Numerical analysis II essentials
REA, The Editors of; Staff of Research Education Association
1989-01-01
REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Numerical Analysis II covers simultaneous linear systems and matrix methods, differential equations, Fourier transformations, partial differential equations, and Monte Carlo methods.
Czech Academy of Sciences Publication Activity Database
Drnovšek, R.; Müller, Vladimír
2014-01-01
Roč. 62, č. 9 (2014), s. 1197-1204 ISSN 0308-1087 R&D Projects: GA ČR GA201/09/0473; GA AV ČR IAA100190903 Institutional support: RVO:67985840 Keywords : joint numerical range * numerical radius Subject RIV: BA - General Mathematics Impact factor: 0.738, year: 2014 http://www.tandfonline.com/doi/abs/10.1080/03081087.2013.816303
The Turbulent Interstellar Medium: Insights and Questions from Numerical Models
Mac Low, Mordecai-Mark; de Avillez, Miguel A.; Korpi, Maarit J.
2003-01-01
"The purpose of numerical models is not numbers but insight." (Hamming) In the spirit of this adage, and of Don Cox's approach to scientific speaking, we discuss the questions that the latest generation of numerical models of the interstellar medium raise, at least for us. The energy source for the interstellar turbulence is still under discussion. We review the argument for supernovae dominating in star forming regions. Magnetorotational instability has been suggested as a way of coupling di...
Numerical models for the circumstellar medium around Betelgeuse
Mackey, Jonathan; Mohamed, Shazrene; Neilson, Hilding R.; Langer, Norbert; Meyer, Dominique M. -A.
2013-01-01
The nearby red supergiant (RSG) Betelgeuse has a complex circumstellar medium out to at least 0.5 parsecs from its surface, shaped by its mass-loss history within the past 0.1 Myr, its environment, and its motion through the interstellar medium (ISM). In principle its mass-loss history can be constrained by comparing hydrodynamic models with observations. Observations and numerical simulations indicate that Betelgeuse has a very young bow shock, hence the star may have only recently become a ...
Numerical Modeling of Electromagnetic Radiation Within a Particulate Medium.
Noe Dobrea, E. Z.
2017-12-01
Numerical modeling of electromagnetic radiation with a particulate medium. Understanding the effect of particulate media and coatings on electromagnetic radiation is key to understanding the effects of multiple scattering on the spectra of geologic materials. Multiple radiative transfer theories have been developed that provide a good approximation to these effects [1,2]. However, approximations regarding particle size, distribution, shape, and other parameters need to be made and in some cases, the theory is limited to specific geometries [2]. In this work, we seek to develop an numerical radiative transfer algorithm to simulate the passage of light through a particulate medium. The code allows arbitrary particle size distributions (uniform, bimodal, trimodal, composition dependent), compositions, and viewing geometries, as well as arbitrary coating thicknesses and compositions. Here, we report on the the status of our model and present comparisons of model predictions with the spectra of well-characterize minerals and mixtures. Future work will include particle size-dependent effects of diffraction as well as particle emittance due to fluorescence and Raman excitation. [1] Hapke, B. (2012). Theory of reflectance and emittance spectroscopy. Cambridge University Press, 2nd edition, 528 p. [2] Shkuratov et al. (1999) Icarus 137
Numerical models for the circumstellar medium around Betelgeuse
Mackey, J.; Mohamed, S.; Neilson, H. R.; Langer, N.; Meyer, D. M.-A.
2013-05-01
The nearby red supergiant (RSG) Betelgeuse has a complex circumstellar medium out to at least 0.5 parsecs from its surface, shaped by its mass-loss history within the past ≈ 0.1 Myr, its environment, and its motion through the interstellar medium (ISM). In principle its mass-loss history can be constrained by comparing hydrodynamic models with observations. Observations and numerical simulations indicate that Betelgeuse has a very young bow shock, hence the star may have only recently become a RSG. To test this possibility we calculated a stellar evolution model for a single star with properties consistent with Betelgeuse. We incorporated the resulting evolving stellar wind into 2D hydrodynamic simulations to model a runaway blue supergiant (BSG) undergoing the transition to a RSG near the end of its life. The collapsing BSG wind bubble induces a bow shock-shaped inner shell which at least superficially resembles Betelgeuse's bow shock, and has a similar mass. Surrounding this is the larger-scale retreating bow shock generated by the now defunct BSG wind's interaction with the ISM. We investigate whether this outer shell could explain the bar feature located (at least in projection) just in front of Betelgeuse's bow shock.
Inverse regression for ridge recovery II: Numerics
Glaws, Andrew; Constantine, Paul G.; Cook, R. Dennis
2018-01-01
We investigate the application of sufficient dimension reduction (SDR) to a noiseless data set derived from a deterministic function of several variables. In this context, SDR provides a framework for ridge recovery. In this second part, we explore the numerical subtleties associated with using two inverse regression methods---sliced inverse regression (SIR) and sliced average variance estimation (SAVE)---for ridge recovery. This includes a detailed numerical analysis of the eigenvalues of th...
Denisov, A. M.; Zakharov, E. V.; Kalinin, A. V.; Kalinin, V. V.
2010-07-01
A numerical method is proposed for solving an inverse electrocardiography problem for a medium with a piecewise constant electrical conductivity. The method is based on the method of boundary integral equations and Tikhonov regularization.
KARAKTERISTIK ADSORPSI TEMBAGA (II PADA HUMIN DALAM MEDIUM AIR TAWAR
Directory of Open Access Journals (Sweden)
Roy Andreas
2006-11-01
Full Text Available Although humic substances consist mosly of humin (65%, however its characteristic in Cu(II odsorption is not yet clearly revealed. In this work, humin was isolated from peat soil of west Kalimantan, purified and then interacted with Cu(II. The purity of isolated humin was determined by its ash content. The funtional group in this purified humin was characterized qualitatively by FTIR and quantitatively by titration. Study on the solubility of Cu(II in freshwater was carried out at pH from 2-12 in the presence and without purified humin. To obtain adsorption kinetic parameters of Cu(II on humin in freshwater, study based on Langmuir-Hinshelwood was carried out, while for its thermodinamics parameters, a study based on Langmuir and Freundlich were employed. The ash content of purified humin was 1,58 % (w/w, it showed that the humin was in pure condition. The active fungtional group identified humin were –COOH (1700 cm-1 115 cmol/kg and –OH fenolic (3421,5 cm-1 562 cmol/kg. At 27 all of Cu(II was precipitated as Cu(OH2. The rate constant for Cu(II in freshwater medium were 2,7 x 10-3 S-1 and 0,6 x 10-3 S-1. The obtained curve fitting of langmuir and freundlich adsorption showed that Langmuir model fit better than Freundlich, indicated that the adsorption reaction are of monolayer. The adsorption capacities of Cu(II on humin in freshwater was 3,033 x 10-4 mol/g
KARAKTERISTIK ADSORPSI TEMBAGA (II PADA HUMIN DALAM MEDIUM AIR TAWAR
Directory of Open Access Journals (Sweden)
Roy Andreas
2006-05-01
Full Text Available Although humic substances consist mosly of humin (65%, however its characteristic in Cu(II odsorption is not yet clearly revealed. In this work, humin was isolated from peat soil of west Kalimantan, purified and then interacted with Cu(II. The purity of isolated humin was determined by its ash content. The funtional group in this purified humin was characterized qualitatively by FTIR and quantitatively by titration. Study on the solubility of Cu(II in freshwater was carried out at pH from 2-12 in the presence and without purified humin. To obtain adsorption kinetic parameters of Cu(II on humin in freshwater, study based on Langmuir-Hinshelwood was carried out, while for its thermodinamics parameters, a study based on Langmuir and Freundlich were employed. The ash content of purified humin was 1,58 % (w/w, it showed that the humin was in pure condition. The active fungtional group identified humin were –COOH (1700 cm-1 115 cmol/kg and –OH fenolic (3421,5 cm-1 562 cmol/kg. At 27 all of Cu(II was precipitated as Cu(OH2. The rate constant for Cu(II in freshwater medium were 2,7 x 10-3 S-1 and 0,6 x 10-3 S-1. The obtained curve fitting of langmuir and freundlich adsorption showed that Langmuir model fit better than Freundlich, indicated that the adsorption reaction are of monolayer. The adsorption capacities of Cu(II on humin in freshwater was 3,033 x 10-4 mol/g
Collisionless microinstabilities in stellarators. II. Numerical simulations
Energy Technology Data Exchange (ETDEWEB)
Proll, J. H. E.; Xanthopoulos, P.; Helander, P. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)
2013-12-15
Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.
Directory of Open Access Journals (Sweden)
V. M. Mikhailov
2017-12-01
Full Text Available Purpose. Testing of numerical solution algorithm for integral equation for calculation of plane meridian magnetostatic field source distribution at interfaces of piecewise homogeneous magnetized medium by means of electrostatic analogy. Methodology. The piecewise homogeneous medium consists of three regions with different magnetic permeabilities: the shell of arbitrary meridian section, external unlimited medium outside the shell, and the medium inside the shell. For testing external homogeneous magnetic field effect on spherical shell is considered. The analytical solution of this problem on the basis of electrostatic analogy from the solution of the problem uniform electrostatic field effect on dielectric shell is obtained. We have compared results of numerical solution of integral equation with the data obtained by means of analytical solution at the variation of magnetic permeabilities of regions of medium. Results. Integral equation and the algorithm of its numerical solution for calculation of source field distribution at the boundaries of piecewise homogeneous medium is validated. Testing of integral equations correctness for calculation of fictitious magnetic charges distribution on axisymmetric boundaries of piecewise homogeneous magnetized medium and algorithms of their numerical solutions can be carried out by means of analytical solutions of problems of homogeneous electrostatic field effect analysis on piecewise homogeneous dielectric medium with central symmetry of boundaries – single-layer and multilayer spherical shells. In the case of spherical shell in wide range of values of the parameter λk, including close to ± 1, numerical solution of integral equation is stable, and relative error in calculating of fictitious magnetic charges surface density and magnetic field intensity inside the shell is from tenths of a percent up to several percent except for the cases of very small values of these quantities. Originality. The use
Energy Technology Data Exchange (ETDEWEB)
Khattri, Sanjay Kumar
2006-07-01
The thesis is concerned with numerically simulating multicomponent, multiphase, reactive transport in heterogeneous porous medium. Such processes are ubiquitous, for example, deposition of green house gases, flow of hydrocarbons and groundwater remediation. Understanding such processes is important from social and economic point of view. For the success of geological sequestration, an accurate estimation of migration patterns of green-house gases is essential. Due to an ever increasing computer power, computational mathematics has become an important tool for predicting dynamics of porous media fluids. Numerical and mathematical modelling of processes in a domain requires grid generation in the domain, discretization of the continuum equations on the generated grid, solution of the formed linear or nonlinear system of discrete equations and finally visualization of the results. The thesis is composed of three chapters and eight papers. Chapter 2 presents two techniques for generating structured quadrilateral and hexahedral meshes. These techniques are called algebraic and elliptic methods. Algebraic techniques are by far the most simple and computationally efficient method for grid generation. Transfinite interpolation operators are a kind of algebraic grid generation technique. In this chapter, many transfinite interpolation operators for grid generation are derived from 1D projection operators. In this chapter, some important properties of hexahedral elements are also mentioned. These properties are useful in discretization of partial differential equations on hexahedral mesh, improving quality of the hexahedral mesh, mesh generation and visualization. Chapter 3 is about CO{sub 2} flow in porous media. In this chapter, we present the mathematical models and their discretization for capturing major physical processes associated with CO{sub 2} deposition in geological formations. Some important simulations of practical applications in 2D and 3D are presented
Numerical simulation for a two-phase porous medium flow problem with rate independent hysteresis
Brokate, M.
2012-05-01
The paper is devoted to the numerical simulation of a multiphase flow in porous medium with a hysteretic relation between the capillary pressures and the saturations of the phases. The flow model we use is based on Darcys law. The hysteretic relation between the capillary pressures and the saturations is described by a play-type hysteresis operator. We propose a numerical algorithm for treating the arising system of equations, discuss finite element schemes and present simulation results for the case of two phases. © 2011 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Bartlewska-Urban Monika
2016-03-01
Full Text Available The following study presents numerical calculations for establishing the impact of temperature changes on the process of distortion of bi-phase medium represented using Biot consolidation equations with Kelvin–Voigt rheological skeleton presented, on the example of thermo-consolidation of a pavement of expressway S17. We analyzed the behavior of the expressway under the action of its own weight, dynamic load caused by traffic and temperature gradient. This paper presents the application of the Biot consolidation model with the Kelvin–Voigt skeleton rheological characteristics and the influence of temperature on the deformation process is taken into account. A three-dimensional model of the medium was created describing the thermal consolidation of a porous medium. The 3D geometrical model of the area under investigation was based on data obtained from the land surveying and soil investigation of a 200 m long section of the expressway and its shoulders.
Maddix, Danielle C.; Sampaio, Luiz; Gerritsen, Margot
2018-05-01
The degenerate parabolic Generalized Porous Medium Equation (GPME) poses numerical challenges due to self-sharpening and its sharp corner solutions. For these problems, we show results for two subclasses of the GPME with differentiable k (p) with respect to p, namely the Porous Medium Equation (PME) and the superslow diffusion equation. Spurious temporal oscillations, and nonphysical locking and lagging have been reported in the literature. These issues have been attributed to harmonic averaging of the coefficient k (p) for small p, and arithmetic averaging has been suggested as an alternative. We show that harmonic averaging is not solely responsible and that an improved discretization can mitigate these issues. Here, we investigate the causes of these numerical artifacts using modified equation analysis. The modified equation framework can be used for any type of discretization. We show results for the second order finite volume method. The observed problems with harmonic averaging can be traced to two leading error terms in its modified equation. This is also illustrated numerically through a Modified Harmonic Method (MHM) that can locally modify the critical terms to remove the aforementioned numerical artifacts.
Numerical Investigations of Moisture Distribution in a Selected Anisotropic Soil Medium
Iwanek, M.
2018-01-01
The moisture of soil profile changes both in time and space and depends on many factors. Changes of the quantity of water in soil can be determined on the basis of in situ measurements, but numerical methods are increasingly used for this purpose. The quality of the results obtained using pertinent software packages depends on appropriate description and parameterization of soil medium. Thus, the issue of providing for the soil anisotropy phenomenon gains a big importance. Although anisotropy can be taken into account in many numerical models, isotopic soil is often assumed in the research process. However, this assumption can be a reason for incorrect results in the simulations of water changes in soil medium. In this article, results of numerical simulations of moisture distribution in the selected soil profile were presented. The calculations were conducted assuming isotropic and anisotropic conditions. Empirical verification of the results obtained in the numerical investigations indicated statistical essential discrepancies for the both analyzed conditions. However, better fitting measured and calculated moisture values was obtained for the case of providing for anisotropy in the simulation model.
KARAKTERISTIK ADSORPSI TEMBAGA (II) PADA HUMIN DALAM MEDIUM AIR TAWAR
Roy Andreas; Narsito Narsito; Sri Noegrohati
2006-01-01
Although humic substances consist mosly of humin (65%), however its characteristic in Cu(II) odsorption is not yet clearly revealed. In this work, humin was isolated from peat soil of west Kalimantan, purified and then interacted with Cu(II). The purity of isolated humin was determined by its ash content. The funtional group in this purified humin was characterized qualitatively by FTIR and quantitatively by titration. Study on the solubility of Cu(II) in freshwater was carried out at pH from...
Energy Technology Data Exchange (ETDEWEB)
Vasilic, Ksenija
2016-05-01
This thesis addresses numerical simulations of self-compacting concrete (SCC) castings and suggests a novel modelling approach that treats reinforcement zones in a formwork as porous media. As a relatively new field in concrete technology, numerical simulations of fresh concrete flow can be a promising aid to optimise casting processes and to avoid on-site casting incidents by predicting the flow behaviour of concrete during the casting process. The simulations of fresh concrete flow generally involve complex mathematical modelling and time-consuming computations. In case of a casting prediction, the simulation time is additionally significantly increased because each reinforcement bar occurring in succession has to be considered one by one. This is particularly problematic when simulating SCC casting, since this type of concrete is typically used for heavily reinforced structural members. However, the wide use of numerical tools for casting prediction in practice is possible only if the tools are user-friendly and simulations are time-saving. In order to shorten simulation time and to come closer to a practical tool for casting prediction, instead to model steel bars one by one, this thesis suggests to model zones with arrays of steel bars as porous media. Consequently, one models the flow of SCC through a reinforcement zone as a free-surface flow of a non-Newtonian fluid, propagating through the medium. By defining characteristic parameters of the porous medium, the influence on the flow and the changed (apparent) behaviour of concrete in the porous matrix can be predicted. This enables modelling of any reinforcement network as a porous zone and thus significantly simplifies and fastens simulations of reinforced components' castings. Within the thesis, a computational model for SCC flow through reinforced sections was developed. This model couples a fluid dynamics model for fresh concrete and the macroscopic approach for the influence of the porous medium
International Nuclear Information System (INIS)
Vasilic, Ksenija
2016-01-01
This thesis addresses numerical simulations of self-compacting concrete (SCC) castings and suggests a novel modelling approach that treats reinforcement zones in a formwork as porous media. As a relatively new field in concrete technology, numerical simulations of fresh concrete flow can be a promising aid to optimise casting processes and to avoid on-site casting incidents by predicting the flow behaviour of concrete during the casting process. The simulations of fresh concrete flow generally involve complex mathematical modelling and time-consuming computations. In case of a casting prediction, the simulation time is additionally significantly increased because each reinforcement bar occurring in succession has to be considered one by one. This is particularly problematic when simulating SCC casting, since this type of concrete is typically used for heavily reinforced structural members. However, the wide use of numerical tools for casting prediction in practice is possible only if the tools are user-friendly and simulations are time-saving. In order to shorten simulation time and to come closer to a practical tool for casting prediction, instead to model steel bars one by one, this thesis suggests to model zones with arrays of steel bars as porous media. Consequently, one models the flow of SCC through a reinforcement zone as a free-surface flow of a non-Newtonian fluid, propagating through the medium. By defining characteristic parameters of the porous medium, the influence on the flow and the changed (apparent) behaviour of concrete in the porous matrix can be predicted. This enables modelling of any reinforcement network as a porous zone and thus significantly simplifies and fastens simulations of reinforced components' castings. Within the thesis, a computational model for SCC flow through reinforced sections was developed. This model couples a fluid dynamics model for fresh concrete and the macroscopic approach for the influence of the porous medium
Rowley, D R; Tindall, D J
1987-06-01
In vitro studies were conducted to determine whether conditioned medium from rat fetal urogenital sinus explants would affect phenotypic characteristics of NBT-II urinary bladder carcinoma cells in culture. NBT-II cells were exposed to medium (30%, v/v) conditioned for 48 h by intact urogenital sinus explants derived from 18-day fetal rats. Upon exposure for 23 h the [3H]thymidine incorporation by NBT-II cells was decreased by 40.3% relative to control cultures. This effect was paralleled by a similar decrease in proliferation. NBT-II cultures decreased in cell number by 32.1 and 45.8% on days 2 and 4, respectively, after exposure to conditioned medium. Although cell proliferation was inhibited, conditioned medium acted to induce an increase in protein secretion. An increase of 18.6% was observed in the incorporation of [35S]methionine into newly synthesized, secreted proteins by NBT-II cells exposed to conditioned medium for 23 h. Morphologically the NBT-II cells exposed to conditioned medium were larger, more spread out, and exhibited a greater array of lamellipodia and filopodia, although [35S]methionine incorporation into cellular proteins was decreased by 11.1%. These results suggest that diffusable factors produced by fetal urogenital sinus explants can induce changes in proliferation, protein synthesis, protein secretion, and phenotypic morphology of NBT-II carcinoma cells in culture.
Numerical simulation about interaction between pressure swirl spray and hot porous medium
Energy Technology Data Exchange (ETDEWEB)
Zhao Zhiguo [School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024 (China)], E-mail: zhzhguo1978@163.com; Xie Maozhao [School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024 (China)
2008-05-15
To gain a deep understanding of the process of the fuel/air mixture formation and the role of the PM (porous medium) in mixture homogenization and combustion in a PM engine, the interaction of a pressure swirl spray and a hot porous medium was investigated computationally by using the modified KIVA-3V code in which an improved spray/hot wall interaction model was incorporated. The improved spray/hot wall interaction model fits into the regime above the Leidenfrost temperature, determines the properties of post-impingement fuel droplets and the quantity of heat transfer between the fuel droplets and a hot surface. An evaporating fuel spray impingement on a hot plane surface was simulated for validating the reasonability of the improved spray/hot wall interaction model. Numerical results compared well with experimental data for spray radius in the liquid and vapor phases. The linearized instability sheet atomization (LISA) model has been used to describe the atomization and breakup processes of the spray from the pressure swirl atomizers. The structure of a hot porous medium with porosity of 0.88 was established using a simple model. The injection, movement and vaporization of the fuel droplets inside the PM and their impingement on the block edges was computed. Consequently, the spatial distribution and time evolution of the temperature and fuel concentration inside the PM were obtained. The influences of the operating parameters, including ambient pressure and spray cone angle, on the characteristics of the fuel spray and mixture formation were discussed based on the numerical simulations. The basic aspects of the interaction between the pressure swirl spray and the hot porous medium have been revealed by the computational results.
Using numerical models of bow shocks to investigate the circumstellar medium of massive stars
International Nuclear Information System (INIS)
Van Marle, A J; Decin, L; Cox, N L J; Meliani, Z
2015-01-01
Many massive stars travel through the interstellar medium at supersonic speeds. As a result they form bow shocks at the interface between the stellar wind. We use numerical hydrodynamics to reproduce such bow shocks numerically, creating models that can be compared to observations. In this paper we discuss the influence of two physical phenomena, interstellar magnetic fields and the presence of interstellar dust grains on the observable shape of the bow shocks of massive stars. We find that the interstellar magnetic field, though too weak to restrict the general shape of the bow shock, reduces the size of the instabilities that would otherwise be observed in the bow shock of a red supergiant. The interstellar dust grains, due to their inertia can penetrate deep into the bow shock structure of a main sequence O-supergiant, crossing over from the ISM into the stellar wind. Therefore, the dust distribution may not always reflect the morphology of the gas. This is an important consideration for infrared observations, which are dominated by dust emission. Our models clearly show, that the bow shocks of massive stars are useful diagnostic tools that can used to investigate the properties of both the stellar wind as well as the interstellar medium
Numerical Simulation of Transient Free Convection Flow and Heat Transfer in a Porous Medium
Directory of Open Access Journals (Sweden)
Rajesh Sharma
2013-01-01
Full Text Available The coupled momentum and heat transfer in unsteady, incompressible flow along a semi-infinite vertical porous moving plate adjacent to an isotropic porous medium with viscous dissipation effect are investigated. The Darcy-Forchheimer nonlinear drag force model which includes the effects of inertia drag forces is employed. The governing differential equations of the problem are transformed into a system of nondimensional differential equations which are solved numerically by the finite element method (FEM. The non-dimensional velocity and temperature profiles are presented for the influence of Darcy number, Forchheimer number, Grashof number, Eckert number, Prandtl number, plate velocity, and time. The Nusselt number is also evaluated and compared with finite difference method (FDM, which shows excellent agreement.
Numerical study of forced convection in a vertical channel filled with heat-generating porous medium
International Nuclear Information System (INIS)
Yang Jian; Zeng Min; Wang Qiuwang; Yan Xiao
2009-01-01
Steady laminar non-Darcian forced convection in a vertical channel filled with heat-generating porous medium is studied numerically by using the local thermal non-equilibrium model. The heat source generated by solid framework is uniform and kept constant; and the temperature of vertical walls is kept at constant temperature T 0 . The flow inside porous medium is modelled by using Forchheimer-Brinkman extended Darcy model. The effects of Reynolds number (0.5 ≤Re ≤ 50), effective fluid-to-solid thermal conductivity ratio Γ(0.001 ≤ Γ ≤ 1.0)and Darcy number (10 -3 ≤ Da ≤ 10 -5 ) are analyzed in detail. It is found that, the effects of Re, Γ and Da are remarkable; at low values of Re and Γ, and at high value of Da, the effect of local thermal non-equilibrium is significant and the local thermal non-equilibrium model should be adopted for predicting the heat transfer characteristics exactly. (authors)
Numerical Simulations of Supernova Remnant Evolution in a Cloudy Interstellar Medium
Energy Technology Data Exchange (ETDEWEB)
Slavin, Jonathan D.; Smith, Randall K.; Foster, Adam; Winter, Henry D.; Raymond, John C.; Slane, Patrick O. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Yamaguchi, Hiroya, E-mail: jslavin@cfa.harvard.edu [NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States)
2017-09-01
The mixed morphology class of supernova remnants has centrally peaked X-ray emission along with a shell-like morphology in radio emission. White and Long proposed that these remnants are evolving in a cloudy medium wherein the clouds are evaporated via thermal conduction once being overrun by the expanding shock. Their analytical model made detailed predictions regarding temperature, density, and emission profiles as well as shock evolution. We present numerical hydrodynamical models in 2D and 3D including thermal conduction, testing the White and Long model and presenting results for the evolution and emission from remnants evolving in a cloudy medium. We find that, while certain general results of the White and Long model hold, such as the way the remnants expand and the flattening of the X-ray surface brightness distribution, in detail there are substantial differences. In particular we find that the X-ray luminosity is dominated by emission from shocked cloud gas early on, leading to a bright peak, which then declines and flattens as evaporation becomes more important. In addition, the effects of thermal conduction on the intercloud gas, which is not included in the White and Long model, are important and lead to further flattening of the X-ray brightness profile as well as lower X-ray emission temperatures.
The effect of UV stars on the intergalactic medium. II
International Nuclear Information System (INIS)
Sonnanstine, A.E.; Hills, J.G.
1976-01-01
The effect of ionizing radiation from the UV stars (hot prewhite dwarfs) on the intergalactic medium (IGM) has been investigated. If the UV stars are powered only by gravitational contraction they radiate most of their energy at a typical surface temperature of 1.5 x 10 5 K which produces a very highly ionized IGM in which the elements carbon, nitrogen and oxygen are left with only one or two electrons. This result in these elements being very inefficient coolants. The gas is cooled principally by free-free emission and the collisional ionization of hydrogen and helium. For a typical UV star temperature of T=1.5 x 10 5 K, the temperature of the ionized gas in the IGM is Tsub(g)=1.2 x 10 5 K for a Hubble constant H 0 =75 kms -1 Mpc -1 and a hydrogen density nsub(H)=10 -6 cm -3 . Heating by cosmic rays and X-rays is insignificant in the IGM except perhaps in the H I clouds because when a hydrogen atom recombines in the IGM it is far more likely to be re-ionized by a UV-star photon than by either of the other two types of particles due to the greater space density of UV-star photons and their appreciably larger ionization cross sections. If the UV stars radiate a substantial fraction of their energy in a helium-burning stage in which they have surface temperatures of about 5 x 10 4 K, the temperature of the IGM could be lowered to about 5 x 10 4 K. (Auth.)
Experimental validation of a numerical model of two-phase displacement in porous medium
International Nuclear Information System (INIS)
Genty, A.
1996-01-01
Burial in geological layers appears to be an interesting solution to dispose of radioactive wastes. This thesis analyzes and simulates the behaviour of gas produced by waste barrels corrosion. The released contaminated gas drains the water initially present in the host rock and yields a water-gas two phase flow. A literature survey of two phase flow shows that fluid interfaces may display instabilities for definite flow characteristics. When the displacement is stable a smooth interface proceeds through the porous medium. When the interface shows fingering, the displacement is said to be 'viscous-unstable', and when the front is jagged the displacement is called 'capillary' displacement. A dimensional analysis of classical equations governing two phase flow in porous media is combined with a classification of dominant forces to define an original map of flow regimes that includes gravitational forces. The map is based on three dimensionless numbers and predicts a priori the flow type. For typical data describing a radioactive waste repository a 'viscous-unstable' displacement is predicted by the map. We simulate water-gas displacement with a numerical model previously developed; this code, based on the Muskat model, uses the mixed-hybrid finite elements technique and is therefore well adapted for tracking moving interfaces. Fluxes are well conserved, however instabilities cannot be simulated. We assume that there is always a scale to be found where instabilities can be averaged and we try to validate the model with experimental two phase flows. We performed laboratory water-gas flow experiments for a variety of flow conditions. The observed displacement types are consistent with the map of flow regimes. Good agreement with numerical simulations is obtained when precise parameters of the displacements are available, in particular relative permeability curves. We conclude that our model allows a first approach of migration of gas near a radioactive waste repository
Wei, Qin; Yan, Liangguo; Chang, Guohua; Ou, Qingyu
2003-02-06
A new catalytic kinetic spectrophotometric method has been developed for the determination of trace amount of manganese (II) in nonionic microemulsion medium. The method is based on the catalytic effect of manganese (II) on the oxidation of dahlia violet by potassium periodate with nitrilotriacetic acid as an activitor in the presence of nonionic microemulsion. Under the optimum conditions, the calibration graph is linear in the range of 0.0004-0.0056 mug ml(-1) of manganese (II) at 580 nm. The detection limit achieved is 3.75x10(-5) mug ml(-1). Manganese (II) in foodstuff samples was determined with satisfactory results.
International Nuclear Information System (INIS)
Ahmed, M.; El Dessouky, S.I.; El-Nadi, Y.A.; Daoud, J.A.; Saad, E.A.
2008-01-01
The paper aims to study the extraction and separation of Cd(II), Co(II) and Ni(II) from their mixtures in hydrochloric acid medium with CYANEX 923 in kerosene. Preliminary investigations showed that only Cd(II) is extracted with CYANEX 923 while Co(II) and Ni(II) are not extracted. Different parameters affecting the extraction of Cd(II) with CYANEX 923 such as hydrochloric acid, hydrogen ion, extractant and metal concentrations, temperature investigations were also investigated. The stoichiometry of the extracted metal species investigated was found to be HCdCl 3 . 2 CYANEX 923. The stripping of the extracted Cd(II) species is obtained with 0.1 M HCl solution. Co(II) was found to be extracted with CYANEX 272 at ph 5.8 leaving Ni(II) in the solution. A developed process for the sequential of Cd(II), Co(II) and Ni(II) from their mixture in hydrochloric acid medium is proposed
Numerical method for nitrogen and steam injection in a porous medium with water
Energy Technology Data Exchange (ETDEWEB)
Lambert, Wanderson; Marchesin, Dan; Albuquerque, Daniel L. [Instituto de Matematica Pura e Aplicada (IMPA), Rio de Janeiro, RJ (Brazil); Bruining, Johannes [TUDELFT (Netherlands)
2004-07-01
The frequent widespread occurrence of contamination due to spills and leaks of organic materials, such as petroleum products, that occur during their transport, storage and disposal constitute a menace to our high-quality ground-water resources. In spite of increased awareness of the environmental impacts of oil spills, it appears to be impossible to avoid these accidents, so it is necessary to develop techniques of groundwater remediation. Traditional clean up methods of these spills, such as pump-and-treat are slow because diffusion/dissolution are the main removal mechanisms used. Removal of contaminants with steam is considered an alternative solution. Steam injection is widely studied in Petroleum Engineering see 'Bruining et. al. (2003)'. From mass balance and conservation of enthalpy equations, we formulate conservation laws governing steam and nitrogen injection in a linear porous medium containing water. Compressibility, heat conductivity and capillarity are neglected. We present an upstream semi implicit method to solve numerically this model, so that optimal clean up strategies can be developed. (author)
Numerical simulation of springback of medium-thick plates in local hot rolling
Directory of Open Access Journals (Sweden)
XIE Dong
2017-10-01
Full Text Available [Objectives] In order to understand the factors of springback in the local hot rolling of medium-thick steel plates,[Methods] a 3D thermal-elastic-plastic analysis is conducted to investigate the factors affecting the amount of springback. Through a series of numerical analyses,the influence of deformation temperature,temperature field distribution,plate size and local loading are examined. [Results] The results show that when the deformation temperature exceeds a certain level at which material yield stress begins to decrease significantly,the springback will reduce markedly with the increase in temperature. Due to the distribution characteristics of the deformation area,the influence of temperature distribution on springback where the local deformation scale is larger is dominated by the three dimensions of temperature field distribution. Changes in the length and width of the plate have a certain influence on the springback,in which changes to the length of a plate where the local deformation scale is larger have a more obvious influence on springback. The springback of the plate decreases with the increase of local loading. [Conclusions] The results of this study can assist in the optimization of parameters in the automatic hot rolling of thick plates,while also having a basic guiding effect on the further study of springback in the local hot rolling of thick plates.
Recovery of copper(II) and chromium(III) from nitrate medium with ...
African Journals Online (AJOL)
The solvent extraction of copper(II) and chromium(III) from nitrate medium with salicylideneaniline (HL) is studied as a function of various parameters: pH, concentration of salicylideneaniline, contact time and the nature of anoin (nitrate and sulfate) in aqueous phase. Chromium(III) is not extracted by salicylideneaniline ...
Study of the extraction of cobalt(II) from sulphate medium by using ...
African Journals Online (AJOL)
In this work we have first investigated the extraction of cobalt(II) from sulphate medium using capric acid dissolved in chloroform and then the effect of other diluents on the extraction process at 25°C. This study aims to understand the behaviour followed by this metal or, in other words, find its stoichiometry at the end of the ...
Naini, Farhad B; Gill, Daljit S; Payne, Ed; Keel, Bill
2007-01-01
Early identification of Class II deep bite malocclusion is essential for a successful treatment outcome. Timely treatment with functional appliances is among the most effective treatment approaches available for the management of Class II malocclusion in growing subjects. The Medium Opening Activator belongs to a family of functional appliances known as activators. The aims of this article are to review the clinical management of the Medium Opening Activator and to describe a number of appliance modifications, including: (1) a method of stepwise advancement of the mandible using the same appliance; (2) modifications allowing transverse expansion of the maxillary posterior segments, and anterior movement of the maxillary labial segment in 1 appliance, negating the need for a prefunctional phase of treatment; and (3) placing mandibular fixed appliances early. A case report is described to demonstrate the benefits of the Medium Opening Activator. © 2007 Quintessence Publishing Co, Inc.
Méndez, David I.; Alcaraz, M. Ángeles
2016-01-01
Introduction: We report an investigation on collaboration practices in research papers published in the most prestigious English-medium astrophysics journals. Method: We propose an evaluation method based on three numerical indicators to study and compare, in absolute terms, three different types of collaboration (international, national and…
FuzzySRI-II A fuzzy rule induction algorithm for numerical output prediction
Afifi, A.
2014-01-01
Current inductive learning algorithms have difficulties handling attributes with numerical output values. This paper presents FuzzySRI-II, a new fuzzy rule induction algorithm for the prediction of numerical outputs. FuzzySRI-II integrates the comprehensibility and ease of application of rule induction algorithms with the uncertainty handling and approximate reasoning capabilities of fuzzy sets. The performance of the proposed FuzzySRI-II algorithm in two simulated control applications involv...
International Nuclear Information System (INIS)
Timoumi, M.; Cherif, B.; Sifaoui, M.S.
2005-01-01
In this paper, heat transfer problem through a semi-transparent porous medium in a cylindrical enclosure is investigated. The governing equations for this problem and the boundary conditions are non-linear differential equations depending on the dimensionless radial coordinate, Planck number N, scattering albedo ω, walls emissivity and thermal conductivity ratio k r . The set of differential equations are solved by a numerical technique taken from the IMSL MATH/LIBRARY. Various results are obtained for the dimensionless temperature profiles in the solid and fluid phases and the radiative heat flux. The effects of some radiative properties of the medium on the heat transfer rate are examined
Numerical Relativity, Black Hole Mergers, and Gravitational Waves: Part II
Centrella, Joan
2012-01-01
This series of 3 lectures will present recent developments in numerical relativity, and their applications to simulating black hole mergers and computing the resulting gravitational waveforms. In this second lecture, we focus on simulations of black hole binary mergers. We hig hlight the instabilities that plagued the codes for many years, the r ecent breakthroughs that led to the first accurate simulations, and the current state of the art.
Directory of Open Access Journals (Sweden)
G. A. Sheikhzadeh
2013-07-01
Full Text Available Steady state natural convection of Al2O3-water nanofluid inside a square cavity filled with a porous medium is investigated numerically. The temperatures of the two side walls of the cavity are maintained at TH and TC, where TC has been considered as the reference condition. The top and the bottom horizontal walls have been considered to be insulated i.e., non-conducting and impermeable to mass transfer. Darcy–Forchheimer model is used to simulate the momentum transfer in the porous medium. The transport equations are solved numerically with finite volume approach using SIMPLER algorithm. The numerical procedure is adopted in the present study yields consistent performance over a wide range of parameters (Rayleigh number, Ra, 104≤ Ra≤ 106, Darcy number, Da, 10-5≤ Da ≤ 10-3, and solid volume fraction, j, 0.0 ≤ j ≤ 0.1. Numerical results are presented in terms of streamlines, isotherms and average Nusselt number. It was found that heat transfer increases with increasing of both Rayleigh number and Darcy number. It is further observed that the heat transfer in the cavity is improved with the increasing of solid volume fraction parameter of nanofluids.
Numerical simulation of the PEP-II beam position monitor
Energy Technology Data Exchange (ETDEWEB)
Kurita, N.; Martin, D.; Ng, C.-K.; Smith, S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T.
1996-08-01
We use MAFIA to analyze the PEP-II button-type beam position monitor (BPM). Employing proper termination of the BPM into a coaxial cable, the output signal at the BPM is determined. Thus the issues of signal sensitivity and power output can be addressed quantitatively, including all transient effects and wakefields. Besides this first quantitative analysis of a true BPM 3D structure, we find that internal resonant modes are a major source of high value narrow-band impedances. The effects of these resonances on coupled-bunch instabilities are discussed. An estimate of the power dissipation in the ceramic vacuum seal under high current operation is given. (author)
Numerical method for solving integral equations of neutron transport. II
International Nuclear Information System (INIS)
Loyalka, S.K.; Tsai, R.W.
1975-01-01
In a recent paper it was pointed out that the weakly singular integral equations of neutron transport can be quite conveniently solved by a method based on subtraction of singularity. This previous paper was devoted entirely to the consideration of simple one-dimensional isotropic-scattering and one-group problems. The present paper constitutes interesting extensions of the previous work in that in addition to a typical two-group anisotropic-scattering albedo problem in the slab geometry, the method is also applied to an isotropic-scattering problem in the x-y geometry. These results are compared with discrete S/sub N/ (ANISN or TWOTRAN-II) results, and for the problems considered here, the proposed method is found to be quite effective. Thus, the method appears to hold considerable potential for future applications. (auth)
Numerical analysis of three-dimensional MHD shock interactions in an inhomogeneous medium
International Nuclear Information System (INIS)
Prndergast, M.; Wu, S.T.
1987-01-01
Study of the formation and propagation of solar-originated shock waves in heliospheric space has attracted significant attention in the past decade. This attention is important because the propagation of shocks in heliospheric space has been thought of as one of the major physical processes for solar wind and cosmic ray modulations and their subsequent influence on the earth's environment. A version of the two step Lax-Wendroff difference method is used to seek solutions of the unsteady magnetohydrodynamic (MHD) equations for the study of a solar flare generated shock wave propagating through an inhomogeneous medium. 8 references
Coordinated Optimization of Visual Cortical Maps (II) Numerical Studies
Reichl, Lars; Heide, Dominik; Löwel, Siegrid; Crowley, Justin C.; Kaschube, Matthias; Wolf, Fred
2012-01-01
In the juvenile brain, the synaptic architecture of the visual cortex remains in a state of flux for months after the natural onset of vision and the initial emergence of feature selectivity in visual cortical neurons. It is an attractive hypothesis that visual cortical architecture is shaped during this extended period of juvenile plasticity by the coordinated optimization of multiple visual cortical maps such as orientation preference (OP), ocular dominance (OD), spatial frequency, or direction preference. In part (I) of this study we introduced a class of analytically tractable coordinated optimization models and solved representative examples, in which a spatially complex organization of the OP map is induced by interactions between the maps. We found that these solutions near symmetry breaking threshold predict a highly ordered map layout. Here we examine the time course of the convergence towards attractor states and optima of these models. In particular, we determine the timescales on which map optimization takes place and how these timescales can be compared to those of visual cortical development and plasticity. We also assess whether our models exhibit biologically more realistic, spatially irregular solutions at a finite distance from threshold, when the spatial periodicities of the two maps are detuned and when considering more than 2 feature dimensions. We show that, although maps typically undergo substantial rearrangement, no other solutions than pinwheel crystals and stripes dominate in the emerging layouts. Pinwheel crystallization takes place on a rather short timescale and can also occur for detuned wavelengths of different maps. Our numerical results thus support the view that neither minimal energy states nor intermediate transient states of our coordinated optimization models successfully explain the architecture of the visual cortex. We discuss several alternative scenarios that may improve the agreement between model solutions and biological
Numerical analysis of gas transfer by natural convection in a fluid saturated porous medium
International Nuclear Information System (INIS)
Akbal, S.; Filiz Baytas, A.
2005-01-01
The concentration distribution of a radioactive gas in a square porous cavity is investigated in this study. The decay of the radioactive gas is taken into account in the concentration equation. The governing equations are solved using alternating direction implicit method (ADI) and Finite volume method. Numerical results for velocity and concentration profiles are presented for an extensive range of parameter like Grashof number (Gr c ), Schmidt number (Sc) and the non-dimensional constant of radioactive decay. (authors)
Numerical analysis of gas transfer by natural convection in a fluid saturated porous medium
Energy Technology Data Exchange (ETDEWEB)
Akbal, S. [Cekmece Nuclear Research and Training Center (Turkey); Filiz Baytas, A. [Istanbul Technical Univ. (Turkey). Inst. for Energy
2005-07-01
The concentration distribution of a radioactive gas in a square porous cavity is investigated in this study. The decay of the radioactive gas is taken into account in the concentration equation. The governing equations are solved using alternating direction implicit method (ADI) and Finite volume method. Numerical results for velocity and concentration profiles are presented for an extensive range of parameter like Grashof number (Gr{sub c}), Schmidt number (Sc) and the non-dimensional constant of radioactive decay. (authors)
Purwanto, Agung; Narsito, Narsito
2010-01-01
An adsorbent was prepared by impregnating 2-mercaptobenzo-thiazole onto polystirene treated diatomaceous earth support. This adsorbent was then applied to adsorb mercury(II) in aqueous medium. The mercury(II) adsorption characteristics of the adsorbent was studied by the use of the original diatomaceous earth as reference. Interaction of mercury(II) and both of diatomaceous earth as well as MBT-diatomaceous were performed in a aqueous batch system to include the following parameters: (a)...
On the Analytical and Numerical Properties of the Truncated Laplace Transform II
2015-05-29
of the Truncated Laplace Transform II. Roy R. Lederman †, Vladimir Rokhlin‡, Technical Report YALEU/DCS/TR-1507 May 29, 2015 † This author’s research...41 (1962), pp. 1295–1336. [11] R. R. Lederman and V. Rokhlin, On the analytical and numerical properties of the truncated laplace transform., tech. rep...Yale CS, 2014. [12] R. R. Lederman and V. Rokhlin, On the analytical and numerical properties of the truncated laplace transform - I, In
International Nuclear Information System (INIS)
Nalegaev, S S; Petrov, N V; Bespalov, V G
2014-01-01
A numerical reconstruction of spatial distributions of optical radiation propagating through a volume of nonlinear medium at input and output planes of the medium was demonstrated using a scheme of digital holography. A nonlinear Schrodinger equation with Fourier Split-Step method was used as a tool to propagate wavefront in the volume of the medium. Time dependence of the refractive index change was not taken into account.
International Nuclear Information System (INIS)
Uddin, Md Jashim; Yusoff, N H Md; Ismail, Ahamd Izani; Anwar Bég, O
2013-01-01
A mathematical model is presented and analysed for steady two-dimensional non-isothermal boundary layer flow from a heated horizontal surface which is embedded in a porous medium saturated with a non-Newtonian power-law nanofluid. It is assumed that the wall temperature and nanoparticle volume fraction vary nonlinearly with the axial distance. By applying appropriate group transformations, the governing transport equations are reduced to a system of coupled, nonlinear ordinary differential equations with associated boundary conditions. The reduced equations are then solved numerically using the Runge–Kutta–Fehlberg fourth–fifth-order numerical method with Maple 13 software. The effects of several thermophysical parameters including rheological power-law index, non-isothermal index, Lewis number, Brownian motion parameter, thermophoresis parameter, buoyancy ratio and internal heat generation/absorption parameter on the non-dimensional velocity, temperature, nanoparticle volume fraction (concentration) and also on the friction factor, heat and mass transfer rates are investigated. A comparison of the present results with the existing published results shows excellent agreement, verifying the accuracy of the present numerical code. The study finds applications in nano biopolymeric manufacturing processes and also thermal enhancement of energy systems employing rheological working fluids. (paper)
Jashim Uddin, Md; Yusoff, N. H. Md; Bég, O. Anwar; Izani Ismail, Ahamd
2013-02-01
A mathematical model is presented and analysed for steady two-dimensional non-isothermal boundary layer flow from a heated horizontal surface which is embedded in a porous medium saturated with a non-Newtonian power-law nanofluid. It is assumed that the wall temperature and nanoparticle volume fraction vary nonlinearly with the axial distance. By applying appropriate group transformations, the governing transport equations are reduced to a system of coupled, nonlinear ordinary differential equations with associated boundary conditions. The reduced equations are then solved numerically using the Runge-Kutta-Fehlberg fourth-fifth-order numerical method with Maple 13 software. The effects of several thermophysical parameters including rheological power-law index, non-isothermal index, Lewis number, Brownian motion parameter, thermophoresis parameter, buoyancy ratio and internal heat generation/absorption parameter on the non-dimensional velocity, temperature, nanoparticle volume fraction (concentration) and also on the friction factor, heat and mass transfer rates are investigated. A comparison of the present results with the existing published results shows excellent agreement, verifying the accuracy of the present numerical code. The study finds applications in nano biopolymeric manufacturing processes and also thermal enhancement of energy systems employing rheological working fluids.
Chew, J. V. L.; Sulaiman, J.
2017-09-01
Partial differential equations that are used in describing the nonlinear heat and mass transfer phenomena are difficult to be solved. For the case where the exact solution is difficult to be obtained, it is necessary to use a numerical procedure such as the finite difference method to solve a particular partial differential equation. In term of numerical procedure, a particular method can be considered as an efficient method if the method can give an approximate solution within the specified error with the least computational complexity. Throughout this paper, the two-dimensional Porous Medium Equation (2D PME) is discretized by using the implicit finite difference scheme to construct the corresponding approximation equation. Then this approximation equation yields a large-sized and sparse nonlinear system. By using the Newton method to linearize the nonlinear system, this paper deals with the application of the Four-Point Newton-EGSOR (4NEGSOR) iterative method for solving the 2D PMEs. In addition to that, the efficiency of the 4NEGSOR iterative method is studied by solving three examples of the problems. Based on the comparative analysis, the Newton-Gauss-Seidel (NGS) and the Newton-SOR (NSOR) iterative methods are also considered. The numerical findings show that the 4NEGSOR method is superior to the NGS and the NSOR methods in terms of the number of iterations to get the converged solutions, the time of computation and the maximum absolute errors produced by the methods.
Directory of Open Access Journals (Sweden)
Agung Purwanto
2010-06-01
Full Text Available An adsorbent was prepared by impregnating 2-mercaptobenzo-thiazole onto polystirene treated diatomaceous earth support. This adsorbent was then applied to adsorb mercury(II in aqueous medium. The mercury(II adsorption characteristics of the adsorbent was studied by the use of the original diatomaceous earth as reference. Interaction of mercury(II and both of diatomaceous earth as well as MBT-diatomaceous were performed in a aqueous batch system to include the following parameters: (a medium acidity and (b mercury(II adsorption characteristic on MBT-diatomaceous with and without the present of other metal ions. In the present work quantification of mercury(II adsorption was done by determining the mercury concentration left in the solution after adsorption. A cold vapour-generation atomic absorption spectroscopy technic was used in this determination.The experiment results show, that the adsorption affinity of MBT-diatomaceous is higher than the original diatomaceous earth. The total adsorption energy of mercury(II for diatomaceous earth (24.702 kJ/mol and MBT-diatomaceous (46.942 kJ/mol suggest that the interaction is chemisorption. The mercury(II maximum adsorption on diatomaceous earth is obtained at pH 6, while similar adsorption on MBT-diatomaceous practically was not influenced by pH changes. The present of other metals, i.e. Fe(III, Co(II, Ni(II, Cu(II, Cd(II and Zn(II in solution does not give any appreciable influence to the adsorption affinity of MBT-diatomaceous to mercury(II; the total sum of the mercury(II adsorbed is constantly high, almost 100 %. Keyword: Impregnation, MBT-diatomaceous, adsorption, mercury(II
Galev, Roman; Kudryavtsev, Alexey; Trashkeev, Sergey
2017-10-01
Laser beam propagation through an integrated fiber-optical system including a miniature cavity filled with a liquid crystal (LC) is numerically simulated. Two different shapes of the cavity are considered: a transverse cylindrical hole and a gap between the parallel end faces of the optical fiber. In both cases, the director field distribution in the LC volume includes a linear singularity (disclination). The Maxwell equations for an anisotropic continuous medium are solved by the FDTD method. Nonlinear effects of beam interaction with the LC medium are ignored. The simulations provide the data on the intensity distribution and direction of the laser beam that passed through the microscopic LC volume. The portions of laser radiation lost due to scattering into the ambient medium and remaining inside the optical fiber are calculated. Based on the calculations, it may be concluded that a significant fraction of the beam energy in the case with the cavity shaped as a transverse hole is scattered owing to focusing and diffraction induced by surface curvature and the finite transverse size of the hole. Moreover, there are regions with elevated energy density in the optical fiber behind the hole, which may lead to fiber fracture under the ultimate load possible in the pulsed mode. In contrast to the system with a hole, the deflection of beam propagation from a straight line in the fiber-optical system with a gap is fairly small. It is noted that beam-LC interaction can lead to the emergence of new fiber-optical modes in the transmitted beam.
de Rosnay, Patricia; Hólm, Elias; Bonavita, Massimo; English, Steve
2017-04-01
The European Centre for Medium-Range Weather Forecasts (ECMWF) system relies on an Earth System approach focusing on atmosphere, ocean, waves, land, and sea ice. Different data assimilation methods are used for the each component of the Earth System. A hybrid 4D-Var is used for the atmosphere, a simplified sea-surface temperature (SST) and sea ice analysis is used for medium-range forecasts and for the reanalyses (ERA-Interim and ERA5). The ECMWF land and atmosphere data assimilation systems are weakly coupled, using a coupled land-atmosphere background forecast and separate analyses for the atmosphere and for the surface (soil moisture and snow). Conventional and satellite observations that inform on the state of both subsystems are assimilated. They are located at the land-atmosphere interface and include two-metre temperature and relative humidity, snow depth, and soil moisture. In this presentation we present the land-atmosphere weakly coupled assimilation currently used at ECMWF for Numerical Weather Prediction (NWP) purpose. Perspectives of coupling enhancement using Ensemble Data Assimilaton (EDA) and EDA-based cross correlation estimates with coupling at the outer loop level of the atmospheric 4D-Var are discussed.
Directory of Open Access Journals (Sweden)
P. Mazzanti
2009-11-01
Full Text Available Coastal and subaqueous landslides can be very dangerous phenomena since they are characterised by the additional risk of induced tsunamis, unlike their completely-subaerial counterparts. Numerical modelling of landslides propagation is a key step in forecasting the consequences of landslides. In this paper, a novel approach named Equivalent Fluid/Equivalent Medium (EFEM has been developed. It adapts common numerical models and software that were originally designed for subaerial landslides in order to simulate the propagation of combined subaerial-subaqueous and completely-subaqueous landslides. Drag and buoyancy forces, the loss of energy at the landslide-water impact and peculiar mechanisms like hydroplaning can be suitably simulated by this approach; furthermore, the change in properties of the landslide's mass, which is encountered at the transition from the subaerial to the submerged environment, can be taken into account. The approach has been tested by modelling two documented coastal landslides (a debris flow and a rock slide at Lake Albano using the DAN-W code. The results, which were achieved from the back-analyses, demonstrate the efficacy of the approach to simulate the propagation of different types of coastal landslides.
Spectrophotometric total protein assay with copper(II)-neocuproine reagent in alkaline medium.
Sözgen, Kevser; Cekic, Sema Demirci; Tütem, Esma; Apak, Resat
2006-02-28
Total protein assay was made using copper(II)-neocuproine (Nc) reagent in alkaline medium (with the help of a hydroxide-carbonate-tartarate solution) after 30min incubation at 40 degrees C. The absorbance of the reduction product, Cu(I)-Nc complex, was recorded at 450nm against a reagent blank. The absorptivity of the developed method for bovine serum albumin (BSA) was 0.023lmg(-1)cm(-1), greater than that of Lowry assay (0.0098), and much greater than that of Cu(II)-bicinchoninic acid (BCA) assay (0.00077). The linear range of the developed method (8-100mgl(-1) BSA) was as wide as that of Lowry, and much wider than that of BCA (200-1000mgl(-1) BSA) assay. The sensitivity of the method was greater than those of Cu-based assays (biuret, Lowry, and BCA) with a LOD of 1mgl(-1) BSA. The within-run and between-run precisions as RSD were 0.73 and 1.01%, respectively. The selectivity of the proposed method for protein was much higher than those of dye-binding and Lowry assays: Most common interferents to other protein assays such as tris, ethanolamine, deoxycholate, CsCl, citrate, and triton X-100 were tolerated at 100-fold concentrations in the analysis of 10mgl(-1) BSA, while the tolerance limits for other interferents, e.g., (NH(4))(2)SO(4) and acetylsalicylic acid (50-fold), SDS (25-fold), and glycerol (20-fold) were at acceptable levels. The redox reaction of Cu(II)-Nc as an outer-sphere electron transfer agent with the peptide bond and with four amino acid residues (cystine, cysteine, tryptophan, and tyrosine) was kinetically more favourable than that of Cu(II) alone in the biuret assay. Since the reduction product of Cu(II) with protein, i.e., Cu(I), was coordinatively saturated with Nc in the stable Cu(Nc)(2)(+) chelate, re-oxidation of the formed Cu(I) with Fenton-like reactions was not possible, thereby preventing a loss of chromophore. After conventional protein extraction, precipitation, and redissolution procedures, the protein contents of the minced meat
Subhani, M.; Nadeem, S.
2017-10-01
The present article is devoted to probe the behavior of a three-dimensional micropolar nanofluid over an exponentially stretching surface in a porous medium. The mathematical model is constructed in the form of partial differential equations using the boundary layer approach. Then by employing similarity transformations, the modelled partial differential equations are transformed to ordinary differential equations. The solution of subsequent ODEs is derived by utilizing the BVP-4C technique alongside the shooting scheme. The graphical illustrations are presented to interpret the salient features of pertinent physical parameters on the concerned profiles for different kinds of nanoparticles, namely copper, titania and alumina with water as the base fluid. For a better understanding of the fluid flow, the numerical variation in the local skin friction coefficients, Cfx and Cfy , and local Nusselt number is analyzed through tables. We can see, from the present study, that the omission of porous matrix enhances the flow of the fluid. Microrotation has a decreasing impact on the skin friction whereas it increases the rate of the heat transfer of the nanofluid.
Enayati, Hooman; Braun, Minel J.; Chandy, Abhilash J.
2018-02-01
This paper presents an investigation of flow and heat transfer in a large diameter (6.25 in) cylindrical enclosure heated laterally and containing a porous block that simulates the basket of nutrients used in a crystal growth reactor. The numerical model entails the use of a commercially available computational engine provided by ANSYS FLUENT, and based on a two-dimensional (2D) axisymmetric Reynolds-averaged Navier Stokes (RANS) equations. The porous medium is simulated using the Brinkman-extended model accounting for the Darcy and Forchheimer induced pressure drops. The porous 'plug' effects are analyzed as both its permeability/inertial resistance and locations in the reactor are changed on a parametric basis, while the Rayleigh number (Ra = gβΔTL3/να) is kept constant at 1.98 × 109. Additionally, the effect of different ratios of the hot to the cold zone lengths are investigated as a part of the current effort. For all cases, the velocity and temperature distributions in the reactor are analyzed together with the flow patterns in, and around the porous block. A comprehensive discussion is provided with regard to the effects of the position of the porous block and its permeability on both the immediately adjacent, and far flows. The consequences on the temperature distribution in the enclosure, when the ratio of the length of the hot-to-cold zones is changed, are also analyzed.
Hibi, Yoshihiko; Tomigashi, Akira
2015-09-01
Numerical simulations that couple flow in a surface fluid with that in a porous medium are useful for examining problems of pollution that involve interactions among atmosphere, water, and groundwater, including saltwater intrusion along coasts. Coupled numerical simulations of such problems must consider both vertical flow between the surface fluid and the porous medium and complicated boundary conditions at their interface. In this study, a numerical simulation method coupling Navier-Stokes equations for surface fluid flow and Darcy equations for flow in a porous medium was developed. Then, the basic ability of the coupled model to reproduce (1) the drawdown of a surface fluid observed in square-pillar experiments, using pillars filled with only fluid or with fluid and a porous medium and (2) the migration of saltwater (salt concentration 0.5%) in the porous medium using the pillar filled with fluid and a porous medium was evaluated. Simulations that assumed slippery walls reproduced well the results with drawdowns of 10-30 cm when the pillars were filled with packed sand, gas, and water. Moreover, in the simulation of saltwater infiltration by the method developed in this study, velocity was precisely reproduced because the experimental salt concentration in the porous medium after saltwater infiltration was similar to that obtained in the simulation. Furthermore, conditions across the boundary between the porous medium and the surface fluid were satisfied in these numerical simulations of square-pillar experiments in which vertical flow predominated. Similarly, the velocity obtained by the simulation for a system coupling flow in surface fluid with that in a porous medium when horizontal flow predominated satisfied the conditions across the boundary. Finally, it was confirmed that the present simulation method was able to simulate a practical-scale surface fluid and porous medium system. All of these numerical simulations, however, required a great deal of
DEFF Research Database (Denmark)
Grey, Michael James; Ladouceur, Michel; Andersen, Jacob B.
2001-01-01
1. The objective of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. 2. Fourteen healthy subjects walked on a treadmill at approximately 3.5 km h(-1) with the left ankle...... attached to a portable stretching device. The soleus stretch reflex was elicited by applying small amplitude (approximately 8 deg) dorsiflexion perturbations 200 ms after heel contact. 3. Short and medium latency responses were observed with latencies of 55 +/- 5 and 78 +/- 6 ms, respectively. The short...... the hypothesis that, during walking the medium latency component of the stretch reflex resulting from an unexpected perturbation is contributed to by group II muscle afferents....
Vadgama, Rajeshkumar N.; Odaneth, Annamma A.; Lali, Arvind M.
2015-01-01
Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B fr...
Cristante,Valtair M.; Araujo,Adriana B.; Jorge,Sônia M. A.; Florentino,Ariovaldo O.; Valente,José P. S.; Padilha,Pedro M.
2006-01-01
This work describes the synthesis and characterization of 2-aminothiazole-modified titania and its application on Hg (II) photoreduction in aqueous medium. Infrared spectroscopy confirmed the chemical modification of the titania matrix. The number of 2-aminothiazole groups attached to the titania was determined by Kjeldahl's method. The photocatalytic experiments were carried out in a cylindrical photoreactor thermostatted at 298 K. The resulting modified photocatalyst 2-aminothiazole titania...
Numerical study of the Columbia high-beta device: Torus-II
International Nuclear Information System (INIS)
Izzo, R.
1981-01-01
The ionization, heating and subsequent long-time-scale behavior of the helium plasma in the Columbia fusion device, Torus-II, is studied. The purpose of this work is to perform numerical simulations while maintaining a high level of interaction with experimentalists. The device is operated as a toroidal z-pinch to prepare the gas for heating. This ionization of helium is studied using a zero-dimensional, two-fluid code. It is essentially an energy balance calculation that follows the development of the various charge states of the helium and any impurities (primarily silicon and oxygen) that are present. The code is an atomic physics model of Torus-II. In addition to ionization, we include three-body and radiative recombination processes
Numerical study of the Columbia high-beta device: Torus-II
Energy Technology Data Exchange (ETDEWEB)
Izzo, R.
1981-01-01
The ionization, heating and subsequent long-time-scale behavior of the helium plasma in the Columbia fusion device, Torus-II, is studied. The purpose of this work is to perform numerical simulations while maintaining a high level of interaction with experimentalists. The device is operated as a toroidal z-pinch to prepare the gas for heating. This ionization of helium is studied using a zero-dimensional, two-fluid code. It is essentially an energy balance calculation that follows the development of the various charge states of the helium and any impurities (primarily silicon and oxygen) that are present. The code is an atomic physics model of Torus-II. In addition to ionization, we include three-body and radiative recombination processes.
HYDRA-II: A hydrothermal analysis computer code: Volume 1, Equations and numerics
International Nuclear Information System (INIS)
McCann, R.A.
1987-04-01
HYDRA-II is a hydrothermal computer code capable of three-dimensional analysis of coupled conduction, convection, and thermal radiation problems. This code is especially appropriate for simulating the steady-state performance of spent fuel storage systems. The code has been evaluated for this application for the US Department of Energy's Commercial Spent Fuel Management Program. HYDRA-II provides a finite difference solution in Cartesian coordinates to the equations governing the conservation of mass, momentum, and energy. A cylindrical coordinate system may also be used to enclose the Cartesian coordinate system. This exterior coordinate system is useful for modeling cylindrical cask bodies. The difference equations for conservation of momentum are enhanced by the incorporation of directional porosities and permeabilities that aid in modeling solid structures whose dimensions may be smaller than the computational mesh. The equation for conservation of energy permits of modeling of orthotropic physical properties and film resistances. Several automated procedures are available to model radiation transfer within enclosures and from fuel rod to fuel rod. The documentation of HYDRA-II is presented in three separate volumes. This volume, Volume I - Equations and Numerics, describes the basic differential equations, illustrates how the difference equations are formulated, and gives the solution procedures employed. Volume II - User's Manual contains code flow charts, discusses the code structure, provides detailed instructions for preparing an input file, and illustrates the operation of the code by means of a model problem. The final volume, Volume III - Verification/Validation Assessments, presents results of numerical simulations of single- and multiassembly storage systems and comparisons with experimental data. 4 refs
Automated Extraction of Crop Area Statistics from Medium-Resolution Imagery, Phase II
National Aeronautics and Space Administration — This project is focusing on the strategic, routine incorporation of medium-resolution satellite imagery into operational agricultural assessments for the global crop...
Directory of Open Access Journals (Sweden)
A. Guerdouh
2016-05-01
Full Text Available The solvent extraction of copper(II and chromium(III from nitrate medium with salicylideneaniline (HL is studied as a function of various parameters: pH, concentration of salicylideneaniline, contact time and the nature of anoin (nitrate and sulfate in aqueous phase. Chromium(III is not extracted by salicylideneaniline diluted in 1-octanol. Copper(II is only extracted by salicylideneaniline and it was found that the highest extractability achieved to 95% at pH 4.9, The stoichiometry of the extracted species was determined by using the method of slope analysis. Elemental analysis, UV–vis and IR-spectra were used to confirm the structure. It is found that the copper (II is extracted as CuL2.2H2O Their equilibrium constant, distribution coefficient, percentage extraction (%E and free energy are also calculated.
Recombination efficiency of molecular hydrogen on interstellar grains - II: A numerical study
International Nuclear Information System (INIS)
Chakrabarti, S.K.; Ankan, Das; Kinsuk, Acharyya; Sonali, Chakrabarti
2006-05-01
Knowledge of the recombination time on the grain surfaces has been a major obstacle in deciding the production rate of molecular hydrogen and other molecules in the interstellar medium. We present a numerical study to compute this time for molecular hydrogen for various cloud and grain parameters. We also find the time dependence, particularly when a grain is freshly injected into the system. Apart from the fact that the recombination times seem to be functions of the grain parameters such as the activation barrier energy, temperature etc., our result also shows the dependence on the number of sites in the grain S and the effective accretion rate per site a s of atomic hydrogen. To put simply the average time that a pair of atomic hydrogens will take to produce one molecular hydrogen depends on how heavily the grain is already populated by atomic and molecular hydrogens and how fast the hopping and desorption times are. We show that if we write the average recombination time as T r ∼ S α /A H , where, A H is the hopping rate, then α could be much greater than 1 for all astrophysically relevant accretion rates. Thus the average formation rate of H 2 is also dependent on the grain parameters, temperature and the accretion rate. We believe that our results will affect the overall rate of the formation of complex molecules such as methanol which requires successive hydrogenation on the grain surfaces in the interstellar medium. (author)
International Nuclear Information System (INIS)
Shar, G.A.; Soomro, G.A.
2004-01-01
Spectrophotometric determination of cobalt(II), nickel(II) and copper(II) is carried out with 1-(2 pyridylazo)-2-naphthol as a complexing reagent in aqueous phase using non-ionic surfactant Tween 80. Beer's law is obeyed for Co(II), Ni(II) and Cu(II) over the range 0.5 - 4.0, 0.5 - 4.0 and 0.5 - 3.0 ngmL/sup -1/ with detection limit (2 σ) of 6.7, 3.2 and 3.9 ngmL/sup -1/. The max molar absorption, molar absorptivity, Sandell's sensitivity of Co(II), Ni(II) and Cu(II) are 580 nm, 570 nm and 555 nm; max (104 mol/sup -1/ cm /sup -1/) is 0.87, 1.8 and 1.6 and 6.8, 3.3 and 3.9 ng cm-2 respectively. The pH at which complex is formed for Co(II), Ni(II) and Cu(II) is 5, 5.5 and 6.5 respectively. The critical micelle concentration (CMC) of Tween 80 is 5%. The present method is compared with that of atomic absorption spectroscopy and no significant difference is noted between the two methods at 95% confidence level. The method has been applied to the determination of Co(II), Ni(II) and Cu(II) in industrial waste water and pharmaceutical samples. (author)
International Nuclear Information System (INIS)
Cheng, L.; Kuznetsov, A.V.
2005-01-01
This paper presents the first attempt to investigate numerically heat transfer in a helical pipe filled with a fluid saturated porous medium; the analysis is based on the full momentum equation for porous media that accounts for the Brinkman and Forchheimer extensions of the Darcy law as well as for the flow inertia. Numerical computations are performed in an orthogonal helical coordinate system. The effects of the Darcy number, the Forchheimer coefficient as well as the Dean and Germano numbers on the axial flow velocity, secondary flow, temperature distribution, and the Nusselt number are investigated. (authors)
Energy Technology Data Exchange (ETDEWEB)
Cheng, L.; Kuznetsov, A.V. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering
2005-07-01
This paper presents the first attempt to investigate numerically heat transfer in a helical pipe filled with a fluid saturated porous medium; the analysis is based on the full momentum equation for porous media that accounts for the Brinkman and Forchheimer extensions of the Darcy law as well as for the flow inertia. Numerical computations are performed in an orthogonal helical coordinate system. The effects of the Darcy number, the Forchheimer coefficient as well as the Dean and Germano numbers on the axial flow velocity, secondary flow, temperature distribution, and the Nusselt number are investigated. (authors)
CSIR Research Space (South Africa)
Mamuru, SA
2010-11-01
Full Text Available Oxygen reduction reaction (ORR) in alkaline medium at iron (II) tetrakis (diaquaplatinum) octacarboxyphthalocyanine (PtFeOCPc) catalyst supported on multi-walled carbon nanotubes (MWCNTs) has been described. The ORR followed the direct 4-electron...
International Nuclear Information System (INIS)
Ceballos, M.A.; Car, E.J.; Prato, T.A.; Prato, C.A.; Alvarez, L.M.; Godoy, A.R.
1995-01-01
Determination of the dynamic properties of the reactor building of Atucha II NPP is carried out in order to: i) Obtain valuable information for seismic qualification of the plant, and ii) Assess some procedures for testing and analysis that are used in the process of seismic evaluation of existing nuclear facilities founded on Quaternary soil deposits. Both steady state and impulsive dynamic tests were performed but attention is centered here in tile techniques used to determine natural frequencies and modal damping ratios with impulsive tests. Numerical analyses were performed by means of a 3-D model model of the superstructure together with foundation stiffness coefficients derived in a separate paper from steady state vibration tests, and also from analysis with a 2-D F.E. model of the soil layers capable of approximating the 3-D features of the problem. The computed foundation stiffness coefficients are compared both with those obtained from the tests and from an axisymmetric F.E. model; results indicate that foundation stiffness coefficients calculated with F.E. models with soil parameters given by laboratory tests performed on cored samples are significantly lower than those given by the steady state vibration tests. (author)
Azadirachta indica leaf powder as a biosorbent for Ni(II) in aqueous medium
Energy Technology Data Exchange (ETDEWEB)
Bhattacharyya, Krishna G., E-mail: krishna2604@sify.com [Department of Chemistry, Gauhati University, Guwahati 781014, Assam (India); Sarma, Jyotirekha [Department of Chemistry, Gauhati University, Guwahati 781014, Assam (India); Sarma, Arunima [Department of Chemistry, Morigaon College, Morigaon 782105, Assam (India)
2009-06-15
Azadirachta indica leaves are converted to a fine powder for use as a biosorbent for the removal of metal ions in aqueous solution. In this work, the adsorptive interactions between Ni(II) and the powder were studied under a variety of conditions involving variations in pH, Ni(II) concentration, biosorbent amount, interaction time and temperature, all in single batch processes. The experimental data have been interpreted on the basis of existing mathematical models of equilibrium kinetics and thermodynamics. The biosorption of Ni(II) increased in the pH range of 2.0-5.0 with {approx}92.6% adsorption at pH 5.0 for the highest amount of the biosorbent (4 g/L). The biosorption followed second-order kinetics and intra-particle diffusion was likely to have significant influence in controlling the process. The Langmuir monolayer adsorption capacity varied from 2.4 to 9.1 mg/g and the equilibrium coefficient from 1.09 to 2.78 L/g with strong indication that the Ni(II) ions were held on the biosorbent surface by formation of an adsorption complex. The thermodynamic parameters showed the process to be exothermic in nature supported by appropriate ranges of values of enthalpy change, entropy change and Gibbs energy change.
Directory of Open Access Journals (Sweden)
H. Niranjan
2016-01-01
Full Text Available We investigate the effects of slip and radiation on magnetoconvection flow of a chemically reacting fluid near a stagnation-point towards a vertical plate embedded in a porous medium analytically and numerically. The governing partial differential equations are diminished into the coupled ordinary differential equations by similarity transformations. Then they are solved analytically by homotopy analysis method and solved numerically by shooting method with RK fourth-order method. In this study, the analytical and numerical results are compared for many combinations of parameters. The rates of heat and mass transfer are calculated. The velocity profile near the plate overshoots on increasing the slip parameter. The concentration and temperature are decreasing on increasing the slip parameter.
A NUMERICAL SIMULATION OF COSMIC RAY MODULATION NEAR THE HELIOPAUSE. II. SOME PHYSICAL INSIGHTS
International Nuclear Information System (INIS)
Luo, Xi; Feng, Xueshang; Potgieter, Marius S.; Du Toit Strauss, R.; Zhang, Ming; Pogorelov, Nikolai V.
2016-01-01
Cosmic ray (CR) transport near the heliopause (HP) is studied using a hybrid transport model, with the parameters constrained by observations from the Voyager 1 spacecraft. We simulate the CR radial flux along different directions in the heliosphere. There is no well-defined thin layer between the solar wind region and the interstellar region along the tail and polar directions of the heliosphere. By analyzing the radial flux curve along the direction of Voyager 2 , together with its trajectory information, the crossing time of the HP by Voyager 2 is predicted to be in 2017.14. We simulate the CR radial flux for different energy values along the direction of Voyager 1 . We find that there is only a modest modulation region of about 10 au wide beyond the HP, so that Voyager 1 observing the Local Interstellar Spectra is justified in numerical modeling. We analyze the heliospheric exit information of pseudo-particles in our stochastic numerical (time-backward) method, conjecturing that they represent the behavior of CR particles, and we find that pseudo-particles that have been traced from the nose region exit in the tail region. This implies that many CR particles diffuse directly from the heliospheric tail region to the nose region near the HP. In addition, when pseudo-particles were traced from the Local Interstellar Medium (LISM), it is found that their exit location (entrance for real particles) from the simulation domain is along the prescribed Interstellar Magnetic Field direction. This indicates that parallel diffusion dominates CR particle transport in the LISM.
Studying the Interstellar Medium of H II/BCD Galaxies Using IFU Spectroscopy
Directory of Open Access Journals (Sweden)
Patricio Lagos
2013-01-01
Full Text Available We review the results from our studies, and previous published work, on the spatially resolved physical properties of a sample of H ii/BCD galaxies, as obtained mainly from integral-field unit spectroscopy with Gemini/GMOS and VLT/VIMOS. We confirm that, within observational uncertainties, our sample galaxies show nearly spatially constant chemical abundances similar to other low-mass starburst galaxies. They also show He ii λ4686 emission with the properties being suggestive of a mix of excitation sources and with Wolf-Rayet stars being excluded as the primary ones. Finally, in this contribution, we include a list of all H ii/BCD galaxies studied thus far with integral-field unit spectroscopy.
International Nuclear Information System (INIS)
Krishna Murty, N.; Satyanarayana, V.; Rukmini, N.
1978-01-01
The reaction between iron(II) and cerium(IV) sulphate in phosphoric acid medium (6-12M) is studied potentiometrically and visually using methylene blue, thionine, azure A, azure B, azure C, toluidine blue, new methylene blue, variamine blue, ferroin, p-ethoxychrysoidine, N-phenylanthranilic acid and barium diphenylamine sulphonate as indicators. This reaction is made use for the analysis of binary mixtures of Fe(II)-Sn(II), Fe(II)-Ti(III), Fe(II)-U(IV), Fe(II)-Mo(V), Fe(II)-Fe(III) with Ce(IV) sulphate and Ce(IV)-U(VI), Ce(IV)-Mo(VI), Ce(IV)-V(V) and Ce(IV)-Cu(II) with iron (II). (author)
Yang, Kun; Wu, Yanqing; Huang, Fenglei; Li, Ming
2017-09-05
An effective computational model is required to accurately predict the dynamic responses in accidental initiations of explosives. The present work uses a series of two-dimensional mechanical-chemical simulations performed via a hydrodynamic-code, DREXH-2D, to efficiently describe the mechanical and ignition-deflagration responses of cased cylindrical polymer-bonded explosives (PBXs) undergoing a low-to-medium-level impact (70-350m/s) in longitudinal direction. The ignition response was predicted based on an ignition criterion of effective plastic work. Slow burning and its growth to deflagration were described through a pressure-dependent reaction rate equation. The extreme value of effective plastic work was found to be useful to determine the ignition threshold velocity for PBXs. For low-level velocity impact, the incident stress wave reflection from lateral surfaces contributed to the formation of ignition regions. After the ignition, the deflagration was induced in the medium-level impact, and its violence was related to the shock strength. However, the low-strength stress wave only induced reaction at local regions, and sequent burning was no longer sensitive to the strength of incident wave. The predicted pressure and temperature results of PBXs were consistent with the medium-level impact tests performed by China Academy of Engineering Physics. Copyright © 2017 Elsevier B.V. All rights reserved.
Application of the numerical density-enthalpy method to the multi-phase flow through a porous medium
Ibrahim, D.; Vermolen, F.J.; Vuik, C.
2010-01-01
In this paper we apply a new method to solve multi-phase fluid flow problem for 1D1D and 2D2D fluid systems. This method is developed at TNO and presented in [1] for spatially homogeneous systems. We call this method the numerical density-enthalpy method (or ??-hh method) because density-enthalpy
A thermoelectric power generating heat exchanger: Part II – Numerical modeling and optimization
International Nuclear Information System (INIS)
Sarhadi, Ali; Bjørk, Rasmus; Lindeburg, Niels; Viereck, Peter; Pryds, Nini
2016-01-01
Highlights: • A comprehensive model was developed to optimize the integrated TEG-heat exchanger. • The developed model was validated with the experimental data. • The effect of using different interface materials on the output power was assessed. • The influence of TEG arrangement on the power production was investigated. • Optimized geometrical parameters and proper interface materials were suggested. - Abstract: In Part I of this study, the performance of an experimental integrated thermoelectric generator (TEG)-heat exchanger was presented. In the current study, Part II, the obtained experimental results are compared with those predicted by a finite element (FE) model. In the simulation of the integrated TEG-heat exchanger, the thermal contact resistance between the TEG and the heat exchanger is modeled assuming either an ideal thermal contact or using a combined Cooper–Mikic–Yovanovich (CMY) and parallel plate gap formulation, which takes into account the contact pressure, roughness and hardness of the interface surfaces as well as the air gap thermal resistance at the interface. The combined CMY and parallel plate gap model is then further developed to simulate the thermal contact resistance for the case of an interface material. The numerical results show good agreement with the experimental data with an average deviation of 17% for the case without interface material and 12% in the case of including additional material at the interfaces. The model is then employed to evaluate the power production of the integrated system using different interface materials, including graphite, aluminum (Al), tin (Sn) and lead (Pb) in a form of thin foils. The numerical results show that lead foil at the interface has the best performance, with an improvement in power production of 34% compared to graphite foil. Finally, the model predicts that for a certain flow rate, increasing the parallel TEG channels for the integrated systems with 4, 8, and 12 TEGs
Simple-II: A new numerical thermal model for predicting thermal performance of Stirling engines
International Nuclear Information System (INIS)
Babaelahi, Mojtaba; Sayyaadi, Hoseyn
2014-01-01
A new thermal model called Simple-II was presented based on modification of the original Simple analysis. First, the engine was modeled considering adiabatic expansion and compression spaces, in which effect of gas leakage from cylinder to buffer space and shuttle effect of displacer were implemented in the basic differential equations. Moreover, non-ideal thermal operation of the regenerator and the longitudinal heat conduction between heater and cooler through the regenerator wall were considered. Based on the magnitudes of pressure drops in heat exchangers, values of pressure in the expansion and compression spaces were corrected. Furthermore, based on the theory of finite speed thermodynamics (FST), the corresponding power loss due to the piston motion and also the mechanical friction were considered. Simple-II was employed for thermal simulation of a prototype Stirling engine. Finally, result of the new model was evaluated by comprehensive comparison of experimental results with those of the previous models. The output power and thermal efficiency were predicted with +20.7% and +7.1% errors, respectively. Also, the regenerator was demonstrated to be the main source of power and heat losses; nevertheless, other loss mechanisms have reasonable effects on output power and/or thermal efficiency of Stirling engines. - Highlights: • A new thermal model was presented based on various loss mechanisms. • Shuttle effect and mass leakage were integrated into differential equations. • FST, mechanical friction and longitudinal conduction losses were considered. • A methodology was presented for numerical solution and correcting results based on losses. • The new model predicted thermal performance of engine with higher accuracy
Directory of Open Access Journals (Sweden)
Mohammad Yaghoub Abdollahzadeh Jamalabadi
2016-04-01
Full Text Available Numerical study of the slip effects and radiative heat transfer on a steady state fully developed Williamson flow of an incompressible Newtonian fluid; between parallel vertical walls of a microchannel with isothermal walls in a porous medium is performed. The slip effects are considered at both boundary conditions. Radiative highly absorbing medium is modeled by the Rosseland approximation. The non-dimensional governing Navier–Stokes and energy coupled partial differential equations formed a boundary problem are solved numerically using the fourth order Runge–Kutta algorithm by means of a shooting method. Numerical outcomes for the skin friction coefficient, the rate of heat transfer represented by the local Nusselt number were presented even as the velocity and temperature profiles illustrated graphically and analyzed. The effects of the temperature number, Grashof number, thermal radiation parameter, Reynolds number, velocity slip length, Darcy number, and temperature jump, on the flow field and temperature field and their effects on the boundaries are presented and discussed.
International Nuclear Information System (INIS)
Caresana, F.; Bilancia, M.; Bartolini, C.M.
2011-01-01
Significant reductions in vehicle fuel consumption can be obtained through a greater control of the thermal status of the engine, especially under partial load conditions. Different systems have been proposed to implement this concept, referred to as improved engine thermal management. The amount of fuel saved depends on the components and layout of the engine cooling plant and on the performance of its control system. In this work, a method was developed to calculate the theoretical minimum fuel consumption of a passenger car and used as a reference in comparing different engine cooling system concepts. A high-medium class car was taken as an example and simulated on standard cycles. Models for power train and cooling system components were developed and linked to simulate the vehicle. A preliminary analysis of the engine was performed using AVL's Boost program. The fuel consumption of the complete vehicle, equipped with a conventional cooling plant, was determined on standard cycles and compared with that of a vehicle equipped with a 'perfect' cooling system, to calculate the theoretical reduction in fuel consumption. - Highlights: → We propose a method for assessing the potential of smart engine thermal management. → A conventional cooling system is compared to a 'perfect' one to estimate fuel economy. → We tested the method in an upper-medium segment passenger car.
Numerical solution of multiband k.p model for tunnelling in type-II heterostructures
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A.E. Botha
2010-01-01
Full Text Available A new and very general method was developed for calculating the charge and spin-resolved electron tunnelling in type-II heterojunctions. Starting from a multiband k.p description of the bulk energy-band structure, a multiband k.p Riccati equation was derived. The reflection and transmission coefficients were obtained for each channel by integrating the Riccati equation over the entire heterostructure. Numerical instability was reduced through this method, in which the multichannel log-derivative of the envelope function matrix, rather than the envelope function itself, was propagated. As an example, a six-band k.p Hamiltonian was used to calculate the current-voltage characteristics of a 10-nm wide InAs/ GaSb/InAs single quantum well device which exhibited negative differential resistance at room temperature. The calculated current as a function of applied (bias voltage was found to be in semiquantitative agreement with the experiment, a result which indicated that inelastic transport mechanisms do not contribute significantly to the valley currents measured in this particular device.
Hami, K.; Zeroual, I.
2017-12-01
In the present research, simulations have been conducted to determine numerically the dynamic behaviour of the flow of underground water fed by a river. The basic equations governing the problem studied are those of Navier-Stokes equations of conservation of momentum (flows between pores), coupled by the Darcy-Forchheimer equations (flows within these pores). To understand the phenomena involved, we first study the impact of flow rate on the pressure and the filtration velocity in the underground medium, the second part is devoted to the calculation of the elevation effect of the river water on the flow behaviour in the saturated and unsaturated zone of the aquifer.
Yajnik, C S; Sardesai, B S; Bhat, D S; Naik, S S; Raut, K N; Shelgikar, K M; Orskov, H; Alberti, K G; Hockaday, T D
1997-01-01
A majority of patients with fibrocalculous pancreatic diabetes (FCPD) do not become ketotic even in adverse conditions. It is not clear whether this ketosis resistance is due to reduced fatty acid release from adipose tissue or to impaired hepatic ketogenesis. We tested hepatic ketogenesis in FCPD patients using a ketogenic challenge of oral medium-chain triglycerides (MCTs) and compared it with that in matched insulin-dependent diabetes mellitus (IDDM) patients and healthy controls. After oral MCTs, FCPD patients showed only a mild increase in blood 3-hydroxybutyrate (3-HB) concentrations (median: fasting, 0.13 mmol/L; peak, 0.52) compared with IDDM patients (fasting, 0.44; peak, 3.39) and controls (fasting, 0.04; peak, 0.75). Plasma nonesterified fatty acid (NEFA) concentrations were comparable in the two diabetic groups (FCPD: fasting, 0.50 mmol/L; peak, 0.79; IDDM: fasting, 0.91; peak, 1.04). Plasma C-peptide concentrations were low and comparable in the two diabetic groups. Plasma glucagon concentrations were higher in IDDM patients in the fasting state, but declined to levels comparable to those in FCPD patients after oral MCTs. Plasma carnitine concentrations were comparable in the two groups of patients. It is concluded that the failure to stimulate ketogenesis under these conditions could be partly due to inhibition of a step beyond fatty acid entry into the mitochondria.
Energy Technology Data Exchange (ETDEWEB)
Churchill, Christopher W.; Trujillo-Gomez, Sebastian; Nielsen, Nikole M. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia)
2013-12-10
In Churchill et al., we used halo abundance matching applied to 182 galaxies in the Mg II Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean Mg II λ2796 equivalent width follows a tight inverse-square power law, W{sub r} (2796)∝(D/R {sub vir}){sup –2}, with projected location relative to the galaxy virial radius and that the Mg II absorption covering fraction is effectively invariant with galaxy virial mass, M {sub h}, over the range 10.7 ≤ log M {sub h}/M {sub ☉} ≤ 13.9. In this work, we explore multivariate relationships between W{sub r} (2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T = 10{sup 4}-10{sup 4.5} K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the Mg II absorbing gas such that the mean W{sub r} (2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D ≅ 0.3 R {sub vir}, independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3 < D/R {sub vir} ≤ 1, the mean W{sub r} (2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W{sub r} (2796) and virial mass. We discuss how simulations and theory constrained by observations support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.
Azadirachta indica (Neem) leaf powder as a biosorbent for removal of Cd(II) from aqueous medium
Energy Technology Data Exchange (ETDEWEB)
Sharma, Arunima [Department of chemistry, Gauhati University, Guwahati 781014, Assam (India); Bhattacharyya, Krishna G. [Department of chemistry, Gauhati University, Guwahati 781014, Assam (India)]. E-mail: krishna2604@sify.com
2005-10-17
A biosorbent, Neem leaf powder (NLP), was prepared from the mature leaves of the Azadirachta indica (Neem) tree by initial cleaning, drying, grinding, washing to remove pigments and redrying. The powder was characterized with respect to specific surface area (21.45 m{sup 2} g{sup -1}), surface topography and surface functional groups and the material was used as an adsorbent in a batch process to remove Cd(II) from aqueous medium under conditions of different concentrations, NLP loadings, pH, agitation time and temperature. Adsorption increased from 8.8% at pH 4.0 to 70.0% at pH 7.0 and 93.6% at pH 9.5, the higher values in alkaline medium being due to removal by precipitation. The adsorption was very fast initially and maximum adsorption was observed within 300 min of agitation. The kinetics of the interactions was tested with pseudo first order Lagergren equation (mean k {sub 1} = 1.2 x 10{sup -2} min{sup -1}), simple second order kinetics (mean k {sub 2} = 1.34 x 10{sup -3} g mg{sup -1} min{sup -1}), Elovich equation, liquid film diffusion model (mean k = 1.39 x 10{sup -2} min{sup -1}) and intra-particle diffusion mechanism. The adsorption data gave good fits with Langmuir and Freundlich isotherms and yielded Langmuir monolayer capacity of 158 mg g{sup -1} for the NLP and Freundlich adsorption capacity of 18.7 L g{sup -1}. A 2.0 g of NLP could remove 86% of Cd(II) at 293 K from a solution containing 158.8 mg Cd(II) per litre. The mean values of the thermodynamic parameters, {delta}H, {delta}S and {delta}G, at 293 K were -73.7 kJ mol{sup -1}, -0.24 J mol{sup -1} K{sup -1} and -3.63 kJ mol{sup -1}, respectively, showing the adsorption process to be thermodynamically favourable. The results have established good potentiality for the Neem leaf powder to be used as a biosorbent for Cd(II)
Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M
2015-12-01
Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.
Directory of Open Access Journals (Sweden)
Rajeshkumar N. Vadgama
2015-12-01
Full Text Available Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15 in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.
Directory of Open Access Journals (Sweden)
Parama Ghoshal
2017-12-01
Full Text Available Reactive convection in a porous medium has received recent interest in the context of the geological storage of carbon dioxide in saline formations. We study theoretically and numerically the gravitational instability of a diffusive boundary layer in the presence of a first-order precipitation reaction. We compare the predictions from normal mode, linear stability analysis, and nonlinear numerical simulations, and discuss the relative deviations. The application of our findings to the storage of carbon dioxide in a siliciclastic aquifer shows that while the reactive-diffusive layer can become unstable within a timescale of 1 to 1.5 months after the injection of carbon dioxide, it can take almost 10 months for sufficiently vigorous convection to produce a considerable increase in the dissolution flux of carbon dioxide.
Kumar, Vikash; Rani, Abha; Singh, Ajay Kumar
2017-12-01
The problem of conjugate free convection from a vertical fin embedded in a fluid-saturated porous medium is investigated. The governing nonlinear equations are solved iteratively by a highly implicit finite difference scheme. In this paper, the results based on four models, viz the Darcy model, the Brinkman model, the non-Darcian model with nonlinear inertia and viscous terms, and also the non-Darcian model with viscous, nonlinear inertia and velocity square terms, are compared. It is seen that fin cooling is more effective at higher Grashof or Darcy numbers due to stronger convection effects. The local Nusselt number is observed to increase with the Grashof or Darcy numbers and decrease slightly with the conduction-convection parameter. The limitation of the Darcy's law is observed at higher values of permeability when the non-Darcian models are more relevant.
Vernengo, Giuliano; Bruzzone, Dario
2016-03-01
The hydrodynamic analysis of a new semi-small waterplane area twin hull (SWATH) suitable for various applications such as small and medium size passenger ferries is presented. This may be an attractive crossover configuration resulting from the merging of two classical shapes: a conventional SWATH and a fast catamaran. The final hull design exhibits a wedge-like waterline shape with the maximum beam at the stern; the hull ends with a very narrow entrance angle, has a prominent bulbous bow typical of SWATH vessels, and features full stern to arrange waterjet propellers. Our analysis aims to perform a preliminary assessment of the hydrodynamic performance of a hull with such a complex shape both in terms of resistance of the hull in calm water and seakeeping capability in regular head waves and compare the performance with that of a conventional SWATH. The analysis is performed using a boundary element method that was preliminarily validated on a conventional SWATH vessel.
Das, Saurish; Patel, H. V.; Milacic, E.; Deen, N. G.; Kuipers, J. A. M.
2018-01-01
We investigate the dynamics of a liquid droplet in contact with a surface of a porous structure by means of the pore-scale level, fully resolved numerical simulations. The geometrical details of the solid porous matrix are resolved by a sharp interface immersed boundary method on a Cartesian computational grid, whereas the motion of the gas-liquid interface is tracked by a mass conservative volume of fluid method. The numerical simulations are performed considering a model porous structure that is approximated by a 3D cubical scaffold with cylindrical struts. The effect of the porosity and the equilibrium contact angle (between the gas-liquid interface and the solid struts) on the spreading behavior, liquid imbibition, and apparent contact angle (between the gas-liquid interface and the porous base) are studied. We also perform several simulations for droplet spreading on a flat surface as a reference case. Gas-liquid systems of the Laplace number, La = 45 and La = 144 × 103 are considered neglecting the effect of gravity. We report the time exponent (n) and pre-factor (C) of the power law describing the evolution of the spreading diameter (S = Ctn) for different equilibrium contact angles and porosity. Our simulations reveal that the apparent or macroscopic contact angle varies linearly with the equilibrium contact angle and increases with porosity. Not necessarily for all the wetting porous structures, a continuous capillary drainage occurs, and we find that the rate of the capillary drainage very much depends on the fluid inertia. At La = 144 × 103, numerically we capture the capillary wave induced pinch-off and daughter droplet ejection. We observe that on the porous structure the pinch-off is weak compared to that on a flat plate.
Directory of Open Access Journals (Sweden)
Habib-Olah Sayehvand
Full Text Available Numerical investigation the problem of nanofluid heat and mass transfer in a channel partially filled with a porous medium in the presence of uniform magnetic field is carried out by a new computational iterative approach known as the spectral local linearization method (SLLM. The similarity solution is used to reduce the governing system of partial differential equations to a set of nonlinear ordinary differential equations which are then solved by SLLM and validity of our solutions is verified by the numerical results (fourth-order Runge-Kutta scheme with the shooting method. In modeling the flow in the channel, the effects of flow inertia, Brinkman friction, nanoparticles concentration and thickness of the porous region are taken into account. The results are obtained for velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number. Also, effects of active parameters such as viscosity parameter, Hartmann number, Darcy number, Prandtl number, Schmidt number, Eckert number, Brownian motion parameter, thermophoresis parameter and the thickness of porous region on the hydrodynamics, heat and mass transfer behaviors are investigated. Keywords: Brownian, Nanofluid, Porous medium, Spectral local linearization method, Thermophoresis
Energy Technology Data Exchange (ETDEWEB)
Luquet, David; Marchiano, Régis; Coulouvrat, François, E-mail: francois.coulouvrat@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 7190, Institut Jean Le Rond d’Alembert, F-75005, Paris (France)
2015-10-28
Many situations involve the propagation of acoustical shock waves through flows. Natural sources such as lightning, volcano explosions, or meteoroid atmospheric entries, emit loud, low frequency, and impulsive sound that is influenced by atmospheric wind and turbulence. The sonic boom produced by a supersonic aircraft and explosion noises are examples of intense anthropogenic sources in the atmosphere. The Buzz-Saw-Noise produced by turbo-engine fan blades rotating at supersonic speed also propagates in a fast flow within the engine nacelle. Simulating these situations is challenging, given the 3D nature of the problem, the long range propagation distances relative to the central wavelength, the strongly nonlinear behavior of shocks associated to a wide-band spectrum, and finally the key role of the flow motion. With this in view, the so-called FLHOWARD (acronym for FLow and Heterogeneous One-Way Approximation for Resolution of Diffraction) method is presented with three-dimensional applications. A scalar nonlinear wave equation is established in the framework of atmospheric applications, assuming weak heterogeneities and a slow wind. It takes into account diffraction, absorption and relaxation properties of the atmosphere, quadratic nonlinearities including weak shock waves, heterogeneities of the medium in sound speed and density, and presence of a flow (assuming a mean stratified wind and 3D turbulent ? flow fluctuations of smaller amplitude). This equation is solved in the framework of the one-way method. A split-step technique allows the splitting of the non-linear wave equation into simpler equations, each corresponding to a physical effect. Each sub-equation is solved using an analytical method if possible, and finite-differences otherwise. Nonlinear effects are solved in the time domain, and others in the frequency domain. Homogeneous diffraction is handled by means of the angular spectrum method. Ground is assumed perfectly flat and rigid. Due to the 3D
Luquet, David; Marchiano, Régis; Coulouvrat, François
2015-10-01
Many situations involve the propagation of acoustical shock waves through flows. Natural sources such as lightning, volcano explosions, or meteoroid atmospheric entries, emit loud, low frequency, and impulsive sound that is influenced by atmospheric wind and turbulence. The sonic boom produced by a supersonic aircraft and explosion noises are examples of intense anthropogenic sources in the atmosphere. The Buzz-Saw-Noise produced by turbo-engine fan blades rotating at supersonic speed also propagates in a fast flow within the engine nacelle. Simulating these situations is challenging, given the 3D nature of the problem, the long range propagation distances relative to the central wavelength, the strongly nonlinear behavior of shocks associated to a wide-band spectrum, and finally the key role of the flow motion. With this in view, the so-called FLHOWARD (acronym for FLow and Heterogeneous One-Way Approximation for Resolution of Diffraction) method is presented with three-dimensional applications. A scalar nonlinear wave equation is established in the framework of atmospheric applications, assuming weak heterogeneities and a slow wind. It takes into account diffraction, absorption and relaxation properties of the atmosphere, quadratic nonlinearities including weak shock waves, heterogeneities of the medium in sound speed and density, and presence of a flow (assuming a mean stratified wind and 3D turbulent ? flow fluctuations of smaller amplitude). This equation is solved in the framework of the one-way method. A split-step technique allows the splitting of the non-linear wave equation into simpler equations, each corresponding to a physical effect. Each sub-equation is solved using an analytical method if possible, and finite-differences otherwise. Nonlinear effects are solved in the time domain, and others in the frequency domain. Homogeneous diffraction is handled by means of the angular spectrum method. Ground is assumed perfectly flat and rigid. Due to the 3D
International Nuclear Information System (INIS)
Luquet, David; Marchiano, Régis; Coulouvrat, François
2015-01-01
Many situations involve the propagation of acoustical shock waves through flows. Natural sources such as lightning, volcano explosions, or meteoroid atmospheric entries, emit loud, low frequency, and impulsive sound that is influenced by atmospheric wind and turbulence. The sonic boom produced by a supersonic aircraft and explosion noises are examples of intense anthropogenic sources in the atmosphere. The Buzz-Saw-Noise produced by turbo-engine fan blades rotating at supersonic speed also propagates in a fast flow within the engine nacelle. Simulating these situations is challenging, given the 3D nature of the problem, the long range propagation distances relative to the central wavelength, the strongly nonlinear behavior of shocks associated to a wide-band spectrum, and finally the key role of the flow motion. With this in view, the so-called FLHOWARD (acronym for FLow and Heterogeneous One-Way Approximation for Resolution of Diffraction) method is presented with three-dimensional applications. A scalar nonlinear wave equation is established in the framework of atmospheric applications, assuming weak heterogeneities and a slow wind. It takes into account diffraction, absorption and relaxation properties of the atmosphere, quadratic nonlinearities including weak shock waves, heterogeneities of the medium in sound speed and density, and presence of a flow (assuming a mean stratified wind and 3D turbulent ? flow fluctuations of smaller amplitude). This equation is solved in the framework of the one-way method. A split-step technique allows the splitting of the non-linear wave equation into simpler equations, each corresponding to a physical effect. Each sub-equation is solved using an analytical method if possible, and finite-differences otherwise. Nonlinear effects are solved in the time domain, and others in the frequency domain. Homogeneous diffraction is handled by means of the angular spectrum method. Ground is assumed perfectly flat and rigid. Due to the 3D
Directory of Open Access Journals (Sweden)
R.S. Tripathy
2016-09-01
The governing equations of the flow have been transformed into ordinary differential equations by using similarity transformation technique and solved using the Runge-Kutta method associated with shooting technique. The numerical solutions are achieved showing the effects of pertinent parameters. For verification of the present findings the results of this study have been compared with the earlier works in particular cases; Darcian and non-Darcian fluids are discussed separately. It is worth reporting that effect of porosity of the medium combined with inertia gives rise to a transverse compression producing thinner boundary layer the solution by finite element method (FEM and Runge–Kutta method, do agree within a reasonable error limit.
Rodriguez, Ernesto; Kim, Yunjin; Durden, Stephen L.
1992-01-01
A numerical evaluation is presented of the regime of validity for various rough surface scattering theories against numerical results obtained by employing the method of moments. The contribution of each theory is considered up to second order in the perturbation expansion for the surface current. Considering both vertical and horizontal polarizations, the unified perturbation method provides best results among all theories weighed.
Sayehvand, Habib-Olah; Basiri Parsa, Amir
Numerical investigation the problem of nanofluid heat and mass transfer in a channel partially filled with a porous medium in the presence of uniform magnetic field is carried out by a new computational iterative approach known as the spectral local linearization method (SLLM). The similarity solution is used to reduce the governing system of partial differential equations to a set of nonlinear ordinary differential equations which are then solved by SLLM and validity of our solutions is verified by the numerical results (fourth-order Runge-Kutta scheme with the shooting method). In modeling the flow in the channel, the effects of flow inertia, Brinkman friction, nanoparticles concentration and thickness of the porous region are taken into account. The results are obtained for velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number. Also, effects of active parameters such as viscosity parameter, Hartmann number, Darcy number, Prandtl number, Schmidt number, Eckert number, Brownian motion parameter, thermophoresis parameter and the thickness of porous region on the hydrodynamics, heat and mass transfer behaviors are investigated.
International Nuclear Information System (INIS)
Draoui, Abdeslam
1989-01-01
The works we present here are on numerical approaches of heat transfer coupling radiation-conduction and radiation-convection within semi-transparent two-dimensional medium. The first part deals with a review of equations of radiative transfer and introduces three numerical methods (Pl, P3, Hottel's zones) which enable one to solve this problem in a two-dimensional environment. After comparing the three methods in the case where radiation is the only mode of transfer, we introduce in the second chapter a study of the coupling of radiation with conduction. So, a fourth method is used to solve this problem. These comparisons lead us to various methods which enable us to show the interest of the spherical harmonics approximations. In the third part, the Pl approximation is kept because it is simple to use, moreover it enables us to introduce both the coupling of radiative transfers with laminar convective equations in a thermally driven two-dimensional cavity. The results show a significant influence of the radiative participation of the fluid on heat and dynamic transfer we met in this type of problem. (author) [fr
International Nuclear Information System (INIS)
Inoue, Tsuyoshi; Inutsuka, Shu-ichiro
2009-01-01
Formation of interstellar clouds as a consequence of thermal instability is studied using two-dimensional two-fluid magnetohydrodynamic simulations. We consider the situation of converging, supersonic flows of warm neutral medium in the interstellar medium that generate a shocked slab of thermally unstable gas in which clouds form. We find, as speculated in Paper I, that in the shocked slab magnetic pressure dominates thermal pressure and the thermal instability grows in the isochorically cooling, thermally unstable slab that leads to the formation of H I clouds whose number density is typically n ∼ -3 , even if the angle between magnetic field and converging flows is small. We also find that even if there is a large dispersion of magnetic field, evolution of the shocked slab is essentially determined by the angle between the mean magnetic field and converging flows. Thus, the direct formation of molecular clouds by piling up warm neutral medium does not seem to be a typical molecular cloud formation process, unless the direction of supersonic converging flows is biased to the orientation of mean magnetic field by some mechanism. However, when the angle is small, the H I shell generated as a result of converging flows is massive and possibly evolves into molecular clouds, provided gas in the massive H I shell is piled up again along the magnetic field line. We expect that another subsequent shock wave can again pile up the gas of the massive shell and produce a larger cloud. We thus emphasize the importance of multiple episodes of converging flows, as a typical formation process of molecular clouds.
Fujioka, Yoshitsugu; Kadono, Keitaro; Fujie, Yasuko; Metsugi, Yukiko; Ogawara, Ken-ichi; Higaki, Kazutaka; Kimura, Toshikiro
2007-06-04
The in-vivo absorbability of drugs categorized into the biopharmaceutics classification system (BCS) class II is very difficult to be predicted because of the large variability in the absorption and/or dissolution kinetics and the lack of an adequate in-vitro system for evaluating the dissolution behavior. We tried to predict the in-vivo absorption kinetics of griseofulvin, categorized into BCS class II, orally administrated as powders into rats, based on Gastrointestinal-Transit-Absorption model (GITA model), consisting of the absorption, dissolution and GI-transit processes. Using the dissolution rate constants (k(dis)) of griseofulvin obtained with JP 1st solution, JP 2nd solution, FaSSIF, FeSSIF and modified SIBLM as a medium, simulation lines were not able to describe the observed mean plasma profile at all. On the other hand, a calculated line provided by employing k(dis) obtained with MREVID 2 (medium reflecting in-vivo dissolution 2), a new medium, was in better agreement with the observed mean plasma profile than existing media, indicating that the utilization of adequate k(dis) value made it possible to predict the in-vivo absorption kinetics of drugs classified into BCS class II based on GITA model and that MREVID 2 could be a useful medium for describing the in-vivo dissolution kinetics.
Examination of Numerical Integration Accuracy and Modeling for GRACE-FO and GRACE-II
McCullough, C.; Bettadpur, S.
2012-12-01
As technological advances throughout the field of satellite geodesy improve the accuracy of satellite measurements, numerical methods and algorithms must be able to keep pace. Currently, the Gravity Recovery and Climate Experiment's (GRACE) dual one-way microwave ranging system can determine changes in inter-satellite range to a precision of a few microns; however, with the advent of laser measurement systems nanometer precision ranging is a realistic possibility. With this increase in measurement accuracy, a reevaluation of the accuracy inherent in the linear multi-step numerical integration methods is necessary. Two areas where this can be a primary concern are the ability of the numerical integration methods to accurately predict the satellite's state in the presence of numerous small accelerations due to operation of the spacecraft attitude control thrusters, and due to small, point-mass anomalies on the surface of the Earth. This study attempts to quantify and minimize these numerical errors in an effort to improve the accuracy of modeling and propagation of these perturbations; helping to provide further insight into the behavior and evolution of the Earth's gravity field from the more capable gravity missions in the future.
Goldsmith, Paul F.; Pineda, Jorge L.; Neufeld, David A.; Wolfire, Mark G.; Risacher, Christophe; Simon, Robert
2018-04-01
We have combined emission from the 158 μm fine structure transition of C+ observed with the GREAT and upGREAT instruments on SOFIA with 21 cm absorption spectra and visual extinction to characterize the diffuse interstellar clouds found along the lines of sight. The weak [C II] emission is consistent in velocity and line width with the strongest H I component produced by the cold neutral medium. The H I column density and kinetic temperature are known from the 21 cm data and, assuming a fractional abundance of ionized carbon, we calculate the volume density and thermal pressure of each source, which vary considerably, with 27 {cm}}-3≤slant n({{{H}}}0) ≤slant 210 cm‑3 considering only the atomic hydrogen along the lines of sight to be responsible for the C+, while 13 {cm}}-3≤slant n({{{H}}}0+{{{H}}}2)≤slant 190 cm‑3 including the hydrogen in both forms. The thermal pressure varies widely with 1970 cm‑3 K ≤slant {P}th}/k≤slant 10,440 cm‑3 K for H0 alone and 750 cm‑3 K ≤ P th/k ≤ 9360 cm‑3 K including both H0 and H2. The molecular hydrogen fraction varies between 0.10 and 0.67. Photoelectric heating is the dominant heating source, supplemented by a moderately enhanced cosmic ray ionization rate, constrained by the relatively low 45 K to 73 K gas temperatures of the clouds. The resulting thermal balance for the two lower-density clouds is satisfactory, but for the two higher-density clouds, the combined heating rate is insufficient to balance the observed C+ cooling.
International Nuclear Information System (INIS)
Kirby, Evan N.; Cohen, Judith G.; Guhathakurta, Puragra; Rockosi, Constance M.; Simon, Joshua D.; Geha, Marla C.; Sneden, Christopher; Sohn, Sangmo Tony; Majewski, Steven R.; Siegel, Michael
2010-01-01
We present a catalog of Fe, Mg, Si, Ca, and Ti abundances for 2961 stars in eight dwarf satellite galaxies of the Milky Way (MW): Sculptor, Fornax, Leo I, Sextans, Leo II, Canes Venatici I, Ursa Minor, and Draco. For the purposes of validating our measurements, we also observed 445 red giants in MW globular clusters and 21 field red giants in the MW halo. The measurements are based on Keck/DEIMOS medium-resolution spectroscopy (MRS) combined with spectral synthesis. We estimate uncertainties in [Fe/H] by quantifying the dispersion of [Fe/H] measurements in a sample of stars in monometallic globular clusters (GCs). We estimate uncertainties in Mg, Si, Ca, and Ti abundances by comparing to high-resolution spectroscopic abundances of the same stars. For this purpose, a sample of 132 stars with published high-resolution spectroscopy in GCs, the MW halo field, and dwarf galaxies has been observed with MRS. The standard deviations of the differences in [Fe/H] and ([α/Fe]) (the average of [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]) between the two samples is 0.15 and 0.16, respectively. This catalog represents the largest sample of multi-element abundances in dwarf galaxies to date. The next papers in this series draw conclusions on the chemical evolution, gas dynamics, and star formation histories from the catalog presented here. The wide range of dwarf galaxy luminosity reveals the dependence of dwarf galaxy chemical evolution on galaxy stellar mass.
A quasi-stationary numerical model of atomized metal droplets, II: Prediction and assessment
DEFF Research Database (Denmark)
Pryds, Nini H.; Hattel, Jesper Henri; Thorborg, Jesper
1999-01-01
A new model which extends previous studies and includes the interaction between enveloping gas and an array of droplets has been developed and presented in a previous paper. The model incorporates the probability density function of atomized metallic droplets into the heat transfer equations....... The main thrust of the model is that the gas temperature was not predetermined and calculated empirically but calculated numerically based on heat balance consideration. In this paper, the accuracy of the numerical model and the applicability of the model as a predictive tool have been investigated...... been illustrated.A comparison between the numerical model and the experimental results shows an excellent agreement and demonstrates the validity of the present model, e.g. the calculated gas temperature which has an important influence on the droplet solidification behaviour as well as the calculated...
Equilibrium gas flow computations. II. An analysis of numerical formulations of conservation laws
International Nuclear Information System (INIS)
Vinokur, M.; Liu, Y.
1988-01-01
Modern numerical techniques employing properties of flux Jacobian matrices are extended to general, equilibrium gas laws. Generalizations of the Beam-Warming scheme, Steger-Warming and van Leer flux-vector splittings, and Roe's approximate Riemann solver are presented for three-dimensional, time-varying grids. The approximations inherent in previous generalizations are discussed. 20 references
Equilibrium gas flow computations. II - An analysis of numerical formulations of conservation laws
Vinokur, Marcel; Liu, Yen
1988-01-01
Modern numerical techniques employing properties of flux Jacobian matrices are extended to general, equilibrium gas laws. Generalizations of the Beam-Warming scheme, Steger-Warming and van Leer flux-vector splittings, and Roe's approximate Riemann solver are presented for three-dimensional, time-varying grids. The approximations inherent in previous generalizations are discussed.
Duque, Earl P. N.; Johnson, Wayne; vanDam, C. P.; Chao, David D.; Cortes, Regina; Yee, Karen
1999-01-01
Accurate, reliable and robust numerical predictions of wind turbine rotor power remain a challenge to the wind energy industry. The literature reports various methods that compare predictions to experiments. The methods vary from Blade Element Momentum Theory (BEM), Vortex Lattice (VL), to variants of Reynolds-averaged Navier-Stokes (RaNS). The BEM and VL methods consistently show discrepancies in predicting rotor power at higher wind speeds mainly due to inadequacies with inboard stall and stall delay models. The RaNS methodologies show promise in predicting blade stall. However, inaccurate rotor vortex wake convection, boundary layer turbulence modeling and grid resolution has limited their accuracy. In addition, the inherently unsteady stalled flow conditions become computationally expensive for even the best endowed research labs. Although numerical power predictions have been compared to experiment. The availability of good wind turbine data sufficient for code validation experimental data that has been extracted from the IEA Annex XIV download site for the NREL Combined Experiment phase II and phase IV rotor. In addition, the comparisons will show data that has been further reduced into steady wind and zero yaw conditions suitable for comparisons to "steady wind" rotor power predictions. In summary, the paper will present and discuss the capabilities and limitations of the three numerical methods and make available a database of experimental data suitable to help other numerical methods practitioners validate their own work.
International Nuclear Information System (INIS)
Anne Susan Georgena, S.; Anjali Devi, S.P.
2011-01-01
Flow induced by stretching surfaces is often encountered in many industrial disciplines. The applications include extrusion process, wire and fiber coating, polymer processing, foodstuff processing, design of various heat exchangers, and chemical processing equipment, among other applications. Stretching will bring in a unidirectional orientation to the extrudate, consequently the quality of the final product considerably depends on the flow and heat transfer mechanism. The analysis of momentum and thermal transports within the fluid on a stretching surface is important for Boundary Value Problem gaining some fundamental understanding of such processes. In view of these applications, the present work deals with such kind of problem. The effect of radiation on the hydromagnetic (MHD) flow and heat transfer over an unsteady stretching surface with variable viscosity embedded in a porous medium is analyzed. Similarity transformations are used to convert the governing time dependent boundary layer equations for momentum and thermal energy into a set of ordinary differential equations containing magnetic interaction parameter M, unsteadiness parameter A, variable viscosity parameter β, permeability parameter λ, radiation parameter R and Prandtl number Pr. The resulting Nonlinear Ordinary Differential Equations are solved numerically by applying numerical shooting technique together with fourth order Runge-Kutta method. The influence of all the parameters involved in the problem over the velocity and temperature are analyzed and illustrated through graphs. Details the velocity and temperature fields as well as the local skin friction and the local Nusselt number for various values of the parameters of the problem are presented. The influence of the magnetic interaction parameter over the velocity and temperature distribution is more pronounced. There is a significant difference in velocity and temperature due to the increase in variable viscosity parameter and the
International Nuclear Information System (INIS)
Luo, Quantian; Tong, Liyong
2013-01-01
This part presents finite element analysis to verify the present formulations on mechanics of the pressurized cellular structures derived in Part I and experimental testing for a pressurized cellular actuator to demonstrate feasibility and realization of the proposed pressurized cellular structures. Linear and nonlinear finite element analyses are implemented in a commercial finite element analysis package and the numerical results are compared with those of the novel formulations given in Part I. A pressurized cellular structure specimen with 3 cells is fabricated and tested. The fabricated 3-cell cellular structure is capable of yielding a free actuation strain of around 24%. The measured pressure-induced displacement and blocking force compare favorably with the numerical results predicted by the finite element analysis and analytical formulations. (paper)
Numerical linked-cluster algorithms. II. t-J models on the square lattice.
Rigol, Marcos; Bryant, Tyler; Singh, Rajiv R P
2007-06-01
We discuss the application of a recently introduced numerical linked-cluster (NLC) algorithm to strongly correlated itinerant models. In particular, we present a study of thermodynamic observables: chemical potential, entropy, specific heat, and uniform susceptibility for the t-J model on the square lattice, with Jt=0.5 and 0.3. Our NLC results are compared with those obtained from high-temperature expansions (HTE) and the finite-temperature Lanczos method (FTLM). We show that there is a sizeable window in temperature where NLC results converge without extrapolations whereas HTE diverges. Upon extrapolations, the overall agreement between NLC, HTE, and FTLM is excellent in some cases down to 0.25t . At intermediate temperatures NLC results are better controlled than other methods, making it easier to judge the convergence and numerical accuracy of the method.
Energy Technology Data Exchange (ETDEWEB)
Doumic, M
2005-05-15
To simulate the propagation of a monochromatic laser beam in a medium, we use the paraxial approximation of the Klein-Gordon (in the time-varying problem) and of the Maxwell (in the non time-depending case) equations. In a first part, we make an asymptotic analysis of the Klein-Gordon equation. We obtain approximated problems, either of Schroedinger or of transport-Schroedinger type. We prove the existence and uniqueness of a solution for these problems, and estimate the difference between it and the exact solution of the Klein-Gordon equation. In a second part, we study the boundary problem for the advection Schroedinger equation, and show what the boundary condition must be so that the problem on our domain should be the restriction of the problem in the whole space: such a condition is called a transparent or an absorbing boundary condition. In a third part, we use the preceding results to build a numerical resolution method, for which we prove stability and show some simulations. (author)
Energy Technology Data Exchange (ETDEWEB)
Wilbois, B.
2003-07-01
In this work, a new model is built which allows to take into consideration the overall mass transfer phenomena (in particular convection) taking place inside a mixture of n{sub c} constituents in a porous medium. This model should allow to foresee the quantitative composition of fluids in oil fields and also to improve the knowledge of the flow of different species inside mixtures. The overall physical phenomena taking place at oil fields is explained in the first chapter. Chapter 2 recalls some thermodynamical notions at the equilibrium and outside equilibrium. These notions, necessary to understand the forecasting methods used by petroleum geologists, are described in chapter 3. This chapter includes also a bibliographic study about the methods of simulation of mass and heat transfers in porous media. In chapter 4, using the thermodynamical relations of irreversible processes described in chapter 2, a new type of macroscopic model allowing to describe the overall phenomena analyzed is developed. The numerical method used to solve this new system of equations is precised. Finally, chapter 5 proposes a set of cases for the validation of the uncoupled phenomena and some qualitative examples of modeling of coupled phenomena. (J.S.)
Schumann, U.
2015-12-01
The Contrail Cirrus Prediction model CoCiP (doi:10.5194/gmd-5-543-2012) has been applied quasi operationally to predict contrails for flight planning of ML-CIRRUS (C. Voigt, DLR, et al.) in Europe and for ACCESS II in California (B. Anderson, NASA, et al.) in March-May 2014. The model uses NWP data from ECMWF and past airtraffic data (actual traffic data are used for analysis). The forecasts provided a sequence of hourly forecast maps of contrail cirrus optical depth for 3.5 days, every 12 h. CoCiP has been compared to observations before, e.g. within a global climate-aerosol-contrail model (Schumann, Penner et al., ACPD, 2015, doi:10.5194/acpd-15-19553-2015). Good predictions would allow for climate optimal routing (see, e.g., US patent by Mannstein and Schumann, US 2012/0173147 A1). The predictions are tested by: 1) Local eyewitness reports and photos, 2) satellite observed cloudiness, 3) autocorrelation analysis of predictions for various forecast periods, 4) comparisons of computed with observed optical depth from COCS (doi:10.5194/amt-7-3233-2014, 2014) by IR METEOSAT-SEVIRI observations over Europe. The results demonstrate medium-range predictability of contrail cirrus to a useful degree for given traffic, soot emissions, and high-quality NWP data. A growing set of satellite, Lidar, and in-situ data from ML-CIRRUS and ACCENT are becoming available and will be used to further test the forecast quality. The autocorrelation of optical depth predictions is near 70% for 3-d forecasts for Europe (outside times with high Sahara dust loads), and only slightly smaller for continental USA. Contrail cirrus is abundant over Europe and USA. More than 1/3 of all cirrus measured with the research aircraft HALO during ML-CIRRUS was impacted by contrails. The radiative forcing (RF) is strongly daytime and ambience dependent. The net annual mean RF, based on our global studies, may reach up to 0.08 W/m2 globally, and may well exceed 1 W/m2 regionally, with maximum over Europe
International Nuclear Information System (INIS)
Islam, M.F.; Begum, D.A.; Rahman, M.; Rahman, M.S.
2009-01-01
In the study of the extractive separation of Al(III) and Ni(II) by di-2-ethylhexyl phosphoric acid D2EHPA-kerosene from aqueous fluoride medium, about 94% Al(III) and 2% Ni(II) were extracted with 0.3 M D2EHPA (pH 2.1 and temperature 30+-1 degree C). Extraction of Ni(II) decreased with increasing extractant concentration. D2EHPA-kerosene-fluoride system showed better extraction of Al(III) with higher extractant concentration and aqueous pH and vice versa for the extraction of Ni(II). The maximum separation factor (beta 1380) was obtained for Al(III) at 20 degree C and decreased to (beta 732) at 60 degree C. The separation of Al(III) from Ni(II) was favoured at normal temperature. Extraction followed the order Al(III), Ni(II). About 99% stripping of Al(III) was attained from the loaded 0.20 M D2EHPA. Much faster extraction of Al(III) compared to Ni(II) and preferential loading were shown by D2EHPA-kerosene in the presence of fluoride ion in the aqueous phase. Separation of Al(III) was the most outstanding from Ni-Al-F-complex solution. (author)
Quasi-direct numerical simulation of a pebble bed configuration, Part-II: Temperature field analysis
International Nuclear Information System (INIS)
Shams, A.; Roelofs, F.; Komen, E.M.J.; Baglietto, E.
2013-01-01
Highlights: ► Quasi direct numerical simulations (q-DNSs) of a pebble bed configuration have been performed. ► This q-DNS database may serve as a reference for the validation of different turbulence modeling approaches. ► A wide range of qualitative and quantitative data throughout the computational domain has been generated. ► Results for mean, RMS of temperature and respective turbulent heat fluxes are extensively reported in this paper. -- Abstract: Good prediction of the flow and heat transfer phenomena in the pebble bed core of a high temperature reactor (HTR) is a challenge for available turbulence models, which still require to be validated. While experimental data are generally desirable in this validation process, due to the complex geometric configuration and measurement difficulties, a very limited amount of data is currently available. On the other hand, direct numerical simulation (DNS) is considered an accurate simulation technique, which may serve as an alternative for validating turbulence models. In the framework of the present study, quasi-direct numerical simulation (q-DNS) of a single face cubic centered pebble bed is performed, which will serve as a reference for the validation of different turbulence modeling approaches in order to perform calculations for a randomly arranged pebble bed. These simulations were performed at a Reynolds number of 3088, based on pebble diameter, with a porosity level of 0.42. Results related to flow field (mean, RMS and covariance of velocity) have been presented in Part-I, whereas, in the present article, we focus our attention to the analysis of the temperature field. A wide range of qualitative and quantitative data for the thermal field (mean, RMS and turbulent heat flux) has been generated
DEFF Research Database (Denmark)
Achtziger, Wolfgang; Stolpe, Mathias
2009-01-01
on the implementation details but also establish finite convergence of the branch-and-bound method. The algorithm is based on solving a sequence of continuous non-convex relaxations which can be formulated as quadratic programs according to the theory in Part I. The quadratic programs to be treated within the branch......-and-bound search all have the same feasible set and differ from each other only in the objective function. This is one reason for making the resulting branch-and-bound method very efficient. The paper closes with several large-scale numerical examples. These examples are, to the knowledge of the authors, by far...
Marquis, J. W.; Campbell, J. R.; Oyola, M. I.; Ruston, B. C.; Zhang, J.
2017-12-01
This is part II of a two-part series examining the impacts of aerosol particles on weather forecasts. In this study, the aerosol indirect effects on weather forecasts are explored by examining the temperature and moisture analysis associated with assimilating dust contaminated hyperspectral infrared radiances. The dust induced temperature and moisture biases are quantified for different aerosol vertical distribution and loading scenarios. The overall impacts of dust contamination on temperature and moisture forecasts are quantified over the west coast of Africa, with the assistance of aerosol retrievals from AERONET, MPL, and CALIOP. At last, methods for improving hyperspectral infrared data assimilation in dust contaminated regions are proposed.
Energy Technology Data Exchange (ETDEWEB)
Yu, Jeong Il; Park, Hee Chul; Choi, Doo Ho [Dept. of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); and others
2016-03-15
A prospective phase II trial was conducted to evaluate the effectiveness and toxicity of regional hyperthermia and whole liver irradiation (WLI) for numerous chemorefractory liver metastases from colorectal cancer. Enrolled patients had numerous chemorefractory hepatic metastases from colorectal cancer. Five sessions of hyperthermia and seven fractions of 3-gray WLI were planned. Health-related quality of life (HRQoL) was determined using the Korean version of the European Organization for Research and Treatment of Cancer quality of life questionnaire C-30 and the Functional Assessment of Cancer Therapy-Hepatobiliary version 4.0. Objective and pain response was evaluated. A total of 12 patients consented to the study and the 10 who received WLI and hyperthermia were analyzed. WLI was completed as planned in nine patients and hyperthermia in eight. Pain response was partial in four patients and stable in four. Partial objective response was achieved in three patients (30.0%) and stable disease was seen in four patients at the 1-month follow-up. One patient died 1 month after treatment because of respiratory failure related to pleural metastasis progression. Other grade III or higher toxicities were detected in three patients; however, all severe toxicities were related to disease progression rather than treatment. No significant difference in HRQoL was noted at the time of assessment for patients who were available for questionnaires. Combined WLI and hyperthermia were well tolerated without severe treatment-related toxicity with a promising response from numerous chemorefractory hepatic metastases from colorectal cancer.
Study of a phase change energy storage using spherical capsules. Part II: Numerical modelling
Energy Technology Data Exchange (ETDEWEB)
Bedecarrats, J.P.; Castaing-Lasvignottes, J.; Strub, F.; Dumas, J.P. [Laboratoire de Thermique, Energetique et Procedes, Universite de Pau et des Pays de l' Adour, Avenue de l' Universite, BP 1155, 64013 Pau cedex (France)
2009-10-15
The objective of this work is the numerical study of an industrial process of energy storage which consists in the use of a cylindrical tank filled with encapsulated phase change materials (PCM). A particularity is present in this kind of processes; it concerns the delay of the crystallization of the PCM, called supercooling phenomenon. The development of the model for cold storage with heat transfer fluid flowing enables a detailed analysis of this process. The effects of different parameters on the behaviour of the tank, such as the inlet temperature, the flow rate, are examined when the tank is in vertical position. There is substantial agreement between the prediction and the experimental values already presented in part I. (author)
A thermoelectric power generating heat exchanger: Part II – Numerical modeling and optimization
DEFF Research Database (Denmark)
Sarhadi, Ali; Bjørk, Rasmus; Lindeburg, N.
2016-01-01
TEG-heat exchanger, the thermal contact resistance between the TEG and the heat exchanger is modeled assuming either an ideal thermal contact or using a combined Cooper–Mikic–Yovanovich (CMY) and parallel plate gap formulation, which takes into account the contact pressure, roughness and hardness...... with an average deviation of 17% for the case without interface material and 12% in the case of including additional material at the interfaces. The model is then employed to evaluate the power production of the integrated system using different interface materials, including graphite, aluminum (Al), tin (Sn......) and lead (Pb) in a form of thin foils. The numerical results show that lead foil at the interface has the best performance, with an improvement in power production of 34% compared to graphite foil. Finally, the model predicts that for a certain flow rate, increasing the parallel TEG channels...
EVOLVE : a Bridge between Probability, Set Oriented Numerics, and Evolutionary Computation II
Coello, Carlos; Tantar, Alexandru-Adrian; Tantar, Emilia; Bouvry, Pascal; Moral, Pierre; Legrand, Pierrick; EVOLVE 2012
2013-01-01
This book comprises a selection of papers from the EVOLVE 2012 held in Mexico City, Mexico. The aim of the EVOLVE is to build a bridge between probability, set oriented numerics and evolutionary computing, as to identify new common and challenging research aspects. The conference is also intended to foster a growing interest for robust and efficient methods with a sound theoretical background. EVOLVE is intended to unify theory-inspired methods and cutting-edge techniques ensuring performance guarantee factors. By gathering researchers with different backgrounds, a unified view and vocabulary can emerge where the theoretical advancements may echo in different domains. Summarizing, the EVOLVE focuses on challenging aspects arising at the passage from theory to new paradigms and aims to provide a unified view while raising questions related to reliability, performance guarantees and modeling. The papers of the EVOLVE 2012 make a contribution to this goal.
Evolution of planetesimals. I - Dynamics: Relaxation in a thin disk. II - Numerical simulations
Palmer, P. L.; Lin, D. N. C.; Aarseth, S. J.
1993-01-01
The study examines the effects of density inhomogeneity and differential rotation as well as inelastic collisions on the dynamical evolution of planetesimals. Consideration is given to a three-step analysis: the dynamical evolution of the planetesimals, collisions and mass accumulation, and interaction with gas. It is shown that the velocity dispersion of a cold system of planetesimals increases rapidly due to elastic gravitational scattering. When the dispersion in the epicycle amplitude becomes comparable to the planetesimals' Roche radius, energy is transferred from the systematic Keplerian shear to the dispersive motion. With a numerical N-body scheme, gravitational scattering and physical collisions among a system of planetesimals is simulated. It is shown that dynamical equilibrium is attained with a velocity dispersion comparable to the surface escape velocity of those planetesimals which contribute most of the system mass.
Thamsen, Bente; Blümel, Bastian; Schaller, Jens; Paschereit, Christian O; Affeld, Klaus; Goubergrits, Leonid; Kertzscher, Ulrich
2015-08-01
Implantable left ventricular assist devices (LVADs) became the therapy of choice in treating end-stage heart failure. Although survival improved substantially and is similar in currently clinically implanted LVADs HeartMate II (HM II) and HeartWare HVAD, complications related to blood trauma are frequently observed. The aim of this study was to compare these two pumps regarding their potential blood trauma employing computational fluid dynamics. High-resolution structured grids were generated for the pumps. Newtonian flow was calculated, solving Reynolds-averaged Navier-Stokes equations with a sliding mesh approach and a k-ω shear stress transport turbulence model for the operating point of 4.5 L/min and 80 mm Hg. The pumps were compared in terms of volumes subjected to certain viscous shear stress thresholds, below which no trauma was assumed (von Willebrand factor cleavage: 9 Pa, platelet activation: 50 Pa, and hemolysis: 150 Pa), and associated residence times. Additionally, a hemolysis index was calculated based on a Eulerian transport approach. Twenty-two percent of larger volumes above 9 Pa were observed in the HVAD; above 50 Pa and 150 Pa the differences between the two pumps were marginal. Residence times were higher in the HVAD for all thresholds. The hemolysis index was almost equal for the HM II and HVAD. Besides the gap regions in both pumps, the inlet regions of the rotor and diffuser blades have a high hemolysis production in the HM II, whereas in the HVAD, the volute tongue is an additional site for hemolysis production. Thus, in this study, the comparison of the HM II and the HVAD using numerical methods indicated an overall similar tendency to blood trauma in both pumps. However, influences of turbulent shear stresses were not considered and effects of the pivot bearing in the HM II were not taken into account. Further in vitro investigations are required. Copyright © 2015 International Center for Artificial Organs and Transplantation and
Ab initio theory of superconductivity in a magnetic field. II. Numerical solution
Linscheid, A.; Sanna, A.; Gross, E. K. U.
2015-07-01
We numerically investigate the spin density functional theory for superconductors (SpinSCDFT) and the approximated exchange-correlation functional, derived and presented in the preceding Paper I [A. Linscheid et al., Phys. Rev. B 92, 024505 (2015), 10.1103/PhysRevB.92.024505]. As a test system, we employ a free-electron gas featuring an exchange splitting, a phononic pairing field, and a Coulomb repulsion. SpinSCDFT results are compared with Sarma, the Bardeen-Cooper-Schrieffer theory, and with an Eliashberg type of approach. We find that the spectrum of the superconducting Kohn-Sham SpinSCDFT system is not in agreement with the true quasiparticle structure. Therefore, starting from the Dyson equation, we derive a scheme that allows to compute the many-body excitations of the superconductor and represents the extension to superconductivity of the G0W0 method in band-structure theory. This superconducting G0W0 method vastly improves the predicted spectra.
Adaptive Core Simulation Employing Discrete Inverse Theory - Part II: Numerical Experiments
International Nuclear Information System (INIS)
Abdel-Khalik, Hany S.; Turinsky, Paul J.
2005-01-01
Use of adaptive simulation is intended to improve the fidelity and robustness of important core attribute predictions such as core power distribution, thermal margins, and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e., in-core instrumentation readings, to adapt the simulation in a meaningful way. The companion paper, ''Adaptive Core Simulation Employing Discrete Inverse Theory - Part I: Theory,'' describes in detail the theoretical background of the proposed adaptive techniques. This paper, Part II, demonstrates several computational experiments conducted to assess the fidelity and robustness of the proposed techniques. The intent is to check the ability of the adapted core simulator model to predict future core observables that are not included in the adaption or core observables that are recorded at core conditions that differ from those at which adaption is completed. Also, this paper demonstrates successful utilization of an efficient sensitivity analysis approach to calculate the sensitivity information required to perform the adaption for millions of input core parameters. Finally, this paper illustrates a useful application for adaptive simulation - reducing the inconsistencies between two different core simulator code systems, where the multitudes of input data to one code are adjusted to enhance the agreement between both codes for important core attributes, i.e., core reactivity and power distribution. Also demonstrated is the robustness of such an application
International Nuclear Information System (INIS)
Krishna Murty, N.; Satyanarayana, V.
1977-01-01
U(VI) and Mo(VI) in 11.5-12.5M, Cr(VI) in 8.5 10.3M and V(V) and V(IV) in 10.5 12.0M phosphoric acid medium can be estimated with Fe(II) visually using azure A, azure B, azure C, toluidine blue and new methylene blue. (author)
Numerical models of protoneutron stars and type-II supernovae - recent developments
Energy Technology Data Exchange (ETDEWEB)
Janka, H.T. [Max-Planck-Institut fuer Astrophysik, Garching (Germany)
1996-11-01
The results of recent multi-dimensional simulations of type-II supernovae are reviewed. They show that convective instabilities in the collapsed stellar core might play an important role already during the first second after the formation of the supernovae shock. Convectively unstable situations occur below and near the neutrinosphere as well as in the neutrino-heated region between the nascent neutron star and the supernova shock after the latter has stalled at a radiums of typically 100-200 km. While convective overturn in the layer of neutrino energy deposition clearly helps the explosion to develop and potentially provides an explanation of strong mantle and envelope mixing, asphericities, and non-uniform {sup 56}Ni distribution observed in supernova SN 1987A, its presence and importance depends on the strength of the neutrino heating and thus on the size of the neutrino fluxes from the neutrino star. Convection in the hot-bubble region can only be developed if the growth timescale of the instabilities and the heating timescale are both shorter than the accretion timescale of the matter advected through the stagnant shock. For too small neutrino luminosities this requirement is not fulfilled and convective activity cannot develop, leading to very weak explosions or even fizzling models, just as in the one-dimensional situations. Convectively enhanced neutrino luminosities from the protoneutron star can therefore provide an essential condition for the explosion of the star. Very recent two-dimensional, self-consistent, general relativistic simulations of the cooling of a newly-formed neutron star demonstrate and confirm the possibility that Ledoux convection, driven by negative lepton number and entropy gradients, may encompass the whole protoneutron star within less than one second and can lead to an increase of the neutrino fluxes by up to a factor of two. (author) 9 figs., refs.
DEFF Research Database (Denmark)
Pedersen, Henrik B.; Josephsen, Jens; Kerszman, Gustaw
1985-01-01
-Tris) buffer and HEPES buffer. The phosphate abolishes the antiphage activity of the platinum complexes probably by some sort of complex formation. This together with dimerization reactions qualitatively explains the tailing off of the phage inactivation rate. High concentrations of NaNO3 as the salt medium...
Bridge Busters: The 397th Bombardment Group (Medium) and the B-26 Marauder in World War II
2015-06-01
instruction on combat procedures, tactics, navigation, communication, and gunnery. The group flew local training missions, known as “ doughnut missions,” to...minimum altitude attacks by fighters, if properly delivered, were the most effective and economical aerial countermeasures against ski sites; medium and...attacks against bridges, its proponents saw these attacks as less economical due to the difficulty of destroying bridges and the large number of bombs
Directory of Open Access Journals (Sweden)
Basim H. Asghar
2017-12-01
Full Text Available The catalytic effect of copper(II catalyst on the oxidation of l-tryptophan (Trp by hexacyanoferrate(III (HCF, has been investigated spectrophotometrically in an aqueous alkaline medium at a constant ionic strength of 0.5Â molÂ dmâ3 and at 25Â Â°C. The stoichiometry for both the uncatalyzed and catalyzed reactions was 1:2 (Trp:HCF. The reactions exhibited first order kinetics with respect to [HCF] and less than unit orders with respect to [Trp] and [OHâ]. The catalyzed reaction exhibited fractional-first order kinetics with respect to [CuII]. The reaction rates were found to increase as the ionic strength and dielectric constant of the reaction medium increase. The effect of temperature on the rates of reactions has also been studied, and the activation parameters associated with the rate-determining steps of the reactions have been evaluated and discussed. Addition of the reaction product HCF(II to the reaction mixture did not affect the rates. Plausible mechanistic schemes for uncatalyzed and catalyzed reactions explaining all of the observed kinetic results have been proposed. In both cases, the final oxidation products are identified as indole-3-acetaldehyde, ammonia, and carbon dioxide. The rate laws associated with the reactionsâ mechanisms are derived. The rate constants of the slow steps of the reactions along with the equilibrium constants are also calculated. Keywords: Oxidation, Kinetics, l-Tryptophan, Hexacyanoferrate(III, Copper(II, Catalysis
Influence of the medium on the reaction rate of the t-butoxyl radical with iron(II)
International Nuclear Information System (INIS)
Mihaljevic, B.; Razem, D.
2002-01-01
Complete text of publication follows. Tert-butoxyl radicals (t-BuO.) were generated by homolytic photodecomposition of di-tert-butylperoxide using ruby laser flashes at 347 nm. The reaction of t-BuO. radicals with Fe 2+ was studied under pseudo-first order conditions. The quantum yield Φ(Fe 3+ ) was determined by measuring the absorbance of Fe 3+ ion as [FeCl] 2+ complex at 360 nm 2 μs after the flash. According to the equation derived from the reaction scheme, the rate constant k 3 was obtained from the relative rate constant k r (k r =k 0 /k 3 ) and the value of k 0 ; the latter refers to the overall rate of the competing disappearance of t-BuO. radicals from the system (reaction 2), including the highest contribution of β-cleavage. The rate constant k 0 was determined using diphenylmethanol instead of Fe 2+ . The known rate constant of the reaction of t-BuO. radical with diphenylmethanol giving ketyl radicals (6.9 x 10 6 dm 3 mol -1 s -1 ) was applied. The quantum yield of ketyl radicals was determined by measuring the maximum of absorbance at 535 nm. At acid concentration of 0.023 mol dm -3 HCl the rate constant k 3 = 3.4 x 10 8 dm 3 mol -1 s -1 was determined. The relative rate constant increased with an increase of the hydrochloric acid concentration which has been ascribed to the lower stability of t-BuO. radical at higher acidity of the medium. The effect of polarity of the medium on the reaction rate was also determined. Decreasing k 3 in media of increasing polarity were explained by increasing of the β-scission rate of t-BuO. radical with increasing polarity of the medium
DEFF Research Database (Denmark)
Yang, Zhiwen; Liu, Shuxue; Bingham, Harry B.
2014-01-01
This paper provides an experimental validation of the second-order coupling theory outlined by Yang et al. (Z. Yang, S. Liu, H.B. Bingham and J. Li., 2013. Second-order coupling of numerical and physical wave tanks for 2D irregular waves. Part I: Formulation, implementation and numerical properties......, submitted for publication) using 2D irregular waves. This work provides a second-order dispersive correction for the physical wavemaker signal which improves the nonlinear transfer of information between the numerical and physical models compared to the first-order method of Zhang et al. (2007......). The important nonlinear parameters and numerical performance were theoretically investigated in Part I. In the present Part II, careful experimental validation is carried out using a sequence of progressively more complex analytical and numerical target waves. The results demonstrate clearly that improved...
Polarographic study of Cd(II)-Schiff base complexes and d.m.e. menthanol-water medium
International Nuclear Information System (INIS)
Patel, M.S.; Trivedi, T.; Vyas, D.N.
1978-01-01
Three Schiff base complexes of Cd 2+ have been investigated polarographically in 60% menthanol-water medium at 26 0 C. The Schiff bases used are salicyladehyde tris buffer (ST), benzaldehydetris buffer (BT) and vanillin tris buffer (VT). Cd-ST and Cd-VT complexes produce reversible reduction wave at dme, while Cd-BT gives a quasi reversible wave. Stability constants of the complexes have been determined and the standard overall electrode reaction rate constant (ksub(e)sup(o)) B of the Cd-BT complex is determined by three different methods. The log β values of complexes are : Cd-ST, 2.72; Cd-VT, 4.90; and Cd-BT, 4.41. (author)
International Nuclear Information System (INIS)
Heintze, E.
1993-01-01
The aim of this report is to validate the program MAX3D built up from the discretization of the formulation (FB) established in part 1. A qualitative and quantitative analysis is carried out on numerical results obtained with various test cases of which, for most of them, analytical solutions are known. 32 figs., 3 refs
Nishimura, Kazutoshi; Hagiwara, Makoto; Akagi, Hirofumi
This paper presents a medium-voltage motor drive with a modular multilevel PWM inverter, and focuses on a startup method and its performance. It is formed by six modular arms, each of which consists of a cascaded stack of multiple bidirectional chopper-cells. The frequency of the dominant ac-voltage fluctuation is equal to the motor (inverter) frequency. These fluctuations occur in the dc capacitor of each chopper-cell, and the magnitude of the fluctuation is inversely proportional to the motor frequency. Because of the increased voltage fluctuation in low-frequency regions, the so-called “volt-per-hertz control” cannot be applied in motor starting. The startup method proposed in this paper is suitable for a motor drive with the modular multilevel PWM inverter. It enables the motor to produce a startup torque loaded on the motor at an initial amplitude and a fixed frequency of the inverter while taking into account constraints on the motor current and the ac-voltage fluctuation. The validity of the startup method as well as the startup performance is confirmed by experiment and simulation.
International Nuclear Information System (INIS)
Floquet, S.; Eysseric, C.
2006-01-01
Oxidation of the nitrosyl ruthenium complex RuNO(OH) 5 2- has been carried out in sodium hydroxide solutions in contact with a gas flow containing ozone. The RuNO(OH) 5 2- complex is converted successively into ruthenate and perruthenate ions. An empirical kinetic rate law for the first step has been determined and was shown to depend on concentrations of (i) the ruthenium complex, (ii) the hydroxide ions and (iii) ozone concentration in the gas flow. The second step of the reaction, corresponding to the perruthenate ion formation, shows a complex mechanism and four competing reactions have been proposed to represent it. The influences on the second step kinetics of several parameters such as ozone or hydroxide concentrations or the conditions of the gas-liquid exchange area are also qualitatively discussed. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Floquet, S. [Commissariat a l' Energie Atomique (CEA/Valrho), Bagnols-sur-Ceze (France); Inst. Lavoisier, IREM UMR 8637, Univ. de Versailles Saint-Quentin, Versailles (France); Eysseric, C. [Commissariat a l' Energie Atomique (CEA/Valrho), Bagnols-sur-Ceze (France)
2006-07-01
Oxidation of the nitrosyl ruthenium complex RuNO(OH){sub 5}{sup 2-} has been carried out in sodium hydroxide solutions in contact with a gas flow containing ozone. The RuNO(OH){sub 5}{sup 2-} complex is converted successively into ruthenate and perruthenate ions. An empirical kinetic rate law for the first step has been determined and was shown to depend on concentrations of (i) the ruthenium complex, (ii) the hydroxide ions and (iii) ozone concentration in the gas flow. The second step of the reaction, corresponding to the perruthenate ion formation, shows a complex mechanism and four competing reactions have been proposed to represent it. The influences on the second step kinetics of several parameters such as ozone or hydroxide concentrations or the conditions of the gas-liquid exchange area are also qualitatively discussed. (orig.)
Remy, Q.; Grenier, I. A.; Marshall, D. J.; Casandjian, J. M.
2018-03-01
Aim. H I 21-cm and 12CO 2.6-mm line emissions trace the atomic and molecular gas phases, respectively, but they miss most of the opaque H I and diffuse H2 present in the dark neutral medium (DNM) at the transition between the H I-bright and CO-bright regions. Jointly probing H I, CO, and DNM gas, we aim to constrain the threshold of the H I-H2 transition in visual extinction, AV, and in total hydrogen column densities, NHtot. We also aim to measure gas mass fractions in the different phases and to test their relation to cloud properties. Methods: We have used dust optical depth measurements at 353 GHz, γ-ray maps at GeV energies, and H I and CO line data to trace the gas column densities and map the DNM in nearby clouds toward the Galactic anticentre and Chamaeleon regions. We have selected a subset of 15 individual clouds, from diffuse to star-forming structures, in order to study the different phases across each cloud and to probe changes from cloud to cloud. Results: The atomic fraction of the total hydrogen column density is observed to decrease in the (0.6-1) × 1021 cm-2 range in NHtot (AV ≈ 0.4 mag) because of the formation of H2 molecules. The onset of detectable CO intensities varies by only a factor of 4 from cloud to cloud, between 0.6 × 1021 cm-2 and 2.5 × 1021 cm-2 in total gas column density. We observe larger H2 column densities than linearly inferred from the CO intensities at AV > 3 mag because of the large CO optical thickness; the additional H2 mass in this regime represents on average 20% of the CO-inferred molecular mass. In the DNM envelopes, we find that the fraction of diffuse CO-dark H2 in the molecular column densities decreases with increasing AV in a cloud. For a half molecular DNM, the fraction decreases from more than 80% at 0.4 mag to less than 20% beyond 2 mag. In mass, the DNM fraction varies with the cloud properties. Clouds with low peak CO intensities exhibit large CO-dark H2 fractions in molecular mass, in particular the
Energy Technology Data Exchange (ETDEWEB)
Boumaiza, Hella [Laboratoire de Chimie des Matériaux et Catalyse, Faculté des Sciences de Tunis, Université El Manar (Tunisia); Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME)-UMR 7564, CNRS-Université de Lorraine, 405, rue de Vandoeuvre, 54600 Villers-lès-Nancy (France); Département de Génie Biologique et Chimique, Institut National des Sciences Appliquées et de Technologies (INSAT), Université de Carthage, Tunis (Tunisia); Coustel, Romain [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME)-UMR 7564, CNRS-Université de Lorraine, 405, rue de Vandoeuvre, 54600 Villers-lès-Nancy (France); Medjahdi, Ghouti [Institut Jean Lamour, Centre de Compétences Rayons X et Spectroscopie (X-Gamma), UMR 7198 CNRS-Université de Lorraine (France); Ruby, Christian, E-mail: Christian.ruby@univ-lorraine.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME)-UMR 7564, CNRS-Université de Lorraine, 405, rue de Vandoeuvre, 54600 Villers-lès-Nancy (France); and others
2017-04-15
Birnessite was synthetized through redox reaction by mixing MnO{sub 4}{sup -}, Mn{sup 2+} and OH{sup -} solutions. The Mn(VII): Mn(II) ratio of 0.33 was chosen and three methods were used consisting in a quick mixing under vigorous stirring of two of the three reagents and then on the dropwise addition of the third one. The obtained solids were characterized by XRD, FTIR and XPS spectroscopies. Their average oxidation states were determined from ICP and CEC measurements while their surface properties were investigated by XPS. This study provides an increased understanding of the importance of dissolved oxygen in the formation of birnessite and hausmannite and shows the ways to obtain pure birnessite. The role of counter-ion ie. Na{sup +} or K{sup +} was also examined. - Graphical abstract: Pathways of birnessite formation. - Highlights: • Pure birnessite is prepared through a redox reaction. • Hausmannite formation is prevented by controlling dissolved O2. • The employed counterion influences the purity of birnessite. • Initial Mn(OH){sub 2} is oxidized by both MnO{sub 4}{sup -} and dissolved O{sub 2}.
International Nuclear Information System (INIS)
Hayes, D.B.
1975-01-01
Constitutive assumptions of local thermal and pressure equilibrium in a mixture of N transforming phases allow construction of a constitutive equation of a generalized Maxwellian form suitable for studying the kinetics of phase transformations induced by shock-wave loading. This equation relates the pressure rate to the strain rate and the phase change rate, the latter being expressed as the time derivative of a vector which has components equal to the mass fractions of the constituent phases. A separate kinetic equation is required for evolution of this composition vector. Coefficients appearing in the constitutive equation depend only on properties that the mixture displays with a frozen composition which in turn depend directly on properties of the pure-phase components of the mixture. The constitutive equation is applied to solid-I--solid-II--liquid bismuth (N = 3). When wave propagation calculations on bismuth are compared with previous theory and experiments, a lower bound on the melting rate of 4 μsec -1 is found
Ye, Gang; Bai, Feifei; Wei, Jichao; Wang, Jianchen; Chen, Jing
2012-07-30
A novel kind of polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6) was synthesized through a post-modification approach. The DCH18C6 moieties bearing amino groups were firstly prepared, followed by covalent grafting to a silica precursor P-(CH(2))(3)-Cl (Where P represents a 3-dimentional polymerized silica matrix) based on nucleophilic substitution reaction. (29)Si and (13)C solid-state NMR, FT-IR, XPS, TGA, ESEM and elemental analysis were employed to systematically characterize the structure, thermal property and surface morphology of the functionalized resin. The results indicated that the DCH18C6 ligands were successfully bonded to the polysiloxane resin with a satisfactory grafting degree (33.6wt.%). Due to the robust organosilica framework and the covalent immobilization of the ligands, the functionalized resin had excellent thermal stability and acid resistance. Batch experiments showed that the resin could effectively separate Sr(II) in high acidity mediums. The distribution coefficient (K(d)) of 43.6cm(3)/g could be achieved in 5.0mol/L HNO(3) solution. The influences of contact time and acidity of HNO(3) on the resin's extraction performance were examined. The reusability and the selectivity to Sr(II) over interference ions were investigated. The DCH18C6-functionalized resin might be potentially applied for the radiostrontium removal in the high level liquid waste (HLLW). Copyright © 2012 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Rahma Bouabda
2016-12-01
Full Text Available This investigation deals with the numerical simulation of entropy generation at mixed convection flow in a lid-driven saturated porous cavity submitted to a magnetic field. The magnetic field is applied in the direction that is normal to the cavity cross section. The governing equations, written in the Darcy–Brinkman–Forchheimer formulation, are solved using a numerical code based on the Control Volume Finite Element Method. The flow structure and heat transfer are presented in the form of streamlines, isotherms and average Nusselt number. The entropy generation was studied for various values of Darcy number (10−3 ≤ Da ≤ 1 and for a range of Hartmann number (0 ≤ Ha ≤ 102. It was found that entropy generation is affected by the variations of the considered dimensionless physical parameters. Moreover, the form drag related to the Forchheimer effect remains significant until a critical Hartmann number value.
Serafin, R. A.; Wnuk, E.
The relative accuracy of ordinary and symmetric difference quotients for elementary functions employed in orbit corrections is investigated analytically. The theoretical results of Serafin (1982) are applied to numerical computations in rectangular coordinates, and results for a number of generalized and practical problems are presented in extensive graphs and discussed in detail. The numerical results confirm that symmetric difference quotients give significantly more accurate predictions than ordinary difference quotients.
Malakpoor, K.; Kaasschieter, E.F.; Huyghe, J.M.
2007-01-01
Abstract: The swelling and shrinkage of biological tissues are modelled by a four-component mixture theory [J.M. Huyghe and J.D. Janssen, Int. J. Engng. Sci. 35 (1997) 793-802; K. Malakpoor, E.F. Kaasschieter and J.M. Huyghe, Mathematical modelling and numerical solution of swelling of cartilaginous
Arrigoni Battaia, Fabrizio; Hennawi, Joseph F.; Prochaska, J. Xavier; Cantalupo, Sebastiano
2015-08-01
The recent discovery by Cantalupo et al. of the largest (˜500 kpc) luminous (L ≃ 1.43 × 1045 erg s-1) Lyα nebula associated with the quasar UM287 (z = 2.279) poses a great challenge to our current understanding of the astrophysics of the halos hosting massive z ˜ 2 galaxies. Either an enormous reservoir of cool gas is required M ≃ 1012 M⊙, exceeding the expected baryonic mass available, or one must invoke extreme gas clumping factors not present in high-resolution cosmological simulations. However, observations of Lyα emission alone cannot distinguish between these two scenarios. We have obtained the deepest ever spectroscopic integrations in the He ii λ1640 and C iv λ1549 emission lines with the goal of detecting extended line emission, but detect neither line to a 3σ limiting SB ≃ 10-18 erg s-1 cm-2 arcsec-2. We construct simple models of the expected emission spectrum in the highly probable scenario that the nebula is powered by photoionization from the central hyper-luminous quasar. The non-detection of He ii implies that the nebular emission arises from a mass Mc ≲ 6.4 × 1010 M⊙ of cool gas on ˜200 kpc scales, distributed in a population of remarkably dense (nH ≳ 3 cm-3) and compact (R ≲ 20 pc) clouds, which would clearly be unresolved by current cosmological simulations. Given the large gas motions suggested by the Lyα line (v ≃ 500 km s-1), it is unclear how these clouds survive without being disrupted by hydrodynamic instabilities. Our work serves as a benchmark for future deep integrations with current and planned wide-field IFU spectrographs such as MUSE, KCWI, and KMOS. Our observations and models suggest that a ≃10 hr exposure would likely detect ˜10 rest-frame UV/optical emission lines, opening up the possibility of conducting detailed photoionization modeling to infer the physical state of gas in the circumgalactic medium. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a
International Nuclear Information System (INIS)
Corge, Ch.
1969-01-01
Numerical analysis of transmission resonances induced by s wave neutrons in time-of-flight experiments can be achieved in a fairly automatic way on an IBM 7094/II computer. The involved computations are carried out following a four step scheme: 1 - experimental raw data are processed to obtain the resonant transmissions, 2 - values of experimental quantities for each resonance are derived from the above transmissions, 3 - resonance parameters are determined using a least square method to solve the over determined system obtained by equalling theoretical functions to the correspondent experimental values. Four analysis methods are gathered in the same code, 4 - graphical control of the results is performed. (author) [fr
Padovan, J.; Adams, M.; Lam, P.; Fertis, D.; Zeid, I.
1982-01-01
Second-year efforts within a three-year study to develop and extend finite element (FE) methodology to efficiently handle the transient/steady state response of rotor-bearing-stator structure associated with gas turbine engines are outlined. The two main areas aim at (1) implanting the squeeze film damper element into a general purpose FE code for testing and evaluation; and (2) determining the numerical characteristics of the FE-generated rotor-bearing-stator simulation scheme. The governing FE field equations are set out and the solution methodology is presented. The choice of ADINA as the general-purpose FE code is explained, and the numerical operational characteristics of the direct integration approach of FE-generated rotor-bearing-stator simulations is determined, including benchmarking, comparison of explicit vs. implicit methodologies of direct integration, and demonstration problems.
Busschaert, C.; Falize, É.; Michaut, C.; Bonnet-Bidaud, J.-M.; Mouchet, M.
2015-07-01
Context. Magnetic cataclysmic variables are close binary systems containing a strongly magnetized white dwarf that accretes matter coming from an M-dwarf companion. The high magnetic field strength leads to the formation of an accretion column instead of an accretion disk. High-energy radiation coming from those objects is emitted from the column close to the white dwarf photosphere at the impact region. Its properties depend on the characteristics of the white dwarf and an accurate accretion column model allows the properties of the binary system to be inferred, such as the white dwarf mass, its magnetic field, and the accretion rate. Aims: We study the temporal and spectral behaviour of the accretion region and use the tools we developed to accurately connect the simulation results to the X-ray and optical astronomical observations. Methods: The radiation hydrodynamics code Hades was adapted to simulate this specific accretion phenomena. Classical approaches were used to model the radiative losses of the two main radiative processes: bremsstrahlung and cyclotron. Synthetic light curves and X-ray spectra were extracted from numerical simulations. A fast Fourier analysis was performed on the simulated light curves. The oscillation frequencies and amplitudes in the X-ray and optical domains are studied to compare those numerical results to observational ones. Different dimensional formulae were developed to complete the numerical evaluations. Results: The complete characterization of the emitting region is described for the two main radiative regimes: when only the bremsstrahlung losses and when both cyclotron and bremsstrahlung losses are considered. The effect of the non-linear cooling instability regime on the accretion column behaviour is analysed. Variation in luminosity on short timescales (~1 s quasi-periodic oscillations) is an expected consequence of this specific dynamic. The importance of secondary shock instability on the quasi-periodic oscillation
M. Raguraman; A. Deb; N. K. Gupta; D. K. Kharat
2008-01-01
In Part I of the current two-part series, a comprehensive simulation-based study of impact of jacketed projectiles on mild steel armour plates has been presented. Using the modelling procedures developed in Part I, a number of parametric studies have been carried out for the same mild steel plates considered in Part I and reported here in Part II. The current investigation includes determination of ballistic limits of a given target plate for different projectile diameters and impact velociti...
Raguraman, M; Deb, A; Gupta, NK; Kharat, DK
2008-01-01
In Part I of the current two-part series, a comprehensive simulation-based study of impact of Jacketed projectiles on mild steel armour plates has been presented. Using the modelling procedures developed in Part I, a number of parametric studies have been carried out for the same mild steel plates considered in Part I and reported here in Part II. The current investigation includes determination of ballistic limits of a given target plate for different projectile diameters and impact velociti...
International Nuclear Information System (INIS)
Buntine, J.D.
1994-01-01
Part I. A study of the behaviour of an inviscid, swirling fluid is performed. This flow can be described by the Squire-Long equation if the constraints of time-independence and axisymmetry are invoked. The particular case of flow through a diverging pipe is selected and a study is conducted to determine over what range of parameters does a solution exist. The work is performed with a view to understanding how the phenomenon of vortex breakdown develops. Experiments and previous numerical studies have indicated that the flow is sensitive to boundary conditions particularly at the pipe inlet. A open-quotes quasi-cylindricalclose quotes amplification of the Squire-Long equation is compared with the more complete model and shown to be able to account for most of its behaviour. An advantage of this latter representation is the relatively undetailed description of the flow geometry it requires in order to calculate a solution. open-quotes Criticalityclose quotes or the ability of small disturbances to propagate upstream is related to results of the quasi-cylindrical and axisymmetric flow models. This leads to an examination of claims made by researchers such as Benjamin and Hall concerning the interrelationship between open-quotes failureclose quotes of the quasi-cylindrical model and the occurrence of a open-quotes criticalclose quotes flow state. Lundgren developed an analytical model for homogeneous turbulence based on a collection of contracting spiral vortices each embedded in an axisymmetric strain field. Using asymptotic approximations he was able to deduce the Kolmogorov k -5/3 behaviour for inertial scales in the turbulence energy spectrum. Pullin ampersand Saffman have enlarged upon his work to make a number of predictions about the behaviour of turbulence described by the model. This work investigates the model numerically. The first part considers how the flow description compares with numerical simulations using the Navier-Stokes equations
DEFF Research Database (Denmark)
Anyfantis, Konstantinos; Tsouvalis, Nicholas G.
2013-01-01
This work is focused on the numerical simulation of experimentally tested single lap joints, based on cohesive zone modeling techniques. Seven cases have been considered for analysis. The models were built in a 3-dimensional finite element space. The adherents were modeled with continuum elements....... The traction increase part of the cohesive laws is given by an exponential function, which describes the elastoplastic adhesive response, and the traction decrease part is given by a linear function, which describes damage initiation and propagation. By using this model, it was achieved to calculate...
Directory of Open Access Journals (Sweden)
Adrian TOADER
2010-09-01
Full Text Available The paper was conceived in two parts. Part I, previously published in this journal, highlighted the main steps of adaptive output feedback control for non-affine uncertain systems, having a known relative degree. The main paradigm of this approach was the feedback linearization (dynamic inversion with neural network augmentation. Meanwhile, based on new contributions of the authors, a new paradigm, that of robust servomechanism problem solution, has been added to the controller architecture. The current Part II of the paper presents the validation of the controller hereby obtained by using the longitudinal channel of a hovering VTOL-type aircraft as mathematical model.
Sjoegreen, Bjoern; Yee, H. C.
2003-01-01
The generalization of a class of low-dissipative high order filter finite difference schemes for long time wave propagation of shock/turbulence/combustion compressible viscous gas dynamic flows to compressible MHD equations for structured curvilinear grids has been developed. The new scheme consists of a divergence free preserving high order spatial base scheme with a filter approach which can be divergence-free preserving depending on the type of filter operator being used, the method of applying the filter step, and the type of flow problem to be considered. Several variants of the filter approach that cater to different flow types are proposed. These filters provide a natural and efficient way for the minimization of the divergence of the magnetic field (Delta * B) numerical error in the sense that no standard divergence cleaning is required. Performance evaluation of these variants, and the key role that the proper treatment of their corresponding numerical boundary conditions can play will be illustrated. Many levels of grid refinement and detailed comparison with several commonly used compressible MHD shock-capturing schemes will be sought. For certain MHD 2-D test problems, divergence free preservation of the magnetic fields of these filter schemes has been achieved.
Directory of Open Access Journals (Sweden)
Kamil Urbanowicz
2015-09-01
Full Text Available Modelling of time-depended hydraulic friction is not an easy issue. As numerous studies have shown, wall shear stress in the pipe can be determined as a sum of the quasi-steady and time-dependent expressions. Time-depended expression is an convolution integral of the local acceleration of the liquid and a weighting function. The weighting function, in general, makes allowance for relation of historic velocity changes and unsteady component of wall shear stress. The original weighting function has usually a very complicated structure, and what is more it makes impossible to do an efficient simulation of dynamical runs. In this paper, in order to enable efficient calculation of unsteady component wall shear stress, new weighting functions are presented as a sum of exponential components. To aim this goal in case of turbulent flow, the scaling procedure proposed by Vitkovsky et al. is used. This method makes very easy the estimation of any new turbulent weighting function. Presented approximated weighting functions are compared with the original counterparts, known from literature in case of laminar and turbulent flows. Using the previously discussed models of cavitation flow CSM, CSMG, CSMA, and the BCM with implemented effective weighting function a series of simulation studies has been made, which showed that the introduced changes in models of unsteady flow with cavitation greatly improve the degree of simulation fit in comparison with experimental results.[b]Keywords[/b]: numerical fluid mechanics, transient flow, cavitation, frequency-dependent friction losses, pipeline, waterhammer
Sonneborn, George; Tripp, Todd M.; Ferlet, Roger; Jenkins, Edward B.; Sofia, U. J.; Vidal-Madjar, Alfred; Woźniak, Prezemysław R.
2000-12-01
High-resolution far-ultraviolet spectra of the early-type stars γ2 Vel and ζ Pup were obtained to measure the interstellar deuterium abundances in these directions. The observations were made with the Interstellar Medium Absorption Profile Spectrograph (IMAPS) during the ORFEUS-SPAS II mission in 1996. IMAPS spectra cover the wavelength range 930-1150 Å with λ/Δλ~80,000. The interstellar D I features are resolved and cleanly separated from interstellar H I in the Lyδ and Lyɛ profiles of both sight lines and also in the Lyγ profile of ζ Pup. The D I profiles were modeled using a velocity template derived from several N I lines in the IMAPS spectra recorded at higher signal-to-noise ratio. To find the best D I column density, we minimized χ2 for model D I profiles that included not only the N(D I) as a free parameter, but also the effects of several potential sources of systematic error, which were allowed to vary as free parameters. H I column densities were measured by analyzing Lyα absorption profiles in a large number of IUE high-dispersion spectra for each of these stars and applying this same χ2-minimization technique. Ultimately we found that D/H=2.18+0.36-0.31×10-5 for γ2 Vel and 1.42+0.25-0.23×10-5 for ζ Pup, values that contrast markedly with D/H derived in Paper I for δ Ori A (the stated errors are 90% confidence limits). Evidently, the atomic D/H ratio in the ISM, averaged over path lengths of 250-500 pc, exhibits significant spatial variability. Furthermore, the observed spatial variations in D/H do not appear to be anticorrelated with N/H, one measure of heavy-element abundances. We briefly discuss some hypotheses to explain the D/H spatial variability. Within the framework of standard big bang nucleosynthesis, the large value of D/H found toward γ2 Vel is equivalent to a cosmic baryon density of ΩBh2=0.023+/-0.002, which we regard as an upper limit since there is no correction for the destruction of deuterium in stars. This paper is
International Nuclear Information System (INIS)
Krätschmer, D.; Roos, E.; Schuler, X.; Herter, K.-H.
2012-01-01
For the construction, design and operation of nuclear components and systems the appropriate technical codes and standards provide detailed analysis procedures which guarantee a reliable behaviour of the structural components throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. To consider effects of light water reactor coolant environments, new design curves included in report NUREG/CR-6909 for austenitic stainless steels and for low alloy steels have been presented. For the usage of these new design curves an environmental fatigue correction factor for incorporating environmental effects has to be calculated and used. The application of this environmental correction factor to a fatigue analysis of a nozzle with transient stratification loads, derived by in-service monitoring, has been performed. The results are used to compare with calculated usage factors, based on design curves without taking environmental effects particularly into account. - Highlights: ► We model an nozzle for fatigue analysis und mechanical and thermal loading conditions. ► A simplified as well as a general elastic–plastic fatigue analysis considering environmental effects is performed. ► The influence of different factors calculating the environmental factor F en are shown. ► The presented numerical evaluation methodology allows the consideration of all relevant parameters to assess lifetime.
Wang, Ding; Ding, Pin-bo; Ba, Jing
2018-03-01
In Part I, a dynamic fracture compliance model (DFCM) was derived based on the poroelastic theory. The normal compliance of fractures is frequency-dependent and closely associated with the connectivity of porous media. In this paper, we first compare the DFCM with previous fractured media theories in the literature in a full frequency range. Furthermore, experimental tests are performed on synthetic rock specimens, and the DFCM is compared with the experimental data in the ultrasonic frequency band. Synthetic rock specimens saturated with water have more realistic mineral compositions and pore structures relative to previous works in comparison with natural reservoir rocks. The fracture/pore geometrical and physical parameters can be controlled to replicate approximately those of natural rocks. P- and S-wave anisotropy characteristics with different fracture and pore properties are calculated and numerical results are compared with experimental data. Although the measurement frequency is relatively high, the results of DFCM are appropriate for explaining the experimental data. The characteristic frequency of fluid pressure equilibration calculated based on the specimen parameters is not substantially less than the measurement frequency. In the dynamic fracture model, the wave-induced fluid flow behavior is an important factor for the fracture-wave interaction process, which differs from the models at the high-frequency limits, for instance, Hudson's un-relaxed model.
Tong, Sheng; Yuan, Fan
2008-01-01
Angiogenesis involves interactions among various molecules and cells. To understand the complexity of interactions, we developed a mathematical model to numerically simulate angiogenesis induced by basic fibroblast growth factor (bFGF) in the corneal pocket assay. The model considered interstitial transport of bFGF, cellular uptake of bFGF, and dynamics of vessel growth. The model was validated by comparing simulated vascular networks, induced by bFGF at three different doses: 5 ng, 15 ng, and 50 ng, with experimental data obtained in the first part of the study, in terms of migration distance of vascular network, total vessel length, and number of vessels. The model was also used to simulate growth dynamics of vascular networks as well as spatial and temporal distribution of bFGF, which could not be measured experimentally. Taken together, results of the study suggested that the coupling between diffusion and cellular uptake of bFGF was critical for determining structures of vascular networks and that the mathematical model was appropriate for simulation of angiogenesis in the cornea.
Cheng, C.-C.; Oran, E. S.; Doschek, G. A.; Boris, J. P.; Mariska, J. T.
1983-01-01
The NRL's Dynamic Flux Tube Model is used to numerically simulate the dynamic response of a coronal magnetic loop to an energy input of the order encountered in solar flares. The coronal plasma is heated by the deposition of flare energy at the top of the loop to more than 10 million K, yielding a conduction front that moves toward the chromosphere, where the plasma is heated by the large downward conductive flux and ablates upward to the coronal part of the loop at velocities of a few hundred km/sec. The conduction front simultaneously produces chromospheric ablation and compresses the material ahead of it. With the aid of compressional instabilities, the compressed plasma grows throughout the flare heating phase, presenting a possible source of the flare optical continuum emission which is correlated with soft X-ray radiation. The observational consequences of rapidly heated loop gas dynamic processes are discussed. In the second part of this presentation, the dynamical calculation results previously obtained are used to predict the spectral line intensities, profiles and wavelengths of several X-ray lines and the UV line of Fe XXI at 1354.1 A. Three different viewing orientations of the loop are considered.
Raskutti, Sudhir; Ostriker, Eve C.; Skinner, M. Aaron
2017-12-01
Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of turbulent star-forming clouds to analyze the detailed interaction between non-ionizing UV radiation and the cloud material. Our simulations trace the evolution of gas and star particles through self-gravitating collapse, star formation, and cloud destruction via radiation-driven outflows. These models are idealized in that we include only radiation feedback and adopt an isothermal equation of state. Turbulence creates a structure of dense filaments and large holes through which radiation escapes, such that only ˜50% of the radiation is (cumulatively) absorbed by the end of star formation. The surface density distribution of gas by mass as seen by the central cluster is roughly lognormal with {σ }{ln{{Σ }}}=1.3{--}1.7, similar to the externally projected surface density distribution. This allows low surface density regions to be driven outwards to nearly 10 times their initial escape speed {v}{esc}. Although the velocity distribution of outflows is broadened by the lognormal surface density distribution, the overall efficiency of momentum injection to the gas cloud is reduced because much of the radiation escapes. The mean outflow velocity is approximately twice the escape speed from the initial cloud radius. Our results are also informative for understanding galactic-scale wind driving by radiation, in particular, the relationship between velocity and surface density for individual outflow structures and the resulting velocity and mass distributions arising from turbulent sources.
Sonntag, D; Stachniss-Carp, S; Stachniss, C; Stachniss, V
2006-04-01
The aim of this paper is to present a new method based on numeric calculus to provide data on any type of root canal curvature at any point of the long axis of the canal. Twenty severely curved, simulated root canals were prepared with rotary FlexMaster and Profile instruments in the crown-down technique and manually in the step-back technique. The inner and outer curvatures were registered in a system of coordinates before and after preparation in increments of 0.5 mm. Using an equalising function, the curvatures were first represented in graphic and algebraic form. The maximum and the mean curvature as well as the length of the arc from the apical foramen to the point of maximum curvature were determined mathematically. An increase in maximum curvature was registered for all four shaping systems investigated. The radius of the inner curvature decreased by 0.5-1.2 mm in the manual systems as a result of the preparation. The Profile system displayed the smallest changes in radius (-0.9 mm) even with the outer curvature, and manual preparation with stainless steel files the most pronounced change (-1.8 mm). The point of maximum curvature at the inner curvature was displaced by 1.6 mm to the apical foramen through manual preparation with Ni-Ti files. At the outer curvature, the maximum displacement (1.8 mm) recorded was also the result of preparation with Ni-Ti hand files, while a displacement of only 0.3 mm to the apical foramen was recorded with the other systems. The method offers a means of determining curvatures precisely without random specification of reference points. The method is also capable of registering only minor changes in curvature in the two-dimensional long axis of the canal.
Directory of Open Access Journals (Sweden)
Bintang Soetjahjo
2018-01-01
Full Text Available Currently, umbilical cord mesenchymal stem cells have the potential to be used as treatment options for any cartilage lesion. This research aimed to evaluate the effects of conditioned medium from umbilical cord mesenchymal stem cells (UC-MSC on damaged cartilage through the expression of proteins TGF-β1, SOX-9, type II collagen and aggrecan, which are known to be related to chondrogenesis. UC-MSC were isolated from 19-days-pregnant Wistar mice and were cultured using the standard procedure to obtain 80% confluence. Subsequently, the culture was confirmed through a microscopic examination that was driven to be an embryoid body to obtain a pre-condition medium. This research utilized 3-month-old male Wistar mice and was categorized into 6 groups (3 control and 3 treatment groups. Each animal had surgery performed to create a femur condyle cartilage defect. The treatment groups were administered a dose of stem cells at 1 mL/kg. Next, immunohistochemical (IHC staining was performed to examine the expression of TGF-β1, SOX-9, type II collagen and aggrecan in the 2nd, 3rd, and 4th month of evaluation. The results were analyzed statistically using ANOVA test. For each of the treatment groups, there was increased expression (p < 0.05 in all proteins TGF-β1, SOX-9, type II collagen and aggrecan when compared with control groups at the 2nd, 3rd, and 4th month of evaluation. Pre-conditioned medium from UC-MSC potentially increases the expression of TGF-β1, SOX-9, type II collagen and aggrecan in the damaged cartilage of Wistar mice.
Starling, R.L.C.; van der Horst, A.J.; Rol, E.; Wijers, R.A.M.J.; Kouveliotou, C.; Wiersema, K.; Curran, P.A.; Weltevrede, P.
2008-01-01
We constrain blast wave parameters and the circumburst media of a subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral
Directory of Open Access Journals (Sweden)
M.Y. Malik
2014-06-01
Full Text Available The present work concerns the pressure dependent viscosity in Carreau fluid through porous medium. Four different combinations of pressure dependent viscosity and pressure dependent porous medium parameters are considered for two types of flow situations namely (i Poiseuille flow and (ii Couette flow. The solutions of non-linear equations have been evaluated numerically by Shooting method along with Runge-Kutta Fehlberg method. The physical features of pertinent parameters have been discussed through graphs.
Directory of Open Access Journals (Sweden)
Luciano Vitali
2006-06-01
Full Text Available The aim of this study was to impregnate the chelating agent 3,3-bis-N,N,bis-(carboxymethylaminomethyl-o-cresolsulfonephthalein in chitosan and to investigate the adsorption of Cu(II ions. The chemical modification was confirmed by FTIR spectrometry, thermogravimetric analysis (TGA and energy dispersive x-ray spectroscopy (EDX. The adsorption studies were carried out with Cu(II ions in a batch process and were shown to be dependent on pH. The adsorption kinetics was tested using three models: pseudo first-order, pseudo second order and intraparticle diffusion. The experimental kinetics data were best fitted with the pseudo second-order model (R² = 0.999, which provided a rate constant, k2, of 1.21 x 10-3 g mg-1 min-1. The adsorption rate depended on the concentration of Cu(II ions on the adsorbent surface and on the quantity of Cu(II ions adsorbed at equilibrium. The Langmuir isotherm model provided the best fit for the equilibrium data in the concentration range investigated, with the maximum adsorption capacity being 81.0 mg of Cu(II per gram of adsorbent, as obtained from the linear equation of the isotherm. Desorption tests revealed that around 90% of the adsorbed metal was removed, using EDTA solution as the eluent. This result suggests that the polymeric matrix can be reused.
Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltervrede, P.
2008-01-01
We constrain blast wave parameters and the circumburst media ofa subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglow data. The spectral fits have been done in count space and include the effects ofmetallicity, and are compared with the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptions which include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of the microphysical parameters, we find a mean value ofp for the sample as a whole of 9.... oa -0.003.0" 2 a_ statistical analysis of the distribution demonstrates that the p-values in this sample are inconsistent with a single universal value forp at the 3 _ level or greater, which has significant implications for particle acceleration models. This approach provides us with a measured distribution ofcircumburst density structures rather than considering only the cases of k ----0 (homogeneous) and k - 2 (windlike). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly windlike. The fifth source has a value of 0 medium.
Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltevrede, P.
2007-01-01
We constrain blastwave parameters and the circumburst media of a subsample of BeppoSAX Gamma-Ray Bursts. For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical and nIR afterglow data. The spectral fits have been done in count space and include the effects of metallicity, and are compared with the previously reported optical and X-ray temporal behaviour. Assuming the fireball model, we can find a mean value of p for the sample as a whole of 2.035. A statistical analysis Of the distribution demonstrates that the p values in this sample are inconsistent with a single universal value for p at the 3sigma level or greater. This approach provides us with a measured distribution of circumburst density structures rather than considering only the cases of k = 0 (homogeneous) and k = 2 (wind-like). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly wind-like. The fifth source has a value of 0 less than or equal to k less than or equal to 1, consistent with a homogeneous circumburst medium.
International Nuclear Information System (INIS)
Shelke, D.N.
1983-01-01
The interaction of beryllium(II) with malonic, amino and thio acids in presence of some substituted and simple dicarboxylic acids has been studied. Mixed complexes of Be(II)-dicarboxylic acids with aspartic and thiomalic acids have been investigated. The distribution of the concentrations of simple and mixed species present, as a function of pH and other equilibrium constants have been utilized to explain the formation of mixed complexes. The estimation of stability constants by the relationship between complex stability and ligand basicity is discussed. The data point out that the slight differences present along the series of the complexes are not suppressed in the ternary ones. (author)
CSIR Research Space (South Africa)
Nandi, D
2015-09-01
Full Text Available . Quantitative immobilization of Ni(II) in an aqueous solution by the fluorescent sensor platform of GC was explored at varying pH, doses, contact times, and temperatures. The pseudo-second-order kinetics equation governed the overall sorption process...
Papacharalampopoulos, Alexios; Vavva, Maria G; Protopappas, Vasilios C; Fotiadis, Dimitrios I; Polyzos, Demosthenes
2011-08-01
Cortical bone is a multiscale heterogeneous natural material characterized by microstructural effects. Thus guided waves propagating in cortical bone undergo dispersion due to both material microstructure and bone geometry. However, above 0.8 MHz, ultrasound propagates rather as a dispersive surface Rayleigh wave than a dispersive guided wave because at those frequencies, the corresponding wavelengths are smaller than the thickness of cortical bone. Classical elasticity, although it has been largely used for wave propagation modeling in bones, is not able to support dispersion in bulk and Rayleigh waves. This is possible with the use of Mindlin's Form-II gradient elastic theory, which introduces in its equation of motion intrinsic parameters that correlate microstructure with the macrostructure. In this work, the boundary element method in conjunction with the reassigned smoothed pseudo Wigner-Ville transform are employed for the numerical determination of time-frequency diagrams corresponding to the dispersion curves of Rayleigh and guided waves propagating in a cortical bone. A composite material model for the determination of the internal length scale parameters imposed by Mindlin's elastic theory is exploited. The obtained results demonstrate the dispersive nature of Rayleigh wave propagating along the complex structure of bone as well as how microstructure affects guided waves.
Energy Technology Data Exchange (ETDEWEB)
Cristante, Valtair M. [Instituto de Quimica, Departamento de Quimica Analitica/UNESP, P.O. box-355, 14800-900, Araraquara, SP (Brazil); Jorge, Sonia M.A. [Instituto de Biociencias, Departamento de Quimica e Bioquimica/UNESP, P.O. box-510, 18618-000, Botucatu, SP (Brazil); Valente, Jose P.S. [Instituto de Biociencias, Departamento de Quimica e Bioquimica/UNESP, P.O. box-510, 18618-000, Botucatu, SP (Brazil); Saeki, Margarida J. [Faculdade de Ciencias de Bauru, Departamento de Quimica, P.O. box-473, 17033360, Bauru, SP, Brasil (Brazil); Florentino, Ariovaldo O. [Instituto de Biociencias, Departamento de Quimica e Bioquimica/UNESP, P.O. box-510, 18618-000, Botucatu, SP (Brazil); Padilha, Pedro M. [Instituto de Biociencias, Departamento de Quimica e Bioquimica/UNESP, P.O. box-510, 18618-000, Botucatu, SP (Brazil)]. E-mail: padilha@ibb.unesp.br
2007-05-07
This paper describes the preparation of thin titanium films via sol-gel route and their subsequent chemical modification by anchoring with 2-aminothiazole ligand and Pd(II) ion sorption, aiming to maximize the photocatalytic activity. The material was characterized by diffuse reflectance infrared Fourier transform spectroscopy, ultraviolet and visible spectrometry, X-ray diffractometry, and scanning electronic microscopy. The amount of palladium adsorbed on the film's surface, determined by graphite furnace atomic absorption spectrometry, showed a value of 2.69 x 10{sup 16} atoms cm{sup -2}. The photocatalytic tests indicated that the functionalization with 2-aminothiazole and the adsorption of palladium (II) were determinants in the semiconductor's enhanced photocatalytic activity.
Rao, G G; Rao, P K
1967-01-01
Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered.
Xu, Xingjian; Li, Haiyan; Wang, Quanying; Li, Dandan; Han, Xuerong; Yu, Hongwen
2017-05-01
A new sight of obtaining a high efficient biosorbent by supplying specific salts into bacterial growth medium was investigated in this study for Pb(II). Among a series of salts including Na 2 SO 4 , Na 2 S 2 O 3 , KCl, and K 2 SO 4 , the highest Pb(II) removal efficiency was observed by psychrotrophilic Pseudomonas putida I3 grown in the presence of 30g/L K 2 SO 4 (KSI3-30) with biosorption capacity of 62.89mg/g under cold condition (15°C), which was increased by 42.35% as compared to control (without any additive, RI3). This stimulation effect was ascribed to the increase of potassium and sulfur containing groups on KSI3-30 surface via metabolic dependent ways. The probable mechanism for Pb(II) adsorption was ion-exchange and chemical complexation. The thermal and kinetic data well fitted to Langmuir adsorption model and pseudo-second order and intraparticle diffusion kinetic model. Good recyclability and effectively dealing with real wastewater suggested KSI3-30 was a promising biosorbent for Pb-contaminated wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Gibbons John R
2001-07-01
Full Text Available Abstract Background Many cloned animals have been created by transfer of differentiated cells at G0/G1 or M phase of the cell cycle into enucleated M II oocytes having high maturation/meiosis/mitosis-promoting factor activity. Because maturation/meiosis/mitosis-promoting factor activity during oocyte maturation is maximal at both M I and M II, M I oocytes may reprogram differentiated cell nuclei as well. The present study was conducted to examine the developmental ability in vitro of porcine embryos reconstructed by transferring somatic cells (ear fibroblasts into enucleated M I or M II oocytes. Results Analysis of the cell cycle stages revealed that 91.2 ± 0.2% of confluent cells were at the G0/G1 phase and 54.1 ± 4.4% of nocodazole-treated cells were at the G2/M phase, respectively. At 6 h after activation, nuclear swelling was observed in 50.0-88.9% and 34.4-39.5% of embryos reconstituted with confluent cells and nocodazole-treated cells regardless of the recipient oocytes, respectively. The incidence of both a swollen nucleus and polar body was low (6.3-10.5% for all nocodazole-treated donor cell regardless of the recipient oocyte. When embryos reconstituted with confluent cells and M I oocytes were cultured, 2 (1.5% blastocysts were obtained and this was significantly (P Conclusions Porcine M I oocytes have a potential to develop into blastocysts after nuclear transfer of somatic cells.
Energy Technology Data Exchange (ETDEWEB)
O' Sullivan, E.; Vrtilek, J. M.; David, L. P.; Zezas, A.; Nulsen, P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Giacintucci, S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Ponman, T. J.; Raychaudhury, S. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Mamon, G. A. [Institut d' Astrophysique de Paris (UMR 7095 CNRS and UMPC), 98 bis Bd Arago, F-75014 Paris (France)
2014-10-01
We use a combination of deep Chandra X-ray observations and radio continuum imaging to investigate the origin and current state of the intra-group medium (IGM) in the spiral-rich compact group HCG 16. We confirm the presence of a faint (L {sub X,} {sub bolo} = 1.87{sub −0.66}{sup +1.03}×10{sup 41} erg s{sup –1}), low-temperature (0.30{sub −0.05}{sup +0.07} keV) IGM extending throughout the ACIS-S3 field of view, with a ridge linking the four original group members and extending to the southeast, as suggested by previous ROSAT and XMM-Newton observations. This ridge contains 6.6{sub −3.3}{sup +3.9}× 10{sup 9} M {sub ☉} of hot gas and is at least partly coincident with a large-scale H I tidal filament, indicating that the IGM in the inner part of the group is highly multi-phase. We present evidence that the group is not yet virialized, and show that gas has probably been transported from the starburst winds of NGC 838 and NGC 839 into the surrounding IGM. Considering the possible origin of the IGM, we argue that material ejected by galactic winds may have played a significant role, contributing 20%-40% of the observed hot gas in the system.
O'Sullivan, E.; Vrtilek, J. M.; David, L. P.; Giacintucci, S.; Zezas, A.; Ponman, T. J.; Mamon, G. A.; Nulsen, P.; Raychaudhury, S.
2014-10-01
We use a combination of deep Chandra X-ray observations and radio continuum imaging to investigate the origin and current state of the intra-group medium (IGM) in the spiral-rich compact group HCG 16. We confirm the presence of a faint (L X, bolo = 1.87+1.03-0.66×1041 erg s-1), low-temperature (0.30+0.07-0.05 keV) IGM extending throughout the ACIS-S3 field of view, with a ridge linking the four original group members and extending to the southeast, as suggested by previous ROSAT and XMM-Newton observations. This ridge contains 6.6+3.9-3.3× 109 M ⊙ of hot gas and is at least partly coincident with a large-scale {H} {I} tidal filament, indicating that the IGM in the inner part of the group is highly multi-phase. We present evidence that the group is not yet virialized, and show that gas has probably been transported from the starburst winds of NGC 838 and NGC 839 into the surrounding IGM. Considering the possible origin of the IGM, we argue that material ejected by galactic winds may have played a significant role, contributing 20%-40% of the observed hot gas in the system.
International Nuclear Information System (INIS)
Khattak, R.; Naqvi, I.I.; Farrukh, M.A.
2007-01-01
Kinetic of the redox reaction between tris (2,2-bipyridine)iron(II) cation and ceric sulphate has been studied in aqueous sulphuric acid medium. Different methods were employed for the determination of order of reaction. The order of reaction is found to be first with respect to reductant however retarding effect of increasing initial concentration of oxidant is found. Influence of (H/sup +/), (SO/sub 4/sup 2-) and dielectric constant (D) on the rate of redox reaction has also been studied. Increase in (H/sup +/) and dielectric constant of the medium retard the rate while enhancement of the (SO/sub 4/sup 2-/) accelerates the rate first and then the reaction goes towards retardation. Effects of (H/sup +/) and (SO/sub 4/sup 2-/) were studied by using acetic acid-sodium acetate buffer for the first one and varying ionic concentrations of the salt sodium sulphate for the latter one, whereas dielectric constant was varied by using 0%, 10% and 20% ethanol-water mixtures. Results of effects of each one of the factors i.e., H/sup +/, SO/sub 4/sup 2-/ and dielectric constant (D) have been compared and on the basis of these factors, (Ce(SO/sub 4/ )/sub 3/)/sup 2-/ is suggested to be the active species of cerium(IV). However a rate law consistent with the observed kinetic data has also been derived supporting the proposed mechanism. (author)
International Nuclear Information System (INIS)
Bodvarsson, G.S.; Lippmann, M.J.
1980-01-01
The computer program CCC (conduction-convection-consolidation), developed at Lawrence Berkeley Laboratory, solves numerically the heat and mass flow equations for a fully saturated medium, and computes one-dimensional consolidation of the simulated systems. The model employs the Integrated Finite Difference Method (IFDM) in discretizing the saturated medium and formulating the governing equations. The sets of equations are solved either by an iterative solution technique (old version) or an efficient sparse solver (new version). The deformation of the medium is calculated using the one-dimensional consolidation theory of Terzaghi. In this paper, the numerical code is described, validation examples given and areas of application discussed. Several example problems involving flow through fractured media are also presented
Energy Technology Data Exchange (ETDEWEB)
Ma, Bo; Tan, Jonathan C.; Barnes, Peter J. [Department of Astronomy, University of Florida, FL 32611 (United States)
2013-12-10
The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale (280° < l < 300°, –4° < b < 2°), unbiased, subparsec resolution survey of Galactic molecular clumps and their embedded stars. Barnes et al. presented the source catalog of ∼300 clumps based on HCO{sup +}(1-0) emission, used to estimate masses M. Here we use archival midinfrared-to-millimeter continuum data to construct spectral energy distributions. Fitting two-temperature gray-body models, we derive bolometric luminosities, L. We find that the clumps have 10 ≲ L/L {sub ☉} ≲ 10{sup 6.5} and 0.1 ≲ L/M/[L {sub ☉}/M {sub ☉}] ≲ 10{sup 3}, consistent with a clump population spanning a range of instantaneous star-formation efficiencies from 0 to ∼50%. We thus expect L/M to be a useful, strongly varying indicator of clump evolution during the star cluster formation process. We find correlations of the ratio of warm-to-cold component fluxes and of cold component temperature with L/M. We also find a near-linear relation between L/M and Spitzer-IRAC specific intensity (surface brightness); thus, this relation may also be useful as a star-formation efficiency indicator. The lower bound of the clump L/M distribution suggests that the star-formation efficiency per free-fall time is ε{sub ff} < 0.2. We do not find strong correlations of L/M with mass surface density, velocity dispersion, or virial parameter. We find a linear relation between L and L{sub HCO{sup +}(1--0)}, although with large scatter for any given individual clump. Fitting together with extragalactic systems, the linear relation still holds, extending over 10 orders of magnitude in luminosity. The complete nature of the CHaMP survey over a several kiloparsec-scale region allows us to derive a measurement at an intermediate scale, bridging those of individual clumps and whole galaxies.
International Nuclear Information System (INIS)
Roman-Duval, Julia; Gordon, Karl D.; Meixner, Margaret; Bot, Caroline; Bolatto, Alberto; Jameson, Katherine; Hughes, Annie; Hony, Sacha; Wong, Tony; Babler, Brian; Bernard, Jean-Philippe; Clayton, Geoffrey C.; Fukui, Yasuo; Galametz, Maud; Galliano, Frederic; Lebouteiller, Vianney; Lee, Min-Young; Glover, Simon; Israel, Frank; Li, Aigen
2014-01-01
The spatial variations of the gas-to-dust ratio (GDR) provide constraints on the chemical evolution and lifecycle of dust in galaxies. We examine the relation between dust and gas at 10-50 pc resolution in the Large and Small Magellanic Clouds (LMC and SMC) based on Herschel far-infrared (FIR), H I 21 cm, CO, and Hα observations. In the diffuse atomic interstellar medium (ISM), we derive the GDR as the slope of the dust-gas relation and find GDRs of 380 −130 +250 ± 3 in the LMC, and 1200 −420 +1600 ± 120 in the SMC, not including helium. The atomic-to-molecular transition is located at dust surface densities of 0.05 M ☉ pc –2 in the LMC and 0.03 M ☉ pc –2 in the SMC, corresponding to A V ∼ 0.4 and 0.2, respectively. We investigate the range of CO-to-H 2 conversion factor to best account for all the molecular gas in the beam of the observations, and find upper limits on X CO to be 6 × 10 20 cm –2 K –1 km –1 s in the LMC (Z = 0.5 Z ☉ ) at 15 pc resolution, and 4 × 10 21 cm –2 K –1 km –1 s in the SMC (Z = 0.2 Z ☉ ) at 45 pc resolution. In the LMC, the slope of the dust-gas relation in the dense ISM is lower than in the diffuse ISM by a factor ∼2, even after accounting for the effects of CO-dark H 2 in the translucent envelopes of molecular clouds. Coagulation of dust grains and the subsequent dust emissivity increase in molecular clouds, and/or accretion of gas-phase metals onto dust grains, and the subsequent dust abundance (dust-to-gas ratio) increase in molecular clouds could explain the observations. In the SMC, variations in the dust-gas slope caused by coagulation or accretion are degenerate with the effects of CO-dark H 2 . Within the expected 5-20 times Galactic X CO range, the dust-gas slope can be either constant or decrease by a factor of several across ISM phases. Further modeling and observations are required to break the degeneracy between dust grain coagulation, accretion, and CO-dark H 2
Energy Technology Data Exchange (ETDEWEB)
Roman-Duval, Julia; Gordon, Karl D.; Meixner, Margaret [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bot, Caroline [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' université, F-67000 Strasbourg (France); Bolatto, Alberto; Jameson, Katherine [Department of Astronomy, Lab for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Hughes, Annie; Hony, Sacha [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Wong, Tony [University of Illinois at Urbana-Champaign, 1002 W. Green St., Urbana, IL 61801 (United States); Babler, Brian [Department of Astronomy, University of Wisconsin, 475 North Charter St., Madison, WI 53706 (United States); Bernard, Jean-Philippe [CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Clayton, Geoffrey C. [Louisiana State University, Department of Physics and Astronomy, 233-A Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001 (United States); Fukui, Yasuo [Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Galametz, Maud [European Southern Observatory, Karl-Schwarzschild-Str 2, D-85748 Garching (Germany); Galliano, Frederic; Lebouteiller, Vianney; Lee, Min-Young [CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Glover, Simon [Zentrum für Astronomie, Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle Strasse 2, D-69120 Heidelberg (Germany); Israel, Frank [Sterrewacht Leiden, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Li, Aigen, E-mail: duval@stsci.edu [314 Physics Building, Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); and others
2014-12-20
The spatial variations of the gas-to-dust ratio (GDR) provide constraints on the chemical evolution and lifecycle of dust in galaxies. We examine the relation between dust and gas at 10-50 pc resolution in the Large and Small Magellanic Clouds (LMC and SMC) based on Herschel far-infrared (FIR), H I 21 cm, CO, and Hα observations. In the diffuse atomic interstellar medium (ISM), we derive the GDR as the slope of the dust-gas relation and find GDRs of 380{sub −130}{sup +250} ± 3 in the LMC, and 1200{sub −420}{sup +1600} ± 120 in the SMC, not including helium. The atomic-to-molecular transition is located at dust surface densities of 0.05 M {sub ☉} pc{sup –2} in the LMC and 0.03 M {sub ☉} pc{sup –2} in the SMC, corresponding to A {sub V} ∼ 0.4 and 0.2, respectively. We investigate the range of CO-to-H{sub 2} conversion factor to best account for all the molecular gas in the beam of the observations, and find upper limits on X {sub CO} to be 6 × 10{sup 20} cm{sup –2} K{sup –1} km{sup –1} s in the LMC (Z = 0.5 Z {sub ☉}) at 15 pc resolution, and 4 × 10{sup 21} cm{sup –2} K{sup –1} km{sup –1} s in the SMC (Z = 0.2 Z {sub ☉}) at 45 pc resolution. In the LMC, the slope of the dust-gas relation in the dense ISM is lower than in the diffuse ISM by a factor ∼2, even after accounting for the effects of CO-dark H{sub 2} in the translucent envelopes of molecular clouds. Coagulation of dust grains and the subsequent dust emissivity increase in molecular clouds, and/or accretion of gas-phase metals onto dust grains, and the subsequent dust abundance (dust-to-gas ratio) increase in molecular clouds could explain the observations. In the SMC, variations in the dust-gas slope caused by coagulation or accretion are degenerate with the effects of CO-dark H{sub 2}. Within the expected 5-20 times Galactic X {sub CO} range, the dust-gas slope can be either constant or decrease by a factor of several across ISM phases. Further modeling
Shibata, Masaru
2016-01-01
This book is composed of two parts: First part describes basics in numerical relativity, that is, the formulations and methods for a solution of Einstein's equation and general relativistic matter field equations. This part will be helpful for beginners of numerical relativity who would like to understand the content of numerical relativity and its background. The second part focuses on the application of numerical relativity. A wide variety of scientific numerical results are introduced focusing in particular on the merger of binary neutron stars and black holes.
International Nuclear Information System (INIS)
Dupuis, Marie-Claude; Farin, Sebastien; Comte, Annabelle; Armand, Gilles; Crusset, Didier; Landais, Patrick; Lebon, Patrick; Plas, Frederic; Schumacher, Stephan; Bertrand, Domitille; Seghers, Elodie; Muzerelle, Sophie
2012-12-01
Within the frame of the public debate organized about the project of creation of a deep reversible disposal for radioactive wastes in Meuse/Haute-Marne, this publication proposes an overview of researches performed since 1991 when the ANDRA was commissioned to study the feasibility of such a disposal for the most radioactive French wastes. This publication deals with the different themes studied by the ANDRA and how, with which means and tools they have been and are addressed. More precisely, it also describes and comments how the geological medium is a guarantee for the storage safety, how waste behaviour is studied in detail, how the storage behaviour must be considered as a whole, how numerical simulation is an essential tool for experimentations, how an underground laboratory allows an as real as possible experimentation of deep storage, how the environment about Cigeo will be controlled and surveyed during at least 100 years, and how researches are performed through numerous international collaborations
Energy Technology Data Exchange (ETDEWEB)
Talukdar, Prabal [Department of Mechanical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Osanyintola, Olalekan F. [XXL Engineering Ltd., 101-807 Manning Road NE, Calgary, AB (Canada); Olutimayin, Stephen O.; Simonson, Carey J. [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK (Canada)
2007-12-15
This paper presents the experimental results on spruce plywood and cellulose insulation using the transient moisture transfer (TMT) facility presented in Part I [P. Talukdar, S.O. Olutmayin, O.F. Osanyintola, C.J. Simonson, An experimental data set for benchmarking 1-D, transient heat and moisture transfer models of hygroscopic building materials-Part-I: experimental facility and property data, Int. J. Heat Mass Transfer, in press, doi:10.1016/j.ijheatmasstransfer.2007.03.026] of this paper. The temperature, relative humidity and moisture accumulation distributions within both materials are presented following different and repeated step changes in air humidity and different airflow Reynolds numbers above the materials. The experimental data are compared with numerical data, numerical sensitivity studies and analytical solutions to increase the confidence in the experimental data set. (author)
International Nuclear Information System (INIS)
Kuipers, J.W.; Thorpe, R.W.
1979-01-01
Problems of numeric data are examined as these relate to the question of possible steps toward implementation of an integrated national information system for DOE. It is proposed that DOE make policy and organization changes in order to centralize and upgrade information management as a particular responsibility for the oversight of DOE-wide information requirements. Eight points to be emphasized in such a program are set forth
Gas dynamics of H II regions. II. Two-dimensional axisymmetric calculations
International Nuclear Information System (INIS)
Bodenheimer, P.; Tenorio-Tagle, G.; Yorke, H.W.
1979-01-01
The evolution of H II regions is calculated with a two-dimensional hydrodynamic numerical procedure under the assumption that the exciting star is born within a cool molecular cloud whose density is about 10 3 particles cm -3 . As the ionization of the cloud's edge is completed, a large pressure gradient is set up and ionized cloud material expands into the ionized low-density (1 particle cm -3 ) intercloud medium, with velocities larger than 30 km s -1 .The calculations are made under the simplifying assumptions that (i) within the H II region, ionization equilibrium holds at all times, (ii) the ionization front is a discontinuity, thus its detailed structure is not calculated, (iii) the temperature of each region (H II region, neutral cloud, and intercloud medium) is constant in time, (iv) all ionizing photons come radially from the exciting star. Four cases are calculated and compared with observations: (1) the edge of the cloud is overrun by a supersonic ionization front, (2) the initial Stroemgren sphere surrounding the star lies deep inside the cloud, thus the cloud's edge is ionized by a subsonic ionization front, (3) the ionization front breaks through two opposite faces of the same cloud simultaneously, (4) the flow encounters an isolated globule of density 10 3 particles cm -3 shortly after emerging from the molecular cloud.The phenomena here considered show how evolving H II regions are an important input of kinetic energy to the interstellar medium
Siegler, Robert S.; Braithwaite, David W.
2016-01-01
In this review, we attempt to integrate two crucial aspects of numerical development: learning the magnitudes of individual numbers and learning arithmetic. Numerical magnitude development involves gaining increasingly precise knowledge of increasing ranges and types of numbers: from non-symbolic to small symbolic numbers, from smaller to larger…
Bright, William
In most languages encountered by linguists, the numerals, considered as a paradigmatic set, constitute a morpho-syntactic problem of only moderate complexity. The Indo-Aryan language family of North India, however, presents a curious contrast. The relatively regular numeral system of Sanskrit, as it has developed historically into the modern…
Rao, G Shanker
2006-01-01
About the Book: This book provides an introduction to Numerical Analysis for the students of Mathematics and Engineering. The book is designed in accordance with the common core syllabus of Numerical Analysis of Universities of Andhra Pradesh and also the syllabus prescribed in most of the Indian Universities. Salient features: Approximate and Numerical Solutions of Algebraic and Transcendental Equation Interpolation of Functions Numerical Differentiation and Integration and Numerical Solution of Ordinary Differential Equations The last three chapters deal with Curve Fitting, Eigen Values and Eigen Vectors of a Matrix and Regression Analysis. Each chapter is supplemented with a number of worked-out examples as well as number of problems to be solved by the students. This would help in the better understanding of the subject. Contents: Errors Solution of Algebraic and Transcendental Equations Finite Differences Interpolation with Equal Intervals Interpolation with Unequal Int...
Energy Technology Data Exchange (ETDEWEB)
Tweed, Dylan; Yang, Xiaohu; Li, Shijie; Jing, Y. P. [Center for Astronomy and Astrophysics, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Huiyuan [Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Cui, Weiguang [Departamento de Física Teórica, Módulo 15, Facultad de Ciencias, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Zhang, Youcai [Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China); Mo, H. J., E-mail: dtweed@sjtu.edu.cn [Department of Astronomy, University of Massachusetts, Amherst MA, 01003-9305 (United States)
2017-05-20
The ELUCID project aims to build a series of realistic cosmological simulations that reproduce the spatial and mass distributions of the galaxies as observed in the Sloan Digital Sky Survey. This requires powerful reconstruction techniques to create constrained initial conditions (ICs). We test the reconstruction method by applying it to several N -body simulations. We use two medium-resolution simulations, which each produced three additional constrained N -body simulations. We compare the resulting friend-of-friend catalogs by using the particle indexes as tracers, and quantify the quality of the reconstruction by varying the main smoothing parameter. The cross-identification method we use proves to be efficient, and the results suggest that the most massive reconstructed halos are effectively traced from the same Lagrangian regions in the ICs. A preliminary time-dependence analysis indicates that high-mass-end halos converge only at a redshift close to the reconstruction redshift. This suggests that, for earlier snapshots, only collections of progenitors may be effectively cross-identified.
Directory of Open Access Journals (Sweden)
Ling Min Zhang
2002-12-01
Full Text Available The authors carried out isoenzyme characterization and genotype comparison studies for Phlebotomus chinensis and Phlebotomus sichuanensis imagoes collected from their holotype/paratype original localities: West Mountain, West Suburb, Beijing and Lixian County, Sichuan Province. Numerical analysis was carried out and the dendrogram of four species of Adlerius was drawn up according to morphological characteristics of these four species. The results showed that P. chinensis and P. sichuanensis can be identified enzymatically in PGM and the MDH-2 allele also differs in P. chinensis from Beijing and. P. sichuanensis. The dendrogram of four Adlerius species showed that P. fengi and P. longiductus are very similar and they clustered first, then P. sichuanensis combine with them to form a combined group. P. chinensis is a separate group from other three. These two groups come to combine at last. Above results have proved that P. sichuanensis is an isolate species instead of a so-called large type P. chinensis.
Scott, L Ridgway
2011-01-01
Computational science is fundamentally changing how technological questions are addressed. The design of aircraft, automobiles, and even racing sailboats is now done by computational simulation. The mathematical foundation of this new approach is numerical analysis, which studies algorithms for computing expressions defined with real numbers. Emphasizing the theory behind the computation, this book provides a rigorous and self-contained introduction to numerical analysis and presents the advanced mathematics that underpin industrial software, including complete details that are missing from most textbooks. Using an inquiry-based learning approach, Numerical Analysis is written in a narrative style, provides historical background, and includes many of the proofs and technical details in exercises. Students will be able to go beyond an elementary understanding of numerical simulation and develop deep insights into the foundations of the subject. They will no longer have to accept the mathematical gaps that ex...
Graphene wire medium: Homogenization and application
DEFF Research Database (Denmark)
Andryieuski, Andrei; Chigrin, Dmitry N.; Lavrinenko, Andrei
2012-01-01
In this contribution we analyze numerically the optical properties of the graphene wire medium, which unit cell consists of a stripe of graphene embedded into dielectric. We propose a simple method for retrieval of the isofrequency contour and effective permittivity tensor. As an example...... of the graphene wire medium application we demonstrate a reconfigurable hyperlens for the terahertz subwavelength imaging capable of resolving two sources with separation λ0/5 in the far-field....
Directory of Open Access Journals (Sweden)
S. Bönisch
2004-02-01
Full Text Available Este trabalho teve por objetivos utilizar krigagem por indicação para espacializar propriedades de solos expressas por atributos numéricos, gerar uma representação acompanhada de medida espacial de incerteza e modelar a propagação de incerteza por procedimentos fuzzy de álgebra de mapas. Foram estudados os atributos: teores de potássio (K e de alumínio (Al trocáveis, saturação por bases (V, soma de bases (S, capacidade de troca catiônica (CTC e teor de areia total (AT, extraídos de 222 perfis pedológicos e de 219 amostras extras, localizados no estado de Santa Catarina. Quando os atributos foram expressos em classes de fertilidade, a incerteza de Al, S e V aumentou e a de K e CTC diminuiu, considerando intervalos de confiança de 95 % de probabilidade. Constatou-se que um maior número de dados numéricos de K, S e V levou a uma maior incerteza na inferência espacial, enquanto o maior número de dados numéricos de AT e CTC diminuiu o grau de incerteza. A incerteza diminuiu quando diferentes representações numéricas foram integradas.The objectives of this study were to use kriging indicators to generate a representation of soil properties expressed by numeric attributes, to assess the uncertainty in estimates, and to model the uncertainty propagation generated by the fuzzy procedures of map algebra. The studied attributes were exchangeable potassium (K and aluminum (Al contents, sum of bases (SB, cationic exchange capacity (CEC, base saturation (V, and total sand content (TST, extracted from 222 pedologic profiles and 219 extra samples, located in Santa Catarina State, Brazil. When the attributes were expressed in fertility classes, the uncertainty of Al, SB, and V increased while the uncertainty of K and CEC decreased, for intervals of confidence of 95% probability. A larger number of numeric data for K, SB, and V provided a larger uncertainty for space inference, while the uncertainty degree decreased for the largest number
Directory of Open Access Journals (Sweden)
Jun Li
2015-02-01
Full Text Available In this work, a macroscopic non-linear constitutive model accounting for damage, inelastic strain and unilateral behavior is proposed for the 2D plain-woven C/SiC composite. A set of scalar damage variables and a new thermodynamic potential expression are introduced in the framework of continuum damage mechanics. In the deduced constitutive equations, the material’s progressive damage deactivation behavior during the compression loading is described by a continuous function, and different deactivation rates under uniaxial and biaxial compression loadings are also considered. In damage evolution laws, the coupling effect among the damage modes and impediment effect of compression stress on the development of shear damage in different plane stress states are taken into account. Besides, the general plasticity theory is applied to describing the evolution of inelastic strain in tension and/or shear stress state. The Tsai–Wu failure criterion is adopted for strength analysis. Additionally, the material model is implemented as a user-defined material subroutine (UMAT and linked to the ABAQUS finite element software, and its performance is demonstrated through several numerical examples.
Raikova, ROSITSA
2000-01-01
Using the method of Lagrange multipliers an analytical solution of the optimization problem formulated for a two-dimensional, 3DOF model of the human upper limb has been described in Part I of this investigation. The objective criterion used is the following: [formula: see text], where F(i) -s are the muscle forces modelled and c(i) -s are unknown weight factors. This study is devoted to the numerical experiments performed in order to investigate which sets of the weight factors may predict physiologically reasonable muscle forces and joint reactions. A sensitivity analysis is also presented. The influence of: the gravity forces, different external loads applied to the hand, changes of the weight factors and of joint angle on the optimal solution is studied. A general conclusion may be drawn: using the above mentioned objective criterion, practically all motor tasks performed by the human upper limb may be described if the c(i) -s are properly chosen. These weight factors generally depend on the joint moments and must be different (their magnitudes as well as their signs) for agonistic muscles and for their antagonists.
Brezinski, C
2012-01-01
Numerical analysis has witnessed many significant developments in the 20th century. This book brings together 16 papers dealing with historical developments, survey papers and papers on recent trends in selected areas of numerical analysis, such as: approximation and interpolation, solution of linear systems and eigenvalue problems, iterative methods, quadrature rules, solution of ordinary-, partial- and integral equations. The papers are reprinted from the 7-volume project of the Journal of Computational and Applied Mathematics on '/homepage/sac/cam/na2000/index.html<
A Heterogeneous Medium Analytical Benchmark
International Nuclear Information System (INIS)
Ganapol, B.D.
1999-01-01
A benchmark, called benchmark BLUE, has been developed for one-group neutral particle (neutron or photon) transport in a one-dimensional sub-critical heterogeneous plane parallel medium with surface illumination. General anisotropic scattering is accommodated through the Green's Function Method (GFM). Numerical Fourier transform inversion is used to generate the required Green's functions which are kernels to coupled integral equations that give the exiting angular fluxes. The interior scalar flux is then obtained through quadrature. A compound iterative procedure for quadrature order and slab surface source convergence provides highly accurate benchmark qualities (4- to 5- places of accuracy) results
International Nuclear Information System (INIS)
Lovelace, Geoffrey; Chen Yanbei; Cohen, Michael; Kaplan, Jeffrey D.; Keppel, Drew; Matthews, Keith D.; Nichols, David A.; Scheel, Mark A.; Sperhake, Ulrich
2010-01-01
Research on extracting science from binary-black-hole (BBH) simulations has often adopted a 'scattering matrix' perspective: given the binary's initial parameters, what are the final hole's parameters and the emitted gravitational waveform? In contrast, we are using BBH simulations to explore the nonlinear dynamics of curved spacetime. Focusing on the head-on plunge, merger, and ringdown of a BBH with transverse, antiparallel spins, we explore numerically the momentum flow between the holes and the surrounding spacetime. We use the Landau-Lifshitz field-theory-in-flat-spacetime formulation of general relativity to define and compute the density of field energy and field momentum outside horizons and the energy and momentum contained within horizons, and we define the effective velocity of each apparent and event horizon as the ratio of its enclosed momentum to its enclosed mass-energy. We find surprisingly good agreement between the horizons' effective and coordinate velocities. During the plunge, the holes experience a frame-dragging-induced acceleration orthogonal to the plane of their spins and their infall ('downward'), and they reach downward speeds of order 1000 km/s. When the common apparent horizon forms (and when the event horizons merge and their merged neck expands), the horizon swallows upward field momentum that resided between the holes, causing the merged hole to accelerate in the opposite ('upward') direction. As the merged hole and the field energy and momentum settle down, a pulsational burst of gravitational waves is emitted, and the merged hole has a final effective velocity of about 20 km/s upward, which agrees with the recoil velocity obtained by measuring the linear momentum carried to infinity by the emitted gravitational radiation. To investigate the gauge dependence of our results, we compare generalized harmonic and Baumgarte-Shapiro-Shibata-Nakamura-moving-puncture evolutions of physically similar initial data; although the generalized
Baker, John G.
2009-01-01
Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.
Nakamura, T
1993-01-01
In GR13 we heard many reports on recent. progress as well as future plans of detection of gravitational waves. According to these reports (see the report of the workshop on the detection of gravitational waves by Paik in this volume), it is highly probable that the sensitivity of detectors such as laser interferometers and ultra low temperature resonant bars will reach the level of h ~ 10—21 by 1998. in this level we may expect the detection of the gravitational waves from astrophysical sources such as coalescing binary neutron stars once a year or so. Therefore the progress in numerical relativity is urgently required to predict the wave pattern and amplitude of the gravitational waves from realistic astrophysical sources. The time left for numerical relativists is only six years or so although there are so many difﬁculties in principle as well as in practice.
Energy Technology Data Exchange (ETDEWEB)
Dyogtyev, Oleksandr
2017-03-02
The thesis dealing with the numerical analysis of the bearing capacity of complex rock mechanical underground systems with filigree structures in the presence of imponderables covers the following issues: status of science and technology, concept for the performance of numerical studies on the bearing capacity of large-volume underground systems, application example salt cavern ASSE II - application of the developed concept/development of numerical tools for the overall system/application of the global model to the given questions/realization of the modification potential.
1988-01-01
TASK AREA & WORK UNIT NUMBERS Dipartimento di Matematica -G.--iattelnuoz .’ Universita di Roma "La Sapienze" rlnlRr% Pnmaq (Tt-al’g) I$. CONTROLLING...guaranteed. 3. Adminisrtrative actions The following investigators are working on the contract: (i) Francesco Zirilli Dipartimento di Matematica "G...Castelnuovo" Universiti di Roma "La Sapienza" 00185 Romna (Italy) (ii) Filippo Aluffi-Pentini Dipartimento di Matematica Universiti di Barn 80125 Bari (Italy
Medium-range fire weather forecasts
J.O. Roads; K. Ueyoshi; S.C. Chen; J. Alpert; F. Fujioka
1991-01-01
The forecast skill of theNational Meteorological Center's medium range forecast (MRF) numerical forecasts of fire weather variables is assessed for the period June 1,1988 to May 31,1990. Near-surface virtual temperature, relative humidity, wind speed and a derived fire weather index (FWI) are forecast well by the MRF model. However, forecast relative humidity has...
Indian Academy of Sciences (India)
medium properties of hadrons. I discuss the relevant symmetries of QCD and how they might affect the observed hadron properties. I then discuss at length the observable consequences of in-medium changes of hadronic properties in reactions with ...
Kuipers, G.; Ritzer, G.
2012-01-01
"The medium is the message" is a phrase coined by Canadian media theorist Marshall McLuhan (1911-1980), in his book Understanding Media: The Extensions of Man (1964). In this book, McLuhan examines the impact of media on societies and human relations, arguing for the primacy of the medium -
Directory of Open Access Journals (Sweden)
D. L. Guerra
2008-09-01
Full Text Available Amostras de caulinita oriundas da região do Rio Capim, estado do Pará, Brasil, foram intercaladas com dimetilsulfóxido - DMSO. As amostras de caulinita naturais e intercaladas foram utilizadas em processo de adsorção com Zn(II em meio aquoso em pH 5,0 e temperatura controlada de 298 ± 1K. As propriedades físico-químicas das amostras de caulinita foram otimizadas pelo processo de intercalação, como: área superficial de 14,74 para 91,72 m²g-1 (A1 e diâmetro de poros de 2,79 para 10,72 nm (A1. A análise dos resultados experimentais de adsorção foi feita pelos modelos de Langmuir, Temkin e Freundlich. O modelo de Langmuir apresentou melhor aproximação com os dados experimentais de adsorção. Estes resultados foram bem representados pelo modelo cinético de segunda ordem de Lagergren, com a taxa constante K2 no intervalo de 4,76x10-3 a 11,81x10-3 g(mmol.min-1 (A2. O processo de adsorção foi considerado rápido alcançando o equilíbrio em 180 min.The kaolinite clay samples from Capim River region, Pará state, Brazil, were intercalated with dimethylsulfoxide - DMSO. The natural and intercalated kaolinite were used in adsorption process with Zn(II in aqueous medium at pH 5.0 and controlled temperature of 298 ± 1K. The physical-chemical properties of kaolinite samples were optimized for the intercalation process, such as: specific area of 14.74 to 91.72 m²g-1 (A1 and pore diameter of 2.79 to 10.72 nm (A1. The adsorption experimental results were analyzed for Langmuir, Temkin and Freundlich models, the Langmuir model has been presented best approximation with experimental adsorption isotherms data. These results best fitted the second order kinetic of Lagergren model with rate constant K2, in the range of 4.76x10-3 to 11.81x10-3 g(mmol.min-1 (A2. The adsorption process was very fast and equilibrium was approached within 180 min.
Numerical derivation in optimization
International Nuclear Information System (INIS)
Abadie, J.; Salhi, Y.
1988-01-01
Newton's method for function minimization possesses an outstanding property. Its final quadratic convergence under very weak hypothesis, but also some drawbacks, among which (i) the possibility of non convergence when starting far from the solution sought and (ii) the necessity of computing (and then programming) the first and second partial derivatives. We show in this paper how to avoid both difficulties, assuming however that the first partial derivatives are computed by exact formulae. The second partial derivatives are computed by central differences of first derivatives. The difference step h is calculated so as to establish a trade-off between accuracy and computation speed. Encouraging numerical experiments support the proposed method [fr
International Nuclear Information System (INIS)
Crutcher, R.M.; and Radio Astronomy Laboratory, University of California, Berkeley)
1982-01-01
Analysis of the velocities of optical interstellar lines shows that the Sun is immersed in a coherently moving local interstellar medium whose velocity vector agrees with that of the interstellar wind observed through backscatter of solar H Lyα and He lambda584 photons. The local interstellar medium consists of both cool clouds and warm intercloud medium gas, has a mass of perhaps approx.30 M/sub sun/, does not have severe depletion of trace elements from the gas phase, and appears to be material which has been shocked and accelerated by stellar winds and supernovae associated with the Sco-Oph OB association
Jacques, Ian
1987-01-01
This book is primarily intended for undergraduates in mathematics, the physical sciences and engineering. It introduces students to most of the techniques forming the core component of courses in numerical analysis. The text is divided into eight chapters which are largely self-contained. However, with a subject as intricately woven as mathematics, there is inevitably some interdependence between them. The level of difficulty varies and, although emphasis is firmly placed on the methods themselves rather than their analysis, we have not hesitated to include theoretical material when we consider it to be sufficiently interesting. However, it should be possible to omit those parts that do seem daunting while still being able to follow the worked examples and to tackle the exercises accompanying each section. Familiarity with the basic results of analysis and linear algebra is assumed since these are normally taught in first courses on mathematical methods. For reference purposes a list of theorems used in the t...
National Aeronautics and Space Administration — Unstructured HIRENASD mesh: - medium size (16 million nodes, 39 million elements) - for node centered solvers - 31.05.2011 - caution: dimensions in mm
DEFF Research Database (Denmark)
Bjerrum, Peter
2005-01-01
The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program...
DEFF Research Database (Denmark)
Bjerrum, Peter
2005-01-01
The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program......The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program...
Defined medium for Moraxella bovis.
Juni, E; Heym, G A
1986-01-01
A defined medium (medium MB) for Moraxella bovis was formulated. Nineteen strains grew well on medium MB. One strain was auxotrophic for asparagine, and another was auxotrophic for methionine. Strains of M. equi and M. lacunata also grew on medium MB. All strains had an absolute requirement for thiamine and were stimulated by or actually required the other growth factors in the medium.
Numerical simulation on coolant flow and heat transfer in core
International Nuclear Information System (INIS)
Yao Zhaohui; Wang Xuefang; Shen Mengyu
1997-01-01
To simulate the coolant flow and the heat transfer characteristics of a core, a computer code, THAPMA (Thermal Hydraulic Analysis Porous Medium Analysis) has been developed. In THAPMA code, conservation equations are based on a porous-medium formulation, which uses four parameters, i.e, volume porosity, directional surface porosity, distributed resistance, and distributed heat source (sink), to model the effects of fuel rods and other internal solid structures on flow and heat transfer. Because the scheme and the solution are very important in accuracy and speed of calculation, a new difference scheme (WSUC) has been used in the energy equation, and a modified PISO solution method have been employed to simulate the steady/transient states. The code has been proved reliable and can effectively solve the transient state problem by several numerical tests. According to the design of Qinshan NPP-II, the flow and heat transfer phenomena in reactor core have been numerically simulated. The distributions of the velocity and the temperature can provide a theoretical basis for core design and safety analysis
Energy Technology Data Exchange (ETDEWEB)
Corge, Ch. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1969-01-01
Numerical analysis of transmission resonances induced by s wave neutrons in time-of-flight experiments can be achieved in a fairly automatic way on an IBM 7094/II computer. The involved computations are carried out following a four step scheme: 1 - experimental raw data are processed to obtain the resonant transmissions, 2 - values of experimental quantities for each resonance are derived from the above transmissions, 3 - resonance parameters are determined using a least square method to solve the over determined system obtained by equalling theoretical functions to the correspondent experimental values. Four analysis methods are gathered in the same code, 4 - graphical control of the results is performed. (author) [French] L'automatisation, sur ordinateur IBM 7094/II, de l'analyse des resonances induites par les neutrons s dans les experiences de transmission par temps de vol a ete accomplie en la decomposant selon un schema articule en quatre phases: 1 - le traitement des donnees experimentales brutes pour obtenir les transmissions interfero-resonnantes, 2 - la determination des grandeurs d'analyse a partir des transmissions precedentes, 3 - l'analyse proprement dite des resonances dont les parametres sont obtenus par la resolution d'un systeme surabondant. Quatre methodes d'analyse sont groupees en un meme programme, 4 - la procedure de verification graphique. (auteur)
DEFF Research Database (Denmark)
Kacunko, Slavko
and cultural perspective. From 1800 on, the great incentive was to push forward the material-physical and optical-mechanical and especially the media ‘exploitation’ of the mirror. The significance of the mirror as a central meta-medium of the visual emerged in a particularly striking way in the late 1830s....... That ricochets through media theory, theories of art and culture and through cultural historiography. A repository is one thing, a transmitter another: the distinction will act crucially on the quest for appropriate perspectives and classifications of what in terms of disciplines would rather appear...... or as synaesthesia gone mute. It stands in contrast with the mirror, which assumes the status of a medium facility or meta-medium of visual transference, encountering its only medial and operative limitation within the analogue or digital repository media. The present proposal for an artistic and cultural history...
African Journals Online (AJOL)
DR. AMINU
ABSTRACT. The manganese (II), cobalt (II), nickel (II) and copper (II) complexes of N, N' – bis(benzoin)ethylenediiminato have been prepared and characterized by infrared, elemental analysis, conductivity measurements and solubility. The potentiometric, and elemental analyses studies of the complexes revealed 1:1 ...
DEFF Research Database (Denmark)
Bjerrum, Peter
2003-01-01
The present essays is an attempt to dertermine the architecural project of the 21st century in realation to a modern conception of space as the medium of architecture, and of society as its program. This attempt adopts the internal point of view of an architect in describing a modern architectura...
International Nuclear Information System (INIS)
Hricko, J.
1995-01-01
The paper presented deals with behavior of the radon in geological medium and with some results of the radon survey in Bratislava and Kosice regions. 1) The a v has been detected in the holes 0.80 m deep. The density of observations - 3 reference areas (one represents 20 stations) per 1 km 2 . The radon risk maps in 1:25000 and 1:50000 scales have been compiled. The 56.8% of the project area lies in low radon risk, 37.6% in medium radon risk and 5.6% in high radon risk. Follow-up monitoring of the equivalent volume radon activity (EVRA) at the flats, located in the areas with high radon risk of the surface layer, has showed values several times higher than Slovak limits (Marianka, Raca, Vajnory). The evidence that neotectonic is excellent medium for rising up emanation to the subsurface layer, is shown on the map. The tectonic zone of Liscie udolie in Bratislava-Karlova Ves area has been clearly detected by profile radon survey (a v > 50 kBq/m 3 ). 2) At present, northern half of the area of Kosice in question was covered by radon survey. The low and medium radon risks have been observed here, while localities with high radon risk are small in extent. The part of radon risk and soil permeability map from northern Kosice area is shown. (J.K.) 3 figs., 2 refs
CULTIVATION OF LEPTOSPIRAE II.
Stalheim, O. H. V.; Wilson, J. B.
1964-01-01
Stalheim, O. H. V. (University of Wisconsin, Madison), and J. B. Wilson. Cultivation of leptospirae. II. Growth and lysis in synthetic medium. J. Bacteriol. 88:55–59. 1964.—Differences were found in the ability of leptospirae to grow in a synthetic medium; 43 strains, consisting of 16 serotypes, were tested and designated as either type I or type II. Type I leptospirae did not grow; type II grew and could be subcultured. The lytic effect of several lipids was measured with Leptospira pomona and L. canicola as representatives of type I and II leptospirae, respectively. L. pomona organisms were rapidly lysed by the monoolein of the synthetic medium and by other lipids as well; L. canicola cells were consistently more resistant. Although both organisms incorporated similar amounts of label when incubated in the presence of oleic-1-C14 acid, only L. canicola grew in a modified, nonlytic synthetic medium. No differences were found in susceptibility to lysis between virulent and avirulent L. canicola organisms. Mutant type I leptospirae grown in synthetic medium had increased resistance to lysis by surface-active agents; they were poorly agglutinated by antiserum. The role of protein in the growth and antigenicity of type I leptospirae is discussed. PMID:14197906
The accuracy of semi-numerical reionization models in comparison with radiative transfer simulations
Hutter, Anne
2018-03-01
We have developed a modular semi-numerical code that computes the time and spatially dependent ionization of neutral hydrogen (H I), neutral (He I) and singly ionized helium (He II) in the intergalactic medium (IGM). The model accounts for recombinations and provides different descriptions for the photoionization rate that are used to calculate the residual H I fraction in ionized regions. We compare different semi-numerical reionization schemes to a radiative transfer (RT) simulation. We use the RT simulation as a benchmark, and find that the semi-numerical approaches produce similar H II and He II morphologies and power spectra of the H I 21cm signal throughout reionization. As we do not track partial ionization of He II, the extent of the double ionized helium (He III) regions is consistently smaller. In contrast to previous comparison projects, the ionizing emissivity in our semi-numerical scheme is not adjusted to reproduce the redshift evolution of the RT simulation, but directly derived from the RT simulation spectra. Among schemes that identify the ionized regions by the ratio of the number of ionization and absorption events on different spatial smoothing scales, we find those that mark the entire sphere as ionized when the ionization criterion is fulfilled to result in significantly accelerated reionization compared to the RT simulation. Conversely, those that flag only the central cell as ionized yield very similar but slightly delayed redshift evolution of reionization, with up to 20% ionizing photons lost. Despite the overall agreement with the RT simulation, our results suggests that constraining ionizing emissivity sensitive parameters from semi-numerical galaxy formation-reionization models are subject to photon nonconservation.
Numerical relativity beyond astrophysics
Garfinkle, David
2017-01-01
Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.
Numerical relativity beyond astrophysics.
Garfinkle, David
2017-01-01
Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology. (ii) investigations of critical behavior at the threshold of black hole formation in gravitational collapse. (iii) investigations inspired by string theory, in particular analogs of black holes in more than 4 spacetime dimensions and gravitational collapse in spacetimes with a negative cosmological constant.
Numerical simulation support to the ESA/THOR mission
Valentini, F.; Servidio, S.; Perri, S.; Perrone, D.; De Marco, R.; Marcucci, M. F.; Daniele, B.; Bruno, R.; Camporeale, E.
2016-12-01
THOR is a spacecraft concept currently undergoing study phase as acandidate for the next ESA medium size mission M4. THOR has been designedto solve the longstanding physical problems of particle heating andenergization in turbulent plasmas. It will provide high resolutionmeasurements of electromagnetic fields and particle distribution functionswith unprecedented resolution, with the aim of exploring the so-calledkinetic scales. We present the numerical simulation framework which is supporting the THOR mission during the study phase. The THOR teamincludes many scientists developing and running different simulation codes(Eulerian-Vlasov, Particle-In-Cell, Gyrokinetics, Two-fluid, MHD, etc.),addressing the physics of plasma turbulence, shocks, magnetic reconnectionand so on.These numerical codes are being used during the study phase, mainly withthe aim of addressing the following points:(i) to simulate the response of real particle instruments on board THOR, byemploying an electrostatic analyser simulator which mimics the response ofthe CSW, IMS and TEA instruments to the particle velocity distributions ofprotons, alpha particle and electrons, as obtained from kinetic numericalsimulations of plasma turbulence.(ii) to compare multi-spacecraft with single-spacecraft configurations inmeasuring current density, by making use of both numerical models ofsynthetic turbulence and real data from MMS spacecraft.(iii) to investigate the validity of the Taylor hypothesis indifferent configurations of plasma turbulence
International Nuclear Information System (INIS)
Anon.
1980-01-01
One of the basic challenges of medium-energy physics is the development of a clear picure of the manner in which pions propagate in nuclear matter. Since the pion is a basic quantum of the nuclear force, understanding its propagation in nuclei contributes to our understanding of the basic nature of nuclear forces. Key to such understanding is a comprehensive and precise experimental description of pion interactions both with complex nuclei and few nucleon systems. This is a major objective of the ANL effort in medium-energy physics. Experiments are carried out as a part of a comprehensive nuclear program, and, because of this perspective, the pion studies are expected to give new insights into the nature of nuclear forces. At the present time, almost all experimental activity is concentrated on measurements using various pion beams of the Los Alamos Meson Physics Facility
Liquid chromatographic extraction medium
Horwitz, E. Philip; Dietz, Mark L.
1994-01-01
A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.
International Nuclear Information System (INIS)
Leupold, Stefan
2005-01-01
QCD, the theory of the strong interaction, has a non-trivial vacuum structure. One way to characterize this structure is by means of non-vanishing matrix elements of quark or gluon operators, the condensates. In hot and/or dense enough strongly interacting media, QCD is subject to phase transitions or rapid crossovers. Consequently, the condensates typically change with density and temperature. An exciting aspect of hadron physics is the question how these changes affect the properties of hadrons which are put in a strongly interacting environment. Here vector mesons deserve special attention as they couple directly to (virtual) photons. The latter can decay into dileptons which leave the strongly interacting system untouched. Via that process information about possible in-medium modifications of the vector mesons can be carried to the detectors. With the ω-meson as an example I will review our current understanding of the connections between in-medium changes of condensates and the in-medium changes of the properties of hadrons. (author)
Energy Technology Data Exchange (ETDEWEB)
Erdman, W.; Behnke, M.
2005-11-01
Kilowatt ratings of modern wind turbines have progressed rapidly from 50 kW to 1,800 kW over the past 25 years, with 3.0- to 7.5-MW turbines expected in the next 5 years. The premise of this study is simple: The rapid growth of wind turbine power ratings and the corresponding growth in turbine electrical generation systems and associated controls are quickly making low-voltage (LV) electrical design approaches cost-ineffective. This report provides design detail and compares the cost of energy (COE) between commercial LV-class wind power machines and emerging medium-voltage (MV)-class multi-megawatt wind technology. The key finding is that a 2.5% reduction in the COE can be achieved by moving from LV to MV systems. This is a conservative estimate, with a 3% to 3.5% reduction believed to be attainable once purchase orders to support a 250-turbine/year production level are placed. This evaluation considers capital costs as well as installation, maintenance, and training requirements for wind turbine maintenance personnel. Subsystems investigated include the generator, pendant cables, variable-speed converter, and padmount transformer with switchgear. Both current-source and voltage-source converter/inverter MV topologies are compared against their low-voltage, voltage-source counterparts at the 3.0-, 5.0-, and 7.5-MW levels.
Numerical methods in astrophysics an introduction
Bodenheimer, Peter; Rozyczka, Michal; Plewa, Tomasz; Yorke, Harold W; Yorke, Harold W
2006-01-01
Basic Equations The Boltzmann Equation Conservation Laws of Hydrodynamics The Validity of the Continuous Medium Approximation Eulerian and Lagrangian Formulation of Hydrodynamics Viscosity and Navier-Stokes Equations Radiation Transfer Conducting and Magnetized Media Numerical Approximations to Partial Differential Equations Numerical Modeling with Finite-Difference Equations Difference Quotient Discrete Representation of Variables, Functions, and Derivatives Stability of Finite-Difference Methods Physical Meaning of Stability Criterion A Useful Implicit Scheme Diffusion
DEFF Research Database (Denmark)
Kacunko, Slavko
to human talent, came the millennia of untiring labours and the play of art and science and thought. The human love-affair with reflection (to cite Mark Pendergast’s subtitle - Mirror/Mirror: A History of the Human Love Affair with Reflection [New York 2003]) has always been a platonic one and I hold...... and cultural perspective. From 1800 on, the great incentive was to push forward the material-physical and optical-mechanical and especially the media ‘exploitation’ of the mirror. The significance of the mirror as a central meta-medium of the visual emerged in a particularly striking way in the late 1830s...
DENSE MEDIUM CYCLONE OPTIMIZATON
Energy Technology Data Exchange (ETDEWEB)
Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood
2005-06-30
Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.
FORMATION OF BINARY COMPLEXES OF Co(II), Ni(II) AND Cu(II ...
African Journals Online (AJOL)
Preferred Customer
INTRODUCTION. Cobalt(II), nickel(II) and copper(II) are associated with several enzymes [1, 2] and any variation ... amounts (10 mg/day), at higher levels of exposure it shows mutagenic and carcinogenic effects. [13]. Minot and ... Nickel plays numerous roles in the biology of microorganisms and plants [15, 16]. Urease, an.
Time's arrow: A numerical experiment
Fowles, G. Richard
1994-04-01
The dependence of time's arrow on initial conditions is illustrated by a numerical example in which plane waves produced by an initial pressure pulse are followed as they are multiply reflected at internal interfaces of a layered medium. Wave interactions at interfaces are shown to be analogous to the retarded and advanced waves of point sources. The model is linear and the calculation is exact and demonstrably time reversible; nevertheless the results show most of the features expected of a macroscopically irreversible system, including the approach to the Maxwell-Boltzmann distribution, ergodicity, and concomitant entropy increase.
Scattering by closely spaced infinite cylinders in an absorbing medium
Directory of Open Access Journals (Sweden)
S.-C. Lee
2011-09-01
Full Text Available Scattering by closely spaced parallel infinite cylinders in an absorbing medium is considered in this paper. The source wave is arbitrarily polarized and propagates in a general direction at the cylinders. The formulation utilizes the Hertz potential approach, and the scattering cross section and intensity distribution in the far-field are developed. Numerical results are presented to illustrate the influence of the absorbing medium on the scattering properties of two configurations of closely-spaced cylinders.
Quenching of g/sub A/ in the nuclear medium
Energy Technology Data Exchange (ETDEWEB)
Parthasarathy, R.; Pasupathy, J.
1988-05-01
The numerical values of g/sub A/ are evaluated using quantum-chromodynamic sum rules. The nuclear medium effects are taken into account by modifying the chiral symmetry breaking correlation,
National Oceanic and Atmospheric Administration, Department of Commerce — Oceanographic station and other data from meteorological sensors, CTD, and bottle casts from numerous platforms from 1955-05-04 to 1986-09-24. Data were processed by...
Numerical Implementation and Computer Simulation of Tracer ...
African Journals Online (AJOL)
Numerical Implementation and Computer Simulation of Tracer Experiments in a Physical Aquifer Model. ... African Research Review ... A sensitivity analysis showed that the time required for complete source depletion, was most dependent on the source definition and the hydraulic conductivity K of the porous medium.
The Abundance of Mg in the Interstellar Medium
Fitzpatrick, Edward L.
1997-06-01
An empirical determination of the f-values of the far-UV Mg II λλ1239, 1240 lines is reported. The strong near-UV Mg II λλ2796, 2803 lines are generally highly saturated along most interstellar sight lines outside the local interstellar medium (ISM) and usually yield extremely uncertain estimates of Mg+ column densities in interstellar gas. Since Mg+ is the dominant form of Mg in the neutral ISM, and since Mg is expected to be a significant constituent of interstellar dust grains, the far-UV lines are critical for assessing the role of this important element in the ISM. This study consists of complete component analyses of the absorption along the lines of sight toward HD 93521 in the Galactic halo and ξ Persei and ζ Ophiuchi in the Galactic disk, including all four UV Mg+ lines and numerous other transitions. The three analyses yield consistent determinations of the λλ1239, 1240 f-values, with weighted means of (6.4 +/- 0.4) × 10-4 and (3.2 +/- 0.2) × 10-4, respectively. These results are a factor of ~2.4 larger than a commonly used theoretical estimate, and a factor of ~2 smaller than a recently suggested empirical revision. The effects of this result on gas- and dust-phase abundance measurements of Mg are discussed. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract NAS5-2655. This Letter is dedicated to the memory of Professor Lyman Spitzer Jr. He was a great guy.
International Nuclear Information System (INIS)
Das, Devlina; Charumathi, D.; Das, Nilanjana
2011-01-01
Single and binary effects of dye Basic Violet 3 and heavy metals, 'namely', Pb(II) and Cd(II), were investigated for their role in dye and heavy metal bioaccumulation by Candida tropicalis that was grown in a sugarcane bagasse extract medium containing 8 g/L, 16 g/L or 24 g/L of sugar. The optimum pH was found to be 4.0 in the single system and 5.0 in the binary system. A central composite design was successfully used to analyse the experimental results. Four numerical correlations that were fitted to a second order quadratic equation were used to estimate optimum combinations predicted by response surface methodology. In the dye-Pb(II) binary system, C. tropicalis was capable of bioaccumulating 49.5% of the dye and 49.6% of the Pb(II), in comparison to 15.9% of the dye and 55.5% of the Cd(II) in the dye-Cd(II) binary system. In these two systems, the pollutants were dispersed at minimum working concentration levels. Competitive inhibition was observed in both the single and binary systems, which was suggested by an increase in the saturation constant, K s , and a simultaneous decrease in the specific growth rate that was calculated from Lineweaver-Burk plots. Atomic force microscopy images demonstrated changes in yeast cell morphology by exposure to these contaminants in the dye-Pb(II) binary system grown in a bioaccumulation medium.
Isogeometric frictionless contact analysis with the third medium method
Kruse, R.; Nguyen-Thanh, N.; Wriggers, P.; De Lorenzis, L.
2018-01-01
This paper presents an isogeometric formulation for frictionless contact between deformable bodies, based on the recently proposed concept of the third medium. This concept relies on continuum formulations not only for the contacting bodies but also for a fictitious intermediate medium in which the bodies can move and interact. Key to the formulation is a suitable definition of the constitutive behavior of the third medium. In this work, based on a number of numerical tests, the role of the material parameters of the third medium is systematically assessed. We also assess the rate of spatial convergence for higher-order discretizations, stemming from the regularization of the non-smooth contact problem inherent to the third medium approach. Finally, problems with self contact are considered and turn out to be an attractive application of the method.
Adiabatic supernova expansion into the circumstellar medium
International Nuclear Information System (INIS)
Band, D.L.; Liang, E.P.
1987-01-01
We perform one dimensional numerical simulations with a Lagrangian hydrodynamics code of the adiabatic expansion of a supernova into the surrounding medium. The early expansion follows Chevalier's analytic self-similar solution until the reverse shock reaches the ejecta core. We follow the expansion as it evolves towards the adiabatic blast wave phase. Some memory of the earlier phases of expansion is retained in the interior even when the outer regions expand as a blast wave. We find the results are sensitive to the initial configuration of the ejecta and to the placement of gridpoints. 6 refs., 2 figs
Numerical Optimization in Microfluidics
DEFF Research Database (Denmark)
Jensen, Kristian Ejlebjærg
2017-01-01
Numerical modelling can illuminate the working mechanism and limitations of microfluidic devices. Such insights are useful in their own right, but one can take advantage of numerical modelling in a systematic way using numerical optimization. In this chapter we will discuss when and how numerical...... optimization is best used....
Directory of Open Access Journals (Sweden)
Ming Chih Chiu
2008-01-01
Full Text Available The aim of the present work is to investigate the effects of blending and chemical interesterification reactions on the softening and melting behavior of chicken fat, its stearin and medium chain triacylglycerols, and blends thereof in various ratios. Chemical interesterification is a promising alternative to the current processes of modifying the physical properties of fats. In the experimental design 7 samples corresponding to 7 different blend proportions were used. The results were represented in triangular diagrams. The addition of stearin influenced the softening and melting points. The mixture response surface methodology proved to be an extremely useful tool for the optimization of the fat mixtures.
Directory of Open Access Journals (Sweden)
José Mordoh
2017-05-01
Full Text Available The irradiated, allogeneic, cellular CSF-470 vaccine plus Bacillus Calmette–Guerin (BCG and recombinant human granulocyte macrophage-colony stimulating factor (rhGM-CSF is being tested against medium-dose IFN-α2b in stages IIB–III cutaneous melanoma (CM patients (pts after surgery in an open, randomized, Phase II/III study. We present the results of the Phase II part of the ongoing CASVAC-0401 study (ClinicalTrials.gov: NCT01729663. Thirty-one pts were randomized to the CSF-470 vaccine (n = 20 or to the IFN-α2b arm (n = 11. During the 2-year treatment, immunized pts should receive 13 vaccinations. On day 1 of each visit, 1.6 × 107 irradiated CSF-470 cells plus 106 colony-forming units BCG plus 100 µg rhGM-CSF were administered intradermally, followed on days 2–4 by 100 µg rhGM-CSF. IFN-α2b pts should receive 10 million units (MU/day/5 days a week for 4 weeks; then 5 MU thrice weekly for 23 months. Toxicity and quality of life (QOL were evaluated at each visit. With a mean and a maximum follow-up of 39.4 and 83 months, respectively, a significant benefit in the distant metastasis-free survival (DMFS for CSF-470 was observed (p = 0.022. Immune monitoring showed an increase in antitumoral cellular and humoral response in vaccinated pts. CSF-470 was well tolerated; 20/20 pts presented grades 1–2 dermic reactions at the vaccination site; 3/20 pts presented grade 3 allergic reactions. Other adverse events (AEs were grade 1. Pts in the IFN-α2b arm presented grades 2–3 hematological (7/11, hepatic (2/11, and cardiac (1/11 toxicity; AEs in 9/11 pts forced treatment interruptions. QOL was significantly superior in the vaccine arm (p < 0.0001. Our results suggest that CSF-470 vaccine plus BCG plus GM-CSF can significantly prolong, with lower toxicity, the DMFS of high-risk CM pts with respect to medium-dose IFN-α2b. The continuation of a Phase III part of the CASVAC-0401 study is encouraged.
Optical activity via Kerr nonlinearity in a spinning chiral medium
Energy Technology Data Exchange (ETDEWEB)
Khan, Anwar Ali, E-mail: anwarali@uom.edu.pk [Department of Physics, University of Malakand at Chakdara Dir(L) (Pakistan); Bacha, Bakht Amin, E-mail: aminoptics@gmail.com [Department of Physics, University of Malakand at Chakdara Dir(L) (Pakistan); Khan, Rahmat Ali, E-mail: rahmat_alipk@yahoo.com [Department of Mathematics, University of Malakand (Pakistan)
2016-11-11
Optical activity is investigated in a chiral medium by employing the four level cascade atomic model, in which the optical responses of the atomic medium are studied with Kerr nonlinearity. Light entering into a chiral medium splits into circular birefringent beams. The angle of divergence between the circular birefringent beams and the polarization states of the two light beams is manipulated with Kerr nonlinearity. In the stationary chiral medium the angle of divergence between the circular birefringent beams is calculated to be 1.3 radian. Furthermore, circular birefringence is optically controlled in a spinning chiral medium, where the maximum rotary photon drag angle for left (right) circularly polarized beam is ±1.1 (±1.5) microradian. The change in the angle of divergence between circular birefringent beams by rotary photon drag is calculated to be 0.4 microradian. The numerical results may help to understand image designing, image coding, discovery of photonic crystals and optical sensing technology. - Highlights: • Coherent control of a circular birefringence in a chiral medium is studied. • Angle of divergence between birefringent beams is modified with Kerr nonlinearity. • Rotary photon drag is controlled for birefringent beams and enhanced with Kerr nonlinearity in a spinning medium. • Rotation of the angle of divergence is observed with mechanical rotation of the medium about an axis and modified with Kerr effect. • A change in the angle of divergence is calculated by about a microradian with rotary photon drag.
Dynamical Model about Rumor Spreading with Medium
Directory of Open Access Journals (Sweden)
Xiaxia Zhao
2013-01-01
Full Text Available Rumor is a kind of social remark, that is untrue, and not be confirmed, and spreads on a large scale in a short time. Usually, it can induce a cloud of pressure, anxiety, and panic. Traditionally, it is propagated by word of mouth. Nowadays, with the emergence of the internet, rumors can be spread by instant messengers, emails, or publishing. With this new pattern of spreading, an ISRW dynamical model considering the medium as a subclass is established. Beside the dynamical analysis of the model, we mainly explore the mechanism of spreading of individuals-to-individuals and medium-to-individual. By numerical simulation, we find that if we want to control the rumor spreading, it will not only need to control the rate of change of the spreader subclass, but also need to control the change of the information about rumor in medium which has larger influence. Moreover, to control the effusion of rumor is more important than deleting existing information about rumor. On the one hand, government should enhance the management of internet. On the other hand, relevant legal institutions for punishing the rumor creator and spreader on internet who can be tracked should be established. Using this way, involved authorities can propose efficient measures to control the rumor spreading to keep the stabilization of society and development of economy.
Determination of the Mean HI Absorption of the Intergalactic Medium ...
Indian Academy of Sciences (India)
Abstract. In recent years, the Lyman-α forest in quasar spectra has been used, together with N-body simulations, to determine the underly- ing matter distribution in the intergalactic medium (IGM). One of the key parameters to be known in order to compare observations and numerical simulations is the mean HI absorption in ...
Effect of geological medium on seismic signals from underground ...
Indian Academy of Sciences (India)
Effect of geological medium on seismic signals from underground nuclear explosion events – A case study for Baneberry site ... After the successful validation of the 3D numerical model for Baneberry site rock media, parametric studies are carried out for 1 and 8 kT yields at 100 m depth (Scaled Depths of Burst SDOB ...
Numerical and Evolutionary Optimization Workshop
Trujillo, Leonardo; Legrand, Pierrick; Maldonado, Yazmin
2017-01-01
This volume comprises a selection of works presented at the Numerical and Evolutionary Optimization (NEO) workshop held in September 2015 in Tijuana, Mexico. The development of powerful search and optimization techniques is of great importance in today’s world that requires researchers and practitioners to tackle a growing number of challenging real-world problems. In particular, there are two well-established and widely known fields that are commonly applied in this area: (i) traditional numerical optimization techniques and (ii) comparatively recent bio-inspired heuristics. Both paradigms have their unique strengths and weaknesses, allowing them to solve some challenging problems while still failing in others. The goal of the NEO workshop series is to bring together people from these and related fields to discuss, compare and merge their complimentary perspectives in order to develop fast and reliable hybrid methods that maximize the strengths and minimize the weaknesses of the underlying paradigms. Throu...
Activation of cyclopentane in aqueous medium and at room ...
African Journals Online (AJOL)
In this study, the use of a transition metal complex, tris (2,2-bipyridine) ruthenium (II) as a photosensitizer to convert cyclopentane into other compounds in an aqueous medium and at room temperature and pressure has been investigated. Peroxydisulphate ion has been used as a radical source. The irradiation of the ...
Status of numerical relativity
Indian Academy of Sciences (India)
Keywords. Numerical relativity; gravitational waves; black hole; neutron star. Abstract. I describe the current status of numerical relativity from my personal point of view. Here, I focus mainly on explaining the numerical implementations necessary for simulating general relativistic phenomena such as the merger of compact ...
On Emulation of Flueric Devices in Excitable Chemical Medium.
Directory of Open Access Journals (Sweden)
Andrew Adamatzky
Full Text Available Flueric devices are fluidic devices without moving parts. Fluidic devices use fluid as a medium for information transfer and computation. A Belousov-Zhabotinsky (BZ medium is a thin-layer spatially extended excitable chemical medium which exhibits travelling excitation wave-fronts. The excitation wave-fronts transfer information. Flueric devices compute via jets interaction. BZ devices compute via excitation wave-fronts interaction. In numerical model of BZ medium we show that functions of key flueric devices are implemented in the excitable chemical system: signal generator, and, xor, not and nor Boolean gates, delay elements, diodes and sensors. Flueric devices have been widely used in industry since late 1960s and are still employed in automotive and aircraft technologies. Implementation of analog of the flueric devices in the excitable chemical systems opens doors to further applications of excitation wave-based unconventional computing in soft robotics, embedded organic electronics and living technologies.
International Nuclear Information System (INIS)
Lassabatere, Thierry
1994-01-01
The target of this research is to set up a unified and coherent working frame based upon the rigorous principles of thermodynamics and making it possible to model a large class of physical phenomena acting in unsaturated porous media, as well as the related interactions with the mechanical state of the structures. This class corresponds to reactive phenomena among which one finds the phase change (desiccation) for which the whole of its subsequent actions (creep but essentially shrinkage) is modelled and which will be treated as a specific application example. The first chapter recalls the bases of the adopted description of the porous medium as well as the global thermodynamical frame which underlays the whole modelling. Chapter II deals with the mainly new formulation and the identification of a non linear elastic constitutive law of the medium involved. Various reflexion elements related to the microscopic behaviours of the components and to experiments have orientated the model towards some more limitative hypotheses making it possible to have a complete and explicit determination of a law for the macroscopic behaviour. Chapter IV and V are examples of application: chapter IV studies the problem of shrinkage and creep in a coupled linear elastic behaviour. Chapter V is limited to the case of shrinkage treated by a numerical application of the whole non-linear elastic model. The results obtained are in good agreement with the corresponding experiments. (author) [fr
International Nuclear Information System (INIS)
Green, R.T.; Manteufel, R.D.; Dodge, F.T.; Svedeman, S.J.
1993-07-01
The performance of a geologic repository for high-level nuclear waste will be influenced to a large degree by thermohydrologic phenomena created by the emplacement of heat-generating radioactive waste. The importance of these phenomena is manifest in that they can greatly affect the movement of moisture and the resulting transport of radionuclides from the repository. Thus, these phenomena must be well understood prior to a definitive assessment of a potential repository site. An investigation has been undertaken along three separate avenues of analysis: (i) laboratory experiments, (ii) mathematical models, and (iii) similitude analysis. A summary of accomplishments to date is as follows. (1) A review of the literature on the theory of heat and mass transfer in partially saturated porous medium. (2) A development of the governing conservation and constitutive equations. (3) A development of a dimensionless form of the governing equations. (4) A numerical study of the importance and sensitivity of flow to a set of dimensionless groups. (5) A survey and evaluation of experimental measurement techniques. (6) Execution of laboratory experiments of nonisothermal flow in a porous medium with a simulated fracture
Energy Technology Data Exchange (ETDEWEB)
Green, R.T.; Manteufel, R.D. [Nuclear Regulatory Commission, Washington, DC (United States). Div. of Regulatory Applications; Dodge, F.T.; Svedeman, S.J. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses
1993-07-01
The performance of a geologic repository for high-level nuclear waste will be influenced to a large degree by thermohydrologic phenomena created by the emplacement of heat-generating radioactive waste. The importance of these phenomena is manifest in that they can greatly affect the movement of moisture and the resulting transport of radionuclides from the repository. Thus, these phenomena must be well understood prior to a definitive assessment of a potential repository site. An investigation has been undertaken along three separate avenues of analysis: (i) laboratory experiments, (ii) mathematical models, and (iii) similitude analysis. A summary of accomplishments to date is as follows. (1) A review of the literature on the theory of heat and mass transfer in partially saturated porous medium. (2) A development of the governing conservation and constitutive equations. (3) A development of a dimensionless form of the governing equations. (4) A numerical study of the importance and sensitivity of flow to a set of dimensionless groups. (5) A survey and evaluation of experimental measurement techniques. (6) Execution of laboratory experiments of nonisothermal flow in a porous medium with a simulated fracture.
International Nuclear Information System (INIS)
Chanfray, G.
1996-07-01
We discuss various aspects of pion physics in the nuclear medium. We first study s-wave pion-nucleus interaction in connection with chiral symmetry restoration and quark condensate in the nuclear medium. We then address the question of p-wave pion-nucleus interaction and collective pionic modes in nuclei and draw the consequences for in medium ππ correlations especially in the scalar-isoscalar channel. We finally discuss the modification of the rho meson mass spectrum at finite density and/or temperature in connection with relativistic heavy ion collisions
Nimbus-2 Level 2 Medium Resolution Infrared Radiometer (MRIR) V001
National Aeronautics and Space Administration — The Nimbus II Medium Resolution Infrared Radiometer (MRIR) was designed to measure electromagnetic radiation emitted and reflected from the earth and its atmosphere...
Differential Medium for Vibrio cholerae
Schrank, Gordon D.; Stager, Charles E.; Verwey, W. F.
1973-01-01
A differential medium designed for rapid presumptive identification of Vibrio cholerae was described and shown to be useful for enumeration of viable cholera vibrios in the presence of other intestinal bacteria. Images PMID:4764406
Medium effects in direct reactions
International Nuclear Information System (INIS)
Karakoc, M; Bertulani, C
2013-01-01
We discuss medium corrections of the nucleon-nucleon (NN) cross sections and their influence on direct reactions at intermediate energies ≳50 MeV/nucleon. The results obtained with free NN cross sections are compared with those obtained with a geometrical treatment of Pauli-blocking and Dirac-Bruecker methods. We show that medium corrections may lead to sizable modifications for collisions at intermediate energies and that they are more pronounced in reactions involving weakly bound nuclei.
A Meta-Analysis of the Effectiveness of English-Medium Education in Hong Kong
Lo, Yuen Yi; Lo, Eric Siu Chung
2014-01-01
To facilitate second language learning, it has become increasingly popular to use a second language as the medium of instruction for content subjects for majority language students. Although numerous research studies have shown the advantages of such kind of programs in North America and Europe, those investigating English as the Medium of…
Response of an anisotropic liquid-saturated porous medium due to ...
Indian Academy of Sciences (India)
Eigenvalue approach, following Laplace and Fourier transforms, has been employed to find the general solution to the field equations in an anisotropic liquid-saturated porous medium, in the transformed domain. The results of isotropic liquid-saturated porous medium can be derived as a special case. A numerical inversion ...
7 CFR 1412.49 - Apportionment of long and medium grain rice.
2010-01-01
... 7 Agriculture 10 2010-01-01 2010-01-01 false Apportionment of long and medium grain rice. 1412.49... and Peanuts 2008 through 2012 § 1412.49 Apportionment of long and medium grain rice. (a) Rice base... rice base acres in paragraph (a) of this section into two categories: (i) Long grain rice, and (ii...
Numerical methods using Matlab
Lindfield, George
2012-01-01
Numerical Methods using MATLAB, 3e, is an extensive reference offering hundreds of useful and important numerical algorithms that can be implemented into MATLAB for a graphical interpretation to help researchers analyze a particular outcome. Many worked examples are given together with exercises and solutions to illustrate how numerical methods can be used to study problems that have applications in the biosciences, chaos, optimization, engineering and science across the board. Numerical Methods using MATLAB, 3e, is an extensive reference offering hundreds of use
Open waveguide cavity using a negative index medium.
Yan, Wei; Shen, Linfang
2008-12-01
An open waveguide cavity formed by a pair of planar waveguides, in which one guiding layer is a negative index medium and the other is a positive index medium, is theoretically demonstrated. For such a waveguide cavity the resonant frequency is independent of the total length of the waveguide system. With the coupled mode theory it is shown that energy flow circulation can be established through the special coupling between the waveguides at the resonant frequency, and thus the wave fields are localized. This phenomenon is further verified numerically with the finite-difference time-domain method. The quality factor of the open waveguide cavity is also discussed.
On modeling and measuring the temperature of the z ∼ 5 intergalactic medium
International Nuclear Information System (INIS)
Lidz, Adam; Malloy, Matthew
2014-01-01
The temperature of the low-density intergalactic medium (IGM) at high redshift is sensitive to the timing and nature of hydrogen and He II reionization, and can be measured from Lyman-alpha (Lyα) forest absorption spectra. Since the memory of intergalactic gas to heating during reionization gradually fades, measurements as close as possible to reionization are desirable. In addition, measuring the IGM temperature at sufficiently high redshifts should help to isolate the effects of hydrogen reionization since He II reionization starts later, at lower redshift. Motivated by this, we model the IGM temperature at z ≳ 5 using semi-numeric models of patchy reionization. We construct mock Lyα forest spectra from these models and consider their observable implications. We find that the small-scale structure in the Lyα forest is sensitive to the temperature of the IGM even at redshifts where the average absorption in the forest is as high as 90%. We forecast the accuracy at which the z ≳ 5 IGM temperature can be measured using existing samples of high resolution quasar spectra, and find that interesting constraints are possible. For example, an early reionization model in which reionization ends at z ∼ 10 should be distinguishable—at high statistical significance—from a lower redshift model where reionization completes at z ∼ 6. We discuss improvements to our modeling that may be required to robustly interpret future measurements.
Shock propagation in a heterogeneous medium
International Nuclear Information System (INIS)
Elbaz, D.
2011-01-01
In the frame of the inertial confinement fusion in direct drive, the use of foams as ablator allows the reduction of hydrodynamic instabilities created on the target by the direct laser irradiation. The foam is made up of carbon (CH) fibers impregnated of cryogenic deuterium-tritium (DT). In the past, studies have been carried out considering this foam to be a homogeneous medium. Yet, the foam presents heterogeneous features. We study the effects of this heterogeneity on the shock velocity when the laser irradiates the target. Thanks to experimental and numerical studies, we show that the shock propagates faster in the heterogeneous medium than in the homogeneous one with the same averaged density. This velocity gap depends on the presence rate of the CH fibers in the foam, the density ratio, the adiabatic coefficient and the foam geometry. We model the foam by different ways, more and more complex. The shock velocity modification is due to the baroclinicity which, during the interaction between the shock front and the interface, creates a vorticity deposition, responsible for the shock acceleration. Accordingly, an interface, which is plane and perpendicular to the front shock, maximizes the vorticity deposition and increases the velocity gaps between heterogeneous and homogeneous media. We found a correlation between the kinetic energy behind the shock front and the velocities relative difference. We compared our results with two analytical models. However, the system is not closed, so we can't for the moment develop a predictive model. (author) [fr
Effect of thermal loading due to laser pulse on thermoelastic porous medium under G-N theory
Directory of Open Access Journals (Sweden)
Mohamed I.A. Othman
Full Text Available The aim of this paper is to study the wave propagation of generalized thermoelastic medium with voids under the effect of thermal loading due to laser pulse with energy dissipation. The material is a homogeneous isotropic elastic half-space and heated by a non-Gaussian laser beam with the pulse duration of 0.2â¯ps. A normal mode method is proposed to analyse the problem and obtain numerical solutions for the displacement components, stresses, temperature distribution and the change in the volume fraction field. The results of the physical quantities have been illustrated graphically by comparison between both types II and III of Green-Naghdi theory for two values of time, as well as with and without void parameters. Keywords: Laser pulse, Voids, Energy dissipation, Green-Naghdi theory, Wave propagation, Thermoelasticity
Numerical Modelling of Streams
DEFF Research Database (Denmark)
Vestergaard, Kristian
In recent years there has been a sharp increase in the use of numerical water quality models. Numeric water quality modeling can be divided into three steps: Hydrodynamic modeling for the determination of stream flow and water levels. Modelling of transport and dispersion of a conservative...
Status of numerical relativity
Indian Academy of Sciences (India)
Abstract. I describe the current status of numerical relativity from my personal point of view. Here, I focus mainly on explaining the numerical implementations necessary for simulating general relativistic phenomena such as the merger of compact binaries and stellar collapse, emphasizing the well-developed current status of ...
Status of numerical relativity
Indian Academy of Sciences (India)
I describe the current status of numerical relativity from my personal point of view. Here, I focus mainly on explaining the numerical implementations necessary for simulating general relativistic phenomena such as the merger of compact binaries and stellar collapse, emphasizing the well-developed current status of such ...
Directory of Open Access Journals (Sweden)
M. Padma Latha
2007-04-01
Full Text Available Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II complexes of L-methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH2+, LH and L-. The predominant species detected are ML, MLH, ML2, ML2H, ML2H2 and MLOH. Models containing different numbers of species were refined by using the computer program MINIQUAD 75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.
Chemistry of the interstellar medium
International Nuclear Information System (INIS)
Umanskij, S.Ya.
1979-01-01
Some aspects of chemistry of interstellar gas-dust clouds are considered. The specific attention is paid to the molecule formation in the interstellar medium. Discussed are the process of hydrogen atom recombination on interstellar specks of dust as well as the formation of double-atom molecules. An ion-molecular mechanism plays the main role in the origination of multiatom molecules. It is noted, that the real progress in chemistry of the interstellar medium will be determined by the development of laboratory investigations at ultralow temperatures and study of the processes proceeding on solid surfaces
Modeling Fractures in a Poro-Elastic Medium
Directory of Open Access Journals (Sweden)
Ganis Benjamin
2014-07-01
Full Text Available We present a fracture model in a poro-elastic medium. The model describes the fracture as a curve or surface according to the dimension, the width of the crack being included into the equation of flow in the fracture. The discretization uses mixed finite elements for the fluid and continuous finite elements for the porous medium’s displacement. The numerical scheme is solved by an algorithm that decouples, on one hand, the computation of the mechanics from that of the fluid, and on the other hand, the computation of the flow in the reservoir from that in the fracture. The model is illustrated by a numerical experiment.
Periodic sequence of stabilized wave segments in an excitable medium
Zykov, V. S.; Bodenschatz, E.
2018-03-01
Numerical computations show that a stabilization of a periodic sequence of wave segments propagating through an excitable medium is possible only in a restricted domain within the parameter space. By application of a free-boundary approach, we demonstrate that at the boundary of this domain the parameter H introduced in our Rapid Communication is constant. We show also that the discovered parameter predetermines the propagation velocity and the shape of the wave segments. The predictions of the free-boundary approach are in good quantitative agreement with results from numerical reaction-diffusion simulations performed on the modified FitzHugh-Nagumo model.
A review of flow modeling for dense medium cyclones
Energy Technology Data Exchange (ETDEWEB)
M. Narasimha; M.S. Brennan; P.N. Holtham [Tata Steel, Jamshedpur (India). R& amp; D Division
2006-06-15
A critical assessment is presented for the existing fluid flow models used for dense medium cyclones (DMCs) and hydrocyclones. As the present discussion indicates, the understanding of dense medium cyclone flow is still far from the complete. However, its similarity to the hydrocyclone provides a basis for improved understanding of fluid flow in DMCs. The complexity of fluid flow in DMCs is basically due to the existence of medium as well as the dominance of turbulent particle size and density effects on separation. Both the theoretical and experimental analysis is done with respect to two-phase motions and solid phase flow in hydrocyclones or DMCs. A detailed discussion is presented on the empirical, semiempirical, and the numerical models based upon both the vorticity-stream function approach and Navier-Stokes equations in their primitive variables and in cylindrical coordinates available in literature. The existing equations describing turbulence and multiphase flows in cyclone are also critically reviewed.
The interaction of supernova ejecta with an ambient medium
International Nuclear Information System (INIS)
Chevalier, R.A.
1983-01-01
Plausible environments for supernovae are the interstellar medium with constant density or a circumstellar medium built up by mass loss with rho proportional to r -2 . Self-similar solutions for the interaction region between the expanding supernova gas and the ambient gas exist provided that the expanding gas has rho proportional to rsup(-n) with n > 5. The circumstellar medium case is likely to be important for the early evolution of Type II supernovae because their progenitor stars are probably red supergiants. The radio and X-ray emission observed from extragalactic supernovae may be from this interaction region. The early self-similar solutions can also be applied to the young galactic remnants. (Auth.)
Ziegler, Gerhard
2011-01-01
Distance protection provides the basis for network protection in transmission systems and meshed distribution systems. This book covers the fundamentals of distance protection and the special features of numerical technology. The emphasis is placed on the application of numerical distance relays in distribution and transmission systems.This book is aimed at students and engineers who wish to familiarise themselves with the subject of power system protection, as well as the experienced user, entering the area of numerical distance protection. Furthermore it serves as a reference guide for s
Singh, Devraj
2015-01-01
Numerical Problems in Physics, Volume 1 is intended to serve the need of the students pursuing graduate and post graduate courses in universities with Physics and Materials Science as subject including those appearing in engineering, medical, and civil services entrance examinations. KEY FEATURES: * 29 chapters on Optics, Wave & Oscillations, Electromagnetic Field Theory, Solid State Physics & Modern Physics * 540 solved numerical problems of various universities and ompetitive examinations * 523 multiple choice questions for quick and clear understanding of subject matter * 567 unsolved numerical problems for grasping concepts of the various topic in Physics * 49 Figures for understanding problems and concept
Micropropagation of dahlia in static liquid medium using slow-release tools of medium ingredients
Klerk, de G.J.M.; Brugge, ter J.
2011-01-01
Growth of dahlia shoots in vitro was ca. 4 times faster in liquid medium than on solidified medium. In liquid standard medium (3% sucrose, macroelements according to Driver–Kuniyuki Walnut medium, microelements according to Murashige–Skoog medium, 0.44 µM benzylaminopurine), the major medium
Electromagnetic stress tensor for an amorphous metamaterial medium
Wang, Neng; Wang, Shubo; Ng, Jack
2018-03-01
We analytically and numerically investigated the internal optical forces exerted by an electromagnetic wave inside an amorphous metamaterial medium. We derived, by using the principle of virtual work, the Helmholtz stress tensor, which takes into account the electrostriction effect. Several examples of amorphous media are considered, and different electromagnetic stress tensors, such as the Einstein-Laub tensor and Minkowski tensor, are also compared. It is concluded that the Helmholtz stress tensor is the appropriate tensor for such systems.
African Journals Online (AJOL)
Windows User
., 2009) biomaterials. However, the ..... reported for various microorganisms by various researchers (Gong et al., 2005). At biomass ... the increase in initial Pb (II) was also observed for removal of Pb (II) by loofa sponge immobilized Aspergillus.
Animal Locomotion in Different Mediums
Indian Academy of Sciences (India)
Wetlands are repositories of unique biodiversity. Wetlandorganisms are well adapted to their habitat, lying at theinterface of aquatic and terrestrial environments. In order tounderstand their adaptations in a better way, it is essential tograsp the basic properties of the medium in which variousorganisms live. This is attempted ...
Animal Locomotion in Different Mediums
Indian Academy of Sciences (India)
IAS Admin
Fishes, moving in water encounter drag forces, which can be of considerable magnitude. If sudden movement is required to catch prey or escape predators in a viscous medium, it is only possible by the contraction of fast, white muscle fibres, which rely on anaerobic glycolysis pathways. Therefore, it is not surprising that.
Molecular spectroscopy of interstellar medium
International Nuclear Information System (INIS)
Varshalovich, D.A.; Khersonskij, V.K.
1980-01-01
Experimental data obtained in the investigation into molecules of interstellar medium by molecular-spectroscopic methods are discussed generally. Ion-molecule reactions play a significant part in the formation of multiatom molecules in the interstellar medium as well as reactions proceeding on the surface of interstellar dust. More than 50 types of molecules have been detected in the interstellar medium at present. In a wide range of wave lengths over 500 spectral lines belonging to various molecules and molecular fragments have been recorded. Interstellar molecules permit to investigate interstellar gas from all the sides. They are a suitable indicator of the isotope composition of interstellar gas. Radio observations of interstellar molecules make it possible to effectively investigate kinematics and space structure both separate gas-dust complexes and total gas distribution in Galaxy. It is noted that achievements of molecular spectroscopy of the interstellar medium radically change representations of the chemical composition of interstellar gas, of isotope abundance and organic substance in the Universe
Hadron photoproduction at medium energy
International Nuclear Information System (INIS)
Dainton, J.B.
1985-04-01
Results from measurements of multibody photoproduction at medium incident photon energy (2.8 to 4.8 GeV) are presented and discussed. Particular emphasis is placed on topics which are not well understood and which therefore motivate experiments with the upgraded electron accelerator and storage ring ELSA at the University of Bonn, FR Germany. (author)
Management of small and medium size enterprises as a carrier of economic growth
Directory of Open Access Journals (Sweden)
Ožegović Lazar
2012-01-01
Full Text Available Numerous studies in the world of market economy show that the share of small and medium size enterprises is constantly increasing compared to large enterprises. This does not decrease the significance of large enterprises, but the dependence between them gets larger every day. National economies which manage to find the optimal combination between small, medium size and large enterprises are more successful than the others. Management of small and medium size enterprises (SMEs in conceptual terms is similar to the process of management of large enterprises. An organization must be managed in order to function and this rule applies to small and medium size enterprises.
Blackbody emission from light interacting with an effective moving dispersive medium.
Petev, M; Westerberg, N; Moss, D; Rubino, E; Rimoldi, C; Cacciatori, S L; Belgiorno, F; Faccio, D
2013-07-26
Intense laser pulses excite a nonlinear polarization response that may create an effective flowing medium and, under appropriate conditions, a blocking horizon for light. Here, we analyze in detail the interaction of light with such laser-induced flowing media, fully accounting for the medium dispersion properties. An analytical model based on a first Born approximation is found to be in excellent agreement with numerical simulations based on Maxwell's equations and shows that when a blocking horizon is formed, the stimulated medium scatters light with a blackbody emission spectrum. Based on these results, diamond is proposed as a promising candidate medium for future studies of Hawking emission from artificial, dispersive horizons.
Remarks on numerical semigroups
International Nuclear Information System (INIS)
Torres, F.
1995-12-01
We extend results on Weierstrass semigroups at ramified points of double covering of curves to any numerical semigroup whose genus is large enough. As an application we strengthen the properties concerning Weierstrass weights state in [To]. (author). 25 refs
Introductory numerical analysis
Pettofrezzo, Anthony J
2006-01-01
Written for undergraduates who require a familiarity with the principles behind numerical analysis, this classical treatment encompasses finite differences, least squares theory, and harmonic analysis. Over 70 examples and 280 exercises. 1967 edition.
Introduction to numerical analysis
Hildebrand, F B
1987-01-01
Well-known, respected introduction, updated to integrate concepts and procedures associated with computers. Computation, approximation, interpolation, numerical differentiation and integration, smoothing of data, other topics in lucid presentation. Includes 150 additional problems in this edition. Bibliography.
Numerical semigroups and applications
Assi, Abdallah
2016-01-01
This work presents applications of numerical semigroups in Algebraic Geometry, Number Theory, and Coding Theory. Background on numerical semigroups is presented in the first two chapters, which introduce basic notation and fundamental concepts and irreducible numerical semigroups. The focus is in particular on free semigroups, which are irreducible; semigroups associated with planar curves are of this kind. The authors also introduce semigroups associated with irreducible meromorphic series, and show how these are used in order to present the properties of planar curves. Invariants of non-unique factorizations for numerical semigroups are also studied. These invariants are computationally accessible in this setting, and thus this monograph can be used as an introduction to Factorization Theory. Since factorizations and divisibility are strongly connected, the authors show some applications to AG Codes in the final section. The book will be of value for undergraduate students (especially those at a higher leve...
Static Analysis Numerical Algorithms
2016-04-01
STATIC ANALYSIS OF NUMERICAL ALGORITHMS KESTREL TECHNOLOGY, LLC APRIL 2016 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE; DISTRIBUTION...3. DATES COVERED (From - To) NOV 2013 – NOV 2015 4. TITLE AND SUBTITLE STATIC ANALYSIS OF NUMERICAL ALGORITHMS 5a. CONTRACT NUMBER FA8750-14-C...and Honeywell Aerospace Advanced Technology to combine model-based development of complex avionics control software with static analysis of the
Numerical computations with GPUs
Kindratenko, Volodymyr
2014-01-01
This book brings together research on numerical methods adapted for Graphics Processing Units (GPUs). It explains recent efforts to adapt classic numerical methods, including solution of linear equations and FFT, for massively parallel GPU architectures. This volume consolidates recent research and adaptations, covering widely used methods that are at the core of many scientific and engineering computations. Each chapter is written by authors working on a specific group of methods; these leading experts provide mathematical background, parallel algorithms and implementation details leading to
Numerical transducer modelling
DEFF Research Database (Denmark)
Cutanda, Vicente
1999-01-01
Numerical modelling is of importance for the design, improvement and study of acoustic transducers such as microphones and accelerometers. Techniques like the boundary element method and the finite element method are the most common supplement to the traditional empirical and analytical approaches...... errors and instabilities in the computations of numerical solutions. An investigation to deal with this narrow-gap problem has been carried out....
African Journals Online (AJOL)
activities of Schiff base tin (II) complexes. Neelofar1 ... Conclusion: All synthesized Schiff bases and their Tin (II) complexes showed high antimicrobial and ...... Singh HL. Synthesis and characterization of tin (II) complexes of fluorinated Schiff bases derived from amino acids. Spectrochim Acta Part A: Molec Biomolec.
Numerical simulation of seismic wave field in graded geological media containing multiple cavities
Fontara, Ioanna-Kleoniki; Dineva, Petia S.; Manolis, George D.; Wuttke, Frank
2016-08-01
In this study, we develop an efficient boundary integral equation method for estimation of seismic motion in a graded medium with multiple cavities under antiplane strain conditions. This inhomogeneous and heterogeneous medium is subjected to either time-harmonic incident shear seismic waves or to body waves radiating from a point seismic source. Three different types of soil material gradient are considered: (i) density and shear modulus vary proportionally as quadratic functions of depth, but the wave velocity remains constant; (ii) the soil material is viscoelastic, with a shear modulus and density that vary with respect to the spatial coordinates in an arbitrary fashion, so that the wave velocity is both frequency and position-dependent and (iii) the soil material has position-dependent shear modulus and constant density, yielding a linear profile for the wave velocity. Three different, frequency-dependent boundary integral equation schemes are respectively developed for the aforementioned three types of graded soil materials based on: (i) Green's function for the quadratically graded elastic half-plane; (ii) a fundamental solution for the viscoelastic full-plane with position-dependent wave speed profiles and (iii) a fundamental solution for an elastic full-plane with a linearly varying wave speed profile. Next, a number of cases involving geological media with position-dependent material properties and any number of cavities of various shapes and geometry are solved in the frequency domain. The numerical results reveal the dependency of the wave fields and zones of stress concentration on the following key factors: (i) type and properties of the soil material gradient; (ii) type and characteristics of the applied seismic load; (iii) shape, position and number of cavities and (iv) interaction phenomena between the cavities and the free surface.
Numerical Based Linear Model for Dipole Magnets
Energy Technology Data Exchange (ETDEWEB)
Li,Y.; Krinsky, S.; Rehak, M.
2009-05-04
In this paper, we discuss an algorithm for constructing a numerical linear optics model for dipole magnets from a 3D field map. The difference between the numerical model and K. Brown's analytic approach is investigated and clarified. It was found that the optics distortion due to the dipoles' fringe focusing must be properly taken into account to accurately determine the chromaticities. In NSLS-II, there are normal dipoles with 35-mm gap and dipoles for infrared sources with 90-mm gap. This linear model of the dipole magnets is applied to the NSLS-II lattice design to match optics parameters between the DBA cells having dipoles with different gaps.
Analytical and numerical study of outflows around young stars
International Nuclear Information System (INIS)
Combet, Celine
2006-01-01
This thesis is built in two distinct parts, treating of two different astrophysical topics: i) in the first (and main) part, work related to star formation is presented whereas ii) the second part deals with cosmic rays. When a star forms, huge bipolar ejections of material, under the form of jets and molecular outflows, are observed as accretion proceeds onto the central object. After an introduction giving a large overview of the star formation process, we focus on the different 'standard' approaches used to model molecular outflows. An alternative and complementary model is then built: the transit model. It is a self-similar MHD model where part of the infalling material is being diverted into an outflow when approaching the central object. It is shown that the transit allows to reach the huge mass rates observed in massive star formation, in opposition to the 'standard' approaches. The model is thoughtfully studied with a Monte Carlo exploration of the parameter space and two families of solutions are put to the fore. The transit model gives a large-scale description of the protostellar environment, showing both density and velocity structures. It is in such a medium that a jet launched from the accretion disk will propagate and a preliminary numerical study of this propagation shows that the morphology and kinematics of the jet is strongly affected by the ambient medium. We conclude in the importance of a good description of the latter and the urge of leaving the 'uniform and motionless medium' usually used in such simulations. The second part focuses on the nuclear component of the Galactic cosmic rays. After being accelerated in supernova remnants, these nuclei propagate through the Galaxy and its halo. Eventually, some of them reach the Earth where they are detected. A good understanding of the propagation processes is compulsory in order to derive the source abundances from the measured ones. In this work, we focus on ultra
Maina, Fadji Hassane; Ackerer, Philippe; Younes, Anis; Guadagnini, Alberto; Berkowitz, Brian
2017-06-07
We present a combined experimental and numerical modeling study that addresses two principal questions: (i) is any particular Eulerian-based method used to solve the classical advection-dispersion equation (ADE) clearly superior (relative to the others), in terms of yielding solutions that reproduce BTCs of the kind that are typically sampled at the outlet of a laboratory cell? and (ii) in the presence of matches of comparable quality against such BTCs, do any of these methods render different (or similar) numerical BTCs at locations within the domain? To address these questions, we obtained measurements from carefully controlled laboratory experiments, and employ them as a reference against which numerical results are benchmarked and compared. The experiments measure solute transport breakthrough curves (BTCs) through a square domain containing various configurations of coarse, medium, and fine quartz sand. The approaches to solve the ADE involve Eulerian-Lagrangian and Eulerian (finite volume, finite elements, mixed and discontinuous finite elements) numerical methods. Model calibration is not examined; permeability and porosity of each sand were determined previously through separate, standard laboratory tests, while dispersivities are assigned values proportional to mean grain size. We find that the spatial discretization of the flow field is of critical importance, due to the non-uniformity of the domain. Although simulated BTCs at the system outlet are observed to be very similar for these various numerical methods, computed local (point-wise, inside the domain) BTCs can be very different. We find that none of the numerical methods is able to fully reproduce the measured BTCs. The impact of model parameter uncertainty on the calculated BTCs is characterized through a set of numerical Monte Carlo simulations; in cases where the impact is significant, assessment of simulation matches to the experimental data can be ambiguous. Copyright © 2017 Elsevier B.V. All
On Numerical Simulation of Flow Through Oil Filters
Iliev, O.; Laptev, V.
2003-01-01
This paper concerns numerical simulation of flow through oil filters. Oil filters consist of filter housing (filter box), and a porous filtering medium, which completely separates the inlet from the outlet. We discuss mathematical models, describing coupled flows in the pure liquid subregions and in the porous filter media, as well as interface conditions between them. Further, we reformulate the problem in fictitious regions method manner, and discuss peculiarities of the numerical algorithm...
In vivo pollination with maize pollen stored in aqueous medium
Energy Technology Data Exchange (ETDEWEB)
Broglia, M. [ENEA, Casaccia (Italy). Area Energia e Innovazione
1994-11-01
A hypertonic aqueous medium can be used to obtain non-bursting, non-germinating maize (zea mays L.) pollen suspensions, which can be stored at 0{sub 0}C preserving pollen viability. This medium could be used in different techniques for maize pollen genetic manipulation, but fertilization ability of such stored pollen has to be proved. In this work, pollen stored in different hypertonic media was used to perform in vivo pollinations by different techniques. Uncut silks and pollen filtered in a paste form were found necessary perequisites for a fruitfull pollen-silk interaction. In the 0.5-1.5 M range a highter sucrose concentration increases storability but decreases fertilization ability. Salts as KNO{sub 3} and CaCl{sub 2} were also explored in an osmotic concentration range. Considering that soluble calcium, needful for germination, can be lost from pollen in aqueous media, a hypertonic aqueous medium osmotically balanced in calcium and sucrose contents was tested as storage medium. Pollen stored several hours in this medium produced numerous seed sets; the high variability of the obtained results made evident the crucial role of silk status in successful pollinations.
Medium modifications with recoil polarization
Energy Technology Data Exchange (ETDEWEB)
Brand, J.F.J. van den [Nationaal Instituut voor Kernfysica en Hoge Energiefysica, Amsterdam (Netherlands); Ent, R. [CEBAF, Newport News, VA (United States)
1994-04-01
The authors show that the virtual Compton scattering process allows for a precise study of the off-shell electron-nucleon vertex. In a separable model, they show the sensitivity to new unconstrained structure functions of the nucleon, beyond the usual Dirac and Pauli form factors. In addition, they show the sensitivity to bound nucleon form factors using the reaction 4He({rvec e},e{prime},{rvec p}){sup 3}H. A nucleon embedded in a nucleus represents a complex system. Firstly, the bound nucleon is necessarily off-shell and in principle a complete understanding of the dynamical structure of the nucleon is required in order to calculate its off-shell electromagnetic interaction. Secondly, one faces the possibility of genuine medium effects, such as for example quark-exchange contributions. Furthermore, the electromagnetic coupling to the bound nucleon is dependent on the nuclear dynamics through the self-energy of the nucleon in the nuclear medium.
Medium modifications with recoil polarization
International Nuclear Information System (INIS)
Brand, J.F.J. van den; Ent, R.
1994-01-01
The authors show that the virtual Compton scattering process allows for a precise study of the off-shell electron-nucleon vertex. In a separable model, they show the sensitivity to new unconstrained structure functions of the nucleon, beyond the usual Dirac and Pauli form factors. In addition, they show the sensitivity to bound nucleon form factors using the reaction 4He(rvec e,e',rvec p) 3 H. A nucleon embedded in a nucleus represents a complex system. Firstly, the bound nucleon is necessarily off-shell and in principle a complete understanding of the dynamical structure of the nucleon is required in order to calculate its off-shell electromagnetic interaction. Secondly, one faces the possibility of genuine medium effects, such as for example quark-exchange contributions. Furthermore, the electromagnetic coupling to the bound nucleon is dependent on the nuclear dynamics through the self-energy of the nucleon in the nuclear medium
Probing the local interstellar medium
International Nuclear Information System (INIS)
Suess, S.T.; Dessler, A.J.
1985-01-01
The paper concerns the location of the heliospheric shock, in view of the discrepancy between the theoretical and experimental values. To determine whether the discrepancy may be attributed to parameters used to describe the local interstellar medium [LISM], the authors applied a sophisticated model of solar-wind expansion to deduce a range of parameters for the LISM. Both the interstellar magnetic field and the pressure due to galactic cosmic rays are considered. (U.K.)
Medium-dependent control of the bacterial growth rate.
Ehrenberg, Måns; Bremer, Hans; Dennis, Patrick P
2013-04-01
By combining results from previous studies of nutritional up-shifts we here re-investigate how bacteria adapt to different nutritional environments by adjusting their macromolecular composition for optimal growth. We demonstrate that, in contrast to a commonly held view the macromolecular composition of bacteria does not depend on the growth rate as an independent variable, but on three factors: (i) the genetic background (i.e. the strain used), (ii) the physiological history of the bacteria used for inoculation of a given growth medium, and (iii) the kind of nutrients in the growth medium. These factors determine the ribosome concentration and the average rate of protein synthesis per ribosome, and thus the growth rate. Immediately after a nutritional up-shift, the average number of ribosomes in the bacterial population increases exponentially with time at a rate which eventually is attained as the final post-shift growth rate of all cell components. After a nutritional up-shift from one minimal medium to another minimal medium of higher nutritional quality, ribosome and RNA polymerase syntheses are co-regulated and immediately increase by the same factor equal to the increase in the final growth rate. However, after an up-shift from a minimal medium to a medium containing all 20 amino acids, RNA polymerase and ribosome syntheses are no longer coregulated; a smaller rate of synthesis of RNA polymerase is compensated by a gradual increase in the fraction of free RNA polymerase, possibly due to a gradual saturation of mRNA promoters. We have also analyzed data from a recent publication, in which it was concluded that the macromolecular composition in terms of RNA/protein and RNA/DNA ratios is solely determined by the effector molecule ppGpp. Our analysis indicates that this is true only in special cases and that, in general, medium adaptation also depends on factors other than ppGpp. Copyright © 2012 Elsevier Masson SAS. All rights reserved.
Barometric Pumping of a Fractured Porous Medium
Adler, P. M.; Mourzenko, V.; Thovert, J. F.; Pili, E.; Guillon, S.
2014-12-01
Fluctuations in the ambient atmospheric pressure result in motion of air in porous fractured media. This mechanism, known as barometric pumping, efficiently transports gaseous species through the vadose zone to the atmosphere. This is of interest in fields, such as transport of trace gases from soil to atmosphere, remediation of contaminated sites, radon in buildings, leakage from carbon sequestration sites and detection of nuclear explosions. The fractures are modeled as polygonal plane surfaces with a given transmissivity embedded in a permeable matrix. The slightly compressible fluid obeys Darcy's law in these two media with exchanges between them. The solute obeys convection-diffusion equations in both media again with exchanges. The fractures and the porous medium are meshed by triangles and tetrahedra, respectively. The equations are discretized by the finite volume method. A Flux Limiting Scheme diminishes numerical dispersion ; the solute transfer between the fractures and the porous medium is precisely evaluated. The resulting equations are solved by conjugate gradient algorithms. This model is applied to the Roselend Natural Laboratory. At a 55 m depth, a sealed cavity allows for gas release experiments across fractured porous rocks in the unsaturated zone. The fractures are hexagons with a radius of 5m; their density is larger than 2.4 10-3 m-3; the aperture is about 0.5 mm. The pressure fluctuations are sinusoidal, of amplitude 0.01 bar and period 1 week. The solute concentration is equal to 1 at the bottom. Systematic results will be presented. First, the precision of the calculations is assessed. Second, the pressure and solute concentration fields are displayed and discussed. Third, the influence of the major parameters (fracture density, aperture, porosity, diffusion coefficient,…) is illustrated and discussed. These results are discussed in terms of the amplification of solute transfer to the ground surface by the pressure fluctuations.
Mie Scattering by a Conducting Sphere Coated Uniaxial Single-Negative Medium
Directory of Open Access Journals (Sweden)
You-Lin Geng
2012-01-01
Full Text Available We propose an accurate analytical method to compute the electromagnetic scattering from three-dimensional (3D conducting sphere coated uniaxial anisotropic single-negative (SNG medium. Based on the spherical vector wave functions (SVWFs in uniaxial anisotropic medium, the electromagnetic field in homogeneous uniaxial SNG medium and free space can be expressed by the SVWFs in uniaxial SNG medium and free space. The continued boundary conditions of electromagnetic fields between the uniaxial SNG medium and free space are applied, and the tangential electrical field is vanished in the surface of conducting sphere, the coefficients of scattering fields in free space can be derived, and then the character of scattering of conducting sphere coated homogeneous uniaxial SNG medium can be obtained. Some numericals are given in the end.
DEFF Research Database (Denmark)
Henriquez, Vicente Cutanda
This thesis describes the development of a numerical model of the propagation of sound waves in fluids with viscous and thermal losses, with application to the simulation of acoustic transducers, in particular condenser microphones for measurement. The theoretical basis is presented, numerical...... tools and implementation techniques are described and performance tests are carried out. The equations that govern the motion of fluids with losses and the corresponding boundary conditions are reduced to a form that is tractable for the Boundary Element Method (BEM) by adopting some hypotheses...... that are allowable in this case: linear variations, absence of flow, harmonic time variation, thermodynamical equilibrium and physical dimensions much larger than the molecular mean free path. A formulation of the BEM is also developed with an improvement designed to cope with the numerical difficulty associated...
Fundamentals of Numerical Modelling of Casting Processes
DEFF Research Database (Denmark)
Hattel, Jesper Henri; Pryds, Nini; Thorborg, Jesper
Fundamentals of Numerical Modelling of Casting Processes comprises a thorough presentation of the basic phenomena that need to be addressed in numerical simulation of casting processes. The main philosophy of the book is to present the topics in view of their physical meaning, whenever possible......, rather than relying strictly on mathematical formalism. The book, aimed both at the researcher and the practicing engineer, as well as the student, is naturally divided into four parts. Part I (Chapters 1-3) introduces the fundamentals of modelling in a 1-dimensional framework. Part II (Chapter 4......) presents the most important aspects of solidification theory related to modelling. Part III (Chapter 5) describes the fluid flow phenomena and in part IV (Chapter 6) the stress-strain analysis is addressed. For all parts, both numerical formulations as well as some important analytical solutions...
Medium Theory and Social Systems
DEFF Research Database (Denmark)
Tække, Jesper
The paper first gives a tentative theoretical explanation of the concept of media, based on the dichotomies of actual/potential (meaning), form/medium (appearance), and substratum/material content (extension in time and space). This theoretical explanation presents...... seen as medium for formation. Finally the paper takes the micro level perspective by applying the theory to newsgroups, interpreting them as self-organizing interactive systems giving a differentiated and diversified scope for social inclusion. ......The paper first gives a tentative theoretical explanation of the concept of media, based on the dichotomies of actual/potential (meaning), form/medium (appearance), and substratum/material content (extension in time and space). This theoretical explanation presents...... the possibility for observation both of a social micro and a social macro level from a medium perspective. In the next section the paper frames the macro level by a tentative synthesis of the medium theory and the sociological systems theory briefly describing a socio...
International Nuclear Information System (INIS)
McKee, S.; Elliott, C.M.
1986-01-01
The applications of mathematics to industrial problems involves the formulation of problems which are amenable to mathematical investigation, mathematical modelling, the solution of the mathematical problem and the inter-pretation of the results. There are 12 chapters describing industrial problems where mathematics and numerical analysis can be applied. These range from the numerical assessment of the flatness of engineering surfaces and plates, the design of chain links, control problems in tidal power generation and low thrust satellite trajectory optimization to mathematical models in welding. One chapter, on the ageing of stainless steels, is indexed separately. (UK)
On numerical Bessel transformation
International Nuclear Information System (INIS)
Sommer, B.; Zabolitzky, J.G.
1979-01-01
The authors present a computer program to calculate the three dimensional Fourier or Bessel transforms and definite integrals with Bessel functions. Numerical integration of systems containing Bessel functions occurs in many physical problems, e.g. electromagnetic form factor of nuclei, all transitions involving multipole expansions at high momenta. Filon's integration rule is extended to spherical Bessel functions. The numerical error is of the order of the Simpson error term of the function which has to be transformed. Thus one gets a stable integral even at large arguments of the transformed function. (Auth.)
Isaacson, Eugene
1994-01-01
This excellent text for advanced undergraduates and graduate students covers norms, numerical solution of linear systems and matrix factoring, iterative solutions of nonlinear equations, eigenvalues and eigenvectors, polynomial approximation, and other topics. It offers a careful analysis and stresses techniques for developing new methods, plus many examples and problems. 1966 edition.
Numerical Estimation in Preschoolers
Berteletti, Ilaria; Lucangeli, Daniela; Piazza, Manuela; Dehaene, Stanislas; Zorzi, Marco
2010-01-01
Children's sense of numbers before formal education is thought to rely on an approximate number system based on logarithmically compressed analog magnitudes that increases in resolution throughout childhood. School-age children performing a numerical estimation task have been shown to increasingly rely on a formally appropriate, linear…
Anastassiou, George A
2015-01-01
This is the first numerical analysis text to use Sage for the implementation of algorithms and can be used in a one-semester course for undergraduates in mathematics, math education, computer science/information technology, engineering, and physical sciences. The primary aim of this text is to simplify understanding of the theories and ideas from a numerical analysis/numerical methods course via a modern programming language like Sage. Aside from the presentation of fundamental theoretical notions of numerical analysis throughout the text, each chapter concludes with several exercises that are oriented to real-world application. Answers may be verified using Sage. The presented code, written in core components of Sage, are backward compatible, i.e., easily applicable to other software systems such as Mathematica®. Sage is open source software and uses Python-like syntax. Previous Python programming experience is not a requirement for the reader, though familiarity with any programming language is a p...
International Nuclear Information System (INIS)
Sollogoub, Pierre
2001-01-01
Numerical analyses are needed in different steps of the overall design process. Complex models or non-linear reactor core behaviour are important for qualification and/or comparison of results obtained. Adequate models and test should be defined. Fuel assembly, fuel row, and the complete core should be tested for seismic effects causing LOCA and flow-induced vibrations (FIV)
Paradoxes in numerical calculations
Czech Academy of Sciences Publication Activity Database
Brandts, J.; Křížek, Michal; Zhang, Z.
2016-01-01
Roč. 26, č. 3 (2016), s. 317-330 ISSN 1210-0552 R&D Projects: GA ČR GA14-02067S Institutional support: RVO:67985840 Keywords : round-off errors * numerical instability * recurrence formulae Subject RIV: BA - General Mathematics Impact factor: 0.394, year: 2016
Numerical Methods in Linguistics
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 1. Numerical Methods in Linguistics - An Introduction to Glottochronology. Raamesh Gowri Raghavan. General Article Volume 10 Issue 1 January 2005 pp 17-24. Fulltext. Click here to view fulltext PDF. Permanent link:
RAMAN amplifier gain dynamics with ASE : Numerical analysis and ...
African Journals Online (AJOL)
... understanding the basic properties of the gain medium. So in this work, we demonstrate an analytical formalism and a numerical horizon of the amplified spontaneous emission (ASE) noise power for distributed Raman amplifier (DRA). Keywords: Amplified spontaneous emission (ASE), optical noise, Raman amplification ...
Budroni, Marcello A; Calabrese, Ilaria; Miele, Ylenia; Rustici, Mauro; Marchettini, Nadia; Rossi, Federico
2017-12-13
In this paper we show that the active interplay of nonlinear kinetics and transport phenomena in a chemical oscillator can be exploited to induce and control chaos. To this aim we use as a model system the ferroin-catalysed Belousov-Zhabotinsky (BZ) oscillating reaction, which is known to evolve to characteristic chaotic transient dynamics when carried out under batch and unstirred conditions. In particular, chemical chaos was found to appear and disappear by following a Ruelle-Takens-Newhouse (RTN) scenario. Here we use medium viscosity as a bifurcation parameter to tune the reaction-diffusion-convection (RDC) interplay and force the reaction in a specific sequence of dynamical regimes: either (i) periodic → quasi-periodic → chaotic or (ii) periodic → quasi-periodic or (iii) only periodic. The medium viscosity can be set by adding different amounts of surfactant (sodium dodecyl sulphate), known to have a little impact on the reaction mechanism, above its critical micelle concentration. Experimental results are supported by means of numerical simulations of a RDC model, which combines self-sustained oscillations to the related chemically-induced buoyancy convection.
Numerical simulation of fluid particle transport through porous media
Najam, S
1999-01-01
The work presented in this report aims at the numerical simulation of fluid particle transport through porous medium. For this purpose various mathematical models and numerical schemes are studied. A mathematical model is derived based on Darcy's Law and continuity equation, it is discretized using finite difference schemes and Guass Seidal iterative procedure is used as a solver. For transient problems Crank Nicolson's method is used. Finally a software in Visual Basic 3.0 is developed that can simulate fluid transport through porous medium by promoting the user to specify the material and geometrical properties of the medium. The unknown pressure heads can be determined at various nodal points and the results are visualized by the colored grid display or by the surface plots.
Numerical Model of Radical Photopolymerization Based on Interdiffusion
Directory of Open Access Journals (Sweden)
Shuhei Yoshida
2014-01-01
Full Text Available An accurate reaction model is required to analyze the characteristics of photopolymers. For this purpose, we propose a numerical model for radical photopolymerization. In the proposed model, elementary reactions such as initiation, propagation, and termination are considered, and we assume interdiffusion for each component in the material. We analyzed the diffraction characteristics of a radical photopolymer based on the proposed interdiffusion model with the beam propagation method. Moreover, we also performed hologram-recording experiments and evaluated the diffraction characteristics of the photopolymer medium. By comparing the numerical and experimental results, medium parameters such as reaction rate and diffusion coefficient can be estimated. We confirmed that the interdiffusion model can reproduce the experimental results and showed that the medium parameters affect the diffraction characteristics.
Development of brachytherapy medium doserate
International Nuclear Information System (INIS)
Atang Susila; Ari Satmoko; Ahmad Rifai; Kristiyanti
2010-01-01
Brachytherapy has proven to be an effective treatment for different types of cancers and it become a common treatment modality in most radiotherapy clinics. PRPN has had experience in development of Low Dose Rate Brachytherapy for cervix cancer treatment. However the treatment process using LDR device needs 5 hours in time that the patient feel uncomfort. Therefore PRPN develops Medium Dose Rate Brachytherapy with radiation activity not more than 5 Currie. The project is divided into two stages. Purchasing of TPS software and TDS design are held in 2010, and the construction will be in 2011. (author)
Charmed hadrons in nuclear medium
International Nuclear Information System (INIS)
Tolos, L.; Gamermann, D.; Molina, R.; Nieves, J.; Oset, E.; Garcia-Recio, C.; Ramos, A.
2010-01-01
We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss the implications of the in-medium properties of open-charm mesons on the D s0 (2317) and the predicted X(3700) scalar resonances. (authors)
HPC Benchmark Suite NMx, Phase II
National Aeronautics and Space Administration — In the phase II effort, Intelligent Automation Inc., (IAI) and University of Central Florida (UCF) propose to develop a comprehensive numerical test suite for...
Modeling multibody systems with uncertainties. Part II: Numerical applications
Energy Technology Data Exchange (ETDEWEB)
Sandu, Corina, E-mail: csandu@vt.edu; Sandu, Adrian; Ahmadian, Mehdi [Virginia Polytechnic Institute and State University, Mechanical Engineering Department (United States)
2006-04-15
This study applies generalized polynomial chaos theory to model complex nonlinear multibody dynamic systems operating in the presence of parametric and external uncertainty. Theoretical and computational aspects of this methodology are discussed in the companion paper 'Modeling Multibody Dynamic Systems With Uncertainties. Part I: Theoretical and Computational Aspects .In this paper we illustrate the methodology on selected test cases. The combined effects of parametric and forcing uncertainties are studied for a quarter car model. The uncertainty distributions in the system response in both time and frequency domains are validated against Monte-Carlo simulations. Results indicate that polynomial chaos is more efficient than Monte Carlo and more accurate than statistical linearization. The results of the direct collocation approach are similar to the ones obtained with the Galerkin approach. A stochastic terrain model is constructed using a truncated Karhunen-Loeve expansion. The application of polynomial chaos to differential-algebraic systems is illustrated using the constrained pendulum problem. Limitations of the polynomial chaos approach are studied on two different test problems, one with multiple attractor points, and the second with a chaotic evolution and a nonlinear attractor set. The overall conclusion is that, despite its limitations, generalized polynomial chaos is a powerful approach for the simulation of multibody dynamic systems with uncertainties.
Modeling multibody systems with uncertainties. Part II: Numerical applications
International Nuclear Information System (INIS)
Sandu, Corina; Sandu, Adrian; Ahmadian, Mehdi
2006-01-01
This study applies generalized polynomial chaos theory to model complex nonlinear multibody dynamic systems operating in the presence of parametric and external uncertainty. Theoretical and computational aspects of this methodology are discussed in the companion paper 'Modeling Multibody Dynamic Systems With Uncertainties. Part I: Theoretical and Computational Aspects .In this paper we illustrate the methodology on selected test cases. The combined effects of parametric and forcing uncertainties are studied for a quarter car model. The uncertainty distributions in the system response in both time and frequency domains are validated against Monte-Carlo simulations. Results indicate that polynomial chaos is more efficient than Monte Carlo and more accurate than statistical linearization. The results of the direct collocation approach are similar to the ones obtained with the Galerkin approach. A stochastic terrain model is constructed using a truncated Karhunen-Loeve expansion. The application of polynomial chaos to differential-algebraic systems is illustrated using the constrained pendulum problem. Limitations of the polynomial chaos approach are studied on two different test problems, one with multiple attractor points, and the second with a chaotic evolution and a nonlinear attractor set. The overall conclusion is that, despite its limitations, generalized polynomial chaos is a powerful approach for the simulation of multibody dynamic systems with uncertainties
Numerical simulation for i - ii type of distribution header throttle
International Nuclear Information System (INIS)
Yuheng, Feng; Wenjun, Hu; Xuedong, Qiao; Zhifeng, Hou
2009-01-01
In the simulation of distribution header throttle structure, using the computational fluid dynamic code-CFX, compared with experiment, the reasons of error is discussed and the reliability of this simulation is proved. Authors have checked same types of calculations, particularly introduced the relationship between CFD and experiment. The results will be theoretic base and reference
Accelerated Numerical Processing API Based on GPU Technology, Phase II
National Aeronautics and Space Administration — The recent performance increases in graphics processing units (GPUs) have made graphics cards an attractive platform for implementing computationally intense...
African Journals Online (AJOL)
CLEMENT O BEWAJI
ABSTRACT: A Schiff base was prepared from the reaction of 2 - amino - 3 – methylbutanoic acid and 2, 4 - pentanedione. The reaction of the prepared Schiff base with ethanolic solution of copper (II) chloride formed diaquo bis( N – 2 – amino – 3 - methylbutyl - 2, 4 - pentanedionato) copper (II) complex. The Schiff base is ...
Saliva as a diagnostic medium.
Pink, Richard; Simek, Jiri; Vondrakova, Jana; Faber, Edgar; Michl, Petr; Pazdera, Jindrich; Indrak, Karel
2009-06-01
This is a review of current knowledge on the use of saliva, gingival cervical fluid and mucosal transudate in the detection of some oral and systemic diseases as well as drugs. Oral fluid is a diagnostic medium that can be easily collected and with minimal invasion but it has been neglected in the past. Today, saliva is being used more often to diagnose: HIV virus, oro-facial and systemic tumors, cardiovascular disease and in detecting addictive substances. Neutropil levels in saliva may also indicate successful bone marrow transplant. Oral fluid is now systematically being researched and oral fluid analysis is being compared with the analysis of other diagnostic media such as blood and urine. A number of recent studies have focused on oncogenic marker detection and its monitoring in saliva. The latest clinical and laboratory findings on diagnostic markers of oropharyngeal carcinoma in oral fluid could be the beginning of their wider use as a diagnostic medium. Oral fluid can also be also used to diagnose other malignancies such as breast cancer which was one of the first malignant tumors to be detected using genetic protein biomarkers. Raised levels of CA15-3 and the epidermal growth factor (EGF) receptor have been found in patients with breast cancer and elevated levels of CA 125 and the glycoprotein complex in the saliva of ovarian cancer patients. Doubtless, the diagnostic value of saliva, aided by current technological development will increase rapidly in the near future.
Unsaturated medium hydrocarbons pollution evaluation
International Nuclear Information System (INIS)
Di Luise, G.
1991-01-01
When the so called porous unsaturated medium, that's the vertical subsoil section between both the ground and water-table level, is interested by a hydrocarbons spill, the problem to evaluate the pollution becomes difficult: considering, essentially, the natural coexistence in it of two fluids, air and water, and the interactions between them. This paper reports that the problems tend to increase when a third fluid, the pollutant, immiscible with water, is introduced into the medium: a three-phases flow, which presents several analogies with the flow conditions present in an oil-reservoir, will be established. In such a situation, it would be very useful to handle the matter by the commonly used parameters in the oil reservoirs studies such as: residual saturation, relative permeability, phases mobility, to derive a first semiquantitative estimation of the pollution. The subsoil pollution form hydrocarbons agents is one of the worldwide more diffused causes of contamination: such events are generally referable to two main effects: accidental (oil pipeline breakdowns, e.g.), and continuous (underground tanks breaks, industrial plants leakages, e.g.)
NEW RSW & Wall Medium Fully Tetrahedral Grid
National Aeronautics and Space Administration — New Medium Fully Tetrahedral RSW Grid with viscous wind tunnel wall at the root. This grid is for a node-based unstructured solver. Medium Tet: Quad Surface Faces= 0...
Numerical simulation in astrophysics
International Nuclear Information System (INIS)
Miyama, Shoken
1985-01-01
There have been many numerical simulations of hydrodynamical problems in astrophysics, e.g. processes of star formation, supernova explosion and formation of neutron stars, and general relativistic collapse of star to form black hole. The codes are made to be suitable for computing such problems. In astrophysical hydrodynamical problems, there are the characteristics: problems of self-gravity or external gravity acting, objects of scales very large or very short, objects changing by short period or long time scale, problems of magnetic force and/or centrifugal force acting. In this paper, we present one of methods of numerical simulations which may satisfy these requirements, so-called smoothed particle methods. We then introduce the methods briefly. Then, we show one of the applications of the methods to astrophysical problem (fragmentation and collapse of rotating isothermal cloud). (Mori, K.)
Borcard, Daniel; Legendre, Pierre
2018-01-01
This new edition of Numerical Ecology with R guides readers through an applied exploration of the major methods of multivariate data analysis, as seen through the eyes of three ecologists. It provides a bridge between a textbook of numerical ecology and the implementation of this discipline in the R language. The book begins by examining some exploratory approaches. It proceeds logically with the construction of the key building blocks of most methods, i.e. association measures and matrices, and then submits example data to three families of approaches: clustering, ordination and canonical ordination. The last two chapters make use of these methods to explore important and contemporary issues in ecology: the analysis of spatial structures and of community diversity. The aims of methods thus range from descriptive to explanatory and predictive and encompass a wide variety of approaches that should provide readers with an extensive toolbox that can address a wide palette of questions arising in contemporary mul...
Borcard, Daniel; Legendre, Pierre
2018-01-01
This new edition of Numerical Ecology with R guides readers through an applied exploration of the major methods of multivariate data analysis, as seen through the eyes of three ecologists. It provides a bridge between a textbook of numerical ecology and the implementation of this discipline in the R language. The book begins by examining some exploratory approaches. It proceeds logically with the construction of the key building blocks of most methods, i.e. association measures and matrices, and then submits example data to three families of approaches: clustering, ordination and canonical ordination. The last two chapters make use of these methods to explore important and contemporary issues in ecology: the analysis of spatial structures and of community diversity. The aims of methods thus range from descriptive to explanatory and predictive and encompass a wide variety of approaches that should provide readers with an extensive toolbox that can address a wide palette of questions arising in contemporary mul...
Handbook of numerical analysis
Ciarlet, Philippe G
Mathematical finance is a prolific scientific domain in which there exists a particular characteristic of developing both advanced theories and practical techniques simultaneously. Mathematical Modelling and Numerical Methods in Finance addresses the three most important aspects in the field: mathematical models, computational methods, and applications, and provides a solid overview of major new ideas and results in the three domains. Coverage of all aspects of quantitative finance including models, computational methods and applications Provides an overview of new ideas an
Numerical Modeling of Airblast.
1987-06-01
can be found in Appendix A. TASK 2.4 The 3--D FCT code was used to study the late time cloud rise geometry from multiple nulear explosions...code was used to study the possiblity of using distributed chemical charges in array geometries. Numerous chemical energy release models where employed...relief of the blast energy at the edges of the DECA charge). Later, it was realized that the edge effects are small at the time when most of the blast
Comments on numerical simulations
International Nuclear Information System (INIS)
Sato, T.
1984-01-01
The author comments on a couple of things about numerical simulation. One is just about the philosophical discussion that is, spontaneous or driven. The other thing is the numerical or technical one. Frankly, the author didn't want to touch on the technical matter because this should be a common sense one for those who are working at numerical simulation. But since many people take numerical simulation results at their face value, he would like to remind you of the reality hidden behind them. First, he would point out that the meaning of ''driven'' in driven reconnection is different from that defined by Schindler or Akasofu. The author's definition is closer to Axford's definition. In the spontaneous case, for some unpredicted reason an excess energy of the system is suddenly released at a certain point. However, one does not answer how such an unstable state far beyond a stable limit is realized in the magnetotail. In the driven case, there is a definite energy buildup phase starting from a stable state; namely, energy in the black box increases from a stable level subject to an external source. When the state has reached a certain position, the energy is released suddenly. The difference between driven and spontaneous is whether the cause (plasma flow) to trigger reconnection is specified or reconnection is triggered unpredictably. Another difference is that in driven reconnection the reconnection rate is dependent on the speed of the external plasma flow, but in spontaneous reconnection the rate is dependent on the internal condition such as the resistivity
Hybrid undulator numerical optimization
Energy Technology Data Exchange (ETDEWEB)
Hairetdinov, A.H. [Kurchatov Institute, Moscow (Russian Federation); Zukov, A.A. [Solid State Physics Institute, Chernogolovka (Russian Federation)
1995-12-31
3D properties of the hybrid undulator scheme arc studied numerically using PANDIRA code. It is shown that there exist two well defined sets of undulator parameters which provide either maximum on-axis field amplitude or minimal higher harmonics amplitude of the basic undulator field. Thus the alternative between higher field amplitude or pure sinusoidal field exists. The behavior of the undulator field amplitude and harmonics structure for a large set of (undulator gap)/(undulator wavelength) values is demonstrated.
Liou, Meng-Sing
2013-11-01
The development of computational fluid dynamics over the last few decades has yielded enormous successes and capabilities that are being routinely employed today; however there remain some open problems to be properly resolved. One example is the so-called overheating problem, which can arise in two very different scenarios, from either colliding or receding streams. Common in both is a localized, numerically over-predicted temperature. Von Neumann reported the former, a compressive overheating, nearly 70 years ago and numerically smeared the temperature peak by introducing artificial diffusion. However, the latter is unphysical in an expansive (rarefying) situation; it still dogs every method known to the author. We will present a study aiming at resolving this overheating problem and we find that: (1) the entropy increase is one-to-one linked to the increase in the temperature rise and (2) the overheating is inevitable in the current computational fluid dynamics framework in practice. Finally we will show a simple hybrid method that fundamentally cures the overheating problem in a rarefying flow, but also retains the property of accurate shock capturing. Moreover, this remedy (enhancement of current numerical methods) can be included easily in the present Eulerian codes. This work is performed under NASA's Fundamental Aeronautics Program.
Secure data storage by three-dimensional absorbers in highly scattering volume medium
International Nuclear Information System (INIS)
Matoba, Osamu; Matsuki, Shinichiro; Nitta, Kouichi
2008-01-01
A novel data storage in a volume medium with highly scattering coefficient is proposed for data security application. Three-dimensional absorbers are used as data. These absorbers can not be measured by interferometer when the scattering in a volume medium is strong enough. We present a method to reconstruct three-dimensional absorbers and present numerical results to show the effectiveness of the proposed data storage.
A new benchmark reference solution for double-diffusive convection in a heterogeneous porous medium
Shao, Q.; Fahs, M.; Younes, Anis; Makradi, A.; Mara, T.
2016-01-01
A new benchmark with a high accurate solution is proposed for the verification of numerical codes dealing with double-diffusive convection in a heterogeneous porous medium. The new benchmark is inspired by the popular problem of square porous cavity by assuming a stratified porous medium. A high accurate steady state solution is developed using the Fourier-Galerkin method. To this aim, the unknowns are expanded in double infinite Fourier series. The accuracy of the developed solution is asses...
Mapping of moveout in a TTI medium
Stovas, A.
2012-01-01
To compute moveout in a transversely isotropic medium with tilted symmetry axis is a very complicated problem. We propose to split this problem into two parts. First, to compute the moveout in a corresponding VTI medium. Second, to map the computed moveout to a TTI medium.
27 CFR 19.914 - Medium plants.
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Medium plants. 19.914... OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Distilled Spirits For Fuel Use Permits § 19.914 Medium plants. Any person wishing to establish a medium plant shall make application for and obtain in...
Optimization of medium composition for apple rootstocks
African Journals Online (AJOL)
User
2011-05-02
May 2, 2011 ... work of MS medium was also empirical and was deve- loped to optimise the mineral composition of the medium for growth of tobacco callus. A subsequent development such as Woody Plant Medium (WPM) (Lloyd and. McCown, 1981) was based on this previous process. 6-Benzylaminopurine (BA) and ...
Il concetto di medium artistico: Richard Wollheim interprete di Ludwig Wittgenstein
Maistrello, Andrea
2016-01-01
The aim of the dissertation is twofold: (i) analyzing the notion (well known by aestheticians, but not so intensively studied) of artistic medium; (ii) showing the relevance of such notion for aesthetics through the examination of some relevant aspects of Richard Wollheim’s philosophy of art, maybe the main figure in Anglo-American philosophy as for considering artistic medium central in art-theorizing. Artistic media, according to Wollheim, can develop only if properly connected to a cultura...
Bovo, R; Galesi, A L L; Jorge, S A C; Piccoli, R A M; Moraes, A M; Pereira, C A; Augusto, E F P
2008-05-01
In the past few years, Drosophila melanogaster cells have been employed for recombinant protein production purposes, and a comprehensive knowledge of their metabolism is essential for process optimization. In this work, the kinetic response of a Schneider S2 cell line, grown in shake flasks, in two different culture media, the serum-free SF900-II((R)) and the serum-supplemented TC-100, was evaluated. Cell growth, amino acids and glucose uptake, and lactate synthesis were measured allowing the calculation of kinetic parameters. The results show that S2 cells metabolism was able to adjust to different environmental situations, as determined by medium formulation, as well as by the particular situation resulting from the culture conditions. Cells attained a 163% higher final cell concentration (1.4 x 10(7) cells mL(-1)) in SF900 II((R)) medium, when compared to serum-supplemented TC-100 medium. Also, a maximum specific cell growth rate 52% higher in SF900 II((R) )medium, when compared to serum-supplemented TC-100 one, was observed. Glutamine was the growth limiting factor in SF900 II((R)) medium, while glucose, sometimes associated with glutamine, controlled growth in serum-supplemented TC-100 medium based formulation. The different pattern of lactate production is an example of the versatility of the metabolism of these cells. This by-product was produced only in glutamine limitation, but the amount synthesized depended not only on the excess glucose, but on other medium components. Therefore, in serum-supplemented TC-100 medium a much smaller lactate amount was generated. Besides, glucose was identified not only as a growth limiting factor, but also as a viability limiting factor, since its depletion accelerated cell death.
Burden, Natalie; Aschberger, Karin; Chaudhry, Qasim; Clift, Martin J D; Fowler, Paul; Johnston, Helinor; Landsiedel, Robert; Rowland, Joanna; Stone, Vicki; Doak, Shareen H
2017-12-01
Nanomaterials convey numerous advantages, and the past decade has seen a considerable rise in their development and production for an expanse of applications. While the potential advantages of nanomaterials are clear, concerns over the impact of human and environmental exposure exist. Concerted, science-led efforts are required to understand the effects of nanomaterial exposure and ensure that protection goals are met. There is much on-going discussion regarding how best to assess nanomaterial risk, particularly considering the large number of tests that may be required. A plethora of forms may need to be tested for each nanomaterial, and risk assessed throughout the life cycle, meaning numerous acute and chronic toxicity studies could be required, which is neither practical nor utilises the current evidence-base. Hence, there are scientific, business, ethical and legislative drivers to re-consider the use of animal toxicity tests. An expert Working Group of regulators, academics and industry scientists were gathered by the UK's NC3Rs to discuss: i) opportunities being offered in the short, medium and long-terms to advance nanosafety, ii) how to align these advances with the application of the 3Rs in nanomaterial safety testing, and iii) shifting the focus of risk assessment from current hazard-based approaches towards exposure-driven approaches. Copyright © 2017. Published by Elsevier Inc.
Refractive and diffractive scattering in the interstellar medium
International Nuclear Information System (INIS)
Cordes, J.M.; Pidwerbetsky, A.; Lovelace, R.V.E.
1986-01-01
Radio wave propagation through electron-density fluctuations in the ISM is studied. Observable propagation effects are explored using a one-dimensional thin-screen model for the turbulent medium. Diffraction caused by stochastic small-scale irregularities is combined with refraction from deterministic large-scale irregularities. Some of the effects are illustrated with numerical simulations of the wave propagation. Multiple imaging is considered, delineating the possible effects and discussing their extensions to two-dimensional screens and extended three-dimensional media. The case where refraction as well as diffraction is caused by a stochastic medium with a spectrum of a given form is considered. The magnitudes of observable effects is estimated for representative spectra that may be relevant to the ISM. The importance of the various effects for timing and scintillation observations of pulsars, VLBI observations of galactic and extragalactic radio sources, and for variability measurements of extragalactic sources is assessed. 47 references
Analysis of photonic band-gap structures in stratified medium
DEFF Research Database (Denmark)
Tong, Ming-Sze; Yinchao, Chen; Lu, Yilong
2005-01-01
Purpose - To demonstrate the flexibility and advantages of a non-uniform pseudo-spectral time domain (nu-PSTD) method through studies of the wave propagation characteristics on photonic band-gap (PBG) structures in stratified medium Design/methodology/approach - A nu-PSTD method is proposed...... in solving the Maxwell's equations numerically. It expands the temporal derivatives using the finite differences, while it adopts the Fourier transform (FT) properties to expand the spatial derivatives in Maxwell's equations. In addition, the method makes use of the chain-rule property in calculus together...... with the transformed space technique in order to make the algorithm flexible in terms of non-uniform spatial sampling. Findings - Through the studies of the wave propagation characteristics on PBG structures in stratified medium, it has been found that the proposed method retains excellent accuracy in the occasions...
A direct sampling method for inverse electromagnetic medium scattering
Ito, Kazufumi
2013-09-01
In this paper, we study the inverse electromagnetic medium scattering problem of estimating the support and shape of medium scatterers from scattered electric/magnetic near-field data. We shall develop a novel direct sampling method based on an analysis of electromagnetic scattering and the behavior of the fundamental solution. It is applicable to a few incident fields and needs only to compute inner products of the measured scattered field with the fundamental solutions located at sampling points. Hence, it is strictly direct, computationally very efficient and highly robust to the presence of data noise. Two- and three-dimensional numerical experiments indicate that it can provide reliable support estimates for multiple scatterers in the case of both exact and highly noisy data. © 2013 IOP Publishing Ltd.
Generalized Effective Medium Theory for Particulate Nanocomposite Materials
Siddiqui, Muhammad Usama; Arif, Abul Fazal M.
2016-01-01
The thermal conductivity of particulate nanocomposites is strongly dependent on the size, shape, orientation and dispersion uniformity of the inclusions. To correctly estimate the effective thermal conductivity of the nanocomposite, all these factors should be included in the prediction model. In this paper, the formulation of a generalized effective medium theory for the determination of the effective thermal conductivity of particulate nanocomposites with multiple inclusions is presented. The formulated methodology takes into account all the factors mentioned above and can be used to model nanocomposites with multiple inclusions that are randomly oriented or aligned in a particular direction. The effect of inclusion dispersion non-uniformity is modeled using a two-scale approach. The applications of the formulated effective medium theory are demonstrated using previously published experimental and numerical results for several particulate nanocomposites. PMID:28773817
Generalized Effective Medium Theory for Particulate Nanocomposite Materials
Directory of Open Access Journals (Sweden)
Muhammad Usama Siddiqui
2016-08-01
Full Text Available The thermal conductivity of particulate nanocomposites is strongly dependent on the size, shape, orientation and dispersion uniformity of the inclusions. To correctly estimate the effective thermal conductivity of the nanocomposite, all these factors should be included in the prediction model. In this paper, the formulation of a generalized effective medium theory for the determination of the effective thermal conductivity of particulate nanocomposites with multiple inclusions is presented. The formulated methodology takes into account all the factors mentioned above and can be used to model nanocomposites with multiple inclusions that are randomly oriented or aligned in a particular direction. The effect of inclusion dispersion non-uniformity is modeled using a two-scale approach. The applications of the formulated effective medium theory are demonstrated using previously published experimental and numerical results for several particulate nanocomposites.
Generalized Effective Medium Theory for Particulate Nanocomposite Materials.
Siddiqui, Muhammad Usama; Arif, Abul Fazal M
2016-08-13
The thermal conductivity of particulate nanocomposites is strongly dependent on the size, shape, orientation and dispersion uniformity of the inclusions. To correctly estimate the effective thermal conductivity of the nanocomposite, all these factors should be included in the prediction model. In this paper, the formulation of a generalized effective medium theory for the determination of the effective thermal conductivity of particulate nanocomposites with multiple inclusions is presented. The formulated methodology takes into account all the factors mentioned above and can be used to model nanocomposites with multiple inclusions that are randomly oriented or aligned in a particular direction. The effect of inclusion dispersion non-uniformity is modeled using a two-scale approach. The applications of the formulated effective medium theory are demonstrated using previously published experimental and numerical results for several particulate nanocomposites.
International Nuclear Information System (INIS)
Vogelweith, L.; Lavergne, J.C.; Martinot, G.; Weiss, A.
1977-01-01
CEA (TECHNICATOME) has developed a range of pressurized water reactors of the type ''CAS compact'' which are adapted to civil ship propulsion, or to electric power production, combined possibly with heat production, up to outputs equivalent to 125 MWe. Nuclear plants equipped with these reactors are suitable to medium-size electric networks. Among the possible realizations, two types of plants are mentioned as examples: 1) Floating electron-nuclear plants; and 2) Combined electric power and desalting plants. The report describes the design characteristics of the different parts of a 125 MWe unit floating electro-nuclear plant: nuclear steam system CAS 3 G, power generating plant, floating platform for the whole plant. The report gives attention to the different possibilities according to site conditions (the plant can be kept floating, in a natural or artificial basin, it can be put aground, ...) and to safety and environment factors. Such unit can be used in places where there is a growing demand in electric power and fresh water. The report describes how the reactor, the power generating plant and multiflash distillation units of an electric power-desalting plant can be combined: choice of the ratio water output/electric power output, thermal cycle combination, choice of the gain ratio, according to economic considerations, and to desired goal of water output. The report analyses also some technical options, such as: choice of the extraction point of steam used as heat supply of the desalting station (bleeding a condensation turbine, or recovering steam at the exhaust of a backpressure turbine), design making the system safe. Lastly, economic considerations are dealt with: combining the production of fresh water and electric power provides usually a much better energy balance and a lower cost for both products. Examples are given of some types of installations which combine medium-size reactors with fresh water stations yielding from 10000 to 120000 m 3 per day
Henderson, Michael
1997-08-01
The Numerical Analysis Objects project (NAO) is a project in the Mathematics Department of IBM's TJ Watson Research Center. While there are plenty of numerical tools available today, it is not an easy task to combine them into a custom application. NAO is directed at the dual problems of building applications from a set of tools, and creating those tools. There are several "reuse" projects, which focus on the problems of identifying and cataloging tools. NAO is directed at the specific context of scientific computing. Because the type of tools is restricted, problems such as tools with incompatible data structures for input and output, and dissimilar interfaces to tools which solve similar problems can be addressed. The approach we've taken is to define interfaces to those objects used in numerical analysis, such as geometries, functions and operators, and to start collecting (and building) a set of tools which use these interfaces. We have written a class library (a set of abstract classes and implementations) in C++ which demonstrates the approach. Besides the classes, the class library includes "stub" routines which allow the library to be used from C or Fortran, and an interface to a Visual Programming Language. The library has been used to build a simulator for petroleum reservoirs, using a set of tools for discretizing nonlinear differential equations that we have written, and includes "wrapped" versions of packages from the Netlib repository. Documentation can be found on the Web at "http://www.research.ibm.com/nao". I will describe the objects and their interfaces, and give examples ranging from mesh generation to solving differential equations.
Effective Medium Theory for Anisotropic Metamaterials
Zhang, Xiujuan
2017-11-12
This dissertation includes the study of effective medium theories (EMTs) and their applications in describing wave propagation in anisotropic metamaterials, which can guide the design of metamaterials. An EMT based on field averaging is proposed to describe a peculiar anisotropic dispersion relation that is linear along the symmetry line but quadratic in the perpendicular direction. This dispersion relation is associated with the topological transition of the iso-frequency contours (IFCs), suggesting interesting wave propagation behaviors from beam shaping to beam splitting. In the framework of coherent potential approximation, an analytical EMT is further developed, with the ability to build a direct connection between the microscopic structure and the macroscopic material properties, which overcomes the requirement of prior knowledge of the field distributions. The derived EMT is valid beyond the long-wavelength limit. Using the EMT, an anisotropic zero-index metamaterial is designed. Moreover, the derived EMT imposes a condition that no scattered wave is generated in the ambient medium, which suggests the input signal cannot detect any object that might exist, making it invisible. Such correspondence between the EMT and the invisibilityinspires us to explore the wave cloaking in the same framework of coherent potential approximation. To further broaden the application realm of EMT, an EMT using the parameter retrieval method is studied in the regimes where the previously-developed EMTs are no longer accurate. Based on this study, in conjunction with the EMT mentioned above, a general scheme to realize coherent perfect absorption (CPA) in anisotropic metamaterials is proposed. As an exciting area in metamaterials, the field of metasurfaces has drawn great attention recently. As an easily attainable device, a grating may be the simplest version of metasurfaces. Here, an analytical EMT for gratings made of cylinders is developed by using the multiple scattering
Effect of switching-off of a plasma medium on a traveling wave
International Nuclear Information System (INIS)
Kalluri, D.K.
1989-01-01
It is known that a sudden creation of a plasma medium of plasma frequency ω ρ splits a traveling wave of frequency ω o into two new waves of frequencies. The negative value for the frequency here indicates a reflected wave. The effect of a sudden collapse of the plasma medium, on a travelling wave of frequency ω o is shown to be the creation of two new waves of frequencies. A numerical solution is obtained for the case of a gradual collapse of the plasma medium. For the case of a slow decay of the particle density an approximate WKB type solution is obtained. Several results are presented
Medium effect on the characteristics of the coupled seismic and electromagnetic signals.
Huang, Qinghua; Ren, Hengxin; Zhang, Dan; Chen, Y John
2015-01-01
Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structure is more complicated than that for a simple uniform structure. Different from the seismic signals, the electromagnetic signals are sensitive to the medium properties such as fluid salinity and fluid viscosity. Therefore, the co-seismic electromagnetic signals may be more informative than seismic signals.
Tattoo: a multifaceted medium of communication
Directory of Open Access Journals (Sweden)
Christian Wymann
2010-11-01
Full Text Available This article suggests the systems theoretical distinction of form/medium as a useful tool for distinguishing social phenomena that might look as if they stem from the same process. This is shown to be the case for the tattoo and tattooing. The tattoo is conceived as a medium of communication through which different forms of communication emerge. Tattooing is one of these forms of communication that shapes the medium in a particular way. The current article sheds a special light on its intricate, communicational constellation, for which the concept of parallax is suggested. Law, medicine and cosmetics as other forms of communication use the medium of tattoo in their own way as well. The form/medium distinction allows us to grasp these different forms of communication, while it shows that they share the tattoo as medium. The article’s ultimate goal is to illustrate that the tattoo figures as a multifaceted medium of communication.
Milner, P; Batten, J E; Curtis, M A
1996-07-01
The aim of this study was the development of a simple, defined medium for the growth of laboratory and clinical isolates of Porphyromonas gingivalis. A medium was designed in which the carbon and nitrogen requirements were provided by a single protein source--bovine serum albumin. High cell yields were achieved in this medium but growth was accompanied by a heavy blackening of the cells due to the deposition of metal sulfide(s), most probably iron(II) sulfide, at the cell surface. Good growth in the absence of blackening was achieved when the iron salt in the medium was substituted with alpha-ketoglutarate. The resultant alpha-ketoglutarate/BSA medium was able to support the growth of all laboratory and clinical P. gingivalis strains examined and should prove useful in the investigation of the physiology and nutritional regulation of virulence of this organism.
Numerical differential protection
Ziegler, Gerhard
2012-01-01
Differential protection is a fast and selective method of protection against short-circuits. It is applied in many variants for electrical machines, trans?formers, busbars, and electric lines.Initially this book covers the theory and fundamentals of analog and numerical differential protection. Current transformers are treated in detail including transient behaviour, impact on protection performance, and practical dimensioning. An extended chapter is dedicated to signal transmission for line protection, in particular, modern digital communication and GPS timing.The emphasis is then pla
Arvo, James
1991-01-01
Graphics Gems II is a collection of articles shared by a diverse group of people that reflect ideas and approaches in graphics programming which can benefit other computer graphics programmers.This volume presents techniques for doing well-known graphics operations faster or easier. The book contains chapters devoted to topics on two-dimensional and three-dimensional geometry and algorithms, image processing, frame buffer techniques, and ray tracing techniques. The radiosity approach, matrix techniques, and numerical and programming techniques are likewise discussed.Graphics artists and comput
Medium-Based Design: Extending a Medium to Create an Exploratory Learning Environment
Rick, Jochen; Lamberty, K. K.
2005-01-01
This article introduces "medium-based" design -- an approach to creating "exploratory learning environments" using the method of "extending a medium". First, the characteristics of exploratory learning environments and medium-based design are described and grounded in related work. Particular attention is given to "extending a medium" --…
Realization of a complementary medium using dielectric photonic crystals.
Xu, Tao; Fang, Anan; Jia, Ziyuan; Ji, Liyu; Hang, Zhi Hong
2017-12-01
By exploiting the scaling invariance of photonic band diagrams, a complementary photonic crystal slab structure is realized by stacking two uniformly scaled double-zero-index dielectric photonic crystal slabs together. The space cancellation effect in complementary photonic crystals is demonstrated in both numerical simulations and microwave experiments. The refractive index dispersion of double-zero-index dielectric photonic crystal is experimentally measured. Using pure dielectrics, our photonic crystal structure will be an ideal platform to explore various intriguing properties related to a complementary medium.
Analysis of photonic band-gap structures in stratified medium
DEFF Research Database (Denmark)
Tong, Ming-Sze; Yinchao, Chen; Lu, Yilong
2005-01-01
in solving the Maxwell's equations numerically. It expands the temporal derivatives using the finite differences, while it adopts the Fourier transform (FT) properties to expand the spatial derivatives in Maxwell's equations. In addition, the method makes use of the chain-rule property in calculus together...... in electromagnetic and microwave applications once the Maxwell's equations are appropriately modeled. Originality/value - The method validates its values and properties through extensive studies on regular and defective 1D PBG structures in stratified medium, and it can be further extended to solving more...
Data acquisition system for medium power neutral beam test facility
International Nuclear Information System (INIS)
Stewart, C.R. Jr.; Francis, J.E. Jr.; Hammons, C.E.; Dagenhart, W.K.
1978-06-01
The Medium Power Neutral Beam Test Facility at Oak Ridge National Laboratory was constructed in order to develop, test, and condition powerful neutral beam lines for the Princeton Large Torus experiment at Princeton Plasma Physics Laboratory. The data acquisition system for the test stand monitors source performance, beam characteristics, and power deposition profiles to determine if the beam line is operating up to its design specifications. The speed of the computer system is utilized to provide near-real-time analysis of experimental data. Analysis of the data is presented as numerical tabulation and graphic display
A direct sampling method to an inverse medium scattering problem
Ito, Kazufumi
2012-01-10
In this work we present a novel sampling method for time harmonic inverse medium scattering problems. It provides a simple tool to directly estimate the shape of the unknown scatterers (inhomogeneous media), and it is applicable even when the measured data are only available for one or two incident directions. A mathematical derivation is provided for its validation. Two- and three-dimensional numerical simulations are presented, which show that the method is accurate even with a few sets of scattered field data, computationally efficient, and very robust with respect to noises in the data. © 2012 IOP Publishing Ltd.
Propagation of shear wave in nonlinear and dissipative medium
International Nuclear Information System (INIS)
Jeambrun, D.
1995-01-01
The civil engineering projects, like nuclear installations, submitted to vibrations or seismic motions, require the study of the soil behaviour underlying the site under intensive dynamic loading. In order to understand in depth the soil damping phenomenon, a propagation of a shear seismic wave in a dissipative medium has been numerically simulated. The computer code, based on a nonlinear hysteretic model using Newmark-Wilson and Newton-Raphson algorithms and variable spatial steps, passes through the difficulties related to acceleration discontinuities. The simulation should allow the identification of the soil parameters by comparison with in situ measures. (author)
Energy Technology Data Exchange (ETDEWEB)
Thiessen, H.A.
1982-08-01
The present conception of LAMPF II is a high-intensity 16-GeV synchrotron injected by the LAMPF 800-MeV H/sup -/ beam. The proton beam will be used to make secondary beams of neutrinos, muons, pions, kaons, antiprotons, and hyperons more intense than those of any existing or proposed accelerator. For example, by taking maximum advantage of a thick target, modern beam optics, and the LAMPF II proton beam, it will be possible to make a negative muon beam with nearly 100% duty factor and nearly 100 times the flux of the existing Stopped Muon Channel (SMC). Because the unique features of the proposed machine are most applicable to beams of the same momentum as LAMPF (that is, < 2 GeV/c), it may be possible to use most of the experimental areas and some of the auxiliary equipment, including spectrometers, with the new accelerator. The complete facility will provide improved technology for many areas of physics already available at LAMPF and will allow expansion of medium-energy physics to include kaons, antiprotons, and hyperons. When LAMPF II comes on line in 1990 LAMPF will have been operational for 18 years and a major upgrade such as this proposal will be reasonable and prudent.
Fast Numerical Methods for Stochastic Partial Differential Equations
2016-04-15
applicable SPDES with efficient numerical methods . This project is intended to address the numerical analysis as well as algorithm aspects of SPDES. Three...no. 1, 784–804. 10. Cao, Yanzhao; Wang, Peng; Wang, Xiaoshen Homotopy continuation methods for stochastic two-point boundary value problems driven by...convergence analysis of Quasi Monte Carlo based Particle Swarm Optimization (PSO) method ; ii) Efficient adaptive domain sparse grid method for SPDES; iii
Confidence in Numerical Simulations
International Nuclear Information System (INIS)
Hemez, Francois M.
2015-01-01
This PowerPoint presentation offers a high-level discussion of uncertainty, confidence and credibility in scientific Modeling and Simulation (M&S). It begins by briefly evoking M&S trends in computational physics and engineering. The first thrust of the discussion is to emphasize that the role of M&S in decision-making is either to support reasoning by similarity or to ''forecast,'' that is, make predictions about the future or extrapolate to settings or environments that cannot be tested experimentally. The second thrust is to explain that M&S-aided decision-making is an exercise in uncertainty management. The three broad classes of uncertainty in computational physics and engineering are variability and randomness, numerical uncertainty and model-form uncertainty. The last part of the discussion addresses how scientists ''think.'' This thought process parallels the scientific method where by a hypothesis is formulated, often accompanied by simplifying assumptions, then, physical experiments and numerical simulations are performed to confirm or reject the hypothesis. ''Confidence'' derives, not just from the levels of training and experience of analysts, but also from the rigor with which these assessments are performed, documented and peer-reviewed.
Directory of Open Access Journals (Sweden)
Aden Evens
2009-01-01
Full Text Available Problematic at best, the desire for a transparent interface nevertheless drives much of digital culture and technology. But not the Web; or at least, not Web 1.0. Thoroughly commercialized, comfortably parsed into genres, serving billions of pages of predigested content to passive consumers, the World Wide Web as developed in the '90s unabashedly embraces its role as medium. While so many digital technologies work to hide their mediacy--drawing in the user with a total simulated sensorium, dematerializing the resistances of size and weight, untangling the knots of cables tying user to machine and machine to cubicle, minimizing the interface--Web 1.0 proudly clings to the browser as a glaring reminder of its medial character. While Web 2.0 has not forsaken the browser altogether, it nevertheless seems to offer a different sort of mediation. Arising alongside the atomization of browser functions, the ubiquitization of connectivity, and the coincidence of producer and user, Web 2.0 retains the form of a medium while reaching for the experiential logic of immediacy. This is not the immediacy of the transparent interface; rather, Web 2.0 effects an immediate relationship between the individual and culture. The interface does not disappear, but its mediacy is subsumed under the general form of cultural participation. Focusing on the "version upgrade" from Web 1.0 to 2.0, this essay will explore the implications for mediacy of this transition, noting that the fantasy of immediacy which drives Web 2.0 is layered and complex. The typical account of immediacy proposes to eliminate the interface and so construct a virtual reality (VR. But Web 2.0 mostly sidesteps the virtual, propelled instead by a fantasy of intuition in which the Web already knows what you want because it is you. Crucially, fantasies about the digital are effective: the computer's futurity inhabits our world, finding its expression in politics, advertising, budgeting, strategic planning
Numerical Simulation of Magnetic Nanoparticles Injection into Two–phase Flow in a Porous Medium
El-Amin, Mohamed
2017-06-09
In this paper, the problem of magnetic nanoparticles injection into a water–oil two–phase flow under an external permanent magnetic field is investigated. The mathematical model of the problem under consideration has been developed. We treat the water-nanoparticles suspension as a miscible mixture while it is immiscible with the oil phase. The magnetized phase pressure includes an additional pressure term with the conventional thermodynamic pressure. The countercurrent imbibition flow problem is taken as an example. Physical variables including water–nanoparticles suspension saturation, nanoparticles concentration, and pore wall/throat deposited nanoparticles are investigated under the influence of the magnetic field.
Numerical assessment of the origin of deep salinity in a low permeability fractured medium
International Nuclear Information System (INIS)
Guimera, Jordi; Ruiz, Eduardo; Luna, Miguel; Arcos, David; Domenech, Cristina; Jordana, Salvador; Saegusa, Hiromitsu; Iwatsuki, Teruki
2007-01-01
Many possible origins have been proposed for the saline groundwater observed in many deep geological environments. In particular, samples obtained from deep boreholes located in granite at the Mizunami Underground Research Laboratory in Central Japan show total dissolved solids increasing to 50 mmol/L at depths below 800 m. Different hypothesis have been formulated to explain the observed fluid composition, among them, long-term water-rock interaction, mixing with residual fluids of magmatic origin and relict seawater dating from Miocene times. A review of the hydrochemical and isotopic data suggests that the three above hypotheses may be valid, at least to different degrees, or that processes acting over more recent geological times may be involved. The origin of the salinity was assessed by simulating land emersion by means of changing the upper recharge boundary. In this manner the Miocene seawater was modeled as being continually mixed with fresh water until the present time. The effects of different retardation processes were considered by varying factors such as matrix diffusion and fracture conductivity. Finally, geochemical reactions reproduced trends in major ions and master variables. This study shows that the salinity observed in the boreholes can be explained qualitatively as residual Miocene age seawater subjected to alteration due to long-term contact with the host material and continuous mixing with meteoric groundwater. (authors)
Castro Heredia, L. M.; Suarez, F. I.; Fernandez, B.; Maass, T.
2016-12-01
For forecasting of water resources, weather outputs provide a valuable source of information which is available online. Compared to traditional ground-based meteorological gauges, weather forecasts data offer spatially and temporally continuous data not yet evaluated and used in the forecasting of water resources in mountainous regions in Chile. Nevertheless, the use of this non-conventional data has been limited or null in developing countries, basically because of the spatial resolution, despite the high potential in the management of water resources. The adequate incorporation of these data in hydrological models requires its evaluation while taking into account the features of river basins in mountainous regions. This work presents an integrated forecasting system which represents a radical change in the way of making the streamflow forecasts in Chile, where the snowmelt forecast is the principal component of water resources management. The integrated system is composed of a physically based hydrological model, which is the prediction tool itself, together with a methodology for remote sensing data gathering that allows feed the hydrological model in real time, and meteorological forecasts from NCEP-CFSv2. Previous to incorporation of meteorological forecasts into the hydrological model, the weather outputs were evaluated and downscaling using statistical downscaling methods. The hydrological forecasts were evaluated in two mountain basins in Chile for a term of six months for the snowmelt period. In every month an assimilation process was performed, and the hydrological forecast was improved. Each month, the snow cover area (from remote sensing) and the streamflow observed were used to assimilate the model parameters in order to improve the next hydrological forecast using meteorological forecasts. The operation of the system in real time shows a good agreement between the streamflow and the snow cover area observed. The hydrological model and the weather outputs were useful to predict the streamflow observed in the entire snowmelt season.
A two-stage method for inverse medium scattering
Ito, Kazufumi
2013-03-01
We present a novel numerical method to the time-harmonic inverse medium scattering problem of recovering the refractive index from noisy near-field scattered data. The approach consists of two stages, one pruning step of detecting the scatterer support, and one resolution enhancing step with nonsmooth mixed regularization. The first step is strictly direct and of sampling type, and it faithfully detects the scatterer support. The second step is an innovative application of nonsmooth mixed regularization, and it accurately resolves the scatterer size as well as intensities. The nonsmooth model can be efficiently solved by a semi-smooth Newton-type method. Numerical results for two- and three-dimensional examples indicate that the new approach is accurate, computationally efficient, and robust with respect to data noise. © 2012 Elsevier Inc.
2011-09-28
...) * * * (4) * * * (ii) Calculate the equivalent fuel consumption test group results as follows for spark... (gallons per 100 mile). * * * * * (c) * * * (4) * * * (ii) Calculate equivalent fuel consumption FCL values... standards for medium- and heavy-duty engines and vehicles, as prescribed under the Energy Independence and...
Dust in the interplanetary medium
Energy Technology Data Exchange (ETDEWEB)
Mann, Ingrid; Lamy, Herve [Belgian Institute for Space Aeronomy, Brussels (Belgium); Czechowski, Andrzej [Space Research Center, Polish Academy of Sciences, Warsaw (Poland); Meyer-Vernet, Nicole; Zaslavsky, Arnaud, E-mail: ingrid.mann@aeronomie.b [LESIA, Observatoire de Paris, Meudon (France)
2010-12-15
The mass density of dust particles that form from asteroids and comets in the interplanetary medium of the solar system is, near 1 AU, comparable to the mass density of the solar wind. It is mainly contained in particles of micrometer size and larger. Dust and larger objects are destroyed by collisions and sublimation and hence feed heavy ions into the solar wind and the solar corona. Small dust particles are present in large number and as a result of their large charge to mass ratio deflected by electromagnetic forces in the solar wind. For nanodust particles of sizes {approx_equal}1-10 nm, recent calculations show trapping near the Sun and outside from about 0.15 AU ejection with velocities close to solar wind velocity. The fluxes of ejected nanodust are detected near 1 AU with the plasma wave instrument onboard the STEREO spacecraft. Although such electric signals have been observed during dust impacts before, the interpretation depends on several different parameters and data analysis is still in progress.
Studies in medium energy physics
International Nuclear Information System (INIS)
Green, A.; Hoffmann, G.W.; McDonough, J.; Purcell, M.J.; Ray, R.L.; Read, D.E.; Worn, S.D.
1991-12-01
This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics
The interstellar medium in galaxies
1997-01-01
It has been more than five decades ago that Henk van de Hulst predicted the observability of the 21-cm line of neutral hydrogen (HI ). Since then use of the 21-cm line has greatly improved our knowledge in many fields and has been used for galactic structure studies, studies of the interstellar medium (ISM) in the Milky Way and other galaxies, studies of the mass distribution of the Milky Way and other galaxies, studies of spiral struc ture, studies of high velocity gas in the Milky Way and other galaxies, for measuring distances using the Tully-Fisher relation etc. Regarding studies of the ISM, there have been a number of instrumen tal developments over the past decade: large CCD's became available on optical telescopes, radio synthesis offered sensitive imaging capabilities, not only in the classical 21-cm HI line but also in the mm-transitions of CO and other molecules, and X-ray imaging capabilities became available to measure the hot component of the ISM. These developments meant that Milky Way was n...
Testability of numerical systems
International Nuclear Information System (INIS)
Soulas, B.
1992-01-01
In order to face up to the growing complexity of systems, the authors undertook to define a new approach for the qualification of systems. This approach is based on the concept of Testability which, supported by system modelization, validation and verification methods and tools, would allow Integrated Qualification process, applied throughout the life-span of systems. The general principles of this approach are introduced in the general case of numerical systems; in particular, this presentation points out the difference between the specification activity and the modelization and validation activity. This approach is illustrated firstly by the study of a global system and then by case of communication protocol as the software point of view. Finally MODEL which support this approach is described. MODEL tool is a commercial tool providing modelization and validation techniques based on Petri Nets with triple extension: Predicate/Transition, Timed and Stochastic Petri Nets
Using PASCAL for numerical analysis
Volper, D.; Miller, T. C.
1978-01-01
The data structures and control structures of PASCAL enhance the coding ability of the programmer. Proposed extensions to the language further increase its usefulness in writing numeric programs and support packages for numeric programs.
Computing the Alexander Polynomial Numerically
DEFF Research Database (Denmark)
Hansen, Mikael Sonne
2006-01-01
Explains how to construct the Alexander Matrix and how this can be used to compute the Alexander polynomial numerically.......Explains how to construct the Alexander Matrix and how this can be used to compute the Alexander polynomial numerically....
Medium of Instruction in Thai Science Learning
Chanjavanakul, Natpat
The goal of this study is to compare classroom discourse in Thai 9th grade science lessons with English or Thai as a medium of instruction. This is a cross-sectional study of video recordings from five lessons in an English-medium instruction class and five lessons in a Thai- medium instruction class from a Thai secondary school. The study involved two teachers and two groups of students. The findings show the use of both English and Thai in English-medium lessons. Students tend to be more responsive to teacher questions in Thai than in English. The findings suggest the use of students' native language during English-medium lessons to help facilitate learning in certain situations. Additionally, the study provides implications for research, practice and policy for using English as a medium of instruction.
Numerical simulation in applied geophysics
Santos, Juan Enrique
2016-01-01
This book presents the theory of waves propagation in a fluid-saturated porous medium (a Biot medium) and its application in Applied Geophysics. In particular, a derivation of absorbing boundary conditions in viscoelastic and poroelastic media is presented, which later is employed in the applications. The partial differential equations describing the propagation of waves in Biot media are solved using the Finite Element Method (FEM). Waves propagating in a Biot medium suffer attenuation and dispersion effects. In particular the fast compressional and shear waves are converted to slow diffusion-type waves at mesoscopic-scale heterogeneities (on the order of centimeters), effect usually occurring in the seismic range of frequencies. In some cases, a Biot medium presents a dense set of fractures oriented in preference directions. When the average distance between fractures is much smaller than the wavelengths of the travelling fast compressional and shear waves, the medium behaves as an effective viscoelastic an...
Numerical relativity; La relatividad numerica
Energy Technology Data Exchange (ETDEWEB)
Alcubierre, M.
2015-07-01
Today the numerical relativity has developed numerical techniques and an understanding of the structure of the field equations and terms of coordinates, as well as an explosion in speed and memory capacity of supercomputers, make it possible to simulate the collision of black holes with masses and different spins in gravitational orbits. It has also allowed to study in detail the collapse and collision of stars neutrons.la numerical relativity has allowed other both numerical and theoretical studies. (Author)
Optical illusions induced by rotating medium
Zang, XiaoFei; Huang, PengCheng; Zhu, YiMing
2018-03-01
Different from the traditional single-function electromagnetic wave rotators (rotate the electromagnetic wavefronts), we propose that rotating medium can be extended to optical illusions such as breaking the diffraction limit and overlapping illusion. Furthermore, the homogeneous but anisotropic rotating medium is simplified by homogeneous and isotropic positive-index materials according to the effective medium theory, which is helpful for future device fabrication. Finite element simulations for the two-dimensional case are performed to demonstrate these properties.
FINDING THE FIRST COSMIC EXPLOSIONS. II. CORE-COLLAPSE SUPERNOVAE
International Nuclear Information System (INIS)
Whalen, Daniel J.; Joggerst, Candace C.; Fryer, Chris L.; Stiavelli, Massimo; Heger, Alexander; Holz, Daniel E.
2013-01-01
Understanding the properties of Population III (Pop III) stars is prerequisite to elucidating the nature of primeval galaxies, the chemical enrichment and reionization of the early intergalactic medium, and the origin of supermassive black holes. While the primordial initial mass function (IMF) remains unknown, recent evidence from numerical simulations and stellar archaeology suggests that some Pop III stars may have had lower masses than previously thought, 15-50 M ☉ in addition to 50-500 M ☉ . The detection of Pop III supernovae (SNe) by JWST, WFIRST, or the TMT could directly probe the primordial IMF for the first time. We present numerical simulations of 15-40 M ☉ Pop III core-collapse SNe performed with the Los Alamos radiation hydrodynamics code RAGE. We find that they will be visible in the earliest galaxies out to z ∼ 10-15, tracing their star formation rates and in some cases revealing their positions on the sky. Since the central engines of Pop III and solar-metallicity core-collapse SNe are quite similar, future detection of any Type II SNe by next-generation NIR instruments will in general be limited to this epoch.
A new numerical approximation of the fractal ordinary differential equation
Atangana, Abdon; Jain, Sonal
2018-02-01
The concept of fractal medium is present in several real-world problems, for instance, in the geological formation that constitutes the well-known subsurface water called aquifers. However, attention has not been quite devoted to modeling for instance, the flow of a fluid within these media. We deem it important to remind the reader that the concept of fractal derivative is not to represent the fractal sharps but to describe the movement of the fluid within these media. Since this class of ordinary differential equations is highly complex to solve analytically, we present a novel numerical scheme that allows to solve fractal ordinary differential equations. Error analysis of the method is also presented. Application of the method and numerical approximation are presented for fractal order differential equation. The stability and the convergence of the numerical schemes are investigated in detail. Also some exact solutions of fractal order differential equations are presented and finally some numerical simulations are presented.
Chemically defined medium and Caenorhabditis elegans
Szewczyk, Nathaniel J.; Kozak, Elena; Conley, Catharine A.
2003-01-01
BACKGROUND: C. elegans has been established as a powerful genetic system. Use of a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of use in large-scale growth and screening of animals. RESULTS: We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats to using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change the composition of the defined medium. CONCLUSIONS: As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.
Models and numerical methods for time- and energy-dependent particle transport
Energy Technology Data Exchange (ETDEWEB)
Olbrant, Edgar
2012-04-13
Particles passing through a medium can be described by the Boltzmann transport equation. Therein, all physical interactions of particles with matter are given by cross sections. We compare different analytical models of cross sections for photons, electrons and protons to state-of-the-art databases. The large dimensionality of the transport equation and its integro-differential form make it analytically difficult and computationally costly to solve. In this work, we focus on the following approximative models to the linear Boltzmann equation: (i) the time-dependent simplified P{sub N} (SP{sub N}) equations, (ii) the M{sub 1} model derived from entropy-based closures and (iii) a new perturbed M{sub 1} model derived from a perturbative entropy closure. In particular, an asymptotic analysis for SP{sub N} equations is presented and confirmed by numerical computations in 2D. Moreover, we design an explicit Runge-Kutta discontinuous Galerkin (RKDG) method to the M{sub 1} model of radiative transfer in slab geometry and construct a scheme ensuring the realizability of the moment variables. Among other things, M{sub 1} numerical results are compared with an analytical solution in a Riemann problem and the Marshak wave problem is considered. Additionally, we rigorously derive a new hierarchy of kinetic moment models in the context of grey photon transport in one spatial dimension. For the perturbed M{sub 1} model, we present numerical results known as the two beam instability or the analytical benchmark due to Su and Olson and compare them to the standard M{sub 1} as well as transport solutions.
Numerical methods for stochastic partial differential equations with white noise
Zhang, Zhongqiang
2017-01-01
This book covers numerical methods for stochastic partial differential equations with white noise using the framework of Wong-Zakai approximation. The book begins with some motivational and background material in the introductory chapters and is divided into three parts. Part I covers numerical stochastic ordinary differential equations. Here the authors start with numerical methods for SDEs with delay using the Wong-Zakai approximation and finite difference in time. Part II covers temporal white noise. Here the authors consider SPDEs as PDEs driven by white noise, where discretization of white noise (Brownian motion) leads to PDEs with smooth noise, which can then be treated by numerical methods for PDEs. In this part, recursive algorithms based on Wiener chaos expansion and stochastic collocation methods are presented for linear stochastic advection-diffusion-reaction equations. In addition, stochastic Euler equations are exploited as an application of stochastic collocation methods, where a numerical compa...
Kavka, P.; Jeřábek, J.; Strouhal, L.
2016-12-01
The contribution presents a numerical model SMODERP that is used for calculation and prediction of surface runoff and soil erosion from agricultural land. The physically based model includes the processes of infiltration (Phillips equation), surface runoff routing (kinematic wave based equation), surface retention, surface roughness and vegetation impact on runoff. The model is being developed at the Department of Irrigation, Drainage and Landscape Engineering, Civil Engineering Faculty, CTU in Prague. 2D version of the model was introduced in last years. The script uses ArcGIS system tools for data preparation. The physical relations are implemented through Python scripts. The main computing part is stand alone in numpy arrays. Flow direction is calculated by Steepest Descent algorithm and in multiple flow algorithm. Sheet flow is described by modified kinematic wave equation. Parameters for five different soil textures were calibrated on the set of hundred measurements performed on the laboratory and filed rainfall simulators. Spatially distributed models enable to estimate not only surface runoff but also flow in the rills. Development of the rills is based on critical shear stress and critical velocity. For modelling of the rills a specific sub model was created. This sub model uses Manning formula for flow estimation. Flow in the ditches and streams are also computed. Numerical stability of the model is controled by Courant criterion. Spatial scale is fixed. Time step is dynamic and depends on the actual discharge. The model is used in the framework of the project "Variability of Short-term Precipitation and Runoff in Small Czech Drainage Basins and its Influence on Water Resources Management". Main goal of the project is to elaborate a methodology and online utility for deriving short-term design precipitation series, which could be utilized by a broad community of scientists, state administration as well as design planners. The methodology will account for
Sager-Klauß, C.V.
2016-01-01
Small- and medium-sized communities might prove to be game-changers in the overall energy transition because many problems have to be solved within their ambit. Urban planning is dealing with the numerous processes of urban change. Energy is a fairly new task to be addressed and many stakeholders
Impact of electric and magnetic fields in a resistant medium on the ...
African Journals Online (AJOL)
In this paper, we compare the impact of electric and magnetic fields in a resistant medium on the velocity of a particle subject to varying path angles by using numerical integration of finite difference method. The results show that the magnetic field has much impact on the velocity than the electric field. Journal of the Nigerian ...
African Journals Online (AJOL)
CLEMENT O BEWAJI
Bhardwaj C. N., and Singh V. R., (1994), Synthesis and characterization of thallium (I) complexes of biologically active benzothiazolines, Indian Journal Chemistry 33(3): 423 - 425. Chakraborty H., Paul N., and Rahman M. L., (1994), Catalytic activities of Schiff bases aquo complexes of Cu (II) in the hydrolysis of amino acid ...
MFIX documentation numerical technique
Energy Technology Data Exchange (ETDEWEB)
Syamlal, M.
1998-01-01
MFIX (Multiphase Flow with Interphase eXchanges) is a general-purpose hydrodynamic model for describing chemical reactions and heat transfer in dense or dilute fluid-solids flows, which typically occur in energy conversion and chemical processing reactors. The calculations give time-dependent information on pressure, temperature, composition, and velocity distributions in the reactors. The theoretical basis of the calculations is described in the MFIX Theory Guide. Installation of the code, setting up of a run, and post-processing of results are described in MFIX User`s manual. Work was started in April 1996 to increase the execution speed and accuracy of the code, which has resulted in MFIX 2.0. To improve the speed of the code the old algorithm was replaced by a more implicit algorithm. In different test cases conducted the new version runs 3 to 30 times faster than the old version. To increase the accuracy of the computations, second order accurate discretization schemes were included in MFIX 2.0. Bubbling fluidized bed simulations conducted with a second order scheme show that the predicted bubble shape is rounded, unlike the (unphysical) pointed shape predicted by the first order upwind scheme. This report describes the numerical technique used in MFIX 2.0.
Personalized numerical observer
Brankov, Jovan G.; Pretorius, P. Hendrik
2010-02-01
It is widely accepted that medical image quality should be assessed using task-based criteria, such as humanobserver (HO) performance in a lesion-detection (scoring) task. HO studies are time consuming and cost prohibitive to be used for image quality assessment during development of either reconstruction methods or imaging systems. Therefore, a numerical observer (NO), a HO surrogate, is highly desirable. In the past, we have proposed and successfully tested a NO based on a supervised-learning approach (namely a support vector machine) for cardiac gated SPECT image quality assessment. In the supervised-learning approach, the goal is to identify the relationship between measured image features and HO myocardium defect likelihood scores. Thus far we have treated multiple HO readers by simply averaging or pooling their respective scores. Due to observer variability, this may be suboptimal and less accurate. Therefore, in this work, we are setting our goal to predict individual observer scores independently in the hope to better capture some relevant lesion-detection mechanism of the human observers. This is even more important as there are many ways to get equivalent observer performance (measured by area under receiver operating curve), and simply predicting some joint (average or pooled) score alone is not likely to succeed.
Numerical simulation methods to richtmyer-meshkov instabilities
International Nuclear Information System (INIS)
Zhou Ning; Yu Yan; Tang Weijun
2003-01-01
Front tracking algorithms have generally assumed that the computational medium is divided into piece-wise smooth subdomains bounded by interfaces and that strong wave interactions are solved via Riemann solutions. However, in multi-dimensional cases, the Riemann solution of multiple shock wave interactions are far more complicated and still subject to analytical study. For this reason, it is very desirable to be able to track contact discontinuities only. A new numerical algorithm to couple a tracked contact surface and an untracked strong shock wave are described. The new tracking algorithm reduces the complication of computation, and maintains the sharp resolution of the contact surface. The numerical results are good. (authors)
Design of a broadband ultra-large area acoustic cloak based on a fluid medium
Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping
2014-10-01
A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.
El-Amin, Mohamed
2011-01-01
The interaction of mixed convection with thermal radiation of an optical dense viscous fluid adjacent to an isothermal cone imbedded in a porous medium with Rosseland diffusion approximation incorporating the variation of permeability and thermal conductivity is numerically investigated. The transformed conservation laws are solved numerically for the case of variable surface temperature conditions. Numerical results are given for the dimensionless temperature profiles and the local Nusselt number for various values of the mixed convection parameter , the cone angle parameter ?, the radiation-conduction parameter R d, and the surface temperature parameter H. Copyright 2011 M. F. El-Amin et al.
Energy Technology Data Exchange (ETDEWEB)
Li, X.Y. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)], E-mail: xyli@siom.ac.cn; Wu, Y.Q. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Key Lab of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of Education, Haerbin 150080 (China)], E-mail: yqwu@siom.ac.cn; Gu, D.D.; Gan, F.X. [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)
2009-02-25
Smooth thin films of nickel(II), cobalt(II) and zinc(II) complexes with azo barbituric acid were prepared by the spin-coating method. Absorption spectra of the thin films on K9 glass substrates in 300-700 nm wavelength region were measured. Optical constants (complex refractive index N = n + ik) of the thin films prepared on single-crystal silicon substrates in 275-695 nm wavelength region were investigated on rotating analyzer-polarizer type of scanning ellipsometer, and dielectric constant {epsilon} ({epsilon} = {epsilon}{sub 1} + i{epsilon}{sub 2}) as well as absorption coefficient {alpha} of thin films were calculated at 405 nm. In addition, static optical recording properties of the cobalt(II) complex thin film with an Ag reflective layer was carried out using a 406.7 nm blue-violet laser and a high numerical aperture (NA) of 0.90. Clear recording marks with high reflectivity contrast (>60%) at proper laser power and pulse width were obtained, and the size of recording mark was as small as 250 nm. The results indicate that these metal(II) complexes are promising organic recording medium for the blu-ray optical storage system.
49 CFR 236.811 - Speed, medium.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Speed, medium. 236.811 Section 236.811 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Speed, medium. A speed not exceeding 40 miles per hour. ...
English Medium of Instruction: A Situation Analysis
Uys, Mandie; van der Walt, Johann; van den Berg, Ria; Botha, Sue
2007-01-01
The majority of learners in southern Africa receive their education through the medium of a second language, English. Although teachers of English play a crucial role in helping learners to acquire language skills in the medium of instruction, we argue that subject content teachers' lack of attention to the teaching of the four language skills may…
Electromagnetic Sources in a Moving Conducting Medium
DEFF Research Database (Denmark)
Johannsen, Günther
1971-01-01
The problem of an arbitrary source distribution in a uniformly moving, homogeneous, isotropic, nondispersive, conducting medium is solved. The technique used is to solve the problem in the rest system of the medium and then write the result in an appropriate four-dimensional, covariant form which...
Effective medium theory for anisotropic metamaterials
Zhang, Xiujuan
2015-01-20
Materials with anisotropic material parameters can be utilized to fabricate many fascinating devices, such as hyperlenses, metasolids, and one-way waveguides. In this study, we analyze the effects of geometric anisotropy on a two-dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided the aspect ratio of the lattice and the eccentricity of the elliptic cylinder satisfy certain conditions. The derived effective medium theory not only recovers the well-known Maxwell-Garnett results in the quasi-static regime, but is also valid beyond the long-wavelength limit, where the wavelength in the host medium is comparable to the size of the lattice so that previous anisotropic effective medium theories fail. Such an advance greatly broadens the applicable realm of the effective medium theory and introduces many possibilities in the design of structures with desired anisotropic material characteristics. A real sample of a recently theoretically proposed anisotropic medium, with a near-zero index to control the flux, is achieved using the derived effective medium theory, and control of the electromagnetic waves in the sample is clearly demonstrated.
Optimization of medium composition for thermostable protease ...
African Journals Online (AJOL)
SERVER
2008-04-17
Apr 17, 2008 ... Optimization of the fermentation medium for maximization of thermostable neutral protease production by Bacillus sp. ... at 3.6 g/l and yeast extract at 3.9 g/l gived maximum protease activity of 6804 U/ml. Key words: Medium ... face method, which is used to study the effects of several factors influencing the ...
Numerical studies in geophysics
Hier Majumder, Catherine Anne
2003-10-01
This thesis focuses on the use of modern numerical techniques in the geo- and environmental sciences. Four topics are discussed in this thesis: finite Prandtl number convection, wavelet analysis, inverse methods and data assimilation, and nuclear waste tank mixing. The finite Prandtl number convection studies examine how convection behavior changes as Prandtl numbers are increased to as high as 2 x 104, on the order of Prandtl numbers expected in very hot magmas or mushy ice diapirs. I found that there are significant differences in the convection style between finite Prandtl number convection and the infinite Prandtl number approximation even for Prandtl numbers on the order of 104. This indicates that the infinite Prandtl convection approximation might not accurately model behavior in fluids with large, but finite Prandtl numbers. The section on inverse methods and data assimilation used the technique of four dimensional variational data assimilation (4D-VAR) developed by meteorologists to integrate observations into forecasts. It was useful in studying the predictability and dependence on initial conditions of finite Prandtl simulations. This technique promises to be useful in a wide range of geological and geophysical fields, including mantle convection, hydrogeology, and sedimentology. Wavelet analysis was used to help image and scrutinize at small-scales both temperature and vorticity fields from convection simulations and the geoid. It was found to be extremely helpful in both cases. It allowed us to separate the information in the data into various spatial scales without losing the locations of the signals in space. This proved to be essential in understanding the processes producing the total signal in the datasets. The nuclear waste study showed that techniques developed in geology and geophysics can be used to solve scientific problems in other fields. I applied state-of-the-art techniques currently employed in geochemistry, sedimentology, and mantle
Yamaya, Chiaki; Inoue, Hiroshi
2008-05-01
The analysis of temperature rise due to the absorption of ultrasound is important for the clarification of the effect of ultrasound waves and the estimation of medium constants. The thermal behavior of ultrasound is used not only for thermotherapy but also in measurement techniques. The estimation of a medium constant becomes possible by analyzing the temperature rise because the temperature change of the medium is particular to each medium. The purpose of this research is to establish a method of estimating medium constants and to develop a numerical simulation method that can be applied to the estimation of medium constants. We elucidated the requirements under which the simulation result corresponds to the experimental result. Good agreement between the experimental and simulation results is shown in this paper, and the validity of this method is described.
Optimization of medium for antimycotic production by Streptomyces spp.
Directory of Open Access Journals (Sweden)
Bajić Bojana Ž.
2013-01-01
Full Text Available Numerous species of the genus Streptomyces, on the appropriate cultivation medium in the process of submerged biosynthesis, as a product of the secondary metabolism, and under aerobic conditions synthesize pharmacologically active compounds. The aim of presented study was optimization of different nitrogen sources in the cultivation medium for the production of antimycotics using a strain of Streptomyces spp. isolated from the environment. Experiments were carried out in accordance with Box-Behnken design with three factors at three levels (peptone: 3.0 g/l, 7.0 g/l and 11.0 g/l; yeast extract: 1.0 g/l, 3.0 g/l and 5.0 g/l; soybean meal: 5.0 g/l, 15.0 g/l and 25.0 g/l and three repetitions in the central point. Cultivation mediums were analyzed for determination of residual sugar, residual nitrogen, pellet diameter and RNA. Also, antimycotic activity of the obtained cultivation mediums was determined using diffusion disc method on the Aspergillus spp. as the test microorganism. For the optimization of selected parameters, a Response Surface Methodology was used and the obtained data were analyzed using the software package DESIGN EXPERT 8.1. Achieved model with a coefficient of determination (R of 0.952 predicted that the maximum inhibition zone diameter (24.0 mm against microorganism Aspergillus spp. and the minimum amount of residual sugar (0.551528 g/l under applied experimental conditions was produced when the contents of varied nitrogen sources were: peptone 11.0 g/l, yeast extract 4.32 g/l and soybean meal 25.00 g/l.
African Journals Online (AJOL)
stereochemistry has been suggested to Zn(II), Cd(II) and Hg(II) complexes. The thermal analysis data provided the kinetic parameters as order of decomposition reaction, activation energy and frequency factor. All theoretical calculations of the ligand and the Cu(II) and Zn(II) complexes were made using Gaussian 03 rev.
Numerical Homogenization of Jointed Rock Masses Using Wave Propagation Simulation
Gasmi, Hatem; Hamdi, Essaïeb; Bouden Romdhane, Nejla
2014-07-01
Homogenization in fractured rock analyses is essentially based on the calculation of equivalent elastic parameters. In this paper, a new numerical homogenization method that was programmed by means of a MATLAB code, called HLA-Dissim, is presented. The developed approach simulates a discontinuity network of real rock masses based on the International Society of Rock Mechanics (ISRM) scanline field mapping methodology. Then, it evaluates a series of classic joint parameters to characterize density (RQD, specific length of discontinuities). A pulse wave, characterized by its amplitude, central frequency, and duration, is propagated from a source point to a receiver point of the simulated jointed rock mass using a complex recursive method for evaluating the transmission and reflection coefficient for each simulated discontinuity. The seismic parameters, such as delay, velocity, and attenuation, are then calculated. Finally, the equivalent medium model parameters of the rock mass are computed numerically while taking into account the natural discontinuity distribution. This methodology was applied to 17 bench fronts from six aggregate quarries located in Tunisia, Spain, Austria, and Sweden. It allowed characterizing the rock mass discontinuity network, the resulting seismic performance, and the equivalent medium stiffness. The relationship between the equivalent Young's modulus and rock discontinuity parameters was also analyzed. For these different bench fronts, the proposed numerical approach was also compared to several empirical formulas, based on RQD and fracture density values, published in previous research studies, showing its usefulness and efficiency in estimating rapidly the Young's modulus of equivalent medium for wave propagation analysis.
Micropropagation of Alstroemeria in liquid medium using slow release of medium components
Klerk, de G.J.M.; Brugge, ter J.
2010-01-01
Alstroemeria rhizomes were micropropagated on semi-solid medium (AM) and in liquid medium (LM). In LM, growth was much enhanced (ca. 70%). Adequate gas exchange was crucial. This was obtained by agitation and in static medium by a sufficient large contact area of the explant and the gaseous
Preliminary 2D numerical modeling of common granular problems
Wyser, Emmanuel; Jaboyedoff, Michel
2017-04-01
Granular studies received an increasing interest during the last decade. Many scientific investigations were successfully addressed to acknowledge the ubiquitous behavior of granular matter. We investigate liquid impacts onto granular beds, i.e. the influence of the packing and compaction-dilation transition. However, a physically-based model is still lacking to address complex microscopic features of granular bed response during liquid impacts such as compaction-dilation transition or granular bed uplifts (Wyser et al. in review). We present our preliminary 2D numerical modeling based on the Discrete Element Method (DEM) using nonlinear contact force law (the Hertz-Mindlin model) for disk shape particles. The algorithm is written in C programming language. Our 2D model provides an analytical tool to address granular problems such as i) granular collapses and ii) static granular assembliy problems. This provides a validation framework of our numerical approach by comparing our numerical results with previous laboratory experiments or numerical works. Inspired by the work of Warnett et al. (2014) and Staron & Hinch (2005), we studied i) the axisymetric collapse of granular columns. We addressed the scaling between the initial aspect ratio and the final runout distance. Our numerical results are in good aggreement with the previous studies of Warnett et al. (2014) and Staron & Hinch (2005). ii) Reproducing static problems for regular and randomly stacked particles provides a valid comparison to results of Egholm (2007). Vertical and horizontal stresses within the assembly are quite identical to stresses obtained by Egholm (2007), thus demonstating the consistency of our 2D numerical model. Our 2D numerical model is able to reproduce common granular case studies such as granular collapses or static problems. However, a sufficient small timestep should be used to ensure a good numerical consistency, resulting in higher computational time. The latter becomes critical
How to Circumvent Church Numerals
DEFF Research Database (Denmark)
Goldberg, Mayer; Torgersen, Mads
2002-01-01
In this work we consider a standard numeral system in the lambda-calculus, and the elementary arithmetic and Boolean functions and predicates defined on this numeral system, and show how to construct terms that "circumvent" or "defeat" these functions: The equality predicate is satisfied when...... comparing these special terms to any numeral, the zero predicate is satisfied for these terms, etc. We believe this exercise offers an instructive look at what definability means in the untyped lambda-calculus....
Collaborative Manufacturing for Small-Medium Enterprises
Irianto, D.
2016-02-01
Manufacturing systems involve decisions concerning production processes, capacity, planning, and control. In a MTO manufacturing systems, strategic decisions concerning fulfilment of customer requirement, manufacturing cost, and due date of delivery are the most important. In order to accelerate the decision making process, research on decision making structure when receiving order and sequencing activities under limited capacity is required. An effective decision making process is typically required by small-medium components and tools maker as supporting industries to large industries. On one side, metal small-medium enterprises are expected to produce parts, components or tools (i.e. jigs, fixture, mold, and dies) with high precision, low cost, and exact delivery time. On the other side, a metal small- medium enterprise may have weak bargaining position due to aspects such as low production capacity, limited budget for material procurement, and limited high precision machine and equipment. Instead of receiving order exclusively, a small-medium enterprise can collaborate with other small-medium enterprise in order to fulfill requirements high quality, low manufacturing cost, and just in time delivery. Small-medium enterprises can share their best capabilities to form effective supporting industries. Independent body such as community service at university can take a role as a collaboration manager. The Laboratory of Production Systems at Bandung Institute of Technology has implemented shared manufacturing systems for small-medium enterprise collaboration.
Direct Numerical Simulations of Transient Dispersion
Porter, M.; Valdes-Parada, F.; Wood, B.
2008-12-01
Transient dispersion is important in many engineering applications, including transport in porous media. A common theoretical approach involves upscaling the micro-scale mass balance equations for convection- diffusion to macro-scale equations that contain effective medium quantities. However, there are a number of assumptions implicit in the various upscaling methods. For example, results obtained from volume averaging are often dependent on a given set of length and time scale constraints. Additionally, a number of the classical models for dispersion do not fully capture the early-time dispersive behavior of the solute for a general set of initial conditions. In this work, we present direct numerical simulations of micro-scale transient mass balance equations for convection-diffusion in both capillary tubes and porous media. Special attention is paid to analysis of the influence of a new time- decaying coefficient that filters the effects of the initial conditions. The direct numerical simulations were compared to results obtained from solving the closure problem associated with volume averaging. These comparisons provide a quantitative measure of the significance of (1) the assumptions implicit in the volume averaging method and (2) the importance of the early-time dispersive behavior of the solute due to various initial conditions.
Representation of Numerical and Non-Numerical Order in Children
Berteletti, Ilaria; Lucangeli, Daniela; Zorzi, Marco
2012-01-01
The representation of numerical and non-numerical ordered sequences was investigated in children from preschool to grade 3. The child's conception of how sequence items map onto a spatial scale was tested using the Number-to-Position task (Siegler & Opfer, 2003) and new variants of the task designed to probe the representation of the alphabet…
Directory of Open Access Journals (Sweden)
Farhad Ali
2013-01-01
Full Text Available The focus of this paper is to analyze the influence of thermal radiation on some unsteady magnetohydrodynamic (MHD free convection flows of an incompressible Brinkman type fluid past a vertical flat plate embedded in a porous medium with the Newtonian heating boundary condition. The fluid is considered as a gray absorbing-emitting but nonscattering medium and the Rosseland approximation in the energy equations is used to describe the radiative heat flux for optically thick fluid. For a detailed analysis of the problem, four important situations of flow due to (i impulsive motion of the plate (ii uniform acceleration of the plate (iii nonuniform acceleration of the plate, and (iv highly nonuniform acceleration of the plate are considered. The governing equations are first transformed into a system of dimensionless equations and then solved analytically using the Laplace transform technique. Numerical results for temperature and velocity are shown graphically, while skin friction and Nusselt number are computed in tables. The results show that temperature and velocity increase on increasing radiation and Newtonian heating parameters. However, the results of magnetic and porosity parameters on velocity are found quite opposite.
Indian Academy of Sciences (India)
Unknown
161. Synthesis, characterisation and electrochemical behaviour of. Cu(II), Co(II), Ni(II) and Zn(II) complexes derived from acetylacetone and p-anisidine and their antimicrobial activity. N RAMAN*, V MUTHURAJ, S RAVICHANDRAN and. A KULANDAISAMY. Department of Chemistry, VHNSN College, Virudhunagar 626 001 ...
Directory of Open Access Journals (Sweden)
UMADEVI K. S.
2017-07-01
Full Text Available WiMedia Medium Access Control (MAC provides high rate data transfer for wireless networking thereby enables construction of high speed home networks. It facilitates data communication between the nodes through two modes namely: i Distributed Reservation Protocol (DRP for isochronous traffic and ii Prioritized Contention Access (PCA for asynchronous traffic. PCA mode enables medium access using CSMA/CA similar to IEEE 802.11e. In the presence of DRP, the throughput of PCA saturates when there is an increase in the number of devices accessing PCA channel. Researchers suggest that the better utilization of medium resolves many issues in an effective way. To demonstrate the effective utilization of the medium, Contention Based Distributed Reservation Protocol Allocation Algorithm for WiMedia Medium Access Control is proposed for reserving Medium Access Slots under DRP in the presence of PCA. The proposed algorithm provides a better medium access, reduces energy consumption and enhances the throughput when compared to the existing methodologies.
Physical processes in the interstellar medium
Spitzer, Lyman
2008-01-01
Physical Processes in the Interstellar Medium discusses the nature of interstellar matter, with a strong emphasis on basic physical principles, and summarizes the present state of knowledge about the interstellar medium by providing the latest observational data. Physics and chemistry of the interstellar medium are treated, with frequent references to observational results. The overall equilibrium and dynamical state of the interstellar gas are described, with discussions of explosions produced by star birth and star death and the initial phases of cloud collapse leading to star formation.
DECOVALEX II PROJECT Executive Summary
International Nuclear Information System (INIS)
Jing, L.; Stephansson, O.; Kautsky, F.
1999-11-01
DECOVALEX II project started in November 1995 as a continuation of the DECOVALEX I project, which was completed at the end of 1994. The project was initiated by recognising the fact that a proper evaluation of the current capacities of numerical modelling of the coupled T-H-M processes in fractured media is needed not only for small scale, well controlled laboratory test cases such as those studied in DECOVALEX I, but also for less characterised, more complex and realistic in-situ experiments. This executive summary presents the motivation, structure, objectives, approaches, and highlights of the main tasks and main achievements of the DECOVALEX II project from 1995-1999. The main source of the materials came from four technical reports the project prepared by the project Secretariat, which, in turn, were based on numerous progress reports produced by a large number of international research teams over the three and half year period. The editors of this summary, together with the Steering Committee of the DECOVALEX II project, feel very encouraged by the progresses which have been made during the project time and very positive about the usefulness of the achievements reached by the project to the larger international community of scientific research and management of radioactive wastes in different countries. We sincerely hope that continued efforts be made to forward the research carried out in both DECOVALEX I and DECOVALEX II projects so that the disposal of radioactive waste could be managed on a more reliable scientific basis
DECOVALEX II PROJECT Executive Summary
Energy Technology Data Exchange (ETDEWEB)
Jing, L.; Stephansson, O. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Civil and Environmental Engineering; Tsang, C.F. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States). Earth Science Div.; Knight, L.J. [United Kingdom Nirex Ltd., Harwell (United Kingdom); Kautsky, F. [Swedish Nuclear Power Inspectorate (SKI), Stockholm (Sweden)
1999-11-01
DECOVALEX II project started in November 1995 as a continuation of the DECOVALEX I project, which was completed at the end of 1994. The project was initiated by recognising the fact that a proper evaluation of the current capacities of numerical modelling of the coupled T-H-M processes in fractured media is needed not only for small scale, well controlled laboratory test cases such as those studied in DECOVALEX I, but also for less characterised, more complex and realistic in-situ experiments. This executive summary presents the motivation, structure, objectives, approaches, and highlights of the main tasks and main achievements of the DECOVALEX II project from 1995-1999. The main source of the materials came from four technical reports the project prepared by the project Secretariat, which, in turn, were based on numerous progress reports produced by a large number of international research teams over the three and half year period. The editors of this summary, together with the Steering Committee of the DECOVALEX II project, feel very encouraged by the progresses which have been made during the project time and very positive about the usefulness of the achievements reached by the project to the larger international community of scientific research and management of radioactive wastes in different countries. We sincerely hope that continued efforts be made to forward the research carried out in both DECOVALEX I and DECOVALEX II projects so that the disposal of radioactive waste could be managed on a more reliable scientific basis.
Numerical Approaches to Spacetime Singularities
Directory of Open Access Journals (Sweden)
Beverly K. Berger
1998-05-01
Full Text Available This review updates a previous review article. Numerical explorationof the properties of singularities could, in principle, yield detailed understanding of their nature in physically realistic cases. Examples of numerical investigations into the formation of naked singularities, critical behavior in collapse, passage through the Cauchy horizon, chaos of the Mixmaster singularity, and singularities in spatially inhomogeneous cosmologies are discussed.
How to Circumvent Church Numerals
DEFF Research Database (Denmark)
Goldberg, Mayer; Torgersen, Mads
2002-01-01
In this work we consider a standard numeral system in the lambda-calculus, and the elementary arithmetic and Boolean functions and predicates defined on this numeral system, and show how to construct terms that "circumvent" or "defeat" these functions: The equality predicate is satisfied when com...
Nucleon form factors in the nuclear medium
Park, Chanyong; Lee, Jung Hun
2018-01-01
By using the AdS/CFT correspondence, we investigate various form factors between nucleons and mesons in a nuclear medium. In order to describe a nuclear medium holographically, we take into account the thermal charged AdS geometry with an appropriate IR cutoff. After introducing an anomalous dimension as a free parameter, we investigate how the nucleon’s mass is affected by the change of the anomalous dimension. Moreover, we study how the form factors of nucleons rely on the properties of the nuclear medium. We show that in a nuclear medium with different numbers of proton and neutron, the degenerated nucleon form factor in the vacuum is split into four different values depending on the isospin charges of nucleon and meson.
Study of niobium corrosion in alkaline medium
International Nuclear Information System (INIS)
Almeida, S.H. de.
1987-01-01
A comparative study of niobium electrochemical behaviour in NaOH and KOH solution, with concentrations between 0,5 and 6,1M is presented. The studies were done through electrochemicals assays, consisting in the corrosion potential and anodic and cathodic polarization curves, complemented by loss of mass experiments. The niobium anodic behaviour in alkaline medium is characterized by passivation occurrence, with a stable film formation. The Na oH solution in alkaline medium are more corrosible to niobium than the KOH solution. The loss of mass assays showed that the corrosion velocit is more dependente of hydroxide concentration in KOH medium than the NaOH medium. (C.G.C.) [pt
Fractional diffusion equation for heterogeneous medium
Energy Technology Data Exchange (ETDEWEB)
Polo L, M. A.; Espinosa M, E. G.; Espinosa P, G. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Av, San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Del Valle G, E., E-mail: plabarrios@hotmail.com [Instituto Politecnico Nacional, Escuela Superior de Fisica y Matematicas, Av. IPN s/n, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico)
2011-11-15
The asymptotic diffusion approximation for the Boltzmann (transport) equation was developed in 1950 decade in order to describe the diffusion of a particle in an isotropic medium, considers that the particles have a diffusion infinite velocity. In this work is developed a new approximation where is considered that the particles have a finite velocity, with this model is possible to describe the behavior in an anomalous medium. According with these ideas the model was obtained from the Fick law, where is considered that the temporal term of the current vector is not negligible. As a result the diffusion equation of fractional order which describes the dispersion of particles in a highly heterogeneous or disturbed medium is obtained, i.e., in a general medium. (Author)
(New molecular ions in the interstellar medium
Directory of Open Access Journals (Sweden)
Roueff Evelyne
2015-01-01
Full Text Available We summarize the present knowledge on the molecular ionic content in the interstellar medium and in circumstellar envelopes. Emphasis is given on the most recent detections and the related chemical issues.
Small and medium power reactors 1987
International Nuclear Information System (INIS)
1987-12-01
This TECDOC follows the publication of TECDOC-347 Small and Medium Power Reactors Project Initiation Study - Phase I published in 1985 and TECDOC-376 Small and Medium Power Reactors 1985 published in 1986. It is mainly intended for decision makers in Developing Member States interested in embarking on a nuclear power programme. It consists of two parts: 1) Guidelines for the Introduction of Small and Medium Power Reactors in Developing Countries. These Guidelines were established during the Advisory Group Meeting held in Vienna from 11 to 15 May 1987. Their purpose is to review key aspects relating to the introduction of Small and Medium Power Reactors in developing countries; 2) Up-dated Information on SMPR Concepts Contributed by Supplier Industries. According to the recommendations of the Second Technical Committee Meeting on SMPRs held in Vienna in March 1985, this part contains the up-dated information formerly published in Annex I of the above mentioned TECDOC-347. Figs
Sharing perspectives on English-medium instruction
Ackerley, Katherine; Helm, Francesca
2017-01-01
This volume gives voice to the views and experiences of researchers, lecturers, administrative staff, teacher trainers and students with regard to the implementation of English-medium instruction in a public university based in the north-east of Italy.
Effective medium theory principles and applications
Choy, Tuck C
2015-01-01
Effective medium theory dates back to the early days of the theory of electricity. Faraday in 1837 proposed one of the earliest models for a composite metal-insulator dielectric and around 1870 Maxwell and later Garnett (1904) developed models to describe a composite or mixed material medium. The subject has been developed considerably since and while the results are useful for predicting materials performance, the theory can also be used in a wide range of problems in physics and materials engineering. This book develops the topic of effective medium theory by bringing together the essentials of both the static and the dynamical theory. Electromagnetic systems are thoroughly dealt with, as well as related areas such as the CPA theory of alloys, liquids, the density functional theory etc., with applications to ultrasonics, hydrodynamics, superconductors, porous media and others, where the unifying aspects of the effective medium concept are emphasized. In this new second edition two further chapters have been...
Medium Effects in Reactions with Rare Isotopes
International Nuclear Information System (INIS)
Bertulani, C A; Karakoç, M
2012-01-01
We discuss medium effects in knockout reactions with rare isotopes of weakly-bound nuclei at intermediate energies. We show that the poorly known corrections may lead to sizable modifications of knockout cross sections and momentum dsitributions.
Switching power converters medium and high power
Neacsu, Dorin O
2013-01-01
An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as
Generation of medium frequency electrotherapeutic signals
Płaza, Mirosław; Szcześniak, Zbigniew; Dudek, Jolanta
2017-08-01
In this paper, generation methods of sinusoidal medium frequency electrotherapeutic signals have been studied. Signals of this type are increasingly used in electrotherapy owing to the development of both physical medicine and engineering sciences. The article presents analysis and comparison of analogue and digital methods of generation therapeutic signals. Analysis presented in the paper attempts to answer the question which technique of medium frequency signal generation can be most broadly applied in electrotherapy methods.
DYNAMIC DEFORMATION THE VISCOELASTIC TWOCOMPONENT MEDIUM
Directory of Open Access Journals (Sweden)
V. S. Polenov
2015-01-01
Full Text Available Summary. In the article are scope harmonious warping of the two-component medium, one component which are represent viscoelastic medium, hereditary properties which are described by the kernel aftereffect Abel integral-differential ratio BoltzmannVolterr, while second – compressible liquid. Do a study one-dimensional case. Use motion equation of two-component medium at movement. Look determination system these equalization in the form of damped wave. Introduce dimensionless coefficient. Combined equations happen to homogeneous system with complex factor relatively waves amplitude in viscoelastic component and in fluid. As a result opening system determinant receive biquadratic equation. Elastic operator express through kernel aftereffect Abel for space Fourier. With the help transformation and symbol series biquadratic equation reduce to quadratic equation. Come to the conclusion that in two-component viscoelastic medium exist two mode sonic waves. As a result solution of quadratic equation be found description advance of waves sonic in viscoelastic two-component medium, which physical-mechanical properties represent complex parameter. Velocity determination advance of sonic waves, attenuation coefficient, mechanical loss tangent, depending on characteristic porous medium and circular frequency formulas receive. Graph dependences of description advance of waves sonic from the temperature logarithm and with the fractional parameter γ are constructed.
Selective medium for culture of Mycoplasma hyopneumoniae.
Cook, Beth S; Beddow, Jessica G; Manso-Silván, Lucía; Maglennon, Gareth A; Rycroft, Andrew N
2016-11-15
The fastidious porcine respiratory pathogen Mycoplasma hyopneumoniae has proven difficult to culture since it was first isolated in 1965. A reliable solid medium has been particularly challenging. Moreover, clinical and pathological samples often contain the fast-growing M. hyorhinis which contaminates and overgrows M. hyopneumoniae in primary culture. The aim of this study was to optimise the culture medium for recovery of M. hyopneumoniae and to devise a medium for selection of M. hyopneumoniae from clinical samples also containing M. hyorhinis. The solid medium devised by Niels Friis was improved by use of Purified agar and incorporation of DEAE-dextran. Addition of glucose or neutralization of acidity in liquid medium with NaOH did not improve the final yield of viable organisms or alter the timing of peak viability. Analysis of the relative susceptibility of M. hyopneumoniae and M. hyorhinis strains to four antimicrobials showed that M. hyopneumoniae is less susceptible than M. hyorhinis to kanamycin. This was consistent in all UK and Danish strains tested. A concentration of 2μg/ml of kanamycin selectively inhibited the growth of all M. hyorhinis tested, while M. hyopneumoniae was able to grow. This forms the basis of an effective selective culture medium for M. hyopneumoniae. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.
Mishchenko, Michael I.; Yang, Ping
2018-01-01
In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenz-Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.
Short- and Medium-Term Induced Ionization in the Earth Atmosphere by Galactic and Solar Cosmic Rays
Directory of Open Access Journals (Sweden)
Alexander Mishev
2013-01-01
Full Text Available The galactic cosmic rays are the main source of ionization in the troposphere of the Earth. Solar energetic particles of MeV energies cause an excess of ionization in the atmosphere, specifically over polar caps. The ionization effect during the major ground level enhancement 69 on January 20, 2005 is studied at various time scales. The estimation of ion rate is based on a recent numerical model for cosmic-ray-induced ionization. The ionization effect in the Earth atmosphere is obtained on the basis of solar proton energy spectra, reconstructed from GOES 11 measurements and subsequent full Monte Carlo simulation of cosmic-ray-induced atmospheric cascade. The evolution of atmospheric cascade is performed with CORSIKA 6.990 code using FLUKA 2011 and QGSJET II hadron interaction models. The atmospheric ion rate is explicitly obtained for various latitudes, namely, 40°N, 60°N and 80°N. The time evolution of obtained ion rates is presented. The short- and medium-term ionization effect is compared with the average effect due to galactic cosmic rays. It is demonstrated that ionization effect is significant only in subpolar and polar atmosphere during the major ground level enhancement of January 20, 2005. It is negative in troposphere at midlatitude, because of the accompanying Forbush effect.
Directory of Open Access Journals (Sweden)
Gabriel Centeno
2017-11-01
Full Text Available Single Point Incremental Forming (SPIF is a flexible and economic manufacturing process with a strong potential for manufacturing small and medium batches of highly customized parts. Formability and failure in SPIF have been intensively discussed in recent years, especially because this process allows stable plastic deformation well above the conventional forming limits, as this enhanced formability is only achievable within a certain range of process parameters depending on the material type. This paper analyzes formability and failure of AISI304-H111 sheets deformed by SPIF compared to conventional testing conditions (including Nakazima and stretch-bending tests. With this purpose, experimental tests in SPIF and stretch-bending were carried out and a numerical model of SPIF is performed. The results allow the authors to establish the following contributions regarding SPIF: (i the setting of the limits of the formability enhancement when small tool diameters are used, (ii the evolution of the crack when failure is attained and (iii the determination of the conditions upon which necking is suppressed, leading directly to ductile fracture in SPIF.
Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part A
Energy Technology Data Exchange (ETDEWEB)
Badruddin, Irfan Anjum [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Quadir, G. A. [School of Mechatronic Engineering, University Malaysia Perlis, Pauh Putra, 02600 Arau, Perlis (Malaysia)
2016-06-08
Heat transfer in a porous medium embedded with vertical flat plate is investigated by using thermal non-equilibrium model. Darcy model is employed to simulate the flow inside porous medium. It is assumed that the heat transfer takes place by natural convection and radiation. The vertical plate is maintained at isothermal temperature. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method. Results are presented in terms of isotherms and streamlines for various parameters such as heat transfer coefficient parameter, thermal conductivity ratio, and radiation parameter.
Effect of rotation on a semiconducting medium with two-temperatures under L-S theory
Directory of Open Access Journals (Sweden)
Othman Mohamed I.A.
2017-06-01
Full Text Available The model of the equations of generalized thermoelasticity in a semi-conducting medium with two-temperature is established. The entire elastic medium is rotated with a uniform angular velocity. The formulation is applied under Lord-Schulman theory with one relaxation time. The normal mode analysis is used to obtain the expressions for the considered variables. Also some particular cases are discussed in the context of the problem. Numerical results for the considered variables are obtained and illustrated graphically. Comparisons are also made with the results predicted in the absence and presence of rotation as well as two-temperature parameter.
Collision density approach of radiation damage in a multispecies medium
International Nuclear Information System (INIS)
Lux, I.; Pazsit, I.
1981-01-01
Space-energy dependent forward type equations for the collision densities of energetic atoms in a multispecies semi-infinite homogeneous medium are formulated. Introduction of the one-dimensional isotropic forward-backward model of Fermi for the scattering and application of the Laplace transform with respect to the lethargy variable will lead to a linear differential equation system with constant coefficients. This equation system is solved for an arbitrary number of species and relations between the collision densities and defect distributions of the different species are given in the Kinchin-Pease model of radiation damage. The case of an alien particle incident on a two-component target is examined in some detail and the sputtering spectra for the three species are given numerically. (author)
Multiple scattering of polarized light in a turbid medium
International Nuclear Information System (INIS)
Gorodnichev, E. E.; Kuzovlev, A. I.; Rogozkin, D. B.
2007-01-01
It is shown that multiple scattering of polarized light in a turbid medium can be represented as independent propagation of three basic modes: intensity and linearly and circularly polarized modes. Weak interaction between the basic modes can be described by perturbation theory and gives rise to 'overtones' (additional polarization modes). Transport equations for the basic and additional modes are derived from a vector radiative transfer equation. Analytical solutions to these equations are found in the practically important cases of diffusive light propagation and small-angle multiple scattering. The results obtained are in good agreement with experimental and numerical results and provide an explanation for the experimentally observed difference in depolarization between linearly and circularly polarized waves
Peristaltic transport of copper-water nanofluid saturating porous medium
Abbasi, F. M.; Hayat, T.; Ahmad, B.
2015-03-01
Prime goal of present study is to model the problem for peristaltic transport of copper-water nanofluid in an asymmetric channel. The fluid fills porous space. Analysis is carried out in the presence of mixed conviction, viscous dissipation and heat generation/absorption. Long wavelength and low Reynolds number approximations are utilized in problem formulation. Numerical computations are presented for the axial velocity, pressure gradient, streamlines, temperature and heat transfer rate at the boundary. Graphical analysis is carried out to examine the effects of sundry parameters on flow quantities of interest. Results revealed that the axial velocity of copper-water nanofluid decreases with an increase in the nanoparticle volume fraction. Copper nanoparticles prove effective coolant since they sufficiently reduce the fluid temperature and show increase in the heat transfer between the fluid and solid boundary. Moreover temperature of the fluid decreases by increasing the permeability of porous medium.
The Origins of [C ii] Emission in Local Star-forming Galaxies
Energy Technology Data Exchange (ETDEWEB)
Croxall, K. V. [Department of Astronomy, The Ohio State University, 4051 McPherson Laboratory, 140 W. 18th Avenue, Columbus, OH, 43210 (United States); Smith, J. D. [Max-Planck-Institut fur Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Pellegrini, E. [Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606 (United States); Groves, B. [Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Bolatto, A.; Wolfire, M. G. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Herrera-Camus, R. [Max-Planck-Institut für extraterrestrische Physik, Giessen-bachstr., D-85748 Garching (Germany); Sandstrom, K. M. [Center for Astrophysics and Space Sciences, Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Draine, B. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Armus, L. [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States); Boquien, M. [Unidad de Astronomía, Fac. Cs. Básicas, Universidad de Antofagasta, Avda. U. de Antofagasta 02800, Antofagasta (Chile); Brandl, B. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Dale, D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Galametz, M. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu—CNRS—Université Paris Diderot, CEA-Saclay, 91191, Gif-sur-Yvette (France); Hunt, L., E-mail: jd.smith@utoledo.edu [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze (Italy); and others
2017-08-20
The [C ii] 158 μ m fine-structure line is the brightest emission line observed in local star-forming galaxies. As a major coolant of the gas-phase interstellar medium, [C ii] balances the heating, including that due to far-ultraviolet photons, which heat the gas via the photoelectric effect. However, the origin of [C ii] emission remains unclear because C{sup +} can be found in multiple phases of the interstellar medium. Here we measure the fractions of [C ii] emission originating in the ionized and neutral gas phases of a sample of nearby galaxies. We use the [N ii] 205 μ m fine-structure line to trace the ionized medium, thereby eliminating the strong density dependence that exists in the ratio of [C ii]/[N ii] 122 μ m. Using the FIR [C ii] and [N ii] emission detected by the KINGFISH (Key Insights on Nearby Galaxies: a Far- Infrared Survey with Herschel ) and Beyond the Peak Herschel programs, we show that 60%–80% of [C ii] emission originates from neutral gas. We find that the fraction of [C ii] originating in the neutral medium has a weak dependence on dust temperature and the surface density of star formation, and has a stronger dependence on the gas-phase metallicity. In metal-rich environments, the relatively cooler ionized gas makes substantially larger contributions to total [C ii] emission than at low abundance, contrary to prior expectations. Approximate calibrations of this metallicity trend are provided.
Numerical Hydrodynamics in General Relativity
Directory of Open Access Journals (Sweden)
Font José A.
2000-05-01
Full Text Available The current status of numerical solutions for the equations of ideal general relativistic hydrodynamics is reviewed. Different formulations of the equations are presented, with special mention of conservative and hyperbolic formulations well-adapted to advanced numerical methods. A representative sample of available numerical schemes is discussed and particular emphasis is paid to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. A comprehensive summary of relevant astrophysical simulations in strong gravitational fields, including gravitational collapse, accretion onto black holes and evolution of neutron stars, is also presented.
Modelling hair follicle growth dynamics as an excitable medium.
Directory of Open Access Journals (Sweden)
Philip J Murray
Full Text Available The hair follicle system represents a tractable model for the study of stem cell behaviour in regenerative adult epithelial tissue. However, although there are numerous spatial scales of observation (molecular, cellular, follicle and multi follicle, it is not yet clear what mechanisms underpin the follicle growth cycle. In this study we seek to address this problem by describing how the growth dynamics of a large population of follicles can be treated as a classical excitable medium. Defining caricature interactions at the molecular scale and treating a single follicle as a functional unit, a minimal model is proposed in which the follicle growth cycle is an emergent phenomenon. Expressions are derived, in terms of parameters representing molecular regulation, for the time spent in the different functional phases of the cycle, a formalism that allows the model to be directly compared with a previous cellular automaton model and experimental measurements made at the single follicle scale. A multi follicle model is constructed and numerical simulations are used to demonstrate excellent qualitative agreement with a range of experimental observations. Notably, the excitable medium equations exhibit a wider family of solutions than the previous work and we demonstrate how parameter changes representing altered molecular regulation can explain perturbed patterns in Wnt over-expression and BMP down-regulation mouse models. Further experimental scenarios that could be used to test the fundamental premise of the model are suggested. The key conclusion from our work is that positive and negative regulatory interactions between activators and inhibitors can give rise to a range of experimentally observed phenomena at the follicle and multi follicle spatial scales and, as such, could represent a core mechanism underlying hair follicle growth.
Modelling hair follicle growth dynamics as an excitable medium.
Murray, Philip J; Maini, Philip K; Plikus, Maksim V; Chuong, Cheng-Ming; Baker, Ruth E
2012-01-01
The hair follicle system represents a tractable model for the study of stem cell behaviour in regenerative adult epithelial tissue. However, although there are numerous spatial scales of observation (molecular, cellular, follicle and multi follicle), it is not yet clear what mechanisms underpin the follicle growth cycle. In this study we seek to address this problem by describing how the growth dynamics of a large population of follicles can be treated as a classical excitable medium. Defining caricature interactions at the molecular scale and treating a single follicle as a functional unit, a minimal model is proposed in which the follicle growth cycle is an emergent phenomenon. Expressions are derived, in terms of parameters representing molecular regulation, for the time spent in the different functional phases of the cycle, a formalism that allows the model to be directly compared with a previous cellular automaton model and experimental measurements made at the single follicle scale. A multi follicle model is constructed and numerical simulations are used to demonstrate excellent qualitative agreement with a range of experimental observations. Notably, the excitable medium equations exhibit a wider family of solutions than the previous work and we demonstrate how parameter changes representing altered molecular regulation can explain perturbed patterns in Wnt over-expression and BMP down-regulation mouse models. Further experimental scenarios that could be used to test the fundamental premise of the model are suggested. The key conclusion from our work is that positive and negative regulatory interactions between activators and inhibitors can give rise to a range of experimentally observed phenomena at the follicle and multi follicle spatial scales and, as such, could represent a core mechanism underlying hair follicle growth.
Yao, Yongchang; Zhai, Zhichen; Wang, Yingjun
2014-01-01
Background. The ATDC5 cell line is regarded as an excellent cell model for chondrogenesis. In most studies with ATDC5 cells, insulin medium (IM) was used to induce chondrogenesis while chondrogenic medium (CM), which was usually applied in chondrogenesis of mesenchymal stem cells (MSCs), was rarely used for ATDC5 cells. This study was mainly designed to investigate the effect of IM, CM, and growth medium (GM) on chondrogenesis of ATDC5 cells. Methods. ATDC5 cells were, respectively, cultured ...
Parton fragmentation in the vacuum and in the medium
Albino, S.; Arleo, F.; Besson, Dave Z.; Brooks, William K.; Buschbeck, B.; Cacciari, M.; Christova, E.; Corcella, G.; D'Enterria, David G.; Dolejsi, Jiri; Domdey, S.; Estienne, M.; Hamacher, Klaus; Heinz, M.; Hicks, K.; Kettler, D.; Kumano, S.; Moch, S.O.; Muccifora, V.; Pacetti, S.; Perez-Ramos, R.; Pirner, H.J.; Pronko, Alexandre Pavlovich; Radici, M.; Rak, J.; Roland, C.; Rudolph, Gerald; Rurikova, Z.; Salgado, C.A.; Sapeta, S.; Saxon, David H.; Seidl, Ralf-Christian; Seuster, R.; Stratmann, M.; Tannenbaum, Michael J.; Tasevsky, M.; Trainor, T.; Traynor, D.; Werlen, M.; Zhou, C.
2008-01-01
We present the mini-proceedings of the workshop on ``Parton fragmentation in the vacuum and in the medium'' held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) in February 2008. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of quark and gluon fragmentation into hadrons at different accelerator facilities (LEP, B-factories, JLab, HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) light-quark and gluon fragmentation in the vacuum including theoretical (global fits analyses and MLLA) and experimental (data from e+e-, p-p, e-p collisions) aspects, (ii) strange and heavy-quark fragmentation, (iii) parton fragmentation in cold QCD matter (nuclear DIS), and (iv) medium-modified fragmentation in hot and dense QCD matter (high-energy nucleus-nucleus collisions). These mini-proceedings consist of an introduction and short summ...
Numerical modeling of oceanic crustal hydrothermal systems
Latychev, Konstantin
The oceanic crust is a complex rock-mineral formation which extends up to several kilometers below the sea floor and covers laterally about two thirds of the planet. Hydrothermal circulation within the crust is driven by magmatic sources and carried by the fluid residing in pores and cracks. Hydrothermal advection transfers about one quarter of the Earth's total heat power from the interior. Marine sediments are believed to be the largest repositories of solid ice-like methane clathrate hydrates. The compliance technique is an important tool for assessment of this resource. It makes use of the oceanic surface gravity waves to induce pressure variations on the sea floor and measure the corresponding vertical deformation. This thesis deals with the convective heat and mass transfer within the oceanic crust, as a fractured porous medium, and the elastic, quasi-static response of hydrated marine sediments to gravity wave loading. Both generic and site-specific applications are considered. Most applications are tackled numerically in three spatial dimensions. The major results are as follows. Fractures can trigger and maintain hydrothermal circulation. The permeability-thickness product in the direction of flow is an adequate parameter to represent the fracture if convection is not vigorous. A new temperature homogenization mechanism for the off-axial convection is proposed which is due to quasi-lateral circulation within a permeable zone between sediment cover and basalt. It explains both the observed correlation between surface heat flux and sediment thickness, as well as regular heat flux variations when no buried topography is present. A hydrothermal model for the CoAxial Segment of the Juan de Fuca Ridge predicts ridge-parallel convection with the low-temperature vents spaced 1 km apart. The compliance approach is feasible for a non-layered medium. The average compliance response depends on the bulk hydrate content, but not on a particular connectivity pattern
Numerical modeling of economic uncertainty
DEFF Research Database (Denmark)
Schjær-Jacobsen, Hans
2007-01-01
Representation and modeling of economic uncertainty is addressed by different modeling methods, namely stochastic variables and probabilities, interval analysis, and fuzzy numbers, in particular triple estimates. Focusing on discounted cash flow analysis numerical results are presented, comparisons...
BCJ numerators from reduced Pfaffian
Energy Technology Data Exchange (ETDEWEB)
Du, Yi-Jian [Center for Theoretical Physics, School of Physics and Technology, Wuhan University,No. 299 Bayi Road, Wuhan 430072 (China); Teng, Fei [Department of Physics and Astronomy, University of Utah,115 South 1400 East, Salt Lake City, UT 84112 (United States)
2017-04-07
By expanding the reduced Pfaffian in the tree level Cachazo-He-Yuan (CHY) integrands for Yang-Mills (YM) and nonlinear sigma model (NLSM), we can get the Bern-Carrasco-Johansson (BCJ) numerators in Del Duca-Dixon-Maltoni (DDM) form for arbitrary number of particles in any spacetime dimensions. In this work, we give a set of very straightforward graphic rules based on spanning trees for a direct evaluation of the BCJ numerators for YM and NLSM. Such rules can be derived from the Laplace expansion of the corresponding reduced Pfaffian. For YM, the each one of the (n−2)! DDM form BCJ numerators contains exactly (n−1)! terms, corresponding to the increasing trees with respect to the color order. For NLSM, the number of nonzero numerators is at most (n−2)!−(n−3)!, less than those of several previous constructions.
Numerical Verification Of Equilibrium Chemistry
International Nuclear Information System (INIS)
Piro, Markus; Lewis, Brent; Thompson, William T.; Simunovic, Srdjan; Besmann, Theodore M.
2010-01-01
A numerical tool is in an advanced state of development to compute the equilibrium compositions of phases and their proportions in multi-component systems of importance to the nuclear industry. The resulting software is being conceived for direct integration into large multi-physics fuel performance codes, particularly for providing boundary conditions in heat and mass transport modules. However, any numerical errors produced in equilibrium chemistry computations will be propagated in subsequent heat and mass transport calculations, thus falsely predicting nuclear fuel behaviour. The necessity for a reliable method to numerically verify chemical equilibrium computations is emphasized by the requirement to handle the very large number of elements necessary to capture the entire fission product inventory. A simple, reliable and comprehensive numerical verification method is presented which can be invoked by any equilibrium chemistry solver for quality assurance purposes.
DEFF Research Database (Denmark)
Karamehmedovic, Mirza; Knudsen, Kim; Wriedt, Thomas
, but the evaluation of their indicator functions can be numerically expensive. On the other hand, decomposition methods express the solution of the Laplace equation in the medium in terms of layer potentials and estimate the inclusion using boundary value error minimisation. However, matching the sources....... Similarly to the decomposition methods, our approach is based on a boundary layer representation of a solution of the Laplace equation in the medium, and it uses µa priori knowledge of the boundary condition satisfied at the interface between the inclusion and the medium. However, both of these developments...
Energy Technology Data Exchange (ETDEWEB)
Yoon, Su-Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sackett, John [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2014-08-01
1. Objectives To produce a validation database out of those recorded signals it will be necessary also to identify the documents need to reconstruct the status of reactor at the time of the beginning of the recordings. This should comprehends the core loading specification (assemblies type and location and burn-up) along with this data the assemblies drawings and the core drawings will be identified. The first task of the project will be identify the location of the sensors, with respect the reactor plant layout, and the physical quantities recorded by the Experimental Breeder Reactor-II (EBR-II) data acquisition system. This first task will allow guiding and prioritizing the selection of drawings needed to numerically reproduce those signals. 1.1 Scopes and Deliverables The deliverables of this project are the list of sensors in EBR-II system, the identification of storing location of those sensors, identification of a core isotopic composition at the moment of the start of system recording. Information of the sensors in EBR-II reactor system was summarized from the EBR-II system design descriptions listed in Section 1.2.
Effect of deformability on fluid flow through a fractured-porous medium
International Nuclear Information System (INIS)
Tsang, C.F.; Noorishad, J.; Witherspoon, P.A.
1985-01-01
A permeable geologic medium containing interstitial fluids generally undergoes deformation as the fluid pressure changes. Depending on the nature of the medium, the strain ranges from infinitesimal to finite quantities. This response is the result of a coupled hydraulic-mechanical phenomenon which can basically be formulated in the generalized three-dimensional theory of consolidation. Dealing mainly with media of little deformability, traditional hydrogeology accounts for medium deformability as far as it affects the volume of pore spaces, through the introduction of a coefficient of specific storage in the fluid flow equation. This treatment can be justified on the basis of a one-dimensional effective stress law and the assumption of homogeneity of the total stress field throughout the medium. The present paper uses a numerical model called ROCMAS (Noorishad et al., 1982; Noorishad e al., 1984) which was developed to calculate fluid flow through a deformable fractured-porous medium. The code employs the Finite Element Method based on a variational approach. It has been verified against a number of simple analytic solutions. In this work, the code is used to address the role of medium deformability in continuous and pulse testing techniques. The errors that may result because of application of traditional fluid flow methods are discussed. It is found that low pressure continuous well testing or pulse testing procedures can reduce such errors. 16 references, 9 figures, 1 table
Numerical evolutions beyond our belief
de Almeida, Guilherme; Colégio Militar Associação Portuguesa de Astrônomos Amadores (APAA) Lisboa – Portugal
2014-01-01
The everyday life situations gave us a good enough training to deal with numerical evolutions operated by arithmetic progressions, so in this specific case we can make good numerical predictions. But our common sense is not usually prepared to deal with numbers that grow, or shrink, according to geometrical progressions. In the last cases, our intuition strongly fails, showing that our intuition is not always right. We also fail in comparing some other situations which we are not trained. Thi...
Numerical experiments modelling turbulent flows
Trefilík, Jiří; Kozel, Karel; Příhoda, Jaromír
2014-03-01
The work aims at investigation of the possibilities of modelling transonic flows mainly in external aerodynamics. New results are presented and compared with reference data and previously achieved results. For the turbulent flow simulations two modifications of the basic k - ω model are employed: SST and TNT. The numerical solution was achieved by using the MacCormack scheme on structured non-ortogonal grids. Artificial dissipation was added to improve the numerical stability.
Numerical experiments modelling turbulent flows
Directory of Open Access Journals (Sweden)
Trefilík Jiří
2014-03-01
Full Text Available The work aims at investigation of the possibilities of modelling transonic flows mainly in external aerodynamics. New results are presented and compared with reference data and previously achieved results. For the turbulent flow simulations two modifications of the basic k – ω model are employed: SST and TNT. The numerical solution was achieved by using the MacCormack scheme on structured non-ortogonal grids. Artificial dissipation was added to improve the numerical stability.
Numerical Analysis of Multiscale Computations
Engquist, Björn; Tsai, Yen-Hsi R
2012-01-01
This book is a snapshot of current research in multiscale modeling, computations and applications. It covers fundamental mathematical theory, numerical algorithms as well as practical computational advice for analysing single and multiphysics models containing a variety of scales in time and space. Complex fluids, porous media flow and oscillatory dynamical systems are treated in some extra depth, as well as tools like analytical and numerical homogenization, and fast multipole method.
Numerical Hydrodynamics in General Relativity
Directory of Open Access Journals (Sweden)
Font José A.
2003-01-01
Full Text Available The current status of numerical solutions for the equations of ideal general relativistic hydrodynamics is reviewed. With respect to an earlier version of the article, the present update provides additional information on numerical schemes, and extends the discussion of astrophysical simulations in general relativistic hydrodynamics. Different formulations of the equations are presented, with special mention of conservative and hyperbolic formulations well-adapted to advanced numerical methods. A large sample of available numerical schemes is discussed, paying particular attention to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. A comprehensive summary of astrophysical simulations in strong gravitational fields is presented. These include gravitational collapse, accretion onto black holes, and hydrodynamical evolutions of neutron stars. The material contained in these sections highlights the numerical challenges of various representative simulations. It also follows, to some extent, the chronological development of the field, concerning advances on the formulation of the gravitational field and hydrodynamic equations and the numerical methodology designed to solve them.
Clean image synthesis and target numerical marching for optical imaging with backscattering light.
Xu, Min; Pu, Yang; Wang, Wubao
2011-03-14
Scanning backscattering imaging and independent component analysis (ICA) are used to probe targets hidden in the subsurface of a turbid medium. A new correction procedure is proposed and used to synthesize a "clean" image of a homogeneous host medium numerically from a set of raster-scanned "dirty" backscattering images of the medium with embedded targets. The independent intensity distributions on the surface of the medium corresponding to individual targets are then unmixed using ICA of the difference between the set of dirty images and the clean image. The target positions are localized by a novel analytical method, which marches the target to the surface of the turbid medium until a match with the retrieved independent component is accomplished. The unknown surface property of the turbid medium is automatically accounted for by this method. Employing clean image synthesis and target numerical marching, three-dimensional (3D) localization of objects embedded inside a turbid medium using independent component analysis in a backscattering geometry is demonstrated for the first time, using as an example, imaging a small piece of cancerous prostate tissue embedded in a host consisting of normal prostate tissue.
Meson's correlation functions in a nuclear medium
Directory of Open Access Journals (Sweden)
Chanyong Park
2016-09-01
Full Text Available We investigate meson's spectrum, decay constant and form factor in a nuclear medium through holographic two- and three-point correlation functions. To describe a nuclear medium composed of protons and neutrons, we consider a hard wall model on the thermal charged AdS geometry and show that due to the isospin interaction with a nuclear medium, there exist splittings of the meson's spectrum, decay constant and form factor relying on the isospin charge. In addition, we show that the ρ-meson's form factor describing an interaction with pseudoscalar fluctuation decreases when the nuclear density increases, while the interaction with a longitudinal part of an axial vector meson increases.
Ioversol contrast medium in canine neuroradiology
International Nuclear Information System (INIS)
Tudury, E.A.; Arias, M.V.B.; Camargo, P.L. de; Faria, M. de L.E.; Machado, C.E.G.
1997-01-01
Ioversol, a non-ionic, hydrosoluble iodine contrast medium at a concentration of 320mg I/ml was used to perform 26 contrast neuroradiographic studies (myelography, epidurography and cerebral ventriculography) in 22 dogs. Since this contrast medium is rapidly absorbed, proper radiographs were obtained within 30 minutes of injection. The product showed adequate radio-opacity, retention time, diffusion and liquor miscibility. Minimal side effects both during and after the radiographic procedures were observed. Not one patient developed seizures, in spite of the use of anesthetic protocols that included either zolarepan-tiletamine or levomepromazin- zilazine- or diazepam-sodium thiopental. The presentation of the contrast medium in a multiple dose vial was considered an advantage, since it decreases losses and allows repeated sterilization in autoclave [pt
Coherent neutrino interactions in a dense medium
International Nuclear Information System (INIS)
Kiers, K.; Weiss, N.
1997-01-01
Motivated by the effect of matter on neutrino oscillations (the MSW effect) we study in more detail the propagation of neutrinos in a dense medium. The dispersion relation for massive neutrinos in a medium is known to have a minimum at nonzero momentum p∼G F ρ/√(2). We study in detail the origin and consequences of this dispersion relation for both Dirac and Majorana neutrinos both in a toy model with only neutral currents and a single neutrino flavor and in a realistic open-quotes standard modelclose quotes with two neutrino flavors. We find that for a range of neutrino momenta near the minimum of the dispersion relation, Dirac neutrinos are trapped by their coherent interactions with the medium. This effect does not lead to the trapping of Majorana neutrinos. copyright 1997 The American Physical Society
Positron annihilation in the interstellar medium
Guessoum, Nidhal; Ramaty, Reuven; Lingenfelter, Richard E.
1991-01-01
Positronium formation and annihilation are studied in a model for the interstellar medium consisting of cold cloud cores, warm partially ionized cloud envelopes, and hot intercloud gas. The gamma-ray spectra resulting from positron annihilation in these components of the interstellar medium are calculated. The spectra from the individual components are then combined, using two limiting assumptions for the propagation of the positrons, namely, that the positrons propagate freely throughout the interstellar medium, and that the positrons are excluded from the cold cloud cores. In the first case, the bulk of the positrons annihilate in the cloud cores and the annihilation line exhibits broad wings resulting from the annihilation of positronium formed by charge exchange in flight. In the second case, the positrons annihilate mainly in the warm envelopes, and the line wings are suppressed.
Charmonium propagation through a dense medium
Directory of Open Access Journals (Sweden)
Kopeliovich B.Z.
2015-01-01
Full Text Available Attenuation of a colourless c̄c dipole propagating with a large momentum through a hot medium originates from two sources, Debye screening (melting, and inelastic collisions with surrounding scattering centres (absorption. The former never terminates completely production of a bound charmonium in heavy ion collisions, even at very high temperatures. The latter, is controlled my the magnitude of the dipole cross section, related to the transport coefficient, which is the rate of transverse momentum broadening in the medium. A novel procedure of Lorentz boosting of the Schrödinger equation is developed, which allows to calculate the charmonium survival probability employing the path-integral technique, incorporating both melting and absorption. A novel mechanism of charmonium regeneration in a dense medium is proposed.
International Nuclear Information System (INIS)
Sarazin, C.L.
1975-01-01
The purpose of this dissertation is to determine quantitatively the effects of U.V. absorbing dust on H II regions, and compare these effects with observations. Many observations indicate that dust grains are present within H II regions. An analytic theory is presented which describes all three of the effects of dust in H II regions. Although this model is relatively crude, it is useful in determining the approximate size of the modifications due to dust. In order to explore this problem more carefully, detailed numerical models of H II regions with dust were constructed. The ionization and thermal structure of these model H II regions is discussed. The observational consequences of the presence of dust are explored; the optical line intensities, radio continuum and line fluxes, and infrared emission of model H II regions with dust are given. These numerical models are compared with observations of diffuse nebulae. The optical line ratios are compared to several nearby bright H II regions, and it is found that the dust models may explain several anomalies in their spectrum
[A modified MacConkey medium].
Wang, J; Tong, M
1999-01-01
We used MacConkey Agar(MCA) medium powder as a basis and added 6-benzoy-2-naphthyl phosphate disodium salt to modify MCA medium. This method was identified by examining several kinds of enteric pathogenic bacteria. Thus it allows us to observe lactose fermentative and phosphatase reaction simultaneously and to recognize Enterobacteriaceae from non-fermentable bacteria on primary culture plates according to the color of colony. This improved method simplifies the recognition procedure and shortens the time so that it is helpful to correctly choosing identification kit.
Power converters for medium voltage networks
Islam, Md Rabiul; Zhu, Jianguo
2014-01-01
This book examines a number of topics, mainly in connection with advances in semiconductor devices and magnetic materials and developments in medium and large-scale renewable power plant technologies, grid integration techniques and new converter topologies, including advanced digital control systems for medium-voltage networks. The book's individual chapters provide an extensive compilation of fundamental theories and in-depth information on current research and development trends, while also exploring new approaches to overcoming some critical limitations of conventional grid integration te
Approximation and stability of three-dimensional natural convection flows in a porous medium
International Nuclear Information System (INIS)
Janotto, Marie-Laurence
1991-01-01
The equations of the three-dimensional natural convection in a porous medium within a differentially heated horizontal walls cavity are solved by a pseudo-spectral method. First we will present the evolution of the two main modes according to two models of convection. A few asymptotic properties connected to the small and large eddies are set up and numerically validated. A new approximate inertial manifold is then proposed. The numerical scheme used is an exponential fitting algorithm the convergence of which is proved. We will present the physical mechanism at the origin of the un-stationary three-dimensional convection at high Rayleigh numbers. (author) [fr
Ultimate regime of high Rayleigh number convection in a porous medium.
Hewitt, Duncan R; Neufeld, Jerome A; Lister, John R
2012-06-01
Well-resolved direct numerical simulations of 2D Rayleigh-Bénard convection in a porous medium are presented for Rayleigh numbers Ra≤4×10(4) which reveal that, contrary to previous indications, the linear classical scaling for the Nusselt number, Nu~Ra, is attained asymptotically. The flow dynamics are analyzed, and the interior of the vigorously convecting system is shown to be increasingly well described as Ra→∞ by a simple columnar "heat-exchanger" model with a single horizontal wave number k and a linear background temperature field. The numerical results are approximately fitted by k~Ra(0.4).
Steady thermal convection from a concentrated source in a porous medium
International Nuclear Information System (INIS)
Hickox, C.E.; Watts, H.A.
1976-11-01
Numerical and approximate analytical solutions are presented for the steady thermal convection in a porous medium resulting from a point source located on the lower boundary of a semi-infinite region. The approximate analytical solution is found to be adequate for Rayleigh numbers greater than 100. Below this value, it is necessary to use numerical techniques to obtain accurate representations of the temperature and flow fields. The results are useful for the preliminary analysis of heat transfer and fluid flow effects due to the implantation of encapsulated nuclear waste material in the seabed. 11 figures
Bhasin, Sheetal; Modi, H. A.
2012-01-01
The combination of medium ingredients has a profound influence on the metabolic pathways running in the microorganism which regulates the production of numerous metabolites. Glucose isomerase (GI), an enzyme with huge potential in the market, can isomerise glucose into fructose. GI is used widely for the production of High-Fructose Corn Syrup (HFCS). HFCS is used as a sweetener in food and pharmaceutical industries. Streptomyces are well-known producers of numerous enzymes including glucose i...
Numerical simulation of the tip aerodynamics and acoustics test
Tejero E, F.; Doerffer, P.; Szulc, O.; Cross, J. L.
2016-04-01
The application of an efficient flow control system on helicopter rotor blades may lead to improved aerodynamic performance. Recently, our invention of Rod Vortex Generators (RVGs) has been analyzed for helicopter rotor blades in hover with success. As a step forward, the study has been extended to forward flight conditions. For this reason, a validation of the numerical modelling for a reference helicopter rotor (without flow control) is needed. The article presents a study of the flow-field of the AH-1G helicopter rotor in low-, medium- and high-speed forward flight. The CFD code FLOWer from DLR has proven to be a suitable tool for the aerodynamic analysis of the two-bladed rotor without any artificial wake modelling. It solves the URANS equations with LEA (Linear Explicit Algebraic stress) k-ω model using the chimera overlapping grids technique. Validation of the numerical model uses comparison with the detailed flight test data gathered by Cross J. L. and Watts M. E. during the Tip Aerodynamics and Acoustics Test (TAAT) conducted at NASA in 1981. Satisfactory agreements for all speed regimes and a presence of significant flow separation in high-speed forward flight suggest a possible benefit from the future implementation of RVGs. The numerical results based on the URANS approach are presented not only for a popular, low-speed case commonly used in rotorcraft community for CFD codes validation but preferably for medium- and high-speed test conditions that have not been published to date.
Yvonnet, Julien; Liu, Liping
2017-01-01
International audience; In the present work, a numerical finite element framework is introduced to model and solve the response of nonlinear soft dielectrics, including the effects of Maxwell stress and flexoelectricity at finite strains. Weak forms, finite element discretizations and constistent linearizations, able to handle strain gradient in the context of flexo-electricity are introduced. Numerical algorithms for the treatment of a soft dielectric in a surrounding medium are presented, m...
Dynamics of unstable sound waves in a non-equilibrium medium at the nonlinear stage
Khrapov, Sergey; Khoperskov, Alexander
2018-03-01
A new dispersion equation is obtained for a non-equilibrium medium with an exponential relaxation model of a vibrationally excited gas. We have researched the dependencies of the pump source and the heat removal on the medium thermodynamic parameters. The boundaries of sound waves stability regions in a non-equilibrium gas have been determined. The nonlinear stage of sound waves instability development in a vibrationally excited gas has been investigated within CSPH-TVD and MUSCL numerical schemes using parallel technologies OpenMP-CUDA. We have obtained a good agreement of numerical simulation results with the linear perturbations dynamics at the initial stage of the sound waves growth caused by instability. At the nonlinear stage, the sound waves amplitude reaches the maximum value that leads to the formation of shock waves system.
Prakash, Jyoti; Kumar, Pankaj; Kumari, Kultaran; Manan, Shweta
2018-02-01
The effect of magnetic-field-dependent (MFD) viscosity on the thermal convection in a ferromagnetic fluid in the presence of a uniform vertical magnetic field is investigated for a fluid layer saturating a densely packed porous medium using the Darcy model. A correction is applied to the model by Sunil et al. [Z. Naturforsch. 59, 397 (2004)], which is very important to predict the correct behaviour of MFD viscosity. A linear stability analysis is carried out for stationary modes. The critical wave number and critical Rayleigh number for the onset of instability, for the case of free boundaries, are determined numerically for sufficiently large values of the magnetic parameter M1. Numerical results are obtained and illustrated graphically. It is shown that MFD viscosity has stabilizing effect on the system, whereas medium permeability has a destabilizing effect.
Experimental and numerical analysis of a knee endoprosthesis numerical model
Directory of Open Access Journals (Sweden)
L. Zach
2016-07-01
Full Text Available The aim of this study is to create and verify a numerical model for a Medin Modular orthopedic knee-joint implant by investigating contact pressure, its distribution and contact surfaces. An experiment using Fuji Prescale pressure sensitive films and a finite element analysis (FEA using Abaqus software were carried out. The experimental data were evaluated using a special designed program and were compared with the results of the analysis. The designed evaluation program had been constructed on the basis of results obtained from a supplementary calibration experiment. The applicability of the numerical model for the real endoprosthesis behavior prediction was proven on the basis of their good correlation.
Shull, J. Michael; France, Kevin; Danforth, Charles W.; Smith, Britton; Tumlinson, Jason
2010-10-01
We report ultraviolet spectra of the high-redshift (z em ≈ 2.9) quasar, HE 2347 - 4342, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope. Spectra in the G130M (medium resolution, 1135-1440 Å) and G140L (low resolution, 1030-2000 Å) gratings exhibit patchy Gunn-Peterson absorption in the 303.78 Å Lyα line of He II between z = 2.39-2.87 (G140L) and z = 2.74-2.90 (G130M). With COS, we obtain better spectral resolution, higher signal-to-noise ratio (S/N), and better determined backgrounds than previous studies, with sensitivity to abundance fractions x He II ≈ 0.01 in filaments of the cosmic web. The He II optical depths from COS are higher than those with the Far Ultraviolet Spectroscopic Explorer and range from τHe II = 5, with a slow recovery in mean optical depth to langτHe II rang numerous flux-transmission windows between 1135 and 1186 Å. The He II absorption extends to 1186.26 Å (z = 2.905), including associated absorbers with z abs ≈ z QSO and minimal "proximity effect" of flux transmission at the He II edge. We propose a QSO systemic redshift z QSO = 2.904 ± 0.002, some Δz = 0.019 higher than that derived from O I λ1302 emission. Three long troughs (4-10 Å or 25-60 Mpc comoving distance) of strong He II absorption between z = 2.75and2.90 are uncharacteristic of the intergalactic medium if He II reionized at zr ≈ 3. Contrary to recent indirect estimates (zr = 3.2 ± 0.2) from H I optical depths, the epoch of He II reionization may extend to z <~ 2.7. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.
African Journals Online (AJOL)
userpc
NI(II) COMPLEXES WITH SCHIFF BASE DERIVED FROM SULPHANILAMINE AND. SALICYLALDEHYDE. ⃰Siraj, I. T. and ... with nickel(II) and cobalt(II) chloride in 2:1 mole ratio yielded Ni(II) and Co(II) complexes respectively. The synthesized .... coordinated ligand (coordination number) was determined using the relation ...
Synthesis and characterisation of Cu (II), Ni (II), Mn (II), Zn (II) and ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Chemical Sciences; Volume 113; Issue 3. Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II) Schiff base complexes derived from o-phenylenediamine and acetoacetanilide. N Raman Y Pitchaikani Raja A Kulandaisamy. Inorganic Volume 113 Issue 3 June 2001 pp 183-189 ...
Mixed Convection Flow along a Stretching Cylinder in a Thermally Stratified Medium
Directory of Open Access Journals (Sweden)
Swati Mukhopadhyay
2012-01-01
Full Text Available An analysis for the axisymmetric laminar boundary layer mixed convection flow of a viscous and incompressible fluid towards a stretching cylinder immersed in a thermally stratified medium is presented in this paper. Similarity transformation is employed to convert the governing partial differential equations into highly nonlinear ordinary differential equations. Numerical solutions of these equations are obtained by a shooting method. It is found that the heat transfer rate at the surface is lower for flow in a thermally stratified medium compared to that of an unstratified medium. Moreover, both the skin friction coefficient and the heat transfer rate at the surface are larger for a cylinder compared to that for a flat plate.
Assessment of community noise for a medium-range airplane with open-rotor engines
Kopiev, V. F.; Shur, M. L.; Travin, A. K.; Belyaev, I. V.; Zamtfort, B. S.; Medvedev, Yu. V.
2017-11-01
Community noise of a hypothetical medium-range airplane equipped with open-rotor engines is assessed by numerical modeling of the aeroacoustic characteristics of an isolated open rotor with the simplest blade geometry. Various open-rotor configurations are considered at constant thrust, and the lowest-noise configuration is selected. A two-engine medium-range airplane at known thrust of bypass turbofan engines at different segments of the takeoff-landing trajectory is considered, after the replacement of those engines by the open-rotor engines. It is established that a medium-range airplane with two open-rotor engines meets the requirements of Chapter 4 of the ICAO standard with a significant margin. It is shown that airframe noise makes a significant contribution to the total noise of an airplane with open-rotor engines at landing.
Interaction of few-cycle laser pulses in an isotropic nonlinear medium
International Nuclear Information System (INIS)
Oganesyan, D L; Vardanyan, A O
2007-01-01
The interaction of few-cycle laser pulses propagating in an isotropic nonlinear medium is studied theoretically. A system of nonlinear Maxwell's equations is integrated numerically with respect to time by the finite difference method. The interaction of mutually orthogonal linearly polarised 0.81-μm, 10-fs pulses is considered. Both the instant Kerr polarisation response and Raman inertial response of the medium in the nonlinear part of the medium are taken into account. The spectral shift of the probe pulse caused by the cross-action of the reference pulse is studied. The spectra of the interacting pulses are studied for different time delays between them and the shifts of these spectra are obtained as a function of the time delay. (nonlinear optical phenomena)
International Nuclear Information System (INIS)
Liffman, K.
1990-01-01
The effects of catastrophic collisional fragmentation and diffuse medium accretion on a the interstellar dust system are computed using a Monte Carlo computer model. The Monte Carlo code has as its basis an analytic solution of the bulk chemical evolution of a two-phase interstellar medium, described by Liffman and Clayton (1989). The model is subjected to numerous different interstellar processes as it transfers from one interstellar phase to another. Collisional fragmentation was found to be the dominant physical process that shapes the size spectrum of interstellar dust. It was found that, in the diffuse cloud phase, 90 percent of the refractory material is locked up in the dust grains, primarily due to accretion in the molecular medium. This result is consistent with the observed depletions of silicon. Depletions were found to be affected only slightly by diffuse cloud accretion. 42 refs
World War II Informational Fact Sheets.
Department of Defense, Washington, DC.
This commemorative book provides numerous fact sheets on various aspects of World War II, both on the fighting front and the homefront. Replicas of posters of the war era, descriptions of battles with maps, contributions of women and minorities to the war effort, even music of the wartime era, add to this collection of resource materials useful to…