Reaction rate calculations via transmission coefficients
Feit, M.D.; Alder, B.J.
1985-01-01
The transmission coefficient of a wavepacket traversing a potential barrier can be determined by steady state calculations carried out in imaginary time instead of by real time dynamical calculations. The general argument is verified for the Eckart barrier potential by a comparison of transmission coefficients calculated from real and imaginary time solutions of the Schroedinger equation. The correspondence demonstrated here allows a formulation for the reaction rate that avoids difficulties due to both rare events and explicitly time dependent calculations. 5 refs., 2 figs
Efficient calculation of atomic rate coefficients in dense plasmas
Aslanyan, Valentin; Tallents, Greg J.
2017-03-01
Modelling electron statistics in a cold, dense plasma by the Fermi-Dirac distribution leads to complications in the calculations of atomic rate coefficients. The Pauli exclusion principle slows down the rate of collisions as electrons must find unoccupied quantum states and adds a further computational cost. Methods to calculate these coefficients by direct numerical integration with a high degree of parallelism are presented. This degree of optimization allows the effects of degeneracy to be incorporated into a time-dependent collisional-radiative model. Example results from such a model are presented.
Riahi, R.; Ben Lakhdar, Z.; Teulet, Ph.; Gleizes, A.
2006-01-01
The weighted total cross-sections (WTCS) theory is used to calculate electron impact excitation, ionization and dissociation cross-sections and rate coefficients of OH, H 2 , OH + , H 2 + , OH - and H 2 - diatomic molecules in the temperature range 1500-15000 K. Calculations are performed for H 2 (X, B, C), OH(X, A, B), H 2 + (X), OH + (X, a, A, b, c), H 2 - (X) and OH - (X) electronic states for which Dunham coefficients are available. Rate coefficients are calculated from WTCS assuming Maxwellian energy distribution functions for electrons and heavy particles. One and 2 temperatures (θ e and θ g respectively for electron and heavy particles kinetic temperatures) results are presented and fitting parameters (a, b and c) are given for each reaction rate coefficient: k(θ) a(θ b )exp(-c/θ). (authors)
Homayoon, Zahra; Jambrina, Pablo G.; Aoiz, F. Javier; Bowman, Joel M.
2012-07-01
In a previous paper [P. G. Jambrina et al., J. Chem. Phys. 135, 034310 (2011), 10.1063/1.3611400] various calculations of the rate coefficient for the Mu + H2 → MuH + H reaction were presented and compared to experiment. The widely used standard quasiclassical trajectory (QCT) method was shown to overestimate the rate coefficients by several orders of magnitude over the temperature range 200-1000 K. This was attributed to a major failure of that method to describe the correct threshold for the reaction owing to the large difference in zero-point energies (ZPE) of the reactant H2 and product MuH (˜0.32 eV). In this Communication we show that by performing standard QCT calculations for the reverse reaction and then applying detailed balance, the resulting rate coefficient is in very good agreement with the other computational results that respect the ZPE, (as well as with the experiment) but which are more demanding computationally.
Stiller, W.
1985-01-01
A classical collision theory is used to describe thermal bimolecular rate coefficeints for reaction between positive and negative ions and polar molecules in a carrier gas. Special attention is paid to ion-molecule reaction in which proton transfer occurs. These reactions play an important role in terrestrial plasma devices, in ionosphere, in planetary atmospheres and in interstellar matter. The equilibrium rate coefficients of the reactions are calculated based on a microscopic reactive cross section derived from a long distance polar molecule-ion potential. The results are compared with experimental values of afterglow measurements. (D.Gy.)
Kokoouline, V.; Richardson, W.
2014-01-01
Uncertainties in theoretical calculations may include: • Systematic uncertainty: Due to applicability limits of the chosen model. • Random: Within a model, uncertainties of model parameters result in uncertainties of final results (such as cross sections). • If uncertainties of experimental and theoretical data are known, for the purpose of data evaluation (to produce recommended data), one should combine two data sets to produce the best guess data with the smallest possible uncertainty. In many situations, it is possible to assess the accuracy of theoretical calculations because theoretical models usually rely on parameters that are uncertain, but not completely random, i.e. the uncertainties of the parameters of the models are approximately known. If there are one or several such parameters with corresponding uncertainties, even if some or all parameters are correlated, the above approach gives a conceptually simple way to calculate uncertainties of final cross sections (uncertainty propagation). Numerically, the statistical approach to the uncertainty propagation could be computationally expensive. However, in situations, where uncertainties are considered to be as important as the actual cross sections (for data validation or benchmark calculations, for example), such a numerical effort is justified. Having data from different sources (say, from theory and experiment), a systematic statistical approach allows one to compare the data and produce “unbiased” evaluated data with improved uncertainties, if uncertainties of initial data from different sources are available. Without uncertainties, the data evaluation/validation becomes impossible. This is the reason why theoreticians should assess the accuracy of their calculations in one way or another. A statistical and systematic approach, similar to the described above, is preferable.
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
Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M
2017-09-07
A theoretical study, involving the calculation of reaction enthalpies, activation energies, mechanisms, and rate coefficients, was made of the reaction of hydroxyl radicals with methyl nitrate, an important process for methyl nitrate removal in the earth's atmosphere. Four reaction channels were considered: formation of H 2 O + CH 2 ONO 2 , CH 3 OOH + NO 2 , CH 3 OH + NO 3 , and CH 3 O + HNO 3 . For all channels, geometry optimization and frequency calculations were performed at the M06-2X/6-31+G** level, while relative energies were improved at the UCCSD(T*)-F12/CBS level. The major channel is found to be the H abstraction channel, to give the products H 2 O + CH 2 ONO 2 . The reaction enthalpy (ΔH 298 K RX ) of this channel is computed as -17.90 kcal mol -1 . Although the other reaction channels are also exothermic, their reaction barriers are high (>24 kcal mol -1 ), and therefore these reactions do not contribute to the overall rate coefficient in the temperature range considered (200-400 K). Pathways via three transition states were identified for the H abstraction channel. Rate coefficients were calculated for these pathways at various levels of variational transition state theory including tunneling. The results obtained are used to distinguish between two sets of experimental rate coefficients, measured in the temperature range of 200-400 K, one of which is approximately an order of magnitude greater than the other. This comparison, as well as the temperature dependence of the computed rate coefficients, shows that the lower experimental values are favored. The implications of the results to atmospheric chemistry are discussed.
Anomaly coefficients: Their calculation and congruences
Braden, H.W.
1988-01-01
A new method for the calculation of anomaly coefficients is presented. For su(n) some explicit and general expressions are given for these. In particular, certain congruences are discovered and investigated among the leading anomaly coefficients. As an application of these congruences, the absence of global six-dimensional gauge anomalies is shown
Honvault, P; Scribano, Y
2013-10-03
The dynamics of the D(+) + H2 → HD + H(+) reaction on a recent ab initio potential energy surface (Velilla, L.; Lepetit, B.; Aguado, A.; Beswick, J. A.; Paniagua, M. J. Chem. Phys. 2008, 129, 084307) has been investigated by means of a time-independent quantum mechanical approach. Cross-sections and rate coefficients are calculated, respectively, for collision energies below 0.1 eV and temperatures up to 100 K for astrophysical application. An excellent accord is found for collision energy above 5 meV, while a disagreement between theory and experiment is observed below this energy. We show that the rate coefficients reveal a slightly temperature-dependent behavior in the upper part of the temperature range considered here. This is in agreement with the experimental data above 80 K, which give a temperature independent value. However, a significant decrease is found at temperatures below 20 K. This decrease can be related to quantum effects and the decay back to the reactant channel, which are not considered by simple statistical approaches, such as the Langevin model. Our results have been fitted to appropriate analytical expressions in order to be used in astrochemical and cosmological models.
Atomic rate coefficients in a degenerate plasma
Aslanyan, Valentin; Tallents, Greg
2015-11-01
The electrons in a dense, degenerate plasma follow Fermi-Dirac statistics, which deviate significantly in this regime from the usual Maxwell-Boltzmann approach used by many models. We present methods to calculate the atomic rate coefficients for the Fermi-Dirac distribution and present a comparison of the ionization fraction of carbon calculated using both models. We have found that for densities close to solid, although the discrepancy is small for LTE conditions, there is a large divergence from the ionization fraction by using classical rate coefficients in the presence of strong photoionizing radiation. We have found that using these modified rates and the degenerate heat capacity may affect the time evolution of a plasma subject to extreme ultraviolet and x-ray radiation such as produced in free electron laser irradiation of solid targets.
Graphical comparison of calculated internal conversion coefficients
Ewbank, W.B.
1980-11-01
Calculated values of the coefficients of internal conversion of gamma rays in the K shell and L 1 , L 2 , L 3 subshells from published tabulations by Band and Trzhaskovskaya and by Roesel et al. at Data Nucl. Data Tables, 21, 92-514(1978) are compared with values obtained by computer interpolation among tabulated values of Hager and Seltzer Nucl. Data, A4, 1-235(1968). In some cases, agreement among the three calculations is remarkably good, and differences are generally less than 5%. In a few cases, there are differences as large as 20 to 50%, corresponding to the threshold effect described by Roesel et al. The Z-dependent resonance minimum described by Roesel et al. is also observed in the comparison of E1-E4 conversion in the L 1 subshell. In several cases (notably M1-M4 conversion in the K shell and L 1 subshell), the Band and Roesel calculations show dramatically different dependence on gamma energy and atomic number. For Z = 100, the Band calculation for E4 conversion in the L 3 subshell shows irregular behavior at energies below the K-shell binding energy. A few high-quality measurements of internal conversion coefficients (+-5%) would help greatly to establish a basis for choice among the theoretical calculations. 32 figures
Diffusion coefficient calculations for cylindrical cells
Lam-Hime, M.
1983-03-01
An accurate and general diffusion coefficient calculation for cylindrical cells is described using isotropic scattering integral transport theory. This method has been particularly applied to large regular lattices of graphite-moderated reactors with annular coolant channels. The cells are divided into homogeneous zones, and a zone-wise flux expansion is used to formulate a collision probability problem. The reflection of neutrons at the cell boundary is accounted for by the conservation of the neutron momentum. The uncorrected diffusion coefficient Benoist's definition is used, and the described formulation does not neglect any effect. Angular correlation terms, energy coupling non-uniformity and anisotropy of the classical flux are exactly taken into account. Results for gas-graphite typical cells are given showing the importance of these approximations
The rating reliability calculator
Solomon David J
2004-04-01
Full Text Available Abstract Background Rating scales form an important means of gathering evaluation data. Since important decisions are often based on these evaluations, determining the reliability of rating data can be critical. Most commonly used methods of estimating reliability require a complete set of ratings i.e. every subject being rated must be rated by each judge. Over fifty years ago Ebel described an algorithm for estimating the reliability of ratings based on incomplete data. While his article has been widely cited over the years, software based on the algorithm is not readily available. This paper describes an easy-to-use Web-based utility for estimating the reliability of ratings based on incomplete data using Ebel's algorithm. Methods The program is available public use on our server and the source code is freely available under GNU General Public License. The utility is written in PHP, a common open source imbedded scripting language. The rating data can be entered in a convenient format on the user's personal computer that the program will upload to the server for calculating the reliability and other statistics describing the ratings. Results When the program is run it displays the reliability, number of subject rated, harmonic mean number of judges rating each subject, the mean and standard deviation of the averaged ratings per subject. The program also displays the mean, standard deviation and number of ratings for each subject rated. Additionally the program will estimate the reliability of an average of a number of ratings for each subject via the Spearman-Brown prophecy formula. Conclusion This simple web-based program provides a convenient means of estimating the reliability of rating data without the need to conduct special studies in order to provide complete rating data. I would welcome other researchers revising and enhancing the program.
Starck, Patricia L; Love, Karen; McPherson, Robert
2008-01-01
In recent years, the focus has been on increasing the number of registered nurse (RN) graduates. Numerous states have initiated programs to increase the number and quality of students entering nursing programs, and to expand the capacity of their programs to enroll additional qualified students. However, little attention has been focused on an equally, if not more, effective method for increasing the number of RNs produced-increasing the graduation rate of students enrolling. This article describes a project that undertook the task of compiling graduation data for 15 entry-level programs, standardizing terms and calculations for compiling the data, and producing a regional report on graduation rates of RN students overall and by type of program. Methodology is outlined in this article. This effort produced results that were surprising to program deans and directors and is expected to produce greater collaborative efforts to improve these rates both locally and statewide.
Compilation report of VHTRC temperature coefficient benchmark calculations
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.).
Analytical scheme calculations of angular momentum coupling and recoupling coefficients
Deveikis, A.; Kuznecovas, A.
2007-03-01
We investigate the Scheme programming language opportunities to analytically calculate the Clebsch-Gordan coefficients, Wigner 6j and 9j symbols, and general recoupling coefficients that are used in the quantum theory of angular momentum. The considered coefficients are calculated by a direct evaluation of the sum formulas. The calculation results for large values of quantum angular momenta were compared with analogous calculations with FORTRAN and Java programming languages.
Analytical scheme calculations of angular momentum coupling and recoupling coefficients
Deveikis, A.; Kuznecovas, A.
2007-01-01
We investigate the Scheme programming language opportunities to analytically calculate the Clebsch-Gordan coefficients, Wigner 6j and 9j symbols, and general recoupling coefficients that are used in the quantum theory of angular momentum. The considered coefficients are calculated by a direct evaluation of the sum formulas. The calculation results for large values of quantum angular momenta were compared with analogous calculations with FORTRAN and Java programming languages
Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M
2013-03-15
The minimum energy path (MEP) of the reaction, CF(3)CHFCF(3) + H → transition state (TS) → CF(3)CFCF(3) + H(2), has been computed at different ab initio levels and with density functional theory (DFT) using different functionals. The computed B3LYP/6-31++G**, BH&HLYP/cc-pVDZ, BMK/6-31++G**, M05/6-31+G**, M05-2X/6-31+G**, UMP2/6-31++G**, PUMP2/6-31++G**//UMP2/6-31++G**, RCCSD(T)/aug-cc-pVDZ//UMP2/6-31++G**, RCCSD(T)/aug-cc-pVTZ(spd,sp)//UMP2//6-31++G**, RCCSD(T)/CBS//M05/6-31+G**, and RCCSD(T)/CBS//UMP2/6-31++G** MEPs, and associated gradients and Hessians, were used in reaction rate coefficient calculations based on the transition state theory (TST). Reaction rate coefficients were computed between 300 and 1500 K at various levels of TST, which include conventional TST, canonical variational TST (CVT) and improved CVT (ICVT), and with different tunneling corrections, namely, Wigner, zero-curvature, and small-curvature (SCT). The computed rate coefficients obtained at different ab initio, DFT and TST levels are compared with experimental values available in the 1000-1200 K temperature range. Based on the rate coefficients computed at the ICVT/SCT level, the highest TST level used in this study, the BH&HLYP functional performs best among all the functionals used, while the RCCSD(T)/CBS//MP2/6-31++G** level is the best among all the ab initio levels used. Comparing computed reaction rate coefficients obtained at different levels of theory shows that, the computed barrier height has the strongest effect on the computed reaction rate coefficients as expected. Variational effects on the computed rate coefficients are found to be negligibly small. Although tunneling effects are relatively small at high temperatures (~1500 K), SCT corrections are significant at low temperatures (~300 K), and both barrier heights and the magnitudes of the imaginary frequencies affect SCT corrections. Copyright © 2012 Wiley Periodicals, Inc.
Calculation of transport coefficients in an axisymmetric plasma
Shumaker, D.E.
1977-01-01
A method of calculating the transport coefficient in an axisymmetric toroidal plasma is presented. This method is useful in calculating the transport coefficients in a Tokamak plasma confinement device. The particle density and temperature are shown to be a constant on a magnetic flux surface. Transport equations are given for the total particle flux and total energy flux crossing a closed toroidal surface. Also transport equations are given for the toroidal magnetic flux. A computer code was written to calculate the transport coefficients for a three species plasma, electrons and two species of ions. This is useful for calculating the transport coefficients of a plasma which contains impurities. It was found that the particle and energy transport coefficients are increased by a large amount, and the transport coefficients for the toroidal magnetic field are reduced by a small amount
Rate coefficient for the reaction N + NO
Fox, J. L.
1994-01-01
Evidence has been advanced that the rate coefficient for the reaction N + NO right arrow N2 + O has a small positive temperature dependence at the high temperatures (900 to 1500 K) that prevail in the terrestrial middle and upper thermosphere by Siskind and Rusch (1992), and at the low temperatures (100 to 200 K) of the Martian lower thermosphere by Fox (1993). Assuming that the rate coefficient recommended by the Jet Propulsion Laboratory evaluation (DeMore et al., 1992) is accurate at 300 K, we derive here the low temperature value of the activation energy for this reaction and thus the rate coefficient that best fits the Viking 1 measured NO densities. We find that the fit is acceptable for a rate coefficient of about 1.3 x 10(exp -10)(T/300)(exp 0.5)exp(-400/T) and better for a value of about 2.5 x 10(exp -10)(T/300)(exp 0.5)exp(-600/T)cu cm/s.
Calculation of transport coefficients in an axisymmetric plasma
Shumaker, D.E.
1976-01-01
A method of calculating the transport coefficient in an axisymmetric toroidal plasma is presented. This method is useful in calculating the transport coefficients in a Tokamak plasma confinement device. The particle density and temperature are shown to be a constant on a magnetic flux surface. Transport equations are given for the total particle flux and total energy flux crossing a closed toroidal surface. Also transport equations are given for the toroidal magnetic flux. A computer code was written to calculate the transport coefficients for a three species plasma, electrons and two species of ions. This is useful for calculating the transport coefficients of a plasma which contains impurities. It was found that the particle and energy transport coefficients are increased by a large amount, and the transport coefficients for the toroidal magnetic field are reduced by a small amount. For example, a deuterium plasma with 1.3 percent oxygen, one of the particle transport coefficients is increased by a factor of about four. The transport coefficients for the toroidal magnetic flux are reduced by about 20 percent. The increase in the particle transport coefficient is due to the collisional scattering of the deuterons by the heavy oxygen ions which is larger than the deuteron electron scattering, the normal process for particle transport in a two species plasma. The reduction in the toroidal magnetic flux transport coefficients are left unexplained
Extensions to the coupling coefficient calculations for muon telescopes
Baker, C P; Humble, J E [Tasmania Univ., Sandy Bay (Australia). Dept. of Physics; Duldig, M L [Dept. of the Arts, Sport, the Environment, Tourism and Territories, Hobart (Australia). Antarctic Div.
1989-01-01
The calculation of coupling coefficients for muon telescopes has previously used interpolation from a limited set of asymptotic directions of arrival of primary particles. Furthermore, these calculations have not incorporated curvature of the atmosphere and thus diverge from the true response at zenith angles greater than about 75 degrees. The necessary extensions to calculate coupling coefficients at arbitrary zenith angles are given, including an improved method of incorporating the asymptotic directions of the primary particles. It is shown, using this method, that certain coupling coefficients are highly sensitive to small changes in asymptotic directions for some telescope configurations. 10 refs., 1 fig., 3 tabs.
Extensions to the coupling coefficient calculations for muon telescopes
Baker, C.P.; Humble, J.E.; Duldig, M.L.
1989-01-01
The calculation of coupling coefficients for muon telescopes has previously used interpolation from a limited set of asymptotic directions of arrival of primary particles. Furthermore, these calculations have not incorporated curvature of the atmosphere and thus diverge from the true response at zenith angles greater than about 75 degrees. The necessary extensions to calculate coupling coefficients at arbitrary zenith angles are given, including an improved method of incorporating the asymptotic directions of the primary particles. It is shown, using this method, that certain coupling coefficients are highly sensitive to small changes in asymptotic directions for some telescope configurations. 10 refs., 1 fig., 3 tabs
Effective dose rate coefficients for exposure to contaminated soil
Veinot, K.G. [Easterly Scientific, Knoxville, TN (United States); Y-12 National Security Complex, Oak Ridge, TN (United States); Eckerman, K.F.; Easterly, C.E. [Easterly Scientific, Knoxville, TN (United States); Bellamy, M.B.; Hiller, M.M.; Dewji, S.A. [Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Oak Ridge, TN (United States); Hertel, N.E. [Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Oak Ridge, TN (United States); Georgia Institute of Technology, Atlanta, GA (United States); Manger, R. [University of California San Diego, Department of Radiation Medicine and Applied Sciences, La Jolla, CA (United States)
2017-08-15
The Oak Ridge National Laboratory Center for Radiation Protection Knowledge has undertaken calculations related to various environmental exposure scenarios. A previous paper reported the results for submersion in radioactive air and immersion in water using age-specific mathematical phantoms. This paper presents age-specific effective dose rate coefficients derived using stylized mathematical phantoms for exposure to contaminated soils. Dose rate coefficients for photon, electron, and positrons of discrete energies were calculated and folded with emissions of 1252 radionuclides addressed in ICRP Publication 107 to determine equivalent and effective dose rate coefficients. The MCNP6 radiation transport code was used for organ dose rate calculations for photons and the contribution of electrons to skin dose rate was derived using point-kernels. Bremsstrahlung and annihilation photons of positron emission were evaluated as discrete photons. The coefficients calculated in this work compare favorably to those reported in the US Federal Guidance Report 12 as well as by other authors who employed voxel phantoms for similar exposure scenarios. (orig.)
Mass: Fortran program for calculating mass-absorption coefficients
Nielsen, Aa.; Svane Petersen, T.
1980-01-01
Determinations of mass-absorption coefficients in the x-ray analysis of trace elements are an important and time consuming part of the arithmetic calculation. In the course of time different metods have been used. The program MASS calculates the mass-absorption coefficients from a given major element analysis at the x-ray wavelengths normally used in trace element determinations and lists the chemical analysis and the mass-absorption coefficients. The program is coded in FORTRAN IV, and is operational on the IBM 370/165 computer, on the UNIVAC 1110 and on PDP 11/05. (author)
Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M
2015-03-21
The reaction between atomic chlorine (Cl) and methyl nitrate (CH3ONO2) is significant in the atmosphere, as Cl is a key oxidant, especially in the marine boundary layer, and alkyl nitrates are important nitrogen-containing organic compounds, which are temporary reservoirs of the reactive nitrogen oxides NO, NO2 and NO3 (NOx). Four reaction channels HCl + CH2ONO2, CH3OCl + NO2, CH3Cl + NO3 and CH3O + ClNO2 were considered. The major channel is found to be the H abstraction channel, to give the products HCl + CH2ONO2. For all channels, geometry optimization and frequency calculations were carried out at the M06-2X/6-31+G** level, while relative electronic energies were improved to the UCCSD(T*)-F12/CBS level. The reaction barrier (ΔE(‡)0K) and reaction enthalpy (ΔH(RX)298K) of the H abstraction channel were computed to be 0.61 and -2.30 kcal mol(-1), respectively, at the UCCSD(T*)-F12/CBS//M06-2X/6-31+G** level. Reaction barriers (ΔE(‡)0K) for the other channels are more positive and these pathways do not contribute to the overall reaction rate coefficient in the temperature range considered (200-400 K). Rate coefficients were calculated for the H-abstraction channel at various levels of variational transition state theory (VTST) including tunnelling. Recommended ICVT/SCT rate coefficients in the temperature range 200-400 K are presented for the first time for this reaction. The values obtained in the 200-300 K region are particularly important as they will be valuable for atmospheric modelling calculations involving reactions with methyl nitrate. The implications of the results to atmospheric chemistry are discussed. Also, the enthalpies of formation, ΔHf,298K, of CH3ONO2 and CH2ONO2 were computed to be -29.7 and 19.3 kcal mol(-1), respectively, at the UCCSD(T*)-F12/CBS level.
Calculation results and experimental testing of doppler feedback coefficients
Yang Shunhai
1989-01-01
The Doppler feedback coefficients are calculated by the interpolation and group collapsing method from multigroup self-shielding factors and infinite dilution cross sections rather than effective resonance integrals by using resonance data base. Since many updated sets of multigroup data are in existence to be selected, the calculation process can be simplified. The heterogeneous effects are taken into account by equivalence relation. The computer code of Doppler feedback coefficients is created on computer CYBER-825 and PDP-11. The results calculated are in good agreement with the experiments
ROVIBRATIONAL QUENCHING RATE COEFFICIENTS OF HD IN COLLISIONS WITH He
Nolte, J. L.; Stancil, P. C.; Lee, T.-G.; Balakrishnan, N.; Forrey, R. C.
2012-01-01
Along with H 2 , HD has been found to play an important role in the cooling of the primordial gas for the formation of the first stars and galaxies. It has also been observed in a variety of cool molecular astrophysical environments. The rate of cooling by HD molecules requires knowledge of collisional rate coefficients with the primary impactors, H, He, and H 2 . To improve knowledge of the collisional properties of HD, we present rate coefficients for the He-HD collision system over a range of collision energies from 10 –5 to 5 × 10 3 cm –1 . Fully quantum mechanical scattering calculations were performed for initial HD rovibrational states of j = 0 and 1 for v = 0-17 which utilized accurate diatom rovibrational wave functions. Rate coefficients of all Δv = 0, –1, and –2 transitions are reported. Significant discrepancies with previous calculations, which adopted a small basis and harmonic HD wave functions for excited vibrational levels, were found for the highest previously considered vibrational state of v = 3. Applications of the He-HD rate coefficients in various astrophysical environments are briefly discussed.
Overview of models allowing calculation of activity coefficients
Jaussaud, C.; Sorel, C
2004-07-01
Activity coefficients must be estimated to accurately quantify the extraction equilibrium involved in spent fuel reprocessing. For these calculations, binary data are required for each electrolyte over a concentration range sometimes exceeding the maximum solubility. The activity coefficients must be extrapolated to model the behavior of binary supersaturated aqueous solution. According to the bibliography, the most suitable models are based on the local composition concept. (authors)
Towards a nonperturbative calculation of weak Hamiltonian Wilson coefficients
Bruno, Mattia; Lehner, Christoph; Soni, Amarjit; Rbc; Ukqcd Collaborations
2018-04-01
We propose a method to compute the Wilson coefficients of the weak effective Hamiltonian to all orders in the strong coupling constant using Lattice QCD simulations. We perform our calculations adopting an unphysically light weak boson mass of around 2 GeV. We demonstrate that systematic errors for the Wilson coefficients C1 and C2 , related to the current-current four-quark operators, can be controlled and present a path towards precise determinations in subsequent works.
Void coefficient of reactivity calculation for AP-600 core
Suparlina, L.; Budiono, T.A.; Mardha, A.; Tukiran
1998-01-01
Void coefficient of reactivity as one of reactor kinetics parameters has been carried out. The calculation was done into two steps which is cell calculation using WIMSD/4 and core calculation using Batan-2DIFF code programs with the condition of beginning of cycle with all fresh fuels elements and all control rods withdrawn. The one dimension transport program in four neutron energy groups is used to calculate the cell generation of various core materials cell has been calculated in 1/4 fuel element with cluster model and square pitch arrange. Moderator density have been reduced until 20% for the void coefficient of reactivity calculation. Macroscopic cross-section as the out put of WIMSD/4 is being used as the input at the diffusion neutron program for core calculation. The void coefficient of reactivity of the AP-600 core can be determined with regular neutron flux and adjoint in four energy groups and X-Y geometry. The results is shown that the K eff calculation value is different 5.2% from the design data
Dielectronic recombination rate coefficients of initially rubidium-like tungsten
Wu, Z.; Zhang, Y.; Fu, Y.; Dong, C.; Surzhykov, A.; Fritzsche, S.
2015-01-01
Dielectric recombination (DR) is a dominant electron recombination process in plasmas. Tungsten ions are expected to be prominent impurities in fusion plasmas so the knowledge of DR rate coefficient of tungsten ions is important to model fusion plasmas. Ab initio calculations of DR rate coefficients of initially rubidium-like W 37+ ions have been performed for the electron temperatures from 1 eV to 5*10 4 eV, by using the Flexible Atomic Code based on the relativistic configuration-interaction method. Special attention has been paid to the partial contributions to total DR rate coefficients as associated with the excitation of individual subshells. A detailed comparison of the calculations shows that the excitation from 4p subshell dominates total DR rate coefficients followed by the excitations from 4s and 4d subshells, while the contribution of excitations from 3l (l = s, p, d) subshells becomes important only at high temperatures. Besides, it is found that the electron excitations associated with Δn = 0, 1 dominate at low-temperature plasmas, however, the excitations associated with Δn ≥ 2 become non-negligible at high-temperature ones
Asua, J.M.; Beuermann, S.; Buback, M.; Castignolles, P.; Charleux, B.; Gilbert, R.G.; Hutchinson, R.A.; Leiza, J.R.; Nikitin, A.N.; Vairon, J.P.; Herk, van A.M.
2004-01-01
Propagation rate coefficients, kp, for free-radical polymerization of butyl acrylate (BA) previously reported by several groups are critically evaluated. All data were determined by the combination of pulsed-laser polymerization (PLP) and subsequent polymer analysis by size exclusion (SEC)
OLIFE: Tight Binding Code for Transmission Coefficient Calculation
Mijbil, Zainelabideen Yousif
2018-05-01
A new and human friendly transport calculation code has been developed. It requires a simple tight binding Hamiltonian as the only input file and uses a convenient graphical user interface to control calculations. The effect of magnetic field on junction has also been included. Furthermore the transmission coefficient can be calculated between any two points on the scatterer which ensures high flexibility to check the system. Therefore Olife can highly be recommended as an essential tool for pretesting studying and teaching electron transport in molecular devices that saves a lot of time and effort.
Calculation of self-diffusion coefficients in iron
Baohua Zhang
2014-01-01
Full Text Available On the basis of available P-V-T equation of state of iron, the temperature and pressure dependence of self-diffusion coefficients in iron polymorphs (α, δ, γ and ɛ phases have been successfully reproduced in terms of the bulk elastic and expansivity data by means of a thermodynamical model that interconnects point defects parameters with bulk properties. The calculated diffusion parameters, such as self-diffusion coefficient, activation energy and activation volume over a broad temperature range (500-2500 K and pressure range (0-100 GPa, compare favorably well with experimental or theoretical ones when the uncertainties are considered.
Calculation of generalized secant integral using binomial coefficients
Guseinov, I.I.; Mamedov, B.A.
2004-01-01
A single series expansion relation is derived for the generalized secant (GS) integral in terms of binomial coefficients, exponential integrals and incomplete gamma functions. The convergence of the series is tested by the concrete cases of parameters. The formulas given in this study for the evaluation of GS integral show good rate of convergence and numerical stability
The HD+ dissociative recombination rate coefficient at low temperature
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.
Jaffe, Richard; Schwenke, David; Chaban, Galina; Panesi, Marco
2014-01-01
Development of High-Fidelity Physics-Based Models to describe hypersonic flight through the atmospheres of Earth and Mars is underway at NASA Ames Research Center. The goal is to construct chemistry models of the collisional and radiative processes that occur in the bow shock and boundary layers of spacecraft during atmospheric entry that are free of empiricism. In this talk I will discuss our philosophy and describe some of our progress. Topics to be covered include thermochemistry, internal energy relaxation, collisional dissociation and radiative emission and absorption. For this work we start by solving the Schrodinger equation to obtain accurate interaction potentials and radiative properties. Then we invoke classical mechanics to compute state-specific heavy particle collision cross sections and reaction rate coefficients. Finally, phenomenological rate coefficients and relaxation times are determined from master equation solutions.
Nuclear data for the calculation of thermal reactor reactivity coefficients
1989-01-01
On its 15th meeting in Vienna, 16-20 June 1986, the International Nuclear Data Committee (INDC) considered it important to review the accuracy with which changes in thermal reactor reactivity resulting from changes in temperature and coolant density can be predicted. It was noted that reactor physicists in several countries had to adjust the thermal neutron cross-section data base in order to reproduce measured reactivity coefficients. Consequently, it appeared to be essential to examine the consistency of the integral and differential cross-section data and to make all the information available which has a bearing on reactivity coefficient prediction. Following the recommendation of the INDC, the Nuclear Data Section of the International Atomic Energy Agency, therefore, convened the Advisory Group Meeting on Nuclear Data for the Calculation of Thermal Reaction Reactivity Coefficients, in Vienna, Austria, 7-10 Dec. 1987. The Conclusions and Recommendations of the meeting together with the papers presented, are submitted in the present document. A separate abstract was prepared for each of these 12 papers. Refs, figs and tabs
Dielectronic recombination rate coefficients to the excited states of CI from CII
Dubau, J.; Kato, T.; Safronova, U.I.
1998-01-01
The dielectronic recombination rate coefficients to the excited states for n=2-6 are calculated including 1s 2 2l 1 2l 2 2l 3 nl (n=2-6, l≤(n-1)) states. The values for the excited states higher than n=6 are extrapolated and the total dielectronic recombination rate coefficients are derived. The rate coefficients to the excited states are fitted to an analytical formula and the fit parameters are given. (author)
Coefficients Calculation in Pascal Approximation for Passive Filter Design
George B. Kasapoglu
2018-02-01
Full Text Available The recently modified Pascal function is further exploited in this paper in the design of passive analog filters. The Pascal approximation has non-equiripple magnitude, in contrast of the most well-known approximations, such as the Chebyshev approximation. A novelty of this work is the introduction of a precise method that calculates the coefficients of the Pascal function. Two examples are presented for the passive design to illustrate the advantages and the disadvantages of the Pascal approximation. Moreover, the values of the passive elements can be taken from tables, which are created to define the normalized values of these elements for the Pascal approximation, as Zverev had done for the Chebyshev, Elliptic, and other approximations. Although Pascal approximation can be implemented to both passive and active filter designs, a passive filter design is addressed in this paper, and the benefits and shortcomings of Pascal approximation are presented and discussed.
Collisional excitation rate coefficients for lithium-like ions
Cochrane, D.M.; McWhirter, R.W.P.
1982-11-01
This report takes all the available good quality quantal calculations of excitation cross-sections by electron collision for lithium-like ions and intercompares them. There is a comparison also with the small amount of experimental data of 2s 2 S - 2p 2 P cross-sections. On the basis of all of these data, a choice is made of the best cross-sections and these are integrated over Maxwellians to give excitation rate coefficients. In general data are available for up to seven transitions in five or six ions. When the results are compared along the iso-electronic sequence, trends are established which allow estimates to be made of the rate coefficients for these seven transitions for any lithium-like ion of nuclear charge greater than boron. The results are presented graphically and as simple formulae. The formulae reproduce the source data at various levels of accuracy from about +-1% for individual ions to universal formulae of accuracy better than +-15% in the relevant temperature ranges. (author)
An online application for the barometric coefficient calculation of NMDB stations
Paschalis, P; Mavromichalaki, H; Gerontidou, M; Koutroumpi, I; Yanke, V; Belov, A; Eroshenko, E
2013-01-01
One of the most important data corrections related to the primary data processing of the neutron monitors is the pressure correction due to the barometric effect. This effect induces considerable variation in the counting rate of a cosmic ray detector which is not related to the real variation of the cosmic rays flux but only to the local atmospheric pressure of the station. In order to provide the worldwide neutron monitor network with good quality data, a correction has to be made that requires the calculation of the barometric coefficient. A new method that effectively calculates the barometric coefficient for a station using data of a reference station in order to subtract the primary variations of cosmic rays is presented in this work. Moreover, this method is the prototype of an online tool that uses data of the NMDB stations and calculates the barometric coefficient for any available station. This tool is also presented.
Papadimitriou, Vassileios C; Lazarou, Yannis G; Talukdar, Ranajit K; Burkholder, James B
2011-01-20
Rate coefficients, k, for the gas-phase reactions of Cl atoms and NO(3) radicals with 2,3,3,3-tetrafluoropropene, CF(3)CF═CH(2) (HFO-1234yf), and 1,2,3,3,3-pentafluoropropene, (Z)-CF(3)CF═CHF (HFO-1225ye), are reported. Cl-atom rate coefficients were measured in the fall-off region as a function of temperature (220-380 K) and pressure (50-630 Torr; N(2), O(2), and synthetic air) using a relative rate method. The measured rate coefficients are well represented by the fall-off parameters k(0)(T) = 6.5 × 10(-28) (T/300)(-6.9) cm(6) molecule(-2) s(-1) and k(∞)(T) = 7.7 × 10(-11) (T/300)(-0.65) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and k(0)(T) = 3 × 10(-27) (T/300)(-6.5) cm(6) molecule(-2) s(-1) and k(∞)(T) = 4.15 × 10(-11) (T/300)(-0.5) cm(3) molecule(-1) s(-1) for (Z)-CF(3)C═CHF with F(c) = 0.6. Reaction product yields were measured in the presence of O(2) to be (98 ± 7)% for CF(3)C(O)F and (61 ± 4)% for HC(O)Cl in the CF(3)CF═CH(2) reaction and (108 ± 8)% for CF(3)C(O)F and (112 ± 8)% for HC(O)F in the (Z)-CF(3)CF═CHF reaction, where the quoted uncertainties are 2σ (95% confidence level) and include estimated systematic errors. NO(3) reaction rate coefficients were determined using absolute and relative rate methods. Absolute measurements yielded upper limits for both reactions between 233 and 353 K, while the relative rate measurements yielded k(3)(295 K) = (2.6 ± 0.25) × 10(-17) cm(3) molecule(-1) s(-1) and k(4)(295 K) = (4.2 ± 0.5) × 10(-18) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF, respectively. The Cl-atom reaction with CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF leads to decreases in their atmospheric lifetimes and global warming potentials and formation of a chlorine-containing product, HC(O)Cl, for CF(3)CF═CH(2). The NO(3) reaction has been shown to have a negligible impact on the atmospheric lifetimes of CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF. The energetics for the reaction of Cl, NO(3), and OH with CF
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)
Calculation of Transport Coefficients in Dense Plasma Mixtures
Haxhimali, T.; Cabot, W. H.; Caspersen, K. J.; Greenough, J.; Miller, P. L.; Rudd, R. E.; Schwegler, E. R.
2011-10-01
We use classical molecular dynamics (MD) to estimate species diffusivity and viscosity in mixed dense plasmas. The Yukawa potential is used to describe the screened Coulomb interaction between the ions. This potential has been used widely, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We calculate transport coefficients in equilibrium simulations using the Green- Kubo relation over a range of thermodynamic conditions including the viscosity and the self - diffusivity for each component of the mixture. The interdiffusivity (or mutual diffusivity) can then be related to the self-diffusivities by using a generalization of the Darken equation. We have also employed non-equilibrium MD to estimate interdiffusivity during the broadening of the interface between two regions each with a high concentration of either species. Here we present results for an asymmetric mixture between Ar and H. These can easily be extended to other plasma mixtures. A main motivation for this study is to develop accurate transport models that can be incorporated into the hydrodynamic codes to study hydrodynamic instabilities. We use classical molecular dynamics (MD) to estimate species diffusivity and viscosity in mixed dense plasmas. The Yukawa potential is used to describe the screened Coulomb interaction between the ions. This potential has been used widely, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We calculate transport coefficients in equilibrium simulations using the Green- Kubo relation over a range of thermodynamic conditions including the viscosity and the self - diffusivity for each component of the mixture. The interdiffusivity (or mutual diffusivity) can then be related to the self-diffusivities by using a generalization of the Darken equation. We have also employed non-equilibrium MD to estimate interdiffusivity during
Dielectronic recombination rate coefficients to the excited states of CII from CIII
Kato, Takako; Safronova, U.; Ohira, Mituhiko.
1996-02-01
Energy levels, radiative transition probabilities and autoionization rates for CII including 1s 2 2l2l'nl'' (n=2-6, l'≤(n-1)) states were calculated by using multi-configurational Hartree-Fock (Cowan code) method. Autoionizing levels above three thresholds: 1s 2 2s 2 ( 1 S), 1s 2 2s2p( 3 P), 1s 2 2s2p( 1 P) were considered. Branching ratios related to the first threshold and the intensity factor were calculated for satellite lines of CII ion. The dielectronic recombination rate coefficients to the excited states for n=2-6 are calculated with these atomic data. The rate coefficients are fitted to an analytical formula and the fit parameters are given. The values for higher excited states than n=6 are extrapolated and the total dielectronic recombination rate coefficients are derived. The effective recombination rate coefficient for different electron densities are also derived. (author)
The Calculation of Fe-Al-O Interaction Coefficient
Kuo, Chin-Guo
2010-01-01
Aluminum is a very common deoxidizer in steel-making processes. The solubility of oxygen in molten iron decreases with increasing aluminum content. For the deoxidation process, the solubility of oxygen in Fe-Al melts decreases with increasing aluminum content. When %Al is increased to 0.34 wt.%, %O decreases to 6.4 ppm, which is the lowest point of the FeAl 2 O 4 curve. Then the Al 2 O 3 curve appears and replaces the FeAl 2 O 4 curve, where the interconnection point of the two curves is the coexistence point of FeAl 2 O 4 and Al 2 O 3 phases. When %Al is increased to 0.4%, the %O decreases to 6.35 ppm, which is the lowest point of the Al 2 O 3 curve. The solubility of oxygen in Fe-Al alloys is about 6.35 ppm with 0.4 wt.% aluminum at 1873 K. Liquid FeO-Al 2 O 3 , hercynite (FeAl 2 O 4 ), and alumina (Al 2 O 3 ) are three possible products during the deoxidation process. Based on thermodynamic calculation, the value of the interaction coefficient of e o Al was determined as -0.75 at 1873 K. This value is in good agreement with experimental curves in the literature.
Calculation of effective absorption coefficient for aerosols of internal mixture
Xu Bo; Huang Yinbo; Fan Chengyu; Qiao Chunhong
2012-01-01
The effective absorption coefficient with time of strong absorbing aerosol made of carbon dusts and water of internal mixture is analyzed, and the influence of different wavelengths and radius ratios on it is discussed. The shorter the wavelength is, the larger the effective absorption coefficient is , and more quickly it increases during 1-100 μs, and the largest increase if 132.65% during 1-100 μs. Different ratios between inner and outer radius have large influence on the effective absorption coefficient. The larger the ratio is, the larger the effective absorption coefficient is, and more quickly it increases during 1-100 μs. The increase of the effective absorption coefficient during 1-100 μs is larger than that during 100-1000 μs, and the largest increase is 138.66% during 1-100 μs. (authors)
The rate coefficients of unimolecular reactions in the systems with power-law distributions
Yin, Cangtao; Guo, Ran; Du, Jiulin
2014-08-01
The rate coefficient formulae of unimolecular reactions are generalized to the systems with the power-law distributions based on nonextensive statistics, and the power-law rate coefficients are derived in the high and low pressure limits, respectively. The numerical analyses are made of the rate coefficients as functions of the ν-parameter, the threshold energy, the temperature and the number of degrees of freedom. We show that the new rate coefficients depend strongly on the ν-parameter different from one (thus from a Boltzmann-Gibbs distribution). Two unimolecular reactions, CH3CO→CH3+CO and CH3NC→CH3CN, are taken as application examples to calculate their power-law rate coefficients, which obtained with the ν-parameters slightly different from one can be exactly in agreement with all the experimental studies on these two reactions in the given temperature ranges.
Simmer, Gregor
2012-01-01
Due to secondary cosmic radiation (SCR), pilots and flight attendants receive elevated effective doses at flight altitudes. For this reason, since 2003 aircrew members are considered as occupationally exposed, in Germany. This work deals with the calculation of dose conversion coefficients (DCC) for protons, neutrons, electrons, positrons, photons and myons, which are crucial for estimation of effective dose from SCR. For the first time, calculations were performed combining Geant4 - a Monte Carlo code developed at CERN - with the voxel phantoms for the reference female and male published in 2008 by ICRP and ICRU. Furthermore, measurements of neutron fluence spectra - which contribute the major part to the effective dose of SCR - were carried out at the Environmental Research Station Schneefernerhaus (UFS) located at 2650 m above sea level nearby the Zugspitze mountain, Germany. These measured neutron spectra, and additionally available calculated spectra, were then folded with the DCC calculated in this work, and effective dose rates for different heights were calculated.
Dielectronic recombination rate coefficients to the excited states of CI from CII
Dubau, J. [Observatoire of Paris, 92 MEUDON (France); Kato, T.; Safronova, U.I.
1998-01-01
The dielectronic recombination rate coefficients to the excited states for n=2-6 are calculated including 1s{sup 2}2l{sub 1}2l{sub 2}2l{sub 3}nl (n=2-6, l{<=}(n-1)) states. The values for the excited states higher than n=6 are extrapolated and the total dielectronic recombination rate coefficients are derived. The rate coefficients to the excited states are fitted to an analytical formula and the fit parameters are given. (author)
Rossi, Lubianka Ferrari Russo
2014-01-01
The main target of this study is to introduce a new method for calculating the coefficients of sensibility through the union of differential method and generalized perturbation theory, which are the two methods generally used in reactor physics to obtain such variables. These two methods, separated, have some issues turning the sensibility coefficients calculation slower or computationally exhaustive. However, putting them together, it is possible to repair these issues and build a new equation for the coefficient of sensibility. The method introduced in this study was applied in a PWR reactor, where it was performed the sensibility analysis for the production and 239 Pu conversion rate during 120 days (1 cycle) of burnup. The computational code used for both burnup and sensibility analysis, the CINEW, was developed in this study and all the results were compared with codes widely used in reactor physics, such as CINDER and SERPENT. The new mathematical method for calculating the sensibility coefficients and the code CINEW provide good numerical agility and also good efficiency and security, once the new method, when compared with traditional ones, provide satisfactory results, even when the other methods use different mathematical approaches. The burnup analysis, performed using the code CINEW, was compared with the code CINDER, showing an acceptable variation, though CINDER presents some computational issues due to the period it was built. The originality of this study is the application of such method in problems involving temporal dependence and, not least, the elaboration of the first national code for burnup and sensitivity analysis. (author)
Calculation of ternary interdiffusion coefficients using a single diffusion couple
Čermák, Jiří; Rothová, Věra
2016-01-01
Roč. 54, č. 5 (2016), s. 305-314 ISSN 0023-432X R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : diffusion * interdiffusion * ternary alloys * ternary diffusion coefficients Subject RIV: BJ - Thermodynamics Impact factor: 0.366, year: 2016
The Influence of Particle Charge on Heterogeneous Reaction Rate Coefficients
Aikin, A. C.; Pesnell, W. D.
2000-01-01
The effects of particle charge on heterogeneous reaction rates are presented. Many atmospheric particles, whether liquid or solid are charged. This surface charge causes a redistribution of charge within a liquid particle and as a consequence a perturbation in the gaseous uptake coefficient. The amount of perturbation is proportional to the external potential and the square of the ratio of debye length in the liquid to the particle radius. Previous modeling has shown how surface charge affects the uptake coefficient of charged aerosols. This effect is now included in the heterogeneous reaction rate of an aerosol ensemble. Extension of this analysis to ice particles will be discussed and examples presented.
Organ and effective dose rate coefficients for submersion exposure in occupational settings
Veinot, K.G.; Dewji, S.A.; Hiller, M.M.; Eckerman, K.F.; Easterly, C.E.
2017-01-01
External dose coefficients for environmental exposure scenarios are often computed using assumption on infinite or semi-infinite radiation sources. For example, in the case of a person standing on contaminated ground, the source is assumed to be distributed at a given depth (or between various depths) and extending outwards to an essentially infinite distance. In the case of exposure to contaminated air, the person is modeled as standing within a cloud of infinite, or semi-infinite, source distribution. However, these scenarios do not mimic common workplace environments where scatter off walls and ceilings may significantly alter the energy spectrum and dose coefficients. In this paper, dose rate coefficients were calculated using the International Commission on Radiological Protection (ICRP) reference voxel phantoms positioned in rooms of three sizes representing an office, laboratory, and warehouse. For each room size calculations using the reference phantoms were performed for photons, electrons, and positrons as the source particles to derive mono-energetic dose rate coefficients. Since the voxel phantoms lack the resolution to perform dose calculations at the sensitive depth for the skin, a mathematical phantom was developed and calculations were performed in each room size with the three source particle types. Coefficients for the noble gas radionuclides of ICRP Publication 107 (e.g., Ne, Ar, Kr, Xe, and Rn) were generated by folding the corresponding photon, electron, and positron emissions over the mono-energetic dose rate coefficients. Results indicate that the smaller room sizes have a significant impact on the dose rate per unit air concentration compared to the semi-infinite cloud case. For example, for Kr-85 the warehouse dose rate coefficient is 7% higher than the office dose rate coefficient while it is 71% higher for Xe-133. (orig.)
Organ and effective dose rate coefficients for submersion exposure in occupational settings
Veinot, K.G. [Easterly Scientific, Knoxville, TN (United States); Y-12 National Security Complex, Oak Ridge, TN (United States); Dewji, S.A.; Hiller, M.M. [Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Eckerman, K.F.; Easterly, C.E. [Easterly Scientific, Knoxville, TN (United States)
2017-11-15
External dose coefficients for environmental exposure scenarios are often computed using assumption on infinite or semi-infinite radiation sources. For example, in the case of a person standing on contaminated ground, the source is assumed to be distributed at a given depth (or between various depths) and extending outwards to an essentially infinite distance. In the case of exposure to contaminated air, the person is modeled as standing within a cloud of infinite, or semi-infinite, source distribution. However, these scenarios do not mimic common workplace environments where scatter off walls and ceilings may significantly alter the energy spectrum and dose coefficients. In this paper, dose rate coefficients were calculated using the International Commission on Radiological Protection (ICRP) reference voxel phantoms positioned in rooms of three sizes representing an office, laboratory, and warehouse. For each room size calculations using the reference phantoms were performed for photons, electrons, and positrons as the source particles to derive mono-energetic dose rate coefficients. Since the voxel phantoms lack the resolution to perform dose calculations at the sensitive depth for the skin, a mathematical phantom was developed and calculations were performed in each room size with the three source particle types. Coefficients for the noble gas radionuclides of ICRP Publication 107 (e.g., Ne, Ar, Kr, Xe, and Rn) were generated by folding the corresponding photon, electron, and positron emissions over the mono-energetic dose rate coefficients. Results indicate that the smaller room sizes have a significant impact on the dose rate per unit air concentration compared to the semi-infinite cloud case. For example, for Kr-85 the warehouse dose rate coefficient is 7% higher than the office dose rate coefficient while it is 71% higher for Xe-133. (orig.)
Dielectronic recombination rate coefficients to excited states of Be-like oxygen
Murakami, Izumi; Safronova, Ulyana I.; Kato, Takako
2001-05-01
We have calculated energy levels, radiative transition probabilities, and autoionization rates for Be-like oxygen (O{sup 4+}) including ls{sup 2}2lnl' (n=2 - 8, l {<=} n - 1) and 1s{sup 2}3l'nl (n=3 - 6, l {<=} n - l) states by multi-configurational Hartree-Fock method (Cowan code) and perturbation theory Z-expansion method (MZ code). The state selective dielectronic recombination rate coefficients to excited states of Be-like O ions are obtained. Configuration mixing plays an important role for the principal quantum number n distribution of the dielectronic recombination rate coefficients for 2snl (n {<=} 5) levels at low electron temperature. The orbital angular momentum quantum number l distribution of the rate coefficients shows a peak at l = 4. The total dielectronic recombination rate coefficient is derived as a function of electron temperature. (author)
Determination of sedimentation rates and absorption coefficient of ...
DR. MIKE HORSFALL
particles have pores that can absorb radiation. Gamma rays have been used to study the absorption coefficients of cobalt(II) insoluble compounds (Essien and Ekpe, 1998), densities of marine sediments. (Gerland and Villinger, 1995) and soil particle-size distribution (Vaz et al., 1992). In this study, sedimentation rates of ...
Rate coefficients for hydrogen abstraction reaction of pinonaldehyde
The H abstraction reaction from the –CHO group was found to be the most dominant reaction channelamong all the possible reaction pathways and its corresponding rate coefficient at 300 K is kEckart's unsymmetrical= 3.86 ×10-10 cm3 molecule-1 s-1. Whereas the channel with immediate lower activation energy is the ...
Gast, R.C.
1981-08-01
A procedure for defining diffusion coefficients from Monte Carlo calculations that results in suitable ones for use in neutron diffusion theory calculations is not readily obtained. This study provides a survey of the methods used to define diffusion coefficients from deterministic calculations and provides a discussion as to why such traditional methods cannot be used in Monte Carlo. This study further provides the empirical procedure used for defining diffusion coefficients from the RCP01 Monte Carlo program
Benchmark calculations of thermal reaction rates. I - Quantal scattering theory
Chatfield, David C.; Truhlar, Donald G.; Schwenke, David W.
1991-01-01
The thermal rate coefficient for the prototype reaction H + H2 yields H2 + H with zero total angular momentum is calculated by summing, averaging, and numerically integrating state-to-state reaction probabilities calculated by time-independent quantum-mechanical scattering theory. The results are very carefully converged with respect to all numerical parameters in order to provide high-precision benchmark results for confirming the accuracy of new methods and testing their efficiency.
Borges, Antonio Andrade
1998-01-01
A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating theses coefficients, which are the differential and the generalized perturbation theory methods. The method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivatives of the integral parameter, Φ, with respect to σ are calculated using the perturbation method and the functional derivatives of this generic integral parameter with respect to σ and Φ are calculated using the differential method. (author)
Global transmission coefficients in Hauser-Feshbach calculations for astrophysics
Rauscher, T [Inst. fuer Physik, Univ. Basel, Basel (Switzerland)
1998-06-01
The current status of optical potentials employed in the prediction of thermonuclear reaction rates for astrophysics in the Hauser-Feshbach formalism is discussed. Special emphasis is put on {alpha}+nucleus potentials. Further experimental efforts are motivated. (orig.)
Tank Z-361 dose rate calculations
Richard, R.F.
1998-01-01
Neutron and gamma ray dose rates were calculated above and around the 6-inch riser of tank Z-361 located at the Plutonium Finishing Plant. Dose rates were also determined off of one side of the tank. The largest dose rate 0.029 mrem/h was a gamma ray dose and occurred 76.2 cm (30 in.) directly above the open riser. All other dose rates were negligible. The ANSI/ANS 1991 flux to dose conversion factor for neutrons and photons were used in this analysis. Dose rates are reported in units of mrem/h with the calculated uncertainty shown within the parentheses
The 95% confidence intervals of error rates and discriminant coefficients
Shuichi Shinmura
2015-02-01
Full Text Available Fisher proposed a linear discriminant function (Fisher’s LDF. From 1971, we analysed electrocardiogram (ECG data in order to develop the diagnostic logic between normal and abnormal symptoms by Fisher’s LDF and a quadratic discriminant function (QDF. Our four years research was inferior to the decision tree logic developed by the medical doctor. After this experience, we discriminated many data and found four problems of the discriminant analysis. A revised Optimal LDF by Integer Programming (Revised IP-OLDF based on the minimum number of misclassification (minimum NM criterion resolves three problems entirely [13, 18]. In this research, we discuss fourth problem of the discriminant analysis. There are no standard errors (SEs of the error rate and discriminant coefficient. We propose a k-fold crossvalidation method. This method offers a model selection technique and a 95% confidence intervals (C.I. of error rates and discriminant coefficients.
Fair and Reasonable Rate Calculation Data -
Department of Transportation — This dataset provides guidelines for calculating the fair and reasonable rates for U.S. flag vessels carrying preference cargoes subject to regulations contained at...
Calculation of noise attenuation coefficient for leaks in the system sodium-water
Yugaj, V.S.; Kozlov, F.A.; Sorokina, T.G.
1986-01-01
In this report the authors present the calculation results for sound attenuation coefficient on hydrogen bubbles in sodium and show a calculation method of attenuation coefficient for different temperatures of sodium in the 1-200 kHz range frequencies [fr
Devine, R.T.; Hsu, Hsiao-Hua
1994-01-01
The current basis for conversion coefficients for calibrating individual photon dosimeters in terms of dose equivalents is found in the series of papers by Grosswent. In his calculation the collision kerma inside the phantom is determined by calculation of the energy fluence at the point of interest and the use of the mass energy absorption coefficient. This approximates the local absorbed dose. Other Monte Carlo methods can be sued to provide calculations of the conversion coefficients. Rogers has calculated fluence-to-dose equivalent conversion factors with the Electron-Gamma Shower Version 3, EGS3, Monte Carlo program and produced results similar to Grosswent's calculations. This paper will report on calculations using the Integrated TIGER Series Version 3, ITS3, code to calculate the conversion coefficients in ICRU Tissue and in PMMA. A complete description of the input parameters to the program is given and comparison to previous results is included
Criticality coefficient calculation for a small PWR using Monte Carlo Transport Code
Trombetta, Debora M.; Su, Jian, E-mail: dtrombetta@nuclear.ufrj.br, E-mail: sujian@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Chirayath, Sunil S., E-mail: sunilsc@tamu.edu [Department of Nuclear Engineering and Nuclear Security Science and Policy Institute, Texas A and M University, TX (United States)
2015-07-01
Computational models of reactors are increasingly used to predict nuclear reactor physics parameters responsible for reactivity changes which could lead to accidents and losses. In this work, preliminary results for criticality coefficient calculation using the Monte Carlo transport code MCNPX were presented for a small PWR. The computational modeling developed consists of the core with fuel elements, radial reflectors, and control rods inside a pressure vessel. Three different geometries were simulated, a single fuel pin, a fuel assembly and the core, with the aim to compare the criticality coefficients among themselves.The criticality coefficients calculated were: Doppler Temperature Coefficient, Coolant Temperature Coefficient, Coolant Void Coefficient, Power Coefficient, and Control Rod Worth. The coefficient values calculated by the MCNP code were compared with literature results, showing good agreement with reference data, which validate the computational model developed and allow it to be used to perform more complex studies. Criticality Coefficient values for the three simulations done had little discrepancy for almost all coefficients investigated, the only exception was the Power Coefficient. Preliminary results presented show that simple modelling as a fuel assembly can describe changes at almost all the criticality coefficients, avoiding the need of a complex core simulation. (author)
Dielectronic and Trielectronic Recombination Rate Coefficients of Be-like Ar14+
Huang, Z. K.; Wen, W. Q.; Xu, X.; Mahmood, S.; Wang, S. X.; Wang, H. B.; Dou, L. J.; Khan, N.; Badnell, N. R.; Preval, S. P.; Schippers, S.; Xu, T. H.; Yang, Y.; Yao, K.; Xu, W. Q.; Chuai, X. Y.; Zhu, X. L.; Zhao, D. M.; Mao, L. J.; Ma, X. M.; Li, J.; Mao, R. S.; Yuan, Y. J.; Wu, B.; Sheng, L. N.; Yang, J. C.; Xu, H. S.; Zhu, L. F.; Ma, X.
2018-03-01
Electron–ion recombination of Be-like 40Ar14+ has been measured by employing the electron–ion merged-beams method at the cooler storage ring CSRm. The measured absolute recombination rate coefficients for collision energies from 0 to 60 eV are presented, covering all dielectronic recombination (DR) resonances associated with 2s 2 → 2s2p core transitions. In addition, strong trielectronic recombination (TR) resonances associated with 2s 2 → 2p 2 core transitions were observed. Both DR and TR processes lead to series of peaks in the measured recombination spectrum, which have been identified by the Rydberg formula. Theoretical calculations of recombination rate coefficients were performed using the state-of-the-art multi-configuration Breit–Pauli atomic structure code AUTOSTRUCTURE to compare with the experimental results. The plasma rate coefficients for DR+TR of Ar14+ were deduced from the measured electron–ion recombination rate coefficients in the temperature range from 103 to 107 K, and compared with calculated data from the literature. The experimentally derived plasma rate coefficients are 60% larger and 30% lower than the previously recommended atomic data for the temperature ranges of photoionized plasmas and collisionally ionized plasmas, respectively. However, good agreement was found between experimental results and the calculations by Gu and Colgan et al. The plasma rate coefficients deduced from experiment and calculated by the current AUTOSTRUCTURE code show agreement that is better than 30% from 104 to 107 K. The present results constitute a set of benchmark data for use in astrophysical modeling.
Dose rate calculations for a reconnaissance vehicle
Grindrod, L.; Mackey, J.; Salmon, M.; Smith, C.; Wall, S.
2005-01-01
A Chemical Nuclear Reconnaissance System (CNRS) has been developed by the British Ministry of Defence to make chemical and radiation measurements on contaminated terrain using appropriate sensors and recording equipment installed in a land rover. A research programme is under way to develop and validate a predictive capability to calculate the build-up of contamination on the vehicle, radiation detector performance and dose rates to the occupants of the vehicle. This paper describes the geometric model of the vehicle and the methodology used for calculations of detector response. Calculated dose rates obtained using the MCBEND Monte Carlo radiation transport computer code in adjoint mode are presented. These address the transient response of the detectors as the vehicle passes through a contaminated area. Calculated dose rates were found to agree with the measured data to be within the experimental uncertainties, thus giving confidence in the shielding model of the vehicle and its application to other scenarios. (authors)
Schwenke, David W.; Jaffe, Richard L.; Chaban, Galina M.
2016-01-01
We have generated accurate global potential energy surfaces for CO+Ar and CO+O that correlate with atom-diatom pairs in their ground electronic states based on extensive ab initio electronic structure calculations and used these potentials in quasi-classical trajectory nuclear dynamics calculations to predict the thermal dissociation rate coefficients over 5000- 35000 K. Our results are not compatible with the 20-45 year old experimental results. For CO + Ar we obtain fairly good agreement with the experimental rate coefficients of Appleton et al. (1970) and Mick and Roth (1993), but our computed rate coefficients exhibit a stronger temperature dependence. For CO + O our dissociation rate coefficient is in close agreement with the value from the Park model, which is an empirical adjustment of older experimental results. However, we find the rate coefficient for CO + O is only 1.5 to 3.3 times larger than CO + Ar over the temperature range of the shock tube experiments (8000-15,000 K). The previously accepted value for this rate coefficient ratio is 15, independent of temperature. We also computed the rate coefficient for the CO + O ex- change reaction which forms C + O2. We find this reaction is much faster than previously believed and is the dominant process in the removal of CO at temperatures up to 16,000 K. As a result, the dissociation of CO is accomplished in two steps (react to form C+O2 and then O2 dissociates) that are endothermic by 6.1 and 5.1 eV, instead of one step that requires 11.2 eV to break the CO bond.
Rate Coefficients for the OH + (CHO)2 (Glyoxal) Reaction Between 240 and 400 K
Feierabend, K. J.; Talukdar, R. K.; Zhu, L.; Ravishankara, A. R.; Burkholder, J. B.
2006-12-01
Glyoxal (CHO)2, the simplest dialdehyde, is an end product formed in the atmospheric oxidation of biogenic hydrocarbons, for example, isoprene. As such, glyoxal plays a role in regional air quality and ozone production in certain locations. Glyoxal is lost in the atmosphere via UV photolysis and reaction with OH. However, the currently available rate coefficient data for the OH + glyoxal reaction is limited to a single room- temperature measurement made using the relative rate method. A determination of the rate coefficient temperature dependence is therefore needed for a more complete interpretation of the atmospheric processing of glyoxal. This study reports the rate coefficient for the OH + (CHO)2 reaction measured under pseudo- first-order conditions in OH ([(CHO)2] > 1000 [OH]0). OH radicals were produced using 248 nm pulsed laser photolysis of H2O2 or HNO3 and detected by pulsed laser induced fluorescence. The concentration of glyoxal in the reactor was determined using three independent techniques; gas flow rates as well as in situ UV and IR absorption. The total pressure in the reactor was varied from 40 to 300 Torr (He), and the rate coefficient was found to be independent of pressure over the temperature range studied. The rate coefficient exhibits a negative temperature dependence between 240 and 400 K consistent with the dependence previously observed for many other aldehydes. Our room-temperature rate coefficient is smaller than the relative rate value that is currently recommended for use in atmospheric model calculations. Our measured rate coefficients are discussed with respect to those for other aldehydes. The atmospheric implications of our work will also be discussed.
Reactivity Coefficient Calculation for AP1000 Reactor Using the NODAL3 Code
Pinem, Surian; Malem Sembiring, Tagor; Tukiran; Deswandri; Sunaryo, Geni Rina
2018-02-01
The reactivity coefficient is a very important parameter for inherent safety and stability of nuclear reactors operation. To provide the safety analysis of the reactor, the calculation of changes in reactivity caused by temperature is necessary because it is related to the reactor operation. In this paper, the temperature reactivity coefficients of fuel and moderator of the AP1000 core are calculated, as well as the moderator density and boron concentration. All of these coefficients are calculated at the hot full power condition (HFP). All neutron diffusion constant as a function of temperature, water density and boron concentration were generated by the SRAC2006 code. The core calculations for determination of the reactivity coefficient parameter are done by using NODAL3 code. The calculation results show that the fuel temperature, moderator temperature and boron reactivity coefficients are in the range between -2.613 pcm/°C to -4.657pcm/°C, -1.00518 pcm/°C to 1.00649 pcm/°C and -9.11361 pcm/ppm to -8.0751 pcm/ppm, respectively. For the water density reactivity coefficients, the positive reactivity occurs at the water temperature less than 190 °C. The calculation results show that the reactivity coefficients are accurate because the results have a very good agreement with the design value.
APUAMA: a software tool for reaction rate calculations.
Euclides, Henrique O; P Barreto, Patricia R
2017-06-01
APUAMA is a free software designed to determine the reaction rate and thermodynamic properties of chemical species of a reagent system. With data from electronic structure calculations, the APUAMA determine the rate constant with tunneling correction, such as Wigner, Eckart and small curvature, and also, include the rovibrational level of diatomic molecules. The results are presented in the form of Arrhenius-Kooij form, for the reaction rate, and the thermodynamic properties are written down in the polynomial form. The word APUAMA means "fast" in Tupi-Guarani Brazilian language, then the code calculates the reaction rate on a simple and intuitive graphic interface, the form fast and practical. As program output, there are several ASCII files with tabulated information for rate constant, rovibrational levels, energy barriers and enthalpy of reaction, Arrhenius-Kooij coefficient, and also, the option to the User save all graphics in BMP format.
Li Qing; Ren Xin; Zhang Kangda
2009-01-01
Using the finite element method, calculation and test are conducted on the bolted joints of four different diameters, and the existing calculation method for bolt compliance coefficient is analyzed. The results indicate that the calculated and test results by finite element method are agreed well, and value D/t f and β have a linear relation. (authors)
Automatic estimation of pressure-dependent rate coefficients.
Allen, Joshua W; Goldsmith, C Franklin; Green, William H
2012-01-21
A general framework is presented for accurately and efficiently estimating the phenomenological pressure-dependent rate coefficients for reaction networks of arbitrary size and complexity using only high-pressure-limit information. Two aspects of this framework are discussed in detail. First, two methods of estimating the density of states of the species in the network are presented, including a new method based on characteristic functional group frequencies. Second, three methods of simplifying the full master equation model of the network to a single set of phenomenological rates are discussed, including a new method based on the reservoir state and pseudo-steady state approximations. Both sets of methods are evaluated in the context of the chemically-activated reaction of acetyl with oxygen. All three simplifications of the master equation are usually accurate, but each fails in certain situations, which are discussed. The new methods usually provide good accuracy at a computational cost appropriate for automated reaction mechanism generation.
Accurate Determination of Tunneling-Affected Rate Coefficients: Theory Assessing Experiment.
Zuo, Junxiang; Xie, Changjian; Guo, Hua; Xie, Daiqian
2017-07-20
The thermal rate coefficients of a prototypical bimolecular reaction are determined on an accurate ab initio potential energy surface (PES) using ring polymer molecular dynamics (RPMD). It is shown that quantum effects such as tunneling and zero-point energy (ZPE) are of critical importance for the HCl + OH reaction at low temperatures, while the heavier deuterium substitution renders tunneling less facile in the DCl + OH reaction. The calculated RPMD rate coefficients are in excellent agreement with experimental data for the HCl + OH reaction in the entire temperature range of 200-1000 K, confirming the accuracy of the PES. On the other hand, the RPMD rate coefficients for the DCl + OH reaction agree with some, but not all, experimental values. The self-consistency of the theoretical results thus allows a quality assessment of the experimental data.
An Analytical-empirical Calculation of Linear Attenuation Coefficient of Megavoltage Photon Beams.
Seif, F; Tahmasebi-Birgani, M J; Bayatiani, M R
2017-09-01
In this study, a method for linear attenuation coefficient calculation was introduced. Linear attenuation coefficient was calculated with a new method that base on the physics of interaction of photon with matter, mathematical calculation and x-ray spectrum consideration. The calculation was done for Cerrobend as a common radiotherapy modifier and Mercury. The values of calculated linear attenuation coefficient with this new method are in acceptable range. Also, the linear attenuation coefficient decreases slightly as the thickness of attenuating filter (Cerrobend or mercury) increased, so the procedure of linear attenuation coefficient variation is in agreement with other documents. The results showed that the attenuation ability of mercury was about 1.44 times more than Cerrobend. The method that was introduced in this study for linear attenuation coefficient calculation is general enough to treat beam modifiers with any shape or material by using the same formalism; however, calculating was made only for mercury and Cerrobend attenuator. On the other hand, it seems that this method is suitable for high energy shields or protector designing.
Laporta, V. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari, Italy and Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Celiberto, R. [Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica, Politecnico di Bari, Italy and Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari (Italy); Tennyson, J. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)
2014-12-09
Rate coefficients for dissociative electron attachment and electron-impact dissociation processes, involving vibrationally excited molecular oxygen, are presented. Analytical fits of the calculated numerical data, useful in the applications, are also provided.
Santos, Adimir dos; Borges, A.A.
2000-01-01
A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating these coefficients, which are the differential and the generalized perturbation theory methods. The proposed method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivates of the integral parameter, φ(ξ), with respect to σ are calculated using the perturbation method and the functional derivates of this generic integral parameter with respect to σ and φ are calculated using the differential method. The new method merges the advantages of the differential and generalized perturbation theory methods and eliminates their disadvantages. (author)
Chapter 10: Calculation of the temperature coefficient of reactivity of a graphite-moderated reactor
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)
Thermodynamically based constraints for rate coefficients of large biochemical networks.
Vlad, Marcel O; Ross, John
2009-01-01
Wegscheider cyclicity conditions are relationships among the rate coefficients of a complex reaction network, which ensure the compatibility of kinetic equations with the conditions for thermodynamic equilibrium. The detailed balance at equilibrium, that is the equilibration of forward and backward rates for each elementary reaction, leads to compatibility between the conditions of kinetic and thermodynamic equilibrium. Therefore, Wegscheider cyclicity conditions can be derived by eliminating the equilibrium concentrations from the conditions of detailed balance. We develop matrix algebra tools needed to carry out this elimination, reexamine an old derivation of the general form of Wegscheider cyclicity condition, and develop new derivations which lead to more compact and easier-to-use formulas. We derive scaling laws for the nonequilibrium rates of a complex reaction network, which include Wegscheider conditions as a particular case. The scaling laws for the rates are used for clarifying the kinetic and thermodynamic meaning of Wegscheider cyclicity conditions. Finally, we discuss different ways of using Wegscheider cyclicity conditions for kinetic computations in systems biology.
Dielectronic recombination rate coefficients to the excited states of CIII from CIV
Safronova, U.; Kato, Takako; Ohira, Mituhiko
1996-07-01
Energy levels, radiative transition probabilities and autoionization rates for CIII including 1s{sup 2}2pnl` (n=2/6, l`{<=}(n-1)) and 1s{sup 2}3lnl` (n=3/6, l`{<=}(n-1)) states were calculated by using multi-configurational Hartree-Fock (Cowan code) method. Autoionizing levels above the 1s{sup 2}2s and 1s{sup 2}2p thresholds were considered and their contributions were computed. Branching ratios on the autoionization rate to the first threshold and intensity factor were calculated for satellite lines of CIII ion. The dielectronic recombination rate coefficients to the excited states for n=2-6 were calculated. The values for the excited states higher than n=6 were extrapolated and the total dielectronic recombination rate coefficients were also derived. The rate coefficients to the excited states were fitted to an analytical formula and the fitting parameters are given. (author)
Accurate reactivity void coefficient calculation for the fast spectrum reactor FBR-IME
Lima, Fabiano P.C.; Vellozo, Sergio de O.; Velozo, Marta J., E-mail: fabianopetruceli@outlook.com, E-mail: vellozo@cbpf.br, E-mail: martajann@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Militar
2017-07-01
This paper aims to present an accurate calculation of the void reactivity coefficient for the FBR-IME, a fast spectrum reactor in development at the Engineering Military Institute (IME). The main design peculiarity lies in using mixed oxide [MOX - PuO{sub 2} + U(natural uranium)O{sub 2}] as fuel core. For this task, SCALE system was used to calculate the reactivity for several voids distributions generated by bubbles in the sodium beyond its boiling point. The results show that although the void reactivity coefficient is positive and location dependent, they are offset by other feedback effects, resulting in a negative overall coefficient. (author)
FORTRAN program for calculating liquid-phase and gas-phase thermal diffusion column coefficients
Rutherford, W.M.
1980-01-01
A computer program (COLCO) was developed for calculating thermal diffusion column coefficients from theory. The program, which is written in FORTRAN IV, can be used for both liquid-phase and gas-phase thermal diffusion columns. Column coefficients for the gas phase can be based on gas properties calculated from kinetic theory using tables of omega integrals or on tables of compiled physical properties as functions of temperature. Column coefficients for the liquid phase can be based on compiled physical property tables. Program listings, test data, sample output, and users manual are supplied for appendices
Electron-impact excitation rate-coefficients and polarization of subsequent emission for Ar"+ ion
Dipti; Srivastava, Rajesh
2016-01-01
Electron impact excitation in Ar"+ ions has been studied by using fully relativistic distorted wave theory. Calculations are performed to obtain the excitation cross-sections and rate-coefficients for the transitions from the ground state 3p"5 (J=3/2) to fine-structure levels of excited states 3p"44s, 3p"44p, 3p"45s, 3p"45p, 3p"43d and 3p"44d. Polarization of the radiation following the excitation has been calculated using the obtained magnetic sub-level cross-sections. Comparison of the present rate-coefficients is also done with the previously reported theoretical results for some unresolved fine structure transitions. - Highlights: • Fully relativistic distorted wave theory has been used to study the excitation of fine-structure states of Ar"+. • We have calculated electron-impact excitation cross-sections for the wide range of incident electron energies. • Electron impact excitation rate-coefficients are calculated as a function of electron temperature. • Polarization of photons emitted following the decay of the excited fine-structure states are also reported.
Biased Brownian dynamics for rate constant calculation.
Zou, G; Skeel, R D; Subramaniam, S
2000-01-01
An enhanced sampling method-biased Brownian dynamics-is developed for the calculation of diffusion-limited biomolecular association reaction rates with high energy or entropy barriers. Biased Brownian dynamics introduces a biasing force in addition to the electrostatic force between the reactants, and it associates a probability weight with each trajectory. A simulation loses weight when movement is along the biasing force and gains weight when movement is against the biasing force. The sampl...
Monte Carlo calculation of the nuclear temperature coefficient in fast reactors
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)
Automatic estimation of pressure-dependent rate coefficients
Allen, Joshua W.; Goldsmith, C. Franklin; Green, William H.
2012-01-01
A general framework is presented for accurately and efficiently estimating the phenomenological pressure-dependent rate coefficients for reaction networks of arbitrary size and complexity using only high-pressure-limit information. Two aspects of this framework are discussed in detail. First, two methods of estimating the density of states of the species in the network are presented, including a new method based on characteristic functional group frequencies. Second, three methods of simplifying the full master equation model of the network to a single set of phenomenological rates are discussed, including a new method based on the reservoir state and pseudo-steady state approximations. Both sets of methods are evaluated in the context of the chemically-activated reaction of acetyl with oxygen. All three simplifications of the master equation are usually accurate, but each fails in certain situations, which are discussed. The new methods usually provide good accuracy at a computational cost appropriate for automated reaction mechanism generation. This journal is © the Owner Societies.
Heat Transfer Coefficient at Cast-Mold Interface During Centrifugal Casting: Calculation of Air Gap
Bohacek, Jan; Kharicha, Abdellah; Ludwig, Andreas; Wu, Menghuai; Karimi-Sibaki, Ebrahim
2018-06-01
During centrifugal casting, the thermal resistance at the cast-mold interface represents a main blockage mechanism for heat transfer. In addition to the refractory coating, an air gap begins to form due to the shrinkage of the casting and the mold expansion, under the continuous influence of strong centrifugal forces. Here, the heat transfer coefficient at the cast-mold interface h has been determined from calculations of the air gap thickness d a based on a plane stress model taking into account thermoelastic stresses, centrifugal forces, plastic deformations, and a temperature-dependent Young's modulus. The numerical approach proposed here is rather novel and tries to offer an alternative to the empirical formulas usually used in numerical simulations for a description of a time-dependent heat transfer coefficient h. Several numerical tests were performed for different coating thicknesses d C, rotation rates Ω, and temperatures of solidus T sol. Results demonstrated that the scenario at the interface is unique for each set of parameters, hindering the possibility of employing empirical formulas without a preceding experiment being performed. Initial values of h are simply equivalent to the ratio of the coating thermal conductivity and its thickness ( 1000 Wm-2 K-1). Later, when the air gap is formed, h drops exponentially to values at least one order of magnitude smaller ( 100 Wm-2 K-1).
Semiempirical method of determining flow coefficients for pitot rake mass flow rate measurements
Trefny, C. J.
1985-01-01
Flow coefficients applicable to area-weighted pitot rake mass flow rate measurements are presented for fully developed, turbulent flow in an annulus. A turbulent velocity profile is generated semiempirically for a given annulus hub-to-tip radius ratio and integrated numerically to determine the ideal mass flow rate. The calculated velocities at each probe location are then summed, and the flow rate as indicated by the rake is obtained. The flow coefficient to be used with the particular rake geometry is subsequently obtained by dividing the ideal flow rate by the rake-indicated flow rate. Flow coefficients ranged from 0.903 for one probe placed at a radius dividing two equal areas to 0.984 for a 10-probe area-weighted rake. Flow coefficients were not a strong function of annulus hub-to-tip radius ratio for rakes with three or more probes. The semiempirical method used to generate the turbulent velocity profiles is described in detail.
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
Microscopic calculation of friction coefficients for use in heavy-ion reaction
Iwamoto, A.; Harada, K.; Yoshida, S.
1981-01-01
A microscopic calculation has been done for the friction coefficient for use in the deep-inelastic collision of heavy nuclei. We adopted the formalism of the linear response theory as a basis and used the adiabatic base of the two-center shell model. Several reaction channels with the total mass numbers of 236 and 260 systems were investigated. The friction coefficients for the radial and deforming motions including the coupling term were calculated as a function of the distance between two nuclei and deformation of the two nuclei for each channel. The general feature of the friction coefficient, its strength and form factor, was clarified in this model and comparison with the results of other models were done. It was found that our model gives a physically plausible value for the friction coefficient as a whole. (orig.)
Nagy, Szilvia; Pipek, János
2015-12-21
In wavelet based electronic structure calculations, introducing a new, finer resolution level is usually an expensive task, this is why often a two-level approximation is used with very fine starting resolution level. This process results in large matrices to calculate with and a large number of coefficients to be stored. In our previous work we have developed an adaptively refined solution scheme that determines the indices, where the refined basis functions are to be included, and later a method for predicting the next, finer resolution coefficients in a very economic way. In the present contribution, we would like to determine whether the method can be applied for predicting not only the first, but also the other, higher resolution level coefficients. Also the energy expectation values of the predicted wave functions are studied, as well as the scaling behaviour of the coefficients in the fine resolution limit.
Koji Ogata
2018-02-01
Full Text Available The octanol–water partition coefficient (logPow is an important index for measuring solubility, membrane permeability, and bioavailability in the drug discovery field. In this paper, the logPow values of 58 compounds were predicted by alchemical free energy calculation using molecular dynamics simulation. In free energy calculations, the atomic charges of the compounds are always fixed. However, they must be recalculated for each solvent. Therefore, three different sets of atomic charges were tested using quantum chemical calculations, taking into account vacuum, octanol, and water environments. The calculated atomic charges in the different environments do not necessarily influence the correlation between calculated and experimentally measured ∆Gwater values. The largest correlation coefficient values of the solvation free energy in water and octanol were 0.93 and 0.90, respectively. On the other hand, the correlation coefficient of logPow values calculated from free energies, the largest of which was 0.92, was sensitive to the combination of the solvation free energies calculated from the calculated atomic charges. These results reveal that the solvent assumed in the atomic charge calculation is an important factor determining the accuracy of predicted logPow values.
Calculation of heat-kernel coefficients and usage of computer algebra
Bel'kov, A.A.; Lanev, A.V.; Schaale, A.
1995-01-01
The calculation of heat-kernel coefficients with the classical De Witt algorithm has been discussed. We present the explicit form of the coefficients up to h 5 in the general case and up to h 7 min for the minimal parts. The results are compared with the expressions in other papers. A method to optimize the usage of memory for working with large expressions on universal computer algebra systems has been proposed. 20 refs
Improved method for calculating neoclassical transport coefficients in the banana regime
Taguchi, M., E-mail: taguchi.masayoshi@nihon-u.ac.jp [College of Industrial Technology, Nihon University, Narashino 275-8576 (Japan)
2014-05-15
The conventional neoclassical moment method in the banana regime is improved by increasing the accuracy of approximation to the linearized Fokker-Planck collision operator. This improved method is formulated for a multiple ion plasma in general tokamak equilibria. The explicit computation in a model magnetic field shows that the neoclassical transport coefficients can be accurately calculated in the full range of aspect ratio by the improved method. The some neoclassical transport coefficients for the intermediate aspect ratio are found to appreciably deviate from those obtained by the conventional moment method. The differences between the transport coefficients with these two methods are up to about 20%.
Integral linear momentum balance in combining flows for calculating the pressure drop coefficients
Bollmann, A.
1983-01-01
Equations for calculating the loss coefficient in combining flows in tee functions are obtained by an integral linear momentum balance. It is a practice, when solving this type of problem, to neglect the pressure difference in the upstream location as well as the wall-fluid interaction in the lateral branch of the junction. In this work it is demonstrated the influence of the above parameters on the loss coefficient based on experimental values and by apropriate algebraic manipulation of the loss coefficient values published by previous investigators. (Author) [pt
Zankl, M.
2001-01-01
Calculations are essential for radiation protection practice because organ doses and effective doses cannot be measured directly. Conversion coefficients describe the numerical relationships of protection quantities and operational quantities. The latter can be measured in practical situations using suitable dosimeters. The conversion coefficients are calculated using radiation transport codes - usually based on Monte Carlo methods - that simulate the interactions of radiation with matter in computational models of the human body. A new generation of human body models, the so-called voxel models, are constructed from image data of real persons using suitable image processing systems, consequently, they represent the human anatomy more realistically than the so-called mathematical models. The numerical effects of realistic body anatomy on the calculated conversion coefficients can amount to 70% and more for external exposures. (orig.) [de
ppcor: An R Package for a Fast Calculation to Semi-partial Correlation Coefficients.
Kim, Seongho
2015-11-01
Lack of a general matrix formula hampers implementation of the semi-partial correlation, also known as part correlation, to the higher-order coefficient. This is because the higher-order semi-partial correlation calculation using a recursive formula requires an enormous number of recursive calculations to obtain the correlation coefficients. To resolve this difficulty, we derive a general matrix formula of the semi-partial correlation for fast computation. The semi-partial correlations are then implemented on an R package ppcor along with the partial correlation. Owing to the general matrix formulas, users can readily calculate the coefficients of both partial and semi-partial correlations without computational burden. The package ppcor further provides users with the level of the statistical significance with its test statistic.
Calculation of fuel and moderator temperature coefficients in APR1400 nuclear reactor by MVP code
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)
Calculating the heat transfer coefficient of frame profiles with internal cavities
Noyé, Peter Anders; Laustsen, Jacob Birck; Svendsen, Svend
2004-01-01
. The heat transfer coefficient is determined by two-dimensional numerical calculations and by measurements. Calculations are performed in Therm (LBNL (2001)), which is developed at Lawrence Berkeley National Laboratory, USA. The calculations are performed in accordance with the future European standards...... correspondence between measured and calculated values. Hence, when determining the heat transfer coefficient of frame profiles with internal cavities by calculations, it is necessary to apply a more detailed radiation exchange model than described in the prEN ISO 10077-2 standard. The ISO-standard offers......Determining the energy performance of windows requires detailed knowledge of the thermal properties of their different elements. A series of standards and guidelines exist in this area. The thermal properties of the frame can be determined either by detailed two-dimensional numerical methods...
Glass dissolution rate measurement and calculation revisited
Fournier, Maxime, E-mail: maxime.fournier@cea.fr [CEA, DEN, DTCD, SECM, F-30207, Bagnols sur Cèze (France); Ull, Aurélien; Nicoleau, Elodie [CEA, DEN, DTCD, SECM, F-30207, Bagnols sur Cèze (France); Inagaki, Yaohiro [Department of Applied Quantum Physics & Nuclear Engineering, Kyushu University, Fukuoka, 819-0395 (Japan); Odorico, Michaël [ICSM-UMR5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule, BP17171, F-30207, Bagnols sur Cèze (France); Frugier, Pierre; Gin, Stéphane [CEA, DEN, DTCD, SECM, F-30207, Bagnols sur Cèze (France)
2016-08-01
Aqueous dissolution rate measurements of nuclear glasses are a key step in the long-term behavior study of such waste forms. These rates are routinely normalized to the glass surface area in contact with solution, and experiments are very often carried out using crushed materials. Various methods have been implemented to determine the surface area of such glass powders, leading to differing values, with the notion of the reactive surface area of crushed glass remaining vague. In this study, around forty initial dissolution rate measurements were conducted following static and flow rate (SPFT, MCFT) measurement protocols at 90 °C, pH 10. The international reference glass (ISG), in the forms of powders with different particle sizes and polished monoliths, and soda-lime glass beads were examined. Although crushed glass grains clearly cannot be assimilated with spheres, it is when using the samples geometric surface (S{sub geo}) that the rates measured on powders are closest to those found for monoliths. Overestimation of the reactive surface when using the BET model (S{sub BET}) may be due to small physical features at the atomic scale—contributing to BET surface area but not to AFM surface area. Such features are very small compared with the thickness of water ingress in glass (a few hundred nanometers) and should not be considered in rate calculations. With a S{sub BET}/S{sub geo} ratio of 2.5 ± 0.2 for ISG powders, it is shown here that rates measured on powders and normalized to S{sub geo} should be divided by 1.3 and rates normalized to S{sub BET} should be multiplied by 1.9 in order to be compared with rates measured on a monolith. The use of glass beads indicates that the geometric surface gives a good estimation of glass reactive surface if sample geometry can be precisely described. Although data clearly shows the repeatability of measurements, results must be given with a high uncertainty of approximately ±25%. - Highlights: • Initial dissolution
Scientific periodical publications rating's calculation and analysis
B. E. Nikitin
2017-01-01
Full Text Available The article considers the constructing problem of the food industry journals aggregate ratings. The streamlines of the seventeen magazines on four bibliometric indexes (SCIENCE INDEX, five-year impact factor RISC given the translated version without self-citations, h-index over 10 years and Herfindahl index, which are used in the scientific electronic library elibrary.ru was used as initial data. The statement of the problem refers to multi-criteria decision-making problems. Ranking the journals in these indexes are different from each other because bibliometric indicators account different aspects of the journals. The classical approach to thisproblems solution is based on generalized criterion building in the form of an additive convolution. However, this approach requires adherence to a number of regular conditions that may not always be performed when the practical problems solution. The reductionspossibility of the considered formulation in the form of multi-criteria decision-making tasks to the problem of collective choice. The aggregated ratings of the reporting journals are calculated by using the three social choice rules – Board procedure, Copeland procedures and Kemeny median heuristic procedures. On the basis of Spearman's rank correlation determined the quantitative evaluation of the degree of intimacy built in magazines. In particular, calculated on the basis of procedure, Board and Kemeny median aggregate ratings reporting in the logs coincided. The results showed that the constructed ordering of journals on the basis of social choice rules are in good agreement with the scientific electronic library (eLIBRARY bibliometric indicators.
Calculating the Effect of External Shading on the Solar Heat Gain Coefficient of Windows
Kohler, Christian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shukla, Yash [CEPT Univ., Ahmedabad (India); Rawal, Rajan [CEPT Univ., Ahmedabad (India)
2017-08-09
Current prescriptive building codes have limited ways to account for the effect of solar shading, such as overhangs and awnings, on window solar heat gains. We propose two new indicators, the adjusted Solar Heat Gain Coefficient (aSHGC) which accounts for external shading while calculating the SHGC of a window, and a weighted SHGC (SHGCw) which provides a seasonal SHGC weighted by solar intensity. We demonstrate a method to calculate these indices using existing tools combined with additional calculations. The method is demonstrated by calculating the effect of an awning on a clear double glazing in New Delhi.
Shim S.M.
2012-01-01
Full Text Available The performance of the CO2 absorber column using mono-ethanolamine (MEA solution as chemical solvent are predicted by a One-Dimensional (1-D rate based model in the present study. 1-D Mass and heat balance equations of vapor and liquid phase are coupled with interfacial mass transfer model and vapor-liquid equilibrium model. The two-film theory is used to estimate the mass transfer between the vapor and liquid film. Chemical reactions in MEA-CO2-H2O system are considered to predict the equilibrium pressure of CO2 in the MEA solution. The mathematical and reaction kinetics models used in this work are calculated by using in-house code. The numerical results are validated in the comparison of simulation results with experimental and simulation data given in the literature. The performance of CO2 absorber column is evaluated by the 1-D rate based model using various reaction rate coefficients suggested by various researchers. When the rate of liquid to gas mass flow rate is about 8.3, 6.6, 4.5 and 3.1, the error of CO2 loading and the CO2 removal efficiency using the reaction rate coefficients of Aboudheir et al. is within about 4.9 % and 5.2 %, respectively. Therefore, the reaction rate coefficient suggested by Aboudheir et al. among the various reaction rate coefficients used in this study is appropriate to predict the performance of CO2 absorber column using MEA solution. [Acknowledgement. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF, funded by the Ministry of Education, Science and Technology (2011-0017220].
Daures, J.; Gouriou, J.; Bordy, J.M.
2010-01-01
The authors report calculations performed using the MNCP and PENELOPE codes to determine the Hp(3)/K air conversion coefficient which allows the Hp(3) dose equivalent to be determined from the measured value of the kerma in the air. They report the definition of the phantom, a 20 cm diameter and 20 cm high cylinder which is considered as representative of a head. Calculations are performed for an energy range corresponding to interventional radiology or cardiology (20 keV-110 keV). Results obtained with both codes are compared
Calculation of conversion coefficients for clinical photon spectra using the MCNP code.
Lima, M A F; Silva, A X; Crispim, V R
2004-01-01
In this work, the MCNP4B code has been employed to calculate conversion coefficients from air kerma to the ambient dose equivalent, H*(10)/Ka, for monoenergetic photon energies from 10 keV to 50 MeV, assuming the kerma approximation. Also estimated are the H*(10)/Ka for photon beams produced by linear accelerators, such as Clinac-4 and Clinac-2500, after transmission through primary barriers of radiotherapy treatment rooms. The results for the conversion coefficients for monoenergetic photon energies, with statistical uncertainty <2%, are compared with those in ICRP publication 74 and good agreements were obtained. The conversion coefficients calculated for real clinic spectra transmitted through walls of concrete of 1, 1.5 and 2 m thick, are in the range of 1.06-1.12 Sv Gy(-1).
Janev, R.K.; Kato, T.; Wang, J.G.
2001-05-01
The available experimental and theoretical cross section data on charge exchange processes in collisions of protons with hydrocarbon molecules have been collected and critically assessed. Using well established scaling relationships for the charge exchange cross sections at low and high collision energies, as well as the known rate coefficients for these reactions in the thermal energy region, a complete cross section database is constructed for proton-C x H y charge exchange reactions from thermal energies up to several hundreds keV for all C x H y molecules with x=1, 2, 3 and 1 ≤ y ≤ 2x + 2. Rate coefficients for these charge exchange reactions have also been calculated in the temperature range from 0.1 eV to 20 keV. (author)
Janev, R.K.; Kato, T. [National Inst. for Fusion Science, Toki, Gifu (Japan); Wang, J.G. [Department of Physics and Astronomy, University of Georgia, Athens (United States)
2001-05-01
The available experimental and theoretical cross section data on charge exchange processes in collisions of protons with hydrocarbon molecules have been collected and critically assessed. Using well established scaling relationships for the charge exchange cross sections at low and high collision energies, as well as the known rate coefficients for these reactions in the thermal energy region, a complete cross section database is constructed for proton-C{sub x}H{sub y} charge exchange reactions from thermal energies up to several hundreds keV for all C{sub x}H{sub y} molecules with x=1, 2, 3 and 1 {<=} y {<=} 2x + 2. Rate coefficients for these charge exchange reactions have also been calculated in the temperature range from 0.1 eV to 20 keV. (author)
Numerical calculation of wall-to-bed heat transfer coefficients in gas-fluidized beds
Kuipers, J.A.M.; Prins, W.; van Swaaij, W.P.M.
1992-01-01
A computer model for a hot gas-fluidized bed has been developed. The theoretical description is based on a two-fluid model (TFM) approach in which both phases are considered to be continuous and fully interpenetrating. Local wall-to-bed heat-transfer coefficients have been calculated by the
Sample Size Calculation for Estimating or Testing a Nonzero Squared Multiple Correlation Coefficient
Krishnamoorthy, K.; Xia, Yanping
2008-01-01
The problems of hypothesis testing and interval estimation of the squared multiple correlation coefficient of a multivariate normal distribution are considered. It is shown that available one-sided tests are uniformly most powerful, and the one-sided confidence intervals are uniformly most accurate. An exact method of calculating sample size to…
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.
Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4
Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R.
2014-01-01
Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H p (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm 3 , composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm 2 ). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)
Calculation of the mass transfer coefficient for the combustion of a carbon particle
Scala, Fabrizio [Istituto di Ricerche sulla Combustione - CNR, P.le Tecchio 80, 80125 Napoli (Italy)
2010-01-15
In this paper we address the calculation of the mass transfer coefficient around a burning carbon particle in an atmosphere of O{sub 2}, N{sub 2}, CO{sub 2}, CO, and H{sub 2}O. The complete set of Stefan-Maxwell equations is analytically solved under the assumption of no homogeneous reaction in the boundary layer. An expression linking the oxygen concentration and the oxygen flux at the particle surface (as a function of the bulk gas composition) is derived which can be used to calculate the mass transfer coefficient. A very simple approximate explicit expression is also given for the mass transfer coefficient, that is shown to be valid in the low oxygen flux limit or when the primary combustion product is CO{sub 2}. The results are given in terms of a correction factor to the equimolar counter-diffusion mass transfer coefficient, which is typically available in the literature for specific geometries and/or fluid-dynamic conditions. The significance of the correction factor and the accuracy of the different available expressions is illustrated for several cases of practical interest. Results show that under typical combustion conditions the use of the equimolar counter-diffusion mass transfer coefficient can lead to errors up to 10%. Larger errors are possible in oxygen-enriched conditions, while the error is generally low in oxy-combustion. (author)
Bley, Michael; Duvail, Magali; Guilbaud, Philippe; Dufrêche, Jean-François
2017-10-19
Herein, a new theoretical method is presented for predicting osmotic equilibria and activities, where a bulk liquid and its corresponding vapor phase are simulated by means of molecular dynamics using explicit polarization. Calculated time-averaged number density profiles provide the amount of evaporated molecules present in the vapor phase and consequently the vapor-phase density. The activity of the solvent and the corresponding osmotic coefficient are determined by the vapor density at different solute concentrations with respect to the reference vapor density of the pure solvent. With the extended Debye-Hückel equation for the activity coefficient along with the corresponding Gibbs-Duhem relation, the activity coefficients of the solutes are calculated by fitting the osmotic coefficients. A simple model based on the combination of Poisson processes and Maxwell-Boltzmann velocity distributions is introduced to interpret statistical phenomena observed during the simulations, which are related to evaporation and recondensation. This method is applied to aqueous dysprosium nitrate [Dy(NO 3 ) 3 ] solutions at different concentrations. The obtained densities of the liquid bulk and the osmotic and activity coefficients are in good agreement with the experimental results for concentrated and saturated solutions. Density profiles of the liquid-vapor interface at different concentrations provide detailed insight into the spatial distributions of all compounds.
Transmission Loss Calculation using A and B Loss Coefficients in Dynamic Economic Dispatch Problem
Jethmalani, C. H. Ram; Dumpa, Poornima; Simon, Sishaj P.; Sundareswaran, K.
2016-04-01
This paper analyzes the performance of A-loss coefficients while evaluating transmission losses in a Dynamic Economic Dispatch (DED) Problem. The performance analysis is carried out by comparing the losses computed using nominal A loss coefficients and nominal B loss coefficients in reference with load flow solution obtained by standard Newton-Raphson (NR) method. Density based clustering method based on connected regions with sufficiently high density (DBSCAN) is employed in identifying the best regions of A and B loss coefficients. Based on the results obtained through cluster analysis, a novel approach in improving the accuracy of network loss calculation is proposed. Here, based on the change in per unit load values between the load intervals, loss coefficients are updated for calculating the transmission losses. The proposed algorithm is tested and validated on IEEE 6 bus system, IEEE 14 bus, system IEEE 30 bus system and IEEE 118 bus system. All simulations are carried out using SCILAB 5.4 (www.scilab.org) which is an open source software.
Reduced Variance using ADVANTG in Monte Carlo Calculations of Dose Coefficients to Stylized Phantoms
Hiller, Mauritius; Bellamy, Michael; Eckerman, Keith; Hertel, Nolan
2017-09-01
The estimation of dose coefficients of external radiation sources to the organs in phantoms becomes increasingly difficult for lower photon source energies. This study focus on the estimation of photon emitters around the phantom. The computer time needed to calculate a result within a certain precision can be lowered by several orders of magnitude using ADVANTG compared to a standard run. Using ADVANTG which employs the DENOVO adjoint calculation package enables the user to create a fully populated set of weight windows and source biasing instructions for an MCNP calculation.
Solc, J.; Suran, J.; Novotna, M.; Pavlis, J.
2008-01-01
The contribution describes a technique of determination of calibration coefficients of a radioactivity monitor using Monte Carlo calculations. The monitor is installed at the NPP Temelin adjacent to lines with a radioactive medium. The output quantity is the activity concentration (in Bq/m3) that is converted from the number of counts per minute measured by the monitor. The value of this conversion constant, i.e. calibration coefficient, was calculated for gamma photons emitted by Co-60 and compared to the data stated by the manufacturer and supplier of these monitors, General Atomic Electronic Systems, Inc., USA. Results of the comparison show very good agreement between calculations and manufacturer data; the differences are lower than the quadratic sum of uncertainties. (authors)
Sato, Kaoru; Endo, Akira; Saito, Kimiaki
2008-10-01
This report presents a complete set of conversion coefficients of organ doses and effective doses calculated for external photon exposure using five Japanese adult voxel phantoms developed at the Japan Atomic Energy Agency (JAEA). At the JAEA, high-resolution Japanese voxel phantoms have been developed to clarify the variation of organ doses due to the anatomical characteristics of Japanese, and three male phantoms (JM, JM2 and Otoko) and two female phantoms (JF and Onago) have been constructed up to now. The conversion coefficients of organ doses and effective doses for the five voxel phantoms have been calculated for six kinds of idealized irradiation geometries from monoenergetic photons ranging from 0.01 to 10 MeV using EGS4, a Monte Carlo code for the simulation of coupled electron-photon transport. The dose conversion coefficients are given as absorbed dose and effective dose per unit air-kerma free-in-air, and are presented in tables and figures. The calculated dose conversion coefficients are compared with those of voxel phantoms based on the Caucasian and the recommended values in ICRP74 in order to discuss (1) variation of organ dose due to the body size and individual anatomy, such as position and shape of organs, and (2) effect of posture on organ doses. The present report provides valuable data to study the influence of the body characteristics of Japanese upon the organ doses and to discuss developing reference Japanese and Asian phantoms. (author)
Calculation of the dispersion-dipole coefficients for interactions between H, He, and H2
Bishop, D.M.; Pipin, J.
1993-01-01
Collisions between atoms and molecules create an induced dipole moment which, at long range separations, stems, in part, from the van der Waals interactions between the colliding species. This contribution is known as the dispersion dipole moment and is of the order R -7 , where R is the separation between particles. Although there have been several approximate calculations of the dispersion-dipole coefficients which govern this contribution, and are the counterparts to the van der Waals dispersion-energy coefficients, there have been few ab initio calculations. In this article we present highly accurate results, based on explicitly electron-correlated wave functions, for the dispersion-dipole coefficients pertaining to interactions between pairs chosen from H, He, and H 2 . We also obtain values with some of the currently used approximate formulas. A comparison shows that these values differ, in general, by a significant amount (∼20--∼40 %) from the accurate ones. We also tabulate values of the dipole--dipole-quadrupole polarizability tensor (B) for imaginary frequency (iω) for a range of frequencies appropriate to a 64-point Gauss--Legendre quadrature for H, He, and H 2 . These values were used in certain numerical integrations we made to verify our original results which had been obtained by analytic integration---they may, however, be useful in other contexts. For H--H 2 and H 2 --H 2 , these are the only ab initio calculations of the dispersion-dipole coefficients of which we are aware
Roteta, M; Baro, J; Fernandez-Varea, J M; Salvat, F
1994-07-01
The FORTRAN 77 code PHOTAC to compute photon attenuation coefficients of elements and compounds is described. The code is based on the semi analytical approximate atomic cross sections proposed by Baro et al. (1994). Photoelectric cross sections for coherent and incoherent scattering and for pair production are obtained as integrals of the corresponding differential cross sections. These integrals are evaluated, to a pre-selected accuracy, by using a 20-point Gauss adaptive integration algorithm. Calculated attenuation coefficients agree with recently compiled databases to within - 1%, in the energy range from 1 keV to 1 GeV. The complete source listing of the program PHOTAC is included. (Author) 14 refs.
Roteta, M.; Baro, J.; Fernandez-Varea, J. M.; Salvat, F.
1994-01-01
The FORTRAN 77 code PHOTAC to compute photon attenuation coefficients of elements and compounds is described. The code is based on the semi analytical approximate atomic cross sections proposed by Baro et al. (1994). Photoelectric cross sections for coherent and incoherent scattering and for pair production are obtained as integrals of the corresponding differential cross sections. These integrals are evaluated, to a pre-selected accuracy, by using a 20-point Gauss adaptive integration algorithm. Calculated attenuation coefficients agree with recently compiled databases to within - 1%, in the energy range from 1 keV to 1 GeV. The complete source listing of the program PHOTAC is included. (Author) 14 refs
Hung, Tran Van; Satoh, Daiki; Takahashi, Fumiaki; Tsuda, Shuichi; Endo, Akira; Saito, Kimiaki; Yamaguchi, Yasuhiro
2005-02-01
Age-dependent dose conversion coefficients for external exposure to photons emitted by radionuclides uniformly distributed in air were calculated. The size of the source region in the calculation was assumed to be effectively semi-infinite in extent. Firstly, organ doses were calculated with a series of age-specific MIRD-5 type phantoms using MCNP code, a Monte Carlo transport code. The calculations were performed for mono-energetic photon sources of twelve energies from 10 keV to 5 MeV and for phantoms of newborn, 1, 5, 10 and 15 years, and adult. Then, the effective doses to the different age-phantoms from the mono-energetic photon sources were estimated based on the obtained organ doses. The calculated effective doses were used to interpolate the conversion coefficients of the effective doses for 160 radionuclides, which are important for dose assessment of nuclear facilities. In the calculation, energies and intensities of emitted photons from radionuclides were taken from DECDC, a recent compilation of decay data for radiation dosimetry developed at JAERI. The results are tabulated in the form of effective dose per unit concentration and time (Sv per Bq s m -3 ). (author)
Recent developments in biokinetic models and the calculation of internal dose coefficients
Fell, T.P.; Phipps, A.W.; Kendall, G.M.; Stradling, G.N.
1997-01-01
In most cases the measurement of radioactivity in an environmental or biological sample will be followed by some estimation of dose and possibly risk, either to a population or an individual. This will normally involve the use of a dose coefficient (dose per unit intake value) taken from a compendium. In recent years the calculation of dose coefficients has seen many developments in both biokinetic modelling and computational capabilities. ICRP has recommended new models for the respiratory tract and for the systemic behavior of many of the more important elements. As well as this, a general age-dependent calculation method has been developed which involves an effectively continuous variation of both biokinetic and dosimetric parameters, facilitating more realistic estimation of doses to young people. These new developments were used in work for recent ICRP, IAEA and CEC compendia of dose coefficients for both members of the public (including children) and workers. This paper presents a general overview of the method of calculation of internal doses with particular reference to the actinides. Some of the implications for dose coefficients of the new models are discussed. For example it is shown that compared with data in ICRP Publications 30 and 54: the new respiratory tract model generally predicts lower deposition in systemic tissues per unit intake; the new biokinetic models for actinides allow for burial of material deposited on bone surfaces; age-dependent models generally feature faster turnover of material in young people. All of these factors can lead to substantially different estimates of dose and examples of the new dose coefficients are given to illustrate these differences. During the development of the new models for actinides, human bioassay data were used to validate the model. Thus, one would expect the new models to give reasonable predictions of bioassay quantities. Some examples of the bioassay applications, e.g., excretion data for the
Determination of sedimentation rates and absorption coefficient of ...
2+ has a higher sedimentation rate of 5.10x10-2 s-1 while Ni2+ has the lowest sedimentation rates of 1.10 x10-3. The rate of sedimentation of the metal carbonates decreased in the order: Zn2+ > Cd2+ > Cu2+ > Co2+ > Ni2+. The order ...
Calculation of high-order virial coefficients for the square-well potential.
Do, Hainam; Feng, Chao; Schultz, Andrew J; Kofke, David A; Wheatley, Richard J
2016-07-01
Accurate virial coefficients B_{N}(λ,ɛ) (where ɛ is the well depth) for the three-dimensional square-well and square-step potentials are calculated for orders N=5-9 and well widths λ=1.1-2.0 using a very fast recursive method. The efficiency of the algorithm is enhanced significantly by exploiting permutation symmetry and by storing integrands for reuse during the calculation. For N=9 the storage requirements become sufficiently large that a parallel algorithm is developed. The methodology is general and is applicable to other discrete potentials. The computed coefficients are precise even near the critical temperature, and thus open up possibilities for analysis of criticality of the system, which is currently not accessible by any other means.
Calculation of the mutual diffusion coefficient by equilibrium and nonequilibrium molecular dynamics
Erpenbeck, J.J.; Kincaid, J.M.
1985-01-01
A nonequilibrium molecular dynamics method for the calculation of the mutual diffusion coefficient for a mixture of hard spheres is described. The method is applied to a 50-50 mixture of equidiameter particles having a mass ratio of 0.1 for the two species, at a volume of three times close-packing. By extrapolating the results to the limit of vanishing concentration gradient and infinite system size, we obtain a value in statistical agreement with the result obtained using a Green-Kubo molecular dynamics procedure which is also described. The nonequilibrium calculation yields a mutual diffusion coefficient which decreases slightly with increasing concentration gradient. The Green-Kubo time correlation function for mutual diffusion displays a slow decay with time, qualitatively similar to the long-time tail which has been predicted by the hydrodynamic theory of Pomeau
Calculation of the mutual diffusion coefficient by equilibrium and nonequilibrium molecular dynamics
Erpenbeck, J.J.; Kincaid, J.M.
1986-01-01
A nonequilibrium molecular dynamics method for the calculation of the mutual diffusion coefficient for a mixture of hard spheres is described. The method is applied to a 50-50 mixture of equidiameter particles having a mass ratio of 0.1 for the two species, at a volume of three times close-packing. By extrapolating the results to the limit of vanishing concentration gradient and infinite system size, we obtain a value in statistical agreement with the result obtained using a Green-Kubo molecular dynamics procedure, which is also described. The nonequilibrium calculation yields a mutual diffusion coefficient which decreases slightly with increasing concentration gradient. The Green-Kubo timecorrelation function for mutual diffusion displays a slow decay with time, qualitatively similar to the long-time tail which has been predicted by the hydrodynamic theory of Pomeau
Roteta, M.; Baro, J.; Fernandez-Varea, J.M.; Salvat, F.
1994-01-01
The FORTRAN 77 code PHOTAC to compute photon attenuation coefficients of elements and compounds is described. The code is based on the semi-analytical approximate atomic cross sections proposed by Baro et al. (1994). Photoelectric cross sections are calculated directly from a simple analytical expression. Atomic cross sections for coherent and incoherent scattering and for pair production are obtained as integrals of the corresponding differential cross sections. These integrals are evaluated, to a pre-selected accuracy, by using a 20-point Gauss adaptive integration algorithm. Calculated attenuation coefficients agree with recently compiled databases to within equal 1%, in the energy range from 1 KeV to 1 GeV. The complete source listing of the program PHOTAC is included
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
Calculation of the octanol-water partition coefficient of armchair polyhex BN nanotubes
Mohammadinasab, E.; Pérez-Sánchez, H.; Goodarzi, M.
2017-12-01
A predictive model for determination partition coefficient (log P) of armchair polyhex BN nanotubes by using simple descriptors was built. The relationship between the octanol-water log P and quantum chemical descriptors, electric moments, and topological indices of some armchair polyhex BN nanotubes with various lengths and fixed circumference are represented. Based on density functional theory electric moments and physico-chemical properties of those nanotubes are calculated.
CALCULATION OF COEFFICIENT OF SHARING OCTANOL-WATER OF ORGANIC COMPOUNDS USING MOLECULAR DESCRIPTORS
B. Souyei
2010-12-01
Full Text Available A quantitative structure-property relationship (QSPR study is carried out to develop correlations that relate the molecular structures of organic compounds to their Octanol- Water partition coefficients, Kow , using molecular descriptors. The correlations are simple in application with good accuracy, which provide an easy, direct and relatively accurate way to calculate Kow. Such calculation gives us a model that gives results in remarkable correlation with the descriptors of blocks fragments of the atom-centered and functional groups (R2 = 0.949, δ = 0477 (R2 = 0.926,δ = 0,548 respectively.
METHODOLOGY FOR CALCULATION OF HORIZONTAL WATER PERMEABILITY COEFFICIENT IN SOIL CAPILLARY BORDER
E. I. Michnevich
2011-01-01
Full Text Available The paper shows that for overall estimation of soil water permeability it is necessary to know a horizontal water permeability value of a soil capillary border in addition to coefficients of filtration and permeability. Relations allowing to determine soil permeability in the area of incomplete saturation, are given in the paper. For a fully developed capillary border some calculation formulae have been obtained in the form of algebraic polynomial versus soil grading (grain composition. These formulae allow to make more accurate calculations while designing and operating reclamation works.
Bhatnagar, Navendu; Kamath, Ganesh; Chelst, Issac; Potoff, Jeffrey J
2012-07-07
The 1-octanol-water partition coefficient log K(ow) of a solute is a key parameter used in the prediction of a wide variety of complex phenomena such as drug availability and bioaccumulation potential of trace contaminants. In this work, adaptive biasing force molecular dynamics simulations are used to determine absolute free energies of hydration, solvation, and 1-octanol-water partition coefficients for n-alkanes from methane to octane. Two approaches are evaluated; the direct transfer of the solute from 1-octanol to water phase, and separate transfers of the solute from the water or 1-octanol phase to vacuum, with both methods yielding statistically indistinguishable results. Calculations performed with the TIP4P and SPC∕E water models and the TraPPE united-atom force field for n-alkanes show that the choice of water model has a negligible effect on predicted free energies of transfer and partition coefficients for n-alkanes. A comparison of calculations using wet and dry octanol phases shows that the predictions for log K(ow) using wet octanol are 0.2-0.4 log units lower than for dry octanol, although this is within the statistical uncertainty of the calculation.
Damla, N.; Baltas, H.; Celik, A.; Kiris, E.; Cevik, U.
2008-01-01
Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass attenuation coefficient, effective atomic, numbers (Z eff ), effective electron densities (N e ) and photon interaction cross section (σ a ) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass attenuation coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass attenuation coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory. (authors)
Calculation of calcium diffusion coefficient of cement hardenings using minute pore data
Hitomi, Takashi; Takeda, Nobufumi; Iriya, Keishiro
2009-01-01
This report describes the calculations of the diffusion coefficient of the Ca ion of cement hardenings using minute pore data. The observed hardenings were ordinary Portland cement (OPC), low-heat Portland cement with fly ash (LPC+FA) and highly fly ash containing silica fume cement (HFSC). The samples were cured in the standard and artificially leached by accelerated test. Minute pore datas of the cement hardenings were acquired with image processing of internal structural information obtained from high resolution X-ray computed tomography observations. Upon analysis, several voxels are combined into one bigger voxel, the diffusion coefficient of the voxels were determined in proportion to the number of voxels which were included in. The results reveal that the change in the calcium diffusion coefficient of OPC due to leaching was large, but the LPC+FA and HFSC cements exhibited even greater changes than OPC. It is suggested that the diffusion coefficients are proportional to the Ca/Si ratio of the samples. (author)
Comparison of the methods for calculating the interfacial heat transfer coefficient in hot stamping
Zhao, Kunmin; Wang, Bin; Chang, Ying; Tang, Xinghui; Yan, Jianwen
2015-01-01
This paper presents a hot stamping experimentation and three methods for calculating the Interfacial Heat Transfer Coefficient (IHTC) of 22MnB5 boron steel. Comparison of the calculation results shows an average error of 7.5% for the heat balance method, 3.7% for the Beck's nonlinear inverse estimation method (the Beck's method), and 10.3% for the finite-element-analysis-based optimization method (the FEA method). The Beck's method is a robust and accurate method for identifying the IHTC in hot stamping applications. The numerical simulation using the IHTC identified by the Beck's method can predict the temperature field with a high accuracy. - Highlights: • A theoretical formula was derived for direct calculation of IHTC. • The Beck's method is a robust and accurate method for identifying IHTC. • Finite element method can be used to identify an overall equivalent IHTC
New method for calculating the coupling coefficient in graded index optical fibers
Savović, Svetislav; Djordjevich, Alexandar
2018-05-01
A simple method is proposed for determining the mode coupling coefficient D in graded index multimode optical fibers. It only requires observation of the output modal power distribution P(m, z) for one fiber length z as the Gaussian launching modal power distribution changes, with the Gaussian input light distribution centered along the graded index optical fiber axis (θ0 = 0) without radial offset (r0 = 0). A similar method we previously proposed for calculating the coupling coefficient D in a step-index multimode optical fibers where the output angular power distributions P(θ, z) for one fiber length z with the Gaussian input light distribution launched centrally along the step-index optical fiber axis (θ0 = 0) is needed to be known.
Barlow, Andrew L; Macleod, Alasdair; Noppen, Samuel; Sanderson, Jeremy; Guérin, Christopher J
2010-12-01
One of the most routine uses of fluorescence microscopy is colocalization, i.e., the demonstration of a relationship between pairs of biological molecules. Frequently this is presented simplistically by the use of overlays of red and green images, with areas of yellow indicating colocalization of the molecules. Colocalization data are rarely quantified and can be misleading. Our results from both synthetic and biological datasets demonstrate that the generation of Pearson's correlation coefficient between pairs of images can overestimate positive correlation and fail to demonstrate negative correlation. We have demonstrated that the calculation of a thresholded Pearson's correlation coefficient using only intensity values over a determined threshold in both channels produces numerical values that more accurately describe both synthetic datasets and biological examples. Its use will bring clarity and accuracy to colocalization studies using fluorescent microscopy.
Measurement and CFD calculation of spacer loss coefficient for a tight-lattice fuel bundle
In, Wang Kee; Shin, Chang Hwan; Kwack, Young Kyun; Lee, Chi Young
2015-01-01
Highlights: • Experiment and CFD analysis evaluated the pressure drop in a spacer grid. • The measurement and CFD errors for the spacer loss coefficient were estimated. • The spacer loss coefficient for the dual-cooled annular fuel bundle was determined. • The CFD prediction agrees with the measured spacer loss coefficient within 8%. - Abstract: An experiment and computational fluid dynamics (CFD) analysis were performed to evaluate the pressure drop in a spacer grid for a dual-cooled annular fuel (DCAF) bundle. The DCAF bundle for the Korean optimum power reactor (OPR1000) is a 12 × 12 tight-lattice rod array with a pitch-to-diameter ratio of 1.08 owing to a larger outer diameter of the annular fuel rod. An experiment was conducted to measure the pressure drop in spacer grid for the DCAF bundle. The test bundle is a full-size 12 × 12 rod bundle with 11 spacer grid. The test condition covers a Reynolds number range of 2 × 10 4 –2 × 10 5 by changing the temperature and flow rate of water. A CFD analysis was also performed to predict the pressure drop through a spacer grid using the full-size and partial bundle models. The pressure drop and loss coefficient of a spacer grid were predicted and compared with the experimental results. The CFD predictions of spacer pressure drop and loss coefficient agree with the measured values within 8%. The spacer loss coefficient for the DCAF bundle is estimated to be approximately 1.50 at a nominal operating condition of OPR1000, i.e., Re = 4 × 10 5
Johns, Maureen; Liu, Hanli
2003-07-01
When light interacts with tissue, it can be absorbed, scattered or reflected. Such quantitative information can be used to characterize the optical properties of tissue, differentiate tissue types in vivo, and identify normal versus diseased tissue. The purpose of this research is to develop an algorithm that determines the reduced scattering coefficient (μs") of tissues from a single optical reflectance spectrum with a small source-detector separation. The basic relationship between μs" and optical reflectance was developed using Monte Carlo simulations. This produced an analytical equation containing μs" as a function of reflectance. To experimentally validate this relationship, a 1.3-mm diameter fiber optic probe containing two 400-micron diameter fibers was used to deliver light to and collect light from Intralipid solutions of various concentrations. Simultaneous measurements from optical reflectance and an ISS oximeter were performed to validate the calculated μs" values determined by the reflectance measurement against the 'gold standard" ISS readings. The calculated μs" values deviate from the expected values by approximately -/+ 5% with Intralipid concentrations between 0.5 - 2.5%. The scattering properties within this concentration range are similar to those of in vivo tissues. Additional calculations are performed to determine the scattering properties of rat brain tissues and to discuss accuracy of the algorithm for measured samples with a broad range of the absorption coefficient (μa).
Kustova, E. V.; Savelev, A. S.; Kunova, O. V.
2018-05-01
Theoretical models for the vibrational state-resolved Zeldovich reaction are assessed by comparison with the results of quasi-classical trajectory (QCT) calculations. An error in the model of Aliat is corrected; the model is generalized taking into account NO vibrational states. The proposed model is fairly simple and can be easily implemented to the software for non-equilibrium flow modeling. It provides a good agreement with the QCT rate coefficients in the whole range of temperatures and reagent/product vibrational states. The developed models are tested in simulations of vibrational and chemical relaxation of air mixture behind a shock wave. The importance of accounting for excitated NO vibrational states and accurate prediction of Zeldovich reactions rates is shown.
Recommended data on proton-ion collision rate coefficients for Fe X-Fe XV ions
Skobelev, I.; Murakami, I.; Kato, T.
2006-01-01
The proton-ion collisions are important for excitation of some ion levels in a high-temperature low density plasma. In the present work evaluation of data obtained for proton-induced transitions in Fe X - Fe XV ions with the help of different theoretical methods is carried out. It is suggested a simple analytical formula with 7 parameters allowing to describe dependency of proton rate coefficient on proton temperature in an enough wide temperature range. The values of free parameters have been determined by fitting of approximation formula to numerical data and are presented for recommended data together with fitting accuracies. By comparing of proton collision rates with electron ones it is shown that proton impact excitation processes may be important for Fe X, XI, XIII-XV ions. The results obtained can be used for plasma kinetics calculations and for development of spectroscopy methods of plasma diagnostics. (author)
Fukuda, Makoto; Yoshimura, Kengo; Namekawa, Koki; Sakai, Kiyotaka
2017-06-01
The objective of the present study is to evaluate the effect of filtration coefficient and internal filtration on dialysis fluid flow and mass transfer coefficient in dialyzers using dimensionless mass transfer correlation equations. Aqueous solution of vitamin B 12 clearances were obtained for REXEED-15L as a low flux dialyzer, and APS-15EA and APS-15UA as high flux dialyzers. All the other design specifications were identical for these dialyzers except for filtration coefficient. The overall mass transfer coefficient was calculated, moreover, the exponents of Reynolds number (Re) and film mass transfer coefficient of the dialysis-side fluid (k D ) for each flow rate were derived from the Wilson plot and dimensionless correlation equation. The exponents of Re were 0.4 for the low flux dialyzer whereas 0.5 for the high flux dialyzers. Dialysis fluid of the low flux dialyzer was close to laminar flow because of its low filtration coefficient. On the other hand, dialysis fluid of the high flux dialyzers was assumed to be orthogonal flow. Higher filtration coefficient was associated with higher k D influenced by mass transfer rate through diffusion and internal filtration. Higher filtration coefficient of dialyzers and internal filtration affect orthogonal flow of dialysis fluid.
Dose Rate and Mass Attenuation Coefficients of Gamma Ray for Concretes
Abdel-Latif, A A; Kansouh, W A; El-Sayed, F H
2003-01-01
This work is concerned with the study of the leakage gamma ray dose and mass attenuation coefficients for ordinary, basalt and dolomite concretes made from local ores. Concretes under investigation were constructed from gravel, basalt and dolomite ores, and then reconstructed with the addition of 3% steel fibers by weight. Measurements were carried out using a collimated beam from sup 6 sup 0 Co gamma ray source and sodium iodide (3x3) crystal with the genie 2000 gamma spectrometer. The obtained fluxes were transformed to gamma ray doses and displayed in the form of gamma ray dose rates distribution. The displayed curves were used to estimate the linear attenuation coefficients (mu), the relaxation lengths (lambda), half value layer (t sub 1 /2) and tenth value layer (t sub 1 /10). Also, The total mass attenuation coefficients of gamma ray have been calculated to the concerned concretes using XCOM (version 3.1) program and database elements cross sections from Z=1 to 100 at energies from 10 keV to 100 MeV. In...
Improved calculation of the third virial coefficient of a free anyon gas
Law, J.; Khare, A.; Bhaduri, R.K.; Suzuki, A.
1994-01-01
For three anyons confined in a harmonic oscillator, only the class of states that interpolates nonlinearly with the statistical parameter contributes to the third virial coefficient of a free anyon gas. Rather than evaluating the full three-body partition function as was done in an earlier publication [J. Law, A. Suzuki, and R. Bhaduri, Phys. Rev. A 46, 4693 (1992)], here only the nonlinear contribution is calculated, thus avoiding delicate cancellations between the irrelevant linear part and the two-body partition function. Our numerical results are consistent with the simple analytical form suggested recently by Myrheim and Olaussen [Phys. Lett. B 299, 267 (1993)
Calculations of the nozzle coefficient of discharge of wet steam turbine stages
Jinling, Z.; Yinian, C.
1989-01-01
A method is presented for calculating the coefficient of discharge of wet steam turbine nozzles. The theoretical formulation of the problem is rigorously in accordance with the theory of two-phase wet steam expansion flow through steam turbine nozzles. The computational values are plotted as sets of curves in accordance with orthogonality test principles. They agree satisfactorily both with historical empirical data and the most recent experimental data obtained in the wet steam two-phase flow laboratory of Xian Jiaotong University. (author)
Calculating the Jet Transport Coefficient q-hat in Lattice Gauge Theory
Majumder, Abhijit
2013-01-01
The formalism of jet modification in the higher twist approach is modified to describe a hard parton propagating through a hot thermalized medium. The leading order contribution to the transverse momentum broadening of a high energy (near on-shell) quark in a thermal medium is calculated. This involves a factorization of the perturbative process of scattering of the quark from the non-perturbative transport coefficient. An operator product expansion of the non-perturbative operator product which represents q -hat is carried out and related via dispersion relations to the expectation of local operators. These local operators are then evaluated in quenched SU(2) lattice gauge theory
A simple formalism for diffusion coefficient calculations in cells having a small optical thickness
Benoist, Pierre.
1980-04-01
A very simple formalism, using directionnal first flight collision probabilities, is established; it is assigned to the calculation of the diffusion coefficients in cells having a small optical thickness. This formalism can be used, at least as a first approximation, in lattices of sodium-cooled fast reactors or of light water reactors. However, due to the two assumptions -cylindricalization of the cell and restriction to the zeroth order term in B 2 (k)- this formalissm cannot be used for sodium-voided or gas-cooled fast reactor lattices [fr
Database crime to crime match rate calculation.
Buckleton, John; Bright, Jo-Anne; Walsh, Simon J
2009-06-01
Guidance exists on how to count matches between samples in a crime sample database but we are unable to locate a definition of how to estimate a match rate. We propose a method that does not proceed from the match counting definition but which has a strong logic.
Kato, T.; Asano, E. [National Institute for Fusion Science, Toki, Gifu (Japan)
1999-06-01
Recombination rate coefficients based on several empirical formulae are compared for ions of H, He, C, N, O, Ne, Na, Mg, Al, Si, S, P, Cl, Ar, Ca, Fe and Ni. The total rate coefficients including radiative recombination and dielectronic recombination are shown in graphs. (author)
Božidar Liščić
2012-02-01
Full Text Available This paper explains the need for a database of cooling intensities for liquid quenchants, in order to predict the quench hardness, microstructure, stresses and distortion, when real engineering components of complex geometry are quenched. The existing laboratory procedures for cooling intensity evaluation, using small test specimens, and Lumped-Heat-Capacity Method for calculation of heat transfer coefficient, are presented. Temperature Gradient Method for heat transfer calculation in workshop conditions, when using the Liscic/Petrofer probe, has been elaborated. Critical heat flux densities and their relation to the initial heat flux density, is explained. Specific facilities for testing quenching intensity in workshop conditions, are shown. The two phase project of the International Federation for Heat Treatment and Surface Engineering (IFHTSE, as recently approved, is mentioned.
Kawamura, T.; Ono, T.; Yamamura, Y.
1994-08-01
Physical sputtering yields from the carbon surface irradiated by the boundary plasma are obtained with the use of a Monte Carlo simulation code ACAT. The yields are calculated for many random initial energy and angle values of incident protons or deuterons with a Maxwellian velocity distribution, and then averaged. Here the temperature of the boundary plasma, the sheath potential and the angle δ between the magnetic field line and the surface normal are taken into account. A new fitting formula for an arrangement of the numerical data of sputtering yield is introduced, in which six fitting parameters are determined from the numerical results and listed. These results provide a way to estimate the erosion of carbon materials irradiated by boundary plasma. The particle reflection coefficients for deuterons and their neutrals from a carbon surface are also calculated by the same code and presented together with, for comparison, that for the case of monoenergetic normal incidence. (author)
Yang, Huan; Goudeli, Eirini; Hogan, Christopher J.
2018-04-01
In gas phase synthesis systems, clusters form and grow via condensation, in which a monomer binds to an existing cluster. While a hard-sphere equation is frequently used to predict the condensation rate coefficient, this equation neglects the influences of potential interactions and cluster internal energy on the condensation process. Here, we present a collision rate theory-molecular dynamics simulation approach to calculate condensation probabilities and condensation rate coefficients. We use this approach to examine atomic condensation onto 6-56-atom Au and Mg clusters. The probability of condensation depends upon the initial relative velocity (v) between atom and cluster and the initial impact parameter (b). In all cases, there is a well-defined region of b-v space where condensation is highly probable, and outside of which the condensation probability drops to zero. For Au clusters with more than 10 atoms, we find that at gas temperatures in the 300-1200 K range, the condensation rate coefficient exceeds the hard-sphere rate coefficient by a factor of 1.5-2.0. Conversely, for Au clusters with 10 or fewer atoms and for 14- and 28-atom Mg clusters, as cluster equilibration temperature increases, the condensation rate coefficient drops to values below the hard-sphere rate coefficient. Calculations also yield the self-dissociation rate coefficient, which is found to vary considerably with gas temperature. Finally, calculations results reveal that grazing (high b) atom-cluster collisions at elevated velocity (>1000 m s-1) can result in the colliding atom rebounding (bounce) from the cluster surface or binding while another atom dissociates (replacement). The presented method can be applied in developing rate equations to predict material formation and growth rates in vapor phase systems.
Barbosa, Thaís da Silva; Peirone, Silvina; Barrera, Javier A; Abrate, Juan P A; Lane, Silvia I; Arbilla, Graciela; Bauerfeldt, Glauco Favilla
2015-04-14
The kinetics of the cis-3-hexene + OH reaction were investigated by an experimental relative rate method and at the density functional theory level. The experimental set-up consisted of a 200 L Teflon bag, operated at atmospheric pressure and 298 K. OH radicals were produced by the photolysis of H2O2 at 254 nm. Relative rate coefficients were determined by comparing the decays of the cis-3-hexene and reference compounds (cyclohexene, 2-buten-1-ol and allyl ether). The mean second-order rate coefficient value found was (6.27 ± 0.66) × 10(-11) cm(3) molecule(-1) s(-1), the uncertainty being estimated by propagation of errors. Theoretical calculations for the addition reaction of OH to cis-3-hexene have also been performed, at the BHandHLYP/aug-cc-pVDZ level, in order to investigate the reaction mechanism, to clarify the experimental observations and to model the reaction kinetics. Different conformations of the reactants, pre-barrier complexes and saddle points were considered in our calculations. The individual rate coefficients, calculated for each conformer of the reactant, at 298 K, using a microcanonical variational transition state method, are 4.19 × 10(-11) and 1.23 × 10(-10) cm(3) molecule(-1) s(-1). The global rate coefficient was estimated from the Boltzmann distribution of the conformers to be 8.10 × 10(-11) cm(3) molecule(-1) s(-1), which is in agreement with the experimental value. Rate coefficients calculated over the temperature range from 200-500 K are also given. Our results suggest that the complex mechanism, explicitly considering different conformations for the stationary points, must be taken into account for a proper description of the reaction kinetics.
49 CFR 1141.1 - Procedures to calculate interest rates.
2010-10-01
... the portion of the year covered by the interest rate. A simple multiplication of the nominal rate by... 49 Transportation 8 2010-10-01 2010-10-01 false Procedures to calculate interest rates. 1141.1... TRANSPORTATION BOARD, DEPARTMENT OF TRANSPORTATION RULES OF PRACTICE PROCEDURES TO CALCULATE INTEREST RATES...
Molecular radiotherapy: The NUKFIT software for calculating the time-integrated activity coefficient
Kletting, P.; Schimmel, S.; Luster, M. [Klinik für Nuklearmedizin, Universität Ulm, Ulm 89081 (Germany); Kestler, H. A. [Research Group Bioinformatics and Systems Biology, Institut für Neuroinformatik, Universität Ulm, Ulm 89081 (Germany); Hänscheid, H.; Fernández, M.; Lassmann, M. [Klinik für Nuklearmedizin, Universität Würzburg, Würzburg 97080 (Germany); Bröer, J. H.; Nosske, D. [Bundesamt für Strahlenschutz, Fachbereich Strahlenschutz und Gesundheit, Oberschleißheim 85764 (Germany); Glatting, G. [Medical Radiation Physics/Radiation Protection, Medical Faculty Mannheim, Heidelberg University, Mannheim 68167 (Germany)
2013-10-15
Purpose: Calculation of the time-integrated activity coefficient (residence time) is a crucial step in dosimetry for molecular radiotherapy. However, available software is deficient in that it is either not tailored for the use in molecular radiotherapy and/or does not include all required estimation methods. The aim of this work was therefore the development and programming of an algorithm which allows for an objective and reproducible determination of the time-integrated activity coefficient and its standard error.Methods: The algorithm includes the selection of a set of fitting functions from predefined sums of exponentials and the choice of an error model for the used data. To estimate the values of the adjustable parameters an objective function, depending on the data, the parameters of the error model, the fitting function and (if required and available) Bayesian information, is minimized. To increase reproducibility and user-friendliness the starting values are automatically determined using a combination of curve stripping and random search. Visual inspection, the coefficient of determination, the standard error of the fitted parameters, and the correlation matrix are provided to evaluate the quality of the fit. The functions which are most supported by the data are determined using the corrected Akaike information criterion. The time-integrated activity coefficient is estimated by analytically integrating the fitted functions. Its standard error is determined assuming Gaussian error propagation. The software was implemented using MATLAB.Results: To validate the proper implementation of the objective function and the fit functions, the results of NUKFIT and SAAM numerical, a commercially available software tool, were compared. The automatic search for starting values was successfully tested for reproducibility. The quality criteria applied in conjunction with the Akaike information criterion allowed the selection of suitable functions. Function fit
Proposals for Calculation of Bucking Coefficient for Concrete-Filled Steel Tube Columns
Krishan, A. L.; Sagadatov, A. I.; Surovtsov, M. M.
2017-11-01
This paper demonstrates that the methodology currently standardized in Russia to factor in the flexibility of reinforced concrete components under extra-central compression produce results that satisfactorily match the experimental values; however, that only holds for the components with a flexibility of λ=40÷60. Given the complex stress state of the concrete core and the steel shell as well as due to the concrete-filled steel tube columns being prone to deformation, this method cannot be used to reliably calculate their load capacity. The literature review has revealed many researchers’ suggestions to factor in the flexibility of concrete-filled steel tubes by means of the buckling coefficient that reduces the limit value of longitudinal force a short compressed element can take. We have analyzed the methods currently standardized in Europe and China as well as more advanced methods proposed by Chinese scientists. Calculating by these methods led to the results that excessively deviated from experimental values. By statistically analyzing a large volume of own and third-party research data as well as the data obtained by non-linear deformation computing, we have derived a new formula to determine the bucking coefficient depending on the relative flexibility.
Barut, A.O.; Salamin, Y.I.
1989-07-01
We present a simple approach to the relativistic calculation of the rates of spontaneous emission starting from the Heisenberg picture formula for the power radiated by a charged particle undergoing acceleration, and evaluate atomic decay rates using relativistic Dirac-Coulomb wavefunctions. The spin of the electron, embedded in its relativistic wavefunction, is shown to correctly provide the two polarization states of the emitted radiation. We discuss selection rules and calculate the Hydrogen 2 P → 1 S transition rate, among others, to be Γ = (6.2650 ± 0.0007)x10 8 s -1 in good agreement with the full field theory calculation as well as with experiment. (author). 14 refs
Determination of the reaction rate coefficient of sulphide mine tailings deposited under water.
Awoh, Akué Sylvette; Mbonimpa, Mamert; Bussière, Bruno
2013-10-15
The efficiency of a water cover to limit dissolved oxygen (DO) availability to underlying acid-generating mine tailings can be assessed by calculating the DO flux at the tailings-water interface. Fick's equations, which are generally used to calculate this flux, require knowing the effective DO diffusion coefficient (Dw) and the reaction (consumption) rate coefficient (Kr) of the tailings, or the DO concentration profile. Whereas Dw can be accurately estimated, few studies have measured the parameter Kr for submerged sulphide tailings. The objective of this study was to determine Kr for underwater sulphide tailings in a laboratory experiment. Samples of sulphide mine tailings (an approximately 6 cm layer) were placed in a cell under a water cover (approximately 2 cm) maintained at constant DO concentration. Two tailings were studied: TA1 with high sulphide content (83% pyrite) and TA2 with low sulphide content (2.8% pyrite). DO concentration was measured with a microelectrode at various depths above and below the tailings-water interface at 1 mm intervals. Results indicate that steady-state condition was rapidly attained. As expected, a diffusive boundary layer (DBL) was observed in all cases. An iterative back-calculation process using the numerical code POLLUTEv6 and taking the DBL into account provided the Kr values used to match calculated and experimental concentration profiles. Kr obtained for tailings TA1 and TA2 was about 80 d(-1) and 6.5 d(-1), respectively. For comparison purposes, Kr obtained from cell tests on tailings TA1 was lower than Kr calculated from the sulphate production rate obtained from shake-flask tests. Steady-state DO flux at the water-tailings interface was then calculated with POLLUTEv6 using tailings characteristics Dw and Kr. For the tested conditions, DO flux ranged from 608 to 758 mg O2/m(2)/d for tailings TA1 and from 177 to 221 mg O2/m(2)/d for tailings TA2. The impact of placing a protective layer of inert material over
Zokaei-Kadijani, S.; Safdari, J.; Mousavian, M.A.; Rashidi, A.
2013-01-01
Highlights: ► Mass transfer coefficient does not depend on biomass concentration. ► The pulp density has a negative effect on mass transfer coefficient. ► The pulp density is the unique factor that affects maximum OUR. ► In this work, Neale’s correlation is corrected for prediction of mass transfer coefficient. ► Biochemical reaction is a limiting factor in the uranium bioleaching process. - Abstract: In this work, the volumetric oxygen mass transfer coefficient and the oxygen uptake rate (OUR) were studied for uranium ore bioleaching process by Acidthiobacillus ferrooxidans in a stirred tank reactor. The Box-Bohnken design method was used to study the effect of operating parameters on the oxygen mass transfer coefficient. The investigated factors were agitation speed (rpm), aeration rate (vvm) and pulp density (% weight/volume) of the stirred tank reactor. Analysis of experimental results showed that the oxygen mass transfer coefficient had low dependence on biomass concentration but had higher dependence on the agitation speed, aeration rate and pulp density. The obtained biological enhancement factors were equal to ones in experiments. On the other hand, the obtained values for Damkohler number (Da < 0.468) indicated that the process was limited by the biochemical reaction rate. Experimental results obtained for oxygen mass transfer coefficient were correlated with the empirical relations proposed by Garcia-Ochoa and Gomez (2009) and Neale and Pinches (1994). Due to the high relative error in the correlation of Neale and Pinches, that correlation was corrected and the coefficient of determination was calculated to be 89%. The modified correlation has been obtained based on a wide range of operating conditions, which can be used to determine the mass transfer coefficient in a bioreactor
A program for calculating and plotting soft x-ray optical interaction coefficients for molecules
Thomas, M.M.; Davis, J.C.; Jacobsen, C.J.; Perera, R.C.C.
1989-08-01
Comprehensive tables for atomic scattering factor components, f1 and f2, were compiled by Henke et al. for the extended photon region 50 - 10000 eV. Accurate calculations of optical interaction coefficients for absorption, reflection and scattering by material systems (e.g. filters, multi-layers, etc...), which have widespread application, can be based simply upon the atomic scattering factors for the elements comprising the material, except near the absorption threshold energies. These calculations based upon the weighted sum of f1 and f2 for each atomic species present can be very tedious if done by hand. This led us to develop a user friendly program to perform these calculations on an IBM PC or compatible computer. By entering the chemical formula, density and thickness of up to six molecules, values of the f1, f2, mass absorption transmission efficiencies, attenuation lengths, mirror reflectivities and complex indices of refraction can be calculated and plotted as a function of energy or wavelength. This program will be available distribution. 7 refs., 1 fig
Calculating the Rate of Senescence From Mortality Data
Koopman, Jacob J E; Rozing, Maarten P; Kramer, Anneke
2016-01-01
, they do not fit mortality rates at young and old ages. Therefore, we developed a method to calculate senescence rates from the acceleration of mortality directly without modeling the mortality rates. We applied the different methods to age group-specific mortality data from the European Renal Association......, the rate of senescence can be calculated directly from non-modeled mortality rates, overcoming the disadvantages of an indirect estimation based on modeled mortality rates....
THIDA: code system for calculation of the exposure dose rate around a fusion device
Iida, Hiromasa; Igarashi, Masahito.
1978-12-01
A code system THIDA has been developed for calculation of the exposure dose rates around a fusion device. It consists of the following: one- and two-dimensional discrete ordinate transport codes; induced activity calculation code; activation chain, activation cross section, radionuclide gamma-ray energy/intensity and gamma-ray group constant files; and gamma ray flux to exposure dose rate conversion coefficients. (author)
The correlation schemes in calculations of the rate constants of some radiation chemical reactions
Zagorets, P.A.; Shostenko, A.G.; Kim, V.
1983-01-01
The various correlation relationships of the evaluation of the rate constants of radiation chemical reactions of addition, abstraction and isomerization were considered. It was shown that neglection of the influence of solvent can result in errors in calculations of rate constants equalling two orders in magnitude. Several examples of isokinetic relationship are given. The methods of calculation of transmission coefficient of reaction addition have been discussed. (author)
Determination of Krypton Diffusion Coefficients in Uranium Dioxide Using Atomic Scale Calculations.
Vathonne, Emerson; Andersson, David A; Freyss, Michel; Perriot, Romain; Cooper, Michael W D; Stanek, Christopher R; Bertolus, Marjorie
2017-01-03
We present a study of the diffusion of krypton in UO 2 using atomic scale calculations combined with diffusion models adapted to the system studied. The migration barriers of the elementary mechanisms for interstitial or vacancy assisted migration are calculated in the DFT+U framework using the nudged elastic band method. The attempt frequencies are obtained from the phonon modes of the defect at the initial and saddle points using empirical potential methods. The diffusion coefficients of Kr in UO 2 are then calculated by combining this data with diffusion models accounting for the concentration of vacancies and the interaction of vacancies with Kr atoms. We determined the preferred mechanism for Kr migration and the corresponding diffusion coefficient as a function of the oxygen chemical potential μ O or nonstoichiometry. For very hypostoichiometric (or U-rich) conditions, the most favorable mechanism is interstitial migration. For hypostoichiometric UO 2 , migration is assisted by the bound Schottky defect and the charged uranium vacancy, V U 4- . Around stoichiometry, migration assisted by the charged uranium-oxygen divacancy (V UO 2- ) and V U 4- is the favored mechanism. Finally, for hyperstoichiometric or O-rich conditions, the migration assisted by two V U 4- dominates. Kr migration is enhanced at higher μ O , and in this regime, the activation energy will be between 4.09 and 0.73 eV depending on nonstoichiometry. The experimental values available are in the latter interval. Since it is very probable that these values were obtained for at least slightly hyperstoichiometric samples, our activation energies are consistent with the experimental data, even if further experiments with precisely controlled stoichiometry are needed to confirm these results. The mechanisms and trends with nonstoichiometry established for Kr are similar to those found in previous studies of Xe.
Kletting, P; Schimmel, S; Kestler, H A; Hänscheid, H; Luster, M; Fernández, M; Bröer, J H; Nosske, D; Lassmann, M; Glatting, G
2013-10-01
Calculation of the time-integrated activity coefficient (residence time) is a crucial step in dosimetry for molecular radiotherapy. However, available software is deficient in that it is either not tailored for the use in molecular radiotherapy and/or does not include all required estimation methods. The aim of this work was therefore the development and programming of an algorithm which allows for an objective and reproducible determination of the time-integrated activity coefficient and its standard error. The algorithm includes the selection of a set of fitting functions from predefined sums of exponentials and the choice of an error model for the used data. To estimate the values of the adjustable parameters an objective function, depending on the data, the parameters of the error model, the fitting function and (if required and available) Bayesian information, is minimized. To increase reproducibility and user-friendliness the starting values are automatically determined using a combination of curve stripping and random search. Visual inspection, the coefficient of determination, the standard error of the fitted parameters, and the correlation matrix are provided to evaluate the quality of the fit. The functions which are most supported by the data are determined using the corrected Akaike information criterion. The time-integrated activity coefficient is estimated by analytically integrating the fitted functions. Its standard error is determined assuming Gaussian error propagation. The software was implemented using MATLAB. To validate the proper implementation of the objective function and the fit functions, the results of NUKFIT and SAAM numerical, a commercially available software tool, were compared. The automatic search for starting values was successfully tested for reproducibility. The quality criteria applied in conjunction with the Akaike information criterion allowed the selection of suitable functions. Function fit parameters and their standard
Rate coefficients for the reactions of ions with polar molecules at interstellar temperatures
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
Cold collisions of SH- with He: Potential energy surface and rate coefficients
Bop, C. T.; Trabelsi, T.; Hammami, K.; Mogren Al Mogren, M.; Lique, F.; Hochlaf, M.
2017-09-01
Collisional energy transfer under cold conditions is of great importance from the fundamental and applicative point of view. Here, we investigate low temperature collisions of the SH- anion with He. We have generated a three-dimensional potential energy surface (PES) for the SH-(X1Σ+)-He(1S) van der Waals complex. The ab initio multi-dimensional interaction PES was computed using the explicitly correlated coupled cluster approach with simple, double, and perturbative triple excitation in conjunction with the augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. The PES presents two minima located at linear geometries. Then, the PES was averaged over the ground vibrational wave function of the SH- molecule and the resulting two-dimensional PES was incorporated into exact quantum mechanical close coupling calculations to study the collisional excitation of SH- by He. We have computed inelastic cross sections among the 11 first rotational levels of SH- for energies up to 2500 cm-1. (De-)excitation rate coefficients were deduced for temperatures ranging from 1 to 300 K by thermally averaging the cross sections. We also performed calculations using the new PES for a fixed internuclear SH- distance. Both sets of results were found to be in reasonable agreement despite differences existing at low temperatures confirming that accurate predictions require the consideration of all internal degrees of freedom in the case of molecular hydrides. The rate coefficients presented here may be useful in interpreting future experimental work on the SH- negative ion colliding with He as those recently done for the OH--He collisional system as well as for possible astrophysical applications in case SH- would be detected in the interstellar medium.
Ferrero, L; Mocnik, G; Ferrini, B S; Perrone, M G; Sangiorgi, G; Bolzacchini, E
2011-06-15
Vertical profiles of aerosol number-size distribution and black carbon (BC) concentration were measured between ground-level and 500m AGL over Milan. A tethered balloon was fitted with an instrumentation package consisting of the newly-developed micro-Aethalometer (microAeth® Model AE51, Magee Scientific, USA), an optical particle counter, and a portable meteorological station. At the same time, PM(2.5) samples were collected both at ground-level and at a high altitude sampling site, enabling particle chemical composition to be determined. Vertical profiles and PM(2.5) data were collected both within and above the mixing layer. Absorption coefficient (b(abs)) profiles were calculated from the Aethalometer data: in order to do so, an optical enhancement factor (C), accounting for multiple light-scattering within the filter of the new microAeth® Model AE51, was determined for the first time. The value of this parameter C (2.05±0.03 at λ=880nm) was calculated by comparing the Aethalometer attenuation coefficient and aerosol optical properties determined from OPC data along vertical profiles. Mie calculations were applied to the OPC number-size distribution data, and the aerosol refractive index was calculated using the effective medium approximation applied to aerosol chemical composition. The results compare well with AERONET data. The BC and b(abs) profiles showed a sharp decrease at the mixing height (MH), and fairly constant values of b(abs) and BC were found above the MH, representing 17±2% of those values measured within the mixing layer. The BC fraction of aerosol volume was found to be lower above the MH: 48±8% of the corresponding ground-level values. A statistical mean profile was calculated, both for BC and b(abs), to better describe their behaviour; the model enabled us to compute their average behaviour as a function of height, thus laying the foundations for valid parametrizations of vertical profile data which can be useful in both remote sensing
Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.
2016-01-01
The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip bounda...
Lei Li
2015-01-01
Full Text Available The ab initio calculations about the properties of the interstitials doping in the rutile TiO2 and their impact on the transport coefficients are reported. As the doping of the Zr or Ti interstitials in the TiO2, the lattice Ti4+ ions acquire the excess electrons so reduced to the Ti3+ or Ti2+ ions. However, the Cu interstitials could not lose enough electrons to reduce the lattice Ti4+ ions. Furthermore, the Ti or Cu interstitials in the ZrO2 also are unable to promote the lattice Zr4+ ions to form the lattice Zr3+ or Zr2+ ions. The high transport coefficients are observed in the defected TiO2 with the Ti or Zr interstitials as the high concentration of the Ti3+ or Ti2+ ions. So, the Zr interstitials are the favorable choice for the extra-doping to improve the transport properties in the TiO2-based resistive random access memory.
Assessing the reliability of calculated catalytic ammonia synthesis rates
Medford, Andrew James; Wellendorff, Jess; Vojvodic, Aleksandra
2014-01-01
We introduce a general method for estimating the uncertainty in calculated materials properties based on density functional theory calculations. We illustrate the approach for a calculation of the catalytic rate of ammonia synthesis over a range of transition-metal catalysts. The correlation...... between errors in density functional theory calculations is shown to play an important role in reducing the predicted error on calculated rates. Uncertainties depend strongly on reaction conditions and catalyst material, and the relative rates between different catalysts are considerably better described...
Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere
Courtin, Regis
1988-01-01
The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.
Low-frequency Carbon Radio Recombination Lines. I. Calculations of Departure Coefficients
Salgado, F.; Morabito, L. K.; Oonk, J. B. R.; Salas, P.; Toribio, M. C.; Röttgering, H. J. A.; Tielens, A. G. G. M. [Leiden Observatory, University of Leiden, P.O. Box 9513, 2300 RA Leiden (Netherlands)
2017-03-10
In the first paper of this series, we study the level population problem of recombining carbon ions. We focus our study on high quantum numbers, anticipating observations of carbon radio recombination lines to be carried out by the Low Frequency Array. We solve the level population equation including angular momentum levels with updated collision rates up to high principal quantum numbers. We derive departure coefficients by solving the level population equation in the hydrogenic approximation and including low-temperature dielectronic capture effects. Our results in the hydrogenic approximation agree well with those of previous works. When comparing our results including dielectronic capture, we find differences that we ascribe to updates in the atomic physics (e.g., collision rates) and to the approximate solution method of the statistical equilibrium equations adopted in previous studies. A comparison with observations is discussed in an accompanying article, as radiative transfer effects need to be considered.
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.
Ablinger, J.; Hasselhuhn, A.; Schneider, C.; Behring, A.; Bluemlein, J.; Freitas, A. de; Raab, C.; Round, M.; Manteuffel, A. von
2014-07-01
We report on our latest results in the calculation of the three-loop heavy flavor contributions to the Wilson coefficients in deep-inelastic scattering in the asymptotic region Q 2 >>m 2 . We discuss the different methods used to compute the required operator matrix elements and the corresponding Feynman integrals. These methods very recently allowed us to obtain a series of new operator matrix elements and Wilson coefficients like the flavor non-singlet and pure singlet Wilson coefficients.
Calculation of the net emission coefficient of an air thermal plasma at very high pressure
Billoux, T; Cressault, Y; Teulet, Ph; Gleizes, A
2012-01-01
The aim of this paper is to present an accurate evaluation of the phenomena appearing for high pressure air plasmas supposed to be in local thermodynamic equilibrium (LTE). In the past, we already calculated the net emission coefficient for air mixtures at atmospheric pressure and for temperatures up to 30kK (molecular contribution being restricted to 10kK). Unfortunately, the existence of high pressures does not allow us to use this database due to the non-ideality of the plasma (Viriel and Debye corrections, energy cut-off ...), and due to the significant shifts of molecular reactions towards upper temperatures. Consequently, this paper proposes an improvement of our previous works with a consideration of high pressure corrections in the composition algorithm in order to take into account the pressure effects, and with a new calculation of all the contributions of the plasma radiation (atomic lines and continuum, molecular continuum, and molecular bands) using an updated database. A particular attention is paid to calculate the contribution of all the major molecular band systems to the radiation: O 2 (Schumann–Runge), N 2 (VUV, 1st and 2nd positive), NO (IR, β, γ, δ, element of ) and N 2 + (1st negative and Meinel). The discrete atomic lines and molecular bands radiation including the overlapping are calculated by a line-by-line method up to 30kK and 100 bar. This updated database is validated in the case of optically thin plasmas and pressure of 1bar by the comparison of our integrated emission strength with the published results. Finally, this work shows the necessity to extend the molecular radiation database up to 15kK at high pressure (bands and continuum) since their corresponding contributions could not be neglected at high temperature.
Impact on Dose Coefficients Calculated with ICRP Adult Mesh-type Reference Computational Phantoms
Yeom, Yeon Soo; Nguyen, Thang Tat; Choi, Chan Soo; Lee, Han Jin; Han, Hae Gin; Han, Min Cheol; Shin, Bang Ho; Kim, Chan Hyeong [Dept. of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)
2017-04-15
In 2016, the International Commission on Radiological Protection (ICRP) formulated a new Task Group (TG) (i.e., TG 103) within Committee 2. The ultimate aim of the TG 103 is to develop the mesh-type reference computational phantoms (MRCPs) that can address dosimetric limitations of the currently used voxel-type reference computational phantoms (VRCPs) due to their limited voxel resolutions. The objective of the present study is to investigate dosimetric impact of the adult MRCPs by comparing dose coefficients (DCs) calculated with the MRCPs for some external and internal exposure cases and the reference DCs in ICRP Publications 116 and 133 that were produced with the adult VRCPs. In the present study, the DCs calculated with the adult MRCPs for some exposure cases were compared with the values in ICRP Publications 116 and 133. This comparison shows that in general the MRCPs provide very similar DCs for uncharged particles, but for charged particles provide significantly different DCs due to the improvement of the MRCPs.
Weiser, P.; Nordmann, R.
1991-01-01
In today's rotordynamic calculations, the input parameters for a finite element analysis (FEA) determine very much the reliability of eigenvalue and eigenmode predictions. While modeling of an elastic structure by means of beam elements etc. is relatively straightforward to perform and the input data for journal bearings are usually known exactly enough, the determination of stiffness and damping for labyrinth seals is still the subject of many investigations. Therefore, the rotordynamic influence of labyrinths is often not included in FEA for rotating machinery because of a lack of computer programs to calculate these parameters. This circumstance can give rise to severe vibration problems especially for high performance turbines or compressors, resulting in remarkable economic losses. The forces generated in labyrinths can be described for small motions around the seal center with a linearized force-motion relationship. Several years ago, we started with the development of computer codes for the determination of rotordynamic seal coefficients. Our different approaches to evaluate the dynamic fluid forces generated by turbulent, compressible seal flow are introduced.
Large scale steam flow test: Pressure drop data and calculated pressure loss coefficients
Meadows, J.B.; Spears, J.R.; Feder, A.R.; Moore, B.P.; Young, C.E.
1993-12-01
This report presents the result of large scale steam flow testing, 3 million to 7 million lbs/hr., conducted at approximate steam qualities of 25, 45, 70 and 100 percent (dry, saturated). It is concluded from the test data that reasonable estimates of piping component pressure loss coefficients for single phase flow in complex piping geometries can be calculated using available engineering literature. This includes the effects of nearby upstream and downstream components, compressibility, and internal obstructions, such as splitters, and ladder rungs on individual piping components. Despite expected uncertainties in the data resulting from the complexity of the piping geometry and two-phase flow, the test data support the conclusion that the predicted dry steam K-factors are accurate and provide useful insight into the effect of entrained liquid on the flow resistance. The K-factors calculated from the wet steam test data were compared to two-phase K-factors based on the Martinelli-Nelson pressure drop correlations. This comparison supports the concept of a two-phase multiplier for estimating the resistance of piping with liquid entrained into the flow. The test data in general appears to be reasonably consistent with the shape of a curve based on the Martinelli-Nelson correlation over the tested range of steam quality
Rate Coefficient Measurements of the Reaction CH3 + O2 = CH3O + O
Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.
1999-01-01
Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, sub -0.47 ) x 10(exp 13) e(-15813 +/- 587 K/T)/cubic cm.mol.s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.
Rate Coefficient Measurements of the Reaction CH3+O2+CH3O+O
Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.
1999-01-01
Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, -0.47)) X 10(exp 13) exp(- 15813 +/- 587 K/T)cc/mol s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.
Updates to In-Line Calculation of Photolysis Rates
How photolysis rates are calculated affects ozone and aerosol concentrations predicted by the CMAQ model and the model?s run-time. The standard configuration of CMAQ uses the inline option that calculates photolysis rates by solving the radiative transfer equation for the needed ...
Population densities and rate coefficients for electron impact excitation in singly ionized oxygen
Awakowicz, P.; Behringer, K.
1995-01-01
In non-LTE arc plasmas, O II excited state number densities were measured relative to the O II ground and metastable states. The results were compared with collisional-radiative code calculations on the basis of the JET ADAS programs. Stationary He plasmas with small oxygen admixtures, generated in a 5 mm diameter cascade arc chamber (pressures 13-70 hPa, arc current 150 A), were investigated spectroscopically in the visible and the VUV spectral range. The continuum of a 2 mm diameter pure He arc (atmospheric pressure, current 100 A) served for calibration of the VUV system response. Plasma diagnostics on the basis of Hβ Stark broadening yielded electron densities between 2.4 x 10 14 and 2.0 x 10 15 cm -3 for the low-pressure O II mixture plasmas. The agreement of measured and calculated excited state populations is generally very satisfactory, thus confirming the rate coefficients in the code. This is of particular interest in this intermediate region between corona balance and LTE, where many atomic data are required in the simulation. Clear indications were found for the diffusion of metastables lowering their number densities significantly below their statistical values. (author)
A calculation of the surface recombination rate constant for hydrogen isotopes on metals
Baskes, M.J.
1980-01-01
The surface recombination rate constant for hydrogen isotopes on a metal has been calculated using a simple model whose parameters may be determined by direct experimental measurements. Using the experimental values for hydrogen diffusivity, solubility, and sticking coefficient at zero surface coverage a reasonable prediction of the surface recombination constant may be made. The calculated recombination constant is in excellent agreement with experiment for bcc iron. A heuristic argument is developed which, along with the rate constant calculation, shows that surface recombination is important in those metals in which hydrogen has an exothermic heat of solution. (orig.)
Some Methods for Calculating Competition Coefficients from Resource-Utilization Spectra.
Schoener, Thomas W
When relative frequencies of resource kinds in the diet are known, the competition coefficient giving the effect of competitor j on i may be computed as \\documentclass{aastex} \\usepackage{amsbsy} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{bm} \\usepackage{mathrsfs} \\usepackage{pifont} \\usepackage{stmaryrd} \\usepackage{textcomp} \\usepackage{portland,xspace} \\usepackage{amsmath,amsxtra} \\usepackage{wasysym} \\pagestyle{empty} \\DeclareMathSizes{10}{9}{7}{6} \\begin{document}$$\\alpha_{ij}=\\left(\\frac{T_{j}}{T_{i}}\\right)\\left[\\frac{{\\sum\\limits_{k=1}^{m}}(d_{ik}/f_{k})\\:(d_{jk}/f_{k})\\:b_{ik}}{\\sum\\limits_{k=1}^{m}(d_{ik}/f_{k})^{2}\\:b_{ik}}\\right],$$\\end{document} where T j /T i = the ratio of the number of items consumed by an individual of competitor j to that consumed by an individual of competitor i, measured over an interval of time that includes all regular fluctuations in consumption for both species; d ik = the frequency of resource k in the diet of competitor i (and similarly for d jk ); f k = the standing frequency of resource k in the environment; b ik = the net calories gained by an individual of competitor i from an item of resource k, or more approximately the calories contained in an item of resource k, or still more approximately the weight or volume of an item of resource k; and the summations are taken over all resources eaten by at least one of the competing species. The coefficient follows from MacArthur's (1968) consumer-resource system when the ratio of the carrying capacity to intrinsic rate of increase is constant for all resources. When relative frequencies of time spent foraging in habitat kinds are known, the competition coefficient may be computed as \\documentclass{aastex} \\usepackage{amsbsy} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{bm} \\usepackage{mathrsfs} \\usepackage{pifont} \\usepackage{stmaryrd} \\usepackage{textcomp} \\usepackage{portland,xspace} \\usepackage
van der Vegt, N.F.A.; Briels, Willem J.; Wessling, Matthias; Strathmann, H.
1998-01-01
The tracer diffusion coefficients of methane in n-alkane liquids of increasing chain length were calculated by measuring the friction from short time nonequilibrium molecular dynamics simulations. The frictional constant was calculated from the exponentially decaying distance between two methane
Kaplan, D.I.; Krupka, K.M.; Serne, R.J.
1997-01-01
As part of an ongoing project funded by a cooperative effort involving the Office of Radiation and Indoor Air (ORIA) of the U.S. Environmental Protection Agency (EPA), the Office of Environmental Restoration (EM-40) of the Department of Energy (DOE), and the Nuclear Regulatory Agency (NRC), distribution coefficient (K d ) values are being compiled from the literature to develop provisional tables for cadmium, cesium, chromium, lead, plutonium, strontium, thorium, and uranium. The tables are organized according to important aqueous- and solid-phase parameters affecting the sorption of these contaminants. These parameters, which vary with contaminant, include pH and redox conditions; cation exchange capacity (CEC); presence of iron-oxide, aluminum-oxide, clay, and mica minerals; organic matter content; and solution concentrations of contaminants, competing ions, and complexing ligands. Sorption information compiled for strontium is used to illustrate our approach. The strontium data show how selected geochemical parameters (i.e., CEC, pH, and clay content) affect Strontium K d values and the selection of open-quote default close-quote K d values needed for modeling contaminant transport and risks at sites for which site specific data are lacking. Results of our evaluation may be used by site management and technical staff to assess contaminant fate, migration, and risk calculations in support of site remediation and waste management decisions
Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.
2016-09-01
The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.
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.
Guzman, F; Errea, L F; Illescas, Clara; Mendez, L; Pons, B
2010-01-01
Classical and semiclassical calculations of nl-resolved charge exchange cross sections in B 5 + collisions with H(n i ) are performed to compute effective emission coefficients for the n = 7 → n = 6 transition in B 4 + for plasma conditions typical of the ASDEX-U tokamak. For n i = 1, the value of the emission coefficient is larger than that obtained from ADAS database by a factor of 2 at energies of 10 keV amu -1 , but no differences are found at energies above 50 keV amu -1 . For n i = 2, our calculation yields emission coefficients close to those derived from ADAS data from low to high impact energies. The emission coefficients corresponding to B 5 + + H(n i = 3) collisions are of the same order of magnitude as those for n i = 2.
Dose Rate Calculations for Rotary Mode Core Sampling Exhauster
Foust, D J
2000-01-01
This document provides the calculated estimated dose rates for three external locations on the Rotary Mode Core Sampling (RMCS) exhauster HEPA filter housing, per the request of Characterization Field Engineering.
Dose Rate Calculations for Rotary Mode Core Sampling Exhauster
FOUST, D.J.
2000-01-01
This document provides the calculated estimated dose rates for three external locations on the Rotary Mode Core Sampling (RMCS) exhauster HEPA filter housing, per the request of Characterization Field Engineering
Calculating stocking rates for game ranches: substitution ratios for ...
Calculating stocking rates for game ranches: substitution ratios for use in the Mopani ... Reports on a study conducted to quantify the overlap in ungulate resource-use on a game ranch, and to demonstrate how ... AJOL African Journals Online.
Mitroy, J.; Bromley, M.W.J.
2003-01-01
The van der Waals coefficients, C 6 , C 8 , and C 10 for the alkali-metal (Li, Na, K, and Rb) and alkaline-earth-metal (Be, Mg, Ca, and Sr) atoms are estimated by a combination of ab initio and semiempirical methods. Polarizabilities and atom-wall coefficients are given as a diagnostic check, and the lowest order nonadiabatic dispersion coefficient, D 8 and the three-body coefficient, C 9 are also presented. The dispersion coefficients are in agreement with the available relativistic many-body perturbation theory calculations. The contribution from the core was included by using constrained sum rules involving the core polarizability and Hartree-Fock expectation values to estimate the f-value distribution
Correlated linear response calculations of the C6 dispersion coefficients of hydrogen halides
Sauer, S. P. A.; Paidarová, Ivana
2007-01-01
Roč. 3, 2-4 (2007), s. 399-421 ISSN 1574-0404 R&D Projects: GA AV ČR IAA401870702 Institutional research plan: CEZ:AV0Z40400503 Keywords : hydrogen halides * C6 dospersion coefficients * van der Waals coefficients * polarizability at imaginary frequences * SOPPA Subject RIV: CF - Physical ; Theoretical Chemistry
Chung, Hoi Sung; Gopich, Irina V; McHale, Kevin; Cellmer, Troy; Louis, John M; Eaton, William A
2011-04-28
Recently developed statistical methods by Gopich and Szabo were used to extract folding and unfolding rate coefficients from single-molecule Förster resonance energy transfer (FRET) data for proteins with kinetics too fast to measure waiting time distributions. Two types of experiments and two different analyses were performed. In one experiment bursts of photons were collected from donor and acceptor fluorophores attached to a 73-residue protein, α(3)D, freely diffusing through the illuminated volume of a confocal microscope system. In the second, the protein was immobilized by linkage to a surface, and photons were collected until one of the fluorophores bleached. Folding and unfolding rate coefficients and mean FRET efficiencies for the folded and unfolded subpopulations were obtained from a photon by photon analysis of the trajectories using a maximum likelihood method. The ability of the method to describe the data in terms of a two-state model was checked by recoloring the photon trajectories with the extracted parameters and comparing the calculated FRET efficiency histograms with the measured histograms. The sum of the rate coefficients for the two-state model agreed to within 30% with the relaxation rate obtained from the decay of the donor-acceptor cross-correlation function, confirming the high accuracy of the method. Interestingly, apparently reliable rate coefficients could be extracted using the maximum likelihood method, even at low (rate coefficients and mean FRET efficiencies were also obtained in an approximate procedure by simply fitting the FRET efficiency histograms, calculated by binning the donor and acceptor photons, with a sum of three-Gaussian functions. The kinetics are exposed in these histograms by the growth of a FRET efficiency peak at values intermediate between the folded and unfolded peaks as the bin size increases, a phenomenon with similarities to NMR exchange broadening. When comparable populations of folded and unfolded
Yang Hongwei; Nanjing Agricultural Univ., Nanjing; Chen Rushan; Zhang Yun
2006-01-01
The dielectric property of dispersive media is written as rational polynomial function, the relation between D and E is derived in time domain. It is named shift operator FDTD (SO-FDTD) method. The high accuracy and efficiency of this method is confirmed by computing the reflection coefficients of electromagnetic waves by a collisional plasma slab. The reflection coefficients between plasma and the atmosphere or vacuum can be calculated by using the SO-FDTD method. The result is that the reflection coefficients are affected by plasma thickness, electron numerical density, the distributing orderliness of electron density, and incidence wave frequency. (authors)
Ablinger, J.; Hasselhuhn, A.; Schneider, C. [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation (RISC); Behring, A.; Bluemlein, J.; Freitas, A. de; Raab, C.; Round, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Manteuffel, A. von [Mainz Univ. (Germany). PRISMA Cluster of Excellence; Wissbrock, F. [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation (RISC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); IHES Institut des Hautes Etudes Scientifiques, Bures-sur-Yvette (France)
2014-07-15
We report on our latest results in the calculation of the three-loop heavy flavor contributions to the Wilson coefficients in deep-inelastic scattering in the asymptotic region Q{sup 2}>>m{sup 2}. We discuss the different methods used to compute the required operator matrix elements and the corresponding Feynman integrals. These methods very recently allowed us to obtain a series of new operator matrix elements and Wilson coefficients like the flavor non-singlet and pure singlet Wilson coefficients.
Baptista Filho, B.D.; Konuk, A.A.
1981-01-01
A new method to calculate pressure drop (Δp) and shell-side heat transfer coefficient (h sub(c)) in a shell-and-tube heat exchanger with segmental baffles is presented. The method is based on the solution of the equations of conservation of mass and momentum between two baffles. The calculated distributions of pressure and velocities given respectively, Δp and h sub(c). The values of Δp and h sub(c) are correlated for a given geometry whit the shell side fluid properties and flow rate. The calculated and experimental results agree very well for a U-Tube heat exchanger. (Author) [pt
Zawawi, N. N. M.; Azmi, W. H.; Redhwan, A. A. M.; Sharif, M. Z.
2017-10-01
Wear of sliding parts and operational machine consistency enhancement can be avoided with good lubrication. Lubrication reduce wear between two contacting and sliding surfaces and decrease the frictional power losses in compressor. The coefficient of friction and wear rate effects study were carried out to measure the friction and anti-wear abilities of Al2O3-SiO2 composite nanolubricants a new type of compressor lubricant to enhanced the compressor performances. The tribology test rig employing reciprocating test conditions to replicate a piston ring contact in the compressor was used to measure the coefficient of friction and wear rate. Coefficient of friction and wear rate effects of different Al2O3-SiO2/PAG composite nanolubricants of Aluminium 2024 plate for 10-kg load at different speed were investigated. Al2O3 and SiO2 nanoparticles were dispersed in the Polyalkylene Glycol (PAG 46) lubricant using two-steps method of preparation. The result shows that the coefficient friction and wear rate of composite nanolubricants decreased compared to pure lubricant. The maximum reduction achievement for friction of coefficient and wear rate by Al2O3-SiO2 composite nanolubricants by 4.78% and 12.96% with 0.06% volume concentration. Therefore, 0.06% volume concentration is selected as the most enhanced composite nanolubricants with effective coefficient of friction and wear rate reduction compared to other volume concentrations. Thus, it is recommended to be used as the compressor lubrication to enhanced compressor performances.
Lopes, J.; De Medeiros, M. P.; Garcez, R.; Filgueiras, R.; Thalhofer, J.; Da Silva, A. X. [Universidade Federal do Rio de Janeiro, Programa de Engenharia Nuclear, Av. Horacio Macedo 2030, 21945-970 Rio de Janeiro (Brazil); Freitas R, W., E-mail: marqueslopez@yahoo.com.br [Instituto Militar de Engenharia, Secao de Engenharia Nuclear, Praca Gen. Tiburcio 80, 22290-270 Urca, Rio de Janeiro (Brazil)
2017-10-15
In spectrometry, the self-attenuation coefficients are fundamental to correct the efficiency of the detection of samples whose density is different from the radioactive standard. To facilitate the procedure of coefficient calculation, mathematical simulations have been widespread as a tool. In this paper, LabSOCS was used to calculate the self-attenuation coefficients for some geometries and the values found were compared to those obtained with MCNPX and experimental values. The percentage deviations found for the self-attenuation coefficient calculated by LabSOCS were below 1.6%, when compared to experimental values. In the extrapolation zone of the fitting curve of the experimental model, the deviations were below 1.9%. The results obtained show that the deviations increase proportionally to the amplitude between the density values of the radioactive standard and the sample. High percentage deviations were also obtained in simulations whose samples had high densities, complex geometries and low energy levels. However, the results indicate that LabSOCS is a tool which may be used in the calculation of self-attenuation coefficients. (Author)
Korun, M.; Vodenik, B.; Zorko, B.
2016-01-01
Two simple methods for calculating the correlations between peaks appearing in gamma-ray spectra are described. We show how the areas are correlated when the peaks do not overlap, but the spectral regions used for the calculation of the background below the peaks do. When the peaks overlap, the correlation can be stronger than in the case of the non-overlapping peaks. The methods presented are simplified to the extent of allowing their implementation with manual calculations. They are intended for practitioners as additional tools to be used when the correlations between the areas of the peaks in the gamma-ray spectra are to be calculated. Also, the correlation coefficient between the number of counts in the peak and the number of counts in the continuous background below the peak is derived. - Highlights: • The correlation coefficients between areas of closely spaced peaks are assessed. • For isolated peaks the correlation arises from the common continuous background. • If peaks overlap the correlation coefficient depends on how much they overlap. • If peaks overlap also the background height affects the correlation coefficient. • The correlation coefficient between the peak area and its background is −1.
Reva, T.D.; Semenov, A.M.
1984-01-01
Statistically significant estimations of the second, third and fourth group integrals of sodium and potassium vapors were obtained in the framework of the initial atom method on the basis of semiempirical equation of state derived by the authors. Possibility is duscussed of estimating dimer, trimer and tetramer concentrations from these data with account of unideality of vapors. High rate of convergence of density and pressure group expansion is demonstrated. Virial coefficients were calculated. It is shown that virial expansions of thermodynamic functions diverge at elevated densities of the gases under study. The estimations of senior virial coefficients of sodium and potassium vapors available in literature were proved to be faulty
Determination of the N2 recombination rate coefficient in the ionosphere
Orsini, N.; Torr, D. G.; Brinton, H. C.; Brace, L. H.; Hanson, W. B.; Hoffman, J. H.; Nier, A. O.
1977-01-01
Measurements of aeronomic parameters made by the Atmosphere Explorer-C satellite are used to determine the recombination rate coefficient of N2(+) in the ionosphere. The rate is found to increase significantly with decreasing electron density. Values obtained range from approximately 1.4 x 10 to the -7th to 3.8 x 10 to the -7th cu cm/sec. This variation is explained in a preliminary way in terms of an increase in the rate coefficient with vibrational excitation. Thus, high electron densities depopulate high vibrational levels reducing the effective recombination rate, whereas, low electron densities result in an enhancement in the population of high vibrational levels, thus, increasing the effective recombination rate.
Benmansour, L.
1992-01-01
The present work shows a group of results, obtained by a neutronic study, concerning the TRIGA MARK II reactor and LIGHT WATER reactors. These studies aim to make cell and diffusion calculations. WIMS D-4 with extended library and DIXY programs are used and tested for those purposes. We also have proceeded to a qualification of WIMS code based on the fuel temperature coefficient calculations. 33 refs.; 23 figs.; 30 tabs. (author)
Benoist, P [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1959-07-01
The calculation of diffusion coefficients in a lattice necessitates the knowledge of a correct method of weighting the free paths of the different constituents. An unambiguous definition of this weighting method is given here, based on the calculation of leakages from a zone of a reactor. The formulation obtained, which is both simple and general, reduces the calculation of diffusion coefficients to that of collision probabilities in the different media; it reveals in the expression for the radial coefficient the series of the terms of angular correlation (cross terms) recently shown by several authors. This formulation is then used to calculate the practical case of a classical type of lattice composed of a moderator and a fuel element surrounded by an empty space. Analytical and numerical comparison of the expressions obtained with those inferred from the theory of BEHRENS shows up the importance of several new terms some of which are linked with the transparency of the fuel element. Cross terms up to the second order are evaluated. A practical formulary is given at the end of the paper. (author) [French] Le calcul des coefficients de diffusion dans un reseau suppose la connaissance d'un mode de ponderation correct des libres parcours des differents constituants. On definit ici sans ambiguite ce mode de ponderation a partir du calcul des fuites hors d'une zone de reacteur. La formulation obtenue, simple et generale, ramene le calcul des coefficients de diffusion a celui des probabilites de collision dans les differents milieux; elle fait apparaitre dans l'expression du coefficient radial la serie des termes de correlation angulaire (termes rectangles), mis en evidence recemment par plusieurs auteurs. Cette formulation est ensuite appliquee au calcul pratique d'un reseau classique, compose d'un moderateur et d'un element combustible entoure d'une cavite; la comparaison analytique et numerique des expressions obtenues avec celles deduites de la theorie de BEHRENS
Rate coefficients for low-energy electron dissociative attachment to molecular hydrogen
Horacek, J.; Houfek, K.; Cizek, M.; Murakami, I.; Kato, T.
2003-02-01
Calculation of rate constants for dissociative electron attachment to molecular hydrogen is reported. The calculation is based on an improved nonlocal resonance model of Cizek, Horacek and Domcke which takes fully into account the nonlocality of the resonance dynamics and uses potentials with correct asymptotic forms. The rate constants are calculated for all quantum numbers v and J of the target molecules and for electron temperature in the range 0-30000 K. (author)
Experiences with leak rate calculations methods for LBB application
Grebner, H.; Kastner, W.; Hoefler, A.; Maussner, G.
1997-01-01
In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations
Experiences with leak rate calculations methods for LBB application
Grebner, H.; Kastner, W.; Hoefler, A.; Maussner, G. [and others
1997-04-01
In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations.
Endo, Akira
2017-07-01
Fluence-to-effective dose conversion coefficients have been calculated for photons, neutrons, electrons, positrons, protons, muons, pions and helium ions for various incident angles of radiations. The aim of this calculation is to provide a set of conversion coefficients to the Report Committee 26 (RC26) of the International Commission on Radiation Units and Measurements (ICRU) for use in defining personal dose equivalent for individual monitoring. The data sets comprise effective dose conversion coefficients for incident angles of radiations from 0° to ±90° in steps of 15° and at ±180°. Conversion coefficients for rotational, isotropic, superior hemisphere semi-isotropic and inferior hemisphere semi-isotropic irradiations are also included. Numerical data of the conversion coefficients are presented as supplementary data. The conversion coefficients are used to define the personal dose equivalent, which is being considered by the ICRU RC26, as the operational quantity for individual monitoring. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Haggerty, R.; Schroth, M.H.; Istok, J.D.
1998-01-01
The single-well, ''''push-pull'''' test method is useful for obtaining information on a wide variety of aquifer physical, chemical, and microbiological characteristics. A push-pull test consists of the pulse-type injection of a prepared test solution into a single monitoring well followed by the extraction of the test solution/ground water mixture from the same well. The test solution contains a conservative tracer and one or more reactants selected to investigate a particular process. During the extraction phase, the concentrations of tracer, reactants, and possible reaction products are measured to obtain breakthrough curves for all solutes. This paper presents a simplified method of data analysis that can be used to estimate a first-order reaction rate coefficient from these breakthrough curves. Rate coefficients are obtained by fitting a regression line to a plot of normalized concentrations versus elapsed time, requiring no knowledge of aquifer porosity, dispersivity, or hydraulic conductivity. A semi-analytical solution to the advective-dispersion equation is derived and used in a sensitivity analysis to evaluate the ability of the simplified method to estimate reaction rate coefficients in simulated push-pull tests in a homogeneous, confined aquifer with a fully-penetrating injection/extraction well and varying porosity, dispersivity, test duration, and reaction rate. A numerical flow and transport code (SUTRA) is used to evaluate the ability of the simplified method to estimate reaction rate coefficients in simulated push-pull tests in a heterogeneous, unconfined aquifer with a partially penetrating well. In all cases the simplified method provides accurate estimates of reaction rate coefficients; estimation errors ranged from 0.1 to 8.9% with most errors less than 5%
Petrignani, A.; Zande, W.J. van der; Cosby, P.C.; Hellberg, F.; Thomas, R.; Larsson, M.
2005-01-01
We have studied the dissociative recombination of the first three vibrational levels of O-2(+) in its electronic ground X (2)Pi(g) state. Absolute rate coefficients, cross sections, quantum yields and branching fractions have been determined in a merged-beam experiment in the heavy-ion storage ring,
Rate coefficients of open shell molecules and radicals: R-matrix ...
2017-04-07
Apr 7, 2017 ... Rate coefficients of open shell molecules and radicals: R-matrix method. JASMEET SINGH1 ... lasers, study of structure of DNA and astrophysics which require a ..... [6] CCPForge, http://ccpforge.cse.rl.ac.uk/projects/ukrmol-in/.
Direct access to dithiobenzoate RAFT agent fragmentation rate coefficients by ESR spin-trapping.
Ranieri, Kayte; Delaittre, Guillaume; Barner-Kowollik, Christopher; Junkers, Thomas
2014-12-01
The β-scission rate coefficient of tert-butyl radicals fragmenting off the intermediate resulting from their addition to tert-butyl dithiobenzoate-a reversible addition-fragmentation chain transfer (RAFT) agent-is estimated via the recently introduced electron spin resonance (ESR)-trapping methodology as a function of temperature. The newly introduced ESR-trapping methodology is critically evaluated and found to be reliable. At 20 °C, a fragmentation rate coefficient of close to 0.042 s(-1) is observed, whereas the activation parameters for the fragmentation reaction-determined for the first time-read EA = 82 ± 13.3 kJ mol(-1) and A = (1.4 ± 0.25) × 10(13) s(-1) . The ESR spin-trapping methodology thus efficiently probes the stability of the RAFT adduct radical under conditions relevant for the pre-equilibrium of the RAFT process. It particularly indicates that stable RAFT adduct radicals are indeed formed in early stages of the RAFT poly-merization, at least when dithiobenzoates are employed as controlling agents as stipulated by the so-called slow fragmentation theory. By design of the methodology, the obtained fragmentation rate coefficients represent an upper limit. The ESR spin-trapping methodology is thus seen as a suitable tool for evaluating the fragmentation rate coefficients of a wide range of RAFT adduct radicals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Hintz, Paul A.; Ervin, Kent M.
1994-04-01
Reactions of Ni-n(n=3-10), Pd-n(n=3-8), and Pt-n(n=3-7) with CO are studied in a flow tube reactor. Bimolecular rate coefficients are measured for the association reaction of CO adsorbing on the cluster surface. The rate coefficients range from about 10% of the collision rate for the trimer anions to near the collision rate for clusters larger than four atoms. The maximum number of CO molecules that bind to each cluster is determined. Whereas the saturation limits for nickel are typical for an 18 electron transition metal, the limits for platinum are lower, reflecting the electron deficient structures observed in condensed phase chemistry. The CO saturated palladium clusters represent the first examples of saturated binary palladium carbonyl compounds. Comparisons are made to similar studies on metal cation and neutral clusters and also to surface scattering studies of nickel group metals.
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.
Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C; Joyce, Kevin P; Kovalenko, Andriy
2016-11-01
Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing ([Formula: see text] for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining [Formula: see text] compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to [Formula: see text]. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple [Formula: see text] correction improved agreement with experiment from [Formula: see text] to [Formula: see text], despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.
Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C.; Joyce, Kevin P.; Kovalenko, Andriy
2016-11-01
Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing (R=0.98 for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining R=0.73 compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to R=0.93. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple pK_{ {a}} correction improved agreement with experiment from R=0.54 to R=0.66, despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.
Dense fluid self-diffusion coefficient calculations using perturbation theory and molecular dynamics
COELHO L. A. F.
1999-01-01
Full Text Available A procedure to correlate self-diffusion coefficients in dense fluids by using the perturbation theory (WCA coupled with the smooth-hard-sphere theory is presented and tested against molecular simulations and experimental data. This simple algebraic expression correlates well the self-diffusion coefficients of carbon dioxide, ethane, propane, ethylene, and sulfur hexafluoride. We have also performed canonical ensemble molecular dynamics simulations by using the Hoover-Nosé thermostat and the mean-square displacement formula to compute self-diffusion coefficients for the reference WCA intermolecular potential. The good agreement obtained from both methods, when compared with experimental data, suggests that the smooth-effective-sphere theory is a useful procedure to correlate diffusivity of pure substances.
Methods for calculating dose conversion coefficients for terrestrial and aquatic biota
Ulanovsky, A.; Proehl, G.; Gomez-Ros, J.M.
2008-01-01
Plants and animals may be exposed to ionizing radiation from radionuclides in the environment. This paper describes the underlying data and assumptions to assess doses to biota due to internal and external exposure for a wide range of masses and shapes living in various habitats. A dosimetric module is implemented which is a user-friendly and flexible possibility to assess dose conversion coefficients for aquatic and terrestrial biota. The dose conversion coefficients have been derived for internal and various external exposure scenarios. The dosimetric model is linked to radionuclide decay and emission database, compatible with the ICRP Publication 38, thus providing a capability to compute dose conversion coefficients for any nuclide from the database and its daughter nuclides. The dosimetric module has been integrated into the ERICA Tool, but it can also be used as a stand-alone version
Calculation of gamma ray exposure rates from uranium ore bodies
Thomson, J.E.; Wilson, O.J.
1980-02-01
The planning of operations associated with uranium mines often requires that estimates be made of the exposure rates from various ore bodies. A straight-forward method of calculating the exposure rate from an arbitrarily shaped body is presented. Parameters for the calculation are evaluated under the assumption of secular equilibrium of uranium with its daughters and that the uranium is uniformly distributed throughout an average soil mixture. The spectral distribution of the emitted gamma rays and the effect of air attenuation are discussed. Worked examples are given of typical situations encountered in uranium mines
A comparison of measured and calculated values of air kerma rates from 137Cs in soil
V. P. Ramzaev
2015-01-01
Full Text Available In 2010, a study was conducted to determine the air gamma dose rate from 137Cs deposited in soil. The gamma dose rate measurements and soil sampling were performed at 30 reference plots from the south-west districts of the Bryansk region (Russia that had been heavily contaminated as a result of the Chernobyl accident. The 137Cs inventory in the top 20 cm of soil ranged from 260 kBq m–2 to 2800 kBq m–2. Vertical distributions of 137Cs in soil cores (6 samples per a plot were determined after their sectioning into ten horizontal layers of 2 cm thickness. The vertical distributions of 137Cs in soil were employed to calculate air kerma rates, K, using two independent methods proposed by Saito and Jacob [Radiat. Prot. Dosimetry, 1995, Vol. 58, P. 29–45] and Golikov et al. [Contaminated Forests– Recent Developments in Risk Identification and Future Perspective. Kluwer Academic Publishers, 1999. – P. 333–341]. A very good coincidence between the methods was observed (Spearman’s rank coefficient of correlation = 0.952; P<0.01; on average, a difference between the kerma rates calculated with two methods did not exceed 3%. The calculated air kerma rates agreed with the measured dose rates in air very well (Spearman’s coefficient of correlation = 0.952; P<0.01. For large grassland plots (n=19, the measured dose rates were on average 6% less than the calculated kerma rates. The tested methods for calculating the air dose rate from 137Cs in soil can be recommended for practical studies in radiology and radioecology.
Simmer, Gregor
2012-04-11
Due to secondary cosmic radiation (SCR), pilots and flight attendants receive elevated effective doses at flight altitudes. For this reason, since 2003 aircrew members are considered as occupationally exposed, in Germany. This work deals with the calculation of dose conversion coefficients (DCC) for protons, neutrons, electrons, positrons, photons and myons, which are crucial for estimation of effective dose from SCR. For the first time, calculations were performed combining Geant4 - a Monte Carlo code developed at CERN - with the voxel phantoms for the reference female and male published in 2008 by ICRP and ICRU. Furthermore, measurements of neutron fluence spectra - which contribute the major part to the effective dose of SCR - were carried out at the Environmental Research Station Schneefernerhaus (UFS) located at 2650 m above sea level nearby the Zugspitze mountain, Germany. These measured neutron spectra, and additionally available calculated spectra, were then folded with the DCC calculated in this work, and effective dose rates for different heights were calculated.
Li, Jun; Guo, Hua
2018-03-15
Thermal rate coefficients for the title reaction and its various isotopologues are computed using a tunneling-corrected transition-state theory on a global potential energy surface recently developed by fitting a large number of high-level ab initio points. The calculated rate coefficients are found to agree well with the measured ones in a wide temperature range, validating the accuracy of the potential energy surface. Strong non-Arrhenius effects are found at low temperatures. In addition, the calculations reproduced the primary and secondary kinetic isotope effects. These results confirm the strong influence of tunneling to this heavy-light-heavy hydrogen abstraction reaction.
Miller, R. D.; Anderson, L. R.
1979-01-01
The LOADS program L218, a digital computer program that calculates dynamic load coefficient matrices utilizing the force summation method, is described. The load equations are derived for a flight vehicle in straight and level flight and excited by gusts and/or control motions. In addition, sensor equations are calculated for use with an active control system. The load coefficient matrices are calculated for the following types of loads: translational and rotational accelerations, velocities, and displacements; panel aerodynamic forces; net panel forces; shears and moments. Program usage and a brief description of the analysis used are presented. A description of the design and structure of the program to aid those who will maintain and/or modify the program in the future is included.
Impact ionisation rate calculations in wide band gap semiconductors
Harrison, D.
1998-09-01
Calculations of band-to-band impact ionisation rates performed in the semi-classical Fermi's Golden Rule approximation are presented here for the semiconductors GaAs, In 0.53 Ga 0.47 As and Si 0.5 Ge 0.5 at 300K. The crystal band structure is calculated using the empirical pseudopotential method. To increase the speed with which band structure data at arbitrary k-vectors can be obtained, an interpolation scheme has been developed. Energies are quadratically interpolated on adapted meshes designed to ensure accuracy is uniform throughout the Brillouin zone, and pseudowavefunctions are quadratically interpolated on a regular mesh. Matrix elements are calculated from the pseudowavefunctions, and include the terms commonly neglected in calculations for narrow band gap materials and an isotropic approximation to the full wavevector and frequency dependent dielectric function. The numerical integration of the rate over all distinct energy and wavevector conserving transitions is performed using two different algorithms. Results from each are compared and found to be in good agreement, indicating that the algorithms are reliable. The rates for electrons and holes in each material are calculated as functions of the k-vector of the impacting carriers, and found to be highly anisotropic. Average rates for impacting carriers at a given energy are calculated and fitted to Keldysh-type expressions with higher than quadratic dependence of the rate on energy above threshold being obtained in all cases. The average rates calculated here are compared to results obtained by other workers, with reasonable agreement being obtained for GaAs, and poorer agreement obtained for InGaAs and SiGe. Possible reasons for the disagreement are investigated. The impact ionisation thresholds are examined and k-space and energy distributions of generated carriers are determined. The role of threshold anisotropy, variation in the matrix elements and the shape of the bands in determining
The calculation of dose rates from rectangular sources
Hartley, B.M.
1998-01-01
A common problem in radiation protection is the calculation of dose rates from extended sources and irregular shapes. Dose rates are proportional to the solid angle subtended by the source at the point of measurement. Simple methods of calculating solid angles would assist in estimating dose rates from large area sources and therefore improve predictive dose estimates when planning work near such sources. The estimation of dose rates is of particular interest to producers of radioactive ores but other users of bulk radioactive materials may have similar interest. The use of spherical trigonometry can assist in determination of solid angles and a simple equation is derived here for the determination of the dose at any distance from a rectangular surface. The solid angle subtended by complex shapes can be determined by modelling the area as a patchwork of rectangular areas and summing the solid angles from each rectangle. The dose rates from bags of thorium bearing ores is of particular interest in Western Australia and measured dose rates from bags and containers of monazite are compared with theoretical estimates based on calculations of solid angle. The agreement is fair but more detailed measurements would be needed to confirm the agreement with theory. (author)
Zarubin, Dmitri P., E-mail: dmitri.zarubin@mtu-net.ru [Department of Physical and Collod Chemistry, Moscow State University of Technology and Management, 73 Zemlyanoi Val, Moscow 109803 (Russian Federation)
2011-08-15
Highlights: > Problem of ionic activity coefficients, determined by potentiometry, is reconsidered. > They are found to be functions of mean activity coefficients and transport numbers of ions. > The finding is verified by calculations and comparing the results with reported data. > Calculations are performed for systems with single electrolytes and binary mixtures. - Abstract: Potentiometric measurements on cells with liquid junctions are sometimes used for calculations of single-ion activity coefficients in electrolyte solutions, the incidence of this being increased recently. As surmised by Guggenheim in the 1930s, such coefficients (of ions i), {gamma}{sub i}, are actually complicated functions of mean ionic activity coefficients, {gamma}{sub {+-}}, and transport numbers of ions, t{sub i}. In the present paper specific functions {gamma}{sub i}({gamma}{sub {+-}}, t{sub i}) are derived for a number of cell types with an arbitrary mixture of strong electrolytes in a one-component solvent in the liquid-junction system. The cell types include cells with (i) identical electrodes, (ii) dissimilar electrodes reversible to the same ions, (iii) dissimilar electrodes reversible to ions of opposite charge signs, (iv) dissimilar electrodes reversible to different ions of the same charge sign, and (v) identical reference electrodes and an ion-selective membrane permeable to ions of only one type. Pairs of functions for oppositely charged ions are found to be consistent with the mean ionic activity coefficients as would be expected for pairs of the proper {gamma}{sub i} quantities by definition of {gamma}{sub {+-}}. The functions are tested numerically on some of the reported {gamma}{sub i} datasets that are the more tractable. A generally good agreement is found with data reported for cells with single electrolytes HCl and KCl in solutions, and with binary mixtures in the liquid-junction systems of KCl from the reference solutions and NaCl and HCl from the test solutions. It
Sloth, Peter
1993-01-01
The grand canonical ensemble has been used to study the evaluation of single ion activity coefficients in homogeneous ionic fluids. In this work, the Coulombic interactions are truncated according to the minimum image approximation, and the ions are assumed to be placed in a structureless......, homogeneous dielectric continuum. Grand canonical ensemble Monte Carlo calculation results for two primitive model electrolyte solutions are presented. Also, a formula involving the second moments of the total correlation functions is derived from fluctuation theory, which applies for the derivatives...... of the individual ionic activity coefficients with respect to the total ionic concentration. This formula has previously been proposed on the basis of somewhat different considerations....
Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli
2017-03-21
The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm -2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an
Transitions in genetic toggle switches driven by dynamic disorder in rate coefficients
Chen, Hang; Thill, Peter; Cao, Jianshu
2016-01-01
In biochemical systems, intrinsic noise may drive the system switch from one stable state to another. We investigate how kinetic switching between stable states in a bistable network is influenced by dynamic disorder, i.e., fluctuations in the rate coefficients. Using the geometric minimum action method, we first investigate the optimal transition paths and the corresponding minimum actions based on a genetic toggle switch model in which reaction coefficients draw from a discrete probability distribution. For the continuous probability distribution of the rate coefficient, we then consider two models of dynamic disorder in which reaction coefficients undergo different stochastic processes with the same stationary distribution. In one, the kinetic parameters follow a discrete Markov process and in the other they follow continuous Langevin dynamics. We find that regulation of the parameters modulating the dynamic disorder, as has been demonstrated to occur through allosteric control in bistable networks in the immune system, can be crucial in shaping the statistics of optimal transition paths, transition probabilities, and the stationary probability distribution of the network.
Transitions in genetic toggle switches driven by dynamic disorder in rate coefficients
Chen, Hang, E-mail: hangchen@mit.edu; Thill, Peter; Cao, Jianshu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2016-05-07
In biochemical systems, intrinsic noise may drive the system switch from one stable state to another. We investigate how kinetic switching between stable states in a bistable network is influenced by dynamic disorder, i.e., fluctuations in the rate coefficients. Using the geometric minimum action method, we first investigate the optimal transition paths and the corresponding minimum actions based on a genetic toggle switch model in which reaction coefficients draw from a discrete probability distribution. For the continuous probability distribution of the rate coefficient, we then consider two models of dynamic disorder in which reaction coefficients undergo different stochastic processes with the same stationary distribution. In one, the kinetic parameters follow a discrete Markov process and in the other they follow continuous Langevin dynamics. We find that regulation of the parameters modulating the dynamic disorder, as has been demonstrated to occur through allosteric control in bistable networks in the immune system, can be crucial in shaping the statistics of optimal transition paths, transition probabilities, and the stationary probability distribution of the network.
Toropov, A A; Toropova, A P; Raska, I
2008-04-01
Simplified molecular input line entry system (SMILES) has been utilized in constructing quantitative structure-property relationships (QSPR) for octanol/water partition coefficient of vitamins and organic compounds of different classes by optimal descriptors. Statistical characteristics of the best model (vitamins) are the following: n=17, R(2)=0.9841, s=0.634, F=931 (training set); n=7, R(2)=0.9928, s=0.773, F=690 (test set). Using this approach for modeling octanol/water partition coefficient for a set of organic compounds gives a model that is statistically characterized by n=69, R(2)=0.9872, s=0.156, F=5184 (training set) and n=70, R(2)=0.9841, s=0.179, F=4195 (test set).
Theoretical calculations of the self-reflection coefficients for some species of ions
Luo, Z.M. E-mail: luozm@scu.edu.cn; Gou, C.; Hou, Q
2002-06-01
The bipartition model of ion transport has been applied to study the self-reflection coefficients of some species of ion beams which are normally incident to a surface. The computational results has been compared with the results taken from Eckstein and Biersack and the compilation data given by Thomas, Janev and Smith. It was found that there are in reasonable agreement between the results given by the bipartition model and the results given by Monte Carlo method.
Villain, P.; Beauchamp, P.; Badawi, K.F.; Goudeau, P.; Renault, P.-O.
2004-01-01
Equilibrium state and elastic coefficients of nanometre-sized single crystal tungsten layers and wires are investigated by atomistic simulations. The variations of the equilibrium distances as a function of the layer thickness or wire cross-section are mainly due to elastic effects of surface tension forces. A strong decrease of the Young's modulus is observed when the transverse dimensions are reduced below 2-3 nm
Al Zain, Jamal; El Hajjaji, O.; El Bardouni, T.; Boukhal, H.; Jaï, Otman
2018-06-01
The MNSR is a pool type research reactor, which is difficult to model because of the importance of neutron leakage. The aim of this study is to evaluate a 2-D transport model for the reactor compatible with the latest release of the DRAGON code and 3-D diffusion of the DONJON code. DRAGON code is then used to generate the group macroscopic cross sections needed for full core diffusion calculations. The diffusion DONJON code, is then used to compute the effective multiplication factor (keff), the feedback reactivity coefficients and neutron flux which account for variation in fuel and moderator temperatures as well as the void coefficient have been calculated using the DRAGON and DONJON codes for the MNSR research reactor. The cross sections of all the reactor components at different temperatures were generated using the DRAGON code. These group constants were used then in the DONJON code to calculate the multiplication factor and the neutron spectrum at different water and fuel temperatures using 69 energy groups. Only one parameter was changed where all other parameters were kept constant. Finally, Good agreements between the calculated and measured have been obtained for every of the feedback reactivity coefficients and neutron flux.
Calculation method for gamma dose rates from Gaussian puffs
Thykier-Nielsen, S; Deme, S; Lang, E
1995-06-01
The Lagrangian puff models are widely used for calculation of the dispersion of releases to the atmosphere. Basic output from such models is concentration of material in the air and on the ground. The most simple method for calculation of the gamma dose from the concentration of airborne activity is based on the semi-infinite cloud model. This method is however only applicable for puffs with large dispersion parameters, i.e. for receptors far away from the release point. The exact calculation of the cloud dose using volume integral requires large computer time usually exceeding what is available for real time calculations. The volume integral for gamma doses could be approximated by using the semi-infinite cloud model combined with correction factors. This type of calculation procedure is very fast, but usually the accuracy is poor because only a few of the relevant parameters are considered. A multi-parameter method for calculation of gamma doses is described here. This method uses precalculated values of the gamma dose rates as a function of E{sub {gamma}}, {sigma}{sub y}, the asymmetry factor - {sigma}{sub y}/{sigma}{sub z}, the height of puff center - H and the distance from puff center R{sub xy}. To accelerate the calculations the release energy, for each significant radionuclide in each energy group, has been calculated and tabulated. Based on the precalculated values and suitable interpolation procedure the calculation of gamma doses needs only short computing time and it is almost independent of the number of radionuclides considered. (au) 2 tabs., 15 ills., 12 refs.
Calculation method for gamma dose rates from Gaussian puffs
Thykier-Nielsen, S.; Deme, S.; Lang, E.
1995-06-01
The Lagrangian puff models are widely used for calculation of the dispersion of releases to the atmosphere. Basic output from such models is concentration of material in the air and on the ground. The most simple method for calculation of the gamma dose from the concentration of airborne activity is based on the semi-infinite cloud model. This method is however only applicable for puffs with large dispersion parameters, i.e. for receptors far away from the release point. The exact calculation of the cloud dose using volume integral requires large computer time usually exceeding what is available for real time calculations. The volume integral for gamma doses could be approximated by using the semi-infinite cloud model combined with correction factors. This type of calculation procedure is very fast, but usually the accuracy is poor because only a few of the relevant parameters are considered. A multi-parameter method for calculation of gamma doses is described here. This method uses precalculated values of the gamma dose rates as a function of E γ , σ y , the asymmetry factor - σ y /σ z , the height of puff center - H and the distance from puff center R xy . To accelerate the calculations the release energy, for each significant radionuclide in each energy group, has been calculated and tabulated. Based on the precalculated values and suitable interpolation procedure the calculation of gamma doses needs only short computing time and it is almost independent of the number of radionuclides considered. (au) 2 tabs., 15 ills., 12 refs
RCS Leak Rate Calculation with High Order Least Squares Method
Lee, Jeong Hun; Kang, Young Kyu; Kim, Yang Ki
2010-01-01
As a part of action items for Application of Leak before Break(LBB), RCS Leak Rate Calculation Program is upgraded in Kori unit 3 and 4. For real time monitoring of operators, periodic calculation is needed and corresponding noise reduction scheme is used. This kind of study was issued in Korea, so there have upgraded and used real time RCS Leak Rate Calculation Program in UCN unit 3 and 4 and YGN unit 1 and 2. For reduction of the noise in signals, Linear Regression Method was used in those programs. Linear Regression Method is powerful method for noise reduction. But the system is not static with some alternative flow paths and this makes mixed trend patterns of input signal values. In this condition, the trend of signal and average of Linear Regression are not entirely same pattern. In this study, high order Least squares Method is used to follow the trend of signal and the order of calculation is rearranged. The result of calculation makes reasonable trend and the procedure is physically consistence
Palmer, B.J.
1994-01-01
A method to calculate the thermal diffusivity D T from spontaneous fluctuations in the local heat energy density is presented. Calculations of the thermal diffusivity are performed for the Lennard-Jones fluid, carbon dioxide, and water. The results for the Lennard-Jones fluid are in agreement with calculations of the thermal conductivity using Green-Kubo relations and nonequilibrium molecular-dynamics techniques. The results for carbon dioxide and water give thermal diffusivities within a factor of 2 of the experimental values
Calculation method for gamma-dose rates from spherical puffs
Thykier-Nielsen, S.; Deme, S.; Lang, E.
1993-05-01
The Lagrangian puff-models are widely used for calculation of the dispersion of atmospheric releases. Basic output from such models are concentrations of material in the air and on the ground. The most simple method for calculation of the gamma dose from the concentration of airborne activity is based on semi-infinite cloud model. This method is however only applicable for points far away from the release point. The exact calculation of the cloud dose using the volume integral requires significant computer time. The volume integral for the gamma dose could be approximated by using the semi-infinite cloud model combined with correction factors. This type of calculation procedure is very fast, but usually the accuracy is poor due to the fact that the same correction factors are used for all isotopes. The authors describe a more elaborate correction method. This method uses precalculated values of the gamma-dose rate as a function of the puff dispersion parameter (δ p ) and the distance from the puff centre for four energy groups. The release of energy for each radionuclide in each energy group has been calculated and tabulated. Based on these tables and a suitable interpolation procedure the calculation of gamma doses takes very short time and is almost independent of the number of radionuclides. (au) (7 tabs., 7 ills., 12 refs.)
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.
Ye, Yong-jun; Wang, Li-heng; Ding, De-xin; Zhao, Ya-li; Fan, Nan-bin
2014-01-01
The radon diffusion coefficient and the free radon production rate are important parameters for describing radon migration in the fragmented uranium ore. In order to determine the two parameters, the pure diffusion migration equation for radon was firstly established and its analytic solution with the two parameters to be determined was derived. Then, a self manufactured experimental column was used to simulate the pure diffusion of the radon, the improved scintillation cell method was used to measure the pore radon concentrations at different depths of the column loaded with the fragmented uranium ore, and the nonlinear least square algorithm was used to inversely determine the radon diffusion coefficient and the free radon production rate. Finally, the solution with the two inversely determined parameters was used to predict the pore radon concentrations at some depths of the column, and the predicted results were compared with the measured results. The results show that the predicted results are in good agreement with the measured results and the numerical inverse method is applicable to the determination of the radon diffusion coefficient and the free radon production rate for the fragmented uranium ore. - Highlights: • Inverse method for determining two transport parameters of radon is proposed. • A self-made experimental apparatus is used to simulate radon diffusion process. • Sampling volume and position for measuring radon concentration are optimized. • The inverse results of an experimental sample are verified
Perturbative methods applied for sensitive coefficients calculations in thermal-hydraulic systems
Andrade Lima, F.R. de
1993-01-01
The differential formalism and the Generalized Perturbation Theory (GPT) are applied to sensitivity analysis of thermal-hydraulics problems related to pressurized water reactor cores. The equations describing the thermal-hydraulic behavior of these reactors cores, used in COBRA-IV-I code, are conveniently written. The importance function related to the response of interest and the sensitivity coefficient of this response with respect to various selected parameters are obtained by using Differential and Generalized Perturbation Theory. The comparison among the results obtained with the application of these perturbative methods and those obtained directly with the model developed in COBRA-IV-I code shows a very good agreement. (author)
Bisetti, Fabrizio
2012-12-01
Simulations of ion and electron transport in flames routinely adopt plasma fluid models, which require transport coefficients to compute the mass flux of charged species. In this work, the mobility and diffusion coefficient of thermal electrons in atmospheric premixed methane/air flames are calculated and analyzed. The electron mobility is highest in the unburnt region, decreasing more than threefold across the flame due to mixture composition effects related to the presence of water vapor. Mobility is found to be largely independent of equivalence ratio and approximately equal to 0.4m 2V -1s -1 in the reaction zone and burnt region. The methodology and results presented enable accurate and computationally inexpensive calculations of transport properties of thermal electrons for use in numerical simulations of charged species transport in flames. © 2012 The Combustion Institute.
Mordik, S.N.; Ponomarev, A.G.
2001-01-01
To study nonlinear dynamics of charged particles in magnetic sector analyzers one applied the matriciant method. When calculating matriciants (transfer matrices) one took account of the boundary-value effects associated with the effect of scattering field, as well as, the higher harmonics of the sector magnetic field up to the third order inclusive. In case of the rectangular distribution of field components along the optical axis one obtained analytical expressions for all aberration coefficients up to the third order exclusive. To simulate the real field with the width of scattering field not equal to zero one applied smooth distribution of components for which calculation of similar aberration coefficients was conducted using the conservative numerical method [ru
Lagana, Antonio; Faginas Lago, Noelia; Rampino, Sergio [Dipartimento di Chimica, Universita di Perugia, 06123 Perugia (Italy); Huarte-Larranaga, FermIn [Computer Simulation and Modeling Lab (CoSMoLab), Parc CientIfic de Barcelona, 08028 Barcelona (Spain); GarcIa, Ernesto [Departamento de Quimica Fisica, Universidad del PaIs Vasco, 01006 Vitoria (Spain)], E-mail: lagana05@gmail.com, E-mail: fhuarte@pcb.ub.es, E-mail: e.garcia@ehu.es
2008-10-15
Zero total angular momentum exact quantum calculations of the probabilities of the N+N{sub 2} reaction have been performed on the L3 potential energy surface having a bent transition state. This has allowed us to work out J-shifting estimates of the thermal rate coefficient based on the calculation of either detailed (state-to-state) or cumulative (multiconfiguration) probabilities. The results obtained are used to compare the numerical outcomes and the concurrent computational machineries of both quantum and semiclassical approaches as well as to exploit the potentialities of the J-shifting model. The implications of moving the barrier to reaction from the previously proposed collinear geometry of the LEPS to the bent one of L3 are also investigated by comparing the related detailed reactive probabilities.
Vanderploeg, H.A.; Booth, R.S.
1976-01-01
Rigorous expressions are derived for the biological-rate coefficients (BRCs) determined from time-dependent measurements of three different dependent variables of radionuclide tracer experiments. These variables, which apply to a single organism, are radionuclide content, radionuclide concentration and specific activity. The BRCs derived from these variables have different mathematical expressions and, for high growth rates, their numerical values can be quite different. The precise mathematical expressions for the BRCs are presented here to aid modelers in selecting the correct parameters for their models and to aid experiments in interpreting their results. The usefulness of these three variables in quantifying elemental uptakes and losses by organisms is discussed. (U.K.)
Jameson, A. R.
1990-01-01
The relationship between the rainfall rate (R) obtained from radiometric brightness temperatures and the extinction coefficient (k sub e) is investigated by computing the values of k sub e over a wide range of rainfall rates, for frequencies from 3 to 25 GHz. The results show that the strength of the relation between the R and the k sub e values exhibits considerable variation for frequencies at this range. Practical suggestions are made concerning the selection of particular frequencies for rain measurements to minimize the error in R determinations.
Derivation of the chemical-equilibrium rate coefficient using scattering theory
Mickens, R. E.
1977-01-01
Scattering theory is applied to derive the equilibrium rate coefficient for a general homogeneous chemical reaction involving ideal gases. The reaction rate is expressed in terms of the product of a number of normalized momentum distribution functions, the product of the number of molecules with a given internal energy state, and the spin-averaged T-matrix elements. An expression for momentum distribution at equilibrium for an arbitrary molecule is presented, and the number of molecules with a given internal-energy state is represented by an expression which includes the partition function.
Development of a model to calculate the overall heat transfer coefficient of greenhouse covers
Rasheed, A.; Lee, J. W.; Lee, H.L.
2017-07-01
A Building Energy Simulation (BES) model based on TRNSYS, was developed to investigate the overall heat transfer coefficient (U-value) of greenhouse covers including polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC), and horticultural glass (HG). This was used to determine the influences of inside-to-outside temperature difference, wind speed, and night sky radiation on the U-values of these materials. The model was calibrated using published values of the inside and outside convective heat transfer coefficients. Validation of the model was demonstrated by the agreement between the computed and experimental results for a single-layer PE film. The results from the BES model showed significant changes in U-value in response to variations in weather parameters and the use of single or double layer greenhouse covers. It was found that the U-value of PC, PVC, and HG was 9%, 4%, and 15% lower, respectively, than that for PE. In addition, by using double glazing a 34% reduction in heat loss was noted. For the given temperature U-value increases as wind speed increases. The slopes at the temperature differences of 20, 30, 40, and 50 °C, were approximately 0.3, 0.5, 0.7, and 0.9, respectively. The results agree with those put forward by other researchers. Hence, the presented model is reliable and can play a valuable role in future work on greenhouse energy modelling.
Semiclassical Calculation of Reaction Rate Constants for Homolytical Dissociations
Cardelino, Beatriz H.
2002-01-01
There is growing interest in extending organometallic chemical vapor deposition (OMCVD) to III-V materials that exhibit large thermal decomposition at their optimum growth temperature, such as indium nitride. The group III nitrides are candidate materials for light-emitting diodes and semiconductor lasers operating into the blue and ultraviolet regions. To overcome decomposition of the deposited compound, the reaction must be conducted at high pressures, which causes problems of uniformity. Microgravity may provide the venue for maintaining conditions of laminar flow under high pressure. Since the selection of optimized parameters becomes crucial when performing experiments in microgravity, efforts are presently geared to the development of computational OMCVD models that will couple the reactor fluid dynamics with its chemical kinetics. In the present study, we developed a method to calculate reaction rate constants for the homolytic dissociation of III-V compounds for modeling OMCVD. The method is validated by comparing calculations with experimental reaction rate constants.
A New Method to Calculate Internal Rate of Return
azadeh zandi
2015-09-01
Full Text Available A number of methods have been developed to choose the best capital investment projects such as net present value, internal rate of return and etc. Internal rate of return method is probably the most popular method among managers and investors. But despite the popularity there are serious drawbacks and limitations in this method. After decades of efforts made by economists and experts to improve the method and its shortcomings, Magni in 2010 has revealed a new approach that can solves the most of internal rate of return method problems. This paper present a new method which is originated from Magni’s approach but has much more simple calculations and can resolve all the drawbacks of internal rate of return method.
Empirical rate equation model and rate calculations of hydrogen generation for Hanford tank waste
HU, T.A.
1999-01-01
Empirical rate equations are derived to estimate hydrogen generation based on chemical reactions, radiolysis of water and organic compounds, and corrosion processes. A comparison of the generation rates observed in the field with the rates calculated for twenty eight tanks shows agreement within a factor of two to three
NAC-1 cask dose rate calculations for LWR spent fuel
CARLSON, A.B.
1999-01-01
A Nuclear Assurance Corporation nuclear fuel transport cask, NAC-1, is being considered as a transport and storage option for spent nuclear fuel located in the B-Cell of the 324 Building. The loaded casks will be shipped to the 200 East Area Interim Storage Area for dry interim storage. Several calculations were performed to assess the photon and neutron dose rates. This report describes the analytical methods, models, and results of this investigation
Calculation of the eroei coefficient for natural gas hydrates in laboratory conditions
Siažik, Ján; Malcho, Milan; Čaja, Alexander
2017-09-01
In the 1960s, scientists discovered that methane hydrate existed in the gas field in Siberia. Gas hydrates are known to be stable under conditions of high pressure and low temperature that have been recognized in polar regions and in the uppermost part of deep -water sediments below the sea floor. The article deals with the determination of the EROEI coefficient to generate the natural gas hydrate in the device under specific temperature and pressure conditions. Energy returned on energy invested expresses ratio of the amount of usable energy delivered from a particular energy resource to the amount of exergy used to obtain that energy resource. Gas hydrates have been also discussed before decades like potential source mainly for regions with restricted access to conventional hydrocarbons also tactic interest in establishing alternative gas reserves.
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
Valdés, José R.; Rodríguez, José M.; Saumell, Javier; Pütz, Thomas
2014-01-01
Highlights: • We develop a methodology for the parametric modelling of flow in hydraulic valves. • We characterize the flow coefficients with a generic function with two parameters. • The parameters are derived from CFD simulations of the generic geometry. • We apply the methodology to two cases from the automotive brake industry. • We validate by comparing with CFD results varying the original dimensions. - Abstract: The main objective of this work is to develop a methodology for the parametric modelling of the flow rate in hydraulic valve systems. This methodology is based on the derivation, from CFD simulations, of the flow coefficient of the critical restrictions as a function of the Reynolds number, using a generalized square root function with two parameters. The methodology is then demonstrated by applying it to two completely different hydraulic systems: a brake master cylinder and an ABS valve. This type of parametric valve models facilitates their implementation in dynamic simulation models of complex hydraulic systems
New rate coefficients of CS in collision with para- and ortho-H2 and astrophysical implications
Denis-Alpizar, Otoniel; Stoecklin, Thierry; Guilloteau, Stéphane; Dutrey, Anne
2018-05-01
Astronomers use the CS molecule as a gas mass tracer in dense regions of the interstellar medium, either to measure the gas density through multi-line observations or the level of turbulence. This necessarily requires the knowledge of the rates coefficients with the most common colliders in the interstellar medium, He and H2. In the present work, the close coupling collisional rates are computed for the first thirty rotational states of CS in collision with para- and ortho-H2 using a recent rigid rotor potential energy surface. Some radiative transfer calculations, using typical astrophysical conditions, are also performed to test this new set of data and to compare with the existing ones.
Wang Xinghua; Zhou Sichun; Zhang Qingxian; Zhao Feng; Liu Jun; Zhu Jian
2013-01-01
Taking Qinshan nuclear power plant as an example, in this paper, Monte Carlo method was used in the MCNP procedures for the establishment of nuclear power station simulation model, construct the reactor pressure vessel and vessel core component composition and arrangement, KCODE card was used to calculate the effect of the number and the location of burnable poison control rod factor K eff by the boron acid. The calculation results show that, with the increasing in the number of burnable poison control rod value-added factor K eff shown a downward trend, and with the burnable poison control rod from the dense to sparse, which K eff will be decreasing slowly. This condition is consistent with the theoretical. (authors)
Divided Saddle Theory: A New Idea for Rate Constant Calculation.
Daru, János; Stirling, András
2014-03-11
We present a theory of rare events and derive an algorithm to obtain rates from postprocessing the numerical data of a free energy calculation and the corresponding committor analysis. The formalism is based on the division of the saddle region of the free energy profile of the rare event into two adjacent segments called saddle domains. The method is built on sampling the dynamics within these regions: auxiliary rate constants are defined for the saddle domains and the absolute forward and backward rates are obtained by proper reweighting. We call our approach divided saddle theory (DST). An important advantage of our approach is that it requires only standard computational techniques which are available in most molecular dynamics codes. We demonstrate the potential of DST numerically on two examples: rearrangement of alanine-dipeptide (CH3CO-Ala-NHCH3) conformers and the intramolecular Cope reaction of the fluxional barbaralane molecule.
Fission observables from 4D Langevin calculations with macroscopic transport coefficients
Usang Mark D.
2018-01-01
Full Text Available We have extended the Langevin equations to 4 dimensions (4D by allowing the independent deformation for the left (δ1 and right fragments (δ2 of the fissioning nucleus. At the moment we are only able to use them in conjunction with the macroscopic transport coefficients. Nevertheless, we can see a considerable improvement in the preliminary results for the fission observables, especially those related to the total kinetic energy (TKE of fission fragments. By plotting the TKE distributions we have revealed the super-long fission modes in 236U and super-short fission modes in 257Fm. By plotting the distribution of δ against the fragment’s TKE we have noted a correlation between the values of δ and Brosa’s fission modes. We have found that the standard fission modes correspond to prolate tips of the light fragments while the complementary heavy fragments have oblate fission tips. On the other hand, if both fragments were prolate at the tips, we get super-long fission modes. If both fragments were oblate at the tips, we get super-short fission modes.
Calculation and validation of heat transfer coefficient for warm forming operations
Omer, Kaab; Butcher, Clifford; Worswick, Michael
2017-10-01
In an effort to reduce the weight of their products, the automotive industry is exploring various hot forming and warm forming technologies. One critical aspect in these technologies is understanding and quantifying the heat transfer between the blank and the tooling. The purpose of the current study is twofold. First, an experimental procedure to obtain the heat transfer coefficient (HTC) as a function of pressure for the purposes of a metal forming simulation is devised. The experimental approach was used in conjunction with finite element models to obtain HTC values as a function of die pressure. The materials that were characterized were AA5182-O and AA7075-T6. Both the heating operation and warm forming deep draw were modelled using the LS-DYNA commercial finite element code. Temperature-time measurements were obtained from both applications. The results of the finite element model showed that the experimentally derived HTC values were able to predict the temperature-time history to within a 2% of the measured response. It is intended that the HTC values presented herein can be used in warm forming models in order to accurately capture the heat transfer characteristics of the operation.
Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R.A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.
2012-01-01
Room-temperature N 2 -broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH 3 Cl-N 2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.
Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R. A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.
2012-07-01
Room-temperature N2-broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH3Cl-N2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.
Determination of diffusion coefficients of oxygen atoms in ZrO2 using first-principles calculations
Segi, Takashi; Okuda, Takanari
2014-01-01
Density functional theory and nudged elastic band calculations were performed in order to determine the diffusion coefficient for oxygen from monoclinic ZrO 2 . The calculated values for monoclinic ZrO 2 at 1000 K and 1500 K were 5.88 × 10 -16 cm 2 s -1 and 2.91 × 10 -11 cm 2 s -1 , respectively, and agreed with previously determined experimental values. In addition, the results of the nudged elastic band calculations suggest that interstitial oxygen sites exist between stable oxygen sites, and if oxygen atoms occupy these sites, stable structures with values for the lattice angle β of greater than 80.53° may be obtained. (author)
Relative measurement of the excitation rate coefficients of the FeXI ion
Marotta, A.
1982-01-01
The collision rate coefficients for the iron atoms are measured through the hot plasma obtainment. The physical model used in this determination is the crown stationary model which consider that the excitation by electronic collisions is balanced by the spontaneous emission. This work was realized in a 15Kj theta pinch device, of high pulse reproductibility. The iron-pentacarbonyl [Fe(Co) 5 ] was used as the impurity source of a hydrogen gas. The temperature and density were determined by the scattering light analysis of a rubi laser using the Thomson scattering. (L.C.) [pt
Jambrina, P. G.; Lara, Manuel; Menéndez, M.; Launay, J.-M.; Aoiz, F. J.
2012-10-01
Cumulative reaction probabilities (CRPs) at various total angular momenta have been calculated for the barrierless reaction S(1D) + H2 → SH + H at total energies up to 1.2 eV using three different theoretical approaches: time-independent quantum mechanics (QM), quasiclassical trajectories (QCT), and statistical quasiclassical trajectories (SQCT). The calculations have been carried out on the widely used potential energy surface (PES) by Ho et al. [J. Chem. Phys. 116, 4124 (2002), 10.1063/1.1431280] as well as on the recent PES developed by Song et al. [J. Phys. Chem. A 113, 9213 (2009), 10.1021/jp903790h]. The results show that the differences between these two PES are relatively minor and mostly related to the different topologies of the well. In addition, the agreement between the three theoretical methodologies is good, even for the highest total angular momenta and energies. In particular, the good accordance between the CRPs obtained with dynamical methods (QM and QCT) and the statistical model (SQCT) indicates that the reaction can be considered statistical in the whole range of energies in contrast with the findings for other prototypical barrierless reactions. In addition, total CRPs and rate coefficients in the range of 20-1000 K have been calculated using the QCT and SQCT methods and have been found somewhat smaller than the experimental total removal rates of S(1D).
Comparison between calculation methods of dose rates in gynecologic brachytherapy
Vianello, E.A.; Biaggio, M.F.; D R, M.F.; Almeida, C.E. de
1998-01-01
In treatments with radiations for gynecologic tumors is necessary to evaluate the quality of the results obtained by different calculation methods for the dose rates on the points of clinical interest (A, rectal, vesicle). The present work compares the results obtained by two methods. The Manual Calibration Method (MCM) tri dimensional (Vianello E., et.al. 1998), using orthogonal radiographs for each patient in treatment, and the Theraplan/T P-11 planning system (Thratonics International Limited 1990) this last one verified experimentally (Vianello et.al. 1996). The results show that MCM can be used in the physical-clinical practice with a percentile difference comparable at the computerized programs. (Author)
Ganeshan, S.; Hector, L.G.; Liu, Z.-K.
2011-01-01
Research highlights: → Implemented the eight frequency model for impurity diffusion in hexagonal metals. → Model inputs were energetics/vibrational properties from first princples. → Predicted diffusion coefficients for Al, Ca, Zn and Sn impurity diffusion in Mg. → Successful prediction of partial correlation factors and jump frequencies. → Good agreement between calculated and experimental results. - Abstract: Diffusion in dilute Mg-X alloys, where X denotes Al, Zn, Sn and Ca impurities, was investigated with first-principles density functional theory in the local density approximation. Impurity diffusion coefficients were computed as a function of temperature using the 8-frequency model which provided the relevant impurity and solvent (Mg) jump frequencies and correlation factors. Minimum energy pathways for impurity diffusion and associated saddle point structures were computed with the climbing image nudged elastic band method. Vibrational properties were obtained with the supercell (direct) method for lattice dynamics. Calculated diffusion coefficients were compared with available experimental data. For diffusion between basal planes, we find D Mg-Ca > D Mg-Zn > D Mg-Sn > D Mg-Al, where D is the diffusion coefficient. For diffusion within a basal plane, the same trend holds except that D Mg-Zn overlaps with D Mg-Al at high temperatures and D Mg-Sn at low temperatures. These trends were explored with charge density contours in selected planes of each Mg-X alloy, the variation of the activation energy for diffusion with the atomic radius of each impurity and the electronic density of states. The theoretical methodology developed herein can be applied to impurity diffusion in other hexagonal materials.
A software to edit voxel phantoms and to calculate conversion coefficients for radiation protection
Vieira, J.W.; Stosic, B.; Lima, F.R.A.; Kramer, R.; Santos, A.M.; Lima, V.J.M.
2005-01-01
The MAX and FAX phantoms have been developed based on a male and female, respectively, adult body from ICRP and coupled to the Monte Carlo code (EGS4). These phantoms permit the calculating of the equivalent dose in organs and tissues of the human body for the radiation protection purposes . In the constructing of these anthropomorphic models, the software developed called FANTOMAS, which performs tasks as file format conversion, filtering 2D and 3D images, exchange of identifying numbers of organs, body mass adjustments based in volume, resampling of 2D and 3D images, resize images, preview consecutive slices of the phantom, running computational models of exposure FANTOMA/EGS4 and viewing graphics of conversion factors between equivalent dose and a measurable dosimetric quantity. This paper presents the main abilities of FANTOMAS and uses the MAX and/or FAX to exemplify some procedures
Neural network approach for the calculation of potential coefficients in quantum mechanics
Ossandón, Sebastián; Reyes, Camilo; Cumsille, Patricio; Reyes, Carlos M.
2017-05-01
A numerical method based on artificial neural networks is used to solve the inverse Schrödinger equation for a multi-parameter class of potentials. First, the finite element method was used to solve repeatedly the direct problem for different parametrizations of the chosen potential function. Then, using the attainable eigenvalues as a training set of the direct radial basis neural network a map of new eigenvalues was obtained. This relationship was later inverted and refined by training an inverse radial basis neural network, allowing the calculation of the unknown parameters and therefore estimating the potential function. Three numerical examples are presented in order to prove the effectiveness of the method. The results show that the method proposed has the advantage to use less computational resources without a significant accuracy loss.
Boas, F Edward; Kamaya, Aya; Do, Bao; Desser, Terry S; Beaulieu, Christopher F; Vasanawala, Shreyas S; Hwang, Gloria L; Sze, Daniel Y
2015-04-01
Perfusion CT of the liver typically involves scanning the liver at least 20 times, resulting in a large radiation dose. We developed and validated a simplified model of tumor blood supply that can be applied to standard triphasic scans and evaluated whether this can be used to distinguish benign and malignant liver lesions. Triphasic CTs of 46 malignant and 32 benign liver lesions were analyzed. For each phase, regions of interest were drawn in the arterially enhancing portion of each lesion, as well as the background liver, aorta, and portal vein. Hepatic artery and portal vein blood supply coefficients for each lesion were then calculated by expressing the enhancement curve of the lesion as a linear combination of the enhancement curves of the aorta and portal vein. Hepatocellular carcinoma (HCC) and hypervascular metastases, on average, both had increased hepatic artery coefficients compared to the background liver. Compared to HCC, benign lesions, on average, had either a greater hepatic artery coefficient (hemangioma) or a greater portal vein coefficient (focal nodular hyperplasia or transient hepatic attenuation difference). Hypervascularity with washout is a key diagnostic criterion for HCC, but it had a sensitivity of 72 % and specificity of 81 % for diagnosing malignancy in our diverse set of liver lesions. The sensitivity for malignancy was increased to 89 % by including enhancing lesions that were hypodense on all phases. The specificity for malignancy was increased to 97 % (p = 0.039) by also examining hepatic artery and portal vein blood supply coefficients, while maintaining a sensitivity of 76 %.
X particle effect for 6Li reaction rates calculations
Kocak, G.; Balantekin, A. B.
2009-01-01
The inferred primordial 6 L i-7 L i abundances are different from standard big bang nucleosynthesis results, 6 L i is 1000 times larger and 7 L i is 3 times smaller than the big bang prediction. In big bang nucleosynthesis, negatively charged massive X particles a possible solution to explain this primordial Li abundances problem [1]. In this study, we consider only X particle effect for nuclear reactions to obtain S-factor and reaction rates for Li. All S-factors calculated within the Optical Model framework for d(α,γ)6 L i system. We showed that the enhancement effect of massive negatively charged X particle for 6 L i system reaction rate.(author)
Orlov, Yu. V.; Irgaziev, B. F.; Nabi, Jameel-Un
2017-08-01
A new algorithm for the asymptotic nuclear coefficients calculation, which we call the Δ method, is proved and developed. This method was proposed by Ramírez Suárez and Sparenberg (arXiv:1602.04082.) but no proof was given. We apply it to the bound state situated near the channel threshold when the Sommerfeld parameter is quite large within the experimental energy region. As a result, the value of the conventional effective-range function Kl(k2) is actually defined by the Coulomb term. One of the resulting effects is a wrong description of the energy behavior of the elastic scattering phase shift δl reproduced from the fitted total effective-range function Kl(k2) . This leads to an improper value of the asymptotic normalization coefficient (ANC) value. No such problem arises if we fit only the nuclear term. The difference between the total effective-range function and the Coulomb part at real energies is the same as the nuclear term. Then we can proceed using just this Δ method to calculate the pole position values and the ANC. We apply it to the vertices 4He+12C ↔16O and 3He+4He↔7Be . The calculated ANCs can be used to find the radiative capture reaction cross sections of the transfers to the 16O bound final states as well as to the 7Be.
Santos, William S.; Carvalho Junior, Alberico B. de; Pereira, Ariana J.S.; Santos, Marcos S.; Maia, Ana F.
2011-01-01
In this paper conversion coefficients (CCs) of equivalent dose and effective in terms of kerma in the air were calculated suggested by the ICRP 74. These dose coefficients were calculated considering a plane radiation source and monoenergetic for a spectrum of energy varying from 10 keV to 2 MeV. The CCs were obtained for four geometries of irradiation, anterior-posterior, posterior-anterior, lateral right side and lateral left side. It was used the radiation transport code Visual Monte Carlo (VMC), and a anthropomorphic simulator of sit female voxel. The observed differences in the found values for the CCs at the four irradiation sceneries are direct results of the body organs disposition, and the distance of these organs to the irradiation source. The obtained CCs will be used for estimative more precise of dose in situations that the exposed individual be sit, as the normally the CCs available in the literature were calculated by using simulators always lying or on their feet
Dateo, Christopher E.; Walch, Stephen P.
2002-01-01
As part of NASA Ames Research Center's Integrated Process Team on Device/Process Modeling and Nanotechnology our goal is to create/contribute to a gas-phase chemical database for use in modeling microelectronics devices. In particular, we use ab initio methods to determine chemical reaction pathways and to evaluate reaction rate coefficients. Our initial studies concern reactions involved in the dichlorosilane-hydrogen (SiCl2H2--H2) and trichlorosilane-hydrogen (SiCl2H-H2) systems. Reactant, saddle point (transition state), and product geometries and their vibrational harmonic frequencies are determined using the complete-active-space self-consistent-field (CASSCF) electronic structure method with the correlation consistent polarized valence double-zeta basis set (cc-pVDZ). Reaction pathways are constructed by following the imaginary frequency mode of the saddle point to both the reactant and product. Accurate energetics are determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations (CCSD(T)) extrapolated to the complete basis set limit. Using the data from the electronic structure calculations, reaction rate coefficients are obtained using conventional and variational transition state and RRKM theories.
Rating of Dynamic Coefficient for Simple Beam Bridge Design on High-Speed Railways
Diachenko, Leonid; Benin, Andrey; Smirnov, Vladimir; Diachenko, Anastasia
2018-06-01
The aim of the work is to improve the methodology for the dynamic computation of simple beam spans during the impact of high-speed trains. Mathematical simulation utilizing numerical and analytical methods of structural mechanics is used in the research. The article analyses parameters of the effect of high-speed trains on simple beam spanning bridge structures and suggests a technique of determining of the dynamic index to the live load. Reliability of the proposed methodology is confirmed by results of numerical simulation of high-speed train passage over spans with different speeds. The proposed algorithm of dynamic computation is based on a connection between maximum acceleration of the span in the resonance mode of vibrations and the main factors of stress-strain state. The methodology allows determining maximum and also minimum values of the main efforts in the construction that makes possible to perform endurance tests. It is noted that dynamic additions for the components of the stress-strain state (bending moments, transverse force and vertical deflections) are different. This condition determines the necessity for differentiated approach to evaluation of dynamic coefficients performing design verification of I and II groups of limiting state. The practical importance: the methodology of determining the dynamic coefficients allows making dynamic calculation and determining the main efforts in split beam spans without numerical simulation and direct dynamic analysis that significantly reduces the labour costs for design.
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.
Estimating Reaction Rate Coefficients Within a Travel-Time Modeling Framework
Gong, R [Georgia Institute of Technology; Lu, C [Georgia Institute of Technology; Luo, Jian [Georgia Institute of Technology; Wu, Wei-min [Stanford University; Cheng, H. [Stanford University; Criddle, Craig [Stanford University; Kitanidis, Peter K. [Stanford University; Gu, Baohua [ORNL; Watson, David B [ORNL; Jardine, Philip M [ORNL; Brooks, Scott C [ORNL
2011-03-01
A generalized, efficient, and practical approach based on the travel-time modeling framework is developed to estimate in situ reaction rate coefficients for groundwater remediation in heterogeneous aquifers. The required information for this approach can be obtained by conducting tracer tests with injection of a mixture of conservative and reactive tracers and measurements of both breakthrough curves (BTCs). The conservative BTC is used to infer the travel-time distribution from the injection point to the observation point. For advection-dominant reactive transport with well-mixed reactive species and a constant travel-time distribution, the reactive BTC is obtained by integrating the solutions to advective-reactive transport over the entire travel-time distribution, and then is used in optimization to determine the in situ reaction rate coefficients. By directly working on the conservative and reactive BTCs, this approach avoids costly aquifer characterization and improves the estimation for transport in heterogeneous aquifers which may not be sufficiently described by traditional mechanistic transport models with constant transport parameters. Simplified schemes are proposed for reactive transport with zero-, first-, nth-order, and Michaelis-Menten reactions. The proposed approach is validated by a reactive transport case in a two-dimensional synthetic heterogeneous aquifer and a field-scale bioremediation experiment conducted at Oak Ridge, Tennessee. The field application indicates that ethanol degradation for U(VI)-bioremediation is better approximated by zero-order reaction kinetics than first-order reaction kinetics.
Rate Coefficient Determinations for H + NO2 → OH + NO from High Pressure Flow Reactor Measurements.
Haas, Francis M; Dryer, Frederick L
2015-07-16
Rate coefficients for the reaction H + NO2 → OH + NO (R1) have been determined over the nominal temperature and pressure ranges of 737-882 K and 10-20 atm, respectively, from measurements in two different flow reactor facilities: one laminar and one turbulent. Considering the existing database of experimental k1 measurements, the present conditions add measurements of k1 at previously unconsidered temperatures between ∼820-880 K, as well as at pressures that exceed existing measurements by over an order of magnitude. Experimental measurements of NOx-perturbed H2 oxidation have been interpreted by a quasi-steady state NOx plateau (QSSP) method. At the QSSP conditions considered here, overall reactivity is sensitive only to the rates of R1 and H + O2 + M → HO2 + M (R2.M). Consequently, the ratio of k1 to k2.M may be extracted as a simple algebraic function of measured NO2, O2, and total gas concentrations with only minimal complication (within measurement uncertainty) due to treatment of overall gas composition M that differs slightly from pure bath gas B. Absolute values of k1 have been determined with reference to the relatively well-known, pressure-dependent rate coefficients of R2.B for B = Ar and N2. Rate coefficients for the title reaction determined from present experimental interpretation of both laminar and turbulent flow reactor results appear to be in very good agreement around a representative value of 1.05 × 10(14) cm(3) mol(-1) s(-1) (1.74 × 10(-10) cm(3) molecule(-1) s(-1)). Further, the results of this study agree both with existing low pressure flash photolysis k1 determinations of Ko and Fontijn (J. Phys. Chem. 95 3984) near 760 K as well as a present fit to the theoretical expression of Su et al. (J. Phys. Chem. A 106 8261). These results indicate that, over the temperature range considered in this study and up to at least 20 atm, net chemistry due to stabilization of the H-NO2 reaction intermediate to form isomers of HNO2 may proceed at
Zhang, Bintuan; Dang, Bingrong; Wang, Zhuanzi; Wei, Wei; Li, Wenjian
2013-10-01
The skin tissue-equivalent slab reported in the International Commission on Radiological Protection (ICRP) Publication 116 to calculate the localised skin dose conversion coefficients (LSDCCs) was adopted into the Monte Carlo transport code Geant4. The Geant4 code was then utilised for computation of LSDCCs due to a circular parallel beam of monoenergetic electrons, protons and alpha particles electrons and alpha particles are found to be in good agreement with the results using the MCNPX code of ICRP 116 data. The present work thus validates the LSDCC values for both electrons and alpha particles using the Geant4 code.
Yasa, F.; Anli, F.; Guengoer, S.
2007-01-01
We present analytical calculations of spherically symmetric radioactive transfer and neutron transport using a hypothesis of P1 and T1 low order polynomial approximation for diffusion coefficient D. Transport equation in spherical geometry is considered as the pseudo slab equation. The validity of polynomial expansionion in transport theory is investigated through a comparison with classic diffusion theory. It is found that for causes when the fluctuation of the scattering cross section dominates, the quantitative difference between the polynomial approximation and diffusion results was physically acceptable in general
Werfelli, Ghofran; Halvick, Philippe; Honvault, Pascal; Kerkeni, Boutheïna; Stoecklin, Thierry
2015-09-21
The observed abundances of the methylidyne cation, CH(+), in diffuse molecular clouds can be two orders of magnitude higher than the prediction of the standard gas-phase models which, in turn, predict rather well the abundances of neutral CH. It is therefore necessary to investigate all the possible formation and destruction processes of CH(+) in the interstellar medium with the most abundant species H, H2, and e(-). In this work, we address the destruction process of CH(+) by hydrogen abstraction. We report a new calculation of the low temperature rate coefficients for the abstraction reaction, using accurate time-independent quantum scattering and a new high-level ab initio global potential energy surface including a realistic model of the long-range interaction between the reactants H and CH(+). The calculated thermal rate coefficient is in good agreement with the experimental data in the range 50 K-800 K. However, at lower temperatures, the experimental rate coefficient takes exceedingly small values which are not reproduced by the calculated rate coefficient. Instead, the latter rate coefficient is close to the one given by the Langevin capture model, as expected for a reaction involving an ion and a neutral species. Several recent theoretical works have reported a seemingly good agreement with the experiment below 50 K, but an analysis of these works show that they are based on potential energy surfaces with incorrect long-range behavior. The experimental results were explained by a loss of reactivity of the lowest rotational states of the reactant; however, the quantum scattering calculations show the opposite, namely, a reactivity enhancement with rotational excitation.
Benchmark calculations for evaluation methods of gas volumetric leakage rate
Asano, R.; Aritomi, M.; Matsuzaki, M.
1998-01-01
A containment function of radioactive materials transport casks is essential for safe transportation to prevent the radioactive materials from being released into environment. Regulations such as IAEA standard determined the limit of radioactivity to be released. Since is not practical for the leakage tests to measure directly the radioactivity release from a package, as gas volumetric leakages rates are proposed in ANSI N14.5 and ISO standards. In our previous works, gas volumetric leakage rates for several kinds of gas from various leaks were measured and two evaluation methods, 'a simple evaluation method' and 'a strict evaluation method', were proposed based on the results. The simple evaluation method considers the friction loss of laminar flow with expansion effect. The strict evaluating method considers an exit loss in addition to the friction loss. In this study, four worked examples were completed for on assumed large spent fuel transport cask (Type B Package) with wet or dry capacity and at three transport conditions; normal transport with intact fuels or failed fuels, and an accident in transport. The standard leakage rates and criteria for two kinds of leak test were calculated for each example by each evaluation method. The following observations are made based upon the calculations and evaluations: the choked flow model of ANSI method greatly overestimates the criteria for tests ; the laminar flow models of both ANSI and ISO methods slightly overestimate the criteria for tests; the above two results are within the design margin for ordinary transport condition and all methods are useful for the evaluation; for severe condition such as failed fuel transportation, it should pay attention to apply a choked flow model of ANSI method. (authors)
Nguyen Thanh Duoc; Nguyen Thi Ai Nhung; Tran Duong; Pham Van Tat
2015-01-01
The results presented in this paper are the ab initio intermolecular potentials and the second virial coefficient, B_2 (T) of the dimer Cl_2-Cl_2. These ab initio potentials were proposed by the quantum chemical calculations at high level of theory CCSD(T) with basis sets of Dunning valence correlation-consistent aug-cc-pVmZ (m = 2, 3); these results were extrapolated to complete basis set limit aug-cc-pV23Z. The ab initio energies of complete basis set limit aug-cc-pV23Z resulted from the exponential extrapolation were used to construct the 5-site pair potential functions. The second virial coefficients for this dimer were predicted from those with four-dimensional integration. The second virial coefficients were also corrected to first-order quantum effects. The results turn out to be in good agreement with experimental data, if available, or with those from empirical correlation. The quality of ab initio 5-site potentials proved the reliability for prediction of molecular thermodynamic properties. (author)
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
Zhu, Hongyu; Qiu, Rui; Ren, Li; Zhang, Hui; Li, Junli; Wu, Zhen; Li, Chunyan
2017-01-01
The human eye lens is sensitive to radiation. ICRP-118 publication recommended a reduction of the occupational annual equivalent dose limit from 150 to 20 mSv, averaged over defined periods of 5 y. Therefore, it is very important to build a detailed eye model for the accurate dose assessment and radiation risk evaluation of eye lens. In this work, a detailed eye model was build based on the characteristic anatomic parameters of the Chinese adult male. This eye model includes seven main structures, which are scleral, choroid, lens, iris, cornea, vitreous body and aqueous humor. The lens was divided into sensitive volume and insensitive volume based on different cell populations. The detailed eye model was incorporated into the converted polygon-mesh version of the Chinese reference adult male whole-body surface model. After the incorporation, dose conversion coefficients for the eye lens were calculated for neutron exposure at AP, PA and LAT geometries with Geant4, the neutron energies were from 0.001 eV to 10 MeV. The calculated lens dose coefficients were compared with those of ICRP-116 publication. Significant differences up to 97.47% were found at PA geometry. This could mainly be attributed to the different geometry characteristic of eye model and parameters of head in different phantom between the present work and ICRP-116 publication. (authors)
Zhu, Hongyu; Qiu, Rui; Wu, Zhen; Ren, Li; Li, Chunyan; Zhang, Hui; Li, Junli
2017-12-01
The human eye lens is sensitive to radiation. ICRP-118 publication recommended a reduction of the occupational annual equivalent dose limit from 150 to 20 mSv, averaged over defined periods of 5 y. Therefore, it is very important to build a detailed eye model for the accurate dose assessment and radiation risk evaluation of eye lens. In this work, a detailed eye model was build based on the characteristic anatomic parameters of the Chinese adult male. This eye model includes seven main structures, which are scleral, choroid, lens, iris, cornea, vitreous body and aqueous humor. The lens was divided into sensitive volume and insensitive volume based on different cell populations. The detailed eye model was incorporated into the converted polygon-mesh version of the Chinese reference adult male whole-body surface model. After the incorporation, dose conversion coefficients for the eye lens were calculated for neutron exposure at AP, PA and LAT geometries with Geant4, the neutron energies were from 0.001 eV to 10 MeV. The calculated lens dose coefficients were compared with those of ICRP-116 publication. Significant differences up to 97.47% were found at PA geometry. This could mainly be attributed to the different geometry characteristic of eye model and parameters of head in different phantom between the present work and ICRP-116 publication. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Schwartz, S.E.
1988-10-01
Although it has been recognized for some time that the rate of reactive uptake of gases in cloudwater can depend on the value of the mass-accommodation coefficient (α) describing interfacial mass transport (MT), definitive evaluation of such rates is only now becoming possible with the availability of measurements of α for gases of atmospheric interest at air-water interfaces. Examination of MT limitation to the rate of in-cloud aqueous-phase oxidation of SO 2 by O 3 and H 2 O 2 shows that despite the low value of α/sub O3/ (5 /times/ 10/sup /minus/4/), interfacial MT of this species is not limiting under essentially all conditions of interest; the high values of α for SO 2 (≥ 0.2) and H 2 O 2 (≥ 0.08) indicate no interfacial MT limitation for these species also. Although gas- and aqueous-phase MT can be limiting under certain extremes of conditions, treating the system as under chemical kinetic control is generally an excellent approximation. Interfacial MT limitation also is found not to hinder the rate of H 2 O 2 formation by aqueous-phase disproportionation of HO 2 . Finally, the rapid uptake of N 2 O 5 by cloud droplets implies that the yield of aqueous HNO 3 from in-cloud gas-phase oxidation of NO 2 by O 3 can be substantial even under daytime conditions. This report consists of copies of viewgraphs prepared for this presentation
Uehara, Yasushi; Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Koshizuka, Seiichi
2009-01-01
In order to predict and mitigate flow accelerated corrosion (FAC) of carbon steel piping in PWR and BWR secondary systems, computer program packages for evaluating FAC have been developed by coupling one through three dimensional (1-3D) computational flow dynamics (CFD) models and corrosion models. To evaluate corrosive conditions, e.g., oxygen concentration and electrochemical corrosion potential (ECP) along the flow path, flow pattern and temperature in each elemental volume were obtained with 1D computational flow dynamics (CFD) codes. Precise flow turbulence and mass transfer coefficients at the structure surface were calculated with 3D CFD codes to determine wall thinning rates. One of the engineering options is application of k-ε calculation as a 3D CFD code, which has limitation of detail evaluation of flow distribution at very surface of large scale piping. A combination of k-ε calculation and wall function was proposed to evaluate precise distribution of mass transfer coefficients with reasonable CPU volume and computing time and, at the same time, reasonable accuracy. (author)
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.
Approaches to proton single-event rate calculations
Petersen, E.L.
1996-01-01
This article discusses the fundamentals of proton-induced single-event upsets and of the various methods that have been developed to calculate upset rates. Two types of approaches are used based on nuclear-reaction analysis. Several aspects can be analyzed using analytic methods, but a complete description is not available. The paper presents an analytic description for the component due to elastic-scattering recoils. There have been a number of studies made using Monte Carlo methods. These can completely describe the reaction processes, including the effect of nuclear reactions occurring outside the device-sensitive volume. They have not included the elastic-scattering processes. The article describes the semiempirical approaches that are most widely used. The quality of previous upset predictions relative to space observations is discussed and leads to comments about the desired quality of future predictions. Brief sections treat the possible testing limitation due to total ionizing dose effects, the relationship of proton and heavy-ion upsets, upsets due to direct proton ionization, and relative proton and cosmic-ray upset rates
Tong, Meiping; Camesano, Terri A; Johnson, William P
2005-05-15
The transport of bacterial strain DA001 was examined in packed quartz sand under a variety of environmentally relevant ionic strength and flow conditions. Under all conditions, the retained bacterial concentrations decreased with distance from the column inlet at a rate that was faster than loglinear, indicating that the deposition rate coefficient decreased with increasing transport distance. The hyperexponential retained profile contrasted againstthe nonmonotonic retained profiles that had been previously observed for this same bacterial strain in glass bead porous media, demonstrating that the form of deviation from log-linear behavior is highly sensitive to system conditions. The deposition rate constants in quartz sand were orders of magnitude below those expected from filtration theory, even in the absence of electrostatic energy barriers. The degree of hyperexponential deviation of the retained profiles from loglinear behavior did not decrease with increasing ionic strength in quartz sand. These observations demonstrate thatthe observed low adhesion and deviation from log-linear behavior was not driven by electrostatic repulsion. Measurements of the interaction forces between DA001 cells and the silicon nitride tip of an atomic force microscope (AFM) showed that the bacterium possesses surface polymers with an average equilibrium length of 59.8 nm. AFM adhesion force measurements revealed low adhesion affinities between silicon nitride and DA001 polymers with approximately 95% of adhesion forces having magnitudes responsible for the low adhesion to silicon nitride, indicating that steric interactions from extracellular polymers controlled DA001 adhesion deficiency and deviation from log-linear behavior on quartz sand.
Büttner, Kathrin; Salau, Jennifer; Krieter, Joachim
2016-01-01
The average topological overlap of two graphs of two consecutive time steps measures the amount of changes in the edge configuration between the two snapshots. This value has to be zero if the edge configuration changes completely and one if the two consecutive graphs are identical. Current methods depend on the number of nodes in the network or on the maximal number of connected nodes in the consecutive time steps. In the first case, this methodology breaks down if there are nodes with no edges. In the second case, it fails if the maximal number of active nodes is larger than the maximal number of connected nodes. In the following, an adaption of the calculation of the temporal correlation coefficient and of the topological overlap of the graph between two consecutive time steps is presented, which shows the expected behaviour mentioned above. The newly proposed adaption uses the maximal number of active nodes, i.e. the number of nodes with at least one edge, for the calculation of the topological overlap. The three methods were compared with the help of vivid example networks to reveal the differences between the proposed notations. Furthermore, these three calculation methods were applied to a real-world network of animal movements in order to detect influences of the network structure on the outcome of the different methods.
Lara, A; Riquelme, M; Vöhringer-Martinez, E
2018-05-11
Partition coefficients serve in various areas as pharmacology and environmental sciences to predict the hydrophobicity of different substances. Recently, they have also been used to address the accuracy of force fields for various organic compounds and specifically the methylated DNA bases. In this study, atomic charges were derived by different partitioning methods (Hirshfeld and Minimal Basis Iterative Stockholder) directly from the electron density obtained by electronic structure calculations in a vacuum, with an implicit solvation model or with explicit solvation taking the dynamics of the solute and the solvent into account. To test the ability of these charges to describe electrostatic interactions in force fields for condensed phases, the original atomic charges of the AMBER99 force field were replaced with the new atomic charges and combined with different solvent models to obtain the hydration and chloroform solvation free energies by molecular dynamics simulations. Chloroform-water partition coefficients derived from the obtained free energies were compared to experimental and previously reported values obtained with the GAFF or the AMBER-99 force field. The results show that good agreement with experimental data is obtained when the polarization of the electron density by the solvent has been taken into account, and when the energy needed to polarize the electron density of the solute has been considered in the transfer free energy. These results were further confirmed by hydration free energies of polar and aromatic amino acid side chain analogs. Comparison of the two partitioning methods, Hirshfeld-I and Minimal Basis Iterative Stockholder (MBIS), revealed some deficiencies in the Hirshfeld-I method related to the unstable isolated anionic nitrogen pro-atom used in the method. Hydration free energies and partitioning coefficients obtained with atomic charges from the MBIS partitioning method accounting for polarization by the implicit solvation model
Mihajlov, A A [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro); Ignjatovic, Lj M [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro); Djuric, Z [Silvaco Data Systems, Compass Point, St Ives PE27 5JL (United Kingdom); Ljepojevic, N N [Silvaco Data Systems, Compass Point, St Ives PE27 5JL (United Kingdom)
2004-11-28
This paper presents the results of semi-classical calculations of rate coefficients of (n - n')-mixing processes in collisions of Rydberg atoms H*(n) with H(1s) atoms. These processes have been modelled by the mechanism of the resonant energy exchange within the electron component of the H*(n) + H collisional system. The calculations of the rate coefficients, based on this model, were performed for the series of principal quantum numbers, n and n', and atomic, T{sub a}, and electronic, T{sub e}, temperatures. It was shown that these processes can be of significant influence on the populations of Rydberg atoms in weakly ionized plasmas (ionization degree {approx}<10{sup -4}), and therefore have to be included in appropriate models of such plasmas.
Mihajlov, A A; Ignjatovic, Lj M; Djuric, Z; Ljepojevic, N N
2004-01-01
This paper presents the results of semi-classical calculations of rate coefficients of (n - n')-mixing processes in collisions of Rydberg atoms H*(n) with H(1s) atoms. These processes have been modelled by the mechanism of the resonant energy exchange within the electron component of the H*(n) + H collisional system. The calculations of the rate coefficients, based on this model, were performed for the series of principal quantum numbers, n and n', and atomic, T a , and electronic, T e , temperatures. It was shown that these processes can be of significant influence on the populations of Rydberg atoms in weakly ionized plasmas (ionization degree ∼ -4 ), and therefore have to be included in appropriate models of such plasmas
Pawlak, Mariusz; Ben-Asher, Anael; Moiseyev, Nimrod
2018-01-09
We present a simple expression and its derivation for reaction rate coefficients for cold anisotropic collision experiments based on adiabatic variational theory and time-independent non-Hermitian scattering theory. We demonstrate that only the eigenenergies of the resulting one-dimensional Schrödinger equation for different complex adiabats are required. The expression is applied to calculate the Penning ionization rate coefficients of an excited metastable helium atom with molecular hydrogen in an energy range spanning from hundreds of kelvins down to the millikelvin regime. Except for trivial quantities like the masses of the nuclei and the bond length of the diatomic molecule participating in the collision, one needs as input data only the complex potential energy surface (CPES). In calculations, we used recently obtained ab initio CPES by D. Bhattacharya et al. ( J. Chem. Theory Comput. 2017 , 13 , 1682 - 1690 ) without fitting parameters. The results show good accord with current measurements ( Nat. Phys. 2017 , 13 , 35 - 38 ).
Erpenbeck, J.J.
1989-01-01
The thermal transport properties of mixtures can be formulated in a number of ways, depending on the choice of driving forces for the transport of heat and matter, without violating the Onsager conditions. Here we treat transport in mixtures based on the driving forces -del ln T and -T del(μ/sub a//T), with T the temperature and μ/sub a/ the specific chemical potential, to obtain the Green-Kubo expressions and the Enskog theory for the corresponding transport coefficients which seem most amenable to molecular-dynamics evaluation. The transport properties of a hard-sphere mixture (mass ratio of 0.1, diameter ratio of 1.0, at a volume of three times close-packed volume), calculated by a Monte Carlo, molecular-dynamics method based on the Green-Kubo formulas, are compared with the predictions of the Enskog theory. The long-time behavior of the Green-Kubo time-correlation functions for shear viscosity, thermal conductivity, thermal diffusion, and mutual diffusion are found to be in good agreement with the predictions of mode-coupling theory. Except for viscosity, the contribution of the long-time tails to the transport coefficients is found to be significant. We obtain values, relative to Enskog, of 1.016 +- 0.007 for shear viscosity, 1.218 +- 0.009 for thermal conductivity, 1.267 +- 0.026 for thermal diffusion, and 1.117 +- 0.008 for mutual diffusion
Ballesteros, Bernabé; Ceacero-Vega, Antonio A; Jiménez, Elena; Albaladejo, José
2015-04-01
mechanism for ring-retaining product channels is proposed to justify the observed reaction products. The global tropospheric lifetimes estimated from the reported OH- and Cl-rate coefficients show that the main removal path for the investigated methylcyclohexanes is the reaction with OH radicals. But in marine environments, after sunrise, Cl reactions become more important in the tropospheric degradation. Thus, the estimated lifetimes range from 16 to 24 h for the reactions of the OH radical (calculated with [OH] = 10(6) atoms cm(-3)) and around 7-8 h in the reactions with Cl atoms in marine environments (calculated with [Cl] = 1.3 × 10(5) atoms cm(-3)). The reaction of Cl atoms and OH radicals and methylcylohexanes can proceed by H abstraction from the different positions.
Dryahina, K.; Spanel, P.
2005-07-01
A method to calculate diffusion coefficients of ions important for the selected ion flow tube mass spectrometry, SIFT-MS, is presented. The ions, on which this method is demonstrated, include the SIFT-MS precursors H3O+(H2O)0,1,2,3, NO.+(H2O)0,1,2 and O2+ and the product ions relevant to analysis of breath trace metabolites ammonia (NH3+(H2O)0,1,2, NH4+(H2O)0,1,2), acetaldehyde (C2H4OH+(H2O)0,1,2), acetone (CH3CO+, (CH3)2CO+, (CH3)2COH+(H2O)0,1, (CH3)2CO.NO+), ethanol (C2H5OHH+(H2O)0,1,2) and isoprene (C5H7+, C5H8+, C5H9+). Theoretical model of the (12, 4) potential for interaction between the ions and the helium atoms is used, with the repulsive part approximated by the mean hard-sphere cross section and the attractive part describing ion-induced dipole interactions. The reduced zero-field mobilities at 300 K are calculated using the Viehland and Mason theory [L.A. Viehland, S.L. Lin, E.A. Mason, At. Data Nucl. Data Tables, 60 (1995) 37-95], parameterised by a simple formula as a function of the mean hard-sphere cross section, and converted to diffusion coefficients using the Einstein relation. The method is tested on a set of experimental data for simple ions and cluster ions.
Hanni, Matti; Lantto, Perttu; Runeberg, Nino; Jokisaari, Jukka; Vaara, Juha
2004-09-22
Quantum chemical calculations of the nuclear shielding tensor, the nuclear quadrupole coupling tensor, and the spin-rotation tensor are reported for the Xe dimer using ab initio quantum chemical methods. The binary chemical shift delta, the anisotropy of the shielding tensor Delta sigma, the nuclear quadrupole coupling tensor component along the internuclear axis chi( parallel ), and the spin-rotation constant C( perpendicular ) are presented as a function of internuclear distance. The basis set superposition error is approximately corrected for by using the counterpoise correction (CP) method. Electron correlation effects are systematically studied via the Hartree-Fock, complete active space self-consistent field, second-order Møller-Plesset many-body perturbation, and coupled-cluster singles and doubles (CCSD) theories, the last one without and with noniterative triples, at the nonrelativistic all-electron level. We also report a high-quality theoretical interatomic potential for the Xe dimer, gained using the relativistic effective potential/core polarization potential scheme. These calculations used valence basis set of cc-pVQZ quality supplemented with a set of midbond functions. The second virial coefficient of Xe nuclear shielding, which is probably the experimentally best-characterized intermolecular interaction effect in nuclear magnetic resonance spectroscopy, is computed as a function of temperature, and compared to experiment and earlier theoretical results. The best results for the second virial coefficient, obtained using the CCSD(CP) binary chemical shift curve and either our best theoretical potential or the empirical potentials from the literature, are in good agreement with experiment. Zero-point vibrational corrections of delta, Delta sigma, chi (parallel), and C (perpendicular) in the nu=0, J=0 rovibrational ground state of the xenon dimer are also reported.
Variationally Optimized Free-Energy Flooding for Rate Calculation
McCarty, James; Valsson, Omar; Tiwary, Pratyush; Parrinello, Michele
2015-08-01
We propose a new method to obtain kinetic properties of infrequent events from molecular dynamics simulation. The procedure employs a recently introduced variational approach [Valsson and Parrinello, Phys. Rev. Lett. 113, 090601 (2014)] to construct a bias potential as a function of several collective variables that is designed to flood the associated free energy surface up to a predefined level. The resulting bias potential effectively accelerates transitions between metastable free energy minima while ensuring bias-free transition states, thus allowing accurate kinetic rates to be obtained. We test the method on a few illustrative systems for which we obtain an order of magnitude improvement in efficiency relative to previous approaches and several orders of magnitude relative to unbiased molecular dynamics. We expect an even larger improvement in more complex systems. This and the ability of the variational approach to deal efficiently with a large number of collective variables will greatly enhance the scope of these calculations. This work is a vindication of the potential that the variational principle has if applied in innovative ways.
Accurate Bit Error Rate Calculation for Asynchronous Chaos-Based DS-CDMA over Multipath Channel
Kaddoum, Georges; Roviras, Daniel; Chargé, Pascal; Fournier-Prunaret, Daniele
2009-12-01
An accurate approach to compute the bit error rate expression for multiuser chaosbased DS-CDMA system is presented in this paper. For more realistic communication system a slow fading multipath channel is considered. A simple RAKE receiver structure is considered. Based on the bit energy distribution, this approach compared to others computation methods existing in literature gives accurate results with low computation charge. Perfect estimation of the channel coefficients with the associated delays and chaos synchronization is assumed. The bit error rate is derived in terms of the bit energy distribution, the number of paths, the noise variance, and the number of users. Results are illustrated by theoretical calculations and numerical simulations which point out the accuracy of our approach.
Calculation of Rates of 4p–4d Transitions in Ar II
Alan Hibbert
2017-02-01
Full Text Available Recent experimental work by Belmonte et al. (2014 has given rates for some 4p–4d transitions that are significantly at variance with the previous experimental work of Rudko and Tang (1967 recommended in the NIST tabulations. To date, there are no theoretical rates with which to compare. In this work, we provide such theoretical data. We have undertaken a substantial and systematic configuration interaction calculation, with an extrapolation process applied to ab initio mixing coefficients, which gives energy differences in agreement with experiment. The length and velocity forms give values that are within 10%–15% of each other. Our results are in sufficiently close agreement with those of Belmonte et al. that we can confidently recommend that their results are much more accurate than the early results of Rudko and Tang, and should be adopted in place of the latter.
A. Parsaie
2017-01-01
Full Text Available Introduction: The study of rivers’ water quality is extremely important. This issue is more important when the rivers are one of the main sources of water supply for drinking, agriculture and industry. Unfortunately, river pollution has become one of the most important problems in the environment. When a source of pollution is transfused into the river, due to molecular motion, turbulence, and non-uniform velocity in cross-section of flow, it quickly spreads and covers all around the cross section and moves along the river with the flow. The governing equation of pollutant transmission in river is Advection Dispersion Equation (ADE. Computer simulation of pollution transmission in rives needs to solve the ADE by analytical or numerical approaches. The ADE has analytical solution under simple boundary and initial conditions but when the flow geometry and hydraulic conditions becomes more complex such as practical engineering problems, the analytical solutions are not applicable. Therefore, to solve this equation several numerical methods have been proposed. In this paper by getting the pollution transmission in the Severn River and Narew River was simulated. Materials and Methods: The longitudinal dispersion coefficient is proportional of properties of Fluid, hydraulic condition and the river geometry characteristics. For fluid properties the density and dynamic viscosity and for hydraulic condition, the velocity, flow depth, velocity and energy gradient slope and for river geometry the width of cross section and longitudinal slope can be mentioned. Several other parameters are influencive, but cannot be clearly measured such as sinuosity path and bed form of river. To derive the governed equation of pollution transmission in river, it is enough to consider an element of river and by using the continuity equation and Fick laws to balancing the inputs and outputs the pollution discharge. To calculate the dispersion coefficient several ways as
Effect of flow rate on the adsorption coefficient of radioactive krypton on activated carbon
Sun, L.S.C.; Underhill, D.W.
1981-01-01
For some time, there have been questions relative to the effect of carrier gas velocity on the adsorption coefficient for radioactive noble gases on activated charcoal. Resolution of these questions is particularly important in terms of developing standard procedures for determining such coefficients under laboratory conditions. Studies at the Harvard Air Cleaning Laboratory appear to confirm that the adsorption coefficient for radioactive krypton on activated charcoal is independent of the velocity of the carrier gas
Variational RRKM calculation of thermal rate constant for C–H bond fission reaction of nitro methane
Afshin Taghva Manesh
2017-02-01
Full Text Available The present work provides quantitative results for the rate constants of unimolecular C–H bond fission reactions in the nitro methane at elevated temperatures up to 2000 K. In fact, there are three different hydrogen atoms in the nitro methane. The potential energy surface for each C–H bond fission reaction of nitro methane was investigated by ab initio calculations. The geometry and vibrational frequencies of the species involved in this process were optimized at the MP2 level of theory, using the cc-pvdz basis set. Since C–H bond fission channel is a barrierless reaction, we have used variational RRKM theory to predict rate coefficients. By means of calculated rate coefficients at different temperatures, the Arrhenius expression of the channel over the temperature range of 100–2000 K is k(T = 5.9E19∗exp(−56274.6/T.
M.A. Chowdhury
2013-12-01
Full Text Available In the present study, friction coefficient and wear rate of gear fiber reinforced plastic (gear fiber and glass fiber reinforced plastic (glass fiber sliding against mild steel are investigated experimentally. In order to do so, a pin on disc apparatus is designed and fabricated. Experiments are carried out when smooth or rough mild steel pin slides on gear fiber and glass fiber disc. Experiments are conducted at normal load 10, 15 and 20 N, sliding velocity 1, 1.5 and 2 m/s and relative humidity 70%. Variations of friction coefficient with the duration of rubbing at different normal loads and sliding velocities are investigated. Results show that friction coefficient is influenced by duration of rubbing, normal load and sliding velocity. In general, friction coefficient increases for a certain duration of rubbing and after that it remains constant for the rest of the experimental time. The obtained results reveal that friction coefficient decreases with the increase in normal load for gear fiber and glass fiber mating with smooth or rough mild steel counterface. On the other hand, it is also found that friction coefficient increases with the increase in sliding velocity for both of the tested materials. Moreover, wear rate increases with the increase in normal load and sliding velocity. The magnitudes of friction coefficient and wear rate are different depending on sliding velocity and normal load for both smooth and rough counterface pin materials.
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
Calculation of thermodynamic properties and transport coefficients of C5F10O-CO2 thermal plasmas
Li, Xingwen; Guo, Xiaoxue; Murphy, Anthony B.; Zhao, Hu; Wu, Jian; Guo, Ze
2017-10-01
The thermodynamic properties and transport coefficients of C5F10O-CO2 gas mixtures, which are being considered as substitutes for SF6 in circuit breaker applications, are calculated for the temperature range from 300 K to 30 000 K and the pressure range from 0.05 MPa to 1.6 MPa. Special attention is paid on investigating the evolution of thermophysical properties of C5F10O-CO2 mixtures with different mixing ratios and with different pressures; both the mixing ratio and pressure significantly affect the properties. This is explained mainly in terms of the changes in the temperatures at which the dissociation and ionization reactions take place. Comparisons of different thermophysical properties of C5F10O-CO2 mixtures with those of SF6 are also carried out. It is found that most of the thermophysical properties of the C5F10O-CO2 mixtures, such as thermal conductivity, viscosity, and electrical conductivity, become closer to those of SF6 as the C5F10O concentration increases. The composition and thermophysical properties of pure C5F10O in the temperature range from 300 K to 2000 K based on the decomposition pathway are also given. The calculation results provide a basis for further study of the insulation and arc-quenching capability of C5F10O-CO2 gas mixtures as substitutes for SF6.
Loureiro, E.C.M.; Khoury, H.; Lima, F.R.A.
1998-01-01
The increasing utilization of oral X-rays, specially in youngsters and children, prompts the assessment of equivalent doses in their organs and tissues. With this purpose, Monte Carlo code was adopted to simulate an X-ray source irradiating phantoms of the MIRD-5 type with different ages (10, 15 and 40 years old) to calculate the conversion coefficients which transform the exposure at skin to equivalent doses at several organs and tissues of interest. In order to check the computer program, simulations were performed for adult patients using the original code (ADAM,FOR developed by GSF Germany) and the adapted program (MCDRO,PAS). Good agreement between results obtained by both programs was observed. Applications to incisive, canine and molar teeth were simulated. The conversion factors were calculated for the following organs and tissues: thyroid, active bone marrow (head and whole body), bone (facial skeleton, cranium and whole body), skin (head and whole body) and crystalline. Based on the obtained results, it follows that the younger the patient and the langer the field area, the higher the doses in assessed organs and tissues
Cranor, W.L.; Alvarez, D.A.; Huckins, J.N.; Petty, J.D.
2009-01-01
To fully utilize semipermeable membrane devices (SPMDs) as passive samplers in air monitoring, data are required to accurately estimate airborne concentrations of environmental contaminants. Limited uptake rate constants (kua) and no SPMD air partitioning coefficient (Ksa) existed for vapor-phase contaminants. This research was conducted to expand the existing body of kinetic data for SPMD air sampling by determining kua and Ksa for a number of airborne contaminants including the chemical classes: polycyclic aromatic hydrocarbons, organochlorine pesticides, brominated diphenyl ethers, phthalate esters, synthetic pyrethroids, and organophosphate/organosulfur pesticides. The kuas were obtained for 48 of 50 chemicals investigated and ranged from 0.03 to 3.07??m3??g-1??d-1. In cases where uptake was approaching equilibrium, Ksas were approximated. Ksa values (no units) were determined or estimated for 48 of the chemicals investigated and ranging from 3.84E+5 to 7.34E+7. This research utilized a test system (United States Patent 6,877,724 B1) which afforded the capability to generate and maintain constant concentrations of vapor-phase chemical mixtures. The test system and experimental design employed gave reproducible results during experimental runs spanning more than two years. This reproducibility was shown by obtaining mean kua values (n??=??3) of anthracene and p,p???-DDE at 0.96 and 1.57??m3??g-1??d-1 with relative standard deviations of 8.4% and 8.6% respectively.
Lenzen, Matthias; Merklein, Marion
2017-10-01
In the automotive sector, a major challenge is the deep-drawing of modern lightweight sheet metals with limited formability. Thus, conventional material models lack in accuracy due to the complex material behavior. A current field of research takes into account the evolution of the Lankford coefficient. Today, changes in anisotropy under increasing degree of deformation are not considered. Only a consolidated average value of the Lankford coefficient is included in conventional material models. This leads to an increasing error in prediction of the flow behavior and therefore to an inaccurate prognosis of the forming behavior. To increase the accuracy of the prediction quality, the strain dependent Lankford coefficient should be respected, because the R-value has a direct effect on the contour of the associated flow rule. Further, the investigated materials show a more or less extinct rate dependency of the yield stress. For this reason, the rate dependency of the Lankford coefficient during uniaxial tension is focused within this contribution. To quantify the influence of strain rate on the Lankford coefficient, tensile tests are performed for three commonly used materials, the aluminum alloy AA6016-T4, the advanced high strength steel DP800 and the deep drawing steel DC06 at three different strain rates. The strain measurement is carried out by an optical strain measurement system. An evolution of the Lankford coefficient was observed for all investigated materials. Also, an influence of the deformation velocity on the anisotropy could be detected.
Langenback, E.G.; Foster, W.M.; Bergofsky, E.H.
1989-01-01
We determined the overall external counting efficiency of radiolabeled particles deposited in the sheep lung. This efficiency permits the noninvasive calculation of the number of particles and microcuries from gamma-scintillation lung images of the live sheep. Additionally, we have calculated the attenuation of gamma radiation (120 keV) by the posterior chest wall and the gamma-scintillation camera collection efficiency of radiation emitted from the lung. Four methods were employed in our experiments: (1) by light microscopic counting of discrete carbonized polystyrene particles with a count median diameter (CMD) of 2.85 microns and tagged with cobalt-57, we delineated a linear relationship between the number of particles and the emitted counts per minute (cpm) detected by well scintillation counting; (2) from this conversion relationship we determined the number of particles inhaled and deposited in the lungs by scintillation counting fragments of dissected lung at autopsy; (3) we defined a linear association between the number of particles or microcuries contained in the lung and the emitted radiation as cpm detected by a gamma scintillation camera in the live sheep prior to autopsy; and (4) we compared the emitted radiation from the lungs of the live sheep to that of whole excised lungs in order to calculate the attenuation coefficient (ac) of the chest wall. The mean external counting efficiency was 4.00 X 10(4) particles/cpm (5.1 X 10(-3) microCi/cpm), the camera collection efficiency was 1 cpm/10(4) disintegrations per minute (dpm), and the ac had a mean of 0.178/cm. The external counting efficiency remained relatively constant over a range of particles and microcuries, permitting a more general use of this ratio to estimate number of particles or microcuries depositing after inhalation in a large mammalian lung if a similarly collimated gamma camera system is used
Bisetti, Fabrizio; El Morsli, Mbark
2012-01-01
Simulations of ion and electron transport in flames routinely adopt plasma fluid models, which require transport coefficients to compute the mass flux of charged species. In this work, the mobility and diffusion coefficient of thermal electrons
Current evaluation of dose rate calculation - analytical method
Tello, Marcos; Vilhena, Marco Tulio
1996-01-01
The accuracy of the dose calculations based on pencil beam formulas such as Fokker-Plank equations and Fermi equations for charged particle transport are studied and a methodology to solve the Boltzmann transport equation is suggested
Calculation of the decay rate of the proton
Ross, D.A.
1980-01-01
The SU(5) model of Georgi and Glashow is used for these calculations, being the simplist such model and since the point of unification of the strong, weak and electromagnetic interactions is very intensitive to the exact details of the model provided it obeys the desert hypothesis. The broad features of the calculation are common to all models with a dessert between the W-mass and unification
Wang, Wei; Shen, Jianqi
2018-06-01
The use of a shaped beam for applications relying on light scattering depends much on the ability to evaluate the beam shape coefficients (BSC) effectively. Numerical techniques for evaluating the BSCs of a shaped beam, such as the quadrature, the localized approximation (LA), the integral localized approximation (ILA) methods, have been developed within the framework of generalized Lorenz-Mie theory (GLMT). The quadrature methods usually employ the 2-/3-dimensional integrations. In this work, the expressions of the BSCs for an elliptical Gaussian beam (EGB) are simplified into the 1-dimensional integral so as to speed up the numerical computation. Numerical results of BSCs are used to reconstruct the beam field and the fidelity of the reconstructed field to the given beam field is estimated. It is demonstrated that the proposed method is much faster than the 2-dimensional integrations and it can acquire more accurate results than the LA method. Limitations of the quadrature method and also the LA method in the numerical calculation are analyzed in detail.
EFFECTS OF TIN ON HARDNESS, WEAR RATE AND COEFFICIENT OF FRICTION OF CAST CU-NI-SN ALLOYS
S. ILANGOVAN
2013-02-01
Full Text Available An investigation was carried out to understand the effects of Sn on hardness, wear rate and the coefficient of friction of spinodal Cu-Ni-Sn alloys. Alloys of appropriate compositions were melted in a crucible furnace under argon atmosphere and cast into sand moulds. Solution heat treated and aged specimens were tested for hardness, wear rate and the coefficient of friction. It was found that the hardness increases when the Sn content increases from 4% to 8% in the solution heat treated conditions. The peak aging time is found to decrease with an increase in the Sn content. Further, the coefficient of friction is independent of hardness whereas the wear rate decreases linearly with hardness irrespective of Sn content.
A paradox: The thermal rate coefficient for the H+DCl → HCl+D exchange reaction
Thompson, D.L.; Suzukawa, H.H. Jr.; Raff, L.M.
1975-01-01
Previously reported photolysis experiments indicate that the frequency factors associated with the hydrogen-exchange reactions H+DCl → HCl+D and D+HCl → DCl+H are on the order of 10 10 cm 3 /molcenter-dotsec. A series of unadjusted, quasiclassical trajectory calculations were been carried out to compute the thermal rate coefficients and activation parameters for a series of 13 thermal processes of the type A+BC → AB+C, where A=H, D, or Cl and BC=H 2 , D 2 , HCl, DCl, or Cl 2 . In addition, hot-atom yield ratios have been computed from the IRP equation for the reactions D*+DCl → D 2 +Cl, D*+Cl 2 → DCl + Cl as a function of the initial D* laboratory energy. The computations yield (1) hot-atom DCl/D 2 yield ratios within a factor of 2 of the experimental values; (2) thermal activation energies in satisfactory agreement with experiment for all processes investigated; and (3) frequency factors in reasonable accord with experiment for all the reactions except the hydrogen exchange reactions
42 CFR 413.312 - Methodology for calculating rates.
2010-10-01
... Determined Payment Rates for Low-Volume Skilled Nursing Facilities, for Cost Reporting Periods Beginning... routine service cost limits; (ii) A wage index to adjust for area wage differences; and (iii) The most... of rates published in the Federal Register under the authority of § 413.320, CMS announces the wage...
Herbst, E.; Leung, C.M.; Rensselaer Polytechnic Institute, Troy, NY)
1986-01-01
Pseudo-time-dependent models of the gas phase chemistry of dense interstellar clouds have been run with large rate coefficients for reactions between ions and polar neutral species, as advocated by Adams, Smith, and Clary. The higher rate coefficients normally lead to a reduction in both the peak and steady state abundances of polar neutrals, which can be as large as an order of magnitude but is more often smaller. Other differences between the results of these models and previous results are also discussed. 38 references
Quantum chemical and conventional TST calculations of rate constants for the OH + alkane reaction
Bravo-Perez, Graciela; Alvarez-Idaboy, J. Raul; Jimenez, Annia Galano; Cruz-Torres, Armando
2005-01-01
Reactions of OH with methane, ethane, propane, i-butane, and n-butane have been modeled using ab initio (MP2) and hybrid DFT (BHandHLYP) methods, and the 6-311G(d,p) basis set. Furthermore, single-point calculations at the CCSD(T) level were carried out at the optimized geometries. The rate constants have been calculated using the conventional transition-state theory (CTST). Arrhenius equations are proposed in the temperature range of 250-650 K. Hindered Internal Rotation partition functions calculations were explicitly carried out and included in the total partition functions. These corrections showed to be relevant in the determination of the pre-exponential parameters, although not so important as in the NO 3 + alkane reactions [G. Bravo-Perez, J.R. Alvarez-Idaboy, A. Cruz-Torres, M.E. Ruiz, J. Phys. Chem. A 106 (2002) 4645]. The explicit participation of the tunnel effect has been taken into account. The calculated rate coefficients provide a very good agreement with the experimental data. The best agreement for the overall alkane + OH reactions seemed to occur when the BHandHLYP geometries and partition functions are used. For propane and i-butane, in addition to the respective secondary and tertiary H-abstraction channels, the primary one has been considered. These pathways are confirmed to be significant in spite of the large differences in activation energies between primary and secondary or primary and tertiary channels, respectively of propane and i-butane reactions and should not be disregarded
Bourgeois, J; Lafore, P; Millot, J P; Rastoin, J; Vathaire, F de [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1959-07-01
1) The concept of an effective removal cross section has been developed in order more easily to compute reactor shielding thicknesses. We have built an experimental facility for the purpose of measuring effective removal cross sections, the value of which had not been published at that time. The first part of this paper describes the device or facility used, the computation method applied, and the results obtained. 2) Starting from this concept, we endeavoured to define a removal cross section as a function of energy. This enabled us to use the method for computations bearing on the attenuation of fast neutrons of any spectrum. An experimental verification was carried out for the case of fission neutrons filtered by a substantial thickness of graphite. 3) Finally, we outline a computation method enabling us to determine the sources of captured gamma rays by the age theory and we give an example of the application in a composite shield. (author) [French] 1) La notion de section efficace effective de deplacement a ete introduite pour calculer commodement les epaisseurs de protection des reacteurs. Nous avons construit un dispositif experimental destine a mesurer les sections efficaces effectives de deplacement dont la valeur n'avait pas ete publiee a cette epoque. La premiere partie de cette communication decrit le dispositif utilise, la methode de calcul employee et les resultats obtenus. 2) A partir de cette notion, nous avons essaye de definir une section efficace de deplacement fonction de l'energie. Ceci permet d'utiliser la methode du deplacement pour des calculs d'attenuation de neutrons rapides dont le spectre est quelconque. Une verification experimentale a ete faite dans le cas de neutrons de fission filtres par une epaisseur notable de graphite. 3) Enfin une methode de calcul permettant de determiner les sources de gamma de capture par la theorie de l'age est exposee et un exemple d'application donne dans une protection composite. (auteur)
Bourgeois, J; Lafore, P; Millot, J P; Rastoin, J; Vathaire, F de [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1958-07-01
1. The concept of an effective removal cross section has been developed in order more easily to compute reactor shielding thicknesses. We have built an experimental facility for the purpose of measuring effective removal cross sections, the value of which had not been published at that time. The first part of this paper describes the device or facility used, the computation method applied, and the results obtained. 2. Starting from this concept, we endeavored to define a removal cross section as a function of energy. This enabled us to use the method for computations bearing on the attenuation of fast neutrons of any spectrum. An experimental verification was carried out for the case of fission neutrons filtered by a substantial thickness of graphite. 3. Finally, we outline a computation method enabling us to determine the sources of captured gamma rays by the age theory and we give an example of the application in a composite shield. (author)Fren. [French] 1. La notion de section efficace effective de deplacement a ete introduite pour calculer commodement les epaisseurs de protection des reacteurs. Nous avons construit un dispositif experimental destine a mesurer les sections efficaces effectives de deplacement dont la valeur n'avait pas ete publiee a cette epoque. La premiere partie de cette communication decrit le dispositif utilise, la methode de calcul employee et les resultats obtenus. 2. A partir de cette notion, nous avons essaye de definir une section efficace de deplacement fonction de l'energie. Ceci permet d'utiliser la methode du deplacement pour des calculs d'attenuation de neutrons rapides dont le spectre est quelconque. Une verification experimentale a ete faite dans le cas de neutrons de fission filtres par une epaisseur notable de graphite. 3. Enfin une mde de calcul permettant de determiner les sources de gamma de capture par la theorie de l'age est exposee et un exemple d'application donne dans une protection composite. (auteur)
Tajima, Satomi; Hayashi, Toshio; Hori, Masaru
2015-02-26
The rate coefficient of F2 + NO → F + FNO is 2 to 5 orders of magnitude higher than that of F2 + NO2 → F + FNO2 even though bond energies of FNO and FNO2 only differ by ∼0.2 eV. To understand the cause of having different rate coefficients of these two reactions, the change in total energies was calculated by varying the stereochemical arrangement of F2 with respect to NOx (x = 1 or 2) by the density functional theory (DFT), using CAM-B3LYP/6-311 G+(d) in the Gaussian program. The permitted approaching angle between the x-axis and the plane consisting of O, N, F, and ϕ plays a key role to restrict the reaction of NO2 and F2 compared to the reaction of NO and F2. This restriction in the reaction space is considered to be the main cause of different rate coefficients depending on the selection of x = 1 or 2 of the reaction of F2 + NOx → F + FNOx, which was also confirmed by the difference in Si etch rate using the F formed by those reactions.
Lima, F.R.A.; Kramer, R.; Khoury, H.J.; Vieira, J.W.; Loureiro, E.C.M.; Hoff, G.
2004-01-01
Patient exposure from radiological examinations is usually quantified in terms of average absorbed dose or equivalent dose to certain radiosensitive organs of the human body. As these quantities cannot be measured in vivo, it is common practice to use physical or computational exposure models, which simulate the exposure to the patient in order to determine not only the quantities of interest (absorbed or equivalent dose), but also at the same time measurable quantities for the exposure conditions given. The ratio between a quantity of interest and a measurable quantity is called a conversion coefficient (CC), which is a function of the source and field parameters (tube voltage, filtration, field size, field position, focus-to-skin distance, etc.), the anatomical properties of the phantom, the elemental composition of relevant body tissues, and the radiation transport method applied. As the effective dose represents a sum over 23 risk-weighted organ and tissue equivalent doses, its determination practically implies the measurement or calculation of a complete distribution of equivalent doses throughout the human body. This task can be resolved most efficiently by means of computational exposure models, which consist of a virtual representation of the human body, also called phantom, connected to a Monte Carlo radiation transport computer code. The recently introduced MAX (Male Adult voXel) and FAXht (Female Adult voXel) head+trunk phantoms have been chosen for this task. With respect to their anatomical properties these phantoms correspond fairly well to the data recommended by the ICRP for the Reference Adult Male and Female. (author)
Santos, William S.; Neves, Lucio P.; Perini, Ana P.; Caldas, Linda V.E.; Maia, Ana F.
2014-01-01
Cardiac procedures are among the most common procedures in interventional radiology (IR), and can lead to high medical and occupational exposures, as in most cases are procedures complex and long lasting. In this work, conversion coefficients (CC) for the risk of cancer, normalized by kerma area product (KAP) to the patient, cardiologist and nurse were calculated using Monte Carlo simulation. The patient and the cardiologist were represented by anthropomorphic simulators MESH, and the nurse by anthropomorphic phantom FASH. Simulators were incorporated into the code of Monte Carlo MCNPX. Two scenarios were created: in the first (1), lead curtain and protective equipment suspended were not included, and in the second (2) these devices were inserted. The radiographic parameters employed in Monte Carlo simulations were: tube voltage of 60 kVp and 120 kVp; filtration of the beam and 3,5 mmAl beam area of 10 x 10 cm 2 . The average values of CCs to eight projections (in 10 -4 / Gy.cm 2 were 1,2 for the patient, 2,6E-03 (scenario 1) and 4,9E-04 (scenario 2) for cardiologist and 5,2E-04 (scenario 1) and 4,0E-04 (Scenario 2) to the nurse. The results show a significant reduction in CCs for professionals, when the lead curtain and protective equipment suspended are employed. The evaluation method used in this work can provide important information on the risk of cancer patient and professional, and thus improve the protection of workers in cardiac procedures of RI
Calculating Outcrossing Rates used in Decision Support Systems for Ships
Nielsen, Ulrik Dam
2008-01-01
Onboard decision support systems (DSS) are used to increase the operational safety of ships. Ideally, DSS can estimate - in the statistical sense - future ship responses on a time scale of the order of 1-3 hours taking into account speed and course changes. The calculations depend on both...... analysis, and the paper derives and describes the main ideas. The concept is illustrated by an example, where the limit state of a non-linear ship response is considered. The results from the parallel system analysis are in agreement with corresponding Monte Carlo simulations. However, the computational...
Gas-phase rate coefficients of the reaction of ozone with four sesquiterpenes at 295 ± 2 K.
Richters, Stefanie; Herrmann, Hartmut; Berndt, Torsten
2015-05-07
The rate coefficients of the reaction of ozone with the four atmospherically relevant sesquiterpenes β-caryophyllene, α-humulene, α-cedrene and isolongifolene were investigated at 295 ± 2 K and atmospheric pressure by at least two independent experimental investigations for each reaction. Relative rate experiments were carried out in a flow tube using two different experimental approaches with GC-MS detection (RR 1) and PTR-MS analysis (RR 2) as the analytical techniques. Absolute rate coefficients were determined in a stopped-flow experiment following the ozone depletion by means of UV spectroscopy. The average rate coefficients from the combined investigations representing the mean values of the different experimental methods are (unit: cm(3) molecule(-1) s(-1)): k(O3+β-caryophyllene) = (1.1 ± 0.3) × 10(-14) (methods: RR 1, RR 2, absolute), k(O3+α-humulene) = (1.2 ± 0.3) × 10(-14) (RR 1, RR 2), k(O3+α-cedrene) = (1.7 ± 0.5) × 10(-16) (RR 2, absolute) and k(O3+isolongifolene) = (1.1 ± 0.5) × 10(-17) (RR 2, absolute). The high ozonolysis rate coefficients for β-caryophyllene and α-humulene agree well with the results by Shu and Atkinson (Int. J. Chem. Kinet., 1994, 26) and lead to short atmospheric lifetimes of about two minutes with respect to the ozone reaction. The relatively small rate coefficients for α-cedrene and isolongifolene differ from the available literature values by a factor of about 2.5-6. Possible reasons for the deviations are discussed. Finally, calibrated sesquiterpene FT-IR spectra were recorded for the first time.
Calculation of multigroup reaction rates for the Ghana Research ...
The discrete ordinate spatial model, which pro-vides solution to the differential form of the transport equation by the Carlson-SN (N=4) approach was adopted to solve the Ludwig-Boltzmann multigroup neutron transport equation for this analysis. The results show that for any fissile resonance absorber, the reaction rates ...
Exact comparison of dose rate measurements and calculation of TN12/2 packages
Taniuchi, H.; Matsuda, F.
1998-01-01
Both of dose rate measurements of TN 12/2 package and calculations by Monte Carlo code MORSE in SCALE code system and MCNP were performed to evaluate the difference between the measurement and the calculation and finding out the cause of the difference. The calculated gamma-ray dose rates agreed well with measured ones, but calculated neutron dose rates overestimated more than a factor of 1.7. When considering the cause of the difference and applying the modification into the neutron calculation, the calculated neutron dose rates become to agree well, and the factor decreased to around 1.3. (authors)
Sample size calculation for comparing two negative binomial rates.
Zhu, Haiyuan; Lakkis, Hassan
2014-02-10
Negative binomial model has been increasingly used to model the count data in recent clinical trials. It is frequently chosen over Poisson model in cases of overdispersed count data that are commonly seen in clinical trials. One of the challenges of applying negative binomial model in clinical trial design is the sample size estimation. In practice, simulation methods have been frequently used for sample size estimation. In this paper, an explicit formula is developed to calculate sample size based on the negative binomial model. Depending on different approaches to estimate the variance under null hypothesis, three variations of the sample size formula are proposed and discussed. Important characteristics of the formula include its accuracy and its ability to explicitly incorporate dispersion parameter and exposure time. The performance of the formula with each variation is assessed using simulations. Copyright © 2013 John Wiley & Sons, Ltd.
Secondary standard dosimetry system with automatic dose/rate calculation
Duftschmid, K.E.; Bernhart, J.; Stehno, G.; Klosch, W.
1980-01-01
A versatile and automated secondary standard instrument has been designed for quick and accurate dose/rate measurement in a wide range of radiation intensity and quality (between 1 μR and 100 kR; 0.2 nC/kg - 20C/kg) for protection and therapy level dosimetry. The system is based on a series of secondary standard ionization chambers connected to a precision digital current integrator with microprocessor circuitry for data evaluation and control. Input of measurement parameters and calibration factors stored in an exchangeable memory chip provide computation of dose/rate values in the desired units. The ionization chambers provide excellent long-term stability and energy response and can be used with internal check sources to test validity of calibration. The system is a useful tool particularly for daily measurements in a secondary standard dosimetry laboratory or radiation therapy center. (H.K.)
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.
Christiansen, Jens; Klit, Peder; Vølund, Anders
2007-01-01
engine. The basic idea is to use the fluid film damping coefficients to estimate the film thickness variation for a piston ring under cyclic varying load. Reynolds Equation is solved for a piston ring and the oil film thickness is determined. In this analysis hydrodynamic lubrication is assumed......In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies Jorgen...
Pozníková, Gabriela; Fischer, Milan; Pohanková, Eva; Trnka, Miroslav
2014-01-01
Roč. 62, č. 5 (2014), s. 1079-1086 ISSN 1211-8516 R&D Projects: GA MŠk LH12037; GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : evapotranspiration * dual crop coefficient model * Bowen ratio/energy balance method * transpiration * soil evaporation * spring barley Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7)
Calculation of turnover rates in stable-isotope studies
Wootton, R.; Ford, G.C.; Cheng, K.N.; Halliday, D.
1985-01-01
In a comparison of glucose turnover measured with 2 H-glucose and with 13 C-glucose Tserng and Kalhan used five apparently different equations and obtained conflicting answers. There is, however, no difference in principle between the use of a stable isotope as a tracer and the use of a radioactive isotope, and the rate of appearance of tracee in a steady-state system (the turnover) can therefore be shown to be proportional to the equilibrium dilution of the infused tracer. Because the sensitivity of measurement of this dilution made using a gas chromatograph-mass spectrometer is lower than that made by radioactivity measurement, the contribution to the measured turnover rate due to the infusate cannot be neglected, as it usually is in radioisotope work. A convenient calibration curve to establish this dilution is the mole ratio of the pure infusate against the area ratio for the relevant ions. Tserng and Kalhan's apparently conflicting results for glucose-turnover using 13 C-glucose as the tracer can all be shown to amount to approximately 11.6 μmol min -1 kg -1 . This value is only slightly lower (0.05 2 H-glucose as the tracer and supports the use of 13 C-glucose as an alternative. (author)
Liu, Yuanrong; Chen, Weimin; Zhong, Jing
2017-01-01
The previously developed numerical inverse method was applied to determine the composition-dependent interdiffusion coefficients in single-phase finite diffusion couples. The numerical inverse method was first validated in a fictitious binary finite diffusion couple by pre-assuming four standard...... sets of interdiffusion coefficients. After that, the numerical inverse method was then adopted in a ternary Al-Cu-Ni finite diffusion couple. Based on the measured composition profiles, the ternary interdiffusion coefficients along the entire diffusion path of the target ternary diffusion couple were...... obtained by using the numerical inverse approach. The comprehensive comparisons between the computations and the experiments indicate that the numerical inverse method is also applicable to high-throughput determination of the composition-dependent interdiffusion coefficients in finite diffusion couples....
Okuno, Hiroshi
2003-01-01
A method for classifying benchmark results of criticality calculations according to similarity was proposed in this paper. After formulation of the method utilizing correlation coefficients, it was applied to burnup credit criticality benchmarks Phase III-A and II-A, which were conducted by the Expert Group on Burnup Credit Criticality Safety under auspices of the Nuclear Energy Agency of the Organisation for Economic Cooperation and Development (OECD/NEA). Phase III-A benchmark was a series of criticality calculations for irradiated Boiling Water Reactor (BWR) fuel assemblies, whereas Phase II-A benchmark was a suite of criticality calculations for irradiated Pressurized Water Reactor (PWR) fuel pins. These benchmark problems and their results were summarized. The correlation coefficients were calculated and sets of benchmark calculation results were classified according to the criterion that the values of the correlation coefficients were no less than 0.15 for Phase III-A and 0.10 for Phase II-A benchmarks. When a couple of benchmark calculation results belonged to the same group, one calculation result was found predictable from the other. An example was shown for each of the Benchmarks. While the evaluated nuclear data seemed the main factor for the classification, further investigations were required for finding other factors. (author)
Baasandorj, Munkhbayar; Ravishankara, A R; Burkholder, James B
2011-09-29
Rate coefficients, k, for the gas-phase reaction of the OH radical with (Z)-CF(3)CH═CHCF(3) (cis-1,1,1,4,4,4-hexafluoro-2-butene) were measured under pseudo-first-order conditions in OH using pulsed laser photolysis (PLP) to produce OH and laser-induced fluorescence (LIF) to detect it. Rate coefficients were measured over a range of temperatures (212-374 K) and bath gas pressures (20-200 Torr; He, N(2)) and found to be independent of pressure over this range of conditions. The rate coefficient has a non-Arrhenius behavior that is well-described by the expression k(1)(T) = (5.73 ± 0.60) × 10(-19) × T(2) × exp[(678 ± 10)/T] cm(3) molecule(-1) s(-1) where k(1)(296 K) was measured to be (4.91 ± 0.50) × 10(-13) cm(3) molecule(-1) s(-1) and the uncertainties are at the 2σ level and include estimated systematic errors. Rate coefficients for the analogous OD radical reaction were determined over a range of temperatures (262-374 K) at 100 Torr (He) to be k(2)(T) = (4.81 ± 0.20) × 10(-19) × T(2) × exp[(776 ± 15)/T], with k(2)(296 K) = (5.73 ± 0.50) × 10(-13) cm(3) molecule(-1) s(-1). OH radical rate coefficients were also measured at 296, 345, and 375 K using a relative rate technique and found to be in good agreement with the PLP-LIF results. A room-temperature rate coefficient for the O(3) + (Z)-CF(3)CH═CHCF(3) reaction was measured using an absolute method with O(3) in excess to be reaction was estimated to be ~20 days. Infrared absorption spectra of (Z)-CF(3)CH═CHCF(3) measured in this work were used to determine a (Z)-CF(3)CH═CHCF(3) global warming potential (GWP) of ~9 for the 100 year time horizon. A comparison of the OH reactivity of (Z)-CF(3)CH═CHCF(3) with other unsaturated fluorinated compounds is presented.
Toyoshima, S.; Noguchi, K.; Seto, H.; Shimizu, M.; Watanabe, N.
2000-01-01
To determine the relationship between apparent diffusion coefficient (ADC) values measured by diffusion-weighted MR imaging and split renal function determined by renal scintigraphy in patients with hydronephrosis. Material and Methods: Diffusion-weighted imaging on a 1.5 T MR unit and renal scintigraphy were performed in 36 patients with hydronephrosis (45 hydronephrotic kidneys, 21 non-hydronephrotic kidneys). ADC values of the individual kidneys were measured by diffusion-weighted MR imaging. Split renal function (glomerular filtration rate (GFR)) was determined by renal scintigraphy using 99m Tc-DTPA. The relationship between ADC values and split GFR was examined in 66 kidneys. The hydronephrotic kidneys were further classified into three groups (severe renal dysfunction, GFR 25 ml/min, n=28), and mean values for ADCs were calculated. Results: In hydronephrotic kidneys, there was a moderate positive correlation between ADC values and split GFR (R2=0.56). On the other hand, in non-hydronephrotic kidneys, poor correlation between ADC values and split GFR was observed (R2=0.08). The mean values for ADCs of the dysfunctioning hydronephrotic kidneys (severe renal dysfunction, 1.32x10 -3 ±0.18x10 -3 mm 2 /s; moderate renal dysfunction, 1.38x10 -3 ±0.10x10 -3 mm2/s) were significantly lower than that of the normal functioning hydronephrotic kidneys (1.63x10 -3 ±0.12±10 -3 mm 2 /s). Conclusion: These results indicated that measurement of ADC values by diffusion-weighted MR imaging has a potential value in the evaluation of the functional status of hydronephrotic kidneys
Photoionization cross sections and Auger rates calculated by many-body perturbation theory
Kelly, H.P.
1976-01-01
Methods for applying the many body perturbation theory to atomic calculations are discussed with particular emphasis on calculation of photoionization cross sections and Auger rates. Topics covered include: Rayleigh--Schroedinger theory; many body perturbation theory; calculations of photoionization cross sections; and Auger rates
Accurate quantum calculations of the reaction rates for H/D+ CH4
Harrevelt, R. van; Nyman, G.; Manthe, U.
2007-01-01
In previous work [T. Wu, H. J. Werner, and U. Manthe, Science 306, 2227 (2004)], accurate quantum reaction rate calculations of the rate constant for the H+CH4 -> CH3+H-2 reaction have been presented. Both the electronic structure calculations and the nuclear dynamics calculations are converged with
Avery, L. W.; Green, Sheldon
1989-01-01
Collisional excitation rates for C3H2, calculated using the coupled states approximation at temperatures of 10-30 K, are presented. C3H2 produces a number of spectral line pairs whose members are close together in frequency but arise from levels with different excitation energies. The rates are used in statistical equilibrium calculations to illustrate the excitation properties and density-dependent behavior of various C3H2 line ratios.
N R Rema
2017-08-01
Full Text Available In this paper, a multiwavelet based fingerprint compression technique using set partitioning in hierarchical trees (SPIHT algorithm with optimised prefilter coefficients is proposed. While wavelet based progressive compression techniques give a blurred image at lower bit rates due to lack of high frequency information, multiwavelets can be used efficiently to represent high frequency information. SA4 (Symmetric Antisymmetric multiwavelet when combined with SPIHT reduces the number of nodes during initialization to 1/4th compared to SPIHT with wavelet. This reduction in nodes leads to improvement in PSNR at lower bit rates. The PSNR can be further improved by optimizing the prefilter coefficients. In this work genetic algorithm (GA is used for optimizing prefilter coefficients. Using the proposed technique, there is a considerable improvement in PSNR at lower bit rates, compared to existing techniques in literature. An overall average improvement of 4.23dB and 2.52dB for bit rates in between 0.01 to 1 has been achieved for the images in the databases FVC 2000 DB1 and FVC 2002 DB3 respectively. The quality of the reconstructed image is better even at higher compression ratios like 80:1 and 100:1. The level of decomposition required for a multiwavelet is lesser compared to a wavelet.
31 CFR 356.21 - How are awards at the high yield or discount rate calculated?
2010-07-01
... discount rate calculated? 356.21 Section 356.21 Money and Finance: Treasury Regulations Relating to Money... high yield or discount rate calculated? (a) Awards to submitters. We generally prorate bids at the highest accepted yield or discount rate under § 356.20(a)(2) of this part. For example, if 80.15% is the...
Rossi, Lubianka Ferrari Russo
2014-07-01
The main target of this study is to introduce a new method for calculating the coefficients of sensibility through the union of differential method and generalized perturbation theory, which are the two methods generally used in reactor physics to obtain such variables. These two methods, separated, have some issues turning the sensibility coefficients calculation slower or computationally exhaustive. However, putting them together, it is possible to repair these issues and build a new equation for the coefficient of sensibility. The method introduced in this study was applied in a PWR reactor, where it was performed the sensibility analysis for the production and {sup 239}Pu conversion rate during 120 days (1 cycle) of burnup. The computational code used for both burnup and sensibility analysis, the CINEW, was developed in this study and all the results were compared with codes widely used in reactor physics, such as CINDER and SERPENT. The new mathematical method for calculating the sensibility coefficients and the code CINEW provide good numerical agility and also good efficiency and security, once the new method, when compared with traditional ones, provide satisfactory results, even when the other methods use different mathematical approaches. The burnup analysis, performed using the code CINEW, was compared with the code CINDER, showing an acceptable variation, though CINDER presents some computational issues due to the period it was built. The originality of this study is the application of such method in problems involving temporal dependence and, not least, the elaboration of the first national code for burnup and sensitivity analysis. (author)
Window Energy Rating System and Calculation of Energy Performance of Windows
Laustsen, Jacob Birck; Svendsen, Svend
The goal of reducing the energy consumption in buildings is the background for the introduction of an energy rating system of fenestration products in Denmark. The energy rating system requires that producers declare, among other things, the heat loss coefficient, U, and the total solar energy...... development, e.g. when the resulting effects of a reduced frame area are evaluated....
Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2014-07-01
Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)
Chang, T.; Torr, D.G.; Richards, P.G.; Solomon, S.C.
1993-01-01
O + ( 2 P) is an important species for studies of the ionosphere and thermosphere: its emission at 7320 angstrom can be used as a diagnostic of the thermospheric atomic oxygen density. Unfortunately, there are no laboratory measurements of the O and N 2 reaction rates which are needed to determine the major sinks of O + ( 2 P). The reaction rates that are generally used were determined from aeronomic data by Rusch et al. but there is evidence that several important inputs that they used should be changed. The authors have recalculated the O and N 2 reaction rates for O + ( 2 P) using recent improvements in the solar EUV flux, cross sections, and photoelectron fluxes. For the standard solar EUV flux, the new N 2 reaction rate of 3.4 ± 1.5 x 10 -10 cm 3 s -1 is close to the value obtained by Rusch et al., but the new O reaction rate of 4.0 ± 1.9 x 10 -10 cm 3 s -1 is about 8 times larger. These new reaction rates are derived using neutral densities, electron density, and solar EUV fluxes measured by Atmosphere Explorer C in 1974 during solar minimum. The new theoretical emission rates are in good agreement with the data for the two orbits studied by Rusch et al. and they are in reasonable agreement with data from five additional orbits that are used in this study. The authors have also examined the effect of uncertainties in the solar EUV flux on the derived reaction rates and found that 15% uncertainties in the solar flux could cause additional uncertainties of up to a factor of 1.5 in the O quenching rate. 19 refs., 4 figs., 8 tabs
Rate Coefficient Measurements and Theoretical Analysis of the OH + ( E) CF3CH=CHCF3 Reaction.
Baasandorj, Munkhbayar; Marshall, Paul; Waterland, Robert L; Ravishankara, Akkihebbal R; Burkholder, James B
2018-04-25
Rate coefficients, k, for the gas-phase reaction of the OH radical with (E) CF3CH=CHCF3 ((E)-1,1,14,4,4-hexafluoro-2-butene, HFO-1336mzz(E)) were measured over a range of temperature (211-374 K) and bath gas pressure (20-300 Torr; He, N2) using a pulsed laser photolysis-laser induced fluorescence (PLP-LIF) technique. k1(T) was independent of pressure over this range of conditions with k1(296 K) = (1.31 ± 0.15) × 10 13 cm3 molecule 1 s 1 and k1(T) = (6.94 ± 0.80) × 10 13 exp[ (496 ± 10)/T] cm3 molecule 1 s 1, where the uncertainties are 2 and the pre-exponential term includes estimated systematic error. Rate coefficients for the OD reaction were also determined over a range of temperature (262-374 K) at 100 Torr (He). The OD rate coefficients were ~15% greater than the OH values and showed similar temperature dependent behavior with k2(T) = (7.52 ± 0.44) × 10 13 exp[ (476 ± 20)/T] and k2(296 K) = (1.53 ± 0.15) × 10 13 cm3 molecule 1 s 1. The rate coefficients for reaction 1 were also measured using a relative rate technique between 296 and 375 K with k1(296 K) measured to be (1.22 ± 0.1) × 10 13 cm3 molecule 1 s 1 in agreement with the PLP-LIF results. In addition, the 296 K rate coefficient for the O3 + (E) CF3CH=CHCF3 reaction was determined to be reaction and the significant decrease in OH reactivity compared to the (Z) CF3CH=CHCF3 stereoisomer reaction. The estimated atmospheric lifetime of (E) CF3CH=CHCF3, due to loss by reaction with OH, is estimated to be ~90 days, while the actual lifetime will depend on the location and season of its emission. Infrared absorption spectra of (E) CF3CH=CHCF3 were measured and used to estimate the 100-year time horizon global warming potentials (GWP) of 32 (atmospherically well-mixed) and 14 (lifetime-adjusted).
Chang, T.; Torr, D. G.; Richards, P. G.; Solomon, S. C.
1993-01-01
O(+)(2P) is an important species for studies of the ionosphere and thermosphere: its emission at 7320 A can be used as a diagnostic of the thermospheric atomic oxygen density. Unfortunately, there are no laboratory measurements of the O and N2 reaction rates which are needed to determine the major sinks of (O+)(2p). We have recalculated the O and N2 reaction rates for O(+) (2P) using recent improvements in the solar EUV flux, cross sections, and photoelectron fluxes. For the standard solar EUV flux, the new N2 reaction rate of 3.4 +/- 1.5 x 10 exp -10 cu cm/s is close to the value obtained by Rusch et al. (1977), but the new O reaction rate of 4.0 +/- 1.9 x 10 exp -10 cu cm/sec is about 8 times larger. These new reaction rates are derived using neutral densities, electron density, and solar EUV fluxes measured by Atmosphere Explorer C in 1974 during solar minimum. The new theoretical emission rates are in good agreement with the data for the two orbits studied by Rusch et al.
Tone, Tatsuzo
1978-07-01
Described are the reactivity coefficient of D-T fusion reaction, slowing-down processes of deuterons injected with high energy and 3.52 MeV alpha particles generated in D-T reaction, and the power balance in a Tokamak reactor plasma. Most of the results were obtained in the first preliminary design of JAERI Experimental Fusion Reactor (JXFR) driven with stationary neutral beam injection. A manual of numerical computation program ''BALTOK'' developed for the calculations is given in the appendix. (auth.)
Garcia, F; Arruda-Neto, J D; Manso, M V; Helene, O M; Vanin, V R; Rodriguez, O; Mesa, J; Likhachev, V P; Filho, J W; Deppman, A; Perez, G; Guzman, F; de Camargo, S P
1999-10-01
A new and simple statistical procedure (STATFLUX) for the calculation of transfer coefficients of radionuclide transport to animals and plants is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. By using experimentally available curves of radionuclide concentrations versus time, for each animal compartment (organs), flow parameters were estimated by employing a least-squares procedure, whose consistency is tested. Some numerical results are presented in order to compare the STATFLUX transfer coefficients with those from other works and experimental data.
Garcia, F.; Manso, M.V.; Rodriguez, O.; Mesa, J.; Arruda-Neto, J.D.T.; Helene, O.M.; Vanin, V.R.; Likhachev, V.P.; Pereira Filho, J.W.; Deppman, A.; Perez, G.; Guzman, F.; Camargo, S.P. de
1999-01-01
A new and simple statistical procedure (STATFLUX) for the calculation of transfer coefficients of radionuclide transport to animals and plants is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. By using experimentally available curves of radionuclide concentrations versus time, for each animal compartment (organs), flow parameters were estimated by employing a least-squares procedure, whose consistency is tested. Some numerical results are presented in order to compare the STATFLUX transfer coefficients with those from other works and experimental data. (author)
Zhong, Ruibo; Yuan, Ming; Gao, Haiyang; Bai, Zhijun; Guo, Jun; Zhao, Xinmin; Zhang, Feng
2016-03-01
Discrete biomolecule-nanoparticle (NP) conjugates play paramount roles in nanofabrication, in which the key is to get the precise molar extinction coefficient of NPs. By making best use of the gift from a specific separation phenomenon of agarose gel electrophoresis (GE), amphiphilic polymer coated NP with exact number of bovine serum albumin (BSA) proteins can be extracted and further experimentally employed to precisely calculate the molar extinction coefficient of the NPs. This method could further benefit the evaluation and extraction of any other dual-component NP-containing bio-conjugates.
Measurements of Drag Coefficients and Rotation Rates of Free-Falling Helixes
Al-Omari, Abdulrhaman A.
2016-05-01
The motion of bacteria in the environment is relevant to several fields. At very small scales and with simple helical shapes, we are able to describe experimentally and mathematically the motion of solid spirals falling freely within a liquid pool. Using these shapes we intend to mimic the motion of bacteria called Spirochetes. We seek to experimentally investigate the linear and the rotational motion of such shapes. A better understanding of the dynamics of this process will be practical not only on engineering and physics, but the bioscience and environmental as well. In the following pages, we explore the role of the shape on the motion of passive solid helixes in different liquids. We fabricate three solid helical shapes and drop them under gravity in water, glycerol and a mixture of 30% glycerol in water. That generated rotation due to helical angle in water. However, we observe the rotation disappear in glycerol. The movement of the solid helical shapes is imaged using a high-speed video camera. Then, the images are analyzed using the supplied software and a computer. Using these simultaneous measurements, we examine the terminal velocity of solid helical shapes. Using this information we computed the drag coefficient and the drag force. We obtain the helical angular velocity and the torque applied to the solid. The results of this study will allow us to more accurately predict the motion of solid helical shape. This analysis will also shed light onto biological questions of bacteria movement.
Lu, J.; Zhang, X.; Zhao, X.
2000-01-01
Relativistic discrete-variational local density functional calculations on endohedral Gd rate at C 60 , La rate at C 60 ,Gd rate at C 74 , and La rate at C 74 are performed. All the C 60 - and C 74 -derived levels are lowered upon endohedral Gd and La doping. Both the Gd (4f 7 5d 1 6s 2 ) and La (5d 1 6s 2 ) atoms only donate their two 6s valence electrons to the cages, leaving behind their 5d electrons when they are placed at the cage centers. Compared with large-band-gap C 60 , small-band-gap C 74 and Gd (La)-metallofullerenes have strong both electron-donating and electron-accepting characters, and the calculated ionization potentials and electron affinities for them agree well with the available experimental data. (orig.)
Sun, Wei; Chou, Chih-Ping; Stacy, Alan W; Ma, Huiyan; Unger, Jennifer; Gallaher, Peggy
2007-02-01
Cronbach's a is widely used in social science research to estimate the internal consistency of reliability of a measurement scale. However, when items are not strictly parallel, the Cronbach's a coefficient provides a lower-bound estimate of true reliability, and this estimate may be further biased downward when items are dichotomous. The estimation of standardized Cronbach's a for a scale with dichotomous items can be improved by using the upper bound of coefficient phi. SAS and SPSS macros have been developed in this article to obtain standardized Cronbach's a via this method. The simulation analysis showed that Cronbach's a from upper-bound phi might be appropriate for estimating the real reliability when standardized Cronbach's a is problematic.
A Review of Rate Coefficients in the D2-F2 Chemical Laser System
1977-08-05
analyzed by subjecting the mixture to a high-frequency dis- charge, then using EPR to assay the relative H and D atom concentrations. The rate...856 ( 1935 ). Anlauf, K. G. , P. E. Charters, D. S. Home, R. G. MacDonald, D. II. Maylotte, J. C. Polanyi, W. J
40 CFR 75.83 - Calculation of Hg mass emissions and heat input rate.
2010-07-01
... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Calculation of Hg mass emissions and... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Hg Mass Emission Provisions § 75.83 Calculation of Hg mass emissions and heat input rate. The owner or operator shall calculate Hg mass emissions...
Calculation of radiation dose rate arisen from radionuclide contained in building materials
Lai Tien Thinh; Nguyen Hao Quang
2008-01-01
This paper presents some results that we used MCNP5 program to calculate radiation dose rate arisen from radionuclide in building materials. Since then, the limits of radionuclide content in building materials are discussed. The calculation results by MCNP are compared with those calculated by analytical method. (author)
Jachic, J.
1985-01-01
It is presented the ONEDM neutronic simulator for RZ spatial calculation, two energy groups, aiming at researching and optimization of a low power fast reactor design. The simulator's methodology is based in RZ calculation from radial and axial calculation iteractively coupled and in macroscopic cross sections corrected by power density and asymmetry of the spectrum in the feedback process with phase library for reference neutronic state. The transversal area which are determined by energy groups and material region in the iteration are introduced in the spatial calculation. The simulator efficiency is tested and compared with the CITATION and 2DB codes. The cross sections are generated by 1DX code. (M.C.K.) [pt
The calculation of coolant leak rate through the cracks using RELAP5 code
Krungeleviciute, V.; Kaliatka, A.
2001-01-01
For reason to choose method of leak detection first of all it is necessary to perform evaluating thermal-hydraulic calculations. These calculations allow to determine flow rate of discharged coolant. For coolant leak rate calculations through possible cracks in Ignalina NPP pipes SQUIRT and RELAP5 thermal-hydraulic codes were used. SQUIRT is well known as computer program that predicts the leakage for cracked pipes in NPP. As this code calculates only water (at subcooled or saturated conditions) leak rate, RELAP5 code model, that calculates water and steam leak rate, was created. For model validation comparison of SQUIRT, RELAP5 and experimental results was performed. Analysis shows RELAP5 code model suitability for calculations of leak through through-wall cracks in pipes. (author)
HU TA
2009-10-26
Assess the steady-state flammability level at normal and off-normal ventilation conditions. The hydrogen generation rate was calculated for 177 tanks using the rate equation model. Flammability calculations based on hydrogen, ammonia, and methane were performed for 177 tanks for various scenarios.
Y. Bakhshan
2015-01-01
Full Text Available Micro scale gas flows has attracted significant research interest in the last two decades. In this research, the fluid flow of gases in the stepped micro-channel at a wide range of Knudsen number has been analyzed with using the Lattice Boltzmann (MRT method. In the model, a modified second-order slip boundary condition and a Bosanquet-type effective viscosity are used to consider the velocity slip at the boundaries and to cover the slip and transition regimes of flow and to gain an accurate simulation of rarefied gases. It includes the slip and transition regimes of flow. The flow specifications such as pressure loss, velocity profile, streamline and friction coefficient at different conditions have been presented. The results show good agreement with available experimental data. The calculation shows that the friction coefficient decreases with increasing the Knudsen number and stepping the micro-channel has an inverse effect on the friction coefficient. Furthermore, a new correlation is suggested for calculation of the friction coefficient in the stepped micro-channel as below: C_f Re = 3.113+2.915/(1 +2 Kn+ 0.641 exp(3.203/(1 + 2 Kn
Tang, Junqi; Gao, Kunpeng; Ou, Quanhong; Fu, Xuewen; Man, Shi-Qing; Guo, Jie; Liu, Yingkai
2018-02-01
Gold nanoparticles (AuNPs) have been researched extensively, such as applied in various biosensors, biomedical imaging and diagnosis, catalysis and physico-chemical analysis. These applications usually required to know the nanoparticle size or concentration. Researchers have been studying a simply and quick way to estimate the concentration or size of nanoparticles from their optical spectra and SPR feature for several years. The extinction cross-sections and the molar attenuation coefficient were one of the key parameters. In this study, we calculated the extinction cross-sections and molar attenuation coefficient (decadic molar extinction coefficient) of small gold nanoparticles by dipole approximation method and modified Beer-Lambert law. The theoretical result showed that the surface plasmon resonance peak of small gold nanoparticles was blueshift with an increase size. Moreover, small AuNPs (sub-10 nm) were prepared by using of dextran or trisodium citrate as reducing agent and capping agent. The experimental synthesized AuNPs was also shows a blueshift as increasing particle size in a certain range. And the concentration of AuNPs was calculated based on the obtained molar attenuation coefficient. For small nanoparticles, the size of nanoparticles and surface plasmon resonance property was not showed a positive correlation compared to larger nanoparticles. These results suggested that SPR peak depended not only on the nanoparticle size and shape but also on the nanoparticles environment.
Determination of the rate coefficient for the N2/+/ + O reaction in the ionosphere
Torr, D. G.; Torr, M. R.; Orsini, N.; Hanson, W. B.; Hoffman, J. H.; Walker, J. C. G.
1977-01-01
Using approximately 400 simultaneous measurements of ion and neutral densities and temperatures, and the spectrum of the solar flux measured by the Atmosphere Explorer C satellite, we have determined the rate constant k1 for the reaction between N2(+) and O in the ionosphere for ion temperatures between 600 and 700 K. We find that k1 = 1.1 x 10 to the minus 10th power cu cm per sec, with a standard deviation of + or - 15%. If we use the temperature dependence for this reaction determined in the laboratory then at 300 K we find excellent agreement with the recommended laboratory value.
Elay, A.G.
1978-01-01
A method to compare calculated and experimental neutron attenuation coefficients (chi) when samples are o, different geometries but the same material is proposed. The best Σ (total removal cross section) is determined by using the fact that the logarithm of the attenuation coefficient varies linearly with respect to Σ i.e. lg chi = + asub(s) Σ, where asub(s) is a parameter that characterises all the geometrical experimental conditions of the neutron source, the sample and the relative source-to-sample geometry. In order to increase the precision, samples of different geometries but the same material were used. Values of chi are determined experimentally and asub(s) calculated for these geometries. The graph of lg chi as a function of asub(s) together with a simple fit to a straight line is sufficient to determine Σ (the slope of the line). (T.G.)
Calculation methods for dissolution rate of multicomponent alloys during electrochemical machining
Dikusar, A.I.; Petrenko, V.I.; Dikusar, G.K.; Ehngel'gardt, G.R.; Michukova, N.Yu.
1981-01-01
The possibility of theoretical calculation of metal dissolution rate during electrochemical mashining is considered. Two calculation techniques are compared at the example of two-component W-Re, Ni-W, Mo-Re alloys, namely: ''charge superposition'' and ''weight percents''. It is concluded that the technique of ''charge superposition'' is the only grounded calculation technique of specific rates of dissolution for alloys [ru
Oh, Seungtaik; Jeong, Il Kwon
2015-11-16
We will introduce a new simple analytic formula of the Fourier coefficient of the 3D field distribution of a point light source to generate a cylindrical angular spectrum which captures the object wave in 360° in the 3D Fourier space. Conceptually, the cylindrical angular spectrum can be understood as a cylindrical version of the omnidirectional spectral approach of Sando et al. Our Fourier coefficient formula is based on an intuitive observation that a point light radiates uniformly in all directions. Our formula is defined over all frequency vectors lying on the entire sphere in the 3D Fourier space and is more natural and computationally more efficient for all around recording of the object wave than that of the previous omnidirectional spectral method. A generalized frequency-based occlusion culling method for an arbitrary complex object is also proposed to enhance the 3D quality of a hologram. As a practical application of the cylindrical angular spectrum, an interactive hologram example is presented together with implementation details.
Hoobler, Ray J.; Leone, Stephen R.
1997-01-01
Rate coefficients for the reactions of C2H + HCN yields products and C2H + CH3CN yields products have been measured over the temperature range 262-360 K. These experiments represent an ongoing effort to accurately measure reaction rate coefficients of the ethynyl radical, C2H, relevant to planetary atmospheres such as those of Jupiter and Saturn and its satellite Titan. Laser photolysis of C2H2 is used to produce C2H, and transient infrared laser absorption is employed to measure the decay of C2H to obtain the subsequent reaction rates in a transverse flow cell. Rate constants for the reaction C2H + HCN yields products are found to increase significantly with increasing temperature and are measured to be (3.9-6.2) x 10(exp 13) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 297-360 K. The rate constants for the reaction C2H + CH3CN yields products are also found to increase substantially with increasing temperature and are measured to be (1.0-2.1) x 10(exp -12) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 262-360 K. For the reaction C2H + HCN yields products, ab initio calculations of transition state structures are used to infer that the major products form via an addition/elimination pathway. The measured rate constants for the reaction of C2H + HCN yields products are significantly smaller than values currently employed in photochemical models of Titan, which will affect the HC3N distribution.
Endres, Eric S; Lakhmanskaya, Olga; Hauser, Daniel; Huber, Stefan E; Best, Thorsten; Kumar, Sunil S; Probst, Michael; Wester, Roland
2014-08-21
In the interstellar medium (ISM) ion–molecule reactions play a key role in forming complex molecules. Since 2006, after the radioastronomical discovery of the first of by now six interstellar anions, interest has grown in understanding the formation and destruction pathways of negative ions in the ISM. Experiments have focused on reactions and photodetachment of the identified negatively charged ions. Hints were found that the reactions of CnH(–) with H2 may proceed with a low (rate [Eichelberger, B.; et al. Astrophys. J. 2007, 667, 1283]. Because of the high abundance of molecular hydrogen in the ISM, a precise knowledge of the reaction rate is needed for a better understanding of the low-temperature chemistry in the ISM. A suitable tool to analyze rare reactions is the 22-pole radiofrequency ion trap. Here, we report on reaction rates for Cn(–) and CnH(–) (n = 2, 4, 6) with buffer gas temperatures of H2 at 12 and 300 K. Our experiments show the absence of these reactions with an upper limit to the rate coefficients between 4 × 10(–16) and 5 × 10(–15) cm(3) s(–1), except for the case of C2(–), which does react with a finite rate with H2 at low temperatures. For the cases of C2H(–) and C4H(–), the experimental results were confirmed with quantum chemical calculations. In addition, the possible influence of a residual reactivity on the abundance of C4H(–) and C6H(–) in the ISM were estimated on the basis of a gas-phase chemical model based on the KIDA database. We found that the simulated ion abundances are already unaffected if reaction rate coefficients with H2 were below 10(–14) cm(3) s(–1).
M.A. Chowdhury; D.M. Nuruzzaman; B.K. Roy; S. Samad; R. Sarker; A.H.M. Rezwan
2013-01-01
In the present study, friction coefficient and wear rate of gear fiber reinforced plastic (gear fiber) and glass fiber reinforced plastic (glass fiber) sliding against mild steel are investigated experimentally. In order to do so, a pin on disc apparatus is designed and fabricated. Experiments are carried out when smooth or rough mild steel pin slides on gear fiber and glass fiber disc. Experiments are conducted at normal load 10, 15 and 20 N, sliding velocity 1, 1.5 and 2 m/s and relative h...
Borges, Antonio Andrade
1998-07-01
A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating theses coefficients, which are the differential and the generalized perturbation theory methods. The method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivatives of the integral parameter, {phi}, with respect to {sigma} are calculated using the perturbation method and the functional derivatives of this generic integral parameter with respect to {sigma} and {phi} are calculated using the differential method. (author)
Audit Calculations of LBLOCA for Ulchin Unit 1 and 2 Power Up rate
Kang, Donggu; Huh, Byunggil; Yoo, Seunghunl; Yang, Chaeyong; Seul, Kwangwon [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2013-05-15
The KINS-Realistic Evaluation Model (KINS-REM) was developed for the independent audit calculation in 1991, and the code accuracy and statistical method have been improved. To support the licensing review and to confirm the validity of licensee's calculation, regulatory auditing calculations have been also conducted. Currently, the modification of Ulchin 1 and 2 operating license for 4.5% power up rate is under review. In this study, the regulatory audit calculation for LBLOCA of Ulchin Unit 1 and 2 with 4.5% power up rate was performed by applying KINS-REM. In this study, the regulatory audit calculation for LBLOCA of Ulchin Unit 1 and 2 with 4.5% power up rate was performed by applying KINS-REM. It is confirmed that the analysis results of LBLOCA for Ulchin 1 and 2 power up rate meets the PCT acceptance criteria.
Sakamoto, Y
2002-01-01
In the prevention of nuclear disaster, there needs the information on the dose equivalent rate distribution inside and outside the site, and energy spectra. The three dimensional radiation transport calculation code is a useful tool for the site specific detailed analysis with the consideration of facility structures. It is important in the prediction of individual doses in the future countermeasure that the reliability of the evaluation methods of dose equivalent rate distribution and energy spectra by using of Monte Carlo radiation transport calculation code, and the factors which influence the dose equivalent rate distribution outside the site are confirmed. The reliability of radiation transport calculation code and the influence factors of dose equivalent rate distribution were examined through the analyses of critical accident at JCO's uranium processing plant occurred on September 30, 1999. The radiation transport calculations including the burn-up calculations were done by using of the structural info...
Onel, L; Blitz, M A; Seakins, P W
2012-04-05
Monoethanol amine (H2NCH2CH2OH, MEA) has been proposed for large-scale use in carbon capture and storage. We present the first absolute, temperature-dependent determination of the rate coefficient for the reaction of OH with MEA using laser flash photolysis for OH generation, monitoring OH removal by laser-induced fluorescence. The room-temperature rate coefficient is determined to be (7.61 ± 0.76) × 10(-11) cm(3) molecule(-1) s(-1), and the rate coefficient decreases by about 40% by 510 K. The temperature dependence of the rate coefficient is given by k1= (7.73 ± 0.24) × 10(-11)(T/295)(-(0.79±0.11)) cm(3) molecule(-1) s(-1). The high rate coefficient shows that gas-phase processing in the atmosphere will be competitive with uptake onto aerosols.
Tchakoua, Théophile; Nkot Nkot, Pierre René; Fifen, Jean Jules; Nsangou, Mama; Motapon, Ousmanou
2018-06-01
We present the first potential energy surface (PES) for the AlO(X2Σ+)-He(1 S) van der Waals complex. This PES has been calculated at the RCCSD(T) level of theory. The mixed Gaussian/Exponential Extrapolation Scheme of complete basis set [CBS(D,T,Q)] was employed. The PES was fitted using global analytical method. This fitted PES was used subsequently in the close-coupling approach for the computation of the state-to-state collisional excitation cross sections of the fine-structure levels of the AlO-He complex. Collision energies were taken up to 2500 cm-1 and they yield after thermal averaging, state-to-state rate coefficients up to 300 K. The propensity rules between the lowest fine-structure levels were studied. These rules show, on one hand, a strong propensity in favour of odd ΔN transitions, and on the other hand, that cross sections and collisional rate coefficients for Δj = ΔN transitions are larger than those for Δj ≠ ΔN transitions.
Meijer, A.
1990-01-01
The chemical interactions of dissolved radionuclides with mineral surfaces along flowpaths from the proposed repository to the accessible environment around Yucca Mountain constitute one of the potential barriers to radionuclide migration at the site. Our limited understanding of these interactions suggests their details will be complex and will involve control by numerous chemical and physical parameters. It appears unlikely that we will understand all the details of these reactions or obtain all the site data required to evaluate each of them in the time available for site characterization. Yet, performance assessment calculations will require some form of coupling of chemical interaction models will hydrologic flow models for the site. Clearly, strategies will be needed to bound the problem without compromising the reliability of the performance assessment calculations required for site suitability analysis. The main purpose of this paper is to describe such a strategy. 39 refs., 7 figs., 5 tabs
Mahdi Alajmi
2015-07-01
Full Text Available The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE, Graphite/Epoxy composites (GE, and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE. The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific wear rate (SWR and coefficient of friction (COF of composites. In general, graphite as an additive to polymeric composite has had an eclectic effect on mechanical properties, whereas it has led to a positive effect on tribological properties, whilst date palm fibers (DPFs, as reinforcement for polymeric composite, promoted a mechanical performance with a slight improvement to the tribological performance. Statistically, this study reveals that there is no strong confirmation of any marked correlation between the mechanical and the specific wear rate of filler/Epoxy composites. There is, however, a remarkable correlation between the mechanical properties and the friction coefficient of filler/Epoxy composites.
Alajmi, Mahdi; Shalwan, Abdullah
2015-07-08
The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE), Graphite/Epoxy composites (GE), and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE). The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific wear rate (SWR) and coefficient of friction (COF) of composites. In general, graphite as an additive to polymeric composite has had an eclectic effect on mechanical properties, whereas it has led to a positive effect on tribological properties, whilst date palm fibers (DPFs), as reinforcement for polymeric composite, promoted a mechanical performance with a slight improvement to the tribological performance. Statistically, this study reveals that there is no strong confirmation of any marked correlation between the mechanical and the specific wear rate of filler/Epoxy composites. There is, however, a remarkable correlation between the mechanical properties and the friction coefficient of filler/Epoxy composites.
FABGEN, a transient power-generation and isotope birth rate calculator
Roland, H.C.
1975-04-01
A description is given of the FABGEN program, a fast-running program for calculating fuel element power-generation rates and selected fission product birth rates in a known neutron flux as functions of time. A first forward difference calculation is used, and the time step is one day. Provisions are made for including various fuel element lengths, variation of thermal flux with time, and use of different fertile isotopes. Five different fission products may be specified for birth-rate calculations. A daily summary may be output, or totals by days may be accumulated for final output. (U.S.)
Calculation of Nonlinear Thermoelectric Coefficients of InAs1-xSbx Using Monte Carlo Method
Sadeghian, RB; Bahk, JH; Bian, ZX; Shakouri, A
2011-12-28
It was found that the nonlinear Peltier effect could take place and increase the cooling power density when a lightly doped thermoelectric material is under a large electrical field. This effect is due to the Seebeck coefficient enhancement from an electron distribution far from equilibrium. In the nonequilibrium transport regime, the solution of the Boltzmann transport equation in the relaxation-time approximation ceases to apply. The Monte Carlo method, on the other hand, proves to be a capable tool for simulation of semiconductor devices at small scales as well as thermoelectric effects with local nonequilibrium charge distribution. InAs1-xSb is a favorable thermoelectric material for nonlinear operation owing to its high mobility inherited from the binary compounds InSb and InAs. In this work we report simulation results on the nonlinear Peltier power of InAs1-xSb at low doping levels, at room temperature and at low temperatures. The thermoelectric power factor in nonlinear operation is compared with the maximum value that can be achieved with optimal doping in the linear transport regime.
Crawford, James; Neretnieks, Ivars; Malmstroem, Maria
2006-10-01
SKB is currently preparing licence applications related to the proposed deep repository for spent nuclear fuel as well as the encapsulation plant required for canister fabrication. The present report is one of several specific data reports that form the data input to an interim safety report (SR-Can) for the encapsulation plant licence application. This report concerns the derivation and recommendation of generic K d data (i.e. linear partitioning coefficients) for safety assessment modelling of far-field radionuclide transport in fractured granitic rock. The data are derived for typical Swedish groundwater conditions and rock types distinctive of those found on the Simpevarp peninsula and Forsmark. Data have been derived for 8 main elements (Cs, Sr, Ra, Ni, Th, U, Np, Am) and various oxidation states. The data have also been supplied with tentative correction factors to account for artefacts that have not been previously considered in detail in previous compilations. For the main reviewed solutes the data are given in terms of a best estimate K d value assumed to be the median of the aggregate set of selected data. A range corresponding to the 25-75% inter-quartile range is also specified and probable ranges of uncertainty are estimated in the form of an upper and lower limit to the expected variability. Data for an additional 19 elements that have not been reviewed are taken from a previous compilation by Carbol and Engkvist
Rate Coefficient for the (4)Heμ + CH4 Reaction at 500 K: Comparison between Theory and Experiment.
Arseneau, Donald J; Fleming, Donald G; Li, Yongle; Li, Jun; Suleimanov, Yury V; Guo, Hua
2016-03-03
The rate constant for the H atom abstraction reaction from methane by the muonic helium atom, Heμ + CH4 → HeμH + CH3, is reported at 500 K and compared with theory, providing an important test of both the potential energy surface (PES) and reaction rate theory for the prototypical polyatomic CH5 reaction system. The theory used to characterize this reaction includes both variational transition-state (CVT/μOMT) theory (VTST) and ring polymer molecular dynamics (RPMD) calculations on a recently developed PES, which are compared as well with earlier calculations on different PESs for the H, D, and Mu + CH4 reactions, the latter, in particular, providing for a variation in atomic mass by a factor of 36. Though rigorous quantum calculations have been carried out for the H + CH4 reaction, these have not yet been extended to the isotopologues of this reaction (in contrast to H3), so it is important to provide tests of less rigorous theories in comparison with kinetic isotope effects measured by experiment. In this regard, the agreement between the VTST and RPMD calculations and experiment for the rate constant of the Heμ + CH4 reaction at 500 K is excellent, within 10% in both cases, which overlaps with experimental error.
El-Maaref, A.A., E-mail: ahmed.maaref@azhar.edu.eg; Saddeek, Y.B.; Abou halaka, M.M.
2017-02-15
Highlights: • Fine-structure calculations of sulfurlike Mn have been performed using configuration interaction technique, CI. • The relativistic effects, Breit-Pauli Hameltonian, have been correlated to the CI calculations. • Excitation rates by electron impact of the Mn X ion have been evaluated up to ionization potential. - Abstract: Fine-structure calculations of energies and transition parameters have been performed using the configuration interaction technique (CI) as implemented in CIV3 code for sulfurlike manganese, Mn X. The calculations are executed in an intermediate coupling scheme using the Breit-Pauli Hamiltonian. As well as, energy levels and oscillator strengths are calculated using LANL code, where the calculations by LANL have been used to estimate the accuracy of the present CI calculations. The calculated energy levels, oscillator strengths, and lifetimes are in reasonable agreement with the published experimental and theoretical values. Electron impact excitation rates of the transitions emit soft X-ray and extreme ultraviolet (EUV) wavelengths have been evaluated. The level population densities are calculated using the collisional radiative model (CRM), as well. The collisional excitation rates and collision strengths have been calculated in the electron temperature range ≤ the ionization potential, ∼1–250 eV.
2011-04-12
... consistently the term ``regular hours.'' The term ``regular hours'' refers to the hours during regular working... during non-overtime and non-holiday hours of operation. Official establishments and official egg products.... FSIS developed proposed formulas in consultation with a private accounting firm to determine the rates...
Taranenko, V.; Xu, X.G.
2008-01-01
Radiation protection of pregnant females and the foetus against ionising radiation is of particular importance to radiation protection due to high foetal radiosensitivity. The only available set of foetal conversion coefficients for photons is based on stylised models of simplified anatomy. Using the RPI-P series of pregnant female and foetus models representing 3-, 6- and 9-month gestation, a set of new fluence to absorbed foetal dose conversion coefficients has been calculated. The RPI-P anatomical models were developed using novel 3D geometry modelling techniques. Organ masses were adjusted to agree within 1% with the ICRP reference data for a pregnant female. Monte Carlo dose calculations were carried out using the MCNPX and Penelope codes for external 50 keV-10 GeV photon beams of six standard configurations. The models were voxelised at 3-mm voxel resolution. Conversion coefficients were tabulated for the three gestational periods for the whole foetus and brain. Comparison with previously published data showed deviations up to 120% for the foetal doses at 50 keV. The discrepancy can be primarily ascribed to anatomical differences. Comparison with published data for five major mother organs is also provided for the 3-month model. Since the RPI-P models exhibit a high degree of anatomical realism, the reported dataset is recommended as a reference for radiation protection of the foetus against external photon exposure. (authors)
Webster, J W [International Atomic Energy Agency, Vienna (Austria)
1962-03-15
The development of the formulae of perturbation theory provides a good opportunity to use one of the principal devices of mathematical heuristics, i.e. proceeding by analogy from something that is simple to something that is more complicated. This paper: (a) Reviews the formulation of perturbation theory as a method of calculating reactivity coefficients; this consists mainly of developing the differential equation for the adjoint flux, as a continuous function of position and lethargy, by proceeding by analogy from the one-group differential equation for adjoint flux. (b) Presents an application of the two-group form of perturbation theory to a boiling-mercury-cooled fast-breeder reactor (MCBR). It is seen that the net Hg density coefficient of reactivity for the first-design-try for the MCBR is negative for some regions and positive for others. However, it is negative for regions of highest statistical weight and where the density change for a power change would be the greatest. The overall Hg density coefficient is thus negative, i.e. the void coefficient is positive-an unsafe condition. It can be easily seen from the two-group formulation what design changes had to be made to obtain a design which would have a negative void coefficient. It developed in subsequent investigations that there were such design changes that could be made and a design of the MCBR with a negative void coefficient was eventually achieved. (author) [French] La mise au points des formules de la theorie des perturbations fournit une bonne occasion d'employer en mathematiques une des principales regles de la methode heuristique, celle qui consiste a proceder par analogie du simple au complexe. L'auteur du memoire: a) Expose une methode permettant de calculer les coefficients de reactivite en utilisant les formules de la theorie des perturbations; en substance, cette methode consiste a developper l'equation differentielle relative au flux adjoint en fonction continue de la position et de la
Relativistic quasiparticle random-phase approximation calculation of total muon capture rates
Marketin, T.; Paar, N.; Niksic, T.; Vretenar, D.
2009-01-01
The relativistic proton-neutron quasiparticle random phase approximation (pn-RQRPA) is applied in the calculation of total muon capture rates on a large set of nuclei from 12 C to 244 Pu, for which experimental values are available. The microscopic theoretical framework is based on the relativistic Hartree-Bogoliubov (RHB) model for the nuclear ground state, and transitions to excited states are calculated using the pn-RQRPA. The calculation is fully consistent, i.e., the same interactions are used both in the RHB equations that determine the quasiparticle basis, and in the matrix equations of the pn-RQRPA. The calculated capture rates are sensitive to the in-medium quenching of the axial-vector coupling constant. By reducing this constant from its free-nucleon value g A =1.262 by 10% for all multipole transitions, the calculation reproduces the experimental muon capture rates to better than 10% accuracy.
Shapiro, A; Lin, B I [Cincinnati Univ., Ohio (USA). Dept. of Chemical and Nuclear Engineering; Windham, J P; Kereiakes, J G
1976-07-01
..gamma.. flux density and dose rate distributions have been calculated about implantable californium-252 sources for an infinite tissue medium. Point source flux densities as a function of energy and position were obtained from a discrete-ordinates calculation, and the flux densities were multiplied by their corresponding kerma factors and added to obtain point source dose rates. The point dose rates were integrated over the line source to obtain line dose rates. Container attenuation was accounted for by evaluating the point dose rate as a function of platinum thickness. Both primary and secondary flux densities and dose rates are presented. The agreement with an independent Monte Carlo calculation was excellent. The data presented should be useful for the design of new source configurations.
Modeling for Dose Rate Calculation of the External Exposure to Gamma Emitters in Soil
Allam, K. A.; El-Mongy, S. A.; El-Tahawy, M. S.; Mohsen, M. A.
2004-01-01
Based on the model proposed and developed in Ph.D thesis of the first author of this work, the dose rate conversion factors (absorbed dose rate in air per specific activity of soil in nGy.hr - 1 per Bq.kg - 1) are calculated 1 m above the ground for photon emitters of natural radionuclides uniformly distributed in the soil. This new and simple dose rate calculation software was used for calculation of the dose rate in air 1 m above the ground. Then the results were compared with those obtained by five different groups. Although the developed model is extremely simple, the obtained results of calculations, based on this model, show excellent agreement with those obtained by the above-mentioned models specially that one adopted by UNSCEAR. (authors)
Distorted wave approach to calculate Auger transition rates of ions in metals
Deutscher, Stefan A. E-mail: sad@utk.edu; Diez Muino, R.; Arnau, A.; Salin, A.; Zaremba, E
2001-08-01
We evaluate the role of target distortion in the determination of Auger transition rates for multicharged ions in metals. The required two electron matrix elements are calculated using numerical solutions of the Kohn-Sham equations for both the bound and continuum states. Comparisons with calculations performed using plane waves and hydrogenic orbitals are presented.
Quade, U.
1994-01-01
Neutron- und Gamma dose rate calculations were performed for the storage containers filled with plutonium nitrate of the MOX fabrication facility of Siemens. For the particle transport calculations the Monte Carlo Code MCNP 4.2 was used. The calculated results were compared with experimental dose rate measurements. It can be stated that the choice of the code system was appropriate since all aspects of the many facettes of the problem were well reproduced in the calculations. The position dependency as well as the influence of the shieldings, the reflections and the mutual influences of the sources were well described by the calculations for the gamma and for the neutron dose rates. However, good agreement with the experimental results on the gamma dose rates could only be reached when the lead shielding of the detector was integrated into the geometry modelling of the calculations. For some few cases of thick shieldings and soft gamma ray sources the statistics of the calculational results were not sufficient. In such cases more elaborate variance reduction methods must be applied in future calculations. Thus the MCNP code in connection with NGSRC has been proven as an effective tool for the solution of this type of problems. (orig./HP) [de
A modified Gaussian integration method for thermal reaction rate calculation in U- and Pu-isotopes
Bosevski, T.; Fredin, B.
1966-01-01
An advanced multi-group cell calculations a lot of data information is very often necessary, and hence the data administration will be elaborate, and the spectrum calculation will be time consuming. We think it is possible to reduce the necessary data information by using an effective reaction rate integration method well suited for U- and Pu-absorptions (author)
Dusciac D.
2016-01-01
Full Text Available In this work, we present the results of the first part of a research project aimed at offering a complete response to dosimeters providers and nuclear physicists’ demands for high-energy (6 – 9 MeV photon beams for radiation protection purposes. Classical facilities allowing the production of high-energy photonic radiation (proton accelerators, nuclear reactors are very rare and need large investment for development and use. A novel solution is proposed, consisting in the use of a medical linear accelerator, allowing a significant decrease of all costs.Using Monte Carlo simulations (MCNP5 and PENELOPE codes, a specifically designed electron-photon conversion target allowing for obtaining a high energy photon beam (with an average energy weighted by fluence of about 6 MeV has been built for radiation protection purposes. Due to the specific design of the target, this “realistic” radiation protection high-energy photon beam presents a uniform distribution of air kerma rate at a distance of 1 m, over a 30 × 30 cm2 surface. Two graphite cavity ionizing chambers for ionometric measurements have been built. For one of these chambers, the charge collection volume has been measured allowing for its use as a primary standard. The second ionizing chamber is used as a transfer standard; as such it has been calibrated in a 60Co beam, and in the high energy photon beam for radiation protection.The measurements with these ionizing chambers allowed for an evaluation of the air kerma rate in the LINAC based high-energy photon beam for radiation protection: the values cover a range between 36 mGy/h and 210 mGy/h, compatible with radiation protection purposes.Finally, using Monte Carlo simulations, conversion coefficients from air kerma to dose equivalent quantities have been calculated in the range between 10 keV and 22.4 MeV, for the spectral distribution of the fluence corresponding to the beam produced by the linear accelerator of the LNE-LNHB.
Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction
Hwang, S. M.; Cooke, J. A.; De Witt, K. J.; Rabinowitz, M. J.
2010-01-01
Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux).
Hu, Haiyang; Wang, Qiang
2018-07-01
A new strategy for grouping spectral absorption coefficients, considering the influences of both temperature and species mole ratio inhomogeneities on correlated-k characteristics of the spectra of gas mixtures, has been deduced to match the calculation method of spectral overlap parameter used in multiscale multigroup wide band k-distribution model. By comparison with current spectral absorption coefficient grouping strategies, for which only the influence of temperature inhomogeneity on the correlated-k characteristics of spectra of single species was considered, the improvements in calculation accuracies resulting from the new grouping strategy were evaluated using a series of 0D cases in which radiance under 3-5-μm wave band emitted by hot combustion gas of hydrocarbon fuel was attenuated by atmosphere with quite different temperature and mole ratios of water vapor and carbon monoxide to carbon dioxide. Finally, evaluations are presented on the calculation of remote sensing thermal images of transonic hot jet exhausted from a chevron ejecting nozzle with solid wall cooling system.
Paula Leite, Rodolfo; Freitas, Rodrigo; Azevedo, Rodolfo; de Koning, Maurice
2016-11-01
The Uhlenbeck-Ford (UF) model was originally proposed for the theoretical study of imperfect gases, given that all its virial coefficients can be evaluated exactly, in principle. Here, in addition to computing the previously unknown coefficients B11 through B13, we assess its applicability as a reference system in fluid-phase free-energy calculations using molecular simulation techniques. Our results demonstrate that, although the UF model itself is too soft, appropriately scaled Uhlenbeck-Ford (sUF) models provide robust reference systems that allow accurate fluid-phase free-energy calculations without the need for an intermediate reference model. Indeed, in addition to the accuracy with which their free energies are known and their convenient scaling properties, the fluid is the only thermodynamically stable phase for a wide range of sUF models. This set of favorable properties may potentially put the sUF fluid-phase reference systems on par with the standard role that harmonic and Einstein solids play as reference systems for solid-phase free-energy calculations.
Imre, K.; Odian, G.
1979-01-01
The effect of diffusion on radiation-initiated graft polymerization has been studied with emphasis on the single- and two-penetrant cases. When the physical properties of the penetrants are similar, the two-penetrant problems can be reduced to the single-penetrant problem by redefining the characteristic parameters of the system. The diffusion-free graft polymerization rate is assumed to be proportional to the upsilon power of the monomer concentration respectively, and, in which the proportionality constant a = k/sub p/R/sub i//sup w//k/sub t//sup z/, where k/sub p/ and k/sub t/ are the propagation and termination rate constants, respectively, and R/sub i/ is the initiation rate. The values of upsilon, w, and z depend on the particular reaction system. The results of earlier work were generalized by allowing a non-Fickian diffusion rate which predicts an essentially exponential dependence on the monomer concentration of the diffusion coefficient, D = D 0 [exp(deltaC/M)], where M is the saturation concentration. A reaction system is characterized by the three dimensionless parameters, upsilon, delta, and A = (L/2)[aM/sup (upsilon--1)//D 0 ]/sup 1/2/, where L is the polymer film thickness. Graft polymerization tends to become diffusion controlled as A increases. Larger values of delta and ν cause a reaction system to behave closer to the diffusion-free regime. Transition from diffusion-free to diffusion-controlled reaction involves changes in the dependence of the reaction rate on film thickness, initiation rate, and monomer concentration. Although the diffusion-free rate is w order in initiation rate, upsilon order in monomer, and independent of film thickness, the diffusion-controlled rate is w/2 order in initiator rate and inverse first-order in film thickness. Dependence of the diffusion-controlled rate on monomer is dependent in a complex manner on the diffusional characteristics of the reaction system. 11 figures, 4 tables
Liu, Dapeng
2017-01-10
Reaction rate coefficients for the reaction of hydroxyl (OH) radicals with nine large branched alkanes (i.e., 2-methyl-3-ethyl-pentane, 2,3-dimethyl-pentane, 2,2,3-trimethylbutane, 2,2,3-trimethyl-pentane, 2,3,4-trimethyl-pentane, 3-ethyl-pentane, 2,2,3,4-tetramethyl-pentane, 2,2-dimethyl-3-ethyl-pentane, and 2,4-dimethyl-3-ethyl-pentane) are measured at high temperatures (900-1300 K) using a shock tube and narrow-line-width OH absorption diagnostic in the UV region. In addition, room-temperature measurements of six out of these nine rate coefficients are performed in a photolysis cell using high repetition laser-induced fluorescence of OH radicals. Our experimental results are combined with previous literature measurements to obtain three-parameter Arrhenius expressions valid over a wide temperature range (300-1300 K). The rate coefficients are analyzed using the next-nearest-neighbor (N-N-N) methodology to derive nine tertiary (T003, T012, T013, T022, T023, T111, T112, T113, and T122) site-specific rate coefficients for the abstraction of H atoms by OH radicals from branched alkanes. Derived Arrhenius expressions, valid over 950-1300 K, are given as (the subscripts denote the number of carbon atoms connected to the next-nearest-neighbor carbon): T003 = 1.80 × 10-10 exp(-2971 K/T) cm3 molecule-1 s-1; T012 = 9.36 × 10-11 exp(-3024 K/T) cm3 molecule-1 s-1; T013 = 4.40 × 10-10 exp(-4162 K/T) cm3 molecule-1 s-1; T022 = 1.47 × 10-10 exp(-3587 K/T) cm3 molecule-1 s-1; T023 = 6.06 × 10-11 exp(-3010 K/T) cm3 molecule-1 s-1; T111 = 3.98 × 10-11 exp(-1617 K/T) cm3 molecule-1 s-1; T112 = 9.08 × 10-12 exp(-3661 K/T) cm3 molecule-1 s-1; T113 = 6.74 × 10-9 exp(-7547 K/T) cm3 molecule-1 s-1; T122 = 3.47 × 10-11 exp(-1802 K/T) cm3 molecule-1 s-1.
Pham Van, Tat; Deiters, Ulrich K.
2015-01-01
Highlights: • We construct the angular orientations of dimers H 2 −H 2 and H 2 −O 2 . • We calculate the ab initio intermolecular interaction energies for all built orientations. • Extrapolating the interaction energies to the complete basis set limit aug-cc-pV23Z. • We develop two 5-site ab initio intermolecular potentials of dimers H 2 −H 2 , H 2 −O 2 . • Calculating the virial coefficients of dimer H 2 −H 2 and H 2 −O 2 . - Abstract: The intermolecular interaction potentials of the dimers H 2 −H 2 and H 2 −O 2 were calculated from quantum mechanics, using coupled-cluster theory CCSD(T) and correlation-consistent basis sets aug-cc-pVmZ (m = 2, 3); the results were extrapolated to the basis set limit aug-cc-pV23Z. The interaction energies were corrected for the basis set superposition error with the counterpoise scheme. For comparison also Møller–Plesset perturbation theory (at levels 2–4) with the basis sets aug-cc-pVTZ were considered, but the results proved inferior. The quantum mechanical results were used to construct analytical pair potential functions. From these functions the second virial coefficients of hydrogen and the cross virial coefficients of the hydrogen–oxygen system were obtained by integration; in both cases corrections for quantum effects were included. The results agree well with experimental data, if available, or with empirical correlations
Sunder, S.; Shoesmith, D.W.; Kolar, M.; Leneveu, D.M.
1998-01-01
Calculation of used nuclear fuel dissolution rates in a geological disposal vault requires a knowledge of the redox conditions in the vault. For redox conditions less oxidizing than those causing UO 2 oxidation to the U 3 O 7 , stage, a thermodynamically-based model is appropriate. For more oxidizing redox conditions a kinetic or an electrochemical model is needed to calculate these rates. The redox conditions in a disposal vault will be affected by the radiolysis of groundwater by the ionizing radiation associated with the fuel. Therefore, we have calculated the alpha-, beta- and gamma-dose rates in water in contact with the reference used fuel in the Canadian Nuclear Fuel Waste Management Program (CNFWMP) as a function of cooling time. Also, we have determined dissolution rates of UO 2 fuel as a function of alpha and gamma dose rates from our electrochemical measurements. These room-temperature rates are used to calculate the dissolution rates of used fuel at 100 o C, the highest temperature expected in a container in the CNFWMP, as a function of time since emplacement. It is shown that beta radiolysis of water will be the main cause of oxidation of used CANDU fuel in a failed container. The use of a kinetic or an electrochemical corrosion model, to calculate fuel dissolution rates, is required for a period of ∼1000 a following emplacement of copper containers in the geologic disposal vault envisaged in the CNFWMP. Beyond this time period a thermodynamically-based model adequately predicts the fuel dissolution rates. The results presented in this paper can be adopted to calculate used fuel dissolution rates for other used UO 2 fuels in other waste management programs. (author)
Reexamining the Dissolution of Spent Fuel: A Comparison of Different Methods for Calculating Rates
Hanson, Brady D.; Stout, Ray B.
2004-01-01
Dissolution rates for spent fuel have typically been reported in terms of a rate normalized to the surface area of the specimen. Recent evidence has shown that neither the geometric surface area nor that measured with BET accurately predicts the effective surface area of spent fuel. Dissolution rates calculated from results obtained by flowthrough tests were reexamined comparing the cumulative releases and surface area normalized rates. While initial surface area is important for comparison of different rates, it appears that normalizing to the surface area introduces unnecessary uncertainty compared to using cumulative or fractional release rates. Discrepancies in past data analyses are mitigated using this alternative method
Torr, D. G.; Torr, M. R.
1980-01-01
Atmosphere Explorer-C satellite measurements are used to determine rate coefficients (RCs) for the following reactions: O(+)(D-2) + N2 yields N2(+) + O (reaction 1), O(+)(D-2) + N2 yields O(+)(S-4) + N2 (reaction 2), and O(+)(D-2) + N2 yields NO(+) + N (reaction 3). Results show the RC for reaction 1 to be 1 (plus 1 or minus 0.5) x 10 to the -10th cu cm per sec, for reaction 2 to be 3 (plus 1 or minus 2) x 10 to the -11th cu cm per sec, and 3 to be less than 5.5 x 10 to the -11th cu cm per sec. It is also found that the reaction of O(+)(D-2) with N2 does not constitute a detectable source of NO(+) ions in the thermosphere.
Calculation of nuclide inventory, decay power, activity and dose rates for spent nuclear fuel
Haakansson, Rune
2000-03-01
The nuclide inventory was calculated for a BWR and a PWR fuel element, with burnups of 38 and 55 MWd/kg uranium for the BWR fuel, and 42 and 60 MWd/kg uranium for the PWR fuel. The calculations were performed for decay times of up to 300,000 years. Gamma and neutron dose rates have been calculated at a distance of 1 m from a bare fuel element and outside the spent fuel canister. The calculations were performed using the CASMO-4 code
HLW disposal by fission reactors; calculation of trans-mutation rate and recycle
Mulyanto
1997-01-01
Transmutation of MA (Minor actinide) and LLFPS (long-lived fission products) into stable nuclide or short-lived isotopes by fission reactors seem to become an alternative technology for HLW disposal. in this study, transmutation rate and recycle calculation were developed in order to evaluate transmutation characteristics of MA and LLFPs in the fission reactors. inventory of MA and LLFPs in the transmutation reactors were determined by solving of criticality equation with 1-D cylindrical geometry of multigroup diffusion equations at the beginning of cycle (BOC). transmutation rate and burn-up was determined by solving of depletion equation. inventory of MA and LLFPs was calculated for 40 years recycle. From this study, it was concluded that characteristics of MA and LLFPs in the transmutation reactors can be evaluated by recycle calculation. by calculation of transmutation rate, performance of fission reactor for transmutation of MA or LLFPs can be discussed
Ruiz, Rafael O.; Di Liscia, Marcelo H.; Diaz, Sergio E. [Universidad Simon Bolivar, Sartendejas, Baruta (Venezuela)
2007-11-15
The identification of the dynamic coefficients in air bearings is fundamental for a suitable roto-dynamic analysis. The present paper shows the development of an algorithm that allows the direct obtaining of the dynamic coefficients in hydrodynamic air bearings as much of numerical form as experimental. The testing bench used consists of two magnetic bearings, which support the rotor in their ends and work as well as actuators allowing inducing controlled orbits in the rotor. The test bearing is located between the magnetic bearings. The dynamic forces generated in the air bearing are registered from three load cells. The algorithm was developed in a commercial code of graphical programming, through which the signals can be collected, controlled and processed. The nonlinear behavior of this type of bearings makes difficult the calculation of the dynamic coefficients, therefore the processing of the signals in frequencial space facilitates, in a certain way, its handling. On the other hand, the numerical model was compared with the experimental results obtaining acceptable approaches in magnitude as well as in behavior. The numerical dynamic coefficients calculation was realized solving the Reynolds differential equation for a compressible fluid in the thickness of the gas film, taking into consideration the fluid mass flow that is introduced, as well as the pressure loss suffered by the same in passing through the feeding orifices. The numerical methods utilized include the solution of the differential equation of Reynolds for finite differences, the calculation of the profile realizing successive iterations and the calculation of the hydrodynamics forces through the Simpson numerical integration. The numerical dynamic coefficients were found applying a minimum squared technique to the hydrodynamic stresses generated in simulating an orbit of the rotor at a determined frequency and velocity, allowing in this way the calculation of the synchronous and asynchronous
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
Preliminary calculations on the cooling rate of the Renca batholit, Sierra de San Luis, Argentina
Lopez de Luchi, M.G.; Ostera, H.A.; Linares, E; Rosello, E.A
2001-01-01
Cooling rates can be used to constrain the unroofing history of plutonic-metamorphic system. Geocronological cooling rates (Spear and Parrish, 1996) can be unravelled using age calculations on minerals that were open systems and subsequently passed through their closure temperatures (Dodson, 1973) during cooling. Several age determinations on different minerals are needed in order to accurately constrain the cooling path of a pluton (Hodges 1991, Spear and Parrish, 1996 and references therein). Isotopic open-system behaviour in minerals can be modelled as volume diffusion process (Hodges, 1991 and references therein), which depends on the cooling rate of the whole system. We present the first results on the calculation of the cooling rate of the Renca batholith on the basis of the combination of both thermometric calculations and available crystallization and cooling ages (au)
Jamet, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1964-07-01
Following on to work started in a previous report, the author carries out in the case of few examples, the calculation of the transmission coefficient T using accurate methods. He then deduces from this the error in the B K W method. The calculations are carried out for values of T ranging down to 10{sup -200}. The use of modern computers makes it possible to obtain values of T to eight decimal places in a few seconds and the practical advantage of the B K W approximation appears therefore considerably reduced. The author gives also a method which may be used for an exact calculation of the energy levels of a potential well. (author) [French] Poursuivant une etude commencee dans une note anterieure, l'auteur effectue, sur quelques exemples, le calcul du coefficient de transmission T par des methodes exactes. Il en deduit ensuite l'erreur de la methode B K W. Les calculs sont faits pour des valeurs de T allant jusqu'a 10{sup -200}. L'utilisation des machines a calculer modernes permettant d'obtenir en quelques secondes, la valeur de T avec 8 decimales exactes, l'interet pratique de l'approximation B K W semble considerablement diminue. L'auteur indique egalement une methode qui peut servir a calculer exactement les niveaux d'energie d'un puits de potentiel. (auteur)
Takemine, S.; Rikimaru, A.; Takahashi, K.
The rice is one of the staple foods in the world High quality rice production requires periodically collecting rice growth data to control the growth of rice The height of plant the number of stem the color of leaf is well known parameters to indicate rice growth Rice growth diagnosis method based on these parameters is used operationally in Japan although collecting these parameters by field survey needs a lot of labor and time Recently a laborsaving method for rice growth diagnosis is proposed which is based on vegetation cover rate of rice Vegetation cover rate of rice is calculated based on discriminating rice plant areas in a digital camera image which is photographed in nadir direction Discrimination of rice plant areas in the image was done by the automatic binarization processing However in the case of vegetation cover rate calculation method depending on the automatic binarization process there is a possibility to decrease vegetation cover rate against growth of rice In this paper a calculation method of vegetation cover rate was proposed which based on the automatic binarization process and referred to the growth hysteresis information For several images obtained by field survey during rice growing season vegetation cover rate was calculated by the conventional automatic binarization processing and the proposed method respectively And vegetation cover rate of both methods was compared with reference value obtained by visual interpretation As a result of comparison the accuracy of discriminating rice plant areas was increased by the proposed
Implementation of Online Promethee Method for Poor Family Change Rate Calculation
Aji, Dhady Lukito; Suryono; Widodo, Catur Edi
2018-02-01
This research has been done online calculation of the rate of poor family change rate by using Preference Ranking Method of Organization Of Enrichment Evaluation (PROMETHEE) .This system is very useful to monitor poverty in a region as well as for administrative services related to poverty rate. The system consists of computer clients and servers connected via the internet network. Poor family residence data obtained from the government. In addition, survey data are inputted through the client computer in each administrative village and also 23 criteria of input in accordance with the established government. The PROMETHEE method is used to evaluate the value of poverty and its weight is used to determine poverty status. PROMETHEE output can also be used to rank the poverty of the registered population of the server based on the netflow value. The poverty rate is calculated based on the current poverty rate compared to the previous poverty rate. The rate results can be viewed online and real time on the server through numbers and graphs. From the test results can be seen that the system can classify poverty status, calculate the poverty rate change rate and can determine the value and poverty ranking of each population.
Implementation of Online Promethee Method for Poor Family Change Rate Calculation
Lukito Aji Dhady
2018-01-01
Full Text Available This research has been done online calculation of the rate of poor family change rate by using Preference Ranking Method of Organization Of Enrichment Evaluation (PROMETHEE .This system is very useful to monitor poverty in a region as well as for administrative services related to poverty rate. The system consists of computer clients and servers connected via the internet network. Poor family residence data obtained from the government. In addition, survey data are inputted through the client computer in each administrative village and also 23 criteria of input in accordance with the established government. The PROMETHEE method is used to evaluate the value of poverty and its weight is used to determine poverty status. PROMETHEE output can also be used to rank the poverty of the registered population of the server based on the netflow value. The poverty rate is calculated based on the current poverty rate compared to the previous poverty rate. The rate results can be viewed online and real time on the server through numbers and graphs. From the test results can be seen that the system can classify poverty status, calculate the poverty rate change rate and can determine the value and poverty ranking of each population.
Bystrov, N. S.; Emelianov, A. V.; Eremin, A. V.; Yatsenko, P. I.
2018-05-01
The kinetics of the dissociation of CF3I behind shock waves was experimentally investigated. The reaction CF3I + Ar → CF3 + I + Ar was studied at temperatures between 900 and 1250 K and pressures of 2–3 bar. For this purpose, the time profiles of the concentration of atomic iodine were measured using a highly sensitive atomic resonance absorption spectroscopy method at a wavelength of 183.04 nm. From these data, the experimental value of the dissociation rate constant of CF3I was obtained: . We found that the investigated range of pressures and temperatures for the CF3I dissociation lies in the pressure transition region. Based on the Rice-Ramsperger–Kassel–Marcus theory, the threshold high and low-pressure rate constants ( and k 0) and falloff curves are calculated for the temperatures of 950–1200 K. As a result of this calculation, the threshold rate constants could be evaluated in the forms: and , and the center broadening factor, which takes into account the contribution of strong and weak collisions in the transition region, is .
Calculation of heat rating and burn-up for test fuel pins irradiated in DR 3
Bagger, C.; Carlsen, H.; Hansen, K.
1980-01-01
A summary of the DR 3 reactor and HP1 rig design is given followed by a detailed description of the calculation procedure for obtaining linear heat rating and burn-up values of fuel pins irradiated in HP1 rigs. The calculations are carried out rather detailed, especially regarding features like end pellet contribution to power as a function of burn-up, gamma heat contributions, and evaluation of local values of heat rating and burn-up. Included in the report is also a description of the fast flux- and cladding temperature calculation techniques currently used. A good agreement between measured and calculated local burn-up values is found. This gives confidence to the detailed treatment of the data. (author)
2002-01-01
Calculations with the quadratic lineal model for medium rate using the equation dose-effect. Several calculations for system of low dose rate brachytherapy plus teletherapy, calculations for brachytherapy with medium dose rate together with teletherapy, dose for fraction and the one numbers of fractions in medium rate
Large-scale calculations of the beta-decay rates and r-process nucleosynthesis
Borzov, I N; Goriely, S [Inst. d` Astronomie et d` Astrophysique, Univ. Libre de Bruxelles, Campus Plaine, Bruxelles (Belgium); Pearson, J M [Inst. d` Astronomie et d` Astrophysique, Univ. Libre de Bruxelles, Campus Plaine, Bruxelles (Belgium); [Lab. de Physique Nucleaire, Univ. de Montreal, Montreal (Canada)
1998-06-01
An approximation to a self-consistent model of the ground state and {beta}-decay properties of neutron-rich nuclei is outlined. The structure of the {beta}-strength functions in stable and short-lived nuclei is discussed. The results of large-scale calculations of the {beta}-decay rates for spherical and slightly deformed nuclides of relevance to the r-process are analysed and compared with the results of existing global calculations and recent experimental data. (orig.)
Calculation of the ingestion critical dose rate for the Goiania radioactive waste repository
Passos, E.M. dos; Martin Alves, A.S. De
1994-01-01
The calculation results of the critical distance for the ingestion dose rate due to a hypothetical Cs-137 release from the Abadia de Goias repository are shown. The work is based on the pathway repository-aquifer-well food chain. The calculations were based upon analytical models for the migration of radioisotopes through the aquifer and for its transfer from well water to food. (author)
Jubb, Aaron M; Gierczak, Tomasz; Baasandorj, Munkhbayar; Waterland, Robert L; Burkholder, James B
2014-05-06
Mixtures of methyl-perfluoroheptene-ethers (CH3OC7F13, MPHEs) are currently in use as replacements for perfluorinated alkanes (PFCs) and poly-ether heat transfer fluids, which are persistent greenhouse gases with lifetimes >1000 years. At present, the atmospheric processing and environmental impact from the use of MPHEs is unknown. In this work, rate coefficients at 296 K for the gas-phase reaction of the OH radical with six key isomers (including stereoisomers and enantiomers) of MPHEs used commercially were measured using a relative rate method. Rate coefficients for the six MPHE isomers ranged from ∼ 0.1 to 2.9 × 10(-12) cm(3) molecule(-1) s(-1) with a strong stereoisomer and -OCH3 group position dependence; the (E)-stereoisomers with the -OCH3 group in an α- position relative to the double bond had the greatest reactivity. Rate coefficients measured for the d3-MPHE isomer analogues showed decreased reactivity consistent with a minor contribution of H atom abstraction from the -OCH3 group to the overall reactivity. Estimated atmospheric lifetimes for the MPHE isomers range from days to months. Atmospheric lifetimes, radiative efficiencies, and global warming potentials for these short-lived MPHE isomers were estimated based on the measured OH rate coefficients along with measured and theoretically calculated MPHE infrared absorption spectra. Our results highlight the importance of quantifying the atmospheric impact of individual components in an isomeric mixture.
Hoefler, A.; Grebner, H.
1992-01-01
Calculations of leak opening and leak rate for through cracks in piping components have been performed. The analyses are pre- or mostly post-calculations to experiments performed at the HDR facility under PWR operating conditions. Piping components under consideration are small diameter straight pipes with circumferential cracks, pipe bends with longitudinal or circumferential cracks and pipe branches with weldment cracks. The component are loaded by internal pressure and opening as well as closing bending moment. The finite element method and two-phase flow leak rate programs are used for the calculations. Results of the analyses are presented as J-integral values, crack opening displacements and areas and leak rates as well as comparisons to the experimental results. 6 refs., 16 figs., 2 tabs
Comparison of leak opening and leak rate calculations to HDR experimental results
Grebner, H.; Hoefler, A.; Hunger, H.
1993-01-01
During the last years a number of calculations of leak opening and leak rate for through cracks in piping components have been performed. Analyses are pre- or mostly post-calculations to experiments performed at the HDR facility under PWR operating conditions. Piping components under consideration were small diameter straight pipes with circumferential cracks, pipe bends with longitudinal or circumferential cracks and pipe branches with weldment cracks. The components were loaded by internal pressure and opening as well as closing bending moment. The finite element method and two-phase flow leak rate programs were used for the calculations. Results of the analyses are presented as J-integral values, crack opening displacements and areas and leak rates as well as comparisons to the experimental results
Calculation of the gamma-dose rate from a continuously emitted plume
Huebschmann, W.; Papadopoulos, D.
1975-06-01
A computer model is presented which calculates the long term gamma dose rate caused by the radioactive off-gas continuously emitted from a stack. The statistical distribution of the wind direction and velocity and of the stability categories is taken into account. The emitted activity, distributed in the atmosphere according to this statistics, is assumed to be concentrated at the mesh points of a three-dimensional grid. The grid spacing and the integration limits determine the accuracy as well as the computer time needed. When calculating the dose rate in a given wind direction, the contribution of the activity emitted into the neighbouring sectors is evaluated. This influence is demonstrated in the results, which are calculated with a error below 3% and compared to the dose rate distribution curves of the submersion model and the model developed by K.J. Vogt. (orig.) [de
The permeability coefficients of mixed matrix membranes of polydimethylsiloxane (PDMS) and silicalite crystal are taken as the sum of the permeability coefficients of membrane components each weighted by their associated mass fraction. The permeability coefficient of a membrane c...
Relativistic QRPA Calculation of β-Decay Rates of r-process Nuclei
Marketin, T.; Paar, N.; Niksic, T.; Vretenar, D.; Ring, P.
2009-01-01
A systematic, fully self-consistent calculation of β-decay rates is presented, based on a microscopic theoretical framework. Analysis is performed on a large number of nuclei from the valley of β stability towards the neutron drip-line. Nuclear ground state is determined using the Relativistic Hartree-Bogoliubov (RHB) model with density-dependent meson-nucleon coupling constants. Transition rates are calculated within the proton-neutron relativistic quasiparticle RPA (pn-RQRPA) using the same interaction that was used in the RHB equations.
American Society for Testing and Materials. Philadelphia
1989-01-01
1.1 This practice covers the providing of guidance in converting the results of electrochemical measurements to rates of uniform corrosion. Calculation methods for converting corrosion current density values to either mass loss rates or average penetration rates are given for most engineering alloys. In addition, some guidelines for converting polarization resistance values to corrosion rates are provided. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
Calculation of dose-rate conversion factors for external exposure to photons and electrons
Kocher, D.C.
1978-01-01
Methods are presented for the calculation of dose-rate conversion factors for external exposure to photon and electron radiation from radioactive decay. A dose-rate conversion factor is defined as the dose-equivalent rate per unit radionuclide concentration. Exposure modes considered are immersion in contaminated air, immersion in contaminated water, and irradiation from a contaminated ground surface. For each radiation type and exposure mode, dose-rate conversion factors are derived for tissue-equivalent material at the body surface of an exposed individual. In addition, photon dose-rate conversion factors are estimated for 22 body organs. The calculations are based on the assumption that the exposure medium is infinite in extent and that the radionuclide concentration is uniform. The dose-rate conversion factors for immersion in contaminated air and water then follow from the requirement that all of the energy emitted in the radioactive decay is absorbed in the infinite medium. Dose-rate conversion factors for ground-surface exposure are calculated at a reference location above a smooth, infinite plane using the point-kernel integration method and known specific absorbed fractions for photons and electrons in air
Cowley, S.C.; Kulsrud, R.M.
1989-11-01
We calculate the fusion reaction rates in molecules of hydrogen isotopes. The rates are calculated analytically (for the first time) as an asymptotic expansion in the ratio of the electron mass to the reduced mass of the nucleii. The fusion rates of the P-D, D-D, and D-T reactions are given for a variable electron mass by a simple analytic formula. However, we do not know any mechanism by which a sufficiently localized electron in solid can have an 'effective mass' large enough to explain the result of Fleischman and Pons (FP). This calculation indicates that P-D rates should exceed D-D rates for D-D fusion rates less than approximately 10 -23 per molecule per second. The D-D fusion rate is enhanced by a factor of 10 5 at 10,000 degree K if the excited vibrational states are populated with a Boltzmann distribution and the rotational excitations suppressed. The suggestion that experimental results could be explained by bombardment of cold deuterons by kilovolt deuterons is shown to be an unlikely from an energetic point of view. 12 refs., 3 figs., 1 tab
Simone, Angela; Kolarik, Jakub; Iwamatsu, Toshiya
2011-01-01
occupants, it is reasonable to consider both the exergy flows in building and those within the human body. Until now, no data have been available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation. The objective of the present work was to relate thermal...... sensation data, from earlier thermal comfort studies, to calculated human-body exergy consumption rates. The results show that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to the slightly cool side of thermal sensation....... Generally, the relationship between air temperature and the exergy consumption rate, as a first approximation, shows an increasing trend. Taking account of both convective and radiative heat exchange between the human body and the surrounding environment by using the calculated operative temperature, exergy...
Myint, P. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hao, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Firoozabadi, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-03-27
Thermodynamic property calculations of mixtures containing carbon dioxide (CO_{2}) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data [1]. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi [2], and the CO_{2} activity coefficient model by Duan and Sun [3]. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO_{2}, pure water, and both CO_{2}-rich and aqueous (H_{2}O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Sun’s model yields accurate results for the partial molar enthalpy of CO_{2}. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H_{2}O-CO_{2}-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.
Axelrod, David
2017-01-01
This paper describes how the discount rate used in present value calculations expresses the preference for sustainability in decision making, and its implication for sustainable economic growth. In essence, the lower the discount rate, the greater the regard for the future, and the more likely we choose behaviors that lead to long-term sustainability. The theoretical framework combines behavioral economics and holonomics, which involve limitations of regard for the future due to constraints o...
Panthere V2: Multipurpose Simulation Software for 3D Dose Rate Calculations
Penessot, Gaël; Bavoil, Éléonore; Wertz, Laurent; Malouch, Fadhel; Visonneau, Thierry; Dubost, Julien
2017-09-01
PANTHERE is a multipurpose radiation protection software developed by EDF to calculate gamma dose rates in complex 3D environments. PANTHERE takes a key role in the EDF ALARA process, enabling to predict dose rates and to organize and optimize operations in high radiation environments. PANTHERE is also used for nuclear waste characterization, transport of nuclear materials, etc. It is used in most of the EDF engineering units and their design service providers and industrial partners.
Rate coefficients for collisional population transfer between 3p54p argon levels at 300 0K
Nguyen, T.D.; Sadeghi, N.
1978-01-01
The population transfer between excited 3p 5 4p argon levels induced by the collisional process Ar* (3p 5 4p)/sub i/ + Ar( 1 S 0 ) arrow-right-left Ar* (3p 5 4p)/sub j/ + Ar( 1 S 0 ) + ΔE was studied in the afterglow of an argon pulsed discharge, at the pressure range of 0.2--1 Torr. Selective population of one particular argon 3p 5 4p level was achieved by laser excitation from one metastable state by use of a tunable cw dye laser. The populations of the laser-excited level and of the collisional excited levels were determined by intensity measurements of the fluorescence line and of the sensitized fluorescence lines. The time-dependence study of the populations of the metastable state, of the laser-excited state, and of the collisional excited states was carried out to ascertain the product channel and to determine the collisional transfer rate coefficients
Feofilov, A. G.; Kutepov, A. A.; She, C. Y.; Smith, A. K.; Pesnell, W. D.; Goldberg, R. A.
2009-01-01
Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(V2) vibrational levels in collisions with oxygen atoms plays an important role. However, neither the rate coefficient of this process (k(CO2O)) nor the atomic oxygen concentrations ([O]) in the MLT are well known. The discrepancy between k(CO2O) measured in the lab and retrieved from atmospheric measurements is of about factor of 2.5. At the same time, the discrepancy between [O] in the MLT measured by different instruments is of the same order of magnitude. In this work we used a synergy of a ground based lidar and satellite infrared radiometer to make a further step in understanding of the physics of the region. In this study we apply the night- and daytime temperatures between 80 and 110 km measured by the Colorado State University narrow-band sodium (Na) lidar located at Fort Collins, Colorado for retrieving the product of k(CO2-O) x [O] from the limb radiances in the 15 micron channel measured by the SABER/TIMED instrument for nearly simultaneous common volume measurements of both instruments within +/-1 degree in latitude, +/-2 degrees in longitude and +/-10 minutes in time. We derive k(CO2-O) and its possible variation range from the retrieved product by utilizing the [O] values measured by the SABER and other instruments.
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.
Calculation of radiation dose rates from a spent nuclear fuel shipping cask
Chen, S.Y.; Yuan, Y.C.
1988-01-01
Radiation doses from a spent nuclear fuel cask are usually from various phases of operations during handling, shipping, and storage of the casks. Assessment of such doses requires knowledge of external radiation dose rates at various locations surrounding a cask. Under current practices, dose rates from gamma photons are usually estimated by means of point- or line-source approaches incorporating the conventional buildup factors. Although such simplified approaches may at times be easy to use, their accuracy has not been verified. For example, those simplified methods have not taken into account influencing factors such as the geometry of the cask and the presence of the ground surface, and the effects of these factors on the calculated dose rates are largely unknown. Moreover, similar empirical equations for buildup factors currently do not exist for neutrons. The objective of this study is to use a more accurate approach in calculating radiation dose rates for both neutrons and gamma photons from a spent fuel cask. The calculation utilizes the more sophisticated transport method and takes into account the geometry of the cask and the presence of the ground surface. The results of a detailed study of dose rates in the near field (within 20 meters) are presented and, for easy application, the cask centerline dose rates are fitted into empirical equations at cask centerline distances up to 2000 meters from the surface of the cask
BAKER, DR; STAEBLER, GM; PETTY, CC; GREENFIELD, CM; LUCE, TC
2003-01-01
OAK-B135 The gyrokinetic equations predict that various drift type waves or modes can be unstable in a tokamak. For some of these modes, such as the ion temperature gradient (ITG) mode and the electron temperature gradient mode, there exists a critical gradient, above which the mode is unstable. Since the existence of unstable modes can cause increased transport, plasmas which are centrally heated tend to increase in temperature gradient until the modes become unstable. Under some conditions the increased transport can fix the gradient at the critical value. here they present a comparison between the measured ion temperature gradients and the critical gradient as calculated by a gyrokinetic linear stability (GKS) code. They also present the maximum linear growth rate as calculated by this code for comparison to experimentally derived transport coefficients. The results show that for low confinement mode (L-mode) discharges, the measured ion temperature gradient is significantly greater than the GKS calculated critical gradient over a large region of the plasma. This is the same region of the plasma where the ion thermal diffusivity is large. For high confinement mode (H-mode) discharges the ion temperature gradient is closer to the critical gradient, but often still greater than the critical gradient over some region. For the best H-mode discharges, the ion temperature is less than or equal to the critical gradient over the whole plasma. In general they find that the position in the plasma where the ion thermal diffusivity starts to increase rapidly is where the maximum linear growth rate is greater than the E x B shearing rate
Ni Zhipeng; Wang Liangbin; Li Jiangang; Chen Zhiyou; Zhang Yong; Wang Futang
2008-01-01
An electromagnetic calculation and the parameters of the magnet system of the magnetically confined plasma rocket were established. By using ANSYS code, it was found that the leakage rate depends on the current intensity of the magnet and the change of the magnet position.
Zinth, Jennifer
2018-01-01
Federal requirements stipulate that states and local education agencies annually calculate and report an Adjusted Cohort Graduation Rate, disaggregated by student group. The ACGR includes all students who graduate from high school in four years with a regular high school diploma, plus all students with the most significant cognitive disabilities…
39 CFR 3010.23 - Calculation of percentage change in rates.
2010-07-01
... DOMINANT PRODUCTS Rules for Applying the Price Cap § 3010.23 Calculation of percentage change in rates. (a... Postal Service billing determinants. The Postal Service shall make reasonable adjustments to the billing determinants to account for the effects of classification changes such as the introduction, deletion, or...
20 CFR 10.216 - How is the pay rate for COP calculated?
2010-04-01
... for COP purposes is equal to the employee's regular “weekly” pay (the average of the weekly pay over... occurred during the 45-day period are to be reflected in the weekly pay determination. (b) The weekly pay... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false How is the pay rate for COP calculated? 10...
Results of Propellant Mixing Variable Study Using Precise Pressure-Based Burn Rate Calculations
Stefanski, Philip L.
2014-01-01
A designed experiment was conducted in which three mix processing variables (pre-curative addition mix temperature, pre-curative addition mixing time, and mixer speed) were varied to estimate their effects on within-mix propellant burn rate variability. The chosen discriminator for the experiment was the 2-inch diameter by 4-inch long (2x4) Center-Perforated (CP) ballistic evaluation motor. Motor nozzle throat diameters were sized to produce a common targeted chamber pressure. Initial data analysis did not show a statistically significant effect. Because propellant burn rate must be directly related to chamber pressure, a method was developed that showed statistically significant effects on chamber pressure (either maximum or average) by adjustments to the process settings. Burn rates were calculated from chamber pressures and these were then normalized to a common pressure for comparative purposes. The pressure-based method of burn rate determination showed significant reduction in error when compared to results obtained from the Brooks' modification of the propellant web-bisector burn rate determination method. Analysis of effects using burn rates calculated by the pressure-based method showed a significant correlation of within-mix burn rate dispersion to mixing duration and the quadratic of mixing duration. The findings were confirmed in a series of mixes that examined the effects of mixing time on burn rate variation, which yielded the same results.
Relativistic QRPA calculation of β-decay rates of r-process nuclei
Marketin, T.; Paar, N.; Niksic, T.
2009-01-01
The rapid neutron-capture process (r-process) is responsible for the creation of many nuclei heavier than iron. To describe the r-process, precise data is needed on a large number of neutron-rich nuclei, most of which are not experimentally reachable. One crucial parameter in modeling the nucleosynthesis are the half-lives of the nuclei through which the r-process runs. Therefore, it is of great importance to develop a reliable predictive model which can be applied to the decay of exotic nuclei. A fully self-consistent calculation of β-decay rates is presented, based on a microscopic theoretical framework. Nuclear ground state is determined using the Relativistic Hartree-Bogoliubov (RHB) model with density-dependent meson-nucleon coupling constants. Momentum dependent terms are also included to improve the density of single-particle states around the Fermi level via an increase of the effective nucleon mass [1]. Transition rates are calculated within the proton-neutron relativistic quasiparticle RPA using the same interaction that was used in the RHB equations. In this way no additional parameters are introduced in the RPA calculation. Weak interaction rates are calculated using the current-current formalism previously employed in the study of other astrophysically significant weak processes [2,3], which systematically includes the contributions of forbidden transitions. This theoretical framework will be utilized to study the contributions of forbidden transitions to the total decay rate in several mass regions. We will compare the calculated half-lives for several isotopic chains with previous calculations and experimental data and discuss possible improvements to the model.(author)
Sasaki, Yasuhiro; Minami, Noritoshi; Yoshida, Yoshitaka
2006-01-01
Institute of Nuclear Safety System, Inc. had developed the dose evaluation system to evaluate the radiation dose of employees at severe accident in a nuclear power plant. This system has features, which are (1) the dose rate of any evaluation point can be evaluated, (2) the dose rate at any time can be evaluated in consideration of the change in the radioactive source, (3) the dose rate map in the plant can be displayed (4) the dose along the access route when moving can be evaluated, and it is possible to use it for examination of the accident management guideline on the dose side etc.. To upgrade the dose evaluation function of this system, the improvements had been done which were introduction of the dose rate conversion coefficient and addition of the access route edit function. By introducing the dose rate conversion coefficient, the calculation time of the dose rate map in the plant was shortened at about 20 seconds, and a new function to evaluate time-dependent dose rate of any evaluation point was added. By adding the access route edit function, it became possible to re-calculate the dose easily at the route change. (author)
Oki, Kensuke; Ma, Bei; Ishitani, Yoshihiro
2017-11-01
Population distributions and transition fluxes of the A exciton in bulk GaN are theoretically analyzed using rate equations of states of the principal quantum number n up to 5 and the continuum. These rate equations consist of the terms of radiative, electron-collisional, and phononic processes. The dependence of the rate coefficients on temperature is revealed on the basis of the collisional-radiative model of hydrogen plasma for the electron-collisional processes and theoretical formulation using Fermi's "golden rule" for the phononic processes. The respective effects of the variations in electron, exciton, and lattice temperatures are exhibited. This analysis is a base of the discussion on nonthermal equilibrium states of carrier-exciton-phonon dynamics. It is found that the exciton dissociation is enhanced even below 150 K mainly by the increase in the lattice temperature. When the thermal-equilibrium temperature increases, the population fluxes between the states of n >1 and the continuum become more dominant. Below 20 K, the severe deviation from the Saha-Boltzmann distribution occurs owing to the interband excitation flux being higher than the excitation flux from the 1 S state. The population decay time of the 1 S state at 300 K is more than ten times longer than the recombination lifetime of excitons with kinetic energy but without the upper levels (n >1 and the continuum). This phenomenon is caused by a shift of population distribution to the upper levels. This phonon-exciton-radiation model gives insights into the limitations of conventional analyses such as the ABC model, the Arrhenius plot, the two-level model (n =1 and the continuum), and the neglect of the upper levels.
Calculation of expected rates of fisheries‐induced evolution in data‐poor situations
Andersen, Ken Haste
2010-01-01
A central part of an impact assessment of the evolutionary effects of fishing is a calculation of the expected rates of fishing induced by current fishing practice and an evaluation of how alternative fishing patterns may reduce evolutionary impacts of fishing. Here a general size-based framework...... for modeling the demography of fish based on size-based prescriptions of natural mortality, growth, and fishing is presented. Life history theory is used to reduce the necessary parameter set by utilizing relations between parameters making the framework particularly well suited for data-poor situations where...... only the size at maturation or the asymptotic size is known. The framework is applied to perform the modeling part of an evolutionary impact assessment using basic quantitative genetics to calculated expected rates of evolution on size at maturation, growth rate, and investment in gonads. A sensitivity...
Concept for calculating dose rates from activated groundwater at accelerator sites
Prolingheuer, N; Vanderborght, J; Schlögl, B; Nabbi, R; Moormann, R
Licensing of particle accelerators requires the proof that the groundwater outside of the site will not be significantly contaminated by activation products formed below accelerator and target. In order to reduce the effort for this proof, a site independent simplified but conservative method is under development. The conventional approach for calculation of activation of soil and groundwater is shortly described on example of a site close to Forschungszentrum Juelich, Germany. Additionally an updated overview of a data library for partition coefficients for relevant nuclides transported in the aquifer at the site is presented. The approximate model for transport of nuclides with ground water including exemplary results on nuclide concentrations outside of the site boundary and of resulting effective doses is described. Further applications and developments are finally outlined.
Dose rates from a C-14 source using extrapolation chamber and MC calculations
Borg, J.
1996-05-01
The extrapolation chamber technique and the Monte Carlo (MC) calculation technique based on the EGS4 system have been studied for application for determination of dose rates in a low-energy β radiation field e.g., that from a 14 C source. The extrapolation chamber measurement method is the basic method for determination of dose rates in β radiation fields. Applying a number of correction factors and the stopping power ratio, tissue to air, the measured dose rate in an air volume surrounded by tissue equivalent material is converted into dose to tissue. Various details of the extrapolation chamber measurement method and evaluation procedure have been studied and further developed, and a complete procedure for the experimental determination of dose rates from a 14 C source is presented. A number of correction factors and other parameters used in the evaluation procedure for the measured data have been obtained by MC calculations. The whole extrapolation chamber measurement procedure was simulated using the MC method. The measured dose rates showed an increasing deviation from the MC calculated dose rates as the absorber thickness increased. This indicates that the EGS4 code may have some limitations for transport of very low-energy electrons. i.e., electrons with estimated energies less than 10 - 20 keV. MC calculations of dose to tissue were performed using two models: a cylindrical tissue phantom and a computer model of the extrapolation chamber. The dose to tissue in the extrapolation chamber model showed an additional buildup dose compared to the dose in the tissue model. (au) 10 tabs., 11 ills., 18 refs
Shell model calculations for levels and transition rates in 204Pb and 206Pb
Wang, D.; McEllistrem, M.T.
1990-01-01
Level energies and decay rates of both negative and positive parity levels of 206,204 Pb have been calculated through mixed-configuration shell model calculations using the modified surface delta interaction (MSDI), the Schiffer-True central interaction, and another two-body interaction. These calculations were all carried out with a full six-orbit neutron hole space. The predicted low-lying levels with the MSDI are in excellent agreement with experiments, accounting for the energies, spins, and parities of essentially all levels below 3 MeV excitation energy except known particle-hole collective excitations in both nuclei. Almost all calculated E2 and M1 transition rates are consistent with measured branching ratios for γ-ray decay of excited levels. The comparison of the observed and calculated levels demonstrates the important role played by the neutron-hole i 13/2 configuration in the levels of 204 Pb and 206 Pb, and interprets an apparent discrepancy over the character and energy spacings of 0 + levels in 204 Pb
Clouvas, A; Antonopoulos-Domis, M; Silva, J
2000-01-01
The dose rate conversion factors D/sub CF/ (absorbed dose rate in air per unit activity per unit of soil mass, nGy h/sup -1/ per Bq kg/sup -1/) are calculated 1 m above ground for photon emitters of natural radionuclides uniformly distributed in the soil. Three Monte Carlo codes are used: 1) The MCNP code of Los Alamos; 2) The GEANT code of CERN; and 3) a Monte Carlo code developed in the Nuclear Technology Laboratory of the Aristotle University of Thessaloniki. The accuracy of the Monte Carlo results is tested by the comparison of the unscattered flux obtained by the three Monte Carlo codes with an independent straightforward calculation. All codes and particularly the MCNP calculate accurately the absorbed dose rate in air due to the unscattered radiation. For the total radiation (unscattered plus scattered) the D/sub CF/ values calculated from the three codes are in very good agreement between them. The comparison between these results and the results deduced previously by other authors indicates a good ag...
Wrede, D E; Dawalibi, H [King Faisal Specialist Hospital and Research Centre, Department of Medical Physics. Riyadh (Saudi Arabia)
1980-01-01
A simple mathematical algorithm is derived from experimental data for dose rates from /sup 137/Cs sources in a finite tissue equivalent medium corresponding to the female pelvis. An analytical expression for a point source of /sup 137/Cs along with a simple numerical integration routine allows for rapid as well as accurate dose rate calculations at points of interest for gynecologic insertions. When compared with theoretical models assuming an infinite unit density medium, the measured dose rates are found to be systematically lower at distances away from a single source; 5 per cent at 2 cm and 10 per cent at 7 cm along the transverse axis. Allowance in the program for print out of dose rates from individual sources to a given point and the feature of source strength modification allows for optimization in terms of increasing the difference in dose rate between reference treatment points and sensitive structures such as the bladder, rectum and colon.
Wrede, D.E.; Dawalibi, H.
1980-01-01
A simple mathematical algorithm is derived from experimental data for dose rates from 137 Cs sources in a finite tissue equivalent medium corresponding to the female pelvis. An analytical expression for a point source of 137 Cs along with a simple numerical integration routine allows for rapid as well as accurate dose rate calculations at points of interest for gynecologic insertions. When compared with theoretical models assuming an infinite unit density medium, the measured dose rates are found to be systematically lower at distances away from a single source; 5 per cent at 2 cm and 10 per cent at 7 cm along the transverse axis. Allowance in the program for print out of dose rates from individual sources to a given point and the feature of source strength modification allows for optimization in terms of increasing the difference in dose rate between reference treatment points and sensitive structures such as the bladder, rectum and colon. (Auth.)
Nieckarz, Zenon; Kułak, Andrzej; Zięba, Stanisław; Kubicki, Marek; Michnowski, Stanisław; Barański, Piotr
2009-02-01
This work presents the results of a comparison between the global storm activity rate IRS and electric field intensity E0 Z. The permanent analysis of the IRS may become an important tool for testing Global Electric Circuit models. IRS is determined by a new method that uses the background component of the first 7 Schumann resonances (SR). The rate calculations are based on ELF observations carried out in 2005 and 2006 in the observatory station "Hylaty" of the Jagiellonian University in the Eastern Carpathians (Kułak, A., Zięba, S., Micek, S., Nieckarz, Z., 2003. Solar variations in extremely low frequency propagation parameters: I. A two-dimensional telegraph equation (TDTE) model of ELF propagation and fundamental parameters of Schumann resonances, J. Geophys. Res., 108, 1270, doi:10.1029/2002JA009304). Diurnal runs of the IRS rate were compared with diurnal runs of E0 Z amplitudes registered at the Earth's surface in the Geophysical Observatory of the Polish Academy of Sciences in Świder (Kubicki, M., 2005. Results of Atmospheric Electricity and Meteorological Observations, S. Kalinowski Geophysical Observatory at Świder 2004, Pub. Inst. Geophysics Polish Academy of Sciences, D-68 (383), Warszawa.). The days with the highest values of the correlation coefficient ( R) between amplitudes of both observed parameters characterizing atmosphere electric activity are shown. The seasonal changes of R, IRS and E0 Z are also presented.
Mohammad Delnavaz
2017-06-01
Conclusion: Evaluation of Y, kd, k0 and Ks parameters in operation of Ekbatan wastewater treatment plant showed that ASM1 model could well determine the coefficients and therefore the conditions of biological treatment is appropriate.
Avat (Arman Taherpour
2017-05-01
Full Text Available The volatile constituents of the essential oil of wild Solanumn nigrum L. obtained from the Kurdistan of Iraq were extracted by head-space/solid-phase micro-extraction (HS/SPME and were analyzed by gas chromatography (GC and gas chromatography/mass spectrometry (GC/MS. Of a total of twenty compounds in the oil, all of them were identified. The main components were as follows: Dillapiole (22.22%, α-Cadinol (16.47%, para-Cymene (10.01%, (E-1-(2,6,6-Trimethyl-1,3-cyclohexadien-1-yl-2-buten-1-one or β-damascenone (9.08%, α-Phellandrene (8.48%, β-Pinene (5.93%, α-Bisabolol acetate (4.53%, (Z,E-4,6,8-Megastigmatriene (4.09%, Phytol (2.49%, Linalyl butanoate (2.13%, 8-methylene-tricyclo[3.2.1.0(2,4]octane (2.60% and Limonene (2.03%. Some physicochemical properties, such as the logarithm of calculated octanol–water partitioning coefficients (logKow and total biodegradation (TBd in mol/h were calculated for compounds 1–20 from S. nigrum L.
Preliminary calculations of release rates from spent fuel in a tuff repository
Apted, M.J.; O'Connell, W.J.; Lee, K.H.; MacIntyre, A.T.; Ueng, T.S.; Pigford, T.H.; Lee, W.W.L.
1991-01-01
Time-dependent release rates of Tc-99, I-129, Cs-135, and Np-237 have been calculated for wet-drip and moist-continuous release modes from the engineered barrier system of a potential nuclear waste repository in unsaturated tuff, representative of a possible repository at Yucca Mountain in southern Nevada. We describe the modes of water contact and of release of dissolved radionuclides to the surrounding intact rock, and the corresponding calculational models. We list the parameter values adopted, and then present numerical results, conclusions, and recommendations. 21 refs., 5 figs., 2 tabs
Shaw, Jacob T.; Lidster, Richard T.; Cryer, Danny R.; Ramirez, Noelia; Whiting, Fiona C.; Boustead, Graham A.; Whalley, Lisa K.; Ingham, Trevor; Rickard, Andrew R.; Dunmore, Rachel E.; Heard, Dwayne E.; Lewis, Ally C.; Carpenter, Lucy J.; Hamilton, Jacqui F.; Dillon, Terry J.
2018-03-01
Gas-phase rate coefficients are fundamental to understanding atmospheric chemistry, yet experimental data are not available for the oxidation reactions of many of the thousands of volatile organic compounds (VOCs) observed in the troposphere. Here, a new experimental method is reported for the simultaneous study of reactions between multiple different VOCs and OH, the most important daytime atmospheric radical oxidant. This technique is based upon established relative rate concepts but has the advantage of a much higher throughput of target VOCs. By evaluating multiple VOCs in each experiment, and through measurement of the depletion in each VOC after reaction with OH, the OH + VOC reaction rate coefficients can be derived. Results from experiments conducted under controlled laboratory conditions were in good agreement with the available literature for the reaction of 19 VOCs, prepared in synthetic gas mixtures, with OH. This approach was used to determine a rate coefficient for the reaction of OH with 2,3-dimethylpent-1-ene for the first time; k = 5.7 (±0.3) × 10-11 cm3 molecule-1 s-1. In addition, a further seven VOCs had only two, or fewer, individual OH rate coefficient measurements available in the literature. The results from this work were in good agreement with those measurements. A similar dataset, at an elevated temperature of 323 (±10) K, was used to determine new OH rate coefficients for 12 aromatic, 5 alkane, 5 alkene and 3 monoterpene VOC + OH reactions. In OH relative reactivity experiments that used ambient air at the University of York, a large number of different VOCs were observed, of which 23 were positively identified. Due to difficulties with detection limits and fully resolving peaks, only 19 OH rate coefficients were derived from these ambient air samples, including 10 reactions for which data were previously unavailable at the elevated reaction temperature of T = 323 (±10) K.
Comparison of measured and calculated reaction rate distributions in an scwr-like test lattice
Raetz, Dominik, E-mail: dominik.raetz@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Jordan, Kelly A., E-mail: kelly.jordan@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Murphy, Michael F., E-mail: mike.murphy@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Perret, Gregory, E-mail: gregory.perret@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Chawla, Rakesh, E-mail: rakesh.chawla@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, EPFL (Switzerland)
2011-04-15
High resolution gamma-ray spectroscopy measurements were performed on 61 rods of an SCWR-like fuel lattice, after irradiation in the central test zone of the PROTEUS zero-power research reactor at the Paul Scherrer Institute in Switzerland. The derived reaction rates are the capture rate in {sup 238}U (C{sub 8}) and the total fission rate (F{sub tot}), and also the reaction rate ratio C{sub 8}/F{sub tot}. Each of these has been mapped rod-wise on the lattice and compared to calculated results from whole-reactor Monte Carlo simulations with MCNPX. Ratios of calculated to experimental values (C/E's) have been assessed for the C{sub 8}, F{sub tot} and C{sub 8}/F{sub tot} distributions across the lattice. These C/E's show excellent agreement between the calculations and the measurements. For the {sup 238}U capture rate distribution, the 1{sigma} level in the comparisons corresponds to an uncertainty of {+-}0.8%, while for the total fission rate the corresponding value is {+-}0.4%. The uncertainty for C{sub 8}/F{sub tot}, assessed as a reaction rate ratio characterizing each individual rod position in the test lattice, is significantly higher at {+-}2.2%. To determine the reproducibility of these results, the measurements were performed twice, once in 2006 and again in 2009. The agreement between these two measurement sets is within the respective statistical uncertainties.
Simone, Angela; Kolarik, Jakub; Olesen, Bjarne W. [ICIEE/BYG, Technical University of Denmark (Denmark); Iwamatsu, Toshiya [Faculty of Urban Environmental Science, Tokyo Metropolitan University (Japan); Asada, Hideo [Architech Consulting Co., Tokyo (Japan); Dovjak, Mateja [Faculty of Civil and Geodetic Engineering, University of Ljubljana (Slovenia); Schellen, Lisje [Eindhoven University of Technology, Faculty of Architecture Building and Planning (Netherlands); Shukuya, Masanori [Laboratory of Building Environment, Tokyo City University, Yokohama (Japan)
2011-01-15
Application of the exergy concept to research on the built environment is a relatively new approach. It helps to optimize climate conditioning systems so that they meet the requirements of sustainable building design. As the building should provide a healthy and comfortable environment for its occupants, it is reasonable to consider both the exergy flows in building and those within the human body. Until now, no data have been available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation. The objective of the present work was to relate thermal sensation data, from earlier thermal comfort studies, to calculated human-body exergy consumption rates. The results show that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to the slightly cool side of thermal sensation. Generally, the relationship between air temperature and the exergy consumption rate, as a first approximation, shows an increasing trend. Taking account of both convective and radiative heat exchange between the human body and the surrounding environment by using the calculated operative temperature, exergy consumption rates increase as the operative temperature increases above 24 C or decreases below 22 C. With the data available so far, a second-order polynomial relationship between thermal sensation and the exergy consumption rate was established. (author)
Rate maximum calculation of Dpa in CNA-II pressure vessel
Mascitti, J. A
2012-01-01
The maximum dpa rate was calculated for the reactor in the following state: fresh fuel, no Xenon, a Boron concentration of 15.3 ppm, critical state, its control rods in the criticality position, hot, at full power (2160 MW). It was determined that the maximum dpa rate under such conditions is 3.54(2)x10 12 s -1 and it is located in the positions corresponding to θ=210 o in the azimuthal direction, and z=20 cm and -60 cm respectively in the axial direction, considering the calculation mesh centered at half height of the fuel element (FE) active length. The dpa rate spectrum was determined as well as the contribution to it for 4 energy groups: a thermal group, two epithermal groups and a fast one. The maximum dpa rate considering the photo-neutrons production from (γ, n) reaction in the heavy water of coolant and moderator was 3.93(4)x10 12 s -1 that is 11% greater than the obtained without photo-neutrons. This verified significant difference between both cases, suggest that photo-neutrons in large heavy water reactors such as CNA-II should not be ignored. The maximum DPA rate in the first mm of the reactor pressure vessel was calculated too and it was obtained a value of 4.22(6)x10 12 s -1 . It should be added that the calculation was carried out with the reactor complete accurate model, with no approximations in spatial or energy variables. Each value has, between parentheses, a percentage relative error representing the statistical uncertainty due to the probabilistic Monte Carlo method used to estimate it. More representative values may be obtained with this method if equilibrium burn-up distribution is used (author)
Aggarwal, K. M.; Kingston, A. E.; McDowell, M. R. C.
1984-03-01
The available experimental and theoretical electron impact excitation cross section data for the transitions from the 1s2 1S ground state to the 1s2s 1,3S and 1s2p 1,3P0 excited states of helium are assessed. Based on this assessed data, excitation rate coefficients are calculated over a wide electron temperature range below 3.0×106K. A comparison with other published results suggests that the rates used should be lower by a factor of 2 or more.
Sakhaee, Mahmoud; Vejdani-Noghreiyan, Alireza; Ebrahimi-Khankook, Atiyeh
2015-01-01
Radiation induced cataract has been demonstrated among people who are exposed to ionizing radiation. To evaluate the deterministic effects of ionizing radiation on the eye lens, several papers dealing with the eye lens dose have been published. ICRP Publication 103 states that the lens of the eye may be more radiosensitive than previously considered. Detailed investigation of the response of the lens showed that there are strong differences in sensitivity to ionizing radiation exposure with respect to cataract induction among the tissues of the lens of the eye. This motivated several groups to look deeper into issue of the dose to a sensitive cell population within the lens, especially for radiations with low energy penetrability that have steep dose gradients inside the lens. Two sophisticated mathematical models of the eye including the inner structure have been designed for the accurate dose estimation in recent years. This study focuses on the calculations of the absorbed doses of different parts of the eye using the stylized models located in UF-ORNL phantom and comparison with the data calculated with the reference computational phantom in a broad parallel beam incident of protons with energies between 20 MeV and 10 GeV. The obtained results indicate that the total lens absorbed doses of reference phantom has good compliance with those of the more sensitive regions of stylized models. However, total eye absorbed dose of these models greatly differ with each other for lower energies. - Highlights: • The validation of reference data for the eye was studied for proton exposures. • Two real mathematical models of the eye were imported into the UF-ORNL phantom. • Fluence to dose conversion coefficients were calculated for different eye sections. • Obtained Results were compared with that of assessed by ICRP adult male phantom
Calculation of the soft error rate of submicron CMOS logic circuits
Juhnke, T.; Klar, H.
1995-01-01
A method to calculate the soft error rate (SER) of CMOS logic circuits with dynamic pipeline registers is described. This method takes into account charge collection by drift and diffusion. The method is verified by comparison of calculated SER's to measurement results. Using this method, the SER of a highly pipelined multiplier is calculated as a function of supply voltage for a 0.6 microm, 0.3 microm, and 0.12 microm technology, respectively. It has been found that the SER of such highly pipelined submicron CMOS circuits may become too high so that countermeasures have to be taken. Since the SER greatly increases with decreasing supply voltage, low-power/low-voltage circuits may show more than eight times the SER for half the normal supply voltage as compared to conventional designs
Decay heat rates calculated using ORIGEN-S and CINDER10 with common data libraries
Brady, M.C.; Hermann, O.W.; Beard, C.A.; Bohnhoff, W.J.; England, T.R.
1991-01-01
A set of two benchmark problems were proposed as part of an international comparison of decay heat codes. Problem specifications included explicit fission-yield, decay and capture data libraries to be used in the calculations. This paper describes the results obtained using these common data to perform the benchmark calculations with two popular depletion codes, ORIGEN-S and CINDER10. Short descriptions of the methods used by each of these codes are also presented. Results from other contributors to the international comparison are discussed briefly. This comparison of decay heat codes using common data libraries demonstrates that discrepant results in calculated decay heat rates are the result of differences in the nuclear data input to the codes and not the method of solution. 15 refs., 2 figs., 8 tabs
Oishi, Koji; Minami, Kiyoshi; Ikeda, Yujiro; Kosako, Kazuaki; Nakamura, Tomoo
1991-01-01
A concrete assembly was irradiated by D-T neutrons for 10 h, and dose rate measurement one day after shutdown has been carried out in order to provide a guide line for selection studies of low activation concrete. The experimental results were analyzed by the two dimensional calculation code DOT3.5 with its related nuclear data library GICX40 based on ENDF/B-III, however disagreement between experiment and calculation was observed in the deeper detector positions. Calculations were also performed using the nuclear data library based on ENDF/B-IV, and agreement within experimental errors was obtained at all detector positions. Selection studies for low activation concrete were performed using this nuclear data library. As a result, it was found that limestone concrete exhibited excellent properties as a low activation concrete in fusion facilities. (orig.)
Extended calculations of energies, transition rates, and lifetimes for F-like Kr XXVIII
Zhang, C. Y.; Si, R.; Yao, K.; Gu, M. F.; Wang, K.; Chen, C. Y.
2018-02-01
The excitation energies, lifetimes, wavelengths and E1, E2, M1 and M2 transition rates for the lowest 389 levels of the 2l7, 2l63l‧, 2l64l‧, and 2l65l‧ configurations from second-order many-body perturbation theory (MBPT) calculations, and the results for the lowest 200 states of the 2l7, 2l63l‧, and 2l64l‧ configurations from multi-configuration Dirac-Hartree-Fock (MCDHF) calculations in F-like Kr XXVIII are presented in this work. The relative differences between our two sets of level energies are mostly within 0.005% for the lowest 200 levels. Comparisons are made with experimental and other available theoretical results to assess the reliability and accuracy of the present calculations. We believe them to be the most complete and accurate results for Kr XXVIII at present.
Calculation of hydrogen outgassing rate of LHD by recombination limited model
Akaishi, K.; Nakasuga, M.
2002-04-01
To simulate hydrogen outgassing in the plasma vacuum vessel of LHD, the recombination limited model is presented, where the time evolution of hydrogen concentration in the wall of the plasma vacuum vessel is described by a one-dimensional diffusion equation. The hydrogen outgassing rates when the plasma vacuum vessel is pumped down at room temperature and baked at 100 degC are calculated as a function of pumping time. The calculation shows that the hydrogen outgassing rate of the plasma vacuum vessel can be reduced at least by one order of magnitude due to pumping and baking. This prediction is consistent with the recent result of outgassing reduction observed in the pumping-down and baking of the plasma vacuum vessel in LHD. (author)
External dose-rate conversion factors for calculation of dose to the public
1988-07-01
This report presents a tabulation of dose-rate conversion factors for external exposure to photons and electrons emitted by radionuclides in the environment. This report was prepared in conjunction with criteria for limiting dose equivalents to members of the public from operations of the US Department of Energy (DOE). The dose-rate conversion factors are provided for use by the DOE and its contractors in performing calculations of external dose equivalents to members of the public. The dose-rate conversion factors for external exposure to photons and electrons presented in this report are based on a methodology developed at Oak Ridge National Laboratory. However, some adjustments of the previously documented methodology have been made in obtaining the dose-rate conversion factors in this report. 42 refs., 1 fig., 4 tabs.
Results of a bench mark test on the crack opening and leak rate calculation
Grebner, H.
1995-01-01
Results of a bench mark test on the standard problem calculation of crack opening and leak rate in piping components are presented. The bench mark test is based on two experiments performed in phase III of the German HDR safety program. The pipe sections considered in these experiments were a straight pipe with an 80 mm diameter containing a circumferential wall penetrating crack and a pipe branch DN 100/DN 25 with a crack in the weldment between the nozzle and the main pipe. Both test pieces were made of austenitic steel and were loaded by internal pressure and bending moment. For the evaluation of the crack opening either analytical methods or estimation schemes or the finite element method were used, while leak rates were calculated by means of two-phase flow methods. The compilation of the results shows very large scatter bands in general, with deviations between calculated and measured values of up to some one hundred percent. Reasons for this behaviour are uncertainties in the measured data and their evaluation as well as the different methods of calculation and their uncertainties. (author)
Preliminary results on food consumption rates for off-site dose calculation of nuclear power plants
Lee, Gab Bock; Chung, Yang Geun; Bang, Sun Young; Kang, Duk Won
2005-01-01
The Internal dose by food consumption mostly account for radiological dose of public around nuclear power plants(NPP). But, food consumption rate applied to off-site dose calculation in Korea which is the result of field investigation around Kori NPP by the KAERI in 1988. is not reflected of the latest dietary characteristics. The Ministry of Health and Welfare Affairs has investigated the food and nutrition of nations every 3 years based on the Law of National Health Improvement. To update the food consumption rates of the maximum individual, the analysis of the national food investigation results and field surveys around nuclear power plant sites have been carried out
Assessments of fluid friction factors for use in leak rate calculations
Chivers, T.C. [Berkeley Technology Centre, Glos (United Kingdom)
1997-04-01
Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.
Torr, D. G.; Orsini, N.
1978-01-01
The Atmosphere Explorer (AE) data are reexamined in the light of new laboratory measurements of the N2(+) recombination rate coefficient alpha. The new measurements support earlier measurements which yielded values of alpha significantly lower than the AE values. It is found that the values for alpha determined from the satellite data can be reconciled with the laboratory measurements, if the charge exchange rate coefficient for O(+)(2D) with N2 is less than one-quarter of that derived in the laboratory by Rutherford and Vroom (1971).
2013-01-08
... DEPARTMENT OF HOMELAND SECURITY U.S. Customs and Border Protection Quarterly IRS Interest Rates... the public of the quarterly Internal Revenue Service interest rates used to calculate interest on... beginning January 1, 2013, the interest rates for [[Page 1223
Calculation of neutron and gamma-ray flux-to-dose-rate conversion factors
Kwon, S.G.; Lee, S.Y.; Yook, C.C.
1981-01-01
This paper presents flux-to-dose-rate conversion factors for neutrons and gamma rays based on the American National Standard Institute (ANSI) N666. These data are used to calculate the dose rate distribution of neutron and gamma ray in radiation fields. Neutron flux-to-dose-rate conversion factors for energies from 2.5 x 10 -8 to 20 MeV are presented; the corresponding energy range for gamma rays is 0.01 to 15 MeV. Flux-to-dose-rate conversion factors were calculated, under the assumption that radiation energy distribution has nonlinearity in the phantom, have different meaning from those values obtained by monoenergetic radiation. Especially, these values were determined with the cross section library. The flux-to-dose-rate conversion factors obtained in this work were in a good agreement to the values presented by ANSI. Those data will be useful for the radiation shielding analysis and the radiation dosimetry in the case of continuous energy distributions. (author)
Calculation of nuclear-spin-relaxation rate for spin-polarized atomic hydrogen
Ahn, R.M.C.; Eijnde, J.P.H.W.V.; Verhaar, B.J.
1983-01-01
Approximations introduced in previous calculations of spin relaxation for spin-polarized atomic hydrogen are investigated by carrying out a more exact coupled-channel calculation. With the exception of the high-temperature approximation, the approximations turn out to be justified up to the 10 -3 level of accuracy. It is shown that at the lowest temperatures for which experimental data are available, the high-temperature limit underestimates relaxation rates by a factor of up to 2. For a comparison with experimental data it is also of interest to pay attention to the expression for the atomic hydrogen relaxation rates in terms of transition amplitudes for two-particle collisions. Discrepancies by a factor of 2 among previous derivations of relaxation rates are pointed out. To shed light on these discrepancies we present two alternative derivations in which special attention is paid to identical-particle aspects. Comparing with experiment, we find our theoretical volume relaxation rate to be in better agreement with measured values than that obtained by other groups. The theoretical surface relaxation rate, however, still shows a discrepancy with experiment by a factor of order 50
Arbib, Zouhayr; de Godos Crespo, Ignacio; Corona, Enrique Lara; Rogalla, Frank
2017-06-01
Microalgae culture in high rate algae ponds (HRAP) is an environmentally friendly technology for wastewater treatment. However, for the implementation of these systems, a better understanding of the oxygenation potential and the influence of climate conditions is required. In this work, the rates of oxygen production, consumption, and exchange with the atmosphere were calculated under varying conditions of solar irradiance and dilution rate during six months of operation in a real scale unit. This analysis allowed determining the biological response of these dynamic systems. The rates of oxygen consumption measured were considerably higher than the values calculated based on the organic loading rate. The response to light intensity in terms of oxygen production in the bioreactor was described with one of the models proposed for microalgae culture in dense concentrations. This model is based on the availability of light inside the culture and the specific response of microalgae to this parameter. The specific response to solar radiation intensity showed a reasonable stability in spite of the fluctuations due to meteorological conditions. The methodology developed is a useful tool for optimization and prediction of the performance of these systems.
Calculation of fluence rate distributions in a pre design clinical facility for BNCT at the LFR
Peeters, T.T.J.M.; Freudenreich, W.E.
1995-12-01
In a previous study [1], it was demonstrated that the creation of a thermal neutron facility for clinical BNCT in the LFR is feasible. Monte Carlo calculations had shown that the neutron fluence rates and gamma dose rates at the detector position of a model representing a first outline of a clinical facility met all requirements that are necessary for clinical BNCT. In order to gain more information about the neutron fluence rates at several positions, a second step is required. Calculations have been performed for the free beam and for a tumour bearing phantom at 5 cm and 10 cm distance from the irradiation window. Due to thermalization and back scattering, the thermal fluence rates in the tumour at 5 and 10 cm distance from the bismuth shield appeared to be approximately twice as high as the thermal fluence rates in the free beam at the corresponding positions of 5 to 6 cm and 10 to 11 cm from the irradiation window. (orig.)
Gomes, Renato G.; Rebello, Wilson F.; Vellozo, Sergio O.; Junior, Luis M.; Vital, Helio C.; Rusin, Tiago; Silva, Ademir X.
2013-01-01
MCNPX simulations have been performed in order to calculate dose rates as well as spectra along the four experimental channels of the gamma irradiating facility at the Technology Center of the Brazilian Army (CTEx). Safety, operational and research requirements have led to the need to determine both the magnitude and spectra of the leaking gamma fluxes. The CTEx experimental facility is cavity type with a moveable set of 28 horizontally positioned rods, filled with Cesium-137 chloride and doubly encased in stainless steel that yields an approximately plane 42 kCi-source that provides a maximum dose rate of about 1.5 kG/h into two irradiating chambers. The channels are intended for irradiation tests outside facility. They would allow larger samples to be exposed to lower gamma dose rates under controlled conditions. Dose rates have been calculated for several positions inside the channels as well as at their exits. In addition, for purposes related to the safety of operators and personnel, the angles submitted by the exiting beams have also been evaluated as they spread when leaving the channels. All calculations have been performed by using a computational model of the CTEx facility that allows its characteristics and operation to be accurately simulated by using the Monte Carlo Method. Virtual dosimeters filled with Fricke (ferrous sulfate) were modeled and positioned throughout 2 vertical channels (top and bottom) and 2 horizontal ones (front and back) in order to map dose rates and gamma spectrum distributions. The calculations revealed exiting collimated beams in the order of tenths of Grays per minute as compared to the maximum 25 Gy / min dose rate in the irradiator chamber. In addition, the beams leaving the two vertical channels were found to exhibit a widespread cone-shaped distribution with aperture angle ranging around 85 deg. The data calculated in this work are intended for use in the design of optimized experiments (better positioning of samples and
Matijevic, M.; Grgic, D.; Jecmenica, R.
2016-01-01
This paper presents comparison of the Krsko Power Plant simplified Spent Fuel Pool (SFP) dose rates using different computational shielding methodologies. The analysis was performed to estimate limiting gamma dose rates on wall mounted level instrumentation in case of significant loss of cooling water. The SFP was represented with simple homogenized cylinders (point kernel and Monte Carlo (MC)) or cuboids (MC) using uranium, iron, water, and dry-air as bulk region materials. The pool is divided on the old and new section where the old one has three additional subsections representing fuel assemblies (FAs) with different burnup/cooling time (60 days, 1 year and 5 years). The new section represents the FAs with the cooling time of 10 years. The time dependent fuel assembly isotopic composition was calculated using ORIGEN2 code applied to the depletion of one of the fuel assemblies present in the pool (AC-29). The source used in Microshield calculation is based on imported isotopic activities. The time dependent photon spectra with total source intensity from Microshield multigroup point kernel calculations was then prepared for two hybrid deterministic-stochastic sequences. One is based on SCALE/MAVRIC (Monaco and Denovo) methodology and another uses Monte Carlo code MCNP6.1.1b and ADVANTG3.0.1. code. Even though this model is a fairly simple one, the layers of shielding materials are thick enough to pose a significant shielding problem for MC method without the use of effective variance reduction (VR) technique. For that purpose the ADVANTG code was used to generate VR parameters (SB cards in SDEF and WWINP file) for MCNP fixed-source calculation using continuous energy transport. ADVATNG employs a deterministic forward-adjoint transport solver Denovo which implements CADIS/FW-CADIS methodology. Denovo implements a structured, Cartesian-grid SN solver based on the Koch-Baker-Alcouffe parallel transport sweep algorithm across x-y domain blocks. This was first
Resolving an ostensible inconsistency in calculating the evaporation rate of sessile drops.
Chini, S F; Amirfazli, A
2017-05-01
This paper resolves an ostensible inconsistency in the literature in calculating the evaporation rate for sessile drops in a quiescent environment. The earlier models in the literature have shown that adapting the evaporation flux model for a suspended spherical drop to calculate the evaporation rate of a sessile drop needs a correction factor; the correction factor was shown to be a function of the drop contact angle, i.e. f(θ). However, there seemed to be a problem as none of the earlier models explicitly or implicitly mentioned the evaporation flux variations along the surface of a sessile drop. The more recent evaporation models include this variation using an electrostatic analogy, i.e. the Laplace equation (steady-state continuity) in a domain with a known boundary condition value, or known as the Dirichlet problem for Laplace's equation. The challenge is that the calculated evaporation rates using the earlier models seemed to differ from that of the recent models (note both types of models were validated in the literature by experiments). We have reinvestigated the recent models and found that the mathematical simplifications in solving the Dirichlet problem in toroidal coordinates have created the inconsistency. We also proposed a closed form approximation for f(θ) which is valid in a wide range, i.e. 8°≤θ≤131°. Using the proposed model in this study, theoretically, it was shown that the evaporation rate in the CWA (constant wetted area) mode is faster than the evaporation rate in the CCA (constant contact angle) mode for a sessile drop. Copyright © 2016 Elsevier B.V. All rights reserved.
Effects of sample size on estimates of population growth rates calculated with matrix models.
Ian J Fiske
Full Text Available BACKGROUND: Matrix models are widely used to study the dynamics and demography of populations. An important but overlooked issue is how the number of individuals sampled influences estimates of the population growth rate (lambda calculated with matrix models. Even unbiased estimates of vital rates do not ensure unbiased estimates of lambda-Jensen's Inequality implies that even when the estimates of the vital rates are accurate, small sample sizes lead to biased estimates of lambda due to increased sampling variance. We investigated if sampling variability and the distribution of sampling effort among size classes lead to biases in estimates of lambda. METHODOLOGY/PRINCIPAL FINDINGS: Using data from a long-term field study of plant demography, we simulated the effects of sampling variance by drawing vital rates and calculating lambda for increasingly larger populations drawn from a total population of 3842 plants. We then compared these estimates of lambda with those based on the entire population and calculated the resulting bias. Finally, we conducted a review of the literature to determine the sample sizes typically used when parameterizing matrix models used to study plant demography. CONCLUSIONS/SIGNIFICANCE: We found significant bias at small sample sizes when survival was low (survival = 0.5, and that sampling with a more-realistic inverse J-shaped population structure exacerbated this bias. However our simulations also demonstrate that these biases rapidly become negligible with increasing sample sizes or as survival increases. For many of the sample sizes used in demographic studies, matrix models are probably robust to the biases resulting from sampling variance of vital rates. However, this conclusion may depend on the structure of populations or the distribution of sampling effort in ways that are unexplored. We suggest more intensive sampling of populations when individual survival is low and greater sampling of stages with high
Effects of sample size on estimates of population growth rates calculated with matrix models.
Fiske, Ian J; Bruna, Emilio M; Bolker, Benjamin M
2008-08-28
Matrix models are widely used to study the dynamics and demography of populations. An important but overlooked issue is how the number of individuals sampled influences estimates of the population growth rate (lambda) calculated with matrix models. Even unbiased estimates of vital rates do not ensure unbiased estimates of lambda-Jensen's Inequality implies that even when the estimates of the vital rates are accurate, small sample sizes lead to biased estimates of lambda due to increased sampling variance. We investigated if sampling variability and the distribution of sampling effort among size classes lead to biases in estimates of lambda. Using data from a long-term field study of plant demography, we simulated the effects of sampling variance by drawing vital rates and calculating lambda for increasingly larger populations drawn from a total population of 3842 plants. We then compared these estimates of lambda with those based on the entire population and calculated the resulting bias. Finally, we conducted a review of the literature to determine the sample sizes typically used when parameterizing matrix models used to study plant demography. We found significant bias at small sample sizes when survival was low (survival = 0.5), and that sampling with a more-realistic inverse J-shaped population structure exacerbated this bias. However our simulations also demonstrate that these biases rapidly become negligible with increasing sample sizes or as survival increases. For many of the sample sizes used in demographic studies, matrix models are probably robust to the biases resulting from sampling variance of vital rates. However, this conclusion may depend on the structure of populations or the distribution of sampling effort in ways that are unexplored. We suggest more intensive sampling of populations when individual survival is low and greater sampling of stages with high elasticities.
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
Nordenfors, C
1999-02-01
To determine dose rate in a gamma radiation field, based on measurements with a semiconductor detector, it is necessary to know how the detector effects the field. This work aims to describe this effect with Monte Carlo simulations and calculations, that is to identify the detector response function. This is done for a germanium gamma detector. The detector is normally used in the in-situ measurements that is carried out regularly at the department. After the response function is determined it is used to reconstruct a spectrum from an in-situ measurement, a so called unfolding. This is done to be able to calculate fluence rate and dose rate directly from a measured (and unfolded) spectrum. The Monte Carlo code used in this work is EGS4 developed mainly at Stanford Linear Accelerator Center. It is a widely used code package to simulate particle transport. The results of this work indicates that the method could be used as-is since the accuracy of this method compares to other methods already in use to measure dose rate. Bearing in mind that this method provides the nuclide specific dose it is useful, in radiation protection, since knowing what the relations between different nuclides are and how they change is very important when estimating the risks
Calculating in situ degradation rates of hydrocarbon compounds in deep waters of the Gulf of Mexico.
Thessen, Anne E; North, Elizabeth W
2017-09-15
Biodegradation is an important process for hydrocarbon weathering that influences its fate and transport, yet little is known about in situ biodegradation rates of specific hydrocarbon compounds in the deep ocean. Using data collected in the Gulf of Mexico below 700m during and after the Deepwater Horizon oil spill, we calculated first-order degradation rate constants for 49 hydrocarbons and inferred degradation rate constants for an additional 5 data-deficient hydrocarbons. Resulting calculated (not inferred) half-lives of the hydrocarbons ranged from 0.4 to 36.5days. The fastest degrading hydrocarbons were toluene (k=-1.716), methylcyclohexane (k=-1.538), benzene (k=-1.333), and C1-naphthalene (k=-1.305). The slowest degrading hydrocarbons were the large straight-chain alkanes, C-26 through C-33 (k=-0.0494 through k=-0.007). Ratios of C-18 to phytane supported the hypothesis that the primary means of degradation in the subsurface was microbial biodegradation. These degradation rate constants can be used to improve models describing the fate and transport of hydrocarbons in the event of an accidental deep ocean oil spill. Copyright © 2017 Elsevier Ltd. All rights reserved.
Error rate of automated calculation for wound surface area using a digital photography.
Yang, S; Park, J; Lee, H; Lee, J B; Lee, B U; Oh, B H
2018-02-01
Although measuring would size using digital photography is a quick and simple method to evaluate the skin wound, the possible compatibility of it has not been fully validated. To investigate the error rate of our newly developed wound surface area calculation using digital photography. Using a smartphone and a digital single lens reflex (DSLR) camera, four photographs of various sized wounds (diameter: 0.5-3.5 cm) were taken from the facial skin model in company with color patches. The quantitative values of wound areas were automatically calculated. The relative error (RE) of this method with regard to wound sizes and types of camera was analyzed. RE of individual calculated area was from 0.0329% (DSLR, diameter 1.0 cm) to 23.7166% (smartphone, diameter 2.0 cm). In spite of the correction of lens curvature, smartphone has significantly higher error rate than DSLR camera (3.9431±2.9772 vs 8.1303±4.8236). However, in cases of wound diameter below than 3 cm, REs of average values of four photographs were below than 5%. In addition, there was no difference in the average value of wound area taken by smartphone and DSLR camera in those cases. For the follow-up of small skin defect (diameter: <3 cm), our newly developed automated wound area calculation method is able to be applied to the plenty of photographs, and the average values of them are a relatively useful index of wound healing with acceptable error rate. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Dos Santos, Adimir; Siqueira, Paulo de Tarso D.; Andrade e Silva, Graciete Simões; Grant, Carlos; Tarazaga, Ariel E.; Barberis, Claudia
2013-01-01
In year 2008 the Atomic Energy National Commission (CNEA) of Argentina, and the Brazilian Institute of Energetic and Nuclear Research (IPEN), under the frame of Nuclear Energy Argentine Brazilian Agreement (COBEN), among many others, included the project “Validation and Verification of Calculation Methods used for Research and Experimental Reactors . At this time, it was established that the validation was to be performed with models implemented in the deterministic codes HUEMUL and PUMA (cell and reactor codes) developed by CNEA and those ones implemented in MCNP by CNEA and IPEN. The necessary data for these validations would correspond to theoretical-experimental reference cases in the research reactor IPEN/MB-01 located in São Paulo, Brazil. The staff of the group Reactor and Nuclear Power Studies (SERC) of CNEA, from the argentine side, performed calculations with deterministic models (HUEMUL-PUMA) and probabilistic methods (MCNP) modeling a great number of physical situations of de reactor, which previously have been studied and modeled by members of the Center of Nuclear Engineering of the IPEN, whose results were extensively provided to CNEA. In this paper results of comparison of calculated and experimental results for temperature coefficients, kinetic parameters and fission rates spatial distributions are shown. (author)
A comparative study of different methods for calculating electronic transition rates
Kananenka, Alexei A.; Sun, Xiang; Schubert, Alexander; Dunietz, Barry D.; Geva, Eitan
2018-03-01
We present a comprehensive comparison of the following mixed quantum-classical methods for calculating electronic transition rates: (1) nonequilibrium Fermi's golden rule, (2) mixed quantum-classical Liouville method, (3) mean-field (Ehrenfest) mixed quantum-classical method, and (4) fewest switches surface-hopping method (in diabatic and adiabatic representations). The comparison is performed on the Garg-Onuchic-Ambegaokar benchmark charge-transfer model, over a broad range of temperatures and electronic coupling strengths, with different nonequilibrium initial states, in the normal and inverted regimes. Under weak to moderate electronic coupling, the nonequilibrium Fermi's golden rule rates are found to be in good agreement with the rates obtained via the mixed quantum-classical Liouville method that coincides with the fully quantum-mechanically exact results for the model system under study. Our results suggest that the nonequilibrium Fermi's golden rule can serve as an inexpensive yet accurate alternative to Ehrenfest and the fewest switches surface-hopping methods.
Small groups, large profits: Calculating interest rates in community-managed microfinance
Rasmussen, Ole Dahl
2012-01-01
Savings groups are a widely used strategy for women’s economic resilience – over 80% of members worldwide are women, and in the case described here, 72.5%. In these savings groups it is common to see the interest rate on savings reported as "20-30% annually". Using panel data from 204 groups...... in Malawi, I show that the right figure is likely to be at least twice this figure. For these groups, the annual return is 62%. The difference comes from sector-wide application of a non-standard interest rate calculations and unrealistic assumptions about the savings profile in the groups. As a result......, it is impossible to compare returns in savings groups with returns elsewhere. Moreover, the interest on savings is incomparable to the interest rate on loans. I argue for the use of a standardized comparable metric and suggest easy ways to implement it. Developments of new tools and standard along these lines...
Yue, Ning J.
2008-01-01
As different types of radionuclides (e.g., 131 Cs source) are introduced for clinical use in brachytherapy, the question is raised regarding whether a relatively simple method exists for the derivation of values of the half value layer (HVL) or the tenth value layer (TVL). For the radionuclide that has been clinically used for years, such as 125 I and 103 Pd, the sources have been manufactured and marketed by several vendors with different designs and structures. Because of the nature of emission of low energy photons for these radionuclides, energy spectra of the sources are very dependent on their individual designs. Though values of the HVL or the TVL in certain commonly used shielding materials are relatively small for these low energy photon emitting sources, the question remains how the variations in energy spectra affect the HVL (or TVL) values and whether these values can be calculated with a relatively simple method. A more fundamental question is whether a method can be established to derive the HVL (TVL) values for any brachytherapy sources and for different materials in a relatively straightforward fashion. This study was undertaken to answer these questions. Based on energy spectra, a well established semiempirical mass attenuation coefficient computing scheme was utilized to derive the HVL (TVL) values of different materials for different types of brachytherapy sources. The method presented in this study may be useful to estimate HVL (TVL) values of different materials for brachytherapy sources of different designs and containing different radionuclides