Loss models for long Josephson junctions
DEFF Research Database (Denmark)
Olsen, O. H.; Samuelsen, Mogens Rugholm
1984-01-01
A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement.......A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement....
Exotic hadron and string junction model
International Nuclear Information System (INIS)
Imachi, Masahiro
1978-01-01
Hadron structure is investigated adopting string junction model as a realization of confinement. Besides exotic hadrons (M 4 , B 5 etc.), unconventional hadrons appear. A mass formula for these hadrons is proposed. New selection rule is introduced which requires the covalence of constituent line at hadron vertex. New duality appears due to the freedom of junction, especially in anti BB→anti BB reaction. A possible assignment of exotic and unconventional hadrons to recently observed narrow meson states is presented. (auth.)
Modeling Bloch oscillations in nanoscale Josephson junctions
Vora, Heli; Kautz, R. L.; Nam, S. W.; Aumentado, J.
2018-01-01
Bloch oscillations in nanoscale Josephson junctions with a Coulomb charging energy comparable to the Josephson coupling energy are explored within the context of a model previously considered by Geigenmüller and Schön that includes Zener tunneling and treats quasiparticle tunneling as an explicit shot-noise process. The dynamics of the junction quasicharge are investigated numerically using both Monte Carlo and ensemble approaches to calculate voltage-current characteristics in the presence of microwaves. We examine in detail the origin of harmonic and subharmonic Bloch steps at dc biases I = (n/m)2ef induced by microwaves of frequency f and consider the optimum parameters for the observation of harmonic (m = 1) steps. We also demonstrate that the GS model allows a detailed semiquantitative fit to experimental voltage-current characteristics previously obtained at the Chalmers University of Technology, confirming and strengthening the interpretation of the observed microwave-induced steps in terms of Bloch oscillations. PMID:29577106
ACCIDENT PREDICTION MODELS FOR UNSIGNALISED URBAN JUNCTIONS IN GHANA
Mohammed SALIFU, MSc., PhD, MIHT, MGhIE
2004-01-01
The main objective of this study was to provide an improved method for safety appraisal in Ghana through the development and application of suitable accident prediction models for unsignalised urban junctions. A case study was designed comprising 91 junctions selected from the two most cosmopolitan cities in Ghana. A wide range of traffic and road data together with the corresponding accident data for each junction for the three-year period 1996-1998 was utilized in the model development p...
Shunted-Josephson-junction model. I. The autonomous case
DEFF Research Database (Denmark)
Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.
1977-01-01
The shunted-Josephson-junction model: the parallel combination of a capacitance, a phase-dependent conductance, and an ideal junction element biased by a constant current, is discussed for arbitrary values of the junction parameters. The main objective is to provide a qualitative understanding...... current-voltage curves are presented. The case with a time-dependent monochromatic bias current is treated in a similar fashion in the companion paper....
International Nuclear Information System (INIS)
Golightly, C.E.; Ravindranath, T.K.; Belblidia, L.A.; O'Farrell, D.; Andersen, P.S.
2006-01-01
The paper describes the core model upgrade of the WNP-2 training simulator and the reasons for the upgrade. The core model as well as the interface with the rest of the simulator are briefly described . The paper also describes the procedure that will be used by WNP-2 to update the simulator core data after future core reloads. Results from the fully integrated simulator are presented. (author)
Shunted-Josephson-junction model. II. The nonautonomous case
DEFF Research Database (Denmark)
Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.
1977-01-01
The shunted-Josephson-junction model with a monochromatic ac current drive is discussed employing the qualitative methods of the theory of nonlinear oscillations. As in the preceding paper dealing with the autonomous junction, the model includes a phase-dependent conductance and a shunt capacitance....... The mathematical discussion makes use of the phase-space representation of the solutions to the differential equation. The behavior of the trajectories in phase space is described for different characteristic regions in parameter space and the associated features of the junction IV curve to be expected are pointed...... out. The main objective is to provide a qualitative understanding of the junction behavior, to clarify which kinds of properties may be derived from the shunted-junction model, and to specify the relative arrangement of the important domains in the parameter-space decomposition....
DNA Three Way Junction Core Decorated with Amino Acids-Like Residues-Synthesis and Characterization
Directory of Open Access Journals (Sweden)
Claudia Addamiano
2016-08-01
Full Text Available Construction and physico-chemical behavior of DNA three way junction (3WJ functionalized by protein-like residues (imidazole, alcohol and carboxylic acid at unpaired positions at the core is described. One 5′-C(S-propargyl-thymidine nucleotide was specifically incorporated on each strand to react through a post synthetic CuACC reaction with either protected imidazolyl-, hydroxyl- or carboxyl-azide. Structural impacts of 5′-C(S-functionalization were investigated to evaluate how 3WJ flexibility/stability is affected.
Stevenson, D. J.
1981-01-01
Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.
Modeling Bloch oscillations in ultra-small Josephson junctions
Vora, Heli; Kautz, Richard; Nam, Sae Woo; Aumentado, Jose
In a seminal paper, Likharev et al. developed a theory for ultra-small Josephson junctions with Josephson coupling energy (Ej) less than the charging energy (Ec) and showed that such junctions demonstrate Bloch oscillations which could be used to make a fundamental current standard that is a dual of the Josephson volt standard. Here, based on the model of Geigenmüller and Schön, we numerically calculate the current-voltage relationship of such an ultra-small junction which includes various error processes present in a nanoscale Josephson junction such as random quasiparticle tunneling events and Zener tunneling between bands. This model allows us to explore the parameter space to see the effect of each process on the width and height of the Bloch step and serves as a guide to determine whether it is possible to build a quantum current standard of a metrological precision using Bloch oscillations.
A charge-based model of Junction Barrier Schottky rectifiers
Latorre-Rey, Alvaro D.; Mudholkar, Mihir; Quddus, Mohammed T.; Salih, Ali
2018-06-01
A new charge-based model of the electric field distribution for Junction Barrier Schottky (JBS) diodes is presented, based on the description of the charge-sharing effect between the vertical Schottky junction and the lateral pn-junctions that constitute the active cell of the device. In our model, the inherently 2-D problem is transformed into a simple but accurate 1-D problem which has a closed analytical solution that captures the reshaping and reduction of the electric field profile responsible for the improved electrical performance of these devices, while preserving physically meaningful expressions that depend on relevant device parameters. The validation of the model is performed by comparing calculated electric field profiles with drift-diffusion simulations of a JBS device showing good agreement. Even though other fully 2-D models already available provide higher accuracy, they lack physical insight making the proposed model an useful tool for device design.
International Nuclear Information System (INIS)
Stevenson, D.J.
1981-01-01
The combination of seismology, high pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to strong constraints on core models. The synthesis presented here is devoted to the defense of the following properties: (1) core formation was contemporaneous with earth accretion; (2) the outer, liquid core is predominately iron but cannot be purely iron; (3) the inner core-outer core boundary represents a thermodynamic equilibrium between a liquid alloys and a predominanately iron solid; (4) thermodynamic and transport properties of outer core can be estimated from liquid-state theories; and (5) the outer core is probably adiabatic and uniform in composition. None of these propositions are universally accepted by geophysicists. But, the intent of this paper is to present a coherent picture which explains most of the data with the fewest ad hoc assumptions. Areas in which future progress is both essential and likely are geo- and cosmochronology, seismological determinations of core structure, fluid dynamics of the core and mantle, and condensed matter physics
One dimensional reactor core model
International Nuclear Information System (INIS)
Kostadinov, V.; Stritar, A.; Radovo, M.; Mavko, B.
1984-01-01
The one dimensional model of neutron dynamic in reactor core was developed. The core was divided in several axial nodes. The one group neutron diffusion equation for each node is solved. Feedback affects of fuel and water temperatures is calculated. The influence of xenon, boron and control rods is included in cross section calculations for each node. The system of equations is solved implicitly. The model is used in basic principle Training Simulator of NPP Krsko. (author)
Directory of Open Access Journals (Sweden)
Hanqian Mao
2016-09-01
Full Text Available The exon junction complex (EJC is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease.
Gap junction modulation by extracellular signaling molecules: the thymus model
Directory of Open Access Journals (Sweden)
Alves L.A.
2000-01-01
Full Text Available Gap junctions are intercellular channels which connect adjacent cells and allow direct exchange of molecules of low molecular weight between them. Such a communication has been described as fundamental in many systems due to its importance in coordination, proliferation and differentiation. Recently, it has been shown that gap junctional intercellular communication (GJIC can be modulated by several extracellular soluble factors such as classical hormones, neurotransmitters, interleukins, growth factors and some paracrine substances. Herein, we discuss some aspects of the general modulation of GJIC by extracellular messenger molecules and more particularly the regulation of such communication in the thymus gland. Additionally, we discuss recent data concerning the study of different neuropeptides and hormones in the modulation of GJIC in thymic epithelial cells. We also suggest that the thymus may be viewed as a model to study the modulation of gap junction communication by different extracellular messengers involved in non-classical circuits, since this organ is under bidirectional neuroimmunoendocrine control.
Multiband model for tunneling in MgB2 junctions
Brinkman, Alexander; Golubov, Alexandre Avraamovitch; Rogalla, Horst; Dolgov, O.V.; Kortus, J.; Kong, Y.; Jepsen, O.; Andersen, O.K.
2002-01-01
A theoretical model for quasiparticle and Josephson tunneling in multiband superconductors is developed and applied to MgB2-based junctions. The gap functions in different bands in MgB2 are obtained from an extended Eliashberg formalism, using the results of band structure calculations. The
DOE-Grand Junction logging model data synopsis
International Nuclear Information System (INIS)
Mathews, M.A.; Koizumi, C.J.; Evans, H.B.
1978-05-01
This synopsis provides the available data concerning the logging models at the DoE-Grand Junction facility, to date (1976). Because gamma-ray logs are used in uranium exploration to estimate the grade (percent U 3 O 8 ) and the thickness of uranium ore zones in exploration drill holes, logging models are required to calibrate the gamma-ray logging equipment in order to obtain accuracy, uniformity, standardization, and repeatability during logging. This quality control is essential for accurate ore reserve calculations and for estimates of ore potential. The logging models at the DoE-Grand Junction facility are available for use by private industry in calibrating their gamma-ray logging equipment. 21 figures, 26 tables
International Nuclear Information System (INIS)
Tikhomirov, A. V.; Gorokhov, A. K.
2007-01-01
The objective of this paper is creation of precision test model for WWER RP neutron-physics calculations. The model is considered as a tool for verification of deterministic computer codes that enables to reduce conservatism of design calculations and enhance WWER RP competitiveness. Precision calculations were performed using code MCNP5/1/ (Monte Carlo method). Engineering computer package Sapfir 9 5andRC V VER/2/ is used in comparative analysis of the results, it was certified for design calculations of WWER RU neutron-physics characteristic. The object of simulation is the first fuel loading of Volgodon NPP RP. Peculiarities of transition in calculation using MCNP5 from 2D geometry to 3D geometry are shown on the full-scale model. All core components as well as radial and face reflectors, automatic regulation in control and protection system control rod are represented in detail description according to the design. The first stage of application of the model is assessment of accuracy of calculation of the core power. At the second stage control and protection system control rod worth was assessed. Full scale RP representation in calculation using code MCNP5 is time consuming that calls for parallelization of computational problem on multiprocessing computer (Authors)
Structure modeling and mutational analysis of gap junction beta 2 ...
African Journals Online (AJOL)
Yomi
2012-04-03
Apr 3, 2012 ... Three dimensional (3 D) structure is very useful for understanding biological functions. Gap junction beta 2 (GJB2), human gene encoding for gap junction beta 2 protein is involved in ... Research in deafness became real.
Interfacial Thermal Transport via One-Dimensional Atomic Junction Model
Directory of Open Access Journals (Sweden)
Guohuan Xiong
2018-03-01
Full Text Available In modern information technology, as integration density increases rapidly and the dimension of materials reduces to nanoscale, interfacial thermal transport (ITT has attracted widespread attention of scientists. This review introduces the latest theoretical development in ITT through one-dimensional (1D atomic junction model to address the thermal transport across an interface. With full consideration of the atomic structures in interfaces, people can apply the 1D atomic junction model to investigate many properties of ITT, such as interfacial (Kapitza resistance, nonlinear interface, interfacial rectification, and phonon interference, and so on. For the ballistic ITT, both the scattering boundary method (SBM and the non-equilibrium Green’s function (NEGF method can be applied, which are exact since atomic details of actual interfaces are considered. For interfacial coupling case, explicit analytical expression of transmission coefficient can be obtained and it is found that the thermal conductance maximizes at certain interfacial coupling (harmonic mean of the spring constants of the two leads and the transmission coefficient is not a monotonic decreasing function of phonon frequency. With nonlinear interaction—phonon–phonon interaction or electron–phonon interaction at interface, the NEGF method provides an efficient way to study the ITT. It is found that at weak linear interfacial coupling, the nonlinearity can improve the ITT, but it depresses the ITT in the case of strong-linear coupling. In addition, the nonlinear interfacial coupling can induce thermal rectification effect. For interfacial materials case which can be simulated by a two-junction atomic chain, phonons show interference effect, and an optimized thermal coupler can be obtained by tuning its spring constant and atomic mass.
Structure of the exon junction core complex with a trapped DEAD-box ATPase bound to RNA
DEFF Research Database (Denmark)
Andersen, Christian Brix Folsted; Ballut, Lionel; Johansen, Jesper Sanderhoff
2006-01-01
exon junction core complex containing the DEAD-box adenosine triphosphatase (ATPase) eukaryotic initiation factor 4AIII (eIF4AIII) bound to an ATP analog, MAGOH, Y14, a fragment of MLN51, and a polyuracil mRNA mimic. eIF4AIII interacts with the phosphate-ribose backbone of six consecutive nucleotides...... and prevents part of the bound RNA from being double stranded. The MAGOH and Y14 subunits lock eIF4AIII in a prehydrolysis state, and activation of the ATPase probably requires only modest conformational changes in eIF4AIII motif I....
A three-dimensional model of a gap junction
International Nuclear Information System (INIS)
Xylouris, K.; Wittum, G.
2009-01-01
Gap junctions are effective electric couplings between neurons and form a very important way of communication between them. Since they can be considered as the points on the neuron's membrane on which for example dendrites of different cells become one piece, in three dimensions they can be modelled by observing this property in the created geometry. Thus they can be easily made part in an already existing 3-dimensional model for signal propagation on the neuron's membrane, if the geometries are chosen in such a way respect the blending of the membranes. A small network of two cells was created, which blend in their dendrites and a simulation of the three-dimensional model was carried out which reveals the fast transmission of the signal from one cell to the other.
Modeling of charge transport in ion bipolar junction transistors.
Volkov, Anton V; Tybrandt, Klas; Berggren, Magnus; Zozoulenko, Igor V
2014-06-17
Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poisson's and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.
Nuclear reactor core modelling in multifunctional simulators
International Nuclear Information System (INIS)
Puska, E.K.
1999-01-01
The thesis concentrates on the development of nuclear reactor core models for the APROS multifunctional simulation environment and the use of the core models in various kinds of applications. The work was started in 1986 as a part of the development of the entire APROS simulation system. The aim was to create core models that would serve in a reliable manner in an interactive, modular and multifunctional simulator/plant analyser environment. One-dimensional and three-dimensional core neutronics models have been developed. Both models have two energy groups and six delayed neutron groups. The three-dimensional finite difference type core model is able to describe both BWR- and PWR-type cores with quadratic fuel assemblies and VVER-type cores with hexagonal fuel assemblies. The one- and three-dimensional core neutronics models can be connected with the homogeneous, the five-equation or the six-equation thermal hydraulic models of APROS. The key feature of APROS is that the same physical models can be used in various applications. The nuclear reactor core models of APROS have been built in such a manner that the same models can be used in simulator and plant analyser applications, as well as in safety analysis. In the APROS environment the user can select the number of flow channels in the three-dimensional reactor core and either the homogeneous, the five- or the six-equation thermal hydraulic model for these channels. The thermal hydraulic model and the number of flow channels have a decisive effect on the calculation time of the three-dimensional core model and thus, at present, these particular selections make the major difference between a safety analysis core model and a training simulator core model. The emphasis on this thesis is on the three-dimensional core model and its capability to analyse symmetric and asymmetric events in the core. The factors affecting the calculation times of various three-dimensional BWR, PWR and WWER-type APROS core models have been
Nuclear reactor core modelling in multifunctional simulators
Energy Technology Data Exchange (ETDEWEB)
Puska, E.K. [VTT Energy, Nuclear Energy, Espoo (Finland)
1999-06-01
The thesis concentrates on the development of nuclear reactor core models for the APROS multifunctional simulation environment and the use of the core models in various kinds of applications. The work was started in 1986 as a part of the development of the entire APROS simulation system. The aim was to create core models that would serve in a reliable manner in an interactive, modular and multifunctional simulator/plant analyser environment. One-dimensional and three-dimensional core neutronics models have been developed. Both models have two energy groups and six delayed neutron groups. The three-dimensional finite difference type core model is able to describe both BWR- and PWR-type cores with quadratic fuel assemblies and VVER-type cores with hexagonal fuel assemblies. The one- and three-dimensional core neutronics models can be connected with the homogeneous, the five-equation or the six-equation thermal hydraulic models of APROS. The key feature of APROS is that the same physical models can be used in various applications. The nuclear reactor core models of APROS have been built in such a manner that the same models can be used in simulator and plant analyser applications, as well as in safety analysis. In the APROS environment the user can select the number of flow channels in the three-dimensional reactor core and either the homogeneous, the five- or the six-equation thermal hydraulic model for these channels. The thermal hydraulic model and the number of flow channels have a decisive effect on the calculation time of the three-dimensional core model and thus, at present, these particular selections make the major difference between a safety analysis core model and a training simulator core model. The emphasis on this thesis is on the three-dimensional core model and its capability to analyse symmetric and asymmetric events in the core. The factors affecting the calculation times of various three-dimensional BWR, PWR and WWER-type APROS core models have been
Comparison of band-to-band tunneling models in Si and Si—Ge junctions
International Nuclear Information System (INIS)
Jiao Yipeng; Wang Taihuan; Wei Kangliang; Du Gang; Liu Xiaoyan
2013-01-01
We compared several different band-to-band tunneling (BTBT) models with both Sentaurus and the two-dimensional full-band Monte Carlo simulator in Si homo-junctions and Si—Ge hetero-junctions. It was shown that in Si homo-junctions, different models could achieve similar results. However, in the Si—Ge hetero-junctions, there were significant differences among these models at high reverse biases (over 2 V). Compared to the nonlocal model, the local models in Sentaurus underrated the BTBT rate distinctly, and the Monte Carlo method was shown to give a better approximation. Additionally, it was found that in the Si region near the interface of the Si—Ge hetero-junctions, the direct tunneling rates increased largely due to the interaction of the band structures of Si and Ge. (semiconductor physics)
Naya, Shin-Ichi; Kume, Takahiro; Akashi, Ryo; Fujishima, Musashi; Tada, Hiroaki
2018-01-31
A key material for artificial photosynthesis including water splitting is heteronanostructured (HNS) photocatalysts. The photocatalytic activity depends on the geometry and dimension, and the quality of junctions between the components. Here we present a half-cut Au(core)-CdS(shell) (HC-Au@CdS) nanoegg as a new HNS plasmonic photocatalyst for water splitting. UV-light irradiation of Au nanoparticle (NP)-loaded ZnO (Au/ZnO) at 50 °C induces the selective deposition of hexagonal CdS on the Au surface of Au/ZnO with an epitaxial (EPI) relation of CdS{0001}/Au{111}. The subsequent selective dissolution of the ZnO support at room temperature yields HC-Au@CdS with the Au NP size and EPI junction (#) retained. Red-light irradiation (λ ex = 640 nm) of HC-Au@#CdS gives rise to continuous stoichiometric water splitting with an unprecedentedly high external quantum yield of 0.24%.
International Nuclear Information System (INIS)
1999-01-01
In order to improve technical - economical parameters fuel with 2.4% enrichment and burnable absorber is started to be used at Ignalina NPP. Using code QUABOX/CUBBOX the main neutronic - physical characteristics were calculated for selected reactor core conditions
Three-dimensional models of conventional and vertical junction laser-photovoltaic energy converters
Heinbockel, John H.; Walker, Gilbert H.
1988-01-01
Three-dimensional models of both conventional planar junction and vertical junction photovoltaic energy converters have been constructed. The models are a set of linear partial differential equations and take into account many photoconverter design parameters. The model is applied to Si photoconverters; however, the model may be used with other semiconductors. When used with a Nd laser, the conversion efficiency of the Si vertical junction photoconverter is 47 percent, whereas the efficiency for the conventional planar Si photoconverter is only 17 percent. A parametric study of the Si vertical junction photoconverter is then done in order to describe the optimum converter for use with the 1.06-micron Nd laser. The efficiency of this optimized vertical junction converter is 44 percent at 1 kW/sq cm.
A numerical model of p-n junctions bordering on surfaces
Energy Technology Data Exchange (ETDEWEB)
Altermatt, P.P.; Aberle, A.G.; Jianhua Zhao; Aihua Wang; Heiser, G. [University of New South Wales, Sydney (Australia). Centre for Photovolatic Engineering
2002-10-01
Many solar cell structures contain regions where the emitter p-n junction borders on the surface. If the surface is not well passivated, a large amount of recombination occurs in such regions. This type of recombination is influenced by the electrostatics of both the p-n junction and the surface, and hence it is different from the commonly described recombination phenomena occurring in the p-n junction within the bulk. We developed a two-dimensional model for the recombination mechanisms occurring in emitter p-n junctions bordering on surfaces. The model is validated by reproducing the experimental I-V curves of specially designed silicon solar cells. It is shown under which circumstances a poor surface passivation, near where the p-n junction borders on the surface, reduces the fill factor and the open-circuit voltage. The model can be applied to many other types of solar cells. (author)
Nonlinear Model of Tape Wound Core Transformers
Directory of Open Access Journals (Sweden)
A. Vahedi
2015-03-01
Full Text Available Recently, tape wound cores due to their excellent magnetic properties, are widely used in different types of transformers. Performance prediction of these transformers needs an accurate model with ability to determine flux distribution within the core and magnetic loss. Spiral structure of tape wound cores affects the flux distribution and always cause complication of analysis. In this paper, a model based on reluctance networks method is presented for analysis of magnetic flux in wound cores. Using this model, distribution of longitudinal and transverse fluxes within the core can be determined. To consider the nonlinearity of the core, a dynamic hysteresis model is included in the presented model. Having flux density in different points of the core, magnetic losses can be calculated. To evaluate the validity of the model, results are compared with 2-D FEM simulations. In addition, a transformer designed for series-resonant converter and simulation results are compared with experimental measurements. Comparisons show accuracy of the model besides simplicity and fast convergence
SPICE modelling of magnetic tunnel junctions written by spin-transfer torque
Energy Technology Data Exchange (ETDEWEB)
Guo, W; Prenat, G; De Mestier, N; Baraduc, C; Dieny, B [SPINTEC, UMR(8191), INAC, CEA/CNRS/UJF, 17 Av. des Martyrs, 38054 Grenoble Cedex 9 (France); Javerliac, V; El Baraji, M, E-mail: guillaume.prenat@cea.f [CROCUS Technology, 5 Place Robert Schuman, 38025 Grenoble (France)
2010-06-02
Spintronics aims at extending the possibility of conventional electronics by using not only the charge of the electron but also its spin. The resulting spintronic devices, combining the front-end complementary metal oxide semiconductor technology of electronics with a magnetic back-end technology, employ magnetic tunnel junctions (MTJs) as core elements. With the intent of simulating a circuit without fabricating it first, a reliable MTJ electrical model which is applicable to the standard SPICE (Simulation Program with Integrated Circuit Emphasis) simulator is required. Since such a model was lacking so far, we present a MTJ SPICE model whose magnetic state is written by using the spin-transfer torque effect. This model has been developed in the C language and validated on the Cadence Virtuoso Platform with a Spectre simulator. Its operation is similar to that of the standard BSIM (Berkeley Short-channel IGFET Model) SPICE model of the MOS transistor and fully compatible with the SPICE electrical simulator. The simulation results obtained using this model have been found in good accord with those theoretical macrospin calculations and results.
A Core Language for Separate Variability Modeling
DEFF Research Database (Denmark)
Iosif-Lazăr, Alexandru Florin; Wasowski, Andrzej; Schaefer, Ina
2014-01-01
Separate variability modeling adds variability to a modeling language without requiring modifications of the language or the supporting tools. We define a core language for separate variability modeling using a single kind of variation point to define transformations of software artifacts in object...... hierarchical dependencies between variation points via copying and flattening. Thus, we reduce a model with intricate dependencies to a flat executable model transformation consisting of simple unconditional local variation points. The core semantics is extremely concise: it boils down to two operational rules...
Core monitoring with analytical model adaption
International Nuclear Information System (INIS)
Linford, R.B.; Martin, C.L.; Parkos, G.R.; Rahnema, F.; Williams, R.D.
1992-01-01
The monitoring of BWR cores has evolved rapidly due to more capable computer systems, improved analytical models and new types of core instrumentation. Coupling of first principles diffusion theory models such as applied to design to the core instrumentation has been achieved by GE with an adaptive methodology in the 3D Minicore system. The adaptive methods allow definition of 'leakage parameters' which are incorporated directly into the diffusion models to enhance monitoring accuracy and predictions. These improved models for core monitoring allow for substitution of traversing in-core probe (TIP) and local power range monitor (LPRM) with calculations to continue monitoring with no loss of accuracy or reduction of thermal limits. Experience in small BWR cores has shown that with one out of three TIP machines failed there was no operating limitation or impact from the substitute calculations. Other capabilities exist in 3D Monicore to align TIPs more accurately and accommodate other types of system measurements or anomalies. 3D Monicore also includes an accurate predictive capability which uses the adaptive results from previous monitoring calculations and is used to plan and optimize reactor maneuvers/operations to improve operating efficiency and reduce support requirements
Micromagnetic modeling of critical current oscillations in magnetic Josephson junctions
golovchanskiy, I.A.; Bol'ginov, V.V.; Stolyarov, V.S.; Abramov, N.N.; Ben Hamida, A.; Emelyanova, O.V.; Stolyarov, B.S.; Kupriyanov, M..Y.; Golubov, Alexandre Avraamovitch; Ryazanov, V.V.
2016-01-01
In this work we propose and explore an effective numerical approach for investigation of critical current dependence on applied magnetic field for magnetic Josephson junctions with in-plane magnetization orientation. This approach is based on micromagnetic simulation of the magnetization reversal
Modeling in the Common Core State Standards
Tam, Kai Chung
2011-01-01
The inclusion of modeling and applications into the mathematics curriculum has proven to be a challenging task over the last fifty years. The Common Core State Standards (CCSS) has made mathematical modeling both one of its Standards for Mathematical Practice and one of its Conceptual Categories. This article discusses the need for mathematical…
A model of magnetic impurities within the Josephson junction of a phase qubit
Energy Technology Data Exchange (ETDEWEB)
Erickson, R P; Pappas, D P [National Institute of Standards and Technology, Boulder, CO 80305 (United States)
2010-02-15
We consider a superconducting phase qubit consisting of a monocrystalline sapphire Josephson junction with its symmetry axis perpendicular to the junction interfaces. Via the London gauge, we present a theoretical model of Fe{sup 3+} magnetic impurities within the junction that describes the effect of a low concentration of such impurities on the operation of the qubit. Specifically, we derive an interaction Hamiltonian expressed in terms of angular momentum states of magnetic impurities and low-lying oscillator states of a current-biased phase qubit. We discuss the coupling between the qubit and impurities within the model near resonance. When the junction is biased at an optimal point for acting as a phase qubit, with a phase difference of {pi}/2 and impurity concentration no greater than 0.05%, we find only a slight decrease in the Q factor of less than 0.01%.
Integrated core-edge-divertor modeling studies
International Nuclear Information System (INIS)
Stacey, W.M.
2001-01-01
An integrated calculation model for simulating the interaction of physics phenomena taking place in the plasma core, in the plasma edge and in the SOL and divertor of tokamaks has been developed and applied to study such interactions. The model synthesises a combination of numerical calculations (1) the power and particle balances for the core plasma, using empirical confinement scaling laws and taking into account radiation losses (2), the particle, momentum and power balances in the SOL and divertor, taking into account the effects of radiation and recycling neutrals, (3) the transport of feeling and recycling neutrals, explicitly representing divertor and pumping geometry, and (4) edge pedestal gradient scale lengths and widths, evaluation of theoretical predictions (5) confinement degradation due to thermal instabilities in the edge pedestals, (6) detachment and divertor MARFE onset, (7) core MARFE onsets leading to a H-L transition, and (8) radiative collapse leading to a disruption and evaluation of empirical fits (9) power thresholds for the L-H and H-L transitions and (10) the width of the edge pedestals. The various components of the calculation model are coupled and must be iterated to a self-consistent convergence. The model was developed over several years for the purpose of interpreting various edge phenomena observed in DIII-D experiments and thereby, to some extent, has been benchmarked against experiment. Because the model treats the interactions of various phenomena in the core, edge and divertor, yet is computationally efficient, it lends itself to the investigation of the effects of different choices of various edge plasma operating conditions on overall divertor and core plasma performance. Studies of the effect of feeling location and rate, divertor geometry, plasma shape, pumping and over 'edge parameters' on core plasma properties (line average density, confinement, density limit, etc.) have been performed for DIII-D model problems. A
Geodynamo Modeling of Core-Mantle Interactions
Kuang, Wei-Jia; Chao, Benjamin F.; Smith, David E. (Technical Monitor)
2001-01-01
Angular momentum exchange between the Earth's mantle and core influences the Earth's rotation on time scales of decades and longer, in particular in the length of day (LOD) which have been measured with progressively increasing accuracy for the last two centuries. There are four possible coupling mechanisms for transferring the axial angular momentum across the core-mantle boundary (CMB): viscous, magnetic, topography, and gravitational torques. Here we use our scalable, modularized, fully dynamic geodynamo model for the core to assess the importance of these torques. This numerical model, as an extension of the Kuang-Bloxham model that has successfully simulated the generation of the Earth's magnetic field, is used to obtain numerical results in various physical conditions in terms of specific parameterization consistent with the dynamical processes in the fluid outer core. The results show that depending on the electrical conductivity of the lower mantle and the amplitude of the boundary topography at CMB, both magnetic and topographic couplings can contribute significantly to the angular momentum exchange. This implies that the core-mantle interactions are far more complex than has been assumed and that there is unlikely a single dominant coupling mechanism for the observed decadal LOD variation.
Modeling and simulation of a dual-junction CIGS solar cell using Silvaco ATLAS
Fotis, Konstantinos
2012-01-01
Approved for public release; distribution is unlimited. The potential of designing a dual-junction Copper Indium Gallium Selenide (CIGS) photovoltaic cell is investigated in this thesis. Research into implementing a dual-junction solar cell, using a CIGS bottom cell and different thin-film designs as a top cell, was conducted in order to increase the current record efficiency of 20.3% for a single CIGS cell. This was accomplished through modeling and simulation using Silvaco ATLASTM, an ad...
A PC microsimulation of a gap acceptance model for turning left at a T-junction
Schaap, Nina; Dijck, T.; van Arem, Bart; Morsink, Peter L.J.
2009-01-01
Vehicles are controlled by sub-behavioral models in a microsimulation model, this includes the gap acceptance model where the decision about how to cross a junction is made. The critical gap in these models must serve as a threshold value to accept or reject the space between two successive vehicles
Enhanced Core Noise Modeling for Turbofan Engines
Stone, James R.; Krejsa, Eugene A.; Clark, Bruce J.
2011-01-01
This report describes work performed by MTC Technologies (MTCT) for NASA Glenn Research Center (GRC) under Contract NAS3-00178, Task Order No. 15. MTCT previously developed a first-generation empirical model that correlates the core/combustion noise of four GE engines, the CF6, CF34, CFM56, and GE90 for General Electric (GE) under Contract No. 200-1X-14W53048, in support of GRC Contract NAS3-01135. MTCT has demonstrated in earlier noise modeling efforts that the improvement of predictive modeling is greatly enhanced by an iterative approach, so in support of NASA's Quiet Aircraft Technology Project, GRC sponsored this effort to improve the model. Since the noise data available for correlation are total engine noise spectra, it is total engine noise that must be predicted. Since the scope of this effort was not sufficient to explore fan and turbine noise, the most meaningful comparisons must be restricted to frequencies below the blade passage frequency. Below the blade passage frequency and at relatively high power settings jet noise is expected to be the dominant source, and comparisons are shown that demonstrate the accuracy of the jet noise model recently developed by MTCT for NASA under Contract NAS3-00178, Task Order No. 10. At lower power settings the core noise became most apparent, and these data corrected for the contribution of jet noise were then used to establish the characteristics of core noise. There is clearly more than one spectral range where core noise is evident, so the spectral approach developed by von Glahn and Krejsa in 1982 wherein four spectral regions overlap, was used in the GE effort. Further analysis indicates that the two higher frequency components, which are often somewhat masked by turbomachinery noise, can be treated as one component, and it is on that basis that the current model is formulated. The frequency scaling relationships are improved and are now based on combustor and core nozzle geometries. In conjunction with the Task
Modeling Radiation Effects on a Triple Junction Solar Cell using Silvaco ATLAS
Schiavo, Daniel
2012-01-01
In this research, Silvaco ATLAS, an advanced virtual wafer fabrication tool, was used to model the effects of radiation on a triple junction InGaP/GaAs/Ge solar cell. A Silvaco ATLAS model of a triple junction InGaP/GaAs/Ge cell was created by first creating individual models for solar cells composed of each material. Realistic doping levels were used and thicknesses were varied to produce the design parameters and create reasonably efficient solar cell models for testing. After the individua...
Preliminary model for core/concrete interactions
International Nuclear Information System (INIS)
Murfin, W.B.
1977-08-01
A preliminary model is described for computing the rate of penetration of concrete by a molten LWR core. Among the phenomena included are convective stirring of the melt by evolved gases, admixture of concrete decomposition products to the melt, chemical reactions, radiative heat loss, and variation of heat transfer coefficients with local pressure. The model is most applicable to a two-phase melt (metallic plus oxidic) having a fairly high metallic content
Nuclear clustering - a cluster core model study
International Nuclear Information System (INIS)
Paul Selvi, G.; Nandhini, N.; Balasubramaniam, M.
2015-01-01
Nuclear clustering, similar to other clustering phenomenon in nature is a much warranted study, since it would help us in understanding the nature of binding of the nucleons inside the nucleus, closed shell behaviour when the system is highly deformed, dynamics and structure at extremes. Several models account for the clustering phenomenon of nuclei. We present in this work, a cluster core model study of nuclear clustering in light mass nuclei
CHARACTERIZING AND MODELING FERRITE-CORE PROBES
International Nuclear Information System (INIS)
Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.; Aldrin, John C.
2010-01-01
In this paper, we accurately and carefully characterize a ferrite-core probe that is widely used for aircraft inspections. The characterization starts with the development of a model that can be executed using the proprietary volume-integral code, VIC-3D(c), and then the model is fitted to measured multifrequency impedance data taken with the probe in freespace and over samples of a titanium alloy and aluminum. Excellent results are achieved, and will be discussed.
Modelling characteristics of ferromagnetic cores with the influence of temperature
International Nuclear Information System (INIS)
Górecki, K; Rogalska, M; Zarȩbski, J; Detka, K
2014-01-01
The paper is devoted to modelling characteristics of ferromagnetic cores with the use of SPICE software. Some disadvantages of the selected literature models of such cores are discussed. A modified model of ferromagnetic cores taking into account the influence of temperature on the magnetizing characteristics and the core losses is proposed. The form of the elaborated model is presented and discussed. The correctness of this model is verified by comparing the calculated and the measured characteristics of the selected ferromagnetic cores.
Modeling impurity-assisted chain creation in noble-metal break junctions
International Nuclear Information System (INIS)
Di Napoli, S; Thiess, A; Blügel, S; Mokrousov, Y
2012-01-01
In this work we present the generalization of the model for chain formation in break junctions, introduced by Thiess et al (2008 Nano Lett. 8 2144), to zigzag transition-metal chains with s and p impurities. We apply this extended model to study the producibility trends for noble-metal chains with impurities, often present in break junction experiments, namely, Cu, Ag and Au chains with H, C, O and N adatoms. Providing the material-specific parameters for our model from systematic full-potential linearized augmented plane-wave first-principles calculations, we find that the presence of such impurities crucially affects the binding properties of the noble-metal chains. We reveal that both the impurity-induced bond strengthening and the formation of zigzag bonds can lead to a significantly enhanced probability for chain formation in break junctions. (paper)
Conceptual Models Core to Good Design
Johnson, Jeff
2011-01-01
People make use of software applications in their activities, applying them as tools in carrying out tasks. That this use should be good for people--easy, effective, efficient, and enjoyable--is a principal goal of design. In this book, we present the notion of Conceptual Models, and argue that Conceptual Models are core to achieving good design. From years of helping companies create software applications, we have come to believe that building applications without Conceptual Models is just asking for designs that will be confusing and difficult to learn, remember, and use. We show how Concept
The 0 and pi contact array model of bicrystal junctions and interferometers
DEFF Research Database (Denmark)
Kornev, Victor K.; Soloviev, Igor I.; Klenov, Nikolai V.
2003-01-01
The array model of the faceted bicrystal Josephson junctions has been developed more comprehensively. The facet size and the facet critical current dependence on. magnetic field are taken in to consideration. The model can be successfully used with high-performance software meant for numerical si...
Critical Josephson current in a model Pb/YBa2Cu3O7-δ junction
International Nuclear Information System (INIS)
Atkinson, W.A.; Carbotte, J.P.
1995-01-01
We consider a simple model for a c-axis Pb/YBa 2 Cu 3 O 7-δ Josephson junction. The observation of a nonzero current in such a junction by Sun et al. [Phys. Rev. Lett. 72, 2267 (1994)] has been taken as evidence against d-wave superconductivity in YBa 2 Cu 3 O 7-δ . We suggest, however, that the pairing interaction in the CuO 2 planes may well be d wave but that the CuO chains destroy the tetragonal symmetry of the system. We examine two ways in which this happens. In a simple model of an incoherent junction, the chains distort the superconducting condensate away from d x 2 -y 2 symmetry. In a specular junction the chains destroy the tetragonal symmetry of the tunneling matrix element. In either case, the loss of tetragonal symmetry results in a finite Josephson current. Our calculated values of the critical current for specular junctions are in good agreement with the results of Sun and co-workers
Modified pressure loss model for T-junctions of engine exhaust manifold
Wang, Wenhui; Lu, Xiaolu; Cui, Yi; Deng, Kangyao
2014-11-01
The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.
Conceptual core model for the reactor core test
International Nuclear Information System (INIS)
Swenson, L.D.
1970-01-01
Several design options for the ZrH Flight System Reactor were investigated which involved tradeoffs of core excess reactivity, reactor control, coolant mixing and cladding thickness. A design point was selected which is to be the basis for more detailed evaluation in the preliminary design phase. The selected design utilizes 295 elements with 0.670 inch element-to-element pitch, 32 mil thick Incoloy cladding, 18.00 inches long fuel meat, hydrogen content of 6.3 x 10 22 atoms/cc fuel, 10.5 w/o uranium, and a spiraled fin configuration with alternate elements having fins with spiral to the right, spiral to the left, and no fin at all (R-L-N fin configuration). Fin height is 30 mils for the center region of the core and 15 mils for the outer region. (U.S.)
CFD modeling of thermal mixing in a T-junction geometry using LES model
Energy Technology Data Exchange (ETDEWEB)
Ayhan, Hueseyin, E-mail: huseyinayhan@hacettepe.edu.tr [Hacettepe University, Department of Nuclear Engineering, Beytepe, Ankara 06800 (Turkey); Soekmen, Cemal Niyazi, E-mail: cemalniyazi.sokmen@hacettepe.edu.tr [Hacettepe University, Department of Nuclear Engineering, Beytepe, Ankara 06800 (Turkey)
2012-12-15
Highlights: Black-Right-Pointing-Pointer CFD simulations of temperature and velocity fluctuations for thermal mixing cases in T-junction are performed. Black-Right-Pointing-Pointer It is found that the frequency range of 2-5 Hz contains most of the energy; therefore, may cause thermal fatigue. Black-Right-Pointing-Pointer This study shows that RANS based calculations fail to predict a realistic mixing between the fluids. Black-Right-Pointing-Pointer LES model can predict instantaneous turbulence behavior. - Abstract: Turbulent mixing of fluids at different temperatures can lead to temperature fluctuations at the pipe material. These fluctuations, or thermal striping, inducing cyclical thermal stresses and resulting thermal fatigue, may cause unexpected failure of pipe material. Therefore, an accurate characterization of temperature fluctuations is important in order to estimate the lifetime of pipe material. Thermal fatigue of the coolant circuits of nuclear power plants is one of the major issues in nuclear safety. To investigate thermal fatigue damage, the OECD/NEA has recently organized a blind benchmark study including some of results of present work for prediction of temperature and velocity fluctuations performing a thermal mixing experiment in a T-junction. This paper aims to estimate the frequency of velocity and temperature fluctuations in the mixing region using Computational Fluid Dynamics (CFD). Reynolds Averaged Navier-Stokes and Large Eddy Simulation (LES) models were used to simulate turbulence. CFD results were compared with the available experimental results. Predicted LES results, even in coarse mesh, were found to be in well-agreement with the experimental results in terms of amplitude and frequency of temperature and velocity fluctuations. Analysis of the temperature fluctuations and the power spectrum densities (PSD) at the locations having the strongest temperature fluctuations in the tee junction shows that the frequency range of 2-5 Hz
Modeling of 4H—SiC multi-floating-junction Schottky barrier diode
International Nuclear Information System (INIS)
Hong-Bin, Pu; Lin, Cao; Zhi-Ming, Chen; Jie, Ren; Ya-Gong, Nan
2010-01-01
This paper develops a new and easy to implement analytical model for the specific on-resistance and electric field distribution along the critical path for 4H—SiC multi-floating junction Schottky barrier diode. Considering the charge compensation effects by the multilayer of buried opposite doped regions, it improves the breakdown voltage a lot in comparison with conventional one with the same on-resistance. The forward resistance of the floating junction Schottky barrier diode consists of several components and the electric field can be understood with superposition concept, both are consistent with MEDICI simulation results. Moreover, device parameters are optimized and the analyses show that in comparison with one layer floating junction, multilayer of floating junction layer is an effective way to increase the device performance when specific resistance and the breakdown voltage are traded off. The results show that the specific resistance increases 3.2 mΩ·cm 2 and breakdown voltage increases 422 V with an additional floating junction for the given structure. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Modeling and Design of Graphene GaAs Junction Solar Cell
Directory of Open Access Journals (Sweden)
Yawei Kuang
2015-01-01
Full Text Available Graphene based GaAs junction solar cell is modeled and investigated by Silvaco TCAD tools. The photovoltaic behaviors have been investigated considering structure and process parameters such as substrate thickness, dependence between graphene work function and transmittance, and n-type doping concentration in GaAs. The results show that the most effective region for photo photogenerated carriers locates very close to the interface under light illumination. Comprehensive technological design for junction yields a significant improvement of power conversion efficiency from 0.772% to 2.218%. These results are in good agreement with the reported experimental work.
Detection of the cemento-enamel junction with three different probes: an "in vitro" model
Barendregt, D.S.; van der Velden, U.; Timmerman, M.F.; Bulthuis, H.M.; van der Weijden, G.A.
2008-01-01
Aim: The purpose of the present study was to test the accuracy and precision with which the cemento-enamel junction (CEJ) can be assessed using three commercially available periodontal probes with different tip endings in both deciduous and permanent teeth. Material and Methods: An "in vitro" model
Vector spin modeling for magnetic tunnel junctions with voltage dependent effects
International Nuclear Information System (INIS)
Manipatruni, Sasikanth; Nikonov, Dmitri E.; Young, Ian A.
2014-01-01
Integration and co-design of CMOS and spin transfer devices requires accurate vector spin conduction modeling of magnetic tunnel junction (MTJ) devices. A physically realistic model of the MTJ should comprehend the spin torque dynamics of nanomagnet interacting with an injected vector spin current and the voltage dependent spin torque. Vector spin modeling allows for calculation of 3 component spin currents and potentials along with the charge currents/potentials in non-collinear magnetic systems. Here, we show 4-component vector spin conduction modeling of magnetic tunnel junction devices coupled with spin transfer torque in the nanomagnet. Nanomagnet dynamics, voltage dependent spin transport, and thermal noise are comprehended in a self-consistent fashion. We show comparison of the model with experimental magnetoresistance (MR) of MTJs and voltage degradation of MR with voltage. Proposed model enables MTJ circuit design that comprehends voltage dependent spin torque effects, switching error rates, spin degradation, and back hopping effects
Testing the HTA core model: experiences from two pilot projects
DEFF Research Database (Denmark)
Pasternack, Iris; Anttila, Heidi; Mäkelä, Marjukka
2009-01-01
OBJECTIVES: The aim of this study was to analyze and describe process and outcomes of two pilot assessments based on the HTA Core Model, discuss the applicability of the model, and explore areas of development. METHODS: Data were gathered from HTA Core Model and pilot Core HTA documents, their va...
A Dynamic Traffic Signal Timing Model and its Algorithm for Junction of Urban Road
DEFF Research Database (Denmark)
Cai, Yanguang; Cai, Hao
2012-01-01
As an important part of Intelligent Transportation System, the scientific traffic signal timing of junction can improve the efficiency of urban transport. This paper presents a novel dynamic traffic signal timing model. According to the characteristics of the model, hybrid chaotic quantum...... evolutionary algorithm is employed to solve it. The proposed model has simple structure, and only requires traffic inflow speed and outflow speed are bounded functions with at most finite number of discontinuity points. The condition is very loose and better meets the requirements of the practical real......-time and dynamic signal control of junction. To obtain the optimal solution of the model by hybrid chaotic quantum evolutionary algorithm, the model is converted to an easily solvable form. To simplify calculation, we give the expression of the partial derivative and change rate of the objective function...
Development of a model for Retran-3D for pressure losses at T-junctions
International Nuclear Information System (INIS)
Barten, W.; Coddington, P.; Sullivan, J.
2001-01-01
For Nuclear Power Plants, both for PWRs and BWRs, there are many instances in normal operation, accidents and transients when it is important to know the pressure drop and quality of the flow, at a flow junction. In this paper two-phase pressure drops in a horizontal T-junction with equal areas are assessed in the case of separating flow using the RETRAN-3D code. Therefore applying the RETRAN-3D code first recoverable pressure drops are calculated for different flow rate ratios, inlet qualities and system pressures for steam-water mixtures. These pressure drops are then compared to analytical expressions by Soliman and Ebadian (1994) developed from the analysis of a wide range of two-phase experimental pressure drop data for equal-sided junctions with horizontal inlet and side branches both for steam-water and air-water flow. With these comparisons the experimental pressure loss is separated into a recoverable part (i.e. that calculated by RETRAN-3D) and an irrecoverable. A model for the irrecoverable pressure losses is derived for the RETRAN-3D code by comparing the RETRAN-3D total momentum equation with the expressions generally used for pressure changes at T-junctions. The results of this model are compared to the experimental data through the expressions of Soliman and Ebadian and are shown to produce very good comparisons particularly for the range of conditions consistent with the experimental data. (author)
Development of a model for Retran-3D for pressure losses at T-junctions
Energy Technology Data Exchange (ETDEWEB)
Barten, W.; Coddington, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Sullivan, J. [Penn State University, Nuclear Engineering Program (United States)
2001-07-01
For Nuclear Power Plants, both for PWRs and BWRs, there are many instances in normal operation, accidents and transients when it is important to know the pressure drop and quality of the flow, at a flow junction. In this paper two-phase pressure drops in a horizontal T-junction with equal areas are assessed in the case of separating flow using the RETRAN-3D code. Therefore applying the RETRAN-3D code first recoverable pressure drops are calculated for different flow rate ratios, inlet qualities and system pressures for steam-water mixtures. These pressure drops are then compared to analytical expressions by Soliman and Ebadian (1994) developed from the analysis of a wide range of two-phase experimental pressure drop data for equal-sided junctions with horizontal inlet and side branches both for steam-water and air-water flow. With these comparisons the experimental pressure loss is separated into a recoverable part (i.e. that calculated by RETRAN-3D) and an irrecoverable. A model for the irrecoverable pressure losses is derived for the RETRAN-3D code by comparing the RETRAN-3D total momentum equation with the expressions generally used for pressure changes at T-junctions. The results of this model are compared to the experimental data through the expressions of Soliman and Ebadian and are shown to produce very good comparisons particularly for the range of conditions consistent with the experimental data. (author)
Modelling of thermohydraulic emergency core cooling phenomena
International Nuclear Information System (INIS)
Yadigaroglu, G.; Andreani, M.; Lewis, M.J.
1990-10-01
The codes used in the early seventies for safety analysis and licensing were based either on the homogeneous model of two-phase flow or on the so-called separate-flow models, which are mixture models accounting, however, for the difference in average velocity between the two phases. In both cases the behavior of the mixture is prescribed a priori as a function of local parameters such as the mass flux and the quality. The modern best-estimate codes used for analyzing LWR LOCA's and transients are often based on a two-fluid or 6-equation formulation of the conservation equations. In this case the conservation equations are written separately for each phase; the mixture is allowed to evolve on its own, governed by the interfacial exchanges of mass, momentum and energy between the phases. It is generally agreed that such relatively sophisticated 6-equation formulations of two-phase flow are necessary for the correct modelling of a number of phenomena and situations arising in LWR accidental situations. They are in particular indispensible for the analysis of stratified or countercurrent flows and of situations in which large departures from thermal and velocity equilibrium exist. This report will be devoted to a discussion of the need for, the capacity and the limitations of the two-phase flow models (with emphasis on the 6-equation formulations) in modelling these two-phase flow and heat transfer phenomena and/or different core cooling situations. 18 figs., 1 tab., 72 refs
Improvement of core degradation model in ISAAC
International Nuclear Information System (INIS)
Kim, Dong Ha; Kim, See Darl; Park, Soo Yong
2004-02-01
If water inventory in the fuel channels depletes and fuel rods are exposed to steam after uncover in the pressure tube, the decay heat generated from fuel rods is transferred to the pressure tube and to the calandria tube by radiation, and finally to the moderator in the calandria tank by conduction. During this process, the cladding will be heated first and ballooned when the fuel gap internal pressure exceeds the primary system pressure. The pressure tube will be also ballooned and will touch the calandria tube, increasing heat transfer rate to the moderator. Although these situation is not desirable, the fuel channel is expected to maintain its integrity as long as the calandria tube is submerged in the moderator, because the decay heat could be removed to the moderator through radiation and conduction. Therefore, loss of coolant and moderator inside and outside the channel may cause severe core damage including horizontal fuel channel sagging and finally loss of channel integrity. The sagged channels contact with the channels located below and lose their heat transfer area to the moderator. As the accident goes further, the disintegrated fuel channels will be heated up and relocated onto the bottom of the calandria tank. If the temperature of these relocated materials is high enough to attack the calandria tank, the calandria tank would fail and molten material would contact with the calandria vault water. Steam explosion and/or rapid steam generation from this interaction may threaten containment integrity. Though a detailed model is required to simulate the severe accident at CANDU plants, complexity of phenomena itself and inner structures as well as lack of experimental data forces to choose a simple but reasonable model as the first step. ISAAC 1.0 was developed to model the basic physicochemical phenomena during the severe accident progression. At present, ISAAC 2.0 is being developed for accident management guide development and strategy evaluation. In
No-Core Shell Model and Reactions
International Nuclear Information System (INIS)
Navratil, P; Ormand, W E; Caurier, E; Bertulani, C
2005-01-01
There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) can predict low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. In this contribution, we present a brief overview of the NCSM with examples of recent applications as well as the first steps taken toward nuclear reaction applications. In particular, we discuss cross section calculations of p+ 6 Li and 6 He+p scattering as well as a calculation of the astrophysically important 7 Be(p, γ) 8 B S-factor
Physical model of the contact resistivity of metal-graphene junctions
International Nuclear Information System (INIS)
Chaves, Ferney A.; Jiménez, David; Cummings, Aron W.; Roche, Stephan
2014-01-01
While graphene-based technology shows great promise for a variety of electronic applications, including radio-frequency devices, the resistance of the metal-graphene contact is a technological bottleneck for the realization of viable graphene electronics. One of the most important factors in determining the resistance of a metal-graphene junction is the contact resistivity. Despite the large number of experimental works that exist in the literature measuring the contact resistivity, a simple model of it is still lacking. In this paper, we present a comprehensive physical model for the contact resistivity of these junctions, based on the Bardeen Transfer Hamiltonian method. This model unveils the role played by different electrical and physical parameters in determining the specific contact resistivity, such as the chemical potential of interaction, the work metal-graphene function difference, and the insulator thickness between the metal and graphene. In addition, our model reveals that the contact resistivity is strongly dependent on the bias voltage across the metal-graphene junction. This model is applicable to a wide variety of graphene-based electronic devices and thus is useful for understanding how to optimize the contact resistance in these systems
Physical model of the contact resistivity of metal-graphene junctions
Energy Technology Data Exchange (ETDEWEB)
Chaves, Ferney A., E-mail: ferneyalveiro.chaves@uab.cat; Jiménez, David [Departament d' Enginyeria Electrònica, Escola d' Enginyeria, Universitat Autònoma de Barcelona, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Cummings, Aron W. [ICN2–Institut Català de Nanociència i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Roche, Stephan [ICN2–Institut Català de Nanociència i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain); ICREA, Institució Catalana de Recerca i Estudis Avançats, 08070 Barcelona (Spain)
2014-04-28
While graphene-based technology shows great promise for a variety of electronic applications, including radio-frequency devices, the resistance of the metal-graphene contact is a technological bottleneck for the realization of viable graphene electronics. One of the most important factors in determining the resistance of a metal-graphene junction is the contact resistivity. Despite the large number of experimental works that exist in the literature measuring the contact resistivity, a simple model of it is still lacking. In this paper, we present a comprehensive physical model for the contact resistivity of these junctions, based on the Bardeen Transfer Hamiltonian method. This model unveils the role played by different electrical and physical parameters in determining the specific contact resistivity, such as the chemical potential of interaction, the work metal-graphene function difference, and the insulator thickness between the metal and graphene. In addition, our model reveals that the contact resistivity is strongly dependent on the bias voltage across the metal-graphene junction. This model is applicable to a wide variety of graphene-based electronic devices and thus is useful for understanding how to optimize the contact resistance in these systems.
Directory of Open Access Journals (Sweden)
Fabio Di Napoli
2017-02-01
Full Text Available Residual lifetime estimation has gained a key point among the techniques that improve the reliability and the efficiency of power converters. The main cause of failures are the junction temperature cycles exhibited by switching devices during their normal operation; therefore, reliable power converter lifetime estimation requires the knowledge of the junction temperature time profile. Since on-line dynamic temperature measurements are extremely difficult, in this work an innovative real-time monitoring strategy is proposed, which is capable of estimating the junction temperature profile from the measurement of the dissipated powers through an accurate and compact thermal model of the whole power module. The equations of this model can be easily implemented inside a FPGA, exploiting the control architecture already present in modern power converters. Experimental results on an IGBT power module demonstrate the reliability of the proposed method.
Glawdel, Tomasz; Elbuken, Caglar; Ren, Carolyn L
2012-01-01
This is the second part of a two-part study on the generation of droplets at a microfluidic T-junction operating in the transition regime. In the preceding paper [Phys. Rev. E 85, 016322 (2012)], we presented our experimental observations of droplet formation and decomposed the process into three sequential stages defined as the lag, filling, and necking stages. Here we develop a model that describes the performance of microfluidic T-junction generators working in the squeezing to transition regimes where confinement of the droplet dominates the formation process. The model incorporates a detailed geometric description of the drop shape during the formation process combined with a force balance and necking criteria to define the droplet size, production rate, and spacing. The model inherently captures the influence of the intersection geometry, including the channel width ratio and height-to-width ratio, capillary number, and flow ratio, on the performance of the generator. The model is validated by comparing it to speed videos of the formation process for several T-junction geometries across a range of capillary numbers and viscosity ratios.
Darmawan, R.
2018-01-01
Nuclear power industry is facing uncertainties since the occurrence of the unfortunate accident at Fukushima Daiichi Nuclear Power Plant. The issue of nuclear power plant safety becomes the major hindrance in the planning of nuclear power program for new build countries. Thus, the understanding of the behaviour of reactor system is very important to ensure the continuous development and improvement on reactor safety. Throughout the development of nuclear reactor technology, investigation and analysis on reactor safety have gone through several phases. In the early days, analytical and experimental methods were employed. For the last four decades 1D system level codes were widely used. The continuous development of nuclear reactor technology has brought about more complex system and processes of nuclear reactor operation. More detailed dimensional simulation codes are needed to assess these new reactors. Recently, 2D and 3D system level codes such as CFD are being explored. This paper discusses a comparative study on two different approaches of CFD modelling on reactor core cooling behaviour.
Gaussian tunneling model of c-axis twist Josephson junctions
International Nuclear Information System (INIS)
Bille, A.; Klemm, R.A.; Scharnberg, K.
2001-01-01
We calculate the critical current density J c J ((var p hi) 0 ) for Josephson tunneling between identical high-temperature superconductors twisted an angle (var p hi) 0 about the c axis. Regardless of the shape of the two-dimensional Fermi surface and for very general tunneling matrix elements, an order parameter (OP) with general d-wave symmetry leads to J c J (π/4)=0. This general result is inconsistent with the data of Li et al. [Phys. Rev. Lett. 83, 4160 (1999)] on Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212), which showed J c J to be independent of (var p hi) 0 . If the momentum parallel to the barrier is conserved in the tunneling process, J c J should vary substantially with the twist angle (var p hi) 0 when the tight-binding Fermi surface appropriate for Bi2212 is taken into account, even if the OP is completely isotropic. We quantify the degree of momentum nonconservation necessary to render J c J ((var p hi) 0 ) constant within experimental error for a variety of pair states by interpolating between the coherent and incoherent limits using five specific models to describe the momentum dependence of the tunneling matrix element squared. From the data of Li et al., we conclude that the c-axis tunneling in Bi2212 must be very nearly incoherent, and that the OP must have a nonvanishing Fermi-surface average for T c . We further show that the apparent conventional sum-rule violation observed by Basov et al. [Science 283, 49 (1999)] can be consistent with such strongly incoherent c-axis tunneling.
International Nuclear Information System (INIS)
McAdory, R.T. Jr.
1988-01-01
A theory is presented for the nonequilibrium voltage states of an irradiated Josephson junction shunted by an external resistor but with no external current or voltage biasing. This device, referred to as a free-running Josephson junction, is modeled in a small--radiation-amplitude, deterministic regime extending the previous work of Shenoy and Agarwal. The time-averaged induced voltage is treated as a dynamical variable, the external radiation is modeled as a current source, and the induced junction-radiation vector potential, with and without a mode structure, is treated to first order in the driving currents. A dynamical equation for the time-averaged induced voltage yields a (nonequilibrium) steady-state relation between the time-averaged induced voltage and the incident radiation amplitude valid for a wide range of voltages, including zero. Regions of bistability occur in the voltage--versus--incident-amplitude curves, some of which are dependent on the external resistor. The zero-voltage state breaks down, as the external radiation amplitude is increased, at a critical value of the incident-radiation amplitude inversely proportional to the external resistance
An improved bipolar junction transistor model for electrical and radiation effects
International Nuclear Information System (INIS)
Kleiner, C.T.; Messenger, G.C.
1982-01-01
The use of bipolar technology in hardened electronic design requires an in-depth understanding of how the Bipolar Junction Transistor (BJT) behaves under normal electrical and radiation environments. Significant improvements in BJT process technology have been reported, and the successful use of sophisticated Computer Aided Design (CAD) tools has aided implementation with respect to specific families of hardened devices. The most advanced BJT model used to date is the Improved Gummel-Poon (IGP) model which is used in CAA programs such as the SPICE II and SLICE programs. The earlier Ebers-Moll model (ref 1 and 2) has also been updated to compare with the older Gummel-Poon model. This paper describes an adaptation of an existing computer model which incorporates the best features of both models into a new, more accurate model called the Improved Bipolar Junction Transistor model. This paper also describes a unique approach to data reduction for the B(I /SUB c/) and V /SUB BE/(ACT) vs I /SUB c/characterizations which has been successfully programmed in Basic using a Commodore PET computer. This model is described in the following sections
Thermal hydraulic model validation for HOR mixed core fuel management
International Nuclear Information System (INIS)
Gibcus, H.P.M.; Vries, J.W. de; Leege, P.F.A. de
1997-01-01
A thermal-hydraulic core management model has been developed for the Hoger Onderwijsreactor (HOR), a 2 MW pool-type university research reactor. The model was adopted for safety analysis purposes in the framework of HEU/LEU core conversion studies. It is applied in the thermal-hydraulic computer code SHORT (Steady-state HOR Thermal-hydraulics) which is presently in use in designing core configurations and for in-core fuel management. An elaborate measurement program was performed for establishing the core hydraulic characteristics for a variety of conditions. The hydraulic data were obtained with a dummy fuel element with special equipment allowing a.o. direct measurement of the true core flow rate. Using these data the thermal-hydraulic model was validated experimentally. The model, experimental tests, and model validation are discussed. (author)
Construction and utilization of linear empirical core models for PWR in-core fuel management
International Nuclear Information System (INIS)
Okafor, K.C.
1988-01-01
An empirical core-model construction procedure for pressurized water reactor (PWR) in-core fuel management is developed that allows determining the optimal BOC k ∞ profiles in PWRs as a single linear-programming problem and thus facilitates the overall optimization process for in-core fuel management due to algorithmic simplification and reduction in computation time. The optimal profile is defined as one that maximizes cycle burnup. The model construction scheme treats the fuel-assembly power fractions, burnup, and leakage as state variables and BOC zone enrichments as control variables. The core model consists of linear correlations between the state and control variables that describe fuel-assembly behavior in time and space. These correlations are obtained through time-dependent two-dimensional core simulations. The core model incorporates the effects of composition changes in all the enrichment control zones on a given fuel assembly and is valid at all times during the cycle for a given range of control variables. No assumption is made on the geometry of the control zones. A scatter-composition distribution, as well as annular, can be considered for model construction. The application of the methodology to a typical PWR core indicates good agreement between the model and exact simulation results
Louie, Richard Nam
2002-12-01
Aircraft fuselages suffer alternating stress during takeoffs and landings, and fatigue cracks begin to grow, usually at rivet holes. The detection of these fatigue cracks under installed fasteners in aging aircraft is a major goal of the nondestructive evaluation (NDE) community. The use of giant magnetoresistance (GMR) sensors in electromagnetic (EM) NDE has been increasing rapidly. For example, here at Langley Research Center, a Rotating Probe System (RPS) containing a GMR element has been incorporated into a product to detect deeply buried flaws in aerospace structures. In order to advance this eddy current probe application and many similar ones, research to create smaller, more sensitive and energy-efficient EM sensors has been aggressively pursued. Recent theoretical and experimental work on spin coherent transport supports the feasibility of carbon nanotube (CNT) based magnetic tunnel junctions. In this study, a spatial filtering scheme is presented that improves the signal to noise ratio of the RPS and does not significantly impact the number of false alarms. Signals due to buried flaws occur at higher frequencies than do signals due to rivet tilt or probe misalignment, and the strategy purposefully targets this fact. Furthermore, the spatial filtering scheme exploits decreases in the probe output that are observed immediately preceding and following the peak in output due to a fatigue crack. Using the new filters, an enhanced probability of flaw detection is expected. In the future, even tinier, more sensitive, low-power sensors are envisioned for the rotating probe and other nondestructive inspection systems. These may be comprised of single-walled carbon nanotubes (SWCNTs) that connect two ferromagnetic (FM) electrodes. Theoretical work has been done at Langley to model the electrical and magnetoconductance behavior of such junctions, for systems containing short "armchair" nanotubes. The present work facilitates the modeling of more realistic system
Evidence for a continental unstable triple junction as an alternate model for Vrancea seismicity
International Nuclear Information System (INIS)
Besutiu, L.
2002-01-01
The Vrancea active seismic zone located in the bending area of Romanian Carpathians stands for a long time as a challenge to geoscientists all over the world. Deep seismicity in continental collision circumstances is rather rare and always constraints on dynamics of subduction. The pattern of the intermediate-depth seismicity in the Vrancea region suggests a confined prismatic nearly vertical seismic body. The small size and geometry of the seismic zone have made it difficult to interpret the kinematics of subduction and continental collision in the area. During the years, several models, almost all subduction-related, have more or less successfully tried to explain this phenomenon. The paper represents an attempt to explain the Vrancea intermediate depth seismicity starting from a new concept, as introduced by the plate tectonics theory: the triple junction. A continental unstable triple junction is proposed as an alternate model to explain the unusual seismicity in the Vrancea seismic area. Three tectonic plates / microplates seem to join in the region: East European Plate (EEP), Moesian microplate (MoP), and the Intra-Alpine microplate (IaP). Their edges are geophysically documented and their motion is evidenced. The differentiation in their relative velocities generated an unstable transform-transform-compression triple junction that determined the vertical collapse of the lithospheric segment to which the intermediate seismicity within Vrancea zone is associated. Three major plates' wedges bound the seismic body: Tornquist-Teissyere zone, Peceneaga-Camena fault, and Trans-Getica fault. Temperature accommodation phenomena associated to the sinking lithospheric body into the hotter upper mantle environment (such as convective cells, phase-transform processes, and devolatilization) could be responsible for the earthquakes occurrence. The problem of the missing subduction related volcanism within Vrancea triple junction (VTJ) area is definitely solved in the case
Study of Charge Transport in Vertically Aligned Nitride Nanowire Based Core Shell P-I-N Junctions
2016-07-01
Ci) [activity of radionuclides] 3.7 × 10 10 per second (s –1 ) [becquerel (Bq)] roentgen (R) [air exposure] 2.579 760 × 10 –4 coulomb per kilogram...objectives include: 1) design and simulation of core-shell structures for realistic estimation of performance metrics achievable from such
Thermal margin model for transition core of KSNP
International Nuclear Information System (INIS)
Nahm, Kee Yil; Lim, Jong Seon; Park, Sung Kew; Chun, Chong Kuk; Hwang, Sun Tack
2004-01-01
The PLUS7 fuel was developed with mixing vane grids for KSNP. For the transition core partly loaded with the PLUS7 fuels, the procedure to set up the optimum thermal margin model of the transition core was suggested by introducing AOPM concept into the screening method which determines the limiting assembly. According to the procedure, the optimum thermal margin model of the first transition core was set up by using a part of nuclear data for the first transition and the homogeneous core with PLUS7 fuels. The generic thermal margin model of PLUS7 fuel was generated with the AOPM of 138%. The overpower penalties on the first transition core were calculated to be 1.0 and 0.98 on the limiting assembly and the generic thermal margin model, respectively. It is not usual case to impose the overpower penalty on reload cores. It is considered that the lack of channel flow due to the difference of pressure drop between PLUS7 and STD fuels results in the decrease of DNBR. The AOPM of the first transition core is evaluated to be about 135% by using the optimum generic thermal margin model which involves the generic thermal margin model and the total overpower penalty. The STD fuel is not included among limiting assembly candidates in the second transition core, because they have much lower pin power than PLUS7 fuels. The reduced number of STD fuels near the limiting assembly candidates the flow from the limiting assembly to increase the thermal margin for the second transition core. It is expected that cycle specific overpower penalties increase the thermal margin for the transition core. Using the procedure to set up the optimum thermal margin model makes sure that the enhanced thermal margin of PLUS7 fuel can be sufficiently applied to not only the homogeneous core but also the transition core
Scaling of Core Material in Rubble Mound Breakwater Model Tests
DEFF Research Database (Denmark)
Burcharth, H. F.; Liu, Z.; Troch, P.
1999-01-01
The permeability of the core material influences armour stability, wave run-up and wave overtopping. The main problem related to the scaling of core materials in models is that the hydraulic gradient and the pore velocity are varying in space and time. This makes it impossible to arrive at a fully...... correct scaling. The paper presents an empirical formula for the estimation of the wave induced pressure gradient in the core, based on measurements in models and a prototype. The formula, together with the Forchheimer equation can be used for the estimation of pore velocities in cores. The paper proposes...... that the diameter of the core material in models is chosen in such a way that the Froude scale law holds for a characteristic pore velocity. The characteristic pore velocity is chosen as the average velocity of a most critical area in the core with respect to porous flow. Finally the method is demonstrated...
APROS 3-D core models for simulators and plant analyzers
International Nuclear Information System (INIS)
Puska, E.K.
1999-01-01
The 3-D core models of APROS simulation environment can be used in simulator and plant analyzer applications, as well as in safety analysis. The key feature of APROS models is that the same physical models can be used in all applications. For three-dimensional reactor cores the APROS models cover both quadratic BWR and PWR cores and the hexagonal lattice VVER-type cores. In APROS environment the user can select the number of flow channels in the core and either five- or six-equation thermal hydraulic model for these channels. The thermal hydraulic model and the channel description have a decisive effect on the calculation time of the 3-D core model and thus just these selection make at present the major difference between a safety analysis model and a training simulator model. The paper presents examples of various types of 3-D LWR-type core descriptions for simulator and plant analyzer use and discusses the differences of calculation speed and physical results between a typical safety analysis model description and a real-time simulator model description in transients. (author)
Thermohydraulic model of WWER-1000 core
International Nuclear Information System (INIS)
Maroti, L.; Szabados, L.
1987-11-01
Safe and economic operation of the WWER-1000 type reactor requires more accurate calculation of the thermohydraulic processes than the one satisfactory for the 440 type cores. The high degree of accuracy is needed both for reactor physics calculations and for the determination of the operational safety limits of the core. The paper illustrates the most important differences between the 1000 and 440 type reactors and presents the main fields of the development work necessary to reach the required accuracy. A prediction for the capability of the computer programs after the proposed development is also given and some suggestions for the further improvement is outlined. (author) 7 refs
International Nuclear Information System (INIS)
Lemonnier, H.; Hervieu, E.
1991-01-01
Phase separation in a tee-junction is modelled in the particular case of bubbly-flow. The model is based on a two-dimensional approach and hence, uses local equations. The first step consists in modelling the single-phase flow in the tee-junction. The free streamline theory is used to predict the flow of the continuous phase. The two recirculation zones which are presented in this case are predicted by the model. The second step consists in predicting the gas bubble paths as a result of the actions of the single-phase flow. Finally, the trajectories of gas bubbles are used to predict the separation characteristics of the tee-junction. Each step of the modelling procedure has been carefully tested by an in-depth experimental investigation. Excellent quantitative agreement is obtained between experimental results and model predictions. Moreover, the phase separation phenomenon is found to be clearly described by the model. (orig.)
Effect of film roughness in Fe/MgO/Fe magnetic tunnel junctions: model calculations
Energy Technology Data Exchange (ETDEWEB)
Edalati Boostan, Saeideh; Heiliger, Christian [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany); Moradi, Hosein [Department of Physics,Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)
2011-07-01
We calculate how interface roughness affects the tunneling magnetoresistance (TMR) in Fe/MgO/Fe (100) junctions. The used method is based on a single-band tight-binding (SBTB) approximation employing the Green's function formalism. We investigate the influence of disorder at the TMR ratio. Thereby, the disorder is modeled by considering different occupation probabilities of Fe and MgO at interface sites. We calculate the current densities for parallel and anti-parallel configurations for different disorders. The results show that the roughness decreases the TMR that match well with experimental observations.
Theoretical results on the tandem junction solar cell based on its Ebers-Moll transistor model
Goradia, C.; Vaughn, J.; Baraona, C. R.
1980-01-01
A one-dimensional theoretical model of the tandem junction solar cell (TJC) with base resistivity greater than about 1 ohm-cm and under low level injection has been derived. This model extends a previously published conceptual model which treats the TJC as an npn transistor. The model gives theoretical expressions for each of the Ebers-Moll type currents of the illuminated TJC and allows for the calculation of the spectral response, I(sc), V(oc), FF and eta under variation of one or more of the geometrical and material parameters and 1MeV electron fluence. Results of computer calculations based on this model are presented and discussed. These results indicate that for space applications, both a high beginning of life efficiency, greater than 15% AM0, and a high radiation tolerance can be achieved only with thin (less than 50 microns) TJC's with high base resistivity (greater than 10 ohm-cm).
Fluid dynamic modeling of junctions in internal combustion engine inlet and exhaust systems
Chalet, David; Chesse, Pascal
2010-10-01
The modeling of inlet and exhaust systems of internal combustion engine is very important in order to evaluate the engine performance. This paper presents new pressure losses models which can be included in a one dimensional engine simulation code. In a first part, a CFD analysis is made in order to show the importance of the density in the modeling approach. Then, the CFD code is used, as a numerical test bench, for the pressure losses models development. These coefficients depend on the geometrical characteristics of the junction and an experimental validation is made with the use of a shock tube test bench. All the models are then included in the engine simulation code of the laboratory. The numerical calculation of unsteady compressible flow, in each pipe of the inlet and exhaust systems, is made and the calculated engine torque is compared with experimental measurements.
Lamination effects on a 3D model of the magnetic core of power transformers
Directory of Open Access Journals (Sweden)
Poveda-Lerma Antonio
2017-12-01
Full Text Available In this paper the lamination effect on the model of a power transformer’s core with stacked E-I structure is analyzed. The distribution of the magnetic flux in the laminations depends on the stacking method. In this work it is shown, using a 3D FEM model and an experimental prototype, that the non-uniform distribution of the flux in a laminated E-I core with alternate-lap joint stack increases substantially the average value of the magnetic flux density in the core, compared with a butt joint stack. Both the simulated model and the experimental tests show that the presence of constructive air-gaps in the E-I junctions gives rise to a zig-zag flux in the depth direction. This inter-lamination flux reduces the magnetic flux density in the I-pieces and increases substantially the magnetic flux density in the E-pieces, with highly saturated points that traditional 2D analysis cannot reproduce. The relation between the number of laminations included in the model, and the computational resourses needed to build it, is also evaluated in this work.
Directory of Open Access Journals (Sweden)
Anam Naz
2017-09-01
Full Text Available Tight junctions help prevent the passage of digestive enzymes and microorganisms through the space between adjacent epithelial cells lining. However, Helicobacter pylori encoded virulence factors negatively regulate these tight junctions and contribute to dysfunction of gastric mucosa. Here, we have predicted the regulation of important tight junction proteins, such as Zonula occludens-1, Claudin-2 and Connexin32 in the presence of pathogenic proteins. Molecular events such as post translational modifications and crosstalk between phosphorylation, O-glycosylation, palmitoylation and methylation are explored which may compromise the integrity of these tight junction proteins. Furthermore, the signaling pathways disrupted by dysregulated kinases, proteins and post-translational modifications are reviewed to design an abstracted computational model showing the situation-dependent dynamic behaviors of these biological processes and entities. A qualitative hybrid Petri Net model is therefore constructed showing the altered host pathways in the presence of virulence factor cytotoxin-associated gene A, leading to the disruption of tight junction proteins. The model is qualitative logic-based, which does not depend on any kinetic parameter and quantitative data and depends on knowledge derived from experiments. The designed model provides insights into the tight junction disruption and disease progression. Model is then verified by the available experimental data, nevertheless formal in vitro experimentation is a promising way to ensure its validation. The major findings propose that H. pylori activated kinases are responsible to trigger specific post translational modifications within tight junction proteins, at specific sites. These modifications may favor alterations in gastric barrier and provide a route to bacterial invasion into host cells.
Nonlinear Dynamic Model of PMBLDC Motor Considering Core Losses
DEFF Research Database (Denmark)
Fasil, Muhammed; Mijatovic, Nenad; Jensen, Bogi Bech
2017-01-01
The phase variable model is used commonly when simulating a motor drive system with a three-phase permanent magnet brushless DC (PMBLDC) motor. The phase variable model neglects core losses and this affects its accuracy when modelling fractional-slot machines. The inaccuracy of phase variable mod...... on the detailed analysis of the flux path and the variation of flux in different components of the machine. A prototype of fractional slot axial flux PMBLDC in-wheel motor is used to assess the proposed nonlinear dynamic model....... of fractional-slot machines can be attributed to considerable armature flux harmonics, which causes an increased core loss. This study proposes a nonlinear phase variable model of PMBLDC motor that considers the core losses induced in the stator and the rotor. The core loss model is developed based...
Modification of Core Model for KNTC 2 Simulator
Energy Technology Data Exchange (ETDEWEB)
Lee, Y.K.; Lee, J.G.; Park, J.E.; Bae, S.N.; Chin, H.C. [Korea Electric Power Research Institute, Taejeon (Korea, Republic of)
1997-12-31
KNTC 2 simulator was developed in 1986 referencing YGN 1. Since the YGN 1 has changed its fuel cycle to long term cycle(cycle 9), the data such as rod worth, boron worth, moderator temperature coefficient, and etc. of the simulator and those of the YGN 1 became different. To incorporate these changes into the simulator and make the simulator more close to the reference plant, core model upgrade became a necessity. During this research, core data for the simulator was newly generated using APA of the WH. And to make it easy tuning and verification of the key characteristics of the reactor model, PC-Based tool was also developed. And to facilitate later core model upgrade, two procedures-`the Procedures for core characteristic generation` and `the Procedures for core characteristic modification`-were also developed. (author). 16 refs., 22 figs., 1 tab.
International Nuclear Information System (INIS)
Bindslev Hansen, J.; Lindelof, P.E.
1985-01-01
In this review we intend to cover recent work involving arrays of Josephson junctions. The work on such arrays falls naturally into three main areas of interest: 1. Technical applications of Josephson junction arrays for high-frequency devices. 2. Experimental studies of 2-D model systems (Kosterlitz-Thouless phase transition, commensurate-incommensurate transition in frustrated (flux) lattices). 3. Investigations of phenomena associated with non-equilibrium superconductivity in and around Josephson junctions (with high current density). (orig./BUD)
A novel macro-model for spin-transfer-torque based magnetic-tunnel-junction elements
Lee, Seungyeon; Lee, Hyunjoo; Kim, Sojeong; Lee, Seungjun; Shin, Hyungsoon
2010-04-01
Spin-transfer-torque (STT) switching in magnetic-tunnel-junction (MTJ) has important merits over the conventional field induced magnetic switching (FIMS) MRAM in avoiding half-select problem, and improving scalability and selectivity. Design of MRAM circuitry using STT-based MTJ elements requires an accurate circuit model which exactly emulates the characteristics of an MTJ in a circuit simulator such as HSPICE. This work presents a novel macro-model that fully emulates the important characteristics of STT-based MTJ. The macro-model is realized as a three terminal sub-circuit that reproduces asymmetric resistance versus current (R-I) characteristics and temperature dependence of R-I hysteresis of STT-based MTJ element.
Analytical modeling of split-gate junction-less transistor for a biosensor application
Directory of Open Access Journals (Sweden)
Shradhya Singh
2018-04-01
Full Text Available This paper represents the analytical modeling of split-gate Dielectric Modulated Junction Less Transistor (JLT for label free electrical detection of bio molecules. Some part of the channel region is opened for providing the binding sites for the bio molecules unlike conventional MOSFET which is enclosed with the gate electrode. Due to this open area, the surface potential of this region affected by the charged and neutral bio molecules immobilized to the open region of channel. Surface potential of the channel region obtained by solving two-Dimensional Poisson's equation by potential profile having parabolic nature through channel region using technique called conformal mapping. By deriving the surface potential model, derivation of threshold model can also be done. For the detection of bio molecule, variation in to the threshold voltage due to binding of bio molecule in the gate underlap region is the sensing metric.
Modelling guidelines for core exit temperature simulations with system codes
Energy Technology Data Exchange (ETDEWEB)
Freixa, J., E-mail: jordi.freixa-terradas@upc.edu [Department of Physics and Nuclear Engineering, Technical University of Catalonia (UPC) (Spain); Paul Scherrer Institut (PSI), 5232 Villigen (Switzerland); Martínez-Quiroga, V., E-mail: victor.martinez@nortuen.com [Department of Physics and Nuclear Engineering, Technical University of Catalonia (UPC) (Spain); Zerkak, O., E-mail: omar.zerkak@psi.ch [Paul Scherrer Institut (PSI), 5232 Villigen (Switzerland); Reventós, F., E-mail: francesc.reventos@upc.edu [Department of Physics and Nuclear Engineering, Technical University of Catalonia (UPC) (Spain)
2015-05-15
Highlights: • Core exit temperature is used in PWRs as an indication of core heat up. • Modelling guidelines of CET response with system codes. • Modelling of heat transfer processes in the core and UP regions. - Abstract: Core exit temperature (CET) measurements play an important role in the sequence of actions under accidental conditions in pressurized water reactors (PWR). Given the difficulties in placing measurements in the core region, CET readings are used as criterion for the initiation of accident management (AM) procedures because they can indicate a core heat up scenario. However, the CET responses have some limitation in detecting inadequate core cooling and core uncovery simply because the measurement is not placed inside the core. Therefore, it is of main importance in the field of nuclear safety for PWR power plants to assess the capabilities of system codes for simulating the relation between the CET and the peak cladding temperature (PCT). The work presented in this paper intends to address this open question by making use of experimental work at integral test facilities (ITF) where experiments related to the evolution of the CET and the PCT during transient conditions have been carried out. In particular, simulations of two experiments performed at the ROSA/LSTF and PKL facilities are presented. The two experiments are part of a counterpart exercise between the OECD/NEA ROSA-2 and OECD/NEA PKL-2 projects. The simulations are used to derive guidelines in how to correctly reproduce the CET response during a core heat up scenario. Three aspects have been identified to be of main importance: (1) the need for a 3-dimensional representation of the core and Upper Plenum (UP) regions in order to model the heterogeneity of the power zones and axial areas, (2) the detailed representation of the active and passive heat structures, and (3) the use of simulated thermocouples instead of steam temperatures to represent the CET readings.
Solid charged-core model of ball lightning
Muldrew, D. B.
2010-01-01
In this study, ball lightning (BL) is assumed to have a solid, positively-charged core. According to this underlying assumption, the core is surrounded by a thin electron layer with a charge nearly equal in magnitude to that of the core. A vacuum exists between the core and the electron layer containing an intense electromagnetic (EM) field which is reflected and guided by the electron layer. The microwave EM field applies a ponderomotive force (radiation pressure) to the electrons preventing them from falling into the core. The energetic electrons ionize the air next to the electron layer forming a neutral plasma layer. The electric-field distributions and their associated frequencies in the ball are determined by applying boundary conditions to a differential equation given by Stratton (1941). It is then shown that the electron and plasma layers are sufficiently thick and dense to completely trap and guide the EM field. This model of BL is exceptional in that it can explain all or nearly all of the peculiar characteristics of BL. The ES energy associated with the core charge can be extremely large which can explain the observations that occasionally BL contains enormous energy. The mass of the core prevents the BL from rising like a helium-filled balloon - a problem with most plasma and burning-gas models. The positively charged core keeps the negatively charged electron layer from diffusing away, i.e. it holds the ball together; other models do not have a mechanism to do this. The high electrical charges on the core and in the electron layer explains why some people have been electrocuted by BL. Experiments indicate that BL radiates microwaves upon exploding and this is consistent with the model. The fact that this novel model of BL can explain these and other observations is strong evidence that the model should be taken seriously.
Modelling the core magnetic field of the earth
Harrison, C. G. A.; Carle, H. M.
1982-01-01
It is suggested that radial off-center dipoles located within the core of the earth be used instead of spherical harmonics of the magnetic potential in modeling the core magnetic field. The off-center dipoles, in addition to more realistically modeling the physical current systems within the core, are if located deep within the core more effective at removing long wavelength signals of either potential or field. Their disadvantage is that their positions and strengths are more difficult to compute, and such effects as upward and downward continuation are more difficult to manipulate. It is nevertheless agreed with Cox (1975) and Alldredge and Hurwitz (1964) that physical realism in models is more important than mathematical convenience. A radial dipole model is presented which agrees with observations of secular variation and excursions.
Improvement of Cycle Dependent Core Model for NPP Simulator
International Nuclear Information System (INIS)
Song, J. S.; Koo, B. S.; Kim, H. Y. and others
2003-11-01
The purpose of this study is to establish automatic core model generation system and to develop 4 cycle real time core analysis methodology with 5% power distribution and 500 pcm reactivity difference criteria for nuclear power plant simulator. The standardized procedure to generate database from ROCS and ANC, which are used for domestic PWR core design, was established for the cycle specific simulator core model generation. An automatic data interface system to generate core model also established. The system includes ARCADIS which edits group constant and DHCGEN which generates interface coupling coefficient correction database. The interface coupling coefficient correction method developed in this study has 4 cycle real time capability and accuracies of which the maximum differences between core design results are within 103 pcm reactivity, 1% relative power distribution and 6% control rod worth. A nuclear power plant core simulation program R-MASTER was developed using the methodology and applied by the concept of distributed client system in simulator. The performance was verified by site acceptance test in Simulator no. 2 in Kori Training Center for 30 initial condition generation and 27 steady state, transient and postulated accident situations
Improvement of Cycle Dependent Core Model for NPP Simulator
Energy Technology Data Exchange (ETDEWEB)
Song, J. S.; Koo, B. S.; Kim, H. Y. and others
2003-11-15
The purpose of this study is to establish automatic core model generation system and to develop 4 cycle real time core analysis methodology with 5% power distribution and 500 pcm reactivity difference criteria for nuclear power plant simulator. The standardized procedure to generate database from ROCS and ANC, which are used for domestic PWR core design, was established for the cycle specific simulator core model generation. An automatic data interface system to generate core model also established. The system includes ARCADIS which edits group constant and DHCGEN which generates interface coupling coefficient correction database. The interface coupling coefficient correction method developed in this study has 4 cycle real time capability and accuracies of which the maximum differences between core design results are within 103 pcm reactivity, 1% relative power distribution and 6% control rod worth. A nuclear power plant core simulation program R-MASTER was developed using the methodology and applied by the concept of distributed client system in simulator. The performance was verified by site acceptance test in Simulator no. 2 in Kori Training Center for 30 initial condition generation and 27 steady state, transient and postulated accident situations.
Toward a mineral physics reference model for the Moon's core.
Antonangeli, Daniele; Morard, Guillaume; Schmerr, Nicholas C; Komabayashi, Tetsuya; Krisch, Michael; Fiquet, Guillaume; Fei, Yingwei
2015-03-31
The physical properties of iron (Fe) at high pressure and high temperature are crucial for understanding the chemical composition, evolution, and dynamics of planetary interiors. Indeed, the inner structures of the telluric planets all share a similar layered nature: a central metallic core composed mostly of iron, surrounded by a silicate mantle, and a thin, chemically differentiated crust. To date, most studies of iron have focused on the hexagonal closed packed (hcp, or ε) phase, as ε-Fe is likely stable across the pressure and temperature conditions of Earth's core. However, at the more moderate pressures characteristic of the cores of smaller planetary bodies, such as the Moon, Mercury, or Mars, iron takes on a face-centered cubic (fcc, or γ) structure. Here we present compressional and shear wave sound velocity and density measurements of γ-Fe at high pressures and high temperatures, which are needed to develop accurate seismic models of planetary interiors. Our results indicate that the seismic velocities proposed for the Moon's inner core by a recent reanalysis of Apollo seismic data are well below those of γ-Fe. Our dataset thus provides strong constraints to seismic models of the lunar core and cores of small telluric planets. This allows us to propose a direct compositional and velocity model for the Moon's core.
Modelling of magnetostriction of transformer magnetic core for vibration analysis
Marks, Janis; Vitolina, Sandra
2017-12-01
Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.
Modelling of magnetostriction of transformer magnetic core for vibration analysis
Directory of Open Access Journals (Sweden)
Marks Janis
2017-12-01
Full Text Available Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.
Itoh, Kazuyoshi; Akimoto, Yoshihiro; Kondo, Shu; Ichimiya, Tomomi; Aoki, Kazuhiro; Tiemeyer, Michael; Nishihara, Shoko
2018-04-15
T antigen (Galβ1-3GalNAcα1-Ser/Thr) is an evolutionary-conserved mucin-type core 1 glycan structure in animals synthesized by core 1 β1,3-galactosyltransferase 1 (C1GalT1). Previous studies showed that T antigen produced by Drosophila C1GalT1 (dC1GalT1) was expressed in various tissues and dC1GalT1 loss in larvae led to various defects, including decreased number of circulating hemocytes, hyper-differentiation of hematopoietic stem cells in lymph glands, malformation of the central nervous system, mislocalization of neuromuscular junction (NMJ) boutons, and ultrastructural abnormalities in NMJs and muscle cells. Although glucuronylated T antigen (GlcAβ1-3Galβ1-3GalNAcα1-Ser/Thr) has been identified in Drosophila, the physiological function of this structure has not yet been clarified. In this study, for the first time, we unraveled biological roles of glucuronylated T antigen. Our data show that in Drosophila, glucuronylation of T antigen is predominantly carried out by Drosophila β1,3-glucuronyltransferase-P (dGlcAT-P). We created dGlcAT-P null mutants and found that mutant larvae showed lower expression of glucuronylated T antigen on the muscles and at NMJs. Furthermore, mislocalization of NMJ boutons and a partial loss of the basement membrane components collagen IV (Col IV) and nidogen (Ndg) at the muscle 6/7 boundary were observed. Those two phenotypes were correlated and identical to previously described phenotypes in dC1GalT1 mutant larvae. In addition, dGlcAT-P null mutants exhibited fewer NMJ branches on muscles 6/7. Moreover, ultrastructural analysis revealed that basement membranes that lacked Col IV and Ndg were significantly deformed. We also found that the loss of dGlcAT-P expression caused ultrastructural defects in NMJ boutons. Finally, we showed a genetic interaction between dGlcAT-P and dC1GalT1. Therefore, these results demonstrate that glucuronylated core 1 glycans synthesized by dGlcAT-P are key modulators of NMJ bouton localization
Geomagnetic core field models in the satellite era
DEFF Research Database (Denmark)
Lesur, Vincent; Olsen, Nils; Thomson, Alan W. P.
2011-01-01
After a brief review of the theoretical basis and difficulties that modelers are facing, we present three recent models of the geomagnetic field originating in the Earth’s core. All three modeling approaches are using recent observatory and near-Earth orbiting survey satellite data. In each case...
Directory of Open Access Journals (Sweden)
Hyein Lim
2013-01-01
Full Text Available Spin-torque oscillator (STO is a promising new technology for the future RF oscillators, which is based on the spin-transfer torque (STT effect in magnetic multilayered nanostructure. It is expected to provide a larger tunability, smaller size, lower power consumption, and higher level of integration than the semiconductor-based oscillators. In our previous work, a circuit-level model of the giant magnetoresistance (GMR STO was proposed. In this paper, we present a physics-based circuit-level model of the magnetic tunnel junction (MTJ-based STO. MTJ-STO model includes the effect of perpendicular torque that has been ignored in the GMR-STO model. The variations of three major characteristics, generation frequency, mean oscillation power, and generation linewidth of an MTJ-STO with respect to the amount of perpendicular torque, are investigated, and the results are applied to our model. The operation of the model was verified by HSPICE simulation, and the results show an excellent agreement with the experimental data. The results also prove that a full circuit-level simulation with MJT-STO devices can be made with our proposed model.
Modeling and Design of a New Flexible Graphene-on-Silicon Schottky Junction Solar Cell
Directory of Open Access Journals (Sweden)
Francesco Dell’Olio
2016-10-01
Full Text Available A new graphene-based flexible solar cell with a power conversion efficiency >10% has been designed. The environmental stability and the low complexity of the fabrication process are the two main advantages of the proposed device with respect to other flexible solar cells. The designed solar cell is a graphene/silicon Schottky junction whose performance has been enhanced by a graphene oxide layer deposited on the graphene sheet. The effect of the graphene oxide is to dope the graphene and to act as anti-reflection coating. A silicon dioxide ultrathin layer interposed between the n-Si and the graphene increases the open-circuit voltage of the cell. The solar cell optimization has been achieved through a mathematical model, which has been validated by using experimental data reported in literature. The new flexible photovoltaic device can be integrated in a wide range of microsystems powered by solar energy.
SCDAP/RELAP5 lower core plate model
International Nuclear Information System (INIS)
Coryell, E.W.; Griffin, F.P.
1999-01-01
The SCDAP/RELAP5 computer code is a best-estimate analysis tool for performing nuclear reactor severe accident simulations. This report describes the justification, theory, implementation, and testing of a new modeling capability which will refine the analysis of the movement of molten material from the core region to the vessel lower head. As molten material moves from the core region through the core support structures it may encounter conditions which will cause it to freeze in the region of the lower core plate, delaying its arrival to the vessel head. The timing of this arrival is significant to reactor safety, because during the time span for material relocation to the lower head, the core may be experiencing steam-limited oxidation. The time at which hot material arrives in a coolant-filled lower vessel head, thereby significantly increasing the steam flow rate through the core region, becomes significant to the progression and timing of a severe accident. This report is a revision of a report INEEL/EXT-00707, entitled ''Preliminary Design Report for SCDAP/RELAP5 Lower Core Plate Model''
Real-time advanced nuclear reactor core model
International Nuclear Information System (INIS)
Koclas, J.; Friedman, F.; Paquette, C.; Vivier, P.
1990-01-01
The paper describes a multi-nodal advanced nuclear reactor core model. The model is based on application of modern equivalence theory to the solution of neutron diffusion equation in real time employing the finite differences method. The use of equivalence theory allows the application of the finite differences method to cores divided into hundreds of nodes, as opposed to the much finer divisions (in the order of ten thousands of nodes) where the unmodified method is currently applied. As a result the model can be used for modelling of the core kinetics for real time full scope training simulators. Results of benchmarks, validate the basic assumptions of the model and its applicability to real-time simulation. (orig./HP)
Modeling of the core of Atucha II nuclear power plant
International Nuclear Information System (INIS)
Blanco, Anibal
2007-01-01
This work is part of a Nuclear Engineer degree thesis of the Instituto Balseiro and it is carried out under the development of an Argentinean Nuclear Power Plant Simulator. To obtain the best representation of the reactor physical behavior using the state of the art tools this Simulator should couple a 3D neutronics core calculation code with a thermal-hydraulics system code. Focused in the neutronic nature of this job, using PARCS, we modeled and performed calculations of the nuclear power plant Atucha 2 core. Whenever it is possible, we compare our results against results obtained with PUMA (the official core code for Atucha 2). (author) [es
Summary of multi-core hardware and programming model investigations
Energy Technology Data Exchange (ETDEWEB)
Kelly, Suzanne Marie; Pedretti, Kevin Thomas Tauke; Levenhagen, Michael J.
2008-05-01
This report summarizes our investigations into multi-core processors and programming models for parallel scientific applications. The motivation for this study was to better understand the landscape of multi-core hardware, future trends, and the implications on system software for capability supercomputers. The results of this study are being used as input into the design of a new open-source light-weight kernel operating system being targeted at future capability supercomputers made up of multi-core processors. A goal of this effort is to create an agile system that is able to adapt to and efficiently support whatever multi-core hardware and programming models gain acceptance by the community.
The QCD model of hadron cores of the meson theory
International Nuclear Information System (INIS)
Pokrovskii, Y.E.
1985-01-01
It was shown that in the previously proposed QCD model of hadron cores the exchange and self-energy contributions of the virtual quark-antiquark-gluon cloud on the outside of a bag which radius coincides with the hardon core radius of the meson theory (∼ 0.4 Fm) have been taken into account at the phenomenological level. Simulation of this cloud by the meson field results in realistic estimations of the nucleon's electroweak properties, moment fractions carried by gluons, quarks, antiquarks and hadron-hadron interaction cross-sections within a wide range of energies. The authors note that the QCD hadron core model proposed earlier not only realistically reflects the hadron masses, but reflects self-consistently main elements of the structure and interaction of hadrons at the quark-gluon bag radius (R - 0.4Fm) being close to the meson theory core radius
International Nuclear Information System (INIS)
Kawabata, C.; Shenoy, S.R.; Bishop, A.R.
1994-11-01
We model high T c superconductors (HTS) by quantum capacitive Josephson junction arrays (JJA), with Angstrom-scale parameters, to obtain an estimate of Tc trends. The basic idea is as follows. Number (or change) and phase are conjugate variables, with the uncertainty products obeying ΔN · Δ Θ > 1. Thus, in HTS, global phase coherence is opposed by charging-energy induced quantum phase fluctuations, especially across Josephson-coupled CuO 2 planes. These have separation d 1 and effective interplanar dielectric constant ε, e.g. from Y atoms in YBaCuO. Decreasing the interplane charging energy E 0 perpendicular to ∼ d 1 /ε, raises Tc. In Section 1, we motivate a modelling of HTS phase excitations by a quantum capacitive 3D JJA model, with XY planar phases. Section 2 gives a physical picture of the HTS transition, relating the complex layered HTS structure to a simpler ''intermediate level'' quantum 3D JJA/XY model. Section 3 sets up a path integral (3+1)D model that reduces to a previously studied anisotropic 3D XY/JJA model, with constants renormalized in some way, by the capacitance. Postponing a detailed analysis to elsewhere, we make a heuristic estimate for the reduction of the previous Tc, by the charging energy. (author). 30 refs, 8 figs
Modelling perspectives on radiation chemistry in BWR reactor core
International Nuclear Information System (INIS)
Ibe, Eishi
1991-01-01
Development of a full-system boiling water reactor core model started in 1982. The model included a two-region reactor core, one with and one without boiling. Key design parameters consider variable dose rates in a three-layer liquid downcomer. Dose rates in the core and downcomer include both generation and recombination reactions of species. Agreement is good between calculations and experimental data of oxygen concentration as a function of hydrogen concentration for different bubble sizes. Oxygen concentration is reduced in the reactor pressure vessel (RPV) by increasing bubble size. The multilayer model follows the oxygen data better than a single-layered model at high concentrations of hydrogen. Key reactions are reduced to five radiolysis reactions and four decomposition reactions for hydrogen peroxide. Calculations by the DOT 3 code showed dose rates from neutrons and gamma rays in various parts of the core. Concentrations of oxygen, hydrogen peroxide, and hydrogen were calculated by the model as a function of time from core inlet. Similar calculations for NWC and HWC were made as a function of height from core inlet both in the boiling channel an the bypass channel. Finally the model was applied to calculate the oxygen plus half the hydrogen peroxide concentrations as a function of hydrogen concentration to compare with data from five plants. Power density distribution with core height was given for an early stage and an end stage of a cycle. Increases of dose rates in the turbine for seven plants were shown as a function of increased hydrogen concentration in the reactor water
Core seismic behaviour: linear and non-linear models
International Nuclear Information System (INIS)
Bernard, M.; Van Dorsselaere, M.; Gauvain, M.; Jenapierre-Gantenbein, M.
1981-08-01
The usual methodology for the core seismic behaviour analysis leads to a double complementary approach: to define a core model to be included in the reactor-block seismic response analysis, simple enough but representative of basic movements (diagrid or slab), to define a finer core model, with basic data issued from the first model. This paper presents the history of the different models of both kinds. The inert mass model (IMM) yielded a first rough diagrid movement. The direct linear model (DLM), without shocks and with sodium as an added mass, let to two different ones: DLM 1 with independent movements of the fuel and radial blanket subassemblies, and DLM 2 with a core combined movement. The non-linear (NLM) ''CORALIE'' uses the same basic modelization (Finite Element Beams) but accounts for shocks. It studies the response of a diameter on flats and takes into account the fluid coupling and the wrapper tube flexibility at the pad level. Damping consists of one modal part of 2% and one part due to shocks. Finally, ''CORALIE'' yields the time-history of the displacements and efforts on the supports, but damping (probably greater than 2%) and fluid-structures interaction are still to be precised. The validation experiments were performed on a RAPSODIE core mock-up on scale 1, in similitude of 1/3 as to SPX 1. The equivalent linear model (ELM) was developed for the SPX 1 reactor-block response analysis and a specified seismic level (SB or SM). It is composed of several oscillators fixed to the diagrid and yields the same maximum displacements and efforts than the NLM. The SPX 1 core seismic analysis with a diagrid input spectrum which corresponds to a 0,1 g group acceleration, has been carried out with these models: some aspects of these calculations are presented here
Isabella, O.; Elshinawy, M.A.A.; Solntsev, S.; Zeman, M.
2012-01-01
Superstrate thin-film silicon triple-junction solar cells on 2-D gratings were optimized using opto-electrical modeling. Tuning the thickness of intermediate and back reflectors and the band gap of the middle cell resulted in 17% initial efficiency.
Computational models of stellar collapse and core-collapse supernovae
International Nuclear Information System (INIS)
Ott, Christian D; O'Connor, Evan; Schnetter, Erik; Loeffler, Frank; Burrows, Adam; Livne, Eli
2009-01-01
Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and provides a scalable AMR approach for 3D fully general-relativistic modeling of stellar collapse, core-collapse supernovae and black hole formation on current and future massively-parallel HPC systems. We show Zelmani's scaling properties to more than 16,000 compute cores and discuss first 3D general-relativistic core-collapse results.
Computational models of stellar collapse and core-collapse supernovae
Energy Technology Data Exchange (ETDEWEB)
Ott, Christian D; O' Connor, Evan [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA (United States); Schnetter, Erik; Loeffler, Frank [Center for Computation and Technology, Louisiana State University, Baton Rouge, LA (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ (United States); Livne, Eli, E-mail: cott@tapir.caltech.ed [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)
2009-07-01
Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and provides a scalable AMR approach for 3D fully general-relativistic modeling of stellar collapse, core-collapse supernovae and black hole formation on current and future massively-parallel HPC systems. We show Zelmani's scaling properties to more than 16,000 compute cores and discuss first 3D general-relativistic core-collapse results.
VHTR core modeling: coupling between neutronic and thermal-hydraulics
International Nuclear Information System (INIS)
Limaiem, I.; Damian, F.; Raepsaet, X.; Studer, E.
2005-01-01
Following the present interest in the next generation nuclear power plan (NGNP), Cea is deploying special effort to develop new models and qualify its research tools for this next generation reactors core. In this framework, the Very High Temperature Reactor concept (VHTR) has an increasing place in the actual research program. In such type of core, a strong interaction exists between neutronic and thermal-hydraulics. Consequently, the global core modelling requires accounting for the temperature feedback in the neutronic models. The purpose of this paper is to present the new neutronic and thermal-hydraulics coupling model dedicated to the High Temperature Reactors (HTR). The coupling model integrates a new version of the neutronic scheme calculation developed in collaboration between Cea and Framatome-ANP. The neutronic calculations are performed using a specific calculation processes based on the APOLLO2 transport code and CRONOS2 diffusion code which are part of the French reactor physics code system SAPHYR. The thermal-hydraulics model is characterised by an equivalent porous media and 1-D fluid/3-D thermal model implemented in the CAST3M/ARCTURUS code. The porous media approach involves the definition of both homogenous and heterogeneous models to ensure a correct temperature feedback. This study highlights the sensitivity of the coupling system's parameters (radial/axial meshing and data exchange strategy between neutronic and thermal-hydraulics code). The parameters sensitivity study leads to the definition of an optimal coupling system specification for the VHTR. Besides, this work presents the first physical analysis of the VHTR core in steady-state condition. The analysis gives information about the 3-D power peaking and the temperature coefficient. Indeed, it covers different core configurations with different helium distribution in the core bypass. (authors)
Modeling of Core Competencies in the Registrar's Office
Pikowsky, Reta
2009-01-01
The Office of the Registrar at the Georgia Institute of Technology, in cooperation with the Office of Human Resources, has been engaged since February 2008 in a pilot project to model core competencies for the leadership team and the staff. It is the hope of the office of Human resources that this pilot will result in a model that can be used…
Compact modeling of SiC Schottky barrier diode and its extension to junction barrier Schottky diode
Navarro, Dondee; Herrera, Fernando; Zenitani, Hiroshi; Miura-Mattausch, Mitiko; Yorino, Naoto; Jürgen Mattausch, Hans; Takusagawa, Mamoru; Kobayashi, Jun; Hara, Masafumi
2018-04-01
A compact model applicable for both Schottky barrier diode (SBD) and junction barrier Schottky diode (JBS) structures is developed. The SBD model considers the current due to thermionic emission in the metal/semiconductor junction together with the resistance of the lightly doped drift layer. Extension of the SBD model to JBS is accomplished by modeling the distributed resistance induced by the p+ implant developed for minimizing the leakage current at reverse bias. Only the geometrical features of the p+ implant are necessary to model the distributed resistance. Reproduction of 4H-SiC SBD and JBS current-voltage characteristics with the developed compact model are validated against two-dimensional (2D) device-simulation results as well as measurements at different temperatures.
Filatrella, G
2002-01-01
The technology to build reproducible and accurately defined structures consisting of many lumped junctions has become available only recently, therefore extended investigations are relatively new. However, beside the interest of such discrete structures per se, it has been suggested soon after the discovery of high-T sub c superconductivity that granular superconductors might be modelled as superconducting islands surrounded by non-superconducting material and weakly coupled to each other. This program has been vigorously carried on, and models of planar Josephson junction arrays (JJAs) have been successfully used to mimic the magnetic behaviour of granular superconductors. The JJA model has been compared to continuous models of non-granular superconductors. We will show how to derive the height of pinning barriers in the JJA model and compare the results with the continuous model. In particular, the existence of current dependent activation energy has been proved to be a key characteristic to understand flux...
Core/corona modeling of diode-imploded annular loads
Terry, R. E.; Guillory, J. U.
1980-11-01
The effects of a tenuous exterior plasma corona with anomalous resistivity on the compression and heating of a hollow, collisional aluminum z-pinch plasma are predicted by a one-dimensional code. As the interior ("core") plasma is imploded by its axial current, the energy exchange between core and corona determines the current partition. Under the conditions of rapid core heating and compression, the increase in coronal current provides a trade-off between radial acceleration and compression, which reduces the implosion forces and softens the pitch. Combined with a heuristic account of energy and momentum transport in the strongly coupled core plasma and an approximate radiative loss calculation including Al line, recombination and Bremsstrahlung emission, the current model can provide a reasonably accurate description of imploding annular plasma loads that remain azimuthally symmetric. The implications for optimization of generator load coupling are examined.
Digital Core Modelling for Clastic Oil and Gas Reservoir
Belozerov, I.; Berezovsky, V.; Gubaydullin, M.; Yur’ev, A.
2018-05-01
"Digital core" is a multi-purpose tool for solving a variety of tasks in the field of geological exploration and production of hydrocarbons at various stages, designed to improve the accuracy of geological study of subsurface resources, the efficiency of reproduction and use of mineral resources, as well as applying the results obtained in production practice. The actuality of the development of the "Digital core" software is that even a partial replacement of natural laboratory experiments with mathematical modelling can be used in the operative calculation of reserves in exploratory drilling, as well as in the absence of core material from wells. Or impossibility of its research by existing laboratory methods (weakly cemented, loose, etc. rocks). 3D-reconstruction of the core microstructure can be considered as a cheap and least time-consuming method for obtaining petrophysical information about the main filtration-capacitive properties and fluid motion in reservoir rocks.
A calculation model for a HTR core seismic response
International Nuclear Information System (INIS)
Buland, P.; Berriaud, C.; Cebe, E.; Livolant, M.
1975-01-01
The paper presents the experimental results obtained at Saclay on a HTGR core model and comparisons with analytical results. Two series of horizontal tests have been performed on the shaking table VESUVE: sinusoidal test and time history response. Acceleration of graphite blocks, forces on the boundaries, relative displacement of the core and PCRB model, impact velocity of the blocks on the boundaries were recorded. These tests have shown the strongly non-linear dynamic behaviour of the core. The resonant frequency of the core is dependent on the level of the excitation. These phenomena have been explained by a computer code, which is a lumped mass non-linear model. Good correlation between experimental and analytical results was obtained for impact velocities and forces on the boundaries. This comparison has shown that the damping of the core is a critical parameter for the estimation of forces and velocities. Time history displacement at the level of PCRV was reproduced on the shaking table. The analytical model was applied to this excitation and good agreement was obtained for forces and velocities. (orig./HP) [de
Energy Technology Data Exchange (ETDEWEB)
Berry, R. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2017-08-14
In the literature, the abundance of pipe network junction models, as well as inclusion of dissipative losses between connected pipes with loss coefficients, has been treated using the incompressible flow assumption of constant density. This approach is fundamentally, physically wrong for compressible flow with density change. This report introduces a mathematical modeling approach for general junctions in piping network systems for which the transient flows are compressible and single-phase. The junction could be as simple as a 1-pipe input and 1-pipe output with differing pipe cross-sectional areas for which a dissipative loss is necessary, or it could include an active component, between an inlet pipe and an outlet pipe, such as a pump or turbine. In this report, discussion will be limited to the former. A more general branching junction connecting an arbitrary number of pipes with transient, 1-D compressible single-phase flows is also presented. These models will be developed in a manner consistent with the use of a general equation of state like, for example, the recent Spline-Based Table Look-up method [1] for incorporating the IAPWS-95 formulation [2] to give accurate and efficient calculations for properties for water and steam with RELAP-7 [3].
AGR core models and their application to HTRs and RBMKs
International Nuclear Information System (INIS)
Baylis, Samuel
2014-01-01
EDF Energy operates 14 AGRs, commissioned between 1976 and 1989. The graphite moderators of these gas cooled reactors are subjected to a number of ageing processes under fast neutron irradiation in a high temperature CO2 environment. As the graphite ages, continued safe operation requires an advanced whole-core modeling capability to enable accurate assessments of the core’s ability to fulfil fundamental nuclear safety requirements. This is also essential in evaluating the reactor's remaining economic lifetime, and similar assessments are useful for HTRs in the design stage. A number of computational and physical models of AGR graphite cores have been developed or are in development, allowing simulation of the reactors in normal, fault and seismic conditions. Many of the techniques developed are applicable to other graphite moderated reactors. Modeling of the RBMK allows validation against a core in a more advanced state of ageing than the AGRs, while there is also an opportunity to adapt the models for high temperature reactors. As an example, a finite element model of the HTR-PM side reflector based on rigid bodies and nonlinear springs is developed, allowing rapid assessments of distortion in the structure to be made. A model of the RBMK moderator has also been produced using an established AGR code based on similar methods. In addition, this paper discusses the limitations of these techniques and the development of more complex core models that address these limitations, along with the lessons that can be applied to HTRs. (author)
Evaluating nuclear physics inputs in core-collapse supernova models
Lentz, E.; Hix, W. R.; Baird, M. L.; Messer, O. E. B.; Mezzacappa, A.
Core-collapse supernova models depend on the details of the nuclear and weak interaction physics inputs just as they depend on the details of the macroscopic physics (transport, hydrodynamics, etc.), numerical methods, and progenitors. We present preliminary results from our ongoing comparison studies of nuclear and weak interaction physics inputs to core collapse supernova models using the spherically-symmetric, general relativistic, neutrino radiation hydrodynamics code Agile-Boltztran. We focus on comparisons of the effects of the nuclear EoS and the effects of improving the opacities, particularly neutrino--nucleon interactions.
Modeling of switching energy of magnetic tunnel junction devices with tilted magnetization
International Nuclear Information System (INIS)
Surawanitkun, C.; Kaewrawang, A.; Siritaratiwat, A.; Kruesubthaworn, A.; Sivaratana, R.; Jutong, N.; Mewes, C.K.A.; Mewes, T.
2015-01-01
For spin transfer torque (STT), the switching energy and thermal stability of magnetic tunnel junctions (MTJ) bits utilized in memory devices are important factors that have to be considered simultaneously. In this article, we examined the minimum energy for STT induced magnetization switching in MTJ devices for different in-plane angles of the magnetization in the free layer and the pinned layer with respect to the major axis of the elliptical cylinder of the cell. Simulations were performed by comparing the analytical solution with macrospin and full micromagnetic calculations. The results show good agreement of the switching energy calculated by using the three approaches for different initial angles of the magnetization of the free layer. Also, the low-energy location specifies the suitable value of both time and current in order to reduce the heat effect during the switching process. - Highlights: • Switching energy model was firstly examined with tiled magnetization in STT-RAM. • Simulation was performed by analytical solution, macrospin and micromagnetic models. • Low energy results from three models show agreement for tilt angle in free layer. • We also found an optimal tilt angle of the pinned layer. • Low-energy location specifies the suitable switching location to reduce heat effect
Modeling and Implementation of HfO2-based Ferroelectric Tunnel Junctions
Pringle, Spencer Allen
HfO2-based ferroelectric tunnel junctions (FTJs) represent a unique opportunity as both a next-generation digital non-volatile memory and as synapse devices in braininspired logic systems, owing to their higher reliability compared to filamentary resistive random-access memory (ReRAM) and higher speed and lower power consumption compared to competing devices, including phase-change memory (PCM) and state-of-the-art FTJ. Ferroelectrics are often easier to deposit and have simpler material structure than films for magnetic tunnel junctions (MTJs). Ferroelectric HfO2 also enables complementary metal-oxide-semiconductor (CMOS) compatibility, since lead zirconate titanate (PZT) and BaTiO3-based FTJs often are not. No other groups have yet demonstrated a HfO2-based FTJ (to best of the author's knowledge) or applied it to a suitable system. For such devices to be useful, system designers require models based on both theoretical physical analysis and experimental results of fabricated devices in order to confidently design control systems. Both the CMOS circuitry and FTJs must then be designed in layout and fabricated on the same die. This work includes modeling of proposed device structures using a custom python script, which calculates theoretical potential barrier heights as a function of material properties and corresponding current densities (ranging from 8x103 to 3x10-2 A/cm 2 with RHRS/RLRS ranging from 5x105 to 6, depending on ferroelectric thickness). These equations were then combined with polynomial fits of experimental timing data and implemented in a Verilog-A behavioral analog model in Cadence Virtuoso. The author proposes tristate CMOS control systems, and circuits, for implementation of FTJ devices as digital memory and presents simulated performance. Finally, a process flow for fabrication of FTJ devices with CMOS is presented. This work has therefore enabled the fabrication of FTJ devices at RIT and the continued investigation of them as applied to any
Myotubular myopathy and the neuromuscular junction: a novel therapeutic approach from mouse models
Directory of Open Access Journals (Sweden)
James J. Dowling
2012-11-01
Myotubular myopathy (MTM is a severe congenital muscle disease characterized by profound weakness, early respiratory failure and premature lethality. MTM is defined by muscle biopsy findings that include centralized nuclei and disorganization of perinuclear organelles. No treatments currently exist for MTM. We hypothesized that aberrant neuromuscular junction (NMJ transmission is an important and potentially treatable aspect of the disease pathogenesis. We tested this hypothesis in two murine models of MTM. In both models we uncovered evidence of a disorder of NMJ transmission: fatigable weakness, improved strength with neostigmine, and electrodecrement with repetitive nerve stimulation. Histopathological analysis revealed abnormalities in the organization, appearance and size of individual NMJs, abnormalities that correlated with changes in acetylcholine receptor gene expression and subcellular localization. We additionally determined the ability of pyridostigmine, an acetylcholinesterase inhibitor, to ameliorate aspects of the behavioral phenotype related to NMJ dysfunction. Pyridostigmine treatment resulted in significant improvement in fatigable weakness and treadmill endurance. In all, these results describe a newly identified pathological abnormality in MTM, and uncover a potential disease-modifying therapy for this devastating disorder.
Modeling and fabrication of 4H-SiC Schottky junction
Martychowiec, A.; Pedryc, A.; Kociubiński, A.
2017-08-01
The rapidly growing demand for electronic devices requires using of alternative semiconductor materials, which could replace conventional silicon. Silicon carbide has been proposed for these harsh environment applications (high temperature, high voltage, high power conditions) because of its wide bandgap, its high temperature operation ability, its excellent thermal and chemical stability, and its high breakdown electric field strength. The Schottky barrier diode (SBD) is known as one of the best refined SiC devices. This paper presents prepared model, simulations and description of technology of 4H-SiC Schottky junction as well as characterization of fabricated structures. The future aim of the application of the structures is an optical detection of an ultraviolet radiation. The model section contains a comparison of two different solutions of SBD's construction. Simulations - as a crucial process of designing electronic devices - have been performed using the ATLAS device of Silvaco TCAD software. As a final result the paper shows I-V characteristics of fabricated diodes.
International Nuclear Information System (INIS)
Flood, Amar H.; Wong, Eric W.; Stoddart, J. Fraser
2006-01-01
The processes by which charge transfer can occur play a foundational role in molecular electronics. Here we consider simplified models of the transfer processes that could be present in bistable molecular switch tunnel junction (MSTJ) devices during one complete cycle of the device from its low- to high- and back to low-conductance state. The bistable molecular switches, which are composed of a monolayer of either switchable catenanes or rotaxanes, exist in either a ground-state co-conformation or a metastable one in which the conduction properties of the two co-conformations, when measured at small biases (+0.1 V), are significantly different irrespective of whether transport is dominated by tunneling or hopping. The voltage-driven generation (±2 V) of molecule-based redox states, which are sufficiently long-lived to allow the relative mechanical movements necessary to switch between the two co-conformations, rely upon unequal charge transfer rates on to and/or off of the molecules. Surface-enhanced Raman spectroscopy has been used to image the ground state of the bistable rotaxane in MSTJ-like devices. Consideration of these models provide new ways of looking at molecular electronic devices that rely, not only on nanoscale charge-transport, but also upon the bustling world of molecular motion in mechanically interlocked bistable molecules
Treating network junctions in finite volume solution of transient gas flow models
Bermúdez, Alfredo; López, Xián; Vázquez-Cendón, M. Elena
2017-09-01
A finite volume scheme for the numerical solution of a non-isothermal non-adiabatic compressible flow model for gas transportation networks on non-flat topography is introduced. Unlike standard Euler equations, the model takes into account wall friction, variable height and heat transfer between the pipe and the environment which are source terms. The case of one single pipe was considered in a previous reference by the authors, [8], where a finite volume method with upwind discretization of the flux and source terms has been proposed in order to get a well-balanced scheme. The main goal of the present paper is to go a step further by considering a network of pipes. The main issue is the treatment of junctions for which container-like 2D finite volumes are introduced. The couplings between pipes (1D) and containers (2D) are carefully described and the conservation properties are analyzed. Numerical tests including real gas networks are solved showing the performance of the proposed methodology.
Modeling of Operating Temperature Performance of Triple Junction Solar Cells Using Silvaco's ATLAS
National Research Council Canada - National Science Library
Sanders, Michael H
2007-01-01
.... Building upon prior thesis work at the Naval Postgraduate School, this thesis utilizes Silvaco's ATLAS software as a tool to simulate the performance of a typical InGaP/GaAs/Ge multi-junction solar...
Mathematical Modeling, Sense Making, and the Common Core State Standards
Schoenfeld, Alan H.
2013-01-01
On October 14, 2013 the Mathematics Education Department at Teachers College hosted a full-day conference focused on the Common Core Standards Mathematical Modeling requirements to be implemented in September 2014 and in honor of Professor Henry Pollak's 25 years of service to the school. This article is adapted from my talk at this conference…
Miyahara, Satoshi; Saito, Mitsumasa; Kanemaru, Takaaki; Villanueva, Sharon Y A M; Gloriani, Nina G; Yoshida, Shin-ichi
2014-08-01
Weil's disease, the most severe form of leptospirosis, is characterized by jaundice, haemorrhage and renal failure. The mechanisms of jaundice caused by pathogenic Leptospira remain unclear. We therefore aimed to elucidate the mechanisms by integrating histopathological changes with serum biochemical abnormalities during the development of jaundice in a hamster model of Weil's disease. In this work, we obtained three-dimensional images of infected hamster livers using scanning electron microscope together with freeze-cracking and cross-cutting methods for sample preparation. The images displayed the corkscrew-shaped bacteria, which infiltrated the Disse's space, migrated between hepatocytes, detached the intercellular junctions and disrupted the bile canaliculi. Destruction of bile canaliculi coincided with the elevation of conjugated bilirubin, aspartate transaminase and alkaline phosphatase levels in serum, whereas serum alanine transaminase and γ-glutamyl transpeptidase levels increased slightly, but not significantly. We also found in ex vivo experiments that pathogenic, but not non-pathogenic leptospires, tend to adhere to the perijunctional region of hepatocyte couplets isolated from hamsters and initiate invasion of the intercellular junction within 1 h after co-incubation. Our results suggest that pathogenic leptospires invade the intercellular junctions of host hepatocytes, and this invasion contributes in the disruption of the junction. Subsequently, bile leaks from bile canaliculi and jaundice occurs immediately. Our findings revealed not only a novel pathogenicity of leptospires, but also a novel mechanism of jaundice induced by bacterial infection. © 2014 The Authors. International Journal of Experimental Pathology © 2014 International Journal of Experimental Pathology.
Vibration tests on some models of PEC reactor core elements
International Nuclear Information System (INIS)
Bonacina, G.; Castoldi, A.; Zola, M.; Cecchini, F.; Martelli, A.; Vincenzi, D.
1982-01-01
This paper describes the aims of the experimental tests carried out at ISMES, within an agreement with the Department of Fast Reactors of ENEA, on some models of the elements of PEC Fast Nuclear Reactor Core in the frame of the activities for the seismic verification of the PEC core. The seismic verification is briefly described with particular attention to the problems arising from the shocks among the various elements during an earthquake, as well as the computer code used, the purpose and the techniques used to perform tests, some results and the first comparison between the theory and the experimental data
Development of local TDC model in core thermal hydraulic analysis
International Nuclear Information System (INIS)
Kwon, H.S.; Park, J.R.; Hwang, D.H.; Lee, S.K.
2004-01-01
The local TDC model consisting of natural mixing and forced mixing part was developed to obtain more realistic local fluid properties in the core subchannel analysis. To evaluate the performance of local TDC model, the CHF prediction capability was tested with the various CHF correlations and local fluid properties at CHF location which are based on the local TDC model. The results show that the standard deviation of measured to predicted CHF ratio (M/P) based on local TDC model can be reduced by about 7% compared to those based on global TDC model when the CHF correlation has no term to account for distance from the spacer grid. (author)
Modeling of impurity transport in the core plasma
International Nuclear Information System (INIS)
Hulse, R.A.
1992-01-01
This paper presents a brief overview of computer modeling of impurity transport in the core region of controlled thermonuclear fusion plasmas. The atomic processes of importance in these high temperature plasmas and the numerical formulation of the model are described. Selected modeling examples are then used to highlight some features of the physics of impurity behavior in large tokamak fusion devices, with an emphasis on demonstrating the sensitivity of such modeling to uncertainties in the rate coefficients used for the atomic processes. This leads to a discussion of current requirements and opportunities for generating the improved sets of comprehensive atomic data needed to support present and future fusion impurity modeling studies
Modeling of reflood of severely damaged reactor core
International Nuclear Information System (INIS)
Bachrata, A.
2012-01-01
The TMI-2 accident and recently Fukushima accident demonstrated that the nuclear safety philosophy has to cover accident sequences involving massive core melt in order to develop reliable mitigation strategies for both, existing and advanced reactors. Although severe accidents are low likelihood and might be caused only by multiple failures, accident management is implemented for controlling their course and mitigating their consequences. In case of severe accident, the fuel rods may be severely damaged and oxidized. Finally, they collapse and form a debris bed on core support plate. Removal of decay heat from a damaged core is a challenging issue because of the difficulty for water to penetrate inside a porous medium. The reflooding (injection of water into core) may be applied only if the availability of safety injection is recovered during accident. If the injection becomes available only in the late phase of accident, water will enter a core configuration that will differ from original rod bundle geometry and will resemble to the severe damaged core observed in TMI-2. The higher temperatures and smaller hydraulic diameters in a porous medium make the coolability more difficult than for intact fuel rods under typical loss of coolant accident conditions. The modeling of this kind of hydraulic and heat transfer is a one of key objectives of this. At IRSN, part of the studies is realized using an European thermo-hydraulic computer code for severe accident analysis ICARE-CATHARE. The objective of this thesis is to develop a 3D reflood model (implemented into ICARE-CATHARE) that is able to treat different configurations of degraded core in a case of severe accident. The proposed model is characterized by treating of non-equilibrium thermal between the solid, liquid and gas phase. It includes also two momentum balance equations. The model is based on a previously developed model but is improved in order to take into account intense boiling regimes (in particular
Quasiparticle energies and lifetimes in a metallic chain model of a tunnel junction.
Szepieniec, Mark; Yeriskin, Irene; Greer, J C
2013-04-14
As electronics devices scale to sub-10 nm lengths, the distinction between "device" and "electrodes" becomes blurred. Here, we study a simple model of a molecular tunnel junction, consisting of an atomic gold chain partitioned into left and right electrodes, and a central "molecule." Using a complex absorbing potential, we are able to reproduce the single-particle energy levels of the device region including a description of the effects of the semi-infinite electrodes. We then use the method of configuration interaction to explore the effect of correlations on the system's quasiparticle peaks. We find that when excitations on the leads are excluded, the device's highest occupied molecular orbital and lowest unoccupied molecular orbital quasiparticle states when including correlation are bracketed by their respective values in the Hartree-Fock (Koopmans) and ΔSCF approximations. In contrast, when excitations on the leads are included, the bracketing property no longer holds, and both the positions and the lifetimes of the quasiparticle levels change considerably, indicating that the combined effect of coupling and correlation is to alter the quasiparticle spectrum significantly relative to an isolated molecule.
Thermal hydraulics model for Sandia's annular core research reactor
International Nuclear Information System (INIS)
Rao, Dasari V.; El-Genk, Mohamed S.; Rubio, Reuben A.; Bryson, James W.; Foushee, Fabian C.
1988-01-01
A thermal hydraulics model was developed for the Annular Core Research Reactor (ACRR) at Sandia National Laboratories. The coupled mass, momentum and energy equations for the core were solved simultaneously using an explicit forward marching numerical technique. The model predictions of the temperature rise across the central channel of the ACRR core were within ± 10 percent agreement with the in-core temperature measurements. The model was then used to estimate the coolant mass flow rate and the axial distribution of the cladding surface temperature in the central and average channels as functions of the operating power and the water inlet subcooling. Results indicated that subcooled boiling occurs at the cladding surface in the central channels of the ACRR at power levels in excess of 0.5 MW. However, the high heat transfer coefficient due to subcooled boiling causes the cladding temperature along most of the active fuel rod region to be quite uniform and to increase very little with the reactor power. (author)
Core Organizational Stakeholder Impact – An assessment model
Carvalho, João M. S.
2013-01-01
Measurement of organizational social impact is a pressing issue in corporate social responsibility research. This paper proposes an alternative measurement model – Core Organizational Stakeholder Impact (COSI) – based on economic, legal and ethical responsibilities of organizations. The model allows understanding organizational social footprint, i.e., how organizations impact each stakeholder. It has 40 indicators, easy to apply, dividing internal and external stakeholders in equa...
Accelerating Atmospheric Modeling Through Emerging Multi-core Technologies
Linford, John Christian
2010-01-01
The new generations of multi-core chipset architectures achieve unprecedented levels of computational power while respecting physical and economical constraints. The cost of this power is bewildering program complexity. Atmospheric modeling is a grand-challenge problem that could make good use of these architectures if they were more accessible to the average programmer. To that end, software tools and programming methodologies that greatly simplify the acceleration of atmospheric modeling...
A simple model for induction core voltage distributions
International Nuclear Information System (INIS)
Briggs, Richard J.; Fawley, William M.
2004-01-01
In fall 2003 T. Hughes of MRC used a full EM simulation code (LSP) to show that the electric field stress distribution near the outer radius of the longitudinal gaps between the four Metglas induction cores is very nonuniform in the original design of the DARHT-2 accelerator cells. In this note we derive a simple model of the electric field distribution in the induction core region to provide physical insights into this result. The starting point in formulating our model is to recognize that the electromagnetic fields in the induction core region of the DARHT-2 accelerator cells should be accurately represented within a quasi-static approximation because the timescale for the fields to change is much longer than the EM wave propagation time. The difficulty one faces is the fact that the electric field is a mixture of both a ''quasi-magnetostatic field'' (having a nonzero curl, with Bdot the source) and a ''quasi-electrostatic field'' (the source being electric charges on the various metal surfaces). We first discuss the EM field structure on the ''micro-scale'' of individual tape windings in Section 2. The insights from that discussion are then used to formulate a ''macroscopic'' description of the fields inside an ''equivalent homogeneous tape wound core region'' in Section 3. This formulation explicitly separates the nonlinear core magnetics from the quasi-electrostatic components of the electric field. In Section 4 a physical interpretation of the radial dependence of the electrostatic component of the electric field derived from this model is presented in terms of distributed capacitances, and the voltage distribution from gap to gap is related to various ''equivalent'' lumped capacitances. Analytic solutions of several simple multi-core cases are presented in Sections 5 and 6 to help provide physical insight into the effect of various proposed changes in the geometrical parameters of the DARHT-2 accelerator cell. Our results show that over most of the gap
Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik
2013-01-01
Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031
VIPRE modeling of VVER-1000 reactor core for DNB analyses
Energy Technology Data Exchange (ETDEWEB)
Sung, Y.; Nguyen, Q. [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Cizek, J. [Nuclear Research Institute, Prague, (Czech Republic)
1995-09-01
Based on the one-pass modeling approach, the hot channels and the VVER-1000 reactor core can be modeled in 30 channels for DNB analyses using the VIPRE-01/MOD02 (VIPRE) code (VIPRE is owned by Electric Power Research Institute, Palo Alto, California). The VIPRE one-pass model does not compromise any accuracy in the hot channel local fluid conditions. Extensive qualifications include sensitivity studies of radial noding and crossflow parameters and comparisons with the results from THINC and CALOPEA subchannel codes. The qualifications confirm that the VIPRE code with the Westinghouse modeling method provides good computational performance and accuracy for VVER-1000 DNB analyses.
Directory of Open Access Journals (Sweden)
Fernando Gimeno Bellver
Full Text Available In this paper, we explore the chaotic behavior of resistively and capacitively shunted Josephson junctions via the so-called Network Simulation Method. Such a numerical approach establishes a formal equivalence among physical transport processes and electrical networks, and hence, it can be applied to efficiently deal with a wide range of differential systems.The generality underlying that electrical equivalence allows to apply the circuit theory to several scientific and technological problems. In this work, the Fast Fourier Transform has been applied for chaos detection purposes and the calculations have been carried out in PSpice, an electrical circuit software.Overall, it holds that such a numerical approach leads to quickly computationally solve Josephson differential models. An empirical application regarding the study of the Josephson model completes the paper. Keywords: Electrical analogy, Network Simulation Method, Josephson junction, Chaos indicator, Fast Fourier Transform
The hard-core model on random graphs revisited
International Nuclear Information System (INIS)
Barbier, Jean; Krzakala, Florent; Zhang, Pan; Zdeborová, Lenka
2013-01-01
We revisit the classical hard-core model, also known as independent set and dual to vertex cover problem, where one puts particles with a first-neighbor hard-core repulsion on the vertices of a random graph. Although the case of random graphs with small and very large average degrees respectively are quite well understood, they yield qualitatively different results and our aim here is to reconciliate these two cases. We revisit results that can be obtained using the (heuristic) cavity method and show that it provides a closed-form conjecture for the exact density of the densest packing on random regular graphs with degree K ≥ 20, and that for K > 16 the nature of the phase transition is the same as for large K. This also shows that the hard-code model is the simplest mean-field lattice model for structural glasses and jamming
Model of coupling with core in the Green function method
International Nuclear Information System (INIS)
Kamerdzhiev, S.P.; Tselyaev, V.I.
1983-01-01
Models of coupling with core in the method of the Green functions, presenting generalization of conventional method of chaotic phases, i.e. account of configurations of more complex than monoparticle-monohole (1p1h) configurations, have been considered. Odd nuclei are studied only to the extent when the task of odd nucleus is solved for even-even nucleus. Microscopic model of the account of delay effects in mass operator M=M(epsilon), which corresponds to the account of the effects influence only on the change of quasiparticle behaviour in magic nucleus as compared with their behaviour, described by pure model of cores, has been considered. The change results in fragmentation of monoparticle levels, which is the main effect, and in the necessity to use new basis as compared with the shell one, corresponding to inoculative quasiparticles. When formulas have been devived concrete type of mass operator M(epsilon) is not used
CFD to modeling molten core behavior simultaneously with chemical phenomena
International Nuclear Information System (INIS)
Vladimir V Chudanov; Anna E Aksenova; Valerii A Pervichko
2005-01-01
Full text of publication follows: This paper deals with the basic features of a computing procedure, which can be used for modeling of destruction and melting of a core with subsequent corium retaining into the reactor vessel. The destruction and melting of core mean the account of the following phenomena: a melting, draining (moving of the melt through a porous layer of core debris), freezing with release of an energy, change of geometry, formation of the molten pool, whose convective intermixing and distribution influence on a mechanism of borders destruction. It is necessary to take into account that during of heating molten pool and development in it of convective fluxes a stratification of a multi-component melt on two layers of metal light and of oxide heavy components is observed. These layers are in interaction, they can exchange by the separate components as result of diffusion or oxidizing reactions. It can have an effect considerably on compositions, on a specific weight, and on properties of molten interacting phases, and on a structure of the molten stratified pool. In turn, the retaining of the formed molten masses in reactor vessel requires the solution of a matched heat exchange problem, namely, of a natural convection in a heat generating fluid in partially or completely molten corium and of heat exchange problem with taking into account of a melting of the reactor vessel. In addition, it is necessary to take into account phase segregation, caused by influence of local and of global natural convective flows and thermal lag of heated up boundaries. The mathematical model for simulation of the specified phenomena is based on the Navier-Stokes equations with variable properties together with the heat transfer equation. For modeling of a corium moving through a porous layer of core debris, the special computing algorithm to take into account density jump on interface between a melt and a porous layer of core debris is designed. The model was
EFEKTIVITAS STRATEGI PENGELOMPOKAN BERPASANGAN DALAM PEMBELAJARAN MATEMATIKA MODEL CORE
Directory of Open Access Journals (Sweden)
Endah Retnowati
2017-02-01
Full Text Available Abstrak: Penelitian ini bertujuan untuk menguji keefektifan pembelajaran CORE (Connect, Organize, Reflect, Extend pada pembelajaran geometri transformasi dengan strategi pengelompokan yang berbeda ditinjau dari kemampuan penalaran, prestasi, dan self efficacy. Penelitian ini merupakan penelitian eksperimen semu dengan populasi siswa kelas XI IPA SMA yang baru pertama kali mempelajari materi geometri transformasi. Sampel penelitian sebanyak dua kelas masing-masing terdiri atas 40 siswa. Siswa belajar dengan dikelompokkan secara berpasangan atau kelompok kecil. Data dikumpulkan dengan teknik tes dan nontes serta dianalisis dengan teknik statistik deskriptif dan inferensial (Manova. Hasil penelitian menunjukkan bahwa pembelajaran CORE strategi berpasangan maupun kelompok kecil efektif ditinjau dari Kriteria Ketuntasan Minimum kemampuan penalaran, prestasi dan self efficacy yang ditetapkan, tetapi tidak terdapat perbedaan yang signifikan di antara kedua strategi pengelompokan tersebut. Repeated measures analysis of variance menunjukkan bahwa kompleksitas materi pembelajaran memengaruhi prestasi belajar secara signifikan. Semakin kompleks materi pembelajaran, penggunaan strategi kelompok kecil lebih baik daripada berpasangan. Kata kunci: CORE, kemampuan penalaran, prestasi belajar, self efficacy THE EFFECTIVENESS OF DYAD STRATEGY DURING MATHEMATICS LEARNING BASED ON CORE MODEL Abstract: The purpose of this study is to test the effectiveness of an instruction, namely CORE (Connect, Organize, Reflect, Extend model, for learning geometry transformation in different grouping strategies (by dyads and small-group work, in terms of reasoning ability, achievement, and self-efficacy. This study was a quasi-experimental research with the entire population of science 11th graders who were novices in geometry transformation. The research samples were two classes which respectively consist of 40 students. Students learned all material either in dyads or small
Generalized model for k -core percolation and interdependent networks
Panduranga, Nagendra K.; Gao, Jianxi; Yuan, Xin; Stanley, H. Eugene; Havlin, Shlomo
2017-09-01
Cascading failures in complex systems have been studied extensively using two different models: k -core percolation and interdependent networks. We combine the two models into a general model, solve it analytically, and validate our theoretical results through extensive simulations. We also study the complete phase diagram of the percolation transition as we tune the average local k -core threshold and the coupling between networks. We find that the phase diagram of the combined processes is very rich and includes novel features that do not appear in the models studying each of the processes separately. For example, the phase diagram consists of first- and second-order transition regions separated by two tricritical lines that merge and enclose a two-stage transition region. In the two-stage transition, the size of the giant component undergoes a first-order jump at a certain occupation probability followed by a continuous second-order transition at a lower occupation probability. Furthermore, at certain fixed interdependencies, the percolation transition changes from first-order → second-order → two-stage → first-order as the k -core threshold is increased. The analytic equations describing the phase boundaries of the two-stage transition region are set up, and the critical exponents for each type of transition are derived analytically.
Astrocytic gap junctional networks suppress cellular damage in an in vitro model of ischemia
Energy Technology Data Exchange (ETDEWEB)
Shinotsuka, Takanori; Yasui, Masato; Nuriya, Mutsuo, E-mail: mnuriya@z2.keio.jp
2014-02-07
Highlights: • Astrocytes exhibit characteristic changes in [Ca{sup 2+}]{sub i} under OGD. • Astrocytic [Ca{sup 2+}]{sub i} increase is synchronized with a neuronal anoxic depolarization. • Gap junctional couplings protect neurons as well as astrocytes during OGD. - Abstract: Astrocytes play pivotal roles in both the physiology and the pathophysiology of the brain. They communicate with each other via extracellular messengers as well as through gap junctions, which may exacerbate or protect against pathological processes in the brain. However, their roles during the acute phase of ischemia and the underlying cellular mechanisms remain largely unknown. To address this issue, we imaged changes in the intracellular calcium concentration ([Ca{sup 2+}]{sub i}) in astrocytes in mouse cortical slices under oxygen/glucose deprivation (OGD) condition using two-photon microscopy. Under OGD, astrocytes showed [Ca{sup 2+}]{sub i} oscillations followed by larger and sustained [Ca{sup 2+}]{sub i} increases. While the pharmacological blockades of astrocytic receptors for glutamate and ATP had no effect, the inhibitions of gap junctional intercellular coupling between astrocytes significantly advanced the onset of the sustained [Ca{sup 2+}]{sub i} increase after OGD exposure. Interestingly, the simultaneous recording of the neuronal membrane potential revealed that the onset of the sustained [Ca{sup 2+}]{sub i} increase in astrocytes was synchronized with the appearance of neuronal anoxic depolarization. Furthermore, the blockade of gap junctional coupling resulted in a concurrent faster appearance of neuronal depolarizations, which remain synchronized with the sustained [Ca{sup 2+}]{sub i} increase in astrocytes. These results indicate that astrocytes delay the appearance of the pathological responses of astrocytes and neurons through their gap junction-mediated intercellular network under OGD. Thus, astrocytic gap junctional networks provide protection against tissue damage
Astrocytic gap junctional networks suppress cellular damage in an in vitro model of ischemia
International Nuclear Information System (INIS)
Shinotsuka, Takanori; Yasui, Masato; Nuriya, Mutsuo
2014-01-01
Highlights: • Astrocytes exhibit characteristic changes in [Ca 2+ ] i under OGD. • Astrocytic [Ca 2+ ] i increase is synchronized with a neuronal anoxic depolarization. • Gap junctional couplings protect neurons as well as astrocytes during OGD. - Abstract: Astrocytes play pivotal roles in both the physiology and the pathophysiology of the brain. They communicate with each other via extracellular messengers as well as through gap junctions, which may exacerbate or protect against pathological processes in the brain. However, their roles during the acute phase of ischemia and the underlying cellular mechanisms remain largely unknown. To address this issue, we imaged changes in the intracellular calcium concentration ([Ca 2+ ] i ) in astrocytes in mouse cortical slices under oxygen/glucose deprivation (OGD) condition using two-photon microscopy. Under OGD, astrocytes showed [Ca 2+ ] i oscillations followed by larger and sustained [Ca 2+ ] i increases. While the pharmacological blockades of astrocytic receptors for glutamate and ATP had no effect, the inhibitions of gap junctional intercellular coupling between astrocytes significantly advanced the onset of the sustained [Ca 2+ ] i increase after OGD exposure. Interestingly, the simultaneous recording of the neuronal membrane potential revealed that the onset of the sustained [Ca 2+ ] i increase in astrocytes was synchronized with the appearance of neuronal anoxic depolarization. Furthermore, the blockade of gap junctional coupling resulted in a concurrent faster appearance of neuronal depolarizations, which remain synchronized with the sustained [Ca 2+ ] i increase in astrocytes. These results indicate that astrocytes delay the appearance of the pathological responses of astrocytes and neurons through their gap junction-mediated intercellular network under OGD. Thus, astrocytic gap junctional networks provide protection against tissue damage during the acute phase of ischemia
On the thermodynamic properties of the generalized Gaussian core model
Directory of Open Access Journals (Sweden)
B.M.Mladek
2005-01-01
Full Text Available We present results of a systematic investigation of the properties of the generalized Gaussian core model of index n. The potential of this system interpolates via the index n between the potential of the Gaussian core model and the penetrable sphere system, thereby varying the steepness of the repulsion. We have used both conventional and self-consistent liquid state theories to calculate the structural and thermodynamic properties of the system; reference data are provided by computer simulations. The results indicate that the concept of self-consistency becomes indispensable to guarantee excellent agreement with simulation data; in particular, structural consistency (in our approach taken into account via the zero separation theorem is obviously a very important requirement. Simulation results for the dimensionless equation of state, β P / ρ, indicate that for an index-value of 4, a clustering transition, possibly into a structurally ordered phase might set in as the system is compressed.
Core-level satellites and outer core-level multiplet splitting in Mn model compounds
International Nuclear Information System (INIS)
Nelson, A. J.; Reynolds, John G.; Roos, Joseph W.
2000-01-01
We report a systematic study of the Mn 2p, 3s, and 3p core-level photoemission and satellite structures for Mn model compounds. Charge transfer from the ligand state to the 3d metal state is observed and is distinguished by prominent shake-up satellites. We also observe that the Mn 3s multiplet splitting becomes smaller as the Mn oxidation state increases, and that 3s-3d electron correlation reduces the branching ratio of the 7 S: 5 S states in the Mn 3s spectra. In addition, as the ligand electronegativity decreases, the spin-state purity is lost in the 3s spectra, as evidenced by peak broadening. Our results are best understood in terms of the configuration-interaction model including intrashell electron correlation, charge transfer, and final-state screening. (c) 2000 American Vacuum Society
Core flow inversion tested with numerical dynamo models
Rau, Steffen; Christensen, Ulrich; Jackson, Andrew; Wicht, Johannes
2000-05-01
We test inversion methods of geomagnetic secular variation data for the pattern of fluid flow near the surface of the core with synthetic data. These are taken from self-consistent 3-D models of convection-driven magnetohydrodynamic dynamos in rotating spherical shells, which generate dipole-dominated magnetic fields with an Earth-like morphology. We find that the frozen-flux approximation, which is fundamental to all inversion schemes, is satisfied to a fair degree in the models. In order to alleviate the non-uniqueness of the inversion, usually a priori conditions are imposed on the flow; for example, it is required to be purely toroidal or geostrophic. Either condition is nearly satisfied by our model flows near the outer surface. However, most of the surface velocity field lies in the nullspace of the inversion problem. Nonetheless, the a priori constraints reduce the nullspace, and by inverting the magnetic data with either one of them we recover a significant part of the flow. With the geostrophic condition the correlation coefficient between the inverted and the true velocity field can reach values of up to 0.65, depending on the choice of the damping parameter. The correlation is significant at the 95 per cent level for most spherical harmonic degrees up to l=26. However, it degrades substantially, even at long wavelengths, when we truncate the magnetic data sets to l currents, similar to those seen in core-flow models derived from geomagnetic data, occur in the equatorial region. However, the true flow does not contain this flow component. The results suggest that some meaningful information on the core-flow pattern can be retrieved from secular variation data, but also that the limited resolution of the magnetic core field could produce serious artefacts.
International Nuclear Information System (INIS)
Wang Chengxin; Yang Guowei; Liu Hongwu; Han Yonghao; Luo Jifeng; Gao Chunxiao; Zou Guangtian
2004-01-01
High-quality heterojunctions between p-type diamond single-crystalline films and highly oriented n-type ZnO films were fabricated by depositing the p-type diamond single-crystal films on the I o -type diamond single crystal using a hot filament chemical vapor deposition, and later growing a highly oriented n-type ZnO film on the p-type diamond single-crystal film by magnetron sputtering. Interestingly, anomalously high ideality factors (n>>2.0) in the prepared ZnO/diamond p-n junction diode in the interim bias voltage range were measured. For this, detailed electronic characterizations of the fabricated p-n junction were conducted, and a theoretical model was proposed to clarify the much higher ideality factors of the special heterojunction diode
Quasi-exactly solvable relativistic soft-core Coulomb models
Energy Technology Data Exchange (ETDEWEB)
Agboola, Davids, E-mail: davagboola@gmail.com; Zhang, Yao-Zhong, E-mail: yzz@maths.uq.edu.au
2012-09-15
By considering a unified treatment, we present quasi exact polynomial solutions to both the Klein-Gordon and Dirac equations with the family of soft-core Coulomb potentials V{sub q}(r)=-Z/(r{sup q}+{beta}{sup q}){sup 1/q}, Z>0, {beta}>0, q{>=}1. We consider cases q=1 and q=2 and show that both cases are reducible to the same basic ordinary differential equation. A systematic and closed form solution to the basic equation is obtained using the Bethe ansatz method. For each case, the expressions for the energies and the allowed parameters are obtained analytically and the wavefunctions are derived in terms of the roots of a set of Bethe ansatz equations. - Highlights: Black-Right-Pointing-Pointer The relativistic bound-state solutions of the soft-core Coulomb models. Black-Right-Pointing-Pointer Quasi-exact treatments of the Dirac and Klein-Gordon equations for the soft-core Coulomb models. Black-Right-Pointing-Pointer Solutions obtained in terms of the roots to the Bethe ansatz equations. Black-Right-Pointing-Pointer The hidden Lie algebraic structure discussed for the models. Black-Right-Pointing-Pointer Results useful in describing mesonic atoms and interaction of intense laser fields with atom.
Numerical simulation of the self-pumped long Josephson junction using a modified sine-Gordon model
DEFF Research Database (Denmark)
Sobolev, A.; Pankratov, A.; Mygind, Jesper
2006-01-01
We have numerically investigated the dynamics of a long Josephson junction (flux-flow oscillator) biased by a DC current in the presence of magnetic field. The study is performed in the frame of the modified sine-Gordon model, which includes the surface losses, RC-load at both FFO ends and the self-pumping...... effect. In our model the dumping parameter depends both on the spatial coordinate and the amplitude of the AC voltage. In order to find the DC FFO voltage the damping parameter has to be calculated by successive approximations and time integration of the perturbed sine-Gordon equation. The modified model...
Cycle length maximization in PWRs using empirical core models
International Nuclear Information System (INIS)
Okafor, K.C.; Aldemir, T.
1987-01-01
The problem of maximizing cycle length in nuclear reactors through optimal fuel and poison management has been addressed by many investigators. An often-used neutronic modeling technique is to find correlations between the state and control variables to describe the response of the core to changes in the control variables. In this study, a set of linear correlations, generated by two-dimensional diffusion-depletion calculations, is used to find the enrichment distribution that maximizes cycle length for the initial core of a pressurized water reactor (PWR). These correlations (a) incorporate the effect of composition changes in all the control zones on a given fuel assembly and (b) are valid for a given range of control variables. The advantage of using such correlations is that the cycle length maximization problem can be reduced to a linear programming problem
Ab Initio Symmetry-Adapted No-Core Shell Model
International Nuclear Information System (INIS)
Draayer, J P; Dytrych, T; Launey, K D
2011-01-01
A multi-shell extension of the Elliott SU(3) model, the SU(3) symmetry-adapted version of the no-core shell model (SA-NCSM), is described. The significance of this SA-NCSM emerges from the physical relevance of its SU(3)-coupled basis, which – while it naturally manages center-of-mass spuriosity – provides a microscopic description of nuclei in terms of mixed shape configurations. Since typically configurations of maximum spatial deformation dominate, only a small part of the model space suffices to reproduce the low-energy nuclear dynamics and hence, offers an effective symmetry-guided framework for winnowing of model space. This is based on our recent findings of low-spin and high-deformation dominance in realistic NCSM results and, in turn, holds promise to significantly enhance the reach of ab initio shell models.
Modelling of the Molten Core Concrete Interaction (MCCI)
International Nuclear Information System (INIS)
Guillaume, M.
2008-01-01
Severe accidents of nuclear power plants are very unlikely to occur, yet it is necessary to be able to predict the evolution of the accident. In some situations, heat generation due to the disintegration of fission products could lead to the melting of the core. If the molten core falls on the floor of the building, it would provoke the melting of the concrete floor. The objective of the studies is to calculate the melting rate of the concrete floor. The work presented in this report is in the continuity of the segregation phase model of Seiler and Froment. It is based on the results of the ARTEMIS experiments. Firstly, we have developed a new model to simulate the transfers within the interfacial area. The new model explains how heat is transmitted to concrete: by conduction, convection and latent heat generation. Secondly, we have modified the coupled modelling of the pool and the interfacial area. We have developed two new models: the first one is the 'liquidus model', whose main hypothesis is that there is no resistance to solute transfer between the pool and the interfacial area. The second one is 'the thermal resistance model', whose main hypothesis is that there is no solute transfer and no dissolution of the interfacial area. The second model is able to predict the evolution of the pool temperature and the melting rate in the tests 3 and 4, with the condition that the obstruction time of the interfacial area is about 10 5 s. The model is not able to explain precisely the origin of this value. The liquidus model is able to predict correctly the evolution of the pool temperature and the melting rate in the tests 2 and 6. (author) [fr
Directory of Open Access Journals (Sweden)
Róbert Rácz
2017-12-01
Full Text Available We have recently developed a novel in vitro model using HAT-7 rat ameloblast cells to functionally study epithelial ion transport during amelogenesis. Our present aims were to identify key transporters of bicarbonate in HAT-7 cells and also to examine the effects of fluoride exposure on vectorial bicarbonate transport, cell viability, and the development of transepithelial resistance. To obtain monolayers, the HAT-7 cells were cultured on Transwell permeable filters. We monitored transepithelial resistance (TER as an indicator of tight junction formation and polarization. We evaluated intracellular pH changes by microfluorometry using the fluorescent indicator BCECF. Activities of ion transporters were tested by withdrawal of various ions from the bathing medium, by using transporter specific inhibitors, and by activation of transporters with forskolin and ATP. Cell survival was estimated by alamarBlue assay. Changes in gene expression were monitored by qPCR. We identified the activity of several ion transporters, NBCe1, NHE1, NKCC1, and AE2, which are involved in intracellular pH regulation and vectorial bicarbonate and chloride transport. Bicarbonate secretion by HAT-7 cells was not affected by acute fluoride exposure over a wide range of concentrations. However, tight-junction formation was inhibited by 1 mM fluoride, a concentration which did not substantially reduce cell viability, suggesting an effect of fluoride on paracellular permeability and tight-junction formation. Cell viability was only reduced by prolonged exposure to fluoride concentrations greater than 1 mM. In conclusion, cultured HAT-7 cells are functionally polarized and are able to transport bicarbonate ions from the basolateral to the apical fluid spaces. Exposure to 1 mM fluoride has little effect on bicarbonate secretion or cell viability but delays tight-junction formation, suggesting a novel mechanism that may contribute to dental fluorosis.
Design of a Data Distribution Core Model for Seafloor Observatories in East China Sea
Chen, H.; Qin, R.; Xu, H.
2017-12-01
High loadings of nutrients and pollutants from agriculture, industries and city waste waters are carried by Changjiang (Yangtze) River and transformed into the foodweb in the river freshwater plume. Understanding these transport and transformation processes is essential for the ecosystem protection, fisheries resources management, seafood safety and human health. As Xiaoqushan Seafloor Observatory and Zhujiajian Seafloor Observatory built in East China Sea, it is an opportunity and a new way for the research of Changjiang River plume. Data collected by seafloor observatory should be accessed conveniently by end users in real time or near real time, which can make it play a better role. Therefore, data distribution is one of major issues for seafloor observatory characterized by long term, real time, high resolution and continuous observation. This study describes a Data Distribution core Model for Seafloor Observatories in East China Sea (ESDDM) containing Data Acquisition Module (DAM), Data Interpretation Module (DIM), Data Transmission Module (DTM) and Data Storage Module (DTM), which enables acquiring, interpreting, transmitting and storing various types of data in real time. A Data Distribution Model Makeup Language (DDML) based on XML is designed to enhance the expansibility and flexibility of the system implemented by ESDDM. Network sniffer is used to acquire data by IP address and port number in DAM promising to release the operating pressure of junction boxes. Data interface, core data processing plugins and common libraries consist of DIM helping it interpret data in a hot swapping way. DTM is an external module in ESDDM transmitting designated raw data packets to Secondary Receiver Terminal. The technology of database connection pool used in DSM facilitates the efficiency of large volumes of continuous data storage. Given a successful scenario in Zhujiajian Seafloor Observatory, the protosystem based on ESDDM running up to 1500h provides a reference for
Ye, P; Yu, H; Simonian, M; Hunter, N
2014-04-01
Previously we demonstrated uniformly strong expression of CD24 in the epithelial attachment to the tooth and in the migrating epithelium of the periodontitis lesion. Titers of serum antibodies autoreactive with CD24 peptide correlated with reduced severity of periodontal disease. Ligation of CD24 expressed by oral epithelial cells induced formation of tight junctions that limited paracellular diffusion. In this study, we aimed to reveal that the lack of uniform expression of tight junction components in the pocket epithelium of periodontitis lesions is likely to contribute to increased paracellular permeability to bacterial products. This is proposed as a potential driver of the immunopathology of periodontitis. An epithelial culture model with close correspondence for expression patterns for tight junction components in periodontal epithelia was used. Immunohistochemical staining and confocal laser scanning microscopy were used to analyse patterns of expression of gingival epithelial tight junction components. The minimally inflamed gingival attachment was characterized by uniformly strong staining at cell contacts for the tight junction components zona occludens-1, zona occludens-2, occludin, junction adhesion molecule-A, claudin-4 and claudin-15. In contrast, the pocket epithelium of the periodontal lesion showed scattered, uneven staining for these components. This pattern correlated closely with that of unstimulated oral epithelial cells in culture. Following ligation of CD24 expressed by these cells, the pattern of tight junction component expression of the minimally inflamed gingival attachment developed rapidly. There was evidence for non-uniform and focal expression only of tight junction components in the pocket epithelium. In the cell-culture model, ligation of CD24 induced a tight junction expression profile equivalent to that observed for the minimally inflamed gingival attachment. Ligation of CD24 expressed by gingival epithelial cells by lectin
Kok, Jacobus B.W.; van der Wal, S.
1996-01-01
The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction
Evaluation of core modeling effect on transients for multi-flow zone design of SFR
International Nuclear Information System (INIS)
Shin, Andong; Choi, Yong Won
2016-01-01
SFR core is composed of different types of assemblies including fuel driver, reflector, blanket, control, safety drivers and other drivers. Modeling of different types of assemblies is inevitable in general. But modeling of core flow zones of with different channels needs a lot of effort and could be a challenge for system code modeling due to its limitation on the number of modeling components. In this study, core modeling effect on SFR transient was investigated with flow-zone model and averaged inner core channel model to improve modeling efficiency and validation of simplified core model for EBR-II loss of flow transient case with the modified TRACE code for SFRs. Core modeling effect on the loss flow transient was analyzed with flow-zoned channel model, single averaged inner core model and highest flow channel with averaged inner core channel model for EBR-II SHRT-17 test core. Case study showed that estimations of transient pump and channel flow as well as channel outlet temperatures were similar for all cases macroscopically. Comparing the result of the base case (flow-zone channel inner core model) and the case 2 (highest flow channel considered averaged inner core channel model), flow and channel outlet temperature response were closer than the case1 (single averaged inner core model)
Evaluation of core modeling effect on transients for multi-flow zone design of SFR
Energy Technology Data Exchange (ETDEWEB)
Shin, Andong; Choi, Yong Won [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2016-10-15
SFR core is composed of different types of assemblies including fuel driver, reflector, blanket, control, safety drivers and other drivers. Modeling of different types of assemblies is inevitable in general. But modeling of core flow zones of with different channels needs a lot of effort and could be a challenge for system code modeling due to its limitation on the number of modeling components. In this study, core modeling effect on SFR transient was investigated with flow-zone model and averaged inner core channel model to improve modeling efficiency and validation of simplified core model for EBR-II loss of flow transient case with the modified TRACE code for SFRs. Core modeling effect on the loss flow transient was analyzed with flow-zoned channel model, single averaged inner core model and highest flow channel with averaged inner core channel model for EBR-II SHRT-17 test core. Case study showed that estimations of transient pump and channel flow as well as channel outlet temperatures were similar for all cases macroscopically. Comparing the result of the base case (flow-zone channel inner core model) and the case 2 (highest flow channel considered averaged inner core channel model), flow and channel outlet temperature response were closer than the case1 (single averaged inner core model)
Progress and problems in modelling HTR core dynamics
International Nuclear Information System (INIS)
Scherer, W.; Gerwin, H.
1991-01-01
In recent years greater effort has been made to establish theoretical models for HTR core dynamics. At KFA Juelich the TINTE (TIme dependent Neutronics and TEmperatures) code system has been developed, which is able to model the primary circuit of an HTR plant using modern numerical techniques and taking into account the mutual interference of the relevant physical variables. The HTR core is treated in 2-D R-Z geometry for both nucleonics and thermo-fluid-dynamics. 2-energy-group diffusion theory is used in the nuclear part including 6 groups of delayed neutron precursors and 14 groups of decay heat producers. Local and non-local heat sources are incorporated, thus simulating gamma ray transport. The thermo-fluid-dynamics module accounts for heterogeneity effects due to the pebble bed structure. Pipes and other components of the primary loop are modelled in 1-D geometry. Forced convection may be treated as well as natural convection in case of blower breakdown accidents. Validation of TINTE has started using the results of a comprehensive experimental program that has been performed at the Arbeitsgemeinschaft Versuchsreaktor GmbH (AVR) high temperature pebble bed reactor at Juelich. In the frame of this program power transients were initiated by varying the helium blower rotational speed or by moving the control rods. In most cases a good accordance between experiment and calculation was found. Problems in modelling the special AVR reactor geometry in two dimensions are described and suggestions for overcoming the uncertainties of experimentally determined control rod reactivities are given. The influence of different polynomial expansions of xenon cross sections to long term transients is discussed together with effects of burnup during that time. Up to now the TINTE code has proven its general applicability to operational core transients of HTR. The effects of water ingress on reactivity, fuel element corrosion and cooling gas properties are now being
Modelling the carbonation of cementitious matrixes by means of the unreacted-core model, UR-CORE
International Nuclear Information System (INIS)
Castellote, M.; Andrade, C.
2008-01-01
This paper presents a model for the carbonation of cementitious matrixes (UR-CORE). The model is based on the principles of the 'unreacted-core' systems, typical of chemical engineering processes, in which the reacted product remains in the solid as a layer of inert ash, adapted for the specific case of carbonation. Development of the model has been undertaken in three steps: 1) Establishment of the controlling step in the global carbonation rate, by using data of fractional conversion of different phases of the cementitious matrixes, obtained by the authors through neutron diffraction data experiments, and reported in [M. Castellote, C. Andrade, X. Turrillas, J. Campo, G. Cuello, Accelerated carbonation of cement pastes in situ monitored by neutron diffraction, Cem. Concr. Res. (2008), doi:10.1016/j.cemconres.2008.07.002]. 2) Then, the model has been adapted and applied to the cementitious materials using different concentrations of CO 2 , with the introduction of the needed assumptions and factors. 3) Finally, the model has been validated with laboratory data at different concentrations (taken from literature) and for long term natural exposure of concretes. As a result, the model seems to be reliable enough to be applied to cementitious materials, being able to extrapolate the results from accelerated tests in any conditions to predict the rate of carbonation in natural exposure, being restricted, at present stage, to conditions with a constant relative humidity
The Effects of Earth's Outer Core's Viscosity on Geodynamo Models
Dong, C.; Jiao, L.; Zhang, H.
2017-12-01
Geodynamo process is controlled by mathematic equations and input parameters. To study effects of parameters on geodynamo system, MoSST model has been used to simulate geodynamo outputs under different outer core's viscosity ν. With spanning ν for nearly three orders when other parameters fixed, we studied the variation of each physical field and its typical length scale. We find that variation of ν affects the velocity field intensely. The magnetic field almost decreases monotonically with increasing of ν, while the variation is no larger than 30%. The temperature perturbation increases monotonically with ν, but by a very small magnitude (6%). The averaged velocity field (u) of the liquid core increases with ν as a simple fitted scaling relation: u∝ν0.49. The phenomenon that u increases with ν is essentially that increasing of ν breaks the Taylor-Proudman constraint and drops the critical Rayleigh number, and thus u increases under the same thermal driving force. Forces balance is analyzed and balance mode shifts with variation of ν. When compared with former studies of scaling laws, this study supports the conclusion that in a certain parameter range, the magnetic field strength doesn't vary much with the viscosity, but opposes to the assumption that the velocity field has nothing to do with the outer core viscosity.
A Global Model for Circumgalactic and Cluster-core Precipitation
Voit, G. Mark; Meece, Greg; Li, Yuan; O'Shea, Brian W.; Bryan, Greg L.; Donahue, Megan
2017-08-01
We provide an analytic framework for interpreting observations of multiphase circumgalactic gas that is heavily informed by recent numerical simulations of thermal instability and precipitation in cool-core galaxy clusters. We start by considering the local conditions required for the formation of multiphase gas via two different modes: (1) uplift of ambient gas by galactic outflows, and (2) condensation in a stratified stationary medium in which thermal balance is explicitly maintained. Analytic exploration of these two modes provides insights into the relationships between the local ratio of the cooling and freefall timescales (I.e., {t}{cool}/{t}{ff}), the large-scale gradient of specific entropy, and the development of precipitation and multiphase media in circumgalactic gas. We then use these analytic findings to interpret recent simulations of circumgalactic gas in which global thermal balance is maintained. We show that long-lasting configurations of gas with 5≲ \\min ({t}{cool}/{t}{ff})≲ 20 and radial entropy profiles similar to observations of cool cores in galaxy clusters are a natural outcome of precipitation-regulated feedback. We conclude with some observational predictions that follow from these models. This work focuses primarily on precipitation and AGN feedback in galaxy-cluster cores, because that is where the observations of multiphase gas around galaxies are most complete. However, many of the physical principles that govern condensation in those environments apply to circumgalactic gas around galaxies of all masses.
Modeling and Simulation of a Dual-Junction CIGS Solar Cell Using Silvaco ATLAS
2012-12-01
stage process, thermal evaporation, electrodeposition , deposition temperatures, content, stoichiometry and composition range on CIGS, inducing in...mesh. This location can be any specific region, and for the purposes of this thesis, a pair of cathode , and anode electrodes was assigned in the two...ATLASTM structure file for the dual-junction CIGS cell. In order to extract an overall I–V curve, two sets of anodes and cathodes were placed on the
Gas dynamics models for an oscillating gaseous core fission reactor
Energy Technology Data Exchange (ETDEWEB)
Kuijper, J.C.; Dam, H. van; Hoogenboom, J.E. (Interuniversitair Reactor Inst., Delft (Netherlands))
1991-01-01
Two one-dimensional models are developed for the investigation of the gas dynamical behaviour of the fuel gas in a cylindrical gaseous core fission reactor. By numerical and analytical calculations, it is shown that, for the case where a direct energy extraction mechanism (such as magneto-hydrodynamics (MHD)) is not present, increasing density oscillations occur in the gas. Also an estimate is made of the attainable direct energy conversion efficiency, for the case where a direct energy extraction mechanism is present. (author).
Shell model in-water frequencies of the core barrel
International Nuclear Information System (INIS)
Takeuchi, K.; De Santo, D.F.
1980-01-01
Natural frequencies of a 1/24th-scale core barrel/vessel model in air and in water are measured by determining frequency responses to applied forces. The measured data are analyzed by the use of the one-dimensional fluid-structure computer code, MULTIFLEX, developed to calculate the hydraulic force. The fluid-structure interaction in the downcomer annulus is computed with a one-dimensional network model formed to be equivalent to two-dimensional fluid-structure interaction. The structural model incorporated in MULTIFLEX is substantially simpler than that necessary for structural analyses. Proposed for computation of structural dynamics is the projector method than can deal with the beam mode by modal analysis and the other shell modes by a direct integration method. Computed in-air and in-water frequencies agree fairly well with the experimental data, verifying the above MULTIFLEX technique
Computational modeling for hexcan failure under core distruptive accidental conditions
Energy Technology Data Exchange (ETDEWEB)
Sawada, T.; Ninokata, H.; Shimizu, A. [Tokyo Institute of Technology (Japan)
1995-09-01
This paper describes the development of computational modeling for hexcan wall failures under core disruptive accident conditions of fast breeder reactors. A series of out-of-pile experiments named SIMBATH has been analyzed by using the SIMMER-II code. The SIMBATH experiments were performed at KfK in Germany. The experiments used a thermite mixture to simulate fuel. The test geometry of SIMBATH ranged from single pin to 37-pin bundles. In this study, phenomena of hexcan wall failure found in a SIMBATH test were analyzed by SIMMER-II. Although the original model of SIMMER-II did not calculate any hexcan failure, several simple modifications made it possible to reproduce the hexcan wall melt-through observed in the experiment. In this paper the modifications and their significance are discussed for further modeling improvements.
A nodal model for the simulation of a PWR core
International Nuclear Information System (INIS)
Souza Pinto, R. de.
1981-06-01
A computer program FORTRAN language was developed to simulate the neutronic and thermal-hydraulic transient behaviour of a PWR reactor core. The reator power is calculated using a point kinectics model with six groups of delayed neutron precursors. The fission product decay heat was considered assuming three effective decay heat groups. A nodal model was employed for the treatment of heat transfer in the fuel rod, with integration of the heat equation by the lumped parameter technique. Axial conduction was neglected. A single-channel nodal model was developed for the thermo-hydrodynamic simulation using mass and energy conservation equations for the control volumes. The effect of the axial pressure variation was neglected. The computer program was tested, with good results, through the simulation of the transient behaviour of postulated accidents in a typical PWR. (Author) [pt
Core competency model for the family planning public health nurse.
Hewitt, Caroline M; Roye, Carol; Gebbie, Kristine M
2014-01-01
A core competency model for family planning public health nurses has been developed, using a three stage Delphi Method with an expert panel of 40 family planning senior administrators, community/public health nursing faculty and seasoned family planning public health nurses. The initial survey was developed from the 2011 Title X Family Planning program priorities. The 32-item survey was distributed electronically via SurveyMonkey(®). Panelist attrition was low, and participation robust resulting in the final 28-item model, suggesting that the Delphi Method was a successful technique through which to achieve consensus. Competencies with at least 75% consensus were included in the model and those competencies were primarily related to education/counseling and administration of medications and contraceptives. The competencies identified have implications for education/training, certification and workplace performance. © 2014 Wiley Periodicals, Inc.
Feasibility analysis of real-time physical modeling using WaveCore processor technology on FPGA
Verstraelen, Martinus Johannes Wilhelmina; Pfeifle, Florian; Bader, Rolf
2015-01-01
WaveCore is a scalable many-core processor technology. This technology is specifically developed and optimized for real-time acoustical modeling applications. The programmable WaveCore soft-core processor is silicon-technology independent and hence can be targeted to ASIC or FPGA technologies. The
A dynamic model for helium core heat exchangers
International Nuclear Information System (INIS)
Schiesser, W.E.; Shih, H.J.; Hartozog, D.G.; Herron, D.M.; Nahmias, D.; Stuber, W.G.; Hindmarsh, A.C.
1990-04-01
To meet the helium (He) requirements of the superconducting supercollider (SSC), the cryogenic plants must be able to respond to time-varying loads. Thus the design and simulation of the cryogenic plants requires dynamic models of their principal components, and in particular, the core heat exchangers. In this paper, we detail the derivation and computer implementation of a model for core heat exchangers consisting of three partial differential equations (PDES) for each fluid stream (the continuity, energy and momentum balances for the He), and one PDE for each parting sheet (the energy balance for the parting sheet metal); the PDEs have time and axial position along the exchanger as independent variables. The computer code can accommodate any number of fluid streams and parting sheets in an adiabatic group. Features of the code include: rigorous or approximate thermodynamic properties for He, upwind and downwind approximation of the PDE spatial derivatives, and sparse matrix time integration. The outputs from the code include the time-dependent axial profiles of the fluid He mass flux, density, pressure, temperature, internal energy and enthalpy. The code is written in transportable Fortran 77, and can therefore be executed on essentially any computer
A dynamic model for helium core heat exchangers
International Nuclear Information System (INIS)
Schiesser, W.E.; Shih, H.J.; Hartzog, D.G.; Herron, D.M.; Nahmias, D.; Stuber, W.G.; Hindmarsh, A.C.
1990-01-01
To meet the helium (He) requirements of the superconducting supercollider (SSC), the cryogenic plants must be able to respond to time-varying loads. Thus the design and simulation of the cryogenic plants requires dynamic models of their principal components, and in particular, the core heat exchangers. In this paper, we detail the derivation and computer implementation of a model for core heat exchangers consisting of three partial differential equations (PDEs) for each fluid stream (the continuity, energy and momentum balances for the He), and one PDE for each parting sheet (the energy balance for the parting sheet metal); the PDEs have time and axial position along the exchanger as independent variables. The computer code can accommodate any number of fluid streams and parting sheets in an adiabatic group. Features of the code include: rigorous or approximate thermodynamic properties for He, upwind and downwind approximation of the PDE spatial derivatives, and sparse matrix time integration. The outputs from the code include the time-dependent axial profiles of the fluid He mass flux, density, pressure, temperature, internal energy and enthalpy. The code is written in transportable Fortran 77, and can therefore be executed on essentially any computer. 10 refs., 10 figs
Recent Developments in No-Core Shell-Model Calculations
International Nuclear Information System (INIS)
Navratil, P.; Quaglioni, S.; Stetcu, I.; Barrett, B.R.
2009-01-01
We present an overview of recent results and developments of the no-core shell model (NCSM), an ab initio approach to the nuclear many-body problem for light nuclei. In this aproach, we start from realistic two-nucleon or two- plus three-nucleon interactions. Many-body calculations are performed using a finite harmonic-oscillator (HO) basis. To facilitate convergence for realistic inter-nucleon interactions that generate strong short-range correlations, we derive effective interactions by unitary transformations that are tailored to the HO basis truncation. For soft realistic interactions this might not be necessary. If that is the case, the NCSM calculations are variational. In either case, the ab initio NCSM preserves translational invariance of the nuclear many-body problem. In this review, we, in particular, highlight results obtained with the chiral two- plus three-nucleon interactions. We discuss efforts to extend the applicability of the NCSM to heavier nuclei and larger model spaces using importance-truncation schemes and/or use of effective interactions with a core. We outline an extension of the ab initio NCSM to the description of nuclear reactions by the resonating group method technique. A future direction of the approach, the ab initio NCSM with continuum, which will provide a complete description of nuclei as open systems with coupling of bound and continuum states is given in the concluding part of the review.
Recent Developments in No-Core Shell-Model Calculations
Energy Technology Data Exchange (ETDEWEB)
Navratil, P; Quaglioni, S; Stetcu, I; Barrett, B R
2009-03-20
We present an overview of recent results and developments of the no-core shell model (NCSM), an ab initio approach to the nuclear many-body problem for light nuclei. In this aproach, we start from realistic two-nucleon or two- plus three-nucleon interactions. Many-body calculations are performed using a finite harmonic-oscillator (HO) basis. To facilitate convergence for realistic inter-nucleon interactions that generate strong short-range correlations, we derive effective interactions by unitary transformations that are tailored to the HO basis truncation. For soft realistic interactions this might not be necessary. If that is the case, the NCSM calculations are variational. In either case, the ab initio NCSM preserves translational invariance of the nuclear many-body problem. In this review, we, in particular, highlight results obtained with the chiral two- plus three-nucleon interactions. We discuss efforts to extend the applicability of the NCSM to heavier nuclei and larger model spaces using importance-truncation schemes and/or use of effective interactions with a core. We outline an extension of the ab initio NCSM to the description of nuclear reactions by the resonating group method technique. A future direction of the approach, the ab initio NCSM with continuum, which will provide a complete description of nuclei as open systems with coupling of bound and continuum states is given in the concluding part of the review.
A numerical strategy for modelling rotating stall in core compressors
Vahdati, M.
2007-03-01
The paper will focus on one specific core-compressor instability, rotating stall, because of the pressing industrial need to improve current design methods. The determination of the blade response during rotating stall is a difficult problem for which there is no reliable procedure. During rotating stall, the blades encounter the stall cells and the excitation depends on the number, size, exact shape and rotational speed of these cells. The long-term aim is to minimize the forced response due to rotating stall excitation by avoiding potential matches between the vibration modes and the rotating stall pattern characteristics. Accurate numerical simulations of core-compressor rotating stall phenomena require the modelling of a large number of bladerows using grids containing several tens of millions of points. The time-accurate unsteady-flow computations may need to be run for several engine revolutions for rotating stall to get initiated and many more before it is fully developed. The difficulty in rotating stall initiation arises from a lack of representation of the triggering disturbances which are inherently present in aeroengines. Since the numerical model represents a symmetric assembly, the only random mechanism for rotating stall initiation is provided by numerical round-off errors. In this work, rotating stall is initiated by introducing a small amount of geometric mistuning to the rotor blades. Another major obstacle in modelling flows near stall is the specification of appropriate upstream and downstream boundary conditions. Obtaining reliable boundary conditions for such flows can be very difficult. In the present study, the low-pressure compression (LPC) domain is placed upstream of the core compressor. With such an approach, only far field atmospheric boundary conditions are specified which are obtained from aircraft speed and altitude. A chocked variable-area nozzle, placed after the last compressor bladerow in the model, is used to impose boundary
BR2 reactor core steady state transient modeling
International Nuclear Information System (INIS)
Makarenko, A.; Petrova, T.
2000-01-01
A coupled neutronics/hydraulics/heat-conduction model of the BR2 reactor core is under development at SCK-CEN. The neutron transport phenomenon has been implemented as steady state and time dependent nodal diffusion. The non-linear heat conduction equation in-side fuel elements is solved with a time dependent finite element method. To allow coupling between functional modules and to simulate subcooled regimes, a simple single-phase hydraulics has been introduced, while the two-phase hydraulics is under development. Multiple tests, general benchmark cases as well as calculation/experiment comparisons demonstrated a good accuracy of both neutronic and thermal hydraulic models, numerical reliability and full code portability. A refinement methodology has been developed and tested for better neutronic representation in hexagonal geometry. Much effort is still needed to complete the development of an extended cross section library with kinetic data and two-phase flow representation. (author)
Development of CFD model for augmented core tripropellant rocket engine
Jones, Kenneth M.
1994-10-01
The Space Shuttle era has made major advances in technology and vehicle design to the point that the concept of a single-stage-to-orbit (SSTO) vehicle appears more feasible. NASA presently is conducting studies into the feasibility of certain advanced concept rocket engines that could be utilized in a SSTO vehicle. One such concept is a tripropellant system which burns kerosene and hydrogen initially and at altitude switches to hydrogen. This system will attain a larger mass fraction because LOX-kerosene engines have a greater average propellant density and greater thrust-to-weight ratio. This report describes the investigation to model the tripropellant augmented core engine. The physical aspects of the engine, the CFD code employed, and results of the numerical model for a single modular thruster are discussed.
Multigroup models of the convective epoch in core collapse supernovae
International Nuclear Information System (INIS)
Swesty, F Douglas; Myra, Eric S
2005-01-01
Understanding the explosion mechanism of core collapse supernovae is a problem that has plagued nuclear astrophysicists since the first computational models of this phenomenon were carried out in the 1960s. Our current theories of this violent phenomenon center around multi-dimensional effects involving radiation-hydrodynamic flows of hot, dense matter and neutrinos. Modeling these multi-dimensional radiative flows presents a computational challenge that will continue to stress high-performance computing beyond the teraflops to the petaflop level. In this paper we describe a few of the scientific discoveries that we have made via terascale computational simulations of supernovae under the auspices of the SciDAC-funded Terascale Supernova Initiative
Core surface flow modelling from high-resolution secular variation
DEFF Research Database (Denmark)
Holme, R.; Olsen, Nils
2006-01-01
-flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....
Systems Modeling for Crew Core Body Temperature Prediction Postlanding
Cross, Cynthia; Ochoa, Dustin
2010-01-01
The Orion Crew Exploration Vehicle, NASA s latest crewed spacecraft project, presents many challenges to its designers including ensuring crew survivability during nominal and off nominal landing conditions. With a nominal water landing planned off the coast of San Clemente, California, off nominal water landings could range from the far North Atlantic Ocean to the middle of the equatorial Pacific Ocean. For all of these conditions, the vehicle must provide sufficient life support resources to ensure that the crew member s core body temperatures are maintained at a safe level prior to crew rescue. This paper will examine the natural environments, environments created inside the cabin and constraints associated with post landing operations that affect the temperature of the crew member. Models of the capsule and the crew members are examined and analysis results are compared to the requirement for safe human exposure. Further, recommendations for updated modeling techniques and operational limits are included.
Baryon-Baryon Interactions ---Nijmegen Extended-Soft-Core Models---
Rijken, T. A.; Nagels, M. M.; Yamamoto, Y.
We review the Nijmegen extended-soft-core (ESC) models for the baryon-baryon (BB) interactions of the SU(3) flavor-octet of baryons (N, Lambda, Sigma, and Xi). The interactions are basically studied from the meson-exchange point of view, in the spirit of the Yukawa-approach to the nuclear force problem [H. Yukawa, ``On the interaction of Elementary Particles I'', Proceedings of the Physico-Mathematical Society of Japan 17 (1935), 48], using generalized soft-core Yukawa-functions. These interactions are supplemented with (i) multiple-gluon-exchange, and (ii) structural effects due to the quark-core of the baryons. We present in some detail the most recent extended-soft-core model, henceforth referred to as ESC08, which is the most complete, sophisticated, and successful interaction-model. Furthermore, we discuss briefly its predecessor the ESC04-model [Th. A. Rijken and Y. Yamamoto, Phys. Rev. C 73 (2006), 044007; Th. A. Rijken and Y. Yamamoto, Ph ys. Rev. C 73 (2006), 044008; Th. A. Rijken and Y. Yamamoto, nucl-th/0608074]. For the soft-core one-boson-exchange (OBE) models we refer to the literature [Th. A. Rijken, in Proceedings of the International Conference on Few-Body Problems in Nuclear and Particle Physics, Quebec, 1974, ed. R. J. Slobodrian, B. Cuec and R. Ramavataram (Presses Universitè Laval, Quebec, 1975), p. 136; Th. A. Rijken, Ph. D. thesis, University of Nijmegen, 1975; M. M. Nagels, Th. A. Rijken and J. J. de Swart, Phys. Rev. D 17 (1978), 768; P. M. M. Maessen, Th. A. Rijken and J. J. de Swart, Phys. Rev. C 40 (1989), 2226; Th. A. Rijken, V. G. J. Stoks and Y. Yamamoto, Phys. Rev. C 59 (1999), 21; V. G. J. Stoks and Th. A. Rijken, Phys. Rev. C 59 (1999), 3009]. All ingredients of these latter models are also part of ESC08, and so a description of ESC08 comprises all models so far in principle. The extended-soft-core (ESC) interactions consist of local- and non-local-potentials due to (i) one-boson-exchanges (OBE), which are the members of nonets of
Applications for coupled core neutronics and thermal-hydraulic models
International Nuclear Information System (INIS)
Eller, J.
1996-01-01
The unprecedented increases in computing capacity that have occurred during the last decade have affected our sciences, and thus our lives, to an extent that is difficult to overstate. All indications are that this trend will continue for years to come. Nuclear reactor systems analysis is one of many areas of engineering that has changed dramatically as a result of this evolution. Our ability to model the various mechanical and physical systems in greater and greater detail has allowed significant improvements in operational efficiency in spite of increasing regulatory requirements. Many of these efficiencies result from the use of more complex and geometrically detailed computer modeling, which is used to justify a reduction or elimination of some of the conservatisms required by earlier, less sophisticated analyses. And more recently, as our industries open-quotes downsize,close quotes efforts are being made to find ways to use the ever-increasing computing capacity to design systems that accomplish more work, in less time, and with fewer people. The balance of this paper discusses some of the visions that Duke Power Company feels would most benefit their particular methodologies. One of the concepts receiving a lot of attention involves an automated coupling of a thermal-hydraulic plant systems analysis model to a three-dimensional core neutronics program. The thermal-hydraulic analysis of several postulated system transients incorporates large conservatisms because of limited ability to model complex time-dependent asymmetric heat sources in adequate geometric detail. For these transients, the core behavior is closely coupled with the thermal-hydraulic behavior of the total plant system and vice versa. Steam-line break, uncontrolled rod withdrawal, and rod drop anayses are likely to benefit most from this type of linked process
Gap junctions and connexin-interacting proteins
Giepmans, Ben N G
2004-01-01
Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the
The 3-dimensional core model DYN3D
Energy Technology Data Exchange (ETDEWEB)
Grundmann, U.; Mittag, S.; Rohde, U.
1999-01-01
Analyzing the safety margins in transients and accidents of nuclear reactors 3-dimensional models of the core were used to avoid conservative assumptions needed for point kinetics or 1-dimensional models. Therefore, the 3D code DYN3D has been developed for the analysis of reactivity initiated accidents (RIA) in thermal nuclear reactors. The power distributions are calculated with the help of nodal expansion methods (NEM) for hexagonal and Cartesian geometry. The fuel rod model and the thermohydraulic part provide fuel temperatures, coolant temperatures and densities as well as boron concentrations for the calculation of feedback effects on the basis of cross section libraries generated by cell codes. Safety relevant parameters like maximum fuel and cladding temperatures, critical heat flux and degree of cladding oxidation are estimated. DYN3D can analyze RIA initiated by moved control rods and/or perturbations of the coolant flow. Stationary and transient boundary conditions for the coolant flow, the core inlet temperatures and boron concentrations at the core inlet have to be given. For analyzing more complex transients the code DYN3D is coupled with the plant model ATHLET of the GRS. The extensive validation work accomplished for DYN3D is presented in several examples. Some applications of the code are described. (orig.) [Deutsch] Die Verwendung 3-dimensionaler Kernmodelle zur Untersuchung der Sicherheitsreserven bei Uebergangsprozessen und Stoerfaellen in Kernreaktoren vermeidet konservative Annahmen, die bei der Benutzung des Punktmodells oder 1-dimensionaler Modelle erforderlich sind. Aus diesen Gruenden wurde das 3-dimensionale Rechenprogramm DYN3D fuer die Untersuchung von Reaktivitaetsstoerfaellen in thermischen Reaktoren entwickelt. Die Leistungsverteilung wird mit nodalen Methoden fuer hexagonale oder kartesische Geometrie berechnet. Das Brennstabmodell und der thermohydraulische Teil von DYN3D liefert die Brennstofftemperaturen, Kuehlmitteltemperaturen
Directory of Open Access Journals (Sweden)
Mindaugas Snipas
2015-01-01
Full Text Available The primary goal of this work was to study advantages of numerical methods used for the creation of continuous time Markov chain models (CTMC of voltage gating of gap junction (GJ channels composed of connexin protein. This task was accomplished by describing gating of GJs using the formalism of the stochastic automata networks (SANs, which allowed for very efficient building and storing of infinitesimal generator of the CTMC that allowed to produce matrices of the models containing a distinct block structure. All of that allowed us to develop efficient numerical methods for a steady-state solution of CTMC models. This allowed us to accelerate CPU time, which is necessary to solve CTMC models, ∼20 times.
Kevrekidis, Panayotis; Williams, Floyd
2014-01-01
The sine-Gordon model is a ubiquitous model of Mathematical Physics with a wide range of applications extending from coupled torsion pendula and Josephson junction arrays to gravitational and high-energy physics models. The purpose of this book is to present a summary of recent developments in this field, incorporating both introductory background material, but also with a strong view towards modern applications, recent experiments, developments regarding the existence, stability, dynamics and asymptotics of nonlinear waves that arise in the model. This book is of particular interest to a wide range of researchers in this field, but serves as an introductory text for young researchers and students interested in the topic. The book consists of well-selected thematic chapters on diverse mathematical and physical aspects of the equation carefully chosen and assigned.
Numerical simulation of the self-pumped long Josephson junction using a modified sine-Gordon model
International Nuclear Information System (INIS)
Sobolev, A.S.; Pankratov, A.L.; Mygind, J.
2006-01-01
We have numerically investigated the dynamics of a long Josephson junction (flux-flow oscillator) biased by a DC current in the presence of magnetic field. The study is performed in the frame of the modified sine-Gordon model, which includes the surface losses, RC-load at both FFO ends and the self-pumping effect. In our model the dumping parameter depends both on the spatial coordinate and the amplitude of the AC voltage. In order to find the DC FFO voltage the damping parameter has to be calculated by successive approximations and time integration of the perturbed sine-Gordon equation. The modified model, which accounts for the presence of the superconducting gap, gives better qualitative agreement with experimental results compare to the conventional sine-Gordon model
Pranevicius, Henrikas; Pranevicius, Mindaugas; Pranevicius, Osvaldas; Bukauskas, Feliksas F.
2015-01-01
The primary goal of this work was to study advantages of numerical methods used for the creation of continuous time Markov chain models (CTMC) of voltage gating of gap junction (GJ) channels composed of connexin protein. This task was accomplished by describing gating of GJs using the formalism of the stochastic automata networks (SANs), which allowed for very efficient building and storing of infinitesimal generator of the CTMC that allowed to produce matrices of the models containing a distinct block structure. All of that allowed us to develop efficient numerical methods for a steady-state solution of CTMC models. This allowed us to accelerate CPU time, which is necessary to solve CTMC models, ∼20 times. PMID:25705700
Testing Numerical Models of Cool Core Galaxy Cluster Formation with X-Ray Observations
Henning, Jason W.; Gantner, Brennan; Burns, Jack O.; Hallman, Eric J.
2009-12-01
Using archival Chandra and ROSAT data along with numerical simulations, we compare the properties of cool core and non-cool core galaxy clusters, paying particular attention to the region beyond the cluster cores. With the use of single and double β-models, we demonstrate a statistically significant difference in the slopes of observed cluster surface brightness profiles while the cluster cores remain indistinguishable between the two cluster types. Additionally, through the use of hardness ratio profiles, we find evidence suggesting cool core clusters are cooler beyond their cores than non-cool core clusters of comparable mass and temperature, both in observed and simulated clusters. The similarities between real and simulated clusters supports a model presented in earlier work by the authors describing differing merger histories between cool core and non-cool core clusters. Discrepancies between real and simulated clusters will inform upcoming numerical models and simulations as to new ways to incorporate feedback in these systems.
International Nuclear Information System (INIS)
Zerbino, H.
1997-01-01
The physical models implemented in power plant simulators have greatly increased in performance and complexity in recent years. This process has been enabled by the ever increasing computing power available at affordable prices. This paper describes this process from several angles: First the operational requirements which are more critical from the point of view of model performance, both for normal and off-normal operating conditions; A second section discusses core model characteristics in the light of the solutions implemented by Thomson Training and Simulation (TT and S) in several full-scope simulators recently built and delivered for Dutch, German, and French nuclear power plants; finally we consider the model validation procedures, which are of course an integral part of model development, and which are becoming more and more severe as performance expectations increase. As a conclusion, it may be asserted that in the core modeling field, as in other areas, the general improvement in the quality of simulation codes has resulted in a fairly rapid convergence towards mainstream engineering-grade calculations. This is remarkable performance in view of the stringent real-time requirements which the simulation codes must satisfy as well as the extremely wide range of operating conditions that they are called upon to cover with good accuracy. (author)
Development of an automated core model for nuclear reactors
International Nuclear Information System (INIS)
Mosteller, R.D.
1998-01-01
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop an automated package of computer codes that can model the steady-state behavior of nuclear-reactor cores of various designs. As an added benefit, data produced for steady-state analysis also can be used as input to the TRAC transient-analysis code for subsequent safety analysis of the reactor at any point in its operating lifetime. The basic capability to perform steady-state reactor-core analysis already existed in the combination of the HELIOS lattice-physics code and the NESTLE advanced nodal code. In this project, the automated package was completed by (1) obtaining cross-section libraries for HELIOS, (2) validating HELIOS by comparing its predictions to results from critical experiments and from the MCNP Monte Carlo code, (3) validating NESTLE by comparing its predictions to results from numerical benchmarks and to measured data from operating reactors, and (4) developing a linkage code to transform HELIOS output into NESTLE input
Edge and coupled core/edge transport modelling in tokamaks
International Nuclear Information System (INIS)
Lodestro, L.L.; Casper, T.A.; Cohen, R.H.
1999-01-01
Recent advances in the theory and modelling of tokamak edge, scrape-off-layer (SOL) and divertor plasmas are described. The effects of the poloidal E x B drift on inner/outer divertor-plate asymmetries within a 1D analysis are shown to be in good agreement with experimental trends; above a critical v ExB , the model predicts transitions to supersonic flow at the inboard midplane. 2D simulations show the importance of E x B flow in the private-flux region and of ∇ B-drifts. A theory of rough plasma-facing surfaces is given, predicting modifications to the SOL plasma. The parametric dependence of detached-plasma states in slab geometry has been explored; with sufficient pumping, the location of the ionization front can be controlled; otherwise only fronts near the plate or the X-point are stable. Studies with a more accurate Monte-Carlo neutrals model and a detailed non-LTE radiation-transport code indicate various effects are important for quantitative modelling. Detailed simulations of the DIII-D core and edge are presented; impurity and plasma flow are discussed and shown to be well modelled with UEDGE. (author)
Edge and coupled core-edge transport modelling in tokamaks
International Nuclear Information System (INIS)
Lodestro, L.L.; Casper, T.A.; Cohen, R.H.
2001-01-01
Recent advances in the theory and modelling of tokamak edge, scrape-off-layer (SOL) and divertor plasmas are described. The effects of the poloidal ExB drift on inner/outer divertor-plate asymmetries within a 1D analysis are shown to be in good agreement with experimental trends; above a critical v ExB, the model predicts transitions to supersonic SOL flow at the inboard midplane. 2D simulations show the importance of ExB flow in the private-flux region and of ∇ B-drifts. A theory of rough plasma-facing surfaces is given, predicting modifications to the SOL plasma. The parametric dependence of detached-plasma states in slab geometry has been explored; with sufficient pumping, the location of the ionization front can be controlled; otherwise only fronts near the plate or the X-point are stable. Studies with a more accurate Monte-Carlo neutrals model and a detailed non-LTE radiation-transport code indicate various effects are important for quantitative modelling. Detailed simulations of the DIII-D core and edge are presented; impurity and plasma flow are discussed and shown to be well modelled with UEDGE. (author)
Modelling Pressurized Water Reactor cores in terms of porous media
International Nuclear Information System (INIS)
Ricciardi, G.; Collard, B.; Ricciardi, G.; Bellizzi, S.; Cochelin, B.
2009-01-01
The aim of this study is to develop a tractable model of a nuclear reactor core taking the complexity of the structure (including its nonlinear behaviour) and fluid flow coupling into account. The mechanical behaviour modelling includes the dynamics of both the fuel assemblies and the fluid. Each rod bundle is modelled in the form of a deformable porous medium; then, the velocity field of the fluid and the displacement field of the structure are defined over the whole domain. The fluid and the structure are first modelled separately, before being linked together. The equations of motion for the structure are obtained using a Lagrangian approach and, to be able to link up the fluid and the structure, the equations of motion for the fluid are obtained using an arbitrary Lagrangian Eulerian approach. The finite element method is applied to spatially discretize the equations. Simulations are performed to analyse the effects of the characteristics of the fluid and of the structure. Finally, the model is validated with a test involving two fuel assemblies, showing good agreement with the experimental data. (authors)
CFD approach to modeling of core-concrete interaction
International Nuclear Information System (INIS)
Vladimir V Chudanov; Anna E Aksenova; Valerii A Pervichko
2005-01-01
Full text of publication follows: A large attention is given to research behavior of concrete structures at high mechanical and thermal loadings, which those suffer at the severe accidents on Nuclear Power Plants with core melting and falling of the molten corium mass into reactor shaft. There are enough programs for analysis of heat and mass transfer processes at interaction of the molten corium with concrete. Most known among them CORCON and WECHSL, which were developed more than twenty years ago, allow considering a quasi-stationary phase decomposition of concrete and the some transition regimes. In opposing to the mentioned codes a new more generalized mathematical model and software are developed for modeling of a wide range of the heat and mass transfer processes under study of the molten core-concrete interaction. The developed mathematical model is based on the Navier-Stokes equations with variable properties with taking into account of a density jump under melting of concrete together with a heat transfer equation. The offered numerical technique is based on modern algorithms with small scheme diffusion, whose discrete approximations are constructed with use of finite-volume methods and the fully staggered grids. The developed software corresponds to modern level of development of computers and takes into account all phenomenology, used by mentioned codes, and allows to simulate the such phenomena and processes as: multidimensional heat transfer in concrete for modeling of transients for an intermediate thermal flux to concrete; direct erosion of concrete at a quasi-stationary regime of interaction with molten fuel masses; heat and mass transfer in corium and convective intermixing in a melt of corium with taking into account of its stratification on two layers of the metal and oxide components and heat transfer by radiation in a cavity of the reactor shaft; change physical properties of corium at concrete decomposition and release in corium of its
Linac beam core modeling from wire-scanner data
International Nuclear Information System (INIS)
Law, A.G.
1977-08-01
This study introduces mathematical modeling of accelerator beams from data collected by wire scanners. Details about a beam core D(x,x',y,y') are examined in several situations: (a) for a discretization of the projection into xy-space, a maximum-entropy solution and a minimum-norm solution are developed and discussed, (b) for undiscretized xy-subspace, a two-dimensional Gaussian approximation D(x,.,y,.) = a exp [α(x-x 0 ) 2 + β(x-x 0 )(y-y 0 ) + γ(y-y 0 ) 2 ] is obtained by least squares, and (c) for four-dimensional space, the fit of a single Gaussian to data from a succession of wire scanners is investigated
Dynamics of pi-junction interferometer circuits
DEFF Research Database (Denmark)
Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.
2002-01-01
The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current depe...
Rizzuto, Emanuele; Pisu, Simona; Musarò, Antonio; Del Prete, Zaccaria
2015-09-01
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to motor neuron degeneration, alteration in neuromuscular junctions (NMJs), muscle atrophy, and paralysis. To investigate the NMJ functionality in ALS we tested, in vitro, two innervated muscle types excised from SOD1(G93A) transgenic mice at the end-stage of the disease: the Soleus, a postural muscle almost completely paralyzed at that stage, and the diaphragm, which, on the contrary, is functional until death. To this aim we employed an experimental protocol that combined two types of electrical stimulation: the direct stimulation and the stimulation through the nerve. The technique we applied allowed us to determine the relevance of NMJ functionality separately from muscle contractile properties in SOD1(G93A) animal model. Functional measurements revealed that the muscle contractility of transgenic diaphragms is almost unaltered in comparison to control muscles, while transgenic Soleus muscles were severely compromised. In contrast, when stimulated via the nerve, both transgenic muscle types showed a strong decrease of the contraction force, a slowing down of the kinetic parameters, as well as alterations in the neurotransmission failure parameter. All together, these results confirm a severely impaired functionality in the SOD1(G93A) neuromuscular junctions.
THE CUSP/CORE PROBLEM AND THE SECONDARY INFALL MODEL
International Nuclear Information System (INIS)
Del Popolo, A.
2009-01-01
We study the cusp/core problem using a secondary infall model that takes into account the effect of ordered and random angular momentum, dynamical friction, and baryons adiabatic contraction (AC). The model is applied to structures on galactic scales (normal and dwarfs spiral galaxies) and on clusters of galaxies scales. Our analysis suggest that angular momentum and dynamical friction are able, on galactic scales, to overcome the competing effect of AC eliminating the cusp. The slope of density profile of inner halos flattens with decreasing halo mass and the profile is well approximated by a Burkert's profile. In order to obtain the Navarro-Frenk-White (NFW) profile, starting from the profiles obtained from our model, the magnitude of angular momentum and dynamical friction must be reduced with respect to the values predicted by the model itself. The rotation curves of four lower sideband galaxies from Gentile et al. are compared to the rotation curves obtained by the model in the present paper obtaining a good fit to the observational data. The time evolution of the density profile of a galaxy of 10 8 -10 9 M sun shows that after a transient steepening, due to the AC, the density profile flattens to α ≅ 0. On cluster scales we observe a similar evolution of the dark matter (DM) density profile but in this case the density profile slope flattens to α ≅ 0.6 for a cluster of ≅10 14 M sun . The total mass profile, differently from that of DM, shows a central cusp well fitted by an NFW model.
Four-fluid model of PWR degraded cores
International Nuclear Information System (INIS)
Dearing, J.F.
1985-01-01
This paper describes the new two-dimensional, four-fluid fluid dynamics and heat transfer (FLUIDS) module of the MELPROG code. MELPROG is designed to give an integrated, mechanistic treatment of pressurized water reactor (PWR) core meltdown accidents from accident initiation to vessel melt-through. The code has a modular data storage and transfer structure, with each module providing the others with boundary conditions at each computational time step. Thus the FLUIDS module receives mass and energy source terms from the fuel pin module, the structures module, and the debris bed module, and radiation energy source terms from the radiation module. MELPROG, which models the reactor vessel, is also designed to model the vessel as a component in the TRAC/PF1 networking solution of a PWR reactor coolant system (RCS). The coupling between TRAC and MELPROG is implicit in the fluid dynamics of the reactor coolant (liquid water and steam) allowing an accurate simulation of the coupling between the vessel and the rest of the RCS during an accident. This paper deals specifically with the numerical model of fluid dynamics and heat transfer within the reactor vessel, which allows a much more realistic simulation (with less restrictive assumptions on physical behavior) of the accident than has been possible before
A parabolic model to control quantum interference in T-shaped molecular junctions
DEFF Research Database (Denmark)
Nozaki, Daijiro; Sevincli, Haldun; Avdoshenko, Stanislav M.
2013-01-01
Quantum interference (QI) effects in molecular devices have drawn increasing attention over the past years due to their unique features observed in the conductance spectrum. For the further development of single molecular devices exploiting QI effects, it is of great theoretical and practical...... interest to develop simple methods controlling the emergence and the positions of QI effects like anti-resonances or Fano line shapes in conductance spectra. In this work, starting from a well-known generic molecular junction with a side group (T-shaped molecule), we propose a simple graphical method...... to visualize the conditions for the appearance of quantum interference, Fano resonances or anti-resonances, in the conductance spectrum. By introducing a simple graphical representation (parabolic diagram), we can easily visualize the relation between the electronic parameters and the positions of normal...
Malekian, Negin; Habibi, Jafar; Zangooei, Mohammad Hossein; Aghakhani, Hojjat
2016-11-01
There are many cells with various phenotypic behaviors in cancer interacting with each other. For example, an apoptotic cell may induce apoptosis in adjacent cells. A living cell can also protect cells from undergoing apoptosis and necrosis. These survival and death signals are propagated through interaction pathways between adjacent cells called gap junctions. The function of these signals depends on the cellular context of the cell receiving them. For instance, a receiver cell experiencing a low level of oxygen may interpret a received survival signal as an apoptosis signal. In this study, we examine the effect of these signals on tumor growth. We make an evolutionary game theory component in order to model the signal propagation through gap junctions. The game payoffs are defined as a function of cellular context. Then, the game theory component is integrated into an agent-based model of tumor growth. After that, the integrated model is applied to ductal carcinoma in situ, a type of early stage breast cancer. Different scenarios are explored to observe the impact of the gap junction communication and parameters of the game theory component on cancer progression. We compare these scenarios by using the Wilcoxon signed-rank test. The Wilcoxon signed-rank test succeeds in proving a significant difference between the tumor growth of the model before and after considering the gap junction communication. The Wilcoxon signed-rank test also proves that the tumor growth significantly depends on the oxygen threshold of turning survival signals into apoptosis. In this study, the gap junction communication is modeled by using evolutionary game theory to illustrate its role at early stage cancers such as ductal carcinoma in situ. This work indicates that the gap junction communication and the oxygen threshold of turning survival signals into apoptosis can notably affect cancer progression. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
International Nuclear Information System (INIS)
Zerbino, H.
1999-01-01
In 1994-1996, Thomson Training and Simulation (TT and S) earned out the D50 Project, which involved the design and construction of optimized replica simulators for one Dutch and three German Nuclear Power Plants. It was recognized early on that the faithful reproduction of the Siemens reactor control and protection systems would impose extremely stringent demands on the simulation models, particularly the Core physics and the RCS thermohydraulics. The quality of the models, and their thorough validation, were thus essential. The present paper describes the main features of the fully 3D Core model implemented by TT and S, and its extensive validation campaign, which was defined in extremely positive collaboration with the Customer and the Core Data suppliers. (author)
International Nuclear Information System (INIS)
Martinez, Michael
1999-01-01
The objective of this research thesis is, on the one hand, to elaborate and to characterise a bonded junction of 16MND5 and 316LN steels, and, on the other hand, to develop a simulation tool for the prediction of microstructures after bonding, as well as residual stresses related to this process. The author first reports the study of the use of diffusion bonding by hot isostatic pressing (HIP diffusion bonding) for the bonding of 16MND5 (steel used in French PWR vessel) and 316LN (austenitic stainless steel used in piping), in order to obtain junctions adapted to a use within PWRs. In this case, the use of an Inconel insert material appeared to be necessary to avoid stainless steel carburization. Thus, inserts in Inconel 600 and 690 have been tested. The objective has then been to develop a realistic calculation of residual stresses in this assembly. These stresses are stimulated by quenching. The author notably studied the simulation of temperature dependent phase transformations, and stress induced phase transformations. An existing model is validated and applied to HIP and quenching cycles. The last part reports the calculation of residual stresses by simulation of the mechanical response of the three-component material cooled from 900 C to room temperature and thus submitted to a loading of thermal origin (dilatation) and metallurgical origin (phase transformations in the 16MND5). The effect of carbon diffusion on mechanical properties has also been taken into account. The author discusses problems faced by existing models, and explains the choice of conventional macro-mechanical models. The three materials are supposed to have a plastic-viscoplastic behaviour with isotropic and kinematic strain hardening, and this behaviour is identified between 20 and 900 C [fr
International Nuclear Information System (INIS)
Beeckmans de West-Meerbeeck, A.
1991-01-01
Irradiation in neutron absorbing devices, requiring high fast neutron fluxes in the core or high thermal fluxes in the reflector and flux traps, lead to higher density fuel and larger core dimensions. A perturbation model of the reactor core helps to estimate the fuel requirements. (orig.)
On-line core monitoring system based on buckling corrected modified one group model
International Nuclear Information System (INIS)
Freire, Fernando S.
2011-01-01
Nuclear power reactors require core monitoring during plant operation. To provide safe, clean and reliable core continuously evaluate core conditions. Currently, the reactor core monitoring process is carried out by nuclear code systems that together with data from plant instrumentation, such as, thermocouples, ex-core detectors and fixed or moveable In-core detectors, can easily predict and monitor a variety of plant conditions. Typically, the standard nodal methods can be found on the heart of such nuclear monitoring code systems. However, standard nodal methods require large computer running times when compared with standards course-mesh finite difference schemes. Unfortunately, classic finite-difference models require a fine mesh reactor core representation. To override this unlikely model characteristic we can usually use the classic modified one group model to take some account for the main core neutronic behavior. In this model a course-mesh core representation can be easily evaluated with a crude treatment of thermal neutrons leakage. In this work, an improvement made on classic modified one group model based on a buckling thermal correction was used to obtain a fast, accurate and reliable core monitoring system methodology for future applications, providing a powerful tool for core monitoring process. (author)
Normal Mode Derived Models of the Physical Properties of Earth's Outer Core
Irving, J. C. E.; Cottaar, S.; Lekic, V.; Wu, W.
2017-12-01
Earth's outer core, the largest reservoir of metal in our planet, is comprised of an iron alloy of an uncertain composition. Its dynamical behaviour is responsible for the generation of Earth's magnetic field, with convection driven both by thermal and chemical buoyancy fluxes. Existing models of the seismic velocity and density of the outer core exhibit some variation, and there are only a small number of models which aim to represent the outer core's density.It is therefore important that we develop a better understanding of the physical properties of the outer core. Though most of the outer core is likely to be well mixed, it is possible that the uppermost outer core is stably stratified: it may be enriched in light elements released during the growth of the solid, iron enriched, inner core; by elements dissolved from the mantle into the outer core; or by exsolution of compounds previously dissolved in the liquid metal which will eventually be swept into the mantle. The stratified layer may host MAC or Rossby waves and it could impede communication between the chemically differentiated mantle and outer core, including screening out some of the geodynamo's signal. We use normal mode center frequencies to estimate the physical properties of the outer core in a Bayesian framework. We estimate the mineral physical parameters needed to best produce velocity and density models of the outer core which are consistent with the normal mode observations. We require that our models satisfy realistic physical constraints. We create models of the outer core with and without a distinct uppermost layer and assess the importance of this region.Our normal mode-derived models are compared with observations of body waves which travel through the outer core. In particular, we consider SmKS waves which are especially sensitive to the uppermost outer core and are therefore an important way to understand the robustness of our models.
Contact with friction modeling for the study of a bolted junction
International Nuclear Information System (INIS)
Lebon, F.; Raous, M.; Boulegues, D.
1987-01-01
Many structural analysis problems are concerned by contact phenomena. A good knowledge of the contact displacements and the contact forces between the different parts of the structure is generally essential in structure assembling. The special boundary behaviour has a strong influence on the distribution of the stresses in the whole structure and on his total fiability. The contact behaviour is strongly non linear because of the non penetration conditions on the one hand, and because of the friction on the other. On such problems the real contact zone and the contact forces are unknown 'a priori' and have to be determined during the resolution. The non-penetration is characterized by unilateral conditions and the friction is described by a constitutive law (Coulomb friction law). The application presented here concerns the assembling of the three parts of a bolted junction using a pressing ring. There are three contact zones in this program. A good description of the contact phenomena is essential to ensure tightness. Our methods are based on projection techniques coupled with overrelaxed Gauss-Seidel methods including condensation procedures (reduction of the number of variables). Non linear programming methods and iterative procedures on special boundary conditions are also used. (orig./HP)
On-Line Core Thermal-Hydraulic Model Improvement
International Nuclear Information System (INIS)
In, Wang Kee; Chun, Tae Hyun; Oh, Dong Seok; Shin, Chang Hwan; Hwang, Dae Hyun; Seo, Kyung Won
2007-02-01
The objective of this project is to implement a fast-running 4-channel based code CETOP-D in an advanced reactor core protection calculator system(RCOPS). The part required for the on-line calculation of DNBR were extracted from the source of the CETOP-D code based on analysis of the CETOP-D code. The CETOP-D code was revised to maintain the input and output variables which are the same as in CPC DNBR module. Since the DNBR module performs a complex calculation, it is divided into sub-modules per major calculation step. The functional design requirements for the DNBR module is documented and the values of the database(DB) constants were decided. This project also developed a Fortran module(BEST) of the RCOPS Fortran Simulator and a computer code RCOPS-SDNBR to independently calculate DNBR. A test was also conducted to verify the functional design and DB of thermal-hydraulic model which is necessary to calculate the DNBR on-line in RCOPS. The DNBR margin is expected to increase by 2%-3% once the CETOP-D code is used to calculate the RCOPS DNBR. It should be noted that the final DNBR margin improvement could be determined in the future based on overall uncertainty analysis of the RCOPS
On-Line Core Thermal-Hydraulic Model Improvement
Energy Technology Data Exchange (ETDEWEB)
In, Wang Kee; Chun, Tae Hyun; Oh, Dong Seok; Shin, Chang Hwan; Hwang, Dae Hyun; Seo, Kyung Won
2007-02-15
The objective of this project is to implement a fast-running 4-channel based code CETOP-D in an advanced reactor core protection calculator system(RCOPS). The part required for the on-line calculation of DNBR were extracted from the source of the CETOP-D code based on analysis of the CETOP-D code. The CETOP-D code was revised to maintain the input and output variables which are the same as in CPC DNBR module. Since the DNBR module performs a complex calculation, it is divided into sub-modules per major calculation step. The functional design requirements for the DNBR module is documented and the values of the database(DB) constants were decided. This project also developed a Fortran module(BEST) of the RCOPS Fortran Simulator and a computer code RCOPS-SDNBR to independently calculate DNBR. A test was also conducted to verify the functional design and DB of thermal-hydraulic model which is necessary to calculate the DNBR on-line in RCOPS. The DNBR margin is expected to increase by 2%-3% once the CETOP-D code is used to calculate the RCOPS DNBR. It should be noted that the final DNBR margin improvement could be determined in the future based on overall uncertainty analysis of the RCOPS.
Directory of Open Access Journals (Sweden)
Hongbin Lu
Full Text Available This study was designed to evaluate the effects of low-intensity pulsed ultrasound on bone regeneration during the bone-tendon junction healing process and to explore the application of synchrotron radiation micro computed tomography in three dimensional visualization of the bone-tendon junction to evaluate the microarchitecture of new trabecular bone. Twenty four mature New Zealand rabbits underwent partial patellectomy to establish a bone-tendon junction injury model at the patella-patellar tendon complex. Animals were then divided into low-intensity pulsed ultrasound treatment (20 min/day, 7 times/week and placebo control groups, and were euthanized at week 8 and 16 postoperatively (n = 6 for each group and time point. The patella-patellar tendon specimens were harvested for radiographic, histological and synchrotron radiation micro computed tomography detection. The area of the newly formed bone in the ultrasound group was significantly greater than that of control group at postoperative week 8 and 16. The high resolution three dimensional visualization images of the bone-tendon junction were acquired by synchrotron radiation micro computed tomography. Low-intensity pulsed ultrasound treatment promoted dense and irregular woven bone formation at week 8 with greater bone volume fraction, number and thickness of new trabecular bone but with lower separation. At week 16, ultrasound group specimens contained mature lamellar bone with higher bone volume fraction and thicker trabeculae than that of control group; however, there was no significant difference in separation and number of the new trabecular bone. This study confirms that low-intensity pulsed ultrasound treatment is able to promote bone formation and remodeling of new trabecular bone during the bone-tendon junction healing process in a rabbit model, and the synchrotron radiation micro computed tomography could be applied for three dimensional visualization to quantitatively evaluate
Ekofisk chalk: core measurements, stochastic reconstruction, network modeling and simulation
Energy Technology Data Exchange (ETDEWEB)
Talukdar, Saifullah
2002-07-01
This dissertation deals with (1) experimental measurements on petrophysical, reservoir engineering and morphological properties of Ekofisk chalk, (2) numerical simulation of core flood experiments to analyze and improve relative permeability data, (3) stochastic reconstruction of chalk samples from limited morphological information, (4) extraction of pore space parameters from the reconstructed samples, development of network model using pore space information, and computation of petrophysical and reservoir engineering properties from network model, and (5) development of 2D and 3D idealized fractured reservoir models and verification of the applicability of several widely used conventional up scaling techniques in fractured reservoir simulation. Experiments have been conducted on eight Ekofisk chalk samples and porosity, absolute permeability, formation factor, and oil-water relative permeability, capillary pressure and resistivity index are measured at laboratory conditions. Mercury porosimetry data and backscatter scanning electron microscope images have also been acquired for the samples. A numerical simulation technique involving history matching of the production profiles is employed to improve the relative permeability curves and to analyze hysteresis of the Ekofisk chalk samples. The technique was found to be a powerful tool to supplement the uncertainties in experimental measurements. Porosity and correlation statistics obtained from backscatter scanning electron microscope images are used to reconstruct microstructures of chalk and particulate media. The reconstruction technique involves a simulated annealing algorithm, which can be constrained by an arbitrary number of morphological parameters. This flexibility of the algorithm is exploited to successfully reconstruct particulate media and chalk samples using more than one correlation functions. A technique based on conditional simulated annealing has been introduced for exact reproduction of vuggy
2012-01-01
Backgound Amyotrophic lateral sclerosis (ALS) is progressive neurodegenerative disease characterized by the loss of motor function. Several ALS genes have been identified as their mutations can lead to familial ALS, including the recently reported RNA-binding protein fused in sarcoma (Fus). However, it is not clear how mutations of Fus lead to motor neuron degeneration in ALS. In this study, we present a Drosophila model to examine the toxicity of Fus, its Drosophila orthologue Cabeza (Caz), and the ALS-related Fus mutants. Results Our results show that the expression of wild-type Fus/Caz or FusR521G induced progressive toxicity in multiple tissues of the transgenic flies in a dose- and age-dependent manner. The expression of Fus, Caz, or FusR521G in motor neurons significantly impaired the locomotive ability of fly larvae and adults. The presynaptic structures in neuromuscular junctions were disrupted and motor neurons in the ventral nerve cord (VNC) were disorganized and underwent apoptosis. Surprisingly, the interruption of Fus nuclear localization by either deleting its nuclear localization sequence (NLS) or adding a nuclear export signal (NES) blocked Fus toxicity. Moreover, we discovered that the loss of caz in Drosophila led to severe growth defects in the eyes and VNCs, caused locomotive disability and NMJ disruption, but did not induce apoptotic cell death. Conclusions These data demonstrate that the overexpression of Fus/Caz causes in vivo toxicity by disrupting neuromuscular junctions (NMJs) and inducing apoptosis in motor neurons. In addition, the nuclear localization of Fus is essential for Fus to induce toxicity. Our findings also suggest that Fus overexpression and gene deletion can cause similar degenerative phenotypes but the underlying mechanisms are likely different. PMID:22443542
Directory of Open Access Journals (Sweden)
Xia Ruohan
2012-03-01
Full Text Available Abstract Backgound Amyotrophic lateral sclerosis (ALS is progressive neurodegenerative disease characterized by the loss of motor function. Several ALS genes have been identified as their mutations can lead to familial ALS, including the recently reported RNA-binding protein fused in sarcoma (Fus. However, it is not clear how mutations of Fus lead to motor neuron degeneration in ALS. In this study, we present a Drosophila model to examine the toxicity of Fus, its Drosophila orthologue Cabeza (Caz, and the ALS-related Fus mutants. Results Our results show that the expression of wild-type Fus/Caz or FusR521G induced progressive toxicity in multiple tissues of the transgenic flies in a dose- and age-dependent manner. The expression of Fus, Caz, or FusR521G in motor neurons significantly impaired the locomotive ability of fly larvae and adults. The presynaptic structures in neuromuscular junctions were disrupted and motor neurons in the ventral nerve cord (VNC were disorganized and underwent apoptosis. Surprisingly, the interruption of Fus nuclear localization by either deleting its nuclear localization sequence (NLS or adding a nuclear export signal (NES blocked Fus toxicity. Moreover, we discovered that the loss of caz in Drosophila led to severe growth defects in the eyes and VNCs, caused locomotive disability and NMJ disruption, but did not induce apoptotic cell death. Conclusions These data demonstrate that the overexpression of Fus/Caz causes in vivo toxicity by disrupting neuromuscular junctions (NMJs and inducing apoptosis in motor neurons. In addition, the nuclear localization of Fus is essential for Fus to induce toxicity. Our findings also suggest that Fus overexpression and gene deletion can cause similar degenerative phenotypes but the underlying mechanisms are likely different.
International Nuclear Information System (INIS)
Dobrowolski, Tomasz
2012-01-01
The constant curvature one and quasi-one dimensional Josephson junction is considered. On the base of Maxwell equations, the sine–Gordon equation that describes an influence of curvature on the kink motion was obtained. It is showed that the method of geometrical reduction of the sine–Gordon model from three to lower dimensional manifold leads to an identical form of the sine–Gordon equation. - Highlights: ► The research on dynamics of the phase in a curved Josephson junction is performed. ► The geometrical reduction is applied to the sine–Gordon model. ► The results of geometrical reduction and the fundamental research are compared.
A Practical Core Loss Model for Filter Inductors of Power Electronic Converters
DEFF Research Database (Denmark)
Matsumori, Hiroaki; Shimizu, Toshihisa; Wang, Xiongfei
2018-01-01
This paper proposes a core loss model for filter inductors of power electronic converters. The model allows a computationally efficient analysis on the core loss of the inductor under the square voltage excitation and the premagnetization condition. First, the core loss of the filter inductor under...... buck chopper excitation is evaluated with the proposed model and compared with the conventional methods. The comparison shows that the proposed method results in a better core loss prediction under the premagnetized condition than that of conventional alternatives. Then, the core loss of the filter...... inductor with the pulsewidth modulated inverter excitation is evaluated, which shows that the proposed model not only accurately predicts the core loss but also identifies the hysteresis loss part. These results demonstrate that the approach can further be used for the development of magnetic materials...
Two-dimensional horizontal model seismic test and analysis for HTGR core
International Nuclear Information System (INIS)
Ikushima, Takeshi; Honma, Toshiaki.
1988-05-01
The resistance against earthquakes of high-temperature gas-cooled reactor (HTGR) core with block-type fuels is not fully ascertained yet. Seismic studies must be made if such a reactor plant is to be installed in areas with frequent earthquakes. The paper presented the test results of seismic behavior of a half scale two-dimensional horizontal slice core model and analysis. The following is a summary of the more important results. (1) When the core is subjected to the single axis excitation and simultaneous two-axis excitations to the core across-corners, it has elliptical motion. The core stays lumped motion at the low excitation frequencies. (2) When the load is placed on side fixed reflector blocks from outside to the core center, the core displacement and reflector impact reaction force decrease. (3) The maximum displacement occurs at simultaneous two-axis excitations. The maximum displacement occurs at the single axis excitation to the core across-flats. (4) The results of two-dimensional horizontal slice core model was compared with the results of two-dimensional vertical one. It is clarified that the seismic response of actual core can be predicted from the results of two-dimensional vertical slice core model. (5) The maximum reflector impact reaction force for seismic waves was below 60 percent of that for sinusoidal waves. (6) Vibration behavior and impact response are in good agreement between test and analysis. (author)
A simplified geometrical model for transient corium propagation in core for LWR with heavy reflector
Directory of Open Access Journals (Sweden)
Saas Laurent
2017-01-01
Full Text Available In the context of the simulation of the Severe Accidents (SA in Light Water Reactors (LWR, we are interested on the in-core corium pool propagation transient in order to evaluate the corium relocation in the vessel lower head. The goal is to characterize the corium and debris flows from the core to accurately evaluate the corium pool propagation transient in the lower head and so the associated risk of vessel failure. In the case of LWR with heavy reflector, to evaluate the corium relocation into the lower head, we have to study the risk associated with focusing effect and the possibility to stabilize laterally the corium in core with a flooded down-comer. It is necessary to characterize the core degradation and the stratification of the corium pool that is formed in core. We assume that the core degradation until the corium pool formation and the corium pool propagation could be modeled separately. In this document, we present a simplified geometrical model (0D model for the in-core corium propagation transient. A degraded core with a formed corium pool is used as an initial state. This state can be obtained from a simulation computed with an integral code. This model does not use a grid for the core as integral codes do. Geometrical shapes and 0D models are associated with the corium pool and the other components of the degraded core (debris, heavy reflector, core plate…. During the transient, these shapes evolve taking into account the thermal and stratification behavior of the corium pool and the melting of the core surrounding components. Some results corresponding to the corium pool propagation in core transients obtained with this model on a LWR with a heavy reflector are given and compared to grid approach of the integral codes MAAP4.
Lagabrielle, Yves; Guivel, Christèle; Maury, René C.; Bourgois, Jacques; Fourcade, Serge; Martin, Hervé
2000-11-01
High thermal gradients are expected to be found at sites of subduction of very young oceanic lithosphere and more particularly at ridge-trench-trench (RTT) triple junctions, where active oceanic spreading ridges enter a subduction zone. Active tectonics, associated with the emplacement of two main types of volcanic products, (1) MORB-type magmas, and (2) calc-alkaline acidic magmas in the forearc, also characterize these plate junction domains. In this context, MORB-type magmas are generally thought to derive from the buried active spreading center subducted at shallow depths, whereas the origin of calc-alkaline acidic magmas is more problematic. One of the best constrained examples of ridge-trench interaction is the Chile Triple Junction (CTJ) located southwest of the South American plate at 46°12'S, where the active Chile spreading center enters the subduction zone. In this area, there is a clear correlation between the emplacement of magmatic products and the migration of the triple junction along the active margin. The CTJ lava population is bimodal, with mafic to intermediate lavas (48-56% SiO 2) and acidic lavas ranging from dacites to rhyolites (66-73% SiO 2). Previous models have shown that partial melting of oceanic crust plus 10-20% of sediments, leaving an amphibole- and plagioclase-rich residue, is the only process that may account for the genesis of acidic magmas. Due to special plate geometry in the CTJ area, a given section of the margin may be successively affected by the passage of several ridge segments. We emphasize that repeated passages will lead to the development of very high thermal gradients allowing melting of rocks of oceanic origin at temperatures of 800-900°C and low pressures, corresponding to depths of 10-20 km depth only. In addition, the structure of the CTJ forearc domain is dominated by horizontal displacements and tilting of crustal blocks along a network of strike-slip faults. The occurrence of such a deformed domain implies
A HARDCORE model for constraining an exoplanet's core size
Suissa, Gabrielle; Chen, Jingjing; Kipping, David
2018-05-01
The interior structure of an exoplanet is hidden from direct view yet likely plays a crucial role in influencing the habitability of the Earth analogues. Inferences of the interior structure are impeded by a fundamental degeneracy that exists between any model comprising more than two layers and observations constraining just two bulk parameters: mass and radius. In this work, we show that although the inverse problem is indeed degenerate, there exists two boundary conditions that enables one to infer the minimum and maximum core radius fraction, CRFmin and CRFmax. These hold true even for planets with light volatile envelopes, but require the planet to be fully differentiated and that layers denser than iron are forbidden. With both bounds in hand, a marginal CRF can also be inferred by sampling in-between. After validating on the Earth, we apply our method to Kepler-36b and measure CRFmin = (0.50 ± 0.07), CRFmax = (0.78 ± 0.02), and CRFmarg = (0.64 ± 0.11), broadly consistent with the Earth's true CRF value of 0.55. We apply our method to a suite of hypothetical measurements of synthetic planets to serve as a sensitivity analysis. We find that CRFmin and CRFmax have recovered uncertainties proportional to the relative error on the planetary density, but CRFmarg saturates to between 0.03 and 0.16 once (Δρ/ρ) drops below 1-2 per cent. This implies that mass and radius alone cannot provide any better constraints on internal composition once bulk density constraints hit around a per cent, providing a clear target for observers.
Directory of Open Access Journals (Sweden)
Antonio J. Torregrosa
2017-05-01
Full Text Available Duct junctions play a major role in the operation and design of most piping systems. The objective of this paper is to establish the potential of a staggered mesh finite volume model as a way to improve the description of the effect of simple duct junctions on an otherwise one-dimensional flow system, such as the intake or exhaust of an internal combustion engine. Specific experiments have been performed in which different junctions have been characterized as a multi-port, and that have provided precise and reliable results on the propagation of pressure pulses across junctions. The results obtained have been compared to simulations performed with a staggered mesh finite volume method with different flux limiters and different meshes and, as a reference, have also been compared with the results of a more conventional pressure loss-based model. The results indicate that the staggered mesh finite volume model provides a closer description of wave dynamics, even if further work is needed to establish the optimal calculation settings.
Silicon fiber with p-n junction
International Nuclear Information System (INIS)
Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B.
2014-01-01
In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.
Liu, Yi; Zhang, He; Liu, Siwei; Lin, Fuchang
2018-05-01
The J-A (Jiles-Atherton) model is widely used to describe the magnetization characteristics of magnetic cores in a low-frequency alternating field. However, this model is deficient in the quantitative analysis of the eddy current loss and residual loss in a high-frequency magnetic field. Based on the decomposition of magnetization intensity, an inverse J-A model is established which uses magnetic flux density B as an input variable. Static and dynamic core losses under high frequency excitation are separated based on the inverse J-A model. Optimized parameters of the inverse J-A model are obtained based on particle swarm optimization. The platform for the pulsed magnetization characteristic test is designed and constructed. The hysteresis curves of ferrite and Fe-based nanocrystalline cores at high magnetization rates are measured. The simulated and measured hysteresis curves are presented and compared. It is found that the inverse J-A model can be used to describe the magnetization characteristics at high magnetization rates and to separate the static loss and dynamic loss accurately.
Little Earth Experiment: An instrument to model planetary cores.
Aujogue, Kélig; Pothérat, Alban; Bates, Ian; Debray, François; Sreenivasan, Binod
2016-08-01
In this paper, we present a new experimental facility, Little Earth Experiment, designed to study the hydrodynamics of liquid planetary cores. The main novelty of this apparatus is that a transparent electrically conducting electrolyte is subject to extremely high magnetic fields (up to 10 T) to produce electromagnetic effects comparable to those produced by moderate magnetic fields in planetary cores. This technique makes it possible to visualise for the first time the coupling between the principal forces in a convection-driven dynamo by means of Particle Image Velocimetry (PIV) in a geometry relevant to planets. We first present the technology that enables us to generate these forces and implement PIV in a high magnetic field environment. We then show that the magnetic field drastically changes the structure of convective plumes in a configuration relevant to the tangent cylinder region of the Earth's core.
Performance modeling and analysis of parallel Gaussian elimination on multi-core computers
Directory of Open Access Journals (Sweden)
Fadi N. Sibai
2014-01-01
Full Text Available Gaussian elimination is used in many applications and in particular in the solution of systems of linear equations. This paper presents mathematical performance models and analysis of four parallel Gaussian Elimination methods (precisely the Original method and the new Meet in the Middle –MiM– algorithms and their variants with SIMD vectorization on multi-core systems. Analytical performance models of the four methods are formulated and presented followed by evaluations of these models with modern multi-core systems’ operation latencies. Our results reveal that the four methods generally exhibit good performance scaling with increasing matrix size and number of cores. SIMD vectorization only makes a large difference in performance for low number of cores. For a large matrix size (n ⩾ 16 K, the performance difference between the MiM and Original methods falls from 16× with four cores to 4× with 16 K cores. The efficiencies of all four methods are low with 1 K cores or more stressing a major problem of multi-core systems where the network-on-chip and memory latencies are too high in relation to basic arithmetic operations. Thus Gaussian Elimination can greatly benefit from the resources of multi-core systems, but higher performance gains can be achieved if multi-core systems can be designed with lower memory operation, synchronization, and interconnect communication latencies, requirements of utmost importance and challenge in the exascale computing age.
International Nuclear Information System (INIS)
Nikonov, S.; Pasichnyk, I.; Velkov, K.; Pautz, A.
2011-01-01
The paper describes the performed comparisons of measured and simulated local core data based on the OECD/NEA Benchmark on Kalinin-3 NPP: 'Switching off of one of the four operating main circulation pumps at nominal reactor power'. The local measurements of in core self-powered neutron detectors (SPND) in 64 fuel assemblies on 7 axial levels are used for the comparisons of the assemblies axial power distributions and the thermocouples readings at 93 fuel assembly heads are applied for the fuel assembly coolant temperature comparisons. The analyses are done on the base of benchmark transient calculations performed with the coupled system code ATHLET/BIPR-VVER. In order to describe more realistically the fluid mixing phenomena in a reactor pressure vessel a new enhanced nodalization scheme is being developed. It could take into account asymmetric flow behaviour in the reactor pressure vessel structures like downcomer, reactor core inlet and outlet, control rods' guided tubes, support grids etc. For this purpose details of the core geometry are modelled. About 58000 control volumes and junctions are applied. Cross connection are used to describe the interaction between the fluid objects. The performed comparisons are of great interest because they show some advantages by performing coupled code production pseudo-3D analysis of NPPs applying the parallel thermo-hydraulic channel methodology (or 1D thermo-hydraulic system code modeling). (Authors)
Ullrich, Paul A.; Jablonowski, Christiane; Kent, James; Lauritzen, Peter H.; Nair, Ramachandran; Reed, Kevin A.; Zarzycki, Colin M.; Hall, David M.; Dazlich, Don; Heikes, Ross; Konor, Celal; Randall, David; Dubos, Thomas; Meurdesoif, Yann; Chen, Xi; Harris, Lucas; Kühnlein, Christian; Lee, Vivian; Qaddouri, Abdessamad; Girard, Claude; Giorgetta, Marco; Reinert, Daniel; Klemp, Joseph; Park, Sang-Hun; Skamarock, William; Miura, Hiroaki; Ohno, Tomoki; Yoshida, Ryuji; Walko, Robert; Reinecke, Alex; Viner, Kevin
2017-12-01
Atmospheric dynamical cores are a fundamental component of global atmospheric modeling systems and are responsible for capturing the dynamical behavior of the Earth's atmosphere via numerical integration of the Navier-Stokes equations. These systems have existed in one form or another for over half of a century, with the earliest discretizations having now evolved into a complex ecosystem of algorithms and computational strategies. In essence, no two dynamical cores are alike, and their individual successes suggest that no perfect model exists. To better understand modern dynamical cores, this paper aims to provide a comprehensive review of 11 non-hydrostatic dynamical cores, drawn from modeling centers and groups that participated in the 2016 Dynamical Core Model Intercomparison Project (DCMIP) workshop and summer school. This review includes a choice of model grid, variable placement, vertical coordinate, prognostic equations, temporal discretization, and the diffusion, stabilization, filters, and fixers employed by each system.
Directory of Open Access Journals (Sweden)
P. A. Ullrich
2017-12-01
Full Text Available Atmospheric dynamical cores are a fundamental component of global atmospheric modeling systems and are responsible for capturing the dynamical behavior of the Earth's atmosphere via numerical integration of the Navier–Stokes equations. These systems have existed in one form or another for over half of a century, with the earliest discretizations having now evolved into a complex ecosystem of algorithms and computational strategies. In essence, no two dynamical cores are alike, and their individual successes suggest that no perfect model exists. To better understand modern dynamical cores, this paper aims to provide a comprehensive review of 11 non-hydrostatic dynamical cores, drawn from modeling centers and groups that participated in the 2016 Dynamical Core Model Intercomparison Project (DCMIP workshop and summer school. This review includes a choice of model grid, variable placement, vertical coordinate, prognostic equations, temporal discretization, and the diffusion, stabilization, filters, and fixers employed by each system.
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Munk-Nielsen, Stig; Teodorescu, Remus
2011-01-01
Reliability is a critical criterion for multi-MW wind turbines, which are being employed with increasing numbers in wind power plants, since they operate under harsh conditions and have high maintenance cost due to their remote locations. In this study, the wind turbine grid-side converter...... reliability is investigated regarding IGBT lifetime based on junction temperature cycling for the grid-side press-pack IGBT 3L-NPC-VSC, which is a state-of-the art high reliability solution. In order to acquire IGBT junction temperatures for given wind power profiles and to use them in IGBT lifetime...... prediction, the converter electro-thermal model including electrical, power loss, and dynamical thermal models is developed with the main focus on the thermal modeling regarding converter topology, switch technology, and physical structure. Moreover, these models are simplified for their practical...
DEFF Research Database (Denmark)
Finlay, Chris; Olsen, Nils; Gillet, Nicolas
We present a new ensemble of time-dependent magnetic field models constructed from satellite and observatory data spanning 1997-2013 that are compatible with prior information concerning the temporal spectrum of core field variations. These models allow sharper field changes compared to tradition...... physical hypotheses can be tested by asking questions of the entire ensemble of core field models, rather than by interpreting any single model.......We present a new ensemble of time-dependent magnetic field models constructed from satellite and observatory data spanning 1997-2013 that are compatible with prior information concerning the temporal spectrum of core field variations. These models allow sharper field changes compared to traditional...... regularization methods based on minimizing the square of second or third time derivative. We invert satellite and observatory data directly by adopting the external field and crustal field modelling framework of the CHAOS model, but apply the stochastic process method of Gillet et al. (2013) to the core field...
High energy pp and anti-pp elastic scattering in nucleon valence core model
International Nuclear Information System (INIS)
Islam, M.M.; Fearnley, T.
1986-01-01
Connection between the valence core model and the effective QCD models of nucleon structure is pointed out. Also, implication of recent anti-pp differential cross section measurements at 53 GeV on our previous calculations is discussed
Directory of Open Access Journals (Sweden)
Sofiane Khachroumi
2010-01-01
Full Text Available Sensor technology is moving towards wide-band-gap semiconductors providing high temperature capable devices. Indeed, the higher thermal conductivity of silicon carbide, (three times more than silicon, permits better heat dissipation and allows better cooling and temperature management. Though many temperature sensors have already been published, little endeavours have been invested in the study of silicon carbide junction field effect devices (SiC-JFET as a temperature sensor. SiC-JFETs devices are now mature enough and it is close to be commercialized. The use of its specific properties versus temperatures is the major focus of this paper. The SiC-JFETs output current-voltage characteristics are characterized at different temperatures. The saturation current and its on-resistance versus temperature are successfully extracted. It is demonstrated that these parameters are proportional to the absolute temperature. A physics-based model is also presented. Relationships between on-resistance and saturation current versus temperature are introduced. A comparative study between experimental data and simulation results is conducted. Important to note, the proposed model and the experimental results reflect a successful agreement as far as a temperature sensor is concerned.
International Nuclear Information System (INIS)
Spirito, Flavia; Capt, Annabelle; Rio, Marcela Del; Larcher, Fernando; Guaguere, Eric; Danos, Olivier; Meneguzzi, Guerrino
2006-01-01
Gene transfer represents the unique therapeutic issue for a number of inherited skin disorders including junctional epidermolysis bullosa (JEB), an untreatable genodermatose caused by mutations in the adhesion ligand laminin 5 (α3β3γ2) that is secreted in the extracellular matrix by the epidermal basal keratinocytes. Because gene therapy protocols require validation in animal models, we have phenotypically reverted by oncoretroviral transfer of the curative gene the keratinocytes isolated from dogs with a spontaneous form of JEB associated with a genetic mutation in the α3 chain of laminin 5. We show that the transduced dog JEB keratinocytes: (1) display a sustained secretion of laminin 5 in the extracellular matrix; (2) recover the adhesion, proliferation, and clonogenic capacity of wild-type keratinocytes; (3) generate fully differentiated stratified epithelia that after grafting on immunocompromised mice produce phenotypically normal skin and sustain permanent expression of the transgene. We validate an animal model that appears particularly suitable to demonstrate feasibility, efficacy, and safety of genetic therapeutic strategies for cutaneous disorders before undertaking human clinical trials
Yang, Bo; Tong, Yuting
2017-04-01
With the rapid development of economy, the development of logistics enterprises in China is also facing a huge challenge, especially the logistics enterprises generally lack of core competitiveness, and service innovation awareness is not strong. Scholars in the process of studying the core competitiveness of logistics enterprises are mainly from the perspective of static stability, not from the perspective of dynamic evolution to explore. So the author analyzes the influencing factors and the evolution process of the core competence of logistics enterprises, using the method of system dynamics to study the cause and effect of the evolution of the core competence of logistics enterprises, construct a system dynamics model of evolution of core competence logistics enterprises, which can be simulated by vensim PLE. The analysis for the effectiveness and sensitivity of simulation model indicates the model can be used as the fitting of the evolution process of the core competence of logistics enterprises and reveal the process and mechanism of the evolution of the core competence of logistics enterprises, and provide management strategies for improving the core competence of logistics enterprises. The construction and operation of computer simulation model offers a kind of effective method for studying the evolution of logistics enterprise core competence.
Modeling the Power Variability of Core Speed Scaling on Homogeneous Multicore Systems
Directory of Open Access Journals (Sweden)
Zhihui Du
2017-01-01
Full Text Available We describe a family of power models that can capture the nonuniform power effects of speed scaling among homogeneous cores on multicore processors. These models depart from traditional ones, which assume that individual cores contribute to power consumption as independent entities. In our approach, we remove this independence assumption and employ statistical variables of core speed (average speed and the dispersion of the core speeds to capture the comprehensive heterogeneous impact of subtle interactions among the underlying hardware. We systematically explore the model family, deriving basic and refined models that give progressively better fits, and analyze them in detail. The proposed methodology provides an easy way to build power models to reflect the realistic workings of current multicore processors more accurately. Moreover, unlike the existing lower-level power models that require knowledge of microarchitectural details of the CPU cores and the last level cache to capture core interdependency, ours are easier to use and scalable to emerging and future multicore architectures with more cores. These attributes make the models particularly useful to system users or algorithm designers who need a quick way to estimate power consumption. We evaluate the family of models on contemporary x86 multicore processors using the SPEC2006 benchmarks. Our best model yields an average predicted error as low as 5%.
Organizational Models for Non-Core Processes Management: A Classification Framework
Directory of Open Access Journals (Sweden)
Alberto F. De Toni
2012-12-01
The framework enables the identification and the explanation of the main advantages and disadvantages of each strategy and to highlight how a company should coherently choose an organizational model on the basis of: (a the specialization/complexity of the non‐core processes, (b the focus on core processes, (c its inclination towards know‐how outsourcing, and (d the desired level of autonomy in the management of non‐core processes.
Transformer core modeling for magnetizing inrush current investigation
Directory of Open Access Journals (Sweden)
A.Yahiou
2014-03-01
Full Text Available The inrush currents generated during an energization of power transformer can reach very high values and may cause many problems in power system. This magnetizing inrush current which occurs at the time of energization of a transformer is due to temporary overfluxing in the transformer core. Its magnitude mainly depends on switching parameters such as the resistance of the primary winding and the point-on-voltage wave (switching angle. This paper describes a system for measuring the inrush current which is composed principally of an acquisition card (EAGLE, and LabVIEW code. The system is also capable of presetting various combinations of switching parameters for the energization of a 2 kVA transformer via an electronic card. Moreover, an algorithm for calculating the saturation curve is presented taking the iron core reactive losses into account, thereby producing a nonlinear inductance. This curve is used to simulate the magnetizing inrush current using the ATP-EMTP software.
International Nuclear Information System (INIS)
Saas, L.; Le Tellier, R.; Bajard, S.
2015-01-01
In this document, we present a simplified geometrical model (0D model) for both the in-core corium propagation transient and the characterization of the mode of corium transfer from the core to the vessel. A degraded core with a formed corium pool is used as an initial state. This initial state can be obtained from a simulation computed with an integral code. This model does not use a grid for the core as integral codes do. Geometrical shapes and 0D models are associated with the corium pool and the other components of the degraded core (debris, heavy reflector, core plate...). During the transient, these shapes evolve taking into account the thermal and stratification behavior of the corium pool and the melting of the core surrounding components. Some results corresponding to the corium pool propagation in core transients obtained with this model on a LWR with a heavy reflector are given and compared to grid approach of the integral codes MAAP4
Jakeman, A. J.; Elsawah, S.; Pierce, S. A.; Ames, D. P.
2016-12-01
The National Socio-Environmental Synthesis Center (SESYNC) Core Modelling Practices Pursuit is developing resources to describe core practices for developing and using models to support integrated water resource management. These practices implement specific steps in the modelling process with an interdisciplinary perspective; however, the particular practice that is most appropriate depends on contextual aspects specific to the project. The first task of the pursuit is to identify the various steps for which implementation practices are to be described. This paper reports on those results. The paper draws on knowledge from the modelling process literature for environmental modelling (Jakeman et al., 2006), engaging stakeholders (Voinov and Bousquet, 2010) and general modelling (Banks, 1999), as well as the experience of the consortium members. We organise the steps around the four modelling phases. The planning phase identifies what is to be achieved, how and with what resources. The model is built and tested during the construction phase, and then used in the application phase. Finally, models that become part of the ongoing policy process require a maintenance phase. For each step, the paper focusses on what is to be considered or achieved, rather than how it is performed. This reflects the separation of the steps from the practices that implement them in different contexts. We support description of steps with a wide range of examples. Examples are designed to be generic and do not reflect any one project or context, but instead are drawn from common situations or from extremely different ones so as to highlight some of the issues that may arise at each step. References Banks, J. (1999). Introduction to simulation. In Proceedings of the 1999 Winter Simulation Conference. Jakeman, A. J., R. A. Letcher, and J. P. Norton (2006). Ten iterative steps in development and evaluation of environmental models. Environmental Modelling and Software 21, 602-614. Voinov, A
Qin, Ning; Wen, John Z.; Ren, Carolyn L.
2017-04-01
This is the second part of a two-part study on a partially miscible liquid-liquid flow (carbon dioxide and deionized water) that is highly pressurized and confined in a microfluidic T-junction. In the first part of this study, we reported experimental observations of the development of flow regimes under various flow conditions and the quantitative characteristics of the drop flow including the drop length, after-generation drop speed, and periodic spacing development between an emerging drop and the newly produced one. Here in part II we provide theoretical justifications to our quantitative studies on the drop flow by considering (1) C O2 hydration at the interface with water, (2) the diffusion-controlled dissolution of C O2 molecules in water, and (3) the diffusion distance of the dissolved C O2 molecules. Our analyses show that (1) the C O2 hydration at the interface is overall negligible, (2) a saturation scenario of the dissolved C O2 molecules in the vicinity of the interface will not be reached within the contact time between the two fluids, and (3) molecular diffusion does play a role in transferring the dissolved molecules, but the diffusion distance is very limited compared with the channel geometry. In addition, mathematical models for the drop length and the drop spacing are developed based on the observations in part I, and their predictions are compared to our experimental results.
Geodynamical simulation of the RRF triple junction
Wang, Z.; Wei, D.; Liu, M.; Shi, Y.; Wang, S.
2017-12-01
Triple junction is the point at which three plate boundaries meet. Three plates at the triple junction form a complex geological tectonics, which is a natural laboratory to study the interactions of plates. This work studies a special triple junction, the oceanic transform fault intersects the collinear ridges with different-spreading rates, which is free of influence of ridge-transform faults and nearby hotspots. First, we build 3-D numerical model of this triple junction used to calculate the stead-state velocity and temperature fields resulting from advective and conductive heat transfer. We discuss in detail the influence of the velocity and temperature fields of the triple junction from viscosity, spreading rate of the ridge. The two sides of the oceanic transform fault are different sensitivities to the two factors. And, the influence of the velocity mainly occurs within 200km of the triple junction. Then, we modify the model by adding a ridge-transform fault to above model and directly use the velocity structure of the Macquarie triple junction. The simulation results show that the temperature at both sides of the oceanic transform fault decreases gradually from the triple junction, but the temperature difference between the two sides is a constant about 200°. And, there is little effect of upwelling velocity away from the triple junction 100km. The model results are compared with observational data. The heat flux and thermal topography along the oceanic transform fault of this model are consistent with the observed data of the Macquarie triple junction. The earthquakes are strike slip distributed along the oceanic transform fault. Their depths are also consistent with the zone of maximum shear stress. This work can help us to understand the interactions of plates of triple junctions and help us with the foundation for the future study of triple junctions.
Josephson junctions with ferromagnetic interlayer
International Nuclear Information System (INIS)
Wild, Georg Hermann
2012-01-01
We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO x /Pd 0.82 Ni 0.18 /Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to π-coupling is observed for a thickness d F =6 nm of the ferromagnetic Pd 0.82 Ni 0.18 interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd 0.82 Ni 0.18 has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.
Josephson junctions with ferromagnetic interlayer
Energy Technology Data Exchange (ETDEWEB)
Wild, Georg Hermann
2012-03-04
We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.
F.B.R. Core mock-up RAPSODIE - II - numerical models
International Nuclear Information System (INIS)
Brochard, D.; Hammami, L.; Gantenbein, F.
1990-01-01
To study the behaviour of LMFBR cores excited by a seism, tests have been performed on the RAPSODIE core mock-up. The aim of this paper is to present the numerical models used to interprete these tests and the comparisons between calculations and experimental results
Discussion about modeling the effects of neutron flux exposure for nuclear reactor core analysis
International Nuclear Information System (INIS)
Vondy, D.R.
1986-04-01
Methods used to calculate the effects of exposure to a neutron flux are described. The modeling of the nuclear-reactor core history presents an analysis challenge. The nuclide chain equations must be solved, and some of the methods in use for this are described. Techniques for treating reactor-core histories are discussed and evaluated
Modelling of reactor control and protection systems in the core simulator program GARLIC
International Nuclear Information System (INIS)
Beraha, D.; Lupas, O.; Ploegert, K.
1984-01-01
For analysis of the interaction between control and limitation systems and the power distribution in the reactor core, a valuable tool is provided by the joint simulation of the core and the interacting systems. To this purpose, the core simulator GARLIC has been enhanced by models of the systems for controlling and limiting the reactor power and the power distribution in the core as well as by modules for calculating safety related core parameters. The computer-based core protection system, first installed in the Grafenrheinfeld NPP, has been included in the simulation. In order to evaluate the accuracy of GARLIC-simulations, the code has been compared with a design code in the train of a verification phase. The report describes the program extensions and the results of the verification. (orig.) [de
A macroscopic cross-section model for BWR pin-by-pin core analysis
International Nuclear Information System (INIS)
Fujita, Tatsuya; Endo, Tomohiro; Yamamoto, Akio
2014-01-01
A macroscopic cross-section model used in boiling water reactor (BWR) pin-by-pin core analysis is studied. In the pin-by-pin core calculation method, pin-cell averaged cross sections are calculated for many combinations of core state and depletion history variables and are tabulated prior to core calculations. Variations of cross sections in a core simulator are caused by two different phenomena (i.e. instantaneous and history effects). We treat them through the core state variables and the exposure-averaged core state variables, respectively. Furthermore, the cross-term effect among the core state and the depletion history variables is considered. In order to confirm the calculation accuracy and discuss the treatment of the cross-term effect, the k-infinity and the pin-by-pin fission rate distributions in a single fuel assembly geometry are compared. Some cross-term effects could be negligible since the impacts of them are sufficiently small. However, the cross-term effects among the control rod history (or the void history) and other variables have large impacts; thus, the consideration of them is crucial. The present macroscopic cross-section model, which considers such dominant cross-term effects, well reproduces the reference results and can be a candidate in practical applications for BWR pin-by-pin core analysis on the normal operations. (author)
Hysteresis development in superconducting Josephson junctions
International Nuclear Information System (INIS)
Refai, T.F.; Shehata, L.N.
1988-09-01
The resistively and capacitive shunted junction model is used to investigate hysteresis development in superconducting Josephson junctions. Two empirical formulas that relate the hysteresis width and the quasi-particle diffusion length in terms of the junctions electrical parameters, temperature and frequency are obtained. The obtained formulas provide a simple tool to investigate the full potentials of the hysteresis phenomena. (author). 9 refs, 3 figs
Core-shell particles as model compound for studying fouling
DEFF Research Database (Denmark)
Christensen, Morten Lykkegaard; Nielsen, Troels Bach; Andersen, Morten Boel Overgaard
2008-01-01
Synthetic colloidal particles with hard cores and soft, water-swollen shells were used to study cake formation during ultrafiltration. The total cake resistance was lowest for particles with thick shells, which indicates that interparticular forces between particles (steric hindrance...... and electrostatic repulsion) influenced cake formation. At low pressure the specific cake resistance could be predicted from the Kozeny-Carman equation. At higher pressures, the resistance increased due to cake compression. Both cake formation and compression were reversible. For particles with thick shells...
Thermal stability analysis and modelling of advanced perpendicular magnetic tunnel junctions
Van Beek, Simon; Martens, Koen; Roussel, Philippe; Wu, Yueh Chang; Kim, Woojin; Rao, Siddharth; Swerts, Johan; Crotti, Davide; Linten, Dimitri; Kar, Gouri Sankar; Groeseneken, Guido
2018-05-01
STT-MRAM is a promising non-volatile memory for high speed applications. The thermal stability factor (Δ = Eb/kT) is a measure for the information retention time, and an accurate determination of the thermal stability is crucial. Recent studies show that a significant error is made using the conventional methods for Δ extraction. We investigate the origin of the low accuracy. To reduce the error down to 5%, 1000 cycles or multiple ramp rates are necessary. Furthermore, the thermal stabilities extracted from current switching and magnetic field switching appear to be uncorrelated and this cannot be explained by a macrospin model. Measurements at different temperatures show that self-heating together with a domain wall model can explain these uncorrelated Δ. Characterizing self-heating properties is therefore crucial to correctly determine the thermal stability.
Park, Hyun Sook; Jung, Sun Young
2013-12-01
This study was done to provide fundamental data for the development of competency reinforcement programs to prevent addictive behavior in adolescents through the construction and examination of an addiction prevention core competency model. In this study core competencies for preventing addictive behavior in adolescents through competency modeling were identified, and the addiction prevention core competency model was developed. It was validated methodologically. Competencies for preventing addictive behavior in adolescents as defined by the addiction prevention core competency model are as follows: positive self-worth, self-control skill, time management skill, reality perception skill, risk coping skill, and positive communication with parents and with peers or social group. After construction, concurrent cross validation of the addiction prevention core competency model showed that this model was appropriate. The study results indicate that the addiction prevention core competency model for the prevention of addictive behavior in adolescents through competency modeling can be used as a foundation for an integral approach to enhance adolescent is used as an adjective and prevent addictive behavior. This approach can be a school-centered, cost-efficient strategy which not only reduces addictive behavior in adolescents, but also improves the quality of their resources.
Directory of Open Access Journals (Sweden)
Hegazy Rezk
2015-09-01
Full Text Available This paper presents a new Matlab/Simulink model of a PV module and a maximum power point tracking (MPPT system for high efficiency InGaP/InGaAs/Ge triple-junction solar cell. The proposed technique is based on Artificial Neural Network. The equivalent circuit model of the triple-junction solar cell includes the parameters of each sub-cell. It is also include the effect of the temperature variations on the energy gap of each sub-cell as well as the diode reverse saturation currents. The implementation of a PV model is based on the triple-junction solar cell in the form of masked block in Matlab/Simulink software package that has a user-friendly icon and dialog. It is fast and accurate technique to follow the maximum power point. The simulation results of the proposed MPPT technique are compared with Perturb and Observe MPPT technique. The output power and energy of the proposed technique are higher than that of the Perturb and Observe MPPT technique. The proposed technique increases the output energy per day for a one PV module from 3.37 kW h to 3.75 kW h, i.e. a percentage of 11.28%.
Directory of Open Access Journals (Sweden)
Xu L
2015-09-01
Full Text Available Liming Xu,1,2,* Mo Dan,1,* Anliang Shao,1 Xiang Cheng,1,3 Cuiping Zhang,4 Robert A Yokel,5 Taro Takemura,6 Nobutaka Hanagata,6 Masami Niwa,7,8 Daisuke Watanabe7,81National Institutes for Food and Drug Control, No 2, Temple of Heaven, Beijing, 2School of Information and Engineering, Wenzhou Medical University, Wenzhou, 3School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, 4Beijing Neurosurgical Institute, Capital Medical University, Beijing, People’s Republic of China; 5College of Pharmacy, University of Kentucky, Lexington, KY, USA; 6Nanotechnology Innovation Station for Nanoscale Science and Technology, National Institute for Materials Science, Tsukuba, Ibaraki, 7Department of Pharmacology, Nagasaki University, 8BBB Laboratory, PharmaCo-Cell Company, Ltd., Nagasaki, Japan*These authors contributed equally to this workBackground: Silver nanoparticles (Ag-NPs can enter the brain and induce neurotoxicity. However, the toxicity of Ag-NPs on the blood–brain barrier (BBB and the underlying mechanism(s of action on the BBB and the brain are not well understood.Method: To investigate Ag-NP suspension (Ag-NPS-induced toxicity, a triple coculture BBB model of rat brain microvascular endothelial cells, pericytes, and astrocytes was established. The BBB permeability and tight junction protein expression in response to Ag-NPS, NP-released Ag ions, and polystyrene-NP exposure were investigated. Ultrastructural changes of the microvascular endothelial cells, pericytes, and astrocytes were observed using transmission electron microscopy (TEM. Global gene expression of astrocytes was measured using a DNA microarray.Results: A triple coculture BBB model of primary rat brain microvascular endothelial cells, pericytes, and astrocytes was established, with the transendothelial electrical resistance values >200 Ω·cm2. After Ag-NPS exposure for 24 hours, the BBB permeability was significantly increased and expression of the
Improvement of Axial Reflector Cross Section Generation Model for PWR Core Analysis
Energy Technology Data Exchange (ETDEWEB)
Shim, Cheon Bo; Lee, Kyung Hoon; Cho, Jin Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-10-15
This paper covers the study for improvement of axial reflector XS generation model. In the next section, the improved 1D core model is represented in detail. Reflector XS generated by the improved model is compared to that of the conventional model in the third section. Nuclear design parameters generated by these two XS sets are also covered in that section. Significant of this study is discussed in the last section. Two-step procedure has been regarded as the most practical approach for reactor core designs because it offers core design parameters quite rapidly within acceptable range. Thus this approach is adopted for SMART (System-integrated Modular Advanced Reac- Tor) core design in KAERI with the DeCART2D1.1/ MASTER4.0 (hereafter noted as DeCART2D/ MASTER) code system. Within the framework of the two-step procedure based SMART core design, various researches have been studied to improve the core design reliability and efficiency. One of them is improvement of reflector cross section (XS) generation models. While the conventional FA/reflector two-node model used for most core designs to generate reflector XS cannot consider the actual configuration of fuel rods that intersect at right angles to axial reflectors, the revised model reflects the axial fuel configuration by introducing the radially simplified core model. The significance of the model revision is evaluated by observing HGC generated by DeCART2D, reflector XS, and core design parameters generated by adopting the two models. And it is verified that about 30 ppm CBC error can be reduced and maximum Fq error decreases from about 6 % to 2.5 % by applying the revised model. Error of AO and axial power shapes are also reduced significantly. Therefore it can be concluded that the simplified 1D core model improves the accuracy of the axial reflector XS and leads to the two-step procedure reliability enhancement. Since it is hard for core designs to be free from the two-step approach, it is necessary to find
Interfacing high-fidelity core neutronics models to whole plant models
International Nuclear Information System (INIS)
McEllin, M.
1999-01-01
Until recently available computer power dictated that whole-plant models of nuclear power stations have typically employed simple models of the reactor core which can not match the fidelity of safety-qualified 2-group, 3D neutronics models. As a result the treatment of situations involving strong coupling between the core and the rest of the plant has inevitably been somewhat approximate, requiring conservative modelling assumptions, or manual iteration between cases, to bound worse case scenarios. Such techniques not only place heavy demands on the engineers involved, they may also result in potentially unnecessary operational constraints. Hardware is today no longer the limiting factor, but the cost of developing and validating high-quality software is now such that it appears attractive to build new systems with a wider simulation scope by using existing stand-alone codes as sub-components. This is not always as straightforward as it might at first appear. This paper illustrates some of the pitfalls, and discusses more sophisticated and robust strategies. (author)
Fisher, Dahlia; Yaniawati, Poppy; Kusumah, Yaya Sukjaya
2017-08-01
This study aims to analyze the character of students who obtain CORE learning model using metacognitive approach. The method in this study is qualitative research and quantitative research design (Mixed Method Design) with concurrent embedded strategy. The research was conducted on two groups: an experimental group and the control group. An experimental group consists of students who had CORE model learning using metacognitive approach while the control group consists of students taught by conventional learning. The study was conducted the object this research is the seventh grader students in one the public junior high schools in Bandung. Based on this research, it is known that the characters of the students in the CORE model learning through metacognitive approach is: honest, hard work, curious, conscientious, creative and communicative. Overall it can be concluded that CORE model learning is good for developing characters of a junior high school student.
Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell Model
Energy Technology Data Exchange (ETDEWEB)
Roth, R; Navratil, P
2007-05-22
We propose an importance truncation scheme for the no-core shell model, which enables converged calculations for nuclei well beyond the p-shell. It is based on an a priori measure for the importance of individual basis states constructed by means of many-body perturbation theory. Only the physically relevant states of the no-core model space are considered, which leads to a dramatic reduction of the basis dimension. We analyze the validity and efficiency of this truncation scheme using different realistic nucleon-nucleon interactions and compare to conventional no-core shell model calculations for {sup 4}He and {sup 16}O. Then, we present the first converged calculations for the ground state of {sup 40}Ca within no-core model spaces including up to 16{h_bar}{Omega}-excitations using realistic low-momentum interactions. The scheme is universal and can be easily applied to other quantum many-body problems.
Jia, X.; Slavin, J.; Chen, Y.; Poh, G.; Toth, G.; Gombosi, T.
2018-05-01
We present results from state-of-the-art global models of Mercury's space environment capable of self-consistently simulating the induction effect at the core and resolving kinetic physics important for magnetic reconnection.
International Nuclear Information System (INIS)
Boyadjiev, T.L.; Semerdjieva, E.G.; Shukrinov, Yu.M.
2007-01-01
We study the vortex structure in three different models of the long Josephson junction: the exponentially shaped Josephson junction and the Josephson junctions with the resistor and the shunt inhomogeneities in the barrier layer. For these three models the critical curves 'critical current-magnetic field' are numerically constructed. We develop the idea of the equivalence of the exponentially shaped Josephson junction and the rectangular junction with the distributed inhomogeneity and demonstrate that at some parameters of the shunt and the resistor inhomogeneities in the ends of the junction the corresponding critical curves are very close to the exponentially shaped one
The human myotendinous junction
DEFF Research Database (Denmark)
Knudsen, A B; Larsen, M; Mackey, Abigail
2015-01-01
The myotendinous junction (MTJ) is a specialized structure in the musculotendinous system, where force is transmitted from muscle to tendon. Animal models have shown that the MTJ takes form of tendon finger-like processes merging with muscle tissue. The human MTJ is largely unknown and has never...... been described in three dimensions (3D). The aim of this study was to describe the ultrastructure of the human MTJ and render 3D reconstructions. Fourteen subjects (age 25 ± 3 years) with isolated injury of the anterior cruciate ligament (ACL), scheduled for reconstruction with a semitendinosus...
Adjustment of cast metal post/cores modeled with different acrylic resins
Gusmão, João Milton Rocha; Pereira, Renato Piai; Alves, Guilhermino Oliveira; Pithon, Matheus Melo; Moreira, David Costa
2016-01-01
Aim: Evaluate the performance of four commercially available chemically-activated acrylic resins (CAARs) by measuring the level of displacement of the cores following casting. Materials and Methods: Two devices were constructed to model the cores based on a natural tooth. Forty post/cores were modeled, 10 in each of the following CAARs: Duralay (Reliance Dental, Illinois, USA), Pattern Resin (GC, Tokyo, Japan), Dencrilay (Dencril, Sao Paulo, Brazil), and Jet (Clássico, Sao Paulo, Brazil). Two...
Study and application of microscopic depletion model in core simulator of COSINE project
International Nuclear Information System (INIS)
Hu Xiaoyu; Wang Su; Yan Yuhang; Liu Zhanquan; Chen Yixue; Huang Kai
2013-01-01
Microscopic depletion correction is one of the commonly used techniques that could improve the historical effect and attain higher precision of diffusion calculation and alleviate the inaccuracy caused by historical effect. Core simulator of COSINE project (core and system integrated engine for design and analysis) has developed a hybrid macroscopic-microscopic depletion model to track important isotopes during each depletion history and correct the macro cross sections. The basic theory was discussed in this paper. The effect and results of microscopic depletion correction were also analyzed. The preliminary test results demonstrate that the microscopic depletion model is effective and practicable for improving the precision of core calculation. (authors)
Molecular electronic junction transport
DEFF Research Database (Denmark)
Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark
2012-01-01
Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...
Directory of Open Access Journals (Sweden)
Sifeu Takougang Kingni
2017-01-01
Full Text Available A linear resistive-capacitive-inductance shunted junction (LRCLSJ model obtained by replacing the nonlinear piecewise resistance of a nonlinear resistive-capacitive-inductance shunted junction (NRCLSJ model by a linear resistance is analyzed in this paper. The LRCLSJ model has two or no equilibrium points depending on the dc bias current. For a suitable choice of the parameters, the LRCLSJ model without equilibrium point can exhibit regular and fast spiking, intrinsic and periodic bursting, and periodic and chaotic behaviors. We show that the LRCLSJ model displays similar dynamical behaviors as the NRCLSJ model. Moreover the coexistence between periodic and chaotic attractors is found in the LRCLSJ model for specific parameters. The lowest order of the commensurate form of the no equilibrium LRCLSJ model to exhibit chaotic behavior is found to be 2.934. Moreover, adaptive finite-time synchronization with parameter estimation is applied to achieve synchronization of unidirectional coupled identical fractional-order form of chaotic no equilibrium LRCLSJ models. Finally, a cryptographic encryption scheme with the help of the finite-time synchronization of fractional-order chaotic no equilibrium LRCLSJ models is illustrated through a numerical example, showing that a high level security device can be produced using this system.
International Nuclear Information System (INIS)
Landau, A.; Nitzan, A.
2006-01-01
Full Text: Molecular electronics, one of the major fields of the current effort in nano-science, may be de ed as the study of electronic behaviors, devices and applications that depend on the properties of matter at the molecular scale. If the miniaturization trend of microelectronic devices is to continue, elements such as transistors and contacts will soon shrink to single molecules. The promise of these new technological breakthroughs has been major driving force in this ld. Moreover, the consideration of molecular systems as electronic devices has raised new fundamental questions. In particular, while traditional quantum chemistry deals with electronically closed systems, we now face problems involving molecular systems that are open to their electronic environment, moreover, function in far from equilibrium situations. A generic molecular junction is made of two electrodes connected by a molecular spacer that takes the form of a molecular chain of varying length or a molecular layer of varying thickness. We use a simple nearest-neighbors tight-biding model with the non-equilibrium Green's function (NEGF) method to investigate and compare between a self-assembled monolayer (SAM), finite molecular layer (FML), and single molecule (SM) chemisorption to a surface of a metal substrate. In addition, we examine the difference in the transmission probability through a SAM, FML and SM sandwiched between two metallic electrodes. Dramatic differences are observed between the SM, FML and SAM density of electronic states and transmission functions. In addition, we analyze the effects of changing different physical parameters such as molecule-substrate interaction, molecule-molecule interactions, etc; interesting effects that pertain to the conduction properties of single molecules and molecular layers are observed. Intriguing results are attained when we investigate the commensurability of the SAM with the metallic surface
Martínez-Rendón, Jacqueline; Sánchez-Guzmán, Erika; Rueda, Angélica; González, James; Gulias-Cañizo, Rosario; Aquino-Jarquín, Guillermo; Castro-Muñozledo, Federico; García-Villegas, Refugio
2017-07-01
TRPV4 (transient receptor potential vanilloid 4) is a cation channel activated by hypotonicity, moderate heat, or shear stress. We describe the expression of TRPV4 during the differentiation of a corneal epithelial cell model, RCE1(5T5) cells. TRPV4 is a late differentiation feature that is concentrated in the apical membrane of the outmost cell layer of the stratified epithelia. Ca 2+ imaging experiments showed that TRPV4 activation with GSK1016790A produced an influx of calcium that was blunted by the specific TRPV4 blocker RN-1734. We analyzed the involvement of TRPV4 in RCE1(5T5) epithelial differentiation by measuring the development of transepithelial electrical resistance (TER) as an indicator of the tight junction (TJ) assembly. We showed that TRPV4 activity was necessary to establish the TJ. In differentiated epithelia, activation of TRPV4 increases the TER and the accumulation of claudin-4 in cell-cell contacts. Epidermal Growth Factor (EGF) up-regulates the TER of corneal epithelial cultures, and we show here that TRPV4 activation mimicked this EGF effect. Conversely, TRPV4 inhibition or knock down by specific shRNA prevented the increase in TER. Moreover, TRPP2, an EGF-activated channel that forms heteromeric complexes with TRPV4, is also concentrated in the outmost cell layer of differentiated RCE1(5T5) sheets. This suggests that the EGF regulation of the TJ may involve a heterotetrameric TRPV4-TRPP2 channel. These results demonstrated TRPV4 activity was necessary for the correct establishment of TJ in corneal epithelia and as well as the regulation of both the barrier function of TJ and its ability to respond to EGF. J. Cell. Physiol. 232: 1794-1807, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Westerhold, Thomas; Röhl, Ursula; Wilkens, Roy H.; Gingerich, Philip D.; Clyde, William C.; Wing, Scott L.; Bowen, Gabriel J.; Kraus, Mary J.
2018-03-01
A consistent chronostratigraphic framework is required to understand the effect of major paleoclimate perturbations on both marine and terrestrial ecosystems. Transient global warming events in the early Eocene, at 56-54 Ma, show the impact of large-scale carbon input into the ocean-atmosphere system. Here we provide the first timescale synchronization of continental and marine deposits spanning the Paleocene-Eocene Thermal Maximum (PETM) and the interval just prior to the Eocene Thermal Maximum 2 (ETM-2). Cyclic variations in geochemical data come from continental drill cores of the Bighorn Basin Coring Project (BBCP, Wyoming, USA) and from marine deep-sea drilling deposits retrieved by the Ocean Drilling Program (ODP). Both are dominated by eccentricity-modulated precession cycles used to construct a common cyclostratigraphic framework. Integration of age models results in a revised astrochronology for the PETM in deep-sea records that is now generally consistent with independent 3He age models. The duration of the PETM is estimated at ˜ 200 kyr for the carbon isotope excursion and ˜ 120 kyr for the associated pelagic clay layer. A common terrestrial and marine age model shows a concurrent major change in marine and terrestrial biota ˜ 200 kyr before ETM-2. In the Bighorn Basin, the change is referred to as Biohorizon B and represents a period of significant mammalian turnover and immigration, separating the upper Haplomylus-Ectocion Range Zone from the Bunophorus Interval Zone and approximating the Wa-4-Wa-5 land mammal zone boundary. In sediments from ODP Site 1262 (Walvis Ridge), major changes in the biota at this time are documented by the radiation of a second generation of apical spine-bearing sphenolith species (e.g., S. radians and S. editus), the emergence of T. orthostylus, and the marked decline of D. multiradiatus.
Energy Technology Data Exchange (ETDEWEB)
Rouxelin, Pascal Nicolas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Strydom, Gerhard [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-09-01
Best-estimate plus uncertainty analysis of reactors is replacing the traditional conservative (stacked uncertainty) method for safety and licensing analysis. To facilitate uncertainty analysis applications, a comprehensive approach and methodology must be developed and applied. High temperature gas cooled reactors (HTGRs) have several features that require techniques not used in light-water reactor analysis (e.g., coated-particle design and large graphite quantities at high temperatures). The International Atomic Energy Agency has therefore launched the Coordinated Research Project on HTGR Uncertainty Analysis in Modeling to study uncertainty propagation in the HTGR analysis chain. The benchmark problem defined for the prismatic design is represented by the General Atomics Modular HTGR 350. The main focus of this report is the compilation and discussion of the results obtained for various permutations of Exercise I 2c and the use of the cross section data in Exercise II 1a of the prismatic benchmark, which is defined as the last and first steps of the lattice and core simulation phases, respectively. The report summarizes the Idaho National Laboratory (INL) best estimate results obtained for Exercise I 2a (fresh single-fuel block), Exercise I 2b (depleted single-fuel block), and Exercise I 2c (super cell) in addition to the first results of an investigation into the cross section generation effects for the super-cell problem. The two dimensional deterministic code known as the New ESC based Weighting Transport (NEWT) included in the Standardized Computer Analyses for Licensing Evaluation (SCALE) 6.1.2 package was used for the cross section evaluation, and the results obtained were compared to the three dimensional stochastic SCALE module KENO VI. The NEWT cross section libraries were generated for several permutations of the current benchmark super-cell geometry and were then provided as input to the Phase II core calculation of the stand alone neutronics Exercise
Development of the Monju core safety analysis numerical models by super-COPD code
International Nuclear Information System (INIS)
Yamada, Fumiaki; Minami, Masaki
2010-12-01
Japan Atomic Energy Agency constructed a computational model for safety analysis of Monju reactor core to be built into a modularized plant dynamics analysis code Super-COPD code, for the purpose of heat removal capability evaluation at the in total 21 defined transients in the annex to the construction permit application. The applicability of this model to core heat removal capability evaluation has been estimated by back to back result comparisons of the constituent models with conventionally applied codes and by application of the unified model. The numerical model for core safety analysis has been built based on the best estimate model validated by the actually measured plant behavior up to 40% rated power conditions, taking over safety analysis models of conventionally applied COPD and HARHO-IN codes, to be capable of overall calculations of the entire plant with the safety protection and control systems. Among the constituents of the analytical model, neutronic-thermal model, heat transfer and hydraulic models of PHTS, SHTS, and water/steam system are individually verified by comparisons with the conventional calculations. Comparisons are also made with the actually measured plant behavior up to 40% rated power conditions to confirm the calculation adequacy and conservativeness of the input data. The unified analytical model was applied to analyses of in total 8 anomaly events; reactivity insertion, abnormal power distribution, decrease and increase of coolant flow rate in PHTS, SHTS and water/steam systems. The resulting maximum values and temporal variations of the key parameters in safety evaluation; temperatures of fuel, cladding, in core sodium coolant and RV inlet and outlet coolant have negligible discrepancies against the existing analysis result in the annex to the construction permit application, verifying the unified analytical model. These works have enabled analytical evaluation of Monju core heat removal capability by Super-COPD utilizing the
Development of the core-model implementation technology for YGN1 simulator
International Nuclear Information System (INIS)
Hong, J. H.; Lee, M. S.; Lee, Y. K.; Su, I. Y.
2004-01-01
The existing core models for the domestic nuclear power plant simulators for PWRs are entirely imported from the foreign simulator vendor. To solve the time-accuracy problem in the poor capabilities in the computer in the early 1990s, several simplifications and assumptions for the neutronics governing equations were indispensible for the realtime calculations of nuclear phenomena in the core region. To overcome the shortages, a new core model based on the MASTER code certified by the domestic regulatory body (KINS) instead of the existing core models is now being developed especially for the realtime core solver for the YGN-1 simulator. This code is named R-MASTER (Realtime MASTER code). Due to the deficiency of the host computer, it is quitely required to run the R-MASTER code on the separate computer with high performance from the host computer on which all the other models than the core model are running. This paper deals with the applied protocols and procedures to guarantee the realtime communication and calculation of the R-MASTER code
Overall feature of EAST operation space by using simple Core-SOL-Divertor model
International Nuclear Information System (INIS)
Hiwatari, R.; Hatayama, A.; Zhu, S.; Takizuka, T.; Tomita, Y.
2005-01-01
We have developed a simple Core-SOL-Divertor (C-S-D) model to investigate qualitatively the overall features of the operational space for the integrated core and edge plasma. To construct the simple C-S-D model, a simple core plasma model of ITER physics guidelines and a two-point SOL-divertor model are used. The simple C-S-D model is applied to the study of the EAST operational space with lower hybrid current drive experiments under various kinds of trade-off for the basic plasma parameters. Effective methods for extending the operation space are also presented. As shown by this study for the EAST operation space, it is evident that the C-S-D model is a useful tool to understand qualitatively the overall features of the plasma operation space. (author)
Cavity syncronisation of underdamped Josephson junction arrays
DEFF Research Database (Denmark)
Barbara, P.; Filatrella, G.; Lobb, C.
2003-01-01
the junctions in the array and an electromagnetic cavity. Here we show that a model of a one-dimensional array of Josephson junctions coupled to a resonator can produce many features of the coherent be havior above threshold, including coherent radiation of power and the shape of the array current...
Validation of ASTEC core degradation and containment models
International Nuclear Information System (INIS)
Kruse, Philipp; Brähler, Thimo; Koch, Marco K.
2014-01-01
Ruhr-Universitaet Bochum performed in a German funded project validation of in-vessel and containment models of the integral code ASTEC V2, jointly developed by IRSN (France) and GRS (Germany). In this paper selected results of this validation are presented. In the in-vessel part, the main point of interest was the validation of the code capability concerning cladding oxidation and hydrogen generation. The ASTEC calculations of QUENCH experiments QUENCH-03 and QUENCH-11 show satisfactory results, despite of some necessary adjustments in the input deck. Furthermore, the oxidation models based on the Cathcart–Pawel and Urbanic–Heidrick correlations are not suitable for higher temperatures while the ASTEC model BEST-FIT based on the Prater–Courtright approach at high temperature gives reliable enough results. One part of the containment model validation was the assessment of three hydrogen combustion models of ASTEC against the experiment BMC Ix9. The simulation results of these models differ from each other and therefore the quality of the simulations depends on the characteristic of each model. Accordingly, the CPA FRONT model, corresponding to the simplest necessary input parameters, provides the best agreement to the experimental data
Gyro-Landau fluid model of tokamak core fluctuations
International Nuclear Information System (INIS)
Leboeuf, J.N.; Carreras, B.A.; Dominguez, N.; Hedrick, C.L.; Sidikman, K.L.; Lynch, V.E.; Drake, J.B.; Walker, D.W.
1992-01-01
Dissipative trapped electron modes (DTEM) may be one of the causes of deterioration of confinement in tokamak and stellatator plasmas. We have implemented a fluid model to study DTEM turbulence in slab geometry. The electron dynamics include in addition to the adiabatic part, a non-adiabatic piece modeled with an i-delta-type response. The ion dynamics include Landau damping and FLR corrections through Landau fluid approximate techniques and Pade approximants for Γ 0 (b)=I 0 (b)e -b . The model follows from the gyrokinetic equation. Evolution equations, which closely resemble those used in standard reduced MHD, are presented since these are better suited to non-linear calculations. The numerical results of radially resolved calculations will be discussed. A recently developed hybrid model, which consists of a gyrokinetic implementation for the ions using particles and the same description for the electron dynamics as in the fluid model, will also be presented
Experimental Study and Mathematical Modeling of Asphaltene Deposition Mechanism in Core Samples
Directory of Open Access Journals (Sweden)
Jafari Behbahani T.
2015-11-01
increased. The experimental results show that the amount of remaining asphaltene in carbonate core samples is higher than those in sandstone core samples. Also, SEM (Scanning Electron Microscopy micrographs of carbonate core samples showed the formation of large clusters of asphaltene in comparison with sandstone core samples during natural depletion. It can be seen from the modeling results that the proposed model based on the multilayer adsorption equilibrium mechanism and four material balance equations is more accurate than those obtained from the monolayer adsorption equilibrium adsorption mechanism and two material balance equations, and is in agreement with the experimental data of natural depletion reported in this work and with those reported in the literature.
NUCORE - A system for nuclear structure calculations with cluster-core models
International Nuclear Information System (INIS)
Heras, C.A.; Abecasis, S.M.
1982-01-01
Calculation of nuclear energy levels and their electromagnetic properties, modelling the nucleus as a cluster of a few particles and/or holes interacting with a core which in turn is modelled as a quadrupole vibrator (cluster-phonon model). The members of the cluster interact via quadrupole-quadrupole and pairing forces. (orig.)
Structure and thermodynamics of core-softened models for alcohols
International Nuclear Information System (INIS)
Munaò, Gianmarco; Urbic, Tomaz
2015-01-01
The phase behavior and the fluid structure of coarse-grain models for alcohols are studied by means of reference interaction site model (RISM) theory and Monte Carlo simulations. Specifically, we model ethanol and 1-propanol as linear rigid chains constituted by three (trimers) and four (tetramers) partially fused spheres, respectively. Thermodynamic properties of these models are examined in the RISM context, by employing closed formulæ for the calculation of free energy and pressure. Gas-liquid coexistence curves for trimers and tetramers are reported and compared with already existing data for a dimer model of methanol. Critical temperatures slightly increase with the number of CH 2 groups in the chain, while critical pressures and densities decrease. Such a behavior qualitatively reproduces the trend observed in experiments on methanol, ethanol, and 1-propanol and suggests that our coarse-grain models, despite their simplicity, can reproduce the essential features of the phase behavior of such alcohols. The fluid structure of these models is investigated by computing radial distribution function g ij (r) and static structure factor S ij (k); the latter shows the presence of a low−k peak at intermediate-high packing fractions and low temperatures, suggesting the presence of aggregates for both trimers and tetramers
Modeling the Formation of Giant Planet Cores I: Evaluating Key Processes
Levison, H. F.; Thommes, E.; Duncan, M. J.
2009-01-01
One of the most challenging problems we face in our understanding of planet formation is how Jupiter and Saturn could have formed before the the solar nebula dispersed. The most popular model of giant planet formation is the so-called 'core accretion' model. In this model a large planetary embryo formed first, mainly by two-body accretion. This is then followed by a period of inflow of nebular gas directly onto the growing planet. The core accretion model has an Achilles heel, namely the very...
The equivalent thermal conductivity of lattice core sandwich structure: A predictive model
International Nuclear Information System (INIS)
Cheng, Xiangmeng; Wei, Kai; He, Rujie; Pei, Yongmao; Fang, Daining
2016-01-01
Highlights: • A predictive model of the equivalent thermal conductivity was established. • Both the heat conduction and radiation were considered. • The predictive results were in good agreement with experiment and FEM. • Some methods for improving the thermal protection performance were proposed. - Abstract: The equivalent thermal conductivity of lattice core sandwich structure was predicted using a novel model. The predictive results were in good agreement with experimental and Finite Element Method results. The thermal conductivity of the lattice core sandwich structure was attributed to both core conduction and radiation. The core conduction caused thermal conductivity only relied on the relative density of the structure. And the radiation caused thermal conductivity increased linearly with the thickness of the core. It was found that the equivalent thermal conductivity of the lattice core sandwich structure showed a highly dependent relationship on temperature. At low temperatures, the structure exhibited a nearly thermal insulated behavior. With the temperature increasing, the thermal conductivity of the structure increased owing to radiation. Therefore, some attempts, such as reducing the emissivity of the core or designing multilayered structure, are believe to be of benefit for improving the thermal protection performance of the structure at high temperatures.
Competency Model 101. The Process of Developing Core Competencies.
Eichelberger, Lisa Wright; Hewlett, Peggy O'Neill
1999-01-01
The Mississippi Competency Model defines nurses' roles as provider (caregiver, teacher, counselor, advocate), professional (scholar, collaborator, ethicist, researcher), and manager (leader, facilitator, intrapreneur, decision maker, technology user) for four levels of nursing: licensed practical nurse, associate degree, bachelor's degree, and…
Modeling Snow Regime in Cores of Small Planetary Bodies
Boukaré, C. E.; Ricard, Y. R.; Parmentier, E.; Parman, S. W.
2017-12-01
Observations of present day magnetic field on small planetary bodies such as Ganymede or Mercury challenge our understanding of planetary dynamo. Several mechanisms have been proposed to explain the origin of magnetic fields. Among the proposed scenarios, one family of models relies on snow regime. Snow regime is supported by experimental studies showing that melting curves can first intersect adiabats in regions where the solidifying phase is not gravitationaly stable. First solids should thus remelt during their ascent or descent. The effect of the snow zone on magnetic field generation remains an open question. Could magnetic field be generated in the snow zone? If not, what is the depth extent of the snow zone? How remelting in the snow zone drive compositional convection in the liquid layer? Several authors have tackled this question with 1D-spherical models. Zhang and Schubert, 2012 model sinking of the dense phase as internally heated convection. However, to our knowledge, there is no study on the convection structure associated with sedimentation and phase change at planetary scale. We extend the numerical model developped in [Boukare et al., 2017] to model snow dynamics in 2D Cartesian geometry. We build a general approach for modeling double diffusive convection coupled with solid-liquid phase change and phase separation. We identify several aspects that may govern the convection structure of the solidifying system: viscosity contrast between the snow zone and the liquid layer, crystal size, rate of melting/solidification and partitioning of light components during phase change.
Junction and circuit fabrication
International Nuclear Information System (INIS)
Jackel, L.D.
1980-01-01
Great strides have been made in Josephson junction fabrication in the four years since the first IC SQUID meeting. Advances in lithography have allowed the production of devices with planar dimensions as small as a few hundred angstroms. Improved technology has provided ultra-high sensitivity SQUIDS, high-efficiency low-noise mixers, and complex integrated circuits. This review highlights some of the new fabrication procedures. The review consists of three parts. Part 1 is a short summary of the requirements on junctions for various applications. Part 2 reviews intergrated circuit fabrication, including tunnel junction logic circuits made at IBM and Bell Labs, and microbridge radiation sources made at SUNY at Stony Brook. Part 3 describes new junction fabrication techniques, the major emphasis of this review. This part includes a discussion of small oxide-barrier tunnel junctions, semiconductor barrier junctions, and microbridge junctions. Part 3 concludes by considering very fine lithography and limitations to miniaturization. (orig.)
The HTA core model: a novel method for producing and reporting health technology assessments
DEFF Research Database (Denmark)
Lampe, Kristian; Mäkelä, Marjukka; Garrido, Marcial Velasco
2009-01-01
OBJECTIVES: The aim of this study was to develop and test a generic framework to enable international collaboration for producing and sharing results of health technology assessments (HTAs). METHODS: Ten international teams constructed the HTA Core Model, dividing information contained...... for diagnostic technologies. Two Core HTAs were produced in parallel with developing the model, providing the first real-life testing of the Model and input for further development. The results of formal validation and public feedback were primarily positive. Development needs were also identified and considered....... An online Handbook is available. CONCLUSIONS: The HTA Core Model is a novel approach to HTA. It enables effective international production and sharing of HTA results in a structured format. The face validity of the Model was confirmed during the project, but further testing and refining are needed to ensure...
State space modeling of reactor core in a pressurized water reactor
Energy Technology Data Exchange (ETDEWEB)
Ashaari, A.; Ahmad, T.; M, Wan Munirah W. [Department of Mathematical Science, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Shamsuddin, Mustaffa [Institute of Ibnu Sina, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Abdullah, M. Adib [Swinburne University of Technology, Faculty of Engineering, Computing and Science, Jalan Simpang Tiga, 93350 Kuching, Sarawak (Malaysia)
2014-07-10
The power control system of a nuclear reactor is the key system that ensures a safe operation for a nuclear power plant. However, a mathematical model of a nuclear power plant is in the form of nonlinear process and time dependent that give very hard to be described. One of the important components of a Pressurized Water Reactor is the Reactor core. The aim of this study is to analyze the performance of power produced from a reactor core using temperature of the moderator as an input. Mathematical representation of the state space model of the reactor core control system is presented and analyzed in this paper. The data and parameters are taken from a real time VVER-type Pressurized Water Reactor and will be verified using Matlab and Simulink. Based on the simulation conducted, the results show that the temperature of the moderator plays an important role in determining the power of reactor core.
Matérn's hard core models of types I and II with arbitrary compact grains
DEFF Research Database (Denmark)
Kiderlen, Markus; Hörig, Mario
Matérn's classical hard core models can be interpreted as models obtained from a stationary marked Poisson process by dependent thinning. The marks are balls of fixed radius, and a point is retained when its associated ball does not hit any other balls (type I) or when its random birth time is st...... of this model with the process of intact grains of the dead leaves model and the Stienen model leads to analogous results for the latter....
International Nuclear Information System (INIS)
Kwon, Young Min; Lee, Yong Bum; Chang, Won Pyo; Haha, Do Hee
2002-01-01
The radial core expansion due to the structure temperature rise is one of major negative reactivity insertion mechanisms in metallic fueled reactor. Thermal expansion is a result of both the laws of nature and the particular core design and it causes negative reactivity feedback by the combination of increased core volume captures and increased core surface leakage. The simple radial core expansion reactivity feedback model developed for the SSC-K code was evaluated by the code-to-code comparison analysis. From the comparison results, it can be stated that the radial core expansion reactivity feedback model employed into the SSC-K code may be reasonably accurate in the UTOP analysis
Energy Technology Data Exchange (ETDEWEB)
Kwon, Young Min; Lee, Yong Bum; Chang, Won Pyo; Haha, Do Hee [KAERI, Taejon (Korea, Republic of)
2002-10-01
The radial core expansion due to the structure temperature rise is one of major negative reactivity insertion mechanisms in metallic fueled reactor. Thermal expansion is a result of both the laws of nature and the particular core design and it causes negative reactivity feedback by the combination of increased core volume captures and increased core surface leakage. The simple radial core expansion reactivity feedback model developed for the SSC-K code was evaluated by the code-to-code comparison analysis. From the comparison results, it can be stated that the radial core expansion reactivity feedback model employed into the SSC-K code may be reasonably accurate in the UTOP analysis.
Theoretical approach to the WWER core thermomechanical modelling
International Nuclear Information System (INIS)
Likhatchev, Y.; Troyanov, V.; Folomeev, V.; Demishonkov, A.
2003-01-01
The paper presents studies on the analysis of root causes of fuel assembly bowing under operating conditions; developing of a methodology for fuel assemblies thermomechanical simulation; developing of a calculation technique for thermomechanical modelling of the fuel assemblies bowing in operational conditions. Some examples of calculation results are given
International Nuclear Information System (INIS)
Oliveira, A.C.J.G. de; Andrade Lima, F.R. de
1989-01-01
The present work is an application of the perturbation theory (Matricial formalism) to a simplified two channels model, for sensitivity calculations in PWR cores. Expressions for some sensitivity coefficients of thermohydraulic interest were developed from the proposed model. The code CASNUR.FOR was written in FORTRAN to evaluate these sensitivity coefficients. The comparison between results obtained from the matrical formalism of pertubation theory with those obtained directly from the two channels model, makes evident the efficiency and potentiality of this perturbation method for nuclear reactor cores sensitivity calculations. (author) [pt
Long Josephson Junction Stack Coupled to a Cavity
DEFF Research Database (Denmark)
Madsen, Søren Peder; Pedersen, Niels Falsig; Groenbech-Jensen, N.
2007-01-01
A stack of inductively coupled long Josephson junctions are modeled as a system of coupled sine-Gordon equations. One boundary of the stack is coupled electrically to a resonant cavity. With one fluxon in each Josephson junction, the inter-junction fluxon forces are repulsive. We look at a possible...... transition, induced by the cavity, to a bunched state....
Ellis, Matthew O. A.; Stamenova, Maria; Sanvito, Stefano
2017-12-01
There exists a significant challenge in developing efficient magnetic tunnel junctions with low write currents for nonvolatile memory devices. With the aim of analyzing potential materials for efficient current-operated magnetic junctions, we have developed a multi-scale methodology combining ab initio calculations of spin-transfer torque with large-scale time-dependent simulations using atomistic spin dynamics. In this work we introduce our multiscale approach, including a discussion on a number of possible schemes for mapping the ab initio spin torques into the spin dynamics. We demonstrate this methodology on a prototype Co/MgO/Co/Cu tunnel junction showing that the spin torques are primarily acting at the interface between the Co free layer and MgO. Using spin dynamics we then calculate the reversal switching times for the free layer and the critical voltages and currents required for such switching. Our work provides an efficient, accurate, and versatile framework for designing novel current-operated magnetic devices, where all the materials details are taken into account.
A model for the design and programming of multi-cores
Jesshope, C.; Grandinetti, L.
2008-01-01
This paper describes a machine/programming model for the era of multi-core chips. It is derived from the sequential model but replaces sequential composition with concurrent composition at all levels in the program except at the level where the compiler is able to make deterministic decisions on
Design of homogeneous trench-assisted multi-core fibers based on analytical model
DEFF Research Database (Denmark)
Ye, Feihong; Tu, Jiajing; Saitoh, Kunimasa
2016-01-01
We present a design method of homogeneous trench-assisted multicore fibers (TA-MCFs) based on an analytical model utilizing an analytical expression for the mode coupling coefficient between two adjacent cores. The analytical model can also be used for crosstalk (XT) properties analysis, such as ...
International Nuclear Information System (INIS)
Zvaritch, Elena; MacLennan, David H.
2015-01-01
Muscle spindles from the hind limb muscles of adult Ryr1 I4895T/wt (IT/+) mice exhibit severe structural abnormalities. Up to 85% of the spindles are separated from skeletal muscle fascicles by a thick layer of connective tissue. Many intrafusal fibers exhibit degeneration, with Z-line streaming, compaction and collapse of myofibrillar bundles, mitochondrial clumping, nuclear shrinkage and pyknosis. The lesions resemble cores observed in the extrafusal myofibers of this animal model and of core myopathy patients. Spindle abnormalities precede those in extrafusal fibers, indicating that they are a primary pathological feature in this murine Ryr1-related core myopathy. Muscle spindle involvement, if confirmed for human core myopathy patients, would provide an explanation for an array of devastating clinical features characteristic of these diseases and provide novel insights into the pathology of RYR1-related myopathies. - Highlights: • Muscle spindles exhibit structural abnormalities in a mouse model of core myopathy. • Myofibrillar collapse and mitochondrial clumping is observed in intrafusal fibers. • Myofibrillar degeneration follows a pattern similar to core formation in extrafusal myofibers. • Muscle spindle abnormalities are a part of the pathological phenotype in the mouse model of core myopathy. • Direct involvement of muscle spindles in the pathology of human RYR1-related myopathies is proposed
International Nuclear Information System (INIS)
Miettinen, Jaakko; Hamalainen, Anitta; Pekkarinen, Esko
2002-01-01
Thermal hydraulic simulation capability for accident conditions is needed at present in VTT in several programs. Traditional thermal hydraulic models are too heavy for simulation in the analysis tasks, where the main emphasis is the rapid neutron dynamics or the core melting. The GENFLO thermal hydraulic model has been developed at VTT for special applications in the combined codes. The basic field equations in GENFLO are for the phase mass, the mixture momentum and phase energy conservation equations. The phase separation is solved with the drift flux model. The basic variables to be solved are the pressure, void fraction, mixture velocity, gas enthalpy, liquid enthalpy, and concentration of non-condensable gas fractions. The validation of the thermohydraulic solution alone includes large break LOCA reflooding experiments and in specific for the severe accident conditions QUENCH tests. In the recriticality analysis the core neutronics is simulated with a two-dimensional transient neutronics code TWODIM. The recriticality with one rapid prompt peak is expected during a severe accident scenario, where the control rods have been melted and ECCS reflooding is started after the depressurization. The GENFLO module simulates the BWR thermohydraulics in this application. The core melting module has been developed for the real time operator training by using the APROS engineering simulators. The core heatup, oxidation, metal and fuel pellet relocation and corium pool formation into the lower plenum are calculated. In this application the GENFLO model simulates the PWR vessel thermohydraulics. In the fuel performance analysis the fuel rod transient behavior is simulated with the FRAPTRAN code. GENFLO simulates the subchannel around a single fuel rod and delivers the heat transfer on the cladding surface for the FRAPTRAN. The transient boundary conditions for the subchannel are transmitted from the system code for operational transient, loss of coolant accidents and
TRANTHAC-1: transient thermal-hydraulic analysis code for HTGR core of multi-channel model
International Nuclear Information System (INIS)
Sato, Sadao; Miyamoto, Yoshiaki
1980-08-01
The computer program TRANTHAC-1 is for predicting thermal-hydraulic transient behavior in HTGR's core of pin-in-block type fuel elements, taking into consideration of the core flow distribution. The program treats a multi-channel model, each single channel representing the respective column composed of fuel elements. The fuel columns are grouped in flow control regions; each region is provided with an orifice assembly. In the region, all channels are of the same shape except one channel. Core heat is removed by downward flow of the control through the channel. In any transients, for given time-dependent power, total core flow, inlet coolant temperature and coolant pressure, the thermal response of the core can be determined. In the respective channels, the heat conduction in radial and axial direction are represented. And the temperature distribution in each channel with the components is calculated. The model and usage of the program are described. The program is written in FORTRAN-IV for computer FACOM 230-75 and it is composed of about 4,000 cards. The required core memory is about 75 kilowords. (author)
Modeling of melt retention in EU-APR1400 ex-vessel core catcher
Energy Technology Data Exchange (ETDEWEB)
Granovsky, V. S.; Sulatsky, A. A.; Khabensky, V. B.; Sulatskaya, M. B. [Alexandrov Research Inst. of Technology NITI, Sosnovy Bor (Russian Federation); Gusarov, V. V.; Almyashev, V. I.; Komlev, A. A. [Saint Petersburg State Technological Univ. SPbSTU, St.Petersburg (Russian Federation); Bechta, S. [KTH, Stockholm (Sweden); Kim, Y. S. [KHNP, 1312 Gil 70, Yuseongdaero, Yuseong-gu, Daejeon (Korea, Republic of); Park, R. J.; Kim, H. Y.; Song, J. H. [KAERI, 989 Gil 111, Daedeokdaero, Yuseong-gu, Daejeon (Korea, Republic of)
2012-07-01
A core catcher is adopted in the EU-APR1400 reactor design for management and mitigation of severe accidents with reactor core melting. The core catcher concept incorporates a number of engineering solutions used in the catcher designs of European EPR and Russian WER-1000 reactors, such as thin-layer corium spreading for better cooling, retention of the melt in a water-cooled steel vessel, and use of sacrificial material (SM) to control the melt properties. SM is one of the key elements of the catcher design and its performance is critical for melt retention efficiency. This SM consists of oxide components, but the core catcher also includes sacrificial steel which reacts with the metal melt of the molten corium to reduce its temperature. The paper describes the required properties of SM. The melt retention capability of the core catcher can be confirmed by modeling the heat fluxes to the catcher vessel to show that it will not fail. The fulfillment of this requirement is demonstrated on the example of LBLOCA severe accident. Thermal and physicochemical interactions between the oxide and metal melts, interactions of the melts with SM, sacrificial steel and vessel, core catcher external cooling by water and release of non-condensable gases are modeled. (authors)
MODELLING CHALCOPYRITE LEACHING BY Fe+3 IONS WITH THE SHRINKING CORE MODEL
Directory of Open Access Journals (Sweden)
Rodrigo Rangel Porcaro
2015-03-01
Full Text Available Chalcopyrite leaching by ferric iron is considered a slow process with low copper recovery; a phenomenon ascribed to the passivation of the mineral surface during leaching. Thus, the current study investigated the leaching kinetics of a high purity chalcopyrite sample in the presence of ferric sulfate as oxidant. The effects of the stirring rate, temperature, Eh and Fe3+ concentration on copper extraction were assessed. The leaching data could be described by the shirking core model (SCM for particles of unchanging size and indicated diffusion in the ash layer as the rate-controlling step with a high activation energy (103.9±6.5kJ/mol; likely an outcome of neglecting the effect of particle size distribution (PSD on the kinetics equations. Both the application of the quasi-steady-state assumption to solid-liquid systems and the effect of the particle size distribution on the interpretation of kinetics data are also discussed.
The modeling of core melting and in-vessel corium relocation in the APRIL code
Energy Technology Data Exchange (ETDEWEB)
Kim. S.W.; Podowski, M.Z.; Lahey, R.T. [Rensselaer Polytechnic Institute, Troy, NY (United States)] [and others
1995-09-01
This paper is concerned with the modeling of severe accident phenomena in boiling water reactors (BWR). New models of core melting and in-vessel corium debris relocation are presented, developed for implementation in the APRIL computer code. The results of model testing and validations are given, including comparisons against available experimental data and parametric/sensitivity studies. Also, the application of these models, as parts of the APRIL code, is presented to simulate accident progression in a typical BWR reactor.
Modelling high-resolution electron microscopy based on core-loss spectroscopy
International Nuclear Information System (INIS)
Allen, L.J.; Findlay, S.D.; Oxley, M.P.; Witte, C.; Zaluzec, N.J.
2006-01-01
There are a number of factors affecting the formation of images based on core-loss spectroscopy in high-resolution electron microscopy. We demonstrate unambiguously the need to use a full nonlocal description of the effective core-loss interaction for experimental results obtained from high angular resolution electron channelling electron spectroscopy. The implications of this model are investigated for atomic resolution scanning transmission electron microscopy. Simulations are used to demonstrate that core-loss spectroscopy images formed using fine probes proposed for future microscopes can result in images that do not correspond visually with the structure that has led to their formation. In this context, we also examine the effect of varying detector geometries. The importance of the contribution to core-loss spectroscopy images by dechannelled or diffusely scattered electrons is reiterated here
International Nuclear Information System (INIS)
Shimada, Yoshio
2000-01-01
It is anticipated that the change of frequency of surveillance tests, preventive maintenance or parts replacement of safety related components may cause the change of component failure probability and result in the change of core damage probability. It is also anticipated that the change is different depending on the initiating event frequency or the component types. This study assessed the change of core damage probability using simplified PSA model capable of calculating core damage probability in a short time period, which is developed by the US NRC to process accident sequence precursors, when various component's failure probability is changed between 0 and 1, or Japanese or American initiating event frequency data are used. As a result of the analysis, (1) It was clarified that frequency of surveillance test, preventive maintenance or parts replacement of motor driven pumps (high pressure injection pumps, residual heat removal pumps, auxiliary feedwater pumps) should be carefully changed, since the core damage probability's change is large, when the base failure probability changes toward increasing direction. (2) Core damage probability change is insensitive to surveillance test frequency change, since the core damage probability change is small, when motor operated valves and turbine driven auxiliary feed water pump failure probability changes around one figure. (3) Core damage probability change is small, when Japanese failure probability data are applied to emergency diesel generator, even if failure probability changes one figure from the base value. On the other hand, when American failure probability data is applied, core damage probability increase is large, even if failure probability changes toward increasing direction. Therefore, when Japanese failure probability data is applied, core damage probability change is insensitive to surveillance tests frequency change etc. (author)
Burhan, Muhammad; Shahzad, Muhammad Wakil; Ng, Kim Choon
2017-01-01
Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.
Directory of Open Access Journals (Sweden)
Elhaseen Elamin
Full Text Available BACKGROUND: Intestinal barrier dysfunction and translocation of endotoxins are involved in the pathogenesis of alcoholic liver disease. Exposure to ethanol and its metabolite, acetaldehyde at relatively high concentrations have been shown to disrupt intestinal epithelial tight junctions in the conventional two dimensional cell culture models. The present study investigated quantitatively and qualitatively the effects of ethanol at concentrations detected in the blood after moderate ethanol consumption, of its metabolite acetaldehyde and of the combination of both compounds on intestinal barrier function in a three-dimensional cell culture model. METHODS AND FINDINGS: Caco-2 cells were grown in a basement membrane matrix (Matrigel™ to induce spheroid formation and were then exposed to the compounds at the basolateral side. Morphological differentiation of the spheroids was assessed by immunocytochemistry and transmission electron microscopy. The barrier function was assessed by the flux of FITC-labeled dextran from the basal side into the spheroids' luminal compartment using confocal microscopy. Caco-2 cells grown on Matrigel assembled into fully differentiated and polarized spheroids with a central lumen, closely resembling enterocytes in vivo and provide an excellent model to study epithelial barrier functionality. Exposure to ethanol (10-40 mM or acetaldehyde (25-200 µM for 3 h, dose-dependently and additively increased the paracellular permeability and induced redistribution of ZO-1 and occludin without affecting cell viability or tight junction-encoding gene expression. Furthermore, ethanol and acetaldehyde induced lysine residue and microtubules hyperacetylation. CONCLUSIONS: These results indicate that ethanol at concentrations found in the blood after moderate drinking and acetaldehyde, alone and in combination, can increase the intestinal epithelial permeability. The data also point to the involvement of protein hyperacetylation in
Burhan, Muhammad
2017-09-16
Despite highest energy potential, solar energy is only available during diurnal period with varying intensity. Therefore, owing to solar intermittency, solar energy systems need to operate in standalone configuration for steady power supply which requires reliable and sustainable energy storage. Hydrogen production has proved to be the most reliable and sustainable energy storage option for medium and long term operation. However, at the first priority, solar energy must be captured with high efficiency, in order to reduce the overall size of the system and energy storage. Multi-junction solar cells (MJCs) provide highest energy efficiency among all of the photovoltaic technologies and the concentrated photovoltaic (CPV) system concept makes their use cost effective. However, literature is lacking the performance model and optimization strategy for standalone operation of the CPV-hydrogen system. In addition, there is no commercial tool available that can analyze CPV performance, utilizing multi-junction solar cell. This paper proposes the performance model for the CPV-hydrogen systems and the multi-objective optimization strategy for its standalone operation and techno-economic analysis, using micro genetic algorithm (micro-GA). The electrolytic hydrogen production with compression storage and fuel cell, is used as energy storage system. The CPV model is verified for the experimental data of InGaP/InGaAs/Ge triple junction solar cell. An optimal CPV system design is provided for uninterrupted power supply, even under seasonal weather variations. Such approach can be easily integrated with commercial tools and the presented performance data can be used for the design of individual components of the system.
Ex-Vessel Core Melt Modeling Comparison between MELTSPREAD-CORQUENCH and MELCOR 2.1
Energy Technology Data Exchange (ETDEWEB)
Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Farmer, Mitchell [Argonne National Lab. (ANL), Argonne, IL (United States); Francis, Matthew W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2014-03-01
System-level code analyses by both United States and international researchers predict major core melting, bottom head failure, and corium-concrete interaction for Fukushima Daiichi Unit 1 (1F1). Although system codes such as MELCOR and MAAP are capable of capturing a wide range of accident phenomena, they currently do not contain detailed models for evaluating some ex-vessel core melt behavior. However, specialized codes containing more detailed modeling are available for melt spreading such as MELTSPREAD as well as long-term molten corium-concrete interaction (MCCI) and debris coolability such as CORQUENCH. In a preceding study, Enhanced Ex-Vessel Analysis for Fukushima Daiichi Unit 1: Melt Spreading and Core-Concrete Interaction Analyses with MELTSPREAD and CORQUENCH, the MELTSPREAD-CORQUENCH codes predicted the 1F1 core melt readily cooled in contrast to predictions by MELCOR. The user community has taken notice and is in the process of updating their systems codes; specifically MAAP and MELCOR, to improve and reduce conservatism in their ex-vessel core melt models. This report investigates why the MELCOR v2.1 code, compared to the MELTSPREAD and CORQUENCH 3.03 codes, yield differing predictions of ex-vessel melt progression. To accomplish this, the differences in the treatment of the ex-vessel melt with respect to melt spreading and long-term coolability are examined. The differences in modeling approaches are summarized, and a comparison of example code predictions is provided.
International Nuclear Information System (INIS)
Suhendi, Endi; Syariati, Rifki; Noor, Fatimah A.; Khairurrijal; Kurniasih, Neny
2014-01-01
We modeled a tunneling current in a p-n junction based on armchair graphene nanoribbons (AGNRs) by using an Airy function approach (AFA) and a transfer matrix method (TMM). We used β-type AGNRs, in which its band gap energy and electron effective mass depends on its width as given by the extended Huckel theory. It was shown that the tunneling currents evaluated by employing the AFA are the same as those obtained under the TMM. Moreover, the calculated tunneling current was proportional to the voltage bias and inversely with temperature
Integrating 3D CAD data for manufacturing and fabrication the core model of reactor TRIGA PUSPATI
International Nuclear Information System (INIS)
Abu Bakar Harun
2005-01-01
This paper describe the intrigue integration of digital 3 Dimensional Computer Aided Design (3D CAD) data manipulation for the Core Model fabrication of REAKTOR TRIGA PUSPATI and ready for mass manufacturing. 3 Dimensional CAD data from Computer Aided Design program will be used as an interpreter in the fabrication of this project. The Core Model of REAKTOR TRIGA PUSPATI will be fabricated with the aid of 3D CAD drawings and digital files. The components will be segregated and divided into 2 categories namely Conventional d Rapid Fabrication. (Author)
300 kWt core conceptual model thermal/hydraulic characteristics
International Nuclear Information System (INIS)
Moody, E.
1971-01-01
The 300 kW(t), 199 element NASA-Lewis/AEC core conceptual model, has been analyzed to determine it's thermal-hydraulic characteristics using the GEOM-3 code. Stack-ups of tolerances and fuel rod asymmetry patterns were used to ascertain cross element Δ T's. Both zoned and uniform spacing were analyzed with a somewhat lower fuel temperature and cross element ΔT found for zoned spacing. With the models considered, the core design appears adequate to limit thermal gradients to approximately 32 0 F. Bypass flow should be controlled to prevent excessive edge element ΔT's. 11 references. (U.S.)
CORCON-MOD3: An integrated computer model for analysis of molten core-concrete interactions
International Nuclear Information System (INIS)
Bradley, D.R.; Gardner, D.R.; Brockmann, J.E.; Griffith, R.O.
1993-10-01
The CORCON-Mod3 computer code was developed to mechanistically model the important core-concrete interaction phenomena, including those phenomena relevant to the assessment of containment failure and radionuclide release. The code can be applied to a wide range of severe accident scenarios and reactor plants. The code represents the current state of the art for simulating core debris interactions with concrete. This document comprises the user's manual and gives a brief description of the models and the assumptions and limitations in the code. Also discussed are the input parameters and the code output. Two sample problems are also given
Investigation of Large Scale Cortical Models on Clustered Multi-Core Processors
2013-02-01
Playstation 3 with 6 available SPU cores outperforms the Intel Xeon processor (with 4 cores) by about 1.9 times for the HTM model and by 2.4 times...runtime breakdowns of the HTM and Dean models respectively on the Cell processor (on the Playstation 3) and the Intel Xeon processor ( 4 thread...YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) 4 . TITLE AND SUBTITLE 5a. CONTRACT NUMBER
Equivalent Josephson junctions
International Nuclear Information System (INIS)
Boyadzhiev, T.L.; ); Semerdzhieva, E.G.; Shukrinov, Yu.M.; Fiziko-Tekhnicheskij Inst., Dushanbe
2008-01-01
The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt- or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is possible to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flux [ru
Vibration mode and vibration shape under excitation of a three phase model transformer core
Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi
2018-04-01
Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.
Scale model study of the seismic response of a nuclear reactor core
International Nuclear Information System (INIS)
Dove, R.C.; Dunwoody, W.E.; Rhorer, R.L.
1983-01-01
The use of scale models to study the dynamics of a system of graphite core blocks used in certain nuclear reactor designs is described. Scaling laws, material selecton, model instrumentation to measure collision forces, and the response of several models to simulated seismic excitation are covered. The effects of Coulomb friction between the blocks and the clearance gaps between the blocks on the system response to seismic excitation are emphasized
Development of seismic analysis model for HTGR core on commercial FEM code
International Nuclear Information System (INIS)
Tsuji, Nobumasa; Ohashi, Kazutaka
2015-01-01
The aftermath of the Great East Japan Earthquake prods to revise the design basis earthquake intensity severely. In aseismic design of block-type HTGR, the securement of structural integrity of core blocks and other structures which are made of graphite become more important. For the aseismic design of block-type HTGR, it is necessary to predict the motion of core blocks which are collided with adjacent blocks. Some seismic analysis codes have been developed in 1970s, but these codes are special purpose-built codes and have poor collaboration with other structural analysis code. We develop the vertical 2 dimensional analytical model on multi-purpose commercial FEM code, which take into account the multiple impacts and friction between block interfaces and rocking motion on contact with dowel pins of the HTGR core by using contact elements. This model is verified by comparison with the experimental results of 12 column vertical slice vibration test. (author)
Fast three-dimensional core optimization based on modified one-group model
Energy Technology Data Exchange (ETDEWEB)
Freire, Fernando S. [ELETROBRAS Termonuclear S.A. - ELETRONUCLEAR, Rio de Janeiro, RJ (Brazil). Dept. GCN-T], e-mail: freire@eletronuclear.gov.br; Martinez, Aquilino S.; Silva, Fernando C. da [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear], e-mail: aquilino@con.ufrj.br, e-mail: fernando@con.ufrj.br
2009-07-01
The optimization of any nuclear reactor core is an extremely complex process that consumes a large amount of computer time. Fortunately, the nuclear designer can rely on a variety of methodologies able to approximate the analysis of each available core loading pattern. Two-dimensional codes are usually used to analyze the loading scheme. However, when particular axial effects are present in the core, two-dimensional analysis cannot produce good results and three-dimensional analysis can be required at all time. Basically, in this paper are presented the major advantages that can be found when one use the modified one-group diffusion theory coupled with a buckling correction model in optimization process. The results of the proposed model are very accurate when compared to benchmark results obtained from detailed calculations using three-dimensional nodal codes (author)
Assessment of core thermo-hydrodynamic models of REFLA-1D with CCTF data
International Nuclear Information System (INIS)
Okubo, Tsutomu; Murao, Yoshio
1983-07-01
In order to assess the core thermo-hydrodynamic models of REFLA-1D/MODE3, which is the latest version of REFLA-1D, several calculations of the core thermo-hydrodynamics have been performed for the CCTF Core-I series tests. The measured initial and boundary conditions were used for these calculations. The calculational results showed that the water accumulation model of Case 2 could predict the CCTF results fairly well as it could for the JAERI small scale facility. The calculated results for the base case and the EM tests were in good agreement with the CCTF data. The parameter effects, such as system pressure, initial clad temperature, Acc injection rate, LPCI injection rate and initial down-comer wall temperature, were predicted correctly, except for the high system pressure and the high LPCI injection rate tests. (author)
A benchmark for coupled thermohydraulics system/three-dimensional neutron kinetics core models
International Nuclear Information System (INIS)
Kliem, S.
1999-01-01
During the last years 3D neutron kinetics core models have been coupled to advanced thermohydraulics system codes. These coupled codes can be used for the analysis of the whole reactor system. Although the stand-alone versions of the 3D neutron kinetics core models and of the thermohydraulics system codes generally have a good verification and validation basis, there is a need for additional validation work. This especially concerns the interaction between the reactor core and the other components of a nuclear power plant (NPP). In the framework of the international 'Atomic Energy Research' (AER) association on VVER Reactor Physics and Reactor Safety, a benchmark for these code systems was defined. (orig.)
CoreFlow: A computational platform for integration, analysis and modeling of complex biological data
DEFF Research Database (Denmark)
Pasculescu, Adrian; Schoof, Erwin; Creixell, Pau
2014-01-01
between data generation, analysis and manuscript writing. CoreFlow is being released to the scientific community as an open-sourced software package complete with proteomics-specific examples, which include corrections for incomplete isotopic labeling of peptides (SILAC) or arginine-to-proline conversion......A major challenge in mass spectrometry and other large-scale applications is how to handle, integrate, and model the data that is produced. Given the speed at which technology advances and the need to keep pace with biological experiments, we designed a computational platform, CoreFlow, which...... provides programmers with a framework to manage data in real-time. It allows users to upload data into a relational database (MySQL), and to create custom scripts in high-level languages such as R, Python, or Perl for processing, correcting and modeling this data. CoreFlow organizes these scripts...
Fast three-dimensional core optimization based on modified one-group model
International Nuclear Information System (INIS)
Freire, Fernando S.; Martinez, Aquilino S.; Silva, Fernando C. da
2009-01-01
The optimization of any nuclear reactor core is an extremely complex process that consumes a large amount of computer time. Fortunately, the nuclear designer can rely on a variety of methodologies able to approximate the analysis of each available core loading pattern. Two-dimensional codes are usually used to analyze the loading scheme. However, when particular axial effects are present in the core, two-dimensional analysis cannot produce good results and three-dimensional analysis can be required at all time. Basically, in this paper are presented the major advantages that can be found when one use the modified one-group diffusion theory coupled with a buckling correction model in optimization process. The results of the proposed model are very accurate when compared to benchmark results obtained from detailed calculations using three-dimensional nodal codes (author)
Constantino, Thomas; Campbell, Simon W.; Lattanzio, John C.
2017-12-01
Theoretical predictions for the core helium burning phase of stellar evolution are highly sensitive to the uncertain treatment of mixing at convective boundaries. In the last few years, interest in constraining the uncertain structure of their deep interiors has been renewed by insights from asteroseismology. Recently, Spruit proposed a limit for the rate of growth of helium-burning convective cores based on the higher buoyancy of material ingested from outside the convective core. In this paper we test the implications of such a limit for stellar models with a range of initial mass and metallicity. We find that the constraint on mixing beyond the Schwarzschild boundary has a significant effect on the evolution late in core helium burning, when core breathing pulses occur and the ingestion rate of helium is fastest. Ordinarily, core breathing pulses prolong the core helium burning lifetime to such an extent that models are at odds with observations of globular cluster populations. Across a wide range of initial stellar masses (0.83 ≤ M/M⊙ ≤ 5), applying the Spruit constraint reduces the core helium burning lifetime because core breathing pulses are either avoided or their number and severity reduced. The constraint suggested by Spruit therefore helps to resolve significant discrepancies between observations and theoretical predictions. Specifically, we find improved agreement for R2 (the observed ratio of asymptotic giant branch to horizontal branch stars in globular clusters), the luminosity difference between these two groups, and in asteroseismology, the mixed-mode period spacing detected in red clump stars in the Kepler field.
Energy Technology Data Exchange (ETDEWEB)
Hu, Rui, E-mail: rhu@anl.gov; Yu, Yiqi
2016-11-15
Highlights: • Developed a computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors. • Applied fully-coupled JFNK solution scheme to avoid the operator-splitting errors. • The accuracy and efficiency of the method is confirmed with a 7-assembly test problem. • The effects of different spatial discretization schemes are investigated and compared to the RANS-based CFD simulations. - Abstract: For efficient and accurate temperature predictions of sodium fast reactor structures, a 3-D full-core conjugate heat transfer modeling capability is developed for an advanced system analysis tool, SAM. The hexagon lattice core is modeled with 1-D parallel channels representing the subassembly flow, and 2-D duct walls and inter-assembly gaps. The six sides of the hexagon duct wall and near-wall coolant region are modeled separately to account for different temperatures and heat transfer between coolant flow and each side of the duct wall. The Jacobian Free Newton Krylov (JFNK) solution method is applied to solve the fluid and solid field simultaneously in a fully coupled fashion. The 3-D full-core conjugate heat transfer modeling capability in SAM has been demonstrated by a verification test problem with 7 fuel assemblies in a hexagon lattice layout. Additionally, the SAM simulation results are compared with RANS-based CFD simulations. Very good agreements have been achieved between the results of the two approaches.
A review of MAAP4 code structure and core T/H model
International Nuclear Information System (INIS)
Song, Yong Mann; Park, Soo Yong
1998-03-01
The modular accident analysis program (MAAP) version 4 is a computer code that can simulate the response of LWR plants during severe accident sequences and includes models for all of the important phenomena which might occur during accident sequences. In this report, MAAP4 code structure and core thermal hydraulic (T/H) model which models the T/H behavior of the reactor core and the response of core components during all accident phases involving degraded cores are specifically reviewed and then reorganized. This reorganization is performed via getting the related models together under each topic whose contents and order are same with other two reports for MELCOR and SCDAP/RELAP5 to be simultaneously published. Major purpose of the report is to provide information about the characteristics of MAAP4 core T/H models for an integrated severe accident computer code development being performed under the one of on-going mid/long-term nuclear developing project. The basic characteristics of the new integrated severe accident code includes: 1) Flexible simulation capability of primary side, secondary side, and the containment under severe accident conditions, 2) Detailed plant simulation, 3) Convenient user-interfaces, 4) Highly modularization for easy maintenance/improvement, and 5) State-of-the-art model selection. In conclusion, MAAP4 code has appeared to be superior for 3) and 4) items but to be somewhat inferior for 1) and 2) items. For item 5), more efforts should be made in the future to compare separated models in detail with not only other codes but also recent world-wide work. (author). 17 refs., 1 tab., 12 figs
Noise variation by compressive stress on the model core of power transformers
Energy Technology Data Exchange (ETDEWEB)
Mizokami, Masato, E-mail: mizokami.g76.masato@jp.nssmc.com; Kurosaki, Yousuke
2015-05-01
The reduction of audible noise generated by cores for power transformers has been required due to environmental concern. It is known that compressive stress in the rolling direction of electrical steel affects magnetostriction and it can result in an increase in noise level. In this research, the effect of compressive stress to noise was investigated on a 3-phase 3-limb model core. Compressive stress was applied in the rolling direction of the limbs from the outside of the core. It increased the sound pressure levels and the slope of the rise was about 2 dBA/MPa. Magnetostriction on single sheet samples was also measured under compressive stress and the harmonic components of the magnetostriction were compared with those of noise. It revealed that the variation in magnetostriction with compressive stress did not entirely correspond to that in noise. In one of the experiments, localized bending happened on one limb during compressing the core. While deformation of the core had not been intended, the noise was measured. The deformation increased the noise by more than 10 dBA and it occurred on most of the harmonic components. - Highlights: • Audible noise was measured on a model core to which compressive stress was applied. • The stress in the rolling direction of the steel causes a rise in noise level. • The slope of the rise in sound pressure level up to 2.5 MPa is about 2 dBA/MPa. • Variation in magnetostriction by stress does not entirely agree with that in noise. • Bend arisen in the core causes an extreme increase in noise.
Noise variation by compressive stress on the model core of power transformers
International Nuclear Information System (INIS)
Mizokami, Masato; Kurosaki, Yousuke
2015-01-01
The reduction of audible noise generated by cores for power transformers has been required due to environmental concern. It is known that compressive stress in the rolling direction of electrical steel affects magnetostriction and it can result in an increase in noise level. In this research, the effect of compressive stress to noise was investigated on a 3-phase 3-limb model core. Compressive stress was applied in the rolling direction of the limbs from the outside of the core. It increased the sound pressure levels and the slope of the rise was about 2 dBA/MPa. Magnetostriction on single sheet samples was also measured under compressive stress and the harmonic components of the magnetostriction were compared with those of noise. It revealed that the variation in magnetostriction with compressive stress did not entirely correspond to that in noise. In one of the experiments, localized bending happened on one limb during compressing the core. While deformation of the core had not been intended, the noise was measured. The deformation increased the noise by more than 10 dBA and it occurred on most of the harmonic components. - Highlights: • Audible noise was measured on a model core to which compressive stress was applied. • The stress in the rolling direction of the steel causes a rise in noise level. • The slope of the rise in sound pressure level up to 2.5 MPa is about 2 dBA/MPa. • Variation in magnetostriction by stress does not entirely agree with that in noise. • Bend arisen in the core causes an extreme increase in noise
Modeling the Conducting Stably-Stratified Layer of the Earth's Core
Petitdemange, L.; Philidet, J.; Gissinger, C.
2017-12-01
Observations of the Earth magnetic field as well as recent theoretical works tend to show that the Earth's outer liquid core is mostly comprised of a convective zone in which the Earth's magnetic field is generated - likely by dynamo action -, but also features a thin, stably stratified layer at the top of the core.We carry out direct numerical simulations by modeling this thin layer as an axisymmetric spherical Couette flow for a stably stratified fluid embedded in a dipolar magnetic field. The dynamo region is modeled by a conducting inner core rotating slightly faster than the insulating mantle due to magnetic torques acting on it, such that a weak differential rotation (low Rossby limit) can develop in the stably stratified layer.In the case of a non-stratified fluid, the combined action of the differential rotation and the magnetic field leads to the well known regime of `super-rotation', in which the fluid rotates faster than the inner core. Whereas in the classical case, this super-rotation is known to vanish in the magnetostrophic limit, we show here that the fluid stratification significantly extends the magnitude of the super-rotation, keeping this phenomenon relevant for the Earth core. Finally, we study how the shear layers generated by this new state might give birth to magnetohydrodynamic instabilities or waves impacting the secular variations or jerks of the Earth's magnetic field.
Modelling of core protection and monitoring system for PWR nuclear power plant simulator
International Nuclear Information System (INIS)
Jung Kun Lee; Byoung Sung Han
1997-01-01
A nuclear power plant simulator was developed for Younggwang units 3 and 4 nuclear power plant (YGN Nos 3 and 4) in Korea; it has been in operation on training center since November 1996. The core protection calculator (CPC) and the core operating limit supervisory system (COLSS) for the simulator were also developed. The CPC is a digital computer-based core protection system, which performs on-line calculation of departure from nucleate boiling ratio (DNBR) and local power density (LPD). It initiates reactor trip when the core conditions exceed designated DNBR or LPD limitations. The COLSS is designed to assist operators by implementing the limiting conditions for operations in the technical specifications. With these systems, it is possible to increase capacity factor and safety of nuclear power plants, because the COLSS data can show accurate operation margin to plant operators and the CPC can protect reactor core. In this study, the function of CPC/COLSS is analyzed in detail, and then simulation model for CPC/COLSS is presented based on the function. Compared with the YGN Nos 3 and 4 plant operation data and CEDIPS/COLSS FORTRAN code test results, the predictions with the model show reasonable results. (Author)
Effect of superconducting solenoid model cores on spanwise iron magnet roll control
Britcher, C. P.
1985-01-01
Compared with conventional ferromagnetic fuselage cores, superconducting solenoid cores appear to offer significant reductions in the projected cost of a large wind tunnel magnetic suspension and balance system. The provision of sufficient magnetic roll torque capability has been a long-standing problem with all magnetic suspension and balance systems; and the spanwise iron magnet scheme appears to be the most powerful system available. This scheme utilizes iron cores which are installed in the wings of the model. It was anticipated that the magnetization of these cores, and hence the roll torque generated, would be affected by the powerful external magnetic field of the superconducting solenoid. A preliminary study has been made of the effect of the superconducting solenoid fuselage model core concept on the spanwise iron magnet roll torque generation schemes. Computed data for one representative configuration indicate that reductions in available roll torque occur over a range of applied magnetic field levels. These results indicate that a 30-percent increase in roll electromagnet capacity over that previously determined will be required for a representative 8-foot wind tunnel magnetic suspension and balance system design.
Energy Technology Data Exchange (ETDEWEB)
Nonboel, E
1985-07-01
A 3-dimensional calculation model of the Danish research reactor DR3 has been developed. Demands of a more effective utilization of the reactor and its facilities has required a more detailed calculation tool than applied so far. A great deal of attention has been devoted to the treatment of the coarse control arms. The model has been tested against measurements with satisfying results. Furthermore the model has been used to analyse a proposal to a new core design called ring-core where 4 central fuel elements are replaced by 4 dummy elements to increase the thermal flux in the center of the reactor. (author)
Thermal-Hydraulics analysis of pressurized water reactor core by using single heated channel model
Directory of Open Access Journals (Sweden)
Reza Akbari
2017-08-01
Full Text Available Thermal hydraulics of nuclear reactor as a basis of reactor safety has a very important role in reactor design and control. The thermal-hydraulic analysis provides input data to the reactor-physics analysis, whereas the latter gives information about the distribution of heat sources, which is needed to perform the thermal-hydraulic analysis. In this study single heated channel model as a very fast model for predicting thermal hydraulics behavior of pressurized water reactor core has been developed. For verifying the results of this model, we used RELAP5 code as US nuclear regulatory approved thermal hydraulics code. The results of developed single heated channel model have been checked with RELAP5 results for WWER-1000. This comparison shows the capability of single heated channel model for predicting thermal hydraulics behavior of reactor core.
Current noise in tunnel junctions
Energy Technology Data Exchange (ETDEWEB)
Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)
2017-06-15
We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Selective interface transparency in graphene nanoribbon based molecular junctions.
Dou, K P; Kaun, C C; Zhang, R Q
2018-03-08
A clear understanding of electrode-molecule interfaces is a prerequisite for the rational engineering of future generations of nanodevices that will rely on single-molecule coupling between components. With a model system, we reveal a peculiar dependence on interfaces in all graphene nanoribbon-based carbon molecular junctions. The effect can be classified into two types depending on the intrinsic feature of the embedded core graphene nanoflake (GNF). For metallic GNFs with |N A - N B | = 1, good/poor contact transparency occurs when the core device aligns with the center/edge of the electrode. The situation is reversed when a semiconducting GNF is the device, where N A = N B . These results may shed light on the design of real connecting components in graphene-based nanocircuits.
Neutron induced permanent damage in Josephson junctions
International Nuclear Information System (INIS)
Mueller, G.P.; Rosen, M.
1982-01-01
14 MeV neutron induced permanent changes in the critical current density of Josephson junctions due to displacement damage in the junction barrier are estimated using a worst case model and the binary collision simulation code MARLOWE. No likelihood of single event hard upsets is found in this model. It is estimated that a fluence of 10 18 -10 19 neutrons/cm 2 are required to change the critical current density by 5%
International Nuclear Information System (INIS)
Ke, Xi-song; Li, Wen-cheng; Hovland, Randi; Qu, Yi; Liu, Run-hui; McCormack, Emmet; Thorsen, Frits; Olsen, Jan Roger; Molven, Anders; Kogan-Sakin, Ira; Rotter, Varda; Akslen, Lars A.; Oyan, Anne Margrete; Kalland, Karl-Henning
2011-01-01
Epithelial to mesenchymal transition (EMT) is pivotal in tumor metastasis. Our previous work reported an EMT model based on primary prostate epithelial cells (EP156T) which gave rise to cells with mesenchymal phenotype (EPT1) without malignant transformation. To promote prostate cell transformation, cells were maintained in saturation density cultures to select for cells overriding quiescence. Foci formed repeatedly following around 8 weeks in confluent EPT1 monolayers. Only later passage EPT1, but not EP156T cells of any passage, could form foci. Cells isolated from the foci were named EPT2 and formed robust colonies in soft agar, a malignant feature present neither in EP156T nor in EPT1 cells. EPT2 cells showed additional malignant traits in vitro, including higher ability to proliferate following confluence, higher resistance to apoptosis and lower dependence on exogenous growth factors than EP156T and EPT1 cells. Microarray profiling identified gene sets, many of which belong to cell junction modules, that changed expression from EP156T to EPT1 cells and continued to change from EPT1 to EPT2 cells. Our findings provide a novel stepwise cell culture model in which EMT emerges independently of transformation and is associated with subsequent accumulation of malignant features in prostate cells. Reprogramming of cell junction modules is involved in both steps.
Gweon, Tae-Geun; Park, Jong-Hyung; Kim, Byung-Wook; Choi, Yang Kyu; Kim, Joon Sung; Park, Sung Min; Kim, Chang Whan; Kim, Hyung-Gil; Chung, Jun-Won
2018-01-15
The aim of this study was to investigate the effects of rebamipide on tight junction proteins in the esophageal mucosa in a rat model of gastroesophageal reflux disease (GERD). GERD was created in rats by tying the proximal stomach. The rats were divided into a control group, a proton pump inhibitor (PPI) group, and a PPI plus rebamipide (PPI+R) group. Pantoprazole (5 mg/kg) was administered intraperitoneally to the PPI and PPI+R groups. An additional dose of rebamipide (100 mg/kg) was administered orally to the PPI+R group. Mucosal erosions, epithelial thickness, and leukocyte infiltration into the esophageal mucosa were measured in isolated esophagi 14 days after the procedure. A Western blot analysis was conducted to measure the expression of claudin-1, -3, and -4. The mean surface area of mucosal erosions, epithelial thickness, and leukocyte infiltration were lower in the PPI group and the PPI+R group than in the control group. Western blot analysis revealed that the expression of claudin-3 and -4 was significantly higher in the PPI+R group than in the control group. Rebamipide may exert an additive effect in combination with PPI to modify the tight junction proteins of the esophageal mucosa in a rat model of GERD. This treatment might be associated with the relief of GERD symptoms.
Model-based temperature noise monitoring methods for LMFBR core anomaly detection
International Nuclear Information System (INIS)
Tamaoki, Tetsuo; Sonoda, Yukio; Sato, Masuo; Takahashi, Ryoichi.
1994-01-01
Temperature noise, measured by thermocouples mounted at each core fuel subassembly, is considered to be the most useful signal for detecting and locating local cooling anomalies in an LMFBR core. However, the core outlet temperature noise contains background noise due to fluctuations in the operating parameters including reactor power. It is therefore necessary to reduce this background noise for highly sensitive anomaly detection by subtracting predictable components from the measured signal. In the present study, both a physical model and an autoregressive model were applied to noise data measured in the experimental fast reactor JOYO. The results indicate that the autoregressive model has a higher precision than the physical model in background noise prediction. Based on these results, an 'autoregressive model modification method' is proposed, in which a temporary autoregressive model is generated by interpolation or extrapolation of reference models identified under a small number of different operating conditions. The generated autoregressive model has shown sufficient precision over a wide range of reactor power in applications to artificial noise data produced by an LMFBR noise simulator even when the coolant flow rate was changed to keep a constant power-to-flow ratio. (author)
Liu, Jun-Hua; Xu, Ting-Ting; Zhu, Wei-Yun; Mao, Sheng-Yong
2014-07-01
The omasal epithelial barrier plays important roles in maintaining nutrient absorption and immune homeostasis in ruminants. However, little information is currently available about the changes in omasal epithelial barrier function at the structural and molecular levels during feeding of a high-grain (HG) diet. Ten male goats were randomly assigned to two groups, fed either a hay diet (0% grain; n = 5) or HG diet (65% grain; n = 5). Changes in omasal epithelial structure and expression of tight junction (TJ) proteins were determined via electron microscopy and Western blot analysis. After 7 weeks on each diet, omasal contents in the HG group showed significantly lower pH (P diet showed profound alterations in omasal epithelial structure and TJ proteins, corresponding to depression of thickness of total epithelia, stratum granulosum, and the sum of the stratum spinosum and stratum basale, marked epithelial cellular damage, erosion of intercellular junctions and down-regulation in expression of the TJ proteins, claudin-4 and occludin. The study demonstrates that feeding a HG diet is associated with omasal epithelial cellular damage and changes in expression of TJ proteins. These research findings provide an insight into the possible significance of diet on the omasal epithelial barrier in ruminants. Copyright © 2014 Elsevier Ltd. All rights reserved.
Ground states and formal duality relations in the Gaussian core model
Cohn, H.; Kumar, A.; Schürmann, A.
2009-01-01
We study dimensional trends in ground states for soft-matter systems. Specifically, using a high-dimensional version of Parrinello-Rahman dynamics, we investigate the behavior of the Gaussian core model in up to eight dimensions. The results include unexpected geometric structures, with surprising
Core-SOL modelling of neon seeded JET discharges with the ITER-like wall
Energy Technology Data Exchange (ETDEWEB)
Telesca, G. [Department of Applied Physics, Ghent University (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Ivanova-Stanik, I.; Zagoerski, R.; Czarnecka, A. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Brezinsek, S.; Huber, A.; Wiesen, S. [Forschungszentrum Juelich GmbH, Institut fuer Klima- und Energieforschung-Plasmaphysik, Juelich (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Drewelow, P. [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Giroud, C. [CCFE Culham, Abingdon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Collaboration: JET EFDA contributors
2016-08-15
Five ELMy H-mode Ne seeded JET pulses have been simulated with the self-consistent core-SOL model COREDIV. In this five pulse series only the Ne seeding rate was changed shot by shot, allowing a thorough study of the effect of Ne seeding on the total radiated power and of its distribution between core and SOL tobe made. The increase in the simulations of the Ne seeding rate level above that achieved in experiments shows saturation of the total radiated power at a relatively low radiated-heating power ratio (f{sub rad} = 0.60) and a further increase of the ratio of SOL to core radiation, in agreement with the reduction of W release at high Ne seeding level. In spite of the uncertainties caused by the simplified SOL model of COREDIV (neutral model, absence of ELMs and slab model for the SOL), the increase of the perpendicular transport in the SOL with increasing Ne seeding rate, which allows to reproduce numerically the experimental distribution core-SOL of the radiated power, appears to be of general applicability. (copyright 2016 The Authors. Contributions to Plasma Physics published by Wiley-VCH Verlag GmbH and Co. KGaA Weinheim. This)
Development of high frequency spice models for ferrite core inductors and transformers
Muyshondt, G. Patrick; Portnoy, William M.
In this work high frequency SPICE models were developed to simulate the hysteresis and saturation effects of toroidal shaped ferrite core inductors and transformers. The models include the nonlinear, multi-valued B-H characteristic of the core material, leakage flux, stray capacitances, and core losses. The saturation effects were modeled using two diode clamping arrangements in conjunction with nonlinear dependent sources. Two possible controlling schemes were developed for the saturation switch. One of the arrangements used the current flowing through a series RC branch to control the switch, while the other used a NAND gate. The NAND gate implementation of the switch proved to be simpler and the parameters associated with it were easier to determine from the measurements and the B-H characteristics of the material. Lumped parameters were used to simulate the parasitic effects. Techniques for measuring these effects are described. The models were verified using manganese-zinc ferrite-type toroidal cores and they have general applicability to all circuit analysis codes equivalent function blocks such as multipliers, adders, and logic components.
First-Principles Modeling of Core/Shell Quantum Dot Sensitized Solar Cells
Azpiroz, Jon Mikel; Infante, Ivan; De Angelis, Filippo
2015-01-01
We report on the density functional theory (DFT) modeling of core/shell quantum dot (QD) sensitized solar cells (QDSSCs), a device architecture that holds great potential in photovoltaics but has not been fully exploited so far. To understand the working mechanisms of this kind of solar cells, we
Supramolecular tunneling junctions
Wimbush, K.S.
2012-01-01
In this study a variety of supramolecular tunneling junctions were created. The basis of these junctions was a self-assembled monolayer of heptathioether functionalized ß-cyclodextrin (ßCD) formed on an ultra-flat Au surface, i.e., the bottom electrode. This gave a well-defined hexagonally packed
Exchange bias and asymmetric hysteresis loops from a microscopic model of core/shell nanoparticles
International Nuclear Information System (INIS)
Iglesias, Oscar; Batlle, Xavier; Labarta, Amilcar
2007-01-01
We present Monte Carlo simulations of hysteresis loops of a model of a magnetic nanoparticle with a ferromagnetic core and an antiferromagnetic shell with varying values of the core/shell interface exchange coupling which aim to clarify the microscopic origin of exchange bias observed experimentally. We have found loop shifts in the field direction as well as displacements along the magnetization axis that increase in magnitude when increasing the interfacial exchange coupling. Overlap functions computed from the spin configurations along the loops have been obtained to explain the origin and magnitude of these features microscopically
Energy Technology Data Exchange (ETDEWEB)
Veshchunov, M.S.; Kisselev, A.E.; Palagin, A.V. [Nuclear Safety Institute, Moscow (Russian Federation)] [and others
1995-09-01
The code package SVECHA for the modeling of in-vessel core degradation (CD) phenomena in severe accidents is being developed in the Nuclear Safety Institute, Russian Academy of Science (NSI RAS). The code package presents a detailed mechanistic description of the phenomenology of severe accidents in a reactor core. The modules of the package were developed and validated on separate effect test data. These modules were then successfully implemented in the ICARE2 code and validated against a wide range of integral tests. Validation results have shown good agreement with separate effect tests data and with the integral tests CORA-W1/W2, CORA-13, PHEBUS-B9+.
Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope.
Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei
2017-10-26
A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10 -5 deg/√h.
α Centauri A as a potential stellar model calibrator: establishing the nature of its core
Nsamba, B.; Monteiro, M. J. P. F. G.; Campante, T. L.; Cunha, M. S.; Sousa, S. G.
2018-05-01
Understanding the physical process responsible for the transport of energy in the core of α Centauri A is of the utmost importance if this star is to be used in the calibration of stellar model physics. Adoption of different parallax measurements available in the literature results in differences in the interferometric radius constraints used in stellar modelling. Further, this is at the origin of the different dynamical mass measurements reported for this star. With the goal of reproducing the revised dynamical mass derived by Pourbaix & Boffin, we modelled the star using two stellar grids varying in the adopted nuclear reaction rates. Asteroseismic and spectroscopic observables were complemented with different interferometric radius constraints during the optimisation procedure. Our findings show that best-fit models reproducing the revised dynamical mass favour the existence of a convective core (≳ 70% of best-fit models), a result that is robust against changes to the model physics. If this mass is accurate, then α Centauri A may be used to calibrate stellar model parameters in the presence of a convective core.
Energy Technology Data Exchange (ETDEWEB)
Chen, N.C.J.; Wendel, M.W.; Yoder, G.L.
1996-02-01
In order to utilize reduced enrichment fuel, the three-element-core design has been proposed. The proposed core configuration consists of inner, middle, and outer elements, with the middle element offset axially beneath the inner and outer elements, which are axially aligned. The three-element-core RELAP5 model assumes that the reactor hardware is changed only within the core region, so that the loop piping, heat exchangers, and pumps remain as assumed for the two-element-core configuration. However, the total flow rate through the core is greater and the pressure drop across the core is less so that the primary coolant pumps and heat exchangers are operating at a different point in their performance curves. This report describes the new RELAP5 input for the core components.
Investigation on macroscopic cross section model for BWR pin-by-pin core analysis - 118
International Nuclear Information System (INIS)
Fujita, T.; Tada, K.; Yamamoto, A.; Yamane, Y.; Kosaka, S.; Hirano, G.
2010-01-01
A cross section model used in the pin-by-pin core analysis for BWR is investigated. In the pin-by-pin core calculation method, pin-cell averaged cross sections are calculated for many combinations of state and history variables that have influences on the cross section and are tabulated prior to the core calculations. Variation of a cross section in a core simulator is classified into two different types, i.e., the instantaneous effect and the history effect. The instantaneous effect is incorporated by the variation of cross section which is caused by the instantaneous change of state variables. For this effect, the exposure, the void fraction, the fuel temperature, the moderator temperature and the control rod are used as indexes. The history effect is the cumulative effect of state variables. We treat this effect with a unified approach using the spectral history. To confirm accuracy of the cross section model, the pin-by-pin fission rate distribution and the k-infinity of fuel assembly which are obtained with the tabulated and the reference cross sections are compared. For the instantaneous effect, the present cross section model well reproduces the reference results for all off-nominal conditions. For the history effect, however, considerable differences both on the pin-by-pin fission rate distribution and the k-infinity are observed at high exposure points. (authors)
VIPRE-01. a thermal-hydraulic analysis code for reactor cores. Volume 1. Mathematical modeling
International Nuclear Information System (INIS)
Stewart, C.W.; Cuta, J.M.; Koontz, A.S.; Kelly, J.M.; Basehore, K.L.; George, T.L.; Rowe, D.S.
1983-04-01
VIPRE (Versatile Internals and Component Program for Reactors; EPRI) has been developed for nuclear power utility thermal-hydraulic analysis applications. It is designed to help evaluate nuclear reactor core safety limits including minimum departure from nucleate boiling ratio (MDNBR), critical power ratio (CPR), fuel and clad temperatures, and coolant state in normal operation and assumed accident conditions. This volume (Volume 1: Mathematical Modeling) explains the major thermal hydraulic models and supporting correlations in detail
Final Report: Legion Core Object Model, March 1, 1996 - September 30, 1999
Energy Technology Data Exchange (ETDEWEB)
Grimshaw, Andrew S.
1999-09-30
The model specifies the composition and functionality of Legion's core objects - those objects that cooperate to create, locate, manage, and remove objects from the legion project. In particular, the object model facilitates a flexible extensible implementation, provides a single persistent name space, grants site autonomy to participating organizations, and scales to millions of sites and trillions of objects. Further, it offers a framework that is well suited to providing mechanisms for high performance, security, fault tolerance and commerce.
Heyde, I.; Girolami, C.; Barckhausen, U.; Freitag, R.
2017-12-01
Hydrothermal vent fields along mid-ocean ridges can be metal-rich and thus of great importance for the industries in the future. By order of the German Federal Ministry of Economics and in coordination with the International Seabed Authority (ISA), BGR explores potential areas of the active spreading system in the Indian Ocean. A main goal is the identification of inactive seafloor massive sulfides (SMS) with the aid of modern exploration techniques. Important contributions could be expected from bathymetric, magnetic, and gravity datasets, which can be acquired simultaneously time from the sea surface within relatively short ship time. The area of interest is located between 21°S and 28°S and includes the southern Central Indian Ridge (CIR) and the northern Southeast Indian Ridge (SEIR). In this study we analyzed the marine gravity and bathymetric data acquired during six research cruises. The profiles running perpendicular to the ridge axis have a mean length of 60 km. Magnetic studies reveal that the parts of the ridges covered are geologically very young with the oldest crust dating back to about 1 Ma. To extend the area outside the ridges, the shipboard data were complemented with data derived from satellite radar altimeter measurements. We analyzed the gravity anomalies along sections which cross particular geologic features (uplifted areas, accommodation zones, hydrothermal fields, and areas with hints for extensional processes e.g. oceanic core complexes) to establish a correlation between the gravity anomalies and the surface geology. Subsequently, for both ridge segments 3D density models were developed. We started with simple horizontally layered models, which, however, do not explain the measured anomalies satisfyingly. The density values of the crust and the upper mantle in the ridge areas had to be reduced. Finally, the models show the lateral heterogeneity and the variations in the thickness of the oceanic crust. There are areas characterized by
Observation and excitation of magnetohydrodynamic waves in numerical models of Earth's core
Teed, R.; Hori, K.; Tobias, S.; Jones, C. A.
2017-12-01
Several types of magnetohydrodynamic waves are theorised to operate in Earth's outer core but their detection is limited by the inability to probe the fluid core directly. Secular variation data and periodic changes in Earth's length-of-day provide evidence for the possible existence of waves. Numerical simulations of core dynamics enable us to search directly for waves and determine their properties. With this information it is possible to consider whether they can be the origin of features observed in observational data. We focus on two types of wave identified in our numerical experiments: i) torsional waves and ii) slow magnetic Rossby waves. Our models display periodic, Earth-like torsional waves that travel outwards from the tangent cylinder circumscribing the inner core. We discuss the properties of these waves and their similarites to observational data. Excitation is via a matching of the Alfvén frequency with that of small modes of convection focused at the tangent cylinder. The slow magnetic Rossby waves observed in our simulations show that these waves may account for some geomagnetic westward drifts observed at mid-latitudes. We present analysis showing excitation of waves by the convective instability and we discuss how the detection of these waves could also provide an estimate of the strength of the toroidal component of the magnetic field within the planetary fluid core.
Studies of mixed HEU-LEU-MTR cores using 3D models
Energy Technology Data Exchange (ETDEWEB)
Haenggi, P.; Lehmann, E.; Hammer, J.; Christen, R. [Paul Scherrer Institute, Villigen (Switzerland)
1997-08-01
Several different core loadings were assembled at the SAPHIR research reactor in Switzerland combining the available types of MTR-type fuel elements, consisting mainly of both HEU and LEU fuel. Bearing in mind the well known problems which can occur in such configurations (especially power peaking), investigations have been carried out for each new loading with a 2D neutron transport code (BOXER). The axial effects were approximated by a global buckling value and therefore the radial effects could be studied in considerably detail. Some of the results were reported at earlier RERTR meetings and were compared to those obtained by other methods and with experimental values. For the explicit study of the third dimension of the core, another code (SILWER), which has been developed in PSI for LWR power plant cores, has been selected. With the help of an adapted model for the MTR-core of SAPHIR, several important questions have been addressed. Among other aspects, the estimation of the axial contribution to the hot channel factors, the influence of the control rod position and of the Xe-poisoning on the power distribution were studied. Special attention was given to a core position where a new element was assumed placed near a empty, water filled position. The comparison of elements of low and high enrichments at this position was made in terms of the induced power peaks, with explicit consideration of axial effects. The program SILWER has proven to be applicable to MTR-cores for the investigation of axial effects. For routine use as for the support of reactor operation, this 3D code is a good supplement to the standard 2D model.
A model for osmium isotopic evolution of metallic solids at the core-mantle boundary
Humayun, Munir
2011-03-01
Some plumes are thought to originate at the core-mantle boundary, but geochemical evidence of core-mantle interaction is limited to Os isotopes in samples from Hawaii, Gorgona (89 Ma), and Kostomuksha (2.7 Ga). The Os isotopes have been explained by physical entrainment of Earth's liquid outer core into mantle plumes. This model has come into conflict with geophysical estimates of the timing of core formation, high-pressure experimental determinations of the solid metal-liquid metal partition coefficients (D), and the absence of expected 182W anomalies. A new model is proposed where metallic liquid from the outer core is partially trapped in a compacting cumulate pile of Fe-rich nonmetallic precipitates (FeO, FeS, Fe3Si, etc.) at the top of the core and undergoes fractional crystallization precipitating solid metal grains, followed by expulsion of the residual metallic liquid back to the outer core. The Os isotopic composition of the solids and liquids in the cumulate pile is modeled as a function of the residual liquid remaining and the emplacement age using 1 bar D values, with variable amounts of oxygen (0-10 wt %) as the light element. The precipitated solids evolve Os isotope compositions that match the trends for Hawaii (at an emplacement age of 3.5-4.5 Ga; 5%-10% oxygen) and Gorgona (emplacement age < 1.5 Ga; 0%-5% oxygen). The Fe-rich matrix of the cumulate pile dilutes the precipitated solid metal decoupling the Fe/Mn ratio from Os and W isotopes. The advantages to using precipitated solid metal as the Os host include a lower platinum group element and Ni content to the mantle source region relative to excess iron, miniscule anomalies in 182W (<0.1 ɛ), and no effects for Pb isotopes, etc. A gradual thermomechanical erosion of the cumulate pile results in incorporation of this material into the base of the mantle, where mantle plumes subsequently entrain it. Fractional crystallization of metallic liquids within the CMB provides a consistent explanation of
Modeling the reactor core of MNSR to simulate its dynamic behavior using the code PARET
International Nuclear Information System (INIS)
Hainoun, A.; Alhabet, F.
2004-02-01
Using the computer code PARET the core of the MNSR reactor was modelled and the neutronics and thermal hydraulic behaviour of the reactor core for the steady state and selected transients, that deal with step change of reactivity including control rod withdraw starting from steady state at various low power level, were simulated. For this purpose a PARET input model for the core of MNSR reactor has been developed enabling the simulation of neutron kinetic and thermal hydraulic of reactor core including reactivity feedback effects. The neutron kinetic model depends on the point kinetic with 15 groups delayed neutrons including photo neutrons of beryllium reflector. In this regard the effect of photo neutron on the dynamic behaviour has been analysed through two additional calculation. In the first the yield of photo neutrons was neglected completely and in the second its share was added to the sixth group of delayed neutrons. In the thermal hydraulic model the fuel elements with their cooling channels were distributed to 4 different groups with various radial power factors. The pressure lose factors for friction, flow direction change, expansion and contraction were estimated using suitable approaches. The post calculations of the relative neutron flux change and core average temperature were found to be consistent with the experimental measurements. Furthermore, the simulation has indicated the influence of photo neutrons of the Beryllium reflector on the neutron flux behaviour. For the reliability of the results sensitivity analysis was carried out to consider the uncertainty in some important parameters like temperature feedback coefficient and flow velocity. On the other hand the application of PARET in simulation of void formation in the subcooled boiling regime were tested. The calculation indicates the capability of PARET in modelling this phenomenon. However, big discrepancy between calculation results and measurement of axial void distribution were observed
Sojeong Kim,; Seungjun Lee,; Hyungsoon Shin,
2010-04-01
In spin transfer torque (STT)-based magnetic tunnel junction (MTJ), the switching depends on the current pulse-width as well as the magnitude of the switching current. We present an advanced macro-model of an STT-MTJ for a circuit simulator such as HSPICE. The macro-model can simulate the dependence of switching behavior on current pulse-width in an STT-MTJ. An imaginary resistor-capacitor (RC) circuit is adopted to emulate complex timing behavior which cannot be described nicely by existing functions in HSPICE. Simulation results show the resistance-current (R-I) curve and timing behavior is in good agreement with the experimental data.
Assessment of TRAC-PD2 reflood core thermo-hydraulic model by CCTF Test C1-16
International Nuclear Information System (INIS)
Sugimoto, Jun
1982-11-01
The TRAC-PD2 reflood core thermo-hydraulic model was assessed by CCTF Test C1-16. The measured data were utilized as core boundary conditions in the TRAC calculations. The results indicate that the core inlet liquid temperature and the core heater rod temperatures are in reasonable agreement with data, but the pressure distribution in the core and water pool formation in the upper plenum are not in good agreement. The parametric effects of the droplet critical Weber number, the material properties of the heater rod, the noding of the upper plenum, and the minimum stable film boiling temperature are also discussed. (author)
Support for Programming Models in Network-on-Chip-based Many-core Systems
DEFF Research Database (Denmark)
Rasmussen, Morten Sleth
This thesis addresses aspects of support for programming models in Network-on- Chip-based many-core architectures. The main focus is to consider architectural support for a plethora of programming models in a single system. The thesis has three main parts. The first part considers parallelization...... models to be supported by a single architecture. The architecture features a specialized network interface processor which allows extensive configurability of the memory system. Based on this architecture, a detailed implementation of the cache coherent shared memory programming model is presented...
Modeling Polarized Emission from Black Hole Jets: Application to M87 Core Jet
Directory of Open Access Journals (Sweden)
Monika Mościbrodzka
2017-09-01
Full Text Available We combine three-dimensional general-relativistic numerical models of hot, magnetized Advection Dominated Accretion Flows around a supermassive black hole and the corresponding outflows from them with a general relativistic polarized radiative transfer model to produce synthetic radio images and spectra of jet outflows. We apply the model to the underluminous core of M87 galaxy. The assumptions and results of the calculations are discussed in context of millimeter observations of the M87 jet launching zone. Our ab initio polarized emission and rotation measure models allow us to address the constrains on the mass accretion rate onto the M87 supermassive black hole.
Energy Technology Data Exchange (ETDEWEB)
Iben, I. Jr.; Tutukov, A.V. (Illinois Univ., Urbana (USA); Astronomicheskii Sovet, Moscow (USSR))
1989-07-01
The characteristics of model stars consisting of a degenerate dwarf core and an envelope which is burning a nuclear fuel or fuels in its interior are explored. The models are relevant to stars which are accreting matter from a companion, to single stars in late stages of evolution, to stripped noninteracting remnants of binary star evolution, and to merging and merged degenerate dwarfs. For any given mass and choice of nuclear fuels, a sequence of models is constructed which differ with respect to the mass of the degenerate core and the envelope characteristics. Each sequence has at least three distinct branches: a degenerate dwarf branch along which envelope mass increases with decreasing luminosity, a plateau branch characterized by a very small envelope mass and by a nearly constant luminosity which reaches the maximum achievable value for the sequence, and an asymptotic giant branch which is at the lowest temperatures achievable and along which envelope mass decreases with increasing luminosity. 78 refs.
International Nuclear Information System (INIS)
Iben, I. Jr.; Tutukov, A.V.
1989-01-01
The characteristics of model stars consisting of a degenerate dwarf core and an envelope which is burning a nuclear fuel or fuels in its interior are explored. The models are relevant to stars which are accreting matter from a companion, to single stars in late stages of evolution, to stripped noninteracting remnants of binary star evolution, and to merging and merged degenerate dwarfs. For any given mass and choice of nuclear fuels, a sequence of models is constructed which differ with respect to the mass of the degenerate core and the envelope characteristics. Each sequence has at least three distinct branches: a degenerate dwarf branch along which envelope mass increases with decreasing luminosity, a plateau branch characterized by a very small envelope mass and by a nearly constant luminosity which reaches the maximum achievable value for the sequence, and an asymptotic giant branch which is at the lowest temperatures achievable and along which envelope mass decreases with increasing luminosity. 78 refs
Directory of Open Access Journals (Sweden)
Dessanti Putri Sekti Ari
2017-03-01
Full Text Available The purpose of this study was to examine the antecedents that affected the acceptance of individuals in using theCore Banking System through the constructs Technology Acceptance Model and its development. Constructsused in this study were perceived usefulness, perceived ease of use, attitude, social influences, behavioral inten-tion, facilitating conditions, and behavior. Data were collected through survey methods. The samples of thisstudy were employees working in commercial banks in Malang Raya. This study used 136 respondents and wasanalyzed by smart PLS. The result of this study was that the construct of perceived usefulness and perceived easeof use in the Technology Acceptance Model affected attitude and behavior. Attitude and behavior in the Technol-ogy Acceptance Model and social influence which was the development of the Technology Acceptance Modelaffected behavioral intention to use the Core Banking System, as well as the construct of behavioral intention inTechnology Acceptance Model affected behavior, whereas construct of facilitating conditions which was thedevelopment of the Technology Acceptance Model did not affect the behavior on using the Core Banking System.
Multiregional coupled conduction--convection model for heat transfer in an HTGR core
International Nuclear Information System (INIS)
Giles, G.E. Jr.; Childs, K.W.; Sanders, J.P.
1978-01-01
HEXEREI is a three-dimensional, coupled conduction-convection heat transfer and multichannel fluid dynamic analysis computer code with both steady-state and transient capabilities. The program was developed to provide thermal-fluid dynamic analysis of a core following the general design for high-temperature gas-cooled reactors (HTGRs); its purpose was to provide licensing evaluations for the U.S. Nuclear Regulatory Commission. In order to efficiently model the HTGR core, the nodal geometry of HEXEREI was chosen as a regular hexagonal array perpendicular to the axis of and bounded by a right circular cylinder. The cylindrical nodal geometry surrounds the hexagonal center portion of the mesh; these two different types of nodal geometries must be connected by interface nodes to complete the accurate modeling of the HTGR core. HEXEREI will automatically generate a nodal geometry that will accurately model a complex assembly of hexagonal and irregular prisms. The accuracy of the model was proven by a comparison of computed values with analytical results for steady-state and transient heat transfer problems. HEXEREI incorporates convective heat transfer to the coolant in many parallel axial flow channels. Forced and natural convection (which permits different flow directions in parallel channels) is included in the heat transfer and fluid dynamic models. HEXEREI incorporates a variety of steady-state and transient solution techniques that can be matched with a particular problem to minimize the computational time. HEXEREI was compared with a code of similar capabilities that was based on a Cartesian mesh. This code modeled only one specific core design, and the mesh spacing was closer than that generated by HEXEREI. Good agreement was obtained with the detail provided by the representations
International Nuclear Information System (INIS)
Palau, J.M.; Cathalau, S.; Hudelot, J.P.; Barran, F.; Bellanger, V.; Magnaud, C.; Moreau, F.
2011-01-01
Burnable poisons are extensively used by Light Water Reactor designers in order to preserve the fuel reactivity potential and increase the cycle length (without increasing the uranium enrichment). In the industrial two-steps (assembly 2D transport-core 3D diffusion) calculation schemes these heterogeneities yield to strong flux and cross-sections perturbations that have to be taken into account in the final 3D burn-up calculations. This paper presents the application of an enhanced cross-section interpolation model (implemented in the French CRONOS2 code) to LWR (highly poisoned) depleted core calculations. The principle is to use the absorbers (or actinide) concentrations as the new interpolation parameters instead of the standard local burnup/fluence parameters. It is shown by comparing the standard (burnup/fluence) and new (concentration) interpolation models and using the lattice transport code APOLLO2 as a numerical reference that reactivity and local reaction rate prediction of a 2x2 LWR assembly configuration (slab geometry) is significantly improved with the concentration interpolation model. Gains on reactivity and local power predictions (resp. more than 1000 pcm and 20 % discrepancy reduction compared to the reference APOLLO2 scheme) are obtained by using this model. In particular, when epithermal absorbers are inserted close to thermal poison the 'shadowing' ('screening') spectral effects occurring during control operations are much more correctly modeled by concentration parameters. Through this outstanding example it is highlighted that attention has to be paid to the choice of cross-section interpolation parameters (burnup 'indicator') in core calculations with few energy groups and variable geometries all along the irradiation cycle. Actually, this new model could be advantageously applied to steady-state and transient LWR heterogeneous core computational analysis dealing with strong spectral-history variations under
Molecular series-tunneling junctions.
Liao, Kung-Ching; Hsu, Liang-Yan; Bowers, Carleen M; Rabitz, Herschel; Whitesides, George M
2015-05-13
Charge transport through junctions consisting of insulating molecular units is a quantum phenomenon that cannot be described adequately by classical circuit laws. This paper explores tunneling current densities in self-assembled monolayer (SAM)-based junctions with the structure Ag(TS)/O2C-R1-R2-H//Ga2O3/EGaIn, where Ag(TS) is template-stripped silver and EGaIn is the eutectic alloy of gallium and indium; R1 and R2 refer to two classes of insulating molecular units-(CH2)n and (C6H4)m-that are connected in series and have different tunneling decay constants in the Simmons equation. These junctions can be analyzed as a form of series-tunneling junctions based on the observation that permuting the order of R1 and R2 in the junction does not alter the overall rate of charge transport. By using the Ag/O2C interface, this system decouples the highest occupied molecular orbital (HOMO, which is localized on the carboxylate group) from strong interactions with the R1 and R2 units. The differences in rates of tunneling are thus determined by the electronic structure of the groups R1 and R2; these differences are not influenced by the order of R1 and R2 in the SAM. In an electrical potential model that rationalizes this observation, R1 and R2 contribute independently to the height of the barrier. This model explicitly assumes that contributions to rates of tunneling from the Ag(TS)/O2C and H//Ga2O3 interfaces are constant across the series examined. The current density of these series-tunneling junctions can be described by J(V) = J0(V) exp(-β1d1 - β2d2), where J(V) is the current density (A/cm(2)) at applied voltage V and βi and di are the parameters describing the attenuation of the tunneling current through a rectangular tunneling barrier, with width d and a height related to the attenuation factor β.
Simulating High Flux Isotope Reactor Core Thermal-Hydraulics via Interdimensional Model Coupling
Energy Technology Data Exchange (ETDEWEB)
Travis, Adam R [ORNL
2014-05-01
A coupled interdimensional model is presented for the simulation of the thermal-hydraulic characteristics of the High Flux Isotope Reactor core at Oak Ridge National Laboratory. The model consists of two domains a solid involute fuel plate and the surrounding liquid coolant channel. The fuel plate is modeled explicitly in three-dimensions. The coolant channel is approximated as a twodimensional slice oriented perpendicular to the fuel plate s surface. The two dimensionally-inconsistent domains are linked to one another via interdimensional model coupling mechanisms. The coupled model is presented as a simplified alternative to a fully explicit, fully three-dimensional model. Involute geometries were constructed in SolidWorks. Derivations of the involute construction equations are presented. Geometries were then imported into COMSOL Multiphysics for simulation and modeling. Both models are described in detail so as to highlight their respective attributes in the 3D model, the pursuit of an accurate, reliable, and complete solution; in the coupled model, the intent to simplify the modeling domain as much as possible without affecting significant alterations to the solution. The coupled model was created with the goal of permitting larger portions of the reactor core to be modeled at once without a significant sacrifice to solution integrity. As such, particular care is given to validating incorporated model simplifications. To the greatest extent possible, the decrease in solution time as well as computational cost are quantified versus the effects such gains have on the solution quality. A variant of the coupled model which sufficiently balances these three solution characteristics is presented alongside the more comprehensive 3D model for comparison and validation.
Modelling mechanical properties of the multilayer composite materials with the polyamide core
Directory of Open Access Journals (Sweden)
Talaśka Krzysztof
2018-01-01
Full Text Available Due to the wide range of application for belt conveyors, engineers look for many different combinations of mechanical properties of conveyor and transmission belts. It can be made by creating multilayer or fibre reinforced composite materials from base thermoplastic or thermosetting polymers. In order to gain high strength with proper elasticity and friction coefficient, the core of the composite conveyor belt is made of polyamide film core, which can be combined with various types of polymer fabrics, films or even rubbers. In this paper authors show the complex model of multilayer composite belt with the polyamide core, which can be used in simulation analyses. The following model was derived based on the experimental research, which consisted of tensile, compression and shearing tests. In order to achieve the most accurate model, proper simulations in ABAQUS were made and then the results were compared with empirical mechanical characteristics of a conveyor belt. The main goal of this research is to fully describe the perforation process of conveyor and transmission belts for vacuum belt conveyors. The following model will help to develop design briefs for machines used for mechanical perforation.
Analytical investigation of a one-dimensional homogenized model for a pressurized water reactor core
International Nuclear Information System (INIS)
Benner, J.; Schumann, U.
1981-01-01
A one-dimensional homogenized model for dynamic fluid-structure interaction in a pressurized water reactor core is used to study the influence of the virtual density and spacer's stiffness. The model consists of a linear system of partial differential equations for fluid velocity, rod velocity and pressure. For these equations analytical solutions are deduced for boundary conditions prescribing either periodic wall oscillations or linearly growing wall accelerations from rest. The theoretical model for the virtual density is verified by comparison to an experiment. For zero spacer stiffness, purely acoustic oscillations appear. For positive spacer stiffness, additional oscillations arise with relative rod motions. The wavelengths of the latter oscillations are small for weak spacers. Large numerical effort would be required in a more complete three-dimensional core-model to resolve such short wave lengths. In fact in a typical core the spacer's stiffness csub(S) is small in comparison to the fluid bulk modulus K. For csub(s)/K <= 0.1 it might be appropriate to neglect the influence of the spacers. (orig.)
Development of Reactor Core Model based on Optimal Analysis for Shinhanul no. 1, 2 Simulator
Energy Technology Data Exchange (ETDEWEB)
Kim, Kyung-min [Korea Hydro Nuclear Power Co., Daejeon (Korea, Republic of)
2016-10-15
As one of the outputs of 'Development of the Shin Hanul Nuclear Plant(SHN) 1,2 Simulator' project which is being done by KHNP Central Research Institute, the SHN1,2 Simulator is being developed including the KNICS methodology and advanced Alarm Systems first applied to the Nuclear Power Plant in Korea, and the SHN 1,2 simulator adopts the virtually stimulated HMI(Human-Machine Interface) for the non-safety MMIS system, whose key-programs are identical to those applied to the real SHN 1,2 plants. The purpose of this paper is to develop localization core model by integrating the Simulator system with the Simulator core model though technology agreement of KAERI. To develop ShinHanul 1 and 2 reactor core simulator model, KHNP and KAERI create MASTER-SIM model and tried validation. And calculations of MASSIM{sub S}S program for MASTER{sub S}IM validation, are within tolerance range. Test has not yet been completed. And many verification will be conducted MASTER-SIM software is expected to be the highest economic software and satisfy international simulator standards.
On Input Vector Representation for the SVR model of Reactor Core Loading Pattern Critical Parameters
International Nuclear Information System (INIS)
Trontl, K.; Pevec, D.; Smuc, T.
2008-01-01
Determination and optimization of reactor core loading pattern is an important factor in nuclear power plant operation. The goal is to minimize the amount of enriched uranium (fresh fuel) and burnable absorbers placed in the core, while maintaining nuclear power plant operational and safety characteristics. The usual approach to loading pattern optimization involves high degree of engineering judgment, a set of heuristic rules, an optimization algorithm and a computer code used for evaluating proposed loading patterns. The speed of the optimization process is highly dependent on the computer code used for the evaluation. Recently, we proposed a new method for fast loading pattern evaluation based on general robust regression model relying on the state of the art research in the field of machine learning. We employed Support Vector Regression (SVR) technique. SVR is a supervised learning method in which model parameters are automatically determined by solving a quadratic optimization problem. The preliminary tests revealed a good potential of the SVR method application for fast and accurate reactor core loading pattern evaluation. However, some aspects of model development are still unresolved. The main objective of the work reported in this paper was to conduct additional tests and analyses required for full clarification of the SVR applicability for loading pattern evaluation. We focused our attention on the parameters defining input vector, primarily its structure and complexity, and parameters defining kernel functions. All the tests were conducted on the NPP Krsko reactor core, using MCRAC code for the calculation of reactor core loading pattern critical parameters. The tested input vector structures did not influence the accuracy of the models suggesting that the initially tested input vector, consisted of the number of IFBAs and the k-inf at the beginning of the cycle, is adequate. The influence of kernel function specific parameters (σ for RBF kernel
Understanding variability of the Southern Ocean overturning circulation in CORE-II models
Downes, S. M.; Spence, P.; Hogg, A. M.
2018-03-01
The current generation of climate models exhibit a large spread in the steady-state and projected Southern Ocean upper and lower overturning circulation, with mechanisms for deep ocean variability remaining less well understood. Here, common Southern Ocean metrics in twelve models from the Coordinated Ocean-ice Reference Experiment Phase II (CORE-II) are assessed over a 60 year period. Specifically, stratification, surface buoyancy fluxes, and eddies are linked to the magnitude of the strengthening trend in the upper overturning circulation, and a decreasing trend in the lower overturning circulation across the CORE-II models. The models evolve similarly in the upper 1 km and the deep ocean, with an almost equivalent poleward intensification trend in the Southern Hemisphere westerly winds. However, the models differ substantially in their eddy parameterisation and surface buoyancy fluxes. In general, models with a larger heat-driven water mass transformation where deep waters upwell at the surface ( ∼ 55°S) transport warmer waters into intermediate depths, thus weakening the stratification in the upper 2 km. Models with a weak eddy induced overturning and a warm bias in the intermediate waters are more likely to exhibit larger increases in the upper overturning circulation, and more significant weakening of the lower overturning circulation. We find the opposite holds for a cool model bias in intermediate depths, combined with a more complex 3D eddy parameterisation that acts to reduce isopycnal slope. In summary, the Southern Ocean overturning circulation decadal trends in the coarse resolution CORE-II models are governed by biases in surface buoyancy fluxes and the ocean density field, and the configuration of the eddy parameterisation.
Review of the SCDAP/RELAP5/MOD3.1 code structure and core T/H model before core damage
International Nuclear Information System (INIS)
Kim, See Darl; Kim, Dong Ha
1998-04-01
The SCDAP/RELAP5 code has been developed for best estimate transient simulation of light water reactor coolant systems during a severe accident. The code is being developed at the INEL under the primary sponsorship of the Office of Nuclear Regulatory Research of the U.S. NRC. As The current time, the SCDAP/RELAP5/MOD3.1 code is the result of merging the RELAP5/MOD3 and SCDAP models. The code models the coupled behavior of the reactor coolant system, core, fission product released during a severe accident transient as well as large and small break loss of coolant accidents, operational transients such as anticipated transient without SCRAM, loss of offsite power, loss of feedwater, and loss of flow. Major purpose of the report is to provide information about the characteristics of SCDAP/RELAP5/MOD3.1 core T/H models for an integrated severe accident computer code being developed under the mid/long-term project. This report analyzes the overall code structure which consists of the input processor, transient controller, and plot file handler. The basic governing equations to simulate the thermohydraulics of the primary system are also described. As the focus is currently concentrated in the core, core nodalization parameters of the intact geometry and the phenomenological subroutines for the damaged core are summarized for the future usage. In addition, the numerical approach for the heat conduction model is investigated along with heat convection model. These studies could provide a foundation for input preparation and model improvement. (author). 6 refs., 3 tabs., 4 figs
Steady State Modelling of Three-core Wire Armoured Submarine Cables
DEFF Research Database (Denmark)
Baù, Matteo; Viafora, Nicola; Hansen, Chris Skovgaard
2016-01-01
This paper introduces Finite Element Method mod-elling techniques applied to wire armoured submarine three-core cables, whose nominal voltages range from 36 to 245 kV. The analysis is focused on the implementation of the net voltage cancellation principle in a 2D environment. The model is utilised...... confirm that the wire armour stranding is not accounted for, but also suggest that the ampacity underrating might be due to other inaccuracies in the IEC modelling indications. Overall, the difference in terms of current rating between the FEM and the IEC approach is found to be voltage dependent and more...
Symplectic no-core shell-model approach to intermediate-mass nuclei
Tobin, G. K.; Ferriss, M. C.; Launey, K. D.; Dytrych, T.; Draayer, J. P.; Dreyfuss, A. C.; Bahri, C.
2014-03-01
We present a microscopic description of nuclei in the intermediate-mass region, including the proximity to the proton drip line, based on a no-core shell model with a schematic many-nucleon long-range interaction with no parameter adjustments. The outcome confirms the essential role played by the symplectic symmetry to inform the interaction and the winnowing of shell-model spaces. We show that it is imperative that model spaces be expanded well beyond the current limits up through 15 major shells to accommodate particle excitations, which appear critical to highly deformed spatial structures and the convergence of associated observables.
Drilling induced damage of core samples. Evidences from laboratory testing and numerical modelling
International Nuclear Information System (INIS)
Lanaro, Flavio
2008-01-01
Extensive sample testing in uniaxial and Brazilian test conditions were carried out for the Shobasama and MIU Research Laboratory Site (Gifu Pref., Japan). The compressive and tensile strength of the samples was observed to be negatively correlated to the in-situ stress components. Such correlation was interpreted as stress-release induced sample damage. Similar stress conditions were then numerically simulated by means of the BEM-DDM code FRACOD 2D in plane strain conditions. This method allows for explicitly consider the influence of newly initiated or propagating fractures on the stress field and deformation of the core during drilling process. The models show that already at moderate stress levels some fracturing of the core during drilling might occur leading to reduced laboratory strength of the samples. Sample damage maps were produced independently from the laboratory test results and from the numerical models and show good agreement with each other. (author)
Network evolution model for supply chain with manufactures as the core
Jiang, Dali; Fang, Ling; Yang, Jian; Li, Wu; Zhao, Jing
2018-01-01
Building evolution model of supply chain networks could be helpful to understand its development law. However, specific characteristics and attributes of real supply chains are often neglected in existing evolution models. This work proposes a new evolution model of supply chain with manufactures as the core, based on external market demand and internal competition-cooperation. The evolution model assumes the external market environment is relatively stable, considers several factors, including specific topology of supply chain, external market demand, ecological growth and flow conservation. The simulation results suggest that the networks evolved by our model have similar structures as real supply chains. Meanwhile, the influences of external market demand and internal competition-cooperation to network evolution are analyzed. Additionally, 38 benchmark data sets are applied to validate the rationality of our evolution model, in which, nine manufacturing supply chains match the features of the networks constructed by our model. PMID:29370201
Network evolution model for supply chain with manufactures as the core.
Fang, Haiyang; Jiang, Dali; Yang, Tinghong; Fang, Ling; Yang, Jian; Li, Wu; Zhao, Jing
2018-01-01
Building evolution model of supply chain networks could be helpful to understand its development law. However, specific characteristics and attributes of real supply chains are often neglected in existing evolution models. This work proposes a new evolution model of supply chain with manufactures as the core, based on external market demand and internal competition-cooperation. The evolution model assumes the external market environment is relatively stable, considers several factors, including specific topology of supply chain, external market demand, ecological growth and flow conservation. The simulation results suggest that the networks evolved by our model have similar structures as real supply chains. Meanwhile, the influences of external market demand and internal competition-cooperation to network evolution are analyzed. Additionally, 38 benchmark data sets are applied to validate the rationality of our evolution model, in which, nine manufacturing supply chains match the features of the networks constructed by our model.
Network evolution model for supply chain with manufactures as the core.
Directory of Open Access Journals (Sweden)
Haiyang Fang
Full Text Available Building evolution model of supply chain networks could be helpful to understand its development law. However, specific characteristics and attributes of real supply chains are often neglected in existing evolution models. This work proposes a new evolution model of supply chain with manufactures as the core, based on external market demand and internal competition-cooperation. The evolution model assumes the external market environment is relatively stable, considers several factors, including specific topology of supply chain, external market demand, ecological growth and flow conservation. The simulation results suggest that the networks evolved by our model have similar structures as real supply chains. Meanwhile, the influences of external market demand and internal competition-cooperation to network evolution are analyzed. Additionally, 38 benchmark data sets are applied to validate the rationality of our evolution model, in which, nine manufacturing supply chains match the features of the networks constructed by our model.
Energy Technology Data Exchange (ETDEWEB)
Wang, Guo Xu; Wu, Jie; Zeng, Bifan; Wu, Wangqiang; Ma, Xiao Qian [School of Electric Power, South China University of Technology, Guangzhou (China); Xu, Zhibin [Electric Power Research Institute of Guangdong Power Grid Corporation, Guangzhou (China)
2017-02-15
A well-performed core power control to track load changes is crucial in pressurized water reactor (PWR) nuclear power stations. It is challenging to keep the core power stable at the desired value within acceptable error bands for the safety demands of the PWR due to the sensitivity of nuclear reactors. In this paper, a state-space model predictive control (MPC) method was applied to the control of the core power. The model for core power control was based on mathematical models of the reactor core, the MPC model, and quadratic programming (QP). The mathematical models of the reactor core were based on neutron dynamic models, thermal hydraulic models, and reactivity models. The MPC model was presented in state-space model form, and QP was introduced for optimization solution under system constraints. Simulations of the proposed state-space MPC control system in PWR were designed for control performance analysis, and the simulation results manifest the effectiveness and the good performance of the proposed control method for core power control.
Arboleda Zapata, M. D. J., Sr.; Arzate-Flores, J.; Guevara Betancourt, R. E., Sr.
2017-12-01
The Jalisco Block is a continental microplate produced by the extension along three large structures: the Tepic-Zacoalco rift (TZR), the Colima rift (CR) and the Chapala rift that converge in a triple junction 50 km southwest of Guadalajara, Mexico, with orientation NW-SE, N-S, and E-W respectively. The present study focuses on investigating the deep structure of the north Colima and eastern Zacoalco grabens close to the Guadalajara triple junction (GTJ). This is a first study of its type that provide insight on the grabens structures and crustal characteristics underneath. We measured along two magnetotellurics (MT) profiles that cut perpendicularly the TZR (profile ZAC), and the northern CR (profile SAY) comprising a total of 24 broad band MT soundings. The ZAC profile has 11 stations and has a NE orientation, and the SAY profile has 14 station aligned E-W. Standard processing and editing procedures were completed, and distortion analysis was applied to the data set in order to define the dimensionality and electric strike of the separated profiles. Static shift was corrected using geology information to distinguish the different types of soundings and later averaging for those soundings located over the same lithology. The Bahr dimensionality parameters showed that the medium is mainly 3D for the SAY profile and 2D for the ZAC profile; furthermore, the regional geoelectric strike azimuth calculated with Bahr methodology were -4° and -48° respectively, with good concordance with the main surface structures. The tipper analysis permitted validated these results, as the real induction vectors were nearly perpendicular to main fault structures. All soundings were rotated to the respective regional strike and a 2D simultaneous inversion of the transverse electric (TE) mode, the transvers magnetic (TM) mode and the Tipper was completed. The RMS fitting error yield 3.2% for ZAC profile and 3.7% for SAY profile. Both profiles show a shallow conductive zone at north of
Primary Tunnel Junction Thermometry
International Nuclear Information System (INIS)
Pekola, Jukka P.; Holmqvist, Tommy; Meschke, Matthias
2008-01-01
We describe the concept and experimental demonstration of primary thermometry based on a four-probe measurement of a single tunnel junction embedded within four arrays of junctions. We show that in this configuration random sample specific and environment-related errors can be avoided. This method relates temperature directly to Boltzmann constant, which will form the basis of the definition of temperature and realization of official temperature scales in the future
Kõrge, Kristina; Berndt, Nadine; Hohmann, Juergen; Romano, Florence; Hiligsmann, Mickael
2017-01-01
The health technology assessment (HTA) Core Model® is a tool for defining and standardizing the elements of HTA analyses within several domains for producing structured reports. This study explored the parallels between the Core Model and a national HTA report. Experiences from various European HTA agencies were also investigated to determine the Core Model's adaptability to national reports. A comparison between a national report on Genetic Counseling, produced by the Cellule d'expertise médicale Luxembourg, and the Core Model was performed to identify parallels in terms of relevant and comparable assessment elements (AEs). Semi-structured interviews with five representatives from European HTA agencies were performed to assess their user experiences with the Core Model. The comparative study revealed that 50 percent of the total number (n = 144) of AEs in the Core Model were relevant for the national report. Of these 144 AEs from the Core Model, 34 (24 percent) were covered in the national report. Some AEs were covered only partly. The interviewees emphasized flexibility in using the Core Model and stated that the most important aspects to be evaluated include characteristics of the disease and technology, clinical effectiveness, economic aspects, and safety. In the present study, the national report covered an acceptable number of AEs of the Core Model. These results need to be interpreted with caution because only one comparison was performed. The Core Model can be used in a flexible manner, applying only those elements that are relevant from the perspective of the technology assessment and specific country context.
Enterprise Architecture Modeling of Core Administrative Systems at KTH : A Modifiability Analysis
Rosell, Peter
2012-01-01
This project presents a case study of modifiability analysis on the Information Systems which are central to the core business processes of Royal Institution of Technology in Stockholm, Sweden by creating, updating and using models. The case study was limited to modifiability regarding only specified Information Systems. The method selected was Enterprise Architecture together with Enterprise Architecture Analysis research results and tools from the Industrial Information and Control Systems ...
Nuclear structure calculations in $^{20}$Ne with No-Core Configuration-Interaction model
Konieczka, Maciej; Satuła, Wojciech
2016-01-01
Negative parity states in $^{20}$Ne and Gamow-Teller strength distribution for the ground-state beta-decay of $^{20}$Na are calculated for the very first time using recently developed No-Core Configuration-Interaction model. The approach is based on multi-reference density functional theory involving isospin and angular-momentum projections. Advantages and shortcomings of the method are briefly discussed.
Simulation tests for temperature mixing in a core bottom model of the HTR-module
International Nuclear Information System (INIS)
Damm, G.; Wehrlein, R.
1992-01-01
Interatom and Siemens are developing a helium-cooled Modular High Temperature Reactor. Under nominal operating conditions temperature differences of up to 120deg C will occur in the 700deg C hot helium flow leaving the core. In addition, cold gas leakages into the hot gas header can produce even higher temperature differences in the coolant flow. At the outlet of the reactor only a very low temperature difference of maximum ± 15deg C is allowed in order to avoid damages at the heat exchanging components due to alternating thermal loads. Since it is not possible to calculate the complex flow behaviour, experimental investigations of the temperature mixing in the core bottom had to be carried out in order to guarantee the necessary reduction of temperature differences in the helium. The presented air simulation tests in a 1:2.9 scaled plexiglas model of the core bottom showed an extremely high mixing rate of the hot gas header and the hot gas duct of the reactor. The temperature mixing of the simulated coolant flow as well as the leakage flows was larger than 95%. Transfered to reactor conditions this means a temperature difference of only ± 3deg C for the main flow at a quite resonable pressure drop. For the cold gas leakages temperature differences in the hot gas up to 400deg C proved to be permissible. The results of the simulation experiments in the Aerodynamic Test Facility of Interatom permitted to design a shorter bottom reflector of the core. (orig.)
Chirality effect in disordered graphene ribbon junctions
International Nuclear Information System (INIS)
Long Wen
2012-01-01
We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon. (paper)
Josephson tunnel junctions in niobium films
International Nuclear Information System (INIS)
Wiik, Tapio.
1976-12-01
A method of fabricating stable Josephson tunnel junctions with reproducible characteristics is described. The junctions have a sandwich structure consisting of a vacuum evaporated niobium film, a niobium oxide layer produced by the glow discharge method and a lead film deposited by vacuum evaporation. Difficulties in producing thin-film Josephson junctions are discussed. Experimental results suggest that the lower critical field of the niobium film is the most essential parameter when evaluating the quality of these junctions. The dependence of the lower critical field on the film thickness and on the Ginzburg-Landau parameter of the film is studied analytically. Comparison with the properties of the evaporated films and with the previous calculations for bulk specimens shows that the presented model is applicable for most of the prepared samples. (author)
Tang, Jiang
2012-09-12
Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.
An analytical model for the study of a small LFR core dynamics: development and benchmark
International Nuclear Information System (INIS)
Bortot, S.; Cammi, A.; Lorenzi, S.; Moisseytsev, A.
2011-01-01
An analytical model for the study of a small Lead-cooled Fast Reactor (LFR) control-oriented dynamics has been developed aimed at providing a useful, very flexible and straightforward, though accurate, tool allowing relatively quick transient design-basis and stability analyses. A simplified lumped-parameter approach has been adopted to couple neutronics and thermal-hydraulics: the point-kinetics approximation has been employed and an average-temperature heat-exchange model has been implemented. The reactor transient responses following postulated accident initiators such as Unprotected Control Rod Withdrawal (UTOP), Loss of Heat Sink (ULOHS) and Loss of Flow (ULOF) have been studied for a MOX and a metal-fuelled core at the Beginning of Cycle (BoC) and End of Cycle (EoC) configurations. A benchmark analysis has been then performed by means of the SAS4A/SASSYS-1 Liquid Metal Reactor Code System, in which a core model based on three representative channels has been built with the purpose of providing verification for the analytical outcomes and indicating how the latter relate to more realistic one-dimensional calculations. As a general result, responses concerning the main core characteristics (namely, power, reactivity, etc.) have turned out to be mutually consistent in terms of both steady-state absolute figures and transient developments, showing discrepancies of the order of only some percents, thus confirming a very satisfactory agreement. (author)
International Nuclear Information System (INIS)
Lim, Chang Seon; Cho, A Ra; Hur, Yera; Choi, Seong Youl
2017-01-01
Radiological Technologists deals with the life of a person which means professional competency is essential for the job. Nevertheless, there have been no studies in Korea that identified the job competence of radiologists. In order to define the core job competencies of Korean radiologists and to present the factor models, 147 questionnaires on job competency of radiology were analyzed using 'PASW Statistics Version 18.0' and 'AMOS Version 18.0'. The valid model consisted of five core job competencies ('Patient management', 'Health and safety', 'Operation of equipment', 'Procedures and management') and 17 sub – competencies. As a result of the factor analysis, the RMSEA value was 0.1 and the CFI, and TLI values were close to 0.9 in the measurement model of the five core job competencies. The validity analysis showed that the mean variance extraction was 0.5 or more and the conceptual reliability value was 0.7 or more , And there was a high correlation between subordinate competencies included in each subordinate competencies. The results of this study are expected to provide specific information necessary for the training and management of human resources centered on competence by clearly showing the job competence required for radiologists in Korea's health environment
International Nuclear Information System (INIS)
Benner, J.
1984-03-01
A method for the numerical simulation of the Pressurized Water Reactor (PWR) core internal's behaviour during a blowdown accident is described, by which the motion of the reactor core and the interaction of the fuel elements with the core barrel and the coolant medium is calculated. Furthermore, some simple models for the support columns, lower and upper core support and the grid plate are provided. All these models have been implemented into the code Flux-4. For the solution of the very complex, coupled equations of motions for fluid and fuel rods an efficient numerical solution technique has been developed. With the new code-version Flux-5 the PWR-blowdown is parametically investigated. The calculated core barrel loadings are compared with Flux-4 results, simulating the core's inertia by a mass ring of HDR type. (orig.) [de
Failure Predictions for VHTR Core Components using a Probabilistic Contiuum Damage Mechanics Model
Energy Technology Data Exchange (ETDEWEB)
Fok, Alex
2013-10-30
The proposed work addresses the key research need for the development of constitutive models and overall failure models for graphite and high temperature structural materials, with the long-term goal being to maximize the design life of the Next Generation Nuclear Plant (NGNP). To this end, the capability of a Continuum Damage Mechanics (CDM) model, which has been used successfully for modeling fracture of virgin graphite, will be extended as a predictive and design tool for the core components of the very high- temperature reactor (VHTR). Specifically, irradiation and environmental effects pertinent to the VHTR will be incorporated into the model to allow fracture of graphite and ceramic components under in-reactor conditions to be modeled explicitly using the finite element method. The model uses a combined stress-based and fracture mechanics-based failure criterion, so it can simulate both the initiation and propagation of cracks. Modern imaging techniques, such as x-ray computed tomography and digital image correlation, will be used during material testing to help define the baseline material damage parameters. Monte Carlo analysis will be performed to address inherent variations in material properties, the aim being to reduce the arbitrariness and uncertainties associated with the current statistical approach. The results can potentially contribute to the current development of American Society of Mechanical Engineers (ASME) codes for the design and construction of VHTR core components.
Zegeye, Ephrem Debebe; Balasingham, Seetha V; Laerdahl, Jon K; Homberset, Håvard; Tønjum, Tone
2012-08-01
The RecG enzyme, a superfamily 2 helicase, is present in nearly all bacteria. Here we report for the first time that the recG gene is also present in the genomes of most vascular plants as well as in green algae, but is not found in other eukaryotes or archaea. The precise function of RecG is poorly understood, although ample evidence shows that it plays critical roles in DNA repair, recombination and replication. We further demonstrate that Mycobacterium tuberculosis RecG (RecG(Mtb)) DNA binding activity had a broad substrate specificity, whereas it only unwound branched-DNA substrates such as Holliday junctions (HJs), replication forks, D-loops and R-loops, with a strong preference for the HJ as a helicase substrate. In addition, RecG(Mtb) preferentially bound relatively long (≥40 nt) ssDNA, exhibiting a higher affinity for the homopolymeric nucleotides poly(dT), poly(dG) and poly(dC) than for poly(dA). RecG(Mtb) helicase activity was supported by hydrolysis of ATP or dATP in the presence of Mg(2+), Mn(2+), Cu(2+) or Fe(2+). Like its Escherichia coli orthologue, RecG(Mtb) is also a strictly DNA-dependent ATPase.
Pasculescu, Adrian; Schoof, Erwin M; Creixell, Pau; Zheng, Yong; Olhovsky, Marina; Tian, Ruijun; So, Jonathan; Vanderlaan, Rachel D; Pawson, Tony; Linding, Rune; Colwill, Karen
2014-04-04
A major challenge in mass spectrometry and other large-scale applications is how to handle, integrate, and model the data that is produced. Given the speed at which technology advances and the need to keep pace with biological experiments, we designed a computational platform, CoreFlow, which provides programmers with a framework to manage data in real-time. It allows users to upload data into a relational database (MySQL), and to create custom scripts in high-level languages such as R, Python, or Perl for processing, correcting and modeling this data. CoreFlow organizes these scripts into project-specific pipelines, tracks interdependencies between related tasks, and enables the generation of summary reports as well as publication-quality images. As a result, the gap between experimental and computational components of a typical large-scale biology project is reduced, decreasing the time between data generation, analysis and manuscript writing. CoreFlow is being released to the scientific community as an open-sourced software package complete with proteomics-specific examples, which include corrections for incomplete isotopic labeling of peptides (SILAC) or arginine-to-proline conversion, and modeling of multiple/selected reaction monitoring (MRM/SRM) results. CoreFlow was purposely designed as an environment for programmers to rapidly perform data analysis. These analyses are assembled into project-specific workflows that are readily shared with biologists to guide the next stages of experimentation. Its simple yet powerful interface provides a structure where scripts can be written and tested virtually simultaneously to shorten the life cycle of code development for a particular task. The scripts are exposed at every step so that a user can quickly see the relationships between the data, the assumptions that have been made, and the manipulations that have been performed. Since the scripts use commonly available programming languages, they can easily be
Chhabra, Sachin; Chopra, Sanjeev; Kataria, Rashim; Sinha, Virendra Deo
2017-12-01
Spinal instrumentation using rods and screws have become procedure of choice for posterior fixation. Vertebral artery anatomy is highly variable in this region posing challenges during surgery. Our study used 3D printer model to understand the anatomy and variations in vertebral artery in live patients thereby providing an accurate idea about vertebral artery injury risk in these patients preoperatively and to rehearse the whole procedure. Ten patients of developmental craniovertebral junction (CVJ) anomalies who were planned for operative intervention in the Department of Neurosurgery at SMS Hospital from February 2016 to December 2016 were analysed using a 3D printer model. Out of twenty vertebral arteries studied in ten patients, two were hypoplastic and out of these one could not be appreciated on 3D printer model. Out of remaining nineteen, thirteen arteries were found to lie outside the joint, three were in lateral third, one traversed the middle third of joint and one lied in medial third. In one patient, the vertebral artery was stretched and it traversed horizontally over the joint. Out of ten patients studied, nine were having occipitalised atlas and so entry of these vertebral arteries into cranium were classified as given by Wang et al. into four types. By our study, 3D printer model was extremely helpful in analyzing joints and vertebral artery preoperatively and making the surgeon acquainted about the placement and trajectory of the screws accordingly. In our opinion, these models should be included as a basic investigation tool in these patients.
Linear and nonlinear modeling of light propagation in hollow-core photonic crystal fiber
DEFF Research Database (Denmark)
Roberts, John; Lægsgaard, Jesper
2009-01-01
Hollow core photonic crystal fibers (HC-PCFs) find applications which include quantum and non-linear optics, gas detection and short high-intensity laser pulse delivery. Central to most applications is an understanding of the linear and nonlinear optical properties. These require careful modeling....... The intricacies of modeling various forms of HC-PCF are reviewed. An example of linear dispersion engineering, aimed at reducing and flattening the group velocity dispersion, is then presented. Finally, a study of short high intensity pulse delivery using HC-PCF in both dispersive and nonlinear (solitonic...
Low-temperature behavior of core-softened models: Water and silica behavior
International Nuclear Information System (INIS)
Jagla, E. A.
2001-01-01
A core-softened model of a glass forming fluid is numerically studied in the limit of very low temperatures. The model shows two qualitatively different behaviors depending on the strength of the attraction between particles. For no or low attraction, the changes of density as a function of pressure are smooth, although hysteretic due to mechanical metastabilities. For larger attraction, sudden changes of density upon compressing and decompressing occur. This global mechanical instability is correlated to the existence of a thermodynamic first-order amorphous-amorphous transition. The two different behaviors obtained correspond qualitatively to the different phenomenology observed in silica and water
GCFR 1/20-scale PCRV central core cavity closure model test
International Nuclear Information System (INIS)
Robinson, G.C.; Dougan, J.R.
1981-06-01
Oak Ridge National Laboratory has been conducting structural response tests of the prestressed concrete reactor vessel (PCRV) closures for the 300-MW(e) gas-cooled fast reactor demonstration power plant. This report describes the third in a series of tests of small-scale closure plug models. The model represents a redesign of the central core cavity closure plug. The primary objective was to demonstrate structural performance and ultimate load capacity of the closure plug. Secondary objectives included obtaining data on crack development and propagation and on mode of failure of the composite structure
Experimental modelling of core debris dispersion from the vault under a PWR pressure vessel: Part 1
International Nuclear Information System (INIS)
Macbeth, R.V.; Trenberth, R.
1987-12-01
Modelling experiments have been done on a 1/25 scale model in Perspex of the vault under a PWR pressure vessel. Various liquids have been used to simulate molten core debris assumed to have fallen on to the vault floor from a breach at the bottom of the pressure vessel. High pressure air and helium have been used to simulate the discharge of steam and gas from the breach. The dispersion of liquid via the vault access shafts has been measured. Photographs have been taken of fluid flow patterns and velocity profiles have been obtained. The requirements for further experiments are indicated. (author)
Mohamed, Khaled Salah
2016-01-01
This book describes the life cycle process of IP cores, from specification to production, including IP modeling, verification, optimization, and protection. Various trade-offs in the design process are discussed, including those associated with many of the most common memory cores, controller IPs and system-on-chip (SoC) buses. Readers will also benefit from the author’s practical coverage of new verification methodologies. such as bug localization, UVM, and scan-chain. A SoC case study is presented to compare traditional verification with the new verification methodologies. · Discusses the entire life cycle process of IP cores, from specification to production, including IP modeling, verification, optimization, and protection; · Introduce a deep introduction for Verilog for both implementation and verification point of view. · Demonstrates how to use IP in applications such as memory controllers and SoC buses. · Describes a new ver...
Advanced Test Reactor Core Modeling Update Project Annual Report for Fiscal Year 2010
Energy Technology Data Exchange (ETDEWEB)
Rahmat Aryaeinejad; Douglas S. Crawford; Mark D. DeHart; George W. Griffith; D. Scott Lucas; Joseph W. Nielsen; David W. Nigg; James R. Parry; Jorge Navarro
2010-09-01
Legacy computational reactor physics software tools and protocols currently used for support of Advanced Test Reactor (ATR) core fuel management and safety assurance and, to some extent, experiment management are obsolete, inconsistent with the state of modern nuclear engineering practice, and are becoming increasingly difficult to properly verify and validate (V&V). Furthermore, the legacy staff knowledge required for application of these tools and protocols from the 1960s and 1970s is rapidly being lost due to staff turnover and retirements. In 2009 the Idaho National Laboratory (INL) initiated a focused effort to address this situation through the introduction of modern high-fidelity computational software and protocols, with appropriate V&V, within the next 3-4 years via the ATR Core Modeling and Simulation and V&V Update (or “Core Modeling Update”) Project. This aggressive computational and experimental campaign will have a broad strategic impact on the operation of the ATR, both in terms of improved computational efficiency and accuracy for support of ongoing DOE programs as well as in terms of national and international recognition of the ATR National Scientific User Facility (NSUF).
Efficient n-gram, Skipgram and Flexgram Modelling with Colibri Core
Directory of Open Access Journals (Sweden)
Maarten van Gompel
2016-08-01
Full Text Available Counting n-grams lies at the core of any frequentist corpus analysis and is often considered a trivial matter. Going beyond consecutive n-grams to patterns such as skipgrams and flexgrams increases the demand for efficient solutions. The need to operate on big corpus data does so even more. Lossless compression and non-trivial algorithms are needed to lower the memory demands, yet retain good speed. Colibri Core is software for the efficient computation and querying of n-grams, skipgrams and flexgrams from corpus data. The resulting pattern models can be analysed and compared in various ways. The software offers a programming library for C++ and Python, as well as command-line tools.
Analytical Model of Thermo-electrical Behaviour in Superconducting Resistive Core Cables
Calvi, M; Breschi, M; Coccoli, M; Granieri, P; Iriart, G; Lecci, F; Siemko, A
2006-01-01
High field superconducting Nb$_{3}$Sn accelerators magnets above 14 T, for future High Energy Physics applications, call for improvements in the design of the protection system against resistive transitions. The longitudinal quench propagation velocity (vq) is one of the parameters defining the requirements of the protection. Up to now vq has been always considered as a physical parameter defined by the operating conditions (the bath temperature, cooling conditions, the magnetic field and the over all current density) and the type of superconductor and stabilizer used. It is possible to enhance the quench propagation velocity by segregating a percent of the stabilizer into the core, although keeping the total amount constant and tuning the contact resistance between the superconducting strands and the core. Analytical model and computer simulations are presented to explain the phenomenon. The consequences with respect to minimum quench energy are evidenced and the strategy to optimize the cable designed is di...
Influence of core model parameters on the characteristics of neutron beams of the research reactor
Directory of Open Access Journals (Sweden)
N. A. Khafizova
2013-12-01
Full Text Available IRT MEPhI reactor is equipped with a number of facilities at horizontal experimental channels (HEC. Knowing of parameters influencing spatio-angular distribution of irradiation fields is essential for each application area. The research for neutron capture therapy (NCT facility at HEC of the reactor was made. Calculation methods have been used to estimate how the reactor core parameters influence neutron beam characteristics at the HEC output. The impact of neutron source model in Monte Carlo calculations by MCNP code on the parameters of neutron and secondary photon field at the output of irradiation beam tubes of research reactor is estimated. The study shows that specifying neutron source with fission reaction rate distribution in SDEF option gives almost the same results as criticality calculation considered the most accurate. Our calculations show that changes of the core operational parameters have insignificant influence on characteristics of neutron beams at HEC output.
Interface between Core/TH Model and Simulator for OPR1000
Energy Technology Data Exchange (ETDEWEB)
Hwang, Do Hyun; Lee, Myeong Soo; Hong, Jin Hyuk; Lee, Seung Ho; Suh, Jung Kwan [KEPRI, Daejeon (Korea, Republic of)
2009-05-15
OPR1000 simulator for ShinKori-Unit 1, which will be operated at 2815MWt of thermal core power, is being developed while the ShinKori-Unit 1 and 2 is being built. OPR1000 simulator adopted the RELAP5 R/T code, which is the adaptation of RELAP5 and NESTLE codes to run in real-time mode with graphical visualization, to model Nuclear Steam Supply System (NSSS) Thermal-Hydraulics (TH) and Reactor Core. The RELAP5 is an advanced, best estimate, reactor TH simulation code developed at Idaho National Engineering and Environment Laboratory(INEEL) and the NESTLE is a true two-energy group neutronics code that computes the neutron flux and power for each node at every time step. As a simulator environment, the 3KEYMASTER{sup TM}, a commercial environment tool of WSC is used.
Interface between Core/TH Model and Simulator for OPR1000
International Nuclear Information System (INIS)
Hwang, Do Hyun; Lee, Myeong Soo; Hong, Jin Hyuk; Lee, Seung Ho; Suh, Jung Kwan
2009-01-01
OPR1000 simulator for ShinKori-Unit 1, which will be operated at 2815MWt of thermal core power, is being developed while the ShinKori-Unit 1 and 2 is being built. OPR1000 simulator adopted the RELAP5 R/T code, which is the adaptation of RELAP5 and NESTLE codes to run in real-time mode with graphical visualization, to model Nuclear Steam Supply System (NSSS) Thermal-Hydraulics (TH) and Reactor Core. The RELAP5 is an advanced, best estimate, reactor TH simulation code developed at Idaho National Engineering and Environment Laboratory(INEEL) and the NESTLE is a true two-energy group neutronics code that computes the neutron flux and power for each node at every time step. As a simulator environment, the 3KEYMASTER TM , a commercial environment tool of WSC is used
CQPSO scheduling algorithm for heterogeneous multi-core DAG task model
Zhai, Wenzheng; Hu, Yue-Li; Ran, Feng
2017-07-01
Efficient task scheduling is critical to achieve high performance in a heterogeneous multi-core computing environment. The paper focuses on the heterogeneous multi-core directed acyclic graph (DAG) task model and proposes a novel task scheduling method based on an improved chaotic quantum-behaved particle swarm optimization (CQPSO) algorithm. A task priority scheduling list was built. A processor with minimum cumulative earliest finish time (EFT) was acted as the object of the first task assignment. The task precedence relationships were satisfied and the total execution time of all tasks was minimized. The experimental results show that the proposed algorithm has the advantage of optimization abilities, simple and feasible, fast convergence, and can be applied to the task scheduling optimization for other heterogeneous and distributed environment.
Initial Comparison of Direct and Legacy Modeling Approaches for Radial Core Expansion Analysis
International Nuclear Information System (INIS)
Shemon, Emily R.
2016-01-01
Radial core expansion in sodium-cooled fast reactors provides an important reactivity feedback effect. As the reactor power increases due to normal start up conditions or accident scenarios, the core and surrounding materials heat up, causing both grid plate expansion and bowing of the assembly ducts. When the core restraint system is designed correctly, the resulting structural deformations introduce negative reactivity which decreases the reactor power. Historically, an indirect procedure has been used to estimate the reactivity feedback due to structural deformation which relies upon perturbation theory and coupling legacy physics codes with limited geometry capabilities. With advancements in modeling and simulation, radial core expansion phenomena can now be modeled directly, providing an assessment of the accuracy of the reactivity feedback coefficients generated by indirect legacy methods. Recently a new capability was added to the PROTEUS-SN unstructured geometry neutron transport solver to analyze deformed meshes quickly and directly. By supplying the deformed mesh in addition to the base configuration input files, PROTEUS-SN automatically processes material adjustments including calculation of region densities to conserve mass, calculation of isotopic densities according to material models (for example, sodium density as a function of temperature), and subsequent re-homogenization of materials. To verify the new capability of directly simulating deformed meshes, PROTEUS-SN was used to compute reactivity feedback for a series of contrived yet representative deformed configurations for the Advanced Burner Test Reactor design. The indirect legacy procedure was also performed to generate reactivity feedback coefficients for the same deformed configurations. Interestingly, the legacy procedure consistently overestimated reactivity feedbacks by 35% compared to direct simulations by PROTEUS-SN. This overestimation indicates that the legacy procedures are in fact
Initial Comparison of Direct and Legacy Modeling Approaches for Radial Core Expansion Analysis
Energy Technology Data Exchange (ETDEWEB)
Shemon, Emily R. [Argonne National Lab. (ANL), Argonne, IL (United States)
2016-10-10
Radial core expansion in sodium-cooled fast reactors provides an important reactivity feedback effect. As the reactor power increases due to normal start up conditions or accident scenarios, the core and surrounding materials heat up, causing both grid plate expansion and bowing of the assembly ducts. When the core restraint system is designed correctly, the resulting structural deformations introduce negative reactivity which decreases the reactor power. Historically, an indirect procedure has been used to estimate the reactivity feedback due to structural deformation which relies upon perturbation theory and coupling legacy physics codes with limited geometry capabilities. With advancements in modeling and simulation, radial core expansion phenomena can now be modeled directly, providing an assessment of the accuracy of the reactivity feedback coefficients generated by indirect legacy methods. Recently a new capability was added to the PROTEUS-SN unstructured geometry neutron transport solver to analyze deformed meshes quickly and directly. By supplying the deformed mesh in addition to the base configuration input files, PROTEUS-SN automatically processes material adjustments including calculation of region densities to conserve mass, calculation of isotopic densities according to material models (for example, sodium density as a function of temperature), and subsequent re-homogenization of materials. To verify the new capability of directly simulating deformed meshes, PROTEUS-SN was used to compute reactivity feedback for a series of contrived yet representative deformed configurations for the Advanced Burner Test Reactor design. The indirect legacy procedure was also performed to generate reactivity feedback coefficients for the same deformed configurations. Interestingly, the legacy procedure consistently overestimated reactivity feedbacks by 35% compared to direct simulations by PROTEUS-SN. This overestimation indicates that the legacy procedures are in fact
Molecular Diffusion through Cyanobacterial Septal Junctions.
Nieves-Morión, Mercedes; Mullineaux, Conrad W; Flores, Enrique
2017-01-03
Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N 2 -fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO 2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP) assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the "septal junctions" (formerly known as "microplasmodesmata") linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans. Although bacteria are frequently considered just as unicellular organisms, there are bacteria that behave as true multicellular organisms. The heterocyst-forming cyanobacteria grow as filaments in which cells communicate. Intercellular molecular exchange is thought to be mediated by septal junctions. Here, we show that intercellular transfer of fluorescent markers in the cyanobacterial filament has the physical properties of simple diffusion. Thus, cyanobacterial septal junctions are functionally analogous to metazoan gap junctions
Development of Sodium Two Phase Flow Model for Kalimer Core Analysis
International Nuclear Information System (INIS)
Chang, W.P.; Hahn, Dohee
2002-01-01
An algorithm for sodium boiling is developed in order to extend the applicability of SSC-K, which is a main system analysis code for the KALIMER (Korea Advanced LIquid Metal Reactor) conceptual design. As the capability of the current SSC-K version is limited to simulation of only a single-phase sodium flow, its applicable range should not be enough to assess the fuel integrity under some of HCDA (Hypothetical Core Disruptive Accident) initiating events where sodium boiling is anticipated. The two-phase flow model similar to that used for the light water system is known to be no more effective directly to liquid metal reactors, because the phenomena observed between two reactor coolant systems are definitely different. The developing algorithm is based on a multiple-bubble slug ejection model, which allows a finite number of bubbles in a channel at any time. The present work is a continuous effort following the former study to confirm a qualitative acceptance on the model. Since the model has been applied only to the active fuel region in the former study, a part of its qualification seems to have already been demonstrated. For its application to the whole KALIMER core channel, however, the model needs to be examined the applicability to the fuel regions other than the active fuel. The present study primarily focuses on that point. In a result, although the model may be improved in a sense through the present study over the previous modeling, a clear limitation is also confirmed with the validity of the model. The further development, therefore, is required for this model to achieve its goal by resolving such limitations. (authors)
Magnetic interaction between spatially extended superconducting tunnel junctions
DEFF Research Database (Denmark)
Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm
2002-01-01
A general description of magnetic interactions between superconducting tunnel junctions is given. The description covers a wide range of possible experimental systems, and we explicitly explore two experimentally relevant limits of coupled junctions. One is the limit of junctions with tunneling...... been considered through arrays of superconducting weak links based on semiconductor quantum wells with superconducting electrodes. We use the model to make direct interpretations of the published experiments and thereby propose that long-range magnetic interactions are responsible for the reported...
MODELING THE FORMATION OF GIANT PLANET CORES. I. EVALUATING KEY PROCESSES
International Nuclear Information System (INIS)
Levison, Harold F.; Thommes, Edward; Duncan, Martin J.
2010-01-01
One of the most challenging problems we face in our understanding of planet formation is how Jupiter and Saturn could have formed before the solar nebula dispersed. The most popular model of giant planet formation is the so-called core accretion model. In this model a large planetary embryo formed first, mainly by two-body accretion. This is then followed by a period of inflow of nebular gas directly onto the growing planet. The core accretion model has an Achilles heel, namely the very first step. We have undertaken the most comprehensive study of this process to date. In this study, we numerically integrate the orbits of a number of planetary embryos embedded in a swarm of planetesimals. In these experiments, we have included a large number of physical processes that might enhance accretion. In particular, we have included (1) aerodynamic gas drag, (2) collisional damping between planetesimals, (3) enhanced embryo cross sections due to their atmospheres, (4) planetesimal fragmentation, and (5) planetesimal-driven migration. We find that the gravitational interaction between the embryos and the planetesimals leads to the wholesale redistribution of material-regions are cleared of material and gaps open near the embryos. Indeed, in 90% of our simulations without fragmentation, the region near those embryos is cleared of planetesimals before much growth can occur. Thus, the widely used assumption that the surface density distribution of planetesimals is smooth can lead to misleading results. In the remaining 10% of our simulations, the embryos undergo a burst of outward migration that significantly increases growth. On timescales of ∼10 5 years, the outer embryo can migrate ∼6 AU and grow to roughly 30 M + . This represents a largely unexplored mode of core formation. We also find that the inclusion of planetesimal fragmentation tends to inhibit growth except for a narrow range of fragment migration rates.
An Exact Solution to the Central Core Model of the Renal Medulla
Mickens, Ronald E.
1998-11-01
The central core model of the renal medulla provides a mathematical representation of the urine concentration mechanism. The model consists of eight coupled, nonlinear ODE's subject to certain initial and boundary conditions. Many investigators have studied the properties of the solutions to these equations, however no general analytic solution is known to exist. Thus, special exact solutions assume a position of significance by providing a basis for insight into the understanding of more realistic models used to analyze actual data. We calculate an exact solution for the case in which the water permeabilities are zero and a particular, but realistic, functional form is used for the metabolic pump. A detailed discussion will be given for the results obtained on the four cencentration and four flux functions that define the model. If invited to do so, the author is willing to expand the talk for the above abstract to twenty minutes.
Benton, E. R.
1986-01-01
A spherical harmonic representation of the geomagnetic field and its secular variation for epoch 1980, designated GSFC(9/84), is derived and evaluated. At three epochs (1977.5, 1980.0, 1982.5) this model incorporates conservation of magnetic flux through five selected patches of area on the core/mantle boundary bounded by the zero contours of vertical magnetic field. These fifteen nonlinear constraints are included like data in an iterative least squares parameter estimation procedure that starts with the recently derived unconstrained field model GSFC (12/83). Convergence is approached within three iterations. The constrained model is evaluated by comparing its predictive capability outside the time span of its data, in terms of residuals at magnetic observatories, with that for the unconstrained model.
Modeling of BWR core meltdown accidents - for application in the MELRPI. MOD2 computer code
Energy Technology Data Exchange (ETDEWEB)
Koh, B R; Kim, S H; Taleyarkhan, R P; Podowski, M Z; Lahey, Jr, R T
1985-04-01
This report summarizes improvements and modifications made in the MELRPI computer code. A major difference between this new, updated version of the code, called MELRPI.MOD2, and the one reported previously, concerns the inclusion of a model for the BWR emergency core cooling systems (ECCS). This model and its computer implementation, the ECCRPI subroutine, account for various emergency injection modes, for both intact and rubblized geometries. Other changes to MELRPI deal with an improved model for canister wall oxidation, rubble bed modeling, and numerical integration of system equations. A complete documentation of the entire MELRPI.MOD2 code is also given, including an input guide, list of subroutines, sample input/output and program listing.
Advanced Test Reactor Core Modeling Update Project Annual Report for Fiscal Year 2011
Energy Technology Data Exchange (ETDEWEB)
David W. Nigg; Devin A. Steuhm
2011-09-01
Legacy computational reactor physics software tools and protocols currently used for support of Advanced Test Reactor (ATR) core fuel management and safety assurance and, to some extent, experiment management are obsolete, inconsistent with the state of modern nuclear engineering practice, and are becoming increasingly difficult to properly verify and validate (V&V). Furthermore, the legacy staff knowledge required for application of these tools and protocols from the 1960s and 1970s is rapidly being lost due to staff turnover and retirements. In 2009 the Idaho National Laboratory (INL) initiated a focused effort to address this situation through the introduction of modern high-fidelity computational software and protocols, with appropriate V&V, within the next 3-4 years via the ATR Core Modeling and Simulation and V&V Update (or 'Core Modeling Update') Project. This aggressive computational and experimental campaign will have a broad strategic impact on the operation of the ATR, both in terms of improved computational efficiency and accuracy for support of ongoing DOE programs as well as in terms of national and international recognition of the ATR National Scientific User Facility (NSUF). The ATR Core Modeling Update Project, targeted for full implementation in phase with the anticipated ATR Core Internals Changeout (CIC) in the 2014 time frame, began during the last quarter of Fiscal Year 2009, and has just completed its first full year. Key accomplishments so far have encompassed both computational as well as experimental work. A new suite of stochastic and deterministic transport theory based reactor physics codes and their supporting nuclear data libraries (SCALE, KENO-6, HELIOS, NEWT, and ATTILA) have been installed at the INL under various permanent sitewide license agreements and corresponding baseline models of the ATR and ATRC are now operational, demonstrating the basic feasibility of these code packages for their intended purpose. Furthermore
Advanced Test Reactor Core Modeling Update Project Annual Report for Fiscal Year 2011
International Nuclear Information System (INIS)
Nigg, David W.; Steuhm, Devin A.
2011-01-01
Legacy computational reactor physics software tools and protocols currently used for support of Advanced Test Reactor (ATR) core fuel management and safety assurance and, to some extent, experiment management are obsolete, inconsistent with the state of modern nuclear engineering practice, and are becoming increasingly difficult to properly verify and validate (V and V). Furthermore, the legacy staff knowledge required for application of these tools and protocols from the 1960s and 1970s is rapidly being lost due to staff turnover and retirements. In 2009 the Idaho National Laboratory (INL) initiated a focused effort to address this situation through the introduction of modern high-fidelity computational software and protocols, with appropriate V and V, within the next 3-4 years via the ATR Core Modeling and Simulation and V and V Update (or 'Core Modeling Update') Project. This aggressive computational and experimental campaign will have a broad strategic impact on the operation of the ATR, both in terms of improved computational efficiency and accuracy for support of ongoing DOE programs as well as in terms of national and international recognition of the ATR National Scientific User Facility (NSUF). The ATR Core Modeling Update Project, targeted for full implementation in phase with the anticipated ATR Core Internals Changeout (CIC) in the 2014 time frame, began during the last quarter of Fiscal Year 2009, and has just completed its first full year. Key accomplishments so far have encompassed both computational as well as experimental work. A new suite of stochastic and deterministic transport theory based reactor physics codes and their supporting nuclear data libraries (SCALE, KENO-6, HELIOS, NEWT, and ATTILA) have been installed at the INL under various permanent sitewide license agreements and corresponding baseline models of the ATR and ATRC are now operational, demonstrating the basic feasibility of these code packages for their intended purpose
International Nuclear Information System (INIS)
Powers, D.A.; Sprung, J.L.
1993-11-01
A classic model of aerosol scrubbing from bubbles rising through water is applied to the decontamination of gases produced during core debris interactions with concrete. The model, originally developed by Fuchs, describes aerosol capture by diffusion, sedimentation, and inertial impaction. This original model for spherical bubbles is modified to account for ellipsoidal distortion of the bubbles. Eighteen uncertain variables are identified in the application of the model to the decontamination of aerosols produced during core debris interactions with concrete by a water pool of specified depth and subcooling. These uncertain variables include properties of the aerosols, the bubbles, the water and the ambient pressure. Results are analyzed using a nonparametric, order statistical analysis that allows quantitative differentiation of stochastic and phenomenological uncertainty. The sampled values of the decontamination factors are used to construct estimated probability density functions for the decontamination factor at confidence levels of 50%, 90% and 95%. The decontamination factors for pools 30, 50, 100, 200, 300, and 500 cm deep and subcooling levels of 0, 2, 5, 10, 20, 30, 50, and 70 degrees C are correlated by simple polynomial regression. These polynomial equations can be used to estimate decontamination factors at prescribed confidence levels
Four-junction superconducting circuit
Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.
2016-01-01
We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit. PMID:27356619
Development of a simplified calculational model for the transient core bowing effect
International Nuclear Information System (INIS)
Yokoo, Takeshi
1997-01-01
A simplified method to analyze the transient core radial deformation has been developed based on a model that calculates the shape of a single representative fuel assembly on the outermost row. The plant transient code CERES has been revised utilizing this method so that a integrated calculational process for the core neutronics, thermal-hydraulics and deformation can be realized. Using CERES, the responses of a 1000MWe class pool type metal fuel FBR plant during a ULOF event are calculated. According to the results, it is clarified that a passive shutdown without coolant boiling is attainable by selecting appropriate values for major design parameters such as the gap width between load-pad and the pad material properties. The maximum coolant temperature during ULOF is found to be 790C when the above core load-pad gap is set to 0.05 mm, which can be regarded as the most likely valued. The temperature increases to 915C but is still lower than the boiling point when 40% of uncertainty is taken into account. (author)
Two-dimensional vertical model seismic test and analysis for HTGR core
International Nuclear Information System (INIS)
Ikushima, Takeshi; Honma, Toshiaki.
1983-02-01
The resistance against earthquakes of high-temperature gas cooled reactor (HTGR) core with block-type fuels is not fully ascertained yet. Seismic studies must be made if such a reactor plant is to be installed in areas with frequent earthquakes. In the paper the test results of seismic behavior of a half-scale two-dimensional vertical slice core model and analysis are presented. The following results were obtained: (1) With soft spring support of the fixed side reflector structure, the relative column displacement is larger than that for hand support but the impact reaction force is smaller. (2) In the case of hard spring support the dowel force is smaller than for soft support. (3) The relative column displacement is larger in the core center than at the periphery. The impact acceleration (force) in the center is smaller than at the periphery. (4) The relative column displacement and impact reaction force are smaller with the gas pressure simulation spring than without. (5) With decreasing gap width between the top blocks of columns, the relative column displacement and impact reaction force decrease. (6) The column damping ratio was estimated as 4 -- 10% of critical. (7) The maximum impact reaction force for random waves such as seismic was below 60% that for a sinusoidal wave. (8) Vibration behavior and impact response are in good agreement between test and analysis. (author)
Development of a New core/reflector model for coarse-mesh nodal methods
International Nuclear Information System (INIS)
Pogosbekyan, Leonid; Cho, Jin Young; Kim, Young Il; Kim, Young Jin; Joo, Hyung Kuk; Chang, Moon Hee.
1997-10-01
This work presents two approaches for reflector simulation in coarse-mesh nodal methods. The first approach is called Interface Matrix Technique (IMT), which simulates the baffle as a banishingly thin layer having the property of reflection and transmission. We applied this technique within the frame of AFEN (Analytic Function Expansion Nodal) method, and developed the AFEN-IM (Interface Matrix) method. AFEN-IM method shows 1.24% and 0.42 % in maximum and RMS (Root Mean Square) assemblywise power error for ZION-1 benchmark problem. The second approach is L-shaped reflector homogenization method. This method is based on the integral response conservation along the L-shaped core-reflector interface. The reference reflector response is calculated from 2-dimensional spectral calculation and the response of the homogenized reflector is derived from the one-node 2-dimensional AFEN problem solution. This method shows 5 times better accuracy than the 1-dimensional homogenization technique in the assemblywise power. Also, the concept of shroud/reflector homogenization for hexagonal core have been developed. The 1-dimensional spectral calculation was used for the determination of 2 group cross sections. The essence of homogenization concept consists in the calculation of equivalent shroud width, which preserve albedo for the fast neutrons in 2-dimensional reflector. This method shows a relative error less than 0.42% in assemblywise power and a difference of 9x10 -5 in multiplication factor for full-core model. (author). 9 refs., 3 tabs., 28 figs
The quark model and the nature of the repulsive core of the nucleon-nucleon interaction
International Nuclear Information System (INIS)
Faessler, A.; Fernandez, F.; Luebeck, G.; Shimizu, K.
1982-01-01
The nature of the repulsive core of the nucleon-nucleon is studied in the quark model. The resonating group equation for nucleon-nucleon scattering is solved with the colour Fermi-Breit interaction including further a linear or quadratic confinement potential. It is shown that the colour magnetic interaction which is adjusted to the Δ-nucleon mass splitting favours the orbital symmetry and disfavours the completely symmetric orbital state. For the important orbital symmetry the relative S wave function between the two nucleons has to have a node. In the framework of the resonating group including the NN, ΔΔ and the hidden colour (CC) channels it is shown that this node produces a 3 S and 1 S phase shift which is identical to a hard core phase shift with a hard core radius γ 0 between 0.3 and 0.6 fm depending on the assumed root mean square radius of the quark part of the nucleon. (orig./HSI)
International Nuclear Information System (INIS)
Reed, K. A.
2015-01-01
Our paper examines the impact of the dynamical core on the simulation of tropical cyclone (TC) frequency, distribution, and intensity. The dynamical core, the central fluid flow component of any general circulation model (GCM), is often overlooked in the analysis of a model's ability to simulate TCs compared to the impact of more commonly documented components (e.g., physical parameterizations). The Community Atmosphere Model version 5 is configured with multiple dynamics packages. This analysis demonstrates that the dynamical core has a significant impact on storm intensity and frequency, even in the presence of similar large-scale environments. In particular, the spectral element core produces stronger TCs and more hurricanes than the finite-volume core using very similar parameterization packages despite the latter having a slightly more favorable TC environment. Furthermore, these results suggest that more detailed investigations into the impact of the GCM dynamical core on TC climatology are needed to fully understand these uncertainties. Key Points The impact of the GCM dynamical core is often overlooked in TC assessments The CAM5 dynamical core has a significant impact on TC frequency and intensity A larger effort is needed to better understand this uncertainty
An approach to model reactor core nodalization for deterministic safety analysis
Salim, Mohd Faiz; Samsudin, Mohd Rafie; Mamat @ Ibrahim, Mohd Rizal; Roslan, Ridha; Sadri, Abd Aziz; Farid, Mohd Fairus Abd
2016-01-01
Adopting good nodalization strategy is essential to produce an accurate and high quality input model for Deterministic Safety Analysis (DSA) using System Thermal-Hydraulic (SYS-TH) computer code. The purpose of such analysis is to demonstrate the compliance against regulatory requirements and to verify the behavior of the reactor during normal and accident conditions as it was originally designed. Numerous studies in the past have been devoted to the development of the nodalization strategy for small research reactor (e.g. 250kW) up to the bigger research reactor (e.g. 30MW). As such, this paper aims to discuss the state-of-arts thermal hydraulics channel to be employed in the nodalization for RTP-TRIGA Research Reactor specifically for the reactor core. At present, the required thermal-hydraulic parameters for reactor core, such as core geometrical data (length, coolant flow area, hydraulic diameters, and axial power profile) and material properties (including the UZrH1.6, stainless steel clad, graphite reflector) have been collected, analyzed and consolidated in the Reference Database of RTP using standardized methodology, mainly derived from the available technical documentations. Based on the available information in the database, assumptions made on the nodalization approach and calculations performed will be discussed and presented. The development and identification of the thermal hydraulics channel for the reactor core will be implemented during the SYS-TH calculation using RELAP5-3D® computer code. This activity presented in this paper is part of the development of overall nodalization description for RTP-TRIGA Research Reactor under the IAEA Norwegian Extra-Budgetary Programme (NOKEBP) mentoring project on Expertise Development through the Analysis of Reactor Thermal-Hydraulics for Malaysia, denoted as EARTH-M.
An approach to model reactor core nodalization for deterministic safety analysis
Energy Technology Data Exchange (ETDEWEB)
Salim, Mohd Faiz, E-mail: mohdfaizs@tnb.com.my; Samsudin, Mohd Rafie, E-mail: rafies@tnb.com.my [Nuclear Energy Department, Regulatory Economics & Planning Division, Tenaga Nasional Berhad (Malaysia); Mamat Ibrahim, Mohd Rizal, E-mail: m-rizal@nuclearmalaysia.gov.my [Prototypes & Plant Development Center, Malaysian Nuclear Agency (Malaysia); Roslan, Ridha, E-mail: ridha@aelb.gov.my; Sadri, Abd Aziz [Nuclear Installation Divisions, Atomic Energy Licensing Board (Malaysia); Farid, Mohd Fairus Abd [Reactor Technology Center, Malaysian Nuclear Agency (Malaysia)
2016-01-22
Adopting good nodalization strategy is essential to produce an accurate and high quality input model for Deterministic Safety Analysis (DSA) using System Thermal-Hydraulic (SYS-TH) computer code. The purpose of such analysis is to demonstrate the compliance against regulatory requirements and to verify the behavior of the reactor during normal and accident conditions as it was originally designed. Numerous studies in the past have been devoted to the development of the nodalization strategy for small research reactor (e.g. 250kW) up to the bigger research reactor (e.g. 30MW). As such, this paper aims to discuss the state-of-arts thermal hydraulics channel to be employed in the nodalization for RTP-TRIGA Research Reactor specifically for the reactor core. At present, the required thermal-hydraulic parameters for reactor core, such as core geometrical data (length, coolant flow area, hydraulic diameters, and axial power profile) and material properties (including the UZrH{sub 1.6}, stainless steel clad, graphite reflector) have been collected, analyzed and consolidated in the Reference Database of RTP using standardized methodology, mainly derived from the available technical documentations. Based on the available information in the database, assumptions made on the nodalization approach and calculations performed will be discussed and presented. The development and identification of the thermal hydraulics channel for the reactor core will be implemented during the SYS-TH calculation using RELAP5-3D{sup ®} computer code. This activity presented in this paper is part of the development of overall nodalization description for RTP-TRIGA Research Reactor under the IAEA Norwegian Extra-Budgetary Programme (NOKEBP) mentoring project on Expertise Development through the Analysis of Reactor Thermal-Hydraulics for Malaysia, denoted as EARTH-M.
Umar, Sulaiman; Man, Norsida; Nawi, Nolila Mohd; Latif, Ismail Abd; Samah, Bahaman Abu
2017-06-01
The study described the perceived importance of, and proficiency in core agricultural extension competencies among extension workers in Peninsular Malaysia; and evaluating the resultant deficits in the competencies. The Borich's Needs Assessment Model was used to achieve the objectives of the study. A sample of 298 respondents was randomly selected and interviewed using a pre-tested structured questionnaire. Thirty-three core competency items were assessed. Instrument validity and reliability were ensured. The cross-sectional data obtained was analysed using SPSS for descriptive statistics including mean weighted discrepancy score (MWDS). Results of the study showed that on a scale of 5, the most important core extension competency items according to respondents' perception were: "Making good use of information and communication technologies/access and use of web-based resources" (M=4.86, SD=0.23); "Conducting needs assessments" (M=4.84, SD=0.16); "organizing extension campaigns" (M=4.82, SD=0.47) and "Managing groups and teamwork" (M=4.81, SD=0.76). In terms of proficiency, the highest competency identified by the respondents was "Conducting farm and home visits (M=3.62, SD=0.82) followed by 'conducting meetings effectively' (M=3.19, SD=0.72); "Conducting focus group discussions" (M=3.16, SD=0.32) and "conducting community forums" (M=3.13, SD=0.64). The discrepancies implying competency deficits were widest in "Acquiring and allocating resources" (MWDS=12.67); use of information and communication technologies (ICTs) and web-based resources in agricultural extension (MWDS=12.59); and report writing and sharing the results and impacts (MWDS=11.92). It is recommended that any intervention aimed at developing the capacity of extension workers in Peninsular Malaysia should prioritize these core competency items in accordance with the deficits established in this study. Copyright © 2017 Elsevier Ltd. All rights reserved.
An approach to model reactor core nodalization for deterministic safety analysis
International Nuclear Information System (INIS)
Salim, Mohd Faiz; Samsudin, Mohd Rafie; Mamat Ibrahim, Mohd Rizal; Roslan, Ridha; Sadri, Abd Aziz; Farid, Mohd Fairus Abd
2016-01-01
Adopting good nodalization strategy is essential to produce an accurate and high quality input model for Deterministic Safety Analysis (DSA) using System Thermal-Hydraulic (SYS-TH) computer code. The purpose of such analysis is to demonstrate the compliance against regulatory requirements and to verify the behavior of the reactor during normal and accident conditions as it was originally designed. Numerous studies in the past have been devoted to the development of the nodalization strategy for small research reactor (e.g. 250kW) up to the bigger research reactor (e.g. 30MW). As such, this paper aims to discuss the state-of-arts thermal hydraulics channel to be employed in the nodalization for RTP-TRIGA Research Reactor specifically for the reactor core. At present, the required thermal-hydraulic parameters for reactor core, such as core geometrical data (length, coolant flow area, hydraulic diameters, and axial power profile) and material properties (including the UZrH 1.6 , stainless steel clad, graphite reflector) have been collected, analyzed and consolidated in the Reference Database of RTP using standardized methodology, mainly derived from the available technical documentations. Based on the available information in the database, assumptions made on the nodalization approach and calculations performed will be discussed and presented. The development and identification of the thermal hydraulics channel for the reactor core will be implemented during the SYS-TH calculation using RELAP5-3D ® computer code. This activity presented in this paper is part of the development of overall nodalization description for RTP-TRIGA Research Reactor under the IAEA Norwegian Extra-Budgetary Programme (NOKEBP) mentoring project on Expertise Development through the Analysis of Reactor Thermal-Hydraulics for Malaysia, denoted as EARTH-M
Tunable Nitride Josephson Junctions.
Energy Technology Data Exchange (ETDEWEB)
Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Henry, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lewis, Rupert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolfley, Steven L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolak, Matthaeus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-12-01
We have developed an ambient temperature, SiO_{2}/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the Ta_{x}N barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlO_{x} barriers for low - power, high - performance computing.
Righter, K.; Danielson, L.; Pando, K.; Shofner, G.; Lee, C. -T.
2013-01-01
Siderophile elements have been used to constrain conditions of core formation and differentiation for the Earth, Mars and other differentiated bodies [1]. Recent models for the Earth have concluded that the mantle and core did not fully equilibrate and the siderophile element contents of the mantle can only be explained under conditions where the oxygen fugacity changes from low to high during accretion and the mantle and core do not fully equilibrate [2,3]. However these conclusions go against several physical and chemical constraints. First, calculations suggest that even with the composition of accreting material changing from reduced to oxidized over time, the fO2 defined by metal-silicate equilibrium does not change substantially, only by approximately 1 logfO2 unit [4]. An increase of more than 2 logfO2 units in mantle oxidation are required in models of [2,3]. Secondly, calculations also show that metallic impacting material will become deformed and sheared during accretion to a large body, such that it becomes emulsified to a fine scale that allows equilibrium at nearly all conditions except for possibly the length scale for giant impacts [5] (contrary to conclusions of [6]). Using new data for D(Mo) metal/silicate at high pressures, together with updated partitioning expressions for many other elements, we will show that metal-silicate equilibrium across a long span of Earth s accretion history may explain the concentrations of many siderophile elements in Earth's mantle. The modeling includes refractory elements Ni, Co, Mo, and W, as well as highly siderophile elements Au, Pd and Pt, and volatile elements Cd, In, Bi, Sb, Ge and As.
International Nuclear Information System (INIS)
Osorio, Mayra; Anglada, Guillem; Lizano, Susana; D'Alessio, Paola
2009-01-01
We present a model aimed to reproduce the observed spectral energy distribution (SED) as well as the ammonia line emission of the G31.41+0.31 hot core. The hot core is modeled as an infalling envelope onto a massive star that is undergoing an intense accretion phase. We assume an envelope with a density and velocity structure resulting from the dynamical collapse of a singular logatropic sphere. The stellar and envelope physical properties are determined by fitting the observed SED. From these physical conditions, the emerging ammonia line emission is calculated and compared with subarcsecond resolution VLA data of the (4,4) transition taken from the literature. The only free parameter in this line fitting is the ammonia abundance. The observed intensities of the main and satellite ammonia (4,4) lines and their spatial distribution can be well reproduced provided the steep increase of the gas-phase ammonia abundance in the hotter (>100 K), inner regions of the core produced by the sublimation of icy mantles where ammonia molecules are trapped is taken into account. The model predictions for the (2,2), (4,4), and (5,5) transitions, obtained with the same set of parameters, are also reasonably in agreement, given the observational uncertainties, with the single-dish spectra of the region available in the literature. The best fit is obtained for a model with a central star of ∼25M sun , a mass accretion rate of ∼3 x 10 -3 M sun yr -1 , and a total luminosity of ∼2 x 10 5 L sun . The outer radius of the envelope is 30,000 AU, where kinetic temperatures as high as ∼40 K are reached. The gas-phase ammonia abundance ranges from ∼2 x 10 -8 in the outer region to ∼3 x 10 -6 in the inner region. To our knowledge, this is the first time that the dust and molecular line data of a hot molecular core, including subarcsecond resolution data that spatially resolve the structure of the core, have been simultaneously explained by a detailed, physically self
Development of 3D ferromagnetic model of tokamak core withstrong toroidal asymmetry
Czech Academy of Sciences Publication Activity Database
Markovič, Tomáš; Gryaznevich, M.; Ďuran, Ivan; Svoboda, V.; Pánek, Radomír
96-97, October (2015), s. 302-305 ISSN 0920-3796. [Symposium on Fusion Technology 2014(SOFT-28)/28./. San Sebastián, 29.09.2014-03.10.2014] R&D Projects: GA ČR GAP205/11/2341; GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * ferromagnetic core * model of ferromagnet * integral method * tokamak GOLEM Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.301, year: 2015 http://www.sciencedirect.com/science/article/pii/S0920379615002100
Turchi, Patrice E. A.; Fattebert, Jean-Luc; Dorr, Milo R.; Wickett, Michael E.; Belak, James F.
2011-03-01
We describe an algorithm for the numerical solution of a phase-field model (PFM) of microstructure evolution in alloys using physical parameters from thermodynamic (CALPHAD) and kinetic databases. The coupled system of PFM equations includes a local order parameter, a quaternion representation of local crystal orientation and a species composition parameter. Time evolution of microstructures and alloy composition is obtained using an implicit time integration of the system. Physical parameters in databases can be obtained either through experiment or first-principles calculations. Application to coring studies and microstructure evolution of Au-Ni will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344
Inverse stochastic-dynamic models for high-resolution Greenland ice core records
DEFF Research Database (Denmark)
Boers, Niklas; Chekroun, Mickael D.; Liu, Honghu
2017-01-01
as statistical properties such as probability density functions, waiting times and power spectra, with no need for any external forcing. The crucial ingredients for capturing these properties are (i) high-resolution training data, (ii) cubic drift terms, (iii) nonlinear coupling terms between the 18O and dust......Proxy records from Greenland ice cores have been studied for several decades, yet many open questions remain regarding the climate variability encoded therein. Here, we use a Bayesian framework for inferring inverse, stochastic-dynamic models from 18O and dust records of unprecedented, subdecadal...
Whole core neutronics modeling of a TRIGA reactor using integral transport theory
International Nuclear Information System (INIS)
Schwinkendorf, K.N.; Toffer, H.
1990-01-01
An innovative analysis approach for performing whole core reactor physics calculations for TRIGA reactors has been employed recently at the Westinghouse Hanford Company. A deterministic transport theory model with sufficient geometric complexity to evaluate asymmetric loading patterns was used. Calculations of this complexity have been performed in the past using Monte Carlo simulation, such as the MCNP code. However, the Monte Carlo calculations are more difficult to prepare and require more computer time. On the Hanford Site CRAY XMP-18 computer, the new methods required less than one-third of the central processing unit time per calculation as compared to an MCNP calculation using 100,000 neutron histories
Loper, Margaret L
2015-01-01
This easy to read text/reference provides a broad introduction to the fundamental concepts of modeling and simulation (M&S) and systems engineering, highlighting how M&S is used across the entire systems engineering lifecycle. Each chapter corresponds to a short lecture covering a core topic in M&S or systems engineering. Topics and features: reviews the full breadth of technologies, methodologies and uses of M&S, rather than just focusing on a specific aspect of the field; presents contributions from renowned specialists in each topic covered; introduces the foundational elements and proce
International Nuclear Information System (INIS)
Aragones, J.M.; Martinez-Val, J.M.; Corella, M.R.
1977-01-01
Fuel management requires that mass, energy, and reactivity balance be satisfied in each reload cycle. Procedures for selection of alternatives, core-state models, and fuel cost calculations have been developed for both equilibrium and transition cycles. Effective cycle lengths and fuel cycle variables--namely, reload batch size, schedule of incore residence for the fuel, feed enrichments, energy sharing cycle by cycle, and discharge burnup and isotopics--are the variables being considered for fuel management planning with a given energy generation plan, fuel design, recycling strategy, and financial assumptions
No-Core Shell Model for A = 47 and A = 49
Energy Technology Data Exchange (ETDEWEB)
Vary, J P; Negoita, A G; Stoica, S
2006-11-13
We apply the no-core shell model to the nuclear structure of odd-mass nuclei straddling {sup 48}Ca. Starting with the NN interaction, that fits two-body scattering and bound state data, we evaluate the nuclear properties of A = 47 and A = 49 nuclei while preserving all the underlying symmetries. Due to model space limitations and the absence of three-body interactions, we incorporate phenomenological interaction terms determined by fits to A = 48 nuclei in a previous effort. Our modified Hamiltonian produces reasonable spectra for these odd-mass nuclei. In addition to the differences in single-particle basis states, the absence of a single-particle Hamiltonian in our no-core approach complicates comparisons with valence effective NN interactions. We focus on purely off-diagonal two-body matrix elements since they are not affected by ambiguities in the different roles for one-body potentials and we compare selected sets of fp-shell matrix elements of our initial and modified Hamiltonians in the harmonic oscillator basis with those of a recent model fp-shell interaction, the GXPF1 interaction of Honma et al. While some significant differences emerge from these comparisons, there is an overall reasonably good correlation between our off-diagonal matrix elements and those of GXPF1.
Modeling of molten core-concrete interactions and fission-product release
International Nuclear Information System (INIS)
Norkus, J.K.; Corradini, M.L.
1991-09-01
The study of molten core-concrete interaction is important in estimating the possible consequences of a severe nuclear reactor accident. CORCON-Mod2 is a computer program which models the thermal, chemical, and physical phenomena associated with molten core-concrete interactions. Models have been added to extend and improve the modeling of these phenomena. An ideal solution chemical equilibrium methodology is presented to predict the fission-product vaporization release. Additional chemical species have been added, and the calculation of chemical equilibrium has been expanded to the oxidic layer and to the mixed layer configuration. Recent experiments performed at Argonne National Laboratory are compared to CORCON predictions of melt temperature, erosion depth, and release fraction of fission products. The results consistently underpredicted the melt temperatures and erosion rates. However, the predictions of release of Te, Ba, Sr, and U were good. A sensitivity study of the effects of initial temperature, concrete type, use of the mixing option, degree of zirconium oxidation, cavity size, and amount of control material on erosion, gas production, and release of radioactive materials was performed for a PWR and a BWR. The initial melt temperature had the greatest effect on the results of interest. Concrete type and cavity size also had important effects. 78 refs., 35 figs., 40 tabs
Real time thermal hydraulic model for high temperature gas-cooled reactor core
International Nuclear Information System (INIS)
Sui Zhe; Sun Jun; Ma Yuanle; Zhang Ruipeng
2013-01-01
A real-time thermal hydraulic model of the reactor core was described and integrated into the simulation system for the high temperature gas-cooled pebble bed reactor nuclear power plant, which was developed in the vPower platform, a new simulation environment for nuclear and fossil power plants. In the thermal hydraulic model, the helium flow paths were established by the flow network tools in order to obtain the flow rates and pressure distributions. Meanwhile, the heat structures, representing all the solid heat transfer elements in the pebble bed, graphite reflectors and carbon bricks, were connected by the heat transfer network in order to solve the temperature distributions in the reactor core. The flow network and heat transfer network were coupled and calculated in real time. Two steady states (100% and 50% full power) and two transients (inlet temperature step and flow step) were tested that the quantitative comparisons of the steady results with design data and qualitative analysis of the transients showed the good applicability of the present thermal hydraulic model. (authors)
A fast converging CFD model for thermal hydraulic analysis of gas cooled reactor cores
International Nuclear Information System (INIS)
Chen, Gary; Anghaie, Samim
1999-01-01
A computational fluid dynamics (CFD) approach to the solution of Navier-Stokes equations for the thermal and flow fields of gas cooled reactor cores is presented. An implicit-explicit MacCormack method based on finite volume discretization scheme, in conjunction with the Gauss-Seidel line iteration procedure is utilized to solve axisymmetric, thin-layer Navier-Stokes equations. This numerical method requires only the inversion of block bidiagonal systems rather than block tridiagonal systems, thus yielding savings in computer time and storage requirements. A two-layer algebraic eddy viscosity turbulence model is used in this study. The effects of turbulence are simulated in terms of the eddy viscosity coefficient, which is calculated for an inner and an outer region separately. An enthalpy-rebalancing scheme is implemented to allow the convergence solutions to be obtained with the application of a wall heat flux. The detailed computational analysis developed in this work is used to evaluate many different Nusselt number equations, property corrections, and axial distance corrections. The calculation based on this CFD model is compared with other published results. The good agreement indicates the usefulness of the presented model for the prediction of flow and temperature distributions for gas cooled reactor cores. (author)
Energy Technology Data Exchange (ETDEWEB)
Duffy, Stephen [Cleveland State Univ., Cleveland, OH (United States)
2013-09-09
This project will implement inelastic constitutive models that will yield the requisite stress-strain information necessary for graphite component design. Accurate knowledge of stress states (both elastic and inelastic) is required to assess how close a nuclear core component is to failure. Strain states are needed to assess deformations in order to ascertain serviceability issues relating to failure, e.g., whether too much shrinkage has taken place for the core to function properly. Failure probabilities, as opposed to safety factors, are required in order to capture the bariability in failure strength in tensile regimes. The current stress state is used to predict the probability of failure. Stochastic failure models will be developed that can accommodate possible material anisotropy. This work will also model material damage (i.e., degradation of mechanical properties) due to radiation exposure. The team will design tools for components fabricated from nuclear graphite. These tools must readily interact with finite element software--in particular, COMSOL, the software algorithm currently being utilized by the Idaho National Laboratory. For the eleastic response of graphite, the team will adopt anisotropic stress-strain relationships available in COMSO. Data from the literature will be utilized to characterize the appropriate elastic material constants.
International Nuclear Information System (INIS)
Duffy, Stephen
2013-01-01
This project will implement inelastic constitutive models that will yield the requisite stress-strain information necessary for graphite component design. Accurate knowledge of stress states (both elastic and inelastic) is required to assess how close a nuclear core component is to failure. Strain states are needed to assess deformations in order to ascertain serviceability issues relating to failure, e.g., whether too much shrinkage has taken place for the core to function properly. Failure probabilities, as opposed to safety factors, are required in order to capture the bariability in failure strength in tensile regimes. The current stress state is used to predict the probability of failure. Stochastic failure models will be developed that can accommodate possible material anisotropy. This work will also model material damage (i.e., degradation of mechanical properties) due to radiation exposure. The team will design tools for components fabricated from nuclear graphite. These tools must readily interact with finite element software--in particular, COMSOL, the software algorithm currently being utilized by the Idaho National Laboratory. For the eleastic response of graphite, the team will adopt anisotropic stress-strain relationships available in COMSO. Data from the literature will be utilized to characterize the appropriate elastic material constants.
International Nuclear Information System (INIS)
Mitsuyasu, Takeshi; Aoyama, Motoo; Yamamoto, Akio
2017-01-01
Highlights: • A coupling model of the two-stage core calculation with subchannel analysis. • BWR fuel assembly parameters are assumed and verified. • The model was evaluated for heterogeneous problems. - Abstract: The two-stage core analysis method is widely used for BWR core analysis. The purpose of this study is to develop a core analysis model coupled with subchannel analysis within the two-stage calculation scheme using an assembly-based thermal-hydraulics calculation in the core analysis. The model changes the 2D lattice physics scheme, and couples with 3D subchannel analysis which evaluates the thermal-hydraulics characteristics within the coolant flow area divided as some subchannel regions. In order to couple with these two analyses, some BWR fuel assembly parameters are assumed and verified. The developed model is evaluated for the heterogeneous problem with and without a control rod. The present model is especially effective for the control rod inserted condition. The present model can incorporate the subchannel effect into the current two-stage core calculation method.
Proposed model for fuel-coolant mixing during a core-melt accident
International Nuclear Information System (INIS)
Corradini, M.L.
1983-01-01
If complete failure of normal and emergency coolant flow occurs in a light water reactor, fission product decay heat would eventually cause melting of the reactor fuel and cladding. The core melt may then slump into the lower plenum and later into the reactor cavity and contact residual liquid water. A model is proposed to describe the fuel-coolant mixing process upon contact. The model is compared to intermediate scale experiments being conducted at Sandia. The modelling of this mixing process will aid in understanding three important processes: (1) fuel debris sizes upon quenching in water, (2) the hydrogen source term during fuel quench, and (3) the rate of steam production. Additional observations of Sandia data indicate that the steam explosion is affected by this mixing process
Inference of ICF Implosion Core Mix using Experimental Data and Theoretical Mix Modeling
International Nuclear Information System (INIS)
Welser-Sherrill, L.; Haynes, D.A.; Mancini, R.C.; Cooley, J.H.; Tommasini, R.; Golovkin, I.E.; Sherrill, M.E.; Haan, S.W.
2009-01-01
The mixing between fuel and shell materials in Inertial Confinement Fusion (ICF) implosion cores is a current topic of interest. The goal of this work was to design direct-drive ICF experiments which have varying levels of mix, and subsequently to extract information on mixing directly from the experimental data using spectroscopic techniques. The experimental design was accomplished using hydrodynamic simulations in conjunction with Haan's saturation model, which was used to predict the mix levels of candidate experimental configurations. These theoretical predictions were then compared to the mixing information which was extracted from the experimental data, and it was found that Haan's mix model performed well in predicting trends in the width of the mix layer. With these results, we have contributed to an assessment of the range of validity and predictive capability of the Haan saturation model, as well as increased our confidence in the methods used to extract mixing information from experimental data.
On simulation of local fluxes in molecular junctions
Cabra, Gabriel; Jensen, Anders; Galperin, Michael
2018-05-01
We present a pedagogical review of the current density simulation in molecular junction models indicating its advantages and deficiencies in analysis of local junction transport characteristics. In particular, we argue that current density is a universal tool which provides more information than traditionally simulated bond currents, especially when discussing inelastic processes. However, current density simulations are sensitive to the choice of basis and electronic structure method. We note that while discussing the local current conservation in junctions, one has to account for the source term caused by the open character of the system and intra-molecular interactions. Our considerations are illustrated with numerical simulations of a benzenedithiol molecular junction.
Some chaotic features of intrinsically coupled Josephson junctions
International Nuclear Information System (INIS)
Kolahchi, M.R.; Shukrinov, Yu.M.; Hamdipour, M.; Botha, A.E.; Suzuki, M.
2013-01-01
Highlights: ► Intrinsically coupled Josephson junctions model a high-T c superconductor. ► Intrinsically coupled Josephson junctions can act as a chaotic nonlinear system. ► Chaos could be due to resonance overlap. ► Avoiding parameters that lead to chaos is important for the design of resonators. -- Abstract: We look for chaos in an intrinsically coupled system of Josephson junctions. This study has direct applications for the high-T c resonators which require coherence amongst the junctions
International Nuclear Information System (INIS)
Golovanov, M.N.; Zyuzin, N.N.; Levin, G.L.; Chesnokov, A.N.
1987-01-01
An approach for estimation of reliability factors of complex reserved systems at early stages of development using the method of imitating simulation is considered. Different types of models, their merits and lacks are given. Features of in-core monitoring systems and advosability of graph model and graph theory element application for estimating reliability of such systems are shown. The results of investigation of the reliability factors of the reactor monitoring, control and core local protection subsystem are shown
Budnar, Srikanth; Yap, Alpha S.
2017-01-01
Mechanical coherence of cell layers is essential for epithelia to function as tissue barriers and to control active tissue dynamics during morphogenesis. RhoA signaling at adherens junctions plays a key role in this process by coupling cadherin-based cell-cell adhesion together with actomyosin contractility. Here we propose and analyze a mathematical model representing core interactions involved in the spatial localization of junctional RhoA signaling. We demonstrate how the interplay between biochemical signaling through positive feedback, combined with diffusion on the cell membrane and mechanical forces generated in the cortex, can determine the spatial distribution of RhoA signaling at cell-cell junctions. This dynamical mechanism relies on the balance between a propagating bistable signal that is opposed by an advective flow generated by an actomyosin stress gradient. Experimental observations on the behavior of the system when contractility is inhibited are in qualitative agreement with the predictions of the model. PMID:28273072
Directory of Open Access Journals (Sweden)
Rashmi Priya
2017-03-01
Full Text Available Mechanical coherence of cell layers is essential for epithelia to function as tissue barriers and to control active tissue dynamics during morphogenesis. RhoA signaling at adherens junctions plays a key role in this process by coupling cadherin-based cell-cell adhesion together with actomyosin contractility. Here we propose and analyze a mathematical model representing core interactions involved in the spatial localization of junctional RhoA signaling. We demonstrate how the interplay between biochemical signaling through positive feedback, combined with diffusion on the cell membrane and mechanical forces generated in the cortex, can determine the spatial distribution of RhoA signaling at cell-cell junctions. This dynamical mechanism relies on the balance between a propagating bistable signal that is opposed by an advective flow generated by an actomyosin stress gradient. Experimental observations on the behavior of the system when contractility is inhibited are in qualitative agreement with the predictions of the model.
Advanced Test Reactor Core Modeling Update Project Annual Report for Fiscal Year 2012
Energy Technology Data Exchange (ETDEWEB)
David W. Nigg, Principal Investigator; Kevin A. Steuhm, Project Manager
2012-09-01
Legacy computational reactor physics software tools and protocols currently used for support of Advanced Test Reactor (ATR) core fuel management and safety assurance, and to some extent, experiment management, are inconsistent with the state of modern nuclear engineering practice, and are difficult, if not impossible, to properly verify and validate (V&V) according to modern standards. Furthermore, the legacy staff knowledge required for application of these tools and protocols from the 1960s and 1970s is rapidly being lost due to staff turnover and retirements. In late 2009, the Idaho National Laboratory (INL) initiated a focused effort, the ATR Core Modeling Update Project, to address this situation through the introduction of modern high-fidelity computational software and protocols. This aggressive computational and experimental campaign will have a broad strategic impact on the operation of the ATR, both in terms of improved computational efficiency and accuracy for support of ongoing DOE programs as well as in terms of national and international recognition of the ATR National Scientific User Facility (NSUF). The ATR Core Modeling Update Project, targeted for full implementation in phase with the next anticipated ATR Core Internals Changeout (CIC) in the 2014-2015 time frame, began during the last quarter of Fiscal Year 2009, and has just completed its third full year. Key accomplishments so far have encompassed both computational as well as experimental work. A new suite of stochastic and deterministic transport theory based reactor physics codes and their supporting nuclear data libraries (HELIOS, KENO6/SCALE, NEWT/SCALE, ATTILA, and an extended implementation of MCNP5) has been installed at the INL under various licensing arrangements. Corresponding models of the ATR and ATRC are now operational with all five codes, demonstrating the basic feasibility of the new code packages for their intended purpose. Of particular importance, a set of as-run core
Energy Technology Data Exchange (ETDEWEB)
Jardanhazy, Anett [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary); Molnar, Mark [Department of Psychophysiology, Institute for Psychology of the Hungarian Academy of Sciences, P.O. Box 398, Budapest H-1394 (Hungary)], E-mail: molnar@cogpsyphy.hu; Jardanhazy, Tamas [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary)], E-mail: jt@nepsy.szote.u-szeged.hu
2009-04-15
The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.
International Nuclear Information System (INIS)
Jardanhazy, Anett; Molnar, Mark; Jardanhazy, Tamas
2009-01-01
The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.
Microscopic tunneling theory of long Josephson junctions
DEFF Research Database (Denmark)
Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm
1992-01-01
We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...
International Nuclear Information System (INIS)
Ohshima, Hiroyuki
2001-10-01
A whole core thermal-hydraulic analysis program ACT is being developed for the purpose of evaluating detailed in-core thermal hydraulic phenomena of fast reactors including the effect of the flow between wrapper-tube walls (inter-wrapper flow) under various reactor operation conditions. As appropriate boundary conditions in addition to a detailed modeling of the core are essential for accurate simulations of in-core thermal hydraulics, ACT consists of not only fuel assembly and inter-wrapper flow analysis modules but also a heat transport system analysis module that gives response of the plant dynamics to the core model. This report describes incorporation of a simplified model to the fuel assembly analysis module and program parallelization by a message passing method toward large-scale simulations. ACT has a fuel assembly analysis module which can simulate a whole fuel pin bundle in each fuel assembly of the core and, however, it may take much CPU time for a large-scale core simulation. Therefore, a simplified fuel assembly model that is thermal-hydraulically equivalent to the detailed one has been incorporated in order to save the simulation time and resources. This simplified model is applied to several parts of fuel assemblies in a core where the detailed simulation results are not required. With regard to the program parallelization, the calculation load and the data flow of ACT were analyzed and the optimum parallelization has been done including the improvement of the numerical simulation algorithm of ACT. Message Passing Interface (MPI) is applied to data communication between processes and synchronization in parallel calculations. Parallelized ACT was verified through a comparison simulation with the original one. In addition to the above works, input manuals of the core analysis module and the heat transport system analysis module have been prepared. (author)
GrowYourIC: A Step Toward a Coherent Model of the Earth's Inner Core Seismic Structure
Lasbleis, Marine; Waszek, Lauren; Day, Elizabeth A.
2017-11-01
A complex inner core structure has been well established from seismic studies, showing radial and lateral heterogeneities at various length scales. Yet no geodynamic model is able to explain all the features observed. One of the main limits for this is the lack of tools to compare seismic observations and numerical models successfully. We use here a new Python tool called GrowYourIC to compare models of inner core structure. We calculate properties of geodynamic models of the inner core along seismic raypaths, for random or user-specified data sets. We test kinematic models which simulate fast lateral translation, superrotation, and differential growth. We explore first the influence on a real inner core data set, which has a sparse coverage of the inner core boundary. Such a data set is however able to successfully constrain the hemispherical boundaries due to a good sampling of latitudes. Combining translation and rotation could explain some of the features of the boundaries separating the inner core hemispheres. The depth shift of the boundaries, observed by some authors, seems unlikely to be modeled by a fast translation but could be produced by slow translation associated with superrotation.
Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H.
2012-01-01
-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising
Chopra, Sanjeev; Kataria, Rashim; Sinha, Virendra Deo
2017-01-01
Background Spinal instrumentation using rods and screws have become procedure of choice for posterior fixation. Vertebral artery anatomy is highly variable in this region posing challenges during surgery. Our study used 3D printer model to understand the anatomy and variations in vertebral artery in live patients thereby providing an accurate idea about vertebral artery injury risk in these patients preoperatively and to rehearse the whole procedure. Methods Ten patients of developmental craniovertebral junction (CVJ) anomalies who were planned for operative intervention in the Department of Neurosurgery at SMS Hospital from February 2016 to December 2016 were analysed using a 3D printer model. Results Out of twenty vertebral arteries studied in ten patients, two were hypoplastic and out of these one could not be appreciated on 3D printer model. Out of remaining nineteen, thirteen arteries were found to lie outside the joint, three were in lateral third, one traversed the middle third of joint and one lied in medial third. In one patient, the vertebral artery was stretched and it traversed horizontally over the joint. Out of ten patients studied, nine were having occipitalised atlas and so entry of these vertebral arteries into cranium were classified as given by Wang et al. into four types. Conclusions By our study, 3D printer model was extremely helpful in analyzing joints and vertebral artery preoperatively and making the surgeon acquainted about the placement and trajectory of the screws accordingly. In our opinion, these models should be included as a basic investigation tool in these patients. PMID:29354734
A core stochastic population projection model for Florida manatees (Trichechus manatus latirostris)
Runge, Michael C.; Sanders-Reed, Carol A.; Fonnesbeck, Christopher J.
2007-01-01
threats are likely to result in a long-term decline in the statewide population and a change in the regional distribution of manatees. Analyses of sensitivity and variance contribution highlight the importance of reducing uncertainty in some life-history parameters, particularly adult survival, temporal variance of adult survival, and long-term warm-water capacity. This core biological model is expected to evolve over time, as better information becomes available about manatees and their habitat, and as new assessment needs arise. We anticipate that this core model will be customized for other state and federal assessments in the near future.
TWO-DIMENSIONAL CORE-COLLAPSE SUPERNOVA MODELS WITH MULTI-DIMENSIONAL TRANSPORT
International Nuclear Information System (INIS)
Dolence, Joshua C.; Burrows, Adam; Zhang, Weiqun
2015-01-01
We present new two-dimensional (2D) axisymmetric neutrino radiation/hydrodynamic models of core-collapse supernova (CCSN) cores. We use the CASTRO code, which incorporates truly multi-dimensional, multi-group, flux-limited diffusion (MGFLD) neutrino transport, including all relevant O(v/c) terms. Our main motivation for carrying out this study is to compare with recent 2D models produced by other groups who have obtained explosions for some progenitor stars and with recent 2D VULCAN results that did not incorporate O(v/c) terms. We follow the evolution of 12, 15, 20, and 25 solar-mass progenitors to approximately 600 ms after bounce and do not obtain an explosion in any of these models. Though the reason for the qualitative disagreement among the groups engaged in CCSN modeling remains unclear, we speculate that the simplifying ''ray-by-ray'' approach employed by all other groups may be compromising their results. We show that ''ray-by-ray'' calculations greatly exaggerate the angular and temporal variations of the neutrino fluxes, which we argue are better captured by our multi-dimensional MGFLD approach. On the other hand, our 2D models also make approximations, making it difficult to draw definitive conclusions concerning the root of the differences between groups. We discuss some of the diagnostics often employed in the analyses of CCSN simulations and highlight the intimate relationship between the various explosion conditions that have been proposed. Finally, we explore the ingredients that may be missing in current calculations that may be important in reproducing the properties of the average CCSNe, should the delayed neutrino-heating mechanism be the correct mechanism of explosion
Baczyńska, Anna K; Rowiński, Tomasz; Cybis, Natalia
2016-01-01
Competency models provide insight into key skills which are common to many positions in an organization. Moreover, there is a range of competencies that is used by many companies. Researchers have developed core competency terminology to underline their cross-organizational value. The article presents a theoretical model of core competencies consisting of two main higher-order competencies called performance and entrepreneurship. Each of them consists of three elements: the performance competency includes cooperation, organization of work and goal orientation, while entrepreneurship includes innovativeness, calculated risk-taking and pro-activeness. However, there is lack of empirical validation of competency concepts in organizations and this would seem crucial for obtaining reliable results from organizational research. We propose a two-step empirical validation procedure: (1) confirmation factor analysis, and (2) classification of employees. The sample consisted of 636 respondents (M = 44.5; SD = 15.1). Participants were administered a questionnaire developed for the study purpose. The reliability, measured by Cronbach's alpha, ranged from 0.60 to 0.83 for six scales. Next, we tested the model using a confirmatory factor analysis. The two separate, single models of performance and entrepreneurial orientations fit quite well to the data, while a complex model based on the two single concepts needs further research. In the classification of employees based on the two higher order competencies we obtained four main groups of employees. Their profiles relate to those found in the literature, including so-called niche finders and top performers. Some proposal for organizations is discussed.
Asteroseismic Constraints on the Models of Hot B Subdwarfs: Convective Helium-Burning Cores
Schindler, Jan-Torge; Green, Elizabeth M.; Arnett, W. David
2017-10-01
Asteroseismology of non-radial pulsations in Hot B Subdwarfs (sdB stars) offers a unique view into the interior of core-helium-burning stars. Ground-based and space-borne high precision light curves allow for the analysis of pressure and gravity mode pulsations to probe the structure of sdB stars deep into the convective core. As such asteroseismological analysis provides an excellent opportunity to test our understanding of stellar evolution. In light of the newest constraints from asteroseismology of sdB and red clump stars, standard approaches of convective mixing in 1D stellar evolution models are called into question. The problem lies in the current treatment of overshooting and the entrainment at the convective boundary. Unfortunately no consistent algorithm of convective mixing exists to solve the problem, introducing uncertainties to the estimates of stellar ages. Three dimensional simulations of stellar convection show the natural development of an overshooting region and a boundary layer. In search for a consistent prescription of convection in one dimensional stellar evolution models, guidance from three dimensional simulations and asteroseismological results is indispensable.
The Use of Hidden Markov Models for Anomaly Detection in Nuclear Core Condition Monitoring
Stephen, Bruce; West, Graeme M.; Galloway, Stuart; McArthur, Stephen D. J.; McDonald, James R.; Towle, Dave
2009-04-01
Unplanned outages can be especially costly for generation companies operating nuclear facilities. Early detection of deviations from expected performance through condition monitoring can allow a more proactive and managed approach to dealing with ageing plant. This paper proposes an anomaly detection framework incorporating the use of the Hidden Markov Model (HMM) to support the analysis of nuclear reactor core condition monitoring data. Fuel Grab Load Trace (FGLT) data gathered within the UK during routine refueling operations has been seen to provide information relating to the condition of the graphite bricks that comprise the core. Although manual analysis of this data is time consuming and requires considerable expertise, this paper demonstrates how techniques such as the HMM can provide analysis support by providing a benchmark model of expected behavior against which future refueling events may be compared. The presence of anomalous behavior in candidate traces is inferred through the underlying statistical foundation of the HMM which gives an observation likelihood averaged along the length of the input sequence. Using this likelihood measure, the engineer can be alerted to anomalous behaviour, indicating data which might require further detailed examination. It is proposed that this data analysis technique is used in conjunction with other intelligent analysis techniques currently employed to analyse FGLT to provide a greater confidence measure in detecting anomalous behaviour from FGLT data.
Inverse stochastic–dynamic models for high-resolution Greenland ice core records
Directory of Open Access Journals (Sweden)
N. Boers
2017-12-01
Full Text Available Proxy records from Greenland ice cores have been studied for several decades, yet many open questions remain regarding the climate variability encoded therein. Here, we use a Bayesian framework for inferring inverse, stochastic–dynamic models from δ18O and dust records of unprecedented, subdecadal temporal resolution. The records stem from the North Greenland Ice Core Project (NGRIP, and we focus on the time interval 59–22 ka b2k. Our model reproduces the dynamical characteristics of both the δ18O and dust proxy records, including the millennial-scale Dansgaard–Oeschger variability, as well as statistical properties such as probability density functions, waiting times and power spectra, with no need for any external forcing. The crucial ingredients for capturing these properties are (i high-resolution training data, (ii cubic drift terms, (iii nonlinear coupling terms between the δ18O and dust time series, and (iv non-Markovian contributions that represent short-term memory effects.
Inverse stochastic-dynamic models for high-resolution Greenland ice core records
Boers, Niklas; Chekroun, Mickael D.; Liu, Honghu; Kondrashov, Dmitri; Rousseau, Denis-Didier; Svensson, Anders; Bigler, Matthias; Ghil, Michael
2017-12-01
Proxy records from Greenland ice cores have been studied for several decades, yet many open questions remain regarding the climate variability encoded therein. Here, we use a Bayesian framework for inferring inverse, stochastic-dynamic models from δ18O and dust records of unprecedented, subdecadal temporal resolution. The records stem from the North Greenland Ice Core Project (NGRIP), and we focus on the time interval 59-22 ka b2k. Our model reproduces the dynamical characteristics of both the δ18O and dust proxy records, including the millennial-scale Dansgaard-Oeschger variability, as well as statistical properties such as probability density functions, waiting times and power spectra, with no need for any external forcing. The crucial ingredients for capturing these properties are (i) high-resolution training data, (ii) cubic drift terms, (iii) nonlinear coupling terms between the δ18O and dust time series, and (iv) non-Markovian contributions that represent short-term memory effects.
3-D core modelling of RIA transient: the TMI-1 benchmark
International Nuclear Information System (INIS)
Ferraresi, P.; Studer, E.; Avvakumov, A.; Malofeev, V.; Diamond, D.; Bromley, B.
2001-01-01
The increase of fuel burn up in core management poses actually the problem of the evaluation of the deposited energy during Reactivity Insertion Accidents (RIA). In order to precisely evaluate this energy, 3-D approaches are used more and more frequently in core calculations. This 'best-estimate' approach requires the evaluation of code uncertainties. To contribute to this evaluation, a code benchmark has been launched. A 3-D modelling for the TMI-1 central Ejected Rod Accident with zero and intermediate initial powers was carried out with three different methods of calculation for an inserted reactivity respectively fixed at 1.2 $ and 1.26 $. The studies implemented by the neutronics codes PARCS (BNL) and CRONOS (IPSN/CEA) describe an homogeneous assembly, whereas the BARS (KI) code allows a pin-by-pin representation (CRONOS has both possibilities). All the calculations are consistent, the variation in figures resulting mainly from the method used to build cross sections and reflectors constants. The maximum rise in enthalpy for the intermediate initial power (33 % P N ) calculation is, for this academic calculation, about 30 cal/g. This work will be completed in a next step by an evaluation of the uncertainty induced by the uncertainty on model parameters, and a sensitivity study of the key parameters for a peripheral Rod Ejection Accident. (authors)
Comparison of CORA and MELCOR core degradation simulation and the MELCOR oxidation model
International Nuclear Information System (INIS)
Wang, Jun; Corradini, Michael L.; Fu, Wen; Haskin, Troy; Tian, Wenxi; Zhang, Yapei; Su, Guanghui; Qiu, Suizheng
2014-01-01
Highlights: • Oxidation model of MELCOR is analyzed and the improving suggestion is provided. • MELCOR core degradation calculating results are compared with CORA experiment. • Flow rate of argon and steam, the generating rate of hydrogen is calculated and compared. • Temperature spatial variation and temperature history is calculated and presented. - Abstract: MELCOR is widely used and sufficiently trusted for severe accident analysis. However, the occurrence of Fukushima has increased the focus on severe accident codes and their use. A MELCOR core degradation calculation was conducted at the University of Wisconsin–Madison under the help of Sandia. The calculation results were checked by comparing with a past CORA experiment. MELCOR calculation results included the flow rate of argon and steam, the generation rate of hydrogen. Through this work, the performance of MELCOR COR package was reviewed in detail. This paper compares the hydrogen generation rates predicted by MELCOR to the CORA test data. While agreement is reasonable it could be improved. Additionally, the MELCOR zirconium oxidation model was analyzed
Comparison of CORA and MELCOR core degradation simulation and the MELCOR oxidation model
Energy Technology Data Exchange (ETDEWEB)
Wang, Jun [College of Engineering, The University of Wisconsin-Madison, Madison, WI 53706 (United States); State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Corradini, Michael L., E-mail: corradini@engr.wisc.edu [College of Engineering, The University of Wisconsin-Madison, Madison, WI 53706 (United States); Fu, Wen [College of Engineering, The University of Wisconsin-Madison, Madison, WI 53706 (United States); Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Haskin, Troy [College of Engineering, The University of Wisconsin-Madison, Madison, WI 53706 (United States); Tian, Wenxi; Zhang, Yapei; Su, Guanghui; Qiu, Suizheng [State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)
2014-09-15
Highlights: • Oxidation model of MELCOR is analyzed and the improving suggestion is provided. • MELCOR core degradation calculating results are compared with CORA experiment. • Flow rate of argon and steam, the generating rate of hydrogen is calculated and compared. • Temperature spatial variation and temperature history is calculated and presented. - Abstract: MELCOR is widely used and sufficiently trusted for severe accident analysis. However, the occurrence of Fukushima has increased the focus on severe accident codes and their use. A MELCOR core degradation calculation was conducted at the University of Wisconsin–Madison under the help of Sandia. The calculation results were checked by comparing with a past CORA experiment. MELCOR calculation results included the flow rate of argon and steam, the generation rate of hydrogen. Through this work, the performance of MELCOR COR package was reviewed in detail. This paper compares the hydrogen generation rates predicted by MELCOR to the CORA test data. While agreement is reasonable it could be improved. Additionally, the MELCOR zirconium oxidation model was analyzed.
3-D core modelling of RIA transient: the TMI-1 benchmark
Energy Technology Data Exchange (ETDEWEB)
Ferraresi, P. [CEA Cadarache, Institut de Protection et de Surete Nucleaire, Dept. de Recherches en Securite, 13 - Saint Paul Lez Durance (France); Studer, E. [CEA Saclay, Dept. Modelisation de Systemes et Structures, 91 - Gif sur Yvette (France); Avvakumov, A.; Malofeev, V. [Nuclear Safety Institute of Russian Research Center, Kurchatov Institute, Moscow (Russian Federation); Diamond, D.; Bromley, B. [Nuclear Energy and Infrastructure Systems Div., Brookhaven National Lab., BNL, Upton, NY (United States)
2001-07-01
The increase of fuel burn up in core management poses actually the problem of the evaluation of the deposited energy during Reactivity Insertion Accidents (RIA). In order to precisely evaluate this energy, 3-D approaches are used more and more frequently in core calculations. This 'best-estimate' approach requires the evaluation of code uncertainties. To contribute to this evaluation, a code benchmark has been launched. A 3-D modelling for the TMI-1 central Ejected Rod Accident with zero and intermediate initial powers was carried out with three different methods of calculation for an inserted reactivity respectively fixed at 1.2 $ and 1.26 $. The studies implemented by the neutronics codes PARCS (BNL) and CRONOS (IPSN/CEA) describe an homogeneous assembly, whereas the BARS (KI) code allows a pin-by-pin representation (CRONOS has both possibilities). All the calculations are consistent, the variation in figures resulting mainly from the method used to build cross sections and reflectors constants. The maximum rise in enthalpy for the intermediate initial power (33 % P{sub N}) calculation is, for this academic calculation, about 30 cal/g. This work will be completed in a next step by an evaluation of the uncertainty induced by the uncertainty on model parameters, and a sensitivity study of the key parameters for a peripheral Rod Ejection Accident. (authors)
Different Paths to Core Pathology: The Equifinal Model of the Schizophrenia Syndrome.
Green, Isobel W; Glausier, Jill R
2016-05-01
Schizophrenia is a clinically heterogeneous disorder that is perhaps more accurately characterized as "the schizophrenia syndrome." This clinical heterogeneity is reflected in the heterogeneous neurobiological presentations associated with the illness. Moreover, even highly specific neural aberrations that are associated with distinct symptoms of schizophrenia are linked to a wide range of risk factors. As such, any individual with schizophrenia likely has a particular set of risk factors that interact and converge to cross the disease threshold, forming a particular etiology that ultimately generates a core pathophysiology. This core pathophysiology may then produce 1 or more symptoms of schizophrenia, leading to common symptoms across individuals in spite of disparate etiologies. As such, the schizophrenia syndrome can be considered as anequifinalentity: a state of dysfunction that can arise from different upstream etiologies. Moreover, schizophrenia etiologies are multifactorial and can involve the interactive effects of a broad range of genetic, environmental, and developmental risk factors. Through a consideration of how disparate etiologies, caused by different sets of risk factors, converge on the same net dysfunction, this paper aims to model the equifinal nature of schizophrenia symptoms. To demonstrate the equifinal model, we discuss how maternal infection and adolescent cannabis use, 2 recognized schizophrenia risk factors, may interact with other genetic, environmental, and/or developmental risk factors to cause the conserved clinical presentation of impaired working memory. © The Author 2015. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.
International Nuclear Information System (INIS)
Wigeland, R.A.
1987-01-01
The present emphasis on inherent safety for LMR designs has resulted in a need to represent the various reactivity feedback mechanisms as accurately as possible. The dominant negative reactivity feedback has been found to result from radial expansion of the core for most postulated ATWS events. For this reason, a more detailed model for calculating the reactivity feedback from radial core expansion has been recently developed for use with the SASSYS/SAS4A Code System. The purpose of this summary is to present an extension to the model so that it is more suitable for handling a core restraint design as used in FFTF, and to compare the SASSYS/SAS4A results using this model to the empirical correlation presently being used to account for radial core expansion reactivity feedback to FFTF
Energy Technology Data Exchange (ETDEWEB)
Zhang, X. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Izaurralde, R. C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zong, Z. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhao, K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thomson, A. M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2012-08-20
The efficiency of calibrating physically-based complex hydrologic models is a major concern in the application of those models to understand and manage natural and human activities that affect watershed systems. In this study, we developed a multi-core aware multi-objective evolutionary optimization algorithm (MAMEOA) to improve the efficiency of calibrating a worldwide used watershed model (Soil and Water Assessment Tool (SWAT)). The test results show that MAMEOA can save about 1-9%, 26-51%, and 39-56% time consumed by calibrating SWAT as compared with sequential method by using dual-core, quad-core, and eight-core machines, respectively. Potential and limitations of MAMEOA for calibrating SWAT are discussed. MAMEOA is open source software.
Modelling of RPV lower head under core melt severe accident condition using OpenFOAM
International Nuclear Information System (INIS)
Madokoro, Hiroshi; Kretzschmar, Frank; Miassoedov, Alexei
2017-01-01
Although six years have been passed since the tragic severe accident at Fukushima Daiichi, still large uncertainties exist in modeling of core degradation and reactor pressure vessel (RPV) failure. It is extremely important to obtain a better understanding of complex phenomena in the lower head in order to improve accident management measures. The possible failure mode of reactor pressure vessel and its failure time are especially a matter of importance. Thermal behavior of the molten pool can be simulated by the Phase-change Effective Convectivity Model (PECM), which is a distributed-parameter model developed in the Royal Institute of Technology (KTH), Sweden. The model calculates convective currents not using a pure CFD approach but based on so called “characteristic velocities” that are determined by empirical correlations depending on the geometry and physical properties of the molten pool. At the Karlsruhe Institute of Technology (KIT), the PECM has been implemented in the open-source CFD software OpenFOAM in order to receive detailed predictions of a core melt behavior in the RPV lower head under severe accident conditions. An advantage of using OpenFOAM is that it is very flexible to add and modify models and physical properties. In the current work, the solver is extended to couple PECM with a structure analysis model of the vessel wall. The model considers thermal expansion, plasticity, creep and damage. The model and physical properties are based on those implemented in ANSYS. Although the previous implementation had restriction that the amount of and geometry of the melt cannot be changed, our coupled model allows flexibility of the melt amount and geometry. The extended solver was used to simulate the LIVE-L1 and -L7V experiments and has demonstrated good prediction of the temperature distribution in the molten pool and heat flux distribution through the vessel wall. Regarding the vessel failure the model was applied to one of the FOREVER tests
Magnetic model for a horse-spleen ferritin with a three-phase core structure
Energy Technology Data Exchange (ETDEWEB)
Jung, J.H.; Eom, T.W. [Quantum Photonic Science Research Center, Department of Physics and Research Institute for Natural Sciences, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Y.P., E-mail: yplee@hanyang.ac.kr [Quantum Photonic Science Research Center, Department of Physics and Research Institute for Natural Sciences, Hanyang University, Seoul 133-791 (Korea, Republic of); Rhee, J.Y. [Department of Physics, Sungkyunkwan University, Suwon (Korea, Republic of); Choi, E.H. [Kwangwoon University, Seoul (Korea, Republic of)
2011-12-15
The increasing interests in magnetic nanoparticles has prompted research on ferritin, which is naturally a well-defined iron-storage protein in most living organisms. However, the exact magnetic behavior of ferritin is not well understood, because the crystal structures of ferritin and ferrihydrite, its major component, are not fully understood. Briefly, we discuss the previous magnetization models of ferritin and ferrihydrite and we present a new model ({Sigma}3L) of the initial magnetization of ferritin, considering its different phases. The new model includes three Langevin-function terms, which represent three different magnetic moments provided by the likely hydroxide and oxide mineral phases in ferritin. Compared to previous models, our simple model fits the experimental data 12 times better in terms of the sum of least squares. The magnetic independence of each component supports the multi-phase compositional model of the mineral core of horse-spleen ferritin. This {Sigma}3L model gives a quantization of the amounts of the different phases within horse-spleen ferritins that matches other published experimental data: 60-80% ferrihydrite, 15-25% maghemite/magnetite, and 1-10% hematite. - Highlights: > We present a new model ({Sigma}3L) of the initial magnetization of ferritin, considering its different phases. > New model includes three Langevin-function terms, which represent three different magnetic moments provided by ferritin phases. > Compared to previous models, our simple model fits the experimental data 12 times better in terms of the sum of least square. > The magnetic independence of each component supports that ferritin and ferrihydrite are composed of different phases.
Experimental modelling of core debris dispersion from the vault under a PWR pressure vessel. Pt. 2
International Nuclear Information System (INIS)
Rose, P.W.
1987-12-01
In previous experiments, done on a 1/25 scale model in Perspex of the vault under a PWR pressure vessel, the instrument tubes support structure built into the vault was not included. It consists of a number of grids made up of fairly massive steel girders. These have now been added to the model and experiments performed using water to simulate molten core debris assumed to have fallen on to the vault floor and high-pressure air to simulate the discharge of steam or gas from the assumed breach at the bottom of the pressure vessel. The results show that the tubes support structure considerably reduces the carry-over of liquid via the vault access shafts. (author)
Low-Temperature Crystal Structures of the Hard Core Square Shoulder Model
Directory of Open Access Journals (Sweden)
Alexander Gabriëlse
2017-11-01
Full Text Available In many cases, the stability of complex structures in colloidal systems is enhanced by a competition between different length scales. Inspired by recent experiments on nanoparticles coated with polymers, we use Monte Carlo simulations to explore the types of crystal structures that can form in a simple hard-core square shoulder model that explicitly incorporates two favored distances between the particles. To this end, we combine Monte Carlo-based crystal structure finding algorithms with free energies obtained using a mean-field cell theory approach, and draw phase diagrams for two different values of the square shoulder width as a function of the density and temperature. Moreover, we map out the zero-temperature phase diagram for a broad range of shoulder widths. Our results show the stability of a rich variety of crystal phases, such as body-centered orthogonal (BCO lattices not previously considered for the square shoulder model.
Gas Core Reactor Numerical Simulation Using a Coupled MHD-MCNP Model
Kazeminezhad, F.; Anghaie, S.
2008-01-01
Analysis is provided in this report of using two head-on magnetohydrodynamic (MHD) shocks to achieve supercritical nuclear fission in an axially elongated cylinder filled with UF4 gas as an energy source for deep space missions. The motivation for each aspect of the design is explained and supported by theory and numerical simulations. A subsequent report will provide detail on relevant experimental work to validate the concept. Here the focus is on the theory of and simulations for the proposed gas core reactor conceptual design from the onset of shock generations to the supercritical state achieved when the shocks collide. The MHD model is coupled to a standard nuclear code (MCNP) to observe the neutron flux and fission power attributed to the supercritical state brought about by the shock collisions. Throughout the modeling, realistic parameters are used for the initial ambient gaseous state and currents to ensure a resulting supercritical state upon shock collisions.
STEADY STATE MODELING OF THE MINIMUM CRITICAL CORE OF THE TRANSIENT REACTOR TEST FACILITY
Energy Technology Data Exchange (ETDEWEB)
Anthony L. Alberti; Todd S. Palmer; Javier Ortensi; Mark D. DeHart
2016-05-01
With the advent of next generation reactor systems and new fuel designs, the U.S. Department of Energy (DOE) has identified the need for the resumption of transient testing of nuclear fuels. The DOE has decided that the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory (INL) is best suited for future testing. TREAT is a thermal neutron spectrum, air-cooled, nuclear test facility that is designed to test nuclear fuels in transient scenarios. These specific scenarios range from simple temperature transients to full fuel melt accidents. DOE has expressed a desire to develop a simulation capability that will accurately model the experiments before they are irradiated at the facility. It is the aim for this capability to have an emphasis on effective and safe operation while minimizing experimental time and cost. The multi physics platform MOOSE has been selected as the framework for this project. The goals for this work are to identify the fundamental neutronics properties of TREAT and to develop an accurate steady state model for future multiphysics transient simulations. In order to minimize computational cost, the effect of spatial homogenization and angular discretization are investigated. It was found that significant anisotropy is present in TREAT assemblies and to capture this effect, explicit modeling of cooling channels and inter-element gaps is necessary. For this modeling scheme, single element calculations at 293 K gave power distributions with a root mean square difference of 0.076% from those of reference SERPENT calculations. The minimum critical core configuration with identical gap and channel treatment at 293 K resulted in a root mean square, total core, radial power distribution 2.423% different than those of reference SERPENT solutions.
Tungsten Transport in the Core of JET H-mode Plasmas, Experiments and Modelling
Angioni, Clemente
2014-10-01
The physics of heavy impurity transport in tokamak plasmas plays an essential role towards the achievement of practical fusion energy. Reliable predictions of the behavior of these impurities require the development of realistic theoretical models and a complete understanding of present experiments, against which models can be validated. Recent experimental campaigns at JET with the ITER-like wall, with a W divertor, provide an extremely interesting and relevant opportunity to perform this combined experimental and theoretical research. Theoretical models of both neoclassical and turbulent transport must consistently include the impact of any poloidal asymmetry of the W density to enable quantitative predictions of the 2D W density distribution over the poloidal cross section. The agreement between theoretical predictions and experimentally reconstructed 2D W densities allows the identification of the main mechanisms which govern W transport in the core of JET H-mode plasmas. Neoclassical transport is largely enhanced by centrifugal effects and the neoclassical convection dominates, leading to central accumulation in the presence of central peaking of the density profiles and insufficiently peaked ion temperature profiles. The strength of the neoclassical temperature screening is affected by poloidal asymmetries. Only around mid-radius, turbulent diffusion offsets neoclassical transport. Consistently with observations in other devices, ion cyclotron resonance heating in the plasma center can flatten the electron density profile and peak the ion temperature profile and provide a means to reverse the neoclassical convection. MHD activity may hamper or speed up the accumulation process depending on mode number and plasma conditions. Finally, the relationship of JET results to a parallel modelling activity of the W behavior in the core of ASDEX Upgrade plasmas is presented. This project has received funding from the European Union's Horizon 2020 research and innovation
International Nuclear Information System (INIS)
Tourniaire, B. . E-mail bruno.tourniaire@cea.fr
2006-01-01
The prediction of heat transfer between corium pool and concrete basemat is of particular significance in the framework of the study of PWR's severe accident. Heat transfer directly governs the ablation velocity of concrete in case of molten core concrete interaction (MCCI) and, consequently, the time delay when the reactor cavity may fail. From a restricted hydrodynamic point of view, this issue is related to heat transfer between a heated bubbling pool and a porous wall with gas injection. Several experimental studies have been performed with simulant materials and many correlations have been provided to address this issue. The comparisons of the results of these correlations with the measurements and their extrapolation to reactor materials show that strong discrepancies between the results of these models are obtained which probably means that some phenomena are not well taken into account. The main purpose of this paper is to present an alternative heat transfer model which was originally developed for chemical engineering applications (bubble columns) by Deckwer. A part of this work is devoted to the presentation of this model, which is based on a surface renewal assumption. Comparison of the results of this model with available experimental data in different systems are presented and discussed. These comparisons clearly show that this model can be used to deal with the particular problem of MCCI. The analyses also lead to enrich the original model by taking into account the thermal resistance of the wall: a new formulation of the Deckwer's correlation is finally proposed
Shapiro and parametric resonances in coupled Josephson junctions
International Nuclear Information System (INIS)
Gaafar, Ma A; Shukrinov, Yu M; Foda, A
2012-01-01
The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We compare the current-voltage characteristics for a stack of coupled Josephson junctions under external irradiation calculated in the framework of CCJJ and CCJJ+DC models.
Stohlmann, Micah; Maiorca, Cathrine; Olson, Travis A.
2015-01-01
Mathematical modeling is an essential integrated piece of the Common Core State Standards. However, researchers have shown that mathematical modeling activities can be difficult for teachers to implement. Teachers are more likely to implement mathematical modeling activities if they have their own successful experiences with such activities. This…
Ohuchida, Satoshi; Endoh, Tetsuo
2018-06-01
In this paper, we propose a new model of inter-cell interference phenomenon in a 10 nm magnetic tunnel junction with perpendicular anisotropy (p-MTJ) array and investigated the interference effect between a program cell and unselected cells due to the oscillatory stray field from neighboring cells by Landau–Lifshitz–Gilbert micromagnetic simulation. We found that interference brings about a switching delay in a program cell and excitation of magnetization precession in unselected cells even when no programing current passes through. The origin of interference is ferromagnetic resonance between neighboring cells. During the interference period, the precession frequency of the program cell is 20.8 GHz, which synchronizes with that of the theoretical precession frequency f = γH eff in unselected cells. The disturbance strength of unselected cells decreased to be inversely proportional to the cube of the distance from the program cell, which is in good agreement with the dependence of stray field on the distance from the program cell calculated by the dipole approximation method.
An Iron-Rain Model for Core Formation on Asteroid 4 Vesta
Kiefer, Walter S.; Mittlefehldt, David W.
2016-01-01
Asteroid 4 Vesta is differentiated into a crust, mantle, and core, as demonstrated by studies of the eucrite and diogenite meteorites and by data from NASA's Dawn spacecraft. Most models for the differentiation and thermal evolution of Vesta assume that the metal phase completely melts within 20 degrees of the eutectic temperature, well before the onset of silicate melting. In such a model, core formation initially happens by Darcy flow, but this is an inefficient process for liquid metal and solid silicate. However, the likely chemical composition of Vesta, similar to H chondrites with perhaps some CM or CV chondrite, has 13-16 weight percent S. For such compositions, metal-sulfide melting will not be complete until a temperature of at least 1350 degrees Centigrade. The silicate solidus for Vesta's composition is between 1100 and 1150 degrees Centigrade, and thus metal and silicate melting must have substantially overlapped in time on Vesta. In this chemically and physically more likely view of Vesta's evolution, metal sulfide drops will sink by Stokes flow through the partially molten silicate magma ocean in a process that can be envisioned as "iron rain". Measurements of eucrites show that moderately siderophile elements such as Ni, Mo, and W reached chemical equilibrium between the metal and silicate phases, which is an important test for any Vesta differentiation model. The equilibration time is a function of the initial metal grain size, which we take to be 25-45 microns based on recent measurements of H6 chondrites. For these sizes and reasonable silicate magma viscosities, equilibration occurs after a fall distance of just a few meters through the magma ocean. Although metal drops may grow in size by merger with other drops, which increases their settling velocities and decreases the total core formation time, the short equilibration distance ensures that the moderately siderophile elements will reach chemical equilibrium between metal and silicate before
In-medium no-core shell model for ab initio nuclear structure calculations
International Nuclear Information System (INIS)
Gebrerufael, Eskendr
2017-01-01
In this work, we merge two successful ab initio nuclear-structure methods, the no-core shell model (NCSM) and the multi-reference in-medium similarity renormalization group (IM-SRG), to define a novel many-body approach for the comprehensive description of ground and excited states of closed- and open-shell medium-mass nuclei. Building on the key advantages of the two methods - the decoupling of excitations at the many-body level in the IM-SRG, and the exact diagonalization in the NCSM applicable up to medium-light nuclei - their combination enables fully converged no-core calculations for an unprecedented range of nuclei and observables at moderate computational cost. The efficiency and rapid model-space convergence of the new approach make it ideally suited for ab initio studies of ground and low-lying excited states of nuclei up to the medium-mass regime. Interactions constructed within the framework of chiral effective field theory provide an excellent opportunity to describe properties of nuclei from first principles, i.e., rooted in quantum chromodynamics, they overcome the lack of predictive power of phenomenological potentials. The hard core of these interactions causes strong short-range correlations, which we soften by using the similarity-renormalization-group transformation that accelerates the model-space convergence of many-body calculations. Three-nucleon effects, which are mandatory for the correct description of bulk properties of nuclei, are included in our calculations by using the normal-ordered two-body approximation, which has been shown to be sufficient to capture the main effects of the three-nucleon interaction. Using these interactions, we analyze energies of ground and excited states in the carbon and oxygen isotopic chains, where conventional NCSM calculations are still feasible and provide an important benchmark. Furthermore, we study the Hoyle state in 12 C - a three-alpha cluster state that cannot be converged in standard NCSM
Schmitz, Oliver; de Jong, Kor; Karssenberg, Derek
2017-04-01
There is an increasing demand to run environmental models on a big scale: simulations over large areas at high resolution. The heterogeneity of available computing hardware such as multi-core CPUs, GPUs or supercomputer potentially provides significant computing power to fulfil this demand. However, this requires detailed knowledge of the underlying hardware, parallel algorithm design and the implementation thereof in an efficient system programming language. Domain scientists such as hydrologists or ecologists often lack this specific software engineering knowledge, their emphasis is (and should be) on exploratory building and analysis of simulation models. As a result, models constructed by domain specialists mostly do not take full advantage of the available hardware. A promising solution is to separate the model building activity from software engineering by offering domain specialists a model building framework with pre-programmed building blocks that they combine to construct a model. The model building framework, consequently, needs to have built-in capabilities to make full usage of the available hardware. Developing such a framework providing understandable code for domain scientists and being runtime efficient at the same time poses several challenges on developers of such a framework. For example, optimisations can be performed on individual operations or the whole model, or tasks need to be generated for a well-balanced execution without explicitly knowing the complexity of the domain problem provided by the modeller. Ideally, a modelling framework supports the optimal use of available hardware whichsoever combination of model building blocks scientists use. We demonstrate our ongoing work on developing parallel algorithms for spatio-temporal modelling and demonstrate 1) PCRaster, an environmental software framework (http://www.pcraster.eu) providing spatio-temporal model building blocks and 2) parallelisation of about 50 of these building blocks using
International Nuclear Information System (INIS)
Hamasaki, K.; Yoshida, K.; Irie, F.; Enpuku, K.
1982-01-01
The microwave response of the dc quasiparticle tunneling current in Josephson tunnel junctions, where the Josephson current is suppressed by an external magnetic field, has been studied quantitatively in order to clarify its characteristics as a probe for the measurement of the junction capacitance. Extensive experiments for both small and long junctions are carried out for distinguishing between microwave behaviors of lumped and distributed constant junctions. It is shown that the observed voltage dependence of the dc quasiparticle tunneling current modified by an applied rf field is in good agreement with a theoretical result which takes into account the influence of the microwave circuit connected to the junction. The comparison between theory and experiment gives the magnitude of the internal rf field in the junction. Together with the applied rf field, this internal rf field leads to the junction rf impedance which is dominated by the junction capacitance in our experimental condition. In the case of lumped junctions, this experimental rf impedance is in reasonable agreement with the theoretical one with the junction capacitance estimated from the Fiske step of the distributed junction fabricated on the same substrate; the obtained ratio of the experimental impedance to the theoretical one is approximately 0.6--1.7. In the case of distributed junctions, however, experimental values of their characteristic impedances are approximately 0.2--0.3 of theoretical values calculated by assuming the one-dimensional junction model and taking account of the standing-wave effect in the junction
Energy Technology Data Exchange (ETDEWEB)
Carette, Diane [INSERM U 1065, Team 5 “Physiopathology of Germ Cell Control: Genomic and Non Genomic Mechanisms” C3M, University of Nice Sophia Antipolis, Nice (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Perrard, Marie-Hélène, E-mail: marie-helene.durand@ens-lyon.fr [Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon I, CNRS, INRA, Ecole Normale Supérieure de Lyon, Lyon (France); Prisant, Nadia [University of Versailles/St Quentin-en-Yvelines (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (Fra