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1

Scission-point model of nuclear fission based on deformed-shell effects  

Microsoft Academic Search

A static model of nuclear fission is proposed based on the assumption of statistical equilibrium among collective degrees of freedom at the scission point. The relative probabilities of formation of complementary fission fragment pairs are determined from the relative potential energies of a system of two nearly touching, coaxial spheroids with quadrupole deformations. The total potential energy of the system

B. D. Wilkins; E. P. Steinberg; R. R. Chasman

1976-01-01

2

Nonuniform character of the population of spin projections K for a fissile nucleus at the scission point and anisotropies in the angular distributions of fragments originating from the induced fission of nuclei  

SciTech Connect

It is shown that the emergence of anisotropies in the angular distributions of fragments originating from the spontaneous and induced fission of oriented actinide nuclei is possible only if nonuniformities in the population of the projectionsM (K) of the fissile-nucleus spin onto the z axis of the laboratory frame (fissile-nucleus symmetry axis) appear simultaneously in the vicinity of the scission point but not in the vicinity of the outer saddle point of the deformation potential. The possibilities for creating the orientation of fissile nuclei for spontaneous and induced fission and the effect of these orientations on the anisotropies under analysis are considered. The role of Coriolis interaction as a unique source of the mixing of different-K fissile-nucleus states at all stages of the fission process is studied with allowance for the dynamical enhancement of this interaction for excited thermalized states of the nucleus involved that is characterized by a high energy density. It is shown that the absence of thermalization of excited states of the fissile nucleus that appear because of the effect of nonadiabaticity of its collective deformation motion in the vicinity of the scission point is a condition of conservation of the influence that transition fission states formed at the inner and outer fission barriers exerts on the distribution of the spin projections K for lowenergy spontaneous nuclear fission. It is confirmed that anisotropies observed in the angular distributions of fragments originating from the fission of nuclei that is induced by fast light particles (multiply charged ions) are due to the appearance of strongly excited equilibrium(nonequilibrium) states of the fissile nucleus in the vicinity of its scission point that have a Gibbs (non-Gibbs) distribution of projections K.

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru [Voronezh State University (Russian Federation); Bunakov, V. E. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation); Kadmensky, S. S. [Voronezh State University (Russian Federation)

2012-11-15

3

Nonuniform character of the population of spin projections K for a fissile nucleus at the scission point and anisotropies in the angular distributions of fragments originating from the induced fission of nuclei  

NASA Astrophysics Data System (ADS)

It is shown that the emergence of anisotropies in the angular distributions of fragments originating from the spontaneous and induced fission of oriented actinide nuclei is possible only if nonuniformities in the population of the projections M ( K) of the fissile-nucleus spin onto the z axis of the laboratory frame (fissile-nucleus symmetry axis) appear simultaneously in the vicinity of the scission point but not in the vicinity of the outer saddle point of the deformation potential. The possibilities for creating the orientation of fissile nuclei for spontaneous and induced fission and the effect of these orientations on the anisotropies under analysis are considered. The role of Coriolis interaction as a unique source of the mixing of different- K fissile-nucleus states at all stages of the fission process is studied with allowance for the dynamical enhancement of this interaction for excited thermalized states of the nucleus involved that is characterized by a high energy density. It is shown that the absence of thermalization of excited states of the fissile nucleus that appear because of the effect of nonadiabaticity of its collective deformation motion in the vicinity of the scission point is a condition of conservation of the influence that transition fission states formed at the inner and outer fission barriers exerts on the distribution of the spin projections K for lowenergy spontaneous nuclear fission. It is confirmed that anisotropies observed in the angular distributions of fragments originating from the fission of nuclei that is induced by fast light particles (multiply charged ions) are due to the appearance of strongly excited equilibrium(nonequilibrium) states of the fissile nucleus in the vicinity of its scission point that have a Gibbs (non-Gibbs) distribution of projections K.

Kadmensky, S. G.; Bunakov, V. E.; Kadmensky, S. S.

2012-11-01

4

Statistical prescission point model of fission fragment angular distributions  

NASA Astrophysics Data System (ADS)

In light of recent developments in fission studies such as slow saddle to scission motion and spin equilibration near the scission point, the theory of fission fragment angular distribution is examined and a new statistical prescission point model is developed. The conditional equilibrium of the collective angular bearing modes at the prescission point, which is guided mainly by their relaxation times and population probabilities, is taken into account in the present model. The present model gives a consistent description of the fragment angular and spin distributions for a wide variety of heavy and light ion induced fission reactions.

John, Bency; Kataria, S. K.

1998-03-01

5

Clustering Effects Within the Dinuclear Model  

NASA Astrophysics Data System (ADS)

The clustering of two nuclei in a nuclear system creates configurations denoted in literature as nuclear molecular structures. A nuclear molecule or a dinuclear system (DNS) as named by Volkov consists of two touching nuclei (clusters) which keep their individuality. Such a system has two main degrees of freedom of collective motions which govern its dynamics: (i) the relative motion between the clusters leading to molecular resonances in the internuclear potential and to the decay of the dinuclear system (separation of the clusters) which is called quasifission since no compound system like in fission is first formed. (ii) the transfer of nucleons or light constituents between the two clusters of the dinuclear system leading to a special dynamics of the mass and charge asymmetries between the clusters in fusion and fission reactions. In this article we discuss the essential aspects of the diabatic internuclear potential used by the di-nuclear system concept and present applications to nuclear structure and reactions. We show applications of the dinuclear model to superdeformed and hyperdeformed bands. An extended discussion is given to the problems of fusion dynamics in the production of superheavy nuclei, to the quasifission process and to multi-nucleon transfer between nuclei. Also the binary and ternary fission processes are discussed within the scission-point model and the dinuclear system concept.

Adamian, Gurgen; Antonenko, Nikolai; Scheid, Werner

6

Consistent theoretical model for the description of the neutron-rich fission product yields  

NASA Astrophysics Data System (ADS)

The consistent model for the description of the independent fission product formation cross-section at light projectile energies up to about 100MeV is described. Pre-compound nucleon emission is described in the framework of the two-component exciton model using the Monte Carlo method, which allows one to incorporate a time duration criterion for the pre-equilibrium stage of the reaction. The decay of the excited compound nuclei, formed after the pre-equilibrium neutron and proton emission, is treated within the time-dependent statistical model with the inclusion of the main dynamical effects of nuclear friction on the fission width and saddle-to-scission descent time. For each member of the compound nucleus ensemble at scission point, the primary fragment isobaric chain yields are calculated using the multimodal approach with the inclusion two superasymmetric fission modes. The charge distribution of the primary fragment isobaric chains was considered as a results of frozen quantal fluctuations of the isovector nuclear matter density at the finite scission neck radius. The calculated fission product formation cross-sections in the neutron, proton, and ? -rays induced fission of the heavy actinides are presented.

Rubchenya, V. A.; Äystö, J.

2012-04-01

7

Application of a temperature-dependent liquid-drop model to dynamical Langevin calculations of fission-fragment distributions of excited nuclei  

NASA Astrophysics Data System (ADS)

A stochastic approach to fission dynamics based on three-dimensional Langevin equations was applied to calculation of the mass-energy and angular distributions of fission fragments. The dependence of the mass-energy distribution parameters on the angular momentum and the anisotropy of the fission-fragment angular distribution on excitation energy have been studied in a wide range of the fissility parameter. A temperature-dependent finite-range liquid-drop model was used in a consistent way to calculate the functional of the Helmholtz free energy and level-density parameter. The modified one-body mechanism of nuclear dissipation (the so-called surface-plus-window dissipation) was used to determine the dissipative forces in Langevin equations. The evaporation of light prescission particles was taken into account on the basis of a statistical model combined with Langevin dynamics. The calculated parameters of the mass-energy distribution and their angular dependencies are in good quantitative agreement with the available experimental data at the value of the reduction coefficient of the contribution from the wall formula equal to 0.25. Analysis of the anisotropy of the fission-fragment angular distribution performed with the saddle-point transition state model and scission-point transition state model indicates that it is necessary to take into account the dynamical aspects of the fission-fragment angular distribution formation.

Ryabov, E. G.; Karpov, A. V.; Nadtochy, P. N.; Adeev, G. D.

2008-10-01

8

Systematic Analysis of Structural Effects in Fission-Product Yields and Neutron Data and the Consequences for Our Understanding of the Fission Process and the Predictive Power of Model Predictions  

NASA Astrophysics Data System (ADS)

Structural effects in fission-product yields and neutron data for a large number of fissioning nuclei between 220Th and 256Fm from spontaneous fission to 14-MeV-neutron-induced fission have been used to deduce information on the properties of the fissioning systems. Macroscopic properties are attributed to the compound nucleus, while fission channels are ascribed to shells in the nascent fragments. Using a recent general empirical description of the nuclear level density and assuming different characteristic time scales for the collective degrees of freedom of the fissioning system, a new fission model has been developed. The model combines the statistical concept of the scission-point model of Wilkins et al. with empirically determined properties of the potential-energy surface and some characteristic dynamical freeze-out times. Although no fine tuning of the parameters has yet been performed, the model reproduces all measured fission yields and neutron data rather well with a unique set and a relatively small number of free parameters. Since the parameters of the model are closely related to physical properties of the systems, some interesting conclusions on the fission process can be deduced. Prospects for the predictive power of this semi-empirical approach for hitherto unknown fissioning systems are discussed.

Schmidt, K.-H.; Jurado, B.

2011-10-01

9

Fission fragment mass distribution for nuclei in the r-process region  

SciTech Connect

The fission fragment mass distribution is estimated theoretically on about 2000 nuclides which might have a critical role on the r-process nucleosynthesis through fission (Z>85). The mass distribution of fission fragment is derived by considering the location and the depth of valleys of potential energy surface near scission point of nuclei calculated by means of the liquid drop model with the shell energy correction by the Two-Center shell model. The guiding principle of determining the fission mass asymmetry is the behavior of the fission paths from the saddle to the scission point given by the Langevin calculation.

Tatsuda, S.; Hashizume, K.; Wada, T.; Ohta, M. [Department of Physics, Konan University, 8-9-1 Okamoto, Kobe 658-8501 (Japan); Sumiyoshi, K. [Numazu College of Technology, NAO (Japan); Otsuki, K. [Univ. of Chicago (United States); Kajino, T. [NAO, GUSA, Univ. of Tokyo (Japan); Koura, H.; Chiba, S. [JAEA (Japan); Aritomo, Y. [FLNR (JINR) (United States)

2007-02-26

10

Fission Yield Predictions with TALYS  

SciTech Connect

The nuclear model code TALYS has been extended to enable the prediction of fission yields. The mass yield curves are extracted from temperature-dependent multi-modal random-neck rupture calculations. Charge yields of the fission fragment are determined using the scission-point model and subsequently folded with the mass yields. We present a comparison of several fission-fragment mass yields and isotopic yields with experimental data.

Duijvestijn, M.C.; Koning, A.J. [Nuclear Research and Consultancy Group NRG, P.O. Box 25, NL-1755 ZG Petten (Netherlands)

2005-05-24

11

Energy partition in nuclear fission  

Microsoft Academic Search

A scission point model (two spheroid model TSM) including semi-empirical, temperature-dependent shell correction energies for deformed fragments at scission is presented. It has been used to describe the mass-asymmetry-dependent partition of the total energy release on both fragments from spontaneous and induced fission. Characteristic trends of experimental fragment energy and neutron multiplicity data as function of incidence energy in the

A. Ruben; H. Märten; D. Seeliger

1991-01-01

12

Interplay between theory and experiment for fission-fragment angular distributions from nuclei near the limits of stability  

Microsoft Academic Search

We examine the application of transition-state theory for fission-fragment angular distributions to composite nuclei near the limits of stability. The possible roles of saddle-point and scission-point configurations are explored. For many heavy-ion reactions that involve large angular momenta, the observed anisotropies are between the predictions of the saddle-point and scisson--point models. Empirical correlations are shown between the effective moments of

R. Freifelder; M. Prakash; John M. Alexander

1986-01-01

13

Modeling  

SciTech Connect

Slurry flows occur in many circumstances, including chemical manufacturing processes, pipeline transfer of coal, sand, and minerals; mud flows; and disposal of dredged materials. In this section we discuss slurry flow applications related to radioactive waste management. The Hanford tank waste solids and interstitial liquids will be mixed to form a slurry so it can be pumped out for retrieval and treatment. The waste is very complex chemically and physically. The ARIEL code is used to model the chemical interactions and fluid dynamics of the waste.

Loth, E.; Tryggvason, G.; Tsuji, Y.; Elghobashi, S. E.; Crowe, Clayton T.; Berlemont, A.; Reeks, M.; Simonin, O.; Frank, Th; Onishi, Yasuo; Van Wachem, B.

2005-09-01

14

Cluster aspects of binary fission  

NASA Astrophysics Data System (ADS)

With the improved scission-point model the mass distributions are calculated for induced fission of different Hg isotopes with even mass numbers A =180, 184, 188, 192, 196, 198. The calculated mass distribution and mean total kinetic energy of fission fragments are in a good agreement with the existing experimental data. The change in the shape of the mass distribution from asymmetric to more symmetric is revealed with increasing A of the fissioning AHg nucleus, and the reactions are proposed to verify this prediction experimentally.

Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.

2013-04-01

15

Preformation probabilities for light ternary particles in the cold (neutronless) fission of {sup 252}Cf  

SciTech Connect

The preformation amplitudes for {alpha} and {sup 10}Be clusters in the cold ternary fission of {sup 252}Cf are estimated within a microscopic model starting from single particle spherical Woods-Saxon wave functions and with a large space BCS-type configuration mixing. The resulting position of the maximum of cluster preformation probability is situated in the region between the two heavier fragments near the scission point, and approaches the fission axis as the distance between the fragments increases. (c) 2000 The American Physical Society.

Florescu, A. [National Institute for Physics and Nuclear Engineering, Bucharest, P.O. Box MG-6, (Romania); Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Sandulescu, A. [National Institute for Physics and Nuclear Engineering, Bucharest, P.O. Box MG-6, (Romania); Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Institut fuer Theoretische Physik der J. W. Goethe Universitaet, D-60054, Frankfurt am Main, (Germany); Delion, D. S. [National Institute for Physics and Nuclear Engineering, Bucharest, P.O. Box MG-6, (Romania); Hamilton, J. H. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Ramayya, A. V. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Greiner, W. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2000-05-01

16

Prompt fission neutron emission in neutron and proton induced reactions at intermediate energies  

SciTech Connect

The generalized model for the description of the prompt fission neutron spectra and multiplicities at neutron and proton energies up to about 100 MeV is described. The three main emission mechanisms considered are the precompound emission, the pre-scission particle evaporation before the saddle point and at descent to the scission point, and the emission from excited fission fragments. The two-component exciton model is used for the description of the preequilibrium stage of the reaction. The time-dependent statistical model with inclusion of the nuclear friction effects describes particle evaporation starting just after the precompound emission stage and lasting for the duration of the evolution of the compound nucleus toward scission. The fragment mass distribution and fission fragment kinetic and excitation energies are determined from the properties of the composite system at the scission point. The particle spectra from the fission fragments are calculated within the statistical approach. These spectra are then transformed into the laboratory rest frame using the calculated fragment kinetic energies and are averaged over the calculated fragment mass distributions. The model was applied to analyze the prompt fission neutron characteristics in the proton and neutron induced fission of actinide nuclei, and comparisons with the experimental data in {sup 238}U(n,f), {sup 238}U(p,f), and {sup 242}Pu(p,f) reactions are presented.

Rubchenya, V. A. [Department of Physics, University of Jyvaeskylae, FIN-40014, Jyvaeskylae, Finland and V. G. Khlopin Radium Institute, RU-194021 St. Petersburg (Russian Federation)

2007-05-15

17

{sup 35}Cl+{sup 12}C asymmetrical fission excitation functions  

SciTech Connect

The fully energy-damped yields from the {sup 35}Cl+{sup 12}C reaction have been systematically investigated using particle-particle coincidence techniques at a {sup 35}Cl bombarding energy of {approximately}8 MeV/nucleon. The fragment-fragment correlation data show that the majority of events arises from a binary-decay process with rather large numbers of secondary light-charged particles emitted from the two excited exit fragments. No evidence is observed for ternary break-up events. The binary-process results of the present measurement, along with those of earlier, inclusive experimental data obtained at several lower bombarding energies are compared with predictions of two different kinds of statistical model calculations. These calculations are performed using the transition-state formalism and the extended Hauser-Feshbach method and are based on the available phase space at the saddle point and scission point of the compound nucleus, respectively. The methods give comparable predictions and are both in good agreement with the experimental results thus confirming the fusion-fission origin of the fully damped yields. The similarity of the predictions for the two models supports the claim that the scission point configuration is very close to that of the saddle point for the light {sup 47}V compound system. The results also give further support for the specific mass-asymmetry-dependent fission barriers needed in the transition-state calculation. {copyright} {ital 1996 The American Physical Society.}

Beck, C.; Mahboub, D.; Nouicer, R.; Matsuse, T.; Djerroud, B.; Freeman, R.M.; Haas, F.; Hachem, A.; Morsad, A.; Youlal, M. [Centre de Recherches Nucleaires, Institut National de Physique Nucleaire et de Physique des Particules--Centre National de la Recherche Scientifique/Universite Louis Pasteur, B.P.28, F-67037 Strasbourg Cedex 2 (France); Sanders, S.J. [Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045 (United States); Dayras, R.; Wieleczko, J.P.; Berthoumieux, E.; Legrain, R.; Pollacco, E. [DAPNIA/SPhN, C.E. Saclay, F-91191 Gif sur Yvette Cedex (France); Cavallaro, S.; De Filippo, E.; Lanzano, G.; Pagano, A.; Sperduto, M.L. [Dipartimento di Fisica dell`Universita di Catania, INFN and LNS Catania, I-95129 Catania (Italy)

1996-07-01

18

High energy ? rays from 252Cf spontaneous fission  

NASA Astrophysics Data System (ADS)

The spontaneous fission decay of 252Cf has been analyzed in a statistical model with emphasis on describing recently reported high energy ?-ray spectra. An enhanced ? emission in the range from 3 to 10 MeV which is observed for nearly symmetric mass splits is readily understood as a result of the different fragment excitation energies. The model includes a viscous motion to the scission point with the possibility of prescission ? emission. It was found that even with saddle-to-scission times of ?sc<66×10-19 s, the maximum consistent with prescission neutron multiplicities, prescission ? rays are overwhelmed by fragment ? rays. Thus, the recently reported strong angular anisotropy of ? rays in the range E?=8-12 MeV is unexplained within the present understanding of the fission process.

Hofman, D. J.; Back, B. B.; Montoya, C. P.; Schadmand, S.; Varma, R.; Paul, P.

1993-03-01

19

Comparative study of the fragments' mass and energy characteristics in the spontaneous fussion of 238Pu, 240Pu and 242Pu and in the thermal-neutron-induced fission of 239Pu  

NASA Astrophysics Data System (ADS)

The energy and mass distribution and their correlations have been studied for the spontaneous fission of 238, 240, 242Pu and for the thermal-neutron-induced fission of 239Pu. A comparison of 240Pu(s.f.) and 239Pu(nth,f) shows that the increase in excitation energy mainly results in an increase of the intrinsic excitation energy. A comparison of the results for 238Pu, 240Pu and 242Pu(s.f.) demonstrates the occurence of different fission modes with varying relative probability. These results are discussed in terms of the scission point model as well as in terms of the fission channel model with random neck-rupture.

Schillebeeckx, P.; Wagemans, C.; Deruytter, A. J.; Barthélémy, R.

1992-08-01

20

Role of deformed shell effects on the mass asymmetry in nuclear fission of mercury isotopes  

NASA Astrophysics Data System (ADS)

Until now, the mass asymmetry in the nuclear fission process has been understood in terms of the strong influence of the nuclear structure of the nascent fragments. Recently, a surprising asymmetric fission has been discovered in the light mercury region and has been interpreted as the result of the influence of the nuclear structure of the parent nucleus, totally discarding the influence of the fragments' structure. To assess the role of the fragment shell effects in the mass asymmetry in this particular region, a scission-point model, based on a full energy balance between the two nascent fragments, has been developed using one of the best theoretical descriptions of microscopic nuclear structure. As for actinides, this approach shows that the asymmetric splitting of the 180Hg nucleus and the symmetric one of 198Hg can be understood on the basis of only the microscopic nuclear structure of the fragments at scission.

Panebianco, Stefano; Sida, Jean-Luc; Goutte, Héloise; Lemaître, Jean-François; Dubray, Noël; Hilaire, Stéphane

2012-12-01

21

Asymmetrical fission and statistical emission of complex fragments from the highly excited {sup 47}V compound nucleus  

SciTech Connect

The properties of the fully damped (deep-inelastic and orbiting) and fusion (evaporation and fission) processes have been investigated in three entrance channels leading to the same {sup 47} V compound nucleus at high excitation energies. No entrance channel effect has been observed in either the evaporation residue or the fission-like yields in contrast to the {sup 28}Si + {sup 12}C and {sup 24}Mg + {sup 16}O reactions in which the orbiting process still persists. The asymmetrical elemental distributions of the fully energy relaxed fragments are well described by fusion-fission models based respectively on the scission point and saddle point pictures. Finally a general discussion of the competition between orbiting and fusion-fission mechanisms in light heavy-ion reactions is presented in the framework of their calculated available number of open channels.

Beck, C.; Djerroud, B.; Haas, F.; Freeman, R.M.; Hachem, A.; Heusch, B.; Morsad, A.; Vuillet-A-Crilles, M.; Youlal, M.; Abe, Y. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Dayras, R.; Wieleczko, J.P.; Legrain, R.; Pollaco, E. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France); Ray, A.; Shapira, D.; Campo, J.G.D.; Kim, H.J. [Oak Ridge National Lab., TN (United States); Cavallaro, S.; De Fillippo, E.; Lanzano, G.; Pagano, A.; Sperduto, M.L. [Istituto Nazionale di Fisica Nucleare, Catania (Italy); Matsuse, T. [Shinshu Univ., Matsumoto, Nagano (Japan); Sanders, S.J. [Kansas Univ., Lawrence, KS (United States)

1991-12-31

22

Asymmetrical fission and statistical emission of complex fragments from the highly excited sup 47 V compound nucleus  

SciTech Connect

The properties of the fully damped (deep-inelastic and orbiting) and fusion (evaporation and fission) processes have been investigated in three entrance channels leading to the same {sup 47} V compound nucleus at high excitation energies. No entrance channel effect has been observed in either the evaporation residue or the fission-like yields in contrast to the {sup 28}Si + {sup 12}C and {sup 24}Mg + {sup 16}O reactions in which the orbiting process still persists. The asymmetrical elemental distributions of the fully energy relaxed fragments are well described by fusion-fission models based respectively on the scission point and saddle point pictures. Finally a general discussion of the competition between orbiting and fusion-fission mechanisms in light heavy-ion reactions is presented in the framework of their calculated available number of open channels.

Beck, C.; Djerroud, B.; Haas, F.; Freeman, R.M.; Hachem, A.; Heusch, B.; Morsad, A.; Vuillet-A-Crilles, M.; Youlal, M.; Abe, Y. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires); Dayras, R.; Wieleczko, J.P.; Legrain, R.; Pollaco, E. (CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Ray, A.; Shapira, D.; Campo, J.G.D.; Kim, H.J. (Oak Ridge National Lab., TN (United States

1991-01-01

23

Structured Modeling and Model Management  

Microsoft Academic Search

\\u000a We discuss Geoffrion’s contribution to model management and the practice of modeling through his structured modeling formalism.\\u000a We review the trajectory of structured model management research, enumerating the contributions and limitations of both structured\\u000a modeling and model management in general. We summarize by suggesting how Geoffrion’s work could be leveraged to contribute\\u000a to a next generation of model management.

Daniel Dolk

24

Fair Model  

NSDL National Science Digital Library

The Fair model web site includes a freely available United States macroeconomic econometric model and a multicounty econometric model. The models run on the Windows OS. Instructors can use the models to teach forecasting, run policy experiments, and evaluate historical episodes of macroeconomic behavior. The web site includes extensive documentation for both models. The simulation is for upper-division economics courses in macroeconomics or econometrics. The principle developer is Ray Fair at Yale University.

Blecha, Betty

25

Toilet Model  

NSDL National Science Digital Library

In this activity, PVC pipe, plastic water bottles and vinyl tubing are used to make a simple working toilet model. The model shows the role of a siphon in the flushing of a toilet. Educators can pre-assemble this model and use it for demonstration purposes or engage learners in the model building process.

Rathjen, Don

2005-01-01

26

Understanding Models  

NSDL National Science Digital Library

Chapter 1 defines and discusses models in a broad, and perhaps unusual, way. In particular, the chapter stresses the framework of personal models that underlie science and learning across fields. Subsequent chapters will deal more with particular kinds of expressed models that are important in science and science teaching: physical models, analog models and plans, mathematical models, and computer simulations. Throughout, the book examines how all models are important to science, how they are used, and how to use them effectively. They can and should be used not only to teach science, but also to teach students something about the process of learning and about the nature of knowledge itself.

Ireton, Shirley W.; Gilbert, Steven W.

2003-01-01

27

Supermatrix models  

SciTech Connect

Radom matrix models based on an integral over supermatrices are proposed as a natural extension of bosonic matrix models. The subtle nature of superspace integration allows these models to have very different properties from the analogous bosonic models. Two choices of integration slice are investigated. One leads to a perturbative structure which is reminiscent of, and perhaps identical to, the usual Hermitian matrix models. Another leads to an eigenvalue reduction which can be described by a two component plasma in one dimension. A stationary point of the model is described.

Yost, S.A.

1991-05-01

28

ENTRAINMENT MODELS  

EPA Science Inventory

This presentation presented information on entrainment models. Entrainment models use entrainment hypotheses to express the continuity equation. The advantage is that plume boundaries are known. A major disadvantage is that the problems that can be solved are rather simple. The ...

29

Higgs models  

NASA Astrophysics Data System (ADS)

This lecture presented at the Baikal summer school on physics of elementary particles and astrophysics in 2011 is devoted to the Higgs mechanism of the electroweak symmetry breaking within the Standard Model and in some models beyond it.

Ivanov, I. P.

2012-12-01

30

Landscape Models  

NSDL National Science Digital Library

In this assignment students model different scenarios of landscape evolution using an on-line landscape evolution model. The assignment takes them through several situations involving changes in commonly modeled landscape variables like overland flow, faulting and uplift, erosivity, and drainage incision. At the end I have students devise a situation (of variables) that tests a hypothesis or the sensitivity of the model to changes in a variable. Designed for a geomorphology course Uses online and/or real-time data

Marchetti, David

31

Model Fundamentals  

NSDL National Science Digital Library

The module provides background information for the Characteristics of Operational NWP Models module (also in the NWP PDS), which contains current information about the characteristics and architecture of commonly used operational models, their operationally significant strengths and weaknesses, and model assessment tools. The subject matter expert for this module is Dr. Ralph Petersen of the National Centers for Environmental Prediction, Environmental Modeling Center (NCEP/EMC).

Spangler, Tim

1999-12-10

32

Model Completeness  

Microsoft Academic Search

\\u000a We already defined model completeness in Chapter 1: a theory T is called model complete if every embedding between models of T is elementary. We dealt with this notion also in Chapter 2, where we considered its connection with quantifier elimination\\u000a and completeness. But now we wish to examine model completeness in a closer and more direct way, to discuss

Annalisa Marcja; Carlo Toffalori

33

Better Models  

NSDL National Science Digital Library

At the end of the first chapter, you realized, hopefully, that the model of an atom that we have so far (Rutherford's model of a concentrated positive nucleus with negative charges around it) doesn't go very far in helping us explain observations. So, why not try to make that model better? This chapter shows you how it's done.

Robertson, William C.

2007-01-01

34

Thinkable models  

Microsoft Academic Search

A primary objective of technical education should be the development of thinkable models in the minds of students. Thinkable models are representations of things and processes simple enough that people can use them in thought experiments. The organization of cognitive structures for technical domains can be imagined to be a network of appropriately connected thinkable models. Artificial intelligence (AI), as

Robert W. Lawler

1996-01-01

35

Energizer Model  

NSDL National Science Digital Library

The EJS Energizer model explores the relationship between kinetic, potential, and total energy. Users create a potential energy curve and observe the resulting motion. The Energizer model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed.

Gallis, Michael R.

2008-10-27

36

Hydrological models are mediating models  

NASA Astrophysics Data System (ADS)

Despite the increasing role of models in hydrological research and decision-making processes, only few accounts of the nature and function of models exist in hydrology. Earlier considerations have traditionally been conducted while making a clear distinction between physically-based and conceptual models. A new philosophical account, primarily based on the fields of physics and economics, transcends classes of models and scientific disciplines by considering models as "mediators" between theory and observations. The core of this approach lies in identifying models as (1) being only partially dependent on theory and observations, (2) integrating non-deductive elements in their construction, and (3) carrying the role of instruments of scientific enquiry about both theory and the world. The applicability of this approach to hydrology is evaluated in the present article. Three widely used hydrological models, each showing a different degree of apparent physicality, are confronted to the main characteristics of the "mediating models" concept. We argue that irrespective of their kind, hydrological models depend on both theory and observations, rather than merely on one of these two domains. Their construction is additionally involving a large number of miscellaneous, external ingredients, such as past experiences, model objectives, knowledge and preferences of the modeller, as well as hardware and software resources. We show that hydrological models convey the role of instruments in scientific practice by mediating between theory and the world. It results from these considerations that the traditional distinction between physically-based and conceptual models is necessarily too simplistic and refers at best to the stage at which theory and observations are steering model construction. The large variety of ingredients involved in model construction would deserve closer attention, for being rarely explicitly presented in peer-reviewed literature. We believe that devoting more importance to identifying and communicating on the many factors involved in model development might increase transparency of model building.

Babel, L. V.; Karssenberg, D.

2013-08-01

37

Station Models  

NSDL National Science Digital Library

This project will allow users to become acquainted with station models that are found on weather maps. Students will study the various atmospheric variables that are depicted on a station model and then practice on an interactive station model program. Part 1 - Being able to read and interpret weather maps is a very important skill in meteorology. One of the most basic skills of predicting the weather is being able to interpret a station model of a given location. A station model is a bundle of information that ...

Ertl, Mr.

2007-11-03

38

Analytical models  

NASA Astrophysics Data System (ADS)

A system-level design and analysis model was developed. This model was conceived to have several key elements: a solar pond thermodynamic performance model, a power generation subsystem model, and an economic analysis element. The basic approach was to create these elements or modules and refine them on an individual basis yet retain the capability to easily couple them into a full system design model. This building block approach allows for maximum flexibility and substitution of refined descriptions as the technology develops. A general overview of interconnecting these subsystem models is presented. The primary program control element will perform the administrative functions of data input, data output, information storage and transfer, and sequential calling of the subsystem models. From the point of view of the requirements of a system design model, a power conversion subsystem model was developed. The goal of the effort was a preliminary subsystem model compatible with the solar pond subsystem model so that a first order system simulation analysis could be performed.

1984-09-01

39

ICRF modelling  

SciTech Connect

This lecture provides a survey of the methods used to model fast magnetosonic wave coupling, propagation, and absorption in tokamaks. The validity and limitations of three distinct types of modelling codes, which will be contrasted, include discrete models which utilize ray tracing techniques, approximate continuous field models based on a parabolic approximation of the wave equation, and full field models derived using finite difference techniques. Inclusion of mode conversion effects in these models and modification of the minority distribution function will also be discussed. The lecture will conclude with a presentation of time-dependent global transport simulations of ICRF-heated tokamak discharges obtained in conjunction with the ICRF modelling codes. 52 refs., 15 figs.

Phillips, C.K.

1985-12-01

40

Computer Models  

NSDL National Science Digital Library

This undergraduate meteorology tutorial from Texas A&M University focuses on computer models that are run by the National Weather Service (NWS) National Centers for Environmental Prediction (NCEP) and are used for forecasting day-to-day weather in the United States. NCEP has four basic models: the Eta Model, the Nested Grid model (NGM), the Rapid Update Cycle (RUC), and the Global Forecast System (GFS). Each model is a self-contained set of computer programs, which include means of analyzing data and computing the evolution of the atmosphere's winds, temperature, pressure, and moisture based on the analyses. Students are given some basic terminology and learn to identify the models and to read model output.

Nielsen-Gammon, John

1996-01-01

41

Modeling patterns for task models  

Microsoft Academic Search

Models allow us to describe complex systems at different abstract and conceptual levels, hence amplify our analytical and problem solving capabilities, However, a lot of human effort and experience is needed to build correct models, and to translate them to concrete artifacts: in our case a usable user interface. This paper introduces the concept of task and pattern models to

Ashraf Gaffar; Daniel Sinnig; Ahmed Seffah; Peter Forbrig

2004-01-01

42

Functions and Models: Mathematical Models  

NSDL National Science Digital Library

Describe the process of mathematical modeling;Name and describe some methods of modeling;Classify a symbolically represented function as one of the elementary algebraic or transcendental functions;Appraise the suitability of different models for interpreting a given set of data.

Freeze, Michael

2003-01-22

43

Ventilation Model  

SciTech Connect

The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future.

H. Yang

1999-11-04

44

Gimbal Model  

NSDL National Science Digital Library

The Gimbal Model illustrates the pitch, roll and yaw of a 3D object. Independent axis mode allows each axes to be rotated without affecting the others axes. If this mode is not selected, the model can be used to explore the phenomena of gimbal lock. This model tests the Java 3D implementation of the EJS 3D library. If the Java 3D option is selected, a airplane VMRL file (wrl) is rendered inside the gimbals. A warning message will appear if the Java 3D library is not available. The Gimbal Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ntnu_Gimbal.jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Hwang, Fu-Kwun; Wee, Loo K.

2011-12-30

45

Atmospheric Modeling  

Microsoft Academic Search

\\u000a Air quality models simulate the atmospheric concentrations and deposition fluxes to the Earth’s surface of air pollutants\\u000a by solving the mass conservation equations that represent the emissions, transport, dispersion, transformations and removal\\u000a of those air pollutants and associated chemical species. Contemporary air quality models can be grouped into two major categories:\\u000a (1) models that calculate the concentrations of air pollutants

Christian Seigneur; Robin Dennis

46

SCARP Model  

NSDL National Science Digital Library

SCARP is the first in a sequence of spreadsheet modeling exercises (SCARP2, LONGPRO, and GLACPRO). In this exercise, students use a simple arithmetic model (a running mean) to simulate the evolution of a scarp (escarpment) across time. Although the output closely resembles an evolving scarp, no real variables are included in the model. The purpose of the exercise, in addition to the simulation, is to develop basic skills in spreadsheeting and especially in graphical display.

Locke, Bill

47

Floodplain Modeling  

NSDL National Science Digital Library

Students explore the impact of changing river volumes and different floodplain terrain in experimental trials with table top-sized riverbed models. The models are made using modeling clay in an aluminum baking pans placed on a slight incline. Water added âupstreamâ at different flow rates and to different riverbed configurations simulates different potential flood conditions. Students study flood dynamics as they modify the riverbed with blockages or levees to simulate real-world scenarios.

Integrated Teaching And Learning Program

48

Model Cheking  

Microsoft Academic Search

Model checking is an automatic technique for verifying finite-state reactive systems, such as sequential circuit designs and\\u000a communication protocols. Specifications are expressed in temporal logic, and the reactive system is modeled as a statetransition\\u000a graph. An efficient search procedure is used to determine whether or not the state-transition graph satisfies the specifications.\\u000a \\u000a We describe the basic model checking algorithm and

Edmund M. Clarke

1997-01-01

49

Neurotransmission Model  

NSDL National Science Digital Library

This lesson allows students to apply engineering principles in the science classroom. Students learn how neurons convey information through designing and building a physical model of neurotransmission.

Dr. Janet M Dubinsky (University of Minnesota Neuroscience)

2011-07-20

50

PREDICTIVE MODELS  

SciTech Connect

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1) chemical flooding; 2) carbon dioxide miscible flooding; 3) in-situ combustion; 4) polymer flooding; and 5) steamflood. CFPM, the Chemical Flood Predictive Model, models micellar (surfactant)-polymer floods in reservoirs, which have been previously waterflooded to residual oil saturation. Thus, only true tertiary floods are considered. An option allows a rough estimate of oil recovery by caustic or caustic-polymer processes. CO2PM, the Carbon Dioxide miscible flooding Predictive Model, is applicable to both secondary (mobile oil) and tertiary (residual oil) floods, and to either continuous CO2 injection or water-alternating gas processes. ICPM, the In-situ Combustion Predictive Model, computes the recovery and profitability of an in-situ combustion project from generalized performance predictive algorithms. PFPM, the Polymer Flood Predictive Model, is switch-selectable for either polymer or waterflooding, and an option allows the calculation of the incremental oil recovery and economics of polymer relative to waterflooding. SFPM, the Steamflood Predictive Model, is applicable to the steam drive process, but not to cyclic steam injection (steam soak) processes. The IBM PC/AT version includes a plotting capability to produces a graphic picture of the predictive model results.

Ray, R.M. (DOE Bartlesville Energy Technology Center, Bartlesville, OK (United States))

1988-10-01

51

Model Volcanoes  

NSDL National Science Digital Library

In this lesson, students will explore volcanoes by constructing models and reflect upon their learning through drawing sketches of their models. Once they have finished making their models, they will experiment with making their volcanoes erupt. They will observe how eruption changes the original form of their volcano models. In this way, students see first hand how this type of phenomena creates physical change. While students at this level may struggle to understand larger and more abstract geographical concepts, they will work directly with material that will help them build a foundation for understanding concepts of phenomena that sculpt the earth.

52

Computational Models  

Cancer.gov

The models work by investigating relationships between the pathways that control a cell's response to inflammation, growth factors, DNA damage, and other events. The goal is to create a dynamic model of the biological processes related to cancer initiation, progression, and metastasis.

53

Probability Models  

NSDL National Science Digital Library

This site, presented by the Department of Statistics at Yale University, gives an explanation, a definition and an example of probability models. Topics include components of probability models and the basic rules of probability. Overall, this is a great resource for any mathematics classroom studying statistics.

Lacey, Michelle

2008-12-26

54

Modeling Daisyworld  

NSDL National Science Digital Library

Daisyworld is a classic model of complex feedbacks in a simple climate system; this activity guides students through the construction of a STELLA model that can be used to experiment with the system, exploring the somewhat surprising dynamics that arise from the interplay of positive and negative feedbacks between daisies and the temperature of their environment.

Bice, David

55

Budget Model.  

ERIC Educational Resources Information Center

|Computerized formula-driven budget models are used by the Washington community college system to define resource needs for legislative budget requests and to distribute legislative appropriations among 22 community college districts. This manual outlines the sources of information needed to operate the model and illustrates the principles on…

Washington State Board for Community Coll. Education, Olympia.

56

Daisyworld Model  

NSDL National Science Digital Library

The simulation exercise uses a STELLA-based model called Daisyworld to explore concepts associated with Earth's energy balance and climate change. Students examine the evolution of a simplified model of an imaginary planet with only two species of life on its surface -- white and black daisies -- with different albedos. The daisies can alter the temperature of the surface where they are growing.

Lovelock, James; Watson, Andrew; Bice, Dave; Dept. Of Geosciences, Penn S.

57

Partition models  

Microsoft Academic Search

Product partition models assume that observations in different components of a random partition of the data are independent given the partition. If the probability distribution of random partitions is in a certain product form prior to making the observations, it is also in product form given the observations. The product model thus provides a convenient machinery for allowing the data

J. A. Hartigan

1990-01-01

58

Thinkable Models.  

ERIC Educational Resources Information Center

Argues that the organization of cognitive structures for technical domains can be visualized as a network of connected thinkable models. Describes a taxonomy of models that has been developed and discusses the issue of how representations relate to human modes of perception and action. Contains 25 references. (DDR)

Lawler, Robert W.

1996-01-01

59

Molecular Modeling  

Microsoft Academic Search

Molecular modeling has trickled down from the realm of pharmaceutical and research laboratories into the realm of undergraduate chemistry instruction. It has opened avenues for the visualization of chemical concepts that previously were difficult or impossible to convey. I am sure that many of you have developed exercises using the various molecular modeling tools. It is the desire of this

Jon L. Holmes

1999-01-01

60

PREDICTIVE MODELS  

Microsoft Academic Search

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1) chemical flooding; 2) carbon dioxide miscible flooding; 3)

1988-01-01

61

PREDICTIVE MODELS  

Microsoft Academic Search

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1) chemical flooding, where soap-like surfactants are injected into

1986-01-01

62

Supernova models  

Microsoft Academic Search

Recent progress in understanding the observed properties of type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the Ni-56 produced therein is reviewed. The expected nucleosynthesis and gamma-line spectra for this model of type I explosions and a model for type II explosions are presented. Finally, a qualitatively new approach

S. E. Woosley; T. A. Weaver

1981-01-01

63

Model Execution  

SciTech Connect

A computer software-based model is typically designed to produce a trace of system evolution over time. The actual process of computing the model state and producing the state values as the simulation time is advanced is called model execution. Models could be designed with a specific execution technique in mind, or could be generally amenable to multiple different execution techniques. Two popular methods that are used to execute models are: time-stepped method and discrete-event method. Each of these methods could in turn be executed either sequentially (on a single processor), or in parallel (using multiple processors concurrently). In this chapter, we describe the time-stepped and discrete event execution methods and outline some of the common approaches to their sequential and parallel execution. Execution concepts common to the methods are described followed by implementation details of the methods.

Perumalla, Kalyan S [ORNL

2007-01-01

64

Nucleon models  

SciTech Connect

Theoretical models for the structure of the nucleons and the hyperons are constructed for the purpose of obtaining an understanding of the dynamics that gives rise to their complex spectra. The most modest goal is to explain the ground state energies and the corresponding static observables - magnetic moments and rms radii. More ambitious models attempt in addition to explain the dynamic observables as, e.g., the electromagnetic form factors, which requires that not only overall features are understood, but that at least some parts of the short-range dynamics are understood as well. The rich structure of the baryon spectrum, with 5 known successive flavor generations [the nucleons (up and down quarks), the strange, the charmed and the bottom hyperons] makes the construction of a realistic nucleon model a complex task. Naturally, if it were possible, one would like to take the Lagrangian density of quantum chromodynamics as the starting point. This is formed of quark and gluon field operators. While the mass scale of the baryons is 1 GeV, that of the light u and d quarks and the gluons is essentially 0 (m{sub u}{congruent} 5 MeV, m{sub d} {congruent} 8 MeV, m{sub gluon} = 0). That baryons with masses of the order of 1 GeV or more can be formed of such light constituents is a consequence of the very strong gluon exchange interaction at low energies. The topics covered in this report are: Chiral Symmetry; The Chiral Bag Model; Chiral Meson Theory; The Skyrmion; Currents and Form Factors; The Skyrme Model and the Chiral Bag Model; Extensions of the Model; Explicit Vector Meson Fields; The Hyperons; The Hyperon Spectrum; The Hyperon Magnetic Moments; Exotics; The Limits of the Bound State Model; and The End of the Nucleon Models.

Riska, D.O. [Univ. of Helsinki (Finland)

1996-12-31

65

Virtual models  

US Patent & Trademark Office Database

A method of generating a virtual model of an object, comprising the step of constructing a fused model to represent the variation of the shape of the object in a plurality of configurations. In the method, position variation vectors may be calculated which describe the variation of a plurality of points in the fused model from their mean positions over all the configurations of the object; the position variation vectors may be assigned a weighting factor which represents a measure of their probabilistic confidence; a weighted covariance matrix may be constructed to represent the variations; the weighted covariance matrix may be operated on to obtain shape variation vectors representing the weighted direction and magnitude of variations; such that the fused model may describe how the shape of the object varies as a function of the shape variation vectors scaled by a shape parameter.

Fisher, III; Robert Burns (Scotland, GB); Faber; Petko (Leonberg, DE); Lukins; Timothy Campbell (Scotland, GB)

2008-10-21

66

Programming models  

SciTech Connect

A programming model is a set of software technologies that support the expression of algorithms and provide applications with an abstract representation of the capabilities of the underlying hardware architecture. The primary goals are productivity, portability and performance.

Daniel, David J [Los Alamos National Laboratory; Mc Pherson, Allen [Los Alamos National Laboratory; Thorp, John R [Los Alamos National Laboratory; Barrett, Richard [SNL; Clay, Robert [SNL; De Supinski, Bronis [LLNL; Dube, Evi [LLNL; Heroux, Mike [SNL; Janssen, Curtis [SNL; Langer, Steve [LLNL; Laros, Jim [SNL

2011-01-14

67

Model Lungs.  

ERIC Educational Resources Information Center

A cheap and simple model that can be made and used by pupils to study the human breathing mechanism is presented. A list of needed materials, procedures for construction, possible refinements, and method of use are included. (KR)

Taylor, Emma

1991-01-01

68

Supernova models  

SciTech Connect

Recent progress in understanding the observed properties of type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the Ni-56 produced therein is reviewed. The expected nucleosynthesis and gamma-line spectra for this model of type I explosions and a model for type II explosions are presented. Finally, a qualitatively new approach to the problem of massive star death and type II supernovae based upon a combination of rotation and thermonuclear burning is discussed. While the theoretical results of existing models are predicated upon the assumption of a successful core bounce calculation and the neglect of such two-dimensional effects as rotation and magnetic fields the new model suggests an entirely different scenario in which a considerable portion of the energy carried by an equatorially ejected blob is deposited in the red giant envelope overlying the mantle of the star.

Woosley, S.E. (California, University, Santa Cruz; California, University, Livermore, CA); Weaver, T.A. (California, University, Livermore, CA)

1981-12-29

69

Energy Models  

EPA Science Inventory

Energy models characterize the energy system, its evolution, and its interactions with the broader economy. The energy system consists of primary resources, including both fossil fuels and renewables; power plants, refineries, and other technologies to process and convert these r...

70

Device modeling  

NASA Astrophysics Data System (ADS)

A summary report is given of the activities of the device modeling workshop which was held as a part of the Space Photovoltaic Research and Technology Conference at the Lewis Research Center, October 7 to 9, 1986. The purpose of this workshop was to access the status of solar cell device modeling to see if it is meeting present and future needs of the photovoltaic community.

Schwartz, Richard

1987-06-01

71

PREDICTIVE MODELS  

SciTech Connect

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1) chemical flooding, where soap-like surfactants are injected into the reservoir to wash out the oil; 2) carbon dioxide miscible flooding, where carbon dioxide mixes with the lighter hydrocarbons making the oil easier to displace; 3) in-situ combustion, which uses the heat from burning some of the underground oil to thin the product; 4) polymer flooding, where thick, cohesive material is pumped into a reservoir to push the oil through the underground rock; and 5) steamflood, where pressurized steam is injected underground to thin the oil. CFPM, the Chemical Flood Predictive Model, models micellar (surfactant)-polymer floods in reservoirs, which have been previously waterflooded to residual oil saturation. Thus, only true tertiary floods are considered. An option allows a rough estimate of oil recovery by caustic or caustic-polymer processes. CO2PM, the Carbon Dioxide miscible flooding Predictive Model, is applicable to both secondary (mobile oil) and tertiary (residual oil) floods, and to either continuous CO2 injection or water-alternating gas processes. ICPM, the In-situ Combustion Predictive Model, computes the recovery and profitability of an in-situ combustion project from generalized performance predictive algorithms. PFPM, the Polymer Flood Predictive Model, is switch-selectable for either polymer or waterflooding, and an option allows the calculation of the incremental oil recovery and economics of polymer relative to waterflooding. SFPM, the Steamflood Predictive Model, is applicable to the steam drive process, but not to cyclic steam injection (steam soak) processes.

Ray, R.M. (DOE Bartlesville Energy Technology Technology Center, Bartlesville, OK (United States))

1986-12-01

72

Supernova models  

Microsoft Academic Search

Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the ⁵⁶Ni produced therein is reviewed. Within the context of this model for Type I explosions and the 1978 model for Type II explosions, the expected nucleosynthesis and gamma-line spectra from both kinds

S. E. Woosley; T. A. Weaver

1980-01-01

73

Modeling life.  

PubMed

We seek to construct physical and mathematical models of life. Such models allow us to test our understanding of how living systems function and how they respond to human imposed stimuli. One system is a genomically and chemically complete model of a minimal cell. This cell is a hypothetical bacterium with the fewest number of genes possible. Such a minimal cell provides a platform to ask about the essential features of a living cell and forms a platform to investigate "synthetic biology." A second system is "Body-on-a-Chip" which is a microfabricated microfluidic system with cells or tissue constructs representing various organs in the body. It can be constructed from human or animal cells and used in drug discovery development. That model is a physical representation of a physiologically based pharmacokinetic model. Both the computer and the physical models provide insight into the underlying biology and provide new tools to make use of that understanding to provide benefits to society. PMID:22527010

Shuler, Michael L

2012-04-17

74

Do stroke models model stroke?  

PubMed Central

Stroke is one of the leading causes of death worldwide and the biggest reason for long-term disability. Basic research has formed the modern understanding of stroke pathophysiology, and has revealed important molecular, cellular and systemic mechanisms. However, despite decades of research, most translational stroke trials that aim to introduce basic research findings into clinical treatment strategies – most notably in the field of neuroprotection – have failed. Among other obstacles, poor methodological and statistical standards, negative publication bias, and incomplete preclinical testing have been proposed as ‘translational roadblocks’. In this article, we introduce the models commonly used in preclinical stroke research, discuss some of the causes of failed translational success and review potential remedies. We further introduce the concept of modeling ‘care’ of stroke patients, because current preclinical research models the disorder but does not model care or state-of-the-art clinical testing. Stringent statistical methods and controlled preclinical trials have been suggested to counteract weaknesses in preclinical research. We conclude that preclinical stroke research requires (1) appropriate modeling of the disorder, (2) appropriate modeling of the care of stroke patients and (3) an approach to preclinical testing that is similar to clinical testing, including Phase 3 randomized controlled preclinical trials as necessary additional steps before new therapies enter clinical testing.

Mergenthaler, Philipp; Meisel, Andreas

2012-01-01

75

Gnomon Model  

NSDL National Science Digital Library

The EJS Gnomon model simulates the shadow cast by a gnomon (the part of a sundial that casts the shadow) over the course of a day for any day of the year and any latitude on Earth. The program gives you the option to use mean Sun (which moves relative to the stars at a constant rate throughout the year) or true Sun (which varies its apparent speed relative to the background stars). The default is to use true Sun. The program also shows the observer's horizon plane on the spherical Earth, as well as the ecliptic and the apparent path of Sun. The Earth View can be set to let Earth rotate or remain fixed EJS Gnomon model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_Gnomon.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for astronomy are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Timberlake, Todd

2009-08-19

76

Mechanistic models  

SciTech Connect

Several models and theories are reviewed that incorporate the idea of radiation-induced lesions (repairable and/or irreparable) that can be related to molecular lesions in the DNA molecule. Usually the DNA double-strand or chromatin break is suggested as the critical lesion. In the models, the shoulder on the low-LET survival curve is hypothesized as being due to one (or more) of the following three mechanisms: (1) interaction'' of lesions produced by statistically independent particle tracks; (2) nonlinear (i.e., linear-quadratic) increase in the yield of initial lesions, and (3) saturation of repair processes at high dose. Comparisons are made between the various approaches. Several significant advances in model development are discussed; in particular, a description of the matrix formulation of the Markov versions of the RMR and LPL models is given. The more advanced theories have incorporated statistical fluctuations in various aspects of the energy-loss and lesion-formation process. An important direction is the inclusion of physical and chemical processes into the formulations by incorporating relevant track structure theory (Monte Carlo track simulations) and chemical reactions of radiation-induced radicals. At the biological end, identification of repair genes and how they operate as well as a better understanding of how DNA misjoinings lead to lethal chromosome aberrations are needed for appropriate inclusion into the theories. More effort is necessary to model the complex end point of radiation-induced carcinogenesis.

Curtis, S.B.

1990-09-01

77

Mechanistic models  

SciTech Connect

Several models and theories are reviewed that incorporate the idea of radiation-induced lesions (repairable and/or irreparable) that can be related to molecular lesions in the DNA molecule. Usually the DNA double-strand or chromatin break is suggested as the critical lesion. In the models, the shoulder on the low-LET survival curve is hypothesized as being due to one (or more) of the following three mechanisms: (1) ``interaction`` of lesions produced by statistically independent particle tracks; (2) nonlinear (i.e., linear-quadratic) increase in the yield of initial lesions, and (3) saturation of repair processes at high dose. Comparisons are made between the various approaches. Several significant advances in model development are discussed; in particular, a description of the matrix formulation of the Markov versions of the RMR and LPL models is given. The more advanced theories have incorporated statistical fluctuations in various aspects of the energy-loss and lesion-formation process. An important direction is the inclusion of physical and chemical processes into the formulations by incorporating relevant track structure theory (Monte Carlo track simulations) and chemical reactions of radiation-induced radicals. At the biological end, identification of repair genes and how they operate as well as a better understanding of how DNA misjoinings lead to lethal chromosome aberrations are needed for appropriate inclusion into the theories. More effort is necessary to model the complex end point of radiation-induced carcinogenesis.

Curtis, S.B.

1990-09-01

78

Micrometer Model  

NSDL National Science Digital Library

The Micrometer Model shows the principle of operation and the physical parts of a real micrometer. Micrometers use a screw to amplify distances that are too small to measure directly into large rotations of the screw that are big enough to read from a scale. The accuracy of a micrometer derives from the accuracy of the thread that is at its heart. The basic operating principle of a micrometer is that the rotation of an accurately made screw can be directly and precisely correlated to a certain amount of axial movement (and vice-versa), through the constant known as the screw's lead. The Micrometer model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double click the ejs_ntnu_Micrometer.jar file to run the program (Java must be installed).

Hwang, Fu-Kwun

2009-09-11

79

Supernova models  

SciTech Connect

Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the /sup 56/Ni produced therein is reviewed. Within the context of this model for Type I explosions and the 1978 model for Type II explosions, the expected nucleosynthesis and gamma-line spectra from both kinds of supernovae are presented. Finally, a qualitatively new approach to the problem of massive star death and Type II supernovae based upon a combination of rotation and thermonuclear burning is discussed.

Woosley, S.E.; Weaver, T.A.

1980-01-01

80

Transducer Models  

NASA Astrophysics Data System (ADS)

This chapter discusses the basic models with emphasis on audio applications. Loudspeakers are most commonly used as an example of electroacoustic transducers yet, from a modelling point of view, they present the broadest range of challenges to the theoreticians. The fundamental principles are, however, applicable to all transducer problems (microphones, hydrophones, ultrasonics). The reader is assumed to be reasonably familiar with the fundamental concepts of electroacoustics; introductory summaries have been presented by, e.g., Poldy (1994) and Hickson and Busch-Vishniac (1997).

Backman, Juha Reinhold

81

Daisyworld Model  

NSDL National Science Digital Library

The Daisyworld model created by Andrew Watson and James Lovelock (1983, Tellus, v. 35B, p. 284-289) is a wonderful example of a self-regulating system incorporating positive and negative feedbacks. The model consists of a planet on which black and white daisies are growing. The growth of these daisies is governed by a parabolic shaped growth function regulated by planetary temperature and is set to zero for temperatures less than 5 ºC or greater than 40 ºC and optimized at 22.5 ºC. The model explores the effect of a steadily increasing solar luminosity on the growth of daisies and the resulting planetary temperature. The growth function for the daisies allows them to modulate the planet's temperature for many years, warming it early on as black daisies grow, and cooling it later as white daisies grow. Eventually, the solar luminosity increases beyond the daisies' capability to modulate the temperature and they die out, leading to a rapid rise in the planetary temperature. Students read Watson and Lovelock's original paper, and then use STELLA to create their own Daisyworld model with which they can experiment. Experiments include changing the albedos of the daisies, changing their death rates, and changing the rate at which energy is conducted from one part of the planet to another. In all cases, students keep track of daisy populations and of planetary temperature over time.

Menking, Kirsten

82

Climate Models  

NSDL National Science Digital Library

Climate models are tools that scientists have developed to help predict the future climate of our planet based on different scenarios of human impacts to the atmosphere. The last ice age occurred because of a drop of only a few degrees in global temperatures, so even small temperature increases are a concern.

Kqed

2012-03-27

83

Model Behavior  

ERIC Educational Resources Information Center

There are dozens of books and hundreds of resources that address the issue of character development in students: how to raise them to be good people, how to teach them to be good citizens, how to help them to make good decisions. Little is written, however, about the character development of principals and school leaders, whose behavior is a model…

Holloway, John

2006-01-01

84

OSPREY Model.  

National Technical Information Service (NTIS)

The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit oper...

V. J. Rutledge

2013-01-01

85

Modeling Muscles  

ERIC Educational Resources Information Center

Teaching the anatomy of the muscle system to high school students can be challenging. Students often learn about muscle anatomy by memorizing information from textbooks or by observing plastic, inflexible models. Although these mediums help students learn about muscle placement, the mediums do not facilitate understanding regarding integration of…

Goodwyn, Lauren; Salm, Sarah

2007-01-01

86

Modeling Convection  

ERIC Educational Resources Information Center

|Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely…

Ebert, James R.; Elliott, Nancy A.; Hurteau, Laura; Schulz, Amanda

2004-01-01

87

Modeling Muscles  

ERIC Educational Resources Information Center

|Teaching the anatomy of the muscle system to high school students can be challenging. Students often learn about muscle anatomy by memorizing information from textbooks or by observing plastic, inflexible models. Although these mediums help students learn about muscle placement, the mediums do not facilitate understanding regarding integration of…

Goodwyn, Lauren; Salm, Sarah

2007-01-01

88

Atmospheric Modeling  

EPA Science Inventory

Although air quality models have been applied historically to address issues specific to ambient air quality standards (i.e., one criteria pollutant at a time) or welfare (e.g.. acid deposition or visibility impairment). they are inherently multipollutant based. Therefore. in pri...

89

Multivariate modeling  

NASA Astrophysics Data System (ADS)

The special session entitled Multivariate Modeling of Hydrologic and Other Geophysical Time Series was held during the AGU Fall Meeting in San Francisco on Thursday, December 8, 1983, and was sponsored by the Surface Runoff Committee of the Hydrology Section of AGU. The session brought together about 100 participants from different disciplines, including hydrologists, oceanographers, meteorologists, and statisticians, to discuss the state of the art and new developments of stochastic description and modeling of multiple time series of hydrologic and geophysical phenomena.The papers and discussion generated during the session covered a wide variety of hydrologic variables such as streamflow, precipitation, specific conductance, groundwater and water use, meteorologic variables such as air temperature, wind and pressure, and oceanographic variables such as ocean temperature and velocity. Among the topics discussed were: modeling that is oriented to data generation of multivariate processes, basic data analysis and description of statistical characteristics in time and space; modeling specifically oriented to forecasting the processes involved; transfer of hydrologic a nd geophysical information; and detection of changes in hydrologic information.

Salas, Jose D.

90

Supernova Models.  

National Technical Information Service (NTIS)

Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the exp 56 Ni produced therein is reviewed. Within the context of this model for T...

S. E. Woosley T. A. Weaver

1980-01-01

91

Supermarket Model  

Microsoft Academic Search

The flow through this supermarket is shown in Fig. 21.1. This model is adapted after an example in [1]. We first describe the crisp system. Customers arrive at the store according to the exponential distribution which will generate times between arrivals. They first go to the Carts area to pick up a shopping cart. We assume that every customer gets

James J. Buckley

92

Criticality Model  

SciTech Connect

The ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, ''Models'', in that they are procedural, rather than mathematical. These model reports document the detailed methodology necessary to implement the approach presented in the Disposal Criticality Analysis Methodology Topical Report and provide calculations utilizing the methodology. Thus, the governing procedure for this type of report is AP-3.12Q, ''Design Calculations and Analyses''. The ''Criticality Model'' is of this latter type, providing a process evaluating the criticality potential of in-package and external configurations. The purpose of this analysis is to layout the process for calculating the criticality potential for various in-package and external configurations and to calculate lower-bound tolerance limit (LBTL) values and determine range of applicability (ROA) parameters. The LBTL calculations and the ROA determinations are performed using selected benchmark experiments that are applicable to various waste forms and various in-package and external configurations. The waste forms considered in this calculation are pressurized water reactor (PWR), boiling water reactor (BWR), Fast Flux Test Facility (FFTF), Training Research Isotope General Atomic (TRIGA), Enrico Fermi, Shippingport pressurized water reactor, Shippingport light water breeder reactor (LWBR), N-Reactor, Melt and Dilute, and Fort Saint Vrain Reactor spent nuclear fuel (SNF). The scope of this analysis is to document the criticality computational method. The criticality computational method will be used for evaluating the criticality potential of configurations of fissionable materials (in-package and external to the waste package) within the repository at Yucca Mountain, Nevada for all waste packages/waste forms. The criticality computational method is also applicable to preclosure configurations. The criticality computational method is a component of the methodology presented in ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003). How the criticality computational method fits in the overall disposal criticality analysis methodology is illustrated in Figure 1 (YMP 2003, Figure 3). This calculation will not provide direct input to the total system performance assessment for license application. It is to be used as necessary to determine the criticality potential of configuration classes as determined by the configuration probability analysis of the configuration generator model (BSC 2003a).

A. Alsaed

2004-09-14

93

Dynamical approach to heavy-ion induced fission using actinide target nuclei at energies around the Coulomb barrier  

NASA Astrophysics Data System (ADS)

In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasifission, and deep quasifission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reactions of 34,36S + 238U and 30Si + 238U at several incident energies around the Coulomb barrier. We find that the time scale in the quasifission as well as the deformation of fission fragments at the scission point are different between the 30Si + 238U and 36S + 238U systems, causing different mass asymmetries of the quasifission.

Aritomo, Y.; Hagino, K.; Nishio, K.; Chiba, S.

2012-04-01

94

Uncertainty Modeling via Frequency Domain Model Validation.  

National Technical Information Service (NTIS)

The majority of literature on robust control assumes that a design model is available and that the uncertainty model bounds the actual variations about the nominal model. However, methods for generating accurate design models have not received as much att...

M. R. Waszak D. Andrisani

1999-01-01

95

ATMOSPHERIC MODELING: MODEL AND ACCURACY  

EPA Science Inventory

The development of models to assess the emission control requirements of primary precursor pollutants in the production of photochemical oxidants has been underway for approximately 20 years. Over the period there has been a considerable increase in our understanding of the basic...

96

The Model  

Microsoft Academic Search

\\u000a The general model we propose could be applied to a wide range of specific situations, for the control of credit risk or of\\u000a any short or long position in financial guarantees. It can be used for ongoing control of guarantees (i.e., impulse control)\\u000a or for optimal seizure timing (i.e., stopping time). In the real world, some situations will allow for

Didier Cossin; Felipe M. Aparicio

97

Gas Model  

NSDL National Science Digital Library

This highly visual model demonstrates the atomic theory of matter which states that a gas is made up of tiny particles of atoms that are in constant motion, smashing into each other. Balls, representing molecules, move within a cage container to simulate this phenomenon. A hair dryer provides the heat to simulate the heating and cooling of gas: the faster the balls are moving, the hotter the gas. Learners observe how the balls move at a slower rate at lower "temperatures."

Exploratorium, The

2013-01-30

98

Gyroscope Model  

NSDL National Science Digital Library

The Gyroscope example computes and displays the dynamics of gyroscope under the influence of a gravitational torque acting on the center of mass. The gyroscope is supported at one end and given an initial angular velocity component about its axis of symmetry and a component perpendicular to its axis of symmetry. The numerical solution shows the motion for all initial conditions including zero initial angular momentum. The model is designed to show the cycloidal motion (precession and nutation) of the gyroscope axle when the initial angular velocity is large. Users can very the position and radius of the spinning mass as well as the initial angle and can display the angular momentum, angular velocity, and torque vectors. A second window shows the elevation angle of the axle and the angular momentum vector.   Units are chosen such that the total mass M and the acceleration of gravity g are one. The rotor is an ellipsoid with a uniform mass distribution and with major axes 2*R and minor axis R/5. The ellipsoid's moment of inertia through the center of mass is 4MR2/5 about the major axes and 26MR2/125 about the minor axis. The Gyroscope model is a supplemental simulation for the article "It Has to Go Down a Little, in Order to Go Around" by Svilen Kostov and Daniel Hammer in The Physics Teacher 49(4), 216-219 (2011) and has been approved by the authors and The Physics Teacher editor. The model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_csm_ch17_Gyroscope.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-02-10

99

Linear Models  

NSDL National Science Digital Library

This site uses linear models to demonstrate the change in bird populations on a barren island over time, supply and demand, and the natural cleaning of a polluted lake by fresh water over time. The problems are laid out and turned into both graphic and equation form in order to understand the rate of change happening in each scenario. There are also links to previously covered materials that can help student review material from past math lessons.

Wattenberg, Frank

1997-01-01

100

Nuclear Models  

SciTech Connect

The atomic nucleus is a typical example of a many-body problem. On the one hand, the number of nucleons (protons and neutrons) that constitute the nucleus is too large to allow for exact calculations. On the other hand, the number of constituent particles is too small for the individual nuclear excitation states to be explained by statistical methods. Another problem, particular for the atomic nucleus, is that the nucleon-nucleon (n-n) interaction is not one of the fundamental forces of Nature, and is hard to put in a single closed equation. The nucleon-nucleon interaction also behaves differently between two free nucleons (bare interaction) and between two nucleons in the nuclear medium (dressed interaction).Because of the above reasons, specific nuclear many-body models have been devised of which each one sheds light on some selected aspects of nuclear structure. Only combining the viewpoints of different models, a global insight of the atomic nucleus can be gained. In this chapter, we revise the the Nuclear Shell Model as an example of the microscopic approach, and the Collective Model as an example of the geometric approach. Finally, we study the statistical properties of nuclear spectra, basing on symmetry principles, to find out whether there is quantum chaos in the atomic nucleus. All three major approaches have been rewarded with the Nobel Prize of Physics. In the text, we will stress how each approach introduces its own series of approximations to reduce the prohibitingly large number of degrees of freedom of the full many-body problem to a smaller manageable number of effective degrees of freedom.

Fossion, Ruben [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, Mexico D. F., C.P. 04510 (Mexico)

2010-09-10

101

Animal Models  

Microsoft Academic Search

\\u000a Clinical research has delineated the nature and severity of acute and chronic cerebral disturbances in relation to abnormal\\u000a glucose metabolism, as reviewed in the previous chapters of this book. By comparison, insight into the pathophysiology is\\u000a still limited and evidence for effective treatment is largely lacking. Studies in animal models may help to fill in these\\u000a gaps in our knowledge.

Geert Jan Biessels

102

Model Well  

NSDL National Science Digital Library

In this quick activity about pollutants and groundwater (page 2 of PDF), learners build a model well with a toilet paper tube. Learners use food coloring to simulate pollutants and observe how they can be carried by groundwater and eventually enter water sources such as wells, rivers, and streams. This activity is associated with nanotechnology and relates to linked video, DragonflyTV Nano: Water Clean-up.

Twin Cities Public Television, Inc.

2008-01-01

103

Eratosthenes Model  

NSDL National Science Digital Library

The Eratosthenes model displays the shadows cast by two gnomons (sticks) at different locations on Earth. For one gnomon, Sun is directly overhead (as would be the case if the gnomon was on the Tropic of Cancer at the summer solstice). The other gnomon is due north of the first gnomon. The sizes of the gnomons are greatly exaggerated for visibility. This simulation can be used to help illustrate how Eratosthenes was able to measure the diameter of Earth using the shadows cast by two gnomons, one situated due north of the other, on a day when the southerly gnomon cast no shadow at all. The distance between the two gnomons (along Earth's surface) can be adjusted. The length of the shadow is given, and this length can be used to determine the angle between the gnomon lines and from that the circumference (and diameter, radius, etc) of Earth. Earth can be hidden to give a better view of the relevant geometry. Eratosthenes model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_Eratosthenes.jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the plot and selecting "Open EJS Model" from the pop-up menu item.

Timberlake, Todd

2010-01-03

104

Modeling biomembranes.  

SciTech Connect

Understanding the properties and behavior of biomembranes is fundamental to many biological processes and technologies. Microdomains in biomembranes or ''lipid rafts'' are now known to be an integral part of cell signaling, vesicle formation, fusion processes, protein trafficking, and viral and toxin infection processes. Understanding how microdomains form, how they depend on membrane constituents, and how they act not only has biological implications, but also will impact Sandia's effort in development of membranes that structurally adapt to their environment in a controlled manner. To provide such understanding, we created physically-based models of biomembranes. Molecular dynamics (MD) simulations and classical density functional theory (DFT) calculations using these models were applied to phenomena such as microdomain formation, membrane fusion, pattern formation, and protein insertion. Because lipid dynamics and self-organization in membranes occur on length and time scales beyond atomistic MD, we used coarse-grained models of double tail lipid molecules that spontaneously self-assemble into bilayers. DFT provided equilibrium information on membrane structure. Experimental work was performed to further help elucidate the fundamental membrane organization principles.

Plimpton, Steven James; Heffernan, Julieanne; Sasaki, Darryl Yoshio; Frischknecht, Amalie Lucile; Stevens, Mark Jackson; Frink, Laura J. Douglas

2005-11-01

105

Molecular Modeling  

NASA Astrophysics Data System (ADS)

Molecular modeling has trickled down from the realm of pharmaceutical and research laboratories into the realm of undergraduate chemistry instruction. It has opened avenues for the visualization of chemical concepts that previously were difficult or impossible to convey. I am sure that many of you have developed exercises using the various molecular modeling tools. It is the desire of this Journal to become an avenue for you to share these exercises among your colleagues. It is to this end that Ron Starkey has agreed to edit such a column and to publish not only the description of such exercises, but also the software documents they use. The WWW is the obvious medium to distribute this combination and so accepted submissions will appear online as a feature of JCE Internet. Typical molecular modeling exercise: finding conformation energies. Molecular Modeling Exercises and Experiments is the latest feature column of JCE Internet, joining Conceptual Questions and Challenge Problems, Hal's Picks, and Mathcad in the Chemistry Curriculum. JCE Internet continues to seek submissions in these areas of interest and submissions of general interest. If you have developed materials and would like to submit them, please see our Guide to Submissions for more information. The Chemical Education Resource Shelf, Equipment Buyers Guide, and WWW Site Review would also like to hear about chemistry textbooks and software, equipment, and WWW sites, respectively. Please consult JCE Internet Features to learn more about these resources at JCE Online. Email Announcements Would you like to be informed by email when the latest issue of the Journal is available online? when a new JCE Software title is shipping? when a new JCE Internet article has been published or is available for Open Review? when your subscription is about to expire? A new feature of JCE Online makes this possible. Visit our Guestbook to learn how. When you submit the form on this page, which includes your email address, you may choose to receive an email notice about a Journal event that interests you. Currently such events include availability of the latest issue of the Journal at JCE Online, expiration of your Journal subscription, shipment of a new JCE Software issue, publication of a new JCE Internet article or its availability for Open Review, and other announcements from the Journal. You may choose any number of these options independently. JCE Online Guestbook. Your Privacy JCE Online promises to you that we will not use the information that you provide in our Guestbook for anything other than our own internal information. We will not provide this information to third parties. We will use the information you provide only in our effort to help make the JCE serve you better. You only need to provide your email address to take advantage of this service; the other information you provide is optional. Molecular Modeling Exercises and Experiments: Mission Statement We are seeking in this JCE Internet feature column to publish molecular modeling exercises and experiments that have been used successfully in undergraduate instruction. The exercises will be published here on JCE Internet. An abstract of published submissions will appear in print in the Journal of Chemical Education. Acceptable exercises could be used in either a chemistry laboratory or a chemistry computer laboratory. The exercise could cover any area of chemistry, but should be limited to undergraduate instructional applications. We envision that most of the exercises/experiments will utilize one of the popular instructional molecular modeling software programs (e.g. HyperChem, Spartan, CAChe, PC Model). Exercises that are specific to a particular modeling program are acceptable, but those usable with any modeling program are preferred. Ideally the exercises/experiments will be of the type where the "correct"answer is not obvious so

Holmes, Jon L.

1999-06-01

106

Simulation modeling using ProModel technology  

Microsoft Academic Search

PROMODEL's simulation modeling products are powerful yet easy-to-use simulation tools for modeling all types of systems and processes. ProModel is designed to model manufacturing systems ranging from small job shops and machining cells to large mass production, flexible manufacturing systems, and supply chain systems. Other simulation products available from PROMODEL Corporation include MedModel®, ServiceModel®, and our latest release, ProModel PI

C. R. Harrell; R. N. Price

2003-01-01

107

Towards an improved evaluation of neutron-induced fission cross sections on actinides  

NASA Astrophysics Data System (ADS)

Mean-field calculations can now provide all the nuclear ingredients required to describe the fission path from the equilibrium deformation up to the nuclear scission point. The information obtained from microscopic mean-field models has been included in the TALYS reaction code to improve the predictions of neutron-induced fission cross sections. The nuclear inputs concern not only the details of the energy surface along the fission path, but also the coherent estimate of the nuclear level density derived within the combinatorial approach on the basis of the same single-particle properties, in particular at the fission saddle points. The predictive power of such a microscopic approach is tested on the experimental data available for the uranium isotopic chain. It is also shown that the various inputs can be tuned to reproduce, at best, experimental data in one unique coherent framework, so that in a close future it should become possible to make, on the basis of such models, accurate fission-cross-section calculations and the corresponding estimates for nuclei, energy ranges, or reaction channels for which no data exist. Such model uncertainties are usually not taken into account in data evaluations.

Goriely, S.; Hilaire, S.; Koning, A. J.; Capote, R.

2011-03-01

108

Towards an improved evaluation of neutron-induced fission cross sections on actinides  

SciTech Connect

Mean-field calculations can now provide all the nuclear ingredients required to describe the fission path from the equilibrium deformation up to the nuclear scission point. The information obtained from microscopic mean-field models has been included in the TALYS reaction code to improve the predictions of neutron-induced fission cross sections. The nuclear inputs concern not only the details of the energy surface along the fission path, but also the coherent estimate of the nuclear level density derived within the combinatorial approach on the basis of the same single-particle properties, in particular at the fission saddle points. The predictive power of such a microscopic approach is tested on the experimental data available for the uranium isotopic chain. It is also shown that the various inputs can be tuned to reproduce, at best, experimental data in one unique coherent framework, so that in a close future it should become possible to make, on the basis of such models, accurate fission-cross-section calculations and the corresponding estimates for nuclei, energy ranges, or reaction channels for which no data exist. Such model uncertainties are usually not taken into account in data evaluations.

Goriely, S. [Institut d'Astronomie et d'Astrophysique, CP-226, Universite Libre de Bruxelles, BE-1050 Brussels (Belgium); Hilaire, S. [CEA, DAM, DIF, F-91297 Arpajon (France); Koning, A. J. [Nuclear Research and Consultancy Group, P.O. Box 25, NL-1755 ZG Petten (Netherlands); Capote, R. [International Atomic Energy Agency, NAPC-Nuclear Data Section, AT-1400 Vienna (Austria)

2011-03-15

109

Model functions of Reynolds stress models  

Microsoft Academic Search

A Reynolds stress (Re-stress) model for the prediction of shear flows is presented. Special attention is paid to the determination of the model functions. First, the general modeling assumptions are discussed and the modeling of the equations is then described in detail. It is shown that by successive analysis of different types of flows a set of model functions with

Johannes Janicka

1988-01-01

110

Predictive Statistical Models for User Modeling  

Microsoft Academic Search

The limitations of traditional knowledge representation methods for modeling complex human behaviour led to the investigation of statistical models. Predictive statistical models enable the anticipation of certain aspects of human behaviour, such as goals, actions and preferences. In this paper, we motivate the development of these models in the context of the user modeling enterprise. We then review the two

Ingrid Zukerman; David W. Albrecht

2001-01-01

111

Bayesian Model Selection in Structural Equation Models  

Microsoft Academic Search

Abstract A Bayesian approach to model selection for structural equation models is outlined. This enables us to compare individual models, nested or non-nested, and also to search through the (perhaps vast) set of possible models for the best ones. The approach selects several models rather than just one, when appropriate, and so enables us to take account, both informally and

Adrian E. Raftery

1993-01-01

112

UNCERTAINTY MODELING VIA FREQUENCY DOMAIN MODEL VALIDATION  

Microsoft Academic Search

The majority of literature on robust control assumes that a design model is available and that the uncertainty model bounds the actual variations about the nominal model. However, methods for generating accurate design models have not received as much attention in the literature. The influence of the level of accuracy of the uncertainty model on closed loop performance has received

Martin R. Waszak

1999-01-01

113

Engineering Structurally Configurable Models with Model Transformation.  

National Technical Information Service (NTIS)

Complex configurable models of embedded software systems are hard to design and maintain, especially when model structures are variable and the number of allowable configurations is unlimited. We employ model transformation as an underlying technique to c...

T. H. Feng

2008-01-01

114

CISNET lung models: Comparison of model assumptions and model structures  

PubMed Central

Sophisticated modeling techniques can be powerful tools to help us understand the effects of cancer control interventions on population trends in cancer incidence and mortality. Readers of journal articles are however rarely supplied with modeling details. Six modeling groups collaborated as part of the National Cancer Institute’s Cancer Intervention and Surveillance Modeling Network (CISNET) to investigate the contribution of US tobacco control efforts towards reducing lung cancer deaths over the period 1975 to 2000. The models included in this monograph were developed independently and use distinct, complementary approaches towards modeling the natural history of lung cancer. The models used the same data for inputs and agreed on the design of the analysis and the outcome measures. This article highlights aspects of the models that are most relevant to similarities of or differences between the results. Structured comparisons can increase the transparency of these complex models.

McMahon, Pamela M.; Hazelton, William; Kimmel, Marek; Clarke, Lauren

2012-01-01

115

About Antiferromagnetic Heisenberg Models.  

National Technical Information Service (NTIS)

Phase transitions and magnetism are addressed. Focus on the (antiferromagnetic) Heisenberg model, a quantum mechanical model for describing (anti)ferromagnetic systems. Classical statistical lattice models, including the Ising model, are compared with mod...

P. Iske

1989-01-01

116

Sales Advertising Response Models  

Microsoft Academic Search

This paper surveys dynamic models in the field of advertising. After a brief introduction to the differential game theory some sales-advertising response models are described. These models are organised under five headings: Vidale-Wolfe generalisations, Lanchester-type models, Leitmann models, Excess advertising models and Combined models. This up-to date review of the existing literature in this field compares specification of models, analysed

Petr Mariel

1998-01-01

117

Fission barriers and half-lives of actinides in the quasimolecular shape valley  

NASA Astrophysics Data System (ADS)

The energy of actinide nuclei in the fusionlike deformation valley has been determined from a liquid-drop model, taking into account the proximity energy, the mass and charge asymmetries, and the shell and pairing energies. Double-humped potential barriers appear. The saddle point corresponds to the second maximum and to the transition from compact one-body shapes with a deep neck to two touching ellipsoids. The scission point, where the effects of the nuclear attractive forces between the fragments vanish, lies at the end of an energy plateau below the saddle point and corresponds to two well-separated fragments. The kinetic and excitation energies of the fragments come from the energy on this plateau. The shell and pairing effects play a main role to decide the most probable decay path. The heights of the potential barriers roughly agree with the experimental data and the calculated half-lives follow the trend of the experimental values. A shallow third minimum and a third peak appear in specific asymmetric exit channels where one fragment is close to a double magic quasispherical nucleus, while the other one evolves from oblate to prolate shapes.

Royer, G.; Jaffré, M.; Moreau, D.

2012-10-01

118

Light charged particle release in252Cf spontaneous fission: Tripartition versus fragment de-excitation  

NASA Astrophysics Data System (ADS)

Double-differential emission probabilities P (E, ?) in angle ? and energy E of protons, tritons, and ?-particles were measured in the case of spontaneous fission of252Cf. A detector system consisting of position-sensitive parallel-plate avalanche counters (PPAC) and ?E-E-telescopes allowed a coincidence measurement of fission fragments (FF) and light charged particles (LCP) in the whole region from 0 deg. to 180 deg. with respect to the light-fragment direction. Previous results for ?-particle emission were confirmed. The background contributions for protons are discussed in detail. For proton emission the background arising from ( n, p)-reactions was measured and compared with a corresponding Monte-Carlo simulation of elastic ( n, p)-clusions. Unlike for tritons and a-particles the P ( E, ?) distribution for protons does not show equatorial peaking in 0 between 80 deg. and 90 deg. and contradicts classical scission point emission. The proton distribution, however, agrees with fragment de-excitation calculations in the framework of the cascade evaporation model (CEM) whereas an analogous calculation for ?-particles completely fails. Upper limits for an additional scission component of proton emission are given.

Schubert, A.; Hutsch, J.; Möller, K.; Neubert, W.; Pilz, W.; Schmidt, G.; Adler, M.; Märten, H.

1992-12-01

119

Model selection for logistic regression models  

NASA Astrophysics Data System (ADS)

Model selection for logistic regression models decides which of some given potential regressors have an effect and hence should be included in the final model. The second interesting question is whether a certain factor is heterogeneous among some subsets, i.e. whether the model should include a random intercept or not. In this paper these questions will be answered with classical as well as with Bayesian methods. The application show some results of recent research projects in medicine and business administration.

Duller, Christine

2012-09-01

120

Multispectral imager modeling  

NASA Astrophysics Data System (ADS)

This paper describes the modeling of multispectral infrared sensors. The current NVESD infrared sensor model, NVTherm, models single spectral band sensors. The current NVTherm model is being updated to model third generation multispectral infrared sensors. A simple model for the target and its background radiance is presented here and typical results are reported for common materials. The proposed target radiance model supports band selection studies. Spectral atmospheric propagation modeling is accomplished using MODTRAN. Example radiance calculations are presented and compared to data collected for validation. The data supports rejecting the null hypothesis that the model is invalid.

Fanning, Jonathan; Halford, Carl; Jacobs, Eddie; Richardson, Phil

2005-05-01

121

Aerosol Modeling for the Global Model Initiative.  

National Technical Information Service (NTIS)

The goal of this project is to develop an aerosol module to be used within the framework of the Global Modeling Initiative (GMI). The model development work will be preformed jointly by the University of Michigan and AER, using existing aerosol models at ...

D. K. Weisenstein M. K. W. Ko

2001-01-01

122

Interfacing materials models with fire field models  

Microsoft Academic Search

For flame spread over solid materials, there has traditionally been a large technology gap between fundamental combustion research and the somewhat simplistic approaches used for practical, real-world applications. Recent advances in computational hardware and computational fluid dynamics (CFD)-based software have led to the development of fire field models. These models, when used in conjunction with material burning models, have the

V. F. Nicolette; S. R. Tieszen; J. L. Moya

1995-01-01

123

Model documentation: household model of energy  

Microsoft Academic Search

The Household Model of Energy is an econometric model, meaning that energy use is determined quantitatively with the use of economic variables such as fuel prices and income. HOME is also primarily a structural model, meaning that energy use is determined as the result of interactions of intermediate components such as the number of households, the end use fuel shares

Holte

1984-01-01

124

From Conceptual Model to Internal Model  

Microsoft Academic Search

A uniform formalism is used to model all stages of knowledge-based systems design. In this approach data, information and knowledge are all represented in this single uniform formalism. This formalism incorporates two classes of constraints which are applied to data, information and to knowledge. A conceptual model is a representation of the system expertise using this formalism. An internal model

John K. Debenham

1997-01-01

125

Modeling Guru: Knowledge Base for NASA Modelers  

Microsoft Academic Search

Modeling Guru is an on-line knowledge-sharing resource for anyone involved with or interested in NASA's scientific models or High End Computing (HEC) systems. Developed and maintained by the NASA's Software Integration and Visualization Office (SIVO) and the NASA Center for Computational Sciences (NCCS), Modeling Guru's combined forums and knowledge base for research and collaboration is becoming a repository for the

M. S. Seablom; G. S. Wojcik; B. H. van Aartsen

2009-01-01

126

Modeling the Interpretive Process.  

ERIC Educational Resources Information Center

|Describes and compares three models used in planning interpretive environmental experiences: an intuitive program-planning model; an interactive communications model; and Cherem's model, in which the audience directly influences program goals and techniques. Cherem's model includes managerial realities, but doesn't recognize the social aspect of…

McKean, Barbara

1999-01-01

127

Multilevel Model Prediction  

ERIC Educational Resources Information Center

|Multilevel models are proven tools in social research for modeling complex, hierarchical systems. In multilevel modeling, statistical inference is based largely on quantification of random variables. This paper distinguishes among three types of random variables in multilevel modeling--model disturbances, random coefficients, and future response…

Frees, Edward W.; Kim, Jee-Seon

2006-01-01

128

Fire models and design  

Microsoft Academic Search

Over the last 20 years there has been a great increase in the construction of computer-based models related to fire risk. Both probabilistic and deterministic models have been produced. Many existing models are in a state of development and new models are being created continually. However, how such models are to be efficaciously employed as part of the design process

Alan N. Beard

1997-01-01

129

Symbolic Modeling of Epistasis  

Microsoft Academic Search

The workhorse of modern genetic analysis is the parametric linear model. The advantages of the linear modeling framework are many and include a mathematical understanding of the model fitting process and ease of interpretation. However, an important limitation is that linear models make assumptions about the nature of the data being modeled. This assumption may not be realistic for complex

Jason H. Moore; Nate Barney; Chia-Ti Tsai; Fu-Tien Chiang; Jiang Gui; Bill C. White

2007-01-01

130

"Bohr's Atomic Model."  

ERIC Educational Resources Information Center

|"Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

Willden, Jeff

2001-01-01

131

Anisotropic reflection models  

Microsoft Academic Search

We present a new set of lighting models derived from the questions of electromagnetism. These models describe the reflection and refraction of light from surfaces which exhibit anisotropy---surfaces with preferred directions. The model allows a new mapping technique, which we call . We also discuss the general relationship between geometric models, surface mapping of all types, and lighting models in

James T. Kajiya

1985-01-01

132

Role Based Workflow Modeling  

Microsoft Academic Search

Role based workflow modeling relates to organization modeling and authorization modeling in two aspects. This paper proposes a role-based access control (RBAC in abbreviation) based organization model and authorization model according to the characteristic of user organization and authorization in workflow management systems, which separate users and their authority from each other, and users authority and authorization can be handled

Zhigang Liang; S. Bai

2006-01-01

133

Model functions of Reynolds stress models  

NASA Astrophysics Data System (ADS)

A Reynolds stress (Re-stress) model for the prediction of shear flows is presented. Special attention is paid to the determination of the model functions. First, the general modeling assumptions are discussed and the modeling of the equations is then described in detail. It is shown that by successive analysis of different types of flows a set of model functions with a high level of universality can be deduced. Finally, prediction/measurement comparisons in homogeneous shear flows, round jets, plane jets, and wakes are presented.

Janicka, Johannes

1988-01-01

134

Solicited abstract: Global hydrological modeling and models  

NASA Astrophysics Data System (ADS)

The origins of rainfall-runoff modeling in the broad sense can be found in the middle of the 19th century arising in response to three types of engineering problems: (1) urban sewer design, (2) land reclamation drainage systems design, and (3) reservoir spillway design. Since then numerous empirical, conceptual and physically-based models are developed including event based models using unit hydrograph concept, Nash's linear reservoir models, HBV model, TOPMODEL, SHE model, etc. From the late 1980s, the evolution of global and continental-scale hydrology has placed new demands on hydrologic modellers. The macro-scale hydrological (global and regional scale) models were developed on the basis of the following motivations (Arenll, 1999). First, for a variety of operational and planning purposes, water resource managers responsible for large regions need to estimate the spatial variability of resources over large areas, at a spatial resolution finer than can be provided by observed data alone. Second, hydrologists and water managers are interested in the effects of land-use and climate variability and change over a large geographic domain. Third, there is an increasing need of using hydrologic models as a base to estimate point and non-point sources of pollution loading to streams. Fourth, hydrologists and atmospheric modellers have perceived weaknesses in the representation of hydrological processes in regional and global climate models, and developed global hydrological models to overcome the weaknesses of global climate models. Considerable progress in the development and application of global hydrological models has been achieved to date, however, large uncertainties still exist considering the model structure including large scale flow routing, parameterization, input data, etc. This presentation will focus on the global hydrological models, and the discussion includes (1) types of global hydrological models, (2) procedure of global hydrological model development, (3) state-of-the-art of existing global hydrological models, and (4) challenges. Acknowledgment: Thanks to Lebing Gong, Elin Widén-Nilsson, and Sven Halldin of Uppsala University for the team work in global hydrological models.

Xu, Chong-Yu

2010-05-01

135

Air Quality Display Model.  

National Technical Information Service (NTIS)

The Air Quality Display Model was developed for the computation of seasonal and annual concentration estimates. It is to be considered as a provisional dispersion model for estimating air quality until continuing research indicates an improved model is av...

1969-01-01

136

Educating with Aircraft Models  

ERIC Educational Resources Information Center

|Described is utilization of aircraft models, model aircraft clubs, and model aircraft magazines to promote student interest in aerospace education. The addresses for clubs and magazines are included. (SL)|

Steele, Hobie

1976-01-01

137

Physiological Modelling Using RL.  

National Technical Information Service (NTIS)

The use of constraints to build quantitative physiological models and the application of these models to assist anaesthetists in decision making are discussed. A simple physiological model of human blood circulation and gas is given. It is represented in ...

F. Degeus E. Rotterdam S. Vandenneheuvel P. Vanemdeboas

1990-01-01

138

Models of magnetism  

NSDL National Science Digital Library

This study investigates the mental models that people construct about magnetic phenomena. The project involved students, physics teachers, engineers, and practitioners. The researchers propose five models following a progression from simple description to a field model. Contains 28 references.

Borges, A. T.; Gilbert, John; Tecnico, Colegio

2006-05-23

139

FNMOC Model Verification System.  

National Technical Information Service (NTIS)

Fleet Numerical Meteorology and Oceanography Center (FNMOC) forecasts the atmospheric environment and weather using several meteorological and oceanographic models. These models' forecasting abilities are verified by comparing the model forecast against t...

K. P. Pace

1998-01-01

140

Model Patterns for Model Transformations in Model Driven Development  

Microsoft Academic Search

Model driven development is a popular approach to mas- ter the complexity of computer based systems, but it is still missing well-established technologies for model transforma- tions. A lot of research has been done to address this sub- ject, most of it tends towards highly expressive and highly specialized transformation languages. This paper takes a contra point to this trend,

Markus Scheidgen

2006-01-01

141

Improved modeling by coupling imperfect models  

NASA Astrophysics Data System (ADS)

Most of the existing approaches for combining models representing a single real-world phenomenon into a multi-model ensemble combine the models a posteriori. Alternatively, in our method the models are coupled into a supermodel and continuously communicate during learning and prediction. The method learns a set of coupling coefficients from short past data in order to unite the different strengths of the models into a better representation of the observed phenomenon. The method is examined using the Lorenz oscillator, which is altered by introducing parameter and structural differences for creating imperfect models. The short past data is obtained by the standard oscillator, and different weight is assigned to each sample of the past data. The coupling coefficients are learned by using a quasi-Newton method and an evolutionary algorithm. We also introduce a way for reducing the supermodel, which is particularly useful for models of high complexity. The results reveal that the proposed supermodel gives a very good representation of the truth even for substantially imperfect models and short past data, which suggests that the super-modeling is promising in modeling real-world phenomena.

Mirchev, Miroslav; Duane, Gregory S.; Tang, Wallace K. S.; Kocarev, Ljupco

2012-07-01

142

ROCK PROPERTIES MODEL ANALYSIS MODEL REPORT  

SciTech Connect

The purpose of this Analysis and Model Report (AMR) is to document Rock Properties Model (RPM) 3.1 with regard to input data, model methods, assumptions, uncertainties and limitations of model results, and qualification status of the model. The report also documents the differences between the current and previous versions and validation of the model. The rock properties models are intended principally for use as input to numerical physical-process modeling, such as of ground-water flow and/or radionuclide transport. The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. This work was conducted in accordance with the following planning documents: WA-0344, ''3-D Rock Properties Modeling for FY 1998'' (SNL 1997, WA-0358), ''3-D Rock Properties Modeling for FY 1999'' (SNL 1999), and the technical development plan, Rock Properties Model Version 3.1, (CRWMS M&O 1999c). The Interim Change Notice (ICNs), ICN 02 and ICN 03, of this AMR were prepared as part of activities being conducted under the Technical Work Plan, TWP-NBS-GS-000003, ''Technical Work Plan for the Integrated Site Model, Process Model Report, Revision 01'' (CRWMS M&O 2000b). The purpose of ICN 03 is to record changes in data input status due to data qualification and verification activities. These work plans describe the scope, objectives, tasks, methodology, and implementing procedures for model construction. The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The work scope for this activity consists of the following: (1) Conversion of the input data (laboratory measured porosity data, x-ray diffraction mineralogy, petrophysical calculations of bound water, and petrophysical calculations of porosity) for each borehole into stratigraphic coordinates; (2) Re-sampling and merging of data sets; (3) Development of geostatistical simulations of porosity; (4) Generation of derivative property models via linear coregionalization with porosity; (5) Post-processing of the simulated models to impart desired secondary geologic attributes and to create summary and uncertainty models; and (6) Conversion of the models into real-world coordinates. The conversion to real world coordinates is performed as part of the integration of the RPM into the Integrated Site Model (ISM) 3.1; this activity is not part of the current analysis. The ISM provides a consistent volumetric portrayal of the rock layers, rock properties, and mineralogy of the Yucca Mountain site and consists of three components: (1) Geologic Framework Model (GFM); (2) RPM, which is the subject of this AMR; and (3) Mineralogic Model. The interrelationship of the three components of the ISM and their interface with downstream uses are illustrated in Figure 1. Figure 2 shows the geographic boundaries of the RPM and other component models of the ISM.

Clinton Lum

2002-02-04

143

Modelling Holocene climate trends: A model intercomparison  

NASA Astrophysics Data System (ADS)

For the paleomodel intercomparison, we compared the results from scenarios with identical forcing for the mid-to-late Holocene period: varying Earth's orbital parameters, fixed level of greenhouse gas concentrations, fixed land-sea mask and orography. 18 paleoclimate modelling groups are involved in this initiative, working on transient Holocene simulations. One major issue of both the modelling and reconstruction side were the quantification of uncertainties, and the evaluation of trend and variability patterns beyond a single proxy and beyond a single model simulation. The goal is to obtain robust results of trend patterns, seasonality changes, as well as transitions on a regional scale. The major objective is to investigate the spatio-temporal pattern of temperature and precipitation changes during Holocene as derived from integrations with a set comprehensive global climate models (GCMs), Earth system models of intermediate complexity (EMICs), as well as conceptual-statistical models. In the conceptual-statistical model by Laepple and Lohmann (2009) a rigorous simple concept is proposed: The temperature response on astronomical timescales has the same function as the response to seasonal insolation variations. The general pattern of surface temperatures in the models shows a high latitude cooling and a low latitude warming. Our analysis shows common patterns of temperature changes, especially for the respective summer seasons. This is a common feature for all model considered. Due to strong differences in atmospheric dynamics and sea ice, we find significant differences in the winter patterns. The precipitation trends show a clear difference between GCMs and EMICs mainly because the treatment of the hydological cycle in the tropics. Most models show a southward movement of the ITCZ. Using statistical analysis of the model variability modes and their amplitude during the Holocene, we reveal a strong heterogeneity in temperature and precipitation pattern and no common response in trend and variability, although a tendency towards NAO- and SOI- (El Nino-like) is detected. Our approach is to obtain, through ensemble runs for climate model output, a range of solutions that can be then compared and evaluated for their consistency with the range of uncertainty given by the palaeoclimate proxies. This approach allows a much more congruent way of comparison between proxy data and model result because both investigations will provide a range of possible climate change where the errors in the estimates are accounted for. We compare the ocean temperature evolution of the Holocene as simulated by climate models and reconstructed from marine temperature proxies. Independently of the choice of the climate model, we observe significant mismatches between modelled and reconstructed amplitudes in the trends for the last 6000 years.

Lohmann, Gerrit

2013-04-01

144

PREDICTIVE MODELS. Enhanced Oil Recovery Model  

SciTech Connect

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1 chemical flooding; 2 carbon dioxide miscible flooding; 3 in-situ combustion; 4 polymer flooding; and 5 steamflood. CFPM, the Chemical Flood Predictive Model, models micellar (surfactant)-polymer floods in reservoirs, which have been previously waterflooded to residual oil saturation. Thus, only true tertiary floods are considered. An option allows a rough estimate of oil recovery by caustic or caustic-polymer processes. CO2PM, the Carbon Dioxide miscible flooding Predictive Model, is applicable to both secondary (mobile oil) and tertiary (residual oil) floods, and to either continuous CO2 injection or water-alternating gas processes. ICPM, the In-situ Combustion Predictive Model, computes the recovery and profitability of an in-situ combustion project from generalized performance predictive algorithms. PFPM, the Polymer Flood Predictive Model, is switch-selectable for either polymer or waterflooding, and an option allows the calculation of the incremental oil recovery and economics of polymer relative to waterflooding. SFPM, the Steamflood Predictive Model, is applicable to the steam drive process, but not to cyclic steam injection (steam soak) processes. The IBM PC/AT version includes a plotting capability to produces a graphic picture of the predictive model results.

Ray, R.M. [DOE Bartlesville Energy Technology Center, Bartlesville, OK (United States)

1992-02-26

145

Maintenance Support Model.  

National Technical Information Service (NTIS)

This thesis develops a general structure of an explicit, sequential event model of maintenance support at division level. The model is intended as an initial stage model for subsequent use in tandem with a combat feeder model to provide necessary insight ...

S. P. Peterson

1984-01-01

146

model of sentence production  

Microsoft Academic Search

The ability to combine words into novel sentences has been used to argue that humans have symbolic language production abilities. Critiques of connectionist models of language often center on the inabil- ity of these models to generalize symbolically (Fodor & Pylyshyn, 1988; Marcus, 1998). To address these issues, a connectionist model of sentence production was developed. The model had variables

Franklin Chang

147

Microbial modeling in foods  

Microsoft Academic Search

Predictive food microbiology is a field of study that combines elements of microbiology, mathematics, and statistics to develop models that describe and predict the growth or decline of microbes under specified environmental conditions. Models can be thought of as having three levels: primary level models describe changes in microbial numbers with time, secondary level models show how the parameters of

Richard C. Whiting

1995-01-01

148

AIDS Epidemiological models  

NASA Astrophysics Data System (ADS)

The aim of this paper is to present mathematical modelling of the spread of infection in the context of the transmission of the human immunodeficiency virus (HIV) and the acquired immune deficiency syndrome (AIDS). These models are based in part on the models suggested in the field of th AIDS mathematical modelling as reported by ISHAM [6].

Rahmani, Fouad Lazhar

2010-11-01

149

Model Engineering using Multimodeling.  

National Technical Information Service (NTIS)

We study the simultaneous use of multiple modeling techniques in the design of embedded systems. We begin with a pre-existing Statecharts model of a simple case study, a traffic light for a pedestrian crossing. This model combines two distinct models of c...

C. Brooks C. P. Cheng E. A. Lee R. Von Hanxleden T. H. Feng

2008-01-01

150

Connectionist models of development  

Microsoft Academic Search

How have connectionist models informed the study of development? This paper considers three contributions from specific models. First, connectionist models have proven useful for exploring nonlinear dynamics and emergent properties, and their role in non- linear developmental trajectories, critical periods and developmental disorders. Second, connectionist models have informed the study of the representations that lead to behavioral dissociations. Third, connectionist

Yuko Munakata; James L. McClelland

2003-01-01

151

the model framework  

Treesearch

We are attempting to develop a computer model that will predict EAB future ... We have two model variants, an insect-flight model and an insect-ride model to assess ... Check the Northern Research Station web site to request a printed copy of ...

152

Global Timber Model  

EPA Science Inventory

The Global Timber Model is an economic model capable of examining global forestry land-use, management, and trade responses to policies. In responding to a policy, the model captures afforestation, forest management, and avoided deforestation behavior. The model estimates harves...

153

Models for Food Webs  

Microsoft Academic Search

Food webs are complex systems of many interacting biological species. After summarizing some of their properties, this contribution presents different ways of modeling food webs. It briefly mentions static models and discusses dynamical models and their population dynamics equations. The complexity-stability debate is mentioned, and evolutionary food web models are presented as a natural way of obtaining large stable webs.

Barbara Drossel

154

Mixed Model Influence Diagnostics  

Microsoft Academic Search

Linear models for uncorrelated data have well established measures to gauge the influence of one or more observations on the analysis. For such models, closed-form update expressions allow efficient computa- tions without refitting the model. When similar notions of statistical influence are applied to mixed models, things are more complicated. Removing data points affects fixed effects and covariance parameter esti-

Oliver Schabenberger

155

Generative Models of Disfluency  

ERIC Educational Resources Information Center

|This thesis describes a generative model for representing disfluent phenomena in human speech. This model makes use of observed syntactic structure present in disfluent speech, and uses a right-corner transform on syntax trees to model this structure in a very natural way. Specifically, the phenomenon of speech repair is modeled by explicitly…

Miller, Timothy A.

2010-01-01

156

Manufacturing modeling and optimization  

Microsoft Academic Search

The purpose of this project was to model and optimize the personnel and equipment utilization in Siltec's Epitaxial manufacturing process. Previous attempts to model the behavior of the process through static models (linear programming and spreadsheets) had not attempted to explain any of the variability experienced in the process line. SIMAN was used to create a simple model to study

D. S. O'Ferrell

1995-01-01

157

RAILWAY NOISE MODEL  

Microsoft Academic Search

The Railway Noise Model (RWNM) was developed at the University of Central Florida and predicts sound levels at receivers near railway operations for analyses used in environmental documents. The RWNM is a simulation model, and trains are modeled as moving point sources of sound. The user can create model objects, tracks, barriers, and receivers, using either the mouse of spreadsheet

John Macdonald; Roger Wayson

1999-01-01

158

MORPHING INSTRUMENT BODY MODELS  

Microsoft Academic Search

In this study we present morphing methods for musical instru- ment body models using DSP techniques. These methods are able to transform a given body model gradually into another one in a controlled way, and they guarantee stability of the body models at each intermediate step. This enables to morph from a certain sized body model to a larger or

Henri Penttinen; Matti Karjalainen

159

Fuzzy Compositional Modeling  

Microsoft Academic Search

Automated modeling refers to automatic (re-)formulation of alternative system models that embody the simplification, abstraction, and approximation of knowledge and data for a given task. This technique is highly desirable for effective problem solving in many application domains. Over the past two decades, compositional modeling (CM) has established itself as a leading approach in automated modeling. CM is a framework

Xin Fu; Qiang Shen

2010-01-01

160

Stable models of superacceleration  

SciTech Connect

We discuss an instability in a large class of models where dark energy is coupled to matter. In these models the mass of the scalar field is much larger than the expansion rate of the Universe. We find models in which this instability is absent, and show that these models generically predict an apparent equation of state for dark energy smaller than -1, i.e., superacceleration. These models have no acausal behavior or ghosts.

Kaplinghat, Manoj; Rajaraman, Arvind [Department of Physics and Astronomy University of California, Irvine, California 92697 (United States)

2007-05-15

161

Models of muscle pain: carrageenan model and acidic saline model.  

PubMed

Carrageenan or acidic saline injected unilaterally into the gastrocnemius muscle or triceps muscle produces a robust and long-lasting hyperalgesia in rats and mice, which is reversible with systemic administration of opioid or anti-inflammatory drugs. This unit describes detailed protocols for inducing and measuring hyperalgesia, and provides information on validation of these models. These models are useful for assessing new compounds for their analgesic activity in muscular pain. PMID:22294122

Radhakrishnan, Rajan; Bement, Marie K Hoeger; Skyba, David; Sluka, Kathleen A; Kehl, Lois J

2004-09-01

162

ADAPT model: Model use, calibration and validation  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper presents an overview of the Agricultural Drainage and Pesticide Transport (ADAPT) model and a case study to illustrate the calibration and validation steps for predicting subsurface tile drainage and nitrate-N losses from an agricultural system. The ADAPT model is a daily time step field ...

163

Model Shrinkage for Discriminative Language Models  

NASA Astrophysics Data System (ADS)

This paper describes a technique for overcoming the model shrinkage problem in automatic speech recognition (ASR), which allows application developers and users to control the model size with less degradation of accuracy. Recently, models for ASR systems tend to be large and this can constitute a bottleneck for developers and users without special knowledge of ASR with respect to introducing the ASR function. Specifically, discriminative language models (DLMs) are usually designed in a high-dimensional parameter space, although DLMs have gained increasing attention as an approach for improving recognition accuracy. Our proposed method can be applied to linear models including DLMs, in which the score of an input sample is given by the inner product of its features and the model parameters, but our proposed method can shrink models in an easy computation by obtaining simple statistics, which are square sums of feature values appearing in a data set. Our experimental results show that our proposed method can shrink a DLM with little degradation in accuracy and perform properly whether or not the data for obtaining the statistics are the same as the data for training the model.

Oba, Takanobu; Hori, Takaaki; Nakamura, Atsushi; Ito, Akinori

164

SIMPLE SNOWDRIFT MODEL FOR DISTRIBUTED HYDROLOGICAL MODELING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Snow transport and deposition can be an important factor in the distribution of spring soil moisture and runoff. Although current hydrological models often attempt to account for heterogeneities in precipitation distribution they do not account for snowdrift effects. A simple snowdrift model was d...

165

MODELLING CHILDREN IN A FAMILY BARGAINING MODEL  

Microsoft Academic Search

We present a two period model, with the child as a public good for the parents. Central to our model is the fact that children need considerable time investment from parents. In the …rst period a couple is married, with a young child. Parents decide on private consumption, total eort to devote to the child, and the division of this

Elisabeth Gugl; Linda Welling

166

Volcanic Ash Dispersion Modeling: The Puff model  

NASA Astrophysics Data System (ADS)

The tracking and forecasting of a volcanic ash clouds movement is critical for providing prompt and accurate volcanic ash advisories. The Puff dispersion model has been developed at the University of Alaska Fairbanks and has been used by the Alaska Volcano Observatory (AVO), since the 1989 Mount Redoubt eruption. The Puff model predicts the moment of an ash cloud, using numerical weather predictions wind fields. Additional information, used as model inputs, includes eruption start time, initial plume height, eruption duration and vertical distribution of the ash cloud. The Puff model can be used for ongoing eruptions and analyzing past events. The model has been developed considerably since its first use in 1989. Now, analysts are able to perform their own volcanic ash cloud forecasts through an online interface and also automated predictions are provided for alert status volcanoes, updated every six hours. The newest addition to the Puff tools is the ability to display the model predictions in three dimensions, using Google Earth. Here, we show the Puff dispersion model, its use by AVO operationally and how the dispersion model has be used to analyze and display the volcanic eruptions in the North Pacific from 1988 - 2008, since the establishment of AVO.

Peterson, R.; Dean, K. G.; Webley, P. W.

2008-12-01

167

PREDICTIVE MODELS. Enhanced Oil Recovery Model  

Microsoft Academic Search

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1 chemical flooding; 2 carbon dioxide miscible flooding; 3

1992-01-01

168

PREDICTIVE MODELS. Enhanced Oil Recovery Model  

Microsoft Academic Search

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1 chemical flooding, where soap-like surfactants are injected into

1992-01-01

169

A model driven approach to model transformations  

Microsoft Academic Search

The OMG's Model Driven Architecture (MDA) initiative has been the focus of much attention in both academia and industry, due to its promise of more rapid and consistent software development through the increased use of models. In order for MDA to reach its full potential, the ability to manipulate and transform mod- els { most obviously from the Platform Independent

Biju Appukuttan; Tony Clark; Sreedhar Reddy; Laurence Tratt

2003-01-01

170

Business Model Innovation: A Process Model  

Microsoft Academic Search

What is business model innovation? A business model is much more than a description of a particular product or service. In addition to describing the offering itself, it lays out the value proposition behind it (i.e., how it creates value for a defined set of customers). It also describes the capabilities and resources needed to execute that value proposition and

Jeanne Liedtka

171

WASP TRANSPORT MODELING AND WASP ECOLOGICAL MODELING  

EPA Science Inventory

A combination of lectures, demonstrations, and hands-on excercises will be used to introduce pollutant transport modeling with the U.S. EPA's general water quality model, WASP (Water Quality Analysis Simulation Program). WASP features include a user-friendly Windows-based interfa...

172

Bayesian Data-Model Fit Assessment for Structural Equation Modeling  

Microsoft Academic Search

Bayesian approaches to modeling are receiving an increasing amount of attention in the areas of model construction and estimation in factor analysis, structural equation modeling (SEM), and related latent variable models. However, model diagnostics and model criticism remain relatively understudied aspects of Bayesian SEM. This article describes and illustrates key features of Bayesian approaches to model diagnostics and assessing data–model

Roy Levy

2011-01-01

173

Linear Glauber model  

NASA Astrophysics Data System (ADS)

We study the time-dependent and the stationary properties of the linear Glauber model in a d-dimensional hypercubic lattice. This model is equivalent to the voter model with noise. By using the Green function method, we get exact results for the two-point correlations from which the critical behavior is obtained. For vanishing noise the model becomes critical with exponents ?=0, ?=1, and ?=1/2 for d?2, with logarithmic corrections at the upper critical dimension dc=2, and ?=0, ?=1/2, and ?=1/2 for d=1. We show that the model can be mapped into a particular reaction-diffusion model.

de Oliveira, Mário J.

2003-06-01

174

Energy-consumption modelling  

SciTech Connect

A highly sophisticated and accurate approach is described to compute on an hourly or daily basis the energy consumption for space heating by individual buildings, urban sectors, and whole cities. The need for models and specifically weather-sensitive models, composite models, and space-heating models are discussed. Development of the Colorado State University Model, based on heat-transfer equations and on a heuristic, adaptive, self-organizing computation learning approach, is described. Results of modeling energy consumption by the city of Minneapolis and Cheyenne are given. Some data on energy consumption in individual buildings are included.

Reiter, E.R.

1980-01-01

175

SAM EMP (SEMP) model  

SciTech Connect

The Surface-To-Air Missile (SAM) Electro-Magnetic-Pulse (EMP) (SEMP) model simulates the illumination of an entire SAM brigade with an EMP weapon. It computes probability distributions of SAM brigade performance levels after an EMP attack has occurred. Brigade performance is determined by the combination of components that survive the EMP. Accordingly, the SEMP model is separated into the component failure model and the condition model. The component failure model computes the failure probability of each component in the brigade from data supplied by two input data files. The condition model converts component failure probabilities into brigade performance in the form of missile availability probability tables.

Thatcher, R.M.

1984-05-01

176

Modeling volatility using state space models.  

PubMed

In time series problems, noise can be divided into two categories: dynamic noise which drives the process, and observational noise which is added in the measurement process, but does not influence future values of the system. In this framework, we show that empirical volatilities (the squared relative returns of prices) exhibit a significant amount of observational noise. To model and predict their time evolution adequately, we estimate state space models that explicitly include observational noise. We obtain relaxation times for shocks in the logarithm of volatility ranging from three weeks (for foreign exchange) to three to five months (for stock indices). In most cases, a two-dimensional hidden state is required to yield residuals that are consistent with white noise. We compare these results with ordinary autoregressive models (without a hidden state) and find that autoregressive models underestimate the relaxation times by about two orders of magnitude since they do not distinguish between observational and dynamic noise. This new interpretation of the dynamics of volatility in terms of relaxators in a state space model carries over to stochastic volatility models and to GARCH models, and is useful for several problems in finance, including risk management and the pricing of derivative securities. Data sets used: Olsen & Associates high frequency DEM/USD foreign exchange rates (8 years). Nikkei 225 index (40 years). Dow Jones Industrial Average (25 years). PMID:9730016

Timmer, J; Weigend, A S

1997-08-01

177

Reducing Model Systematic Error through Super Modelling  

NASA Astrophysics Data System (ADS)

Numerical models are key tools in the projection of the future climate change. However, state-of-the-art general circulation models (GCMs) exhibit significant systematic errors and large uncertainty exists in future climate projections, because of limitations in parameterization schemes and numerical formulations. The general approach to tackle uncertainty is to use an ensemble of several different GCMs. However, ensemble results may smear out major variability, such as the ENSO. Here we take a novel approach and build a super model (i.e., an optimal combination of several models): We coupled two atmospheric GCMs (AGCM) with one ocean GCM (OGCM). The two AGCMs receive identical boundary conditions from the OGCM, while the OGCM is driven by a weighted flux combination from the AGCMs. The atmospheric models differed in their convection scheme and climate-related parameters. As climate models show large sensitivity to convection schemes and parameterization, this approach may be a good basis for constructing a super model. We performed experiments with a small set of manually chosen coefficients and also with a learning algorithm to adjust the coefficients. The coupling strategy is able to synchronize atmospheric variability of the two AGCMs in the tropics, particularly over the western equatorial Pacific, and produce reasonable climate variability. Different coupling weights were shown to alter the simulated mean climate state. Some improvements were found that suggest a refined strategy for choosing weighting coefficients could lead to even better performance.

Shen, Mao-Lin; Keenlyside, Noel; Selten, Frank; Duane, Gregory; Wiegerinck, Wim; Hiemstra, Paul

2013-04-01

178

Generalized multilevel structural equation modeling  

Microsoft Academic Search

A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent variables. The response model generalizes GLMMs to incorporate factor structures

Sophia Rabe-Hesketh; Anders Skrondal; Andrew Pickles

2004-01-01

179

Nature of Modeling.  

National Technical Information Service (NTIS)

This chapter attempts to define modeling precisely. It surveys the kinds of models human beings use and discusses their motivations, advantages, and limitations. It places simulation in this context and surveys various kinds of computerized simulation. It...

J. Rothenberg

1989-01-01

180

Supersymmetry and model building  

SciTech Connect

An introductory review of supersymmetry and supersymmetric model building is presented. The topics discussed include, a brief introduction to the formalism of supersymmetry, the gauge hierarchy problem, the minimal supersymmetric standard model and supersymmetric grand unified theories.

Raby, S.

1986-06-01

181

Exposure Analysis Modeling System  

EPA Science Inventory

The Exposure Analysis Modeling System (EXAMS) is an interactive software application for formulating aquatic ecosystem models and evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals including pesticides, industrial materials, and leachates f...

182

Digital Troposcatter Performance Model.  

National Technical Information Service (NTIS)

The development of a computer prediction model for digital troposcatter communication system design is described. Propagation and modem performance are modeled. These include Path Loss and RSL distributions for troposcatter propagation and mixed troposcat...

A. Malaga J. Fetteroll P. Monsen S. Parl S. Tolman

1983-01-01

183

Visualization of Model Output  

NSDL National Science Digital Library

Visualization of output from mathematical or statistical models is one of the best ways to introduce introductory geoscience students to the results and behavior of sophisticated models. Example of good sites ...

184

Computer modeling of detonators.  

National Technical Information Service (NTIS)

A mathematical model of detonators which describes the resistance of the exploding bridgewire or exploding foil initiator as a function of energy deposition will be described. This model includes many parameters that can be adjusted to obtain a close fit ...

C. M. Furnberg

1994-01-01

185

Smart Weapons Encounter Model.  

National Technical Information Service (NTIS)

This report covers the Smart Weapon Encounter Model (SWEM) developed to support the Tank Extended Range Munition (TERM) science and technology objective (STO) III G.3. The report describes the model's algorithm, input, and Output. SWEM uses solid geometry...

R. J. Pearson K. K. Chien

2000-01-01

186

Launch Abort Chemistry Model.  

National Technical Information Service (NTIS)

Computer models provide a framework for better understanding of complex phenomena. Events such as launch aborts are rare, and detailed field information about the chemical load they introduce into the atmosphere is rare. A good model will make predictions...

B. B. Brady A. McIlroy L. R. Martin

1997-01-01

187

Make a DNA Model  

NSDL National Science Digital Library

In this activity, learners make a 3-D model of DNA using paper and toothpicks. While constructing this model, learners will explore the composition and structure of DNA. The activity also gives suggestions for alternate materials and challenges to explore.

History, American M.

2012-06-26

188

Viscoelastic Finite Difference Modeling.  

National Technical Information Service (NTIS)

Real earth media disperse and attenuate propagating waves. This anelastic behavior can be well described by a viscoelastic model. We have developed a finite difference simulator to model wave propagation in viscoelastic media. The finite difference method...

J. O. Blanch J. O. Robertsson W. W. Symes

1993-01-01

189

Manpower Allocation Model Survey.  

National Technical Information Service (NTIS)

The report contains a separate study of each of three mathematical manpower models and a comparative evaluation of each with the Manpower Allocation Model (MAM) developed by the Mellonics Systems Development Division.

1970-01-01

190

Melanoma Risk Prediction Models  

Cancer.gov

The following risk prediction models are intended primarily for research use and have been peer-reviewed, meaning the methodology and results of these models have been evaluated by qualified scientists and clinicians and published in scientific and medical journals.

191

Modeling Fluid Structure Interaction.  

National Technical Information Service (NTIS)

The principal goal of this program is on integrating experiments with analytical modeling to develop physics-based reduced-order analytical models of nonlinear fluid-structure interactions in articulated naval platforms. The critical research path for thi...

H. Benaroya T. Wei

2000-01-01

192

Model Cloud Relationships.  

National Technical Information Service (NTIS)

Contents: Radar Reflectivity Studies; Three-Dimensional Cloud/Mesoscale Model Investigations of Potential Aircraft Icing Regions; Inclusion of Ice Processes in the One-Dimensional Cloud/Turbulence Model.

W. R. Cotton E. E. Hindman G. Tripoli R. L. McAnelly C. Chen

1983-01-01

193

Dengue Transfusion Risk Model  

Center for Biologics Evaluation and Research (CBER)

Text VersionDengue Transfusion Risk Model. Lyle R. Petersen, MD, MPH. ... D s = Duration of viremia before symptoms develop. Dengue Risk Model Variables. ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

194

The interacting boson model  

SciTech Connect

This chapter examines the algebraic and geometric properties of the interacting boson model-1, and reviews the interacting boson model-2. Explains that the model was originally introduced with only one kind of collective boson variable with angular momentum J=O and J=2 (the interacting boson model-1), and subsequently, a more elaborate version was introduced with two kinds of collective variables, proton bosons and neutron bosons (the interacting boson model-2). Discusses analytic solutions, transitional classes, extensions of the models, coherent states, transitional classes and shape-phase transitions, energy levels, electromagnetic transition rates, other properties, a microscopic description of interacting bosons, generalized seniority, the single j-shell, several j-shells, and the Ginocchio model. Excludes odd-even nuclei and the corresponding interacting boson-fermion models 1 and 2 from the review.

Arima, A.; Iachello, F.

1984-01-01

195

Target Temperature Modeling.  

National Technical Information Service (NTIS)

A computerized mathematical model for the prediction of time-dependent surface temperatures and radiances of planar targets and backgrounds has been formulated. The model accounts for the effects of (1) solar insulation, (2) radiative transfer, (3) natura...

D. Bornemeier R. Bennett R. Horvath

1969-01-01

196

Network Models of Crystals.  

National Technical Information Service (NTIS)

The subject matter of the research on this contract has been two-fold: (1) network models for electrons in solids (2) stochastic models of transport in amorphous materials. A list of publications is included.

E. W. Montroll

1974-01-01

197

Introduction to Modeling (SAM)  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students are introduced to "key characteristics of 2D and 3D models as they are created and used in the Molecular Workbench Software. It ranges from 2D modeling of a superball to roving through 3-D molecules." The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In the activity, students are allowed to explore at their own pace in a digital environment full of demonstrations, illustrations, and models they can manipulate. The content of the module is divided into seven pages: Designing a computer model, Running and visualizing the model, Extended visualization, Annotation and sharing, Using the model to do experiments, Modeling an atom, and 3D static models. In addition to the activity, visitors will find an overview of the activity and details of the central concepts.

2008-12-08

198

Preclinical Models of Depression.  

National Technical Information Service (NTIS)

New animal models of human depression, especially endogenous depression, were developed. Depression was induced by means other than drugs. The model was validated by behavioral, neuroendocrine and neurochemical resemblances to the human disorder and by re...

B. J. Carroll

1983-01-01

199

Modeling Gust in Model Reduction Framework  

NASA Astrophysics Data System (ADS)

Determining gust effects on fluid flows and fluid structure interactions is important in many applications. Direct numerical simulations of these effects may be very expensive. This is especially true in cases where gust parameters could vary. The overall goal of this effort is to develop tools and reduced-order models that are capable of assessing gust effects and that can be used for flow control or uncertainty quantification of flow parameters. As such, we simulate the flow past a circular cylinder with and without an incoming gust. Proper orthogonal decomposition (POD) is performed on the simulated flow data to compute the dominant basis functions (modes) using the method of snapshots. The results show that reduced-order models from steady flow cannot be readily used to develop reduced-order models for the same flow with incoming gust. Methodologies to incorporate gust effect within the reduced-order model are discussed.

Ghommem, Mehdi; Akhtar, Imran; Hajj, Muhammad; Puri, Ishwar

2009-11-01

200

Current animal models: cotton rat animal model.  

PubMed

The cotton rat (Sigmodon hispidus) model has proven to be a suitable small animal model for measles virus pathogenesis to fill the niche between tissue culture and studies in macaques. Similar to mice, inbred cotton rats are available in a microbiologically defined quality with an ever-increasing arsenal of reagents and methods available for the study of infectious diseases. Cotton rats replicate measles virus in the respiratory tract and (depending on virus strain) in lymphoid organs. They can be infected with vaccine, wild-type, and recombinant measles viruses and have been used to study viruses with genetic modifications. Other areas of study include efficacy testing of antivirals and vaccines. The cotton rat also has been an informative animal model to investigate measles virus-induced immune suppression and suppression of vaccination by maternal antibodies. In addition, the cotton rat promises to be a useful model for the study of polymicrobial disease (interaction between measles virus and secondary pathogens). PMID:19203106

Niewiesk, S

2009-01-01

201

Models and Their Adaptation  

Microsoft Academic Search

\\u000a This chapter describes computer simulation models developed for ­estimating greenhouse gas fluxes of different ecosystems.\\u000a In general, each model is used for the simulation of specific parts of the complex systems; therefore, merging the results\\u000a of various kind of models can give a better insight. In this chapter, we describe four models used for estimating biospheric\\u000a fluxes of greenhouse gases

Zoltán Somogyi; Dóra Hidy; Györgyi Gelybó; Zoltán Barcza; Galina Churkina; László Haszpra; László Horváth; Attila Machon; Balázs Grosz

202

Linear Glauber model  

Microsoft Academic Search

We study the time-dependent and the stationary properties of the linear Glauber model in a d-dimensional hypercubic lattice. This model is equivalent to the voter model with noise. By using the Green function method, we get exact results for the two-point correlations from which the critical behavior is obtained. For vanishing noise the model becomes critical with exponents beta=0, gamma=1,

Mário J. de Oliveira

2003-01-01

203

Calibrated Properties Model  

SciTech Connect

The purpose of this Model Report is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Office of Repository Development (ORD). The UZ contains the unsaturated rock layers overlying the repository and host unit, which constitute a natural barrier to flow, and the unsaturated rock layers below the repository which constitute a natural barrier to flow and transport. This work followed, and was planned in, ''Technical Work Plan (TWP) for: Performance Assessment Unsaturated Zone'' (BSC 2002 [160819], Section 1.10.8 [under Work Package (WP) AUZM06, Climate Infiltration and Flow], and Section I-1-1 [in Attachment I, Model Validation Plans]). In Section 4.2, four acceptance criteria (ACs) are identified for acceptance of this Model Report; only one of these (Section 4.2.1.3.6.3, AC 3) was identified in the TWP (BSC 2002 [160819], Table 3-1). These calibrated property sets include matrix and fracture parameters for the UZ Flow and Transport Model (UZ Model), drift seepage models, and drift-scale and mountain-scale coupled-process models from the UZ Flow, Transport and Coupled Processes Department in the Natural Systems Subproject of the Performance Assessment (PA) Project. The Calibrated Properties Model output will also be used by the Engineered Barrier System Department in the Engineering Systems Subproject. The Calibrated Properties Model provides input through the UZ Model and other process models of natural and engineered systems to the Total System Performance Assessment (TSPA) models, in accord with the PA Strategy and Scope in the PA Project of the Bechtel SAIC Company, LLC (BSC). The UZ process models provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic and thermal-loading conditions. UZ flow is a TSPA model component.

J. Wang

2003-06-24

204

Spatial Structure: Patch Models  

Microsoft Academic Search

Discrete spatial heterogenity is introduced into disease transmission models, resulting in large systems of ordinary differential\\u000a equations. Such metapopulation models describe disease spread on a number of spatial patches. In the first model considered,\\u000a there is no explicit movement of individuals; rather infectives can pass the disease to susceptibles in other patches. The\\u000a second type of model explicitly includes rates

P. van den Driessche

205

Big toy models  

Microsoft Academic Search

We pursue a model-oriented rather than axiomatic approach to the foundations of Quantum Mechanics, with the idea that new\\u000a models can often suggest new axioms. This approach has often been fruitful in Logic and Theoretical Computer Science. Rather\\u000a than seeking to construct a simplified toy model, we aim for a ‘big toy model’, in which both quantum and classical systems

Samson Abramsky

206

Posterior shape models.  

PubMed

We present a method to compute the conditional distribution of a statistical shape model given partial data. The result is a "posterior shape model", which is again a statistical shape model of the same form as the original model. This allows its direct use in the variety of algorithms that include prior knowledge about the variability of a class of shapes with a statistical shape model. Posterior shape models then provide a statistically sound yet easy method to integrate partial data into these algorithms. Usually, shape models represent a complete organ, for instance in our experiments the femur bone, modeled by a multivariate normal distribution. But because in many application certain parts of the shape are known a priori, it is of great interest to model the posterior distribution of the whole shape given the known parts. These could be isolated landmark points or larger portions of the shape, like the healthy part of a pathological or damaged organ. However, because for most shape models the dimensionality of the data is much higher than the number of examples, the normal distribution is singular, and the conditional distribution not readily available. In this paper, we present two main contributions: First, we show how the posterior model can be efficiently computed as a statistical shape model in standard form and used in any shape model algorithm. We complement this paper with a freely available implementation of our algorithms. Second, we show that most common approaches put forth in the literature to overcome this are equivalent to probabilistic principal component analysis (PPCA), and Gaussian Process regression. To illustrate the use of posterior shape models, we apply them on two problems from medical image analysis: model-based image segmentation incorporating prior knowledge from landmarks, and the prediction of anatomically correct knee shapes for trochlear dysplasia patients, which constitutes a novel medical application. Our experiments confirm that the use of conditional shape models for image segmentation improves the overall segmentation accuracy and robustness. PMID:23837968

Albrecht, Thomas; Lüthi, Marcel; Gerig, Thomas; Vetter, Thomas

2013-06-15

207

Mathematical models of hysteresis  

NASA Astrophysics Data System (ADS)

Progress is reported in 7 areas: development of vector Preisach-type models of hysteresis; modeling of rotational hysteretic losses; experimental testing of generalized vector Preisach models of hysteresis; development of Preisach-type models for after-effect; analytical investigation of penetration of electromagnetic fields into superconductors with gradual resistive transitions; computation of magnetic fields in hysteretic media; and development of new techniques for calculating 3-D eddy current problems.

Mayergoyz, I. D.

1993-09-01

208

Generalized Additive Models  

Microsoft Academic Search

Likelihood-based regression models such as the normal linear regression model and the linear logistic model, assume a linear (or some other parametric) form for the covariates $X_1, X_2, \\\\cdots, X_p$. We introduce the class of generalized additive models which replaces the linear form $\\\\sum \\\\beta_jX_j$ by a sum of smooth functions $\\\\sum s_j(X_j)$. The $s_j(\\\\cdot)$'s are unspecified functions that are

Trevor Hastie; Robert Tibshirani

1986-01-01

209

Bootstrap model selection in generalized linear models  

Microsoft Academic Search

Model selection is a central component of data analysis. Though there are a variety of methods for likelihood-based estimation\\u000a methods, there are relatively few for non-likelihood-based generalized linear models (GLMs), such as in the quasi-likelihood\\u000a and generalized estimating equation (GEE) approaches. In this paper, we develop basic and bias-corrected bootstrap approaches\\u000a to estimate the predictive mean squared error (PMSE) of

Wei Pan; Chap T. Le

2001-01-01

210

Solid Waste Projection Model: Model user's guide  

SciTech Connect

The Solid Waste Projection Model (SWPM) system is an analytical tool developed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford company (WHC) specifically to address solid waste management issues at the Hanford Central Waste Complex (HCWC). This document, one of six documents supporting the SWPM system, contains a description of the system and instructions for preparing to use SWPM and operating Version 1 of the model. 4 figs., 1 tab.

Stiles, D.L.; Crow, V.L.

1990-08-01

211

PREDICTIVE MODELS. Enhanced Oil Recovery Model  

SciTech Connect

PREDICTIVE MODELS is a collection of five models - CFPM, CO2PM, ICPM, PFPM, and SFPM - used in the 1982-1984 National Petroleum Council study of enhanced oil recovery (EOR) potential. Each pertains to a specific EOR process designed to squeeze additional oil from aging or spent oil fields. The processes are: 1 chemical flooding, where soap-like surfactants are injected into the reservoir to wash out the oil; 2 carbon dioxide miscible flooding, where carbon dioxide mixes with the lighter hydrocarbons making the oil easier to displace; 3 in-situ combustion, which uses the heat from burning some of the underground oil to thin the product; 4 polymer flooding, where thick, cohesive material is pumped into a reservoir to push the oil through the underground rock; and 5 steamflood, where pressurized steam is injected underground to thin the oil. CFPM, the Chemical Flood Predictive Model, models micellar (surfactant)-polymer floods in reservoirs, which have been previously waterflooded to residual oil saturation. Thus, only true tertiary floods are considered. An option allows a rough estimate of oil recovery by caustic or caustic-polymer processes. CO2PM, the Carbon Dioxide miscible flooding Predictive Model, is applicable to both secondary (mobile oil) and tertiary (residual oil) floods, and to either continuous CO2 injection or water-alternating gas processes. ICPM, the In-situ Combustion Predictive Model, computes the recovery and profitability of an in-situ combustion project from generalized performance predictive algorithms. PFPM, the Polymer Flood Predictive Model, is switch-selectable for either polymer or waterflooding, and an option allows the calculation of the incremental oil recovery and economics of polymer relative to waterflooding. SFPM, the Steamflood Predictive Model, is applicable to the steam drive process, but not to cyclic steam injection (steam soak) processes.

Ray, R.M. [DOE Bartlesville Energy Technology Technology Center, Bartlesville, OK (United States)

1992-02-26

212

Current Animal Models: Cotton Rat Animal Model  

Microsoft Academic Search

The cotton rat ( Sigmodon hispidus ) model has proven to be a suitable small animal model for measles virus pathogenesis to fill the niche between tissue culture\\u000a and studies in macaques. Similar to mice, inbred cotton rats are available in a microbiologically defined quality with an\\u000a ever-increasing arsenal of reagents and methods available for the study of infectious diseases.

S. Niewiesk

213

Bayesian Model Comparison of Structural Equation Models  

Microsoft Academic Search

\\u000a Structural equation modeling is a multivariate method for establishing meaningful models to investigate the relationships\\u000a of some latent (causal) and manifest (control) variables with other variables. In the past quarter of a century, it has drawn\\u000a a great deal of attention in psychometrics and sociometrics, both in terms of theoretical developments and practical applications\\u000a (see Bentler and Wu, 2002; Bollen,

Sik-Yum Lee; Xin-Yuan Song

214

Anticipated model consequences, model affect, and imitation  

Microsoft Academic Search

60 3rd and 4th graders individually observed a videotaped adult who either encouraged or prohibited a model's play with toys while he was gone; after the adult's departure, the model performed 6 distinctive play behaviors and exhibited a grin, frown, or blank stare following each play response. Analysis of variance revealed that anticipated-reward Ss surpassed anticipated-punishment Ss on 4 measures:

Stephen J. Dollinger; Mark H. Thelen

1975-01-01

215

EconModel  

NSDL National Science Digital Library

This site contains 21 modular, easy to use economic models, that are appropriate for class assignments or in-class demonstrations. Students can simulate all the standard models taught in most economics courses. EconModel uses the Windows OS. The simulations were developed by William R. Parke of the University of North Carolina at Chapel Hill.

Blecha, Betty J.

216

EXPOSURE MODELING - SHEDS  

EPA Science Inventory

This presentation provides a general overview of SHEDS model features, describes algorithms in the SHEDS-Air Toxics model that focus on mobile source exposures and multipathway exposures, and presents examples of results from application of the SHEDS-Air Toxics model to benzene i...

217

IR DIAL performance modeling  

SciTech Connect

We are developing a DIAL performance model for CALIOPE at LLNL. The intent of the model is to provide quick and interactive parameter sensitivity calculations with immediate graphical output. A brief overview of the features of the performance model is given, along with an example of performance calculations for a non-CALIOPE application.

Sharlemann, E.T.

1994-07-01

218

Surface complexation modeling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Adsorption-desorption reactions are important processes that affect the transport of contaminants in the environment. Surface complexation models are chemical models that can account for the effects of variable chemical conditions, such as pH, on adsorption reactions. These models define specific ...

219

Calibrated Properties Model  

Microsoft Academic Search

The purpose of this Model Report is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Office of Repository Development (ORD). The UZ contains the unsaturated rock layers overlying the repository and host unit, which constitute a natural barrier to flow, and the unsaturated rock layers below

J. Wang

2003-01-01

220

Modeling and Remodeling Writing  

ERIC Educational Resources Information Center

|In Section 1 of this article, the author discusses the succession of models of adult writing that he and his colleagues have proposed from 1980 to the present. He notes the most important changes that differentiate earlier and later models and discusses reasons for the changes. In Section 2, he describes his recent efforts to model young…

Hayes, John R.

2012-01-01

221

Multilevel covariance component models  

Microsoft Academic Search

SUMMARY A straightforward extension to the multilevel linear model with nested covariance components is described. This allows the specification and efficient estimation of a very general mixed linear model with both crossed and nested covariance components. Goldstein (1986) describes the analysis of the multilevel mixed effects linear model with random coefficients, where the variance and covariance components have a nested

H. GOLDSTEIN

1987-01-01

222

A suicide epidemic model  

Microsoft Academic Search

An epidemic model of suicides clustered in time and space is presented. In this model suicides are depicted as an infection that can be spread from person to person. The model is based on the assumption that spread of suicide ideation via various means of communication increases as the number of suicides increases. A threshold condition for an epidemic to

Barry R. Davis; Robert J. Hardy

1986-01-01

223

REGULATORY AIR QUALITY MODELS  

EPA Science Inventory

Appendix W to 40CFR Part 51 (Guideline on Air Quality Models) specifies the models to be used for purposes of permitting, PSD, and SIPs. Through a formal regulatory process this modeling guidance is periodically updated to reflect current science. In the most recent action, thr...

224

Practicing modelling in manufacturing  

Microsoft Academic Search

This paper is about understanding modelling practices in manufacturing and contribute in methodologies and approaches facilitating introduction of modelling in a company. Based on ethnographic studies at real work environments and scenario-building workshops, we could identify and analyse several issues like how to involve and engage domain workers in modelling activities, that there are four different levels of formal and

H. Tellioglu

2009-01-01

225

An uncertain regression model  

Microsoft Academic Search

Purpose – The purpose of this paper is to propose an uncertain regression model with an intrinsic error structure facilitated by an uncertain canonical process. Design\\/methodology\\/approach – This model is suitable for dealing with expert's knowledge ranging from small to medium size data of impreciseness. In order to have a rigorous mathematical treatment on the new regression model, this paper

Renkuan Guo; Danni Guo; YanHong Cui

2011-01-01

226

Reexamining Community Corrections Models  

Microsoft Academic Search

Historically, community corrections has been based on models of diversion, advocacy, and reintegration. Increases in crime and more high-risk offenders being sentenced to probation have led to emphases on control and surveillance, and “just deserts,” adversary, and restitution models have replaced the original models. The author argues for strategies of internalization, reintegrative shaming, and victim-offender reconciliation for a comprehensive community

Richard Lawrence

1991-01-01

227

On solvable boson models  

SciTech Connect

The problem of equilibrium states and/or ground states of exactly solvable homogeneous boson models is stated and explicitly proved as a special case of the general variational problem of statistical mechanics in terms of quasifree states. We apply the result to a model of super-radiant Bose-Einstein condensation and to the pairing boson model.

Pule, Joe V. [School of Mathematical Sciences, University College Dublin, Belfield, Dublin 4 (Ireland); Verbeure, Andre F. [Instituut voor Theoretische Fysica, K.U. Leuven, B-3000 Leuven (Belgium); Zagrebnov, Valentin A. [Universite de la Mediterranee Centre de Physique Theorique-UMR 6207, Luminy-Case 907, 13288 Marseille, Cedex 09 (France)

2008-04-15

228

Mathematical models of hysteresis  

Microsoft Academic Search

A new approach to Preisach's hysteresis model, which emphasizes its phenomenological nature and mathematical generality, is briefly described. Then the theorem which gives the necessary and sufficient conditions for the representation of actual hysteresis nonlinearities by Preisach's model is proven. The significance of this theorem is that it establishes the limits of applicability of this model.

I. Mayergoyz

1986-01-01

229

Generic sonar Model  

Microsoft Academic Search

The Generic Sonar Model is a computer program designed to provide sonar system developers with a comprehensive modeling capability for evaluating the performance of sonar systems and investigating the ocean environment in which they operate. The model provides features not presently available in any single computer program. These permit cost\\/accuracy trade-offs for specific applications, and interfacing the results with generalized

H. Weinberg

1982-01-01

230

The Model Neuron  

NSDL National Science Digital Library

In this activity, learners create a model of a neuron by using colored clay or play dough. Learners use diagrams to build the model and then label the parts on a piece of paper. This resource guide includes extension ideas like using fruit or candy instead of clay. See the "Modeling the Nervous System" page for a recipe for play dough.

Chudler, Eric

2009-01-01

231

Model magnet studies  

Microsoft Academic Search

A design, construction, and testing program for model magnets is underway at Fermilab to evaluate alternatives in the development of small aperture magnets. The most thoroughly developed of these programs utilizes a set of model magnets based on the Tevatron quadrupoles and dipoles as a standard. These 7.6cm aperture model magnets, approximately 64cm long, have construction or material changes which

A. D. McInturff; J. Carson; N. Engler; H. Fisk; R. Hanft; R. Lundy; P. Mantsch; T. Nicol; R. Niemann; E. Schmidt; A. Szymulanski

1985-01-01

232

Modeling Industry Political Dynamics  

Microsoft Academic Search

The purpose of this article is to extend from the business and society research focus on corporate political strategy and to factor this emphasis into business strategy thinking. The approach taken is to incorporate business and society concepts into a model that parallels Michael Porter's well-known Five Forces Model of business strategy. The applicability of the parallel model for practitioners

John F. Mahon; Richard A. McGowan

1998-01-01

233

How effective are models?  

Microsoft Academic Search

This article discusses a number of common interpretations of 'implementation' in the literature, and how these have been confused. Various different levels of implementation are then discussed, including the concept of model effectiveness. This is concerned with both the operational effectiveness of the model, as shown by a tangible improvement in the system modelled, and the personal effectiveness in helping

John Fripp

1985-01-01

234

Crushed Salt Constitutive Model  

SciTech Connect

The constitutive model used to describe the deformation of crushed salt is presented in this report. Two mechanisms -- dislocation creep and grain boundary diffusional pressure solution -- are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. Upon complete consolidation, the crushed-salt model reproduces the Multimechanism Deformation (M-D) model typically used for the Waste Isolation Pilot Plant (WIPP) host geological formation salt. New shear consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on WIPP and southeastern New Mexico salt. Nonlinear least-squares model fitting to the database produced two sets of material parameter values for the model -- one for the shear consolidation tests and one for a combination of the shear and hydrostatic consolidation tests. Using the parameter values determined from the fitted database, the constitutive model is validated against constant strain-rate tests. Shaft seal problems are analyzed to demonstrate model-predicted consolidation of the shaft seal crushed-salt component. Based on the fitting statistics, the ability of the model to predict the test data, and the ability of the model to predict load paths and test data outside of the fitted database, the model appears to capture the creep consolidation behavior of crushed salt reasonably well.

Callahan, G.D.

1999-02-01

235

Interaction and Intervention Modeling  

Microsoft Academic Search

PURPOSE: Methods called interaction and intervention modeling are presented. Interaction modeling examines the interactions between variables as the basis for predicting the impact of multiple variables on a target population and on populations with difference distributions of risk factors. Intervention modeling incorporates these interactions and aims to extrapolate the impact of multiple interventions to new populations. The aim is to

Richard Riegelman; Dante Verme; James Rochon; Ayman El-Mohandes

2002-01-01

236

MPP Fortran Programming Model  

Microsoft Academic Search

This report describes the MPP Fortran programming model which will be supported on the first phaseMPP systems. Based on existing and proposed standards, it is a work sharing model which combinesfeatures from existing models in a way that may be both efficiently implemented and useful.

Douglas M. Pase; Tom MacDonald; Andrew Meltzer

1992-01-01

237

Models and theories  

Microsoft Academic Search

Economic theories are systems of beliefs about the world. Models formalize parts or aspects of theories but leave much of their content out. An example of a component of theories not contained in models are the instructions for how to proceed when a model fails (in Lakatos’ terms the ‘positive heuristic’). Mathematization gives precision of statement but not of empirical

Axel Leijonhufvud

1997-01-01

238

Model transformations in MT  

Microsoft Academic Search

Model transformations are recognised as a vital aspect of Model Driven Development, but current approaches cover only a small part of the possible spectrum. In this paper I present the MT model transformation which shows how a QVT-like language can be extended with novel pattern matching constructs, how tracing information can be automatically constructed and visualized, and how the transformed

Laurence Tratt

2007-01-01

239

Tests of Rating Models  

ERIC Educational Resources Information Center

The study reports empirical tests of Anderson's, Haubensak's, Helson's, and Parducci's rating models when two end anchors are used for rating. The results show that these models cannot predict the judgment effect called here the Dai Pra effect. It is shown that an extension of Anderson's model is consistent with this effect. The results confirm…

Masin, Sergio Cesare; Busetto, Martina

2010-01-01

240

Bioeconomic and market models  

Microsoft Academic Search

5 Abstract: The United States has a century of experience with the development of models that describe markets for forest products and trends in resource conditions. In the last four decades, increasing rigor in policy debates has stimulated the development of models to support policy analysis. Increasingly, research has evolved (often relying on computer-based models) to increase understanding of consumer

Richard Haynes; Darius Adams; Peter Ince; John Mills; Ralph Alig

241

Vestibular postural control model  

Microsoft Academic Search

Current models for physiological components and a posture control experiment conducted with three normal subjects form the basis for a model which seeks to describe quantitatively the control of body sway when only vestibular motion cues are used. Emphasis is placed on delineating the relative functional roles of the linear and the angular acceleration sensors and on modeling the functional

Lewis M. Nashner

1972-01-01

242

Lightning Return Stroke Models  

Microsoft Academic Search

We test the two most commonly used lightning return stroke models, Bruce-Golde and trammission line, against subsequent stroke electric and magnetic field wave forms measured simultaneously at near and distant stations and show that these models are inadequate to describe the experimental data. We then propose a new return stroke model that is physically plausible and that yields good approximations

Y. T. Lin; M. A. Uman; R. B. Standler

1980-01-01

243

Elementary Teacher Training Models.  

ERIC Educational Resources Information Center

|This collection of articles contains descriptions of nine elementary teacher training program models conducted at universities throughout the United States. The articles include the following: (a) "The University of Toledo Model Program," by George E. Dickson; (b) "The Florida State University Model Program," by G. Wesley Sowards; (c) "The…

Blewett, Evelyn J., Ed.

244

MODAL AEROSOL DYNAMICS MODEL  

EPA Science Inventory

The Modal Aerosol Dynamics (MAD) model is a computationally efficient model for solving the General Dynamics Equation of Aerosols (GDE) (Friedlander, 1977). The simplifying assumption in the model is that aerosol size distributions can be approximated by overlapping modes, each r...

245

Dependability and security models  

Microsoft Academic Search

There is a need to quantify system properties methodically. Dependability and security models have evolved nearly independently. Therefore, it is crucial to develop a classification of dependability and security models which can meet the requirement of professionals in both fault-tolerant computing and security community. In this paper, we present a new classification of dependability and security models. First we present

Kishor S. Trivedi; Dong Seong Kim; Arpan Roy; Deep Medhi

2009-01-01

246

Modeling Natural Selection  

ERIC Educational Resources Information Center

In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

Bogiages, Christopher A.; Lotter, Christine

2011-01-01

247

Disease Epidemic Model  

NSDL National Science Digital Library

This model can be used to create a virtual population to observe how different factors might affect the spread of a disease. Scientists often use computer models to study complicated phenomena like epidemics. This model is a simplified simulation of any disease that is spread through human contact.

Shodor

248

Boys Town Education Model.  

ERIC Educational Resources Information Center

This monograph describes the curriculum and teaching methods used to teach socialization skills at the Boys Town (Nebraska) special residential school for boys with behavioral disorders as well as replications of the Boys Town model in other locations. The model takes the basic techniques of the schools's Family/Home model and applies them to…

Wells, Patricia L.

249

Shape Modeling Using Homotopy  

Microsoft Academic Search

Introduces a new method of shape modeling using homotopy and object-oriented modeling. Homotopy is a kind of topology that gives more general ideas of presenting invariant properties of geometrical objects and is further expanded to conceptual objects. The conventional shape modeling method, using polygonalization, has serious difficulties in preserving invariant properties, leading to the necessity of a massive amount of

Kenji Ohmori; Tosiyasu L. Kunii

2001-01-01

250

Active Appearance Models  

Microsoft Academic Search

We describe a new method of matching statistical models of appearance to images. A set of model parameters control modes of shape and gray-level variation learned from a training set. We construct an efficient iterative matching algorithm by learning the relationship between perturbations in the model parameters and the induced image errors

Timothy F. Cootes; Gareth J. Edwards; Christopher J. Taylor

2001-01-01

251

Physical Modeling Synthesis Update  

Microsoft Academic Search

Recent research in physical modeling of musical instruments for purposes of sound synthesis is reviewed. Recent references, results, and outstanding problems are highlighted for models of strings, winds, brasses, percussion, and acoustic spaces. Emphasis is placed on digital waveguide models and the musical acoustics research on which they are based.

Julius O. Smith

1996-01-01

252

Computational Models of Neuromodulation  

Microsoft Academic Search

Computational modeling of neural substrates provides an excellent the- oretical framework for the understanding of the computational roles of neuromodulation. In this review, we illustrate, with a large number of modeling studies, the specific computations performed by neuromodula- tion in the context of various neural models of invertebrate and vertebrate preparations. We base our characterization of neuromodulations on their computational

Jean-marc Fellous; Christiane Linster

1998-01-01

253

Progress in mix modeling  

SciTech Connect

We have identified the Cranfill multifluid turbulence model (Cranfill, 1992) as a starting point for development of subgrid models of instability, turbulent and mixing processes. We have differenced the closed system of equations in conservation form, and coded them in the object-oriented hydrodynamics code FLAG, which is to be used as a testbed for such models.

Harrison, A.K.

1997-03-14

254

Model for ball lightning.  

National Technical Information Service (NTIS)

A model for ball lightning (BL) is described. It is based upon the vorton model for elementary particles, which exploits the symmetry between electricity and magnetism. The core, or driving engine, of BL in this model is comprised of a vorton-antivorton p...

D. Fryberger

1994-01-01

255

Analytical dynamic tire model  

Microsoft Academic Search

Modeling of tire friction is one of the central problems for vehicle control systems design. LuGre-type dynamic tire model has been proposed and well discussed in previous studies, because it offers a compact form of dynamic model that is convenient in advanced control studies. It has been successfully used in tire slip control design and vehicle state estimation problems. In

Wei Liang; Jure Medanic; Roland Ruhl

2008-01-01

256

Elliptical graphical modelling  

Microsoft Academic Search

We propose elliptical graphical models based on conditional uncorrelatedness as a robust generalization of Gaussian graphical models. Letting the population distribution be elliptical instead of normal allows the fitting of data with arbitrarily heavy tails. We study the class of proportionally affine equivariant scatter estimators and show how they can be used to perform elliptical graphical modelling. This leads to

D. Vogel; R. Fried

2011-01-01

257

SECOND GENERATION MODEL  

EPA Science Inventory

One of the environmental and economic models that the U.S. EPA uses to assess climate change policies is the Second Generation Model (SGM). SGM is a 13 region, 24 sector computable general equilibrium (CGE) model of the world that can be used to estimate the domestic and intern...

258

A Model Performance  

ERIC Educational Resources Information Center

|Building information modeling (BIM) uses three-dimensional modeling concepts, information technology and interoperable software to design, construct and operate a facility. However, BIM can be more than a tool for virtual modeling--it can provide schools with a 3-D walkthrough of a project while it still is on the electronic drawing board. BIM…

Thornton, Bradley D.; Smalley, Robert A.

2008-01-01

259

Sources of Model Error  

NSDL National Science Digital Library

This undergraduate meteorology tutorial from Texas A&M University describes the common sources of weather forecasting computer model error, ways to identify model error, and how to correct a forecast for some simple types of error. Model sensitivity to parameterization and topography are covered.

Nielsen-Gammon, John

1996-01-01

260

The Common Land Model  

Microsoft Academic Search

The Common Land Model (CLM) was developed for community use by a grassroots collaboration of scientists who have an interest in making a general land model available for public use and further development. The major model characteristics include enough unevenly spaced layers to adequately represent soil temperature and soil moisture, and a multilayer parameterization of snow processes; an explicit treatment

Yongjiu Dai; Xubin Zeng; Robert E. Dickinson; Ian Baker; Gordon B. Bonan; Michael G. Bosilovich; A. Scott Denning; Paul A. Dirmeyer; Guoyue Niu; Keith W. Oleson; C. Adam Schlosser; Zong-Liang Yang

2003-01-01

261

Bicycles, motorcycles, and models  

Microsoft Academic Search

The development of bicycles and motorcycles since the first patented running machine, or draisine, in 1817 is described. Bicycle modeling and control were also discussed. These models include: derivatives or simplifications of Whipple's bicycle dynamics model in which the lateral motion constraints at the road contact are nonholonomic, requiring special techniques to form correct equations of motion; and the Timoshenko-Young

DAVID J. N. LIMEBEER; ROBIN S. SHARP

2006-01-01

262

Advanced Restraint System Modeling.  

National Technical Information Service (NTIS)

The Articulated Total Body (ATB) model is currently being used by the AFAMRL to study the biomechanics of the pilot-seat ejection from an aircraft. The new ATB-II model presented in this report incorporates features developed since the original ATB model ...

F. E. Butler J. T. Fleck

1980-01-01

263

Model Rockets and Microchips.  

ERIC Educational Resources Information Center

|Points out the instructional applications and program possibilities of a unit on model rocketry. Describes the ways that microcomputers can assist in model rocket design and in problem calculations. Provides a descriptive listing of model rocket software for the Apple II microcomputer. (ML)|

Fitzsimmons, Charles P.

1986-01-01

264

Flexible labor supply models  

Microsoft Academic Search

Discrete-choice models of labor supply have become very popular for ex ante evaluations of policy reforms as they easily account for non-convex budget sets. We test the constraints imposed in practice on these models and suggest a fully flexible model that significantly improves fit.

Olivier Bargain

2009-01-01

265

Correlated Topic Models  

Microsoft Academic Search

Topic models, such as latent Dirichlet allocation (LDA), have been an ef- fective tool for the statistical analysis of document collections and other discrete data. The LDA model assumes that the words of each document arise from a mixture of topics, each of which is a distribution over the vo- cabulary. A limitation of LDA is the inability to model

David M. Blei; John D. Lafferty

2005-01-01

266

WILDFIRE RISK MODEL VALIDATION  

Microsoft Academic Search

Field samples (n = 128) collected during summer 2001 were used to create a series of fuel load and wildfire risk models. Field data collected during the summer 2002 field season (n = 370) were used to determine the accuracy of these models, as well as to refine and rebuild the existing models. Using this new data, we created an

Ben McMahan; Keith T. Weber

267

Auditory Processing Models  

NASA Astrophysics Data System (ADS)

There are at least two main reasons why auditory processing models are constructed: to represent the results from a variety of experiments within one framework and to explain the functioning of the system. Specifically, processing models help generate hypotheses that can be explicitly stated and quantitatively tested for complex systems. The models can also help determine how a deficit in one or more components affects the overall operation of the system. The development of auditory models has been hampered by the complexity of the individual auditory processing stages and their interactions. This resulted in a multiplicity of auditory models described in the literature.

Dau, Torsten

268

Scalar Field Gradient Model  

NSDL National Science Digital Library

The Scalar Field Gradient Model displays the gradient of a scalar field using a numerical approximation to the partial derivatives. This simple teaching model also shows how to display and model scalar and vector fields using the EJS. The EJS Scalar Field Gradient Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_math_ScalarFieldGradient.jar file will run the program if Java is installed.

Christian, Wolfgang

2009-03-14

269

Models of Abnormal Scarring  

PubMed Central

Keloids and hypertrophic scars are thick, raised dermal scars, caused by derailing of the normal scarring process. Extensive research on such abnormal scarring has been done; however, these being refractory disorders specific to humans, it has been difficult to establish a universal animal model. A wide variety of animal models have been used. These include the athymic mouse, rats, rabbits, and pigs. Although these models have provided valuable insight into abnormal scarring, there is currently still no ideal model. This paper reviews the models that have been developed.

Seo, Bommie F.; Lee, Jun Yong; Jung, Sung-No

2013-01-01

270

CRAC2 model description  

SciTech Connect

The CRAC2 computer code is a revised version of CRAC (Calculation of Reactor Accident Consequences) which was developed for the Reactor Safety Study. This document provides an overview of the CRAC2 code and a description of each of the models used. Significant improvements incorporated into CRAC2 include an improved weather sequence sampling technique, a new evacuation model, and new output capabilities. In addition, refinements have been made to the atmospheric transport and deposition model. Details of the modeling differences between CRAC2 and CRAC are emphasized in the model descriptions.

Ritchie, L.T.; Alpert, D.J.; Burke, R.P.; Johnson, J.D.; Ostmeyer, R.M.; Aldrich, D.C.; Blond, R.M.

1984-03-01

271

USGS mineral deposit models  

USGS Publications Warehouse

This CD-ROM publication is a compilation of 29 previously published mineral deposit model and related reports of the USGS. It in part reflects a history of mineral deposit model development within the USGS. Model types presented include descriptive, grade-tonnage, geoenvironmental, and geophysical. These models generally compile the geologic, geochemical, and geophysical characteristics of various types of metallic and nonmetallic mineral deposits. The models list attributes intended as guides for resource and geoenvironmental studies and for mineral exploration. They are presented using the lithologic-tectonic environmental mineral deposit classification scheme originally developed by Cox and Singer (1986).

edited by Stoeser, D. B.; Heran, William D.

2000-01-01

272

Model equations of state  

NASA Astrophysics Data System (ADS)

Model equations of state determining the thermodynamic characteristics of matter in various states of aggregation are reviewed. Methods for describing the thermodynamics of gases, liquids, and plasmas are described. Quantum-mechanical models for solids and a quasiclassical model of matter are discussed. Models which can be used to study melting, evaporation, structural and electronic phase transitions in solids, and phase transitions in nonideal plasmas are also discussed. The ranges of applicability of the various methods are determined. The results of model-based calculations are compared with the experimental data available.

Bushman, A. V.; Fortov, V. E.

1983-06-01

273

UZ Colloid Transport Model  

SciTech Connect

The UZ Colloid Transport model development plan states that the objective of this Analysis/Model Report (AMR) is to document the development of a model for simulating unsaturated colloid transport. This objective includes the following: (1) use of a process level model to evaluate the potential mechanisms for colloid transport at Yucca Mountain; (2) Provide ranges of parameters for significant colloid transport processes to Performance Assessment (PA) for the unsaturated zone (UZ); (3) Provide a basis for development of an abstracted model for use in PA calculations.

M. McGraw

2000-04-13

274

Wireless traffic modeling and prediction using seasonal ARIMA models  

Microsoft Academic Search

Seasonal ARIMA model is a good traffic model capable of capturing the behavior of a network traffic stream. In this paper, we give a general expression of seasonal ARIMA models with two periodicities and provide procedures to model and to predict traffic using seasonal ARIMA models. Our feasibility study experiments showed that seasonal ARIMA models could be used to model

Yantai Shu; Minfang Yu; Jiakun Liu; O. W. W. Yang

2003-01-01

275

Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models  

Microsoft Academic Search

Structural equation models have wide applications. One of the most important issues in analyzing structural equation models is model comparison. This article proposes a Bayesian model comparison statistic, namely the L?-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider a Bayesian semiparametric approach for estimation and model comparison in the context of structural equation models

Xin-Yuan Song; Ye-Mao Xia; Jun-Hao Pan; Sik-Yum Lee

2011-01-01

276

Distributed fuzzy system modeling  

SciTech Connect

The paper introduces and studies an idea of distributed modeling treating it as a new paradigm of fuzzy system modeling and analysis. This form of modeling is oriented towards developing individual (local) fuzzy models for specific modeling landmarks (expressed as fuzzy sets) and determining the essential logical relationships between these local models. The models themselves are implemented in the form of logic processors being regarded as specialized fuzzy neural networks. The interaction between the processors is developed either in an inhibitory or excitatory way. In more descriptive way, the distributed model can be sought as a collection of fuzzy finite state machines with their individual local first or higher order memories. It is also clarified how the concept of distributed modeling narrows down a gap between purely numerical (quantitative) models and the qualitative ones originated within the realm of Artificial Intelligence. The overall architecture of distributed modeling is discussed along with the detailed learning schemes. The results of extensive simulation experiments are provided as well. 17 refs.

Pedrycz, W.; Chi Fung Lam, P.; Rocha, A.F. [Univ. of Manitoba, Winnipeg, Manitoba (Canada)

1995-05-01

277

Microbial modeling in foods.  

PubMed

Predictive food microbiology is a field of study that combines elements of microbiology, mathematics, and statistics to develop models that describe and predict the growth or decline of microbes under specified environmental conditions. Models can be thought of as having three levels: primary level models describe changes in microbial numbers with time, secondary level models show how the parameters of the primary model vary with environmental conditions, and the tertiary level combines the first two types of models with user-friendly application software or expert systems that calculate microbial behavior under the specified conditions. Primary models include time-to-growth, Gompertz function, exponential growth rate, and inactivation/survival models. Commonly used secondary models are response surface equations and the square root and Arrhenius relationships. Microbial models are valuable tools in planning Hazard Analysis, Critical Control Point (HACCP) programs and making decisions, as they provide the first estimates of expected changes in microbial populations when exposed to a specific set of conditions. This review describes the models currently being developed for food-borne microorganisms, particularly pathogens, and discusses their uses. PMID:8777014

Whiting, R C

1995-11-01

278

Calibrated Properties Model  

SciTech Connect

The purpose of this model report is to document the calibrated properties model that provides calibrated property sets for unsaturated zone (UZ) flow and transport process models (UZ models). The calibration of the property sets is performed through inverse modeling. This work followed, and was planned in, ''Technical Work Plan (TWP) for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Sections 1.2.6 and 2.1.1.6). Direct inputs to this model report were derived from the following upstream analysis and model reports: ''Analysis of Hydrologic Properties Data'' (BSC 2004 [DIRS 170038]); ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2004 [DIRS 169855]); ''Simulation of Net Infiltration for Present-Day and Potential Future Climates'' (BSC 2004 [DIRS 170007]); ''Geologic Framework Model'' (GFM2000) (BSC 2004 [DIRS 170029]). Additionally, this model report incorporates errata of the previous version and closure of the Key Technical Issue agreement TSPAI 3.26 (Section 6.2.2 and Appendix B), and it is revised for improved transparency.

T. Ghezzehej

2004-10-04

279

Rail-transportation modeling  

SciTech Connect

Many different types of transportation models are used to model coal transportation by rail. To obtain realistic results, it is usually necessary to consider other modes in addition to rail and other commodities in addition to coal. For example, to know the potential bottlenecks on the rail system it is necessary to predict the total level of freight movement on the rail system. This requires modeling the movements of other commodities in addition to coal. To predict the levels of flows of both coal and non-coal commodities on the rail system, it is necessary to predict the share of total flows carried by rail. This requires accurate modeling of competing modes. To develop accurate rate models it is also necessary to have information on competing modes. This paper presents a collection of transportation models used to model the various aspects of coal transportation by rail and shows how they interact.

Tobin, R.L.

1982-01-01

280

Graphs and Tracks Model  

NSDL National Science Digital Library

The Graphs and Tracks Model allows instructors to create custom models of a ball rolling on a track with a variable shape. This EJS model was inspired by the Graphs and Tracks program by David Trowbridge. Instructors set the heights of the track segments and the model displays the motion of the ball. Optional displays, including position and velocity graphs, energy graphs, and data tables, can be added depending on the learning goals for the activity. Documents can aslo be added to the model to provide student instructions or activities. The customized simulation is then saved as a new jar file that can be redistributed. The Graphs and Tracks Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed.

Christian, Wolfgang; Belloni, Mario

2012-05-30

281

Electric Generator Model  

NSDL National Science Digital Library

The EJS Electric Generator Model shows a simple electric generator made from a conducting loop rotating in a uniform magnetic field and connected to an ammeter. The model shows a plot of the magnetic flux and induced current. If Ejs is installed, right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item allows for editing of the model. The Electric Generator model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_Generator.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Cox, Anne; Christian, Wolfgang

2009-09-22

282

Oscillator Chain Model  

NSDL National Science Digital Library

The EJS Oscillator Chain model shows a one-dimensional linear array of coupled harmonic oscillators with fixed ends. This model can be used to study the propagation of waves in a continuous medium and the vibrational modes of a crystalline lattice. The Ejs model shown here contains 31 coupled oscillators equally spaced within the interval [0, 2 pi] with fixed ends. Ejs Oscillator Chain model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_osc_OscillatorChain.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-11-06

283

Foam process models.  

SciTech Connect

In this report, we summarize our work on developing a production level foam processing computational model suitable for predicting the self-expansion of foam in complex geometries. The model is based on a finite element representation of the equations of motion, with the movement of the free surface represented using the level set method, and has been implemented in SIERRA/ARIA. An empirically based time- and temperature-dependent density model is used to encapsulate the complex physics of foam nucleation and growth in a numerically tractable model. The change in density with time is at the heart of the foam self-expansion as it creates the motion of the foam. This continuum-level model uses an homogenized description of foam, which does not include the gas explicitly. Results from the model are compared to temperature-instrumented flow visualization experiments giving the location of the foam front as a function of time for our EFAR model system.

Moffat, Harry K.; Noble, David R.; Baer, Thomas A. (Procter & Gamble Co., West Chester, OH); Adolf, Douglas Brian; Rao, Rekha Ranjana; Mondy, Lisa Ann

2008-09-01

284

Inhomogeneous Universe Models: the Szekeres Model  

NASA Astrophysics Data System (ADS)

Observations of the luminosity distance and redshift of type Ia supernovae lead to the conclusion that the expansion of the universe is accelerating, but only when the observations are interpreted under the assumptions of homogeneity and isotropy on large scales. It has been shown that relaxing these assumptions allows for alternative universe models which match the observed distance-redshift relation without any mysterious ``dark energy''. The simplest such models, the spherically symmetric Lemaître-Tolman-Bondi (LTB) class of models, have been much studied, and have been found by many to be problematic. The Szekeres class of models is a generalization of LTB which possesses no symmetries in general. It is able to better represent the lumpiness of the universe's matter distribution, and so it should serve as a more complete and accurate framework in which to interpret our observations. We present an overview of the Szekeres model as it applies to cosmology. We show how its shape gives it advantages over LTB, such as a potential for faster structure formation, better compliance with the Copernican principle, and possibly even explaining the anomalous alignment of several cosmological observations. We briefly mention our progress on studying the CMB dipole seen by observers within a Szekeres universe. This research was supported by the Texas Space Grant Consortium.

Buckley, Robert; Schlegel, E. M.

2012-01-01

285

TRAFFIC MODELLING USING CELLULAR AUTOMATA  

Microsoft Academic Search

Today's traffic models are divided into 3 main categories: microscopic models, mesoscopic models and macroscopic models. Each of them has its own advantages over the others. In this article it will be dealt with the microscopic models. Their main advantage is that they model car behaviour on the most detailed level and are great for modelling smaller traffic networks. Disadvantage

Michala Drozdová

2008-01-01

286

Generalized Multilevel Structural Equation Modeling  

ERIC Educational Resources Information Center

A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…

Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

2004-01-01

287

Triangle zigzag transition modeling  

NASA Astrophysics Data System (ADS)

Designing read-back subsystems in magnetic recording requires precise knowledge about the signal picked up by the reading head. As areal densities in longitudinal magnetic recording increase, the read-back signal becomes more corrupted by intersymbol interference, media noise, and intertrack interference. Due to the spatial distribution of transitions on a disk surface and the nonlinear character of bit interactions, two dimensional media plane models are widely used to model the write process. If a two dimensional (or three dimensional) read- head model is utilized, intertrack interferences are also observed. Micromagnetic media modeling, coupled with appropriate read-head models, have been successfully used to model the 'raw' magnetic recording channel. However, due to its high computational complexity, micromagnetic modeling is an impractical tool in statistical signal analyses such as error rate studies where thousands of transitions need to be created. We propose a much simpler, yet realistic, two dimensional write process model. We call it the triangle zig-zag transition (TZ- ZT) model since the transition boundary is modeled by lateral sides of isosceles triangles of alternating orientations truncated on a common basis line across the track width. Formulas are presented that relate the parameters of the model, the probability density function of triangle heights and the constant vertex angle, to the magnetization transition profile of an isolated transition and to the cross track correlation width, respectively. Although stochastic zig-zag models have been proposed in the past, our model has the advantage that it is stable across the track, that is, it is not an independent increment process and it therefore doesn't exhibit a cross track drift. Compared to micromagnetic modeling, the TZ-ZT model offers computational savings of 4 orders of magnitude, while transition shapes and media noise are modeled with comparable accuracy, as our results show. For these reasons, the TZ-ZT model, combined with an appropriate head-sensitivity function, is an attractive 'raw channel' model for applications such as statistical performance analyses where large numbers of bits are needed.

Kavcic, Aleksandar; Moura, Jose M.

1995-12-01

288

Phyloclimatic modeling: combining phylogenetics and bioclimatic modeling.  

PubMed

We investigate the impact of past climates on plant diversification by tracking the "footprint" of climate change on a phylogenetic tree. Diversity within the cosmopolitan carnivorous plant genus Drosera (Droseraceae) is focused within Mediterranean climate regions. We explore whether this diversity is temporally linked to Mediterranean-type climatic shifts of the mid-Miocene and whether climate preferences are conservative over phylogenetic timescales. Phyloclimatic modeling combines environmental niche (bioclimatic) modeling with phylogenetics in order to study evolutionary patterns in relation to climate change. We present the largest and most complete such example to date using Drosera. The bioclimatic models of extant species demonstrate clear phylogenetic patterns; this is particularly evident for the tuberous sundews from southwestern Australia (subgenus Ergaleium). We employ a method for establishing confidence intervals of node ages on a phylogeny using replicates from a Bayesian phylogenetic analysis. This chronogram shows that many clades, including subgenus Ergaleium and section Bryastrum, diversified during the establishment of the Mediterranean-type climate. Ancestral reconstructions of bioclimatic models demonstrate a pattern of preference for this climate type within these groups. Ancestral bioclimatic models are projected into palaeo-climate reconstructions for the time periods indicated by the chronogram. We present two such examples that each generate plausible estimates of ancestral lineage distribution, which are similar to their current distributions. This is the first study to attempt bioclimatic projections on evolutionary time scales. The sundews appear to have diversified in response to local climate development. Some groups are specialized for Mediterranean climates, others show wide-ranging generalism. This demonstrates that Phyloclimatic modeling could be repeated for other plant groups and is fundamental to the understanding of evolutionary responses to climate change. PMID:17060200

Yesson, C; Culham, A

2006-10-01

289

Modeling agriculture in the Community Land Model  

NASA Astrophysics Data System (ADS)

The potential impact of climate change on agriculture is uncertain. In addition, agriculture could influence above- and below-ground carbon storage. Development of models that represent agriculture is necessary to address these impacts. We have developed an approach to integrate agriculture representations for three crop types - maize, soybean, and spring wheat - into the coupled carbon-nitrogen version of the Community Land Model (CLM), to help address these questions. Here we present the new model, CLM-Crop, validated against observations from two AmeriFlux sites in the United States, planted with maize and soybean. Seasonal carbon fluxes compared well with field measurements. CLM-Crop yields were comparable with observations in some regions, although the generality of the crop model and its lack of technology and irrigation made direct comparison difficult. CLM-Crop was compared against the standard CLM3.5, which simulates crops as grass. The comparison showed improvement in gross primary productivity in regions where crops are the dominant vegetation cover. Crop yields and productivity were negatively correlated with temperature and positively correlated with precipitation. In case studies with the new crop model looking at impacts of residue management and planting date on crop yield, we found that increased residue returned to the litter pool increased crop yield, while reduced residue returns resulted in yield decreases. Using climate controls to signal planting date caused different responses in different crops. Maize and soybean had opposite reactions: when low temperature threshold resulted in early planting, maize responded with a loss of yield, but soybean yields increased. Our improvements in CLM demonstrate a new capability in the model - simulating agriculture in a realistic way, complete with fertilizer and residue management practices. Results are encouraging, with improved representation of human influences on the land surface and the potentially resulting climate impacts.

Drewniak, B.; Song, J.; Prell, J.; Kotamarthi, V. R.; Jacob, R.

2012-12-01

290

Geochemical modeling: a review  

SciTech Connect

Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted.

Jenne, E.A.

1981-06-01

291

[Mathematical models of hysteresis  

SciTech Connect

The research described in this proposal is currently being supported by the US Department of Energy under the contract Mathematical Models of Hysteresis''. Thus, before discussing the proposed research in detail, it is worthwhile to describe and summarize the main results achieved in the course of our work under the above contract. Our ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with nonlocal memories''. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. Our research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. Our study has by and large been centered around the following topics: various generalizations and extensions of the classical Preisach model, finding of necessary and sufficient conditions for the representation of actual hysteretic nonlinearities by various Preisach type models, solution of identification problems for these models, numerical implementation and experimental testing of Preisach type models. Although the study of Preisach type models has constituted the main direction of the research, some effort has also been made to establish some interesting connections between these models and such topics as: the critical state model for superconducting hysteresis, the classical Stoner-Wohlfarth model of vector magnetic hysteresis, thermal activation type models for viscosity, magnetostrictive hysteresis and neural networks.

Mayergoyz, I.D.

1991-01-01

292

Modeling of surface reactions  

SciTech Connect

Mathematical models are used to elucidate properties of the monomer-monomer and monomer-dimer type chemical reactions on a two-dimensional surface. The authors use mean-field and lattice gas models, detailing similarities and differences due to correlations in the lattice gas model. The monomer-monomer, or AB surface reaction model, with no diffusion, is investigated for various reaction rates k. Study of the exact rate equations reveals that poisoning always occurs if the adsorption rates of the reactants are unequal. If the adsorption rates of the reactants are equal, simulations show slow poisoning, associated with clustering of reactants. This behavior is also shown for the two-dimensional voter model. The authors analyze precisely the slow poisoning kinetics by an analytic treatment for the AB reaction with infinitesimal reaction rate, and by direct comparison with the voter model. They extend the results to incorporate the effects of place-exchange diffusion, and they compare the AB reaction with infinitesimal reaction rate and no diffusion to the voter model with diffusion at rate 1/2. They also consider the relationship of the voter model to the monomer-dimer model, and investigate the latter model for small reaction rates. The monomer-dimer, or AB[sub 2] surface reaction model is also investigated. Specifically, they consider the ZGB-model for CO-oxidation, and in generalizations of this model which include adspecies diffusion. A theory of nucleation to describe properties of non-equilibrium first-order transitions, specifically the evolution between [open quote]reactive[close quote] steady states and trivial adsorbing states, is derived. The behavior of the [open quote]epidemic[close quote] survival probability, P[sub s], for a non-poisoned patch surrounded by a poisoned background is determined below the poisoning transition.

Ray, T.R.

1993-01-01

293

Supersymmetric Landau models  

NASA Astrophysics Data System (ADS)

This work is focused on the different supersymmetric extensions of the Landau model. We aim to fully solve each model and describe its energy levels, wavefunctions, Hilbert space and define a norm on it, as well as find symmetry generators and transformations with respect to them. Several possible generalizations were considered before. It was found for Landau model on the so called Superflag manifold as well as planar Superflag and Superplane Landau models that standard norm on the Hilbert space is not positive definite. Later for planar cases it was found that it is possible to fix this by introducing a new norm which will be invariant and positive definite. Surprisingly this procedure brings up 'hidden' symmetries for the known super Landau models. In the dissertation we apply the same procedure for Landau model on superpshere and Superflag manifolds. It turns out that superpsherical Landau model is equivalent to the Superflag model with one of the parameters fixed. Because the model on superpshere can be recovered from the Superflag we will do calculations of corrected norm only for the Superflag. After this we develop a different generalization of the Superplane Landau model. Starting with Lagrangian in a superfield form we introduce two arbitrary functions of superfields K(?) and V(?) into the Lagrangian. We follow with the component form of Lagrangian. The quantization of the model is possible, and we will show that there is a reparametrization which turn equation of motion of the first scheme into the second set. Standard metric is again non-positive definite and we apply already known procedure to correct it. It will not be possible to solve Schrodinger equations in general with undefined K and V, so we consider one specific case which give us Landau model on a sphere with N = 2 supersymmetry, which put it apart from the superspherical Landau model, which have a superpshere for a target space but do not possess supersymmetry.

Beylin, Andrey V.

294

Linear Glauber model.  

PubMed

We study the time-dependent and the stationary properties of the linear Glauber model in a d-dimensional hypercubic lattice. This model is equivalent to the voter model with noise. By using the Green function method, we get exact results for the two-point correlations from which the critical behavior is obtained. For vanishing noise the model becomes critical with exponents beta=0, gamma=1, and nu=1/2 for d > or =2, with logarithmic corrections at the upper critical dimension d(c)=2, and beta=0, gamma=1/2, and nu=1/2 for d=1. We show that the model can be mapped into a particular reaction-diffusion model. PMID:16241298

de Oliveira, Mário J

2003-06-06

295

Chromosphere flare models  

NASA Astrophysics Data System (ADS)

Further calculated results based on the F1 and F2 chromospheric models of Machado et al. (1980) are presented in addition to results from a model with enhanced temperatures relative to the weak-flare model F1 in the upper photosphere and low chromosphere, and from a model with enhanced temperatures relative to the strong flare model F2 in the upper chromosphere. The coupled equations of statistical equilibrium and radiative transfer for H, H(-), He I-II, C I-IV, Si I-II, Mg I-II, Fe, Al, O I-II, Na, and Ca II are solved, and the overall absorption and emission of radiation by lines throughout the spectrum are determined by means of a reduced set of opacities taken from a compilation of over 10 million lines. Semiempirical models show that the white light flare continuum may arise by extreme chromospheric overheating, as well as by an enhancement of the minimum temperature region.

Avrett, E. H.; Kurucz, R. L.; Machado, M. E.

1985-08-01

296

The Everglades Landscape Model  

NSDL National Science Digital Library

Developed by researchers at the Institute for Ecological Economics and the South Florida Water Management District, the Everglades Landscape Model is one of the tools in a research management program used to focus research and evaluate changes in water management of southern Florida. The site has a brief introduction to the problems involved with the management of the region and the general objectives of the project. In addition, there is a detailed section outlining the particulars of the model's structure and the specific premises assumed within the model. There is also a full list of related publications dealing with different projects involved with the model and various progress reports. Finally, a variety of data generated by the model and data used to run the model is available for visitors to the site.

297

The Barotropic Model  

NSDL National Science Digital Library

This applet tests the sensitivity of a barotropic model to time step, grid spacing, and initial conditions. The site explains the CFL (Courant-Friedrichs-Lewy) criterion (that the speed of fastest winds in the model must be less than or equal to grid spacing divided by the time step) and how a finite-difference weather prediction model blows up if this criterion is not met. The user of this applet will learn what the model looks like when it blows up, that a modeler cannot arbitrarily choose a horizontal grid spacing without also taking into account the time step of the model, and that if fine horizontal resolution is desired to see small-scale weather, there must be fine time resolution, too.

Ackerman, Steve; Whittaker, Tom

298

The model coupling toolkit.  

SciTech Connect

The advent of coupled earth system models has raised an important question in parallel computing: What is the most effective method for coupling many parallel models to form a high-performance coupled modeling system? We present our solution to this problem--The Model Coupling Toolkit (MCT). We explain how our effort to construct the Next-Generation Coupler for NCAR Community Climate System Model motivated us to create this toolkit. We describe in detail the conceptual design of the MCT and explain its usage in constructing parallel coupled models. We present preliminary performance results for the toolkit's parallel data transfer facilities. Finally, we outline an agenda for future development of the MCT.

Larson, J. W.; Jacob, R. L.; Foster, I.; Guo, J.

2001-04-13

299

Physical modeling of transducers  

NASA Astrophysics Data System (ADS)

It is difficult to do significant work on transducers in an academic or small-shop setting since the machinery required for the fabrication of the micro-sized elements is expensive, and the needed human expertise takes a long time to acquire. The expense of preparing for prototype production must be committed even before the design has been tested. This paper discusses a means to allow fabrication of low-frequency models of high-frequency transducers in the average academic laboratory or model shop -- without requiring exotic saws, presses, etc., for preliminary evaluation of the design. These models will have the added advantage that they can be more realistic models of actual transducers than present computer models. In addition, we show that acoustic fields can be scaled so that field models of scattering and propagation can be used to investigate these effects.

Reid, John M.; Lewin, Peter A.; Zhang, Qian

1997-04-01

300

Morris-Lecar Model  

NSDL National Science Digital Library

The Morris-Lecar Model is an abstraction of the Hodgkin-Huxley Model that has two state variables: the voltage within the neuron and a potassium gating variable. This model gives three presets for parameters and allows the user to open a new window to see the phase space. By viewing the phase space and adjusting the parameters him- or herself, the user can gain a complete understanding of the dynamics of this neuron abstraction. The Morris-Lecar Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Thomson, Colin F.

2012-09-18

301

RC Circuit Model  

NSDL National Science Digital Library

RC Circuit models the dynamical behavior of a voltage source attached in series to a resistor and capacitor. The source voltage can be chosen to be either a 10 volt sinusoidal or square wave with an adjustable frequency. Users can examine and change the model if they have Ejs installed. The RC Circuit model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_RcCircuit.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-10-05

302

Cystic fibrosis mouse models.  

PubMed

Animal models of cystic fibrosis (CF) are powerful tools that enable the study of the mechanisms and complexities of human disease. Murine models have several intrinsic advantages compared with other animal models, including lower cost, maintenance, and rapid reproduction rate. Mice can be easily genetically manipulated by making transgenic or knockout mice, or by backcrossing to well-defined inbred strains in a reasonably short period of time. However, anatomic and immunologic differences between mice and humans mean that murine models have inherent limitations that must be considered when interpreting the results obtained from experimental models and applying these to the pathogenesis of CF disease in humans. This review will focus on the different CF mouse models available that represent diverse phenotypes observed in humans with CF and that can help researchers elucidate the diverse functions of the CFTR protein. PMID:16888286

Guilbault, Claudine; Saeed, Zienab; Downey, Gregory P; Radzioch, Danuta

2006-08-03

303

Hindmarsh-Rose Model  

NSDL National Science Digital Library

The Hindmarsh-Rose model is a system of three differential equations that model a different physical aspect of a single neuron. The three dynamical variables in this model, x, y, and z represent respectively the membrane potential, the activity of fast gated ion channels (such as sodium and potassium), and the activity of slow-gated ion channels (such as calcium and chloride). The Hindmarsh-Rose model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Thomson, Colin F.

2012-11-06

304

Exceptional electroweak model  

SciTech Connect

We consider a gauge extension of the electroweak sector of the standard model based on the group G{sub 2}xSU(2)xU(1). The exceptional group G{sub 2} is the smallest rank two group that contains SU(3) as a subgroup; the SU(3) prediction sin{sup 2}{theta}{sub w}=1/4 follows approximately in this model if the couplings of the additional SU(2) and U(1) factors are sufficiently large. We study the symmetry-breaking sector of the model, the bounds from precision electroweak constraints and the mass spectrum of exotic gauge bosons that may be produced at future colliders. We also discuss a SU(3) electroweak model in which a vectorlike sector is included explicitly to facilitate the decays of otherwise stable exotic states. The models considered here represent plausible extensions of the minimal SU(3) electroweak model with potentially distinctive TeV-scale phenomenology.

Carone, Christopher D.; Rastogi, Ashwin [Particle Theory Group, Department of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795 (United States)

2008-02-01

305

The XXC models  

NASA Astrophysics Data System (ADS)

A class of recently introduced multi-states XX models is generalized to include a deformation parameter. This corresponds to an additional nearest-neighbor CC interaction in the defining quadratic Hamiltonian. Complete integrability of the one-dimensional models is shown in the context of the quantum inverse scattering method.The new R-matrix is derived. The diagonalization of the XXC models is carried out using the algebraic Bethe ansatz.

Maassarani, Z.

1998-07-01

306

Mass Balance Model  

NSDL National Science Digital Library

In this JAVA-based interactive modeling activity, students are introduced to the concept of mass balance, flow rates, and equilibrium using a simple water bucket model. Students can vary flow rate into the bucket, initial water level in the bucket, and residence time of water in the bucket. After running the model, the bucket's water level as a function of time is presented graphically and in tabular form.

Mackay, Robert; Science Education Resource Center, Starting P.

307

Mathematical Models of Narcolepsy  

Microsoft Academic Search

\\u000a Mathematical modeling offers a way to critically test experimentally derived theories, integrate experimental results across\\u000a spatial and temporal scales, and generate predictions to drive bench science and influence clinical practice. Although, in\\u000a general, mathematical modeling approaches have been applied to narcolepsy only recently, developments in modeling normal sleep\\/wake\\u000a behavior have laid an excellent foundation for linking the experimental insights about

Cecilia Diniz Behn

308

Simulation models for schizophrenia  

Microsoft Academic Search

\\u000a As discussed in Ellenbroek and Cools, Animal models, this volume, the development of simulation models for schizophrenia has\\u000a gained momentum in the last decade through the recognition that not only symptoms, but also psychophysiological and psychological\\u000a disturbances of the disease can be used. This has led to the development of models like prepulse inhibition (PPI), P50 gating\\u000a and latent inhibition.

Bart A. Ellenbroek; Frank Sams-Dodd; Alexander R. Cools

309

Models for citation behavior  

Microsoft Academic Search

The number of citations of journal papers is an important measure of the impact of research. Thus, the modeling of citation\\u000a behavior needs attention. Burrell, Egghe, Rousseau and others pioneered this type of modeling. Several models have been proposed\\u000a for the citation distribution. In this note, we derive the most comprehensive collection of formulas for the citation distribution,\\u000a covering some

Saralees Nadarajah; Samuel Kotz

2007-01-01

310

Roller Coaster Model  

NSDL National Science Digital Library

The EJS Roller Coaster model explores the relationship between kinetic, potential, and total energy as a cart travels along a roller coaster. Users can create their own roller coaster curve and observe the resulting motion. The Roller Coaster model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed.

Gallis, Michael R.

2008-10-27

311

Model-Based Traces  

Microsoft Academic Search

We introduce model-based traces, which trace behavioral mod- els of a system's design during its execution, allowing to combine model- driven engineering with dynamic analysis. Specically, we take visual inter-object scenario-based and intra-object state-based models (sequence charts and statecharts) used for a system's design, and follow their acti- vation and progress as they come to life at runtime, during the

Shahar Maoz

2008-01-01

312

On Deterministic Fractional Models  

Microsoft Academic Search

\\u000a This chapter is dedicated to presenting some aspects of the so-called Ordinary and\\/or Partial Fractional Differential Equations.\\u000a During last 20 years the main underground reason that explain the interest of the applied researchers in the fractional models\\u000a have been the known close link that exists between such kind of models and the so-called “Jump” stochastic models, such as\\u000a the CTRW

Margarita Rivero; Juan J. Trujillo; M. Pilar Velasco

313

SAM EMP (SEMP) model  

Microsoft Academic Search

The Surface-To-Air Missile (SAM) Electro-Magnetic-Pulse (EMP) (SEMP) model simulates the illumination of an entire SAM brigade with an EMP weapon. It computes probability distributions of SAM brigade performance levels after an EMP attack has occurred. Brigade performance is determined by the combination of components that survive the EMP. Accordingly, the SEMP model is separated into the component failure model and

Thatcher

1984-01-01

314

Gauge Messenger Models  

SciTech Connect

We consider gauge messenger models in which X and Y gauge bosons and gauginos are messengers of supersymmetry breaking. In simple gauge messenger models, all the soft parameters except {mu} and B{mu} are calculated in terms of a single scale parameter MSUSY which is proportional to F / MGUT. Unique prediction on dark matter in gauge messenger models is discussed. (Based on hep-ph/0601036 and hep-ph/0607169)

Kim, Hyung Do [School of Physics and Astronomy, Seoul National University, Seoul, Korea, 151-747 (Korea, Republic of); CTP, Seoul National University, Seoul, 151-747 (Korea, Republic of)

2006-11-28

315

HOMER® Micropower Optimization Model  

SciTech Connect

NREL has developed the HOMER micropower optimization model. The model can analyze all of the available small power technologies individually and in hybrid configurations to identify least-cost solutions to energy requirements. This capability is valuable to a diverse set of energy professionals and applications. NREL has actively supported its growing user base and developed training programs around the model. These activities are helping to grow the global market for solar technologies.

Lilienthal, P.

2005-01-01

316

Natural Form Modeling  

Microsoft Academic Search

Most engineering software has been designed and optimized for parametric shapes. Sophisticated modeling of natural objects\\u000a is free-form based, reflecting their inherent design. The merging of natural with parametric-based forms presents additional\\u000a challenges. While work is needed, there are solutions that enable natural form modeling and analysis. Our focus is to use\\u000a medical imaging and 3D modeling to analyze the

Douglas Robertson; Gulshan Sharma

317

Traffic Network Models Correlated  

Microsoft Academic Search

The procedure and main result of a comparative study based on using an autoregressive model and an artificial intelligence technique applied to a Wimax traffic data series forecasting task are presented in this document. The time series forecasting methods being compared are: ANFIS model (Adaptive Network-based Fuzzy Inference Sys-tem) and ARIMA model (Auto-Regressive Integrated Moving Average). This article aims to

C. A. Hernandez S; L. F. Pedraza M

2010-01-01

318

Microscopic models of hardness  

Microsoft Academic Search

Recent developments in the field of microscopic hardness models have been reviewed. In these models, the theoretical hardness\\u000a is described as a function of the bond density and bond strength. The bond strength may be characterized by energy gap, reference\\u000a potential, electron-holding energy or Gibbs free energy, and different expressions of bond strength may lead to different\\u000a hardness models. In

F. M. Gao; L. H. Gao

2010-01-01

319

Modelling Pediatric Kinematics  

PubMed Central

In the field of pediatric biomechanics, crash dummy and numerical model development suffers from too limited human subject data to directly establish response and injury values. In order to create child crash dummies and numerical models it is necessary to combine the results from real world accident and reconstruction data, scaled adult data and data from animal testing with limited child volunteer data. This paper presents the functional and biomechanical targets for child crash dummies and numerical models.

van Ratingen, M.R.; Wismans, J.

1998-01-01

320

The Princeton Ocean Model  

NSDL National Science Digital Library

The Princeton Ocean Model (POM), a sigma coordinate, free surface, ocean model, can be "used for modeling estuaries, coastal regions, basin, and global oceans." Users can find helpful guides on how to use the freely distributed POM. The web site offers downloads of the proceedings of past meetings. Researchers can find links to data sources, national agencies and labs, and organizations. The Applications link offers numerous examples of organizations that have used POM in their research projects.

2007-10-08

321

The Princeton Ocean Model  

NSDL National Science Digital Library

The Princeton Ocean Model (POM), a sigma coordinate, free surface, ocean model, can be "used for modeling estuaries, coastal regions, basin, and global oceans." Users can find helpful guides on how to use the freely distributed POM. The web site offers downloads of the proceedings of past meetings. Researchers can find links to data sources, national agencies and labs, and organizations. The Applications link offers numerous examples of organizations that have used POM in their research projects.

322

Spherical Mirror Model  

NSDL National Science Digital Library

The Spherical Mirror Model demonstrates the focusing of light using a spherical mirror. The user can change the size and position of the object, the focal length of the mirror and the rays shown in the diagram. The Spherical Mirror Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_Spherical_Mirror.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

323

Battle of Animal Models  

Microsoft Academic Search

This is a brief summary of the animal models session held during the 12th Annual Meeting of the Society on NeuroImmune Pharmacology,\\u000a Santa Fe, NM, USA. This session provided important information for participants on availability and utility of animal models\\u000a for the studies of HIV-1 central nervous system infection and drug abuse. It highlighted animal model relevance to human disease\\/condition,

Yuri Persidsky; Howard Fox

2007-01-01

324

Thin Film Interference Model  

NSDL National Science Digital Library

The Thin Film Interference model investigates reflection and transmission of light through a thin film. The user can change the thickness and index of refraction of the thin film as well as the incident light wavelength. The Thin Film Interference Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_ThinFilm.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

325

Making Mendel's Model Manageable  

NSDL National Science Digital Library

Genetics is often a fascinating but difficult subject for middle level students. This engaging activity presents an approach that helps students understand how genotypes can translate into phenotypes using Gummi Bears and Gummi Dolphins to solve problems using Mendel's model, and then revising the model as necessary. Developing a model gives students a sense of how science works and how data translate into scientific ideas.

Mesmer, Karen

2006-01-01

326

Systems model for learning  

Microsoft Academic Search

Develops a model of learning that differs greatly from traditional or intuitive models. This hard system is specifically designed for the context of problem-solving\\/higher-order thinking, rather than automatic learning. Research in educational psychology and cognitive science provides the basis for the model. Learning is the integration of new knowledge\\/behaviors into a framework, and subsequently recalling what is relevant in the

Philip Buriak; Brian McNurlen; Joe Harper

1995-01-01

327

Fraction Model I  

NSDL National Science Digital Library

Explore different representations for fractions. This applet allows students to create a fraction,then see it as a visual model, and as percent and decimal equivalents. They can choose the model to be a circle, a rectangle, or a set model. Intended for the young learner, this version restricts the numerator to values from 0 to 20, and the denominator to benchmark values of 1, 2, 4, 5, 8, 10 and 20.

Illuminations, Nctm

2000-01-01

328

Solid model design simplification  

SciTech Connect

This paper documents an investigation of approaches to improving the quality of Pro/Engineer-created solid model data for use by downstream applications. The investigation identified a number of sources of problems caused by deficiencies in Pro/Engineer`s geometric engine, and developed prototype software capable of detecting many of these problems and guiding users towards simplified, useable models. The prototype software was tested using Sandia production solid models, and provided significant leverage in attacking the simplification problem.

Ames, A.L.; Rivera, J.J.; Webb, A.J.; Hensinger, D.M.

1997-12-01

329

Business process Modeling Language  

Microsoft Academic Search

Abstract The Business Process Modeling Language (BPML) specification provides an abstract model for expressing business processes,and supporting entities. BPML defines a formal model for expressing abstract and executable processes,thataddress,all aspects of enterprise business processes, including activities of varying complexity, transactions and their compensation, data management, concurrency, exception handling and operational semantics. BPML also provides a grammar in the form of

A. Arkin

2002-01-01

330

SUSY GUT model building  

NASA Astrophysics Data System (ADS)

The evolution of SUSY GUT model building is discussed, starting with the construction of 4D GUTs, to orbifold GUTs and finally to orbifold GUTs, within the heterotic string model. This evolution is an attempt to obtain realistic string models, perhaps relevant for the LHC. This review is in memory of the sudden loss of Julius Wess, a leader in the field, who will be sorely missed.

Raby, Stuart

2009-01-01

331

Modeling Imports in a Keynesian Expenditure Model  

ERIC Educational Resources Information Center

The author discusses several issues that instructors of introductory macroeconomics courses should consider when introducing imports in the Keynesian expenditure model. The analysis suggests that the specification of the import function should partially, if not completely, be the result of a simple discussion about the spending and import…

Findlay, David W.

2010-01-01

332

Oscillator Chain JS Model  

NSDL National Science Digital Library

The EJS Oscillator Chain model shows a one-dimensional linear array of coupled harmonic oscillators with fixed ends. This model can be used to study the propagation of waves in a continuous medium and the vibrational modes of a crystalline lattice. The Ejs model shown here contains 31 coupled oscillators equally spaced within the interval [0, 2 pi] with fixed ends. The Oscillator Chain JS Model was developed using the Easy Java Simulations (Ejs) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Christian, Wolfgang

2013-08-25

333

Modeling a Changing World  

NSDL National Science Digital Library

Modeling a Changing World written by mathematics professor Tim Chartier and his student Nick Dovidio presents curricular material in an OSP Launcher package to motivate the need for numerically solving ordinary differential equations. The package discusses such applications as a mass-spring system and its connection to computer simulation for movies. An interactive model that simulates a two-body gravitational model of the moon and earth allows for exploring the topic of numerical error. Other models explore topics that include slope fields, numerical integration and numerical solvers for ordinary differential equations.

Chartier, Tim

2008-09-19

334

Crow process modeling  

SciTech Connect

Western Research Institute (wRI) has developed a numerical model (TCROW) to describe CROW{sup TM} processing of contaminated aquifers. CROW is a patented technology for the removal of contaminant organics from water-saturated formations by injection of hot water or low- temperature steam. TCROW is based on a fully implicit, thermal, compositional model (TSRS) previously developed by wRI. TCROW`s formulation represents several enhancements and simplifications over TSRS and results in a model specifically tailored to model the CROW process.

NONE

1997-04-01

335

Central Force JS Model  

NSDL National Science Digital Library

The Central Force JavaScript Model computes the trajectory of a particle acted on by a central force.  The model reads uses a JavaScript mathematical expression parser to read the force and a adaptive step Runge-Kutta 5(4) algorithm to compute the trajectory.  This model is designed to test the speed of the JS parser and the accuracy of the EJS JavaScript ODE solver. The Central Force JS Model was developed using the Easy Java Simulations (EJS) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Christian, Wolfgang

2013-09-01

336

Carbon Temperature Model  

NSDL National Science Digital Library

With this carbon/temperature interactive model, students investigate the role of atmospheric carbon in the greenhouse effect using a relationship between atmospheric carbon dioxide and global temperature.

Center, Nasa: C.; Nasa

337

Numerical dynamo models  

NSDL National Science Digital Library

This page from the Swiss Federal Institute of Technology explains current research modeling geomagnetic processes, including magnetic reversals and secular variation. Includes three supporting figures.

Jackson, Andrew; Finlay, Chris; Zurich, Eth

338

Dynamic Trajectory Visualizer Model  

NSDL National Science Digital Library

The Dynamic Trajectory Animator allows instructors to create two-dimensional single-particle Newtonian dynamics models for teaching. Instructors set two functions, Fx(t) and Fy(t), and the model displays the position-space particle motion as well as position, velocity, and acceleration graphs and tables. The customized simulation is then saved with associated curricular as a new jar file that can be redistributed. The Dynamic Trajectory Animator Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_TabletopProjectile.jar file will run the program if Java is installed.

Christian, Wolfgang; Belloni, Mario

2012-05-11

339

Analytic Trajectory Visualizer Model  

NSDL National Science Digital Library

The Analytic Animator allows instructors to create two-dimensional single-particle kinematics models for teaching. Instructors set two functions, x(t) and y(t), and the model displays the position-space particle motion as well as position, velocity, and acceleration graphs and tables. The customized simulation is then saved with associated curricular as a new jar file that can be redistributed. The Analytic Trajectory Animator Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_TabletopProjectile.jar file will run the program if Java is installed.

Christian, Wolfgang; Belloni, Mario

2012-05-15

340

Ferris Wheel Model  

NSDL National Science Digital Library

The Ferris Wheel Model explores the amusement park ride modeled after Ferris' original wheel. The simulation shows a wheel that can be varied in radius from 40 m (Ferris' original wheels) to 100 m, or about 10 meters langer than the current world record. In addition, the rotational speed of the wheel can be varied from 10 - 20 m/s. By selecting the checkbox, the free-body diagram can be shown. The Ferris Wheel Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed.

Belloni, Mario

2012-01-23

341

Models of Reality.  

SciTech Connect

Conscious awareness of our environment is based on a feedback loop comprised of sensory input transmitted to the central nervous system leading to construction of our ''model of the world,'' (Lewis et al, 1982). We then assimilate the neurological model at the unconscious level into information we can later consciously consider useful in identifying belief systems and behaviors for designing diverse systems. Thus, we can avoid potential problems based on our open-to-error perceived reality of the world. By understanding how our model of reality is organized, we allow ourselves to transcend content and develop insight into how effective choices and belief systems are generated through sensory derived processes. These are the processes which provide the designer the ability to meta model (build a model of a model) the user; consequently, matching the mental model of the user with that of the designer's and, coincidentally, forming rapport between the two participants. The information shared between the participants is neither assumed nor generalized, it is closer to equivocal; thus minimizing error through a sharing of each other's model of reality. How to identify individual mental mechanisms or processes, how to organize the individual strategies of these mechanisms into useful patterns, and to formulate these into models for success and knowledge based outcomes is the subject of the discussion that follows.

Brown-VanHoozer, S. A.

1999-06-02

342

Theory of Chemical Modeling  

NASA Astrophysics Data System (ADS)

In order to deal with the complexity of natural systems simplified models are employed to illustrate the principal and regulatory factors controlling a chemical system. Following the aphorism of Albert Einstein: Everything should be made as simple as possible, but not simpler, models need not to be completely realistic to be useful (Stumm and Morgan 1996), but need to meet a successful balance between realism and practicality. Properly constructed, a model is neither too simplified that it is unrealistic nor too detailed that it cannot be readily evaluated and applied to the problem of interest (Bethke 1996). The results of a model have to be at least partially observable or experimentally verifiable (Zhu and Anderson 2002). Geochemical modeling theories are presented here in a sequence of increasing complexity from geochemical equilibrium models to kinetic, reaction path, and finally coupled transport and reaction models. The description is far from complete but provides the needs for the set up of reactive transport models of hydrothermal systems as done within subsequent chapters. Extensive reviews of geochemical models in general can be found in the literature (Appelo and Postma 1999, Bethke 1996, Melchior and Bassett 1990, Nordstrom and Ball 1984, Paschke and van der Heijde 1996).

Kühn, Michael

343

Interference Model: Ripple Tank  

NSDL National Science Digital Library

The Interference Model: Ripple Tank investigates constructive and destructive interference between two point sources. The user can change the point source frequency, location and separation and phase difference between the point sources. The model also shows the difference in distance from the point sources to a movable observation point. The Interference Model: Ripple Tank was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_Ripple_Tank_Interference.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

344

Flight Dynamics Modeling  

Microsoft Academic Search

\\u000a In Chap. 6, we present a comprehensive modeling process to obtain a highly accurate nonlinear dynamical model for our unmanned\\u000a systems, SheLion (also applicable to HeLion). We first derive a minimum-complexity model structure, which covers all the important\\u000a dynamic features necessary for flight control law design. Based on this structured model, we develop a five-step procedure,\\u000a a systematic combination of the

Guowei Cai; Ben M. Chen; Tong Heng Lee

345

Global nonlinear aerodynamic model identification based on NARMAX model  

Microsoft Academic Search

A new method for global nonlinear aerodynamic model identification is presented. Aerodynamic model of aircraft is analyzed, and a simple and effective aerodynamic model is presented. The aerodynamic model of aircraft is then depicted in NARMAX (Nonlinear Auto Regressive Moving Average model with eXogenous inputs) form inside a Linear Regression framework. The items and coefficients of the aerodynamic model are

Hui Xia; Xianyu Meng; Qingwei Chen

2010-01-01

346

Eliciting information for product modeling using process modeling  

Microsoft Academic Search

A product model is a formal and structured definition of product information. The most common procedure for defin- ing a product data model is to first describe the business and\\/or engineering process in a formal process model, then to create a product data model based on the process model. However, there is a logical gap between process modeling and product

Ghang Lee; Charles M. Eastman; Rafael Sacks

2007-01-01

347

Hierarchical Bayesian models as formal models of causal reasoning  

Microsoft Academic Search

Hierarchical Bayesian models (HBMs) have recently been advocated as formal, computational models of causal induction and reasoning. These models assume that abstract, theoretical causal knowledge and observable data constrain causal model representations of the world. HBMs allow us to model various forms of inferences, including the induction of causal model representations, causal categorisation and the induction of causal laws. It

York Hagmayer; Ralf Mayrhofer

2012-01-01

348

Groundwater Model Validation  

SciTech Connect

Models have an inherent uncertainty. The difficulty in fully characterizing the subsurface environment makes uncertainty an integral component of groundwater flow and transport models, which dictates the need for continuous monitoring and improvement. Building and sustaining confidence in closure decisions and monitoring networks based on models of subsurface conditions require developing confidence in the models through an iterative process. The definition of model validation is postulated as a confidence building and long-term iterative process (Hassan, 2004a). Model validation should be viewed as a process not an end result. Following Hassan (2004b), an approach is proposed for the validation process of stochastic groundwater models. The approach is briefly summarized herein and detailed analyses of acceptance criteria for stochastic realizations and of using validation data to reduce input parameter uncertainty are presented and applied to two case studies. During the validation process for stochastic models, a question arises as to the sufficiency of the number of acceptable model realizations (in terms of conformity with validation data). Using a hierarchical approach to make this determination is proposed. This approach is based on computing five measures or metrics and following a decision tree to determine if a sufficient number of realizations attain satisfactory scores regarding how they represent the field data used for calibration (old) and used for validation (new). The first two of these measures are applied to hypothetical scenarios using the first case study and assuming field data consistent with the model or significantly different from the model results. In both cases it is shown how the two measures would lead to the appropriate decision about the model performance. Standard statistical tests are used to evaluate these measures with the results indicating they are appropriate measures for evaluating model realizations. The use of validation data to constrain model input parameters is shown for the second case study using a Bayesian approach known as Markov Chain Monte Carlo. The approach shows a great potential to be helpful in the validation process and in incorporating prior knowledge with new field data to derive posterior distributions for both model input and output.

Ahmed E. Hassan

2006-01-24

349

Pharmacophore modeling for ADME.  

PubMed

One of the major reasons for late-stage failure of drug candidates is due to problems uncovered in pharmacokinetics during clinical trials. There is now a general consensus for earlier consideration of these effects in the drug discovery process. Computer-aided design technology provides us with tools to develop predictive models for such pharmacokinetic properties. Among these tools, we focus on pharmacophore modeling techniques in this article. Pharmacophore models that are reported for various cytochrome P450 (CYP) enzymes are reviewed for the isoenzymes CYP1A2, 2B6, 2C9, 2C19, 2D6, 2E1, and 3A4. In addition pharmacophore models for related metabolic processes through CYP19 (aromatase), CYP51 (14.?-lanosterol demethylase), PXR (pregnane X-receptor), and finally for human intrinsic clearance are also reviewed. The models reported by various scientists are schematically represented in the figures in order to visually demonstrate their similarities and differences. The models developed by different researchers or sometimes even by the same research group for different sets of ligands, provide a clear picture of the challenges in coming up with a single model with good predictive values. One of the main reasons for this challenge is related to relatively large size of the active sites and flexibility of the CYP isoenzymes, which results in multiple binding sites. We propose development of multiple- diverse pharmacophore models for each binding mode (as opposed to a single predictive model for each CYP isoenzyme). After scoring and prioritization of the models, we propose the use of a battery of pharmacophore models for each CYP isoenzyme binding mode to computationally obtain a P450 interaction profile for drug candidates early in the drug development cycle, when decisions on their fate can be made before incurring the costs of synthesis and testing. PMID:23675939

Guner, Osman F; Bowen, J Phillip

2013-01-01

350

2010 Chesapeake Bay Eutrophication Model.  

National Technical Information Service (NTIS)

The Chesapeake Bay Environmental Model Package is a combination of interactive models. The Community Multi-Scale Air Quality Model and a set of regression models compute daily atmospheric nitrogen and phosphorus loads to the Chesapeake Bay watershed and t...

C. F. Cerco M. R. Noel S. Kim

2010-01-01

351

BioVapor Model Evaluation  

EPA Science Inventory

General background on modeling and specifics of modeling vapor intrusion are given. Three classical model applications are described and related to the problem of petroleum vapor intrusion. These indicate the need for model calibration and uncertainty analysis. Evaluation of Bi...

352

Coalbed methane modeling analysis  

Microsoft Academic Search

Systems analyses or the Department of Energy's (DOE) Coalbed Methane Project (CMP) were performed at the Morgantown Energy Technology Center (METC). In the analyses, both reservoir and stimulation models were evaluated using data from US Steel's Oak Grove Coal Degasification Field. In the first part of the study two reservoir models designed for predicting methane and water production from coalbeds,

G. L. Covatch; A. W. Layne; S. P. Salamy

1985-01-01

353

Supercomputers-modeling reality  

Microsoft Academic Search

The mathematical modeling capabilities of supercomputers and the possibilities they open up for scientific research are explored. The need for teraflop machines and progress in that direction are discussed. Some modeling applications are described. These include internal combustion engines, semiconductor crystal growth, electromagnetic simulation and design, molecular biology, imaging, geology, meteorology, ocean services, and turbulence

M. Grossman

1992-01-01

354

Mathematical models of hysteresis  

SciTech Connect

The ongoing research has largely been focused on the development of mathematical models of hysteretic nonlinearities with nonlocal memories. The distinct feature of these nonlinearities is that their current states depend on past histories of input variations. It turns out that memories of hysteretic nonlinearities are quite selective. Indeed, experiments show that only some past input extrema (not the entire input variations) leave their marks upon future states of hysteretic nonlinearities. Thus special mathematical tools are needed in order to describe nonlocal selective memories of hysteretic nonlinearities. The origin of such tools can be traced back to the landmark paper of Preisach. Their research has been primarily concerned with Preisach-type models of hysteresis. All these models have a common generic feature; they are constructed as superpositions of simplest hysteretic nonlinearities-rectangular loops. During the past four years, the study has been by and large centered around the following topics: (1) further development of Scalar and vector Preisach-type models of hysteresis; (2) experimental testing of Preisach-type models of hysteresis; (3) development of new models for viscosity (aftereffect) in hysteretic systems; (4) development of mathematical models for superconducting hysteresis in the case of gradual resistive transitions; (5) software implementation of Preisach-type models of hysteresis; and (6) development of new ideas which have emerged in the course of the research work. The author briefly describes the main scientific results obtained in the areas outlined above.

NONE

1998-08-01

355

Video Self-Modeling  

ERIC Educational Resources Information Center

|Video self-modeling (VSM) first appeared on the psychology and education stage in the early 1970s. The practical applications of VSM were limited by lack of access to tools for editing video, which is necessary for almost all self-modeling videos. Thus, VSM remained in the research domain until the advent of camcorders and VCR/DVD players and,…

Buggey, Tom; Ogle, Lindsey

2012-01-01

356

Symmetry and Model Checking  

Microsoft Academic Search

We show how to exploit symmetry in model checking for concurrent systems containing many identical or isomorphic components. We focus in particular on those composed of many isomorphic processes. In many cases we are able to obtain significant, even exponential, savings in the complexity of model checking.

E. Allen Emerson; A. Prasad Sistla

1993-01-01

357

Stochastic ontogenetic growth model  

Microsoft Academic Search

An ontogenetic growth model (OGM) for a thermodynamically closed system is generalized to satisfy both the first and second law of thermodynamics. The hypothesized stochastic ontogenetic growth model (SOGM) is shown to entail the interspecies allometry relation by explicitly averaging the basal metabolic rate and the total body mass over the steady-state probability density for the total body mass (TBM).

B. J. West

2012-01-01

358

Building models with GOCAD  

Microsoft Academic Search

The aim of this paper is to give a quick overview of some of the different tools available in the GOCAD software package to build 2-D and 3-D models. With the help of this paper and the GOCAD Manual (Mallet, 1993), someone without any knowledge about GOCAD should be able to build any complex model from its representation on a

Arnaud Berlioux

2001-01-01

359

Hidden Process Models.  

National Technical Information Service (NTIS)

This thesis introduces Hidden Process Models (HPMs). HPMs are a probabilistic time series model for data assumed to be generated by a set of processes, where each process is characterized by a unique spatial-temporal signature and a probability distributi...

R. A. Hutchinson

2009-01-01

360

Stereolithography models. Final report  

SciTech Connect

This report describes the first stereolithographic models made, which proved in a new release of ProEngineer software (Parametric Technologies, or PTC) and 3D Systems (Valencia, California) software for the SLA 250 machine. They are a model of benzene and the {alpha}-carbon backbone of the variable region of an antibody.

Smith, R.E.

1995-03-01

361

Modeling prosody: Different approaches  

NASA Astrophysics Data System (ADS)

Prosody pervades all aspects of a speech signal, both in terms of raw acoustic outcomes and linguistically meaningful units, from the phoneme to the discourse unit. It is carried in the suprasegmental features of fundamental frequency, loudness, and duration. Several models have been developed to account for the way prosody organizes speech, and they vary widely in terms of their theoretical assumptions, organizational primitives, actual procedures of application to speech, and intended use (e.g., to generate speech from text vs. to model the prosodic phonology of a language). In many cases, these models overtly contradict one another with regard to their fundamental premises or their identification of the perceptible objects of linguistic prosody. These competing models are directly compared. Each model is applied to the same speech samples. This parallel analysis allows for a critical inspection of each model and its efficacy in assessing the suprasegmental behavior of the speech. The analyses illustrate how different approaches are better equipped to account for different aspects of prosody. Viewing the models and their successes from an objective perspective allows for creative possibilities in terms of combining strengths from models which might otherwise be considered fundamentally incompatible.

Carmichael, Lesley M.

2002-11-01

362

Ørsted initial field model  

Microsoft Academic Search

Magnetic measurements taken by the Ørsted satellite during geomagnetic quiet conditions around January 1, 2000 have been used to derive a spherical harmonic model of the Earth's magnetic field for epoch 2000.0. The maximum degree and order of the model is 19 for internal, and 2 for external, source fields; however, coefficients above degree 14 may not be robust. Such

N. Olsen; R. Holme; G. Hulot; T. Sabaka; T. Neubert; L. Tøffner-Clausen; F. Primdahl; J. Jørgensen; J.-M. Léger; D. Barraclough; J. Bloxham; J. Cain; C. Constable; V. Golovkov; A. Jackson; P. Kotzé; B. Langlais; S. Macmillan; M. Mandea; J. Merayo; L. Newitt; M. Purucker; T. Risbo; M. Stampe; A. Thomson; C. Voorhies

2000-01-01

363

Modeling the space shuttle  

Microsoft Academic Search

We summarize our methodology for modeling space shuttle processing using discrete event simulation. Why the project was initiated, what the overall goals were, how it was funded, and who were the members of the project team are identified. We describe the flow of the space shuttle flight hardware through the supporting infrastructure and how the-model was created to accurately portray

Grant R. Cates; Martin J. Steele; M. Mollaghasemi; G. Rabadi

2002-01-01

364

Polymer ball lightning model  

Microsoft Academic Search

A theoretical model of Ball lightning (BL) is presented. According to this model the BL is an aggregate of polymer molecules. These macromolecules are interknitted or sewn together, and therefore the structure is a polymer net with the corresponding rheologic and fractal properties. Because of the dielectric properties such BL can accumulate and store large amounts of the electrostatic energy

Vladimir L Bychkov

1994-01-01

365

Space Ship Pilot Model  

NSDL National Science Digital Library

The Space Ship Pilot model is a model of motion under Newton's laws with and without resistive forces. The first environment puts the user in control of docking a space shuttle, and the second puts the user in control of docking a boat.

Joiner, David; The Shodor Education Foundation, Inc.

366

Bitzer's Model Reconstructed.  

ERIC Educational Resources Information Center

Reconstructs Lloyd Bitzer's situational model to serve as a guide for the generation of multiperspectival critical assessments of rhetorical discourse. Uses two of President Bush's speeches on the drug crisis to illustrate how the reconstructed model can account for such modern problems as multiple audiences, perceptions, and exigencies. (PA)

Lybarger, Scott; Smith, Craig R.

1996-01-01

367

Computer Virus Propagation Models  

Microsoft Academic Search

The availability of reliable models of computer virus propa- gation would prove useful in a number of ways, in order both to predict future threats, and to develop new containment measures. In this pa- per, we review the most popular models of virus propagation, analyzing the underlying assumptions of each of them, their strengths and their weaknesses. We also introduce

Giuseppe Serazzi; Stefano Zanero

2003-01-01

368

Using Models Effectively  

ERIC Educational Resources Information Center

|Models are crucial to science teaching and learning, yet they can create unforeseen and overlooked challenges for students and teachers. For example, consider the time-tested clay volcano that relies on a vinegar and-baking-soda mixture for its "eruption." Based on a classroom demonstration of that geologic model, elementary students may…

Eichinger, John

2005-01-01

369

Benchmarking the benchmarking models  

Microsoft Academic Search

Purpose – A review of benchmarking literature revealed that there are different types of benchmarking and a plethora of benchmarking process models. In some cases, a model has been uniquely developed for performing a particular type of benchmarking. This poses the following problems: it can create confusion among the users as to whether they should use only the unique benchmarking

G. Anand; Rambabu Kodali

2008-01-01

370

Editor's Corner: Model Biology  

NSDL National Science Digital Library

Models are at the core of the scientific enterprise. They help us make predictions, understand complex systems, generate new ideas, and visualize both the very large and the very small. The generation of models is the creative engine that drives scientifi

Metz, Steve

2011-02-01

371

Nanotechnologies: Risk assessment model  

Microsoft Academic Search

The development and use of nanomaterials has grown widely in the last years. Hence, it is necessary to carry out a careful and aimed risk assessment for the safety of the workers. The objective of this research is a specific assessment model finalized to the workplaces where the personnel work manipulating nanoparticles. This model mainly takes into account the number

F. Giacobbe; L. Monica; D. Geraci

2009-01-01

372

Computer modeling of detonators  

Microsoft Academic Search

A mathematical model of detonators which describes the resistance of the exploding bridgewire or exploding foil initiator as a function of energy deposition will be described. This model includes many parameters that can be adjusted to obtain a close fit to experimental data. This has been demonstrated using recent experimental data taken within Sandia National Laboratories

C. M. Furnberg

1994-01-01

373

Preliminary semiempirical transport models  

SciTech Connect

A class of semiempirical transport models is proposed for testing against confinement data from tokamaks and for use in operations planning and machine design. A reference model is proposed to be compatible with published confinement data. Theoretical considerations are used to express the anomalous transport coefficients in terms of appropriate dimensionless parameters.

Singer, C.E.

1983-11-01

374

Poisson Distribution Model  

NSDL National Science Digital Library

The Poisson Distribution Model shows how to use the Apache Commons Math library (included in EJS) to generate random numbers that follow the Poisson distribution. A histogram of the numbers is displayed. This simple teaching example illustrates the use of the Histogram view element and how to speed up a simulation by running the model several time before updating the view.

Franciscouembre

2013-02-13

375

Lithium battery thermal models  

Microsoft Academic Search

Thermal characteristics and thermal behavior of lithium batteries are important both for the batteries meeting operating life requirements and for safety considerations. Sandia National Laboratories has a broad-based program that includes analysis, engineering and model development. We have determined thermal properties of lithium batteries using a variety of calorimetric methods for many years. We developed the capability to model temperature

Daniel H Doughty; Paul C Butler; Rudolph G Jungst; E. Peter Roth

2002-01-01

376

Modeling Residential Energy Use.  

National Technical Information Service (NTIS)

This paper describes a comprehensive engineering-economic computer model used to simulate energy use in the residential sector from 1970 to 2000. The purpose of the model is to provide an analytical tool with which to evaluate a variety of conservation po...

E. Hirst W. Lin J. Cope

1976-01-01

377

An equatorial scintillation model  

Microsoft Academic Search

Radiowave scintillation in the presence of natural and\\/or high altitude nuclear disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report develops a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed equatorial F layer. The model has been incorporated into Program WBMOD along with subroutines for computing both link geometry and

E. J. Fremouw; R. E. Robins

1985-01-01

378

Composite Load Model Evaluation  

SciTech Connect

The WECC load modeling task force has dedicated its effort in the past few years to develop a composite load model that can represent behaviors of different end-user components. The modeling structure of the composite load model is recommended by the WECC load modeling task force. GE Energy has implemented this composite load model with a new function CMPLDW in its power system simulation software package, PSLF. For the last several years, Bonneville Power Administration (BPA) has taken the lead and collaborated with GE Energy to develop the new composite load model. Pacific Northwest National Laboratory (PNNL) and BPA joint force and conducted the evaluation of the CMPLDW and test its parameter settings to make sure that: • the model initializes properly, • all the parameter settings are functioning, and • the simulation results are as expected. The PNNL effort focused on testing the CMPLDW in a 4-bus system. An exhaustive testing on each parameter setting has been performed to guarantee each setting works. This report is a summary of the PNNL testing results and conclusions.

Lu, Ning; Qiao, Hong (Amy)

2007-09-30

379

Models and Metaphors  

ERIC Educational Resources Information Center

|Humanity delights in spinning conceptual models of the world. These models, in turn, mirror their respective root metaphors. Three root metaphors--spiritual, organic, and mechanical--have dominated western thought. The spiritual metaphor runs from Plato, through Hegel, and connects with Montessori. The organic metaphor extends from Aristotle,…

Ivie, Stanley D.

2007-01-01

380

Data, Modeling and Decisions.  

National Technical Information Service (NTIS)

Past experience with models--and related methods of analysis--may be an inadequate guide for managers considering a use of new tools now available. The latter, viewed as multiple-variable systems models, may differ in their data requirements and decision ...

A . Charnes W. W. Cooper

1965-01-01

381

Calibrating hydraulic network models  

Microsoft Academic Search

Although calibration should always be included in any hydraulic analysis, it is often neglected or done haphazardly. As a result, inappropriate data may be used or data errors may be overlooked, so the resulting hydraulic model is of limited value. The novice may see calibrating a hydraulic network model as a task as daunting as climbing Mt. Everest. This article

Lindell E. Ormsbee; Srinivasa Lingireddy

1997-01-01

382

STREAM WATER QUALITY MODEL  

EPA Science Inventory

QUAL2K (or Q2K) is a river and stream water quality model that is intended to represent a modernized version of the QUAL2E (or Q2E) model (Brown and Barnwell 1987). Q2K is similar to Q2E in the following respects: One dimensional. The channel is well-mixed vertically a...

383

Modeling of stratosphere airship  

Microsoft Academic Search

The dynamics and kinematics model is very important for the analysis of stability, manipulation and control of stratosphere airship. A full modeling approach that includes the computation of aerodynamics of airship and the added mass for the nonlinear dynamics simulation of stratosphere airships is proposed in this paper. In this approach, the aerodynamics of airship is calculated based on a

Xiao-liang Wang; Ye Ma; Xue-xiong Shan

2010-01-01

384

Updating Situation Models  

ERIC Educational Resources Information Center

The authors examined how situation models are updated during text comprehension. If comprehenders keep track of the evolving situation, they should update their models such that the most current information, the here and now, is more available than outdated information. Contrary to this updating hypothesis, E. J. O'Brien, M. L. Rizzella, J. E.…

Zwaan, Rolf A.; Madden, Carol J.

2004-01-01

385

Models for microquasars  

Microsoft Academic Search

I review current models used to interpret the spectra and variability of microquasars. Among other things, I discuss the structure of the accretion flow and its dependence on mass accretion rate, the intrinsic connection between hot comptonizing corona and compact radio jet in the hard state, as well as possible models for the spectral hysteresis observed during outbursts of transient

Julien Malzac

2007-01-01

386

Maximizing mouse cancer models  

Microsoft Academic Search

Animal models of cancer provide an alternative means to determine the causes of and treatments for malignancy, thus representing a resource of immense potential for cancer medicine. The sophistication of modelling cancer in mice has increased to the extent that investigators can both observe and manipulate a complex disease process in a manner impossible to perform in patients. However, owing

Kristopher K. Frese; David A. Tuveson

2007-01-01

387

SCARP2 Model  

NSDL National Science Digital Library

This exercise is a second or familiarization exercise in spreadsheeting, but is also a mathematical model for slope evolution. It uses the concept of "erosivity" (generally, the relative ratio of driving and resisting forces) and slope angle to reshape an initial topography. Finally, it asks the students themselves to come up with a real-world situation worth modeling.

Locke, Bill

388

A Lung Model  

NSDL National Science Digital Library

In this activity, create a model of our lungs. Using simple everyday materials, construct a model that demonstrates how when you breathe, your lungs and diaphragm fill with air and expand. This activity guide includes a step-by-step instructional video.

Center, Saint L.

2013-01-17

389

Thirring x Liouville model  

SciTech Connect

A conformally invariant completely integrable model of classical field theory in two-dimensional space-time that describes the interaction of a scalar and a spinor field is proposed. It is shown that the scattering in the model is nontrivial.

Pogrebkov, A.K.; Talalov, S.V.

1987-09-01

390

String Model Building  

SciTech Connect

In this talk I review some recent progress in heterotic and F theory model building. I then consider work in progress attempting to find the F theory dual to a class of heterotic orbifold models which come quite close to the MSSM.

Raby, Stuart [Physics Department, Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210 (United States)

2010-02-10

391

Modeling for Insights  

SciTech Connect

System Dynamics is a computer-aided approach to evaluating the interrelationships of different components and activities within complex systems. Recently, System Dynamics models have been developed in areas such as policy design, biological and medical modeling, energy and the environmental analysis, and in various other areas in the natural and social sciences. The real power of System Dynamic modeling is gaining insights into total system behavior as time, and system parameters are adjusted and the effects are visualized in real time. System Dynamic models allow decision makers and stakeholders to explore long-term behavior and performance of complex systems, especially in the context of dynamic processes and changing scenarios without having to wait decades to obtain field data or risk failure if a poor management or design approach is used. The Idaho National Laboratory recently has been developing a System Dynamic model of the US Nuclear Fuel Cycle. The model is intended to be used to identify and understand interactions throughout the entire nuclear fuel cycle and suggest sustainable development strategies. This paper describes the basic framework of the current model and presents examples of useful insights gained from the model thus far with respect to sustainable development of nuclear power.

Jacob J. Jacobson; Gretchen Matthern

2007-04-01

392

Structural Equation Model Trees  

ERIC Educational Resources Information Center

|In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

2013-01-01

393

Math, Science, and Models  

ERIC Educational Resources Information Center

|For the past five summers, the authors have taught summer school to recent immigrants and refugees. Their experiences with these fourth-grade English language learners (ELL) have taught them the value of using models to build scientific and mathematical concepts. In this article, they describe the use of different forms of 2- and 3-D models to…

Weinburgh, Molly; Silva, Cecilia

2011-01-01

394

LONGPRO Stream Modeling Exercise  

NSDL National Science Digital Library

The purpose of this exercise is to integrate modeling with field data. The activity includes links to a "virtual field trip" of maps and photographs. Data from a creek is included in the field trip and students use an Excel spreadsheet model to analyze the data.

Locke, Bill

395

Kepler Paper Model  

NSDL National Science Digital Library

In this activity, learners build a paper model of the spacecraft and photometer (telescope) used during NASA's Kepler Mission. This resource includes files for the model, which can be printed out on heavy stock paper, and instructions for assembling the various parts.

Nasa

2005-01-01

396

Spatially homothetic cosmological models  

Microsoft Academic Search

Spatially homothetic cosmological models are defined as space-time manifolds acted on by a 3-parameter group of transformations transitive over spacelike hypersurfaces, whose effect is to multiply the metric by a constant conformal factor. Previous work on these models is reviewed briefly and the algebraic classification scheme of Eardley is described. Explicit forms of the metric and group generators are given

J. P. Luminet

1978-01-01

397

Modeling and simulation  

SciTech Connect

This book presents the papers given at a conference on computerized simulation. Topics considered at the conference included expert systems, modeling in electric power systems, power systems operating strategies, energy analysis, a linear programming approach to optimum load shedding in transmission systems, econometrics, simulation in natural gas engineering, solar energy studies, artificial intelligence, vision systems, hydrology, multiprocessors, and flow models.

Hanham, R.; Vogt, W.G.; Mickle, M.H.

1986-01-01

398

Submarine Dynamic Modeling  

Microsoft Academic Search

This paper discusses the development of a dynamic model for a torpedo shaped sub- marine. Expressions for hydrostatic, added mass, hydrodynamic, control surface and pro- peller forces and moments are derived from first principles. Experimental data obtained from flume tests of the submarine are inserted into the model in order to provide computer simulations of the open loop behavior of

Peter Ridley; Julien Fontan; Peter Corke

399

Models of Coordination  

Microsoft Academic Search

While software is becoming decomposed in more and more finegrained entities, the interactions amongst those become of major importance. While method- ologies for building such components are well established, the design and support of their interplay can not build on commonly understood and well defined models. In this paper, we review several coordination models from various disciplines, and describe how

Robert Tolksdorf

2000-01-01

400

Legal Policy Optimizing Models  

ERIC Educational Resources Information Center

|The use of mathematical models originally developed by economists and operations researchers is described for legal process research. Situations involving plea bargaining, arraignment, and civil liberties illustrate the applicability of decision theory, inventory modeling, and linear programming in operations research. (LBH)|

Nagel, Stuart; Neef, Marian

1977-01-01

401

Properties of ZF Models  

Microsoft Academic Search

Summary. The article deals with the concepts of satisfiability of ZF set theory language formulae in a model (a non-empty family of sets) and the axioms of ZF theory introduced in (6). It is shown that the transitive model satisfies the axiom of extensionality and that it satisfies the axiom of pairs if and only if it is closed to

Grzegorz Bancerek

1990-01-01

402

MATHEMATICAL MODELLING OF HANTAVIRUS  

Microsoft Academic Search

I review recent mathematical models of the epizootic of Hantavirus in mice popu- lations. The models are mainly based on field observations of Peromyscus maniculatus populations in New Mexico, which hosts Sin Nombre virus. The sporadic disappear- ance of the infection during times of adverse conditions is explained as a phase tran- sition controlled by the environment. Refinements of the

Guillermo Abramson

403

Sinusoids: Applications and Modeling  

NSDL National Science Digital Library

This demo actively involves students via the software simulations so that the determination of the sinusoidal model has a geometric flavor that complements the algebraic tools stressed in texts. This approach also introduces a modeling aspect since in some situations we may only be able to obtain a "close" approximation to the actual curve or data. Animations and Excel routines are included.

Roberts, Lila F.; Hill, David R.

2004-07-21

404

Multiscale modeling of respiration  

Microsoft Academic Search

A multiscale mathematical model was developed to distinguish responses of external and cellular respiration to exercise of moderate intensity. The simulation shows that the characteristic MRTs of external and cellular respiration are similar even when a transit delay exists between the tissue cells and the lungs. The results of our model show that the O2 transport processes from lungs to

Haiying Zhou; NICOLA LAI; GERALD M. SAIDEL; MARCO E. CABRERA

2009-01-01

405

Minimalistic neutrino mass model  

Microsoft Academic Search

We consider the simplest model which solves the solar and atmospheric neutrino puzzles, in the sense that it contains the smallest amount of beyond the Standard Model ingredients. The solar neutrino data is accounted for by Planck-mass effects while the atmospheric neutrino anomaly is due to the existence of a single right-handed neutrino at an intermediate mass scale between 109

André de Gouvêa; José W. F. Valle

2001-01-01

406

Outside Users Payload Model.  

National Technical Information Service (NTIS)

The outside users payload model which is a continuation of documents and replaces and supersedes the July 1984 edition is presented. The time period covered by this model is 1985 through 2000. The following sections are included: (1) definition of the sco...

1985-01-01

407

Face modeling for recognition  

Microsoft Academic Search

D Human face models have been widely used in appli- cations such as facial animation, video compressiodcoding, augmented reality, head tracking, facial expression recogni- tion, human action recognition, and face recognition. Mod- eling human faces provides a potential solution to identi- fying faces with variations in illumination, pose, and facial expression. We propose a method of modeling human faces based

Rein-lien Hsu; Anil K. Jain

2001-01-01

408

Mortality modeling: A review  

Microsoft Academic Search

Looking at survival in terms of biological indicators of aging has given rise to various models of mortality, some of which we review here. The most notable models are that of Strehler and Mildvan, which relates the force of mortality to the ability of organisms to compensate for stress, and that of Sacher and Trucco, which describes the role played

Anatoli I. Yashin; Ivan A. Iachine; Alexander S. Begun

2000-01-01

409

ADVANCED CHEMISTRY BASINS MODEL  

Microsoft Academic Search

The advanced Chemistry Basin Model project has been operative for 48 months. During this period, about half the project tasks are on projected schedule. On average the project is somewhat behind schedule (90%). Unanticipated issues are causing model integration to take longer then scheduled, delaying final debugging and manual development. It is anticipated that a short extension will be required

William Goddard; Lawrence Cathles; Mario Blanco; Paul Manhardt; Peter Meulbroek; Yongchun Tang

2004-01-01

410

Modeling TCP Latency  

Microsoft Academic Search

Several analytic models describe the steady-state throughput of bulk transfer TCP flows as a function of round trip time and packet loss rate. These models describe flows based on the assumption that they are long enough to sustain many packet losses. However, most TCP trans- fers across today's Internet are short enough to see few, if any, losses and consequently

Neal Cardwell; Stefan Savage; Thomas E. Anderson

2000-01-01

411

Multilevel Mixture Factor Models  

ERIC Educational Resources Information Center

|Factor analysis is a statistical method for describing the associations among sets of observed variables in terms of a small number of underlying continuous latent variables. Various authors have proposed multilevel extensions of the factor model for the analysis of data sets with a hierarchical structure. These Multilevel Factor Models (MFMs)…

Varriale, Roberta; Vermunt, Jeroen K.

2012-01-01

412

Logistic Model Trees  

Microsoft Academic Search

Tree induction methods and linear models are popular techniques for supervised learning tasks, both for the prediction of nominal classes and numeric values. For predicting numeric quantities, there has been work on combining these two schemes into ‘model trees’, i.e. trees that contain linear regression functions at the leaves. In this paper, we present an algorithm that adapts this idea

Niels Landwehr; Mark Hall; Eibe Frank

2005-01-01

413

Logistic Model Trees  

Microsoft Academic Search

Tree induction methods and linear models are popular techniques for supervised learning tasks, both for the prediction of nominal classes and numeric values. For predicting numeric quantities, there has been work on combining these two schemes into 'model trees', i.e. trees that contain linear regression functions at the leaves. In this paper, we present an algorithm that adapts this idea

Niels Landwehr; Mark Hall; Eibe Frank

2003-01-01

414

Automated Student Model Improvement  

ERIC Educational Resources Information Center

Student modeling plays a critical role in developing and improving instruction and instructional technologies. We present a technique for automated improvement of student models that leverages the DataShop repository, crowd sourcing, and a version of the Learning Factors Analysis algorithm. We demonstrate this method on eleven educational…

Koedinger, Kenneth R.; McLaughlin, Elizabeth A.; Stamper, John C.

2012-01-01

415

Modeling AGV systems  

Microsoft Academic Search

Computer simulation is often used as an analysis tool during the design of Automated Guided Vehicle (AGV) systems. However, because of the complexities inherent in automated material handling systems, general-purpose simulation languages must be used creatively to capture the desired detail in the model. This paper presents some general concepts which can be used to model AGV systems. Also, some

Deborah A. Davis; Calder Sq

1986-01-01

416

Model transformations in Converge  

Microsoft Academic Search

Model transformations are currently the focus of much interest and research due to the OMG's QVT initiative. Current proposals for model transformation lan- guages can be divided into two main camps: those taking a 'declarative' approach, and those opting for an 'imperative' approach. In this paper we detail an imper- ative, meta-circular, object orientated, pattern matching programming language Converge which

Laurence Tratt; Tony Clark

2003-01-01

417

AGRICULTURAL SIMULATION MODEL (AGSIM)  

EPA Science Inventory

AGSIM is a large-scale econometric simulation model of regional crop and national livestock production in the United States. The model was initially developed to analyze the aggregate economic impacts of a wide variety issues facing agriculture, such as technological change, pest...

418

Lessons from Leading Models  

ERIC Educational Resources Information Center

|Quint reports on a synthesis evaluation of three widely used high school reform models--Talent Development, First Things First, and career academies. She highlights approaches within each model that helped high schools restructure themselves in ways that affected student outcomes, particularly for struggling 9th graders and students from…

Quint, Janet

2008-01-01

419

Pragmatization Of Conceptual Modelling  

Microsoft Academic Search

The aim of the paper is to show how speech act theory can be used in systems development as a theoretical foundation for conceptual modelling. The specific issue addressed is how to make explicit the connection between the conceptual model and the pragmatic use of the information system within a social action context. This implies an integration of traditional conceptual

Pär J. Ågerfalk; Owen Eriksson

2002-01-01

420

Models in Biology.  

ERIC Educational Resources Information Center

|Addresses the most popular models currently being chosen for biological research and the reasons behind those choices. Among the current favorites are zebra fish, fruit flies, mice, monkeys, and yeast. Concludes with a brief examination of the ethical issues involved, and why some animals may need to be replaced in research with model systems.…

Flannery, Maura C.

1997-01-01

421

FASST Vegetation Models.  

National Technical Information Service (NTIS)

The one-dimensional dynamic state of the ground model FASST (Fast All-season Soil Strength) is a state of the ground model developed by Frankenstein and Koenig (2004) as part of the Army's Battlespace Terrain Reasoning and Awareness (BTRA) research progra...

S. Frankenstein G. Koenig

2004-01-01

422

Virtual clay modeling system  

Microsoft Academic Search

This paper describes a CAD system in which a user can directly manipulate the shape of a virtual object like a clay model and can produce its solid model data. The key component of its hardware is a special input device with a 3D position tracker and a tactile sensor. In this system, the movement of a virtual object is

Ken-ichi Kameyama

1997-01-01

423

Cranial Nerves Model  

NSDL National Science Digital Library

Lesson is designed to introduce students to cranial nerves through the use of an introductory lecture. Students will then create a three-dimensional model of the cranial nerves. An information sheet will accompany the model in order to help students learn crucial aspects of the cranial nerves.

Juliann Garza (University of Texas-Pan American Physician Assistant Studies)

2010-08-16

424

VENTURI SCRUBBER PERFORMANCE MODEL  

EPA Science Inventory

The paper presents a new model for predicting the particle collection performance of venturi scrubbers. It assumes that particles are collected by atomized liquid only in the throat section. The particle collection mechanism is inertial impaction, and the model uses a single drop...

425

Unitary Response Regression Models  

ERIC Educational Resources Information Center

The dependent variable in a regular linear regression is a numerical variable, and in a logistic regression it is a binary or categorical variable. In these models the dependent variable has varying values. However, there are problems yielding an identity output of a constant value which can also be modelled in a linear or logistic regression with…

Lipovetsky, S.

2007-01-01

426

Pathological Gambling: Psychiatric Models  

ERIC Educational Resources Information Center

|Three psychiatric conceptual models: addictive, obsessive-compulsive spectrum and mood spectrum disorder have been proposed for pathological gambling. The objectives of this paper are to (1) evaluate the evidence base from the most recent reviews of each model, (2) update the evidence through 2007 and (3) summarize the status of the evidence for…

Westphal, James R.

2008-01-01

427

Phenomenology of SUSY models  

NASA Astrophysics Data System (ADS)

This article presents a review of the minimal supersymmetric extension of the Standard Model (MSSM), concentrating mainly in the steps needed to derive the lagrangian of the model within the superspace formalism. Some attention is also given to the reduction of parameters that results from incorporating the hypothesis of Grand Unification and low energy Supergravity; the most salient phenomenological consequences are also discussed.

Diaz-Cruz, J. Lorenzo

1996-02-01

428

Money-saving model  

Microsoft Academic Search

This article addresses refinements in computer models and satellite images that allowed for the reduction of costs for upgrading the dams and spillways on the Au Sable River. The upgrades were for increasing the capacity of the dams and spillways to accommodate a probable maximum flood. The topics of the article include a description of the basic watershed model, refining

C. Mettel; D. McGraw; S. Strater

1994-01-01

429

Modelling contextual security policies  

Microsoft Academic Search

As computer infrastructures become more complex, security models must provide means to handle more flexible and dynamic requirements. In the Organization Based Access Control (OrBAC) model, it is possible to express such requirements using the notion of context. In OrBAC, each security rule (permission, prohibition, obligation or dispensa- tion) only applies in a given context. A context is viewed as

Nora Cuppens-Boulahia

430

Dynamic Selection of Models.  

National Technical Information Service (NTIS)

The DSM algorithm solves the model-selection problem for a ventilator-management advisor (VMA). A VMA is a computer program that applies patient-specific models of physiology to interpret intensive-care unit (ICU) data and to predict the effects of altern...

G. W. Rutledge

1995-01-01

431

DYNAMIC ESTUARY MODEL PERFORMANCE  

EPA Science Inventory

Applications of the Dynamic Estuary Model (DEM) to both the Delaware and Potomac Estuaries by the Environmental Protection Agency during the 1970s are summarized and evaluated. Methods for calibrating, refining, and validating this model, and statistics for evaluating its perform...

432

Animal models of candidiasis.  

PubMed

Animal models are powerful tools to study the pathogenesis of diverse types of candidiasis. Murine models are particularly attractive because of cost, ease of handling, technical feasibility, and experience with their use. In this chapter, we describe methods for two of the most popular murine models of disease caused by Candida albicans. In an intravenously disseminated candidiasis (DC) model, immunocompetent mice are infected by lateral tail vein injections of a C. albicans suspension. Endpoints include mortality, tissue burdens of infection (most importantly in the kidneys, although spleens and livers are sometimes also assessed), and histopathology of infected organs. In a model of oral/esophageal candidiasis, mice are immunosuppressed with cortisone acetate and inoculated in the oral cavities using swabs saturated with a C. albicans suspension. Since mice do not die from oral candidiasis in this model, endpoints are tissue burden of infection and histopathology. The DC and oral/esophageal models are most commonly used for studies of C. albicans virulence, in which the disease-causing ability of a mutant strain is compared with an isogenic parent strain. Nevertheless, the basic techniques we describe are also applicable to models adapted to investigate other aspects of pathogenesis, such as spatiotemporal patterns of gene expression, specific aspects of host immune response and assessment of antifungal agents, immunomodulatory strategies, and vaccines. PMID:19152040

Clancy, Cornelius J; Cheng, Shaoji; Nguyen, Minh Hong

2009-01-01

433

Introduction to Population Modeling.  

ERIC Educational Resources Information Center

|The focus is on the formulation and solution of mathematical models with the idea of a population employed mainly as a pedogogical tool. If the biological setting is stripped away, the material can be interpreted as topics or the qualitative behavior of differential and difference equations. The first group of models investigate the dynamics of a…

Frauenthal, James C.

434

The Transferable Belief Model  

Microsoft Academic Search

Abstract: We describe the Transferable Belief Model, a model for representing quantified beliefs based on belief functions. Beliefs can be held at two levels: 1) a credal level where beliefs are entertained and quantified by belief functions, 2) a pignistic level where beliefs can be used to make decisions and are quantified by probability functions. The relation between the belief

Philippe Smets; Robert Kennes

1994-01-01

435

The Transferable Belief Model  

Microsoft Academic Search

We describe the Transferable Belief Model, a model for representing quantified beliefs based on belief functions. Beliefs can be held at two levels: 1) a credal level where beliefs are entertained and quantified by belief functions, 2) a pignistic level where beliefs can be used to make decisions and are quantified by probability functions. The relation between the belief function

Philippe Smets; Yen-teh Hsia; Alessandro Saffiotti; Robert Kennes; Elizabeth Umkehrer; E. Umkehren

1991-01-01

436

Modelling University Governance  

ERIC Educational Resources Information Center

|Twentieth century governance models used in public universities are subject to increasing doubt across the English-speaking world. Governments question if public universities are being efficiently governed; if their boards of trustees are adequately fulfilling their trust obligations towards multiple stakeholders; and if collegial models of…

Trakman, Leon

2008-01-01

437

STORM WATER MANAGEMENT MODEL  

EPA Science Inventory

Storm Water Management Model (SWMM) is a comprehensive model for analysis of quantity and quality problems associated with urban runoff. Both single-event and continuous simulation may be performed on catchments having storm sewers, combined sewers, and natural drainage, for pred...

438

Video Self-Modeling  

ERIC Educational Resources Information Center

Video self-modeling (VSM) first appeared on the psychology and education stage in the early 1970s. The practical applications of VSM were limited by lack of access to tools for editing video, which is necessary for almost all self-modeling videos. Thus, VSM remained in the research domain until the advent of camcorders and VCR/DVD players and,…

Buggey, Tom; Ogle, Lindsey

2012-01-01

439

Erosion by Wind: Modeling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Models of wind erosion are used to investigate fundamental processes and guide resource management. Many models are similar in that - temporal variables control soil wind erodibility; erosion begins when friction velocity exceeds a threshold; and transport capacity for saltation/creep is proportion...

440

Modeling of energy economics  

Microsoft Academic Search

Descriptions, with flow charts and diagrams, outline three models used in energy economics. The Electric Utility Model describes finances of a regulated utility based on demand projections, debt interest rates, preferred dividend rates, and the expected rate of return on equity. Decision rules on using long-term debts, preferred, or common stock to raise capital are incorporated in such a way

M. S. Carliner; I. Gershkoff

1975-01-01

441

Examples of Mathematical Modeling  

PubMed Central

Mathematical modeling is being increasingly recognized within the biomedical sciences as an important tool that can aid the understanding of biological systems. The heavily regulated cell renewal cycle in the colonic crypt provides a good example of how modeling can be used to find out key features of the system kinetics, and help to explain both the breakdown of homeostasis and the initiation of tumorigenesis. We use the cell population model by Johnston et al.5 to illustrate the power of mathematical modeling by considering two key questions about the cell population dynamics in the colonic crypt. We ask: how can a model describe both homeostasis and unregulated growth in tumorigenesis; and to which parameters in the system is the model most sensitive? In order to address these questions, we discuss what type of modeling approach is most appropriate in the crypt. We use the model to argue why tumorigenesis is observed to occur in stages with long lag phases between periods of rapid growth, and we identify the key parameters.

Johnston, Matthew D.; Edwards, Carina M.; Bodmer, Walter F.; Maini, Philip K.; Chapman, S. Jonathan

2008-01-01

442

Using Models Effectively  

ERIC Educational Resources Information Center

Models are crucial to science teaching and learning, yet they can create unforeseen and overlooked challenges for students and teachers. For example, consider the time-tested clay volcano that relies on a vinegar and-baking-soda mixture for its "eruption." Based on a classroom demonstration of that geologic model, elementary students may interpret…

Eichinger, John

2005-01-01

443

Models of technology diffusion  

Microsoft Academic Search

The literature on new technology diffusion is vast, and it spills over many conventional disciplinary boundaries. This paper surveys the literature by focusing on alternative explanations of the dominant stylized fact: that the usage of new technologies over time typically follows an S-curve. The most commonly found model which is used to account for this model is the so-called epidemic

P. A. Geroski

2000-01-01

444

Electricity Market Modeling Trends  

Microsoft Academic Search

The trend towards competition in the electricity sector has led to efforts by the research community to develop decision and analysis support models adapted to the new market context. This paper focuses on electricity generation market modeling. Its aim is to help to identify, classify and characterize the somewhat confusing diversity of approaches that can be found in the technical

Mariano Ventosa; Álvaro Baíllo; Andrés Ramos; Michel Rivier

2004-01-01

445

On Ising models  

Microsoft Academic Search

For various Ising models two approaches are discussed, one is that of simulating lattices, also called gauging on exact equations, the other is that of calculating analytical expressions for the boundary free energy of Ising lattices. The first approach allows to conjecture a solution for some Ising models, that have sofar not been solved, once some exact partial result for

C. Hoede; H. J. W. Zandvliet

2006-01-01

446

New IRFPA device model  

Microsoft Academic Search

Existing infrared IRFPA models lack simplicity for setting up the detector's architecture\\/structure and lack continuity between IR detector material, IR detector processes, detector architecture, and detector operation. Existing models also lack the ability to reveal spatially and quantitatively the full impact of the detector's material, process and architecture on IRFPA performance. This paper discusses the development of a new IRFPA

Glenn T. Hess; Davy Dai; Thomas J. Sanders; Gwendolyn W. Newsome; Theodore Fischer

1999-01-01

447

Generalized gamma frailty model.  

PubMed

In this article, we present a frailty model using the generalized gamma distribution as the frailty distribution. It is a power generalization of the popular gamma frailty model. It also includes other frailty models such as the lognormal and Weibull frailty models as special cases. The flexibility of this frailty distribution makes it possible to detect a complex frailty distribution structure which may otherwise be missed. Due to the intractable integrals in the likelihood function and its derivatives, we propose to approximate the integrals either by Monte Carlo simulation or by a quadrature method and then determine the maximum likelihood estimates of the parameters in the model. We explore the properties of the proposed frailty model and the computation method through a simulation study. The study shows that the proposed model can potentially reduce errors in the estimation, and that it provides a viable alternative for correlated data. The merits of proposed model are demonstrated in analysing the effects of sublingual nitroglycerin and oral isosorbide dinitrate on angina pectoris of coronary heart disease patients based on the data set in Danahy et al. (sustained hemodynamic and antianginal effect of high dose oral isosorbide dinitrate. Circulation 1977; 55:381-387). PMID:16220516

Balakrishnan, N; Peng, Yingwei

2006-08-30

448

Smoothing and mixed models  

Microsoft Academic Search

Smoothing methods that use basis functions with penalisation can be formulated as maximum likelihood estimators and best predictors in a mixed model framework. Such connections are at least a quarter of a century old but, perhaps with the advent of mixed model software, have led to a paradigm shift in the eld of smoothing. The reason is that most, perhaps

M. P. WAND

2003-01-01

449

Make a Model Caldera  

NSDL National Science Digital Library

In this quick activity (page 2 of PDF), learners will model how large depressions near the top of a volcano are formed by using an inflating and deflating balloon submerged in flour. The model illustrates how volcanic ground swells and collapses as pressure builds and drains from a magma reservoir. Relates to the linked video, DragonflyTV GPS: Lava Flow.

Twin Cities Public Television, Inc.

2007-01-01

450

Dual-Schemata Model  

NASA Astrophysics Data System (ADS)

In this paper, a new machine-learning method, called Dual-Schemata model, is presented. Dual-Schemata model is a kind of self-organizational machine learning methods for an autonomous robot interacting with an unknown dynamical environment. This is based on Piaget's Schema model, that is a classical psychological model to explain memory and cognitive development of human beings. Our Dual-Schemata model is developed as a computational model of Piaget's Schema model, especially focusing on sensori-motor developing period. This developmental process is characterized by a couple of two mutually-interacting dynamics; one is a dynamics formed by assimilation and accommodation, and the other dynamics is formed by equilibration and differentiation. By these dynamics schema system enables an agent to act well in a real world. This schema's differentiation process corresponds to a symbol formation process occurring within an autonomous agent when it interacts with an unknown, dynamically changing environment. Experiment results obtained from an autonomous facial robot in which our model is embedded are presented; an autonomous facial robot becomes able to chase a ball moving in various ways without any rewards nor teaching signals from outside. Moreover, emergence of concepts on the target movements within a robot is shown and discussed in terms of fuzzy logics on set-subset inclusive relationships.

Taniguchi, Tadahiro; Sawaragi, Tetsuo

451

Modelling behavioural contagion.  

PubMed

The last decade has seen much work on quantitative understanding of human behaviour, with online social interaction offering the possibility of more precise measurement of behavioural phenomena than was previously possible. A parsimonious model is proposed that incorporates several observed features of behavioural contagion not seen in existing epidemic model schemes, leading to metastable behavioural dynamics. PMID:21325317

House, Thomas

2011-02-16

452

Modelling behavioural contagion  

PubMed Central

The last decade has seen much work on quantitative understanding of human behaviour, with online social interaction offering the possibility of more precise measurement of behavioural phenomena than was previously possible. A parsimonious model is proposed that incorporates several observed features of behavioural contagion not seen in existing epidemic model schemes, leading to metastable behavioural dynamics.

House, Thomas

2011-01-01

453

Theory of Chemical Modeling  

Microsoft Academic Search

In order to deal with the complexity of natural systems simplified models are employed to illustrate the principal and regulatory factors controlling a chemical system. Following the aphorism of Albert Einstein: Everything should be made as simple as possible, but not simpler, models need not to be completely realistic to be useful (Stumm and Morgan 1996), but need to meet

Michael Kühn

2001-01-01

454

External System Modeling  

Microsoft Academic Search

In this thesis a novel design strategy is presented. The key elements of the design strategy comprise the modeling of the physical sources, the separation of the system into the design component and the external system, the characterization of the external system as a complex source, and finally the use of the complex source\\/design component model to optimize the performance

Bryce Kevin Gardner

1995-01-01

455

Groves Model Accuracy Study.  

National Technical Information Service (NTIS)

USAFETAC was tasked to review the scientific literature for studies of the Groves Neutral Density Climatology Model and compare the Groves Model with others in the 30-60 km range. The tasking included a request to investigate the merits of comparing accur...

M. C. Peterson

1991-01-01

456

Dynamic topic models  

Microsoft Academic Search

A family of probabilistic time series models is developed to analyze the time evolution of topics in large document collections. The approach is to use state space models on the natural param- eters of the multinomial distributions that repre- sent the topics. Variational approximations based on Kalman filters and nonparametric wavelet re- gression are developed to carry out approximate posterior

David M. Blei; John D. Lafferty

2006-01-01

457

Animal models of osteoarthritis.  

PubMed

Animal models of osteoarthritis are used to study the pathogenesis of cartilage degeneration and to evaluate potential antiarthritic drugs for clinical use. Animal models of naturally occurring osteoarthritis (OA) occur in knee joints of guinea pigs, mice and other laboratory animal species. Transgenic models have been developed in mice. Commonly utilized surgical instability models include medial meniscal tear in guinea pigs and rats, medial or lateral partial meniscectomy in rabbits, medial partial or total meniscectomy or anterior cruciate transection in dogs. Additional models of cartilage degeneration can be induced by intra-articular iodoacetate injection or by administration of oral or parenteral quinolone antibiotics. None of these models have a proven track record of predicting efficacy in human disease since there are no agents that have been proven to provide anything other than symptomatic relief in human OA. However, agents that are active in these models are currently in clinical trials. Methodologies, gross and histopathologic features and comparisons to human disease will be discussed for the various models. PMID:15758487

Bendele, A M

2001-06-01

458

Procedural modeling of buildings  

Microsoft Academic Search

CGA shape, a novel shape grammar for the procedural modeling of CG architecture, produces building shells with high visual quality and geometric detail. It produces extensive architectural models for computer games and movies, at low cost. Context sensitive shape rules allow the user to specify interactions between the entities of the hierarchical shape descriptions. Selected examples demonstrate solutions to previously

Pascal Müller; Peter Wonka; Simon Haegler; Andreas Ulmer; Luc J. Van Gool

2006-01-01

459

Interactive modeling of Muqarnas  

Microsoft Academic Search

Muqarnas is a mesmerizing 3D feature of Islamic architecture that exhibit intricate geometry. Such designs are composed of several basic structures combined in successive layers, producing complicated 3D surfaces. In this paper we propose a new approach for interactive modelling of muqarnas based on their layered structure. As a guidance for the modeling workflow, floor plans are used. We also

N. Hamekasi; F. F. Samavati; A. Nasri

2011-01-01

460

Verifying and validating simulation models  

Microsoft Academic Search

This paper discusses verification and validation of simulation models. The different approaches to deciding model validity am presented; how model verification and validation relate to the model development process are discussed; various validation techniques are defined, conceptual model validity, model verification, operational validity, and data validity are described; ways to document results are given; and a recommended procedure is presented.

Robert G. Sargent

1996-01-01

461

Modeling and simulation of friction  

Microsoft Academic Search

Two new models for 'slip-stick' friction are presented. One, called the 'bristle model,' is an approximation designed to capture the physical phenomenon of sticking. This model is relatively inefficient numerically. The other model, called the 'reset integrator model,' does not capture the details for the sticking phenomenon, but is numerically efficient and exhibits behavior similar to the model proposed by

David A. Haessig; Bernard Friedland

1991-01-01

462

Active Shape Models - 'Smart Snakes  

Microsoft Academic Search

We describe 'Active Shape Models' which iteratively adapt to refine esti- mates of the pose, scale and shape of models of image objects. The method uses flexible models derived from sets of training examples. These models, known as Point Distribution Models, represent objects as sets of labelled points. An initial estimate of the location of the model points in an

T. F. Cootes; C. J. Taylor

1992-01-01

463

Modeling evapotranspiration by combing a two-source model, a leaf stomatal model, and a light-use efficiency model  

NASA Astrophysics Data System (ADS)

A new version of evapotranspiration model was proposed.A canopy conductance model was used in the new model.Both GPP and ET was estimated in the model.The model illustrated good agreement with observations at two ecosystems.The model has the potential to be used at regional scale.

Hu, Zhongmin; Li, Shenggong; Yu, Guirui; Sun, Xiaomin; Zhang, Leiming; Han, Shijie; Li, Yingnian

2013-09-01

464

Binary models for marginal independence  

Microsoft Academic Search

Log-linear models are a classical tool for the analysis of contingency tables. In particular, the subclass of graphical log-linear models provides a general framework for modelling conditional independences. However, with the exception of special structures, marginal independence hypotheses cannot be accommodated by these traditional models. Focusing on binary variables, we present a model class that provides a framework for modelling

Mathias Drton; Thomas S. Richardson

2008-01-01

465

Modeling developmental cognitive neuroscience.  

PubMed

In the past few years connectionist models have greatly contributed to formulating theories of cognitive development. Some of these models follow the approach of developmental cognitive neuroscience in exploring interactions between brain development and cognitive development by integrating structural change into learning. We describe two classes of these models. The first focuses on experience-dependent structural elaboration within a brain region by adding or deleting units and connections during learning. The second models the gradual integration of different brain areas based on combinations of experience-dependent and maturational factors. These models provide new theories of the mechanisms of cognitive change in various domains and they offer an integrated framework to study normal and abnormal development, and normal and impaired adult processing. PMID:16603407

Westermann, Gert; Sirois, Sylvain; Shultz, Thomas R; Mareschal, Denis

2006-04-17

466

Conformal superspace ?-models  

NASA Astrophysics Data System (ADS)

We review recent developments in the context of two-dimensional conformally invariant ?-models. These quantum field theories play a prominent role in the covariant superstring quantization in flux backgrounds and in the analysis of disordered systems.We present supergroup WZW models as primary examples of logarithmic conformal field theories, whose structure is almost entirely determined by the underlying supergeometry. In particular, we discuss the harmonic analysis on supergroups and supercosets and point out the subtleties of Lie superalgebra representation theory that are responsible for the emergence of logarithmic representations. Furthermore, special types of marginal deformations of supergroup WZW models are studied which only exist if the Killing form is vanishing. We show how exact expressions for anomalous dimensions of boundary fields can be derived using quasi-abelian perturbation theory. Finally, the knowledge of the exact spectrum is used to motivate a duality between the OSP(4|2) symmetric Gross-Neveu model and the S3 supersphere ?-model.

Mitev, Vladimir; Quella, Thomas; Schomerus, Volker

2011-09-01

467

Ballistics and Orbits Model  

NSDL National Science Digital Library

The EJS Ballistics and Orbits model displays ballistic trajectories near the Earth. The model shows the trajectory with respect to the inertial coordinate system and the trajectory as seen from a point of view that is co-rotating with the Earth. You can examine and modify this simulation if you have EJS installed by right-clicking within the plot and selecting âOpen EJS Modelâ from the pop-up menu item. The Ballistics and Orbits model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_nl_teunissen_ballistics_and_orbits.jar file will run the program if Java is installed. Additional information about this model can be found by visiting the authorâs web site: http://www.cleonis.nl/index.htm.

Teunissen, Cleon

2009-11-03

468

Binomial Distribution Model  

NSDL National Science Digital Library

The EJS Binomial Distribution Model calculates the binomial distribution. You can change the number of trials and probability. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Binomial Distribution Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_BinomialDistribution.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-04-23

469

Molecular Dynamics Model  

NSDL National Science Digital Library

The EJS Molecular Dynamics model is constructed using the Lennard-Jones potential truncated at a distance of 3 molecular diameters. The motion of the molecules is governed by Newton's laws, approximated using the Verlet algorithm with the indicated time step. For sufficiently small time steps dt, the system's total energy should be approximately conserved. The Molecular Dynamics model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_md_MolecularDynamics.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-11-16

470

Global ice sheet modeling  

SciTech Connect

The University of Maine conducted this study for Pacific Northwest Laboratory (PNL) as part of a global climate modeling task for site characterization of the potential nuclear waste respository site at Yucca Mountain, NV. The purpose of the study was to develop a global ice sheet dynamics model that will forecast the three-dimensional configuration of global ice sheets for specific climate change scenarios. The objective of the third (final) year of the work was to produce ice sheet data for glaciation scenarios covering the next 100,000 years. This was accomplished using both the map-plane and flowband solutions of our time-dependent, finite-element gridpoint model. The theory and equations used to develop the ice sheet models are presented. Three future scenarios were simulated by the model and results are discussed.

Hughes, T.J.; Fastook, J.L. [Univ. of Maine, Orono, ME (United States). Institute for Quaternary Studies

1994-05-01

471

Rainfall erosion model  

NASA Astrophysics Data System (ADS)

A model describing rainfall erosion over the course of a long time period is proposed. The model includes: (1) a new equation of detachment of soil particles by water flows based on the Mirtskhulava equation; (2) a new equation for the transport capacity of the flow based on a modified Bagnold equation, which is used in the AGNPS model; (3) modified SCS runoff equation; (4) probability distributions for rainfall. The proposed equations agree satisfactorily with the data of on-site observations of the Moldova and Nizhnedevitsk water-balance stations. The Monte Carlo method is used for numerical modeling of random variables. The results of modeling agree satisfactorily with empirical equations developed for conditions in Russia and the United States. The effect of climatic conditions on the dependence of longtime average annual soil loss on various factors is analyzed. Minimum information is used for assigning the initial data.

Sukhanovskii, Yu. P.

2010-09-01

472

Beyond the Standard Model  

SciTech Connect

These lectures constitute a short course in ``Beyond the Standard Model`` for students of experimental particle physics. The author discusses the general ideas which guide the construction of models of physics beyond the Standard model. The central principle, the one which most directly motivates the search for new physics, is the search for the mechanism of the spontaneous symmetry breaking observed in the theory of weak interactions. To illustrate models of weak-interaction symmetry breaking, the author gives a detailed discussion of the idea of supersymmetry and that of new strong interactions at the TeV energy scale. He discusses experiments that will probe the details of these models at future pp and e{sup +}e{sup {minus}} colliders.

Peskin, M.E.

1997-05-01

473

Stochastic patch exploitation model  

PubMed Central

A solitary animal is foraging in a patch consisting of discrete prey items. We develop a stochastic model for the accumulation of gain as a function of elapsed time in the patch. The model is based on the waiting times between subsequent encounters with the prey items. The novelty of the model is in that it renders possible–via parameterization of the waiting time distributions: the incorporation of different foraging situations and patch structures into the gain process. The flexibility of the model is demonstrated with different foraging scenarios. Dependence of gain expectation and variance of the parameters of the waiting times is studied under these conditions. The model allows us to comment upon some of the basic concepts in contemporary foraging theory.

Rita, H.; Ranta, E.

1998-01-01

474

Fuzzy object modeling  

NASA Astrophysics Data System (ADS)

To make Quantitative Radiology (QR) a reality in routine clinical practice, computerized automatic anatomy recognition (AAR) becomes essential. As part of this larger goal, we present in this paper a novel fuzzy strategy for building bodywide group-wise anatomic models. They have the potential to handle uncertainties and variability in anatomy naturally and to be integrated with the fuzzy connectedness framework for image segmentation. Our approach is to build a family of models, called the Virtual Quantitative Human, representing normal adult subjects at a chosen resolution of the population variables (gender, age). Models are represented hierarchically, the descendents representing organs contained in parent organs. Based on an index of fuzziness of the models, 32 thorax data sets, and 10 organs defined in them, we found that the hierarchical approach to modeling can effectively handle the non-linear relationships in position, scale, and orientation that exist among organs in different patients.

Udupa, Jayaram K.; Odhner, Dewey; Falcao, Alexandre X.; Ciesielski, Krzysztof C.; Miranda, Paulo A. V.; Vaideeswaran, Pavithra; Mishra, Shipra; Grevera, George J.; Saboury, Babak; Torigian, Drew A.

2011-03-01

475

Latent class model diagnosis.  

PubMed

In many areas of medical research, such as psychiatry and gerontology, latent class variables are used to classify individuals into disease categories, often with the intention of hierarchical modeling. Problems arise when it is not clear how many disease classes are appropriate, creating a need for model selection and diagnostic techniques. Previous work has shown that the Pearson chi 2 statistic and the log-likelihood ratio G2 statistic are not valid test statistics for evaluating latent class models. Other methods, such as information criteria, provide decision rules without providing explicit information about where discrepancies occur between a model and the data. Identifiability issues further complicate these problems. This paper develops procedures for assessing Markov chain Monte Carlo convergence and model diagnosis and for selecting the number of categories for the latent variable based on evidence in the data using Markov chain Monte Carlo techniques. Simulations and a psychiatric example are presented to demonstrate the effective use of these methods. PMID:11129461

Garrett, E S; Zeger, S L

2000-12-01

476

Subgrid-Scale modeling  

NASA Astrophysics Data System (ADS)

The purpose of this lecture is to give an overview of the subgrid scale models used for Large Eddy Simulations (LES). The first models where essentially eddy-viscosity models, where the turbulent viscosity coefficient was found by simple dimensional considerations (the mixing length theory) or taking into account Kolmogorov theory (the Smagorinsky model). Since then there have been many improvements, and now some of the physical ingredients of turbulence, such as the local backscatter and the anisotropy of small scale structures, can be successfully taken into account. Far from being a black box tool to obtain answers to turbulent flow problems, the Large Eddy Simulation technique is still a work in progress with many odds and ends. We give in this lecture an overview of the historical development of turbulence models and we point out the lights and shadows of them with attention to the open problems that still remain to be solved.

Valdettaro, L.

477

XAFS Model Compound Library  

DOE Data Explorer

The XAFS Model Compound Library contains XAFS data on model compounds. The term "model" compounds refers to compounds of homogeneous and well-known crystallographic or molecular structure. Each data file in this library has an associated atoms.inp file that can be converted to a feff.inp file using the program ATOMS. (See the related Searchable Atoms.inp Archive at http://cars9.uchicago.edu/~newville/adb/) This Library exists because XAFS data on model compounds is useful for several reasons, including comparing to unknown data for "fingerprinting" and testing calculations and analysis methods. The collection here is currently limited, but is growing. The focus to date has been on inorganic compounds and minerals of interest to the geochemical community. [Copied, with editing, from http://cars9.uchicago.edu/~newville/ModelLib/

Newville, Matthew

478

Models of consistency.  

PubMed

This article presents a theory of how individuals detect whether descriptions of an entity are consistent or inconsistent. The theory postulates that individuals try to construct a mental model of the entity in which all the propositions are true. If they succeed, they infer that the description is consistent; otherwise, they infer that it is inconsistent. We report three experiments that corroborated the theory. Experiment 1 confirmed that evaluating consistency is easier when an initial model suffices than when reasoners have to find an alternative model. Experiment 2 established the occurrence of illusion, inferences about the properties of entities. Experiment 3 showed that the illusions correspond to mental models of the assertions, even when these models are wrong because they fail to represent what is false. PMID:12661674

Legrenzi, Paolo; Girotto, Vittorio; Johnson-Laird, P N

2003-03-01

479

Radioactive Decay Model  

NSDL National Science Digital Library

The EJS Radioactive Decay Model simulates the decay of a radioactive sample using discrete random events. It displays the number of radioactive nuclei as a function of time. You can change the initial number of nuclei and the decay constant as well as changing the plot to a semi-log plot. The Radioactive Decay model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ms_explicit_RadioactiveDecay.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-01-23

480

Criticality Model Report  

SciTech Connect

The purpose of the ''Criticality Model Report'' is to validate the MCNP (CRWMS M&O 1998h) code's ability to accurately predict the effective neutron multiplication factor (k{sub eff}) for a range of conditions spanned by various critical configurations representative of the potential configurations commercial reactor assemblies stored in a waste package may take. Results of this work are an indication of the accuracy of MCNP for calculating eigenvalues, which will be used as input for criticality analyses for spent nuclear fuel (SNF) storage at the proposed Monitored Geologic Repository. The scope of this report is to document the development and validation of the criticality model. The scope of the criticality model is only applicable to commercial pressurized water reactor fuel. Valid ranges are established as part of the validation of the criticality model. This model activity follows the description in BSC (2002a).

J.M. Scaglione

2003-03-12

481

Ejs Spherical Pendulum Model  

NSDL National Science Digital Library

The Ejs Spherical Pendulum model displays the dynamics of a spherical pendulum in three dimensions. The pendulum is initially displaced from equilibrium and the pendulum bob has zero initial velocity. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Spherical Pendulum model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_osc_Pendulum3D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-05

482

Modeling ocean circulation  

SciTech Connect

Ocean numerical models have become quite realistic over the past several years as a result of improved methods, faster computers, and global data sets. Models now treat basin-scale to global domains while retaining the fine spatial scales that are important for modeling the transport of heat, salt, and other properties over vast distances. Simulations are reproducing observed satellite results on the energetics of strong currents and are properly showing diverse aspects of thermodynamic and dynamic ocean responses ranging from deep-water production of El Nino. Now models can represent not only currents but also the consequences for climate, biology, and geo-chemistry over time spans for months to decades. However, much remains to be understood from models about ocean circulation on longer time scales, including the evolution of the dominant water masses, the predictability of climate, and the ocean`s influence on global change. 34 refs., 6 figs.

Semtner, A.J. [Naval Postgraduate School, Monterey, CA (United States)

1995-09-08

483

Modeling Ionospheric Outflows In Global Models (Invited)  

NASA Astrophysics Data System (ADS)

The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of this ionospheric plasma has a notable impact on magnetospheric composition and processes. We present our methodology for including an ionospheric mass source into global models, and for tracking the consequences for the space environment system. An overview of our recent efforts is provided. In particular, we illustrate the effect that plasma of ionospheric origin can have on the magnetosphere by simulating extreme geospace events when the fraction of O+ is largest, and contrast those results with simulations of more moderate events. We also compare different techniques of modeling/tracking ionospheric outflow, and explore the implications for the storm-time ring current and magnetospheric magnetic field configuration.

Glocer, A.; Toth, G.; Fok, M. H.; Gombosi, T. I.; Welling, D. T.

2010-12-01

484

Models, Traffic Models, Simulation, and Traffic Simulation  

Microsoft Academic Search

\\u000a This introductory chapter to a book on traffic simulation fundamentals is aimed at setting up a comprehensive framework for\\u000a simulation as a well-established and grounded OR technique and its specificities when applied to traffic systems; the main\\u000a approaches to traffic simulation and the principles of traffic simulation model building; the fundamentals of traffic flow\\u000a theory and its application to traffic

Jaume Barceló

485

Saturn Dynamo Model (Invited)  

NASA Astrophysics Data System (ADS)

There has been considerable interest during the past few years about the banded zonal winds and global magnetic field on Saturn (and Jupiter). Questions regarding the depth to which the intense winds extend below the surface and the role they play in maintaining the dynamo continue to be debated. The types of computer models employed to address these questions fall into two main classes: general circulation models (GCMs) based on hydrostatic shallow-water assumptions from the atmospheric and ocean modeling communities and global non-hydrostatic deep convection models from the geodynamo and solar dynamo communities. The latter class can be further divided into Boussinesq models, which do not account for density stratification, and anelastic models, which do. Recent efforts to convert GCMs to deep circulation anelastic models have succeeded in producing fluid flows similar to those obtained from the original deep convection anelastic models. We describe results from one of the original anelastic convective dynamo simulations and compare them to a recent anelastic dynamo benchmark for giant gas planets. This benchmark is based on a polytropic reference state that spans five density scale heights with a radius and rotation rate similar to those of our solar system gas giants. The resulting magnetic Reynolds number is about 3000. Better spatial resolution will be required to produce more realistic predictions that capture the effects of both the density and electrical conductivity stratifications and include enough of the turbulent kinetic energy spectrum. Important additional physics may also be needed in the models. However, the basic models used in all simulation studies of the global dynamics of giant planets will hopefully first be validated by doing these simpler benchmarks.

Glatzmaier, G. A.

2010-12-01

486

Quantum Magnetism Analysis Model  

NSDL National Science Digital Library

The Quantum Magnetism Analysis Model was created to help students as well as researchers who are studying magnetism. It provides a very simple interface for defining (theoretical) quantum spin models; sliders are automatically created to vary the parameters in the models; and several plots are automatically created to visualize the results. Within the program, several measured (experimental) data sets are included for a variety of real molecules. These provide the opportunity to experience the modeling process by varying the parameters in the model and exploring how the simulated results compare to the measured data. The interactions between neighboring quantum magnetic moments ("spins") are modeled using the Heisenberg model; calculations are carried out by numerically diagonalizing the matrix representation of the Heisenberg Hamiltonian; and plots display the energy spectrum, magnetization, and magnetic susceptibility as a function of temperature and magnetic field. This simulation is a "Fully Integrated Tool for Magnetic Analysis in Research & Teaching," so we also refer to it with the acronym "FIT-MART". FIT-MART was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking ejs_fitmart.jar file will run the package if Java is installed. In future versions of this simulation, curricular materials will be included to help students to learn about magnetism, and automated fitting routines will be included to help researchers quickly and easily model experimental data. FIT-MART was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking ejs_fitmart.jar file will run the package if Java is installed.

Engelhardt, Larry; Garland, Chad; Rainey, Cameron; Freeman, Austin

2012-07-27

487

PET Pharmacokinetic Modelling  

NASA Astrophysics Data System (ADS)

Positron Emission Tomography is a well-established technique that allows imaging and quantification of tissue properties in-vivo. The goal of pharmacokinetic modelling is to estimate physiological parameters, e.g. perfusion or receptor density from the measured time course of a radiotracer. After a brief overview of clinical application of PET, we summarize the fundamentals of modelling: distribution volume, Fick's principle of local balancing, extraction and perfusion, and how to calculate equilibrium data from measurements after bolus injection. Three fundamental models are considered: (i) the 1-tissue compartment model, e.g. for regional cerebral blood flow (rCBF) with the short-lived tracer [15O]water, (ii) the 2-tissue compartment model accounting for trapping (one exponential + constant), e.g. for glucose metabolism with [18F]FDG, (iii) the reversible 2-tissue compartment model (two exponentials), e.g. for receptor binding. Arterial blood sampling is required for classical PET modelling, but can often be avoided by comparing regions with specific binding with so called reference regions with negligible specific uptake, e.g. in receptor imaging. To estimate the model parameters, non-linear least square fits are the standard. Various linearizations have been proposed for rapid parameter estimation, e.g. on a pixel-by-pixel basis, for the prize of a bias. Such linear approaches exist for all three models; e.g. the PATLAK-plot for trapping substances like FDG, and the LOGAN-plot to obtain distribution volumes for reversibly binding tracers. The description of receptor modelling is dedicated to the approaches of the subsequent lecture (chapter) of Millet, who works in the tradition of Delforge with multiple-injection investigations.

Müller-Schauenburg, Wolfgang; Reimold, Matthias

488

Tsunami Modeling: Development of Benchmarked Models  

NASA Astrophysics Data System (ADS)

We discuss the progress towards the development of benchmarked models for forecasting tsunami inundation. Tsunami hydrodynamics has progressed slower than research in other natural hazards, because for several decades only the largest tsunamis were being reported. With the exception of the 1960 and 1964 events, there had been only qualitative information on inundation. While the basic equations for analysis have been known for decades, the existing synthesis leading to real time forecasts as currently available had to await the development of sophisticated modeling tools, the large-scale laboratory experiments in the 1980s-1990s and the tsunameter recordings of 2003 and since. The field survey results in the 1990s (Synolakis and Okal, 2005) served as crude proxies to free-field tsunami recordings and allowed for the validation and verification of numerical procedures. State-of-the-art inundation and forecasting codes have evolved through a painstaking process of careful validation and verification which can be traced back to the 1990 NSF Catalina workshop on Long-Wave Runup Models (Liu et al., 1991). Operational tsunami forecasting was only made possible through the availability of deep ocean measurements. We will describe this journey from development of the basic field equations to forecasts, through the scientific milestones that served as benchmarks and reality checks. In summary, as research in live networks -where problems and solution ideas arise spontaneously- tsunami hydrodynamic modeling was driven by milestone scientific meetings, and post tsunami surveys that kept identifying novel problem geometries and previously unrecognized phenomena. We discuss necessary validation and verification steps for numerical codes to be used for inundation mapping, design and operations (Synolakis et al., 2007). Liu, P. L.-F., C. E. Synolakis and H. H. Yeh, 1991. Report on the International Workshop on Long-Wave Run- up. J. Fluid Mech., 229, 675-688. Synolakis, C. E. and E. A. Okal, 2005. 1992-2002: perspective on a decade of post tsunami surveys. Adv. Nat. Technol. Hazards, 23, 1-30. Synolakis, C. E., E. N. Bernard, V. V. Titov, U. Kanoglu and F. Gonzalez, 2007. Standards, criteria, and procedures for NOAA evaluation of tsunami numerical models. NOAA OAR Special Report, Contribution No 3053, NOAA/OAR/PMEL, Seattle, WA, 55 pp.

Kanoglu, U.; Synolakis, C. E.

2008-12-01

489

Simulation modeling using promodel technology: simulation modeling using promodel technology  

Microsoft Academic Search

PROMODEL's simulation modeling products are powerful yet easy-to-use simulation tools for modeling all types of systems and processes. ProModel® is designed to model manufacturing systems ranging from small job shops and machining cells to large mass production, flexible manufacturing systems, and supply chain systems. Other simulation products available from PROMODEL Corporation include MedModel®, ServiceModel®, and our latest release, ProModel PI

Charles R. Harrell; Rochelle N. Price

2003-01-01

490

Biophysical models in hadrontherapy  

NASA Astrophysics Data System (ADS)

One major rationale for the application of ion beams in tumor therapy is their increased relative biological effectiveness RBE in the Bragg peak region For dose prescription the increased effectiveness has to be taken into account in treatment planning Hence the complex dependencies of RBE on the dose level biological endpoint position in the field etc require biophysical models which have to fulfill two important criteria simplicity and quantitative precision Simplicity means that the number of free parameters should be kept at a minimum Due to the lack of precise quantitative data at least at present this requirement is incompatible with approaches aiming at the molecular modeling of the whole chain of production processing and repair of biological damages Quantitative precision is required since steep gradients in the dose response curves are observed for most tumor and normal tissues thus even small uncertainties in the estimation of the biologically effective dose can transform into large uncertainties in the clinical outcome The paper will give a general introduction into the field followed by a brief description of a specific model the so called Local Effect Model LEM This model has been successfully applied within treatment planning in the GSI pilot project for carbon ion tumor therapy over almost 10 years now The model is based on the knowledge of charged particle track structure in combination with the response of the biological objects to conventional photon radiation The model will be critically discussed with respect to other

Scholz, M.; Elsaesser, T.

491

Animal Models of Atherosclerosis  

PubMed Central

Atherosclerosis is a chronic inflammatory disorder that is the underlying cause of most cardiovascular disease. Both cells of the vessel wall and cells of the immune system participate in atherogenesis. This process is heavily influenced by plasma lipoproteins, genetics and the hemodynamics of the blood flow in the artery. A variety of small and large animal models have been used to study the atherogenic process. No model is ideal as each has its own advantages and limitations with respect to manipulation of the atherogenic process and modeling human atherosclerosis or lipoprotein profile. Useful large animal models include pigs, rabbits and non-human primates. Due in large part to the relative ease of genetic manipulation and the relatively short time frame for the development of atherosclerosis, murine models are currently the most extensively used. While not all aspects of murine atherosclerosis are identical to humans, studies using murine models have suggested potential biological processes and interactions that underlie this process. As it becomes clear that different factors may influence different stages of lesion development, the use of mouse models with the ability to turn on or delete proteins or cells in tissue specific and temporal manner will be very valuable.

Getz, Godfrey S.; Reardon, Catherine A.

2012-01-01

492

Modeling Transient Eruptive Processes  

NASA Astrophysics Data System (ADS)

Computer models of volcanic eruptions are essential for understanding the physical processes occurring within a volcanic conduit. We are building upon previous modeling efforts in order to simulate two-phase homogeneous flow prior to fragmentation. Our code is designed to track changing pressure, velocity, density, and volatile concentrations within the conduit. Its primary emphasis is the efficient numerical modeling of transient eruptive events. As such, it is possible to model eruption triggers associated with sudden decompression, more gradual diffusive bubble growth, and injection of volatile-rich magma. We alter initial conditions, including volatile distribution, conduit geometry, and magma recharge to quantify how these parameters affect eruption evolution. Our model complements existing numerical approaches for eruption dynamics and incorporates results from experimentalists and observational volcanologists. This enables us to assess the relative impact of various solubility laws, diffusion rates, as well as nucleation and fragmentation criteria. In the process, we address other important questions within the modeling community, such as: When and where does nucleation occur? What kind of boundary conditions should be imposed at the fragmentation front / gas-particle-jet boundary? How do turbulent flow, wall friction, and erosion affect flow? Modeling results are to be compared with observations from contemporaneous eruptions at Colima, Mexico, Santiaguito, Guatemala, and Tungurahua, Ecuador.

Johnson, J. B.; Proussevitch, A.; Sahagian, D.

2004-05-01

493

Mouse Models of Arteriosclerosis  

PubMed Central

Animal models are designed to be preliminary tools for better understanding of the pathogenesis, improvement in diagnosis, prevention, and therapy of arteriosclerosis in humans. Attracted by the well-defined genetic systems, a number of investigators have begun to use the mouse as an experimental system for arteriosclerosis research. Hundreds of inbred lines have been established, and the genetic map is relatively well defined, and both congenic strains and recombinant strains are available to facilitate genetic experimentation. Because arteriosclerosis is a complicated disease, which includes spontaneous (native) atherosclerosis, transplant arteriosclerosis, vein graft atherosclerosis, and angioplasty-induced restenosis, several mouse models for studying all types of arteriosclerosis have recently been established. Using these mouse models, much knowledge concerning the pathogenesis of the disease and therapeutic intervention has been gained, eg, origins of endothelial and smooth muscle cells in lesions of transplant and vein graft atherosclerosis. This review will not attempt to cover all aspects of mouse models, rather focus on models of arterial injuries, vein grafts, and transplant arteriosclerosis, by which the major progress in understanding the mechanisms of the disease has been made. This article will also point out (dis)advantages of a variety of models, and how the models can be appropriately chosen for different purposes of study.

Xu, Qingbo

2004-01-01

494

Phases of Moon Model  

NSDL National Science Digital Library

The EJS Phases of Moon model displays the appearance of Moon and how it changes depending on the position of Moon relative to Earth and Sun. The main window shows Earth (at the center) and Moon, as well as a circle tracing out Moon's orbit. Sun is far to the right in this picture and therefore the right side of Earth and Moon are bright while the left sides are dark. By using the Options Menu the Moon View window shows the appearance of Moon as seen from Earth when Moon is in the position shown in the main window. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. The EJS Phases of Moon model includes three supplemental documents (see below) that include a middle school lesson plan, a college level worksheet, and the student version of the program. EJS Phases of Moon model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_MoonPhases.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for astronomy are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Timberlake, Todd

2009-08-01

495

New models of hemostasis.  

PubMed

Hemostasis is an essential protective mechanism that depends on a delicate balance of procoagulant and anticoagulant processes. The waterfall/cascade models of coagulation are useful for understanding several essential steps of coagulation in vitro. These have resulted in the creation of the plasma-based tests used commonly and the ability to identify deficiencies in the extrinsic, intrinsic, and common pathways of coagulation. The model was also essential in elucidating the role of several of the inhibitors of coagulation and is currently used to demonstrate coagulation as it occurs in plasma in a static environment that is devoid of endothelial interactions. The intrinsic pathway originally described by these models does not appear to be essential for in vivo hemostasis but may play a role in pathologic thrombosis. The waterfall/cascade models' lack of cellular elements sets the stage for the cell-based model of coagulation. The cell-based model of blood coagulation, which includes the varied, complicated network of factors necessary for appropriate in vivo coagulation to occur, was the next step in the evolution of our understanding of coagulation. Recently, researchers have focused on real-time, in vivo models of hemostasis and this research reveals unexpected phenomena. PMID:23031454

McMichael, Maureen

2012-08-29

496

Invertebrate models of alcoholism.  

PubMed

For invertebrates to become useful models for understanding the genetic and physiological mechanisms of alcoholism related behaviors and the predisposition towards alcoholism, several general requirements must be fulfilled. The animal should encounter ethanol in its natural habitat, so that the central nervous system of the organism will have evolved mechanisms for responding to ethanol exposure. How the brain adapts to ethanol exposure depends on its access to ethanol, which can be regulated metabolically and/or by physical barriers. Therefore, a model organism should have metabolic enzymes for ethanol degradation similar to those found in humans. The neurons and supporting glial cells of the model organism that regulate behaviors affected by ethanol should share the molecular and physiological pathways found in humans, so that results can be compared. Finally, the use of invertebrate models should offer advantages over traditional model systems and should offer new insights into alcoholism-related behaviors. In this review we will summarize behavioral similarities and identified genes and mechanisms underlying ethanol-induced behaviors in invertebrates. This review mainly focuses on the use of the nematode Caenorhabditis elegans, the honey bee Apis mellifera and the fruit fly Drosophila melanogaster as model systems. We will discuss insights gained from those studies in conjunction with their vertebrate model counterparts and the implications for future research into alcoholism and alcohol-induced behaviors. PMID:21472534

Scholz, Henrike; Mustard, Julie A

2013-01-01

497

New precompound decay model  

SciTech Connect

A new precompound Monte Carlo simulation model is presented. It permits unlimited multiple precompound emission for each interaction, may be used to give exclusive spectra and yields, and does not rely upon those exciton state densities shown to be inconsistent with the assumed two body transitions in the hybrid and exciton model formulations. Results of the new model are compared with {sup 90}Zr ({ital p},{ital xn}) single differential spectra for incident energies from 25 to 160 MeV, and for {sup 59}Co ({ital p},{ital x}) and {sup 51}V ({ital p},{ital x}) excitation functions for incident proton energies up to 200 MeV. The new model gives significant improvement over the hybrid model for calculation of excitation functions. Multiple precompound decay predictions are compared for the two models. It is shown that the restriction to two precompound nucleons per decay in the hybrid model becomes a poor approximation for incident proton energies above {approx_equal}80 MeV. {copyright} {ital 1996 The American Physical Society.}

Blann, M. [Lawrence Livermore National Laboratory, P.O. Box 808, L-59, Livermore, California 94551 (United States)

1996-09-01

498

Subthreshold SPICE Model Optimization  

NASA Astrophysics Data System (ADS)

The first step in integrated circuit design is the simulation of said design in software to verify proper functionally and design requirements. Properties of the process are provided by fabrication foundries in the form of SPICE models. These SPICE models contain the electrical data and physical properties of the basic circuit elements. A limitation of these models is that the data collected by the foundry only accurately model the saturation region. This is fine for most users, but when operating devices in the subthreshold region they are inadequate for accurate simulation results. This is why optimizing the current SPICE models to characterize the subthreshold region is so important. In order to accurately simulate this region of operation, MOSFETs of varying widths and lengths are fabricated and the electrical test data is collected. From the data collected the parameters of the model files are optimized through parameter extraction rather than curve fitting. With the completed optimized models the circuit designer is able to simulate circuit designs for the sub threshold region accurately.

Lum, Gregory; Au, Henry; Neff, Joseph; Bozeman, Eric; Kamin, Nick; Shimabukuro, Randy

2011-04-01

499

GIA Ice Models  

NASA Astrophysics Data System (ADS)

Defining the ice load in a way that avoids circularity is perhaps the most difficult aspect of GIA modeling. At any instant of past time the global land-supported ice load must honor the meltwater curve and the known edges of the ice, but within these constraints the ice mass can be swapped to a considerable extent between the various glacial systems and parts of those systems. In our models, ice thickness is controlled by the effective basal shear stress (EBSS). This parameter incorporates the sub-ice lithology (e.g., whether the ice rests on sediment of crystalline rock), the relative local snow accumulation rate, and the local basal shear strength (which presumably depends most strongly on sub-ice temperature). The effective basal shear stress can be fairly easily modified to construct an ice model. The ice model is evaluated by the geological reasonability of its changes in EBSS in space and time, and by how well it matches measured GIA data. The risk that an incorrect earth model can be forced to fit the GIA data by manipulating the ice model (the circularity mentioned above) can be minimized by evaluating the longest wavelength deformations (peripheral bulge behavior) before proceeding to the shorter wavelength deformations (local emergence variations). The poster will describe how we have proceeded in this fashion to develop a framework for interpreting GIA data in Norway. The poster will be augmented by computer software that compares emergence data to models at specific sites in Norway.

Kachuck, Samuel; Cathles, Larry; Amantov, Aleksey

2013-04-01

500

Comprehensive EUV lithography model  

NASA Astrophysics Data System (ADS)

As EUV lithography nears pilot-line stage, photolithography modeling becomes increasingly important in order for engineers to build viable, production-worthy processes. In this paper, we present a comprehensive, calibrated lithography model that includes optical effects such as mask shadowing and flare, combined with a stochastic resist model that can predict effects such as line-edge roughness. The model was calibrated to CD versus pitch data with varying levels of flare, as well as dense lines with varying degrees of mask shadowing. We then use this model to investigate several issues critical to EUV. First, we investigate EUV photoresist technology: the impact of photoelectron-PAG exposure kinetics on photospeed, and then we examine the trade-off between LWR and photospeed by changing quencher loading in the photoresist model. Second, we compare the predicted process windows for dense lines as flare and lens aberrations are reduced from the levels in the current alpha tools to the levels expected in the beta tools. The observed interactions between optical improvements and resist LWR indicate that a comprehensive model is required to provide a realistic evaluation of a lithography process.

Smith, Mark D.; Graves, Trey; Biafore, John; Robertson, Stewart; Kim, Cheolkyun; Moon, James; Kim, Jaeheon; Bok, Cheolkyu; Yim, Donggyu

2011-03-01