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1

Compound nucleus decay: Comparison between saddle point and scission point barriers  

NASA Astrophysics Data System (ADS)

One of the principal characteristics of nuclear multifragmentation is the emission of complex fragments of intermediate mass. An extension of the statistical multifragmentation model has been developed, in which the process can be interpreted as the near simultaneous limit of a series of sequential binary decays. In this extension, intermediate mass fragment emissions are described by expressions almost identical to those of light particle emission. At lower temperatures, similar expressions have been shown to furnish a good description of very light intermediate mass fragment emission but not of the emission of heavier fragments, which seems to be determined by the transition density at the saddle-point rather than at the scission point. Here, we wish to compare these different formulations of intermediate fragmment emission and analyze the extent to which they remain distinguishable at high excitation energy.

Santos, T. J.; Carlson, B. V.

2014-11-01

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

The Generalized Model for the Description of Prompt Neutrons in the Low-energy Fission  

NASA Astrophysics Data System (ADS)

The generalized model for the description of neutron emission from the spontaneous and neutron-induced fission in the energy interval up to 20 MeV is developed. For accurate calculations of nucleon composition and excitation energy of the fissioning nucleus at the scission point, the time-dependent statistical model including the pre-equilibrium neutron emission and nuclear friction effects is used. For each member of the compound nucleus ensemble at the scission point, the primary fission-fragment characteristics such as kinetic and excitation energies and yields are calculated using the scission-point fission model with nuclear shell and pairing effects, and based on the multimodal approach. The charge distribution for the primary fragment isobaric chains is considered as a result of the frozen quantal fluctuations of the isovector nuclear matter density at the finite scission neck radius. The post-scission neutron spectra are calculated as the result of the equilibrium emission from the fully accelerated fission fragments with calculated kinetic energies. The pre- scission neutron multiplicity and spectra for multi-chance fission are also calculated. The neutron and ?-ray emission during the saddle-to-scission time is also included in the consideration. This mechanism may partially explain the long standing problem of the so-called isotropic component of prompt fission neutrons.

Rubchenya, V. A.

4

Angular distributions of evaporated particles, fission and intermediate-mass fragments : on the search for consistent models  

NASA Astrophysics Data System (ADS)

During the last two years there has been a true cacophony concerning the meaning of experimental angular distributions for fission and fission-like fragments. The heavily used, saddle-point, transition-state model has been shown to be of limited value for high-spin systems, and a wide variety of proposals has appeared often with mutual inconsistencies and conflicting views. Even though equilibrium statistical models for fragment emission and particle evaporation must have a very close kinship, this relationship, often left as murky, has now come onto center stage for understanding reactions at ? 100 MeV. Basic questions concern the nature of the decision-point configurations, their degrees of freedom, the role of deformation and the relevant moments of inertia. This paper points out serious inconsistencies in several recent scission-point models and discusses conditions for applicability of saddle-point and scission-point approaches. Au cours des deux dernières années, l'interprétation des distributions angulaires de fragments a donné lieu à une véritable cacophonie. Les limitations du modèle courant considérant le point selle comme un état de transition sont apparues clairement pour les systèmes à haut spin, et une grande variété de remèdes prescntant souvent des incohérences mutuelles et des points de vue conflictuels ont été proposés. Même si les modèles décrivant l'émission de fragments ou de particules légères doivent nécessairement posséder une parente naturelle, cette relation, souvent laissée dans l'ombre, se trouve maintenant au centre de la compréhension des mécanismes de réactions lorsque les énergies d'excitation dépassent 100 MeV. Les questions primordiales concernent la nature des configurations critiques du point de vue de l'évolution ultérieure du système, de leurs degrés de liberté, du rôle de la déformation, et des moments d'inertie concernés. Cet article met en évidence de sérieuses incohérences dans plusieurs modèles récents centrés sur le point de scission et discute les conditions d'applicabilité des approches du point selle et du point de scission.

Alexander, J. M.

5

An Electrostatic Charge Partitioning Model for the Dissociation of Protein Complexes in the Gas Phase  

NASA Astrophysics Data System (ADS)

Electrosprayed multi-protein complexes can be dissociated by collisional activation in the gas phase. Typically, these processes follow a mechanism whereby a single subunit gets ejected with a disproportionately high amount of charge relative to its mass. This asymmetric behavior suggests that the departing subunit undergoes some degree of unfolding prior to being separated from the residual complex. These structural changes occur concomitantly with charge (proton) transfer towards the subunit that is being unraveled. Charge accumulation takes place up to the point where the subunit loses physical contact with the residual complex. This work develops a simple electrostatic model for studying the relationship between conformational changes and charge enrichment during collisional activation. Folded subunits are described as spheres that carry continuum surface charge. The unfolded chain is envisioned as random coil bead string. Simulations are guided by the principle that the system will adopt the charge configuration with the lowest potential energy for any backbone conformation. A finite-difference gradient algorithm is used to determine the charge on each subunit throughout the dissociation process. Both dimeric and tetrameric protein complexes are investigated. The model reproduces the occurrence of asymmetric charge partitioning for dissociation events that are preceded by subunit unfolding. Quantitative comparisons of experimental MS/MS data with model predictions yield estimates of the structural changes that occur during collisional activation. Our findings suggest that subunit separation can occur over a wide range of scission point structures that correspond to different degrees of unfolding.

Sciuto, Stephen V.; Liu, Jiangjiang; Konermann, Lars

2011-10-01

6

Antiproton-induced nuclear fission  

Microsoft Academic Search

A dynamical model, which takes into account all stages of fission induced by stopped antiprotons (atomic cascade, intranuclear cascade, evaporation cascade, fission of a compound nucleus, and evaporation from fission fragments), has been formulated. In particular, the dynamics of the descent of fissioning nuclei from the saddle point to the scission point has been described by the diffusion model. The

A. S. Iljinov; M. V. Mebel; H. Daniel; T. von Egidy; F. J. Hartmann; P. Hofmann; Y. S. Kim

1994-01-01

7

Superasymmetric Fission  

NASA Astrophysics Data System (ADS)

The existence of superasymmetric fission mode connected with Z = 28 and N = 50 nuclear shells is analysed in the framework of the scission point model. Calculations of PES near the scission point had shown that the 78Ni fission mode would be manifested in fission of neutron-rich compound nuclei. In the case of fission of superheavy nucleus the superasymmetric fission mode is enhanced by influence of the Z = 82 and N = 126 nuclear shells in heavy fragment. Enhancement of highly asymmetric mass and charge division in the proton and neutron fission of 238U at intermediate energy in comparison with thermal neutron induced fission was described by the model developed for calculating the product yields with inclusion of superasymmetric fission mode. This model was used for the prediction of the formation cross sections of neutron-rich nuclides in fission.

Rubchenya, V. A.

2001-10-01

8

FISSION OF {sup 238}U INDUCED BY INELASTIC SCATTERING OF 120 MeV {alpha}-PARTICLES  

SciTech Connect

The fission decay of {sup 238}U has been measured as function of excitation energy in inelastic scattering of 120 MeV {alpha}-particles. Total kinetic energies and masses of fission fragments were measured by the double energy method. It is observed that the total kinetic energy E{sub K} decreases and that the valley in the mass distribution is reduced when the excitation energy of the system is increased. No indication of anomalous total kinetic energy release in the region of the giant quadrupole resonance has been found. A qualitative interpretation of the data is given on the basis of a static scission point model.

Back, B.B.; Shotter, A.C.; Symons, T.J.M.; Bice, A.; Gelbke, C.K.; Awes, T.C.; Scott, D.K.

1980-09-01

9

Statistical estimation of physical quantities in thermal- and fast-neutron-induced fission. [Fission product mass yields, fragment kinetic energies, numbers of prompt neutrons  

Microsoft Academic Search

Making use of a model based on the statistical theory in which the scission-point distance is treated as an adjustable parameter, calculations were performed to obtain the mass yields of fission products, the kinetic energies of fission fragments and the numbers of prompt neutrons from neutron-induced fission of ²³²Th, ²³¹Pa, ²³³U, ²³⁵U, ²³⁸U, ²³⁷Np, ²³⁹Pu and ²⁴¹Pu for incident-neutron energies

T. Yamamoto; K. Sugiyama

1975-01-01

10

Effects of large angular momenta on the fission properties of Pt isotopes  

NASA Astrophysics Data System (ADS)

The effects of large angular momenta on the fission properties of Pt isotopes are studied. Fissioning Pt systems were produced in fusion reactions of 16O + 170Yb and 32S + 144,150,152,154Sm in the energy range of 0.8-2.0 times the fusion barrier. The sub-barrier fusion-fission cross sections show a strong dependence on the target deformation. A pronounced increase in a simple model calculation in the total kinetic energy release with bombarding energy is accounted for by the increasing contribution of centrifugal energy. The widths of the mass and kinetic energy distributions increase rapidly with the angular momentum of the fissioning system. This effect is not accounted for by simple scission point model calculations. [NUCLEAR REACTIONS, FISSION 16O+170Yb, E=90-148 MeV, 32S + 144,150,152,154Sm, E=180-230 MeV, measured fission cross sections, ?f(E), total kinetic energy and mass distributions as a function of bombarding energy. Analysis in terms of the scission point model of fission.

Glagola, B. G.; Back, B. B.; Betts, R. R.

1984-02-01

11

Modeling modeling.  

PubMed Central

Models are tools; they need to fit both the hand and the task. Presence or absence of a feature such as a pacemaker or a cascade is not in itself good. Or bad. Criteria for model evaluation involve benefit-cost ratios, with the numerator a function of the range of phenomena explained, goodness of fit, consistency with other nearby models, and intangibles such as beauty. The denominator is a function of complexity, the number of phenomena that must be ignored, and the effort necessary to incorporate the model into one's parlance. Neither part of the ratio can yet be evaluated for MTS, whose authors provide some cogent challenges to SET. PMID:10220934

Killeen, P R

1999-01-01

12

Study of Fission Barrier Heights of Uranium Isotopes by the Macroscopic-Microscopic Method  

NASA Astrophysics Data System (ADS)

Potential energy surfaces of uranium nuclei in the range of mass numbers 229 through 244 are investigated in the framework of the macroscopic-microscopic model and the heights of static fission barriers are obtained in terms of a double-humped structure. The macroscopic part of the nuclear energy is calculated according to Lublin—Strasbourg-drop (LSD) model. Shell and pairing corrections as the microscopic part are calculated with a folded-Yukawa single-particle potential. The calculation is carried out in a five-dimensional parameter space of the generalized Lawrence shapes. In order to extract saddle points on the potential energy surface, a new algorithm which can effectively find an optimal fission path leading from the ground state to the scission point is developed. The comparison of our results with available experimental data and others' theoretical results confirms the reliability of our calculations.

Zhong, Chun-Lai; Fan, Tie-Shuan

2014-09-01

13

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(n th,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

14

Cold deformed fission in232U( n, f) and239Pu( n, f)  

NASA Astrophysics Data System (ADS)

Masses, charges and kinetic energies of light fission fragments from the reactions232U( n, f) and239Pu( n, f) induced by thermal neutrons have been measured on the Cosi fan tutte spectrometer of the Institut Laue-Langevin in Grenoble. Both at very high and very low kinetic energies marked fine structures in the mass yields and odd-even staggerings in the charge yields are observed. In the framework of a scission point model the results are shown to point to compact and deformed scission configurations, respectively, where at scission the fragments carry no intrinsic excitation energy. The two limiting processes may, therefore, be called cold compact fission (usually known as cold fission) and cold deformed fission. The latter process as a general phenomenon of low energy fission has come into focus only recently.

Kaufmann, J.; Mollenkopf, W.; Gönnenwein, F.; Geltenbort, P.; Oed, A.

1992-09-01

15

Comparison of the energy and mass characteristics of the 239Pu(nth,f) and the 240Pu(sf) fragments  

NASA Astrophysics Data System (ADS)

The energy and mass distributions and their correlations have been studied for the spontaneous fission of 240Pu and the thermal neutron induced fission of 239Pu. A comparison of the 240Pu(sf) and the 239Pu(nth,f) results shows a narrower mass distribution, a much higher peak yield, a much lower symmetric fission yield, and a more pronounced fine structure for the spontaneous fission than for the neutron induced fission. The average total kinetic energy is 1.3 MeV higher for 240Pu(sf) than for 239Pu(nth,f), and also the energy-mass correlations behave differently in both cases. All these results are discussed and interpreted in the framework of the scission point model of Wilkins et al. Finally, the damping of the 240Pu fission mode below the barrier is demonstrated.

Wagemans, C.; Allaert, E.; Deruytter, A.; Barthélémy, R.; Schillebeeckx, P.

1984-07-01

16

Energy and mass distributions for 241Pu(n th, f), 242Pu(s.f.) and 244Pu(s.f.) fragments  

NASA Astrophysics Data System (ADS)

The energy and mass distributions and their correlations have been studied for the spontaneous fission of 242Pu and 244Pu and for the thermal-neutron induced fission of 241Pu. A comparison of the 242Pu(s.f.) and the 241Pu(n th, f) results shows a narrower mass distribution, a much higher peak yield and a more pronounced fine structure for the spontaneous fission than for the neutron induced fission. The average total kinetic energy is higher for 242Pu(s.f.) than for 241Pu(n th, f), and also the energy-mass correlations behave differently in both cases. The 244Pu(s.f.) data are very similar to these for 242Pu(s.f.). All these results are discussed and interpreted in the frame of the scission point model of Wilkins et al.

Allaert, E.; Wagemans, C.; Wegener-Penning, G.; Deruytter, A. J.; Barthélémy, R.

1982-05-01

17

Fragment mass and kinetic energy distributions for 242Pu(sf), 241Pu(nth,f), and 242Pu(?,f)  

NASA Astrophysics Data System (ADS)

Energy correlation measurements were performed for the spontaneous fission of 242Pu, the thermal-neutron-induced fission of 241Pu, and the photofission of 242Pu with 12-, 15-, 20-, and 30- MeV bremsstrahlung. The photofission cross section for 242Pu was determined up to 30 MeV. For 242Pu(sf) the overall kinetic energy distribution is strongly asymmetric and the overall mass distribution has a very high peak yield (9%). Important deviations of the average total kinetic energy release and the average light and heavy fragment masses and from the systematics of Unik et al. are also observed for this fissioning system. These effects can be explained in the framework of the static scission point model by the strong preferential formation of a shell-stabilized scission configuration with the neutron number of the heavy and light fragments in the vicinity of the spherical N=82 neutron shell and the deformed N=66 neutron shell, respectively. A decrease of with the average excitation energy , dd=-0.30+/-0.04, is observed in the photofission of 242Pu. A study of the energy-mass correlations shows that the mentioned decrease is caused predominantly by a diminution of the shell corrections in the mass region of the spherical N=82 neutron shell. A comparison of the mass and kinetic energy distributions obtained in this work for 242Pu, with previously reported results for 240Pu and 244Pu and with scission point model calculations, is also included. [RADIOACTIVITY, FISSION 242Pu(sf). NUCLEAR REACTIONS, FISSION 241Pu(nth,f),242Pu(?,f),E?=12,15,20,30 MeV; measured photofission yields, fragment energies E1, E2; deduced ?(?,f), N(?,Ek).

Thierens, H.; Jacobs, E.; D'Hondt, P.; de Clercq, A.; Piessens, M.; de Frenne, D.

1984-02-01

18

Models and Modeling.  

ERIC Educational Resources Information Center

In this workshop, we will continue to reflect on a models and modeling perspective to understand how students and teachers learn and reason about real life situations encountered in a mathematics and science classroom. We will discuss the idea of a model as a conceptual system that is expressed by using external representational media, and that is…

Lesh, Richard; Carmona, Guadalupe; Post, Thomas

19

Models, Fiction, and Fictional Models  

NASA Astrophysics Data System (ADS)

The following sections are included: * Introduction * Why Most Models in Science Are Not Fictional * Typically Fictional Models in Science * Modeling the Unobservable * Fictional Models for the Unobservable? * References

Liu, Chuang

2014-03-01

20

Niche Modeling: Model Evaluation  

E-print Network

of carelessness. Among these aspects is that of model evaluation or validation. This unit provides a simple introduction to the basic concepts that are important in model validation, using some very simple examples. The focus is on two solutions to the challenge...

Peterson, A. Townsend

2012-08-29

21

Quantum Circuit Model Topological Model  

E-print Network

Quantum Circuit Model Topological Model Comparison of Models Topological Quantum Computation Eric Rowell Texas A&M University October 2010 Eric Rowell Topological Quantum Computation #12;Quantum Circuit Model Topological Model Comparison of Models Outline 1 Quantum Circuit Model Gates, Circuits

Rowell, Eric C.

22

MODEL DEVELOPMENT - DOSE MODELS  

EPA Science Inventory

Model Development Humans are exposed to mixtures of chemicals from multiple pathways and routes. These exposures may result from a single event or may accumulate over time if multiple exposure events occur. The traditional approach of assessing risk from a single chemica...

23

Modeling Malaria  

NSDL National Science Digital Library

In this module, we develop models of the effects of malaria on various populations of humans and mosquitoes. After considering differential equations to model a system, we create a model using the systems modeling tool STELLA. Projects involve various refinements of the model.

Angela B. Shiflet

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.

Betty Blecha

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.

Don Rathjen

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.

Shirley Watt Ireton

2003-01-01

27

MODEL ABSTRACTION IN HYDROLOGIC MODELING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Model abstraction (MA) is a methodology for reducing the complexity of a simulation model while maintaining the validity of the simulation results with respect to the question that the simulation is being used to address. The MA explicitly deals with uncertainties in model structure and in model par...

28

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

29

Modeling Transformation  

E-print Network

pGLO plasmids Bacterial chromosomal DNA Cell membrane #12;Heat-shock @ 42°C IncreasesModeling Transformation What does each step do? #12;Transformation Procedure #12;Transformation Procedure #12;Building Your Model Yarn = chromosomal DNA Beads

Rose, Michael R.

30

Modeling Convection  

NSDL National Science Digital Library

Typically, teachers use simple models that employ differences in temperature and density to help students visualize convection. However, most of these models are incomplete or merely hint at (instead of model) convective circulation. In order to make the use of models more effective, the authors developed an alternative system that uses a simple, low-cost apparatus that not only maintains dynamic convective circulation, but also illustrates two adjacent cells that teaches students about Earth's processes.

Amanda Schulz

2004-09-01

31

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

David Marchetti

32

Why Model?  

Microsoft Academic Search

This address treats some enduring misconceptions about modeling. One of these is that the goal is always prediction. The lecture distinguishes between explanation and prediction as modeling goals, and offers sixteen reasons other than prediction to build a model. It also challenges the common assumption that scientific theories arise from and 'summarize' data, when often, theories precede and guide data

Joshua M. Epstein

2008-01-01

33

Phoenix model  

EPA Science Inventory

Phoenix (formerly referred to as the Second Generation Model or SGM) is a global general equilibrium model designed to analyze energy-economy-climate related questions and policy implications in the medium- to long-term. This model disaggregates the global economy into 26 industr...

34

Modeling Arcs  

Microsoft Academic Search

Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma initiation, plasma evolution, surface damage and gra- dient limits. We use simple PIC codes for modeling plasmas, molecular dynamics for modeling surface

Zeke Insepov; Jim Norem; Seth Veitzer; Sudhakar Mahalingam

2011-01-01

35

SIR Model  

NSDL National Science Digital Library

This worksheet implements an SIR (Susceptible/ Infected/ Resistant) model of epidemiology for vector-borne diseases. Up to three microbial strains with different virulence and transmission parameters can be modeled and the results graphed. Originally designed to explore coevolution of myxoma and rabbits, the model is easily generalized to other systems.

Tony Weisstein (Truman State University; Biology)

2007-06-20

36

Animal models.  

PubMed

Epilepsy accounts for a significant portion of the dis-ease burden worldwide. Research in this field is fundamental and mandatory. Animal models have played, and still play, a substantial role in understanding the patho-physiology and treatment of human epilepsies. A large number and variety of approaches are available, and they have been applied to many animals. In this chapter the in vitro and in vivo animal models are discussed,with major emphasis on the in vivo studies. Models have used phylogenetically different animals - from worms to monkeys. Our attention has been dedicated mainly to rodents.In clinical practice, developmental aspects of epilepsy often differ from those in adults. Animal models have often helped to clarify these differences. In this chapter, developmental aspects have been emphasized.Electrical stimulation and chemical-induced models of seizures have been described first, as they represent the oldest and most common models. Among these models, kindling raised great interest, especially for the study of the epileptogenesis. Acquired focal models mimic seizures and occasionally epilepsies secondary to abnormal cortical development, hypoxia, trauma, and hemorrhage.Better knowledge of epileptic syndromes will help to create new animal models. To date, absence epilepsy is one of the most common and (often) benign forms of epilepsy. There are several models, including acute pharmacological models (PTZ, penicillin, THIP, GBL) and chronic models (GAERS, WAG/Rij). Although atypical absence seizures are less benign, thus needing more investigation, only two models are so far available (AY-9944,MAM-AY). Infantile spasms are an early childhood encephalopathy that is usually associated with a poor out-come. The investigation of this syndrome in animal models is recent and fascinating. Different approaches have been used including genetic (Down syndrome,ARX mutation) and acquired (multiple hit, TTX, CRH,betamethasone-NMDA) models.An entire section has been dedicated to genetic models, from the older models obtained with spontaneous mutations (GEPRs) to the new engineered knockout, knocking, and transgenic models. Some of these models have been created based on recently recognized patho-genesis such as benign familial neonatal epilepsy, early infantile encephalopathy with suppression bursts, severe myoclonic epilepsy of infancy, the tuberous sclerosis model, and the progressive myoclonic epilepsy. The contribution of animal models to epilepsy re-search is unquestionable. The development of further strategies is necessary to find novel strategies to cure epileptic patients, and optimistically to allow scientists first and clinicians subsequently to prevent epilepsy and its consequences. PMID:22938964

Coppola, Antonietta; Moshé, Solomon L

2012-01-01

37

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

38

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 ...

Mr. Ertl

2007-11-03

39

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.

John Nielsen-Gammon

1996-01-01

40

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

41

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.

Michael Freeze

42

Climate Models  

NASA Technical Reports Server (NTRS)

Climate models is a very broad topic, so a single volume can only offer a small sampling of relevant research activities. This volume of 14 chapters includes descriptions of a variety of modeling studies for a variety of geographic regions by an international roster of authors. The climate research community generally uses the rubric climate models to refer to organized sets of computer instructions that produce simulations of climate evolution. The code is based on physical relationships that describe the shared variability of meteorological parameters such as temperature, humidity, precipitation rate, circulation, radiation fluxes, etc. Three-dimensional climate models are integrated over time in order to compute the temporal and spatial variations of these parameters. Model domains can be global or regional and the horizontal and vertical resolutions of the computational grid vary from model to model. Considering the entire climate system requires accounting for interactions between solar insolation, atmospheric, oceanic and continental processes, the latter including land hydrology and vegetation. Model simulations may concentrate on one or more of these components, but the most sophisticated models will estimate the mutual interactions of all of these environments. Advances in computer technology have prompted investments in more complex model configurations that consider more phenomena interactions than were possible with yesterday s computers. However, not every attempt to add to the computational layers is rewarded by better model performance. Extensive research is required to test and document any advantages gained by greater sophistication in model formulation. One purpose for publishing climate model research results is to present purported advances for evaluation by the scientific community.

Druyan, Leonard M.

2012-01-01

43

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

44

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.

Bill Locke

45

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.

46

Cloud Modeling  

NASA Technical Reports Server (NTRS)

Numerical cloud models have been developed and applied extensively to study cloud-scale and mesoscale processes during the past four decades. The distinctive aspect of these cloud models is their ability to treat explicitly (or resolve) cloud-scale dynamics. This requires the cloud models to be formulated from the non-hydrostatic equations of motion that explicitly include the vertical acceleration terms since the vertical and horizontal scales of convection are similar. Such models are also necessary in order to allow gravity waves, such as those triggered by clouds, to be resolved explicitly. In contrast, the hydrostatic approximation, usually applied in global or regional models, does allow the presence of gravity waves. In addition, the availability of exponentially increasing computer capabilities has resulted in time integrations increasing from hours to days, domain grids boxes (points) increasing from less than 2000 to more than 2,500,000 grid points with 500 to 1000 m resolution, and 3-D models becoming increasingly prevalent. The cloud resolving model is now at a stage where it can provide reasonably accurate statistical information of the sub-grid, cloud-resolving processes poorly parameterized in climate models and numerical prediction models.

Tao, Wei-Kuo; Moncrieff, Mitchell; Einaud, Franco (Technical Monitor)

2001-01-01

47

Ventilation Model  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. The purposes of Revision 01 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To further satisfy KTI agreements RDTME 3.01 and 3.14 (Reamer and Williams 2001a) by providing the source documentation referred to in the KTI Letter Report, ''Effect of Forced Ventilation on Thermal-Hydrologic Conditions in the Engineered Barrier System and Near Field Environment'' (Williams 2002). Specifically to provide the results of the MULTIFLUX model which simulates the coupled processes of heat and mass transfer in and around waste emplacement drifts during periods of forced ventilation. This portion of the model report is presented as an Alternative Conceptual Model with a numerical application, and also provides corroborative results used for model validation purposes (Section 6.3 and 6.4).

V. Chipman

2002-10-05

48

Model Selection for Geostatistical Models  

SciTech Connect

We consider the problem of model selection for geospatial data. Spatial correlation is typically ignored in the selection of explanatory variables and this can influence model selection results. For example, the inclusion or exclusion of particular explanatory variables may not be apparent when spatial correlation is ignored. To address this problem, we consider the Akaike Information Criterion (AIC) as applied to a geostatistical model. We offer a heuristic derivation of the AIC in this context and provide simulation results that show that using AIC for a geostatistical model is superior to the often used approach of ignoring spatial correlation in the selection of explanatory variables. These ideas are further demonstrated via a model for lizard abundance. We also employ the principle of minimum description length (MDL) to variable selection for the geostatistical model. The effect of sampling design on the selection of explanatory covariates is also explored.

Hoeting, Jennifer A.; Davis, Richard A.; Merton, Andrew A.; Thompson, Sandra E.

2006-02-01

49

Turbulence modeling  

NASA Technical Reports Server (NTRS)

The objective of this work is to develop, verify, and incorporate the baseline two-equation turbulence models which account for the effects of compressibility into the three-dimensional Reynolds averaged Navier-Stokes (RANS) code and to provide documented descriptions of the models and their numerical procedures so that they can be implemented into 3-D CFD codes for engineering applications.

Bardina, Jorge E.

1995-01-01

50

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 which…

Washington State Board for Community Coll. Education, Olympia.

51

Modeling Sunspots  

ERIC Educational Resources Information Center

Modeling in science has been studied by education researchers for decades and is now being applied broadly in school. It is among the scientific practices featured in the "Next Generation Science Standards" ("NGSS") (Achieve Inc. 2013). This article describes modeling activities in an extracurricular science club in a high…

Oh, Phil Seok; Oh, Sung Jin

2013-01-01

52

Minibeast Models  

NSDL National Science Digital Library

In this activity, learners create models of bugs. Learners use household materials like plastic cups and straws to create models of bugs like centipedes and spiders. The activity is covered in the first 5 pages of the document. There are also a number of related activities that introduce learners to the world of invertebrates.

2012-06-26

53

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.

James Lovelock

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.

David Bice

55

Scale Models  

NSDL National Science Digital Library

In this activity, learners explore the relative sizes and distances of objects in the solar system. Without being informed of the expected product, learners will make a Play-doh model of the Earth-Moon system, scaled to size and distance. The facilitator reveals the true identity of the system at the conclusion of the activity. During the construction phase, learners try to guess what members of the solar system their model represents. Each group receives different amounts of Play-doh, with each group assigned a color (red, blue, yellow, white). At the end, groups set up their models and inspect the models of other groups. They report patterns of scale that they notice; as the amount of Play-doh increases, for example, so do the size and distance of the model. This resource guide includes background information about the Earth to Moon ratio and solar eclipses.

2012-06-26

56

Protein structure modeling with MODELLER.  

PubMed

Genome sequencing projects have resulted in a rapid increase in the number of known protein sequences. In contrast, only about one-hundredth of these sequences have been characterized at atomic resolution using experimental structure determination methods. Computational protein structure modeling techniques have the potential to bridge this sequence-structure gap. In this chapter, we present an example that illustrates the use of MODELLER to construct a comparative model for a protein with unknown structure. Automation of a similar protocol has resulted in models of useful accuracy for domains in more than half of all known protein sequences. PMID:24573470

Webb, Benjamin; Sali, Andrej

2014-01-01

57

OSPREY Model  

SciTech Connect

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 operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed within Multi-physics Object Oriented Simulation Environment (MOOSE) developed at the Idaho National Laboratory (INL). Off-gas Separation and REcoverY (OSPREY) models the adsorption of off-gas constituents for dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions. Inputs to the model include gas, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. The simulation outputs component concentrations along the column length as a function of time from which breakthrough data is obtained. The breakthrough data can be used to determine bed capacity, which in turn can be used to size columns. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data and parameters were input into the adsorption model to develop models specific for krypton adsorption. The same can be done for iodine, xenon, and tritium. The model will be validated with experimental breakthrough curves. Customers will be given access to OSPREY to used and evaluate the model.

Veronica J. Rutledge

2013-01-01

58

Model Center  

NSDL National Science Digital Library

A human is a complicated organism, and it is considered unethical to do many kinds of experiments on human subjects. For these reasons, biologists often use simpler 'model' organisms that are easy to keep and manipulate in the laboratory. Despite obvious differences, model organisms share with humans many key biochemical and physiological functions that have been conserved (maintained) by evolution. Each of the following model organisms has its advantages and disadvantages in different research applications. This tool allows you to examine the similarities between different systems by comparing the proteins they share and the proportion of DNA they have in common. Choose a gene from the drop-down menu and select the species you want to compare. Rolling over the images will give you a more detailed description of each model. Clicking on a gene�s name will take you to the National Center for Biological Information, where you can explore the latest relevant scientific literature.

2009-04-14

59

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

60

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...

61

Modeling Arcs  

E-print Network

Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma initiation, plasma evolution, surface damage and gra- dient limits. We use simple PIC codes for modeling plasmas, molecular dynamics for modeling surface breakdown, and surface damage, and mesoscale surface thermodynamics and finite element electrostatic codes for to evaluate surface properties. Since any given experiment seems to have more variables than data points, we have tried to consider a wide variety of arcing (rf structures, e beam welding, laser ablation, etc.) to help constrain the problem, and concentrate on common mechanisms. While the mechanisms can be comparatively simple, modeling can be challenging.

Insepov, Zeke; Veitzer, Seth; Mahalingam, Sudhakar

2011-01-01

62

Modeling Arcs  

SciTech Connect

Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma initiation, plasma evolution, surface damage and gradient limits. We use simple PIC codes for modeling plasmas, molecular dynamics for modeling surface breakdown, and surface damage, and mesoscale surface thermodynamics and finite element electrostatic codes for to evaluate surface properties. Since any given experiment seems to have more variables than data points, we have tried to consider a wide variety of arcing (rf structures, e beam welding, laser ablation, etc.) to help constrain the problem, and concentrate on common mechanisms. While the mechanisms can be comparatively simple, modeling can be challenging.

Insepov, Z.; Norem, J. [Argonne National Lab, Argonne, IL 60439 (United States); Vetizer, S.; Mahalingam, S. [Tech-X Corp., Boulder, CO (United States)

2011-12-23

63

Micromolecular modeling  

NASA Technical Reports Server (NTRS)

A reaction kinetics based model of the photodegradation process, which measures all important rate constants, and a computerized model capable of predicting the photodegradation rate and failure modes of a 30 year period, were developed. It is shown that the computerized photodegradation model for polyethylene correctly predicts failure of ELVAX 15 and cross linked ELVAX 150 on outdoor exposure. It is indicated that cross linking ethylene vinyl acetate (EVA) does not significantly change its degradation rate. It is shown that the effect of the stabilizer package is approximately equivalent on both polymers. The computerized model indicates that peroxide decomposers and UV absorbers are the most effective stabilizers. It is found that a combination of UV absorbers and a hindered amine light stabilizer (HALS) is the most effective stabilizer system.

Guillet, J. E.

1984-01-01

64

Device modeling  

NASA Technical Reports Server (NTRS)

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

1987-01-01

65

Molecular Models  

NSDL National Science Digital Library

Created and maintained by Dr. Dave Woodcock of the Chemistry Department at Okanagan University College in British Columbia, Canada, this site features models of over 1,100 molecules in .pdb, or Chemscape Chime, format (link to free download provided). Users may search the molecular database using an internal search engine or browse by category or alphabetically. Index page entries include the molecule's name, formula, molar mass, and comments. The site also features more detailed models of selected molecular fragments.

Woodcock, Dave.

66

Time-dependent isospin composition of particles emitted in fission events following Ar40+Au197 at 35 MeV/u  

NASA Astrophysics Data System (ADS)

Fission fragments resulting from the fission of target-like nuclei produced in the Ar40+Au197 reaction at 35 MeV/u are measured in coincidence with the emitted light charged particles (LCPs). Comparison of the N /Z composition of the LCPs at middle and large angles in the laboratory frame shows that particles emitted at smaller angles, which contain a larger contribution from dynamical emission, are more neutron rich. A moving-source model is used to fit the energy spectra of the hydrogen isotopes. A hierarchy from proton to deuteron and triton is observed in the multiplicity ratio between the intermediate velocity source and the compound nucleus source. This ratio is sensitive to the dynamical emission at early stages of the reaction and to statistical emission lasting up to the scission point. Calculations with the improved quantum molecular dynamics (ImQMD) transport-model qualitatively support the picture that more free and bound neutrons are emitted during the early stage, showing a clear dependence of N /Z on the parametrization of the symmetry energy. The time-dependent isospin composition of the emitted particles thus may be used to probe the symmetry energy at subsaturation densities.

Wang, R. S.; Zhang, Y.; Xiao, Z. G.; Tian, J. L.; Zhang, Y. X.; Wu, Q. H.; Duan, L. M.; Jin, G. M.; Hu, R. J.; Wang, S. F.; Li, Z. Y.; Wang, H. W.; Zhang, Z.; Yi, H.; Li, H. J.; Cheng, W. J.; Huang, Y.; Lü, L. M.

2014-06-01

67

Mass and nuclear charge yields for 237Np(2n th,f) at different fission fragment kinetic energies  

NASA Astrophysics Data System (ADS)

The recoil mass separator LOHENGRIN of the Laue-Langevin Institute Grenoble has been used to measure for the first time, the yields of light fission fragments from the fissioning system: 23993Np; this odd-Z nucleus is formed after double thermal neutron capture in a 23993Np target. The mass distributions were measured for different kinetic energies between 92 and 115.5 MeV, but the nuclear charge distributions were determined only up to 112 MeV. These distributions are compared to the distributions obtained for the even-even system 24094Pu. At high kinetic energy, the mass distribution shows a prominent peak around mass number AL = 106. These cold fragmentations are discussed in terms of a calculation based on a scission point model extrapolated to the cold fission case. As expected for an odd- Z fissioning nucleus, the nuclear charge distributions do not reveal any odd-even effect. The global neutron odd-even effect is found to be (8.1 ± 1.5)%. A simple model has been used to show that most of the neutron odd-even effect results from prompt neutron evaporation from the fragments.

Martinez, G.; Barreau, G.; Sicre, A.; Doan, T. P.; Audouard, P.; Leroux, B.; Arafa, W.; Brissot, R.; Bocquet, J. P.; Faust, H.; Koczon, P.; Mutterer, M.; Gönnenwein, F.; Asghar, M.; Quade, U.; Rudolph, K.; Engelhardt, D.; Piasecki, E.

1990-09-01

68

Modeling depression in animal models.  

PubMed

Animal models and preclinical tests have played large roles in the development of antidepressant drugs and are likely to continue to play important roles. In the present communication, the main animal models of depression have been described and reviewed. These models include the Flinders sensitive line (FSL) rat, the Wistar Kyoto (WKY) rat, the fawn-hooded (FH) rat, and the learned helpless (LH) rat. In addition, the materials used to assess the behavior of these rats, including swim tanks, drinking tubes, and an open field apparatus, have been discussed. Finally, the methods used in collecting the relevant behaviors in the animal models are described. These include the procedures used in the forced swim test and chronic mild stress protocols, including the sucrose preference test. It is concluded that the behavioral tests used to infer depressed-like behavior in rats will continue to provide useful data if the appropriate animals and proper methods are used. PMID:22231810

Overstreet, David H

2012-01-01

69

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

70

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

71

Modeling reality  

NASA Technical Reports Server (NTRS)

Although powerful computers have allowed complex physical and manmade hardware systems to be modeled successfully, we have encountered persistent problems with the reliability of computer models for systems involving human learning, human action, and human organizations. This is not a misfortune; unlike physical and manmade systems, human systems do not operate under a fixed set of laws. The rules governing the actions allowable in the system can be changed without warning at any moment, and can evolve over time. That the governing laws are inherently unpredictable raises serious questions about the reliability of models when applied to human situations. In these domains, computers are better used, not for prediction and planning, but for aiding humans. Examples are systems that help humans speculate about possible futures, offer advice about possible actions in a domain, systems that gather information from the networks, and systems that track and support work flows in organizations.

Denning, Peter J.

1990-01-01

72

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

73

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

74

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...

75

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

76

Model thinking.  

PubMed

Nancy Roper, Win Logan and Alison Tierney published their ground-breaking model of nursing in 1980, sparking the evolution of nursing theory from staid, biomedical thinking to an individualised, independent approach. Jane Salvage looks back at the lasting impact their research had on her and the profession as whole. PMID:16425763

Salvage, Jane

77

Model Organisms  

NSDL National Science Digital Library

A human is a complicated organism, and it is considered unethical to do many kinds of experiments on human subjects. For these reasons, biologists often use simpler �model� organisms that are easy to keep and manipulate in the laboratory. Despite ob

2009-04-14

78

Marshmallow Models  

NSDL National Science Digital Library

No glue is needed for learners of any age to become marshmallow architects or engineers. Using marshmallows and water (and maybe edible decorations like peanut butter, pretzels, gumdrops, etc.), learners wet a few marshamallows at a time and stick them together bit by bit to construct whatever models they want.

Lawrence Hall of Science

2010-01-01

79

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.

Kirsten Menking

80

Groundwater Model  

NSDL National Science Digital Library

In this activity, students build a model to demonstrate how aquifers are formed and ground water becomes polluted. For younger students, the teacher can perform this activity as a demonstration, or older students can perform it themselves. A materials list, instructions, and extension activities are provided.

81

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

82

Urban Modelling  

Microsoft Academic Search

Urban models are computer-based simulations used for testing theories about spatial location and interaction between land uses and related activities. They also provide digital environments for testing the consequences of physical planning policies on the future form of cities. As computers, software and data have become richer, and as our conception of the way complex systems such as cities grow

Michael Batty; Rob Kitchin; Nigel Thrift

83

Diffusion Models  

NSDL National Science Digital Library

Web-based intructional material describing the use of diffusion models in population ecology. This page is part of a set of on-line lectures on Quantitative Population Ecology produced by Alexei Sharov in the Department of Entomology at Virginia Tech.

Alexei Sharov

84

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

85

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

86

Nuclear-charge distribution for A=121 from thermal-neutron-induced fission of 235U  

NASA Astrophysics Data System (ADS)

The fractional cumulative yield of 121Ag and the fractional independent yields of 121Cd, 121In, and 121Sn from thermal-neutron-induced fission of 235U were determined radiochemically to be 0.12+/-0.05, 0.61+/-0.09, 0.24+/-0.08, and 0.03+/-0.04, respectively. The yield values were used to determine the nuclear-charge-distribution parameters ?Z=0.55+/-0.10 and ?Z=0.50+/-0.05 for A=121. The ?Z for A=121 is close to ?Z¯=0.52+/-0.02 for high-yield fission products, and no evidence for an even-odd Z effect was found for A=121. The positive ?Z value, which corresponds to ZP=48.15, is similar to those for several higher mass numbers reported previously, and it is considerably greater than the negative values predicted by the scission-point theoretical model. The use of a separation distance between nascent fragments greater than 1.4 fm, the value used in the theoretical calculations, could reduce the discrepancy and could also account for the observed enhanced independent yields of tin fission products with ZP near 50 (A=126-129).

Robinson, Larry; Wahl, Arthur C.; Semkow, Tomasz M.; Norris, Andrew E.

1985-04-01

87

Micrometer Model  

NSDL National Science Digital Library

This interactive simulation gives students practice in the operation and the physical parts of a real micrometer, a measuring device that employs a screw to amplify distances that are too small to measure easily. 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).

2009-09-10

88

Modelling Coalitions: . . .  

E-print Network

In the last few years, argumentation frameworks have been successfully applied to multi agent systems. Recently, argumentation has been used to provide a framework for reasoning about coalition formation. At the same time alternatingtime temporal logic has been used to reason about the behavior and abilities of coalitions of agents. However, ATL operators account only for the existence of successful strategies of coalitions. They do not consider whether coalitions can be actually formed. This paper is an attempt to combine both frameworks and to develop a logic through which we can reason at the same time (1) about abilities of coalitions of agents and (2) about the formation of coalitions. We provide a formal extension of ATL, ATL c, in which the actual computation of the coalition is modelled in terms of argumentation semantics. We show that ATL c ’s proof theory can be understood as a natural extension of the model checking procedure used in ATL.

Nils Bulling; Jürgen Dix; Carlos I. Chesñevar

2008-01-01

89

Simple Models  

NSDL National Science Digital Library

As stated in "About This Book," the author isn't going to take the usual approach to the subject of chemistry. Because virtually all explanations of chemical reactions are based on our current model of atoms and molecules, the first thing to do here is to help you understand why we believe that atoms and molecules look and act the way they do. That's not a trivial issue, because despite the impression you might have gotten from textbooks, no one has ever seen an atom in the sense that you can see this page in front of you. What we have are observations and experiments that lead us to formulate models of atoms. This free selection includes the Table of Contents, Preface, About This Book section, a Safety Note, and the Glossary.

William C. Robertson, Ph.D.

2007-01-01

90

Fibre Models  

NASA Astrophysics Data System (ADS)

Fibre models have been introduced as simple models to describe failure. They are based on the probability distribution of broken fibres. The load redistribution after a fibre yields can be global or local and the first case can often be solved analytically. We will present an interpolation between these the local and the global case and apply it to experimental situations like the compression of granular packings. Introducing viscoelastic fibres allows to describe the creep of wood. It is even possible to deal analytically with a gradual degradation of fibres and consider damage as well as healing. In this way Basquin's law of fatigue can be reproduced and new universalities concerning the histograms of bursts and waiting times can be uncovered.

Herrmann, H. J.; Kun, F.

2007-12-01

91

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.

Frank Wattenberg

1997-01-01

92

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."

The Exploratorium

2013-01-30

93

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

94

Model checking  

NASA Technical Reports Server (NTRS)

Automatic formal verification methods for finite-state systems, also known as model-checking, successfully reduce labor costs since they are mostly automatic. Model checkers explicitly or implicitly enumerate the reachable state space of a system, whose behavior is described implicitly, perhaps by a program or a collection of finite automata. Simple properties, such as mutual exclusion or absence of deadlock, can be checked by inspecting individual states. More complex properties, such as lack of starvation, require search for cycles in the state graph with particular properties. Specifications to be checked may consist of built-in properties, such as deadlock or 'unspecified receptions' of messages, another program or implicit description, to be compared with a simulation, bisimulation, or language inclusion relation, or an assertion in one of several temporal logics. Finite-state verification tools are beginning to have a significant impact in commercial designs. There are many success stories of verification tools finding bugs in protocols or hardware controllers. In some cases, these tools have been incorporated into design methodology. Research in finite-state verification has been advancing rapidly, and is showing no signs of slowing down. Recent results include probabilistic algorithms for verification, exploitation of symmetry and independent events, and the use symbolic representations for Boolean functions and systems of linear inequalities. One of the most exciting areas for further research is the combination of model-checking with theorem-proving methods.

Dill, David L.

1995-01-01

95

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

96

10. MOVABLE BED SEDIMENTATION MODELS. DOGTOOTH BEND MODEL (MODEL SCALE: ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. MOVABLE BED SEDIMENTATION MODELS. DOGTOOTH BEND MODEL (MODEL SCALE: 1' = 400' HORIZONTAL, 1' = 100' VERTICAL), AND GREENVILLE BRIDGE MODEL (MODEL SCALE: 1' = 360' HORIZONTAL, 1' = 100' VERTICAL). - Waterways Experiment Station, Hydraulics Laboratory, Halls Ferry Road, 2 miles south of I-20, Vicksburg, Warren County, MS

97

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

98

Atomic Models, Nagaoka's Saturnian Model  

Microsoft Academic Search

In late 1903, Hantaro Nagaoka (1865–1950) developed the earliest published quasi-planetary model of the atom. This graduate\\u000a of the University of Tokyo from 1887 spent his postdoctoral period in Vienna, Berlin and Munich before obtaining a professorship\\u000a in Tokyo to become Japan's foremost modern physicist. Nagaoka assumed that the atom is a large, massive, positively charged\\u000a sphere, encircled by very

Klaus Hentschel

99

Biomimetic modelling.  

PubMed Central

Biomimetics is seen as a path from biology to engineering. The only path from engineering to biology in current use is the application of engineering concepts and models to biological systems. However, there is another pathway: the verification of biological mechanisms by manufacture, leading to an iterative process between biology and engineering in which the new understanding that the engineering implementation of a biological system can bring is fed back into biology, allowing a more complete and certain understanding and the possibility of further revelations for application in engineering. This is a pathway as yet unformalized, and one that offers the possibility that engineers can also be scientists. PMID:14561351

Vincent, Julian F V

2003-01-01

100

Cancer Models  

Microsoft Academic Search

The aims of this study were to evaluate the distributionof 99mTcmetho@yisobutyIisonitrile (MIBI) in 3 animal models of breastcancer,the effectof radiotherapyon @Tc-MIBl uptake, and the relationshipbetweenuptakeand microvesseldensity. Methods:We used syngeneic,subcutaneously transplanted FM3A,MM48,and Ehrlichmousebreastcancer. @mTc-MlBl and FDG were injected intravenously, and tumor uptake was mea sured30 mmlater.Double-tracermacroautoradiography (ARG) imageswere preparedwith @mTc-MlBl and 2-deoxy-D-(1 -14C)- glucose(14C-DG), analyzedquantitatively,and comparedwith histology.The radiotherapeutic effectsof 20 Gy

Hiromichi Ohira; Kazuo Kubota; Noriaki Ohuchi; Yukou Harada; Hiroshi Fukuda; Susumu Satomi

101

Constructing NARMAX models using ARMAX models  

Microsoft Academic Search

This paper outlines how it is possible to decompose a complex non-linear modelling problem into a set of simpler linear modelling problems. Local ARMAX models valid within certain operating regimes are interpolated to construct a global NARMAX (non-linear NARMAX) model. Knowledge of the system behaviour in terms of operating regimes is the primary basis for building such models, hence it

TOR A. JOHANSEN; BJARNE A. FOSS

1993-01-01

102

Graphical models, causal inference, and econometric models  

E-print Network

Graphical models, causal inference, and econometric models Peter Spirtes Abstract A graphical model modeling has historical ties to causal modeling in econometrics and other social sciences, there have been isolated from the econometric tradition. In this paper I will describe a number of recent developments

Spirtes, Peter

103

The Standard Model Beyond the Standard Model  

E-print Network

The Standard Model Beyond the Standard Model New physics with top quark Search for Extra, January 13, 2010 Ritesh Singh New physics at LHC #12;The Standard Model Beyond the Standard Model New physics with top quark Search for Extra-dimensions Conclusions 1 The Standard Model Building block

104

Pre-Modeling Ensures Accurate Solid Models  

ERIC Educational Resources Information Center

Successful solid modeling requires a well-organized design tree. The design tree is a list of all the object's features and the sequential order in which they are modeled. The solid-modeling process is faster and less prone to modeling errors when the design tree is a simple and geometrically logical definition of the modeled object. Few high…

Gow, George

2010-01-01

105

Technological Forecasting---Model Selection, Model Stability, and Combining Models  

Microsoft Academic Search

The paper identifies 29 models that the literature suggests are appropriate for technological forecasting. These models are divided into three classes according to the timing of the point of inflexion in the innovation or substitution process. Faced with a given data set and such a choice, the issue of model selection needs to be addressed. Evidence used to aid model

Nigel Meade; Towhidul Islam

1998-01-01

106

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. PMID:22882887

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

2012-01-01

107

Modelling Sonoluminescence  

E-print Network

In single-bubble sonoluminescence, a bubble trapped by a sound wave in a flask of liquid is forced to expand and contract; exactly once per cycle, the bubble emits a very sharp ($< 50 ps$) pulse of visible light. This is a robust phenomenon observable to the naked eye, yet the mechanism whereby the light is produced is not well understood. One model that has been proposed is that the light is "vacuum radiation" generated by the coupling of the electromagnetic fields to the surface of the bubble. In this paper, we simulate vacuum radiation by solving Maxwell's equations with an additional term that couples the field to the bubble's motion. We show that, in the static case originally considered by Casimir, we reproduce Casimir's result. In a simple purely time-dependent example, we find that an instability occurs and the pulse of radiation grows exponentially. In the more realistic case of spherically-symmetric bubble motion, we again find exponential growth in the context of a small-radius approximation.

Alan Chodos; Sarah Groff

1998-11-04

108

Modeling sonoluminescence  

SciTech Connect

In single-bubble sonoluminescence, a bubble trapped by a sound wave in a flask of liquid is forced to expand and contract; exactly once per cycle, the bubble emits a very sharp ({lt}50 ps) pulse of visible light. This is a robust phenomenon observable to the naked eye, yet the mechanism whereby the light is produced is not well understood. One model that has been proposed is that the light is {open_quotes}vacuum radiation{close_quotes} generated by the coupling of the electromagnetic fields to the surface of the bubble. In this paper, we simulate vacuum radiation by solving Maxwell{close_quote}s equations with an additional term that couples the field to the bubble{close_quote}s motion. We show that, in the static case originally considered by Casimir [Proc. K. Ned. Akad. Nel. {bold 51}, 783 (1948)], we reproduce Casimir{close_quote}s result. In a simple purely time-dependent example, we find that an instability occurs and the pulse of radiation grows exponentially. In the more realistic case of spherically symmetric bubble motion, we again find exponential growth in the context of a small-radius approximation. {copyright} {ital 1999} {ital The American Physical Society}

Chodos, A. [Center for Theoretical Physics, Yale University, 217 Prospect Street, New Haven, Connecticut 06511-8167 (United States)] [Center for Theoretical Physics, Yale University, 217 Prospect Street, New Haven, Connecticut 06511-8167 (United States); Groff, S. [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

1999-03-01

109

Fission barriers and half-lives of actinides in the quasi-molecular shape valley G. Royer, M. Jaffre, D. Moreau  

E-print Network

. 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 fragments­17], and light nucleus emission [18, 19], and fusion data [20] have been also reproduced in the fusionlike shape

Boyer, Edmond

110

Rossignac & Requicha Solid Modeling 1 Solid Modeling  

E-print Network

Rossignac & Requicha Solid Modeling 1 Solid Modeling Jarek R. Rossignac GVU Center, College University of Southern California at Los Angeles 1 Introduction A solid model is a digital representation of the geometry of an existing or envisioned physical object. Solid models are used in many industries, from

Rossignac, Jarek

111

Analytic Modeling Birth-Death Model  

E-print Network

Analytic Modeling Birth-Death Model 1 A Review -Random Variables · A variable representing on Exponential Distribution 11 Birth-Death Model 12 #12;Birth-Death Model · Queuing system with a single service State Dependent Arrival Rate 14 #12;State Dependent Service Rate 15 Definition of Birth-Death Process 16

Shihada, Basem

112

THE EVT HEV MODEL A. Kinematics Model  

E-print Network

is limited to between zero and ,maxvehv . The torque applied by the chassis brake is limited to a maximum of ,maxkT . The chassis brake cannot apply torque to accelerate the vehicle. These limits are expressed. Engine Model The engine model is based on a Willan's Line model, similar to [3, 4]. The engine is modeled

Grizzle, Jessy W.

113

I&C Modeling in SPAR Models  

SciTech Connect

The Standardized Plant Analysis Risk (SPAR) models for the U.S. commercial nuclear power plants currently have very limited instrumentation and control (I&C) modeling [1]. Most of the I&C components in the operating plant SPAR models are related to the reactor protection system. This was identified as a finding during the industry peer review of SPAR models. While the Emergency Safeguard Features (ESF) actuation and control system was incorporated into the Peach Bottom Unit 2 SPAR model in a recent effort [2], various approaches to expend resources for detailed I&C modeling in other SPAR models are investigated.

John A. Schroeder

2012-06-01

114

Comparative Protein Structure Modeling Using Modeller  

PubMed Central

Functional characterization of a protein sequence is one of the most frequent problems in biology. This task is usually facilitated by accurate three-dimensional (3-D) structure of the studied protein. In the absence of an experimentally determined structure, comparative or homology modeling can sometimes provide a useful 3-D model for a protein that is related to at least one known protein structure. Comparative modeling predicts the 3-D structure of a given protein sequence (target) based primarily on its alignment to one or more proteins of known structure (templates). The prediction process consists of fold assignment, target-template alignment, model building, and model evaluation. This unit describes how to calculate comparative models using the program MODELLER and discusses all four steps of comparative modeling, frequently observed errors, and some applications. Modeling lactate dehydrogenase from Trichomonas vaginalis (TvLDH) is described as an example. The download and installation of the MODELLER software is also described. PMID:18428767

Eswar, Narayanan; Marti-Renom, Marc A.; Madhusudhan, M.S.; Eramian, David; Shen, Min-yi; Pieper, Ursula

2014-01-01

115

Modeling cholera outbreaks  

PubMed Central

Mathematical modeling can be a valuable tool for studying infectious disease outbreak dynamics and simulating the effects of possible interventions. Here, we describe approaches to modeling cholera outbreaks and how models have been applied to explore intervention strategies, particularly in Haiti. Mathematical models can play an important role in formulating and evaluating complex cholera outbreak response options. Major challenges to cholera modeling are insufficient data for calibrating models and the need to tailor models for different outbreak scenarios. PMID:23412687

Longini, Ira M.; Morris, J. Glenn

2014-01-01

116

Uncertainty Modeling Via Frequency Domain Model Validation  

NASA Technical Reports Server (NTRS)

Abstract 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 even less attention. The research reported herein is an initial step in applying and extending the concept of model validation to the problem of obtaining practical uncertainty models for robust control analysis and design applications. An extension of model validation called 'sequential validation' is presented and applied to a simple spring-mass-damper system to establish the feasibility of the approach and demonstrate the benefits of the new developments.

Waszak, Martin R.; Andrisani, Dominick, II

1999-01-01

117

Model Theory and Quantum  

E-print Network

Model Theory and Quantum Groups Sonia L'Innocente Model Theory and Quantum Groups Sonia L'Innocente (University of Mons) Model Theory and Quantum Groups 1 / 40 #12;Model Theory and Quantum Groups Sonia L Theory and Quantum Groups 2 / 40 #12;Model Theory and Quantum Groups Sonia L'Innocente Seminar's aim We

Mons-Hainaut, Université de

118

Opponent Modeling in Machiavelli  

Microsoft Academic Search

Opponent modeling is a technique in computer game-playing which attempts to create a model of an opponent's strategy. This model can then be used to predict the opponent's future ac- tions. This paper attempts to apply opponent modeling to the commercial card game Machi- avelli1, a game containing imperfect informa- tion. Neural networks are used to build the models. These

M. H. J. Bergsma

119

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

120

Modeling the Heart  

NSDL National Science Digital Library

Models of the heart have been developed since 1960, starting with the discovery and modeling of potassium channels. The first models of calcium balance were made in the 1980s and have now reached a high degree of physiological detail. During the 1990s, these cell models were incorporated into anatomically detailed tissue and organ models.

Denis Noble (Oxford University Department of Physiology)

2004-08-01

121

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

122

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

123

Modeling transient rootzone salinity (SWS Model)  

Technology Transfer Automated Retrieval System (TEKTRAN)

The combined, water quality criteria for irrigation, water and ion processes in soils, and plant and soil response is sufficiently complex that adequate analysis requires computer models. Models for management are also needed but these models must consider that the input requirements must be reasona...

124

Cognitive Modeling Cognitive Modelling -The nature of  

E-print Network

Cognitive Modeling Cognitive Modelling - The nature of Connectionism and notes on computability Mathias Hinz Universität Bremen November 17, 2014 November 17, 2014 1 #12;Cognitive Modeling topic · Comparing PDP and nature · properties of PDP · computability · discussion November 17, 2014 2 #12;Cognitive

Bremen, Universität

125

Models of Magnetism.  

ERIC Educational Resources Information Center

Investigates the mental models that people construct about magnetic phenomena. Involves students, physics teachers, engineers, and practitioners. Proposes five models following a progression from simple description to a field model. Contains 28 references. (DDR)

Borges, A. Tarciso; Gilbert, John K.

1998-01-01

126

MODEL CONSERVATION STANDARD INTRODUCTION  

E-print Network

MODEL CONSERVATION STANDARD INTRODUCTION As directed by the Northwest Power Act, the Council has designed model conservation standards to produce all electricity savings that are cost believes the measures used to achieve the model conservation standards should provide reliable savings

127

Mathematics and Statistics Models  

NSDL National Science Digital Library

Developed by Bob MacKay, Clark College. What are Mathematical and Statistical Models These types of models are obviously related, but there are also real differences between them. Mathematical Models: grow out of ...

128

Composite Linear Models  

Cancer.gov

Statistical Software Composite Linear Models (Written by Stuart G. Baker) The composite linear models software is a matrix approach to compute maximum likelihood estimates and asymptotic standard errors for models for incomplete multinomial data. It

129

Editor's Roundtable: Model behavior  

NSDL National Science Digital Library

Models are manageable representations of objects, concepts, and phenomena, and are everywhere in science. Models are "thinking tools" for scientists and have always played a key role in the development of scientific knowledge. Models of the solar system,

Inez Liftig

2010-11-01

130

Orbital Debris Modeling  

NASA Technical Reports Server (NTRS)

Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)

Liou, J. C.

2012-01-01

131

Geologic Framework Model Analysis Model Report  

SciTech Connect

The purpose of this report is to document the Geologic Framework Model (GFM), Version 3.1 (GFM3.1) with regard to data input, modeling methods, assumptions, uncertainties, limitations, and validation of the model results, qualification status of the model, and the differences between Version 3.1 and previous versions. The GFM represents a three-dimensional interpretation of the stratigraphy and structural features of the location of the potential Yucca Mountain radioactive waste repository. The GFM encompasses an area of 65 square miles (170 square kilometers) and a volume of 185 cubic miles (771 cubic kilometers). The boundaries of the GFM were chosen to encompass the most widely distributed set of exploratory boreholes (the Water Table or WT series) and to provide a geologic framework over the area of interest for hydrologic flow and radionuclide transport modeling through the unsaturated zone (UZ). The depth of the model is constrained by the inferred depth of the Tertiary-Paleozoic unconformity. The GFM was constructed from geologic map and borehole data. Additional information from measured stratigraphy sections, gravity profiles, and seismic profiles was also considered. This interim change notice (ICN) was prepared in accordance with the Technical Work Plan for the Integrated Site Model Process Model Report Revision 01 (CRWMS M&O 2000). The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The GFM is one component of the Integrated Site Model (ISM) (Figure l), which has been developed to provide a consistent volumetric portrayal of the rock layers, rock properties, and mineralogy of the Yucca Mountain site. The ISM consists of three components: (1) Geologic Framework Model (GFM); (2) Rock Properties Model (RPM); and (3) Mineralogic Model (MM). The ISM merges the detailed project stratigraphy into model stratigraphic units that are most useful for the primary downstream models and the repository design. These downstream models include the hydrologic flow models and the radionuclide transport models. All the models and the repository design, in turn, will be incorporated into the Total System Performance Assessment (TSPA) of the potential radioactive waste repository block and vicinity to determine the suitability of Yucca Mountain as a host for the repository. The interrelationship of the three components of the ISM and their interface with downstream uses are illustrated in Figure 2.

R. Clayton

2000-12-19

132

BioModels Database  

NSDL National Science Digital Library

Hosted by the European Bioinformatics Institute, the BioModels Database is a collaborative, "new effort to develop a data resource that will allow biologist to store, search and retrieve published mathematical models of biological interests. The models in the BioModels Database are annotated and linked to relevant data resources, such as publications, databases of compounds and pathways, controlled vocabularies, etc." The website allows visitors to browse and search the Database for models. The site also provides information about submitting models for the Database. It should be noted that submitted models must undergo tests conducted by BioModels Database curators before they are incorporated. [NL

133

Generalized smooth models  

SciTech Connect

The class of gene linear models is extended to develop a class of nonparametric regression models known as generalized smooth models. The technique of local scoring is used to estimate a generalized smooth model and the estimation procedure based on locally weighted regression is shown to produce local likelihood estimates. The asymptotically correct distribution of the deviance difference is derived and its use in comparing the fits of generalized linear models and generalized smooth models is illustrated. The relationship between generalized smooth models and generalized additive models is discussed, also.

Glosup, J.

1992-07-23

134

Comparative Protein Structure Modeling Using MODELLER.  

PubMed

Functional characterization of a protein sequence is one of the most frequent problems in biology. This task is usually facilitated by accurate three-dimensional (3-D) structure of the studied protein. In the absence of an experimentally determined structure, comparative or homology modeling can sometimes provide a useful 3-D model for a protein that is related to at least one known protein structure. Comparative modeling predicts the 3-D structure of a given protein sequence (target) based primarily on its alignment to one or more proteins of known structure (templates). The prediction process consists of fold assignment, target-template alignment, model building, and model evaluation. This unit describes how to calculate comparative models using the program MODELLER and discusses all four steps of comparative modeling, frequently observed errors, and some applications. Modeling lactate dehydrogenase from Trichomonas vaginalis (TvLDH) is described as an example. The download and installation of the MODELLER software is also described. Curr. Protoc. Bioinform. 47:5.6.1-5.6.32. © 2014 by John Wiley & Sons, Inc. PMID:25199792

Webb, Benjamin; Sali, Andrej

2014-01-01

135

MARS software model for modeling modular manipulators  

NASA Astrophysics Data System (ADS)

In this paper we describe the application of the MARS model, for modelling and reasoning about modular robot systems, to modular manipulators. The MARS model provides a mechanism for describing robotic components and a method for reasoning about the interaction of these components in modular manipulator configurations. It specifically aims to articulate functionality that is a property of the whole manipulator, but which is not represented in any one component. This functionality arises, in particular, through the capacity for modules to inherit functionality from each other. The paper also uses the case of modular manipulators to illustrate a number of features of the MARS model, including the use of abstract and concrete module classes, and to identify some current limitations of the model. The latter provide the basis for ongoing development of the model.

McKee, Gerard T.; Fryer, J. A.; Schenker, Paul S.

2001-10-01

136

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

137

Strategic Thinking of Modeling Method and Modeling  

Microsoft Academic Search

Three-dimensional computer software have much to accomplish in the current application areas because they all have powerful modeling and simulation and recycling functions of real scenes. Today the most well-known and widely used 3D software should be 3DSMAX software, which is widely used in construction, decoration, video advertising and other areas. It offers us many modeling functions and various modeling

Guobin Peng; Runhong Peng

2010-01-01

138

The Rater Bundle Model.  

ERIC Educational Resources Information Center

Introduces the Rater Bundle Model, an item response model for repeated ratings of student work. Applies the model to real and simulated data to illustrate the approach, which was motivated by the observation that when repeated ratings occur, the assumption of conditional independence is violated, and current item response models can then…

Wilson, Mark; Hoskens, Machteld

2001-01-01

139

Instructional Models (Part III).  

ERIC Educational Resources Information Center

Describes five models for instructional design, including the ASSURE Model (analyze learners, state objectives, select methods, media and materials, utilize media and materials, require learner participation, and evaluate); the Learning Cycle; Instructional Analysis Model; Integrated Model for Teaching Library Skills; and Instructional…

Callison, Daniel

2002-01-01

140

Securing the biometric model  

Microsoft Academic Search

We propose a structured methodology following a full vulnerability analysis of the general biometric model outlined by Mansfield and Wayman (2002). Based on this analysis, a new multidimensional paradigm named the biometric architecture & system security (BASS) model is proposed, which adds comprehensive security and management layers to the existing biometric model. The BASS model is a structured methodology that

Anthony C. LENISKI; Richard C. SKINNER; Shawn F. McGANN; Stephen J. ELLIOTT

2003-01-01

141

Learning Tractable Probabilistic Models  

E-print Network

of Washington Daniel Lowd Dept. Computer & Information Science University of Oregon #12;Outline l Motivation l Standard tractable models l The sum-product theorem l Bounded-inference graphical models l Feature trees l Sum-product networks l Tractable Markov logic l Other tractable models 2 #12;Goal: Large Joint Models

Lowd, Daniel

142

Semantic data models  

Microsoft Academic Search

Semantic data models have emerged from a requirement for more expressive conceptual data models. Current generation data models lack direct support for relationships, data abstraction, inheritance, constraints, unstructured objects, and the dynamic properties of an application. Although the need for data models with richer semantics is widely recognized, no single approach has won general acceptance. This paper describes the generic

Joan Peckham; Fred J. Maryanski

1988-01-01

143

Multimodeling and Model Abstraction  

Technology Transfer Automated Retrieval System (TEKTRAN)

The multiplicity of models of the same process or phenomenon is the commonplace in environmental modeling. Last 10 years brought marked interest to making use of the variety of conceptual approaches instead of attempting to find the best model or using a single preferred model. Two systematic approa...

144

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

145

Modeling tidal turbines  

Microsoft Academic Search

Performance prediction models are valuable tools for use in the development of tidal turbines. A model that can accurately predict the performance of a device can be used to optimize the design parameters more rapidly and at a much lower cost than carrying out the design studies using scale model tests. Tidal turbine models are principally dependent on the aerodynamic

N. E. Turner; A. Owen; M. Hossain

2008-01-01

146

Mesoscale Ocean Circulation Models  

NSDL National Science Digital Library

This module examines mesoscale ocean circulation models and features and processes that they predict. These models simulate temperature, salinity, currents, and elevation in 3 dimensions through a period of time. They have sufficient resolution to simulate features like fronts, eddies, upwelling, and internal tides. In this module, we examine current operational models, limitations to model forecasts, examples of predicted ocean features, and potential applications.

2014-09-14

147

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

148

Fire Model Matrix  

NSDL National Science Digital Library

The Fire Model Matrix is an on-line resource that presents four fire community models in a matrix that facilitates the exploration of the characteristics of each model. As part of the Advanced Fire Weather Forecasters Course, this matrix is meant to sensitize forecasters to the use of weather data in these fire models to forecast potential fire activity.

2014-09-14

149

Process models for industry  

SciTech Connect

The purpose of this paper is to describe and illustrate how process models developed at BNL are used to analyze industrial energy use. A model of the US pulp and paper industry is described and discussed as a specific application of process modeling methodology. Case study results from the pulp and paper model illustrate how process models can be used to analyze a variety of issues. Applications discussed include projections of energy demand, conservation technology assessment, energy-related tax policies, and sensitivity analysis. A subsequent discussion of these results supports the conclusion that industry process models are versatile and powerful tools for energy end-use modeling and conservation analysis.

Pierce, B.; Hill, D.; Howe, S.O.

1981-01-01

150

Nearshore Wave Modeling  

NSDL National Science Digital Library

Ocean waves near shore impact public safety, commerce, navigation, and, of course recreation. Predicting these waves has driven efforts to model them for more than two decades. This module introduces forecasters to different nearshore wave models, including phase-resolving and 1- and 2-dimensional spectral models. It describes the processes that wave models simulate, the assumptions they make, the initial and boundary conditions required to run the models, and potential sources of error in model forecasts. While focusing on SWAN, the module also examines the Navy Standard surf Model and Bouss-2D.

COMET

2009-05-19

151

Calibrated Properties Model  

SciTech Connect

The purpose of this Analysis/Model Report (AMR) is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Yucca Mountain Site Characterization Project (YMP). This work was performed in accordance with the ''AMR Development Plan for U0035 Calibrated Properties Model REV00. These calibrated property sets include matrix and fracture parameters for the UZ Flow and Transport Model (UZ Model), drift seepage models, drift-scale and mountain-scale coupled-processes models, and Total System Performance Assessment (TSPA) models as well as Performance Assessment (PA) and other participating national laboratories and government agencies. These 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.

C. Ahlers; H. Liu

2000-03-12

152

Model Comparison Bayes rule for  

E-print Network

Model Comparison Bayes rule for models Bayes factors Spike rates Linear Models Model Evidence Complexity AIC and BIC Example fMRI example Bayes versus classical inference Model evidence in data space;Model Comparison Bayes rule for models Bayes factors Spike rates Linear Models Model Evidence Complexity

Penny, Will

153

ULTRA-UNIVERSAL MODELS  

Microsoft Academic Search

The concept of ultra-universal algebras in varieties is generalized to models of first order theories. Characterizations of theories which have ulta-universal models are found and general examples of ultra-universal models are investigated. In particular we show that a theory has an ultra-universal model iff it is consistent and its class of models satisfies the joint embedding property.

Colin Naturman; Henry Rose

1992-01-01

154

Accuracy of hemodialysis modeling  

Microsoft Academic Search

Accuracy of hemodialysis modeling.BackgroundOne- and two-compartmental models of hemodialysis (HD) are well known. These models make it possible to analyze the course of treatment and to predict the effect of dialysis procedures. Mathematical modeling helps physicians to match dialysis therapy to the individual needs of the patient; however, the efficiency of the models depends on the accuracy of the coefficients.

Mariusz Zió?ko; Jacek A Pietrzyk; Joanna Grabska-Chrz?stowska

2000-01-01

155

Applications of Model Selection in Credit Models  

E-print Network

Problem Goals of modeling effort · Exploratory, generating conjectures for subsequent study · Accurate. This problem may be going away? Search -- How do you find the right model? We still rely on brute force Information theory has been useful · Unified perspective that gives common ground for analysis. · Generates

Stine, Robert A.

156

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 ...

157

Geochemistry Model Validation Report: External Accumulation Model  

SciTech Connect

The purpose of this Analysis and Modeling Report (AMR) is to validate the External Accumulation Model that predicts accumulation of fissile materials in fractures and lithophysae in the rock beneath a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. (Lithophysae are voids in the rock having concentric shells of finely crystalline alkali feldspar, quartz, and other materials that were formed due to entrapped gas that later escaped, DOE 1998, p. A-25.) The intended use of this model is to estimate the quantities of external accumulation of fissile material for use in external criticality risk assessments for different types of degrading WPs: U.S. Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The scope of the model validation is to (1) describe the model and the parameters used to develop the model, (2) provide rationale for selection of the parameters by comparisons with measured values, and (3) demonstrate that the parameters chosen are the most conservative selection for external criticality risk calculations. To demonstrate the applicability of the model, a Pu-ceramic WP is used as an example. The model begins with a source term from separately documented EQ6 calculations; where the source term is defined as the composition versus time of the water flowing out of a breached waste package (WP). Next, PHREEQC, is used to simulate the transport and interaction of the source term with the resident water and fractured tuff below the repository. In these simulations the primary mechanism for accumulation is mixing of the high pH, actinide-laden source term with resident water; thus lowering the pH values sufficiently for fissile minerals to become insoluble and precipitate. In the final section of the model, the outputs from PHREEQC, are processed to produce mass of accumulation, density of accumulation, and the geometry of the accumulation zone. The density of accumulation and the geometry of the accumulation zone are calculated using a characterization of the fracture system based on field measurements made in the proposed repository (BSC 2001k). The model predicts that accumulation would spread out in a conical accumulation volume. The accumulation volume is represented with layers as shown in Figure 1. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance.

K. Zarrabi

2001-09-27

158

jModelTest: phylogenetic model averaging.  

PubMed

jModelTest is a new program for the statistical selection of models of nucleotide substitution based on "Phyml" (Guindon and Gascuel 2003. A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood. Syst Biol. 52:696-704.). It implements 5 different selection strategies, including "hierarchical and dynamical likelihood ratio tests," the "Akaike information criterion," the "Bayesian information criterion," and a "decision-theoretic performance-based" approach. This program also calculates the relative importance and model-averaged estimates of substitution parameters, including a model-averaged estimate of the phylogeny. jModelTest is written in Java and runs under Mac OSX, Windows, and Unix systems with a Java Runtime Environment installed. The program, including documentation, can be freely downloaded from the software section at http://darwin.uvigo.es. PMID:18397919

Posada, David

2008-07-01

159

Multiple model inference.  

SciTech Connect

This paper compares three approaches for model selection: classical least squares methods, information theoretic criteria, and Bayesian approaches. Least squares methods are not model selection methods although one can select the model that yields the smallest sum-of-squared error function. Information theoretic approaches balance overfitting with model accuracy by incorporating terms that penalize more parameters with a log-likelihood term to reflect goodness of fit. Bayesian model selection involves calculating the posterior probability that each model is correct, given experimental data and prior probabilities that each model is correct. As part of this calculation, one often calibrates the parameters of each model and this is included in the Bayesian calculations. Our approach is demonstrated on a structural dynamics example with models for energy dissipation and peak force across a bolted joint. The three approaches are compared and the influence of the log-likelihood term in all approaches is discussed.

Swiler, Laura Painton; Urbina, Angel

2010-07-01

160

Model Validation Status Review  

SciTech Connect

The primary objective for the Model Validation Status Review was to perform a one-time evaluation of model validation associated with the analysis/model reports (AMRs) containing model input to total-system performance assessment (TSPA) for the Yucca Mountain site recommendation (SR). This review was performed in response to Corrective Action Request BSC-01-C-01 (Clark 2001, Krisha 2001) pursuant to Quality Assurance review findings of an adverse trend in model validation deficiency. The review findings in this report provide the following information which defines the extent of model validation deficiency and the corrective action needed: (1) AMRs that contain or support models are identified, and conversely, for each model the supporting documentation is identified. (2) The use for each model is determined based on whether the output is used directly for TSPA-SR, or for screening (exclusion) of features, events, and processes (FEPs), and the nature of the model output. (3) Two approaches are used to evaluate the extent to which the validation for each model is compliant with AP-3.10Q (Analyses and Models). The approaches differ in regard to whether model validation is achieved within individual AMRs as originally intended, or whether model validation could be readily achieved by incorporating information from other sources. (4) Recommendations are presented for changes to the AMRs, and additional model development activities or data collection, that will remedy model validation review findings, in support of licensing activities. The Model Validation Status Review emphasized those AMRs that support TSPA-SR (CRWMS M&O 2000bl and 2000bm). A series of workshops and teleconferences was held to discuss and integrate the review findings. The review encompassed 125 AMRs (Table 1) plus certain other supporting documents and data needed to assess model validity. The AMRs were grouped in 21 model areas representing the modeling of processes affecting the natural and engineered barriers, plus the TSPA model itself Description of the model areas is provided in Section 3, and the documents reviewed are described in Section 4. The responsible manager for the Model Validation Status Review was the Chief Science Officer (CSO) for Bechtel-SAIC Co. (BSC). The team lead was assigned by the CSO. A total of 32 technical specialists were engaged to evaluate model validation status in the 21 model areas. The technical specialists were generally independent of the work reviewed, meeting technical qualifications as discussed in Section 5.

E.L. Hardin

2001-11-28

161

Trapped Radiation Model Uncertainties: Model-Data and Model-Model Comparisons  

NASA Technical Reports Server (NTRS)

The standard AP8 and AE8 models for predicting trapped proton and electron environments have been compared with several sets of flight data to evaluate model uncertainties. Model comparisons are made with flux and dose measurements made on various U.S. low-Earth orbit satellites (APEX, CRRES, DMSP. LDEF, NOAA) and Space Shuttle flights, on Russian satellites (Photon-8, Cosmos-1887, Cosmos-2044), and on the Russian Mir space station. This report gives the details of the model-data comparisons -- summary results in terms of empirical model uncertainty factors that can be applied for spacecraft design applications are given in a companion report. The results of model-model comparisons are also presented from standard AP8 and AE8 model predictions compared with the European Space Agency versions of AP8 and AE8 and with Russian trapped radiation models.

Armstrong, T. W.; Colborn, B. L.

2000-01-01

162

Trapped Radiation Model Uncertainties: Model-Data and Model-Model Comparisons  

NASA Technical Reports Server (NTRS)

The standard AP8 and AE8 models for predicting trapped proton and electron environments have been compared with several sets of flight data to evaluate model uncertainties. Model comparisons are made with flux and dose measurements made on various U.S. low-Earth orbit satellites (APEX, CRRES, DMSP, LDEF, NOAA) and Space Shuttle flights, on Russian satellites (Photon-8, Cosmos-1887, Cosmos-2044), and on the Russian Mir Space Station. This report gives the details of the model-data comparisons-summary results in terms of empirical model uncertainty factors that can be applied for spacecraft design applications are given in a combination report. The results of model-model comparisons are also presented from standard AP8 and AE8 model predictions compared with the European Space Agency versions of AP8 and AE8 and with Russian-trapped radiation models.

Armstrong, T. W.; Colborn, B. L.

2000-01-01

163

All models are wrong.  

PubMed

As the field of phylogeography has continued to move in the model-based direction, researchers continue struggling to construct useful models for inference. These models must be both simple enough to be tractable yet contain enough of the complexity of the natural world to make meaningful inference. Beyond constructing such models for inference, researchers explore model space and test competing models with the data on hand, with the goal of improving the understanding of the natural world and the processes underlying natural biological communities. Approximate Bayesian computation (ABC) has increased in recent popularity as a tool for evaluating alternative historical demographic models given population genetic samples. As a thorough demonstration, Pelletier & Carstens (2014) use ABC to test 143 phylogeographic submodels given geographically widespread genetic samples from the salamander species Plethodon idahoensis (Carstens et al. 2014) and, in so doing, demonstrate how the results of the ABC model choice procedure are dependent on the model set one chooses to evaluate. PMID:24931159

Hickerson, Michael J

2014-06-01

164

Marine Modeling and Analysis  

NSDL National Science Digital Library

The Marine Modeling and Analysis Branch (MMAB) of the Environmental Modeling Center is responsible for the development of improved numerical weather and marine prediction modeling systems. These models provide analysis and real-time forecast guidance on marine meteorological, oceanographic, and cryospheric parameters over the global oceans and coastal areas of the US. This site provides access to MMAB modeling tools for ocean waves (including an interactive presentation,) sea ice, marine meteorology, sea surface temperature and more. The site also features a mailing list, bibliography of publications, and information about modeling products still in the experimental and development phases.

National Centers for Environmental Prediction, National Oceanic and Atmospheric Administration

165

Nitrogen Crop Response Model  

NSDL National Science Digital Library

This on-line dynamic model from Horticulture Research International (HRI) "simulates the growth response of 25 crops to applications of nitrogen fertilizer." The model incorporates the effects of climate, organic material and leaching. Users select a region of the world, enter input into the model (e.g., crop type, date of sowing, weather conditions, nitrogen applications, etc.), and run the model for numeric and graphical output. Substantial effort has been made to describe the model's behavior and to present useful output; interested users may select the "advanced" or "detailed" options for further information on each model.

Draycott, Ann.

166

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

167

Marine Wave Model Matrix  

NSDL National Science Digital Library

The Marine Wave Model Matrix provides information on the formulation of wave models developed by the National Centers for Environmental Prediction (NCEP) and other modeling centers, including how these models forecast the generation, propagation, and dissipation of ocean waves using NWP model forecasts for winds and near-surface temperature and stability. Additionally, information is provided on data assimilation, post-processing of data, and verfication of wave models currently in operation. Within the post-processing pages are links to forecast output both in graphical and raw form, including links for data downloads. Links to COMET training on wave processes are also provided.

COMET

2006-05-16

168

Biosphere Model Report  

SciTech Connect

The purpose of this report is to document the biosphere model, the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), which describes radionuclide transport processes in the biosphere and associated human exposure that may arise as the result of radionuclide release from the geologic repository at Yucca Mountain. The biosphere model is one of the process models that support the Yucca Mountain Project (YMP) Total System Performance Assessment (TSPA) for the license application (LA), TSPA-LA. The ERMYN provides the capability of performing human radiation dose assessments. This report documents the biosphere model, which includes: (1) Describing the reference biosphere, human receptor, exposure scenarios, and primary radionuclides for each exposure scenario (Section 6.1); (2) Developing a biosphere conceptual model using site-specific features, events, and processes (FEPs) (Section 6.2), the reference biosphere (Section 6.1.1), the human receptor (Section 6.1.2), and approximations (Sections 6.3.1.4 and 6.3.2.4); (3) Building a mathematical model using the biosphere conceptual model (Section 6.3) and published biosphere models (Sections 6.4 and 6.5); (4) Summarizing input parameters for the mathematical model, including the uncertainty associated with input values (Section 6.6); (5) Identifying improvements in the ERMYN compared with the model used in previous biosphere modeling (Section 6.7); (6) Constructing an ERMYN implementation tool (model) based on the biosphere mathematical model using GoldSim stochastic simulation software (Sections 6.8 and 6.9); (7) Verifying the ERMYN by comparing output from the software with hand calculations to ensure that the GoldSim implementation is correct (Section 6.10); (8) Validating the ERMYN by corroborating it with published biosphere models; comparing conceptual models, mathematical models, and numerical results (Section 7).

D.W. Wu; A.J. Smith

2004-11-08

169

Develop a Model Component  

NASA Technical Reports Server (NTRS)

During my internship at NASA, I was a model developer for Ground Support Equipment (GSE). The purpose of a model developer is to develop and unit test model component libraries (fluid, electrical, gas, etc.). The models are designed to simulate software for GSE (Ground Special Power, Crew Access Arm, Cryo, Fire and Leak Detection System, Environmental Control System (ECS), etc. .) before they are implemented into hardware. These models support verifying local control and remote software for End-Item Software Under Test (SUT). The model simulates the physical behavior (function, state, limits and 110) of each end-item and it's dependencies as defined in the Subsystem Interface Table, Software Requirements & Design Specification (SRDS), Ground Integrated Schematic (GIS), and System Mechanical Schematic.(SMS). The software of each specific model component is simulated through MATLAB's Simulink program. The intensiv model development life cycle is a.s follows: Identify source documents; identify model scope; update schedule; preliminary design review; develop model requirements; update model.. scope; update schedule; detailed design review; create/modify library component; implement library components reference; implement subsystem components; develop a test script; run the test script; develop users guide; send model out for peer review; the model is sent out for verifictionlvalidation; if there is empirical data, a validation data package is generated; if there is not empirical data, a verification package is generated; the test results are then reviewed; and finally, the user. requests accreditation, and a statement of accreditation is prepared. Once each component model is reviewed and approved, they are intertwined together into one integrated model. This integrated model is then tested itself, through a test script and autotest, so that it can be concluded that all models work conjointly, for a single purpose. The component I was assigned, specifically, was a fluid component, a discrete pressure switch. The switch takes a fluid pressure input, and if the pressure is greater than a designated cutoff pressure, the switch would stop fluid flow.

Ensey, Tyler S.

2013-01-01

170

A future of the model organism model  

PubMed Central

Changes in technology are fundamentally reframing our concept of what constitutes a model organism. Nevertheless, research advances in the more traditional model organisms have enabled fresh and exciting opportunities for young scientists to establish new careers and offer the hope of comprehensive understanding of fundamental processes in life. New advances in translational research can be expected to heighten the importance of basic research in model organisms and expand opportunities. However, researchers must take special care and implement new resources to enable the newest members of the community to engage fully with the remarkable legacy of information in these fields. PMID:24577733

Rine, Jasper

2014-01-01

171

Modeling Guru: Knowledge Base for NASA Modelers  

NASA Astrophysics Data System (ADS)

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 accumulated expertise of NASA's scientific modeling and HEC communities. All NASA modelers and associates are encouraged to participate and provide knowledge about the models and systems so that other users may benefit from their experience. Modeling Guru is divided into a hierarchy of communities, each with its own set forums and knowledge base documents. Current modeling communities include those for space science, land and atmospheric dynamics, atmospheric chemistry, and oceanography. In addition, there are communities focused on NCCS systems, HEC tools and libraries, and programming and scripting languages. Anyone may view most of the content on Modeling Guru (available at http://modelingguru.nasa.gov/), but you must log in to post messages and subscribe to community postings. The site offers a full range of "Web 2.0" features, including discussion forums, "wiki" document generation, document uploading, RSS feeds, search tools, blogs, email notification, and "breadcrumb" links. A discussion (a.k.a. forum "thread") is used to post comments, solicit feedback, or ask questions. If marked as a question, SIVO will monitor the thread, and normally respond within a day. Discussions can include embedded images, tables, and formatting through the use of the Rich Text Editor. Also, the user can add "Tags" to their thread to facilitate later searches. The "knowledge base" is comprised of documents that are used to capture and share expertise with others. The default "wiki" document lets users edit within the browser so others can easily collaborate on the same document, even allowing the author to select those who may edit and approve the document. To maintain knowledge integrity, all documents are moderated before they are visible to the public. Modeling Guru, running on Clearspace by Jive Software, has been an active resource to the NASA modeling and HEC communities for more than a year and currently has more than 100 active users. SIVO will soon install live instant messaging support, as well as a user-customizable homepage with social-networking features. In addition, SIVO plans to implement a large dataset/file storage capability so that users can quickly and easily exchange datasets and files with one another. Continued active community participation combined with periodic software updates and improved features will ensure that Modeling Guru remains a vibrant, effective, easy-to-use tool for the NASA scientific community.

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

2009-05-01

172

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...

173

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.

174

Easily Constructed Geometric Models.  

ERIC Educational Resources Information Center

Describes how to make the following paper molecular models: trigonal prism; tetragonal pyramid; tetrahedral; and trigonal pyramid. Methodology is given for general paper model manipulation to make various shapes including a chain of tetrahedra and an icosahedron. (MVL)

Yamana, Shukichi; And Others

1988-01-01

175

A Probabilistic Reputation Model  

Microsoft Academic Search

This work introduces a probabilistic model of reputation. It is based on the fol- lowing simple consumer-provider interaction model. Consumers are assumed to order items to providers, who each have some internal, latent, \\

Francois Fouss; Youssef Achbany; Marco Saerens

176

Modeling By Example  

E-print Network

Software developers use modeling to explore design alternatives before investing in the higher costs of building the full system. Unlike constructing specific examples, constructing general models is challenging and ...

Mendel, Lucy (Lucy R.)

2007-01-01

177

Silicon Baroreceptors: Modeling Cardiovascular  

E-print Network

Silicon Baroreceptors: Modeling Cardiovascular Pressure Transduction in Analog VLSI John Lazzaro of the baroreceptors in the carotid vessel. Inspired by re- cent work in silicon models of the cochlea [3

Lazzaro, John

178

Comparison of Decision Models  

NASA Technical Reports Server (NTRS)

Two methods of multiattribute decision analysis compared in report. One method employs linear utility model. Other utilizes multiplicative utility model. Report based on interviews with experts in automotive technology to obtain their preferences regarding 10 new types of vehicles.

Feinberg, A.; Miles, J. R. F.; Smith, J. H.; Scheuer, E. M.

1986-01-01

179

Bounding Species Distribution Models  

NASA Technical Reports Server (NTRS)

Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5): 642-647, 2011].

Stohlgren, Thomas J.; Jarnevich, Cahterine S.; Morisette, Jeffrey T.; Esaias, Wayne E.

2011-01-01

180

Bounding species distribution models  

USGS Publications Warehouse

Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used. ?? 2011 Current Zoology.

Stohlgren, T.J.; Jarnevich, C.S.; Esaias, W.E.; Morisette, J.T.

2011-01-01

181

Dahl friction modeling  

E-print Network

The drive behind improved friction models has been better prediction and control of dynamic systems. The earliest model was of classical Coulomb friction; however, the discontinuity during force reversal of the Coulomb ...

Chou, Danielle, 1981-

2004-01-01

182

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 ...

183

Protein solubility modeling.  

PubMed

A thermodynamic framework (UNIQUAC model with temperature dependent parameters) is applied to model the salt-induced protein crystallization equilibrium, i.e., protein solubility. The framework introduces a term for the solubility product describing protein transfer between the liquid and solid phase and a term for the solution behavior describing deviation from ideal solution. Protein solubility is modeled as a function of salt concentration and temperature for a four-component system consisting of a protein, pseudo solvent (water and buffer), cation, and anion (salt). Two different systems, lysozyme with sodium chloride and concanavalin A with ammonium sulfate, are investigated. Comparison of the modeled and experimental protein solubility data results in an average root mean square deviation of 5.8%, demonstrating that the model closely follows the experimental behavior. Model calculations and model parameters are reviewed to examine the model and protein crystallization process. PMID:10397850

Agena, S M; Pusey, M L; Bogle, I D

1999-07-20

184

I. Introduction Simulation Modeling  

E-print Network

program, and modeling, experimentation, simulation, and programming methodologies or techniques used, experimentation technique, simulation methodology, and software engineering. Key Words and Phrases: assessment task the abilities of the traditional model- based methodologies. As reported by Roth, Gass

Tesfatsion, Leigh

185

Of Molecules and Models.  

ERIC Educational Resources Information Center

Presents an activity in which models help students visualize both the DNA process and transcription. After constructing DNA, RNA messenger, and RNA transfer molecules; students model cells, protein synthesis, codons, and RNA movement. (MDH)

Brinner, Bonnie

1992-01-01

186

SEDIMENT GEOCHEMICAL MODEL  

EPA Science Inventory

Until recently, sediment geochemical models (diagenetic models) have been only able to explain sedimentary flux and concentration profiles for a few simplified geochemical cycles (e.g., nitrogen, carbon and sulfur). However with advances in numerical methods, increased accuracy ...

187

Monte Carlo Modeling  

NSDL National Science Digital Library

Monte Carlo modeling refers to the solution of mathematical problems with the use of random numbers. This can include both function integration and the modeling of stochastic phenomena using random processes.

David Joiner

188

TMDL RUSLE MODEL  

EPA Science Inventory

We developed a simplified spreadsheet modeling approach for characterizing and prioritizing sources of sediment loadings from watersheds in the United States. A simplified modeling approach was developed to evaluate sediment loadings from watersheds and selected land segments. ...

189

PERSISTENCE IN MODEL ECOSYSTEMS  

EPA Science Inventory

Mathematical models aid in understanding environmental systems and in developing testable hypotheses relevant to the fate and ecological effects of toxic substances in such systems. Within the framework of microcosm or laboratory ecosystem modeling, some differential equation mod...

190

Learning in graphical models  

E-print Network

Statistical applications in fields such as bioinformatics, information retrieval, speech processing, image processing and communications often involve large-scale models in which thousands or millions of random variables are linked in complex ways. Graphical models provide a general methodology for approaching these problems, and indeed many of the models developed by researchers in these applied fields are instances of the general graphical model formalism. We review some of the basic ideas underlying graphical models, including the algorithmic ideas that allow graphical models to be deployed in large-scale data analysis problems. We also present examples of graphical models in bioinformatics, error-control coding and language processing. Key words and phrases: Probabilistic graphical models, junction tree algorithm, sum-product algorithm, Markov chain Monte Carlo, variational inference, bioinformatics, error-control coding.

Michael I. Jordan

2004-01-01

191

Communication system modeling  

NASA Technical Reports Server (NTRS)

This report presents the results of work on communications systems modeling and covers three different areas of modeling. The first of these deals with the modeling of signals in communication systems in the frequency domain and the calculation of spectra for various modulations. These techniques are applied in determining the frequency spectra produced by a unified carrier system, the down-link portion of the Command and Communications System (CCS). The second modeling area covers the modeling of portions of a communication system on a block basis. A detailed analysis and modeling effort based on control theory is presented along with its application to modeling of the automatic frequency control system of an FM transmitter. A third topic discussed is a method for approximate modeling of stiff systems using state variable techniques.

Holland, L. D.; Walsh, J. R., Jr.; Wetherington, R. D.

1971-01-01

192

Volumetric particle modeling  

E-print Network

This dissertation presents a robust method of modeling objects and forces for computer animation. Within this method objects and forces are represented as particles. As in most modeling systems, the movement of objects is driven by physically based...

Dingle, Brent Michael

2007-09-17

193

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.

American Museum of Natural History

2012-06-26

194

METEOROLOGICAL AND TRANSPORT MODELING  

EPA Science Inventory

Advanced air quality simulation models, such as CMAQ, as well as other transport and dispersion models, require accurate and detailed meteorology fields. These meteorology fields include primary 3-dimensional dynamical and thermodynamical variables (e.g., winds, temperature, mo...

195

How Mesoscale Models Work  

NSDL National Science Digital Library

The goal of this training module is to help you increase your understanding of how mesoscale models work. Such understanding, in turn, can help you more efficiently and accurately evaluate model-generated forecast products.

COMET

2002-04-22

196

Protein solubility modeling  

NASA Technical Reports Server (NTRS)

A thermodynamic framework (UNIQUAC model with temperature dependent parameters) is applied to model the salt-induced protein crystallization equilibrium, i.e., protein solubility. The framework introduces a term for the solubility product describing protein transfer between the liquid and solid phase and a term for the solution behavior describing deviation from ideal solution. Protein solubility is modeled as a function of salt concentration and temperature for a four-component system consisting of a protein, pseudo solvent (water and buffer), cation, and anion (salt). Two different systems, lysozyme with sodium chloride and concanavalin A with ammonium sulfate, are investigated. Comparison of the modeled and experimental protein solubility data results in an average root mean square deviation of 5.8%, demonstrating that the model closely follows the experimental behavior. Model calculations and model parameters are reviewed to examine the model and protein crystallization process. Copyright 1999 John Wiley & Sons, Inc.

Agena, S. M.; Pusey, M. L.; Bogle, I. D.

1999-01-01

197

Mathematical circulatory system model  

NASA Technical Reports Server (NTRS)

A system and method of modeling a circulatory system including a regulatory mechanism parameter. In one embodiment, a regulatory mechanism parameter in a lumped parameter model is represented as a logistic function. In another embodiment, the circulatory system model includes a compliant vessel, the model having a parameter representing a change in pressure due to contraction of smooth muscles of a wall of the vessel.

Lakin, William D. (Inventor); Stevens, Scott A. (Inventor)

2010-01-01

198

Hierarchical Bass model  

NASA Astrophysics Data System (ADS)

We propose a new model about diffusion of a product which includes a memory of how many adopters or advertisements a non-adopter met, where (non-)adopters mean people (not) possessing the product. This effect is lacking in the Bass model. As an application, we utilize the model to fit the iPod sales data, and so the better agreement is obtained than the Bass model.

Tashiro, Tohru

2014-03-01

199

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

200

Modeling the Solar Chromosphere  

E-print Network

Spectral diagnostic features formed in the solar chromosphere are few and difficult to interpret -- they are neither formed in the optically thin regime nor in local thermodynamic equilibrium (LTE). To probe the state of the chromosphere, both from observations and theory, it is therefore necessary with modeling. I discuss both traditional semi-empirical modeling, numerical experiments illustrating important ingredients necessary for a self-consistent theoretical modeling of the solar chromosphere and the first results of such models.

M. Carlsson

2007-04-11

201

Lagrangian helicopter model  

Microsoft Academic Search

\\u000a There is a growing interest in the construction and control of autonomous model helicopters [47, 90]. Recently, a number of\\u000a authors from the control community have begun to investigate an integrated non-linear dynamic model of a scale model autonomous\\u000a helicopter (cf. conference papers [28, 62, 95, 101, 119] and more recently the jounal papers [93, 102]). Model helicopters\\u000a display a

Isabelle Fantoni; Rogelio Lozano

202

Introduction to Ocean Models  

NSDL National Science Digital Library

Oceans cover over 70% of the surface of the earth, yet many details of their workings are not fully understood. To better understand and forecast the state of the ocean, we rely on numerical ocean models. Ocean models combine observations and physics to predict the ocean temperature, salinity, and currents at any time and any place across the ocean basins. This module will discuss what goes into numerical ocean models, including model physics, coordinate systems, parameterization, initialization, and boundary conditions.

COMET

2007-08-06

203

Model documention: Commercial Sector Energy Model. [CSEM  

SciTech Connect

The CSEM forecasts floorspace area and demand for natural gas, electricity and fuel oil for six building categories in four Census regions. Real disposable personal income, population and real fuel prices are the major exogenous drivers of these forecasts. The commercial model uses the coefficients from the three econometric submodules to calculate building floorspace, end-use fuel choices, and utilization (enegy use per square foot) for the three major fuels. Separately from these structural components the model also calculates energy use for the minor fuels liquefied petroleum gas, kerosene, coal and motor gasoline. Through the use of accounting equations, the commercial model combines the structural components to get total commercial energy use over the major fuels. It then adds in the minor fuels, passes the information back to the other models and writes reports.

Not Available

1984-08-10

204

Aerosol Modeling for the Global Model Initiative  

NASA Technical Reports Server (NTRS)

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 the two institutions as starting points. The GMI aerosol model will be tested, evaluated against observations, and then applied to assessment of the effects of aircraft sulfur emissions as needed by the NASA Subsonic Assessment in 2001. The work includes the following tasks: 1. Implementation of the sulfur cycle within GMI, including sources, sinks, and aqueous conversion of sulfur. Aerosol modules will be added as they are developed and the GMI schedule permits. 2. Addition of aerosol types other than sulfate particles, including dust, soot, organic carbon, and black carbon. 3. Development of new and more efficient parameterizations for treating sulfate aerosol nucleation, condensation, and coagulation among different particle sizes and types.

Weisenstein, Debra K.; Ko, Malcolm K. W.

2001-01-01

205

Model reduction for Hidden Markov models  

E-print Network

The contribution of this thesis is the development of tractable computational methods for reducing the complexity of two classes of dynamical systems, finite alphabet Hidden Markov Models and Jump Linear Systems with finite ...

Kotsalis, Georgios

2006-01-01

206

3 Human vs. model 2 Salience model  

E-print Network

4 Contour model Robert J. Peters (1), T. Nathan Mundhenk (2), Laurent Itti (2), and Christof Koch (1 Winner-take-all Inhibition of return Attended location adapted from Itti&Koch (2001), Nat. Rev. Neurosci

Peters, Rob

207

Continuous Growth Models  

NSDL National Science Digital Library

This worksheet compares user-input growth data with predictions under linear, exponential, and logistic models of growth. Students can input parameters for each model; the program graphs the results and computes a crude goodness-of-fit measure. Introduces concepts of modeling and statistical analysis that can be more thoroughly explored using standard statistics software (JMP, SAS, etc.)

Tony Weisstein (Truman State University; Biology)

2005-12-16

208

Phyloclimatic Modelling Workshop  

E-print Network

– from ice cores Palaeohistory • Fossil history – Mostly pollen • Geological record – Continental drift – Climate • Computer models – Climate Alastair Culham Gathering the evidence • Fossil history is generally poor and patchy even in the best recorded... climate models? • Modelling here relies on: – Knowing continental positions – Knowing altitudes – Knowing sea levels – Knowing atmospheric gas concentrations • This can be validated against fossil evidence – Pollen/macrofossils – ‘Fossil’ atmospheres...

Yesson, Christopher

2012-11-13

209

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

210

Textile composites: modelling strategies  

Microsoft Academic Search

Textile materials are characterised by the distinct hierarchy of structure, which should be represented by a model of textile geometry and mechanical behaviour. In spite of a profound investigation of textile materials and a number of theoretical models existing in the textile literature for different structures, a model covering all structures typical for composite reinforcements is not available. Hence the

S. V. Lomov; G. Huysmans; Y. Luo; R. S. Parnas; A. Prodromou; I. Verpoest; F. R. Phelan

2001-01-01

211

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 4 Prof. Dr. Benedikt L¨owe Reasoning and Formal Modelling for Forensic Science Lecture 4 Prof. Dr. Benedikt L¨owe 2nd Semester 2010/11 #12;Reasoning and Formal Modelling for Forensic Science Lecture 4 Prof. Dr. Benedikt L¨owe Where are we right

Löwe, Benedikt

212

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 6 Prof. Dr. Benedikt L¨owe Reasoning and Formal Modelling for Forensic Science Lecture 6 Prof. Dr. Benedikt L¨owe 2nd Semester 2010/11 #12;Reasoning and Formal Modelling for Forensic Science Lecture 6 Prof. Dr. Benedikt L¨owe Reminder: Controlled

Löwe, Benedikt

213

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 12 Prof. Dr. Benedikt L¨owe Reasoning and Formal Modelling for Forensic Science Lecture 12 Prof. Dr. Benedikt L¨owe 2nd Semester 2010/11 #12;Reasoning and Formal Modelling for Forensic Science Lecture 12 Prof. Dr. Benedikt L¨owe Plan for today. #12

Löwe, Benedikt

214

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 5 Prof. Dr. Benedikt L¨owe Reasoning and Formal Modelling for Forensic Science Lecture 5 Prof. Dr. Benedikt L¨owe 2nd Semester 2010/11 #12;Reasoning and Formal Modelling for Forensic Science Lecture 5 Prof. Dr. Benedikt L¨owe Reminder: Controlled

Löwe, Benedikt

215

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 10 Prof. Dr. Benedikt L¨owe Reasoning and Formal Modelling for Forensic Science Lecture 10 Prof. Dr. Benedikt L¨owe 2nd Semester 2010/11 #12;Reasoning and Formal Modelling for Forensic Science Lecture 10 Prof. Dr. Benedikt L¨owe A reminder from

Löwe, Benedikt

216

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 3 Prof. Dr. Benedikt L¨owe Reasoning and Formal Modelling for Forensic Science Lecture 3 Prof. Dr. Benedikt L¨owe 2nd Semester 2010/11 #12;Reasoning and Formal Modelling for Forensic Science Lecture 3 Prof. Dr. Benedikt L¨owe Binary connectives

Löwe, Benedikt

217

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

218

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 can…

Thornton, Bradley D.; Smalley, Robert A.

2008-01-01

219

Models of Earth  

NSDL National Science Digital Library

In this activity, candy models are used to demonstrate the features of the Earth, including its internal structure and layers. Students learn why models are essential in Earth science and answer questions about how their candy models do and do not compare with the actual Earth.

Nicole LaDue

220

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

221

Modeling Wine Fermentation  

NSDL National Science Digital Library

Humans have been producing wines for thousands of years. How did wine making get started? How has it changed? The Wine Mini-Model simulation enables us to explore the basic fermentation process as well as model enhancements such as the higher alcohol tolerance of cultivated yeasts used in modern wine making. * model the fermentation process in early and modern wines

Ethel D. Stanley (Beloit College; Biology)

2006-05-20

222

Modeling for Tsunami Forecast  

E-print Network

Modeling for Tsunami Forecast Vasily Titov NOAA Center for Tsunami Research Pacific Marine Environmental Laboratory Seattle, WA #12;Outline Tsunami Modeling Development Toward Real- time Tsunami Forecast Challenges Modeling development in 1990 -2000 Short-term Inundation Forecast for Tsunamis Forecast system

223

Global Timber Model (GTM)  

EPA Science Inventory

GTM 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 harvests in industrial fore...

224

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.

2012-06-26

225

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.

John Nielsen-Gammon

1996-01-01

226

Rock Properties Model  

SciTech Connect

The purpose of this model report is to document the Rock Properties Model version 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 model provides mean matrix and lithophysae porosity, and the cross-correlated mean bulk density as direct input to the ''Saturated Zone Flow and Transport Model Abstraction'', MDL-NBS-HS-000021, REV 02 (BSC 2004 [DIRS 170042]). The constraints, caveats, and limitations associated with this model are discussed in Section 6.6 and 8.2. Model validation accomplished by corroboration with data not cited as direct input is discussed in Section 7. The revision of this model report was performed as part of activities being conducted under the ''Technical Work Plan for: The Integrated Site Model, Revision 05'' (BSC 2004 [DIRS 169635]). The purpose of this revision is to bring the report up to current procedural requirements and address the Regulatory Integration Team evaluation comments. The work plan describes the scope, objectives, tasks, methodology, and procedures for this process.

C. Lum

2004-09-16

227

Empirical Bayes Linear Models  

E-print Network

Empirical Bayes Will Penny Linear Models fMRI analysis Gradient Ascent Online learning Delta Rule Newton Method Bayesian Linear Models MAP Learning MEG Source Reconstruction Empirical Bayes Model Maximum Likelihood Augmented Form ReML Objective Function References Empirical Bayes Will Penny 3rd March

Penny, Will

228

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

229

Models for Products  

ERIC Educational Resources Information Center

This paper explores how models can support productive thinking. For us a model is a "thing", a tool to help make sense of something. We restrict attention to specific models for whole-number multiplication, hence the wording of the title. They support evolving thinking in large measure through the ways their users redesign them. They assume new…

Speiser, Bob; Walter, Chuck

2011-01-01

230

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

231

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...

232

QUALITATIVE ECOLOGICAL MODELING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Students construct qualitative models of an ecosystem and use the models to evaluate the direct and indirect effects that may result from perturbations to the ecosystem. Qualitative modeling is described for use in two procedures, each with different educational goals and student backgrounds in min...

233

Fraction Model III  

NSDL National Science Digital Library

This tool allows the individual or the classroom to explore several representations of fractions. After selecting numerator and denominator, any number from 1 to 100, learners see the fraction itself, a visual model, as well as decimal and percent equivalents. They can choose the model to be a circle, a rectangle, or a set model.

NCTM Illuminations

2000-01-01

234

Fraction Model II  

NSDL National Science Digital Library

With this tool, students can explore different representations for fractions. They can create a fraction, selecting any numerator or denominator up to 20, and see a model of the fraction as well as its percent and decimal equivalents. For the model, they can choose either a circle, a rectangle, or a set model.

NCTM Illuminations

2000-01-01

235

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

1998-01-01

236

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

237

Modeling Earnings Dynamics  

Microsoft Academic Search

In this paper we use indirect inference to estimate a joint model of earnings, employment, job changes, wage rates, and work hours over a career. Our model incorporates duration dependence in several variables, multiple sources of unobserved heterogeneity, job-specific error components in both wages and hours, and measurement error. We use the model to address a number of important questions

Joseph G. Altonji; Anthony Smith; Ivan Vidangos

2009-01-01

238

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

239

The Java memory model  

Microsoft Academic Search

This paper describes the new Java memory model, which has been revised as part of Java 5.0. The model specifies the legal behaviors for a multithreaded program; it defines the semantics of multithreaded Java programs and partially determines legal implementations of Java virtual machines and compilers.The new Java model provides a simple interface for correctly synchronized programs -- it guarantees

Jeremy Manson; William Pugh; Sarita V. Adve

2005-01-01

240

Model Breaking Points Conceptualized  

ERIC Educational Resources Information Center

Current curriculum initiatives (e.g., National Governors Association Center for Best Practices and Council of Chief State School Officers 2010) advocate that models be used in the mathematics classroom. However, despite their apparent promise, there comes a point when models break, a point in the mathematical problem space where the model cannot,…

Vig, Rozy; Murray, Eileen; Star, Jon R.

2014-01-01

241

Modeling ocean deep convection  

Microsoft Academic Search

The goal of this study is to assess models for Deep Convection with special emphasis on their use in coarse resolution ocean general circulation models. A model for deep convection must contain both vertical transport and lateral advection by mesoscale eddies generated by baroclinic instabilities. The first process operates mostly in the initial phases while the second dominates the final

V. M. Canuto; A. Howard; P. Hogan; Y. Cheng; M. S. Dubovikov; L. M. Montenegro

2004-01-01

242

Peacekeeper tank slosh model  

NASA Technical Reports Server (NTRS)

Information on a tank slosh model for Peacekeeper missiles is given in viewgraph form. Allowable vehicle errors for nose cone ejection clearance, vehicle maneuver sloshing problems, slosh/moment prediction, slosh surface specification, code validation, experimental model-computational model comparison and the propellant storage assembly are covered.

Schwartz, Sidney H.

1987-01-01

243

A Model Chemistry Class.  

ERIC Educational Resources Information Center

Described is an activity which uses a 96-well reaction plate and soda straws to construct a model of the periodic table of the elements. The model illustrates the ionization energies of the various elements. Construction of the model and related concepts are discussed. (CW)

Summerlin, Lee; Borgford, Christie

1989-01-01

244

Scoring hidden Markov models  

Microsoft Academic Search

Motivation: Statistical sequence comparison techniques, such as hidden Markov models and generalized profiles, calculate the probability that a sequence was generated by a given model. Log-odds scoring is a means of evaluating this probability by comparing it to a null hypothesis, usually a simpler statistical model intended to represent the universe of sequences as a whole, rather than the group

Christian Barrett; Richard Hughey; Kevin Karplus

1997-01-01

245

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...

246

Geometric Modelling Dagstuhl 2002  

E-print Network

, simulation, and medical imaging, and it attracts researchers with backgrounds in computer science as well, Houston Editorial Geometric Modeling is the branch of Computer Science concerned with the efficient to the following diverse topics: · curve and surface modeling · non-manifold modeling in CAD · multiresolution

Hahmann, Stefanie

247

The Constructivist Learning Model  

NSDL National Science Digital Library

Much cognitive science research has been used to support a new model of learning. This most promising new model is called the Constructivist Learning Model (CLM). Russell Yeany (University of Georgia) has called CLM the most exciting idea of the past 50 y

Robert E. Yager

2000-01-01

248

IMAGE Satellite Scale Model  

NSDL National Science Digital Library

This is an activity about scale model building. Learners will use mathematics to determine the scale model size, construct a pattern, and build a paper scale model of the IMAGE (Imager for Magnetopause-to-Aurora Global Exploration) satellite, the first satellite mission to image the Earth's magnetosphere. This is the second activity in the Solar Storms and You: Exploring Satellite Design educator guide.

2012-08-03

249

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

250

Stochastic Complexity and Modeling  

Microsoft Academic Search

As a modification of the notion of algorithmic complexity, the stochastic complexity of a string of data, relative to a class of probabilistic models, is defined to be the fewest number of binary digits with which the data can be encoded by taking advantage of the selected models. The computation of the stochastic complexity produces a model, which may be

Jorma Rissanen

1986-01-01

251

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.

252

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

253

MATHEMATICAL MODELS IN EPIDEMIOLOGY  

Microsoft Academic Search

Summary This paper provides an overview of the use of mathematical models to explain the epidemiology of infectious diseases, and to assess the potential benefits of proposed control strategies. The development is broadly historical: beginning with the concept of mass action and compartmental models; proceeding through models for vector-born infections with special reference to malaria; touching on ideas arising in

M. G. Roberts

254

Incinerator model uses Lotus  

Microsoft Academic Search

To evaluate proposed incineration systems, designers, operators, and regulatory personnel have had to resort to general computerized combustion models. These, however, have only limited application to incinerators. This article describes one way to build a computerized model specially designed for incinerators. If the model is built to cover a wide spectrum of incinerator applications, it can provide a consistent means

1987-01-01

255

PESTICIDE ROOT ZONE MODEL  

EPA Science Inventory

PRZM3 is a modeling system that links two subordinate models - PRZM and VADOFT to predict pesticide transport and transformation down through the crop root and unsaturated zone. PRZM3 includes modeling capabilities for such phenomena as soil temperature simulation, vo...

256

Succession Model Landscape Stochasticity  

E-print Network

100 1000 10000 patch sizes birth rate both Disturbance Model Landscape Stochasticity Low Control High" accomplished by incrementing the patch birth rate (Control: s = a = 10) A simple model of species viabilitySuccession Model Landscape Stochasticity Low Control High Very High ThresholdMultiplier 0.1 1 10

257

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

258

Generalized Latent Trait Models.  

ERIC Educational Resources Information Center

Discusses a general model framework within which manifest variables with different distributions in the exponential family can be analyzed with a latent trait model. Presents a unified maximum likelihood method for estimating the parameters of the generalized latent trait model and discusses the scoring of individuals on the latent dimensions.…

Moustaki, Irini; Knott, Martin

2000-01-01

259

Models, Norms and Sharing.  

ERIC Educational Resources Information Center

To investigate the effect of modeling on altruism, 156 third and fifth grade children were exposed to a model who either shared with them, gave to a charity, or refused to share. The test apparatus, identified as a game, consisted of a box with signal lights and a chute through which marbles were dispensed. Subjects and the model played the game…

Harris, Mary B.

260

Modeling Climate Dynamically  

ERIC Educational Resources Information Center

A dynamical systems approach to energy balance models of climate is presented, focusing on low order, or conceptual, models. Included are global average and latitude-dependent, surface temperature models. The development and analysis of the differential equations and corresponding bifurcation diagrams provides a host of appropriate material for…

Walsh, Jim; McGehee, Richard

2013-01-01

261

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...

262

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

263

Ocean-Modeling.org  

NSDL National Science Digital Library

The purpose of this web site is to facilitate the development and testing of the Terrain-following Ocean Modeling System (TOMS) and to provide a forum to the ocean community at large. The site provides an explanation of three-dimensional modeling, as well as an overview of the four primary types of ocean modeling methods currently in use and links to labs around the country using these modeling techniques. A collection of links to freely downloadable ocean modeling tools is provided. The site also includes links to data sources, publications, bulletin boards, chat rooms and other relevant sites.

Ocean-Modeling.org

264

Complex matrix model duality  

SciTech Connect

The same complex matrix model calculates both tachyon scattering for the c=1 noncritical string at the self-dual radius and certain correlation functions of operators which preserve half the supersymmetry in N=4 super-Yang-Mills theory. It is dual to another complex matrix model where the couplings of the first model are encoded in the Kontsevich-like variables of the second. The duality between the theories is mirrored by the duality of their Feynman diagrams. Analogously to the Hermitian Kontsevich-Penner model, the correlation functions of the second model can be written as sums over discrete points in subspaces of the moduli space of punctured Riemann surfaces.

Brown, T. W. [DESY, Hamburg, Theory Group, Notkestrasse, 85, D-22603 Hamburg (Germany)

2011-04-15

265

Reconstruction of Inflation Models  

E-print Network

In this paper, we reconstruct viable inflationary models by starting from spectral index and tensor-to-scalar ratio from Planck observations. We analyze three different kinds of models: scalar field theories, fluid cosmology and f(R)-modified gravity. We recover the well known R^2-inflation in Jodan frame and Einstein frame representation, the massive scalar inflaton models and two models of inhomogeneous fluid. A model of R^2-correction to Einstein's gravity plus a "cosmological constant" with an exact solution for early time acceleration is reconstructed.

Myrzakulov, Ratbay; Zerbini, Sergio

2015-01-01

266

Weather Station Model  

NSDL National Science Digital Library

This lesson instructs students on how to read station models, the symbols used on weather maps to show data (temperature, wind speed and direction, barometeric pressure, etc.) for a given reporting station. It includes a diagram of a station model, an explanation of the data conveyed by the numbers and symbols, and a table of definitions for the graphic symbols used with models. There is also a set of interactive station models students can use for practice at interpretation, and an interactive exercise in which students use real-time weather data to interpret models.

267

A Generalized Higgs Model  

E-print Network

The Higgs model is generalized so that in addition to the radial Higgs field there are fields which correspond to the themasy and entropy. The model is further generalized to include state and sign parameters. A reduction to the standard Higgs model is given and how to break symmetry using a non-zero VEV (vacuum expectation value) is shown. A 'fluid rotation' can be performed on the standard Higgs model to give a model dependant on the entropy and themasy and with a constant mass.

Mark D. Roberts

2003-12-14

268

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

269

TEAMS Model Analyzer  

NASA Technical Reports Server (NTRS)

The TEAMS model analyzer is a supporting tool developed to work with models created with TEAMS (Testability, Engineering, and Maintenance System), which was developed by QSI. In an effort to reduce the time spent in the manual process that each TEAMS modeler must perform in the preparation of reporting for model reviews, a new tool has been developed as an aid to models developed in TEAMS. The software allows for the viewing, reporting, and checking of TEAMS models that are checked into the TEAMS model database. The software allows the user to selectively model in a hierarchical tree outline view that displays the components, failure modes, and ports. The reporting features allow the user to quickly gather statistics about the model, and generate an input/output report pertaining to all of the components. Rules can be automatically validated against the model, with a report generated containing resulting inconsistencies. In addition to reducing manual effort, this software also provides an automated process framework for the Verification and Validation (V&V) effort that will follow development of these models. The aid of such an automated tool would have a significant impact on the V&V process.

Tijidjian, Raffi P.

2010-01-01

270

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

271

A model of strength  

USGS Publications Warehouse

In her AAAS News & Notes piece "Can the Southwest manage its thirst?" (26 July, p. 362), K. Wren quotes Ajay Kalra, who advocates a particular method for predicting Colorado River streamflow "because it eschews complex physical climate models for a statistical data-driven modeling approach." A preference for data-driven models may be appropriate in this individual situation, but it is not so generally, Data-driven models often come with a warning against extrapolating beyond the range of the data used to develop the models. When the future is like the past, data-driven models can work well for prediction, but it is easy to over-model local or transient phenomena, often leading to predictive inaccuracy (1). Mechanistic models are built on established knowledge of the process that connects the response variables with the predictors, using information obtained outside of an extant data set. One may shy away from a mechanistic approach when the underlying process is judged to be too complicated, but good predictive models can be constructed with statistical components that account for ingredients missing in the mechanistic analysis. Models with sound mechanistic components are more generally applicable and robust than data-driven models.

Johnson, Douglas H.; Cook, R.D.

2013-01-01

272

Animal models of atherosclerosis  

PubMed Central

In this mini-review several commonly used animal models of atherosclerosis have been discussed. Among them, emphasis has been made on mice, rabbits, pigs and non-human primates. Although these animal models have played a significant role in our understanding of induction of atherosclerotic lesions, we still lack a reliable animal model for regression of the disease. Researchers have reported several genetically modified and transgenic animal models that replicate human atherosclerosis, however each of current animal models have some limitations. Among these animal models, the apolipoprotein (apo) E-knockout (KO) mice have been used extensively because they develop spontaneous atherosclerosis. Furthermore, atherosclerotic lesions developed in this model depending on experimental design may resemble humans’ stable and unstable atherosclerotic lesions. This mouse model of hypercholesterolemia and atherosclerosis has been also used to investigate the impact of oxidative stress and inflammation on atherogenesis. Low density lipoprotein (LDL)-r-KO mice are a model of human familial hypercholesterolemia. However, unlike apo E-KO mice, the LDL-r-KO mice do not develop spontaneous atherosclerosis. Both apo E-KO and LDL-r-KO mice have been employed to generate other relevant mouse models of cardiovascular disease through breeding strategies. In addition to mice, rabbits have been used extensively particularly to understand the mechanisms of cholesterol-induced atherosclerosis. The present review paper details the characteristics of animal models that are used in atherosclerosis research. PMID:24868511

Kapourchali, Fatemeh Ramezani; Surendiran, Gangadaran; Chen, Li; Uitz, Elisabeth; Bahadori, Babak; Moghadasian, Mohammed H

2014-01-01

273

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 for soybean, but not as well for maize. CLM-Crop yields were comparable with observations in countries such as the United States, Argentina, and China, 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 agreement with other modeling studies. 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.

2013-04-01

274

Multiscale Modeling of Recrystallization  

SciTech Connect

We propose a multi length scale approach to modeling recrystallization which links a dislocation model, a cell growth model and a macroscopic model. Although this methodology and linking framework will be applied to recrystallization, it is also applicable to other types of phase transformations in bulk and layered materials. Critical processes such as the dislocation structure evolution, nucleation, the evolution of crystal orientations into a preferred texture, and grain size evolution all operate at different length scales. In this paper we focus on incorporating experimental measurements of dislocation substructures, rnisorientation measurements of dislocation boundaries, and dislocation simulations into a mesoscopic model of cell growth. In particular, we show how feeding information from the dislocation model into the cell growth model can create realistic initial microstructure.

Godfrey, A.W.; Holm, E.A.; Hughes, D.A.; Lesar, R.; Miodownik, M.A.

1998-12-07

275

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

276

Toward Scientific Numerical Modeling  

NASA Technical Reports Server (NTRS)

Ultimately, scientific numerical models need quantified output uncertainties so that modeling can evolve to better match reality. Documenting model input uncertainties and verifying that numerical models are translated into code correctly, however, are necessary first steps toward that goal. Without known input parameter uncertainties, model sensitivities are all one can determine, and without code verification, output uncertainties are simply not reliable. To address these two shortcomings, two proposals are offered: (1) an unobtrusive mechanism to document input parameter uncertainties in situ and (2) an adaptation of the Scientific Method to numerical model development and deployment. Because these two steps require changes in the computational simulation community to bear fruit, they are presented in terms of the Beckhard-Harris-Gleicher change model.

Kleb, Bil

2007-01-01

277

Minimal quiver standard model  

SciTech Connect

This paper discusses the minimal quiver gauge theory embedding of the standard model that could arise from brane world type string theory constructions. It is based on the low energy effective field theory of D branes in the perturbative regime. The model differs from the standard model by the addition of one extra massive gauge boson, and contains only one additional parameter to the standard model: the mass of this new particle. The coupling of this new particle to the standard model is uniquely determined by input from the standard model and consistency conditions of perturbative string theory. We also study some aspects of the phenomenology of this model and bounds on its possible observation at the Large Hadron Collider.

Berenstein, David; Pinansky, Samuel [Department of Physics, University of California at Santa Barbara, California 93106 (United States)

2007-05-01

278

Ventilation Model Report  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. Revision 01 ICN 01 included the results of the unqualified software code MULTIFLUX to assess the influence of moisture on the ventilation efficiency. The purposes of Revision 02 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To asses the impacts of moisture on the ventilation efficiency.

V. Chipman; J. Case

2002-12-20

279

Michel Verleysen Non-linear models and model selection for spectral data -1 Non-linear models and model selection  

E-print Network

1 Michel Verleysen Non-linear models and model selection for spectral data - 1 Non-linear models-la-Neuve, Belgium) November 2002 Michel Verleysen Non-linear models and model selection for spectral data - 2 250 Another fine wine #12;2 Michel Verleysen Non-linear models and model selection for spectral data

Verleysen, Michel

280

Bayesian Model Bayes rule for  

E-print Network

Bayesian Model Comparison Will Penny Bayes rule for models Bayes factors Nonlinear Models Model Comparison Will Penny June 2nd 2011 #12;Bayesian Model Comparison Will Penny Bayes rule for models Bayes factors Nonlinear Models Variational Laplace Free Energy Complexity Decompositions AIC and BIC

Penny, Will

281

Model management systems: A survey  

Microsoft Academic Search

This paper provides a survey of model management literature within the mathematical modeling domain. The first part of the survey is a review and a summary of the literature. After giving some basic definitions of modeling, modeling life cycle, and model management, two representative algebraic modeling languages followed by three approaches to modeling are introduced. These approaches are database, graph-based,

Anandhi Bharadwaj; Joobin Choobineh; Amber Lo; Bala Shetty

1992-01-01

282

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

283

Constitutive models in LAME.  

SciTech Connect

The Library of Advanced Materials for Engineering (LAME) provides a common repository for constitutive models that can be used in computational solid mechanics codes. A number of models including both hypoelastic (rate) and hyperelastic (total strain) constitutive forms have been implemented in LAME. The structure and testing of LAME is described in Scherzinger and Hammerand ([3] and [4]). The purpose of the present report is to describe the material models which have already been implemented into LAME. The descriptions are designed to give useful information to both analysts and code developers. Thus far, 33 non-ITAR/non-CRADA protected material models have been incorporated. These include everything from the simple isotropic linear elastic models to a number of elastic-plastic models for metals to models for honeycomb, foams, potting epoxies and rubber. A complete description of each model is outside the scope of the current report. Rather, the aim here is to delineate the properties, state variables, functions, and methods for each model. However, a brief description of some of the constitutive details is provided for a number of the material models. Where appropriate, the SAND reports available for each model have been cited. Many models have state variable aliases for some or all of their state variables. These alias names can be used for outputting desired quantities. The state variable aliases available for results output have been listed in this report. However, not all models use these aliases. For those models, no state variable names are listed. Nevertheless, the number of state variables employed by each model is always given. Currently, there are four possible functions for a material model. This report lists which of these four methods are employed in each material model. As far as analysts are concerned, this information is included only for the awareness purposes. The analyst can take confidence in the fact that model has been properly implemented and the methods necessary for achieving accurate and efficient solutions have been incorporated. The most important method is the getStress function where the actual material model evaluation takes place. Obviously, all material models incorporate this function. The initialize function is included in most material models. The initialize function is called once at the beginning of an analysis and its primary purpose is to initialize the material state variables associated with the model. Many times, there is some information which can be set once per load step. For instance, we may have temperature dependent material properties in an analysis where temperature is prescribed. Instead of setting those parameters at each iteration in a time step, it is much more efficient to set them once per time step at the beginning of the step. These types of load step initializations are performed in the loadStepInit method. The final function used by many models is the pcElasticModuli method which changes the moduli that are to be used by the elastic preconditioner in Adagio. The moduli for the elastic preconditioner are set during the initialization of Adagio. Sometimes, better convergence can be achieved by changing these moduli for the elastic preconditioner. For instance, it typically helps to modify the preconditioner when the material model has temperature dependent moduli. For many material models, it is not necessary to change the values of the moduli that are set initially in the code. Hence, those models do not have pcElasticModuli functions. All four of these methods receive information from the matParams structure as described by Scherzinger and Hammerand.

Hammerand, Daniel Carl; Scherzinger, William Mark

2007-09-01

284

Introduction to Climate Models  

NSDL National Science Digital Library

This module explains how climate models work. Because the modeling of both weather and climate share many similarities, the content throughout this module draws frequent comparisons and highlights the differences. We explain not only how, but why climate models differ from weather models. To do so, we explore the difference between weather and climate, then show how models are built to simulate climate and generate the statistics that describe it. We conclude with a discussion of models are tuned and tested. Understanding how climate responds to changes in atmospheric composition and other factors drives climate research. Climate models provide a tool to understand how processes work and interact with each other. Our intended audience is the weather forecasting community: those who are already familiar with NWP models. Non-forecasters with an interest in weather and climate should also find the module useful. The content is not overly technical and the goal of this module is not to train people to develop climate models but to highlight the similarities and differences between weather and climate models.

2014-09-14

285

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

286

The Earth System Model  

NASA Technical Reports Server (NTRS)

The Earth System Model is the natural evolution of current climate models and will be the ultimate embodiment of our geophysical understanding of the planet. These models are constructed from components - atmosphere, ocean, ice, land, chemistry, solid earth, etc. models and merged together through a coupling program which is responsible for the exchange of data from the components. Climate models and future earth system models will have standardized modules, and these standards are now being developed by the ESMF project funded by NASA. The Earth System Model will have a variety of uses beyond climate prediction. The model can be used to build climate data records making it the core of an assimilation system, and it can be used in OSSE experiments to evaluate. The computing and storage requirements for the ESM appear to be daunting. However, the Japanese ES theoretical computing capability is already within 20% of the minimum requirements needed for some 2010 climate model applications. Thus it seems very possible that a focused effort to build an Earth System Model will achieve succcss.

Schoeberl, Mark; Rood, Richard B.; Hildebrand, Peter; Raymond, Carol

2003-01-01

287

Introduction: reminiscing on models and modeling.  

PubMed

This chapter answers three basic questions, which are: (1) Why build models, (2) why build models of fragile X syndrome, and (3) what has been learned from the models of fragile X syndrome that have been made? The first question is used to frame the other two questions, providing the appropriate context by which the rest of the book should be examined. Of necessity the last two questions are only addressed briefly, and from one man's point of view, as they contain the subject matter of the entirety of the book. Thus, the reader is introduced to the various topics under review and urged to read for him/herself their contents, drawing such conclusions as he/she thinks are warranted. PMID:22009344

Denman, Robert B

2012-01-01

288

Radiation Environment Modeling for Spacecraft Design: New Model Developments  

NASA Technical Reports Server (NTRS)

A viewgraph presentation on various new space radiation environment models for spacecraft design is described. The topics include: 1) The Space Radiatio Environment; 2) Effects of Space Environments on Systems; 3) Space Radiatio Environment Model Use During Space Mission Development and Operations; 4) Space Radiation Hazards for Humans; 5) "Standard" Space Radiation Environment Models; 6) Concerns about Standard Models; 7) Inadequacies of Current Models; 8) Development of New Models; 9) New Model Developments: Proton Belt Models; 10) Coverage of New Proton Models; 11) Comparison of TPM-1, PSB97, AP-8; 12) New Model Developments: Electron Belt Models; 13) Coverage of New Electron Models; 14) Comparison of "Worst Case" POLE, CRESELE, and FLUMIC Models with the AE-8 Model; 15) New Model Developments: Galactic Cosmic Ray Model; 16) Comparison of NASA, MSU, CIT Models with ACE Instrument Data; 17) New Model Developmemts: Solar Proton Model; 18) Comparison of ESP, JPL91, KIng/Stassinopoulos, and PSYCHIC Models; 19) New Model Developments: Solar Heavy Ion Model; 20) Comparison of CREME96 to CREDO Measurements During 2000 and 2002; 21) PSYCHIC Heavy ion Model; 22) Model Standardization; 23) Working Group Meeting on New Standard Radiation Belt and Space Plasma Models; and 24) Summary.

Barth, Janet; Xapsos, Mike; Lauenstein, Jean-Marie; Ladbury, Ray

2006-01-01

289

Extended frequency turbofan model  

NASA Technical Reports Server (NTRS)

The fan model was developed using two dimensional modeling techniques to add dynamic radial coupling between the core stream and the bypass stream of the fan. When incorporated into a complete TF-30 engine simulation, the fan model greatly improved compression system frequency response to planar inlet pressure disturbances up to 100 Hz. The improved simulation also matched engine stability limits at 15 Hz, whereas the one dimensional fan model required twice the inlet pressure amplitude to stall the simulation. With verification of the two dimensional fan model, this program formulated a high frequency F-100(3) engine simulation using row by row compression system characteristics. In addition to the F-100(3) remote splitter fan, the program modified the model fan characteristics to simulate a proximate splitter version of the F-100(3) engine.

Mason, J. R.; Park, J. W.; Jaekel, R. F.

1980-01-01

290

Probabilistic Mesomechanical Fatigue Model  

NASA Technical Reports Server (NTRS)

A probabilistic mesomechanical fatigue life model is proposed to link the microstructural material heterogeneities to the statistical scatter in the macrostructural response. The macrostructure is modeled as an ensemble of microelements. Cracks nucleation within the microelements and grow from the microelements to final fracture. Variations of the microelement properties are defined using statistical parameters. A micromechanical slip band decohesion model is used to determine the crack nucleation life and size. A crack tip opening displacement model is used to determine the small crack growth life and size. Paris law is used to determine the long crack growth life. The models are combined in a Monte Carlo simulation to determine the statistical distribution of total fatigue life for the macrostructure. The modeled response is compared to trends in experimental observations from the literature.

Tryon, Robert G.

1997-01-01

291

Multiscale Cancer Modeling  

PubMed Central

Simulating cancer behavior across multiple biological scales in space and time, i.e., multiscale cancer modeling, is increasingly being recognized as a powerful tool to refine hypotheses, focus experiments, and enable more accurate predictions. A growing number of examples illustrate the value of this approach in providing quantitative insight on the initiation, progression, and treatment of cancer. In this review, we introduce the most recent and important multiscale cancer modeling works that have successfully established a mechanistic link between different biological scales. Biophysical, biochemical, and biomechanical factors are considered in these models. We also discuss innovative, cutting-edge modeling methods that are moving predictive multiscale cancer modeling toward clinical application. Furthermore, because the development of multiscale cancer models requires a new level of collaboration among scientists from a variety of fields such as biology, medicine, physics, mathematics, engineering, and computer science, an innovative Web-based infrastructure is needed to support this growing community. PMID:21529163

Macklin, Paul; Cristini, Vittorio

2013-01-01

292

Energy balance climate models  

NASA Technical Reports Server (NTRS)

An introductory survey of the global energy balance climate models is presented with an emphasis on analytical results. A sequence of increasingly complicated models involving ice cap and radiative feedback processes are solved, and the solutions and parameter sensitivities are studied. The model parameterizations are examined critically in light of many current uncertainties. A simple seasonal model is used to study the effects of changes in orbital elements on the temperature field. A linear stability theorem and a complete nonlinear stability analysis for the models are developed. Analytical solutions are also obtained for the linearized models driven by stochastic forcing elements. In this context the relation between natural fluctuation statistics and climate sensitivity is stressed.

North, G. R.; Cahalan, R. F.; Coakley, J. A., Jr.

1981-01-01

293

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

294

Cloud Model Bat Algorithm  

PubMed Central

Bat algorithm (BA) is a novel stochastic global optimization algorithm. Cloud model is an effective tool in transforming between qualitative concepts and their quantitative representation. Based on the bat echolocation mechanism and excellent characteristics of cloud model on uncertainty knowledge representation, a new cloud model bat algorithm (CBA) is proposed. This paper focuses on remodeling echolocation model based on living and preying characteristics of bats, utilizing the transformation theory of cloud model to depict the qualitative concept: “bats approach their prey.” Furthermore, Lévy flight mode and population information communication mechanism of bats are introduced to balance the advantage between exploration and exploitation. The simulation results show that the cloud model bat algorithm has good performance on functions optimization. PMID:24967425

Zhou, Yongquan; Xie, Jian; Li, Liangliang; Ma, Mingzhi

2014-01-01

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

Chromosphere flare models  

NASA Technical Reports Server (NTRS)

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.

1985-01-01

297

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.

298

Outside users payload model  

NASA Technical Reports Server (NTRS)

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 scope of the model; (2) discussion of the methodology used; (3) overview of total demand; (4) summary of the estimated market segmentation by launch vehicle; (5) summary of the estimated market segmentation by user type; (6) details of the STS market forecast; (7) summary of transponder trends; (8) model overview by mission category; and (9) detailed mission models. All known non-NASA, non-DOD reimbursable payloads forecast to be flown by non-Soviet-block countries are included in this model with the exception of Spacelab payloads and small self contained payloads. Certain DOD-sponsored or cosponsored payloads are included if they are reimbursable launches.

1985-01-01

299

AREST model description  

SciTech Connect

The Office of Civilian Radioactive Waste Management and the Power Reactor and Nuclear Fuel Development Corporation of Japan (PNC) have supported the development of the Analytical Repository Source-Term (AREST) at Pacific Northwest Laboratory. AREST is a computer model developed to evaluate radionuclide release from an underground geologic repository. The AREST code can be used to calculate/estimate the amount and rate of each radionuclide that is released from the engineered barrier system (EBS) of the repository. The EBS is the man-made or disrupted area of the repository. AREST was designed as a system-level models to simulate the behavior of the total repository by combining process-level models for the release from an individual waste package or container. AREST contains primarily analytical models for calculating the release/transport of radionuclides to the lost rock that surrounds each waste package. Analytical models were used because of the small computational overhead that allows all the input parameters to be derived from a statistical distribution. Recently, a one-dimensional numerical model was also incorporated into AREST, to allow for more detailed modeling of the transport process with arbitrary length decay chains. The next step in modeling the EBS, is to develop a model that couples the probabilistic capabilities of AREST with a more detailed process model. This model will need to look at the reactive coupling of the processes that are involved with the release process. Such coupling would include: (1) the dissolution of the waste form, (2) the geochemical modeling of the groundwater, (3) the corrosion of the container overpacking, and (4) the backfill material, just to name a few. Several of these coupled processes are already incorporated in the current version of AREST.

Engel, D.W.; McGrail, B.P.

1993-11-01

300

Generating Gowdy cosmological models  

NASA Astrophysics Data System (ADS)

Using the analogy with stationary axisymmetric solutions, we present a method to generate new analytic cosmological solutions of Einstein's equation belonging to the class of T3 Gowdy cosmological models. We show that the solutions can be generated from their data at the initial singularity and present the formal general solution for arbitrary initial data. We exemplify the method by constructing the Kantowski-Sachs cosmological model and a generalization of it that corresponds to an unpolarized T3 Gowdy model.

Sánchez, Alberto; Macías, Alfredo; Quevedo, Hernando

2004-05-01

301

Animal Models of Mesothelioma  

Microsoft Academic Search

\\u000a Animal models for mesothelioma mainly stem from exposure of different species to environmental fibers that are carcinogenic.\\u000a The majority take months for a mesothelioma to develop in the abdomen or the chest. The models are invaluable, however, for\\u000a studying molecular pathways. Other models in transgenic animals have used novel promoters or other molecules involved in mesothelioma\\u000a generation to produce the

Harvey I. Pass; Joseph B. Pincus; Michele Carbone; Magdalena Plasilova

302

Dynamical holographic QCD model  

NASA Astrophysics Data System (ADS)

We develop a dynamical holographic QCD model, which resembles the renormalization group from ultraviolet (UV) to infrared (IR). The dynamical holographic model is constructed in the graviton-dilaton-scalar framework with the dilaton background field ? and scalar field X responsible for the gluodynamics and chiral dynamics, respectively. We summarize the results on hadron spectra, QCD phase transition and transport properties including the jet quenching parameter and the shear/bulk viscosity in the framework of the dynamical holographic QCD model.

Li, Danning; Huang, Mei

2014-11-01

303

Global Atmospheric Aerosol Modeling  

NASA Technical Reports Server (NTRS)

Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

2012-01-01

304

Frequentist Model Average Estimators  

Microsoft Academic Search

The traditional use of model selection methods in practice is to proceed as if the final selected model had been chosen in advance, without ac- knowledging the additional uncertainty introduced by model selection. This often means underreporting of variability and too optimistic confidence intervals. We build a general large-sample likelihood apparatus in which limiting distributions and risk properties of estimators-post-selection

Hjort N. L; Gerda Claeskens

2003-01-01

305

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.

306

Atmospheric prediction model survey  

NASA Technical Reports Server (NTRS)

As part of the SEASAT Satellite program of NASA, a survey of representative primitive equation atmospheric prediction models that exist in the world today was written for the Jet Propulsion Laboratory. Seventeen models developed by eleven different operational and research centers throughout the world are included in the survey. The surveys are tutorial in nature describing the features of the various models in a systematic manner.

Wellck, R. E.

1976-01-01

307

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

308

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.

NCTM Illuminations

2000-01-01

309

Modeling Instruction Program  

NSDL National Science Digital Library

Created by David Hestenes of Arizona State University's modeling instruction and software development research, this site is an approach to reform of curriculum design and teaching methodology has been guided by a Modeling Theory of Physics Instruction. In addition, the site also provides modeling instructions for biology, chemistry and physical science. External links are provided under the heading "Opportunities for Professional Growth." These allow teachers the opportunity for explore workshops and other programs which can help enhance their teaching/curriculum.

Hestenes, David

310

The Integrated Medical Model  

NASA Technical Reports Server (NTRS)

The goals of the Integrated Medical Model (IMM) are to develop an integrated, quantified, evidence-based decision support tool useful to crew health and mission planners and to help align science, technology, and operational activities intended to optimize crew health, safety, and mission success. Presentation slides address scope and approach, beneficiaries of IMM capabilities, history, risk components, conceptual models, development steps, and the evidence base. Space adaptation syndrome is used to demonstrate the model's capabilities.

Kerstman, Eric; Minard, Charles; Saile, Lynn; Freiere deCarvalho, Mary; Myers, Jerry; Walton, Marlei; Butler, Douglas; Iyengar, Sriram; Johnson-Throop, Kathy; Baumann, David

2010-01-01

311

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.

Robert MacKay

312

What is a "Model"?  

NSDL National Science Digital Library

In this activity, learners simulate the behavior of the atmosphere. Learners working in groups of four will represent "cells" of the model (Earth, lower atmosphere, upper atmosphere, and space) and exchange energy with each other. Learners will observe how temperature fluctuates in the model. Use this activity to introduce learners to the inner-workings of the atmosphere as well as how scientists use models to understand abstract phenomena.

Colorado State University

2009-01-01

313

Modeling an HIV Particle  

NSDL National Science Digital Library

This activity helps learners visualize the Human Immunodeficiency Virus (HIV) by constructing three-dimensional HIV particle models from paper. The model to be used is a 20-sided polyhedron (icosahedron) and represents a complete viral particle. Learners combine their finished models into one mass. This is a first step toward estimating how many HIV particles could be contained inside a white blood cell before being released into the blood stream to attack new cells.

Gregory L. Vogt, Ed.D.

2011-01-01

314

Area Models: Multiplying Fractions  

NSDL National Science Digital Library

In this lesson students will investigate relationship between area models and the concept of multiplying fractions. Students will use area model to develop understanding of the concept of multiplying fractions as well as to find the product of two common fraction. The teacher will use the free application GeoGebra (see download link under Suggested Technology) to provide students with a visual representation of how area models can be used at the time of multiplying fractions.

2012-11-05

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

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.

Karen Mesmer

2006-03-01

317

Agile Software Process model  

Microsoft Academic Search

The article proposes a new software process model, ASP (Agile Software Process) based on a decade-long evolution of software process models inside a Japanese software factory. The Japanese software factory was a successful model in the development of quality software for large-scale business applications in the 1980s. However, the business climate of software development has dramatically changed in the last

Mikio Aoyama

1997-01-01

318

Model Analyses and Guidance  

NSDL National Science Digital Library

This site from the NOAA provides graphics for forecast models including: the ETA, the Global Forecast System (GFS), the Wave Watch III (WW3), the Nested Grid model (NGM), and the Rapid Update Cycle (RUC). Outputs are available for North America, North Pacific, Western North Atlantic, and the Polar Ice Drift. Users can find links to detailed descriptions of the inputs and history of each model.

319

Model Wind Tunnel  

NSDL National Science Digital Library

In this activity, learners build a miniature wind tunnel to measure force. Learners construct the model out of Lexan plastic, a fan, and a precise digital scale. When wind pushes against a model car, a beam (hacked out of the digital scale) measures the force, which is very close to the actual drag caused by the car. Learners can use this tool to help prepare for a Pinewood Derby or model car race, or to learn about wind forces and turbulence.

Douglas Desrochers

2011-01-01

320

Particle bed reactor modeling  

NASA Technical Reports Server (NTRS)

The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

Sapyta, Joe; Reid, Hank; Walton, Lew

1993-01-01

321

A Model Parasite  

NSDL National Science Digital Library

In this detailed activity (on pages 9-18), learners investigate the body parts of a parasitic ascaris worm by making and dissecting clay models. Each learner creates a model of either a male or female worm, then they swap models, predict the sex of their new worm, and dissect it to check their prediction. Labels are provided for marking the parts of the dissected models. The activity introduces learners to the structure and function of digestive and reproductive organs of organisms that can live in the human body and cause disease.

University of Nebraska State Museum

2001-01-01

322

Modeling Earth's Energy Balance  

NSDL National Science Digital Library

In this activity, learners use the STELLA box modeling software to determine Earth's temperature based on incoming solar radiation and outgoing terrestrial radiation. Starting with a simple black body model, the exercise gradually adds complexity by incorporating albedo, then a 1-layer atmosphere, then a 2-layer atmosphere, and finally a complex atmosphere with latent and sensible heat fluxes. With each step, students compare the modeled surface temperature to Earth's actual surface temperature, thereby providing a check on how well each increasingly complex model captures the physics of the actual system.

Kirsten Menking

323

Modeling plant morphogenesis.  

PubMed

Applications of computational techniques to developmental plant biology include the processing of experimental data and the construction of simulation models. Substantial progress has been made in these areas over the past few years. Complex image-processing techniques are used to integrate sequences of two-dimensional images into three-dimensional descriptions of development over time and to extract useful quantitative traits. Large amounts of data are integrated into empirical models of developing plant organs and entire plants. Mechanistic models link molecular-level phenomena with the resulting phenotypes. Several models shed light on the possible properties of active auxin transport and its role in plant morphogenesis. PMID:16376602

Prusinkiewicz, Przemyslaw; Rolland-Lagan, Anne-Gaëlle

2006-02-01

324

Space Station Parametric Models  

NASA Technical Reports Server (NTRS)

The development of two parametric models for a four-panel planar initial space station is described. The derivations of the distributed parameter model are presented in detail with the hope that the same method and procedures can be employed for stations with different configurations or for changes within the same configuration class. The 19-DOF finite-element model is also described. With the availability of the 19-DOF and a lower-DOF space station models, the frequency characteristics of the various dynamical systems in the space station environment are identified.

Hamidi, M.; Wang, S. J.

1985-01-01

325

Models of Holographic superconductivity  

E-print Network

We construct general models for holographic superconductivity parametrized by three couplings which are functions of a real scalar field and show that under general assumptions they describe superconducting phase transitions. While some features are universal and model independent, important aspects of the quantum critical behavior strongly depend on the choice of couplings, such as the order of the phase transition and critical exponents of second-order phase transitions. In particular, we study a one-parameter model where the phase transition changes from second to first order above some critical value of the parameter and a model with tunable critical exponents.

Francesco Aprile; Jorge G. Russo

2010-01-21

326

Myeloproliferative Neoplasm Animal Models  

PubMed Central

Synopsis Myeloproliferative neoplasm (MPN) animal models accurately re-capitulate human disease in mice and have been an important tool for the study of MPN biology and therapy. Transplantation of BCR-ABL transduced bone marrow cells into irradiated syngeneic mice established the field of MPN animal modeling and the retroviral bone marrow transplantation (BMT) assay has been used extensively since. Genetically engineered MPN animal models have enabled detailed characterization of the effects of specific MPN associated genetic abnormalities on the hematopoietic stem and progenitor cell (HSPC) compartment and xenograft models have allowed the study of primary human MPN-propagating cells in vivo. All models have facilitated the pre-clinical development of MPN therapies. JAK2V617F, the most common molecular abnormality in BCR-ABL negative MPN, has been extensively studied using retroviral, transgenic, knock-in and xenograft models. MPN animal models have also been used to investigate additional genetic lesions found in human MPN and to evaluate the bone marrow microenvironment in these diseases. Finally, several genetic lesions, although not common, somatically mutated drivers of MPN in humans induce a MPN phenotype in mice. Future uses for MPN animal models will include modeling compound genetic lesions in MPN and studying myelofibrotic transformation. PMID:23009938

Mullally, Ann; Lane, Steven W.; Brumme, Kristina; Ebert, Benjamin L.

2012-01-01

327

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

328

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

329

Wind power prediction models  

NASA Technical Reports Server (NTRS)

Investigations were performed to predict the power available from the wind at the Goldstone, California, antenna site complex. The background for power prediction was derived from a statistical evaluation of available wind speed data records at this location and at nearby locations similarly situated within the Mojave desert. In addition to a model for power prediction over relatively long periods of time, an interim simulation model that produces sample wind speeds is described. The interim model furnishes uncorrelated sample speeds at hourly intervals that reproduce the statistical wind distribution at Goldstone. A stochastic simulation model to provide speed samples representative of both the statistical speed distributions and correlations is also discussed.

Levy, R.; Mcginness, H.

1976-01-01

330

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.

NASA: Challenger Center

331

Parametric Models of Periodogram  

NASA Astrophysics Data System (ADS)

The maximum likelihood estimator is used to determine fit parameters for various parametric models of the Fourier periodogram followed by the selection of the best-fit model amongst competing models using the Akaike information criteria. This analysis, when applied to light curves of active galactic nuclei can be used to infer the presence of quasi-periodicity and break or knee frequencies. The extracted information can be used to place constraints on the mass, spin and other properties of the putative central black hole and the region surrounding it through theoretical models involving disk and jet physics.

Mohan, P.; Mangalam, A.; Chattopadhyay, S.

2014-11-01

332

Parametric Models of Periodogram  

NASA Astrophysics Data System (ADS)

The maximum likelihood estimator is used to determine fit parameters for various parametric models of the Fourier periodogram followed by the selection of the best-fit model amongst competing models using the Akaike information criteria. This analysis, when applied to light curves of active galactic nuclei can be used to infer the presence of quasi-periodicity and break or knee frequencies. The extracted information can be used to place constraints on the mass, spin and other properties of the putative central black hole and the region surrounding it through theoretical models involving disk and jet physics.

Mohan, P.; Mangalam, A.; Chattopadhyay, S.

2014-09-01

333

Modelling approaches in biomechanics.  

PubMed Central

Conceptual, physical and mathematical models have all proved useful in biomechanics. Conceptual models, which have been used only occasionally, clarify a point without having to be constructed physically or analysed mathematically. Some physical models are designed to demonstrate a proposed mechanism, for example the folding mechanisms of insect wings. Others have been used to check the conclusions of mathematical modelling. However, others facilitate observations that would be difficult to make on real organisms, for example on the flow of air around the wings of small insects. Mathematical models have been used more often than physical ones. Some of them are predictive, designed for example to calculate the effects of anatomical changes on jumping performance, or the pattern of flow in a 3D assembly of semicircular canals. Others seek an optimum, for example the best possible technique for a high jump. A few have been used in inverse optimization studies, which search for variables that are optimized by observed patterns of behaviour. Mathematical models range from the extreme simplicity of some models of walking and running, to the complexity of models that represent numerous body segments and muscles, or elaborate bone shapes. The simpler the model, the clearer it is which of its features is essential to the calculated effect. PMID:14561333

Alexander, R McN

2003-01-01

334

NARSTO NE MODEL  

Atmospheric Science Data Center

... Station Instrument:  Chemiluminescence UV Ozone Detector Location:  Northeastern United States ... Files:  NE Model Readme Hourly Surface Air Quality Ozone & Nitrogen Measurement Sites Related Data:  ...

2014-04-25

335

Incinerator model uses Lotus  

SciTech Connect

To evaluate proposed incineration systems, designers, operators, and regulatory personnel have had to resort to general computerized combustion models. These, however, have only limited application to incinerators. This article describes one way to build a computerized model specially designed for incinerators. If the model is built to cover a wide spectrum of incinerator applications, it can provide a consistent means of quickly comparing design configuration method, the author built his model in the Lotus 1-2-3 spreadsheet, with which more people are familiar.

Marks, C.H.

1987-12-01

336

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.

Andrew Jackson

337

Using Markov Models and Hidden Markov Models to Find Repetitive  

E-print Network

Using Markov Models and Hidden Markov Models to Find Repetitive Extragenic Palindromic Sequences for using simple Markov models and hidden Markov models hmms to search for interesting sequences for automatically constructing simple Markov models and hidden Markov models from small training sets

Karplus, Kevin

338

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

339

DYNAMIC MODEL DATA DYNAMIC SIMULATION ,MODELING  

E-print Network

/B/C/D Propane condenser Table 4.1.4 Heat exchanger Unit Operations Unit Operations (Model Name) Description E LINK ,HYSIS SOFTWARE PID CONTROL SYSTEM . REFRIGERATOR SYSTEM SAMPLE . 2 , STAND to effect the pressure than one of cooling water exchanger. Figure 4.2.5 Data for E-2512A/B Figure 4

Hong, Deog Ki

340

BLACK-BOX MODELLING Response surface modelling  

E-print Network

Post-processing Scaling / normalizing the data helps both for ANN & SVM's Otherwise there is a risk Neural Networks Support-Vector Machines Importance of Data Post-processing Feature Selection Algorithm of the first tools of machine learning Many publications of ANN- based models in electronics Known issues

Steels, Luc

341

Model selection in compositional spaces  

E-print Network

We often build complex probabilistic models by composing simpler models-using one model to generate parameters or latent variables for another model. This allows us to express complex distributions over the observed data ...

Grosse, Roger Baker

2014-01-01

342

Epidemic modeling techniques for smallpox  

E-print Network

Infectious disease models predict the impact of outbreaks. Discrepancies between model predictions stem from both the disease parameters used and the underlying mathematics of the models. Smallpox has been modeled extensively ...

McLean, Cory Y. (Cory Yuen Fu)

2004-01-01

343

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...

344

Why business models matter.  

PubMed

"Business model" was one of the great buzz-words of the Internet boom. A company didn't need a strategy, a special competence, or even any customers--all it needed was a Web-based business model that promised wild profits in some distant, ill-defined future. Many people--investors, entrepreneurs, and executives alike--fell for the fantasy and got burned. And as the inevitable counterreaction played out, the concept of the business model fell out of fashion nearly as quickly as the .com appendage itself. That's a shame. As Joan Magretta explains, a good business model remains essential to every successful organization, whether it's a new venture or an established player. To help managers apply the concept successfully, she defines what a business model is and how it complements a smart competitive strategy. Business models are, at heart, stories that explain how enterprises work. Like a good story, a robust business model contains precisely delineated characters, plausible motivations, and a plot that turns on an insight about value. It answers certain questions: Who is the customer? How do we make money? What underlying economic logic explains how we can deliver value to customers at an appropriate cost? Every viable organization is built on a sound business model, but a business model isn't a strategy, even though many people use the terms interchangeably. Business models describe, as a system, how the pieces of a business fit together. But they don't factor in one critical dimension of performance: competition. That's the job of strategy. Illustrated with examples from companies like American Express, EuroDisney, WalMart, and Dell Computer, this article clarifies the concepts of business models and strategy, which are fundamental to every company's performance. PMID:12024761

Magretta, Joan

2002-05-01

345

ENSO Nonlinear Regression Model  

NASA Astrophysics Data System (ADS)

A multiple polynomial regression of sea-surface temperature anomalies (SSTA) is used to build and compare linear and nonlinear stochastically forced models of ENSO. It is shown that the nonlinear model has a significantly better forecast skill for Nino3.4 SSTA than its linear counterpart, in particular during strong warm ENSO events. The 1950-2002 Kaplan extended SSTA dataset (IRI/LDEO Climate Data Library), 60N-30S, 30E-110W, is used to train and validate the models. Both linear and nonlinear models are trained on 1950-1996, and validated on1997-2002 SSTA data, which includes the strong 1997-1998 warm ENSO event. We apply a multi-layer generalization of multiple polynomial regression where the residual stochastic forcing at a given level is modeled as a function of variables at the current, and all preceding levels. The number of levels is determined so that the lag-0 covariance of the residual forcing converges to a constant matrix, while its lag-1 covariance vanishes. Regression models are obtained via partial least-square (PLS) cross-validation procedure, where the leading empirical orthogonal functions (EOFs) of SSTA are chosen to build predictor variables for the regression model’s first level. PLS finds the so-called factors, or latent variables that both capture the maximum variance in the predictor variables, and achieve high correlation with response variables. The phase-locking of ENSO to annual cycle in the model is achieved by adding the linear seasonal forcing on the first regression level. A better performance of the nonlinear model is associated with its ability to simulate a non-Gaussian distribution of ENSO events, with warm events having larger amplitude than cold events. This property cannot be captured in a linear model.

Kondrashov, D.; Kravtsov, S.; Ghil, M.

2003-04-01

346

Biosphere Process Model Report  

SciTech Connect

To evaluate the postclosure performance of a potential monitored geologic repository at Yucca Mountain, a Total System Performance Assessment (TSPA) will be conducted. Nine Process Model Reports (PMRs), including this document, are being developed to summarize the technical basis for each of the process models supporting the TSPA model. These reports cover the following areas: (1) Integrated Site Model; (2) Unsaturated Zone Flow and Transport; (3) Near Field Environment; (4) Engineered Barrier System Degradation, Flow, and Transport; (5) Waste Package Degradation; (6) Waste Form Degradation; (7) Saturated Zone Flow and Transport; (8) Biosphere; and (9) Disruptive Events. Analysis/Model Reports (AMRs) contain the more detailed technical information used to support TSPA and the PMRs. The AMRs consists of data, analyses, models, software, and supporting documentation that will be used to defend the applicability of each process model for evaluating the postclosure performance of the potential Yucca Mountain repository system. This documentation will ensure the traceability of information from its source through its ultimate use in the TSPA-Site Recommendation (SR) and in the National Environmental Policy Act (NEPA) analysis processes. The objective of the Biosphere PMR is to summarize (1) the development of the biosphere model, and (2) the Biosphere Dose Conversion Factors (BDCFs) developed for use in TSPA. The Biosphere PMR does not present or summarize estimates of potential radiation doses to human receptors. Dose calculations are performed as part of TSPA and will be presented in the TSPA documentation. The biosphere model is a component of the process to evaluate postclosure repository performance and regulatory compliance for a potential monitored geologic repository at Yucca Mountain, Nevada. The biosphere model describes those exposure pathways in the biosphere by which radionuclides released from a potential repository could reach a human receptor. Collectively, the potential human receptor and exposure pathways form the biosphere model. More detailed technical information and data about potential human receptor groups and the characteristics of exposure pathways have been developed in a series of AMRs and Calculation Reports.

J. Schmitt

2000-05-25

347

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

348

The Monster Model John Baldwin  

E-print Network

The Monster Model John Baldwin February 3, 2010 Contemporary model theorists often begin papers model theory but they are explicitly addressed and do not arise through the monster model convention is a particular first order theory. The need is for a monster model of the theory T. If M is a saturated model

Baldwin, John T.

349

Bayesian Model Averaging: A Tutorial  

Microsoft Academic Search

Standard statistical practice ignores model uncertainty. Data analysts typically select a model from some class of models and then proceed as if the selected model had generated the data. This approach ignores the uncertainty in model selection, leading to over-confident in- ferences and decisions that are more risky than one thinks they are. Bayesian model averaging (BMA) provides a coherent

Jennifer A. Hoeting; David Madigan; Adrian E. Raftery; Chris T. Volinsky

350

Modelling Nonlinear Economic Time Series  

Microsoft Academic Search

This book contains an extensive up-to-date overview of nonlinear time series models and their application to modelling economic relationships. It considers nonlinear models in stationary and nonstationary frameworks, and both parametric and nonparametric models are discussed. The book contains examples of nonlinear models in economic theory and presents the most common nonlinear time series models. Importantly, it shows the reader

Timo Terasvirta; Dag Tjostheim; Clive W. J. Granger

351

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

352

Modeling Antibody Diversity.  

ERIC Educational Resources Information Center

Understanding antibody structure and function is difficult for many students. The rearrangement of constant and variable regions during antibody differentiation can be effectively simulated using a paper model. Describes a hands-on laboratory exercise which allows students to model antibody diversity using readily available resources. (PVD)

Baker, William P.; Moore, Cathy Ronstadt

1998-01-01

353

Modeling Microbial Growth  

NSDL National Science Digital Library

Is bacterial growth always exponential? Do bacteria with the fastest rate of growth always have the largest populations? Biota models offer extended opportunities to observe population growth over time. What are the factors that affect growth? Explore continuous, chaotic, and cyclic growth models. * examine the dynamics of growth for populations of virtual bacteria with differing growth rates and carrying capacities

Ethel D. Stanley (Beloit College; Biology)

2006-05-20

354

Modeling Carbon Exchange  

NASA Technical Reports Server (NTRS)

Model results will be reviewed to assess different methods for bounding the terrestrial role in the global carbon cycle. It is proposed that a series of climate model runs could be scoped that would tighten the limits on the "missing sink" of terrestrial carbon and could also direct future satellite image analyses to search for its geographical location and understand its seasonal dynamics.

Sellers, Piers

2012-01-01

355

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

356

PHOTOCHEMICAL BOX MODEL (PBM)  

EPA Science Inventory

This magnetic tape contains the FORTRAN source code, sample input data, and sample output data for the Photochemical Box Model (PBM). The PBM is a simple stationary single-cell model with a variable height lid designed to provide volume-integrated hour averages of O3 and other ph...

357

Dynamic accelerator modeling  

SciTech Connect

Object-Oriented Programming has been used extensively to model the LBL Advanced Light Source 1.5 GeV electron storage ring. This paper is on the present status of the class library construction with emphasis on a dynamic modeling.

Nishimura, Hiroshi

1993-05-01

358

Repairing CAD models  

Microsoft Academic Search

We describe an algorithm for repairing polyhedral CAD models that have errors in their B-REP. Errors like cracks, degeneracie s, du- plication, holes and overlaps are usually introduced in sol id mod- els due to imprecise arithmetic, model transformations, de signer's fault, programming bugs, etc. Such errors often hamper furt her pro- cessing like finite element analysis, radiosity computatio n

Gill Barequet; Subodh Kumar

1997-01-01

359

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

360

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

361

Multiplying Fractions (Area Model)  

NSDL National Science Digital Library

In this teaching idea, students will learn how to use the area model to find the product when two fractions are multiplied. NOTE: Click the Download link on the right side of the screen to display the lesson without ads and to view the graphic example of the model.

Audrey Pruitt - on Hotchalk Lesson Plans Page

2012-04-22

362

Reasoning and Formal Modelling  

E-print Network

Reasoning and Formal Modelling for Forensic Science Lecture 2 Prof. Dr. Benedikt L¨owe What for Forensic Science Lecture 2 Prof. Dr. Benedikt L¨owe What is logic anyway? The Wason task Syntax, Semantics, Pragmatics Assessment and grade (1). #12;Reasoning and Formal Modelling for Forensic Science Lecture 2 Prof

Löwe, Benedikt

363

Sound mobility models  

Microsoft Academic Search

Simulation has become an indispensable tool in the construction and evaluation of mobile systems. By using mobility models that describe constituent movement, one can explore large systems, producing repeatable results for comparison between alternatives. Unfortunately, the vast majority of mobility models---including all those in which nodal speed and distance or destination are chosen independently---suffer from decay; average speed decreases until

Jungkeun Yoon; Mingyan Liu; Brian Noble

2003-01-01

364

Generalized dielectric breakdown model  

Microsoft Academic Search

We propose a generalized version of the dielectric breakdown model (DBM) for generic breakdown processes. It interpolates between the standard DBM and its analog with quenched disorder (QDBM), as a temperaturelike parameter is varied. The physics of other well-known fractal growth phenomena such as invasion percolation and the Eden model are also recovered for some particular parameter values. Competition between

R. Cafiero; A. Gabrielli; M. Marsili; M. A. Muñoz; L. Pietronero

1999-01-01

365

Applied model validation  

NASA Astrophysics Data System (ADS)

The NBS Center for Fire Research (CFR) conducts scientific research bearing on the fire safety of buildings, vehicles, tunnels and other inhabited structures. Data from controlled fire experiments are collected, analyzed and reduced to the analytical formulas that appear to underly the observed phenomena. These results and more general physical principles are then combined into models to predict the development of environments that may be hostile to humans. This is a progress report of an applied model validation case study. The subject model is Transport of Fire, Smoke and Gases (FAST). Products from a fire in a burn room exit through a connected corridor to outdoors. Cooler counterflow air in a lower layer feeds the fire. The model predicts corridor layer temperatures and thicknesses vs. time, given enclosure, fire and ambient specifications. Data have been collected from 38 tests using several fire sizes, but have not been reduced. Corresponding model results, and model and test documentation are yet to come. Considerable modeling and calculation is needed to convert instrument readings to test results comparable with model outputs so that residual differences may be determined.

Davies, A. D.

1985-07-01

366

MODELING WATER QUALITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Water quality models are based on some representation of hydrology and may include movement of surface water, ground water, and mixing of water in lakes and water bodies. Water quality models simulate some combination of sediment, nutrients, heavy metals, xenobiotics, and aquatic biology. Althoug...

367

Focus Article Electrophysiological models  

E-print Network

capabilities of individual neurons lie at the core of these models, with the emphasis shifting upward addressed. This review provides an introduction to the techniques for constructing biophysically based neuroinformatics approaches that can potentially link such models with a wealth of empirical data currently being

Nelson, Mark E.

368

Illowra FLIR performance model  

Microsoft Academic Search

This paper describes the Illowra forward looking infrared (FLIR) performance model, which has been developed by the Defence Science and Technology Organisation (DSTO) and British Aerospace Australia (BAeA). The Illowra model enables calculations of system performance to be carried out for a wide range of FLIR technologies including thermal, photoconductive, and photovoltaic detector based systems used in various staring and

Grant Burfield; Duncan W. Craig; Murray R. Meharry; John W. Norrington; I. Tuohy

1993-01-01

369

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

370

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.

Bill Locke

371

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

372

Modeling Shared Situation Awareness  

Microsoft Academic Search

This study presents an initial computational model of shared situation awareness (SA) based upon data collected from a simulated training exercise, designed to mimic real life events in a military personnel recovery center. Situation awareness was measured during the exercise using the Situation Awareness Global Assessment Technique (SAGAT). Our initial model examined how well five factors (social network distance, physical

Cheryl A. Bolstad; Haydee M. Cuevas

2005-01-01

373

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

374

Animal models for osteoporosis  

NASA Technical Reports Server (NTRS)

Animal models will continue to be important tools in the quest to understand the contribution of specific genes to establishment of peak bone mass and optimal bone architecture, as well as the genetic basis for a predisposition toward accelerated bone loss in the presence of co-morbidity factors such as estrogen deficiency. Existing animal models will continue to be useful for modeling changes in bone metabolism and architecture induced by well-defined local and systemic factors. However, there is a critical unfulfilled need to develop and validate better animal models to allow fruitful investigation of the interaction of the multitude of factors which precipitate senile osteoporosis. Well characterized and validated animal models that can be recommended for investigation of the etiology, prevention and treatment of several forms of osteoporosis have been listed in Table 1. Also listed are models which are provisionally recommended. These latter models have potential but are inadequately characterized, deviate significantly from the human response, require careful choice of strain or age, or are not practical for most investigators to adopt. It cannot be stressed strongly enough that the enormous potential of laboratory animals as models for osteoporosis can only be realized if great care is taken in the choice of an appropriate species, age, experimental design, and measurements. Poor choices will results in misinterpretation of results which ultimately can bring harm to patients who suffer from osteoporosis by delaying advancement of knowledge.

Turner, R. T.; Maran, A.; Lotinun, S.; Hefferan, T.; Evans, G. L.; Zhang, M.; Sibonga, J. D.

2001-01-01

375

Prewhirl Jet Model  

NASA Technical Reports Server (NTRS)

Simple accurate model of centrifugal or rocket engine pumps provides information necessary to design inducer backflow deflector, backflow eliminator and prewhirl jet in jet mixing zones. Jet design based on this model shows improvement in inducer suction performance and reduced cavitation damage.

Meng, S. Y.; Jensen, M.; Jackson, E. D.

1985-01-01

376

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

377

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.

2012-04-12

378

Insect Models of Immunosenescence  

Microsoft Academic Search

For the past few decades invertebrates have been used extensively as models for understanding the general process of senescence\\u000a (see reviews by Partridge and Gems 2002 ; Grotewiel et al. 2005 ; Keller and Jemielity 2006 ; Houthoofd and Vanfleteren 2007\\u000a ) and since the 1920’s as models for understanding the genes, signaling pathways and cellular processes involved in innate

Jeff Leips

379

Macroscopic Models of Superconductivity  

E-print Network

Macroscopic Models of Superconductivity S. J. Chapman, St. Catherine's College, Oxford. Thesis-boundary model for the destruction of superconductivity by an applied magnetic field, under isothermal then describe the Ginzburg-Landau theory of superconductivity, in which the sharp interface is `smoothed out

Chapman, Jon

380

Interharmonics: Theory and Modeling  

Microsoft Academic Search

Some of the most remarkable issues related to interharmonic theory and modeling are presented. Starting from the basic definitions and concepts, attention is first devoted to interharmonic sources. Then, the interharmonic assessment is considered with particular attention to the problem of the frequency resolution and of the computational burden associated with the analysis of periodic steady-state waveforms. Finally, modeling of

A. Testa; M. F. Akram; R. Burch; G. Carpinelli; G. Chang; V. Dinavahi; C. Hatziadoniu; W. M. Grady; E. Gunther; M. Halpin; P. Lehn; Y. Liu; R. Langella; M. Lowenstein; A. Medina; T. Ortmeyer; S. Ranade; P. Ribeiro; N. Watson; J. Wikston; W. Xu

2007-01-01

381

Empirical Bayes Linear Models  

E-print Network

Empirical Bayes Will Penny Linear Models Empirical Bayes Isotropic Covariances EM Algorithm Coding MAP Learning Self-Inhibition Receptive Fields References Empirical Bayes Will Penny Bayesian Inference Course, WTCN, UCL, March 2013 #12;Empirical Bayes Will Penny Linear Models Empirical Bayes

Penny, Will

382

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

383

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

384

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

385

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

386

Calibrating Water System Models  

Microsoft Academic Search

Calibration enables a computer model to simulate field conditions accurately. Telemetry data and field measurements of the system provide base data for calibration, but computer programs that automatically extract and compare pertinent data with simulated values can aid the process. Once calibrated, the model can be used with a great degree of confidence as a predictor and as a benchmark

A. Lee Cesario; J. O. Davis

1984-01-01

387

Dasymetric Modeling and Uncertainty  

PubMed Central

Dasymetric models increase the spatial resolution of population data by incorporating related ancillary data layers. The role of uncertainty in dasymetric modeling has not been fully addressed as of yet. Uncertainty is usually present because most population data are themselves uncertain, and/or the geographic processes that connect population and the ancillary data layers are not precisely known. A new dasymetric methodology - the Penalized Maximum Entropy Dasymetric Model (P-MEDM) - is presented that enables these sources of uncertainty to be represented and modeled. The P-MEDM propagates uncertainty through the model and yields fine-resolution population estimates with associated measures of uncertainty. This methodology contains a number of other benefits of theoretical and practical interest. In dasymetric modeling, researchers often struggle with identifying a relationship between population and ancillary data layers. The PEDM model simplifies this step by unifying how ancillary data are included. The P-MEDM also allows a rich array of data to be included, with disparate spatial resolutions, attribute resolutions, and uncertainties. While the P-MEDM does not necessarily produce more precise estimates than do existing approaches, it does help to unify how data enter the dasymetric model, it increases the types of data that may be used, and it allows geographers to characterize the quality of their dasymetric estimates. We present an application of the P-MEDM that includes household-level survey data combined with higher spatial resolution data such as from census tracts, block groups, and land cover classifications. PMID:25067846

Nagle, Nicholas N.; Buttenfield, Barbara P.; Leyk, Stefan; Speilman, Seth

2014-01-01

388

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...

389

Geothermal Power Plant Model  

NSDL National Science Digital Library

In this activity, learners make a model of a power plant that uses steam. Learners use simple materials like foil, a tin can, and a pot of water to model a geothermal power plant. Learners use a pinwheel to observe the power produced by the steam. SAFETY NOTE: Adult assistance required.

California Energy Commission

2006-01-01

390

Cognitive Models Visual Sensemaking  

E-print Network

innovation & knowledge creation l foraging for information l making sense of it l "crystallizing" it into new-09-1999 12 Data State Reference Model l Uses four data representation stages l Operators between and within stages l State Model DATA ANALYTICAL REPRESENTATION VISUALIZATION REPRESENTATION VIEW DATA TRANSFORMATION

Chi, Ed Huai-hsin

391

Modeling network dynamics  

PubMed Central

We use the lac operon in Escherichia coli as a prototype system to illustrate the current state, applicability, and limitations of modeling the dynamics of cellular networks. We integrate three different levels of description (molecular, cellular, and that of cell population) into a single model, which seems to capture many experimental aspects of the system. PMID:12743100

Vilar, José M.G.; Guet, C?lin C.; Leibler, Stanislas

2003-01-01

392

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

393

Computational Modeling of Tires  

NASA Technical Reports Server (NTRS)

This document contains presentations and discussions from the joint UVA/NASA Workshop on Computational Modeling of Tires. The workshop attendees represented NASA, the Army and Air force, tire companies, commercial software developers, and academia. The workshop objectives were to assess the state of technology in the computational modeling of tires and to provide guidelines for future research.

Noor, Ahmed K. (compiler); Tanner, John A. (compiler)

1995-01-01

394

Generalized simplicial chiral models  

NASA Astrophysics Data System (ADS)

Using the auxiliary field representation of the simplicial chiral models on a ( d-1)-dimensional simplex, the simplicial chiral models are generalized through replacing the term Tr (AA †) in the Lagrangian of these models by an arbitrary class function of AA †; V(AA †) . This is the same method used in defining the generalized two-dimensional Yang-Mills theories (gYM 2) from ordinary YM 2. We call these models the "generalized simplicial chiral models". Using the results of the one-link integral over a U( N) matrix, the large- N saddle-point equations for eigenvalue density function ?( z) in the weak ( ?> ?c) and strong ( ?< ?c) regions are computed. In d=2, where the model is in some sense related to the gYM 2 theory, the saddle-point equations are solved for ?( z) in the two regions, and the explicit value of critical point ?c is calculated for V(B)= Tr B n(B=AA †) . For V(B)= Tr B 2, Tr B 3, and Tr B4, the critical behaviour of the model at d=2 is studied, and by calculating the internal energy, it is shown that these models have a third order phase transition.

Alimohammadi, Masoud

2000-02-01

395

Foundations of Biomolecular Modeling  

PubMed Central

The 2013 Nobel Prize in Chemistry has been awarded to Martin Kaplus, Michael Levitt, and Arieh Warshel for “Development of Multiscale Models for Complex Chemical Systems”. The honored work from the 1970s has provided a foundation for the widespread activities today in modeling organic and biomolecular systems. PMID:24315087

Jorgensen, William L.

2014-01-01

396

Modeling the Night Sky  

NSDL National Science Digital Library

In this two-part activity, learners explore the Earth and Sun's positions in relation to the constellations of the ecliptic with a small model. Then they extend to explore the motions of the Earth and the inner planets in a larger classroom-size model.

McDonald Observatory

2011-01-01

397

Fitting Zodiacal Models  

E-print Network

Models of the zodiacal light are necessary to convert measured data taken from low Earth orbit into the radiation field outside the solar system. The uncertainty in these models dominates the overall uncertainty in determining the extragalactic background light for wavelengths < 100 microns.

Edward L. Wright

2001-06-22

398

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...

399

ATMOSPHERIC MODEL DEVELOPMENT  

EPA Science Inventory

This task provides credible state of the art air quality models and guidance for use in implementation of National Ambient Air Quality Standards for ozone and PM. This research effort is to develop and improve air quality models, such as the Community Multiscale Air Quality (CMA...

400

Modeling Water Filtration  

ERIC Educational Resources Information Center

Model-eliciting activities (MEAs) are not new to those in engineering or mathematics, but they were new to Melissa Parks. Model-eliciting activities are simulated real-world problems that integrate engineering, mathematical, and scientific thinking as students find solutions for specific scenarios. During this process, students generate solutions…

Parks, Melissa

2014-01-01

401

Modeling Vacuum Arcs  

Microsoft Academic Search

We are developing a model of vacuum arcs to describe vacuum breakdown in 805 MHz systems, however the basic mechanisms at work should apply to other applications. The model assumes: 1) that arcs develop as a result of mechanical failure of the surface due to Coulomb explosions, 2) this is followed by ionization of fragments by field emitted currents and

J. Norem; Z. Insepov; Th. Proslier; D. Huang; S. Mahalingam; S. Veitzer

2010-01-01

402

Modeling rf breakdown arcs  

Microsoft Academic Search

We describe breakdown in 805 MHz rf accelerator cavities in terms of a number of self consistent mechanisms. We divide the breakdown process into three stages: 1) we model surface failure using molecular dynamics of fracture caused by electrostatic tensile stress, 2) we model the ionization of neutrals responsible for plasma initiation and plasma growth using a particle in cell

Zeke Insepov; Jim Norem; Thomas Proslier; Dazhang Huang; Sudhakar Mahalingam; Seth Veitzer

2010-01-01

403

motivations modeling social structure  

E-print Network

diversity outline 1 motivations peptic ulcer disease bandit problems social structure 2 modeling social of Transient Diversity #12;motivations modeling social structure transient diversity peptic ulcer disease bandit problems social structure peptic ulcer disease Two nineteenth century theories about peptic ulcer

Zollman, Kevin

404

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...

405

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...

406

Context modeling and reasoning  

E-print Network

Applications Sentient Computing Smart * (Room, Space, Factory, ...) #12;Context-aware applications #12;10 User, Context-aware Applications (SFB 627)Universität Stuttgart #12;2 SFB 627 (Nexus): World Models for Mobile Context-Aware Systems Goals: Methods to realize global world model Innovative context-aware applications

Appelrath, Hans-Jürgen

407

COMPUTER PROCESSING AND MODELING -  

E-print Network

with advanced or disseminated disease. Preclinical rodent models provide a unique opportu- nity to test novel Society/Lungevity Foundation Research *Correspondence to: Vanessa K. Tidwell, B.S., Campus Box 1127 sur- gical resection hampers long-term survival (4). Preclinical rodent models provide a unique

Nehorai, Arye

408

Modelling Synchronized Hypermedia Presentations  

Microsoft Academic Search

This paper presents a synchronization model for hypermedia presentations. Several media, continuous, like video and audio files, and non-continuous, like text pages and images, are delivered separately in a distributed environment like the World Wide Web, and presented to the user in a coordinated way. The model is based on a set of synchronization relationships which define media behavior during

Ombretta Gaggi; Augusto Celentano

2005-01-01

409

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.

2004-07-21

410

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

411

THE AQUATOX MODEL  

EPA Science Inventory

This lecture will present AQUATOX, an aquatic ecosystem simulation model developed by Dr. Dick Park and supported by the U.S. EPA. The AQUATOX model predicts the fate of various pollutants, such as nutrients and organic chemicals, and their effects on the ecosystem, including fi...

412

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

413

Workplace Research Model  

NSDL National Science Digital Library

This pdf from the South Carolina Advanced Technological Education National Resource Center discusses a model for guided research to improve education for engineering and industrial technicians. The SC ATE Workplace Research Model provides a guide for interdisciplinary faculty, teacher and student teams to conduct workplace research and gain a better understanding of the technicianâ??s role in the workplace through industry site visits.

414

The Modeling Process  

Microsoft Academic Search

Considerable interest currently exists in the application of the systems approach to the solution of societal, political, and environmental problems. The essence of this systems approach is modeling, the capability to describe large-scale complicated interactive systems by symbolic representations so that inferences regarding the effects of alternative system configurations can be easily and rapidly structured. The modeling process is itself

G. Arthur Mihramber

1972-01-01

415

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

416

The Alternate Atomic Model  

Microsoft Academic Search

An alternate atomic model posits concentric electron and nucleon fields spinning together about an empty center. It is alternative to the generally accepted planetary system in which electron point particles orbit about a center clump of nucleon point particles. Introduced in 1992 as an alternative to the standard model of the nucleus it applies scientific space-time knowledge unknown when the

Evan Ragland

2008-01-01

417

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.

Bill Locke

418

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

419

COMMUTER EXPOSURE MODELING METHODOLOGIES  

EPA Science Inventory

Two methodologies for modeling commuter exposures are proposed: computer-oriented approach and a manual approach. Both modeling methodologies require that major commuter routes, or pathways, be identified and that the traffic on the remainder of the roadway network be treated as ...

420

MODELING FASHION , Gang Wang  

E-print Network

MODELING FASHION Qi Chen , Gang Wang , Chew Lim Tan Department of Computer Science, National}@comp.nus.edu.sg, wanggang@ntu.edu.sg ABSTRACT We propose a method to try to model fashionable dress- es in this paper. We clustering approach. A fashionable dress is expected to con- tain certain visual patterns which make

Tan, Chew Lim

421

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

Steve Metz

2011-02-01

422

Modeling a Hospital Organization  

Microsoft Academic Search

A multidimensional input-output model of a hospital's components is developed which, because it tracks the flows of people, materials, and services, can be used for long-range planning and resource allocation, and dynamic simulation of the hospital. The model also allows the determination of shadow prices, and hence, the profitability of the various hospital components.

William V. Gudaitis; Robert A. Brown

1975-01-01

423

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

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

The EMEFS model evaluation  

SciTech Connect

The binational Eulerian Model Evaluation Field Study (EMEFS) consisted of several coordinated data gathering and model evaluation activities. In the EMEFS, data were collected by five air and precipitation monitoring networks between June 1988 and June 1990. Model evaluation is continuing. This interim report summarizes the progress made in the evaluation of the Regional Acid Deposition Model (RADM) and the Acid Deposition and Oxidant Model (ADOM) through the December 1990 completion of a State of Science and Technology report on model evaluation for the National Acid Precipitation Assessment Program (NAPAP). Because various assessment applications of RADM had to be evaluated for NAPAP, the report emphasizes the RADM component of the evaluation. A protocol for the evaluation was developed by the model evaluation team and defined the observed and predicted values to be used and the methods by which the observed and predicted values were to be compared. Scatter plots and time series of predicted and observed values were used to present the comparisons graphically. Difference statistics and correlations were used to quantify model performance. 64 refs., 34 figs., 6 tabs.

Barchet, W.R. (Pacific Northwest Lab., Richland, WA (United States)); Dennis, R.L. (Environmental Protection Agency, Research Triangle Park, NC (United States)); Seilkop, S.K. (Analytical Sciences, Inc., Durham, NC (United States)); Banic, C.M.; Davies, D.; Hoff, R.M.; Macdonald, A.M.; Mickle, R.E.; Padro, J.; Puckett, K. (Atmospheric Environment Service, Downsview, ON (Canada)); Byun, D.; McHenry, J.N.

1991-12-01

426

Turbulent combustion modeling  

Microsoft Academic Search

Numerical simulation of flames is a growing field bringing important improvements to our understanding of combustion. The main issues and related closures of turbulent combustion modeling are reviewed. Combustion problems involve strong coupling between chemistry, transport and fluid dynamics. The basic properties of laminar flames are first presented along with the major tools developed for modeling turbulent combustion. The links

Denis Veynante; Luc Vervisch

2002-01-01

427

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

428

Multibody modeling and verification  

Microsoft Academic Search

A summary of a ten week project on flexible multibody modeling, verification and control is presented. Emphasis was on the need for experimental verification. A literature survey was conducted for gathering information on the existence of experimental work related to flexible multibody systems. The first portion of the assigned task encompassed the modeling aspects of flexible multibodies that can undergo

Gloria J. Wiens

1989-01-01

429

Earth and ocean modeling  

NASA Technical Reports Server (NTRS)

A modular structured system of computer programs is presented utilizing earth and ocean dynamical data keyed to finitely defined parameters. The model is an assemblage of mathematical algorithms with an inherent capability of maturation with progressive improvements in observational data frequencies, accuracies and scopes. The Eom in its present state is a first-order approach to a geophysical model of the earth's dynamics.

Knezovich, F. M.

1976-01-01

430

Cognitive Systems Cognitive Modeling  

E-print Network

1 Cognitive Systems Cognitive Modeling Foundations of Information Processing in Natural Barkowsky, Christian Freksa 2 Cognitive Systems: Topics · Introduction · Perception · Memory and Reasoning · Learning and Action · Communication · Empirical Methods 3 Cognitive Modeling: Topics · Cognitive

Bremen, Universität

431

MODELING THE AMES TEST  

EPA Science Inventory

Despite the value and widespread use of the Ames test, little attention has been focused on standardizing quantitative methods of analyzing these data. In this paper, a realistic and statistically tractable model is developed for the evaluation of Ames-type data. The model assume...

432

Modeling Internet topology  

Microsoft Academic Search

The topology of a network, or a group of networks such as the Internet, has a strong bearing on many management and performance issues. Good models of the topological structure of a network are essential for developing and analyzing internetworking technology. This article discusses how graph-based models can be used to represent the topology of large networks, particularly aspects of

K. I. Calvert; M. B. Doar; E. W. Zegura

1997-01-01

433

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

434

A Model for Implementation.  

ERIC Educational Resources Information Center

Describes the Constructural Multi-Modalities Model for MST (math, science, and technology) Inquiry Units. The MST Model uses an interdisciplinary and constructivist approach and allows teachers to create lesson plans that: integrate MST in tandem; adhere to local, state, and national standards; and actively engage students' differentiated learning…

O'Connor-Petruso, Sharon Anne

2003-01-01

435

Quark model spectroscopy  

Microsoft Academic Search

A general overview of quark models of hadrons is presented. Experiment results and theoretical attempts to explain the data are discussed. Bag models and pion clouds, hadron masses and baryon magnetic moments, quark clustering and NN interactions, and the GA\\/GV ratio are topics included in this review. (AIP)

Harry J. Lipkin; MARIA GOEPPERT-MAYER

1984-01-01

436

Make a Model Fossil  

NSDL National Science Digital Library

This activity is a combination outdoor/indoor lab where students will collect natural materials from the environment and use them to create both a mold and cast model of a fossil. Students will learn how a fossil is formed and why scientists use models to help them understand how things work and develop.

437

Modelling the Bicoid gradient  

PubMed Central

Morphogen gradients provide embryonic tissues with positional information by inducing target genes at different concentration thresholds and thus at different positions. The Bicoid morphogen gradient in Drosophila melanogaster embryos has recently been analysed quantitatively, yet how it forms remains a matter of controversy. Several biophysical models that rely on production, diffusion and degradation have been formulated to account for the observed dynamics of the Bicoid gradient, but no one model can account for all its characteristics. Here, we discuss how existing data on this gradient fit the various proposed models and what aspects of gradient formation these models fail to explain. We suggest that knowing a few additional parameters, such as the lifetime of Bicoid, would help to identify and develop better models of Bicoid gradient formation. PMID:20570935

Grimm, Oliver; Coppey, Mathieu; Wieschaus, Eric

2010-01-01

438

VENTILATION MODEL REPORT  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their postclosure analyses.

V. Chipman

2002-10-31

439

Linear models: permutation methods  

USGS Publications Warehouse

Permutation tests (see Permutation Based Inference) for the linear model have applications in behavioral studies when traditional parametric assumptions about the error term in a linear model are not tenable. Improved validity of Type I error rates can be achieved with properly constructed permutation tests. Perhaps more importantly, increased statistical power, improved robustness to effects of outliers, and detection of alternative distributional differences can be achieved by coupling permutation inference with alternative linear model estimators. For example, it is well-known that estimates of the mean in linear model are extremely sensitive to even a single outlying value of the dependent variable compared to estimates of the median [7, 19]. Traditionally, linear modeling focused on estimating changes in the center of distributions (means or medians). However, quantile regression allows distributional changes to be estimated in all or any selected part of a distribution or responses, providing a more complete statistical picture that has relevance to many biological questions [6]...

Cade, B.S.

2005-01-01

440

Varicella infection modeling.  

SciTech Connect

Infectious diseases can spread rapidly through healthcare facilities, resulting in widespread illness among vulnerable patients. Computational models of disease spread are useful for evaluating mitigation strategies under different scenarios. This report describes two infectious disease models built for the US Department of Veteran Affairs (VA) motivated by a Varicella outbreak in a VA facility. The first model simulates disease spread within a notional contact network representing staff and patients. Several interventions, along with initial infection counts and intervention delay, were evaluated for effectiveness at preventing disease spread. The second model adds staff categories, location, scheduling, and variable contact rates to improve resolution. This model achieved more accurate infection counts and enabled a more rigorous evaluation of comparative effectiveness of interventions.

Jones, Katherine A.; Finley, Patrick D.; Moore, Thomas W.; Nozick, Linda Karen; Martin, Nathaniel; Bandlow, Alisa; Detry, Richard Joseph; Evans, Leland B.; Berger, Taylor Eugen

2013-09-01

441

Strength Modeling Report  

NASA Technical Reports Server (NTRS)

Strength modeling is a complex and multi-dimensional issue. There are numerous parameters to the problem of characterizing human strength, most notably: (1) position and orientation of body joints; (2) isometric versus dynamic strength; (3) effector force versus joint torque; (4) instantaneous versus steady force; (5) active force versus reactive force; (6) presence or absence of gravity; (7) body somatotype and composition; (8) body (segment) masses; (9) muscle group envolvement; (10) muscle size; (11) fatigue; and (12) practice (training) or familiarity. In surveying the available literature on strength measurement and modeling an attempt was made to examine as many of these parameters as possible. The conclusions reached at this point toward the feasibility of implementing computationally reasonable human strength models. The assessment of accuracy of any model against a specific individual, however, will probably not be possible on any realistic scale. Taken statistically, strength modeling may be an effective tool for general questions of task feasibility and strength requirements.

Badler, N. I.; Lee, P.; Wong, S.

1985-01-01

442

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

443

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

444

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

445

Model simulates ocean conditions  

NASA Astrophysics Data System (ADS)

Researchers from the National Oceanic and Atmospheric Administration (NOAA) have developed a high-resolution general circulation computer model that has been used to simulate ocean conditions in the tropical Pacific. According to George Philander of NOAA's Geophysical Fluid Dynamics Laboratory in Princeton, N.J., the new model has been used in a “remarkably realistic” simulation of the 1982-1983 El Niño event, one of the most severe on record.The model accurately recreated sea surface temperatures at different stages of the El Niño event and provided simulated currents and subsurface temperatures in excellent agreement with those actually observed, Philander said. “The model is being run in real time, and for the first time provides us with a coherent picture of oceanic conditions in the Pacific.” Later this year, the new model will be transferred to NOAA's National Meteorological Center for operational use.

446

Modeling Vacuum Arcs  

E-print Network

We are developing a model of vacuum arcs. This model assumes that arcs develop as a result of mechanical failure of the surface due to Coulomb explosions, followed by ionization of fragments by field emission and the development of a small, dense plasma that interacts with the surface primarily through self sputtering and terminates as a unipolar arc capable of producing breakdown sites with high enhancement factors. We have attempted to produce a self consistent picture of triggering, arc evolution and surface damage. We are modeling these mechanisms using Molecular Dynamics (mechanical failure, Coulomb explosions, self sputtering), Particle-In-Cell (PIC) codes (plasma evolution), mesoscale surface thermodynamics (surface evolution), and finite element electrostatic modeling (field enhancements). We can present a variety of numerical results. We identify where our model differs from other descriptions of this phenomenon.

Insepov, Z; Proslier, T; Huang, D; Mahalingam, S; Veitzer, S

2010-01-01

447

Anisotropic Rabi model  

E-print Network

We define the anisotropic Rabi model as the generalization of the spin-boson Rabi model: The Hamiltonian system breaks the parity symmetry; the rotating and counter-rotating interactions are governed by two different coupling constants; a further parameter introduces a phase factor in the counter-rotating terms. The exact energy spectrum and eigenstates of the generalized model is worked out. The solution is obtained as an elaboration of a recent proposed method for the isotropic limit of the model. In this way, we provide a long sought solution of a cascade of models with immediate relevance in different physical fields, including i) quantum optics: two-level atom in single mode cross electric and magnetic fields; ii) solid state physics: electrons in semiconductors with Rashba and Dresselhaus spin-orbit coupling; iii) mesoscopic physics: Josephson junctions flux-qubit quantum circuits.

Qiong-Tao Xie; Shuai Cui; Jun-Peng Cao; Luigi Amico; Heng Fan

2014-05-20

448

Interactive Model Problem Set  

NSDL National Science Digital Library

The problem set asks students to complete and discuss interactive, policy-relevant models from two case studies of models and policy that have been previously discussed in class: fisheries and chemicals. The first question asks the students to play the online Fishbanks game, which uses a model interface to illustrate management strategies for fisheries. The students are then asked to think about how the model might be used in decision-making contexts. The second question asks students to consider the case of a chemical under review in the context of the Stockholm Convention on Persistent Organic Pollutants, and to assess its overall persistence and long-range transport using an Excel-based modeling tool.

Noelle Selin

449

Developing Climate Model Comparisons  

NASA Astrophysics Data System (ADS)

Since 1995, the worldwide climate modeling community has designed and participated in a series of intercomparison projects for the purposes of understanding and improving model performance, investigating scientific questions about the climate system, and projecting future climate conditions. These projects have been defined under the umbrella of the Coupled Model Intercomparison Project, and phase 6 of that project (CMIP6) is just getting under way. As in previous phases, many CMIP6 modeling activities interact and overlap with each other. For example, credible projections of future climate conditions require understanding and validating a variety of Earth system model responses, including those to changes in concentrations of greenhouse gases, aerosols and other air pollutants, and land use change.

O'Neill, Brian C.; Lamarque, Jean-Francois; Lawrence, David

2014-12-01

450

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

451

Modeling glacial climates  

NASA Technical Reports Server (NTRS)

Mathematical climate modelling has matured as a discipline to the point that it is useful in paleoclimatology. As an example a new two dimensional energy balance model is described and applied to several problems of current interest. The model includes the seasonal cycle and the detailed land-sea geographical distribution. By examining the changes in the seasonal cycle when external perturbations are forced upon the climate system it is possible to construct hypotheses about the origin of midlatitude ice sheets and polar ice caps. In particular the model predicts a rather sudden potential for glaciation over large areas when the Earth's orbital elements are only slightly altered. Similarly, the drift of continents or the change of atmospheric carbon dioxide over geological time induces radical changes in continental ice cover. With the advance of computer technology and improved understanding of the individual components of the climate system, these ideas will be tested in far more realistic models in the near future.

North, G. R.; Crowley, T. J.

1984-01-01

452

Maximally Expressive Task Modeling  

NASA Technical Reports Server (NTRS)

Planning and scheduling systems organize "tasks" into a timeline or schedule. The tasks are defined within the scheduling system in logical containers called models. The dictionary might define a model of this type as "a system of things and relations satisfying a set of rules that, when applied to the things and relations, produce certainty about the tasks that are being modeled." One challenging domain for a planning and scheduling system is the operation of on-board experiment activities for the Space Station. The equipment used in these experiments is some of the most complex hardware ever developed by mankind, the information sought by these experiments is at the cutting edge of scientific endeavor, and the procedures for executing the experiments are intricate and exacting. Scheduling is made more difficult by a scarcity of space station resources. The models to be fed into the scheduler must describe both the complexity of the experiments and procedures (to ensure a valid schedule) and the flexibilities of the procedures and the equipment (to effectively utilize available resources). Clearly, scheduling space station experiment operations calls for a "maximally expressive" modeling schema. Modeling even the simplest of activities cannot be automated; no sensor can be attached to a piece of equipment that can discern how to use that piece of equipment; no camera can quantify how to operate a piece of equipment. Modeling is a human enterprise-both an art and a science. The modeling schema should allow the models to flow from the keyboard of the user as easily as works of literature flowed from the pen of Shakespeare. The Ground Systems Department at the Marshall Space Flight Center has embarked on an effort to develop a new scheduling engine that is highlighted by a maximally expressive modeling schema. This schema, presented in this paper, is a synergy of technological advances and domain-specific innovations.

Japp, John; Davis, Elizabeth; Maxwell, Theresa G. (Technical Monitor)

2002-01-01

453

Saturn Radiation (SATRAD) Model  

NASA Technical Reports Server (NTRS)

The Saturnian radiation belts have not received as much attention as the Jovian radiation belts because they are not nearly as intense-the famous Saturnian particle rings tend to deplete the belts near where their peak would occur. As a result, there has not been a systematic development of engineering models of the Saturnian radiation environment for mission design. A primary exception is that of Divine (1990). That study used published data from several charged particle experiments aboard the Pioneer 1 1, Voyager 1, and Voyager 2 spacecraft during their flybys at Saturn to generate numerical models for the electron and proton radiation belts between 2.3 and 13 Saturn radii. The Divine Saturn radiation model described the electron distributions at energies between 0.04 and 10 MeV and the proton distributions at energies between 0.14 and 80 MeV. The model was intended to predict particle intensity, flux, and fluence for the Cassini orbiter. Divine carried out hand calculations using the model but never formally developed a computer program that could be used for general mission analyses. This report seeks to fill that void by formally developing a FORTRAN version of the model that can be used as a computer design tool for missions to Saturn that require estimates of the radiation environment around the planet. The results of that effort and the program listings are presented here along with comparisons with the original estimates carried out by Divine. In addition, Pioneer and Voyager data were scanned in from the original references and compared with the FORTRAN model s predictions. The results were statistically analyzed in a manner consistent with Divine s approach to provide estimates of the ability of the model to reproduce the original data. Results of a formal review of the model by a panel of experts are also presented. Their recommendations for further tests, analyses, and extensions to the model are discussed.

Garrett, H. B.; Ratliff, J. M.; Evans, R. W.

2005-01-01

454

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

455

Model predictive control with linear models  

SciTech Connect

This article discusses the existing linear model predictive control concepts in a unified theoretical framework based on a stabilizing, infinite horizon, linear quadratic regulator. In order to represent unstable as well as stable multivariable systems, the standard state-space formulation is used for the plant model. The incorporation of a nominally stabilizing constrained regulator eliminates the current requirement of tuning for nominal stability. Output feedback is addressed in the well-established framework of the linear quadratic state-estimation problem. This framework allows the flexibility to handle nonsquare systems, noisy inputs and outputs, and nonzero input, output, and state disturbances. This formulation subsumes the integral control schemes designed to remove steady-state offset currently in industrial use. The online implementation of the controller requires the solution of a standard quadratic program that is no more computationally intensive than existing algorithms.

Muske, K.R.; Rawlings, J.B. (Univ. of Texas, Austin (United States))

1993-02-01

456

Spiral model pilot project information model  

NASA Technical Reports Server (NTRS)

The objective was an evaluation of the Spiral Model (SM) development approach to allow NASA Marshall to develop an experience base of that software management methodology. A discussion is presented of the Information Model (IM) that was used as part of the SM methodology. A key concept of the SM is the establishment of an IM to be used by management to track the progress of a project. The IM is the set of metrics that is to be measured and reported throughout the life of the project. These metrics measure both the product and the process to ensure the quality of the final delivery item and to ensure the project met programmatic guidelines. The beauty of the SM, along with the IM, is the ability to measure not only the correctness of the specification and implementation of the requirements but to also obtain a measure of customer satisfaction.

1991-01-01

457

Modeling Cytomegalovirus Infection in Mouse Tumor Models  

PubMed Central

The hypothesis that cytomegalovirus (CMV) modulates cancer is evolving. Originally discovered in glioblastoma in 2002, the number of cancers, where intratumoral CMV antigen is detected, has increased in recent years suggesting that CMV actively affects the pathobiology of certain tumors. These findings are controversial as several groups have also reported inability to replicate these results. Regardless, several clinical trials for glioblastoma are underway or have been completed that target intratumoral CMV with anti-viral drugs or immunotherapy. Therefore, a better understanding of the possible pathobiology of CMV in cancer needs to be ascertained. We have developed genetic, syngeneic, and orthotopic malignant glioma mouse models to study the role of CMV in cancer development and progression. These models recapitulate for the most part intratumoral CMV expression as seen in human tumors. Additionally, we discovered that CMV infection in Trp53?/+ mice promotes pleomorphic rhabdomyosarcomas. These mouse models are not only a vehicle for studying pathobiology of the viral-tumor interaction but also a platform for developing and testing cancer therapeutics.

Price, Richard Lee; Chiocca, Ennio Antonio

2015-01-01

458

Expert Models and Modeling Processes Associated with a Computer-Modeling Tool  

ERIC Educational Resources Information Center

Holding the premise that the development of expertise is a continuous process, this study concerns expert models and modeling processes associated with a modeling tool called Model-It. Five advanced Ph.D. students in environmental engineering and public health used Model-It to create and test models of water quality. Using "think aloud" technique…

Zhang, BaoHui; Liu, Xiufeng; Krajcik, Joseph S.

2006-01-01

459

Meshfree magnetotelluric modelling  

NASA Astrophysics Data System (ADS)

We present a new approach for 2-D magnetotelluric forward numerical modelling in contrast to traditional numerical methods like finite elements or finite differences. The method used for solving the partial differential equations is based on a mesh-free technique which does not need an underlaying mesh or grid. We use the Meshless Local Petrov-Galerkin (MLPG) method in combination with radial basis functions to simulate the response of a given conductivity model to a plane-wave source. We compare the mesh-free solution with known simulation programs and simple analytical solutions. Furthermore, we discuss the new magnetotelluric modelling method in terms of implementation and stability. First, we study the convergence and discretization errors of the new method with a simple half-space conductivity model. Then we compare our mesh-free simulation results with simple 2-D conductivity models with the results of a well-known finite element program. In the end, we provide a smooth conductivity model calculated with the mesh-free approach. The modelling results, even with randomly distributed nodes, are in a good agreement with those obtained by the finite element method.

Wittke, J.; Tezkan, B.

2014-08-01

460

Functional Generalized Additive Models.  

PubMed

We introduce the functional generalized additive model (FGAM), a novel regression model for association studies between a scalar response and a functional predictor. We model the link-transformed mean response as the integral with respect to t of F{X(t), t} where F(·,·) is an unknown regression function and X(t) is a functional covariate. Rather than having an additive model in a finite number of principal components as in Müller and Yao (2008), our model incorporates the functional predictor directly and thus our model can be viewed as the natural functional extension of generalized additive models. We estimate F(·,·) using tensor-product B-splines with roughness penalties. A pointwise quantile transformation of the functional predictor is also considered to ensure each tensor-product B-spline has observed data on its support. The methods are evaluated using simulated data and their predictive performance is compared with other competing scalar-on-function regression alternatives. We illustrate the usefulness of our approach through an application to brain tractography, where X(t) is a signal from diffusion tensor imaging at position, t, along a tract in the brain. In one example, the response is disease-status (case or control) and in a second example, it is the score on a cognitive test. R code for performing the simulations and fitting the FGAM can be found in supplemental materials available online. PMID:24729671

McLean, Mathew W; Hooker, Giles; Staicu, Ana-Maria; Scheipl, Fabian; Ruppert, David

2014-01-01

461

Computationally modeling interpersonal trust  

PubMed Central

We present a computational model capable of predicting—above human accuracy—the degree of trust a person has toward their novel partner by observing the trust-related nonverbal cues expressed in their social interaction. We summarize our prior work, in which we identify nonverbal cues that signal untrustworthy behavior and also demonstrate the human mind's readiness to interpret those cues to assess the trustworthiness of a social robot. We demonstrate that domain knowledge gained from our prior work using human-subjects experiments, when incorporated into the feature engineering process, permits a computational model to outperform both human predictions and a baseline model built in naiveté of this domain knowledge. We then present the construction of hidden Markov models to investigate temporal relationships among the trust-related nonverbal cues. By interpreting the resulting learned structure, we observe that models built to emulate different levels of trust exhibit different sequences of nonverbal cues. From this observation, we derived sequence-based temporal features that further improve the accuracy of our computational model. Our multi-step research process presented in this paper combines the strength of experimental manipulation and machine learning to not only design a computational trust model but also to further our understanding of the dynamics of interpersonal trust. PMID:24363649

Lee, Jin Joo; Knox, W. Bradley; Wormwood, Jolie B.; Breazeal, Cynthia; DeSteno, David

2013-01-01

462

Functional Generalized Additive Models  

PubMed Central

We introduce the functional generalized additive model (FGAM), a novel regression model for association studies between a scalar response and a functional predictor. We model the link-transformed mean response as the integral with respect to t of F{X(t), t} where F(·,·) is an unknown regression function and X(t) is a functional covariate. Rather than having an additive model in a finite number of principal components as in Müller and Yao (2008), our model incorporates the functional predictor directly and thus our model can be viewed as the natural functional extension of generalized additive models. We estimate F(·,·) using tensor-product B-splines with roughness penalties. A pointwise quantile transformation of the functional predictor is also considered to ensure each tensor-product B-spline has observed data on its support. The methods are evaluated using simulated data and their predictive performance is compared with other competing scalar-on-function regression alternatives. We illustrate the usefulness of our approach through an application to brain tractography, where X(t) is a signal from diffusion tensor imaging at position, t, along a tract in the brain. In one example, the response is disease-status (case or control) and in a second example, it is the score on a cognitive test. R code for performing the simulations and fitting the FGAM can be found in supplemental materials available online. PMID:24729671

McLean, Mathew W.; Hooker, Giles; Staicu, Ana-Maria; Scheipl, Fabian; Ruppert, David

2014-01-01

463

Model molecules mimicking asphaltenes.  

PubMed

Asphalthenes are typically defined as the fraction of petroleum insoluble in n-alkanes (typically heptane, but also hexane or pentane) but soluble in toluene. This fraction causes problems of emulsion formation and deposition/precipitation during crude oil production, processing and transport. From the definition it follows that asphaltenes are not a homogeneous fraction but is composed of molecules polydisperse in molecular weight, structure and functionalities. Their complexity makes the understanding of their properties difficult. Proper model molecules with well-defined structures which can resemble the properties of real asphaltenes can help to improve this understanding. Over the last ten years different research groups have proposed different asphaltene model molecules and studied them to determine how well they can mimic the properties of asphaltenes and determine the mechanisms behind the properties of asphaltenes. This article reviews the properties of the different classes of model compounds proposed and present their properties by comparison with fractionated asphaltenes. After presenting the interest of developing model asphaltenes, the composition and properties of asphaltenes are presented, followed by the presentation of approaches and accomplishments of different schools working on asphaltene model compounds. The presentation of bulk and interfacial properties of perylene-based model asphaltene compounds developed by Sjöblom et al. is the subject of the next part. Finally the emulsion-stabilization properties of fractionated asphaltenes and model asphaltene compounds is presented and discussed. PMID:25638443

Sjöblom, Johan; Simon, Sébastien; Xu, Zhenghe

2015-04-01

464

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

465

SPAR Model Structural Efficiencies  

SciTech Connect

The Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) are supporting initiatives aimed at improving the quality of probabilistic risk assessments (PRAs). Included in these initiatives are the resolution of key technical issues that are have been judged to have the most significant influence on the baseline core damage frequency of the NRC’s Standardized Plant Analysis Risk (SPAR) models and licensee PRA models. Previous work addressed issues associated with support system initiating event analysis and loss of off-site power/station blackout analysis. The key technical issues were: • Development of a standard methodology and implementation of support system initiating events • Treatment of loss of offsite power • Development of standard approach for emergency core cooling following containment failure Some of the related issues were not fully resolved. This project continues the effort to resolve outstanding issues. The work scope was intended to include substantial collaboration with EPRI; however, EPRI has had other higher priority initiatives to support. Therefore this project has addressed SPAR modeling issues. The issues addressed are • SPAR model transparency • Common cause failure modeling deficiencies and approaches • Ac and dc modeling deficiencies and approaches • Instrumentation and control system modeling deficiencies and approaches

John Schroeder; Dan Henry

2013-04-01

466

Acute radiation risk models  

NASA Astrophysics Data System (ADS)

Biologically motivated mathematical models, which describe the dynamics of the major hematopoietic lineages (the thrombocytopoietic, lymphocytopoietic, granulocytopoietic, and erythropoietic systems) in acutely/chronically irradiated humans are developed. These models are implemented as systems of nonlinear differential equations, which variables and constant parameters have clear biological meaning. It is shown that the developed models are capable of reproducing clinical data on the dynamics of these systems in humans exposed to acute radiation in the result of incidents and accidents, as well as in humans exposed to low-level chronic radiation. Moreover, the averaged value of the "lethal" dose rates of chronic irradiation evaluated within models of these four major hematopoietic lineages coincides with the real minimal dose rate of lethal chronic irradiation. The demonstrated ability of the models of the human thrombocytopoietic, lymphocytopoietic, granulocytopoietic, and erythropoietic systems to predict the dynamical response of these systems to acute/chronic irradiation in wide ranges of doses and dose rates implies that these mathematical models form an universal tool for the investigation and prediction of the dynamics of the major human hematopoietic lineages for a vast pattern of irradiation scenarios. In particular, these models could be applied for the radiation risk assessment for health of astronauts exposed to space radiation during long-term space missions, such as voyages to Mars or Lunar colonies, as well as for health of people exposed to acute/chronic irradiation due to environmental radiological events.

Smirnova, Olga

467

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

468

VPPA weld model evaluation  

NASA Technical Reports Server (NTRS)

NASA uses the Variable Polarity Plasma Arc Welding (VPPAW) process extensively for fabrication of Space Shuttle External Tanks. This welding process has been in use at NASA since the late 1970's but the physics of the process have never been satisfactorily modeled and understood. In an attempt to advance the level of understanding of VPPAW, Dr. Arthur C. Nunes, Jr., (NASA) has developed a mathematical model of the process. The work described in this report evaluated and used two versions (level-0 and level-1) of Dr. Nunes' model, and a model derived by the University of Alabama at Huntsville (UAH) from Dr. Nunes' level-1 model. Two series of VPPAW experiments were done, using over 400 different combinations of welding parameters. Observations were made of VPPAW process behavior as a function of specific welding parameter changes. Data from these weld experiments was used to evaluate and suggest improvements to Dr. Nunes' model. Experimental data and correlations with the model were used to develop a multi-variable control algorithm for use with a future VPPAW controller. This algorithm is designed to control weld widths (both on the crown and root of the weld) based upon the weld parameters, base metal properties, and real-time observation of the crown width. The algorithm exhibited accuracy comparable to that of the weld width measurements for both aluminum and mild steel welds.

Mccutcheon, Kimble D.; Gordon, Stephen S.; Thompson, Paul A.

1992-01-01

469

Modeling defibrillation electrode performance.  

PubMed

A Boundary Element (BE) model was developed of the electric potential field in the heart arising from electric potentials applied on implanted defibrillator electrodes. The model solved Laplace's equation for potential and was implemented using the BE method with realistic torso structures. An efficient out-of-core solver was developed, allowing any size problem to be solved, subject only to computer speed and time available. A method was also developed that allowed matrices calculated in one problem to be used in other, similar problems, often reducing calculation times by an order of magnitude. Model validation included comparison with myocardial potentials from a finite element model and clinically found voltage and resistance at defibrillation threshold from 29 patients. The model was used in investigations of transvenous electrode configurations, with potential found for reduction in defibrillation voltage and energy. The BE model was successful in modelling the electric field in the torso, in predicting implantable defibrillator performance and in finding application in electrode performance studies. PMID:17281079

Gale, Timothy

2005-01-01

470

Computationally modeling interpersonal trust.  

PubMed

We present a computational model capable of predicting-above human accuracy-the degree of trust a person has toward their novel partner by observing the trust-related nonverbal cues expressed in their social interaction. We summarize our prior work, in which we identify nonverbal cues that signal untrustworthy behavior and also demonstrate the human mind's readiness to interpret those cues to assess the trustworthiness of a social robot. We demonstrate that domain knowledge gained from our prior work using human-subjects experiments, when incorporated into the feature engineering process, permits a computational model to outperform both human predictions and a baseline model built in naiveté of this domain knowledge. We then present the construction of hidden Markov models to investigate temporal relationships among the trust-related nonverbal cues. By interpreting the resulting learned structure, we observe that models built to emulate different levels of trust exhibit different sequences of nonverbal cues. From this observation, we derived sequence-based temporal features that further improve the accuracy of our computational model. Our multi-step research process presented in this paper combines the strength of experimental manipulation and machine learning to not only design a computational trust model but also to further our understanding of the dynamics of interpersonal trust. PMID:24363649

Lee, Jin Joo; Knox, W Bradley; Wormwood, Jolie B; Breazeal, Cynthia; Desteno, David

2013-01-01

471

Turbulence Modeling Workshop  

NASA Technical Reports Server (NTRS)

Advances in turbulence modeling are needed in order to calculate high Reynolds number flows near the onset of separation and beyond. To this end, the participants in this workshop made the following recommendations. (1) A national/international database and standards for turbulence modeling assessment should be established. Existing experimental data sets should be reviewed and categorized. Advantage should be taken of other efforts already under-way, such as that of the European Research Community on Flow, Turbulence, and Combustion (ERCOFTAC) consortium. Carefully selected "unit" experiments will be needed, as well as advances in instrumentation, to fill the gaps in existing datasets. A high priority should be given to document existing turbulence model capabilities in a standard form, including numerical implementation issues such as grid quality and resolution. (2) NASA should support long-term research on Algebraic Stress Models and Reynolds Stress Models. The emphasis should be placed on improving the length-scale equation, since it is the least understood and is a key component of two-equation and higher models. Second priority should be given to the development of improved near-wall models. Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) would provide valuable guidance in developing and validating new Reynolds-averaged Navier-Stokes (RANS) models. Although not the focus of this workshop, DNS, LES, and hybrid methods currently represent viable approaches for analysis on a limited basis. Therefore, although computer limitations require the use of RANS methods for realistic configurations at high Reynolds number in the foreseeable future, a balanced effort in turbulence modeling development, validation, and implementation should include these approaches as well.

Rubinstein, R. (Editor); Rumsey, C. L. (Editor); Salas, M. D. (Editor); Thomas, J. L. (Editor); Bushnell, Dennis M. (Technical Monitor)

2001-01-01

472

Model compilation: An approach to automated model derivation  

NASA Technical Reports Server (NTRS)

An approach is introduced to automated model derivation for knowledge based systems. The approach, model compilation, involves procedurally generating the set of domain models used by a knowledge based system. With an implemented example, how this approach can be used to derive models of different precision and abstraction is illustrated, and models are tailored to different tasks, from a given set of base domain models. In particular, two implemented model compilers are described, each of which takes as input a base model that describes the structure and behavior of a simple electromechanical device, the Reaction Wheel Assembly of NASA's Hubble Space Telescope. The compilers transform this relatively general base model into simple task specific models for troubleshooting and redesign, respectively, by applying a sequence of model transformations. Each transformation in this sequence produces an increasingly more specialized model. The compilation approach lessens the burden of updating and maintaining consistency among models by enabling their automatic regeneration.

Keller, Richard M.; Baudin, Catherine; Iwasaki, Yumi; Nayak, Pandurang; Tanaka, Kazuo

1990-01-01

473

Improved steamflood analytical model  

E-print Network

?????????????????????????........ 22 Fig. 3.5 Active and inactive cells in a 1/8 five-spot pattern model?????? 23 Fig. 3.6 Simulation grid for area of 2.5 ac, SPE comparative case model???. 25 Fig. 3.7 Simulation grid for area of 5.0 ac, SPE comparative case model???. 26 Fig. 3... Skk (3.5) The residual oil saturation (water/oil system) Sorw = 0.15, the residual oil saturation (gas oil system), Sorg = 0.10, and the critical gas saturation, Sgc = 0.06. Oil relative permeability at interstitial water saturation, kroiw...

Chandra, Suandy

2006-10-30

474

Vesta thermal models  

NASA Astrophysics Data System (ADS)

Vesta thermal evolution and structural models are compared. These models, based on decay of 26Al, 60Fe and long-lived radionuclides (40K, 232Th, 235U and 238U), differ for the delay in injection (Delta td) of 26Al by the nebula in which Vesta was formed. In all models we can see the pristine formation of a metallic core followed by the differentiation of silicatic mantle and we can observe the evolution of the crust. This is in preparation of the Dawn mission that will provide us with constraints on the crust thickness and composition of the crust and underlying mantle.

Formisano, M.; Federico, C.; Coradini, A.

475

Model Course: Security +  

NSDL National Science Digital Library

This site includes a model course from the CyberWatch Center. The site does not currently include any educational materials, but does provide a model framework for structuring a course on this topic. This course would cover the current risks to electronic data, as well as a structured way to address security problems. The course would provide a good starting point for students going on to study specialized security. A detailed course outline is included. Users must register to view the model course, but registration is free and easy.

476

Dynamic hysteresis modelling  

NASA Astrophysics Data System (ADS)

A viscous-type dynamic hysteresis model (DHM) is developed. The DHM is compatible with static underlying model of any type and nature (Preisach or non-Preisach). The distinguishing features of the DHM are its arbitrary frequency dependence and the ability to control the shape of the dynamic hysteresis loop. The numerical method for the incorporation of the DHM in magnetodynamic computations is illustrated by a good agreement of modelled dynamic loops with measured loops of non-oriented and grain-oriented electrical steels.

Zirka, S. E.; Moroz, Y. I.; Marketos, P.; Moses, A. J.

2004-01-01

477

Nonlocal quark model  

SciTech Connect

A nonlocal quark model is described. Quarks are described by a virton field, existing as virtual states only. Hadrons are described by standard quantized fields and have experimentally observable masses. Hadrons are bound states of quarks. The model satisfies all axioms of relativistic quantum field theory and does not contain ultraviolet divergences. Hadron-quark interaction Lagrangians are introduced. The strong, electromagnetic, and weak decays of the pseudoscalar and vector mesons as well as the baryon octet and decuplet are considered. The model contains only two free parameters, which characterize the quark field. Good agreement with the experimental data is obtained.

Efimov, G.V.; Ivanov, M.A.

1981-09-01

478

Tetrade Spin Foam Model  

E-print Network

We propose a spin foam model of four-dimensional quantum gravity which is based on the integration of the tetrads in the path integral for the Palatini action of General Relativity. In the Euclidian gravity case we show that the model can be understood as a modification of the Barrett-Crane spin foam model. Fermionic matter can be coupled by using the path integral with sources for the tetrads and the spin connection, and the corresponding state sum is based on a spin foam where both the edges and the faces are colored independently with the irreducible representations of the spacetime rotations group.

A. Mikovic

2005-04-26

479

DNA Jewelry Models  

NSDL National Science Digital Library

Making DNA Jewelry Models is a portion of a unit on molecular genetics. Using the directions for this hands-on activity/lab helps students construct a model of DNA to learn DNA structure and decode it to better understand protein synthesis. They also have an actual badge of their DNA literacy to wear or use. Whether a key ring, earrings, bracelet, or necklace, students from fourth grade through adult can do and enjoy this activity. (Even visually impaired students made a model using larger beads.)

BEGIN:VCARD VERSION:2.1 FN:Catherine Sheils Ross N:Sheils Ross; Catherine ORG:Berkley High School (retired-6/98) REV:2005-04-09 END:VCARD

1995-06-30

480

Structural Model of Eumelanin  

NASA Astrophysics Data System (ADS)

Melanin is a ubiquitous pigment in living organisms with multiple important functions, yet its structure is not well understood. We propose a structural model for eumelanin protomolecules, consisting of 4 or 5 of the basic molecular units (hydroquinone, indolequinone, and its tautomers), in arrangements that contain an inner porphyrin ring. We use time-dependent density functional theory to calculate the optical absorption spectrum of the structural model, which reproduces convincingly the main features of the experimental spectrum of eumelanin. Our model also reproduces accurately other important properties of eumelanin, including x-ray scattering data, its ability to capture and release metal ions, and the characteristic size of the protomolecules.

Kaxiras, Efthimios; Tsolakidis, Argyrios; Zonios, George; Meng, Sheng

2006-11-01

481

Modeling EERE Deployment Programs  

SciTech Connect

The purpose of this report is to compile information and conclusions gathered as part of three separate tasks undertaken as part of the overall project, “Modeling EERE Deployment Programs,” sponsored by the Planning, Analysis, and Evaluation office within the Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE). The purpose of the project was to identify and characterize the modeling of deployment programs within the EERE Technology Development (TD) programs, address improvements to modeling in the near term, and note gaps in knowledge where future research is needed.

Cort, Katherine A.; Hostick, Donna J.; Belzer, David B.; Livingston, Olga V.

2007-11-08

482

Lie 2-algebra models  

NASA Astrophysics Data System (ADS)

In this paper, we begin the study of zero-dimensional field theories with fields taking values in a semistrict Lie 2-algebra. These theories contain the IKKT matrix model and various M-brane related models as special cases. They feature solutions that can be interpreted as quantized 2-plectic manifolds. In particular, we find solutions corresponding to quantizations of 3, S 3 and a five-dimensional Hpp-wave. Moreover, by expanding a certain class of Lie 2-algebra models around the solution corresponding to quantized 3, we obtain higher BF-theory on this quantized space.

Ritter, Patricia; Sämann, Christian

2014-04-01

483

Modeling dihadron fragmentation functions  

E-print Network

We present a model for dihadron fragmentation functions, describing the fragmentation of a quark into two unpolarized hadrons. We tune the parameters of our model to the output of the PYTHIA event generator for two-hadron semi-inclusive production in deep inelastic scattering at HERMES. Once the parameters of the model are fixed, we make predictions for other unknown fragmentation functions and for a single-spin asymmetry in the azimuthal distribution of pi+ pi- pairs in semi-inclusive deep inelastic scattering on a transversely polarized target at HERMES and COMPASS. Such asymmetry could be used to measure the quark transversity distribution function.

Alessandro Bacchetta; Marco Radici

2006-08-03

484

Modeling Undertow Velocities  

NASA Astrophysics Data System (ADS)

The paper will present a theoretical model for the prediction of undertow velocity profiles in the surf zone due to near-normally incident waves. The waves may be periodic or narrow-banded random waves, and the beach may be plane or barred. The theoretical model consists of three components: (i) breaking wave model; (ii) surface roller model; and (iii) undertow velocity profile model. \\textit{The breaking wave model} (Tajima and Madsen, 2002) is based on the concept of an equivalent linear wave and predicts linear wave characteristics for shoaling, breaking and broken waves. Non-linear wave characteristics, e.g., near-bottom orbital velocity, are obtained from equivalent linear wave characteristics and local bottom slope through use of simple transform formulae. \\textit{The surface roller model} is based on the same principle as Dally et al. (1985), but differs from this by transferring only the potential energy lost from the wave motion into the surface roller and calculating the decay of surface roller energy using a decay coefficient equal to that obtained for the breaking wave dissipation model. \\textit{The undertow velocity profile model} assumes a linearly varying shear stress over the water depth combined with an assumed form of the turbulent eddy viscosity. The shear stress at the surface is obtained from the breaking wave and surface roller models, whereas the bottom shear stress is obtained from considerations of mass conservation, i.e., depth-integrated undertow velocity must equal the volume transport of waves and surface roller above trough level. The near-bottom undertow velocity is calculated at the edge of the wave-bottom boundary layer, from knowledge of near-bottom orbital velocity, bottom shear stress and bottom roughness, using the combined wave-current bottom boundary layer theory by Madsen (1994). Comparison of predicted and measured undertow velocity profiles are performed for periodic and random waves normally incident on plane and barred concrete beaches as well as random waves near-normally incident on barred movable bed beach profiles. In general the agreement between predicted and observed undertow velocities is excellent. It is shown that model predictions are fairly insensitive to the choice of turbulent eddy viscosity, which is the only adjustable quantity in the model.

Tajima, Y.; Madsen, O. S.

2002-12-01

485

Dynamical model for thyroid  

NASA Astrophysics Data System (ADS)

Thyroid's main chemical reactions are employed to develop a mathematical model. The presented model is based on differential equations where their dynamics reflects many aspects of thyroid's behavior. Our main focus here is the well known, but not well understood, phenomenon so called as Wolff-Chaikoff effect. It is shown that the inhibitory effect of intake iodide on the rate of one single enzyme causes a similar effect as Wolff-Chaikoff. Besides this issue, the presented model is capable of revealing other complex phenomena of thyroid hormones homeostasis.

Rokni Lamooki, Gholam Reza; Shirazi, Amir H.; Mani, Ali R.

2015-05-01

486

Animal Model of Dermatophytosis  

PubMed Central

Dermatophytosis is superficial fungal infection caused by dermatophytes that invade the keratinized tissue of humans and animals. Lesions from dermatophytosis exhibit an inflammatory reaction induced to eliminate the invading fungi by using the host's normal immune function. Many scientists have attempted to establish an experimental animal model to elucidate the pathogenesis of human dermatophytosis and evaluate drug efficacy. However, current animal models have several issues. In the present paper, we surveyed reports about the methodology of the dermatophytosis animal model for tinea corporis, tinea pedis, and tinea unguium and discussed future prospects. PMID:22619489

Shimamura, Tsuyoshi; Kubota, Nobuo; Shibuya, Kazutoshi

2012-01-01

487

Stochastic ontogenetic growth model  

NASA Astrophysics Data System (ADS)

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). This is the first derivation of the interspecies metabolic allometric relation from a dynamical model and the asymptotic steady-state distribution of the TBM is fit to data and shown to be inverse power law.

West, B. J.; West, D.

2012-02-01

488

Atmospheric and Oceanic Modeling  

NSDL National Science Digital Library

The numerical methods, formulation and parameterizations used in models of the circulation of the atmosphere and ocean will be described in detail. Widely used numerical methods will be the focus but we will also review emerging concepts and new methods. The numerics underlying a hierarchy of models will be discussed, ranging from simple GFD models to the high-end GCMs. In the context of ocean GCMs, we will describe parameterization of geostrophic eddies, mixing and the surface and bottom boundary layers. In the atmosphere, we will review parameterizations of convection and large scale condensation, the planetary boundary layer and radiative transfer.

Adcroft, Alistair

489

Temperature Dependent Pspice Model  

SciTech Connect

This paper provides a behavioral model in Pspice for a silicon carbide (SiC) power MOSFET rated at 1200 V / 20 A for a wide temperature range. The Pspice model is built using device parameters extracted through experiment. The static and dynamic behavior of the SiC power MOSFET is simulated and compared to the measured data to show the accuracy of the Pspice model. The switching losses are obtained from experiment under multiple operation conditions. The temperature dependent behavior has been simulated and analyzed. Then the parasitics in the circuit have been studied and the effects on the switching behavior are simulated and discussed.

Tolbert, Leon M [ORNL; Cui, Yutian [ORNL; Chinthavali, Madhu Sudhan [ORNL

2012-01-01

490

TUTORIAL: Validating biorobotic models  

NASA Astrophysics Data System (ADS)

Some issues in neuroscience can be addressed by building robot models of biological sensorimotor systems. What we can conclude from building models or simulations, however, is determined by a number of factors in addition to the central hypothesis we intend to test. These include the way in which the hypothesis is represented and implemented in simulation, how the simulation output is interpreted, how it is compared to the behaviour of the biological system, and the conditions under which it is tested. These issues will be illustrated by discussing a series of robot models of cricket phonotaxis behaviour. .

Webb, Barbara

2006-09-01

491

Modeling Compressed Turbulence  

SciTech Connect

From ICE to ICF, the effect of mean compression or expansion is important for predicting the state of the turbulence. When developing combustion models, we would like to know the mix state of the reacting species. This involves density and concentration fluctuations. To date, research has focused on the effect of compression on the turbulent kinetic energy. The current work provides constraints to help development and calibration for models of species mixing effects in compressed turbulence. The Cambon, et al., re-scaling has been extended to buoyancy driven turbulence, including the fluctuating density, concentration, and temperature equations. The new scalings give us helpful constraints for developing and validating RANS turbulence models.

Israel, Daniel M. [Los Alamos National Laboratory

2012-07-13

492

Component-specific modeling  

NASA Technical Reports Server (NTRS)

Accomplishments are described for the second year effort of a 3-year program to develop methodology for component specific modeling of aircraft engine hot section components (turbine blades, turbine vanes, and burner liners). These accomplishments include: (1) engine thermodynamic and mission models; (2) geometry model generators; (3) remeshing; (4) specialty 3-D inelastic stuctural analysis; (5) computationally efficient solvers, (6) adaptive solution strategies; (7) engine performance parameters/component response variables decomposition and synthesis; (8) integrated software architecture and development, and (9) validation cases for software developed.

Mcknight, R. L.

1985-01-01

493

MSIS-86 thermospheric model  

NASA Astrophysics Data System (ADS)

The MSIS-86 empirical model of thermospheric temperature, density and composition uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over that in the MSIS-83 model. Terms were added or changed to better represent seasonal variations in the polar regions under both quiet and magnetically disturbed conditions. Local time variations in the magnetic activity effect were added. In addition a new species, atomic nitrogen, was added to the previous list of N2, O2, He, O, H, and Ar covered by the model.

Hedin, Alan E.

1987-05-01

494

MSIS-86 thermospheric model  

NASA Technical Reports Server (NTRS)

The MSIS-86 empirical model of thermospheric temperature, density and composition uses new temperature and composition data from the Dynamics Explorer satellite to improve the representation of polar region morphology over that in the MSIS-83 model. Terms were added or changed to better represent seasonal variations in the polar regions under both quiet and magnetically disturbed conditions. Local time variations in the magnetic activity effect were added. In addition a new species, atomic nitrogen, was added to the previous list of N2, O2, He, O, H, and Ar covered by the model.

Hedin, Alan E.

1987-01-01

495

Battery performance models in ADVISOR  

Microsoft Academic Search

This paper summarizes battery modeling capabilities in ADVISOR—the National Renewable Energy Laboratory’s advanced vehicle simulator written in the Matlab\\/Simulink environment. ADVISOR’s Matlab-oriented battery models consist of the following: (1) an internal resistance model, (2) a resistance–capacitance (RC) model, (3) a PNGV capacitance model, (4) a neural network (nnet) lead acid model, and (5) a fundamental lead acid battery model. For

V. H. Johnson

2002-01-01

496

Climate and atmospheric modeling studies  

NASA Technical Reports Server (NTRS)

The climate and atmosphere modeling research programs have concentrated on the development of appropriate atmospheric and upper ocean models, and preliminary applications of these models. Principal models are a one-dimensional radiative-convective model, a three-dimensional global model, and an upper ocean model. Principal applications were the study of the impact of CO2, aerosols, and the solar 'constant' on climate.

1992-01-01

497

A High Precision Prediction Model Using Hybrid Grey Dynamic Model  

ERIC Educational Resources Information Center

In this paper, we propose a new prediction analysis model which combines the first order one variable Grey differential equation Model (abbreviated as GM(1,1) model) from grey system theory and time series Autoregressive Integrated Moving Average (ARIMA) model from statistics theory. We abbreviate the combined GM(1,1) ARIMA model as ARGM(1,1)…

Li, Guo-Dong; Yamaguchi, Daisuke; Nagai, Masatake; Masuda, Shiro

2008-01-01

498

Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models  

ERIC Educational Resources Information Center

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[subscript nu]"-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider…

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

2011-01-01

499

Image modeling and enhancement via structured sparse model selection  

Microsoft Academic Search

An image representation framework based on structured sparse model selection is introduced in this work. The corresponding modeling dictionary is comprised of a family of learned orthogonal bases. For an image patch, a model is first selected from this dictionary through linear approximation in a best basis, and the signal estimation is then calculated with the selected model. The model

Guoshen Yu; Guillermo Sapiro; Stéphane Mallat

2010-01-01

500

Hidden Markov Models in Computational Biology: Applications to Protein Modeling  

E-print Network

Hidden Markov Models in Computational Biology: Applications to Protein Modeling UCSC-CRL-93: krogh@nordig.ei.dth.dk, haussler@cse.ucsc.edu August 17, 1993 Keywords: Hidden Markov Models, Multiple biology. In this paper, we apply hidden Markov models (HMMs) to the problems of statistical modeling

Moriyama, Etsuko