology Data Exchange (ETDEWEB)
Svetlov, I L; Sukhanov, N N; Krivko, A I; Roshchina, I N; Khatsinskaia, I M
1987-01-01
Experimental data are presented on the temperature dependence of the short- term strength characteristics, Young's modulus, and linear expansion coefficients of single crystals of a nickel alloy, ZhS6F, with crystallographic orientations along the 001, 111, 011, and 112 lines. It is found that the mechanical properties and Young's modulus of the alloy crystals exibit anisotropy in the temperature range 20-900 C. The linear thermal expansion coefficient is isotropic up to 900 C and equal to that of the equiaxed alloy. 10 references.
Buffoni, Boris; Groves, Mark D.; Wahlén, Erik
2018-06-01
Fully localised solitary waves are travelling-wave solutions of the three- dimensional gravity-capillary water wave problem which decay to zero in every horizontal spatial direction. Their existence has been predicted on the basis of numerical simulations and model equations (in which context they are usually referred to as `lumps'), and a mathematically rigorous existence theory for strong surface tension (Bond number {β} greater than {1/3}) has recently been given. In this article we present an existence theory for the physically more realistic case {0 point of the reduced functional is found by minimising it over its natural constraint set.
Czech Academy of Sciences Publication Activity Database
Vinš, Václav; Planková, Barbora; Hrubý, Jan
2013-01-01
Roč. 34, č. 5 (2013), s. 792-812 ISSN 0195-928X R&D Projects: GA AV ČR IAA200760905; GA ČR(CZ) GPP101/11/P046; GA ČR GA101/09/1633 Institutional research plan: CEZ:AV0Z20760514 Institutional support: RVO:61388998 Keywords : chemical polarity * gradient theory * surface tension Subject RIV: BJ - Thermodynamics Impact factor: 0.623, year: 2013 http://www.springerlink.com/openurl.asp?genre=article&id=doi:10.1007/s10765-012-1207-z
Barman, Biraj Kumar; Rajbanshi, Biplab; Yasmin, Ananya; Roy, Mahendra Nath
2018-05-01
The formation of the host-guest inclusion complexes of ionic liquids namely [BMIm]Cl and [HMIm]Cl with α-CD and β-CD were studied by means of physicochemical and spectroscopic methods. Conductivity and surface tension study were in good agreement with the 1H NMR and FT-IR studies which confirm the formation of the inclusion complexes. The Density and viscosity study also supported the formation of the ICs. Further the stoichiometry was determined 1:1 for each case and the association constants and thermodynamic parameters derived supported the most feasible formation of the [BMIm]Cl- β-CD inclusion complex.
Directory of Open Access Journals (Sweden)
Xiaogang Wu
2017-10-01
Full Text Available This study investigated the heat problems that occur during the operation of power batteries, especially thermal runaway, which usually take place in high temperature environments. The study was conducted on a ternary polymer lithium-ion battery. In addition, a lumped parameter thermal model was established to analyze the thermal behavior of the electric bus battery system under the operation conditions of the driving cycles of the Harbin city electric buses. Moreover, the quantitative relationship between the optimum heat transfer coefficient of the battery and the ambient temperature was investigated. The relationship between the temperature rise (Tr, the number of cycles (c, and the heat transfer coefficient (h under three Harbin bus cycles have been investigated at 30 °C, because it can provide a basis for the design of the battery thermal management system. The results indicated that the heat transfer coefficient that meets the requirements of the battery thermal management system is the cubic power function of the ambient temperature. Therefore, if the ambient temperature is 30 °C, the heat transfer coefficient should be at least 12 W/m2K in the regular bus lines, 22 W/m2K in the bus rapid transit lines, and 32 W/m2K in the suburban lines.
Energy Technology Data Exchange (ETDEWEB)
Talamo, Alberto E-mail: alby@neutron.kth.se; Gudowski, Waclaw E-mail: wacek@neutron.kth.se; Cetnar, Jerzy E-mail: jerzy@neutron.kth.se; Venneri, Francesco E-mail: venneri@lanl.gov
2004-11-01
We investigated some important neutronic features of the deep burn modular helium reactor (DB-MHR) using the MCNP/MCB codes. Our attention was focused on the neutron flux and its spectrum, capture to fission ratio of {sup 239}Pu and the temperature coefficient of fuel and moderator. The DB-MHR is a graphite-moderated helium-cooled reactor proposed by General Atomic to address the need for a fast and efficient incineration of plutonium for non-proliferation purposes as well as the management of light water reactors (LWRs) waste. In fact, recent studies have shown that the use of the DB-MHR coupled to ordinary LWRs would keep constant the world inventory of plutonium for a reactor fleet producing 400 TW{sub e}/y. In the present studies, the DB-MHR is loaded with Np-Pu driver fuel (DF) with an isotopic composition corresponding to LWRs spent fuel waste. DF uses fissile isotopes (e.g. {sup 239}Pu and {sup 241}Pu), previously generated in the LWRs, and maintains criticality conditions in the DB-MHR. After an irradiation of three years, the spent DF is reprocessed and its remaining actinides are manufactured into fresh transmutation fuel (TF). TF mainly contains non-fissile actinides which undergo neutron capture and transmutation during the subsequent three-year irradiation in the DB-MHR. At the same time, TF provides control and negative reactivity feedback to the reactor. After extraction of the spent TF, irradiated for three years, over 94% of {sup 239}Pu and 53% of all actinides coming from LWRs waste will have been destroyed in the DB-MHR. In this paper we look at the operation conditions at equilibrium for the DB-MHR and evaluate fluxes and reactivity responses using state of the art 3-D Monte Carlo simulations.
Energy Technology Data Exchange (ETDEWEB)
Nasirzadeh, Karamat E-mail: karamat.nasirzadeh@chemie.uni-regensburg.de; Neueder, Roland; Kunz, Werner
2004-06-01
Precise vapor pressure data for pure acetonitrile and (LiBr + acetonitrile) are given for temperatures ranging from T=(298.15 to 343.15) K. The molality range is from m=(0.0579 to 0.8298) mol {center_dot} kg{sup -1}. The osmotic coefficients are calculated by taking into account the second virial coefficient of acetonitrile. The parameters of the extended Pitzer ion interaction model of Archer and the mole fraction-based thermodynamic model of Clegg-Pitzer are evaluated. These models accurately reproduce the available osmotic coefficients. The parameters of the extended Pitzer ion interaction model of Archer are used to calculate the mean molal activity coefficients.
International Nuclear Information System (INIS)
Kawahara, Akimaro; Sadatomi, Michio; Higuchi, Tatsuya
2009-01-01
Two-phase diversion cross-flow between tight lattice subchannels has been investigated experimentally and analytically. For hydraulically non-equilibrium flows with the pressure difference between the subchannels, experiments were conducted using a vertical multiple-channel with two subchannels simplifying a triangle tight lattice rod bundle. To know the effects of the reduced surface tension on the diversion cross-flow, water and water with a surfactant were used as the test liquids. Data were obtained on the axial variations in the pressure difference between the subchannels, gas and liquid flow rates and void fraction in each subchannel for slug-churn and annular flows. In the analysis, flow redistribution processes due to the diversion cross-flow have been calculated by our subchannel analysis code based on a two-fluid model. From a comparison between the experiment and the code calculation, the code was found to be valid against the present data if the improved constitutive equations of wall and interfacial friction reported in our previous paper were incorporated to account for the reduced surface tension effects. (author)
Directory of Open Access Journals (Sweden)
S. Ekström
2009-02-01
Full Text Available A significant fraction of the organic material in aerosols is made of highly soluble compounds such as sugars (mono- and polysaccharides and polyols such as the 2-methyltetrols, methylerythritol and methyltreitol. Because of their high solubility these compounds are considered as potentially efficient CCN material. For the 2-methyltetrols, this would have important implications for cloud formation at global scale because they are thought to be produced by the atmospheric oxidation of isoprene. To investigate this question, the complete Köhler curves for C3-C6 polyols and the 2-methyltetrols have been determined experimentally from osmolality and surface tension measurements. Contrary to what was expected, none of these compounds displayed a higher CCN efficiency than organic acids. Their Raoult terms show that this limited CCN efficiency is due to their absence of dissociation in water, this in spite of slight surface-tension effects for the 2-methyltetrols. Thus, compounds such as saccharides and polyols would not contribute more to cloud formation than other organic compounds studied so far. In particular, the presence of 2-methyltetrols in aerosols would not particularly enhance cloud formation in the atmosphere, in contrary to recently suggested.
International Nuclear Information System (INIS)
Zhong, Xinxin; Zhao, Yi; Cao, Jianshu
2014-01-01
The time-dependent wavepacket diffusion method for carrier quantum dynamics (Zhong and Zhao 2013 J. Chem. Phys. 138 014111), a truncated version of the stochastic Schrödinger equation/wavefunction approach that approximately satisfies the detailed balance principle and scales well with the size of the system, is applied to investigate the carrier transport in one-dimensional systems including both the static and dynamic disorders on site energies. The predicted diffusion coefficients with respect to temperature successfully bridge from band-like to hopping-type transport. As demonstrated in paper I (Moix et al 2013 New J. Phys. 15 085010), the static disorder tends to localize the carrier, whereas the dynamic disorder induces carrier dynamics. For the weak dynamic disorder, the diffusion coefficients are temperature-independent (band-like property) at low temperatures, which is consistent with the prediction from the Redfield equation, and a linear dependence of the coefficient on temperature (hopping-type property) only appears at high temperatures. In the intermediate regime of dynamic disorder, the transition from band-like to hopping-type transport can be easily observed at relatively low temperatures as the static disorder increases. When the dynamic disorder becomes strong, the carrier motion can follow the hopping-type mechanism even without static disorder. Furthermore, it is found that the memory time of dynamic disorder is an important factor in controlling the transition from the band-like to hopping-type motions. (paper)
Czech Academy of Sciences Publication Activity Database
Součková, Monika; Klomfar, Jaroslav; Pátek, Jaroslav
2016-01-01
Roč. 100, September (2016), s. 79-88 ISSN 0021-9614 R&D Projects: GA ČR GA13-00145S Institutional support: RVO:61388998 Keywords : 1-Cn-3-methylimidazolium cation * tetrafluoroborate anion * density–temperature relation * surface tension–temperature relation * recommended property values Subject RIV: BJ - Thermodynamics Impact factor: 2.726, year: 2016
Zamani, A.; Azargoshasb, T.; Niknam, E.
2017-10-01
Effects of applied magnetic field, temperature and dimensions on the optical absorption coefficients (AC) and refractive index (RI) changes of a GaAs quantum ring are investigated in the presence of both Rashba and Dresselhaus spin-orbit interactions (SOI). To this end, the finite difference method (FDM) is used in order to numerically calculate the energy eigenvalues and eigenstates of the system while the compact density matrix approach is hired to calculate the optical properties. It is shown that application of magnetic field, temperature as well as the geometrical size in the presence of spin-orbit interactions, alter the electronic structure and consequently influence the linear and third-order nonlinear optical absorption coefficients as well as the refractive index changes of the system. Results show an obvious blue shift in optical curves with enhancing external magnetic field and temperature while the increment of dimensions result in red shift.
Nakanishi, Koichi; Kogure, Akinori; Deuchi, Keiji; Kuwana, Ritsuko; Takamatsu, Hiromu; Ito, Kiyoshi
2015-01-01
We previously developed a method for evaluating the heat resistance of microorganisms by measuring the transition temperature at which the coefficient of linear expansion of a cell changes. Here, we performed heat resistance measurements using a scanning probe microscope with a nano thermal analysis system. The microorganisms studied included six strains of the genus Bacillus or related genera, one strain each of the thermophilic obligate anaerobic bacterial genera Thermoanaerobacter and Moorella, two strains of heat-resistant mold, two strains of non-sporulating bacteria, and one strain of yeast. Both vegetative cells and spores were evaluated. The transition temperature at which the coefficient of linear expansion due to heating changed from a positive value to a negative value correlated strongly with the heat resistance of the microorganism as estimated from the D value. The microorganisms with greater heat resistance exhibited higher transition temperatures. There was also a strong negative correlation between the coefficient of linear expansion and heat resistance in bacteria and yeast, such that microorganisms with greater heat resistance showed lower coefficients of linear expansion. These findings suggest that our method could be useful for evaluating the heat resistance of microorganisms.
Thermophysical Properties of Molten Silicon Measured by JPL High Temperature Electrostatic Levitator
Rhim, W. K.; Ohsaka, K.
1999-01-01
Five thermophysical properties of molten silicon measured by the High Temperature Electrostatic Levitator (HTESL) at JPL are presented. The properties measured are the density, the constant pressure specific heat capacity, the hemispherical total emissivity, the surface tension and the viscosity.
Bondarenko, G. G.; Dubinina, M. S.; Fisher, M. R.; Kristya, V. I.
2018-04-01
For a hybrid model of the low-current discharge considering, along with direct ionization of the mixture components by electrons, the Penning ionization of mercury atoms by metastable argon atoms, the ionization coefficient in the argon-mercury mixture used in illuminating lamps is calculated. The analytical approximation formula describing the dependence of the ionization coefficient of the mixture on the reduced electric field strength and temperature is obtained for sufficiently wide ranges of their variations, and its accuracy is estimated. It is demonstrated that the discharge ignition voltage calculated using this formula is in agreement with the results of simulation and the available experimental data.
Wu, Tzi-Yi; Chen, Bor-Kuan; Hao, Lin; Peng, Yu-Chun; Sun, I-Wen
2011-01-01
A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol) (PEG) [Mw = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ρ, refractive index, n, viscosity, η, and surface tension, γ, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values. PMID:21731460
Directory of Open Access Journals (Sweden)
Lin Hao
2011-04-01
Full Text Available A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol (PEG [Mw = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ρ, refractive index, n, viscosity, η, and surface tension, γ, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values.
International Nuclear Information System (INIS)
Taherkhani, Farid; Akbarzadeh, Hamed; Feyzi, Mostafa; Rafiee, Hamid Reza
2015-01-01
Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models
Energy Technology Data Exchange (ETDEWEB)
Taherkhani, Farid, E-mail: faridtaherkhani@gmail.com, E-mail: f.taherkhani@razi.ac.ir [Razi University, Department of Physical Chemistry (Iran, Islamic Republic of); Akbarzadeh, Hamed [Hakim Sabzevari University, Department of Chemistry (Iran, Islamic Republic of); Feyzi, Mostafa; Rafiee, Hamid Reza [Razi University, Department of Physical Chemistry (Iran, Islamic Republic of)
2015-01-15
Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models.
International Nuclear Information System (INIS)
Ahmed, N.; Khan, G.
1990-09-01
In this report the author used of a very useful technique of simulation and applied it to successfully for determining the various properties of sodium, both in liquid and solid phase near transition point. As a first step the determination of specific heat and diffusion coefficient have been carried out. In liquid state the molecular dynamics (MD) values calculated matched the experimental data. But in solid state the diffusion coefficient obtained were not consistent with the one expected for a solid, rather the values obtained suggested that sodium remained in liquid state even below the melting point. (A.B.)
Energy Technology Data Exchange (ETDEWEB)
Su, Jun [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); College of Mechanics Engineering, Nanjing Institute of Industry Technology, Nanjing, 210023 (China); Zhang, Jun, E-mail: zhangjun@njtech.edu.cn [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China)
2016-12-01
Graphical abstract: - Highlights: • The non-polar and short vinyl groups can greatly reduce G′ of HDPE composites. • Long chains on BaTiO{sub 3} surface enhance the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups on BaTiO{sub 3} surface raise the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups can boost the dielectric constant of HDPE composites. • The potential use in electronic equipment of the KH550 composites is obtained. - Abstract: In this work, three types of coupling agents: isopropyl trioleic titanate (NDZ105), vinyltriethoxysilane (SG-Si151), 3-aminopropyltriethoxysilane (KH550) were applied to modify the surface tension of Barium titanate (BaTiO{sub 3}) particles. The Fourier transform infrared (FT-IR) spectra confirm the chemical adherence of coupling agents to the particle surface. The long hydrocarbon chains in NDZ105 can cover the particle surface and reduce the polar surface tension of BaTiO{sub 3} from 37.53 mJ/m{sup 2} to 7.51 mJ/m{sup 2}, turning it from hydrophilic to oleophilic properties. The short and non-polar vinyl groups in SG-Si151 does not influence the surface tension of BaTiO{sub 3}, but make BaTiO{sub 3} have both hydrophilic and oleophilic properties. The polar amino in KH550 can keep BaTiO{sub 3} still with hydrophilic properties. It is found that SG-Si151 modified BaTiO{sub 3} has the lowest interaction with HDPE matrix, lowering the storage modulus of HDPE composites to the greatest extent. As for mechanical properties, the polar amino groups in KH550 on BaTiO{sub 3} surface can improve the adhesion of BaTiO{sub 3} with HDPE matrix, which increases the elongation at break of HDPE composites to the greatest extent. In terms of electrical properties, the polar amino groups on surface of BaTiO{sub 3} can boost the dielectric properties of HDPE/BaTiO{sub 3} composites and decrease the volume resistivity of HDPE/BaTiO{sub 3} composites. The aim of this study is to investigate how functional groups
Hayashi, Nobuhiko; Terauchi, Masaharu; Aya, Youichirou; Kanayama, Shutetsu; Nishitani, Hikaru; Nakagawa, Tohru; Takase, Michihiko
2017-09-01
We are developing a thin and lightweight CPV module using small size lens system made from poly methyl methacrylate (PMMA) with a short focal length and micro-solar cells to decrease the transporting and the installing costs of CPV systems. In order to achieve high conversion efficiency in CPV modules using micro-solar cells, the micro-solar cells need to be mounted accurately to the irradiated region of the concentrated sunlight. In this study, we have successfully developed self-align method thanks to the surface tension of the melted solder even utilizing commercially available surface-mounting technology (SMT). Solar cells were self-aligned to the specified positions of the circuit board by this self-align method with accuracy within ±10 µm. We actually fabricated CPV modules using this self-align method and demonstrated high conversion efficiency of our CPV module.
International Nuclear Information System (INIS)
Jamet, Didier; Torres, David; Brackbill, J.U.
2002-01-01
Errors in the computation of fluid flows with surface tension are examined. These errors cause large parasitic flows when the capillary number is large and have often been attributed to truncation error in underresolved interfacial regions. A study using the second-gradient method reveals that when truncation error is eliminated in the computation of energy exchanges between surface and kinetic energies so that energy is strictly conserved, the parasitic currents are reduced to round-off. The results are based on general thermodynamic arguments and can be used to guide improvements in other methods, such as the continuum-surface-force (CSF) method, which is commonly used with the volume-of-fluid (VOF) method
Rojewska, Monika; Biadasz, Andrzej; Kotkowiak, Michał; Olejnik, Anna; Rychlik, Joanna; Dudkowiak, Alina; Prochaska, Krystyna
2013-10-01
The adsorption properties of surfactant mixtures containing two types of quaternary derivatives of lysosomotropic substances: alkyl N,N-dimethylalaninates methobromides and alkyl N,N-dimethylglycinates methobromides were studied. Quantitative and qualitative description of the adsorption process was carried out on the basis of experimentally obtained equilibrium surface tension isotherms. The results indicated that most of the systems studied revealed synergistic effect both in adsorption and wetting properties. In vitro studies on human cancer cells were undertaken and the data obtained showed that the mixtures suppressed the cancer cells' proliferation more effectively than individual components. Results of preliminary research on the interaction of catanionic mixtures with phospholipids suggested a possibility of a strong penetration of cell membranes by the mixtures investigated. Copyright © 2013 Elsevier B.V. All rights reserved.
Jamet, D; Brackbill, J U
2002-01-01
Errors in the computation of fluid flows with surface tension are examined. These errors cause large parasitic flows when the capillary number is large and have often been attributed to truncation error in underresolved interfacial regions. A study using the second-gradient method reveals that when truncation error is eliminated in the computation of energy exchanges between surface and kinetic energies so that energy is strictly conserved, the parasitic currents are reduced to round-off. The results are based on general thermodynamic arguments and can be used to guide improvements in other methods, such as the continuum-surface-force (CSF) method, which is commonly used with the volume-of-fluid (VOF) method.
International Nuclear Information System (INIS)
Yan Hong; Wei Jiu-An; Cui Shu-Wen; Zhu Ru-Zeng
2013-01-01
The expressions of the radius and the surface tension of surface of tension R s and γ s in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature [Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out. (condensed matter: structural, mechanical, and thermal properties)
Lin, Bojie; Miao, Yong; Wang, Jin; Fan, Zhexiang; Du, Lijuan; Su, Yongsheng; Liu, Bingcheng; Hu, Zhiqi; Xing, Malcolm
2016-03-09
Human dermal papilla (DP) cells have been studied extensively when grown in the conventional monolayer. However, because of great deviation from the real in vivo three-dimensional (3D) environment, these two-dimensional (2D) grown cells tend to lose the hair-inducible capability during passaging. Hence, these 2D caused concerns have motivated the development of novel 3D culture techniques to produce cellular microtissues with suitable mimics. The hanging-drop approach is based on surface tension-based technique and the interaction between surface tension and gravity field that makes a convergence of liquid drops. This study used this technique in a converged drop to form cellular spheroids of dermal papilla cells. It leads to a controllable 3Dspheroid model for scalable fabrication of inductive DP microtissues. The optimal conditions for culturing high-passaged (P8) DP spheroids were determined first. Then, the morphological, histological and functional studies were performed. In addition, expressions of hair-inductive markers including alkaline phosphatase, α-smooth muscle actin and neural cell adhesion molecule were also analyzed by quantitative RT-PCR, immunostaining and immunoblotting. Finally, P8-DP microtissues were coimplanted with newborn mouse epidermal cells (EPCs) into nude mice. Our results indicated that the formation of 3D microtissues not only endowed P8-DP microtissues many similarities to primary DP, but also confer these microtissues an enhanced ability to induce hair-follicle (HF) neogenesis in vivo. This model provides a potential to elucidate the native biology of human DP, and also shows the promising for the controllable and scalable production of inductive DP cells applied in future follicle regeneration.