Electrokinetics Models for Micro and Nano Fluidic Impedance Sensors

DTIC Science & Technology

2010-11-01

primitive Differential-Algebraic Equations (DAEs), used to process and interpret the experimentally measured electrical impedance data (Sun and Morgan...field, and species respectively. A second-order scheme was used to calculate the ionic species distribution. The linearized algebraic equations were...is governed by the Poisson equation 2 0 0 r i i i F z cε ε φ∇ + =∑ where ε0 and εr are, respectively, the electrical permittivity in the vacuum

Deep circulations under simple classes of stratification

NASA Technical Reports Server (NTRS)

Salby, Murry L.

1989-01-01

Deep circulations where the motion field is vertically aligned over one or more scale heights are studied under barotropic and equivalent barotropic stratifications. The study uses two-dimensional equations reduced from the three-dimensional primitive equations in spherical geometry. A mapping is established between the full primitive equations and general shallow water behavior and the correspondence between variables describing deep atmospheric motion and those of shallow water behavior is established.

A direct Primitive Variable Recovery Scheme for hyperbolic conservative equations: The case of relativistic hydrodynamics.

PubMed

Aguayo-Ortiz, A; Mendoza, S; Olvera, D

2018-01-01

In this article we develop a Primitive Variable Recovery Scheme (PVRS) to solve any system of coupled differential conservative equations. This method obtains directly the primitive variables applying the chain rule to the time term of the conservative equations. With this, a traditional finite volume method for the flux is applied in order avoid violation of both, the entropy and "Rankine-Hugoniot" jump conditions. The time evolution is then computed using a forward finite difference scheme. This numerical technique evades the recovery of the primitive vector by solving an algebraic system of equations as it is often used and so, it generalises standard techniques to solve these kind of coupled systems. The article is presented bearing in mind special relativistic hydrodynamic numerical schemes with an added pedagogical view in the appendix section in order to easily comprehend the PVRS. We present the convergence of the method for standard shock-tube problems of special relativistic hydrodynamics and a graphical visualisation of the errors using the fluctuations of the numerical values with respect to exact analytic solutions. The PVRS circumvents the sometimes arduous computation that arises from standard numerical methods techniques, which obtain the desired primitive vector solution through an algebraic polynomial of the charges.

A direct Primitive Variable Recovery Scheme for hyperbolic conservative equations: The case of relativistic hydrodynamics

PubMed Central

Mendoza, S.; Olvera, D.

2018-01-01

In this article we develop a Primitive Variable Recovery Scheme (PVRS) to solve any system of coupled differential conservative equations. This method obtains directly the primitive variables applying the chain rule to the time term of the conservative equations. With this, a traditional finite volume method for the flux is applied in order avoid violation of both, the entropy and “Rankine-Hugoniot” jump conditions. The time evolution is then computed using a forward finite difference scheme. This numerical technique evades the recovery of the primitive vector by solving an algebraic system of equations as it is often used and so, it generalises standard techniques to solve these kind of coupled systems. The article is presented bearing in mind special relativistic hydrodynamic numerical schemes with an added pedagogical view in the appendix section in order to easily comprehend the PVRS. We present the convergence of the method for standard shock-tube problems of special relativistic hydrodynamics and a graphical visualisation of the errors using the fluctuations of the numerical values with respect to exact analytic solutions. The PVRS circumvents the sometimes arduous computation that arises from standard numerical methods techniques, which obtain the desired primitive vector solution through an algebraic polynomial of the charges. PMID:29659602

Three dimensional thermal pollution models. Volume 1: Review of mathematical formulations. [waste heat discharge from power plants and effects on ecosystems

NASA Technical Reports Server (NTRS)

Lee, S. S.; Sengupta, S.

1978-01-01

A mathematical model package for thermal pollution analyses and prediction is presented. These models, intended as user's manuals, are three dimensional and time dependent using the primitive equation approach. Although they have sufficient generality for application at sites with diverse topographical features; they also present specific instructions regarding data preparation for program execution and sample problems. The mathematical formulation of these models is presented including assumptions, approximations, governing equations, boundary and initial conditions, numerical method of solution, and same results.

Intermediate Models of Planetary Circulations in the Atmosphere and Ocean.

NASA Astrophysics Data System (ADS)

McWilliams, James C.; Gent, Peter R.

1980-08-01

Large-scale extratropical motions (with dimensions comparable to, or somewhat smaller than, the planetary radius) in the atmosphere and ocean exhibit a more restricted range of phenomena than are admissible in the primitive equations for fluid motions, and there have been many previous proposals for simpler, more phenomenologically limited models of these motions. The oldest and most successful of these is the quasi-geostrophic model. An extensive discussion is made of models intermediate between the quasi-geostrophic and primitive ones, some of which have been previously proposed [e.g., the balance equations (BE), where tendencies in the equation for the divergent component of velocity are neglected, or the geostrophic momentum approximation (GM), where ageostrophic accelerations are neglected relative to geostrophic ones] and some of which are derived here. Virtues of these models are assessed in the dual measure of nearly geostrophic momentum balance (i.e., small Rossby number) and approximate frontal structure (i.e., larger along-axis velocities and length scales than their cross-axis counterparts), since one or both of these circumstances is usually characteristic of planetary motions. Consideration is also given to various coordinate transformations, since they can yield simpler expressions for the governing differential equations of the intermediate models. In particular, a new set of coordinates is proposed, isentropic geostrophic coordinates,(IGC), which has the advantage of making implicit the advections due to ageostrophic horizontal and vertical velocities under various approximations. A generalization of quasi-geostrophy is made. named hypo-geostrophy (HG), which is an asymptotic approximation of one higher order accuracy in Rossby number. The governing equations are simplest in IGC for both HG and GM; we name the latter in these coordinates isentropic semi-geostrophy (ISG), in analogy to Hoskins' (1975) semi-geostrophy (SG). HG, GM and BE are, in our opinion, the three most valuable intermediate models for future consideration. HG and BE are superior to GM asymptotically in small Rossby number, but HG in IGC and GM are superior to HG in other coordinates and BE in frontal asymptotics. GM has global (not asymptotic) integral invariants of energy and enstrophy, which HG lacks, and this may assure physically better solutions in weakly asymptotic situations. BE has one global (energy) and one asymptotic (enstrophy) invariant. BE has difficulties of solution existence and uniqueness. Further progress in the search for intermediate models requires obtaining an extensive set of solutions for these models for comparison with quasi-geostrophic and primitive equation solutions.

Computational simulation of probabilistic lifetime strength for aerospace materials subjected to high temperature, mechanical fatigue, creep and thermal fatigue

NASA Technical Reports Server (NTRS)

Boyce, Lola; Bast, Callie C.; Trimble, Greg A.

1992-01-01

This report presents the results of a fourth year effort of a research program, conducted for NASA-LeRC by the University of Texas at San Antonio (UTSA). The research included on-going development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subject to a number of effects or primitive variables. These primitive variables may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above-described constitutive equation using actual experimental materials data together with regression analysis of that data, thereby predicting values for the empirical material constants for each effect or primitive variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from industry and the open literature for materials typically for applications in aerospace propulsion system components. Material data for Inconel 718 has been analyzed using the developed methodology.

Computational simulation of probabilistic lifetime strength for aerospace materials subjected to high temperature, mechanical fatigue, creep, and thermal fatigue

NASA Technical Reports Server (NTRS)

Boyce, Lola; Bast, Callie C.; Trimble, Greg A.

1992-01-01

The results of a fourth year effort of a research program conducted for NASA-LeRC by The University of Texas at San Antonio (UTSA) are presented. The research included on-going development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subjected to a number of effects or primitive variables. These primitive variables may include high temperature, fatigue, or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation was randomized and is included in the computer program, PROMISC. Also included in the research is the development of methodology to calibrate the above-described constitutive equation using actual experimental materials data together with regression analysis of that data, thereby predicting values for the empirical material constants for each effect or primitive variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from industry and the open literature for materials typically for applications in aerospace propulsion system components. Material data for Inconel 718 was analyzed using the developed methodology.

Using exact solutions to develop an implicit scheme for the baroclinic primitive equations

NASA Technical Reports Server (NTRS)

Marchesin, D.

1984-01-01

The exact solutions presently obtained by means of a novel method for nonlinear initial value problems are used in the development of numerical schemes for the computer solution of these problems. The method is applied to a new, fully implicit scheme on a vertical slice of the isentropic baroclinic equations. It was not possible to find a global scale phenomenon that could be simulated by the baroclinic primitive equations on a vertical slice.

A model for tides and currents in the English Channel and southern North Sea

USGS Publications Warehouse

Walters, Roy A.

1987-01-01

The amplitude and phase of 11 tidal constituents for the English Channel and southern North Sea are calculated using a frequency domain, finite element model. The governing equations - the shallow water equations - are modifed such that sea level is calculated using an elliptic equation of the Helmholz type followed by a back-calculation of velocity using the primitive momentum equations. Triangular elements with linear basis functions are used. The modified form of the governing equations provides stable solutions with little numerical noise. In this field-scale test problem, the model was able to produce the details of the structure of 11 tidal constituents including O1, K1, M2, S2, N2, K2, M4, MS4, MN4, M6, and 2MS6.

An explicit mixed numerical method for mesoscale model

NASA Technical Reports Server (NTRS)

Hsu, H.-M.

1981-01-01

A mixed numerical method has been developed for mesoscale models. The technique consists of a forward difference scheme for time tendency terms, an upstream scheme for advective terms, and a central scheme for the other terms in a physical system. It is shown that the mixed method is conditionally stable and highly accurate for approximating the system of either shallow-water equations in one dimension or primitive equations in three dimensions. Since the technique is explicit and two time level, it conserves computer and programming resources.

Application of satellite data in variational analysis for global cyclonic systems

NASA Technical Reports Server (NTRS)

Achtemeier, G. L.

1987-01-01

The research goal was a variational data assimilation method that incorporates as dynamical constraints, the primitive equations for a moist, convectively unstable atmosphere and the radiative transfer equation. Variables to be adjusted include the three-dimensional vector wind, height, temperature, and moisture from rawinsonde data, and cloud-wind vectors, moisture, and radiance from satellite data. This presents a formidable mathematical problem. In order to facilitate thorough analysis of each of the model components, four variational models that divide the problem naturally according to increasing complexity are defined. Each model is summarized.

Atmospheric prediction model survey

NASA Technical Reports Server (NTRS)

Wellck, R. E.

1976-01-01

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.

Existence and Regularity of Invariant Measures for the Three Dimensional Stochastic Primitive Equations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glatt-Holtz, Nathan, E-mail: negh@vt.edu; Kukavica, Igor, E-mail: kukavica@usc.edu; Ziane, Mohammed, E-mail: ziane@usc.edu

2014-05-15

We establish the continuity of the Markovian semigroup associated with strong solutions of the stochastic 3D Primitive Equations, and prove the existence of an invariant measure. The proof is based on new moment bounds for strong solutions. The invariant measure is supported on strong solutions and is furthermore shown to have higher regularity properties.

Application of satellite data in variational analysis for global cyclonic systems

NASA Technical Reports Server (NTRS)

Achtemeier, G. L.

1988-01-01

The goal of the research is a variational data assimilation method that incorporates as dynamical constraints, the primitive equations for a moist, convectively unstable atmosphere and the radiative transfer equation. Variables to be adjusted include the three-dimensional vector wind, height, temperature, and moisture from rawinsonde data, and cloud-wind vectors, moisture, and radiance from satellite data. In order to facilitate thorough analysis of each of the model components, four variational models that divide the problem naturally according to increasing complexity were defined. The research performed during the second year fall into four areas: sensitivity studies involving Model 1; evaluation of Model 2; reformation of Model 1 for greater compatibility with Model 2; development of Model 3 (radiative transfer equation); and making the model more responsive to the observations.

The effect of latent heat release on synoptic-to-planetary wave interactions and its implication for satellite observations: Theoretical modeling

NASA Technical Reports Server (NTRS)

Branscome, Lee E.; Bleck, Rainer; Obrien, Enda

1990-01-01

The project objectives are to develop process models to investigate the interaction of planetary and synoptic-scale waves including the effects of latent heat release (precipitation), nonlinear dynamics, physical and boundary-layer processes, and large-scale topography; to determine the importance of latent heat release for temporal variability and time-mean behavior of planetary and synoptic-scale waves; to compare the model results with available observations of planetary and synoptic wave variability; and to assess the implications of the results for monitoring precipitation in oceanic-storm tracks by satellite observing systems. Researchers have utilized two different models for this project: a two-level quasi-geostrophic model to study intraseasonal variability, anomalous circulations and the seasonal cycle, and a 10-level, multi-wave primitive equation model to validate the two-level Q-G model and examine effects of convection, surface processes, and spherical geometry. It explicitly resolves several planetary and synoptic waves and includes specific humidity (as a predicted variable), moist convection, and large-scale precipitation. In the past year researchers have concentrated on experiments with the multi-level primitive equation model. The dynamical part of that model is similar to the spectral model used by the National Meteorological Center for medium-range forecasts. The model includes parameterizations of large-scale condensation and moist convection. To test the validity of results regarding the influence of convective precipitation, researchers can use either one of two different convective schemes in the model, a Kuo convective scheme or a modified Arakawa-Schubert scheme which includes downdrafts. By choosing one or the other scheme, they can evaluate the impact of the convective parameterization on the circulation. In the past year researchers performed a variety of initial-value experiments with the primitive-equation model. Using initial conditions typical of climatological winter conditions, they examined the behavior of synoptic and planetary waves growing in moist and dry environments. Surface conditions were representative of a zonally averaged ocean. They found that moist convection associated with baroclinic wave development was confined to the subtropics.

A model for tides and currents in the English Channel and southern North Sea

NASA Astrophysics Data System (ADS)

Walters, Roy. A.

The amplitude and phase of 11 tidal constituents for the English Channel and southern North Sea are calculated using a frequency domain, finite element model. The governing equations — the shallow water equations — are modifed such that sea level is calculated using an elliptic equation of the Helmholz type followed by a back-calculation of velocity using the primitive momentum equations. Triangular elements with linear basis functions are used. The modified form of the governing equations provides stable solutions with little numerical noise. In this field-scale test problem, the model was able to produce the details of the structure of 11 tidal constituents including O 1, K 1, M 2, S 2, N 2, K 2, M 4, MS 4, MN 4, M 6, and 2MS 6.

A manual for PARTI runtime primitives

NASA Technical Reports Server (NTRS)

Berryman, Harry; Saltz, Joel

1990-01-01

Primitives are presented that are designed to help users efficiently program irregular problems (e.g., unstructured mesh sweeps, sparse matrix codes, adaptive mesh partial differential equations solvers) on distributed memory machines. These primitives are also designed for use in compilers for distributed memory multiprocessors. Communications patterns are captured at runtime, and the appropriate send and receive messages are automatically generated.

Existence and Non-uniqueness of Global Weak Solutions to Inviscid Primitive and Boussinesq Equations

NASA Astrophysics Data System (ADS)

Chiodaroli, Elisabetta; Michálek, Martin

2017-08-01

We consider the initial value problem for the inviscid Primitive and Boussinesq equations in three spatial dimensions. We recast both systems as an abstract Euler-type system and apply the methods of convex integration of De Lellis and Székelyhidi to show the existence of infinitely many global weak solutions of the studied equations for general initial data. We also introduce an appropriate notion of dissipative solutions and show the existence of suitable initial data which generate infinitely many dissipative solutions.

Winter and summer simulations with the GLAS climate model

NASA Technical Reports Server (NTRS)

Shukla, J.; Straus, D.; Randall, D.; Sud, Y.; Marx, L.

1981-01-01

The GLAS climate model is a general circulation model based on the primitive equations in sigma coordinates on a global domain in the presence of orography. The model incorporates parameterizations of the effects of radiation, convection, large scale latent heat release, turbulent and boundary layer fluxes, and ground hydrology. Winter and summer simulations were carried out with this model, and the resulting data are compared to observations.

Middle atmosphere project. A semi-spectral numerical model for the large-scale stratospheric circulation

NASA Technical Reports Server (NTRS)

Holton, J. R.; Wehrbein, W.

1979-01-01

The complete model is a semispectral model in which the longitudinal dependence is represented by expansion in zonal harmonics while the latitude and height dependencies are represented by a finite difference grid. The model is based on the primitive equations in the log pressure coordinate system. The lower boundary of the model domain is set at the 100 mb level (i.e., near the tropopause) and the effects of tropospheric forcing are included in the lower boundary condition. The upper boundary is at approximately 96 km, and the latitudinal extent is either global or hemispheric. The basic differential equations and boundary conditions are outlined. The finite difference equations are described. The initial conditions are discussed and a sample calculation is presented. The FORTRAN code is given in the appendix.

A manual for PARTI runtime primitives, revision 1

NASA Technical Reports Server (NTRS)

Das, Raja; Saltz, Joel; Berryman, Harry

1991-01-01

Primitives are presented that are designed to help users efficiently program irregular problems (e.g., unstructured mesh sweeps, sparse matrix codes, adaptive mesh partial differential equations solvers) on distributed memory machines. These primitives are also designed for use in compilers for distributed memory multiprocessors. Communications patterns are captured at runtime, and the appropriate send and receive messages are automatically generated.

Jet formation and equatorial superrotation in Jupiter's atmosphere: Numerical modelling using a new efficient parallel code

NASA Astrophysics Data System (ADS)

Rivier, Leonard Gilles

Using an efficient parallel code solving the primitive equations of atmospheric dynamics, the jet structure of a Jupiter like atmosphere is modeled. In the first part of this thesis, a parallel spectral code solving both the shallow water equations and the multi-level primitive equations of atmospheric dynamics is built. The implementation of this code called BOB is done so that it runs effectively on an inexpensive cluster of workstations. A one dimensional decomposition and transposition method insuring load balancing among processes is used. The Legendre transform is cache-blocked. A "compute on the fly" of the Legendre polynomials used in the spectral method produces a lower memory footprint and enables high resolution runs on relatively small memory machines. Performance studies are done using a cluster of workstations located at the National Center for Atmospheric Research (NCAR). BOB performances are compared to the parallel benchmark code PSTSWM and the dynamical core of NCAR's CCM3.6.6. In both cases, the comparison favors BOB. In the second part of this thesis, the primitive equation version of the code described in part I is used to study the formation of organized zonal jets and equatorial superrotation in a planetary atmosphere where the parameters are chosen to best model the upper atmosphere of Jupiter. Two levels are used in the vertical and only large scale forcing is present. The model is forced towards a baroclinically unstable flow, so that eddies are generated by baroclinic instability. We consider several types of forcing, acting on either the temperature or the momentum field. We show that only under very specific parametric conditions, zonally elongated structures form and persist resembling the jet structure observed near the cloud level top (1 bar) on Jupiter. We also study the effect of an equatorial heat source, meant to be a crude representation of the effect of the deep convective planetary interior onto the outer atmospheric layer. We show that such heat forcing is able to produce strong equatorial superrotating winds, one of the most striking feature of the Jovian circulation.

A NUMERICAL ANALYSIS OF LANDFALL OF THE 1979 RED TIDE OF KARENIA BREVIS ALONG THE WEST COAST OF FLORIDA. (R827085)

EPA Science Inventory

Abstract

A simple ecological model, coupled to a primitive equation circulation model, is able to replicate the observed alongshore transport of the toxic dinoflagellate Karenia brevis on the West Florida shelf during a fall red tide in 1979. Initial land fall o...

A Variational Formalism for the Radiative Transfer Equation and a Geostrophic, Hydrostatic Atmosphere: Prelude to Model 3

NASA Technical Reports Server (NTRS)

Achtemeier, Gary L.

1991-01-01

The second step in development of MODEL III is summarized. It combines the four radiative transfer equations of the first step with the equations for a geostrophic and hydrostatic atmosphere. This step is intended to bring radiance into a three dimensional balance with wind, height, and temperature. The use of the geostrophic approximation in place of the full set of primitive equations allows for an easier evaluation of how the inclusion of the radiative transfer equation increases the complexity of the variational equations. Seven different variational formulations were developed for geostrophic, hydrostatic, and radiative transfer equations. The first derivation was too complex to yield solutions that were physically meaningful. For the remaining six derivations, the variational method gave the same physical interpretation (the observed brightness temperatures could provide no meaningful input to a geostrophic, hydrostatic balance) at least through the problem solving methodology used in these studies. The variational method is presented and the Euler-Lagrange equations rederived for the geostrophic, hydrostatic, and radiative transfer equations.

Forcing a three-dimensional, hydrostatic, primitive-equation model for application in the surf zone: 2. Application to DUCK94

NASA Astrophysics Data System (ADS)

Newberger, P. A.; Allen, J. S.

2007-08-01

A three-dimensional primitive-equation model for application to the nearshore surf zone has been developed. This model, an extension of the Princeton Ocean Model (POM), predicts the wave-averaged circulation forced by breaking waves. All of the features of the original POM are retained in the extended model so that applications can be made to regions where breaking waves, stratification, rotation, and wind stress make significant contributions to the flow behavior. In this study we examine the effects of breaking waves and wind stress. The nearshore POM circulation model is embedded within the NearCom community model and is coupled with a wave model. This combined modeling system is applied to the nearshore surf zone off Duck, North Carolina, during the DUCK94 field experiment of October 1994. Model results are compared to observations from this experiment, and the effects of parameter choices are examined. A process study examining the effects of tidal depth variation on depth-dependent wave-averaged currents is carried out. With identical offshore wave conditions and model parameters, the strength and spatial structure of the undertow and of the alongshore current vary systematically with water depth. Some three-dimensional solutions show the development of shear instabilities of the alongshore current. Inclusion of wave-current interactions makes an appreciable difference in the characteristics of the instability.

Large-eddy simulation of a turbulent mixing layer

NASA Technical Reports Server (NTRS)

Mansour, N. N.; Ferziger, J. H.; Reynolds, W. C.

1978-01-01

The three dimensional, time dependent (incompressible) vorticity equations were used to simulate numerically the decay of isotropic box turbulence and time developing mixing layers. The vorticity equations were spatially filtered to define the large scale turbulence field, and the subgrid scale turbulence was modeled. A general method was developed to show numerical conservation of momentum, vorticity, and energy. The terms that arise from filtering the equations were treated (for both periodic boundary conditions and no stress boundary conditions) in a fast and accurate way by using fast Fourier transforms. Use of vorticity as the principal variable is shown to produce results equivalent to those obtained by use of the primitive variable equations.

Finite element techniques for the Navier-Stokes equations in the primitive variable formulation and the vorticity stream-function formulation

NASA Technical Reports Server (NTRS)

Glaisner, F.; Tezduyar, T. E.

1987-01-01

Finite element procedures for the Navier-Stokes equations in the primitive variable formulation and the vorticity stream-function formulation have been implemented. For both formulations, streamline-upwind/Petrov-Galerkin techniques are used for the discretization of the transport equations. The main problem associated with the vorticity stream-function formulation is the lack of boundary conditions for vorticity at solid surfaces. Here an implicit treatment of the vorticity at no-slip boundaries is incorporated in a predictor-multicorrector time integration scheme. For the primitive variable formulation, mixed finite-element approximations are used. A nine-node element and a four-node + bubble element have been implemented. The latter is shown to exhibit a checkerboard pressure mode and a numerical treatment for this spurious pressure mode is proposed. The two methods are compared from the points of view of simulating internal and external flows and the possibilities of extensions to three dimensions.

A global multilevel atmospheric model using a vector semi-Lagrangian finite-difference scheme. I - Adiabatic formulation

NASA Technical Reports Server (NTRS)

Bates, J. R.; Moorthi, S.; Higgins, R. W.

1993-01-01

An adiabatic global multilevel primitive equation model using a two time-level, semi-Lagrangian semi-implicit finite-difference integration scheme is presented. A Lorenz grid is used for vertical discretization and a C grid for the horizontal discretization. The momentum equation is discretized in vector form, thus avoiding problems near the poles. The 3D model equations are reduced by a linear transformation to a set of 2D elliptic equations, whose solution is found by means of an efficient direct solver. The model (with minimal physics) is integrated for 10 days starting from an initialized state derived from real data. A resolution of 16 levels in the vertical is used, with various horizontal resolutions. The model is found to be stable and efficient, and to give realistic output fields. Integrations with time steps of 10 min, 30 min, and 1 h are compared, and the differences are found to be acceptable.

A fully vectorized numerical solution of the incompressible Navier-Stokes equations. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Patel, N.

1983-01-01

A vectorizable algorithm is presented for the implicit finite difference solution of the incompressible Navier-Stokes equations in general curvilinear coordinates. The unsteady Reynolds averaged Navier-Stokes equations solved are in two dimension and non-conservative primitive variable form. A two-layer algebraic eddy viscosity turbulence model is used to incorporate the effects of turbulence. Two momentum equations and a Poisson pressure equation, which is obtained by taking the divergence of the momentum equations and satisfying the continuity equation, are solved simultaneously at each time step. An elliptic grid generation approach is used to generate a boundary conforming coordinate system about an airfoil. The governing equations are expressed in terms of the curvilinear coordinates and are solved on a uniform rectangular computational domain. A checkerboard SOR, which can effectively utilize the computer architectural concept of vector processing, is used for iterative solution of the governing equations.

Theory and modeling of atmospheric turbulence, part 2

NASA Technical Reports Server (NTRS)

Chen, C. M.

1984-01-01

Two dimensional geostrophic turbulence driven by a random force is investigated. Based on the Liouville equation, which simulates the primitive hydrodynamical equations, a group-kinetic theory of turbulence is developed and the kinetic equation of the scaled singlet distribution is derived. The kinetic equation is transformed into an equation of spectral balance in the equilibrium and non-equilibrium states. Comparison is made between the propagators and the Green's functions in the case of the non-asymptotic quasi-linear equation to prove the equivalence of both kinds of approximations used to describe perturbed trajectories of plasma turbulence. The microdynamical state of fluid turbulence is described by a hydrodynamical system and transformed into a master equation analogous to the Vlasov equation for plasma turbulence. The spectral balance for the velocity fluctuations of individual components shows that the scaled pressure strain correlation and the cascade transfer are two transport functions that play the most important roles.

Electric Double-Layer Structure in Primitive Model Electrolytes. Comparing Molecular Dynamics with Local-Density Approximations

DOE PAGES

Giera, Brian; Lawrence Livermore National Lab.; Henson, Neil; ...

2015-02-27

We evaluate the accuracy of local-density approximations (LDAs) using explicit molecular dynamics simulations of binary electrolytes comprised of equisized ions in an implicit solvent. The Bikerman LDA, which considers ions to occupy a lattice, poorly captures excluded volume interactions between primitive model ions. Instead, LDAs based on the Carnahan–Starling (CS) hard-sphere equation of state capture simulated values of ideal and excess chemical potential profiles extremely well, as is the relationship between surface charge density and electrostatic potential. Excellent agreement between the EDL capacitances predicted by CS-LDAs and computed in molecular simulations is found even in systems where ion correlations drivemore » strong density and free charge oscillations within the EDL, despite the inability of LDAs to capture the oscillations in the detailed EDL profiles.« less

Formulation of Efficient Finite Element Prediction Models.

DTIC Science & Technology

1980-01-01

vorticity-divergence FEM formulation. This paper will compare these FEM formulations by considering the Vgeostrophic adjustment process with the linearized...by Fourier transforming the terms that are independent of t in (2.12)-(2.14) or (2.19)-(2.21). However, in this paper the final state will be...filtering in a baroclinic primitive equation model. 17 L . , 5. Conclusions The objective of this paper is to determine the response of various finite

On the Vertical Structure of Seasonal, Interannual and Intraseasonal Flows

DTIC Science & Technology

1992-12-01

regions. Extensive use is made of a primitive equation (PE) model, as a diagnostic tool, to explore the extent to which tropical heating might influence ...vertical modes, while Wiin-Nielsen (1971a and b) studied the time 2 behaviour of long waves for various vertical structures. More recent investigations...nonlinear three-leve PE model, are used to determine the influence of tropical heating on extratropica wave response. In Chapter 4, the interannual changes

Characteristics of 3-D transport simulations of the stratosphere and mesosphere

NASA Technical Reports Server (NTRS)

Fairlie, T. D. A.; Siskind, D. E.; Turner, R. E.; Fisher, M.

1992-01-01

A 3D mechanistic, primitive-equation model of the stratosphere and mesosphere is coupled to an offline spectral transport model. The dynamics model is initialized with and forced by observations so that the coupled models may be used to study specific episodes. Results are compared with those obtained by transport online in the dynamics model. Although some differences are apparent, the results suggest that coupling of the models to a comprehensive photochemical package will provide a useful tool for studying the evolution of constituents in the middle atmosphere during specific episodes.

A study of the adequacy of quasi-geostrophic dynamics for modeling the effect of frontal cyclones on the larger scale flow

NASA Technical Reports Server (NTRS)

Mudrick, S.

1985-01-01

The validity of quasi-geostrophic (QG) dynamics were tested on compared to primitive equation (PE) dynamics, for modeling the effect of cyclone waves on the larger scale flow. The formation of frontal cyclones and the dynamics of occluded frontogenesis were studied. Surface friction runs with the PE model and the wavelength of maximum instability is described. Also fine resolution PE simulation of a polar low is described.

Atmospheric model development in support of SEASAT. Volume 2: Analysis models

NASA Technical Reports Server (NTRS)

Langland, R. A.

1977-01-01

As part of the SEASAT program of NASA, two sets of analysis programs were developed for the Jet Propulsion Laboratory. One set of programs produce 63 x 63 horizontal mesh analyses on a polar stereographic grid. The other set produces 187 x 187 third mesh analyses. The parameters analyzed include sea surface temperature, sea level pressure and twelve levels of upper air temperature, height and wind analyses. The analysis output is used to initialize the primitive equation forecast models.

Existence and Regularity Results for the Inviscid Primitive Equations with Lateral Periodicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamouda, Makram, E-mail: mahamoud@indiana.edu; Jung, Chang-Yeol, E-mail: changyeoljung@gmail.com; Temam, Roger, E-mail: temam@indiana.edu

2016-06-15

The article is devoted to prove the existence and regularity of the solutions of the 3D inviscid Linearized Primitive Equations (LPEs) in a channel with lateral periodicity. This was assumed in a previous work (Hamouda et al. in Discret Contin Dyn Syst Ser S 6(2):401–422, 2013) which is concerned with the boundary layers generated by the corresponding viscous problem. Although the equations under investigation here are of hyperbolic type, the standard methods do not apply because of the specificity of the hyperbolic system. A set of non-local boundary conditions for the inviscid LPEs has to be imposed at the lateralmore » boundary of the channel making thus the system well-posed.« less

Probabilistic lifetime strength of aerospace materials via computational simulation

NASA Technical Reports Server (NTRS)

Boyce, Lola; Keating, Jerome P.; Lovelace, Thomas B.; Bast, Callie C.

1991-01-01

The results of a second year effort of a research program are presented. The research included development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic phenomenological constitutive relationship, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subjected to a number of effects of primitive variables. These primitive variables often originate in the environment and may include stress from loading, temperature, chemical, or radiation attack. This multifactor interaction constitutive equation is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the constitutive equation using actual experimental materials data together with the multiple linear regression of that data.

The terminal area simulation system. Volume 1: Theoretical formulation

NASA Technical Reports Server (NTRS)

Proctor, F. H.

1987-01-01

A three-dimensional numerical cloud model was developed for the general purpose of studying convective phenomena. The model utilizes a time splitting integration procedure in the numerical solution of the compressible nonhydrostatic primitive equations. Turbulence closure is achieved by a conventional first-order diagnostic approximation. Open lateral boundaries are incorporated which minimize wave reflection and which do not induce domain-wide mass trends. Microphysical processes are governed by prognostic equations for potential temperature water vapor, cloud droplets, ice crystals, rain, snow, and hail. Microphysical interactions are computed by numerous Orville-type parameterizations. A diagnostic surface boundary layer is parameterized assuming Monin-Obukhov similarity theory. The governing equation set is approximated on a staggered three-dimensional grid with quadratic-conservative central space differencing. Time differencing is approximated by the second-order Adams-Bashforth method. The vertical grid spacing may be either linear or stretched. The model domain may translate along with a convective cell, even at variable speeds.

Formulation of an explicit-multiple-time-step time integration method for use in a global primitive equation grid model

NASA Technical Reports Server (NTRS)

Chao, W. C.

1982-01-01

With appropriate modifications, a recently proposed explicit-multiple-time-step scheme (EMTSS) is incorporated into the UCLA model. In this scheme, the linearized terms in the governing equations that generate the gravity waves are split into different vertical modes. Each mode is integrated with an optimal time step, and at periodic intervals these modes are recombined. The other terms are integrated with a time step dictated by the CFL condition for low-frequency waves. This large time step requires a special modification of the advective terms in the polar region to maintain stability. Test runs for 72 h show that EMTSS is a stable, efficient and accurate scheme.

Statistical Field Estimation for Complex Coastal Regions and Archipelagos (PREPRINT)

DTIC Science & Technology

2011-04-09

and study the computational properties of these schemes. Specifically, we extend a multiscale Objective Analysis (OA) approach to complex coastal...computational properties of these schemes. Specifically, we extend a multiscale Objective Analysis (OA) approach to complex coastal regions and... multiscale free-surface code builds on the primitive-equation model of the Harvard Ocean Predic- tion System (HOPS, Haley et al. (2009)). Additionally

Diurnal forcing of planetary atmospheres

NASA Technical Reports Server (NTRS)

Houben, Howard C.

1991-01-01

The utility of the Mars Planetary Boundary Layer Model (MPBL) for calculations in support of the Mars 94 balloon mission was substantially enhanced by the introduction of a balloon equation of motion into the model. Both vertical and horizontal excursions of the balloon are calculated along with its volume, temperature, and pressure. The simulations reproduce the expected 5-min vertical oscillations of a constant density balloon at altitude on Mars. The results of these calculations are presented for the nominal target location of the balloon. A nonlinear balanced model was developed for the Martian atmosphere. It was used to initialize a primitive equation model for the simulations of the Earth's atmosphere at the time of the El Chichon eruption in 1982. It is also used as an assimilation model to update the temperature and wind fields at frequent intervals.

A nested-grid limited-area model for short term weather forecasting

NASA Technical Reports Server (NTRS)

Wong, V. C.; Zack, J. W.; Kaplan, M. L.; Coats, G. D.

1983-01-01

The present investigation is concerned with a mesoscale atmospheric simulation system (MASS), incorporating the sigma-coordinate primitive equations. The present version of this model (MASS 3.0) has 14 vertical layers, with the upper boundary at 100 mb. There are 128 x 96 grid points in each layer. The earlier version of this model (MASS 2.0) has been described by Kaplan et al. (1982). The current investigation provides a summary of major revisions to that version and a description of the parameterization schemes which are presently included in the model. The planetary boundary layer (PBL) is considered, taking into account aspects of generalized similarity theory and free convection, the surface energy budget, the surface moisture budget, and prognostic equations for the depth h of the PBL. A cloud model is discussed, giving attention to stable precipitation, and cumulus convection.

Counting Primitive Pythagorean Triples

ERIC Educational Resources Information Center

Ayoub, Ayoub B.

2005-01-01

A triple (x,y,z) of natural numbers is called a Primitive Pythagorean Triple (PPT) if it satisfies two conditions: (1) x[squared] + y[squared] = z[squared]; and (2) x, y, and z have no common factor other than one. All the PPT's are given by the parametric equations: (1) x = m[squared] - n[squared]; (2) y = 2mn; and (3) z = m[squared] +…

Combination of Alternative Models by Mutual Data Assimilation: Supermodeling With A Suite of Primitive Equation Models

NASA Astrophysics Data System (ADS)

Duane, G. S.; Selten, F.

2016-12-01

Different models of climate and weather commonly give projections/predictions that differ widely in their details. While averaging of model outputs almost always improves results, nonlinearity implies that further improvement can be obtained from model interaction in run time, as has already been demonstrated with toy systems of ODEs and idealized quasigeostrophic models. In the supermodeling scheme, models effectively assimilate data from one another and partially synchronize with one another. Spread among models is manifest as a spread in possible inter-model connection coefficients, so that the models effectively "agree to disagree". Here, we construct a supermodel formed from variants of the SPEEDO model, a primitive-equation atmospheric model (SPEEDY) coupled to ocean and land. A suite of atmospheric models, coupled to the same ocean and land, is chosen to represent typical differences among climate models by varying model parameters. Connections are introduced between all pairs of corresponding independent variables at synoptic-scale intervals. Strengths of the inter-atmospheric connections can be considered to represent inverse inter-model observation error. Connection strengths are adapted based on an established procedure that extends the dynamical equations of a pair of synchronizing systems to synchronize parameters as well. The procedure is applied to synchronize the suite of SPEEDO models with another SPEEDO model regarded as "truth", adapting the inter-model connections along the way. The supermodel with trained connections gives marginally lower error in all fields than any weighted combination of the separate model outputs when used in "weather-prediction mode", i.e. with constant nudging to truth. Stronger results are obtained if a supermodel is used to predict the formation of coherent structures or the frequency of such. Partially synchronized SPEEDO models give a better representation of the blocked-zonal index cycle than does a weighted average of the constituent model outputs. We have thus shown that supermodeling and the synchronization-based procedure to adapt inter-model connections give results superior to output averaging not only with highly nonlinear toy systems, but with smaller nonlinearities as occur in climate models.

Analyzing Martian winds and tracer concentrations using Mars Observer data

NASA Technical Reports Server (NTRS)

Houben, Howard C.

1993-01-01

During the courses of a day, the Mars Observer spacecraft will acquire globally distributed profiles of the martian atmosphere. It is highly desirable that this data be assembled into synoptic weather maps (complete specifications of the atmospheric pressure, temperature, and winds at a given time), which can in turn be used as starting points in the study of many meteorological phenomena. Unfortunately, the special nature of the Mars Observer data presents several challenges above and beyond the usual difficult problem of data initialization. Mars Observer atmospheric data will consist almost exclusively of asynoptic vertical profiles of temperatures (or radiances) and pressures, whereas winds are generally in balance with horizontal gradients of these quantities (which will not be observed). It will therefore be necessary to resort to dynamical models to analyze the wind fields. As a rule, data assimilation into atmospheric models can result in the generation of spurious gravity waves, so special steps must be taken to suppress these. In addition, the asynoptic nature of the data will require a four-dimensional (space and time) data assimilation scheme. The problem is to find a full set of meteorological fields (winds and temperatures) such that, when marched forward in time in the model, they achieve a best fit (in the weighted least-squares sense) to the data. The proposed solution is to develop a model especially for the Mars Observer data assimilation problem. Gravity waves are filtered from the model by eliminating all divergence terms from the prognostic divergence equation. This leaves a diagnostic gradient wind relation between the rotational wind and the temperature field. The divergent wind is diagnosed as the wind required to maintain the gradient wind balance in the presence of the diabatic heating. The primitive equations of atmospheric dynamics (with three principal dependent variables) are thus reduced to a simpler system with a single prognostic equation for temperature - the variable that will be best observed. (This balance system was apparently first derived by Charney as a first-order Rossby number expansion of the equations of motion). Experience with a full primitive equation model of the martian atmosphere indicates that a further simplification is possible: at least for short-term integrations, the model can be linearized about the zonally symmetric basic state.

Ensemble assimilation of ARGO temperature profile, sea surface temperature, and altimetric satellite data into an eddy permitting primitive equation model of the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Yan, Y.; Barth, A.; Beckers, J. M.; Candille, G.; Brankart, J. M.; Brasseur, P.

2015-07-01

Sea surface height, sea surface temperature, and temperature profiles at depth collected between January and December 2005 are assimilated into a realistic eddy permitting primitive equation model of the North Atlantic Ocean using the Ensemble Kalman Filter. Sixty ensemble members are generated by adding realistic noise to the forcing parameters related to the temperature. The ensemble is diagnosed and validated by comparison between the ensemble spread and the model/observation difference, as well as by rank histogram before the assimilation experiments. An incremental analysis update scheme is applied in order to reduce spurious oscillations due to the model state correction. The results of the assimilation are assessed according to both deterministic and probabilistic metrics with independent/semiindependent observations. For deterministic validation, the ensemble means, together with the ensemble spreads are compared to the observations, in order to diagnose the ensemble distribution properties in a deterministic way. For probabilistic validation, the continuous ranked probability score (CRPS) is used to evaluate the ensemble forecast system according to reliability and resolution. The reliability is further decomposed into bias and dispersion by the reduced centered random variable (RCRV) score in order to investigate the reliability properties of the ensemble forecast system. The improvement of the assimilation is demonstrated using these validation metrics. Finally, the deterministic validation and the probabilistic validation are analyzed jointly. The consistency and complementarity between both validations are highlighted.

A Petascale Non-Hydrostatic Atmospheric Dynamical Core in the HOMME Framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tufo, Henry

The High-Order Method Modeling Environment (HOMME) is a framework for building scalable, conserva- tive atmospheric models for climate simulation and general atmospheric-modeling applications. Its spatial discretizations are based on Spectral-Element (SE) and Discontinuous Galerkin (DG) methods. These are local methods employing high-order accurate spectral basis-functions that have been shown to perform well on massively parallel supercomputers at any resolution and scale particularly well at high resolutions. HOMME provides the framework upon which the CAM-SE community atmosphere model dynamical-core is constructed. In its current incarnation, CAM-SE employs the hydrostatic primitive-equations (PE) of motion, which limits its resolution to simulations coarser thanmore » 0.1 per grid cell. The primary objective of this project is to remove this resolution limitation by providing HOMME with the capabilities needed to build nonhydrostatic models that solve the compressible Euler/Navier-Stokes equations.« less

Asymptotic of the Solutions of Hyperbolic Equations with a Skew-Symmetric Perturbation

NASA Astrophysics Data System (ADS)

Gallagher, Isabelle

1998-12-01

Using methods introduced by S. Schochet inJ. Differential Equations114(1994), 476-512, we compute the first term of an asymptotic expansion of the solutions of hyperbolic equations perturbated by a skew-symmetric linear operator. That result is first applied to two systems describing the motion of geophysic fluids: the rotating Euler equations and the primitive system of the quasigeostrophic equations. Finally in the last part, we study the slightly compressible Euler equations by application of that same result.

An analysis of the vertical structure equation for arbitrary thermal profiles

NASA Technical Reports Server (NTRS)

Cohn, Stephen E.; Dee, Dick P.

1989-01-01

The vertical structure equation is a singular Sturm-Liouville problem whose eigenfunctions describe the vertical dependence of the normal modes of the primitive equations linearized about a given thermal profile. The eigenvalues give the equivalent depths of the modes. The spectrum of the vertical structure equation and the appropriateness of various upper boundary conditions, both for arbitrary thermal profiles were studied. The results depend critically upon whether or not the thermal profile is such that the basic state atmosphere is bounded. In the case of a bounded atmosphere it is shown that the spectrum is always totally discrete, regardless of details of the thermal profile. For the barotropic equivalent depth, which corresponds to the lowest eigen value, upper and lower bounds which depend only on the surface temperature and the atmosphere height were obtained. All eigenfunctions are bounded, but always have unbounded first derivatives. It was proved that the commonly invoked upper boundary condition that vertical velocity must vanish as pressure tends to zero, as well as a number of alternative conditions, is well posed. It was concluded that the vertical structure equation always has a totally discrete spectrum under the assumptions implicit in the primitive equations.

An analysis of the vertical structure equation for arbitrary thermal profiles

NASA Technical Reports Server (NTRS)

Cohn, Stephen E.; Dee, Dick P.

1987-01-01

The vertical structure equation is a singular Sturm-Liouville problem whose eigenfunctions describe the vertical dependence of the normal modes of the primitive equations linearized about a given thermal profile. The eigenvalues give the equivalent depths of the modes. The spectrum of the vertical structure equation and the appropriateness of various upper boundary conditions, both for arbitrary thermal profiles were studied. The results depend critically upon whether or not the thermal profile is such that the basic state atmosphere is bounded. In the case of a bounded atmosphere it is shown that the spectrum is always totally discrete, regardless of details of the thermal profile. For the barotropic equivalent depth, which corresponds to the lowest eigen value, upper and lower bounds which depend only on the surface temperature and the atmosphere height were obtained. All eigenfunctions are bounded, but always have unbounded first derivatives. It was proved that the commonly invoked upper boundary condition that vertical velocity must vanish as pressure tends to zero, as well as a number of alternative conditions, is well posed. It was concluded that the vertical structure equation always has a totally discrete spectrum under the assumptions implicit in the primitive equations.

Large eddy simulation of incompressible turbulent channel flow

NASA Technical Reports Server (NTRS)

Moin, P.; Reynolds, W. C.; Ferziger, J. H.

1978-01-01

The three-dimensional, time-dependent primitive equations of motion were numerically integrated for the case of turbulent channel flow. A partially implicit numerical method was developed. An important feature of this scheme is that the equation of continuity is solved directly. The residual field motions were simulated through an eddy viscosity model, while the large-scale field was obtained directly from the solution of the governing equations. An important portion of the initial velocity field was obtained from the solution of the linearized Navier-Stokes equations. The pseudospectral method was used for numerical differentiation in the horizontal directions, and second-order finite-difference schemes were used in the direction normal to the walls. The large eddy simulation technique is capable of reproducing some of the important features of wall-bounded turbulent flows. The resolvable portions of the root-mean square wall pressure fluctuations, pressure velocity-gradient correlations, and velocity pressure-gradient correlations are documented.

Finite element computation of a viscous compressible free shear flow governed by the time dependent Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Cooke, C. H.; Blanchard, D. K.

1975-01-01

A finite element algorithm for solution of fluid flow problems characterized by the two-dimensional compressible Navier-Stokes equations was developed. The program is intended for viscous compressible high speed flow; hence, primitive variables are utilized. The physical solution was approximated by trial functions which at a fixed time are piecewise cubic on triangular elements. The Galerkin technique was employed to determine the finite-element model equations. A leapfrog time integration is used for marching asymptotically from initial to steady state, with iterated integrals evaluated by numerical quadratures. The nonsymmetric linear systems of equations governing time transition from step-to-step are solved using a rather economical block iterative triangular decomposition scheme. The concept was applied to the numerical computation of a free shear flow. Numerical results of the finite-element method are in excellent agreement with those obtained from a finite difference solution of the same problem.

Compilation of Abstracts of Theses Submitted by Candidates for Degrees: October 1990 to September 1991

DTIC Science & Technology

1991-09-30

Tool (ASSET) COMPUTER SCIENCE Vicki Sue Abel VIEWER - A User Interface for Failure 49 Lieutenant Commander, U.S. Navy Region Analysis and Medio Monti...California Current System using a Primitive Equation Model Charles C. McGlothin, Jr. Ambient Sound in the Ocean Induced by 257 Lieutenant, U.S. Navy Heavy...parameters,, and ambient flow/oscillating flow combinations using VAX-3520 and NASA’s Supercomputers. Extensive sensitivity analysis has been performed

Density-functional theory of spherical electric double layers and zeta potentials of colloidal particles in restricted-primitive-model electrolyte solutions.

PubMed

Yu, Yang-Xin; Wu, Jianzhong; Gao, Guang-Hua

2004-04-15

A density-functional theory is proposed to describe the density profiles of small ions around an isolated colloidal particle in the framework of the restricted primitive model where the small ions have uniform size and the solvent is represented by a dielectric continuum. The excess Helmholtz energy functional is derived from a modified fundamental measure theory for the hard-sphere repulsion and a quadratic functional Taylor expansion for the electrostatic interactions. The theoretical predictions are in good agreement with the results from Monte Carlo simulations and from previous investigations using integral-equation theory for the ionic density profiles and the zeta potentials of spherical particles at a variety of solution conditions. Like the integral-equation approaches, the density-functional theory is able to capture the oscillatory density profiles of small ions and the charge inversion (overcharging) phenomena for particles with elevated charge density. In particular, our density-functional theory predicts the formation of a second counterion layer near the surface of highly charged spherical particle. Conversely, the nonlinear Poisson-Boltzmann theory and its variations are unable to represent the oscillatory behavior of small ion distributions and charge inversion. Finally, our density-functional theory predicts charge inversion even in a 1:1 electrolyte solution as long as the salt concentration is sufficiently high. (c) 2004 American Institute of Physics.

PECHCV, PECHFV, PEFHCV and PEFHFV: A set of atmospheric, primitive equation forecast models for the Northern Hemisphere, volume 3

NASA Technical Reports Server (NTRS)

Wellck, R. E.; Pearce, M. L.

1976-01-01

As part of the SEASAT program of NASA, a set of four hemispheric, atmospheric prediction models were developed. The models, which use a polar stereographic grid in the horizontal and a sigma coordinate in the vertical, are: (1) PECHCV - five sigma layers and a 63 x 63 horizontal grid, (2) PECHFV - ten sigma layers and a 63 x 63 horizontal grid, (3) PEFHCV - five sigma layers and a 187 x 187 horizontal grid, and (4) PEFHFV - ten sigma layers and a 187 x 187 horizontal grid. The models and associated computer programs are described.

An Extended Kalman Filter to Assimilate Altimetric Data into a Non-Linear Model of the Tropical Pacific

NASA Technical Reports Server (NTRS)

Gourdeau, L.; Verron, J.; Murtugudde, R.; Busalacchi, A. J.

1997-01-01

A new implementation of the extended Kaman filter is developed for the purpose of assimilating altimetric observations into a primitive equation model of the tropical Pacific. Its specificity consists in defining the errors into a reduced basis that evolves in time with the model dynamic. Validation by twin experiments is conducted and the method is shown to be efficient in quasi real conditions. Data from the first 2 years of the Topex/Poseidon mission are assimilated into the Gent & Cane [1989] model. Assimilation results are evaluated against independent in situ data, namely TAO mooring observations.

A time-accurate algorithm for chemical non-equilibrium viscous flows at all speeds

NASA Technical Reports Server (NTRS)

Shuen, J.-S.; Chen, K.-H.; Choi, Y.

1992-01-01

A time-accurate, coupled solution procedure is described for the chemical nonequilibrium Navier-Stokes equations over a wide range of Mach numbers. This method employs the strong conservation form of the governing equations, but uses primitive variables as unknowns. Real gas properties and equilibrium chemistry are considered. Numerical tests include steady convergent-divergent nozzle flows with air dissociation/recombination chemistry, dump combustor flows with n-pentane-air chemistry, nonreacting flow in a model double annular combustor, and nonreacting unsteady driven cavity flows. Numerical results for both the steady and unsteady flows demonstrate the efficiency and robustness of the present algorithm for Mach numbers ranging from the incompressible limit to supersonic speeds.

Lens elliptic gamma function solution of the Yang-Baxter equation at roots of unity

NASA Astrophysics Data System (ADS)

Kels, Andrew P.; Yamazaki, Masahito

2018-02-01

We study the root of unity limit of the lens elliptic gamma function solution of the star-triangle relation, for an integrable model with continuous and discrete spin variables. This limit involves taking an elliptic nome to a primitive rNth root of unity, where r is an existing integer parameter of the lens elliptic gamma function, and N is an additional integer parameter. This is a singular limit of the star-triangle relation, and at subleading order of an asymptotic expansion, another star-triangle relation is obtained for a model with discrete spin variables in {Z}rN . Some special choices of solutions of equation of motion are shown to result in well-known discrete spin solutions of the star-triangle relation. The saddle point equations themselves are identified with three-leg forms of ‘3D-consistent’ classical discrete integrable equations, known as Q4 and Q3(δ=0) . We also comment on the implications for supersymmetric gauge theories, and in particular comment on a close parallel with the works of Nekrasov and Shatashvili.

High energy behavior of gravity at large N

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canfora, F.

2006-09-15

A first step in the analysis of the renormalizability of gravity at large N is carried out. Suitable resummations of planar diagrams give rise to a theory in which there is only a finite number of primitive, superficially divergent, Feynman diagrams. The mechanism is similar to the one which makes the 3D Gross-Neveu model renormalizable at large N. The connections with gravitational confinement and Kawai-Lewellen-Tye relations are briefly analyzed. Some potential problems in fulfilling the Zinn-Justin equations are pointed out.

The use of stellite scatterometer winds to drive a primitive equation model of the Indian Ocean: The impact of bandlike sampling

NASA Technical Reports Server (NTRS)

Barnier, Bernard; Capella, Jorge; O'Brien, James J.

1994-01-01

The aim of this study is to evaluate the impact of the bandlike sampling of spaceborne scatterometers on the ability of scatterometer winds to successfully force the mean flow and seasonal cycle of an ocean model in the context of equatorial and tropical dynamics. The equatorial ocean is simulated with a four-layer, primitive equation, reduced gravity model of the Indian Ocean. The variable wind stress used in this study is derived from one year (1988) of 6-hour analyses of the 10-m wind vector over the Indian Ocean performed at the European Centre for Medium-Range Weather Forecasts (ECMWF). It is applied as a forcing at every grid point of the model to drive a reference circulation. Scatterometer winds are simulated from ECMWF winds, using the nominal configurations and orbital parameters of the European Remote Sensing 1 (ERS-1) and NASA Scatterometer (NSCAT) missions. The model is forced in real time under swaths with the raw scatterometer winds of ERS-1 and NSCAT, with a persistence condition (i.e., the wind is kept constsnt until the next passage of the satellite provides a new value). The circulation obtained for each of the scatterometer experiments is compared with the reference circulation. The seasonal circulation of the Indian Ocean with NSCAT winds is very similar to the reference. The perturbations introduced by the bandlike sampling and the persistance condition have an impact similar to that of a small uncorrelated noise added to the reference forcing. The persistence condition for ERS-1 does not give results which are as good as those obtained for NSCAT.

Assimilation of TOPEX/Poseidon altimeter data into a global ocean circulation model: How good are the results?

NASA Astrophysics Data System (ADS)

Fukumori, Ichiro; Raghunath, Ramanujam; Fu, Lee-Lueng; Chao, Yi

1999-11-01

The feasibility of assimilating satellite altimetry data into a global ocean general circulation model is studied. Three years of TOPEX/Poseidon data are analyzed using a global, three-dimensional, nonlinear primitive equation model. The assimilation's success is examined by analyzing its consistency and reliability measured by formal error estimates with respect to independent measurements. Improvements in model solution are demonstrated, in particular, properties not directly measured. Comparisons are performed with sea level measured by tide gauges, subsurface temperatures and currents from moorings, and bottom pressure measurements. Model representation errors dictate what can and cannot be resolved by assimilation, and its identification is emphasized.

Meridionally propagating interannual-to-interdecadal variability in a linear ocean-atmosphere model

NASA Technical Reports Server (NTRS)

Mehta, Vikram M.

1992-01-01

Meridional oscillation modes in a global, primitive-equation coupled ocean-atmosphere model have been analyzed in order to determine whether they contain such meridionally propagating modes as surface-pressure perturbations with years-to-decades oscillation periods. A two-layer global ocean model and a two-level global atmosphere model were then formulated. For realistic parameter values and basic states, meridional modes oscillating at periods of several years to several decades are noted to be present in the coupled ocean-atmosphere model; the oscillation periods, travel times, and meridional structures of surface pressure perturbations in one of the modes are found to be comparable to the corresponding characteristics of observed sea-level pressure perturbations.

Ocean Thermal and Color Evolution During the 1997/1998 ENSO Event

NASA Technical Reports Server (NTRS)

Rienecker, Michele

1998-01-01

A reduced gravity primitive equation modeling and assimilation system is used to study the evolution of the tropical Pacific during the 1997/1998 ENSO cycle. The modeling/assimilation scheme ingests satellite altimeter data and TAO temperature profiles and uses SSM/I satellite derived winds as surface boundary forcing. The four-dimensional structure of the upper ocean circulation structure will be compared against available in situ observations across the Pacific basin. In particular, variability near the Galapagos Islands will be highlighted during the spring of 1998 when phytoplankton concentrations were observed to increase a hundred-fold over a two week period.

The compatible balancing approach to initialization, and four-dimensional data assimilation. [in meteorology

NASA Technical Reports Server (NTRS)

Ghil, M.

1980-01-01

A unified theoretical approach to both the four-dimensional assimilation of asynoptic data and the initialization problem is attempted. This approach relies on the derivation of certain relationships between geopotential tendencies and tendencies of the horizontal velocity field in primitive-equation models of atmospheric flow. The approach is worked out and analyzed in detail for some simple barotropic models. Certain independent results of numerical experiments for the time-continuous assimilation of real asynoptic meteorological data into a complex, baroclinic weather prediction model are discussed in the context of the present approach. Tentative inferences are drawn for practical assimilation procedures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patnaik, P. C.

The SIGMET mesoscale meteorology simulation code represents an extension, in terms of physical modelling detail and numerical approach, of the work of Anthes (1972) and Anthes and Warner (1974). The code utilizes a finite difference technique to solve the so-called primitive equations which describe transient flow in the atmosphere. The SIGMET modelling contains all of the physics required to simulate the time dependent meteorology of a region with description of both the planetary boundary layer and upper level flow as they are affected by synoptic forcing and complex terrain. The mathematical formulation of the SIGMET model and the various physicalmore » effects incorporated into it are summarized.« less

The Spectral Element Method for Geophysical Flows

NASA Astrophysics Data System (ADS)

Taylor, Mark

1998-11-01

We will describe SEAM, a Spectral Element Atmospheric Model. SEAM solves the 3D primitive equations used in climate modeling and medium range forecasting. SEAM uses a spectral element discretization for the surface of the globe and finite differences in the vertical direction. The model is spectrally accurate, as demonstrated by a variety of test cases. It is well suited for modern distributed-shared memory computers, sustaining over 24 GFLOPS on a 240 processor HP Exemplar. This performance has allowed us to run several interesting simulations in full spherical geometry at high resolution (over 22 million grid points).

On Synchronization Primitive Systems.

DTIC Science & Technology

The report studies the question: what synchronization primitive should be used to handle inter-process communication. A formal model is presented...between these synchronization primitives. Although only four synchronization primitives are compared, the general methods can be used to compare other... synchronization primitives. Moreover, in the definitions of these synchronization primitives, conditional branches are explicitly allowed. In addition

Development of a severe local storm prediction system: A 60-day test of a mesoscale primitive equation model

NASA Technical Reports Server (NTRS)

Paine, D. A.; Zack, J. W.; Kaplan, M. L.

1979-01-01

The progress and problems associated with the dynamical forecast system which was developed to predict severe storms are examined. The meteorological problem of severe convective storm forecasting is reviewed. The cascade hypothesis which forms the theoretical core of the nested grid dynamical numerical modelling system is described. The dynamical and numerical structure of the model used during the 1978 test period is presented and a preliminary description of a proposed multigrid system for future experiments and tests is provided. Six cases from the spring of 1978 are discussed to illustrate the model's performance and its problems. Potential solutions to the problems are examined.

A numerical investigation of the President's Day storm of February 18-19, 1979

NASA Technical Reports Server (NTRS)

Nappi, A. J.; Warner, T. T.

1983-01-01

The reported investigation is based on the use of a three-dimensional, primitive equation model. The President's Day storm, formed in the Gulf of Mexico as a massive anticyclone, affected the northern states with record-breaking cold temperatures. Attention is given to the physical processes relevant to storm formation, the forecast model, a description of experiments and model forecasts, and model results. An attempt is made to determine the important dynamic processes at work during the evolution of the storm. The jet streak interactions which occurred in the cyclogenetic environment, the effects of cold air damming, and the formation of a strong mesoscale coastal front are found to be of particular interest.

Development of a three-dimensional Navier-Stokes code on CDC star-100 computer

NASA Technical Reports Server (NTRS)

Vatsa, V. N.; Goglia, G. L.

1978-01-01

A three-dimensional code in body-fitted coordinates was developed using MacCormack's algorithm. The code is structured to be compatible with any general configuration, provided that the metric coefficients for the transformation are available. The governing equations are developed in primitive variables in order to facilitate the incorporation of physical boundary conditions and turbulence-closure models. MacCormack's two-step, unsplit, time-marching algorithm is used to solve the unsteady Navier-Stokes equations until steady-state solution is achieved. Cases discussed include (1) flat plate in supersonic free stream; (2) supersonic flow along an axial corner; (3) subsonic flow in an axial corner at M infinity = 0.95; and (4) supersonic flow in an axial corner at M infinity 1.5.

Multiscale Modeling of Cardiac Cellular Energetics

PubMed Central

BASSINGTHWAIGHTE, JAMES B.; CHIZECK, HOWARD J.; ATLAS, LES E.; QIAN, HONG

2010-01-01

Multiscale modeling is essential to integrating knowledge of human physiology starting from genomics, molecular biology, and the environment through the levels of cells, tissues, and organs all the way to integrated systems behavior. The lowest levels concern biophysical and biochemical events. The higher levels of organization in tissues, organs, and organism are complex, representing the dynamically varying behavior of billions of cells interacting together. Models integrating cellular events into tissue and organ behavior are forced to resort to simplifications to minimize computational complexity, thus reducing the model’s ability to respond correctly to dynamic changes in external conditions. Adjustments at protein and gene regulatory levels shortchange the simplified higher-level representations. Our cell primitive is composed of a set of subcellular modules, each defining an intracellular function (action potential, tricarboxylic acid cycle, oxidative phosphorylation, glycolysis, calcium cycling, contraction, etc.), composing what we call the “eternal cell,” which assumes that there is neither proteolysis nor protein synthesis. Within the modules are elements describing each particular component (i.e., enzymatic reactions of assorted types, transporters, ionic channels, binding sites, etc.). Cell subregions are stirred tanks, linked by diffusional or transporter-mediated exchange. The modeling uses ordinary differential equations rather than stochastic or partial differential equations. This basic model is regarded as a primitive upon which to build models encompassing gene regulation, signaling, and long-term adaptations in structure and function. During simulation, simpler forms of the model are used, when possible, to reduce computation. However, when this results in error, the more complex and detailed modules and elements need to be employed to improve model realism. The processes of error recognition and of mapping between different levels of model form complexity are challenging but are essential for successful modeling of large-scale systems in reasonable time. Currently there is to this end no established methodology from computational sciences. PMID:16093514

Ensemble assimilation of ARGO temperature profile, sea surface temperature and Altimetric satellite data into an eddy permitting primitive equation model of the North Atlantic ocean

NASA Astrophysics Data System (ADS)

Yan, Yajing; Barth, Alexander; Beckers, Jean-Marie; Candille, Guillem; Brankart, Jean-Michel; Brasseur, Pierre

2015-04-01

Sea surface height, sea surface temperature and temperature profiles at depth collected between January and December 2005 are assimilated into a realistic eddy permitting primitive equation model of the North Atlantic Ocean using the Ensemble Kalman Filter. 60 ensemble members are generated by adding realistic noise to the forcing parameters related to the temperature. The ensemble is diagnosed and validated by comparison between the ensemble spread and the model/observation difference, as well as by rank histogram before the assimilation experiments. Incremental analysis update scheme is applied in order to reduce spurious oscillations due to the model state correction. The results of the assimilation are assessed according to both deterministic and probabilistic metrics with observations used in the assimilation experiments and independent observations, which goes further than most previous studies and constitutes one of the original points of this paper. Regarding the deterministic validation, the ensemble means, together with the ensemble spreads are compared to the observations in order to diagnose the ensemble distribution properties in a deterministic way. Regarding the probabilistic validation, the continuous ranked probability score (CRPS) is used to evaluate the ensemble forecast system according to reliability and resolution. The reliability is further decomposed into bias and dispersion by the reduced centred random variable (RCRV) score in order to investigate the reliability properties of the ensemble forecast system. The improvement of the assimilation is demonstrated using these validation metrics. Finally, the deterministic validation and the probabilistic validation are analysed jointly. The consistency and complementarity between both validations are highlighted. High reliable situations, in which the RMS error and the CRPS give the same information, are identified for the first time in this paper.

Beyond ideal magnetohydrodynamics: from fibration to 3  +  1 foliation

NASA Astrophysics Data System (ADS)

Andersson, N.; Hawke, I.; Dionysopoulou, K.; Comer, G. L.

2017-06-01

We consider a resistive multi-fluid framework from the 3  +  1 space-time foliation point-of-view, paying particular attention to issues relating to the use of multi-parameter equations of state and the associated inversion from evolved to primitive variables. We highlight relevant numerical issues that arise for general systems with relative flows. As an application of the new formulation, we consider a three-component system relevant for hot neutron stars. In this case we let the baryons (neutrons and protons) move together, but allow heat and electrons to exhibit relative flow. This reduces the problem to three momentum equations; overall energy-momentum conservation, a generalised Ohm’s law and a heat equation. Our results provide a hierarchy of increasingly complex models and prepare the ground for new state-of-the-art simulations of relevant scenarios in relativistic astrophysics.

A systematic Monte Carlo simulation study of the primitive model planar electrical double layer over an extended range of concentrations, electrode charges, cation diameters and valences

NASA Astrophysics Data System (ADS)

Valiskó, Mónika; Kristóf, Tamás; Gillespie, Dirk; Boda, Dezső

2018-02-01

The purpose of this study is to provide data for the primitive model of the planar electrical double layer, where ions are modeled as charged hard spheres, the solvent as an implicit dielectric background (with dielectric constant ɛ = 78.5), and the electrode as a smooth, uniformly charged, hard wall. We use canonical and grand canonical Monte Carlo simulations to compute the concentration profiles, from which the electric field and electrostatic potential profiles are obtained by solving Poisson's equation. We report data for an extended range of parameters including 1:1, 2:1, and 3:1 electrolytes at concentrations c = 0.0001 - 1 M near electrodes carrying surface charges up to σ = ±0.5 Cm-2. The anions are monovalent with a fixed diameter d- = 3 Å, while the charge and diameter of cations are varied in the range z+ = 1, 2, 3 and d+ = 1.5, 3, 6, and 9 Å (the temperature is 298.15 K). We provide all the raw data in the supplementary material (ftp://ftp.aip.org/epaps/aip_advances/E-AAIDBI-8-084802">supplementary material).

A four-dimensional primitive equation model for coupled coastal-deep ocean studies

NASA Technical Reports Server (NTRS)

Haidvogel, D. B.

1981-01-01

A prototype four dimensional continental shelf/deep ocean model is described. In its present form, the model incorporates the effects of finite amplitude topography, advective nonlinearities, and variable stratification and rotation. The model can be forced either directly by imposed atmospheric windstress and surface pressure distributions, and energetic mean currents imposed by the exterior oceanic circulation; or indirectly by initial distributions of shoreward propagation mesoscale waves and eddies. To avoid concerns over the appropriate specification of 'open' boundary conditions on the cross-shelf and seaward model boundaries, a periodic channel geometry (oriented along-coast) is used. The model employs a traditional finite difference expansion in the cross-shelf direction, and a Fourier (periodic) representation in the long-shelf coordinate.

First-Order System Least-Squares for the Navier-Stokes Equations

NASA Technical Reports Server (NTRS)

Bochev, P.; Cai, Z.; Manteuffel, T. A.; McCormick, S. F.

1996-01-01

This paper develops a least-squares approach to the solution of the incompressible Navier-Stokes equations in primitive variables. As with our earlier work on Stokes equations, we recast the Navier-Stokes equations as a first-order system by introducing a velocity flux variable and associated curl and trace equations. We show that the resulting system is well-posed, and that an associated least-squares principle yields optimal discretization error estimates in the H(sup 1) norm in each variable (including the velocity flux) and optimal multigrid convergence estimates for the resulting algebraic system.

Model-Free Primitive-Based Iterative Learning Control Approach to Trajectory Tracking of MIMO Systems With Experimental Validation.

PubMed

Radac, Mircea-Bogdan; Precup, Radu-Emil; Petriu, Emil M

2015-11-01

This paper proposes a novel model-free trajectory tracking of multiple-input multiple-output (MIMO) systems by the combination of iterative learning control (ILC) and primitives. The optimal trajectory tracking solution is obtained in terms of previously learned solutions to simple tasks called primitives. The library of primitives that are stored in memory consists of pairs of reference input/controlled output signals. The reference input primitives are optimized in a model-free ILC framework without using knowledge of the controlled process. The guaranteed convergence of the learning scheme is built upon a model-free virtual reference feedback tuning design of the feedback decoupling controller. Each new complex trajectory to be tracked is decomposed into the output primitives regarded as basis functions. The optimal reference input for the control system to track the desired trajectory is next recomposed from the reference input primitives. This is advantageous because the optimal reference input is computed straightforward without the need to learn from repeated executions of the tracking task. In addition, the optimization problem specific to trajectory tracking of square MIMO systems is decomposed in a set of optimization problems assigned to each separate single-input single-output control channel that ensures a convenient model-free decoupling. The new model-free primitive-based ILC approach is capable of planning, reasoning, and learning. A case study dealing with the model-free control tuning for a nonlinear aerodynamic system is included to validate the new approach. The experimental results are given.

Modeling the Gulf Stream System: How Far from Reality?

NASA Technical Reports Server (NTRS)

Choa, Yi; Gangopadhyay, Avijit; Bryan, Frank O.; Holland, William R.

1996-01-01

Analyses of a primitive equation ocean model simulation of the Atlantic Ocean circulation at 1/6 deg horizontal resolution are presented with a focus on the Gulf Stream region. Among many successful features of this simulation, this letter describes the Gulf Stream separation from the coast of North America near Cape Hatteras, meandering of the Gulf Stream between Cape Hatteras and the Grand Banks, and the vertical structure of temperature and velocity associated with the Gulf Stream. These results demonstrate significant improvement in modeling the Gulf Stream system using basin- to global scale ocean general circulation models. Possible reasons responsible for the realistic Gulf Stream simulation are discussed, contrasting the major differences between the present model configuration and those of previous eddy resolving studies.

Calculation of wind-driven surface currents in the North Atlantic Ocean

NASA Technical Reports Server (NTRS)

Rees, T. H.; Turner, R. E.

1976-01-01

Calculations to simulate the wind driven near surface currents of the North Atlantic Ocean are described. The primitive equations were integrated on a finite difference grid with a horizontal resolution of 2.5 deg in longitude and latitude. The model ocean was homogeneous with a uniform depth of 100 m and with five levels in the vertical direction. A form of the rigid-lid approximation was applied. Generally, the computed surface current patterns agreed with observed currents. The development of a subsurface equatorial countercurrent was observed.

Entropy jump across an inviscid shock wave

NASA Technical Reports Server (NTRS)

Salas, Manuel D.; Iollo, Angelo

1995-01-01

The shock jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The shock profiles for specific volume, speed, and pressure are shown to be the same, however density has a different shock profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the shock layer. We demonstrate that because of this phenomenon, the entropy, propagation equation cannot be used as a conservation law.

On the time-splitting scheme used in the Princeton Ocean Model

NASA Astrophysics Data System (ADS)

Kamenkovich, V. M.; Nechaev, D. A.

2009-05-01

The analysis of the time-splitting procedure implemented in the Princeton Ocean Model (POM) is presented. The time-splitting procedure uses different time steps to describe the evolution of interacting fast and slow propagating modes. In the general case the exact separation of the fast and slow modes is not possible. The main idea of the analyzed procedure is to split the system of primitive equations into two systems of equations for interacting external and internal modes. By definition, the internal mode varies slowly and the crux of the problem is to determine the proper filter, which excludes the fast component of the external mode variables in the relevant equations. The objective of this paper is to examine properties of the POM time-splitting procedure applied to equations governing the simplest linear non-rotating two-layer model of constant depth. The simplicity of the model makes it possible to study these properties analytically. First, the time-split system of differential equations is examined for two types of the determination of the slow component based on an asymptotic approach or time-averaging. Second, the differential-difference scheme is developed and some criteria of its stability are discussed for centered, forward, or backward time-averaging of the external mode variables. Finally, the stability of the POM time-splitting schemes with centered and forward time-averaging is analyzed. The effect of the Asselin filter on solutions of the considered schemes is studied. It is assumed that questions arising in the analysis of the simplest model are inherent in the general model as well.

Numerical simulations of drainage flows on Mars

NASA Technical Reports Server (NTRS)

Parish, Thomas R.; Howard, Alan D.

1992-01-01

Data collected by Viking Landers have shown that the meteorology of the near surface Martian environment is analogous to desertlike terrestrial conditions. Geological evidence such as dunes and frost streaks indicate that the surface wind is a potentially important factor in scouring of the martian landscape. In particular, the north polar basin shows erosional features that suggest katabatic wind convergence into broad valleys near the margin of the polar cap. The pattern of katabatic wind drainage off the north polar cap is similar to that observed on Earth over Antarctica or Greenland. The sensitivity is explored of Martian drainage flows to variations in terrain slope and diurnal heating using a numerical modeling approach. The model used is a 2-D sigma coordinate primitive equation system that has been used for simulations of Antarctic drainage flows. Prognostic equations include the flux forms of the horizontal scalar momentum equations, temperature, and continuity. Parameterization of both longwave (terrestrial) and shortwave (solar) radiation is included. Turbulent transfer of heat and momentum in the Martian atmosphere remains uncertain since relevant measurements are essentially nonexistent.

A coupled implicit method for chemical non-equilibrium flows at all speeds

NASA Technical Reports Server (NTRS)

Shuen, Jian-Shun; Chen, Kuo-Huey; Choi, Yunho

1993-01-01

The present time-accurate coupled-solution procedure addresses the chemical nonequilibrium Navier-Stokes equations over a wide Mach-number range uses, in conjunction with the strong conservation form of the governing equations, five unknown primitive variables. The numerical tests undertaken address steady convergent-divergent nozzle flows with air dissociation/recombination, dump combustor flows with n-pentane/air chemistry, and unsteady nonreacting cavity flows.

Computational Role of Tunneling in a Programmable Quantum Annealer

NASA Technical Reports Server (NTRS)

Boixo, Sergio; Smelyanskiy, Vadim; Shabani, Alireza; Isakov, Sergei V.; Dykman, Mark; Amin, Mohammad; Mohseni, Masoud; Denchev, Vasil S.; Neven, Hartmut

2016-01-01

Quantum tunneling is a phenomenon in which a quantum state tunnels through energy barriers above the energy of the state itself. Tunneling has been hypothesized as an advantageous physical resource for optimization. Here we present the first experimental evidence of a computational role of multiqubit quantum tunneling in the evolution of a programmable quantum annealer. We developed a theoretical model based on a NIBA Quantum Master Equation to describe the multi-qubit dissipative cotunneling effects under the complex noise characteristics of such quantum devices.We start by considering a computational primitive, the simplest non-convex optimization problem consisting of just one global and one local minimum. The quantum evolutions enable tunneling to the global minimum while the corresponding classical paths are trapped in a false minimum. In our study the non-convex potentials are realized by frustrated networks of qubit clusters with strong intra-cluster coupling. We show that the collective effect of the quantum environment is suppressed in the critical phase during the evolution where quantum tunneling decides the right path to solution. In a later stage dissipation facilitates the multiqubit cotunneling leading to the solution state. The predictions of the model accurately describe the experimental data from the D-WaveII quantum annealer at NASA Ames. In our computational primitive the temperature dependence of the probability of success in the quantum model is opposite to that of the classical paths with thermal hopping. Specially, we provide an analysis of an optimization problem with sixteen qubits,demonstrating eight qubit cotunneling that increases success probabilities. Furthermore, we report results for larger problems with up to 200 qubits that contain the primitive as subproblems.

The birth of numerical weather prediction

NASA Astrophysics Data System (ADS)

Wiin-Nielsen, A.

1991-08-01

The paper describes the major events leading gradually to operational, numerical, short-range predictions for the large-scale atmospheric flow. The theoretical foundation starting with Rossby's studies of the linearized, barotropic equation and ending a decade and a half later with the general formulation of the quasi-geostrophic, baroclinic model by Charney and Phillips is described. The problems connected with the very long waves and the inconsistences of the geostrophic approximation which were major obstacles in the first experimental forecasts are discussed. The resulting changes to divergent barotropic and baroclinic models and to the use of the balance equation are described. After the discussion of the theoretical foundation, the paper describes the major developments leading to the Meteorology Project at the Institute for Advanced Studied under the leadership of John von Neumann and Jule Charney followed by the establishment of the Joint Numerical Weather Prediction Unit in Suitland, Maryland. The interconnected developments in Europe, taking place more-or-less at the same time, are described by concentrating on the activities in Stockholm where the barotropic model was used in many experiments leading also to operational forecasts. The further developments resulting in the use of the primitive equations and the formulation of medium-range forecasting models are not included in the paper.

The birth of numerical weather prediction

NASA Astrophysics Data System (ADS)

Wiin-Nielsen, A.

1991-09-01

The paper describes the major events leading gradually to operational, numerical, short-range predictions for the large-scale atmospheric flow. The theoretical foundation starting with Rossby's studies of the linearized, barotropic equation and ending a decade and a half later with the general formulation of the quasi-geostrophic, baroclinic model by Charney and Phillips is described. The problems connected with the very long waves and the inconsistences of the geostrophic approximation which were major obstacles in the first experimental forecasts are discussed. The resulting changes to divergent barotropic and baroclinic models and to the use of the balance equation are described. After the discussion of the theoretical foundation, the paper describes the major developments leading to the Meteorology Project at the Institute for Advanced Studied under the leadership of John von Neumann and Jule Charney followed by the establishment of the Joint Numerical Weather Prediction Unit in Suitland, Maryland. The inter-connected developments in Europe, taking place more-or-less at the same time, are described by concentrating on the activities in Stockholm where the barotropic model was used in many experiments leading also to operational forecasts. The further developments resulting in the use of the primitive equations and the formulation of medium-range forecasting models are not included in the paper.

MPF: A portable message passing facility for shared memory multiprocessors

NASA Technical Reports Server (NTRS)

Malony, Allen D.; Reed, Daniel A.; Mcguire, Patrick J.

1987-01-01

The design, implementation, and performance evaluation of a message passing facility (MPF) for shared memory multiprocessors are presented. The MPF is based on a message passing model conceptually similar to conversations. Participants (parallel processors) can enter or leave a conversation at any time. The message passing primitives for this model are implemented as a portable library of C function calls. The MPF is currently operational on a Sequent Balance 21000, and several parallel applications were developed and tested. Several simple benchmark programs are presented to establish interprocess communication performance for common patterns of interprocess communication. Finally, performance figures are presented for two parallel applications, linear systems solution, and iterative solution of partial differential equations.

A Computer Code for Swirling Turbulent Axisymmetric Recirculating Flows in Practical Isothermal Combustor Geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.; Rhode, D. L.

1982-01-01

A primitive pressure-velocity variable finite difference computer code was developed to predict swirling recirculating inert turbulent flows in axisymmetric combustors in general, and for application to a specific idealized combustion chamber with sudden or gradual expansion. The technique involves a staggered grid system for axial and radial velocities, a line relaxation procedure for efficient solution of the equations, a two-equation k-epsilon turbulence model, a stairstep boundary representation of the expansion flow, and realistic accommodation of swirl effects. A user's manual, dealing with the computational problem, showing how the mathematical basis and computational scheme may be translated into a computer program is presented. A flow chart, FORTRAN IV listing, notes about various subroutines and a user's guide are supplied as an aid to prospective users of the code.

Learning multivariate distributions by competitive assembly of marginals.

PubMed

Sánchez-Vega, Francisco; Younes, Laurent; Geman, Donald

2013-02-01

We present a new framework for learning high-dimensional multivariate probability distributions from estimated marginals. The approach is motivated by compositional models and Bayesian networks, and designed to adapt to small sample sizes. We start with a large, overlapping set of elementary statistical building blocks, or "primitives," which are low-dimensional marginal distributions learned from data. Each variable may appear in many primitives. Subsets of primitives are combined in a Lego-like fashion to construct a probabilistic graphical model; only a small fraction of the primitives will participate in any valid construction. Since primitives can be precomputed, parameter estimation and structure search are separated. Model complexity is controlled by strong biases; we adapt the primitives to the amount of training data and impose rules which restrict the merging of them into allowable compositions. The likelihood of the data decomposes into a sum of local gains, one for each primitive in the final structure. We focus on a specific subclass of networks which are binary forests. Structure optimization corresponds to an integer linear program and the maximizing composition can be computed for reasonably large numbers of variables. Performance is evaluated using both synthetic data and real datasets from natural language processing and computational biology.

Study of three-dimensional effects on vortex breakdown

NASA Technical Reports Server (NTRS)

Salas, M. D.; Kuruvila, G.

1988-01-01

The incompressible axisymmetric steady Navier-Stokes equations in primitive variables are used to simulate vortex breakdown. The equations, discretized using a second-order, central-difference scheme, are linearized and then solved using an exact LU decomposition, Gaussian elimination, and Newton iteration. Solutions are presented for Reynolds numbers, based on vortex-core radius, as high as 1500. An attempt to study the stability of the axisymmetric solutions against three-dimensional perturbations is discussed.

Quantitative Comparisons of a Coarse-Grid LES with Experimental Data for Backward-Facing Step Flow

NASA Astrophysics Data System (ADS)

McDonough, J. M.

1999-11-01

A novel approach to LES employing an additive decomposition of both solutions and governing equations (similar to ``multi-level'' approaches of Dubois et al.,Dynamic Multilevel Methods and the Simulation of Turbulence, Cambridge University Press, 1999) is presented; its main structural features are lack of filtering of governing equations (instead, solutions are filtered to remove aliasing due to under resolution) and direct modeling of subgrid-scale primitive variables (rather than modeling their correlations) in the manner proposed by Hylin and McDonough (Int. J. Fluid Mech. Res. 26, 228-256, 1999). A 2-D implementation of this formalism is applied to the backward-facing step flow studied experimentally by Driver and Seegmiller (AIAA J. 23, 163-171, 1985) and Driver et al. (AIAA J. 25, 914-919, 1987), and run on grids sufficiently coarse to permit easy extension to 3-D, industrially-realistic problems. Comparisons of computed and experimental mean quantities (velocity profiles, turbulence kinetic energy, reattachment lengths, etc.) and effects of grid refinement will be presented.

Emergence of Functional Hierarchy in a Multiple Timescale Neural Network Model: A Humanoid Robot Experiment

PubMed Central

Yamashita, Yuichi; Tani, Jun

2008-01-01

It is generally thought that skilled behavior in human beings results from a functional hierarchy of the motor control system, within which reusable motor primitives are flexibly integrated into various sensori-motor sequence patterns. The underlying neural mechanisms governing the way in which continuous sensori-motor flows are segmented into primitives and the way in which series of primitives are integrated into various behavior sequences have, however, not yet been clarified. In earlier studies, this functional hierarchy has been realized through the use of explicit hierarchical structure, with local modules representing motor primitives in the lower level and a higher module representing sequences of primitives switched via additional mechanisms such as gate-selecting. When sequences contain similarities and overlap, however, a conflict arises in such earlier models between generalization and segmentation, induced by this separated modular structure. To address this issue, we propose a different type of neural network model. The current model neither makes use of separate local modules to represent primitives nor introduces explicit hierarchical structure. Rather than forcing architectural hierarchy onto the system, functional hierarchy emerges through a form of self-organization that is based on two distinct types of neurons, each with different time properties (“multiple timescales”). Through the introduction of multiple timescales, continuous sequences of behavior are segmented into reusable primitives, and the primitives, in turn, are flexibly integrated into novel sequences. In experiments, the proposed network model, coordinating the physical body of a humanoid robot through high-dimensional sensori-motor control, also successfully situated itself within a physical environment. Our results suggest that it is not only the spatial connections between neurons but also the timescales of neural activity that act as important mechanisms leading to functional hierarchy in neural systems. PMID:18989398

A diagnostic model to estimate winds and small-scale drag from Mars Observer PMIRR data

NASA Technical Reports Server (NTRS)

Barnes, J. R.

1993-01-01

Theoretical and modeling studies indicate that small-scale drag due to breaking gravity waves is likely to be of considerable importance for the circulation in the middle atmospheric region (approximately 40-100 km altitude) on Mars. Recent earth-based spectroscopic observations have provided evidence for the existence of circulation features, in particular, a warm winter polar region, associated with gravity wave drag. Since the Mars Observer PMIRR experiment will obtain temperature profiles extending from the surface up to about 80 km altitude, it will be extensively sampling middle atmospheric regions in which gravity wave drag may play a dominant role. Estimating the drag then becomes crucial to the estimation of the atmospheric winds from the PMIRR-observed temperatures. An interative diagnostic model based upon one previously developed and tested with earth satellite temperature data will be applied to the PMIRR measurements to produce estimates of the small-scale zonal drag and three-dimensional wind fields in the Mars middle atmosphere. This model is based on the primitive equations, and can allow for time dependence (the time tendencies used may be based upon those computed in a Fast Fourier Mapping procedure). The small-scale zonal drag is estimated as the residual in the zonal momentum equation; the horizontal winds having first been estimated from the meridional momentum equation and the continuity equation. The scheme estimates the vertical motions from the thermodynamic equation, and thus needs estimates of the diabatic heating based upon the observed temperatures. The latter will be generated using a radiative model. It is hoped that the diagnostic scheme will be able to produce good estimates of the zonal gravity wave drag in the Mars middle atmosphere, estimates that can then be used in other diagnostic or assimilation efforts, as well as more theoretical studies.

SMP: A solid modeling program version 2.0

NASA Technical Reports Server (NTRS)

Randall, D. P.; Jones, K. H.; Vonofenheim, W. H.; Gates, R. L.; Matthews, C. G.

1986-01-01

The Solid Modeling Program (SMP) provides the capability to model complex solid objects through the composition of primitive geometric entities. In addition to the construction of solid models, SMP has extensive facilities for model editing, display, and analysis. The geometric model produced by the software system can be output in a format compatible with existing analysis programs such as PATRAN-G. The present version of the SMP software supports six primitives: boxes, cones, spheres, paraboloids, tori, and trusses. The details for creating each of the major primitive types is presented. The analysis capabilities of SMP, including interfaces to existing analysis programs, are discussed.

On non-primitively divergent vertices of Yang-Mills theory

NASA Astrophysics Data System (ADS)

Huber, Markus Q.

2017-11-01

Two correlation functions of Yang-Mills beyond the primitively divergent ones, the two-ghost-two-gluon and the four-ghost vertices, are calculated and their influence on lower vertices is examined. Their full (transverse) tensor structure is taken into account. As input, a solution of the full two-point equations - including two-loop terms - is used that respects the resummed perturbative ultraviolet behavior. A clear hierarchy is found with regard to the color structure that reduces the number of relevant dressing functions. The impact of the two-ghost-two-gluon vertex on the three-gluon vertex is negligible, which is explained by the fact that all non-small dressing functions drop out due to their color factors. Only in the ghost-gluon vertex a small net effect below 2% is seen. The four-ghost vertex is found to be extremely small in general. Since these two four-point functions do not enter into the propagator equations, these findings establish their small overall effect on lower correlation functions.

A low-order model of the equatorial ocean-atmosphere system

NASA Astrophysics Data System (ADS)

Legnani, Roberto

A low order model of the equatorial ocean-atmosphere coupled system is presented. The model atmosphere includes a hydrological cycle with cloud-radiation interaction. The model ocean is based on mixed layer dynamics with a parameterization of entrainment processes. The coupling takes place via transfer to momentum, sensible heat, latent heat and short wave and long wave radiation through the ocean surface. The dynamical formulation is that of the primitive equations of an equatorial beta-plane, with zonally periodic and meridionally infinite geometry. The system is expanded into the set of normal modes pertinent to the linear problem and severly truncated to a few modes; 54 degrees of freedom are retained. Some nonlinear terms of the equations are evaluated in physical space and then projected onto the functional space; other terms are evaluated directly in the functional space. Sensitivity tests to variations of the parameters are performed, and some results from 10-year initial value simulations are presented. The model is capable of supporting oscillations of different time scales, ranging from a few days to a few years; it prefers a particular zonally asymmetric state, but temporarily switches to a different (opposite) zonally asymmetric state in an event-like fashion.

a Low-Order Model of the Equatorial Ocean-Atmosphere System.

NASA Astrophysics Data System (ADS)

Legnani, Roberto

A low order model of the equatorial ocean-atmosphere coupled system is presented. The model atmosphere includes a hydrological cycle with cloud-radiation interaction. The model ocean is based on mixed layer dynamics with a parameterization of entrainment processes. The coupling takes place via transfer to momentum, sensible heat, latent heat and short -wave and long-wave radiation through the ocean surface. The dynamical formulation is that of the primitive equations of an equatorial beta-plane, with zonally periodic and meridionally infinite geometry. The system is expanded into the set of normal modes pertinent to the linear problem and severely truncated to a few modes; 54 degrees of freedom are retained. Some nonlinear terms of the equations are evaluated in physical space and then projected onto the functional space; other terms are evaluated directly in the functional space. Sensitivity tests to variations of the parameters are performed, and some results from 10-year initial value simulations are presented. The model is capable of supporting oscillations of different time scales, ranging from a few days to a few years; it prefers a particular zonally asymmetric state, but temporarily switches to a different (opposite) zonally asymmetric state in an event-like fashion.

Effects of subsurface ocean dynamics on instability waves in the tropical Pacific

NASA Astrophysics Data System (ADS)

Lawrence, Sean P.; Allen, Myles R.; Anderson, David L. T.; Llewellyn-Jones, David T.

1998-08-01

Tropical instability waves in a primitive equation model of the tropical Pacific Ocean, forced with analyzed wind stresses updated daily, show unexpectedly close phase correspondence with observation through the latter half of 1992. This suggests that these waves are not pure instabilities developing from infinitesimal disturbances, but that their phases and phase speeds are at least partially determined by the wind stress forcing. To quantify and explain this observation, we perfomed several numerical experiments, which indicate that remotely forced Rossby waves can influence both the phase and phase speed of tropical instability waves. We suggest that a remote wind forcing determines the high model/observation phase correspondence of tropical instability waves through a relatively realistic simulation of equatorial Kelvin and Rossby wave activity.

Operational seasonal and interannual predictions of ocean conditions

NASA Technical Reports Server (NTRS)

Leetmaa, Ants

1992-01-01

Dr. Leetmaa described current work at the U.S. National Meteorological Center (NMC) on coupled systems leading to a seasonal prediction system. He described the way in which ocean thermal data is quality controlled and used in a four dimensional data assimilation system. This consists of a statistical interpolation scheme, a primitive equation ocean general circulation model, and the atmospheric fluxes that are required to force this. This whole process generated dynamically consist thermohaline and velocity fields for the ocean. Currently routine weekly analyses are performed for the Atlantic and Pacific oceans. These analyses are used for ocean climate diagnostics and as initial conditions for coupled forecast models. Specific examples of output products were shown both in the Pacific and the Atlantic Ocean.

Evaluation of the Lattice-Boltzmann Equation Solver PowerFLOW for Aerodynamic Applications

NASA Technical Reports Server (NTRS)

Lockard, David P.; Luo, Li-Shi; Singer, Bart A.; Bushnell, Dennis M. (Technical Monitor)

2000-01-01

A careful comparison of the performance of a commercially available Lattice-Boltzmann Equation solver (Power-FLOW) was made with a conventional, block-structured computational fluid-dynamics code (CFL3D) for the flow over a two-dimensional NACA-0012 airfoil. The results suggest that the version of PowerFLOW used in the investigation produced solutions with large errors in the computed flow field; these errors are attributed to inadequate resolution of the boundary layer for reasons related to grid resolution and primitive turbulence modeling. The requirement of square grid cells in the PowerFLOW calculations limited the number of points that could be used to span the boundary layer on the wing and still keep the computation size small enough to fit on the available computers. Although not discussed in detail, disappointing results were also obtained with PowerFLOW for a cavity flow and for the flow around a generic helicopter configuration.

Response of an eddy-permitting ocean model to the assimilation of sparse in situ data

NASA Astrophysics Data System (ADS)

Li, Jian-Guo; Killworth, Peter D.; Smeed, David A.

2003-04-01

The response of an eddy-permitting ocean model to changes introduced by data assimilation is studied when the available in situ data are sparse in both space and time (typical for the majority of the ocean). Temperature and salinity (T&S) profiles from the WOCE upper ocean thermal data set were assimilated into a primitive equation ocean model over the North Atlantic, using a simple nudging scheme with a time window of about 2 days and a horizontal spatial radius of about 1°. When data are sparse the model returns to its unassimilated behavior, locally "forgetting" or rejecting the assimilation, on timescales determined by the local advection and diffusion. Increasing the spatial weighting radius effectively reduces both processes and hence lengthens the model restoring time (and with it, the impact of assimilation). Increasing the nudging factor enhances the assimilation effect but has little effect on the model restoring time.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arakawa, Akio; Konor, C.S.

Two types of vertical grids are used for atmospheric models: The Lorenz (L grid) and the Charney-Phillips grid (CP grid). In this paper, problems with the L grid are pointed out that are due to the existence of an extra degree of freedom in the vertical distribution of the temperature (and the potential temperature). Then a vertical differencing of the primitive equations based on the CP grid is presented, while most of the advantages of the L grid in a hybrid {sigma}-p vetical coordinate are maintained. The discrete hydrostatic equation is constructed in such a way that it is freemore » from the vertical computational mode in the thermal field. Also, the vertical advection of the potential temperature in the discrete thermodynamic equation is constructed in such a way that it reduces to the standard (and most straightforward) vertical differencing of the quasigeostrophic equations based on the CP grid. Simulations of standing oscillations superposed on a resting atmosphere are presented using two vertically discrete models, one based on the L grid and the other on the CP grid. The comparison of the simulations shows that with the L grid a stationary vertically zigzag pattern dominates in the thermal field, while with the CP grid no such pattern is evident. Simulations of the growth of an extrapolated cyclone in a cyclic channel on a {beta} plan are also presented using two different {sigma}-coordinate models, again one with the L grid and the other with the CP grid, starting from random disturbances. 17 refs., 8 figs.« less

A Global Interpolation Function (GIF) boundary element code for viscous flows

NASA Technical Reports Server (NTRS)

Reddy, D. R.; Lafe, O.; Cheng, A. H-D.

1995-01-01

Using global interpolation functions (GIF's), boundary element solutions are obtained for two- and three-dimensional viscous flows. The solution is obtained in the form of a boundary integral plus a series of global basis functions. The unknown coefficients of the GIF's are determined to ensure the satisfaction of the governing equations at selected collocation points. The values of the coefficients involved in the boundary integral equations are determined by enforcing the boundary conditions. Both primitive variable and vorticity-velocity formulations are examined.

The influence of the equatorial QBO on sudden stratospheric warmings

NASA Technical Reports Server (NTRS)

Holton, James R.; Austin, John

1991-01-01

A global primitive-equation model of the stratosphere and mesosphere is integrated for specified planetary-wave forcing at the 100-mb level with mean zonal flow conditions corresponding to the westerly and easterly phases of the equatorial QBO, respectively. The responses in the two QBO phases were compared for integrations with wavenumber-1 forcing-amplitude maxima at 100 mb and 60 deg N varying from 100 to 400 m. The phase of the QBO had little effect on the results in the weak-wave (100-m) cases, which did not produce warmings, and strong-wave (400-m) cases, which produced major sudden warmings.

A study of the adequacy of quasi-geostrophic dynamics for modeling the effect of frontal cyclones on the larger scale flow

NASA Technical Reports Server (NTRS)

Mudrick, Stephen

1987-01-01

The evolution of individual cyclone waves is studied in order to see how well quasi-geostrophic (QG) dynamics can simulate the behavior of primitive equations (PE) dynamics. This work is an extension of a similar study (Mudrick, 1982); emphasis is placed here on adding a frontal zone and other more diverse features to the basic states used. In addition, sets of PE integrations, with and without friction, are used to study the formation of surface occluded fronts within the evolving cyclones. Results of the study are summarized at the beginning of the report.

A dual potential formulation of the Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Gegg, S. G.; Pletcher, R. H.; Steger, J. L.

1989-01-01

A dual potential formulation for numerically solving the Navier-Stokes equations is developed and presented. The velocity field is decomposed using a scalar and vector potential. Vorticity and dilatation are used as the dependent variables in the momentum equations. Test cases in two dimensions verify the capability to solve flows using approximations from potential flow to full Navier-Stokes simulations. A three-dimensional incompressible flow formulation is also described. An interesting feature of this approach to solving the Navier-Stokes equations is the decomposition of the velocity field into a rotational part (vector potential) and an irrotational part (scalar potential). The Helmholtz decomposition theorem allows this splitting of the velocity field. This approach has had only limited use since it increases the number of dependent variables in the solution. However, it has often been used for incompressible flows where the solution scheme is known to be fast and accurate. This research extends the usage of this method to fully compressible Navier-Stokes simulations by using the dilatation variable along with vorticity. A time-accurate, iterative algorithm is used for the uncoupled solution of the governing equations. Several levels of flow approximation are available within the framework of this method. Potential flow, Euler and full Navier-Stokes solutions are possible using the dual potential formulation. Solution efficiency can be enhanced in a straightforward way. For some flows, the vorticity and/or dilatation may be negligible in certain regions (e.g., far from a viscous boundary in an external flow). It is possible to drop the calculation of these variables then and optimize the solution speed. Also, efficient Poisson solvers are available for the potentials. The relative merits of non-primitive variables versus primitive variables for solution of the Navier-Stokes equations are also discussed.

Next Generation, 4-D Distributed Modeling and Visualization of Battlefield

DTIC Science & Technology

2006-07-14

accurate. However, the effectiveness of such a view is determined by its usability. If the picture contained all the information that had been...major key to success in such missions is the ability to model real-world urban areas accurately and effectively , so as to support US military mission...primitives (including the standard CG primitives such as plane, cube, wedge, polyhedron, cylinder and sphere, and high-order surface primitives such as

On the orbital stability of pendulum-like vibrations of a rigid body carrying a rotor

NASA Astrophysics Data System (ADS)

Yehia, Hamad M.; El-Hadidy, E. G.

2013-09-01

One of the most notable effects in mechanics is the stabilization of the unstable upper equilibrium position of a symmetric body fixed from one point on its axis of symmetry, either by giving the body a suitable angular velocity or by adding a suitably spinned rotor along its axis. This effect is widely used in technology and in space dynamics. The aim of the present article is to explore the effect of the presence of a rotor on a simple periodic motion of the rigid body and its motion as a physical pendulum. The equation in the variation for pendulum vibrations takes the form in which α depends on the moments of inertia, ρ on the gyrostatic momentum of the rotor and ν (the modulus of the elliptic function) depends on the total energy of the motion. This equation, which reduces to Lame's equation when ρ = 0, has not been studied to any extent in the literature. The determination of the zones of stability and instability of plane motion reduces to finding conditions for the existence of primitive periodic solutions (with periods 4 K( ν), 8 K( ν)) with those parameters. Complete analysis of primitive periodic solutions of this equation is performed analogously to that of Ince for Lame's equation. Zones of stability and instability are determined analytically and illustrated in a graphical form by plotting surfaces separating them in the three-dimensional space of parameters. The problem is also solved numerically in certain regions of the parameter space, and results are compared to analytical ones.

Numerical simulation of the world ocean circulation

NASA Technical Reports Server (NTRS)

Takano, K.; Mintz, Y.; Han, Y. J.

1973-01-01

A multi-level model, based on the primitive equations, is developed for simulating the temperature and velocity fields produced in the world ocean by differential heating and surface wind stress. The model ocean has constant depth, free slip at the lower boundary, and neglects momentum advection; so that there is no energy exchange between the barotropic and baroclinic components of the motion, although the former influences the latter through temperature advection. The ocean model was designed to be coupled to the UCLA atmospheric general circulation model, for the study of the dynamics of climate and climate changes. But here, the model is tested by prescribing the observed seasonally varying surface wind stress and the incident solar radiation, the surface air temperature and humidity, cloudiness and the surface wind speed, which, together with the predicted ocean surface temperature, determine the surface flux of radiant energy, sensible heat and latent heat.

Evaluation of the synoptic and mesoscale predictive capabilities of a mesoscale atmospheric simulation system

NASA Technical Reports Server (NTRS)

Koch, S. E.; Skillman, W. C.; Kocin, P. J.; Wetzel, P. J.; Brill, K.; Keyser, D. A.; Mccumber, M. C.

1983-01-01

The overall performance characteristics of a limited area, hydrostatic, fine (52 km) mesh, primitive equation, numerical weather prediction model are determined in anticipation of satellite data assimilations with the model. The synoptic and mesoscale predictive capabilities of version 2.0 of this model, the Mesoscale Atmospheric Simulation System (MASS 2.0), were evaluated. The two part study is based on a sample of approximately thirty 12h and 24h forecasts of atmospheric flow patterns during spring and early summer. The synoptic scale evaluation results benchmark the performance of MASS 2.0 against that of an operational, synoptic scale weather prediction model, the Limited area Fine Mesh (LFM). The large sample allows for the calculation of statistically significant measures of forecast accuracy and the determination of systematic model errors. The synoptic scale benchmark is required before unsmoothed mesoscale forecast fields can be seriously considered.

Space structure vibration modes: How many exist? Which ones are important?

NASA Technical Reports Server (NTRS)

Hughes, P. C.

1984-01-01

This report attempts to shed some light on the two issues raised in the title, namely, how many vibration modes does a real structure have, and which of these modes are important? The surprise-free answers to these two questions are, respectively, an infinite number and the first several modes. The author argues that the absurd subspace (all but the first billion modes) is not a strength of continuum modeling, but, in fact, a weakness. Partial differential equations are not real structures, only mathematical models. This note also explains (1) that the PDE model and the finite element model are, in fact, the same model, the latter being a numerical method for dealing with the former, (2) that modes may be selected on dynamical grounds other than frequency alone, and (3) that long slender rods are useful as primitive cases but dangerous to extrapolate from.

Marching iterative methods for the parabolized and thin layer Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Israeli, M.

1985-01-01

Downstream marching iterative schemes for the solution of the Parabolized or Thin Layer (PNS or TL) Navier-Stokes equations are described. Modifications of the primitive equation global relaxation sweep procedure result in efficient second-order marching schemes. These schemes take full account of the reduced order of the approximate equations as they behave like the SLOR for a single elliptic equation. The improved smoothing properties permit the introduction of Multi-Grid acceleration. The proposed algorithm is essentially Reynolds number independent and therefore can be applied to the solution of the subsonic Euler equations. The convergence rates are similar to those obtained by the Multi-Grid solution of a single elliptic equation; the storage is also comparable as only the pressure has to be stored on all levels. Extensions to three-dimensional and compressible subsonic flows are discussed. Numerical results are presented.

Essential equivalence of the general equation for the nonequilibrium reversible-irreversible coupling (GENERIC) and steepest-entropy-ascent models of dissipation for nonequilibrium thermodynamics.

PubMed

Montefusco, Alberto; Consonni, Francesco; Beretta, Gian Paolo

2015-04-01

By reformulating the steepest-entropy-ascent (SEA) dynamical model for nonequilibrium thermodynamics in the mathematical language of differential geometry, we compare it with the primitive formulation of the general equation for the nonequilibrium reversible-irreversible coupling (GENERIC) model and discuss the main technical differences of the two approaches. In both dynamical models the description of dissipation is of the "entropy-gradient" type. SEA focuses only on the dissipative, i.e., entropy generating, component of the time evolution, chooses a sub-Riemannian metric tensor as dissipative structure, and uses the local entropy density field as potential. GENERIC emphasizes the coupling between the dissipative and nondissipative components of the time evolution, chooses two compatible degenerate structures (Poisson and degenerate co-Riemannian), and uses the global energy and entropy functionals as potentials. As an illustration, we rewrite the known GENERIC formulation of the Boltzmann equation in terms of the square root of the distribution function adopted by the SEA formulation. We then provide a formal proof that in more general frameworks, whenever all degeneracies in the GENERIC framework are related to conservation laws, the SEA and GENERIC models of the dissipative component of the dynamics are essentially interchangeable, provided of course they assume the same kinematics. As part of the discussion, we note that equipping the dissipative structure of GENERIC with the Leibniz identity makes it automatically SEA on metric leaves.

Sea Surface Salinity Variability from Simulations and Observations: Preparing for Aquarius

NASA Technical Reports Server (NTRS)

Jacob, S. Daniel; LeVine, David M.

2010-01-01

Oceanic fresh water transport has been shown to play an important role in the global hydrological cycle. Sea surface salinity (SSS) is representative of the surface fresh water fluxes and the upcoming Aquarius mission scheduled to be launched in December 2010 will provide excellent spatial and temporal SSS coverage to better estimate the net exchange. In most ocean general circulation models, SSS is relaxed to climatology to prevent model drift. While SST remains a well observed variable, relaxing to SST reduces the range of SSS variability in the simulations (Fig.1). The main objective of the present study is to simulate surface tracers using a primitive equation ocean model for multiple forcing data sets to identify and establish a baseline SSS variability. The simulated variability scales are compared to those from near-surface argo salinity measurements.

Scale Dependend Investigations of the Dynamic State Index Concerning the QG-Theory

NASA Astrophysics Data System (ADS)

Mueller, Annette; Névir, Peter

2017-04-01

The Dynamic State Index (DSI) indicates local deviations of the atmospheric flow field from a steady wind solution based on the primitive equations under adiabatic and inviscid conditions. We represent generalizations of the DSI for reduced models given by the quasi-geostrophic theory and the Rossby-model. By applying a Fourier transformation to the circumpolar geopotential height field we demonstrate the characteristic dipole structure of the DSI-field related to atmospheric waves. Furthermore, by applying data of the COSMO-DE model of the German Weather Service (DWD), we compare the vertical profile of all three DSI-parameters concerning classes with and without precipitation. We work out that the relation to precipitation decreases with increasing approximation, but in all scales, it can be shown that the DSI is highly correlated to diabatic processes.

Modeling the quasi-biennial oscillation's effect on the winter stratospheric circulation

NASA Technical Reports Server (NTRS)

O'Sullivan, Donal; Young, Richard E.

1992-01-01

The influence of the equatorial quasi-biennial oscillation (QBO) on the winter middle atmosphere is modeled with a mechanistic global primitive equation model. The model's polar vortex evolution is sensitive to the lower stratosphere's tropical winds, with the polar vortex becoming more (less) disturbed as the lower stratospheric winds are more easterly (westerly). This agrees with the observed relationship between wintertime polar circulation strength and the phase of the QBO in the lower stratosphere. In these experiments it is the extratropical planetary Rossby waves that provide the tropical-extratropical coupling mechanism. More easterly tropical winds in the lower stratosphere act to confine the extratropical Rossby waves farther north and closer to the vortex at the QBO altitudes, weakening the vortex relative to the case of westerly QBO phase. While the QBO winds occur in the lower stratosphere, the anomaly in the polar vortex strength is strongest at higher levels.

Large-Eddy/Reynolds-Averaged Navier-Stokes Simulation of Shock-Train Development in a Coil-Laser Diffuser

DTIC Science & Technology

2014-09-06

as the Riemann solver . The primitive-variable vector Ts kTwvupW ],,,,,,[ ω= is used in the reconstruction. The initial step in the PPM...University’s (NCSU) REACTMB flow solver is used in the present effort. REACTMB solves the Navier-Stokes equations governing a multi-component

Representation primitives, process models and patient data in computer-interpretable clinical practice guidelines: a literature review of guideline representation models.

PubMed

Wang, Dongwen; Peleg, Mor; Tu, Samson W; Boxwala, Aziz A; Greenes, Robert A; Patel, Vimla L; Shortliffe, Edward H

2002-12-18

Representation of clinical practice guidelines in a computer-interpretable format is a critical issue for guideline development, implementation, and evaluation. We studied 11 types of guideline representation models that can be used to encode guidelines in computer-interpretable formats. We have consistently found in all reviewed models that primitives for representation of actions and decisions are necessary components of a guideline representation model. Patient states and execution states are important concepts that closely relate to each other. Scheduling constraints on representation primitives can be modeled as sequences, concurrences, alternatives, and loops in a guideline's application process. Nesting of guidelines provides multiple views to a guideline with different granularities. Integration of guidelines with electronic medical records can be facilitated by the introduction of a formal model for patient data. Data collection, decision, patient state, and intervention constitute four basic types of primitives in a guideline's logic flow. Decisions clarify our understanding on a patient's clinical state, while interventions lead to the change from one patient state to another.

Prediction of convective activity using a system of parasitic-nested numerical models

NASA Technical Reports Server (NTRS)

Perkey, D. J.

1976-01-01

A limited area, three dimensional, moist, primitive equation (PE) model is developed to test the sensitivity of quantitative precipitation forecasts to the initial relative humidity distribution. Special emphasis is placed on the squall-line region. To accomplish the desired goal, time dependent lateral boundaries and a general convective parameterization scheme suitable for mid-latitude systems were developed. The sequential plume convective parameterization scheme presented is designed to have the versatility necessary in mid-latitudes and to be applicable for short-range forecasts. The results indicate that the scheme is able to function in the frontally forced squallline region, in the gently rising altostratus region ahead of the approaching low center, and in the over-riding region ahead of the warm front. Three experiments are discussed.

A study of the dynamics of droughts in Northern Brazil: Observations, theory, and numerical experiments with a global atmospheric circulation model

NASA Technical Reports Server (NTRS)

Shukla, J.; Moura, A. D.

1980-01-01

The monthly mean sea surface temperature anomalies over tropical Altantic and rainfall anomalies over two selected stations for 25 years (1948-1972) were examined. It is found that the most severe drought events are associated with the simultaneous occurrence of warm sea surface temperature anomalies over north and cold sea surface temperature anomalies over south tropical Atlantic. Simultaneous occurrences of warm sea surface temperature anomaly at 15 deg N, 45 deg W and cold sea surface temperature anomaly at 15 deg S, 5 deg W were always associated with negative anomalies of rainfall, and vice versa. A simple primitive equation model is used to calculate the frictionally controlled and thermally driven circulation due to a prescribed heating function in a resting atmosphere.

Detailed Primitive-Based 3d Modeling of Architectural Elements

NASA Astrophysics Data System (ADS)

Remondino, F.; Lo Buglio, D.; Nony, N.; De Luca, L.

2012-07-01

The article describes a pipeline, based on image-data, for the 3D reconstruction of building façades or architectural elements and the successive modeling using geometric primitives. The approach overcome some existing problems in modeling architectural elements and deliver efficient-in-size reality-based textured 3D models useful for metric applications. For the 3D reconstruction, an opensource pipeline developed within the TAPENADE project is employed. In the successive modeling steps, the user manually selects an area containing an architectural element (capital, column, bas-relief, window tympanum, etc.) and then the procedure fits geometric primitives and computes disparity and displacement maps in order to tie visual and geometric information together in a light but detailed 3D model. Examples are reported and commented.

Probabilistic simulation of the human factor in structural reliability

NASA Technical Reports Server (NTRS)

Chamis, C. C.

1993-01-01

A formal approach is described in an attempt to computationally simulate the probable ranges of uncertainties of the human factor in structural probabilistic assessments. A multi-factor interaction equation (MFIE) model has been adopted for this purpose. Human factors such as marital status, professional status, home life, job satisfaction, work load and health, are considered to demonstrate the concept. Parametric studies in conjunction with judgment are used to select reasonable values for the participating factors (primitive variables). Suitability of the MFIE in the subsequently probabilistic sensitivity studies are performed to assess the validity of the whole approach. Results obtained show that the uncertainties for no error range from five to thirty percent for the most optimistic case.

Probabilistic simulation of the human factor in structural reliability

NASA Astrophysics Data System (ADS)

Chamis, Christos C.; Singhal, Surendra N.

1994-09-01

The formal approach described herein computationally simulates the probable ranges of uncertainties for the human factor in probabilistic assessments of structural reliability. Human factors such as marital status, professional status, home life, job satisfaction, work load, and health are studied by using a multifactor interaction equation (MFIE) model to demonstrate the approach. Parametric studies in conjunction with judgment are used to select reasonable values for the participating factors (primitive variables). Subsequently performed probabilistic sensitivity studies assess the suitability of the MFIE as well as the validity of the whole approach. Results show that uncertainties range from 5 to 30 percent for the most optimistic case, assuming 100 percent for no error (perfect performance).

Probabilistic Simulation of the Human Factor in Structural Reliability

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Singhal, Surendra N.

1994-01-01

The formal approach described herein computationally simulates the probable ranges of uncertainties for the human factor in probabilistic assessments of structural reliability. Human factors such as marital status, professional status, home life, job satisfaction, work load, and health are studied by using a multifactor interaction equation (MFIE) model to demonstrate the approach. Parametric studies in conjunction with judgment are used to select reasonable values for the participating factors (primitive variables). Subsequently performed probabilistic sensitivity studies assess the suitability of the MFIE as well as the validity of the whole approach. Results show that uncertainties range from 5 to 30 percent for the most optimistic case, assuming 100 percent for no error (perfect performance).

Application of multi-grid methods for solving the Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Demuren, A. O.

1989-01-01

The application of a class of multi-grid methods to the solution of the Navier-Stokes equations for two-dimensional laminar flow problems is discussed. The methods consist of combining the full approximation scheme-full multi-grid technique (FAS-FMG) with point-, line-, or plane-relaxation routines for solving the Navier-Stokes equations in primitive variables. The performance of the multi-grid methods is compared to that of several single-grid methods. The results show that much faster convergence can be procured through the use of the multi-grid approach than through the various suggestions for improving single-grid methods. The importance of the choice of relaxation scheme for the multi-grid method is illustrated.

Corrigenda of 'explicit wave-averaged primitive equations using a generalized Lagrangian Mean'

NASA Astrophysics Data System (ADS)

Ardhuin, F.; Rascle, N.; Belibassakis, K. A.

2017-05-01

Ardhuin et al. (2008) gave a second-order approximation in the wave slope of the exact Generalized Lagrangian Mean (GLM) equations derived by Andrews and McIntyre (1978), and also performed a coordinate transformation, going from GLM to a 'GLMz' set of equations. That latter step removed the wandering of the GLM mean sea level away from the Eulerian-mean sea level, making the GLMz flow non-divergent. That step contained some inaccuarate statements about the coordinate transformation, while the rest of the paper contained an error on the surface dynamic boundary condition for viscous stresses. I am thankful to Mathias Delpey and Hidenori Aiki for pointing out these errors, which are corrected below.

Application of multi-grid methods for solving the Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Demuren, A. O.

1989-01-01

This paper presents the application of a class of multi-grid methods to the solution of the Navier-Stokes equations for two-dimensional laminar flow problems. The methods consists of combining the full approximation scheme-full multi-grid technique (FAS-FMG) with point-, line- or plane-relaxation routines for solving the Navier-Stokes equations in primitive variables. The performance of the multi-grid methods is compared to those of several single-grid methods. The results show that much faster convergence can be procured through the use of the multi-grid approach than through the various suggestions for improving single-grid methods. The importance of the choice of relaxation scheme for the multi-grid method is illustrated.

Parallel Computation of the Regional Ocean Modeling System (ROMS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, P; Song, Y T; Chao, Y

2005-04-05

The Regional Ocean Modeling System (ROMS) is a regional ocean general circulation modeling system solving the free surface, hydrostatic, primitive equations over varying topography. It is free software distributed world-wide for studying both complex coastal ocean problems and the basin-to-global scale ocean circulation. The original ROMS code could only be run on shared-memory systems. With the increasing need to simulate larger model domains with finer resolutions and on a variety of computer platforms, there is a need in the ocean-modeling community to have a ROMS code that can be run on any parallel computer ranging from 10 to hundreds ofmore » processors. Recently, we have explored parallelization for ROMS using the MPI programming model. In this paper, an efficient parallelization strategy for such a large-scale scientific software package, based on an existing shared-memory computing model, is presented. In addition, scientific applications and data-performance issues on a couple of SGI systems, including Columbia, the world's third-fastest supercomputer, are discussed.« less

Investigate wave-mean flow interaction and transport in the extratropical winter stratosphere

NASA Technical Reports Server (NTRS)

Smith, Anne K.

1993-01-01

The grant supported studies using several models along with observations in order to investigate some questions of wave-mean flow interaction and transport in the extratropical winter stratosphere. A quasi-geostrophic wave model was used to investigate the possibility that resonant growth of planetary wave 2 may have played a role in the sudden stratospheric warming of February 1979. The results of the time-dependent integration support the interpretation of resonance during February, 1979. Because of the possibility that the model treatment of critical line interactions exerted a controlling influence on the atmospheric dynamics, a more accurate model was needed for wave-mean flow interaction studies. A new model was adapted from the 3-dimensional primitive equation model developed by K. Rose and G. Brasseur. In its present form the model is global, rather than hemispheric; it contains an infrared cooling algorithm and a parameterized solar heating; it has parameterized gravity wave drag; and the chemistry has been entirely revised.

Using Abstraction in Explicity Parallel Programs.

DTIC Science & Technology

1991-07-01

However, we only rely on sequential consistency of memory operations. includ- ing reads. writes and any synchronization primitives provided by the...explicit synchronization primitives . This demonstrates the practical power of sequentially consistent memory, as opposed to weaker models of memory that...a small set of synchronization primitives , all pro- cedures have non-waiting specifications. This is in contrast to richer process-oriented

Semantically-Sensitive Macroprocessing

DTIC Science & Technology

1989-12-15

constr uct for protecting critical regions. Given the synchronization primitives P and V, we might implement the following transformation, where...By this we mean that the semantic model for the base language provides a primitive set of concepts, represented by data types and operations...the gener- ation of a (dynamic-) semantically equivalent program fragment ultimately expressible in terms of built-in primitives . Note that static

A finite element method for solving the shallow water equations on the sphere

NASA Astrophysics Data System (ADS)

Comblen, Richard; Legrand, Sébastien; Deleersnijder, Eric; Legat, Vincent

Within the framework of ocean general circulation modeling, the present paper describes an efficient way to discretize partial differential equations on curved surfaces by means of the finite element method on triangular meshes. Our approach benefits from the inherent flexibility of the finite element method. The key idea consists in a dialog between a local coordinate system defined for each element in which integration takes place, and a nodal coordinate system in which all local contributions related to a vectorial degree of freedom are assembled. Since each element of the mesh and each degree of freedom are treated in the same way, the so-called pole singularity issue is fully circumvented. Applied to the shallow water equations expressed in primitive variables, this new approach has been validated against the standard test set defined by [Williamson, D.L., Drake, J.B., Hack, J.J., Jakob, R., Swarztrauber, P.N., 1992. A standard test set for numerical approximations to the shallow water equations in spherical geometry. Journal of Computational Physics 102, 211-224]. Optimal rates of convergence for the P1NC-P1 finite element pair are obtained, for both global and local quantities of interest. Finally, the approach can be extended to three-dimensional thin-layer flows in a straightforward manner.

Topological versus rheological entanglement length in primitive-path analysis protocols, tube models, and slip-link models

NASA Astrophysics Data System (ADS)

Everaers, Ralf

2012-08-01

We show that the front factor appearing in the shear modulus of a phantom network, Gph=(1-2/f)(ρkBT)/Ns, also controls the ratio of the strand length, Ns, and the number of monomers per Kuhn length of the primitive paths, NphPPKuhn, characterizing the average network conformation. In particular, NphPPKuhn=Ns/(1-2/f) and Gph=(ρkBT)/NphPPKuhn. Neglecting the difference between cross-links and slip-links, these results can be transferred to entangled systems and the interpretation of primitive path analysis data. In agreement with the tube model, the analogy to phantom networks suggest that the rheological entanglement length, Nerheo=(ρkBT)/Ge, should equal NePPKuhn. Assuming binary entanglements with f=4 functional junctions, we expect that Nerheo should be twice as large as the topological entanglement length, Netopo. These results are in good agreement with reported primitive path analysis results for model systems and a wide range of polymeric materials. Implications for tube and slip-link models are discussed.

Toward a self-organizing pre-symbolic neural model representing sensorimotor primitives.

PubMed

Zhong, Junpei; Cangelosi, Angelo; Wermter, Stefan

2014-01-01

The acquisition of symbolic and linguistic representations of sensorimotor behavior is a cognitive process performed by an agent when it is executing and/or observing own and others' actions. According to Piaget's theory of cognitive development, these representations develop during the sensorimotor stage and the pre-operational stage. We propose a model that relates the conceptualization of the higher-level information from visual stimuli to the development of ventral/dorsal visual streams. This model employs neural network architecture incorporating a predictive sensory module based on an RNNPB (Recurrent Neural Network with Parametric Biases) and a horizontal product model. We exemplify this model through a robot passively observing an object to learn its features and movements. During the learning process of observing sensorimotor primitives, i.e., observing a set of trajectories of arm movements and its oriented object features, the pre-symbolic representation is self-organized in the parametric units. These representational units act as bifurcation parameters, guiding the robot to recognize and predict various learned sensorimotor primitives. The pre-symbolic representation also accounts for the learning of sensorimotor primitives in a latent learning context.

Toward a self-organizing pre-symbolic neural model representing sensorimotor primitives

PubMed Central

Zhong, Junpei; Cangelosi, Angelo; Wermter, Stefan

2014-01-01

The acquisition of symbolic and linguistic representations of sensorimotor behavior is a cognitive process performed by an agent when it is executing and/or observing own and others' actions. According to Piaget's theory of cognitive development, these representations develop during the sensorimotor stage and the pre-operational stage. We propose a model that relates the conceptualization of the higher-level information from visual stimuli to the development of ventral/dorsal visual streams. This model employs neural network architecture incorporating a predictive sensory module based on an RNNPB (Recurrent Neural Network with Parametric Biases) and a horizontal product model. We exemplify this model through a robot passively observing an object to learn its features and movements. During the learning process of observing sensorimotor primitives, i.e., observing a set of trajectories of arm movements and its oriented object features, the pre-symbolic representation is self-organized in the parametric units. These representational units act as bifurcation parameters, guiding the robot to recognize and predict various learned sensorimotor primitives. The pre-symbolic representation also accounts for the learning of sensorimotor primitives in a latent learning context. PMID:24550798

A numerical world ocean general circulation model Part I. Basic design and barotropic experiment

NASA Astrophysics Data System (ADS)

Han, Young-June

1984-08-01

A new six-layer world ocean general circulation model based on the primitive system of equations is described in detail and its performance in the case of a homogeneous ocean is described. These test integrations show that the model is capable of reproducing the observed mean barotropic or vertically-integrated transport, as well as the seasonal variability of the major ocean gyres. The surface currents, however, are dominated by the Ekman transport, and such non-linear features as the western boundary currents and the equatorial countercurrents are poorly represented. The abyssal boundary countercurrents are also absent due to the lack of thermohaline forcing. The most conspicuous effect of the bottom topography on a homogeneous ocean is seen in the Southern ocean where the calculated Antarctic circumpolar transport through the Drake passage ( ≈ 10 Sv, with bathymetry included) greatly underestimates the observed transport (≈ 100 Sv).

A Preliminary Model Study of the Large-Scale Seasonal Cycle in Bottom Pressure Over the Global Ocean

NASA Technical Reports Server (NTRS)

Ponte, Rui M.

1998-01-01

Output from the primitive equation model of Semtner and Chervin is used to examine the seasonal cycle in bottom pressure (Pb) over the global ocean. Effects of the volume-conserving formulation of the model on the calculation Of Pb are considered. The estimated seasonal, large-scale Pb signals have amplitudes ranging from less than 1 cm over most of the deep ocean to several centimeters over shallow, boundary regions. Variability generally increases toward the western sides of the basins, and is also larger in some Southern Ocean regions. An oscillation between subtropical and higher latitudes in the North Pacific is clear. Comparison with barotropic simulations indicates that, on basin scales, seasonal Pb variability is related to barotropic dynamics and the seasonal cycle in Ekman pumping, and results from a small, net residual in mass divergence from the balance between Ekman and Sverdrup flows.

Simulation of Wave-Current Interaction Using a Three-Dimensional Hydrodynamic Model Coupled With a Phase Averaged Wave Model

NASA Astrophysics Data System (ADS)

Marsooli, R.; Orton, P. M.; Georgas, N.; Blumberg, A. F.

2016-02-01

The Stevens Institute of Technology Estuarine and Coastal Ocean Model (sECOM) has been coupled with a more advanced surface wave model to simulate wave‒current interaction, and results have been validated in estuarine and nearshore waters. sECOM is a three‒dimensional, hydrostatic, free surface, primitive equation model. It solves the Navier‒Stokes equations and the conservation equations for temperature and salinity using a finite‒difference method on an Arakawa C‒grid with a terrain‒following (sigma) vertical coordinate and orthogonal curvilinear horizontal coordinate system. The model is coupled with the surface wave model developed by Mellor et al. (2008), which solves the spectral equation and takes into account depth and current refraction, and deep and shallow water. The wave model parameterizes the energy distribution in frequency space and the wave‒wave interaction process by using a specified spectrum shape. The coupled wave‒hydrodynamic model considers the wave‒current interaction through wave‒induced bottom stress, depth‒dependent radiation stress, and wave effects on wind‒induced surface stress. The model is validated using the data collected at a natural sandy beach at Duck, North Carolina, during the DUCK94 experiment. This test case reveals the capability of the model to simulate the wave‒current interaction in nearshore coastal systems. The model is further validated using the data collected in Jamaica Bay, a semi‒enclosed body of water located in New York City region. This test reveals the applicability of the model to estuarine systems. These validations of the model and comparisons to its prior wave model, the Great Lakes Environmental Research Laboratory (GLERL) wave model (Donelan 1977), are presented and discussed. ReferencesG.L. Mellor, M.A. Donelan, and L‒Y. Oey, 2008, A Surface Wave Model for Coupling with Numerical Ocean Circulation Models. J. Atmos. Oceanic Technol., 25, 1785‒1807.Donelan, M. A 1977. A simple numerical model for wave and wind stress application. Report, National Water Research Institute, Burlington, Ontario, Canada, 28 pp.

Energy variational analysis of ions in water and channels: Field theory for primitive models of complex ionic fluids

PubMed Central

Eisenberg, Bob; Hyon, YunKyong; Liu, Chun

2010-01-01

Ionic solutions are mixtures of interacting anions and cations. They hardly resemble dilute gases of uncharged noninteracting point particles described in elementary textbooks. Biological and electrochemical solutions have many components that interact strongly as they flow in concentrated environments near electrodes, ion channels, or active sites of enzymes. Interactions in concentrated environments help determine the characteristic properties of electrodes, enzymes, and ion channels. Flows are driven by a combination of electrical and chemical potentials that depend on the charges, concentrations, and sizes of all ions, not just the same type of ion. We use a variational method EnVarA (energy variational analysis) that combines Hamilton’s least action and Rayleigh’s dissipation principles to create a variational field theory that includes flow, friction, and complex structure with physical boundary conditions. EnVarA optimizes both the action integral functional of classical mechanics and the dissipation functional. These functionals can include entropy and dissipation as well as potential energy. The stationary point of the action is determined with respect to the trajectory of particles. The stationary point of the dissipation is determined with respect to rate functions (such as velocity). Both variations are written in one Eulerian (laboratory) framework. In variational analysis, an “extra layer” of mathematics is used to derive partial differential equations. Energies and dissipations of different components are combined in EnVarA and Euler–Lagrange equations are then derived. These partial differential equations are the unique consequence of the contributions of individual components. The form and parameters of the partial differential equations are determined by algebra without additional physical content or assumptions. The partial differential equations of mixtures automatically combine physical properties of individual (unmixed) components. If a new component is added to the energy or dissipation, the Euler–Lagrange equations change form and interaction terms appear without additional adjustable parameters. EnVarA has previously been used to compute properties of liquid crystals, polymer fluids, and electrorheological fluids containing solid balls and charged oil droplets that fission and fuse. Here we apply EnVarA to the primitive model of electrolytes in which ions are spheres in a frictional dielectric. The resulting Euler–Lagrange equations include electrostatics and diffusion and friction. They are a time dependent generalization of the Poisson–Nernst–Planck equations of semiconductors, electrochemistry, and molecular biophysics. They include the finite diameter of ions. The EnVarA treatment is applied to ions next to a charged wall, where layering is observed. Applied to an ion channel, EnVarA calculates a quick transient pile-up of electric charge, transient and steady flow through the channel, stationary “binding” in the channel, and the eventual accumulation of salts in “unstirred layers” near channels. EnVarA treats electrolytes in a unified way as complex rather than simple fluids. Ad hoc descriptions of interactions and flow have been used in many areas of science to deal with the nonideal properties of electrolytes. It seems likely that the variational treatment can simplify, unify, and perhaps derive and improve those descriptions. PMID:20849161

A Variational Assimilation Method for Satellite and Conventional Data: a Revised Basic Model 2B

NASA Technical Reports Server (NTRS)

Achtemeier, Gary L.; Scott, Robert W.; Chen, J.

1991-01-01

A variational objective analysis technique that modifies observations of temperature, height, and wind on the cyclone scale to satisfy the five 'primitive' model forecast equations is presented. This analysis method overcomes all of the problems that hindered previous versions, such as over-determination, time consistency, solution method, and constraint decoupling. A preliminary evaluation of the method shows that it converges rapidly, the divergent part of the wind is strongly coupled in the solution, fields of height and temperature are well-preserved, and derivative quantities such as vorticity and divergence are improved. Problem areas are systematic increases in the horizontal velocity components, and large magnitudes of the local tendencies of the horizontal velocity components. The preliminary evaluation makes note of these problems but detailed evaluations required to determine the origin of these problems await future research.

The logical primitives of thought: Empirical foundations for compositional cognitive models.

PubMed

Piantadosi, Steven T; Tenenbaum, Joshua B; Goodman, Noah D

2016-07-01

The notion of a compositional language of thought (LOT) has been central in computational accounts of cognition from earliest attempts (Boole, 1854; Fodor, 1975) to the present day (Feldman, 2000; Penn, Holyoak, & Povinelli, 2008; Fodor, 2008; Kemp, 2012; Goodman, Tenenbaum, & Gerstenberg, 2015). Recent modeling work shows how statistical inferences over compositionally structured hypothesis spaces might explain learning and development across a variety of domains. However, the primitive components of such representations are typically assumed a priori by modelers and theoreticians rather than determined empirically. We show how different sets of LOT primitives, embedded in a psychologically realistic approximate Bayesian inference framework, systematically predict distinct learning curves in rule-based concept learning experiments. We use this feature of LOT models to design a set of large-scale concept learning experiments that can determine the most likely primitives for psychological concepts involving Boolean connectives and quantification. Subjects' inferences are most consistent with a rich (nonminimal) set of Boolean operations, including first-order, but not second-order, quantification. Our results more generally show how specific LOT theories can be distinguished empirically. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Viscous flow computations using a second-order upwind differencing scheme

NASA Technical Reports Server (NTRS)

Chen, Y. S.

1988-01-01

In the present computations of a wide range of fluid flow problems by means of the primitive variables-incorporating Navier-Stokes equations, a mixed second-order upwinding scheme approximates the convective terms of the transport equations and the scheme's accuracy is verified for convection-dominated high Re number flow problems. An adaptive dissipation scheme is used as a monotonic supersonic shock flow capture mechanism. Many benchmark fluid flow problems, including the compressible and incompressible, laminar and turbulent, over a wide range of M and Re numbers, are presently studied to verify the accuracy and robustness of this numerical method.

A real-time robot arm collision detection system

NASA Technical Reports Server (NTRS)

Shaffer, Clifford A.; Herb, Gregory M.

1990-01-01

A data structure and update algorithm are presented for a prototype real time collision detection safety system for a multi-robot environment. The data structure is a variant of the octree, which serves as a spatial index. An octree recursively decomposes 3-D space into eight equal cubic octants until each octant meets some decomposition criteria. The octree stores cylspheres (cylinders with spheres on each end) and rectangular solids as primitives (other primitives can easily be added as required). These primitives make up the two seven degrees-of-freedom robot arms and environment modeled by the system. Octree nodes containing more than a predetermined number N of primitives are decomposed. This rule keeps the octree small, as the entire environment for the application can be modeled using a few dozen primitives. As robot arms move, the octree is updated to reflect their changed positions. During most update cycles, any given primitive does not change which octree nodes it is in. Thus, modification to the octree is rarely required. Incidents in which one robot arm comes too close to another arm or an object are reported. Cycle time for interpreting current joint angles, updating the octree, and detecting/reporting imminent collisions averages 30 milliseconds on an Intel 80386 processor running at 20 MHz.

Synchronized Trajectories in a Climate "Supermodel"

NASA Astrophysics Data System (ADS)

Duane, Gregory; Schevenhoven, Francine; Selten, Frank

2017-04-01

Differences in climate projections among state-of-the-art models can be resolved by connecting the models in run-time, either through inter-model nudging or by directly combining the tendencies for corresponding variables. Since it is clearly established that averaging model outputs typically results in improvement as compared to any individual model output, averaged re-initializations at typical analysis time intervals also seems appropriate. The resulting "supermodel" is more like a single model than it is like an ensemble, because the constituent models tend to synchronize even with limited inter-model coupling. Thus one can examine the properties of specific trajectories, rather than averaging the statistical properties of the separate models. We apply this strategy to a study of the index cycle in a supermodel constructed from several imperfect copies of the SPEEDO model (a global primitive-equation atmosphere-ocean-land climate model). As with blocking frequency, typical weather statistics of interest like probabilities of heat waves or extreme precipitation events, are improved as compared to the standard multi-model ensemble approach. In contrast to the standard approach, the supermodel approach provides detailed descriptions of typical actual events.

Primitive erythrocytes are generated from hemogenic endothelial cells.

PubMed

Stefanska, Monika; Batta, Kiran; Patel, Rahima; Florkowska, Magdalena; Kouskoff, Valerie; Lacaud, Georges

2017-07-25

Primitive erythroblasts are the first blood cells generated during embryonic hematopoiesis. Tracking their emergence both in vivo and in vitro has remained challenging due to the lack of specific cell surface markers. To selectively investigate primitive erythropoiesis, we have engineered a new transgenic embryonic stem (ES) cell line, where eGFP expression is driven by the regulatory sequences of the embryonic βH1 hemoglobin gene expressed specifically in primitive erythroid cells. Using this ES cell line, we observed that the first primitive erythroblasts are detected in vitro around day 1.5 of blast colony differentiation, within the cell population positive for the early hematopoietic progenitor marker CD41. Moreover, we establish that these eGFP + cells emerge from a hemogenic endothelial cell population similarly to their definitive hematopoietic counterparts. We further generated a corresponding βH1-eGFP transgenic mouse model and demonstrated the presence of a primitive erythroid primed hemogenic endothelial cell population in the developing embryo. Taken together, our findings demonstrate that both in vivo and in vitro primitive erythrocytes are generated from hemogenic endothelial cells.

Essential roles for Cdx in murine primitive hematopoiesis.

PubMed

Brooke-Bisschop, Travis; Savory, Joanne G A; Foley, Tanya; Ringuette, Randy; Lohnes, David

2017-02-15

The Cdx transcription factors play essential roles in primitive hematopoiesis in the zebrafish where they exert their effects, in part, through regulation of hox genes. Defects in hematopoiesis have also been reported in Cdx mutant murine embryonic stem cell models, however, to date no mouse model reflecting the zebrafish Cdx mutant hematopoietic phenotype has been described. This is likely due, in part, to functional redundancy among Cdx members and the early lethality of Cdx2 null mutants. To circumvent these limitations, we used Cre-mediated conditional deletion to assess the impact of concomitant loss of Cdx1 and Cdx2 on murine primitive hematopoiesis. We found that Cdx1/Cdx2 double mutants exhibited defects in primitive hematopoiesis and yolk sac vasculature concomitant with reduced expression of several genes encoding hematopoietic transcription factors including Scl/Tal1. Chromatin immunoprecipitation analysis revealed that Scl was occupied by Cdx2 in vivo, and Cdx mutant hematopoietic yolk sac differentiation defects could be rescued by expression of exogenous Scl. These findings demonstrate critical roles for Cdx members in murine primitive hematopoiesis upstream of Scl. Copyright © 2017 Elsevier Inc. All rights reserved.

Oparin's coacervates as an important milestone in chemical evolution

NASA Astrophysics Data System (ADS)

Kolb, Vera M.

2015-09-01

Although Oparin's coacervate model for the origin of life by chemical evolution is almost 100 years old, it is still valid. However, the structure of his originally proposed coacervate is not considered prebiotic, based on some recent developments in prebiotic chemistry. We have remedied this deficiency of the Oparin's model, by substituting his coacervate with a prebiotically feasible one. Oparin's coacervates are aqueous structures, but have a boundary with the rest of the aqueous medium. They exhibit properties of self-replication, and provide a path to a primitive metabolism, via chemical competition and thus a primitive selection. Thus, coacervates are good models for proto-cells. We review here some salient points of Oparin's model and address also some philosophical views on the beginning of natural selection in primitive chemical systems.

Linearized simulation of flow over wind farms and complex terrains.

PubMed

Segalini, Antonio

2017-04-13

The flow over complex terrains and wind farms is estimated here by numerically solving the linearized Navier-Stokes equations. The equations are linearized around the unperturbed incoming wind profile, here assumed logarithmic. The Boussinesq approximation is used to model the Reynolds stress with a prescribed turbulent eddy viscosity profile. Without requiring the boundary-layer approximation, two new linear equations are obtained for the vertical velocity and the wall-normal vorticity, with a reduction in the computational cost by a factor of 8 when compared with a primitive-variables formulation. The presence of terrain elevation is introduced as a vertical coordinate shift, while forestry or wind turbines are included as body forces, without any assumption about the wake structure for the turbines. The model is first validated against some available experiments and simulations, and then a simulation of a wind farm over a Gaussian hill is performed. The speed-up effect of the hill is clearly beneficial in terms of the available momentum upstream of the crest, while downstream of it the opposite can be said as the turbines face a decreased wind speed. Also, the presence of the hill introduces an additional spanwise velocity component that may also affect the turbines' operations. The linear superposition of the flow over the hill and the flow over the farm alone provided a first estimation of the wind speed along the farm, with discrepancies of the same order of magnitude for the spanwise velocity. Finally, the possibility of using a parabolic set of equations to obtain the turbulent kinetic energy after the linearized model is investigated with promising results.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Author(s).

Linearized simulation of flow over wind farms and complex terrains

NASA Astrophysics Data System (ADS)

Segalini, Antonio

2017-03-01

The flow over complex terrains and wind farms is estimated here by numerically solving the linearized Navier-Stokes equations. The equations are linearized around the unperturbed incoming wind profile, here assumed logarithmic. The Boussinesq approximation is used to model the Reynolds stress with a prescribed turbulent eddy viscosity profile. Without requiring the boundary-layer approximation, two new linear equations are obtained for the vertical velocity and the wall-normal vorticity, with a reduction in the computational cost by a factor of 8 when compared with a primitive-variables formulation. The presence of terrain elevation is introduced as a vertical coordinate shift, while forestry or wind turbines are included as body forces, without any assumption about the wake structure for the turbines. The model is first validated against some available experiments and simulations, and then a simulation of a wind farm over a Gaussian hill is performed. The speed-up effect of the hill is clearly beneficial in terms of the available momentum upstream of the crest, while downstream of it the opposite can be said as the turbines face a decreased wind speed. Also, the presence of the hill introduces an additional spanwise velocity component that may also affect the turbines' operations. The linear superposition of the flow over the hill and the flow over the farm alone provided a first estimation of the wind speed along the farm, with discrepancies of the same order of magnitude for the spanwise velocity. Finally, the possibility of using a parabolic set of equations to obtain the turbulent kinetic energy after the linearized model is investigated with promising results. This article is part of the themed issue 'Wind energy in complex terrains'.

Perceptual integration of kinematic components in the recognition of emotional facial expressions.

PubMed

Chiovetto, Enrico; Curio, Cristóbal; Endres, Dominik; Giese, Martin

2018-04-01

According to a long-standing hypothesis in motor control, complex body motion is organized in terms of movement primitives, reducing massively the dimensionality of the underlying control problems. For body movements, this low-dimensional organization has been convincingly demonstrated by the learning of low-dimensional representations from kinematic and EMG data. In contrast, the effective dimensionality of dynamic facial expressions is unknown, and dominant analysis approaches have been based on heuristically defined facial "action units," which reflect contributions of individual face muscles. We determined the effective dimensionality of dynamic facial expressions by learning of a low-dimensional model from 11 facial expressions. We found an amazingly low dimensionality with only two movement primitives being sufficient to simulate these dynamic expressions with high accuracy. This low dimensionality is confirmed statistically, by Bayesian model comparison of models with different numbers of primitives, and by a psychophysical experiment that demonstrates that expressions, simulated with only two primitives, are indistinguishable from natural ones. In addition, we find statistically optimal integration of the emotion information specified by these primitives in visual perception. Taken together, our results indicate that facial expressions might be controlled by a very small number of independent control units, permitting very low-dimensional parametrization of the associated facial expression.

A zonally symmetric model for the monsoon-Hadley circulation with stochastic convective forcing

NASA Astrophysics Data System (ADS)

De La Chevrotière, Michèle; Khouider, Boualem

2017-02-01

Idealized models of reduced complexity are important tools to understand key processes underlying a complex system. In climate science in particular, they are important for helping the community improve our ability to predict the effect of climate change on the earth system. Climate models are large computer codes based on the discretization of the fluid dynamics equations on grids of horizontal resolution in the order of 100 km, whereas unresolved processes are handled by subgrid models. For instance, simple models are routinely used to help understand the interactions between small-scale processes due to atmospheric moist convection and large-scale circulation patterns. Here, a zonally symmetric model for the monsoon circulation is presented and solved numerically. The model is based on the Galerkin projection of the primitive equations of atmospheric synoptic dynamics onto the first modes of vertical structure to represent free tropospheric circulation and is coupled to a bulk atmospheric boundary layer (ABL) model. The model carries bulk equations for water vapor in both the free troposphere and the ABL, while the processes of convection and precipitation are represented through a stochastic model for clouds. The model equations are coupled through advective nonlinearities, and the resulting system is not conservative and not necessarily hyperbolic. This makes the design of a numerical method for the solution of this system particularly difficult. Here, we develop a numerical scheme based on the operator time-splitting strategy, which decomposes the system into three pieces: a conservative part and two purely advective parts, each of which is solved iteratively using an appropriate method. The conservative system is solved via a central scheme, which does not require hyperbolicity since it avoids the Riemann problem by design. One of the advective parts is a hyperbolic diagonal matrix, which is easily handled by classical methods for hyperbolic equations, while the other advective part is a nilpotent matrix, which is solved via the method of lines. Validation tests using a synthetic exact solution are presented, and formal second-order convergence under grid refinement is demonstrated. Moreover, the model is tested under realistic monsoon conditions, and the ability of the model to simulate key features of the monsoon circulation is illustrated in two distinct parameter regimes.

Quantifying chain reptation in entangled polymer melts: Topological and dynamical mapping of atomistic simulation results onto the tube model

NASA Astrophysics Data System (ADS)

Stephanou, Pavlos S.; Baig, Chunggi; Tsolou, Georgia; Mavrantzas, Vlasis G.; Kröger, Martin

2010-03-01

The topological state of entangled polymers has been analyzed recently in terms of primitive paths which allowed obtaining reliable predictions of the static (statistical) properties of the underlying entanglement network for a number of polymer melts. Through a systematic methodology that first maps atomistic molecular dynamics (MD) trajectories onto time trajectories of primitive chains and then documents primitive chain motion in terms of a curvilinear diffusion in a tubelike region around the coarse-grained chain contour, we are extending these static approaches here even further by computing the most fundamental function of the reptation theory, namely, the probability ψ(s,t) that a segment s of the primitive chain remains inside the initial tube after time t, accounting directly for contour length fluctuations and constraint release. The effective diameter of the tube is independently evaluated by observing tube constraints either on atomistic displacements or on the displacement of primitive chain segments orthogonal to the initial primitive path. Having computed the tube diameter, the tube itself around each primitive path is constructed by visiting each entanglement strand along the primitive path one after the other and approximating it by the space of a small cylinder having the same axis as the entanglement strand itself and a diameter equal to the estimated effective tube diameter. Reptation of the primitive chain longitudinally inside the effective constraining tube as well as local transverse fluctuations of the chain driven mainly from constraint release and regeneration mechanisms are evident in the simulation results; the latter causes parts of the chains to venture outside their average tube surface for certain periods of time. The computed ψ(s,t) curves account directly for both of these phenomena, as well as for contour length fluctuations, since all of them are automatically captured in the atomistic simulations. Linear viscoelastic properties such as the zero shear rate viscosity and the spectra of storage and loss moduli obtained on the basis of the obtained ψ(s,t) curves for three different polymer melts (polyethylene, cis-1,4-polybutadiene, and trans-1,4-polybutadiene) are consistent with experimental rheological data and in qualitative agreement with the double reptation and dual constraint models. The new methodology is general and can be routinely applied to analyze primitive path dynamics and chain reptation in atomistic trajectories (accumulated through long MD simulations) of other model polymers or polymeric systems (e.g., bidisperse, branched, grafted, etc.); it is thus believed to be particularly useful in the future in evaluating proposed tube models and developing more accurate theories for entangled systems.

Inference of dust opacities for the 1977 Martian great dust storms from Viking Lander 1 pressure data

NASA Technical Reports Server (NTRS)

Zurek, R. W.

1981-01-01

The tidal heating components for the dusty Martian atmosphere are computed based on dust optical parameters estimated from Viking Lander imaging data, and used to compute the variation of the tidal surface pressure components at the Viking Lander sites as a function of season and the total vertical extinction optical depth of the atmosphere. An atmospheric tidal model is used which is based on the inviscid, hydrostatic primitive equations linearized about a motionless basic state the temperature of which varies only with height, and the profiles of the tidal forcing components are computed using a delta-Eddington approximation to the radiative transfer equations. Comparison of the model results with the observed variations of surface pressure and overhead dust opacity at the Viking Lander 1 site reveal that the dust opacities and optical parameters derived from imaging data are roughly representative of the global dust haze necessary to reproduce the observed surface pressure amplitudes, with the exception of the model-inferred asymmetry parameter, which is smaller during the onset of a great storm. The observed preferential enhancement of the semidiurnal tide with respect to the diurnal tide during dust storm onset is shown to be due primarily to the elevation of the tidal heating source in a very dusty atmosphere.

A Guide to FASTGEN Target Geometric Modeling

DTIC Science & Technology

1993-10-01

component part is described in plate mode. These rules apply to all primitives with the exception of rod mode primitives which are always accompanied by a...format. A detailed discussion of the rules for preparing the target description file, where components are described using primitives defined as triangles...NN position is 99, the diameter of a rod mode component is limited to a maximum of 1.98-inches. Theie are several rules and cautions associated with

Quadruped robots' modular trajectories: Stability issues

NASA Astrophysics Data System (ADS)

Pinto, Carla M. A.

2012-09-01

Pinto, Santos, Rocha and Matos [13, 12] study a CPG model for the generation of modular trajectories of quadruped robots. They consider that each movement is composed of two types of primitives: rhythmic and discrete. The rhythmic primitive models the periodic patterns and the discrete primitive is inserted as a perturbation of those patterns. In this paper we begin to tackle numerically the problem of the stability of that mathematical model. We observe that if the discrete part is inserted in all limbs, with equal values, and as an offset of the rhythmic part, the obtained gait is stable and has the same spatial and spatio-temporal symmetry groups as the purely rhythmic gait, differing only on the value of the offset.

New numerical determination of habitability in the Galaxy: the SETI connection

NASA Astrophysics Data System (ADS)

Ramirez, Rodrigo; Gómez-Muñoz, Marco A.; Vázquez, Roberto; Núñez, Patricia G.

2018-01-01

In this paper, we determine the habitability of Sun-like stars in the Galaxy using Monte Carlo simulations, which are guided by the factors of the Drake Equation for the considerations on the astrophysical and biological parameters needed to generate and maintain life on a planet's surface. We used a simple star distribution, initial mass function and star formation history to reproduce the properties and distribution of stars within the Galaxy. Using updated exoplanet data from the Kepler mission, we assign planets to some of the stars, and then follow the evolution of life on the planets that met the habitability criteria using two different civilization hypotheses. We predict that around 51% of Earth-like planets in the habitable zone (HZ) are inhabited by primitive life and 4% by technological life. We apply the results to the Kepler field of view, and predicted that there should be at least six Earth-like planets in the HZ, three of them inhabited by primitive life. According to our model, non-technological life is very common if there are the right conditions, but communicative civilizations are less likely to exist and detect. Nonetheless, we predict a considerable number of detectable civilizations within our Galaxy, making it worthwhile to keep searching.

Deuterium enrichment in the primitive ices of the protosolar nebula

NASA Technical Reports Server (NTRS)

Lutz, Barry L.; Owen, Tobias; De Bergh, Catherine

1990-01-01

On the basis of CH3D/CH4-ratio observations in the outer planets, the present effort to estimate the D/H ratio of the protosolar nebula's primitive ices arrives at two simple, yet effectively limiting models which constrain the degree of dilution undergone by deuterated volatiles through mixing with the initial hydrogen envelopes. These volatiles would have been contributed to planetary atmospheres by evaporated primordial ices. Ice D/H ratio model results of 0.0001 to 0.001 are compared with values for other potentially primitive material-containing bodies in the solar system, as well as with D/H ratio values from interstellar polyatomic molecules.

Sensitivity of a mesoscale model to initial specification of relative humidity, liquid water and vertical motion

NASA Technical Reports Server (NTRS)

Kalb, M. W.; Perkey, D. J.

1985-01-01

The influence of synoptic scale initial conditions on the accuracy of mesoscale precipitation modeling is investigated. Attention is focused on the relative importance of the water vapor, cloud water, rain water, and vertical motion, with the analysis carried out using the Limited Area Mesoscale Prediction System (LAMPS). The fully moist primitive equation model has 15 levels and a terrain-following sigma coordinate system. A K-theory approach was implemented to model the planetary boundary layer. A total of 15 sensitivity simulations were run to investigate the effects of the synoptic initial conditions of the four atmospheric variables. The absence of synoptic cloud and rain water amounts in the initialization caused a 2 hr delay in the onset of precipitation. The delay was increased if synoptic-scale vertical motion was used instead of mesoscale values. Both the delays and a choice of a smoothed moisture field resulted in underestimations of the total rainfall.

Fully automatic segmentation of the femur from 3D-CT images using primitive shape recognition and statistical shape models.

PubMed

Ben Younes, Lassad; Nakajima, Yoshikazu; Saito, Toki

2014-03-01

Femur segmentation is well established and widely used in computer-assisted orthopedic surgery. However, most of the robust segmentation methods such as statistical shape models (SSM) require human intervention to provide an initial position for the SSM. In this paper, we propose to overcome this problem and provide a fully automatic femur segmentation method for CT images based on primitive shape recognition and SSM. Femur segmentation in CT scans was performed using primitive shape recognition based on a robust algorithm such as the Hough transform and RANdom SAmple Consensus. The proposed method is divided into 3 steps: (1) detection of the femoral head as sphere and the femoral shaft as cylinder in the SSM and the CT images, (2) rigid registration between primitives of SSM and CT image to initialize the SSM into the CT image, and (3) fitting of the SSM to the CT image edge using an affine transformation followed by a nonlinear fitting. The automated method provided good results even with a high number of outliers. The difference of segmentation error between the proposed automatic initialization method and a manual initialization method is less than 1 mm. The proposed method detects primitive shape position to initialize the SSM into the target image. Based on primitive shapes, this method overcomes the problem of inter-patient variability. Moreover, the results demonstrate that our method of primitive shape recognition can be used for 3D SSM initialization to achieve fully automatic segmentation of the femur.

Viscous Incompressible Flow Computations for 3-D Steady and Unsteady Flows

NASA Technical Reports Server (NTRS)

Kwak, Dochan

2001-01-01

This viewgraph presentation gives an overview of viscous incompressible flow computations for three-dimensional steady and unsteady flows. Details are given on the use of computational fluid dynamics (CFD) as an engineering tool, solution methods for incompressible Navier-Stokes equations, numerical and physical characteristics of the primitive variable approach, and the role of CFD in the past and in current engineering and research applications.

Mesoscale spiral vortex embedded within a Lake Michigan snow squall band - High resolution satellite observations and numerical model simulations

NASA Technical Reports Server (NTRS)

Lyons, Walter A.; Keen, Cecil S.; Hjelmfelt, Mark; Pease, Steven R.

1988-01-01

It is known that Great Lakes snow squall convection occurs in a variety of different modes depending on various factors such as air-water temperature contrast, boundary-layer wind shear, and geostrophic wind direction. An exceptional and often neglected source of data for mesoscale cloud studies is the ultrahigh resolution multispectral data produced by Landsat satellites. On October 19, 1972, a clearly defined spiral vortex was noted in a Landsat-1 image near the southern end of Lake Michigan during an exceptionally early cold air outbreak over a still very warm lake. In a numerical simulation using a three-dimensional Eulerian hydrostatic primitive equation mesoscale model with an initially uniform wind field, a definite analog to the observed vortex was generated. This suggests that intense surface heating can be a principal cause in the development of a low-level mesoscale vortex.

An implicit solution of the three-dimensional Navier-Stokes equations for an airfoil spanning a wind tunnel. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Moitra, A.

1982-01-01

An implicit finite-difference algorithm is developed for the numerical solution of the incompressible three dimensional Navier-Stokes equations in the non-conservative primitive-variable formulation. The flow field about an airfoil spanning a wind-tunnel is computed. The coordinate system is generated by an extension of the two dimensional body-fitted coordinate generation techniques of Thompson, as well as that of Sorenson, into three dimensions. Two dimensional grids are stacked along a spanwise coordinate defined by a simple analytical function. A Poisson pressure equation for advancing the pressure in time is arrived at by performing a divergence operation on the momentum equations. The pressure at each time-step is calculated on the assumption that continuity be unconditionally satisfied. An eddy viscosity coefficient, computed according to the algebraic turbulence formulation of Baldwin and Lomax, simulates the effects of turbulence.

Differential Galois theory and non-integrability of planar polynomial vector fields

NASA Astrophysics Data System (ADS)

Acosta-Humánez, Primitivo B.; Lázaro, J. Tomás; Morales-Ruiz, Juan J.; Pantazi, Chara

2018-06-01

We study a necessary condition for the integrability of the polynomials vector fields in the plane by means of the differential Galois Theory. More concretely, by means of the variational equations around a particular solution it is obtained a necessary condition for the existence of a rational first integral. The method is systematic starting with the first order variational equation. We illustrate this result with several families of examples. A key point is to check whether a suitable primitive is elementary or not. Using a theorem by Liouville, the problem is equivalent to the existence of a rational solution of a certain first order linear equation, the Risch equation. This is a classical problem studied by Risch in 1969, and the solution is given by the "Risch algorithm". In this way we point out the connection of the non integrability with some higher transcendent functions, like the error function.

A Deformable Generic 3D Model of Haptoral Anchor of Monogenean

PubMed Central

Teo, Bee Guan; Dhillon, Sarinder Kaur; Lim, Lee Hong Susan

2013-01-01

In this paper, a digital 3D model which allows for visualisation in three dimensions and interactive manipulation is explored as a tool to help us understand the structural morphology and elucidate the functions of morphological structures of fragile microorganisms which defy live studies. We developed a deformable generic 3D model of haptoral anchor of dactylogyridean monogeneans that can subsequently be deformed into different desired anchor shapes by using direct manipulation deformation technique. We used point primitives to construct the rectangular building blocks to develop our deformable 3D model. Point primitives are manually marked on a 2D illustration of an anchor on a Cartesian graph paper and a set of Cartesian coordinates for each point primitive is manually extracted from the graph paper. A Python script is then written in Blender to construct 3D rectangular building blocks based on the Cartesian coordinates. The rectangular building blocks are stacked on top or by the side of each other following their respective Cartesian coordinates of point primitive. More point primitives are added at the sites in the 3D model where more structural variations are likely to occur, in order to generate complex anchor structures. We used Catmull-Clark subdivision surface modifier to smoothen the surface and edge of the generic 3D model to obtain a smoother and more natural 3D shape and antialiasing option to reduce the jagged edges of the 3D model. This deformable generic 3D model can be deformed into different desired 3D anchor shapes through direct manipulation deformation technique by aligning the vertices (pilot points) of the newly developed deformable generic 3D model onto the 2D illustrations of the desired shapes and moving the vertices until the desire 3D shapes are formed. In this generic 3D model all the vertices present are deployed for displacement during deformation. PMID:24204903

A deformable generic 3D model of haptoral anchor of Monogenean.

PubMed

Teo, Bee Guan; Dhillon, Sarinder Kaur; Lim, Lee Hong Susan

2013-01-01

In this paper, a digital 3D model which allows for visualisation in three dimensions and interactive manipulation is explored as a tool to help us understand the structural morphology and elucidate the functions of morphological structures of fragile microorganisms which defy live studies. We developed a deformable generic 3D model of haptoral anchor of dactylogyridean monogeneans that can subsequently be deformed into different desired anchor shapes by using direct manipulation deformation technique. We used point primitives to construct the rectangular building blocks to develop our deformable 3D model. Point primitives are manually marked on a 2D illustration of an anchor on a Cartesian graph paper and a set of Cartesian coordinates for each point primitive is manually extracted from the graph paper. A Python script is then written in Blender to construct 3D rectangular building blocks based on the Cartesian coordinates. The rectangular building blocks are stacked on top or by the side of each other following their respective Cartesian coordinates of point primitive. More point primitives are added at the sites in the 3D model where more structural variations are likely to occur, in order to generate complex anchor structures. We used Catmull-Clark subdivision surface modifier to smoothen the surface and edge of the generic 3D model to obtain a smoother and more natural 3D shape and antialiasing option to reduce the jagged edges of the 3D model. This deformable generic 3D model can be deformed into different desired 3D anchor shapes through direct manipulation deformation technique by aligning the vertices (pilot points) of the newly developed deformable generic 3D model onto the 2D illustrations of the desired shapes and moving the vertices until the desire 3D shapes are formed. In this generic 3D model all the vertices present are deployed for displacement during deformation.

Developmental Approach for Behavior Learning Using Primitive Motion Skills.

PubMed

Dawood, Farhan; Loo, Chu Kiong

2018-05-01

Imitation learning through self-exploration is essential in developing sensorimotor skills. Most developmental theories emphasize that social interactions, especially understanding of observed actions, could be first achieved through imitation, yet the discussion on the origin of primitive imitative abilities is often neglected, referring instead to the possibility of its innateness. This paper presents a developmental model of imitation learning based on the hypothesis that humanoid robot acquires imitative abilities as induced by sensorimotor associative learning through self-exploration. In designing such learning system, several key issues will be addressed: automatic segmentation of the observed actions into motion primitives using raw images acquired from the camera without requiring any kinematic model; incremental learning of spatio-temporal motion sequences to dynamically generates a topological structure in a self-stabilizing manner; organization of the learned data for easy and efficient retrieval using a dynamic associative memory; and utilizing segmented motion primitives to generate complex behavior by the combining these motion primitives. In our experiment, the self-posture is acquired through observing the image of its own body posture while performing the action in front of a mirror through body babbling. The complete architecture was evaluated by simulation and real robot experiments performed on DARwIn-OP humanoid robot.

Quantitative non-destructive testing

NASA Technical Reports Server (NTRS)

Welch, C. S.

1985-01-01

The work undertaken during this period included two primary efforts. The first is a continuation of theoretical development from the previous year of models and data analyses for NDE using the Optical Thermal Infra-Red Measurement System (OPTITHIRMS) system, which involves heat injection with a laser and observation of the resulting thermal pattern with an infrared imaging system. The second is an investigation into the use of the thermoelastic effect as an effective tool for NDE. As in the past, the effort is aimed towards NDE techniques applicable to composite materials in structural applications. The theoretical development described produced several models of temperature patterns over several geometries and material types. Agreement between model data and temperature observations was obtained. A model study with one of these models investigated some fundamental difficulties with the proposed method (the primitive equation method) for obtaining diffusivity values in plates of thickness and supplied guidelines for avoiding these difficulties. A wide range of computing speeds was found among the various models, with a one-dimensional model based on Laplace's integral solution being both very fast and very accurate.

The annual pressure cycle on Mars: Results from the LMD Martian atmospheric general circulation model

NASA Technical Reports Server (NTRS)

Hourdin, Frederic; Forget, Francois; Talagrand, O.

1993-01-01

We have been developing a General Circulation Model (GCM) of the martian atmosphere since 1989. The model has been described rather extensively elsewhere and only the main characteristics are given here. The dynamical part of the model, adapted from the LMD terrestrial climate model, is based on a finite-difference formulation of the classical 'primitive equations of meteorology.' The radiative transfer code includes absorption and emission by CO2 (carefully validated by comparison to line-by-line calculations) and dust in the thermal range and absorption and scattering by dust in the visible range. Other physical parameterizations are included: modeling of vertical turbulent mixing, dry convective adjustment (in order to prevent vertical unstable temperature profiles), and a multilayer model of the thermal conduction in the soil. Finally, the condensation-sublimation of CO2 is introduced through specification of a pressure-dependent condensation temperature. The atmospheric and surface temperatures are prevented from falling below this critical temperature by condensation and direct precipitation onto the surface of atmospheric CO2. The only prespecified spatial fields are the surface thermal inertia, albedo, and topography.

Three-dimensional time dependent computation of turbulent flow

NASA Technical Reports Server (NTRS)

Kwak, D.; Reynolds, W. C.; Ferziger, J. H.

1975-01-01

The three-dimensional, primitive equations of motion are solved numerically for the case of isotropic box turbulence and the distortion of homogeneous turbulence by irrotational plane strain at large Reynolds numbers. A Gaussian filter is applied to governing equations to define the large scale field. This gives rise to additional second order computed scale stresses (Leonard stresses). The residual stresses are simulated through an eddy viscosity. Uniform grids are used, with a fourth order differencing scheme in space and a second order Adams-Bashforth predictor for explicit time stepping. The results are compared to the experiments and statistical information extracted from the computer generated data.

A Logical Basis In The Layered Computer Vision Systems Model

NASA Astrophysics Data System (ADS)

Tejwani, Y. J.

1986-03-01

In this paper a four layer computer vision system model is described. The model uses a finite memory scratch pad. In this model planar objects are defined as predicates. Predicates are relations on a k-tuple. The k-tuple consists of primitive points and relationship between primitive points. The relationship between points can be of the direct type or the indirect type. Entities are goals which are satisfied by a set of clauses. The grammar used to construct these clauses is examined.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheviakov, Alexei F., E-mail: chevaikov@math.usask.ca

Partial differential equations of the form divN=0, N{sub t}+curl M=0 involving two vector functions in R{sup 3} depending on t, x, y, z appear in different physical contexts, including the vorticity formulation of fluid dynamics, magnetohydrodynamics (MHD) equations, and Maxwell's equations. It is shown that these equations possess an infinite family of local divergence-type conservation laws involving arbitrary functions of space and time. Moreover, it is demonstrated that the equations of interest have a rather special structure of a lower-degree (degree two) conservation law in R{sup 4}(t,x,y,z). The corresponding potential system has a clear physical meaning. For the Maxwell's equations,more » it gives rise to the scalar electric and the vector magnetic potentials; for the vorticity equations of fluid dynamics, the potentialization inverts the curl operator to yield the fluid dynamics equations in primitive variables; for MHD equations, the potential equations yield a generalization of the Galas-Bogoyavlenskij potential that describes magnetic surfaces of ideal MHD equilibria. The lower-degree conservation law is further shown to yield curl-type conservation laws and determined potential equations in certain lower-dimensional settings. Examples of new nonlocal conservation laws, including an infinite family of nonlocal material conservation laws of ideal time-dependent MHD equations in 2+1 dimensions, are presented.« less

Response of the Benguela upwelling systems to spatial variations in the wind stress

NASA Astrophysics Data System (ADS)

Fennel, Wolfgang; Junker, Tim; Schmidt, Martin; Mohrholz, Volker

2012-08-01

In this paper we combine field observations, numerical modeling and an idealized analytical theory to study some features of the Benguela upwelling system. The current system can be established through a combination of observations and realistic simulations with an advanced numerical model. The poleward undercurrent below the equator-ward coastal jet is often found as a countercurrent that reaches the sea surface seaward of the coastal jet. The coastal band of cold upwelled water appears to broaden from south to north and at the northern edge of the wind band an offshore flow is often detected, which deflects the coastal Angola current to the west. These features can be explained and understood with an idealized analytical model forced by a spatially variable wind. A crucial role is played by the wind stress curl, which shapes the oceanic response through Ekman-pumping. The interplay of the curl driven effects and the coastal Ekman upwelling together with the coastal jet, Kelvin waves, and the undercurrent is the key to understand the formation of the three-dimensional circulation patterns in the Benguela system. While the numerical model is based on the full set of primitive equations, realistic topography and forcing, the analytic model uses a linear, flat-bottomed f-plane ocean, where the coast is a straight wall and the forcing is represented by an alongshore band of dome-shaped wind stress. Although the analytical model is highly idealized it is very useful to grasp the basic mechanisms leading to the response patterns.

Interfacial characteristics of propylene carbonate and validation of simulation models for electrochemical applications

NASA Astrophysics Data System (ADS)

You, Xinli

Supercapacitors have occupy an indispensable role in today's energy storage systems due to their high power density and long life. The introduction of car- bon nanotube (CNT) forests as electrode offers the possibility of nano-scale design and high capacitance. We have performed molecular dynamics simulations on a CNT forest-based electrochemical double-layer capacitor (EDLC) and a widely used electrolyte solution (tetra-ethylammonium tetra-fluoroborate in propylene carbonate, TEABF4 /PC). We compare corresponding primitive model and atomically detailed model of TEABF4 /P, emphasizing the significance of ion clustering in electrolytes. The molecular dynamic simulation results suggests that the arrangement of closest neigh- bors leads to the formation of cation-anion chains or rings. Fuoss's discussion of ion-pairing model provides the approximation for a primitive model of 1-1 electrolyte is not broadly satisfactory for both primitive and atomically detailed cases. A more general Poisson statistical assumption is shown to be satisfactory when coordina- tion numbers are low, as is likely to be the case when ion-pairing initiates. We examined the Poisson-based model over a range of concentrations for both models of TEABF4 /P, and the atomically detailed model results identified solvent-separated nearest-neighbor ion-pairs. Large surface areas plays an essential role in nanomaterial properties, which calls for an accurate description of interfaces through modeling. We studied propylene carbonate, a widely used solvent in EDLC systems. PC wets graphite with a contact angle of 31°. The MD simulation model reproduced this contact angle after reduction 40% of the strength of graphite-C atom Lennard-Jones interactions with the solvent. The critical temperature of PC was accurately evaluated by extrapolating the PC liquid-vapor surface tensions. PC molecules tend to lie flat on the PC liquid-vapor surface, and project the propyl carbon toward the vapor phase. Liquid PC simulations also provide basic data for construction of accurate information to assist in device- level modeling of EDLCs. The most serious uncertainty with previous simulations of CNT based EDLCs was definition of the actual composition of the pores. Therefore, direct simulations of filling of CNT forest based electrochemical double-layer capacitors with TEABF4 /P solution was performed. Those calculation characterize the charging and discharg- ing process, including rates of charging responses, the possibility of bubble forma- tion, and kinetic properties with confinement. The mobilities of ions and solvent was investigated through mean square displacement (MSD) and velocity autocorrela- tion functions (VACF). The memory kernel was extracted from VACF by discretized linear-equation solving and a specialized Fourier transform method, results implies the existence of dielectric friction. With the interest in chemical features of EDLCs, a multi-scale theory was de- veloped to embed high resolution ab initio molecular dynamics (AIMD) methods into studies of EDLCs. This theory was based on McMillan-Mayer theory, potential dis- tribution approach, and quasi-chemical theory. The quasi-chemical theory allow us to break-up the free energies into packing, outer-shell and chemical contributions, where the last part can be done by AIMD directly. For the primitive model of TEABF4 /P, Gaussian statistical models are effective for these outer-shell contributions. And the Gaussian approximation is more efficient than the Bennett method in achieving an accurate mean activity coefficient.

Numerical Simulation of Bow Waves and Transom-Stern Flows

NASA Astrophysics Data System (ADS)

Dommermuth, Douglas G.; Schlageter, Eric A.; Talcott, John C.; Wyatt, Donald C.; Novikov, Evgeny A.

1997-11-01

A stratified-flow formulation is used to model the breaking bow wave and the separated transom-stern flow that are generated by a ship moving with forward speed. The interface of the air with the water is identified as the zero level-set of a three-dimensional function. The ship is modeled using a body-force technique on a cartesian grid. The three-dimensional body-force is generated using a surface panelization of the entire ship, including the above-water geometry up to and including the deck. The effects of surface tension are modeled as a source term that is concentrated at the air-water interface. The effects of gravity are modeled as a volumetric force. The three-dimensional, unsteady, Navier-Stokes equations are expressed in primitive-variable form. A LES formulation with a Smagorinsky sub-grid-scale model is used to model turbulence. Numerical convergence is demonstrated using 128x64x65, 256x128x129, and 512x256x257 grid points. The numerical results compare well to whisker-probe measurements of the free-surface elevation generated by a naval combatant.

Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

DTIC Science & Technology

2008-10-01

K. Fishman and B. M. W. Tsui, "Development of a computer-generated model for the coronary arterial tree based on multislice CT and morphometric data...mathematical models based on geometric primitives8-22. Bakic et al created synthetic x-ray mammograms using a 3D simulated breast tissue model consisting of...utilized a combination of voxel matrices and geometric primitives to create a breast phantom that includes the breast surface, the duct system, and

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobottka, Marcelo, E-mail: sobottka@mtm.ufsc.br; Hart, Andrew G., E-mail: ahart@dim.uchile.cl

Highlights: {yields} We propose a simple stochastic model to construct primitive DNA sequences. {yields} The model provide an explanation for Chargaff's second parity rule in primitive DNA sequences. {yields} The model is also used to predict a novel type of strand symmetry in primitive DNA sequences. {yields} We extend the results for bacterial DNA sequences and compare distributional properties intrinsic to the model to statistical estimates from 1049 bacterial genomes. {yields} We find out statistical evidences that the novel type of strand symmetry holds for bacterial DNA sequences. -- Abstract: Chargaff's second parity rule for short oligonucleotides states that themore » frequency of any short nucleotide sequence on a strand is approximately equal to the frequency of its reverse complement on the same strand. Recent studies have shown that, with the exception of organellar DNA, this parity rule generally holds for double-stranded DNA genomes and fails to hold for single-stranded genomes. While Chargaff's first parity rule is fully explained by the Watson-Crick pairing in the DNA double helix, a definitive explanation for the second parity rule has not yet been determined. In this work, we propose a model based on a hidden Markov process for approximating the distributional structure of primitive DNA sequences. Then, we use the model to provide another possible theoretical explanation for Chargaff's second parity rule, and to predict novel distributional aspects of bacterial DNA sequences.« less

A new potential for the numerical simulations of electrolyte solutions on a hypersphere

NASA Astrophysics Data System (ADS)

Caillol, Jean-Michel

1993-12-01

We propose a new way of performing numerical simulations of the restricted primitive model of electrolytes—and related models—on a hypersphere. In this new approach, the system is viewed as a single component fluid of charged bihard spheres constrained to move at the surface of a four dimensional sphere. A charged bihard sphere is defined as the rigid association of two antipodal charged hard spheres of opposite signs. These objects interact via a simple analytical potential obtained by solving the Poisson-Laplace equation on the hypersphere. This new technique of simulation enables a precise determination of the chemical potential of the charged species in the canonical ensemble by a straightforward application of Widom's insertion method. Comparisons with previous simulations demonstrate the efficiency and the reliability of the method.

Adaptive Osher-type scheme for the Euler equations with highly nonlinear equations of state

NASA Astrophysics Data System (ADS)

Lee, Bok Jik; Toro, Eleuterio F.; Castro, Cristóbal E.; Nikiforakis, Nikolaos

2013-08-01

For the numerical simulation of detonation of condensed phase explosives, a complex equation of state (EOS), such as the Jones-Wilkins-Lee (JWL) EOS or the Cochran-Chan (C-C) EOS, are widely used. However, when a conservative scheme is used for solving the Euler equations with such equations of state, a spurious solution across the contact discontinuity, a well known phenomenon in multi-fluid systems, arises even for single materials. In this work, we develop a generalised Osher-type scheme in an adaptive primitive-conservative framework to overcome the aforementioned difficulties. Resulting numerical solutions are compared with the exact solutions and with the numerical solutions from the Godunov method in conjunction with the exact Riemann solver for the Euler equations with Mie-Grüneisen form of equations of state, such as the JWL and the C-C equations of state. The adaptive scheme is extended to second order and its empirical convergence rates are presented, verifying second order accuracy for smooth solutions. Through a suite of several tests problems in one and two space dimensions we illustrate the failure of conservative schemes and the capability of the methods of this paper to overcome the difficulties.

Simulation of Oxygen Disintegration and Mixing With Hydrogen or Helium at Supercritical Pressure

NASA Technical Reports Server (NTRS)

Bellan, Josette; Taskinoglu, Ezgi

2012-01-01

The simulation of high-pressure turbulent flows, where the pressure, p, is larger than the critical value, p(sub c), for the species under consideration, is relevant to a wide array of propulsion systems, e.g. gas turbine, diesel, and liquid rocket engines. Most turbulence models, however, have been developed for atmospheric-p turbulent flows. The difference between atmospheric-p and supercritical-p turbulence is that, in the former situation, the coupling between dynamics and thermodynamics is moderate to negligible, but for the latter it is very significant, and can dominate the flow characteristics. The reason for this stems from the mathematical form of the equation of state (EOS), which is the perfect-gas EOS in the former case, and the real-gas EOS in the latter case. For flows at supercritical pressure, p, the large eddy simulation (LES) equations consist of the differential conservation equations coupled with a real-gas EOS. The equations use transport properties that depend on the thermodynamic variables. Compared to previous LES models, the differential equations contain not only the subgrid scale (SGS) fluxes, but also new SGS terms, each denoted as a correction. These additional terms, typically assumed null for atmospheric pressure flows, stem from filtering the differential governing equations, and represent differences between a filtered term and the same term computed as a function of the filtered flow field. In particular, the energy equation contains a heat-flux correction (q-correction) that is the difference between the filtered divergence of the heat flux and the divergence of the heat flux computed as a function of the filtered flow field. In a previous study, there was only partial success in modeling the q-correction term, but in this innovation, success has been achieved by using a different modeling approach. This analysis, based on a temporal mixing layer Direct Numerical Simulation database, shows that the focus in modeling the q-correction should be on reconstructing the primitive variable gradients rather than their coefficients, and proposes the approximate deconvolution model (ADM) as an effective means of flow field reconstruction for LES heat flux calculation. Further, results for a study conducted for temporal mixing layers initially containing oxygen in the lower stream, and hydrogen or helium in the upper stream, show that, for any LES, including SGS-flux models (constant-coefficient Gradient or Scale-Similarity models, dynamic-coefficient Smagorinsky/Yoshizawa or mixed Smagorinsky/Yoshizawa/Gradient models), the inclusion of the q-correction in the LES leads to the theoretical maximum reduction of the SGS heat-flux difference. The remaining error in modeling this new subgrid term is thus irreducible.

Postures and Motions Library Development for Verification of Ground Crew Human Systems Integration Requirements

NASA Technical Reports Server (NTRS)

Jackson, Mariea Dunn; Dischinger, Charles; Stambolian, Damon; Henderson, Gena

2012-01-01

Spacecraft and launch vehicle ground processing activities require a variety of unique human activities. These activities are being documented in a Primitive motion capture library. The Library will be used by the human factors engineering in the future to infuse real to life human activities into the CAD models to verify ground systems human factors requirements. As the Primitive models are being developed for the library the project has selected several current human factors issues to be addressed for the SLS and Orion launch systems. This paper explains how the Motion Capture of unique ground systems activities are being used to verify the human factors analysis requirements for ground system used to process the STS and Orion vehicles, and how the primitive models will be applied to future spacecraft and launch vehicle processing.

Postures and Motions Library Development for Verification of Ground Crew Human Factors Requirements

NASA Technical Reports Server (NTRS)

Stambolian, Damon; Henderson, Gena; Jackson, Mariea Dunn; Dischinger, Charles

2013-01-01

Spacecraft and launch vehicle ground processing activities require a variety of unique human activities. These activities are being documented in a primitive motion capture library. The library will be used by human factors engineering analysts to infuse real to life human activities into the CAD models to verify ground systems human factors requirements. As the primitive models are being developed for the library, the project has selected several current human factors issues to be addressed for the Space Launch System (SLS) and Orion launch systems. This paper explains how the motion capture of unique ground systems activities is being used to verify the human factors engineering requirements for ground systems used to process the SLS and Orion vehicles, and how the primitive models will be applied to future spacecraft and launch vehicle processing.

A hybrid multiview stereo algorithm for modeling urban scenes.

PubMed

Lafarge, Florent; Keriven, Renaud; Brédif, Mathieu; Vu, Hoang-Hiep

2013-01-01

We present an original multiview stereo reconstruction algorithm which allows the 3D-modeling of urban scenes as a combination of meshes and geometric primitives. The method provides a compact model while preserving details: Irregular elements such as statues and ornaments are described by meshes, whereas regular structures such as columns and walls are described by primitives (planes, spheres, cylinders, cones, and tori). We adopt a two-step strategy consisting first in segmenting the initial meshbased surface using a multilabel Markov Random Field-based model and second in sampling primitive and mesh components simultaneously on the obtained partition by a Jump-Diffusion process. The quality of a reconstruction is measured by a multi-object energy model which takes into account both photo-consistency and semantic considerations (i.e., geometry and shape layout). The segmentation and sampling steps are embedded into an iterative refinement procedure which provides an increasingly accurate hybrid representation. Experimental results on complex urban structures and large scenes are presented and compared to state-of-the-art multiview stereo meshing algorithms.

Stationary Waves of the Ice Age Climate.

NASA Astrophysics Data System (ADS)

Cook, Kerry H.; Held, Isaac M.

1988-08-01

A linearized, steady state, primitive equation model is used to simulate the climatological zonal asymmetries (stationary eddies) in the wind and temperature fields of the 18 000 YBP climate during winter. We compare these results with the eddies simulated in the ice age experiments of Broccoli and Manabe, who used CLIMAP boundary conditions and reduced atmospheric CO2 in an atmospheric general circulation model (GCM) coupled with a static mixed layer ocean model. The agreement between the models is good, indicating that the linear model can be used to evaluate the relative influences of orography, diabatic heating, and transient eddy heat and momentum transports in generating stationary waves. We find that orographic forcing dominates in the ice age climate. The mechanical influence of the continental ice sheets on the atmosphere is responsible for most of the changes between the present day and ice age stationary eddies. This concept of the ice age climate is complicated by the sensitivity of the stationary eddies to the large increase in the magnitude of the zonal mean meridional temperature gradient simulated in the ice age GCM.

An error-tuned model for sensorimotor learning

PubMed Central

Sadeghi, Mohsen; Wolpert, Daniel M.

2017-01-01

Current models of sensorimotor control posit that motor commands are generated by combining multiple modules which may consist of internal models, motor primitives or motor synergies. The mechanisms which select modules based on task requirements and modify their output during learning are therefore critical to our understanding of sensorimotor control. Here we develop a novel modular architecture for multi-dimensional tasks in which a set of fixed primitives are each able to compensate for errors in a single direction in the task space. The contribution of the primitives to the motor output is determined by both top-down contextual information and bottom-up error information. We implement this model for a task in which subjects learn to manipulate a dynamic object whose orientation can vary. In the model, visual information regarding the context (the orientation of the object) allows the appropriate primitives to be engaged. This top-down module selection is implemented by a Gaussian function tuned for the visual orientation of the object. Second, each module's contribution adapts across trials in proportion to its ability to decrease the current kinematic error. Specifically, adaptation is implemented by cosine tuning of primitives to the current direction of the error, which we show to be theoretically optimal for reducing error. This error-tuned model makes two novel predictions. First, interference should occur between alternating dynamics only when the kinematic errors associated with each oppose one another. In contrast, dynamics which lead to orthogonal errors should not interfere. Second, kinematic errors alone should be sufficient to engage the appropriate modules, even in the absence of contextual information normally provided by vision. We confirm both these predictions experimentally and show that the model can also account for data from previous experiments. Our results suggest that two interacting processes account for module selection during sensorimotor control and learning. PMID:29253869

A balanced motor primitive framework can simultaneously explain motor learning in unimanual and bimanual movements.

PubMed

Takiyama, Ken; Sakai, Yutaka

2017-02-01

Certain theoretical frameworks have successfully explained motor learning in either unimanual or bimanual movements. However, no single theoretical framework can comprehensively explain motor learning in both types of movement because the relationship between these two types of movement remains unclear. Although our recent model of a balanced motor primitive framework attempted to simultaneously explain motor learning in unimanual and bimanual movements, this model focused only on a limited subset of bimanual movements and therefore did not elucidate the relationships between unimanual movements and various bimanual movements. Here, we extend the balanced motor primitive framework to simultaneously explain motor learning in unimanual and various bimanual movements as well as the transfer of learning effects between unimanual and various bimanual movements; these phenomena can be simultaneously explained if the mean activity of each primitive for various unimanual movements is balanced with the corresponding mean activity for various bimanual movements. Using this balanced condition, we can reproduce the results of prior behavioral and neurophysiological experiments. Furthermore, we demonstrate that the balanced condition can be implemented in a simple neural network model. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

How rare is complex life in the Milky Way?

PubMed

Bounama, Christine; von Bloh, Werner; Franck, Siegfried

2007-10-01

An integrated Earth system model was applied to calculate the number of habitable Earth-analog planets that are likely to have developed primitive (unicellular) and complex (multicellular) life in extrasolar planetary systems. The model is based on the global carbon cycle mediated by life and driven by increasing stellar luminosity and plate tectonics. We assumed that the hypothetical primitive and complex life forms differed in their temperature limits and CO(2) tolerances. Though complex life would be more vulnerable to environmental stress, its presence would amplify weathering processes on a terrestrial planet. The model allowed us to calculate the average number of Earth-analog planets that may harbor such life by using the formation rate of Earth-like planets in the Milky Way as well as the size of a habitable zone that could support primitive and complex life forms. The number of planets predicted to bear complex life was found to be approximately 2 orders of magnitude lower than the number predicted for primitive life forms. Our model predicted a maximum abundance of such planets around 1.8 Ga ago and allowed us to calculate the average distance between potentially habitable planets in the Milky Way. If the model predictions are accurate, the future missions DARWIN (up to a probability of 65%) and TPF (up to 20%) are likely to detect at least one planet with a biosphere composed of complex life.

Some lessons and thoughts from development of an old-fashioned high-resolution atmospheric general circulation model

NASA Astrophysics Data System (ADS)

Ohfuchi, Wataru; Enomoto, Takeshi; Yoshioka, Mayumi K.; Takaya, Koutarou

2014-05-01

Some high-resolution simulations with a conventional atmospheric general circulation model (AGCM) were conducted right after the first Earth Simulator started operating in the spring of 2002. More simulations with various resolutions followed. The AGCM in this study, AFES (Agcm For the Earth Simulator), is a primitive equation spectral transform method model with a cumulus convection parameterization. In this presentation, some findings from comparisons between high and low-resolution simulations, and some future perspectives of old-fashioned AGCMs will be discussed. One obvious advantage of increasing resolution is capability of resolving the fine structures of topography and atmospheric flow. By increasing resolution from T39 (about 320 km horizontal grid interval) to T79 (160 km), to T159 (80 km) to T319 (40 km), topographic precipitation over Japan becomes increasingly realistic. This feature is necessary for climate and weather studies involving both global and local aspects. In order to resolve submesoscale (about 100 km horizontal scale) atmospheric circulation, about 10-km grid interval is necessary. Comparing T1279 (10 km) simulations with T319 ones, it is found that, for example, the intensity of heavy rain associated with Baiu front and the central pressure of typhoon become more realistic. These realistic submesoscale phenomena should have impact on larger-sale flow through dynamics and thermodynamics. An interesting finding by increasing horizontal resolution of a conventional AGCM is that some cumulus convection parameterizations, such as Arakawa-Schubert type scheme, gradually stop producing precipitation, while some others, such as Emanuel type, do not. With the former, the grid condensation increases with the model resolution to compensate. Which characteristics are more desirable is arguable but it is an important feature one has to consider when developing a high-resolution conventional AGCM. Many may think that conventional primitive equation spectral transform AGCMs, such as AFES, have no future. Developing globally homogeneous nonhydrostatic cloud resolving grid AGCMs is obviously a straightforward direction for the future. However these models will be very expensive for many users for a while, perhaps for the next some decades. On the other hand, old-fashioned AGCMs with a grid interval of 20-100 km will remain to be accurate and efficient tools for many users for many years to come. Also by coupling with a fine-resolution regional nonhydrostatic model, a conventional AGCM may overcome its limitation for use in climate and weather studies in the future.

Implicit preconditioned WENO scheme for steady viscous flow computation

NASA Astrophysics Data System (ADS)

Huang, Juan-Chen; Lin, Herng; Yang, Jaw-Yen

2009-02-01

A class of lower-upper symmetric Gauss-Seidel implicit weighted essentially nonoscillatory (WENO) schemes is developed for solving the preconditioned Navier-Stokes equations of primitive variables with Spalart-Allmaras one-equation turbulence model. The numerical flux of the present preconditioned WENO schemes consists of a first-order part and high-order part. For first-order part, we adopt the preconditioned Roe scheme and for the high-order part, we employ preconditioned WENO methods. For comparison purpose, a preconditioned TVD scheme is also given and tested. A time-derivative preconditioning algorithm is devised and a discriminant is devised for adjusting the preconditioning parameters at low Mach numbers and turning off the preconditioning at intermediate or high Mach numbers. The computations are performed for the two-dimensional lid driven cavity flow, low subsonic viscous flow over S809 airfoil, three-dimensional low speed viscous flow over 6:1 prolate spheroid, transonic flow over ONERA-M6 wing and hypersonic flow over HB-2 model. The solutions of the present algorithms are in good agreement with the experimental data. The application of the preconditioned WENO schemes to viscous flows at all speeds not only enhances the accuracy and robustness of resolving shock and discontinuities for supersonic flows, but also improves the accuracy of low Mach number flow with complicated smooth solution structures.

Initial Investigation on the Aerodynamic Performance of Flapping Wings for Nano Air Vehicles

DTIC Science & Technology

2008-02-01

Experiments with Primitive Equations”, Monthly Weather Review, 93:99-164, 1963. 36. Yuan, W., Schilling, R., “Numerical Simulation of the Draft Tube and...LE and TE wake vorticity – Fully flexible wake – Linear approximation of Kutta condition yields a linear system of equations at each time step...all cases one must consider the drain rate. High drain rates substantially diminish capacity! Some batteries simply not capable of delivering

A model for the enantiomeric enrichment of polypeptides on the primitive earth

NASA Technical Reports Server (NTRS)

Blair, N. E.; Bonner, W. A.

1981-01-01

A potential model is presented for the origin of optical activity in polypeptides on the primitive earth due to enantiomeric enrichment in succeeding polymerization-hydrolysis cycles. The model was developed in experiments with the polymerization of a DL-leucine N-carboxyanhydride mixture with a 31.2% enantiomeric excess of the L isomer with sodium methoxide initiator to yield a polyleucine product which was in turn partially hydrolyzed by acid. The polymerization-hydrolysis was found to produce a net 23.8% increase in the enantiomeric excess of the remaining unhydrolyzed polypeptide (14.2% from the polymerization and 9.6% from the partial hydrolysis). On the basis of these results, it is suggested that a slight excess produced by an appropriate chiral physical process may be enhanced by cycles of stereoselective polymerization and hydrolysis driven by fluctuating wet and dry environmental cycles on the primitive earth.

Impact of Discrete Corrections in a Modular Approach for Trajectory Generation in Quadruped Robots

NASA Astrophysics Data System (ADS)

Pinto, Carla M. A.; Santos, Cristina P.; Rocha, Diana; Matos, Vítor

2011-09-01

Online generation of trajectories in robots is a very complex task that involves the combination of different types of movements, i.e., distinct motor primitives. The later are used to model complex behaviors in robots, such as locomotion in irregular terrain and obstacle avoidance. In this paper, we consider two motor primitives: rhythmic and discrete. We study the effect on the robots' gaits of superimposing the two motor primitives, considering two distinct types of coupling. Additionally, we simulate two scenarios, where the discrete primitive is inserted in all of the four limbs, or is inserted in ipsilateral pairs of limbs. Numerical results show that amplitude and frequency of the periodic solutions, corresponding to the gaits trot and pace, are almost constant for diffusive and synaptic couplings.

Development of a fractional-step method for the unsteady incompressible Navier-Stokes equations in generalized coordinate systems

NASA Technical Reports Server (NTRS)

Rosenfeld, Moshe; Kwak, Dochan; Vinokur, Marcel

1992-01-01

A fractional step method is developed for solving the time-dependent three-dimensional incompressible Navier-Stokes equations in generalized coordinate systems. The primitive variable formulation uses the pressure, defined at the center of the computational cell, and the volume fluxes across the faces of the cells as the dependent variables, instead of the Cartesian components of the velocity. This choice is equivalent to using the contravariant velocity components in a staggered grid multiplied by the volume of the computational cell. The governing equations are discretized by finite volumes using a staggered mesh system. The solution of the continuity equation is decoupled from the momentum equations by a fractional step method which enforces mass conservation by solving a Poisson equation. This procedure, combined with the consistent approximations of the geometric quantities, is done to satisfy the discretized mass conservation equation to machine accuracy, as well as to gain the favorable convergence properties of the Poisson solver. The momentum equations are solved by an approximate factorization method, and a novel ZEBRA scheme with four-color ordering is devised for the efficient solution of the Poisson equation. Several two- and three-dimensional laminar test cases are computed and compared with other numerical and experimental results to validate the solution method. Good agreement is obtained in all cases.

FoSSI: the family of simplified solver interfaces for the rapid development of parallel numerical atmosphere and ocean models

NASA Astrophysics Data System (ADS)

Frickenhaus, Stephan; Hiller, Wolfgang; Best, Meike

The portable software FoSSI is introduced that—in combination with additional free solver software packages—allows for an efficient and scalable parallel solution of large sparse linear equations systems arising in finite element model codes. FoSSI is intended to support rapid model code development, completely hiding the complexity of the underlying solver packages. In particular, the model developer need not be an expert in parallelization and is yet free to switch between different solver packages by simple modifications of the interface call. FoSSI offers an efficient and easy, yet flexible interface to several parallel solvers, most of them available on the web, such as PETSC, AZTEC, MUMPS, PILUT and HYPRE. FoSSI makes use of the concept of handles for vectors, matrices, preconditioners and solvers, that is frequently used in solver libraries. Hence, FoSSI allows for a flexible treatment of several linear equations systems and associated preconditioners at the same time, even in parallel on separate MPI-communicators. The second special feature in FoSSI is the task specifier, being a combination of keywords, each configuring a certain phase in the solver setup. This enables the user to control a solver over one unique subroutine. Furthermore, FoSSI has rather similar features for all solvers, making a fast solver intercomparison or exchange an easy task. FoSSI is a community software, proven in an adaptive 2D-atmosphere model and a 3D-primitive equation ocean model, both formulated in finite elements. The present paper discusses perspectives of an OpenMP-implementation of parallel iterative solvers based on domain decomposition methods. This approach to OpenMP solvers is rather attractive, as the code for domain-local operations of factorization, preconditioning and matrix-vector product can be readily taken from a sequential implementation that is also suitable to be used in an MPI-variant. Code development in this direction is in an advanced state under the name ScOPES: the Scalable Open Parallel sparse linear Equations Solver.

Agradient velocity, vortical motion and gravity waves in a rotating shallow-water model

NASA Astrophysics Data System (ADS)

Sutyrin Georgi, G.

2004-07-01

A new approach to modelling slow vortical motion and fast inertia-gravity waves is suggested within the rotating shallow-water primitive equations with arbitrary topography. The velocity is exactly expressed as a sum of the gradient wind, described by the Bernoulli function,B, and the remaining agradient part, proportional to the velocity tendency. Then the equation for inverse potential vorticity,Q, as well as momentum equations for agradient velocity include the same source of intrinsic flow evolution expressed as a single term J (B, Q), where J is the Jacobian operator (for any steady state J (B, Q) = 0). Two components of agradient velocity are responsible for the fast inertia-gravity wave propagation similar to the traditionally used divergence and ageostrophic vorticity. This approach allows for the construction of balance relations for vortical dynamics and potential vorticity inversion schemes even for moderate Rossby and Froude numbers assuming the characteristic value of |J(B, Q)| = to be small. The components of agradient velocity are used as the fast variables slaved to potential vorticity that allows for diagnostic estimates of the velocity tendency, the direct potential vorticity inversion with the accuracy of 2 and the corresponding potential vorticity-conserving agradient velocity balance model (AVBM). The ultimate limitations of constructing the balance are revealed in the form of the ellipticity condition for balanced tendency of the Bernoulli function which incorporates both known criteria of the formal stability: the gradient wind modified by the characteristic vortical Rossby wave phase speed should be subcritical. The accuracy of the AVBM is illustrated by considering the linear normal modes and coastal Kelvin waves in the f-plane channel with topography.

Climatic impact of Amazon deforestation - a mechanistic model study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ning Zeng; Dickinson, R.E.; Xubin Zeng

1996-04-01

Recent general circulation model (GCM) experiments suggest a drastic change in the regional climate, especially the hydrological cycle, after hypothesized Amazon basinwide deforestation. To facilitate the theoretical understanding os such a change, we develop an intermediate-level model for tropical climatology, including atmosphere-land-ocean interaction. The model consists of linearized steady-state primitive equations with simplified thermodynamics. A simple hydrological cycle is also included. Special attention has been paid to land-surface processes. It generally better simulates tropical climatology and the ENSO anomaly than do many of the previous simple models. The climatic impact of Amazon deforestation is studied in the context of thismore » model. Model results show a much weakened Atlantic Walker-Hadley circulation as a result of the existence of a strong positive feedback loop in the atmospheric circulation system and the hydrological cycle. The regional climate is highly sensitive to albedo change and sensitive to evapotranspiration change. The pure dynamical effect of surface roughness length on convergence is small, but the surface flow anomaly displays intriguing features. Analysis of the thermodynamic equation reveals that the balance between convective heating, adiabatic cooling, and radiation largely determines the deforestation response. Studies of the consequences of hypothetical continuous deforestation suggest that the replacement of forest by desert may be able to sustain a dry climate. Scaling analysis motivated by our modeling efforts also helps to interpret the common results of many GCM simulations. When a simple mixed-layer ocean model is coupled with the atmospheric model, the results suggest a 1{degrees}C decrease in SST gradient across the equatorial Atlantic Ocean in response to Amazon deforestation. The magnitude depends on the coupling strength. 66 refs., 16 figs., 4 tabs.« less

Design of Quasi-Terminator Orbits near Primitive Bodies

NASA Technical Reports Server (NTRS)

Lantoine, Gregory; Broschart, Stephen B.; Grebow, Daniel J.

2013-01-01

Quasi-terminator orbits are a class of quasi-periodic orbits around a primitive body that exist in the vicinity of the well-known terminator orbits. The inherent stability of quasi-terminator trajectories and their wide variety of viewing geometries make them a very compelling option for primitive body mapping missions. In this paper, we discuss orbit design methodologies for selection of an appropriate quasi-terminator orbit that would meet the needs of a specific mission. Convergence of these orbits in an eccentric, higher-fidelity model is also discussed with an example case at Bennu, the target of the upcoming NASA's OSIRIS-REx mission.

KSOS Computer Program Development Specifications (Type B-5). (Kernelized Secure Operating System). I. Security Kernel (CDRL 0002AF). II. UNIX Emulator (CDRL 0002AG). III. Security-Related Software (CDRL 0002AH).

DTIC Science & Technology

1980-12-01

Commun- ications Corporation, Palo Alto, CA (March 1978). g. [Walter at al. 74] Walter, K.G. et al., " Primitive Models for Computer .. Security", ESD-TR...discussion is followed by a presenta- tion of the Kernel primitive operations upon these objects. All Kernel objects shall be referenced by a common...set of sizes. All process segments, regardless of domain, shall be manipulated by the same set of Kernel segment primitives . User domain segments

Numerical simulations of a transverse indirect circulation and low-level jet in the exit region of an upper-level jet

NASA Technical Reports Server (NTRS)

Brill, K. F.; Uccellini, L. W.; Burkhart, R. P.; Warner, T. T.; Anthes, R. A.

1985-01-01

A numerical study was performed of a severe weather event (tornado) which occurred on May 10, 1973 in the Ohio region. The situation was modeled with a primitive equation mesoscale dynamic formulation. Account was taken of precipitation, the planetary boundary layer parameters as bulk quantities, the vertical pressure gradient, and lateral boundary conditions based on radiosonde data. Two 12-hr simulations, adiabatic and nondivergent, respectively, were analyzed for relationships between upper and lower level jets. In the adiabatic formulation, a transverse circulation with a low level jet formed at the exit region of the upper level jet. The nondivergent situation led to similar, but weaker, phenomena. Both forms suggest that indirect circulation in the exit zone of an upper level jet is strongly influenced by the initial structure of the jet.

The rotation of the Uranian system

NASA Technical Reports Server (NTRS)

Podolak, M.

1984-01-01

The rotation of Uranus is examined for clues as to the origin of the Solar System. Both theories based on the formation of planets through the accretion of small planetesimals, and theories based on the formation of giant gaseous protoplanets through a gravitational instability in the primitive solar nebula allow for qualitative explanations of the large tilt of Uranus's equator to the orbital plane, and the fact that its satellites lie in the equatorial plane. Models of the planetary interior show that the mass ratio of ice-forming materials to rock in Uranus's interior must be more than about three if the rotation period is about 16 h. Such a large ratio seems to exclude those accretional theories that require most of the nebular gas to be heated to relatively high temperatures before being accreted into the planet.

Zonally averaged model of dynamics, chemistry and radiation for the atmosphere

NASA Technical Reports Server (NTRS)

Tung, K. K.

1985-01-01

A nongeostrophic theory of zonally averaged circulation is formulated using the nonlinear primitive equations on a sphere, taking advantage of the more direct relationship between the mean meridional circulation and diabatic heating rate which is available in isentropic coordinates. Possible differences between results of nongeostrophic theory and the commonly used geostrophic formulation are discussed concerning: (1) the role of eddy forcing of the diabatic circulation, and (2) the nonlinear nearly inviscid limit vs the geostrophic limit. Problems associated with the traditional Rossby number scaling in quasi-geostrophic formulations are pointed out and an alternate, more general scaling based on the smallness of mean meridional to zonal velocities for a rotating planet is suggested. Such a scaling recovers the geostrophic balanced wind relationship for the mean zonal flow but reveals that the mean meridional velocity is in general ageostrophic.

Mathematical aspects of finite element methods for incompressible viscous flows

NASA Technical Reports Server (NTRS)

Gunzburger, M. D.

1986-01-01

Mathematical aspects of finite element methods are surveyed for incompressible viscous flows, concentrating on the steady primitive variable formulation. The discretization of a weak formulation of the Navier-Stokes equations are addressed, then the stability condition is considered, the satisfaction of which insures the stability of the approximation. Specific choices of finite element spaces for the velocity and pressure are then discussed. Finally, the connection between different weak formulations and a variety of boundary conditions is explored.

Studies of Stirring and Mixing at the Submesoscale in the Ocean: FY2013 Annual Report

DTIC Science & Technology

2013-09-30

uhler, and R. Ferrari. Particle dispersion by random waves in the rotating Boussinesq system . J. Fluid Mech., 670:150-175, 2011. Ferrari, R.. A...We have now run a suite of QG simulations in parallel with Boussinesq Primitive Equation (PE) simulations (using the Diablo code), systematicaly...density fronts. J. Phys. Oceanogr., 40:1222-1242, 2010. Taylor, J., K. S. Smith and R. Ferrari. Submesoscale stirring of tracers in Boussinesq and quasi

Number Theoretic Background

NASA Astrophysics Data System (ADS)

Rudnick, Z.

Contents: 1. Introduction 2. Divisibility 2.1. Basics on Divisibility 2.2. The Greatest Common Divisor 2.3. The Euclidean Algorithm 2.4. The Diophantine Equation ax+by=c 3. Prime Numbers 3.1. The Fundamental Theorem of Arithmetic 3.2. There Are Infinitely Many Primes 3.3. The Density of Primes 3.4. Primes in Arithmetic Progressions 4. Continued Fractions 5. Modular Arithmetic 5.1. Congruences 5.2. Modular Inverses 5.3. The Chinese Remainder Theorem 5.4. The Structure of the Multiplicative Group (Z/NZ)^* 5.5. Primitive Roots 6. Quadratic Congruences 6.1. Euler's Criterion 6.2. The Legendre Symbol and Quadratic Reciprocity 7. Pell's Equation 7.1. The Group Law 7.2. Integer Solutions 7.3. Finding the Fundamental Solution 8. The Riemann Zeta Function 8.1 Analytic Continuation and Functinal Equation of ζ(s) 8.2 Connecting the Primes and the Zeros of ζ(s) 8.3 The Riemann Hypothesis References

A finite element solution algorithm for the Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Baker, A. J.

1974-01-01

A finite element solution algorithm is established for the two-dimensional Navier-Stokes equations governing the steady-state kinematics and thermodynamics of a variable viscosity, compressible multiple-species fluid. For an incompressible fluid, the motion may be transient as well. The primitive dependent variables are replaced by a vorticity-streamfunction description valid in domains spanned by rectangular, cylindrical and spherical coordinate systems. Use of derived variables provides a uniformly elliptic partial differential equation description for the Navier-Stokes system, and for which the finite element algorithm is established. Explicit non-linearity is accepted by the theory, since no psuedo-variational principles are employed, and there is no requirement for either computational mesh or solution domain closure regularity. Boundary condition constraints on the normal flux and tangential distribution of all computational variables, as well as velocity, are routinely piecewise enforceable on domain closure segments arbitrarily oriented with respect to a global reference frame.

Melting of the primitive martian mantle at 0.5-2.2 GPa and the origin of basalts and alkaline rocks on Mars

NASA Astrophysics Data System (ADS)

Collinet, Max; Médard, Etienne; Charlier, Bernard; Vander Auwera, Jacqueline; Grove, Timothy L.

2015-10-01

We have performed piston-cylinder experiments on a primitive martian mantle composition between 0.5 and 2.2 GPa and 1160 to 1550 °C. The composition of melts and residual minerals constrain the possible melting processes on Mars at 50 to 200 km depth under nominally anhydrous conditions. Silicate melts produced by low degrees of melting (<10 wt.%) were analyzed in layers of vitreous carbon spheres or in micro-cracks inside the graphite capsule. The total range of melt fractions investigated extends from 5 to 50 wt.%, and the liquids produced display variable SiO2 (43.7-59.0 wt.%), MgO (5.3-18.6 wt.%) and Na2O + K2O (1.0-6.5 wt.%) contents. We provide a new equation to estimate the solidus temperature of the martian mantle: T (°C) = 1033 + 168.1 P (GPa) - 14.22P2 (GPa), which places the solidus 50 °C below that of fertile terrestrial peridotites. Low- and high-degree melts are compared to martian alkaline rocks and basalts, respectively. We suggest that the parental melt of Adirondack-class basalts was produced by ∼25 wt.% melting of the primitive martian mantle at 1.5 GPa (∼135 km) and ∼1400 °C. Despite its brecciated nature, NWA 7034/7533 might be composed of material that initially crystallized from a primary melt produced by ∼10-30 wt.% melting at the same pressure. Other igneous rocks from Mars require mantle reservoirs with different CaO/Al2O3 and FeO/MgO ratios or the action of fractional crystallization. Alkaline rocks can be derived from mantle sources with alkali contents (∼0.5 wt.%) similar to the primitive mantle.

An implicit numerical scheme for the simulation of internal viscous flows on unstructured grids

NASA Technical Reports Server (NTRS)

Jorgenson, Philip C. E.; Pletcher, Richard H.

1994-01-01

The Navier-Stokes equations are solved numerically for two-dimensional steady viscous laminar flows. The grids are generated based on the method of Delaunay triangulation. A finite-volume approach is used to discretize the conservation law form of the compressible flow equations written in terms of primitive variables. A preconditioning matrix is added to the equations so that low Mach number flows can be solved economically. The equations are time marched using either an implicit Gauss-Seidel iterative procedure or a solver based on a conjugate gradient like method. A four color scheme is employed to vectorize the block Gauss-Seidel relaxation procedure. This increases the memory requirements minimally and decreases the computer time spent solving the resulting system of equations substantially. A factor of 7.6 speed up in the matrix solver is typical for the viscous equations. Numerical results are obtained for inviscid flow over a bump in a channel at subsonic and transonic conditions for validation with structured solvers. Viscous results are computed for developing flow in a channel, a symmetric sudden expansion, periodic tandem cylinders in a cross-flow, and a four-port valve. Comparisons are made with available results obtained by other investigators.

Tangent linear super-parameterization: attributable, decomposable moist processes for tropical variability studies

NASA Astrophysics Data System (ADS)

Mapes, B. E.; Kelly, P.; Song, S.; Hu, I. K.; Kuang, Z.

2015-12-01

An economical 10-layer global primitive equation solver is driven by time-independent forcing terms, derived from a training process, to produce a realisting eddying basic state with a tracer q trained to act like water vapor mixing ratio. Within this basic state, linearized anomaly moist physics in the column are applied in the form of a 20x20 matrix. The control matrix was derived from the results of Kuang (2010, 2012) who fitted a linear response function from a cloud resolving model in a state of deep convecting equilibrium. By editing this matrix in physical space and eigenspace, scaling and clipping its action, and optionally adding terms for processes that do not conserve moist statice energy (radiation, surface fluxes), we can decompose and explain the model's diverse moist process coupled variability. Recitified effects of this variability on the general circulation and climate, even in strictly zero-mean centered anomaly physic cases, also are sometimes surprising.

A defect stream function, law of the wall/wake method for compressible turbulent boundary layers

NASA Technical Reports Server (NTRS)

Barnwell, Richard W.; Dejarnette, Fred R.; Wahls, Richard A.

1989-01-01

The application of the defect stream function to the solution of the two-dimensional, compressible boundary layer is examined. A law of the wall/law of the wake formulation for the inner part of the boundary layer is presented which greatly simplifies the computational task near the wall and eliminates the need for an eddy viscosity model in this region. The eddy viscosity model in the outer region is arbitrary. The modified Crocco temperature-velocity relationship is used as a simplification of the differential energy equation. Formulations for both equilibrium and nonequilibrium boundary layers are presented including a constrained zero-order form which significantly reduces the computational workload while retaining the significant physics of the flow. A formulation for primitive variables is also presented. Results are given for the constrained zero-order and second-order equilibrium formulations and are compared with experimental data. A compressible wake function valid near the wall has been developed from the present results.

MACOP modular architecture with control primitives

PubMed Central

Waegeman, Tim; Hermans, Michiel; Schrauwen, Benjamin

2013-01-01

Walking, catching a ball and reaching are all tasks in which humans and animals exhibit advanced motor skills. Findings in biological research concerning motor control suggest a modular control hierarchy which combines movement/motor primitives into complex and natural movements. Engineers inspire their research on these findings in the quest for adaptive and skillful control for robots. In this work we propose a modular architecture with control primitives (MACOP) which uses a set of controllers, where each controller becomes specialized in a subregion of its joint and task-space. Instead of having a single controller being used in this subregion [such as MOSAIC (modular selection and identification for control) on which MACOP is inspired], MACOP relates more to the idea of continuously mixing a limited set of primitive controllers. By enforcing a set of desired properties on the mixing mechanism, a mixture of primitives emerges unsupervised which successfully solves the control task. We evaluate MACOP on a numerical model of a robot arm by training it to generate desired trajectories. We investigate how the tracking performance is affected by the number of controllers in MACOP and examine how the individual controllers and their generated control primitives contribute to solving the task. Furthermore, we show how MACOP compensates for the dynamic effects caused by a fixed control rate and the inertia of the robot. PMID:23888140

Search for Primitive Matter in the Solar System

NASA Technical Reports Server (NTRS)

Libourel, G.; Michel, P.; Delbo, M.; Ganino, C.; Recio-Blanco, A.; de Laverny, P.; Zolensky, M. E.; Krot, A. N.

2017-01-01

Recent astronomical observations and theoretical modeling led to a consensus regarding the global scenario of the formation of young stellar objects (YSO) from a cold molecular cloud of interstellar dust (organics and minerals) and gas that, in some cases, leads to the formation of a planetary system. In the case of our Solar System, which has already evolved for approximately 4567 Ma, the quest is to access, through the investigation of planets, moons, cometary and asteroidal bodies, meteorites, micrometeorites, and interplanetary dust particles, the primitive material that contains the key information about the early Solar System processes and its evolution. However, laboratory analyses of extraterrestrial samples, astronomical observations and dynamical models of the Solar System evolution have not brought yet any conclusive evidence on the nature and location of primitive matter in the Solar System, preventing a clear understanding of its early stages.

Primitive erythropoiesis is regulated by miR-126 via nonhematopoietic Vcam-1+ cells.

PubMed

Sturgeon, Christopher M; Chicha, Laurie; Ditadi, Andrea; Zhou, Qinbo; McGrath, Kathleen E; Palis, James; Hammond, Scott M; Wang, Shusheng; Olson, Eric N; Keller, Gordon

2012-07-17

Primitive erythropoiesis defines the onset of hematopoiesis in the yolk sac of the early embryo and is initiated by the emergence of progenitors assayed as colony-forming cells (EryP-CFCs). EryP-CFCs are detected for only a narrow window during embryonic development, suggesting that both their initiation and termination are tightly controlled. Using the embryonic stem differentiation system to model primitive erythropoiesis, we found that miR-126 regulates the termination of EryP-CFC development. Analyses of miR-126 null embryos revealed that this miR also regulates EryP-CFCs in vivo. We identified vascular cell adhesion molecule-1 (Vcam-1) expressed by a mesenchymal cell population as a relevant target of miR-126. Interaction of EryP-CFCs with Vcam-1 accelerated their maturation to ßh1-globin(+) and Ter119(+) cells through a Src family kinase. These findings uncover a cell nonautonomous regulatory pathway for primitive erythropoiesis that may provide insight into the mechanism(s) controlling the developmental switch from primitive to definitive hematopoiesis. Copyright © 2012 Elsevier Inc. All rights reserved.

An approximate Kalman filter for ocean data assimilation: An example with an idealized Gulf Stream model

NASA Technical Reports Server (NTRS)

Fukumori, Ichiro; Malanotte-Rizzoli, Paola

1995-01-01

A practical method of data assimilation for use with large, nonlinear, ocean general circulation models is explored. A Kalman filter based on approximation of the state error covariance matrix is presented, employing a reduction of the effective model dimension, the error's asymptotic steady state limit, and a time-invariant linearization of the dynamic model for the error integration. The approximations lead to dramatic computational savings in applying estimation theory to large complex systems. We examine the utility of the approximate filter in assimilating different measurement types using a twin experiment of an idealized Gulf Stream. A nonlinear primitive equation model of an unstable east-west jet is studied with a state dimension exceeding 170,000 elements. Assimilation of various pseudomeasurements are examined, including velocity, density, and volume transport at localized arrays and realistic distributions of satellite altimetry and acoustic tomography observations. Results are compared in terms of their effects on the accuracies of the estimation. The approximate filter is shown to outperform an empirical nudging scheme used in a previous study. The examples demonstrate that useful approximate estimation errors can be computed in a practical manner for general circulation models.

Exact Solutions for Wind-Driven Coastal Upwelling and Downwelling over Sloping Topography

NASA Astrophysics Data System (ADS)

Choboter, P.; Duke, D.; Horton, J.; Sinz, P.

2009-12-01

The dynamics of wind-driven coastal upwelling and downwelling are studied using a simplified dynamical model. Exact solutions are examined as a function of time and over a family of sloping topographies. Assumptions in the two-dimensional model include a frictionless ocean interior below the surface Ekman layer, and no alongshore dependence of the variables; however, dependence in the cross-shore and vertical directions is retained. Additionally, density and alongshore momentum are advected by the cross-shore velocity in order to maintain thermal wind. The time-dependent initial-value problem is solved with constant initial stratification and no initial alongshore flow. An alongshore pressure gradient is added to allow the cross-shore flow to be geostrophically balanced far from shore. Previously, this model has been used to study upwelling over flat-bottom and sloping topographies, but the novel feature in this work is the discovery of exact solutions for downwelling. These exact solutions are compared to numerical solutions from a primitive-equation ocean model, based on the Princeton Ocean Model, configured in a similar two-dimensional geometry. Many typical features of the evolution of density and velocity during downwelling are displayed by the analytical model.

Modeling of Dense Water Production and Salt Transport from Alaskan Coastal Polynyas

NASA Technical Reports Server (NTRS)

Signorini, Sergio R.; Cavalieri, Donald J.

2000-01-01

The main significance of this paper is that a realistic, three-dimensional, high-resolution primitive equation model has been developed to study the effects of dense water formation in Arctic coastal polynyas. The model includes realistic ambient stratification, realistic bottom topography, and is forced by time-variant surface heat flux, surface salt flux, and time-dependent coastal flow. The salt and heat fluxes, and the surface ice drift, are derived from satellite observations (SSM/I and NSCAT sensors). The model is used to study the stratification, salt transport, and circulation in the vicinity of Barrow Canyon during the 1996/97 winter season. The coastal flow (Alaska coastal current), which is an extension of the Bering Sea throughflow, is formulated in the model using the wind-transport regression. The results show that for the 1996/97 winter the northeastward coastal current exports 13% to 26% of the salt produced by coastal polynyas upstream of Barrow Canyon in 20 to 30 days. The salt export occurs more rapidly during less persistent polynyas. The inclusion of ice-water stress in the model makes the coastal current slightly weaker and much wider due to the combined effects of surface drag and offshore Ekman transport.

An approximate Kalman filter for ocean data assimilation: An example with an idealized Gulf Stream model

NASA Astrophysics Data System (ADS)

Fukumori, Ichiro; Malanotte-Rizzoli, Paola

1995-04-01

A practical method of data assimilation for use with large, nonlinear, ocean general circulation models is explored. A Kaiman filter based on approximations of the state error covariance matrix is presented, employing a reduction of the effective model dimension, the error's asymptotic steady state limit, and a time-invariant linearization of the dynamic model for the error integration. The approximations lead to dramatic computational savings in applying estimation theory to large complex systems. We examine the utility of the approximate filter in assimilating different measurement types using a twin experiment of an idealized Gulf Stream. A nonlinear primitive equation model of an unstable east-west jet is studied with a state dimension exceeding 170,000 elements. Assimilation of various pseudomeasurements are examined, including velocity, density, and volume transport at localized arrays and realistic distributions of satellite altimetry and acoustic tomography observations. Results are compared in terms of their effects on the accuracies of the estimation. The approximate filter is shown to outperform an empirical nudging scheme used in a previous study. The examples demonstrate that useful approximate estimation errors can be computed in a practical manner for general circulation models.

Sensory processing and world modeling for an active ranging device

NASA Technical Reports Server (NTRS)

Hong, Tsai-Hong; Wu, Angela Y.

1991-01-01

In this project, we studied world modeling and sensory processing for laser range data. World Model data representation and operation were defined. Sensory processing algorithms for point processing and linear feature detection were designed and implemented. The interface between world modeling and sensory processing in the Servo and Primitive levels was investigated and implemented. In the primitive level, linear features detectors for edges were also implemented, analyzed and compared. The existing world model representations is surveyed. Also presented is the design and implementation of the Y-frame model, a hierarchical world model. The interfaces between the world model module and the sensory processing module are discussed as well as the linear feature detectors that were designed and implemented.

Hierarchical HMM based learning of navigation primitives for cooperative robotic endovascular catheterization.

PubMed

Rafii-Tari, Hedyeh; Liu, Jindong; Payne, Christopher J; Bicknell, Colin; Yang, Guang-Zhong

2014-01-01

Despite increased use of remote-controlled steerable catheter navigation systems for endovascular intervention, most current designs are based on master configurations which tend to alter natural operator tool interactions. This introduces problems to both ergonomics and shared human-robot control. This paper proposes a novel cooperative robotic catheterization system based on learning-from-demonstration. By encoding the higher-level structure of a catheterization task as a sequence of primitive motions, we demonstrate how to achieve prospective learning for complex tasks whilst incorporating subject-specific variations. A hierarchical Hidden Markov Model is used to model each movement primitive as well as their sequential relationship. This model is applied to generation of motion sequences, recognition of operator input, and prediction of future movements for the robot. The framework is validated by comparing catheter tip motions against the manual approach, showing significant improvements in the quality of catheterization. The results motivate the design of collaborative robotic systems that are intuitive to use, while reducing the cognitive workload of the operator.

Polycyclic aromatic hydrocarbons - Primitive pigment systems in the prebiotic environment

NASA Technical Reports Server (NTRS)

Deamer, D. W.

1992-01-01

The chemical evolution of meteoritic organics in the primitive earth is examined experimentally with attention given to the photochemical effects of hydrocarbon/water mixtures. Also addressed are the generation of amphiphilic products by photochemical reactions and the transduction of light energy into potentially useful forms. Polycyclic aromatic hydrocarbons (PAHs) absorb light and exist in carbonaceous chondrites; PAHs are therefore examined as primitive pigments by means of salt solutions with pyrene, fluoranthene, and pyrene derivatives with hexadecane. The hexadecane undergoes photochemical oxidation and yields long-chain amphiphiles with oxygen supplied by water, and acid pH shifts also occur. PAHs are also tested in lipid bilayer membranes to examine light-energy transduction. Protons are found to accumulate within the membrane-bounded volume to form proton gradients, and this reaction is theorized to be a good model of primitive photochemical reactions that related to the transduction of light energy into useable forms.

Quantitative Model to Predict Melts on the Ol-Opx Saturation Boundary during Mantle Melting: The Role of H2O

NASA Astrophysics Data System (ADS)

Andrews, A. L.; Grove, T. L.

2014-12-01

Two quantitative, empirical models are presented that predict mantle melt compositions in equilibrium with olivine (ol) + orthopyroxene (opx) ± spinel (sp) as a function of variable pressure and H2O content. The models consist of multiple linear regressions calibrated using new data from H2O-undersaturated primitive and depleted mantle lherzolite melting experiments as well as experimental literature data. The models investigate the roles of H2O, Pressure, 1-Mg# (1-[XMg/(XMg+XFe)]), NaK# ((Na2O+K2O)/(Na2O+K2O+CaO)), TiO2, and Cr2O3 on mantle melt compositions. Melts are represented by the pseudoternary endmembers Clinopyroxene (Cpx), Olivine (Ol), Plagioclase (Plag), and Quartz (Qz) of Tormey et al. (1987). Model A returns predictive equations for the four endmembers with identical predictor variables, whereas Model B chooses predictor variables for the four compositional endmember equations and temperature independently. We employ the use of Akaike Information Criteria (Akaike, 1974) to determine the best predictor variables from initial variables chosen through thermodynamic reasoning and by previous models. In both Models A and B, the coefficients for H2O show that increasing H2O drives the melt to more Qz normative space, as the Qz component increases by +0.012(3) per 1 wt.% H2O. The other endmember components decrease and are all three times less affected by H2O (Ol: -0.004(2); Cpx: -0.004(2); Plag: -0.004(3)). Consistent with previous models and experimental data, increasing pressure moves melt compositions to more Ol normative space at the expense of the Qz component. The models presented quantitatively determine the influence of H2O, Pressure, 1-Mg#, NaK#, TiO2, and Cr2O3 on mantle melts in equilibrium with ol+opx±sp; the equations presented can be used to predict melts of known mantle source compositions saturated in ol+opx±sp. References Tormey, Grove, & Bryan (1987), doi: 10.1007/BF00375227. Akaike (1974), doi: 10.1109/TAC.1974.1100705.

Primitive Photosynthetic Architectures Based on Self-Organization and Chemical Evolution of Amino Acids and Metal Ions.

PubMed

Liu, Kai; Ren, Xiaokang; Sun, Jianxuan; Zou, Qianli; Yan, Xuehai

2018-06-01

The emergence of light-energy-utilizing metabolism is likely to be a critical milestone in prebiotic chemistry and the origin of life. However, how the primitive pigment is spontaneously generated still remains unknown. Herein, a primitive pigment model based on adaptive self-organization of amino acids (Cystine, Cys) and metal ions (zinc ion, Zn 2+ ) followed by chemical evolution under hydrothermal conditions is developed. The resulting hybrid microspheres are composed of radially aligned cystine/zinc (Cys/Zn) assembly decorated with carbonate-doped zinc sulfide (C-ZnS) nanocrystals. The part of C-ZnS can work as a light-harvesting antenna to capture ultraviolet and visible light, and use it in various photochemical reactions, including hydrogen (H 2 ) evolution, carbon dioxide (CO 2 ) photoreduction, and reduction of nicotinamide adenine dinucleotide (NAD + ) to nicotinamide adenine dinucleotide hydride (NADH). Additionally, guest molecules (e.g., glutamate dehydrogenase, GDH) can be encapsulated within the hierarchical Cys/Zn framework, which facilitates sustainable photoenzymatic synthesis of glutamate. This study helps deepen insight into the emergent functionality (conversion of light energy) and complexity (hierarchical architecture) from interaction and reaction of prebiotic molecules. The primitive pigment model is also promising to work as an artificial photosynthetic microreactor.

New results in equal sums of like powers

NASA Astrophysics Data System (ADS)

Ekl, R. L.

1998-07-01

This paper reports on new results for the equation [GRAPHICS] i.e., equal sums of like powers. Since the 1967 Lander, Parkin and Selfridge survey paper [4], few other numeric results have been published (see Elkies [6] and Ekl [3]). The present paper reports on several new smallest primitive solutions. Further, search limits have been extended in many cases, and tables of solutions are presented. Additionally, new solutions to the same class of problems in distinct integers have been discovered.

An equation involving the Smarandache primitive function and triangular numbers

NASA Astrophysics Data System (ADS)

Fu, Ruiqin; Yang, Hai; Wu, Jing

2018-04-01

All manuscripts must be in English, also the table and figure texts, otherwise we cannot publish your paper. Please keep a second copy of your manuscript in your office. When receiving the paper, we assume that the corresponding authors grant us the copyright to use the paper for the book or journal in question. Should authors use tables or figures from other Publications, they must ask the corresponding publishers to grant them the right to publish this material in their paper.

Simulations of the general circulation of the Martian atmosphere. I - Polar processes

NASA Technical Reports Server (NTRS)

Pollack, James B.; Haberle, Robert M.; Schaeffer, James; Lee, Hilda

1990-01-01

Numerical simulations of the Martian atmosphere general circulation are carried out for 50 simulated days, using a three-dimensional model, based on the primitive equations of meteorology, which incorporated the radiative effects of atmospheric dust on solar and thermal radiation. A large number of numerical experiments were conducted for alternative choices of seasonal date and dust optical depth. It was found that, as the dust content of the winter polar region increased, the rate of atmospheric CO2 condensation increased sharply. It is shown that the strong seasonal variation in the atmospheric dust content observed might cause a number of hemispheric asymmetries. These asymmetries include the greater prevalence of polar hoods in the northern polar region during winter, the lower albedo of the northern polar cap during spring, and the total dissipation of the northern CO2 ice cap during the warmer seasons.

Partitioning strategy for efficient nonlinear finite element dynamic analysis on multiprocessor computers

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Peters, Jeanne M.

1989-01-01

A computational procedure is presented for the nonlinear dynamic analysis of unsymmetric structures on vector multiprocessor systems. The procedure is based on a novel hierarchical partitioning strategy in which the response of the unsymmetric and antisymmetric response vectors (modes), each obtained by using only a fraction of the degrees of freedom of the original finite element model. The three key elements of the procedure which result in high degree of concurrency throughout the solution process are: (1) mixed (or primitive variable) formulation with independent shape functions for the different fields; (2) operator splitting or restructuring of the discrete equations at each time step to delineate the symmetric and antisymmetric vectors constituting the response; and (3) two level iterative process for generating the response of the structure. An assessment is made of the effectiveness of the procedure on the CRAY X-MP/4 computers.

Assimilation of satellite altimeter data in a primitive-equation model of the Azores Madeira region

NASA Astrophysics Data System (ADS)

Gavart, Michel; De Mey, Pierre; Caniaux, Guy

1999-07-01

The aim of this study is to implement satellite altimetric assimilation into a high-resolution primitive-equation ocean model and check the validity and sensitivity of the results. Beyond this paper, the remote objective is to get a dynamical tool capable of simulating the surface ocean processes linked to the air-sea interactions as well as to perform mesoscale ocean forecasting. For computational cost and practical reasons, this study takes place in a 1000 by 1000 sq km open domain of the Canary basin. The assimilation experiments are carried out with the combined TOPEX/POSEIDON and ERS-1 data sets between June 1993 and December 1993. The space-time domain overlaps with in situ data collected during the SEMAPHORE experiment and thus enables an objective validation of the results. A special boundary treatment is applied to the model by creating a surrounding recirculating area separated from the interior by a buffer zone. The altimetric assimilation is done by implementing a reduced-order optimal interpolation algorithm with a special vertical projection of the surface model/data misfits. We perform a first experiment with a vertical projection onto an isopycnal EOF representing the Azores Current vertical variability. An objective validation of the model's velocities with Lagrangian float data shows good results (the correlation is 0.715 at 150 dbar). The question of the sensitivity to the vertical projection is addressed by performing similar experiments using a method for lifting/lowering of the water column, and using an EOF in Z-coordinates. Some comparisons with in situ temperature data do not show any significant difference between the three projections, after five months of assimilation. However, in order to preserve the large-scale water characteristics, we felt that the isopycnal projection was a more physically consistent choice. Then, the complementary character of the two satellites is assessed with two additional experiments which use each altimeter data sets separately. There is an evidence of the benefit of combining the two data sets. Otherwise, an experiment assimilating long-wavelength bias-corrected CLS altimetric maps every 10 days exhibits the best correlation scores and emphasizes the importance of reducing the orbit error and biases in the altimetric data sets. The surface layers of the model are forced using realistic daily wind stress values computed from ECMWF analyses. Although we resolve small space and time scales, in our limited domain the wind stress does not significantly influence the quality of the results obtained with the altimetric assimilation. Finally, the relative effects of the data selection procedure and of the integration times (cycle lengths) is explored by performing data window experiments. A value of 10 days seems to be the most satisfactory cycle length.

Software Assurance Curriculum Project Volume 1: Master of Software Assurance Reference Curriculum

DTIC Science & Technology

2010-08-01

activity by providing a check on the relevance and currency of the process used to develop the MSwA2010 curriculum content. Figure 2 is an expansion of...random oracle model, symmetric crypto primitives, modes of operations, asymmetric crypto primitives (Chapter 5) [16] Detailed design...encryption, public key encryption, digital signatures, message authentication codes, crypto protocols, cryptanalysis, and further detailed crypto

Sandboxes for Model-Based Inquiry

NASA Astrophysics Data System (ADS)

Brady, Corey; Holbert, Nathan; Soylu, Firat; Novak, Michael; Wilensky, Uri

2015-04-01

In this article, we introduce a class of constructionist learning environments that we call Emergent Systems Sandboxes ( ESSs), which have served as a centerpiece of our recent work in developing curriculum to support scalable model-based learning in classroom settings. ESSs are a carefully specified form of virtual construction environment that support students in creating, exploring, and sharing computational models of dynamic systems that exhibit emergent phenomena. They provide learners with "entity"-level construction primitives that reflect an underlying scientific model. These primitives can be directly "painted" into a sandbox space, where they can then be combined, arranged, and manipulated to construct complex systems and explore the emergent properties of those systems. We argue that ESSs offer a means of addressing some of the key barriers to adopting rich, constructionist model-based inquiry approaches in science classrooms at scale. Situating the ESS in a large-scale science modeling curriculum we are implementing across the USA, we describe how the unique "entity-level" primitive design of an ESS facilitates knowledge system refinement at both an individual and social level, we describe how it supports flexible modeling practices by providing both continuous and discrete modes of executability, and we illustrate how it offers students a variety of opportunities for validating their qualitative understandings of emergent systems as they develop.

Capture, Learning, and Classification of Upper Extremity Movement Primitives in Healthy Controls and Stroke Patients

PubMed Central

Guerra, Jorge; Uddin, Jasim; Nilsen, Dawn; Mclnerney, James; Fadoo, Ammarah; Omofuma, Isirame B.; Hughes, Shatif; Agrawal, Sunil; Allen, Peter; Schambra, Heidi M.

2017-01-01

There currently exist no practical tools to identify functional movements in the upper extremities (UEs). This absence has limited the precise therapeutic dosing of patients recovering from stroke. In this proof-of-principle study, we aimed to develop an accurate approach for classifying UE functional movement primitives, which comprise functional movements. Data were generated from inertial measurement units (IMUs) placed on upper body segments of older healthy individuals and chronic stroke patients. Subjects performed activities commonly trained during rehabilitation after stroke. Data processing involved the use of a sliding window to obtain statistical descriptors, and resulting features were processed by a Hidden Markov Model (HMM). The likelihoods of the states, resulting from the HMM, were segmented by a second sliding window and their averages were calculated. The final predictions were mapped to human functional movement primitives using a Logistic Regression algorithm. Algorithm performance was assessed with a leave-one-out analysis, which determined its sensitivity, specificity, and positive and negative predictive values for all classified primitives. In healthy control and stroke participants, our approach identified functional movement primitives embedded in training activities with, on average, 80% precision. This approach may support functional movement dosing in stroke rehabilitation. PMID:28813877

Hydrazines and carbohydrazides produced from oxidized carbon in earth's primitive environment

NASA Technical Reports Server (NTRS)

Folsome, C. E.; Brittain, A.; Smith, A.; Chang, S.

1981-01-01

Whether abiological organic compounds can be formed from the interactions of energy sources with nitrogen, oxidized carbon and water is held to be of importance in geochemical models of the primordial earth atmosphere. It is reported that experiments using quenched spark discharges through molecular nitrogen on aqueous suspensions of CaCO3 and other reactants to simulate the hydrosphere/atmosphere interface yield hydrazine and carbohydrazine in significant but low yields. Such reactions in primitive aquatic environments may have supplied a pathway for chemical evolution and the origin of life, on a primitive earth in which fully oxidized states of carbon were available for the primary synthesis of organic matter.

Deictic primitives for general purpose navigation

NASA Technical Reports Server (NTRS)

Crismann, Jill D.

1994-01-01

A visually-based deictic primative used as an elementary command set for general purpose navigation was investigated. It was shown that a simple 'follow your eyes' scenario is sufficient for tracking a moving target. Limitations of velocity, acceleration, and modeling of the response of the mechanical systems were enforced. Realistic paths of the robots were produced during the simulation. Scientists could remotely command a planetary rover to go to a particular rock formation that may be interesting. Similarly an expert at plant maintenance could obtain diagnostic information remotely by using deictic primitives on a mobile are used in the deictic primitives, we could imagine that the exact same control software could be used for all of these applications.

Toward higher order tests of the gravitational interaction

NASA Technical Reports Server (NTRS)

Nordtvedt, Ken

1989-01-01

Analyses and interpretations of experiments which test post-Newtonian gravity are usually done under the assumption that gravity is a metric field phenomenon - a manifestation of space-time geometry. This, however, is unnecessary and one can start at a more primitive level - that there simply exists a phenomenological, gravitational, many-body equation of motion which must be determined by a package of observations. In fact, over the last couple decades, a diverse collection of solar system interbody tracking observations, supplemented by data from the binary pulsar system PSR 1913 + 16, has completely mapped out the first post-Newtonian order. After the fact, using empirically determined equations of motion, along with some observed properties of nongravitational clocks and rulers and conservation laws for energy, momentum and angular momentum, a post-Newtonian Lagrangian can be constructed, a geometrical space-time metric field conceptual interpretation can be developed, Lorentz invariance of the equations of motion can be shown, and the equations of motion are found to agree with the predictions of Einstein's gravitational theory, General Relativity, within experimental accuracy.

On hydrostatic flows in isentropic coordinates

NASA Astrophysics Data System (ADS)

Bokhove, Onno

2000-01-01

The hydrostatic primitive equations of motion which have been used in large-scale weather prediction and climate modelling over the last few decades are analysed with variational methods in an isentropic Eulerian framework. The use of material isentropic coordinates for the Eulerian hydrostatic equations is known to have distinct conceptual advantages since fluid motion is, under inviscid and statically stable circumstances, confined to take place on quasi-horizontal isentropic surfaces. First, an Eulerian isentropic Hamilton's principle, expressed in terms of fluid parcel variables, is therefore derived by transformation of a Lagrangian Hamilton's principle to an Eulerian one. This Eulerian principle explicitly describes the boundary dynamics of the time-dependent domain in terms of advection of boundary isentropes sB; these are the values the isentropes have at their intersection with the (lower) boundary. A partial Legendre transform for only the interior variables yields an Eulerian ‘action’ principle. Secondly, Noether's theorem is used to derive energy and potential vorticity conservation from the Eulerian Hamilton's principle. Thirdly, these conservation laws are used to derive a wave-activity invariant which is second-order in terms of small-amplitude disturbances relative to a resting or moving basic state. Linear stability criteria are derived but only for resting basic states. In mid-latitudes a time- scale separation between gravity and vortical modes occurs. Finally, this time-scale separation suggests that conservative geostrophic and ageostrophic approximations can be made to the Eulerian action principle for hydrostatic flows. Approximations to Eulerian variational principles may be more advantageous than approximations to Lagrangian ones because non-dimensionalization and scaling tend to be based on Eulerian estimates of the characteristic scales involved. These approximations to the stratified hydrostatic formulation extend previous approximations to the shallow- water equations. An explicit variational derivation is given of an isentropic version of Hoskins & Bretherton's model for atmospheric fronts.

Automatic determination of fault effects on aircraft functionality

NASA Technical Reports Server (NTRS)

Feyock, Stefan

1989-01-01

The problem of determining the behavior of physical systems subsequent to the occurrence of malfunctions is discussed. It is established that while it was reasonable to assume that the most important fault behavior modes of primitive components and simple subsystems could be known and predicted, interactions within composite systems reached levels of complexity that precluded the use of traditional rule-based expert system techniques. Reasoning from first principles, i.e., on the basis of causal models of the physical system, was required. The first question that arises is, of course, how the causal information required for such reasoning should be represented. The bond graphs presented here occupy a position intermediate between qualitative and quantitative models, allowing the automatic derivation of Kuipers-like qualitative constraint models as well as state equations. Their most salient feature, however, is that entities corresponding to components and interactions in the physical system are explicitly represented in the bond graph model, thus permitting systematic model updates to reflect malfunctions. Researchers show how this is done, as well as presenting a number of techniques for obtaining qualitative information from the state equations derivable from bond graph models. One insight is the fact that one of the most important advantages of the bond graph ontology is the highly systematic approach to model construction it imposes on the modeler, who is forced to classify the relevant physical entities into a small number of categories, and to look for two highly specific types of interactions among them. The systematic nature of bond graph model construction facilitates the process to the point where the guidelines are sufficiently specific to be followed by modelers who are not domain experts. As a result, models of a given system constructed by different modelers will have extensive similarities. Researchers conclude by pointing out that the ease of updating bond graph models to reflect malfunctions is a manifestation of the systematic nature of bond graph construction, and the regularity of the relationship between bond graph models and physical reality.

Monitoring air quality in California's Central Valley with aircraft and continuous mountaintop observations - attribution insights gained by considering the scalar budget equation

NASA Astrophysics Data System (ADS)

Faloona, I. C.; Trousdell, J.; Caputi, D.; Conley, S. A.

2017-12-01

Ozone is one of the six criteria pollutants established by the US EPA's Clean Air Act, and one of two that still routinely violates federal standards as it is a secondary pollutant and therefore subject to indirect control strategies on complex, non-linear atmospheric chemistry. While improvements have been seen in many regions where ozone controls are in place, gains in California's San Joaquin Valley have lagged many other districts across the state. We present airborne measurements from several different campaigns in the valley (DISCOVER-AQ, ArvinO3, and CABOTS) along with data from a mountaintop monitoring site on its upwind side near the Pacific coast that has been operational for 5 years, and we shed light on several outstanding questions concerning air pollution in California's vast Central Valley. The framework of analysis is centered on the primitive equation of any atmospheric constituent - the scalar budget equation. By measuring each term in this equation, we gain insights into the relative impacts of exogenous (due to long range transport) vs. endogenous ozone (due to local photochemical production). We further argue that small aircraft campaigns with an emphasis on scalar budgeting sorties are a cost-effective tool in uncovering specific shortcomings of regional air quality models (e.g., lateral boundary conditions can be tested by comparing horizontal advection, turbulence parameterizations by comparing vertical fluxes, and chemical mechanisms by comparing net photochemical production rates.) In the case of NOx and CH4, for instance, we find that solving for surface emissions points toward inventory underestimates of both species by at least a factor of two. We discuss possible causes of these discrepancies, and suggest other ways to specifically vet aspects of regional air quality models with airborne measurements of meteorological and chemical variables.

Data assimilation experiments using the diffusive back and forth nudging for the NEMO ocean model

NASA Astrophysics Data System (ADS)

Ruggiero, G. A.; Ourmières, Y.; Cosme, E.; Blum, J.; Auroux, D.; Verron, J.

2014-07-01

The Diffusive Back and Forth Nudging (DBFN) is an easy-to-implement iterative data assimilation method based on the well-known Nudging method. It consists in a sequence of forward and backward model integrations, within a given time window, both of them using a feedback term to the observations. Therefore in the DBFN, the Nudging asymptotic behavior is translated into an infinite number of iterations within a bounded time domain. In this method, the backward integration is carried out thanks to what is called backward model, which is basically the forward model with reversed time step sign. To maintain numeral stability the diffusion terms also have their sign reversed, giving a diffusive character to the algorithm. In this article the DBFN performance to control a primitive equation ocean model is investigated. In this kind of model non-resolved scales are modeled by diffusion operators which dissipate energy that cascade from large to small scales. Thus, in this article the DBFN approximations and their consequences on the data assimilation system set-up are analyzed. Our main result is that the DBFN may provide results which are comparable to those produced by a 4Dvar implementation with a much simpler implementation and a shorter CPU time for convergence.

A new approach for developing adjoint models

NASA Astrophysics Data System (ADS)

Farrell, P. E.; Funke, S. W.

2011-12-01

Many data assimilation algorithms rely on the availability of gradients of misfit functionals, which can be efficiently computed with adjoint models. However, the development of an adjoint model for a complex geophysical code is generally very difficult. Algorithmic differentiation (AD, also called automatic differentiation) offers one strategy for simplifying this task: it takes the abstraction that a model is a sequence of primitive instructions, each of which may be differentiated in turn. While extremely successful, this low-level abstraction runs into time-consuming difficulties when applied to the whole codebase of a model, such as differentiating through linear solves, model I/O, calls to external libraries, language features that are unsupported by the AD tool, and the use of multiple programming languages. While these difficulties can be overcome, it requires a large amount of technical expertise and an intimate familiarity with both the AD tool and the model. An alternative to applying the AD tool to the whole codebase is to assemble the discrete adjoint equations and use these to compute the necessary gradients. With this approach, the AD tool must be applied to the nonlinear assembly operators, which are typically small, self-contained units of the codebase. The disadvantage of this approach is that the assembly of the discrete adjoint equations is still very difficult to perform correctly, especially for complex multiphysics models that perform temporal integration; as it stands, this approach is as difficult and time-consuming as applying AD to the whole model. In this work, we have developed a library which greatly simplifies and automates the alternate approach of assembling the discrete adjoint equations. We propose a complementary, higher-level abstraction to that of AD: that a model is a sequence of linear solves. The developer annotates model source code with library calls that build a 'tape' of the operators involved and their dependencies, and supplies callbacks to compute the action of these operators. The library, called libadjoint, is then capable of symbolically manipulating the forward annotation to automatically assemble the adjoint equations. Libadjoint is open source, and is explicitly designed to be bolted-on to an existing discrete model. It can be applied to any discretisation, steady or time-dependent problems, and both linear and nonlinear systems. Using libadjoint has several advantages. It requires the application of an AD tool only to small pieces of code, making the use of AD far more tractable. As libadjoint derives the adjoint equations, the expertise required to develop an adjoint model is greatly diminished. One major advantage of this approach is that the model developer is freed from implementing complex checkpointing strategies for the adjoint model: libadjoint has sufficient information about the forward model to re-play the entire forward solve when necessary, and thus the checkpointing algorithm can be implemented entirely within the library itself. Examples are shown using the Fluidity/ICOM framework, a complex ocean model under development at Imperial College London.

Combination Chemotherapy in Treating Patients With Non-Metastatic Extracranial Ewing Sarcoma

ClinicalTrials.gov

2018-02-09

Adult Supratentorial Primitive Neuroectodermal Tumor (PNET); Childhood Supratentorial Primitive Neuroectodermal Tumor; Ewing Sarcoma of Bone; Extraosseous Ewing Sarcoma; Extraosseous Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Localized Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Peripheral Primitive Neuroectodermal Tumor of the Kidney; Untreated Childhood Supratentorial Primitive Neuroectodermal Tumor

Energy-optimal path planning in the coastal ocean

NASA Astrophysics Data System (ADS)

Subramani, Deepak N.; Haley, Patrick J.; Lermusiaux, Pierre F. J.

2017-05-01

We integrate data-driven ocean modeling with the stochastic Dynamically Orthogonal (DO) level-set optimization methodology to compute and study energy-optimal paths, speeds, and headings for ocean vehicles in the Middle-Atlantic Bight (MAB) region. We hindcast the energy-optimal paths from among exact time-optimal paths for the period 28 August 2006 to 9 September 2006. To do so, we first obtain a data-assimilative multiscale reanalysis, combining ocean observations with implicit two-way nested multiresolution primitive-equation simulations of the tidal-to-mesoscale dynamics in the region. Second, we solve the reduced-order stochastic DO level-set partial differential equations (PDEs) to compute the joint probability of minimum arrival time, vehicle-speed time series, and total energy utilized. Third, for each arrival time, we select the vehicle-speed time series that minimize the total energy utilization from the marginal probability of vehicle-speed and total energy. The corresponding energy-optimal path and headings are obtained through the exact particle-backtracking equation. Theoretically, the present methodology is PDE-based and provides fundamental energy-optimal predictions without heuristics. Computationally, it is 3-4 orders of magnitude faster than direct Monte Carlo methods. For the missions considered, we analyze the effects of the regional tidal currents, strong wind events, coastal jets, shelfbreak front, and other local circulations on the energy-optimal paths. Results showcase the opportunities for vehicles that intelligently utilize the ocean environment to minimize energy usage, rigorously integrating ocean forecasting with optimal control of autonomous vehicles.

Energy Optimal Path Planning: Integrating Coastal Ocean Modelling with Optimal Control

NASA Astrophysics Data System (ADS)

Subramani, D. N.; Haley, P. J., Jr.; Lermusiaux, P. F. J.

2016-02-01

A stochastic optimization methodology is formulated for computing energy-optimal paths from among time-optimal paths of autonomous vehicles navigating in a dynamic flow field. To set up the energy optimization, the relative vehicle speed and headings are considered to be stochastic, and new stochastic Dynamically Orthogonal (DO) level-set equations that govern their stochastic time-optimal reachability fronts are derived. Their solution provides the distribution of time-optimal reachability fronts and corresponding distribution of time-optimal paths. An optimization is then performed on the vehicle's energy-time joint distribution to select the energy-optimal paths for each arrival time, among all stochastic time-optimal paths for that arrival time. The accuracy and efficiency of the DO level-set equations for solving the governing stochastic level-set reachability fronts are quantitatively assessed, including comparisons with independent semi-analytical solutions. Energy-optimal missions are studied in wind-driven barotropic quasi-geostrophic double-gyre circulations, and in realistic data-assimilative re-analyses of multiscale coastal ocean flows. The latter re-analyses are obtained from multi-resolution 2-way nested primitive-equation simulations of tidal-to-mesoscale dynamics in the Middle Atlantic Bight and Shelbreak Front region. The effects of tidal currents, strong wind events, coastal jets, and shelfbreak fronts on the energy-optimal paths are illustrated and quantified. Results showcase the opportunities for longer-duration missions that intelligently utilize the ocean environment to save energy, rigorously integrating ocean forecasting with optimal control of autonomous vehicles.

Spectral evolution of weakly nonlinear random waves: kinetic description vs direct numerical simulations

NASA Astrophysics Data System (ADS)

Annenkov, Sergei; Shrira, Victor

2016-04-01

We study numerically the long-term evolution of water wave spectra without wind forcing, using three different models, aiming at understanding the role of different sets of assumptions. The first model is the classical Hasselmann kinetic equation (KE). We employ the WRT code kindly provided by G. van Vledder. Two other models are new. As the second model, we use the generalised kinetic equation (gKE), derived without the assumption of quasi-stationarity. Thus, unlike the KE, the gKE is valid in the cases when a wave spectrum is changing rapidly (e.g. at the initial stage of evolution of a narrow spectrum). However, the gKE employs the same statistical closure as the KE. The third model is based on the Zakharov integrodifferential equation for water waves and does not depend on any statistical assumptions. Since the Zakharov equation plays the role of the primitive equation of the theory of wave turbulence, we refer to this model as direct numerical simulation of spectral evolution (DNS-ZE). For initial conditions, we choose two narrow-banded spectra with the same frequency distribution (a JONSWAP spectrum with high peakedness γ = 6) and different degrees of directionality. These spectra are from the set of observations collected in a directional wave tank by Onorato et al (2009). Spectrum A is very narrow in angle (corresponding to N = 840 in the cosN directional model). Spectrum B is initially wider in angle (corresponds to N = 24). Short-term evolution of both spectra (O(102) wave periods) has been studied numerically by Xiao et al (2013) using two other approaches (broad-band modified nonlinear Schrödinger equation and direct numerical simulation based on the high-order spectral method). We use these results to verify the initial stage of our DNS-ZE simulations. However, the advantage of the DNS-ZE method is that it allows to study long-term spectral evolution (up to O(104) periods), which was previously possible only with the KE. In the short-term evolution, we find a good agreement between our DNS-ZE results and simulations by Xiao et al (2013), both for the evolution of frequency spectra and for the directional spreading. In the long term, all three approaches demonstrate very close evolution of integral characteristics of spectra, approaching for large time the theoretical asymptotes of the self-similar stage of evolution. However, the detailed comparison of the spectral evolution shows certain notable differences. Both kinetic equations give virtually identical evolution of spectrum B, but in the case of initially nearly one-dimensional spectrum A the KE overestimates the amplitude of the spectral peak. Meanwhile, the DNS-ZE results show considerably wider spectra with less pronounced peak. There is a striking difference for the rate of spectral broadening, which is much larger for the gKE and especially for the KE, than for the DNS-ZE. We show that the rates of change of the spectra obtained with the DNS-ZE are proportional to the fourth power of nonlinearity, corresponding to the dynamical timescale of evolution, rather than the statistical timescale of both kinetic equations.

Advanced Robotics for In-Space Vehicle Processing

NASA Technical Reports Server (NTRS)

Smith, Jeffrey H.; Estus, Jay; Heneghan, Cate; Bosley, John

1990-01-01

An analysis of spaceborne vehicle processing is described. Generic crew-EVA tasks are presented for a specific vehicle, the orbital maneuvering vehicle (OMV), with general implications to other on-orbit vehicles. The OMV is examined with respect to both servicing and maintenance. Crew-EVA activities are presented by task and mapped to a common set of generic crew-EVA primitives to identify high-demand areas for telerobot services. Similarly, a set of telerobot primitives is presented that can be used to model telerobot actions for alternative telerobot reference configurations. The telerobot primitives are tied to technologies and used for composting telerobot operations for an automated refueling scenario. Telerobotics technology issues and design accomodation guidelines (hooks and scars) for the Space Station Freedom are described.

Dynamics of the Antarctic Circumpolar Current. Evidence for Topographic Effects from Altimeter Data and Numerical Model Output

NASA Technical Reports Server (NTRS)

Gille, Sarah T.

1995-01-01

Geosat altimeter data and numerical model output are used to examine the circulation and dynamics of the Antarctic Circumpolar Current (ACC). The mean sea surface height across the ACC has been reconstructed from height variability measured by the altimeter, without assuming prior knowledge of the geoid. The results indicate locations for the Subantarctic and Polar Fronts which are consistent with in situ observations and indicate that the fronts are substantially steered by bathymetry. Detailed examination of spatial and temporal variability indicates a spatial decorrelation scale of 85 km and a temporal e-folding scale of 34 days. Empirical Orthogonal Function analysis suggests that the scales of motion are relatively short, occuring on 1000 km length-scales rather than basin or global scales. The momentum balance of the ACC has been investigated using output from the high resolution primitive equation model in combination with altimeter data. In the Semtner-Chervin quarter-degree general circulation model topographic form stress is the dominant process balancing the surface wind forcing. In stream coordinates, the dominant effect transporting momentum across the ACC is bibarmonic friction. Potential vorticity is considered on Montgomery streamlines in the model output and along surface streamlines in model and altimeter data. (AN)

Nongeostrophic theory of zonally averaged circulation. I - Formulation

NASA Technical Reports Server (NTRS)

Tung, Ka Kit

1986-01-01

A nongeostrophic theory of zonally averaged circulation is formulated using the nonlinear primitive equations (mass conservation, thermodynamics, and zonal momentum) on a sphere. The relationship between the mean meridional circulation and diabatic heating rate is studied. Differences between results of nongeostropic theory and the geostrophic formulation concerning the role of eddy forcing of the diabatic circulation and the nonlinear nearly inviscid limit versus the geostrophic limit are discussed. Consideration is given to the Eliassen-Palm flux divergence, the Eliassen-Palm pseudodivergence, the nonacceleration theorem, and the nonlinear nongeostrophic Taylor relationship.

A Formal Approach to the Provably Correct Synthesis of Mission Critical Embedded Software for Multi Core Embedded Platforms

DTIC Science & Technology

2014-04-01

synchronization primitives based on preset templates can result in over synchronization if unchecked, possibly creating deadlock situations. Further...inputs rather than enforcing synchronization with a global clock. MRICDF models software as a network of communicating actors. Four primitive actors...control wants to send interrupt or not. Since this is shared buffer, a semaphore mechanism is assumed to synchronize the read/write of this buffer. The

Contamination of the asteroid belt by primordial trans-Neptunian objects.

PubMed

Levison, Harold F; Bottke, William F; Gounelle, Matthieu; Morbidelli, Alessandro; Nesvorný, David; Tsiganis, Kleomenis

2009-07-16

The main asteroid belt, which inhabits a relatively narrow annulus approximately 2.1-3.3 au from the Sun, contains a surprising diversity of objects ranging from primitive ice-rock mixtures to igneous rocks. The standard model used to explain this assumes that most asteroids formed in situ from a primordial disk that experienced radical chemical changes within this zone. Here we show that the violent dynamical evolution of the giant-planet orbits required by the so-called Nice model leads to the insertion of primitive trans-Neptunian objects into the outer belt. This result implies that the observed diversity of the asteroid belt is not a direct reflection of the intrinsic compositional variation of the proto-planetary disk. The dark captured bodies, composed of organic-rich materials, would have been more susceptible to collisional evolution than typical main-belt asteroids. Their weak nature makes them a prodigious source of micrometeorites-sufficient to explain why most are primitive in composition and are isotopically different from most macroscopic meteorites.

A comparison of two- and three-dimensional tracer transport within a stratospheric circulation model

NASA Technical Reports Server (NTRS)

Schneider, H.-R.; Geller, M. A.

1985-01-01

Use of the residual circulation for stratospheric tracer transport has been compared to a fully three-dimensional calculation. The wind fields used in this study were obtained from a global, semispectral, primitive equation model, extending from 10 to 100 km in altitude. Comparisons were done with a passive tracer and an ozone-like substance over a two-month period corresponding to a Northern Hemisphere winter. It was found that the use of the residual circulation can lead to errors in the tracer concentrations of about a factor of 2. The error is made up of two components. One is fluctuating with a period of approximately one month and reflects directly the wave transience that occurs on that time-scale. The second part is increasing steadily over the integration period and results from an overestimate of the vertical transport by the residual circulation. Furthermore, the equatorward and upward mixing that occurs with transport by the three-dimensional circulation at low latitudes is not well reproduced when the residual circulation is used.

Origin of primitive ocean island basalts by crustal gabbro assimilation and multiple recharge of plume-derived melts

NASA Astrophysics Data System (ADS)

Borisova, Anastassia Y.; Bohrson, Wendy A.; Grégoire, Michel

2017-07-01

Chemical Geodynamics relies on a paradigm that the isotopic composition of ocean island basalt (OIB) represents equilibrium with its primary mantle sources. However, the discovery of huge isotopic heterogeneity within olivine-hosted melt inclusions in primitive basalts from Kerguelen, Iceland, Hawaii and South Pacific Polynesia islands implies open-system behavior of OIBs, where during magma residence and transport, basaltic melts are contaminated by surrounding lithosphere. To constrain the processes of crustal assimilation by OIBs, we employed the Magma Chamber Simulator (MCS), an energy-constrained thermodynamic model of recharge, assimilation and fractional crystallization. For a case study of the 21-19 Ma basaltic series, the most primitive series ever found among the Kerguelen OIBs, we performed sixty-seven simulations in the pressure range from 0.2 to 1.0 GPa using compositions of olivine-hosted melt inclusions as parental magmas, and metagabbro xenoliths from the Kerguelen Archipelago as wallrock. MCS modeling requires that the assimilant is anatectic crustal melts (P2O5 ≤ 0.4 wt.% contents) derived from the Kerguelen oceanic metagabbro wallrock. To best fit the phenocryst assemblage observed in the investigated basaltic series, recharge of relatively large masses of hydrous primitive basaltic melts (H2O = 2-3 wt%; MgO = 7-10 wt.%) into a middle crustal chamber at 0.2 to 0.3 GPa is required. Our results thus highlight the important impact that crustal gabbro assimilation and mantle recharge can have on the geochemistry of mantle-derived olivine-phyric OIBs. The importance of crustal assimilation affecting primitive plume-derived basaltic melts underscores that isotopic and chemical equilibrium between ocean island basalts and associated deep plume mantle source(s) may be the exception rather than the rule.

The Specific Features of Pollution Transport in the Northwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Diansky, Nikolay; Fomin, Vladimir; Gusev, Anatoly

2013-04-01

Two calculations of pollutant dispersal in the Northwest Pacific Ocean are presented: (1) during possible shipwrecks in the process of spent nuclear fuel transportation from Petropavlovsk-Kamchatsky and (2) pollutant spread from the Japanese coast after the Fukushima 1 nuclear disaster on March 11, 2011. The circulation was simulated using a σ - coordinate ocean model INMOM (Institute of Numerical Mathematics Ocean Model) developed at the INM RAS. The INMOM is based on the primitive equations using the spherical σ - coordinate system with a free ocean surface. The INMOM was realized for the Pacific Ocean basin from the equator to the Bering Strait with a high 1/8° spatial resolution for reproducing the mesoscale ocean variability. The pollutant dispersal in the case of possible shipwrecks was estimated for currents for a statistically average year with atmospheric forcing from Common Ocean-ice Reference Experiments (CORE) for normal year data. The pollution spread from the Fukushima 1 nuclear power plant (NPP) was estimated for currents calculated with the real atmospheric forcing in accordance with the NCEP GFS (0.5 degree grid). The simulation period of pollutant dispersal from Fukushima 1 was 17 days: from March 11 to 28, 2011. The results of numerical simulation show that pollutant dispersal from the Fukushima 1 spread eastward according to the Kuroshio. Moreover, exceeding of natural background radiation level was simulated in the narrow region of the Japanese coast with width of less than 50 km.

Nature of global large-scale sea level variability in relation to atmospheric forcing: A modeling study

NASA Astrophysics Data System (ADS)

Fukumori, Ichiro; Raghunath, Ramanujam; Fu, Lee-Lueng

1998-03-01

The relation between large-scale sea level variability and ocean circulation is studied using a numerical model. A global primitive equation model of the ocean is forced by daily winds and climatological heat fluxes corresponding to the period from January 1992 to January 1994. The physical nature of sea level's temporal variability from periods of days to a year is examined on the basis of spectral analyses of model results and comparisons with satellite altimetry and tide gauge measurements. The study elucidates and diagnoses the inhomogeneous physics of sea level change in space and frequency domain. At midlatitudes, large-scale sea level variability is primarily due to steric changes associated with the seasonal heating and cooling cycle of the surface layer. In comparison, changes in the tropics and high latitudes are mainly wind driven. Wind-driven variability exhibits a strong latitudinal dependence in itself. Wind-driven changes are largely baroclinic in the tropics but barotropic at higher latitudes. Baroclinic changes are dominated by the annual harmonic of the first baroclinic mode and is largest off the equator; variabilities associated with equatorial waves are smaller in comparison. Wind-driven barotropic changes exhibit a notable enhancement over several abyssal plains in the Southern Ocean, which is likely due to resonant planetary wave modes in basins semienclosed by discontinuities in potential vorticity. Otherwise, barotropic sea level changes are typically dominated by high frequencies with as much as half the total variance in periods shorter than 20 days, reflecting the frequency spectra of wind stress curl. Implications of the findings with regards to analyzing observations and data assimilation are discussed.

Pursuit-evasion games with information uncertainties for elusive orbital maneuver and space object tracking

NASA Astrophysics Data System (ADS)

Shen, Dan; Jia, Bin; Chen, Genshe; Blasch, Erik; Pham, Khanh

2015-05-01

This paper develops and evaluates a pursuit-evasion (PE) game approach for elusive orbital maneuver and space object tracking. Unlike the PE games in the literature, where the assumption is that either both players have perfect knowledge of the opponents' positions or use primitive sensing models, the proposed PE approach solves the realistic space situation awareness (SSA) problem with imperfect information, where the evaders will exploit the pursuers' sensing and tracking models to confuse their opponents by maneuvering their orbits to increase the uncertainties, which the pursuers perform orbital maneuvers to minimize. In the game setup, each game player P (pursuer) and E (evader) has its own motion equations with a small continuous low-thrust. The magnitude of the low thrust is fixed and the direction can be controlled by the associated game player. The entropic uncertainty is used to generate the cost functions of game players. The Nash or mixed Nash equilibrium is composed of the directional controls of low-thrusts. Numerical simulations are emulated to demonstrate the performance. Simplified perturbations models (SGP4/SDP4) are exploited to calculate the ground truth of the satellite states (position and speed).

A zonally averaged, three-basin ocean circulation model for climate studies

NASA Astrophysics Data System (ADS)

Hovine, S.; Fichefet, T.

1994-09-01

A two-dimensional, three-basin ocean model suitable for long-term climate studies is developed. The model is based on the zonally averaged form of the primitive equations written in spherical coordinates. The east-west density difference which arises upon averaging the momentum equations is taken to be proportional to the meridional density gradient. Lateral exchanges of heat and salt between the basins are explicitly resolved. Moreover, the model includes bottom topography and has representations of the Arctic Ocean and of the Weddell and Ross seas. Under realistic restoring boundary conditions, the model reproduces the global conveyor belt: deep water is formed in the Atlantic between 60 and 70°N at a rate of about 17 Sv (1 Sv=106 m3 s-1) and in the vicinity of the Antarctic continent, while the Indian and Pacific basins show broad upwelling. Superimposed on this thermohaline circulation are vigorous wind-driven cells in the upper thermocline. The simulated temperature and salinity fields and the computed meridional heat transport compare reasonably well with the observational estimates. When mixed boundary conditions (i.e., a restoring condition on sea-surface temperature and flux condition on sea-surface salinity) are applied, the model exhibits an irregular behavior before reaching a steady state characterized by self-sustained oscillations of 8.5-y period. The conveyor-belt circulation always results at this stage. A series of perturbation experiments illustrates the ability of the model to reproduce different steady-state circulations under mixed boundary conditions. Finally, the model sensitivity to various factors is examined. This sensitivity study reveals that the bottom topography and the presence of a submarine meridional ridge in the zone of the Drake Passage play a crucial role in determining the properties of the model bottom-water masses. The importance of the seasonality of the surface forcing is also stressed.

Microfluidic assay of the deformability of primitive erythroblasts.

PubMed

Zhou, Sitong; Huang, Yu-Shan; Kingsley, Paul D; Cyr, Kathryn H; Palis, James; Wan, Jiandi

2017-09-01

Primitive erythroblasts (precursors of red blood cells) enter vascular circulation during the embryonic period and mature while circulating. As a result, primitive erythroblasts constantly experience significant hemodynamic shear stress. Shear-induced deformation of primitive erythroblasts however, is poorly studied. In this work, we examined the deformability of primitive erythroblasts at physiologically relevant flow conditions in microfluidic channels and identified the regulatory roles of the maturation stage of primitive erythroblasts and cytoskeletal protein 4.1 R in shear-induced cell deformation. The results showed that the maturation stage affected the deformability of primitive erythroblasts significantly and that primitive erythroblasts at later maturational stages exhibited a better deformability due to a matured cytoskeletal structure in the cell membrane.

Quasi-Geostrophic Diagnosis of Mixed-Layer Dynamics Embedded in a Mesoscale Turbulent Field

NASA Astrophysics Data System (ADS)

Chavanne, C. P.; Klein, P.

2016-02-01

A new quasi-geostrophic model has been developed to diagnose the three-dimensional circulation, including the vertical velocity, in the upper ocean from high-resolution observations of sea surface height and buoyancy. The formulation for the adiabatic component departs from the classical surface quasi-geostrophic framework considered before since it takes into account the stratification within the surface mixed-layer that is usually much weaker than that in the ocean interior. To achieve this, the model approximates the ocean with two constant-stratification layers : a finite-thickness surface layer (or the mixed-layer) and an infinitely-deep interior layer. It is shown that the leading-order adiabatic circulation is entirely determined if both the surface streamfunction and buoyancy anomalies are considered. The surface layer further includes a diabatic dynamical contribution. Parameterization of diabatic vertical velocities is based on their restoring impacts of the thermal-wind balance that is perturbed by turbulent vertical mixing of momentum and buoyancy. The model skill in reproducing the three-dimensional circulation in the upper ocean from surface data is checked against the output of a high-resolution primitive-equation numerical simulation. Correlation between simulated and diagnosed vertical velocities are significantly improved in the mixed-layer for the new model compared to the classical surface quasi-geostrophic model, reaching 0.9 near the surface.

Correct Patterning of the Primitive Streak Requires the Anterior Visceral Endoderm

PubMed Central

Stuckey, Daniel W.; Di Gregorio, Aida; Clements, Melanie; Rodriguez, Tristan A.

2011-01-01

Anterior-posterior axis specification in the mouse requires signalling from a specialised extra-embryonic tissue called the anterior visceral endoderm (AVE). AVE precursors are induced at the distal tip of the embryo and move to the prospective anterior. Embryological and genetic analysis has demonstrated that the AVE is required for anterior patterning and for correctly positioning the site of primitive streak formation by inhibiting Nodal activity. We have carried out a genetic ablation of the Hex-expressing cells of the AVE (Hex-AVE) by knocking the Diphtheria toxin subunit A into the Hex locus in an inducible manner. Using this model we have identified that, in addition to its requirement in the anterior of the embryo, the Hex-AVE sub-population has a novel role between 5.5 and 6.5dpc in patterning the primitive streak. Embryos lacking the Hex-AVE display delayed initiation of primitive streak formation and miss-patterning of the anterior primitive streak. We demonstrate that in the absence of the Hex-AVE the restriction of Bmp2 expression to the proximal visceral endoderm is also defective and expression of Wnt3 and Nodal is not correctly restricted to the posterior epiblast. These results, coupled with the observation that reducing Nodal signalling in Hex-AVE ablated embryos increases the frequency of phenotypes observed, suggests that these primitive streak patterning defects are due to defective Nodal signalling. Together, our experiments demonstrate that the AVE is not only required for anterior patterning, but also that specific sub-populations of this tissue are required to pattern the posterior of the embryo. PMID:21445260

[The cultural history of palliative care in primitive societies: an integrative review].

PubMed

Siles González, José; Solano Ruiz, Maria Del Carmen

2012-08-01

The objective of this study is to describe the evolution of palliative care in order to reflect on the possibility of its origin in primitive cultures and their relationship with the beginnings of the cult of the dead. It describes the change in the symbolic structures and social interactions involved in palliative care during prehistory: functional unit, functional framework and functional element. The theoretical framework is based on cultural history, the dialectical structural model and symbolic interactionism. Categorization techniques, cultural history and dialectic structuralism analyses were performed. Palliative care existed in primitive societies, mostly associated with the rites of passage with a high symbolic content. The social structures - functional unit, functional framework and functional element - are the pillars that supported palliative care in prehistory societies.

Lightweight causal and atomic group multicast

NASA Technical Reports Server (NTRS)

Birman, Kenneth P.; Schiper, Andre; Stephenson, Pat

1991-01-01

The ISIS toolkit is a distributed programming environment based on support for virtually synchronous process groups and group communication. A suite of protocols is presented to support this model. The approach revolves around a multicast primitive, called CBCAST, which implements a fault-tolerant, causally ordered message delivery. This primitive can be used directly or extended into a totally ordered multicast primitive, called ABCAST. It normally delivers messages immediately upon reception, and imposes a space overhead proportional to the size of the groups to which the sender belongs, usually a small number. It is concluded that process groups and group communication can achieve performance and scaling comparable to that of a raw message transport layer. This finding contradicts the widespread concern that this style of distributed computing may be unacceptably costly.

Predicting Coupled Ocean-Atmosphere Modes with a Climate Modeling Hierarchy -- Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael Ghil, UCLA; Andrew W. Robertson, IRI, Columbia Univ.; Sergey Kravtsov, U. of Wisconsin, Milwaukee

The goal of the project was to determine midlatitude climate predictability associated with tropical-extratropical interactions on interannual-to-interdecadal time scales. Our strategy was to develop and test a hierarchy of climate models, bringing together large GCM-based climate models with simple fluid-dynamical coupled ocean-ice-atmosphere models, through the use of advanced probabilistic network (PN) models. PN models were used to develop a new diagnostic methodology for analyzing coupled ocean-atmosphere interactions in large climate simulations made with the NCAR Parallel Climate Model (PCM), and to make these tools user-friendly and available to other researchers. We focused on interactions between the tropics and extratropics throughmore » atmospheric teleconnections (the Hadley cell, Rossby waves and nonlinear circulation regimes) over both the North Atlantic and North Pacific, and the ocean’s thermohaline circulation (THC) in the Atlantic. We tested the hypothesis that variations in the strength of the THC alter sea surface temperatures in the tropical Atlantic, and that the latter influence the atmosphere in high latitudes through an atmospheric teleconnection, feeding back onto the THC. The PN model framework was used to mediate between the understanding gained with simplified primitive equations models and multi-century simulations made with the PCM. The project team is interdisciplinary and built on an existing synergy between atmospheric and ocean scientists at UCLA, computer scientists at UCI, and climate researchers at the IRI.« less

A recursive vesicle-based model protocell with a primitive model cell cycle

NASA Astrophysics Data System (ADS)

Kurihara, Kensuke; Okura, Yusaku; Matsuo, Muneyuki; Toyota, Taro; Suzuki, Kentaro; Sugawara, Tadashi

2015-09-01

Self-organized lipid structures (protocells) have been proposed as an intermediate between nonliving material and cellular life. Synthetic production of model protocells can demonstrate the potential processes by which living cells first arose. While we have previously described a giant vesicle (GV)-based model protocell in which amplification of DNA was linked to self-reproduction, the ability of a protocell to recursively self-proliferate for multiple generations has not been demonstrated. Here we show that newborn daughter GVs can be restored to the status of their parental GVs by pH-induced vesicular fusion of daughter GVs with conveyer GVs filled with depleted substrates. We describe a primitive model cell cycle comprising four discrete phases (ingestion, replication, maturity and division), each of which is selectively activated by a specific external stimulus. The production of recursive self-proliferating model protocells represents a step towards eventual production of model protocells that are able to mimic evolution.

Recovery Schemes for Primitive Variables in General-relativistic Magnetohydrodynamics

NASA Astrophysics Data System (ADS)

Siegel, Daniel M.; Mösta, Philipp; Desai, Dhruv; Wu, Samantha

2018-05-01

General-relativistic magnetohydrodynamic (GRMHD) simulations are an important tool to study a variety of astrophysical systems such as neutron star mergers, core-collapse supernovae, and accretion onto compact objects. A conservative GRMHD scheme numerically evolves a set of conservation equations for “conserved” quantities and requires the computation of certain primitive variables at every time step. This recovery procedure constitutes a core part of any conservative GRMHD scheme and it is closely tied to the equation of state (EOS) of the fluid. In the quest to include nuclear physics, weak interactions, and neutrino physics, state-of-the-art GRMHD simulations employ finite-temperature, composition-dependent EOSs. While different schemes have individually been proposed, the recovery problem still remains a major source of error, failure, and inefficiency in GRMHD simulations with advanced microphysics. The strengths and weaknesses of the different schemes when compared to each other remain unclear. Here we present the first systematic comparison of various recovery schemes used in different dynamical spacetime GRMHD codes for both analytic and tabulated microphysical EOSs. We assess the schemes in terms of (i) speed, (ii) accuracy, and (iii) robustness. We find large variations among the different schemes and that there is not a single ideal scheme. While the computationally most efficient schemes are less robust, the most robust schemes are computationally less efficient. More robust schemes may require an order of magnitude more calls to the EOS, which are computationally expensive. We propose an optimal strategy of an efficient three-dimensional Newton–Raphson scheme and a slower but more robust one-dimensional scheme as a fall-back.

A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Coirier, William J.; Powell, Kenneth G.

1994-01-01

A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations in two dimensions is developed and tested. Grids about geometrically complicated bodies are generated automatically, by recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, N-sided 'cut' cells are created using polygon-clipping algorithms. The grid is stored in a binary-tree structure which provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite-volume formulation. The convective terms are upwinded: a gradient-limited, linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The more robust of a series of viscous flux functions is used to provide the viscous fluxes at the cell interfaces. Adaptively-refined solutions of the Navier-Stokes equations using the Cartesian, cell-based approach are obtained and compared to theory, experiment, and other accepted computational results for a series of low and moderate Reynolds number flows.

A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Coirier, William J.; Powell, Kenneth G.

1995-01-01

A Cartesian, cell-based approach for adaptively-refined solutions of the Euler and Navier-Stokes equations in two dimensions is developed and tested. Grids about geometrically complicated bodies are generated automatically, by recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, N-sided 'cut' cells are created using polygon-clipping algorithms. The grid is stored in a binary-tree data structure which provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite-volume formulation. The convective terms are upwinded: A gradient-limited, linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The more robust of a series of viscous flux functions is used to provide the viscous fluxes at the cell interfaces. Adaptively-refined solutions of the Navier-Stokes equations using the Cartesian, cell-based approach are obtained and compared to theory, experiment and other accepted computational results for a series of low and moderate Reynolds number flows.

Photovoltaic panel extraction from very high-resolution aerial imagery using region-line primitive association analysis and template matching

NASA Astrophysics Data System (ADS)

Wang, Min; Cui, Qi; Sun, Yujie; Wang, Qiao

2018-07-01

In object-based image analysis (OBIA), object classification performance is jointly determined by image segmentation, sample or rule setting, and classifiers. Typically, as a crucial step to obtain object primitives, image segmentation quality significantly influences subsequent feature extraction and analyses. By contrast, template matching extracts specific objects from images and prevents shape defects caused by image segmentation. However, creating or editing templates is tedious and sometimes results in incomplete or inaccurate templates. In this study, we combine OBIA and template matching techniques to address these problems and aim for accurate photovoltaic panel (PVP) extraction from very high-resolution (VHR) aerial imagery. The proposed method is based on the previously proposed region-line primitive association framework, in which complementary information between region (segment) and line (straight line) primitives is utilized to achieve a more powerful performance than routine OBIA. Several novel concepts, including the mutual fitting ratio and best-fitting template based on region-line primitive association analyses, are proposed. Automatic template generation and matching method for PVP extraction from VHR imagery are designed for concept and model validation. Results show that the proposed method can successfully extract PVPs without any user-specified matching template or training sample. High user independency and accuracy are the main characteristics of the proposed method in comparison with routine OBIA and template matching techniques.

Whole-Body Radiation Therapy, Systemic Chemotherapy, and High-Dose Chemotherapy Followed By Stem Cell Rescue in Treating Patients With Poor-Risk Ewing Sarcoma

ClinicalTrials.gov

2015-01-07

Adult Supratentorial Primitive Neuroectodermal Tumor (PNET); Ewing Sarcoma of Bone; Extraosseous Ewing Sarcoma; Metastatic Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Recurrent Childhood Supratentorial Primitive Neuroectodermal Tumor; Recurrent Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Untreated Childhood Supratentorial Primitive Neuroectodermal Tumor

Direct volumetric rendering based on point primitives in OpenGL.

PubMed

da Rosa, André Luiz Miranda; de Almeida Souza, Ilana; Yuuji Hira, Adilson; Zuffo, Marcelo Knörich

2006-01-01

The aim of this project is to present a renderization by software algorithm of acquired volumetric data. The algorithm was implemented in Java language and the LWJGL graphical library was used, allowing the volume renderization by software and thus preventing the necessity to acquire specific graphical boards for the 3D reconstruction. The considered algorithm creates a model in OpenGL, through point primitives, where each voxel becomes a point with the color values related to this pixel position in the corresponding images.

Macroscopic Modeling of a One-Dimensional Electrochemical Cell using the Poisson-Nernst-Planck Equations

NASA Astrophysics Data System (ADS)

Yan, David

This thesis presents the one-dimensional equations, numerical method and simulations of a model to characterize the dynamical operation of an electrochemical cell. This model extends the current state-of-the art in that it accounts, in a primitive way, for the physics of the electrolyte/electrode interface and incorporates diffuse-charge dynamics, temperature coupling, surface coverage, and polarization phenomena. The one-dimensional equations account for a system with one or two mobile ions of opposite charge, and the electrode reaction we consider (when one is needed) is a one-electron electrodeposition reaction. Though the modeled system is far from representing a realistic electrochemical device, our results show a range of dynamics and behaviors which have not been observed previously, and explore the numerical challenges required when adding more complexity to a model. Furthermore, the basic transport equations (which are developed in three spatial dimensions) can in future accomodate the inclusion of additional physics, and coupling to more complex boundary conditions that incorporate two-dimensional surface phenomena and multi-rate reactions. In the model, the Poisson-Nernst-Planck equations are used to model diffusion and electromigration in an electrolyte, and the generalized Frumkin-Butler-Volmer equation is used to model reaction kinetics at electrodes. An energy balance equation is derived and coupled to the diffusion-migration equation. The model also includes dielectric polarization effects by introducing different values of the dielectric permittivity in different regions of the bulk, as well as accounting for surface coverage effects due to adsorption, and finite size "crowding", or steric effects. Advection effects are not modeled but could in future be incorporated. In order to solve the coupled PDE's, we use a variable step size second order scheme in time and finite differencing in space. Numerical tests are performed on a simplified system and the scheme's stability and convergence properties are discussed. While evaluating different methods for discretizing the coupled flux boundary condition, we discover a thresholding behaviour in the adaptive time stepper, and perform additional tests to investigate it. Finally, a method based on ghost points is chosen for its favorable numerical properties compared to the alternatives. With this method, we are able to run simulations with a large range of parameters, including any value of the nondimensionalized Debye length epsilon. The numerical code is first used to run simulations to explore the effects of polarization, surface coverage, and temperature. The code is also used to perform frequency sweeps of input signals in order to mimic impedance spectroscopy experiments. Finally, in Chapter 5, we use our model to apply ramped voltages to electrochemical systems, and show theoretical and simulated current-voltage curves for liquid and solid thin films, cells with blocking (polarized) electrodes, and electrolytes with background charge. Linear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. No general theory of linear-sweep voltammetry is available, however, for unsupported electrolytes and for other situations where diffuse charge effects play a role. We show theoretical and simulated current-voltage curves for liquid and solid thin films, cells with blocking electrodes, and membranes with fixed background charge. The analysis focuses on the coupling of Faradaic reactions and diffuse charge dynamics, but capacitive charging of the double layers is also studied, for early time transients at reactive electrodes and for non-reactive blocking electrodes. The final chapter highlights the role of diffuse charge in the context of voltammetry, and illustrates which regimes can be approximated using simple analytical expressions and which require more careful consideration.

Do plumes exist beneath Northwest Kyushu southwest Japan?

NASA Astrophysics Data System (ADS)

Mashima, H.

2014-12-01

A thermal plume model was proposed for the Hot-spot type volcanism at Northwest Kyushu, southwest Japan in the post period of opening of the Sea of Japan. The model regards the Northwest Kyushu Basalts (NWKBs) were magmas fractionated from parental magmas with MgO = 12.8 - 18.8 wt. %, indicating that partial melting occurred at temperatures from 1330 to 1500 °C and at pressures from 1.5 to 3.0 GPa (Sakuyama et al., 2009; 2014). Previous petrological and observations, however, indicate that the NWKBs separated from the source mantle at pressures shallower than those inferred from the plume model. The Mg-Fe-Ni compositions of some NWKBs suggest that they could have been in equilibrium with mantle olivines with Fo = 81 - 87, meaning that they would have been not fractionated but primitive magmas. The NWKBs are associated with primitive high magnesium andesites, indicating that partial melting continued at low pressure such as 0.5 GPa (Mashima, 2009a, b). NWKBs include not garnet lherzolite xenoliths but spinel lherzolite, showing that primitive melt separation occurred at pressure lower than 2GPa (Arai et al., 2001). These lines of evidence indicate that the separation of primitive NWKBs occurred at temperature up to 1250　°C and pressures from 0.5 to 1.5 GPa, significantly lower than those assumed by the plume model. Instead of the plume model, geology of NW Kyushu infers that the volcanism was a consequence of the tectonic evolution of NW Kyushu. The volcanism was leaks of asthenosphere thickened extensional tectonics from the Paleogene to the early Miocene. Orientations of NWKB dikes indicate their eruption was induced by the reactivation of preexisting faults under horizontal compressive stress field oriented to a NW-SE direction. This　horizontally compressive stress field would have been caused by mechanical interactions between the subducting Philippine Sea pate and the Eurasian Plate. The NW Kyushu volcanism could be explained in the context of plate tectonics without the plume hypothesis.

Secure Heterogeneous Multicore Platform Through Diversity and Redundancy

DTIC Science & Technology

2012-03-31

implementation detects synchronization in this way. If a programmer uses custom synchronization primitives , our approach assumes that such primitives ... synchronization primitives . Primitives such as barriers and spinlocks explicitly enforce a pre- determined ordering among threads. Therefore, the outcome of...these synchronization operations are deterministic. In the discussion, we will refer to these primitives as ordering synchronization operations. On the

A non-local model of fractional heat conduction in rigid bodies

NASA Astrophysics Data System (ADS)

Borino, G.; di Paola, M.; Zingales, M.

2011-03-01

In recent years several applications of fractional differential calculus have been proposed in physics, chemistry as well as in engineering fields. Fractional order integrals and derivatives extend the well-known definitions of integer-order primitives and derivatives of the ordinary differential calculus to real-order operators. Engineering applications of fractional operators spread from viscoelastic models, stochastic dynamics as well as with thermoelasticity. In this latter field one of the main actractives of fractional operators is their capability to interpolate between the heat flux and its time-rate of change, that is related to the well-known second sound effect. In other recent studies a fractional, non-local thermoelastic model has been proposed as a particular case of the non-local, integral, thermoelasticity introduced at the mid of the seventies. In this study the autors aim to introduce a different non-local model of extended irreverible thermodynamics to account for second sound effect. Long-range heat flux is defined and it involves the integral part of the spatial Marchaud fractional derivatives of the temperature field whereas the second-sound effect is accounted for introducing time-derivative of the heat flux in the transport equation. It is shown that the proposed model does not suffer of the pathological problems of non-homogenoeus boundary conditions. Moreover the proposed model coalesces with the Povstenko fractional models in unbounded domains.

Quantization and Quantum-Like Phenomena: A Number Amplitude Approach

NASA Astrophysics Data System (ADS)

Robinson, T. R.; Haven, E.

2015-12-01

Historically, quantization has meant turning the dynamical variables of classical mechanics that are represented by numbers into their corresponding operators. Thus the relationships between classical variables determine the relationships between the corresponding quantum mechanical operators. Here, we take a radically different approach to this conventional quantization procedure. Our approach does not rely on any relations based on classical Hamiltonian or Lagrangian mechanics nor on any canonical quantization relations, nor even on any preconceptions of particle trajectories in space and time. Instead we examine the symmetry properties of certain Hermitian operators with respect to phase changes. This introduces harmonic operators that can be identified with a variety of cyclic systems, from clocks to quantum fields. These operators are shown to have the characteristics of creation and annihilation operators that constitute the primitive fields of quantum field theory. Such an approach not only allows us to recover the Hamiltonian equations of classical mechanics and the Schrödinger wave equation from the fundamental quantization relations, but also, by freeing the quantum formalism from any physical connotation, makes it more directly applicable to non-physical, so-called quantum-like systems. Over the past decade or so, there has been a rapid growth of interest in such applications. These include, the use of the Schrödinger equation in finance, second quantization and the number operator in social interactions, population dynamics and financial trading, and quantum probability models in cognitive processes and decision-making. In this paper we try to look beyond physical analogies to provide a foundational underpinning of such applications.

Two-dimensional CFD modeling of wave rotor flow dynamics

NASA Technical Reports Server (NTRS)

Welch, Gerard E.; Chima, Rodrick V.

1994-01-01

A two-dimensional Navier-Stokes solver developed for detailed study of wave rotor flow dynamics is described. The CFD model is helping characterize important loss mechanisms within the wave rotor. The wave rotor stationary ports and the moving rotor passages are resolved on multiple computational grid blocks. The finite-volume form of the thin-layer Navier-Stokes equations with laminar viscosity are integrated in time using a four-stage Runge-Kutta scheme. Roe's approximate Riemann solution scheme or the computationally less expensive advection upstream splitting method (AUSM) flux-splitting scheme is used to effect upwind-differencing of the inviscid flux terms, using cell interface primitive variables set by MUSCL-type interpolation. The diffusion terms are central-differenced. The solver is validated using a steady shock/laminar boundary layer interaction problem and an unsteady, inviscid wave rotor passage gradual opening problem. A model inlet port/passage charging problem is simulated and key features of the unsteady wave rotor flow field are identified. Lastly, the medium pressure inlet port and high pressure outlet port portion of the NASA Lewis Research Center experimental divider cycle is simulated and computed results are compared with experimental measurements. The model accurately predicts the wave timing within the rotor passages and the distribution of flow variables in the stationary inlet port region.

Two-dimensional CFD modeling of wave rotor flow dynamics

NASA Technical Reports Server (NTRS)

Welch, Gerard E.; Chima, Rodrick V.

1993-01-01

A two-dimensional Navier-Stokes solver developed for detailed study of wave rotor flow dynamics is described. The CFD model is helping characterize important loss mechanisms within the wave rotor. The wave rotor stationary ports and the moving rotor passages are resolved on multiple computational grid blocks. The finite-volume form of the thin-layer Navier-Stokes equations with laminar viscosity are integrated in time using a four-stage Runge-Kutta scheme. The Roe approximate Riemann solution scheme or the computationally less expensive Advection Upstream Splitting Method (AUSM) flux-splitting scheme are used to effect upwind-differencing of the inviscid flux terms, using cell interface primitive variables set by MUSCL-type interpolation. The diffusion terms are central-differenced. The solver is validated using a steady shock/laminar boundary layer interaction problem and an unsteady, inviscid wave rotor passage gradual opening problem. A model inlet port/passage charging problem is simulated and key features of the unsteady wave rotor flow field are identified. Lastly, the medium pressure inlet port and high pressure outlet port portion of the NASA Lewis Research Center experimental divider cycle is simulated and computed results are compared with experimental measurements. The model accurately predicts the wave timing within the rotor passage and the distribution of flow variables in the stationary inlet port region.

Observations and Numerical Modeling of Eddy Generation in the Mediterranean Undercurrent

NASA Astrophysics Data System (ADS)

Serra, N.; Ambar, I.; Kaese, R.

2001-12-01

In the frame of the European Union MAST III project CANIGO (Canary Islands Gibraltar Azores Observations), RAFOS floats were deployed in the Mediterranean undercurrent off south Portugal during the period from September 1997 to September 1998. An analysis of this Lagrangian approach complemented with results obtained with XBT probes and current meter data from the same project shows some of the major aspects of the flow associated with the undercurrent as well as the eddy activity related with it. Floats that stayed in the undercurrent featured a downstream deceleration and a steering by bottom topography. Three meddy formations at Cape St. Vincent could be isolated from the float data as well as the generation of dipolar structures in the Portimao Canyon, a feature not previously directly observed. The dynamical coupling of meddies and cyclones was observed for a considerable period of time. High-resolution modeling of the Mediterranean Outflow using a sigma-coordinate primitive equations ocean model (SCRUM) incorporating realistic topography and stratification reveals the adjustment of the salty plume while descending along the continental slope of the Gulf of Cadiz channeled by the topography. The model reproduces the generation of eddies in the two observed sites (cape and canyon) and the splitting of the outflow water into well-defined cores.

Distinguishing synchronous and time-varying synergies using point process interval statistics: motor primitives in frog and rat

PubMed Central

Hart, Corey B.; Giszter, Simon F.

2013-01-01

We present and apply a method that uses point process statistics to discriminate the forms of synergies in motor pattern data, prior to explicit synergy extraction. The method uses electromyogram (EMG) pulse peak timing or onset timing. Peak timing is preferable in complex patterns where pulse onsets may be overlapping. An interval statistic derived from the point processes of EMG peak timings distinguishes time-varying synergies from synchronous synergies (SS). Model data shows that the statistic is robust for most conditions. Its application to both frog hindlimb EMG and rat locomotion hindlimb EMG show data from these preparations is clearly most consistent with synchronous synergy models (p < 0.001). Additional direct tests of pulse and interval relations in frog data further bolster the support for synchronous synergy mechanisms in these data. Our method and analyses support separated control of rhythm and pattern of motor primitives, with the low level execution primitives comprising pulsed SS in both frog and rat, and both episodic and rhythmic behaviors. PMID:23675341

Attributed relational graphs for cell nucleus segmentation in fluorescence microscopy images.

PubMed

Arslan, Salim; Ersahin, Tulin; Cetin-Atalay, Rengul; Gunduz-Demir, Cigdem

2013-06-01

More rapid and accurate high-throughput screening in molecular cellular biology research has become possible with the development of automated microscopy imaging, for which cell nucleus segmentation commonly constitutes the core step. Although several promising methods exist for segmenting the nuclei of monolayer isolated and less-confluent cells, it still remains an open problem to segment the nuclei of more-confluent cells, which tend to grow in overlayers. To address this problem, we propose a new model-based nucleus segmentation algorithm. This algorithm models how a human locates a nucleus by identifying the nucleus boundaries and piecing them together. In this algorithm, we define four types of primitives to represent nucleus boundaries at different orientations and construct an attributed relational graph on the primitives to represent their spatial relations. Then, we reduce the nucleus identification problem to finding predefined structural patterns in the constructed graph and also use the primitives in region growing to delineate the nucleus borders. Working with fluorescence microscopy images, our experiments demonstrate that the proposed algorithm identifies nuclei better than previous nucleus segmentation algorithms.

New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications

NASA Astrophysics Data System (ADS)

Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

2016-05-01

Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

A sigma-coordinate primitive equation model for studying the circulation in the South Atlantic Part II: Meridional transports and seasonal variability

NASA Astrophysics Data System (ADS)

Marchesiello, P.; Barnier, B.; de Miranda, A. P.

1998-04-01

The mean and seasonal variability of the circulation and meridional heat transport in the South Atlantic are investigated using a set of numerical experiments. The primitive equation model uses a topography-following (sigma) coordinate. The model domain is limited to the South Atlantic basin. Artificial boundaries at Drake Passage, between Brazil and Angola, and between South Africa and Antarctica are treated as open boundaries. Finally, recent and self-consistent estimates of seasonal fluxes are used to define a model-dependent atmospheric forcing. Quasi-diagnostic simulations forced by constant climatological winds are first conducted to determine the sensitivity of model solutions to bottom topography smoothing, and to diagnose meridional fluxes from a mass field that is relaxed to the annual climatology of Levitus (1982). Model results show good agreement with known climatological circulation features in this basin, especially in the Confluence Region, where coarse resolution models usually give smooth structures. Sensitivity studies show that the more detailed features of the circulation are influenced by the model bathymetry. The model simulates a meridional circulation whose upper branch (the return flow that balances the southward flow of North Atlantic Deep Water) is composed of Intermediate (IW) and Thermocline (TW) Waters. The transport of IW is found to be predominant, and the value of meridional heat transport consequently falls within the low estimates. We notice that the meridional heat balance is sensitive to the position of the Confluence. When this region occurs too far south, the amount of IW contributing to the return flow of the overturning cell is reduced. Prognostic simulations forced by seasonal winds and heat fluxes are studied to quantify the impact of wind forcing on the circulation in the South Atlantic. Particular attention is focused on meridional transports at 30°S. Analysis of the mean annual circulation confirms that the upper branch of the meridional circulation is predominantly composed of IW (9 Sv), rather than TW (5.3 Sv). The mean transport of the lower branch is 16 Sv, in agreement with recent estimates by Schlitzer (1996). The annual meridional heat transport (0.29 PW) is still within the low estimates, but agrees well with other estimates that give a dominant role to IW (Rintoul, 1991). Original results also concern the variability of the upper branch of the meridional circulation. It is shown that the wind creates seasonal variability in the Subtropical Gyre, which has a marked impact on the water mass balance in the South Atlantic. In winter, a large convergence to the north of the Subtropical Gyre (27°S) reduces the northward flow of IW, whereas stronger Ekman pumping favors an equatorward transport of TW. In summer, this convergence disappears and a larger transport of IW is allowed. Thus a more complex scheme is proposed for the meridional circulation, in which local wind forcing in the South Atlantic Basin has a significant role in preconditioning the surface waters of the global overturning cell.

Quantitative descriptions of generalized arousal, an elementary function of the vertebrate brain

PubMed Central

Quinkert, Amy Wells; Vimal, Vivek; Weil, Zachary M.; Reeke, George N.; Schiff, Nicholas D.; Banavar, Jayanth R.; Pfaff, Donald W.

2011-01-01

We review a concept of the most primitive, fundamental function of the vertebrate CNS, generalized arousal (GA). Three independent lines of evidence indicate the existence of GA: statistical, genetic, and mechanistic. Here we ask, is this concept amenable to quantitative analysis? Answering in the affirmative, four quantitative approaches have proven useful: (i) factor analysis, (ii) information theory, (iii) deterministic chaos, and (iv) application of a Gaussian equation. It strikes us that, to date, not just one but at least four different quantitative approaches seem necessary for describing different aspects of scientific work on GA. PMID:21555568

Finite element analysis of inviscid subsonic boattail flow

NASA Technical Reports Server (NTRS)

Chima, R. V.; Gerhart, P. M.

1981-01-01

A finite element code for analysis of inviscid subsonic flows over arbitrary nonlifting planar or axisymmetric bodies is described. The code solves a novel primitive variable formulation of the coupled irrotationality and compressible continuity equations. Results for flow over a cylinder, a sphere, and a NACA 0012 airfoil verify the code. Computed subcritical flows over an axisymmetric boattailed afterbody compare well with finite difference results and experimental data. Interative coupling with an integral turbulent boundary layer code shows strong viscous effects on the inviscid flow. Improvements in code efficiency and extensions to transonic flows are discussed.

Cartographic Modeling: Computer-assisted Analysis of Spatially Defined Neighborhoods

NASA Technical Reports Server (NTRS)

Berry, J. K.; Tomlin, C. D.

1982-01-01

Cartographic models addressing a wide variety of applications are composed of fundamental map processing operations. These primitive operations are neither data base nor application-specific. By organizing the set of operations into a mathematical-like structure, the basis for a generalized cartographic modeling framework can be developed. Among the major classes of primitive operations are those associated with reclassifying map categories, overlaying maps, determining distance and connectivity, and characterizing cartographic neighborhoods. The conceptual framework of cartographic modeling is established and techniques for characterizing neighborhoods are used as a means of demonstrating some of the more sophisticated procedures of computer-assisted map analysis. A cartographic model for assessing effective roundwood supply is briefly described as an example of a computer analysis. Most of the techniques described have been implemented as part of the map analysis package developed at the Yale School of Forestry and Environmental Studies.

Versatility of `hemorheologic fitness' according to exercise intensity: emphasis on the "healthy primitive lifestyle"

NASA Astrophysics Data System (ADS)

Brun, Jean-Frédéric; Varlet-Marie, Emmanuelle; Chevance, Guillaume; Pollatz, Marion; Fedou, Christine; de Mauverger, Eric Raynaud

2014-05-01

We recently proposed a unifying hypothesis to reconcile unexpected findings in exercise hemorheology and the classical concepts of "hemorheologic fitness" and the "triphasic effects of exercise", based on the "healthy primitive lifestyle" paradigm. This paradigm assumes that evolution has selected genetic polymorphisms leading to insulin resistance as an adaptative strategy to cope with continuous low intensity physical activity and a special alimentation moderately high in protein, rich in low glycemic index carbohydrates, and poor in saturated fat. According to this protocol the true physiological picture would be that of an individual whose exercise and nutritional habits are close from this lifestyle, both sedentary subjects and trained athletes representing situations on the edge of this model. Unfortunately samples of people truly adhering to this ancestral lifestyle are hard to obtain. In order to address this picture we tried to compare databases obtained with our preceding published studies. As a model of the "healthy primitive lifestyle" we selected patients trained at low intensity (LI) and given an advice of protein intake around 1.2 g/kg/day. Results show a continuum for plasma viscosity which seems to be lower in athletes than LI-trained and even more sedentaries. When sedentary subjects become obese the most obvious characteristic is an increase in red blood cell (RBC) aggregation correlated to the size of fat stores. It is clear that 3 months of LI are not a perfect model of "healthy primitive lifestyle", but these data suggest that the most important effect of LI regular exercise is to decrease plasma viscosity and that sedentarity increases RBC aggregation mostly when it results in increased fat storage.

Construction of a magnetostrictive hysteresis operator using a tripod-like primitive hopfield neural network

NASA Astrophysics Data System (ADS)

Adly, A. A.; Abd-El-Hafiz, S. K.

2018-05-01

It is well known that accurate modeling of magnetostrictive hysteresis is crucial to different industrial applications. Although several magnetostrictive models have been developed in the past, the accuracy-efficiency balance has always been crucial. Recently, the possibility of constructing a primitive vector hysteresis operator using a tri-node Hopfield Neural Network (HNN) was demonstrated. Based upon the fact that mechanical stress along a certain direction results in dimensional deformation, this paper introduces a novel extension to the aforementioned recently developed approach. More specifically, a stress-driven evolution of a tri-node HNN hysteresis operator pair is proposed, thus yielding a tripod-like HNN pair having different input offset values. Model identification, sample simulation results and comparison with experimental measurements are given in the paper.

Three-Dimensional Navier-Stokes Method with Two-Equation Turbulence Models for Efficient Numerical Simulation of Hypersonic Flows

NASA Technical Reports Server (NTRS)

Bardina, J. E.

1994-01-01

A new computational efficient 3-D compressible Reynolds-averaged implicit Navier-Stokes method with advanced two equation turbulence models for high speed flows is presented. All convective terms are modeled using an entropy satisfying higher-order Total Variation Diminishing (TVD) scheme based on implicit upwind flux-difference split approximations and arithmetic averaging procedure of primitive variables. This method combines the best features of data management and computational efficiency of space marching procedures with the generality and stability of time dependent Navier-Stokes procedures to solve flows with mixed supersonic and subsonic zones, including streamwise separated flows. Its robust stability derives from a combination of conservative implicit upwind flux-difference splitting with Roe's property U to provide accurate shock capturing capability that non-conservative schemes do not guarantee, alternating symmetric Gauss-Seidel 'method of planes' relaxation procedure coupled with a three-dimensional two-factor diagonal-dominant approximate factorization scheme, TVD flux limiters of higher-order flux differences satisfying realizability, and well-posed characteristic-based implicit boundary-point a'pproximations consistent with the local characteristics domain of dependence. The efficiency of the method is highly increased with Newton Raphson acceleration which allows convergence in essentially one forward sweep for supersonic flows. The method is verified by comparing with experiment and other Navier-Stokes methods. Here, results of adiabatic and cooled flat plate flows, compression corner flow, and 3-D hypersonic shock-wave/turbulent boundary layer interaction flows are presented. The robust 3-D method achieves a better computational efficiency of at least one order of magnitude over the CNS Navier-Stokes code. It provides cost-effective aerodynamic predictions in agreement with experiment, and the capability of predicting complex flow structures in complex geometries with good accuracy.

A study of the control problem of the shoot side environment delivery system of a closed crop growth research chamber

NASA Technical Reports Server (NTRS)

Blackwell, C. C.; Blackwell, A. L.

1992-01-01

The details of our initial study of the control problem of the crop shoot environment of a hypothetical closed crop growth research chamber (CGRC) are presented in this report. The configuration of the CGRC is hypothetical because neither a physical subject nor a design existed at the time the study began, a circumstance which is typical of large scale systems control studies. The basis of the control study is a mathematical model which was judged to adequately mimic the relevant dynamics of the system components considered necessary to provide acceptable realism in the representation. Control of pressure, temperature, and flow rate of the crop shoot environment, along with its oxygen, carbon dioxide, and water concentration is addressed. To account for mass exchange, the group of plants is represented in the model by a source of oxygen, a source of water vapor, and a sink for carbon dioxide. In terms of the thermal energy exchange, the group of plants is represented by a surface with an appropriate temperature. Most of the primitive equations about an experimental operating condition and a state variable representation which was extracted from the linearized equations are presented. Next, we present the results of a real Jordan decomposition and the repositioning of an undesirable eigenvalue via full state feedback. The state variable representation of the modeling system is of the nineteenth order and reflects the eleven control variables and eight system disturbances. Five real eigenvalues are very near zero, with one at zero, three having small magnitude positive values, and one having a small magnitude negative value. A Singular Value Decomposition analysis indicates that these non-zero eigenvalues are not results of numerical error.

Dynamic Primitives of Motor Behavior

PubMed Central

Hogan, Neville; Sternad, Dagmar

2013-01-01

We present in outline a theory of sensorimotor control based on dynamic primitives, which we define as attractors. To account for the broad class of human interactive behaviors—especially tool use—we propose three distinct primitives: submovements, oscillations and mechanical impedances, the latter necessary for interaction with objects. Due to fundamental features of the neuromuscular system, most notably its slow response, we argue that encoding in terms of parameterized primitives may be an essential simplification required for learning, performance, and retention of complex skills. Primitives may simultaneously and sequentially be combined to produce observable forces and motions. This may be achieved by defining a virtual trajectory composed of submovements and/or oscillations interacting with impedances. Identifying primitives requires care: in principle, overlapping submovements would be sufficient to compose all observed movements but biological evidence shows that oscillations are a distinct primitive. Conversely, we suggest that kinematic synergies, frequently discussed as primitives of complex actions, may be an emergent consequence of neuromuscular impedance. To illustrate how these dynamic primitives may account for complex actions, we briefly review three types of interactive behaviors: constrained motion, impact tasks, and manipulation of dynamic objects. PMID:23124919

Free energy and phase equilibria for the restricted primitive model of ionic fluids from Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Orkoulas, Gerassimos; Panagiotopoulos, Athanassios Z.

1994-07-01

In this work, we investigate the liquid-vapor phase transition of the restricted primitive model of ionic fluids. We show that at the low temperatures where the phase transition occurs, the system cannot be studied by conventional molecular simulation methods because convergence to equilibrium is slow. To accelerate convergence, we propose cluster Monte Carlo moves capable of moving more than one particle at a time. We then address the issue of charged particle transfers in grand canonical and Gibbs ensemble Monte Carlo simulations, for which we propose a biased particle insertion/destruction scheme capable of sampling short interparticle distances. We compute the chemical potential for the restricted primitive model as a function of temperature and density from grand canonical Monte Carlo simulations and the phase envelope from Gibbs Monte Carlo simulations. Our calculated phase coexistence curve is in agreement with recent results of Caillol obtained on the four-dimensional hypersphere and our own earlier Gibbs ensemble simulations with single-ion transfers, with the exception of the critical temperature, which is lower in the current calculations. Our best estimates for the critical parameters are T*c=0.053, ρ*c=0.025. We conclude with possible future applications of the biased techniques developed here for phase equilibrium calculations for ionic fluids.

Discovering motion primitives for unsupervised grouping and one-shot learning of human actions, gestures, and expressions.

PubMed

Yang, Yang; Saleemi, Imran; Shah, Mubarak

2013-07-01

This paper proposes a novel representation of articulated human actions and gestures and facial expressions. The main goals of the proposed approach are: 1) to enable recognition using very few examples, i.e., one or k-shot learning, and 2) meaningful organization of unlabeled datasets by unsupervised clustering. Our proposed representation is obtained by automatically discovering high-level subactions or motion primitives, by hierarchical clustering of observed optical flow in four-dimensional, spatial, and motion flow space. The completely unsupervised proposed method, in contrast to state-of-the-art representations like bag of video words, provides a meaningful representation conducive to visual interpretation and textual labeling. Each primitive action depicts an atomic subaction, like directional motion of limb or torso, and is represented by a mixture of four-dimensional Gaussian distributions. For one--shot and k-shot learning, the sequence of primitive labels discovered in a test video are labeled using KL divergence, and can then be represented as a string and matched against similar strings of training videos. The same sequence can also be collapsed into a histogram of primitives or be used to learn a Hidden Markov model to represent classes. We have performed extensive experiments on recognition by one and k-shot learning as well as unsupervised action clustering on six human actions and gesture datasets, a composite dataset, and a database of facial expressions. These experiments confirm the validity and discriminative nature of the proposed representation.

The space-time solution element method: A new numerical approach for the Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Scott, James R.; Chang, Sin-Chung

1995-01-01

This paper is one of a series of papers describing the development of a new numerical method for the Navier-Stokes equations. Unlike conventional numerical methods, the current method concentrates on the discrete simulation of both the integral and differential forms of the Navier-Stokes equations. Conservation of mass, momentum, and energy in space-time is explicitly provided for through a rigorous enforcement of both the integral and differential forms of the governing conservation laws. Using local polynomial expansions to represent the discrete primitive variables on each cell, fluxes at cell interfaces are evaluated and balanced using exact functional expressions. No interpolation or flux limiters are required. Because of the generality of the current method, it applies equally to the steady and unsteady Navier-Stokes equations. In this paper, we generalize and extend the authors' 2-D, steady state implicit scheme. A general closure methodology is presented so that all terms up through a given order in the local expansions may be retained. The scheme is also extended to nonorthogonal Cartesian grids. Numerous flow fields are computed and results are compared with known solutions. The high accuracy of the scheme is demonstrated through its ability to accurately resolve developing boundary layers on coarse grids. Finally, we discuss applications of the current method to the unsteady Navier-Stokes equations.

A real-time robot arm collision avoidance system

NASA Technical Reports Server (NTRS)

Shaffer, Clifford A.; Herb, Gregory M.

1992-01-01

A data structure and update algorithm are presented for a prototype real-time collision avoidance safety system simulating a multirobot workspace. The data structure is a variant of the octree, which serves as a spatial index. An octree recursively decomposes 3D space into eight equal cubic octants until each octant meets some decomposition criteria. The N-objects octree, which indexes a collection of 3D primitive solids is used. These primitives make up the two (seven-degrees-of-freedom) robot arms and workspace modeled by the system. As robot arms move, the octree is updated to reflect their changed positions. During most update cycles, any given primitive does not change which octree nodes it is in. Thus, modification to the octree is rarely required. Cycle time for interpreting current arm joint angles, updating the octree to reflect new positions, and detecting/reporting imminent collisions averages 30 ms on an Intel 80386 processor running at 20 MHz.

A recursive vesicle-based model protocell with a primitive model cell cycle

PubMed Central

Kurihara, Kensuke; Okura, Yusaku; Matsuo, Muneyuki; Toyota, Taro; Suzuki, Kentaro; Sugawara, Tadashi

2015-01-01

Self-organized lipid structures (protocells) have been proposed as an intermediate between nonliving material and cellular life. Synthetic production of model protocells can demonstrate the potential processes by which living cells first arose. While we have previously described a giant vesicle (GV)-based model protocell in which amplification of DNA was linked to self-reproduction, the ability of a protocell to recursively self-proliferate for multiple generations has not been demonstrated. Here we show that newborn daughter GVs can be restored to the status of their parental GVs by pH-induced vesicular fusion of daughter GVs with conveyer GVs filled with depleted substrates. We describe a primitive model cell cycle comprising four discrete phases (ingestion, replication, maturity and division), each of which is selectively activated by a specific external stimulus. The production of recursive self-proliferating model protocells represents a step towards eventual production of model protocells that are able to mimic evolution. PMID:26418735

Element Mapping in Anhydrous IDPs: Identification of the Host Phases of Major/Minor Elements as a Test of Nebula Condensation Models

NASA Technical Reports Server (NTRS)

Flynn, G. J.; Keller, L. P.; Wirick, S.; Jacobsen, C.

2004-01-01

Many anhydrous interplanetary dust particles (IDPs) are the most pristine samples of primitive solar system dust currently available for laboratory analysis. Their primitive nature is demonstrated by: 1) the high content of moderately volatile elements, indicating they have not been heated significantly since formation, 2) the absence of hydrated material, indicating they never experienced aqueous processing, 3) the presence of unequilibrated mineral assemblages, 4) the presence of large isotopic anomalies (e.g., D and 15N enrichment), in these IDPs.

A two-level generative model for cloth representation and shape from shading.

PubMed

Han, Feng; Zhu, Song-Chun

2007-07-01

In this paper, we present a two-level generative model for representing the images and surface depth maps of drapery and clothes. The upper level consists of a number of folds which will generate the high contrast (ridge) areas with a dictionary of shading primitives (for 2D images) and fold primitives (for 3D depth maps). These primitives are represented in parametric forms and are learned in a supervised learning phase using 3D surfaces of clothes acquired through photometric stereo. The lower level consists of the remaining flat areas which fill between the folds with a smoothness prior (Markov random field). We show that the classical ill-posed problem-shape from shading (SFS) can be much improved by this two-level model for its reduced dimensionality and incorporation of middle-level visual knowledge, i.e., the dictionary of primitives. Given an input image, we first infer the folds and compute a sketch graph using a sketch pursuit algorithm as in the primal sketch [10], [11]. The 3D folds are estimated by parameter fitting using the fold dictionary and they form the "skeleton" of the drapery/cloth surfaces. Then, the lower level is computed by conventional SFS method using the fold areas as boundary conditions. The two levels interact at the final stage by optimizing a joint Bayesian posterior probability on the depth map. We show a number of experiments which demonstrate more robust results in comparison with state-of-the-art work. In a broader scope, our representation can be viewed as a two-level inhomogeneous MRF model which is applicable to general shape-from-X problems. Our study is an attempt to revisit Marr's idea [23] of computing the 2(1/2)D sketch from primal sketch. In a companion paper [2], we study shape from stereo based on a similar two-level generative sketch representation.

Salinity Effects on the Adsorption of Nucleic Acid Compounds on Na-Montmorillonite: a Prebiotic Chemistry Experiment

NASA Astrophysics Data System (ADS)

Villafañe-Barajas, Saúl A.; Baú, João Paulo T.; Colín-García, María; Negrón-Mendoza, Alicia; Heredia-Barbero, Alejandro; Pi-Puig, Teresa; Zaia, Dimas A. M.

2018-02-01

Any proposed model of Earth's primitive environments requires a combination of geochemical variables. Many experiments are prepared in aqueous solutions and in the presence of minerals. However, most sorption experiments are performed in distilled water, and just a few in seawater analogues, mostly inconsistent with a representative primitive ocean model. Therefore, it is necessary to perform experiments that consider the composition and concentration of dissolved salts in the early ocean to understand how these variables could have affected the absorption of organic molecules into minerals. In this work, the adsorption of adenine, adenosine, and 5'AMP onto Na+montmorillonite was studied using a primitive ocean analog (4.0 Ga) from experimental and computational approaches. The order of sorption of the molecules was: 5'AMP > adenine > adenosine. Infrared spectra showed that the interaction between these molecules and montmorillonite occurs through the NH2 group. In addition, electrostatic interaction between negatively charged montmorillonite and positively charge N1 of these molecules could occur. Results indicate that dissolved salts affect the sorption in all cases; the size and structure of each organic molecule influence the amount sorbed. Specifically, the X-ray diffraction patterns show that dissolved salts occupy the interlayer space in Na-montmorillonite and compete with organic molecules for available sites. The adsorption capacity is clearly affected by dissolved salts in thermodynamic terms as deduced by isotherm models. Indeed, molecular dynamic models suggest that salts are absorbed in the interlamellar space and can interact with oxygen atoms exposed in the edges of clay or in its surface, reducing the sorption of the organic molecules. This research shows that the sorption process could be affected by high concentration of salts, since ions and organic molecules may compete for available sites on inorganic surfaces. Salt concentration in primitive oceans may have strongly affected the sorption, and hence the concentration processes of organic molecules on minerals.

Statistics of Atmospheric Circulations from Cumulant Expansions

NASA Astrophysics Data System (ADS)

Marston, B.; Sabou, F.

2010-12-01

Large-scale atmospheric flows are not so nonlinear as to preclude their direct statistical simulation (DSS) by systematic expansions in equal-time cumulants. Such DSS offers a number of advantages: (i) Low-order statistics are smoother in space and stiffer in time than the underlying instantaneous flows, hence statistically stationary or slowly varying fixed points can be described with fewer degrees of freedom and can also be accessed rapidly. (ii) Convergence with increasing resolution can be demonstrated. (iii) Finally and most importantly, DSS leads more directly to understanding, by integrating out fast modes, leaving only the slow modes that contain the most interesting information. This makes the approach ideal for simulating and understanding modes of the climate system, including changes in these modes that are driven by climate change. The equations of motion for the cumulants form an infinite hierarchy. The simplest closure is to set the third and higher order cumulants to zero. We extend previous work (Marston, Conover, and Schneider 2008) along these lines to two-layer models of the general circulation which has previously been argued to be only weakly nonlinear (O'Gorman and Schneider, 2006). Equal-time statistics so obtained agree reasonably well with those accumulated by direct numerical simulation (DNS) reproducing efficiently the midlatitude westerlies and storm tracks, tropical easterlies, and non-local teleconnection patterns (Marston 2010). Low-frequency modes of variability can also be captured. The primitive equation model of Held & Suarez, with and without latent heat release, is investigated, providing a test of whether DSS accurately reproduces the responses to simple climate forcings as found by DNS.

Revisiting the Phase Curves of WASP-43b: Confronting Re-analyzed Spitzer Data with Cloudy Atmospheres

NASA Astrophysics Data System (ADS)

Mendonça, João M.; Malik, Matej; Demory, Brice-Olivier; Heng, Kevin

2018-04-01

Recently acquired Hubble and Spitzer phase curves of the short-period hot Jupiter WASP-43b make it an ideal target for confronting theory with data. On the observational front, we re-analyze the 3.6 and 4.5 μm Spitzer phase curves and demonstrate that our improved analysis better removes residual red noise due to intra-pixel sensitivity, which leads to greater fluxes emanating from the nightside of WASP-43b, thus reducing the tension between theory and data. On the theoretical front, we construct cloud-free and cloudy atmospheres of WASP-43b using our Global Circulation Model (GCM), THOR, which solves the non-hydrostatic Euler equations (compared to GCMs that typically solve the hydrostatic primitive equations). The cloud-free atmosphere produces a reasonable fit to the dayside emission spectrum. The multi-phase emission spectra constrain the cloud deck to be confined to the nightside and have a finite cloud-top pressure. The multi-wavelength phase curves are naturally consistent with our cloudy atmospheres, except for the 4.5 μm phase curve, which requires the presence of enhanced carbon dioxide in the atmosphere of WASP-43b. Multi-phase emission spectra at higher spectral resolution, as may be obtained using the James Webb Space Telescope, and a reflected-light phase curve at visible wavelengths would further constrain the properties of clouds in WASP-43b.

Elementary dispersion analysis of some mimetic discretizations on triangular C-grids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korn, P., E-mail: peter.korn@mpimet.mpg.de; Danilov, S.; A.M. Obukhov Institute of Atmospheric Physics, Moscow

2017-02-01

Spurious modes supported by triangular C-grids limit their application for modeling large-scale atmospheric and oceanic flows. Their behavior can be modified within a mimetic approach that generalizes the scalar product underlying the triangular C-grid discretization. The mimetic approach provides a discrete continuity equation which operates on an averaged combination of normal edge velocities instead of normal edge velocities proper. An elementary analysis of the wave dispersion of the new discretization for Poincaré, Rossby and Kelvin waves shows that, although spurious Poincaré modes are preserved, their frequency tends to zero in the limit of small wavenumbers, which removes the divergence noisemore » in this limit. However, the frequencies of spurious and physical modes become close on shorter scales indicating that spurious modes can be excited unless high-frequency short-scale motions are effectively filtered in numerical codes. We argue that filtering by viscous dissipation is more efficient in the mimetic approach than in the standard C-grid discretization. Lumping of mass matrices appearing with the velocity time derivative in the mimetic discretization only slightly reduces the accuracy of the wave dispersion and can be used in practice. Thus, the mimetic approach cures some difficulties of the traditional triangular C-grid discretization but may still need appropriately tuned viscosity to filter small scales and high frequencies in solutions of full primitive equations when these are excited by nonlinear dynamics.« less

Use of shape-preserving interpolation methods in surface modeling

NASA Technical Reports Server (NTRS)

Ftitsch, F. N.

1984-01-01

In many large-scale scientific computations, it is necessary to use surface models based on information provided at only a finite number of points (rather than determined everywhere via an analytic formula). As an example, an equation of state (EOS) table may provide values of pressure as a function of temperature and density for a particular material. These values, while known quite accurately, are typically known only on a rectangular (but generally quite nonuniform) mesh in (T,d)-space. Thus interpolation methods are necessary to completely determine the EOS surface. The most primitive EOS interpolation scheme is bilinear interpolation. This has the advantages of depending only on local information, so that changes in data remote from a mesh element have no effect on the surface over the element, and of preserving shape information, such as monotonicity. Most scientific calculations, however, require greater smoothness. Standard higher-order interpolation schemes, such as Coons patches or bicubic splines, while providing the requisite smoothness, tend to produce surfaces that are not physically reasonable. This means that the interpolant may have bumps or wiggles that are not supported by the data. The mathematical quantification of ideas such as physically reasonable and visually pleasing is examined.

Cellular Particle Dynamics simulation of biomechanical relaxation processes of multi-cellular systems

NASA Astrophysics Data System (ADS)

McCune, Matthew; Kosztin, Ioan

2013-03-01

Cellular Particle Dynamics (CPD) is a theoretical-computational-experimental framework for describing and predicting the time evolution of biomechanical relaxation processes of multi-cellular systems, such as fusion, sorting and compression. In CPD, cells are modeled as an ensemble of cellular particles (CPs) that interact via short range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through numerical integration of their equations of motion. Here we present CPD simulation results for the fusion of both spherical and cylindrical multi-cellular aggregates. First, we calibrate the relevant CPD model parameters for a given cell type by comparing the CPD simulation results for the fusion of two spherical aggregates to the corresponding experimental results. Next, CPD simulations are used to predict the time evolution of the fusion of cylindrical aggregates. The latter is relevant for the formation of tubular multi-cellular structures (i.e., primitive blood vessels) created by the novel bioprinting technology. Work supported by NSF [PHY-0957914]. Computer time provided by the University of Missouri Bioinformatics Consortium.

The mevalonate pathway regulates primitive streak formation via protein farnesylation

PubMed Central

Okamoto-Uchida, Yoshimi; Yu, Ruoxing; Miyamura, Norio; Arima, Norie; Ishigami-Yuasa, Mari; Kagechika, Hiroyuki; Yoshida, Suguru; Hosoya, Takamitsu; Nawa, Makiko; Kasama, Takeshi; Asaoka, Yoichi; Alois, Reiner Wimmer; Elling, Ulrich; Penninger, Josef M.; Nishina, Sachiko; Azuma, Noriyuki; Nishina, Hiroshi

2016-01-01

The primitive streak in peri-implantation embryos forms the mesoderm and endoderm and controls cell differentiation. The metabolic cues regulating primitive streak formation remain largely unknown. Here we utilised a mouse embryonic stem (ES) cell differentiation system and a library of well-characterised drugs to identify these metabolic factors. We found that statins, which inhibit the mevalonate metabolic pathway, suppressed primitive streak formation in vitro and in vivo. Using metabolomics and pharmacologic approaches we identified the downstream signalling pathway of mevalonate and revealed that primitive streak formation requires protein farnesylation but not cholesterol synthesis. A tagging-via-substrate approach revealed that nuclear lamin B1 and small G proteins were farnesylated in embryoid bodies and important for primitive streak gene expression. In conclusion, protein farnesylation driven by the mevalonate pathway is a metabolic cue essential for primitive streak formation. PMID:27883036

Graphical Means for Inspecting Qualitative Models of System Behaviour

ERIC Educational Resources Information Center

Bouwer, Anders; Bredeweg, Bert

2010-01-01

This article presents the design and evaluation of a tool for inspecting conceptual models of system behaviour. The basis for this research is the Garp framework for qualitative simulation. This framework includes modelling primitives, such as entities, quantities and causal dependencies, which are combined into model fragments and scenarios.…

Connectivity among straits of the northwest Pacific marginal seas

NASA Astrophysics Data System (ADS)

Cho, Yang-Ki; Seo, Gwang-Ho; Choi, Byoung-Ju; Kim, Sangil; Kim, Young-Gyu; Youn, Yong-Hoon; Dever, Edward P.

2009-06-01

The connectivity among straits of the northwest Pacific marginal seas is investigated with a primitive-equation ocean circulation model simulated for 10 years from 1994 to 2003. Over the simulation interval the temporal and spatial means and variations of the model sea surface temperature are comparable to those of the satellite sea surface temperature. The model transport through the straits shows good agreement with the available observations and a high seasonality in the Taiwan Strait, the Korea Strait, and the Soya Strait but relatively low seasonality in the Tsugaru Strait. The Kuroshio and Taiwan Warm Current (TWC) are two sources of water flowing through the Korea Strait. The volume transport in the Korea Strait is dominated by the Kuroshio in winter (83%) and by the TWC in summer (66%). Relative to the transport through the Korea Strait, the transport percentages of the Tsugaru Strait connecting to the northwest Pacific Ocean are 79% in winter and 65% in summer. The seasonality of the Korea Strait transport is positively correlated with the cross-strait wind stress. The drifter experiments show that it takes about 4 months for most of the drifters deployed in the Taiwan Strait to enter the Korea Strait and more than 2 months to travel from the Korea Strait to the Tsugaru and Soya straits.

Isotopic Fractionation in Primitive Material: Quantifying the Contribution of Interstellar Chemistry

NASA Technical Reports Server (NTRS)

Charnley, Steven

2010-01-01

Anomalously fractionated isotopic material is found in many primitive Solar System objects, such as meteorites and comets. It is thought, in some cases, to trace interstellar matter that was incorporated into the Solar Nebula without undergoing significant processing. We will present the results of models of the nitrogen, oxygen, and carbon fractionation chemistry in dense molecular clouds, particularly in cores where substantial freeze-out of molecules on to dust has occurred. The range of fractionation ratios expected in different interstellar molecules will be discussed and compared to the ratios measured in molecular clouds, comets and meteoritic material. These models make several predictions that can be tested in the near future by molecular line observations, particularly with ALMA.

Minimization In Digital Design As A Meta-Planning Problem

NASA Astrophysics Data System (ADS)

Ho, William P. C.; Wu, Jung-Gen

1987-05-01

In our model-based expert system for automatic digital system design, we formalize the design process into three sub-processes - compiling high-level behavioral specifications into primitive behavioral operations, grouping primitive operations into behavioral functions, and grouping functions into modules. Consideration of design minimization explicitly controls decision-making in the last two subprocesses. Design minimization, a key task in the automatic design of digital systems, is complicated by the high degree of interaction among the time sequence and content of design decisions. In this paper, we present an AI approach which directly addresses these interactions and their consequences by modeling the minimization prob-lem as a planning problem, and the management of design decision-making as a meta-planning problem.

18F-FLT Positron Emission Tomography and Diffusion-Weighted Magnetic Resonance Imaging in Planning Surgery and Radiation Therapy and Measuring Response in Patients With Newly Diagnosed Ewing Sarcoma

ClinicalTrials.gov

2017-11-16

Adult Supratentorial Primitive Neuroectodermal Tumor (PNET); Ewing Sarcoma of Bone; Extraosseous Ewing Sarcoma; Localized Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Metastatic Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Untreated Childhood Supratentorial Primitive Neuroectodermal Tumor

Metabolic reprogramming: a cancer hallmark even warburg did not anticipate.

PubMed

Ward, Patrick S; Thompson, Craig B

2012-03-20

Cancer metabolism has long been equated with aerobic glycolysis, seen by early biochemists as primitive and inefficient. Despite these early beliefs, the metabolic signatures of cancer cells are not passive responses to damaged mitochondria but result from oncogene-directed metabolic reprogramming required to support anabolic growth. Recent evidence suggests that metabolites themselves can be oncogenic by altering cell signaling and blocking cellular differentiation. No longer can cancer-associated alterations in metabolism be viewed as an indirect response to cell proliferation and survival signals. We contend that altered metabolism has attained the status of a core hallmark of cancer. Copyright © 2012 Elsevier Inc. All rights reserved.

Determination of Mean Dynamic Topography (MDT) to Bridge Geoid and Mean Sea Surface Height (SSH) with a New Elliptic Equation

NASA Astrophysics Data System (ADS)

Chu, P. C.

2016-12-01

Mean dynamic topography (MDT, η) bridges the geoid and the mean sea surface (from satellite altimetry) and constrains large scale surface geostrophic circulations. It can be estimated from either satellite or underwater ocean temperature (T) and salinity (S) data. Satellite altimeter measures sea surface height (SSH) with high precision and unique resolution above a reference ellipsoid (not geoid). Two Gravity Recovery and Climate Experiment (GRACE) satellites launched in 2002, provide data to compute the marine geoid [called the GRACE Gravity Model (GGM)] (see website: http://www.csr.utexas.edu/grace/). The MDT is the difference of altimetry-derived mean SSH and the mean marine geoid (using GGM or pre-GRACE gravity model such as EGM96). A major difficulty arises that the spatial variations in mean SSH and marine geoid are approximately two orders of magnitude larger than the spatial variations in η.The second approach (using T, Sdata) is based on geostrophic balance, which is at the minimum energy state in the linear Boussinesq primitive equations with conservation of potential vorticity. In this paper, a new elliptic equation, -[∂x(gh/f2)∂xη+∂y(gh/f2)∂yη]+η = (g/f2)(∂C/∂x-∂B/∂y)is derived to determine MDT with H the water depth, g the gravitational acceleration, and coefficients (B, C) depend on 3D mean temperature (T) and salinity (S) data. Numerical approach transforms the elliptic equation into a set of well-posed linear algebraic equations of η at grid points. The solution for the North Atlantic Ocean (100oW-6oW, 7oN-72oN) on 1oX1ogrids with the coefficients (B, C) calculated from the three-dimensional (T, S) data of the NOAA National Centers for Environmental Information (NCEI) World Ocean Atlas 2013 version 2 (http://www.nodc.noaa.gov/OC5/woa13/woa13data.html) and H from the NOAA ETOPO5 (https://www.ngdc.noaa.gov/mgg/fliers/93mgg01.html), compares well with the difference (also considered as the MDT) between the time-averaged SSH and the geoid from the NASA/JPL (http://gracetellus.jpl.nasa.gov/data/dot/). Further application of this elliptic equation method on the high-precision altimetry measurements of SSH such as the Surface Water and Ocean Topography (SWOT) is also presented.

Genetic origin, admixture and population history of aurochs (Bos primigenius) and primitive European cattle

PubMed Central

Upadhyay, M R; Chen, W; Lenstra, J A; Goderie, C R J; MacHugh, D E; Park, S D E; Magee, D A; Matassino, D; Ciani, F; Megens, H-J; van Arendonk, J A M; Groenen, M A M; Marsan, P A; Balteanu, V; Dunner, S; Garcia, J F; Ginja, C; Kantanen, J

2017-01-01

The domestication of taurine cattle initiated ~10 000 years ago in the Near East from a wild aurochs (Bos primigenius) population followed by their dispersal through migration of agriculturalists to Europe. Although gene flow from wild aurochs still present at the time of this early dispersion is still debated, some of the extant primitive cattle populations are believed to possess the aurochs-like primitive features. In this study, we use genome-wide single nucleotide polymorphisms to assess relationship, admixture patterns and demographic history of an ancient aurochs sample and European cattle populations, several of which have primitive features and are suitable for extensive management. The principal component analysis, the model-based clustering and a distance-based network analysis support previous works suggesting different histories for north-western and southern European cattle. Population admixture analysis indicates a zebu gene flow in the Balkan and Italian Podolic cattle populations. Our analysis supports the previous report of gene flow between British and Irish primitive cattle populations and local aurochs. In addition, we show evidence of aurochs gene flow in the Iberian cattle populations indicating wide geographical distribution of the aurochs. Runs of homozygosity (ROH) reveal that demographic processes like genetic isolation and breed formation have contributed to genomic variations of European cattle populations. The ROH also indicate recent inbreeding in southern European cattle populations. We conclude that in addition to factors such as ancient human migrations, isolation by distance and cross-breeding, gene flow between domestic and wild-cattle populations also has shaped genomic composition of European cattle populations. PMID:27677498

Genetic origin, admixture and population history of aurochs (Bos primigenius) and primitive European cattle.

PubMed

Upadhyay, M R; Chen, W; Lenstra, J A; Goderie, C R J; MacHugh, D E; Park, S D E; Magee, D A; Matassino, D; Ciani, F; Megens, H-J; van Arendonk, J A M; Groenen, M A M

2017-02-01

The domestication of taurine cattle initiated ~10 000 years ago in the Near East from a wild aurochs (Bos primigenius) population followed by their dispersal through migration of agriculturalists to Europe. Although gene flow from wild aurochs still present at the time of this early dispersion is still debated, some of the extant primitive cattle populations are believed to possess the aurochs-like primitive features. In this study, we use genome-wide single nucleotide polymorphisms to assess relationship, admixture patterns and demographic history of an ancient aurochs sample and European cattle populations, several of which have primitive features and are suitable for extensive management. The principal component analysis, the model-based clustering and a distance-based network analysis support previous works suggesting different histories for north-western and southern European cattle. Population admixture analysis indicates a zebu gene flow in the Balkan and Italian Podolic cattle populations. Our analysis supports the previous report of gene flow between British and Irish primitive cattle populations and local aurochs. In addition, we show evidence of aurochs gene flow in the Iberian cattle populations indicating wide geographical distribution of the aurochs. Runs of homozygosity (ROH) reveal that demographic processes like genetic isolation and breed formation have contributed to genomic variations of European cattle populations. The ROH also indicate recent inbreeding in southern European cattle populations. We conclude that in addition to factors such as ancient human migrations, isolation by distance and cross-breeding, gene flow between domestic and wild-cattle populations also has shaped genomic composition of European cattle populations.

Diagnostic Study of Tumor Characteristics in Patients With Ewing's Sarcoma

ClinicalTrials.gov

2013-06-20

Localized Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Metastatic Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Recurrent Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor

Comparative analysis of the 5S rRNA and its associated proteins reveals unique primitive rather than parasitic features in Giardia lamblia.

PubMed

Feng, Jin-Mei; Sun, Jun; Xin, De-Dong; Wen, Jian-Fan

2012-01-01

5S rRNA is a highly conserved ribosomal component. Eukaryotic 5S rRNA and its associated proteins (5S rRNA system) have become very well understood. Giardia lamblia was thought by some researchers to be the most primitive extant eukaryote while others considered it a highly evolved parasite. Previous reports have indicated that some aspects of its 5S rRNA system are simpler than that of common eukaryotes. We here explore whether this is true to its entire system, and whether this simplicity is a primitive or parasitic feature. By collecting and confirming pre-existing data and identifying new data, we obtained almost complete datasets of the system of three isolates of G. lamblia, two other parasitic excavates (Trichomonas vaginalis, Trypanosoma cruzi), and one free-living one (Naegleria gruberi). After comprehensively comparing each aspect of the system among these excavates and also with those of archaea and common eukaryotes, we found all the three Giardia isolates to harbor a same simplified 5S rRNA system, which is not only much simpler than that of common eukaryotes but also the simplest one among those of these excavates, and is surprisingly very similar to that of archaea; we also found among these excavates the system in parasitic species is not necessarily simpler than that in free-living species, conversely, the system of free-living species is even simpler in some respects than those of parasitic ones. The simplicity of Giardia 5S rRNA system should be considered a primitive rather than parasitically-degenerated feature. Therefore, Giardia 5S rRNA system might be a primitive system that is intermediate between that of archaea and the common eukaryotic model system, and it may reflect the evolutionary history of the eukaryotic 5S rRNA system from the archaeal form. Our results also imply G. lamblia might be a primitive eukaryote with secondary parasitically-degenerated features.

The Mediterranean Forecasting System: recent developments

NASA Astrophysics Data System (ADS)

Tonani, Marina; Oddo, Paolo; Korres, Gerasimos; Clementi, Emanuela; Dobricic, Srdjan; Drudi, Massimiliano; Pistoia, Jenny; Guarnieri, Antonio; Romaniello, Vito; Girardi, Giacomo; Grandi, Alessandro; Bonaduce, Antonio; Pinardi, Nadia

2014-05-01

Recent developments of the Mediterranean Monitoring and Forecasting Centre of the EU-Copernicus marine service, the Mediterranean Forecasting System (MFS), are presented. MFS provides forecast, analysis and reanalysis for the physical and biogeochemical parameters of the Mediterranean Sea. The different components of the system are continuously updated in order to provide to the users the best available product. This work is focus on the physical component of the system. The physical core of MFS is composed by an ocean general circulation model (NEMO) coupled with a spectral wave model (Wave Watch-III). The NEMO model provides to WW-III surface currents and SST fields, while WW-III returns back to NEMO the neutral component of the surface drag coefficient. Satellite Sea Level Anomaly observations and in-situ T & S vertical profiles are assimilated into this system using a variational assimilation scheme based on 3DVAR (Dobricic, 2008) . Sensitive experiments have been performed in order to assess the impact of the assimilation of the latest available SLA missions, Altika and Cryosat together with the long term available mission of Jason2. The results show a significant improvement of the MFS skill due to the multi-mission along track assimilation. The primitive equations module has been recently upgraded with the introduction of the atmospheric pressure term and a new, explicit, numerical scheme has been adopted to solve the barotropic component of the equations of motion. The SLA satellite observations for data assimilation have been consequently modified in order to account for the new atmospheric pressure term introduced in the equations. This new system has been evaluated using tide gauge coastal buoys and the satellite along track data. The quality of the SSH has improved significantly while a minor impact has been observed on the other state variables (temperature, salinity and currents). Experiments with a higher resolution NWP (numerical weather prediction) forcing provided by the COSMO-MED system (provided by the Italian Meteorological Office), have been performed and a pre-operational 3-day forecast production system has been developed. The comparison between this system and the official one forced by the ECMWF NWP data will be discussed.

Highly turbulent solutions of the Lagrangian-averaged Navier-Stokes alpha model and their large-eddy-simulation potential.

PubMed

Pietarila Graham, Jonathan; Holm, Darryl D; Mininni, Pablo D; Pouquet, Annick

2007-11-01

We compute solutions of the Lagrangian-averaged Navier-Stokes alpha - (LANS alpha ) model for significantly higher Reynolds numbers (up to Re approximately 8300 ) than have previously been accomplished. This allows sufficient separation of scales to observe a Navier-Stokes inertial range followed by a second inertial range specific to the LANS alpha model. Both fully helical and nonhelical flows are examined, up to Reynolds numbers of approximately 1300. Analysis of the third-order structure function scaling supports the predicted l3 scaling; it corresponds to a k-1 scaling of the energy spectrum for scales smaller than alpha. The energy spectrum itself shows a different scaling, which goes as k1. This latter spectrum is consistent with the absence of stretching in the subfilter scales due to the Taylor frozen-in hypothesis employed as a closure in the derivation of the LANS alpha model. These two scalings are conjectured to coexist in different spatial portions of the flow. The l3 [E(k) approximately k-1] scaling is subdominant to k1 in the energy spectrum, but the l3 scaling is responsible for the direct energy cascade, as no cascade can result from motions with no internal degrees of freedom. We demonstrate verification of the prediction for the size of the LANS alpha attractor resulting from this scaling. From this, we give a methodology either for arriving at grid-independent solutions for the LANS alpha model, or for obtaining a formulation of the large eddy simulation optimal in the context of the alpha models. The fully converged grid-independent LANS alpha model may not be the best approximation to a direct numerical simulation of the Navier-Stokes equations, since the minimum error is a balance between truncation errors and the approximation error due to using the LANS alpha instead of the primitive equations. Furthermore, the small-scale behavior of the LANS alpha model contributes to a reduction of flux at constant energy, leading to a shallower energy spectrum for large alpha. These small-scale features, however, do not preclude the LANS alpha model from reproducing correctly the intermittency properties of the high-Reynolds-number flow.

Collecting and Storing Biological Samples From Patients With Ewing Sarcoma

ClinicalTrials.gov

2017-12-11

Askin Tumor; Localized Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Metastatic Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor; Recurrent Ewing Sarcoma/Peripheral Primitive Neuroectodermal Tumor

Influence of H2O on Liquidus Temperatures of Primitive Basalts and Olivine-Liquid Thermometry.

NASA Astrophysics Data System (ADS)

Medard, E.; Grove, T. L.

2005-12-01

We have undertaken a systematic experimental study aimed at understanding the effect of water on olivine liquidus temperatures of primitive basalts. Experiments have been performed on a primitive tholeiitic basalt from Medicine Lake Volcano, California (sample 82-72f, Bartels et al. 1991). The dry liquidus has been characterized from 0.1 MPa to 1.2 GPa. The wet liquidus has been constrained to within 15 °C using water-saturated experiments performed in a MHC externally heated pressure vessel. Preliminary results show that the olivine-liquidus depression (i.e., the difference between dry and water-bearing liquidus) is essentially a linear function of the water content of the melt: ΔT = 560  X(HO0.5), where X(HO0.5) is the mole fraction of water, calculated on a single-cation oxide basis. For 82-72f, this roughly translates into a 30 °C / wt% H2O depression. Simple systems (e.g., diopside/H2O, albite/H2O) suggest that melt structure / composition may have an influence on H2O liquidus depression, and this potential influence is currently under investigation. Experimental phase equilibria and thermobarometry of primitive basalts provide the primary evidence for estimating melting conditions and thermal structures in the Earth's mantle. Assessing the influence of H2O is critical, because it is the dominant volatile component involved in igneous processes, and it has been shown to cause a significant reduction in liquidus temperatures. However, recent model parameterizations vary from very large effects at low H2O contents (about 75 °C at 1 wt% H2O, Falloon and Danyushevsky 2000) to linear effect of H2O vs liquidus temperature (about 25 °C at 1 wt% H2O, Sugawara 2000). Our experimental determination more closely approximates the latter model. A key consequence is that the presence of small amounts of water in MORB magmas (< 1wt%) will only have a very small effect (< 30 °C) on liquidus temperature determination for mid-ocean-ridges. For magmas that are more water-rich, as observed in subduction zones, ocean island and continental magmatism, this parameterization of H2O liquidus depression can be included in existing thermodynamic models to retrieve magmatic temperatures from petrology of primitive basalts.

The impact of satellite temperature soundings on the forecasts of a small national meteorological service

NASA Technical Reports Server (NTRS)

Wolfson, N.; Thomasell, A.; Alperson, Z.; Brodrick, H.; Chang, J. T.; Gruber, A.; Ohring, G.

1984-01-01

The impact of introducing satellite temperature sounding data on a numerical weather prediction model of a national weather service is evaluated. A dry five level, primitive equation model which covers most of the Northern Hemisphere, is used for these experiments. Series of parallel forecast runs out to 48 hours are made with three different sets of initial conditions: (1) NOSAT runs, only conventional surface and upper air observations are used; (2) SAT runs, satellite soundings are added to the conventional data over oceanic regions and North Africa; and (3) ALLSAT runs, the conventional upper air observations are replaced by satellite soundings over the entire model domain. The impact on the forecasts is evaluated by three verification methods: the RMS errors in sea level pressure forecasts, systematic errors in sea level pressure forecasts, and errors in subjective forecasts of significant weather elements for a selected portion of the model domain. For the relatively short range of the present forecasts, the major beneficial impacts on the sea level pressure forecasts are found precisely in those areas where the satellite sounding are inserted and where conventional upper air observations are sparse. The RMS and systematic errors are reduced in these regions. The subjective forecasts of significant weather elements are improved with the use of the satellite data. It is found that the ALLSAT forecasts are of a quality comparable to the SAR forecasts.

Solution-Adaptive Cartesian Cell Approach for Viscous and Inviscid Flows

NASA Technical Reports Server (NTRS)

Coirier, William J.; Powell, Kenneth G.

1996-01-01

A Cartesian cell-based approach for adaptively refined solutions of the Euler and Navier-Stokes equations in two dimensions is presented. Grids about geometrically complicated bodies are generated automatically, by the recursive subdivision of a single Cartesian cell encompassing the entire flow domain. Where the resulting cells intersect bodies, polygonal cut cells are created using modified polygon-clipping algorithms. The grid is stored in a binary tree data structure that provides a natural means of obtaining cell-to-cell connectivity and of carrying out solution-adaptive mesh refinement. The Euler and Navier-Stokes equations are solved on the resulting grids using a finite volume formulation. The convective terms are upwinded: A linear reconstruction of the primitive variables is performed, providing input states to an approximate Riemann solver for computing the fluxes between neighboring cells. The results of a study comparing the accuracy and positivity of two classes of cell-centered, viscous gradient reconstruction procedures is briefly summarized. Adaptively refined solutions of the Navier-Stokes equations are shown using the more robust of these gradient reconstruction procedures, where the results computed by the Cartesian approach are compared to theory, experiment, and other accepted computational results for a series of low and moderate Reynolds number flows.

Evaluating structural pattern recognition for handwritten math via primitive label graphs

NASA Astrophysics Data System (ADS)

Zanibbi, Richard; Mouchère, Harold; Viard-Gaudin, Christian

2013-01-01

Currently, structural pattern recognizer evaluations compare graphs of detected structure to target structures (i.e. ground truth) using recognition rates, recall and precision for object segmentation, classification and relationships. In document recognition, these target objects (e.g. symbols) are frequently comprised of multiple primitives (e.g. connected components, or strokes for online handwritten data), but current metrics do not characterize errors at the primitive level, from which object-level structure is obtained. Primitive label graphs are directed graphs defined over primitives and primitive pairs. We define new metrics obtained by Hamming distances over label graphs, which allow classification, segmentation and parsing errors to be characterized separately, or using a single measure. Recall and precision for detected objects may also be computed directly from label graphs. We illustrate the new metrics by comparing a new primitive-level evaluation to the symbol-level evaluation performed for the CROHME 2012 handwritten math recognition competition. A Python-based set of utilities for evaluating, visualizing and translating label graphs is publicly available.

A musculoskeletal model of human locomotion driven by a low dimensional set of impulsive excitation primitives

PubMed Central

Sartori, Massimo; Gizzi, Leonardo; Lloyd, David G.; Farina, Dario

2013-01-01

Human locomotion has been described as being generated by an impulsive (burst-like) excitation of groups of musculotendon units, with timing dependent on the biomechanical goal of the task. Despite this view being supported by many experimental observations on specific locomotion tasks, it is still unknown if the same impulsive controller (i.e., a low-dimensional set of time-delayed excitastion primitives) can be used as input drive for large musculoskeletal models across different human locomotion tasks. For this purpose, we extracted, with non-negative matrix factorization, five non-negative factors from a large sample of muscle electromyograms in two healthy subjects during four motor tasks. These included walking, running, sidestepping, and crossover cutting maneuvers. The extracted non-negative factors were then averaged and parameterized to obtain task-generic Gaussian-shaped impulsive excitation curves or primitives. These were used to drive a subject-specific musculoskeletal model of the human lower extremity. Results showed that the same set of five impulsive excitation primitives could be used to predict the dynamics of 34 musculotendon units and the resulting hip, knee and ankle joint moments (i.e., NRMSE = 0.18 ± 0.08, and R2 = 0.73 ± 0.22 across all tasks and subjects) without substantial loss of accuracy with respect to using experimental electromyograms (i.e., NRMSE = 0.16 ± 0.07, and R2 = 0.78 ± 0.18 across all tasks and subjects). Results support the hypothesis that biomechanically different motor tasks might share similar neuromuscular control strategies. This might have implications in neurorehabilitation technologies such as human-machine interfaces for the torque-driven, proportional control of powered prostheses and orthoses. In this, device control commands (i.e., predicted joint torque) could be derived without direct experimental data but relying on simple parameterized Gaussian-shaped curves, thus decreasing the input drive complexity and the number of needed sensors. PMID:23805099

A musculoskeletal model of human locomotion driven by a low dimensional set of impulsive excitation primitives.

PubMed

Sartori, Massimo; Gizzi, Leonardo; Lloyd, David G; Farina, Dario

2013-01-01

Human locomotion has been described as being generated by an impulsive (burst-like) excitation of groups of musculotendon units, with timing dependent on the biomechanical goal of the task. Despite this view being supported by many experimental observations on specific locomotion tasks, it is still unknown if the same impulsive controller (i.e., a low-dimensional set of time-delayed excitastion primitives) can be used as input drive for large musculoskeletal models across different human locomotion tasks. For this purpose, we extracted, with non-negative matrix factorization, five non-negative factors from a large sample of muscle electromyograms in two healthy subjects during four motor tasks. These included walking, running, sidestepping, and crossover cutting maneuvers. The extracted non-negative factors were then averaged and parameterized to obtain task-generic Gaussian-shaped impulsive excitation curves or primitives. These were used to drive a subject-specific musculoskeletal model of the human lower extremity. Results showed that the same set of five impulsive excitation primitives could be used to predict the dynamics of 34 musculotendon units and the resulting hip, knee and ankle joint moments (i.e., NRMSE = 0.18 ± 0.08, and R (2) = 0.73 ± 0.22 across all tasks and subjects) without substantial loss of accuracy with respect to using experimental electromyograms (i.e., NRMSE = 0.16 ± 0.07, and R (2) = 0.78 ± 0.18 across all tasks and subjects). Results support the hypothesis that biomechanically different motor tasks might share similar neuromuscular control strategies. This might have implications in neurorehabilitation technologies such as human-machine interfaces for the torque-driven, proportional control of powered prostheses and orthoses. In this, device control commands (i.e., predicted joint torque) could be derived without direct experimental data but relying on simple parameterized Gaussian-shaped curves, thus decreasing the input drive complexity and the number of needed sensors.

Reconstructing Holocene climate using a climate model: Model strategy and preliminary results

NASA Astrophysics Data System (ADS)

Haberkorn, K.; Blender, R.; Lunkeit, F.; Fraedrich, K.

2009-04-01

An Earth system model of intermediate complexity (Planet Simulator; PlaSim) is used to reconstruct Holocene climate based on proxy data. The Planet Simulator is a user friendly general circulation model (GCM) suitable for palaeoclimate research. Its easy handling and the modular structure allow for fast and problem dependent simulations. The spectral model is based on the moist primitive equations conserving momentum, mass, energy and moisture. Besides the atmospheric part, a mixed layer-ocean with sea ice and a land surface with biosphere are included. The present-day climate of PlaSim, based on an AMIP II control-run (T21/10L resolution), shows reasonable agreement with ERA-40 reanalysis data. Combining PlaSim with a socio-technological model (GLUES; DFG priority project INTERDYNAMIK) provides improved knowledge on the shift from hunting-gathering to agropastoral subsistence societies. This is achieved by a data assimilation approach, incorporating proxy time series into PlaSim to initialize palaeoclimate simulations during the Holocene. For this, the following strategy is applied: The sensitivities of the terrestrial PlaSim climate are determined with respect to sea surface temperature (SST) anomalies. Here, the focus is the impact of regionally varying SST both in the tropics and the Northern Hemisphere mid-latitudes. The inverse of these sensitivities is used to determine the SST conditions necessary for the nudging of land and coastal proxy climates. Preliminary results indicate the potential, the uncertainty and the limitations of the method.

Procedures for offline grid nesting in regional ocean models

NASA Astrophysics Data System (ADS)

Mason, Evan; Molemaker, Jeroen; Shchepetkin, Alexander F.; Colas, Francois; McWilliams, James C.; Sangrà, Pablo

One-way offline nesting of a primitive-equation regional ocean numerical model (ROMS) is investigated, with special attention to the boundary forcing file creation process. The model has a modified open boundary condition which minimises false wave reflections, and is optimised to utilise high-frequency boundary updates. The model configuration features a previously computed solution which supplies boundary forcing data to an interior domain with an increased grid resolution. At the open boundaries of the interior grid (the child) the topography is matched to that of the outer grid (the parent), over a narrow transition region. A correction is applied to the normal baroclinic and barotropic velocities at the open boundaries of the child to ensure volume conservation. It is shown that these steps, together with a carefully constructed interpolation of the parent data, lead to a high-quality child solution, with minimal artifacts such as persistent rim currents and wave reflections at the boundaries. Sensitivity experiments provide information about the robustness of the model open boundary condition to perturbations in the surface wind stress forcing field, to the perturbation of the volume conservation enforcement in the boundary forcing, and to perturbation of the vertical density structure in the boundary forcing. This knowledge is important when extending the nesting technique to include external data from alien sources, such as ocean models with physics and/or numerics different from ROMS, or from observed climatologies of temperature, salinity and sea level.

Feature-oriented regional modeling and simulations in the Gulf of Maine and Georges Bank

NASA Astrophysics Data System (ADS)

Gangopadhyay, Avijit; Robinson, Allan R.; Haley, Patrick J.; Leslie, Wayne G.; Lozano, Carlos J.; Bisagni, James J.; Yu, Zhitao

2003-03-01

The multiscale synoptic circulation system in the Gulf of Maine and Georges Bank (GOMGB) region is presented using a feature-oriented approach. Prevalent synoptic circulation structures, or 'features', are identified from previous observational studies. These features include the buoyancy-driven Maine Coastal Current, the Georges Bank anticyclonic frontal circulation system, the basin-scale cyclonic gyres (Jordan, Georges and Wilkinson), the deep inflow through the Northeast Channel (NEC), the shallow outflow via the Great South Channel (GSC), and the shelf-slope front (SSF). Their synoptic water-mass ( T- S) structures are characterized and parameterized in a generalized formulation to develop temperature-salinity feature models. A synoptic initialization scheme for feature-oriented regional modeling and simulation (FORMS) of the circulation in the coastal-to-deep region of the GOMGB system is then developed. First, the temperature and salinity feature-model profiles are placed on a regional circulation template and then objectively analyzed with appropriate background climatology in the coastal region. Furthermore, these fields are melded with adjacent deep-ocean regional circulation (Gulf Stream Meander and Ring region) along and across the SSF. These initialization fields are then used for dynamical simulations via the primitive equation model. Simulation results are analyzed to calibrate the multiparameter feature-oriented modeling system. Experimental short-term synoptic simulations are presented for multiple resolutions in different regions with and without atmospheric forcing. The presented 'generic and portable' methodology demonstrates the potential of applying similar FORMS in many other regions of the Global Coastal Ocean.

Modeling and simulation of dust behaviors behind a moving vehicle

NASA Astrophysics Data System (ADS)

Wang, Jingfang

Simulation of physically realistic complex dust behaviors is a difficult and attractive problem in computer graphics. A fast, interactive and visually convincing model of dust behaviors behind moving vehicles is very useful in computer simulation, training, education, art, advertising, and entertainment. In my dissertation, an experimental interactive system has been implemented for the simulation of dust behaviors behind moving vehicles. The system includes physically-based models, particle systems, rendering engines and graphical user interface (GUI). I have employed several vehicle models including tanks, cars, and jeeps to test and simulate in different scenarios and conditions. Calm weather, winding condition, vehicle turning left or right, and vehicle simulation controlled by users from the GUI are all included. I have also tested the factors which play against the physical behaviors and graphics appearances of the dust particles through GUI or off-line scripts. The simulations are done on a Silicon Graphics Octane station. The animation of dust behaviors is achieved by physically-based modeling and simulation. The flow around a moving vehicle is modeled using computational fluid dynamics (CFD) techniques. I implement a primitive variable and pressure-correction approach to solve the three dimensional incompressible Navier Stokes equations in a volume covering the moving vehicle. An alternating- direction implicit (ADI) method is used for the solution of the momentum equations, with a successive-over- relaxation (SOR) method for the solution of the Poisson pressure equation. Boundary conditions are defined and simplified according to their dynamic properties. The dust particle dynamics is modeled using particle systems, statistics, and procedure modeling techniques. Graphics and real-time simulation techniques, such as dynamics synchronization, motion blur, blending, and clipping have been employed in the rendering to achieve realistic appearing dust behaviors. In addition, I introduce a temporal smoothing technique to eliminate the jagged effect caused by large simulation time. Several algorithms are used to speed up the simulation. For example, pre-calculated tables and display lists are created to replace some of the most commonly used functions, scripts and processes. The performance study shows that both time and space costs of the algorithms are linear in the number of particles in the system. On a Silicon Graphics Octane, three vehicles with 20,000 particles run at 6-8 frames per second on average. This speed does not include the extra calculations of convergence of the numerical integration for fluid dynamics which usually takes about 4-5 minutes to achieve steady state.

Synthesis of phosphatidylcholine under possible primitive earth conditions

NASA Technical Reports Server (NTRS)

Rao, M.; Eichberg, J.; Oro, J.

1982-01-01

Using a primitive earth evaporating pond model, the synthesis of phosphatidylcholine was accomplished when a reaction mixture of choline chloride and disodium phosphatidate, in the presence of cyanamide and traces of acid, was evaporated and heated at temperatures ranging from 25 to 100 C for 7 hours. Optimum yields of about 15% were obtained at 80 C. Phosphatidylcholine was identified by chromatographic, chemical and enzymatic degradation methods. On enzymatic hydrolysis with phospholipase A2 and phospholipase C, lysophosphatidylcholine and phosphorylcholine were formed, respectively. Alkaline hydrolysis gave glycerophosphorylcholine. The synthesis of phosphatidylcholine as the major compound was accompanied by the formation of lysophosphatidylcholine in smaller amounts. Cyanamide was found to be essential for the formation of phosphatidylcholine, and only traces of HCl, of the order of that required to convert the disodium phosphatidate to free phosphatidic acid were found necessary for the synthesis. This work suggests that phosphatidylcholine, which is an essential component of most biological membranes, could have been synthesized on the primitive earth.

Topological analysis of polymeric melts: chain-length effects and fast-converging estimators for entanglement length.

PubMed

Hoy, Robert S; Foteinopoulou, Katerina; Kröger, Martin

2009-09-01

Primitive path analyses of entanglements are performed over a wide range of chain lengths for both bead spring and atomistic polyethylene polymer melts. Estimators for the entanglement length N_{e} which operate on results for a single chain length N are shown to produce systematic O(1/N) errors. The mathematical roots of these errors are identified as (a) treating chain ends as entanglements and (b) neglecting non-Gaussian corrections to chain and primitive path dimensions. The prefactors for the O(1/N) errors may be large; in general their magnitude depends both on the polymer model and the method used to obtain primitive paths. We propose, derive, and test new estimators which eliminate these systematic errors using information obtainable from the variation in entanglement characteristics with chain length. The new estimators produce accurate results for N_{e} from marginally entangled systems. Formulas based on direct enumeration of entanglements appear to converge faster and are simpler to apply.

Primitive Path Analysis and Stress Distribution in Highly Strained Macromolecules

PubMed Central

2017-01-01

Polymer material properties are strongly affected by entanglement effects. For long polymer chains and composite materials, they are expected to be at the origin of many technically important phenomena, such as shear thinning or the Mullins effect, which microscopically can be related to topological constraints between chains. Starting from fully equilibrated highly entangled polymer melts, we investigate the effect of isochoric elongation on the entanglement structure and force distribution of such systems. Theoretically, the related viscoelastic response usually is discussed in terms of the tube model. We relate stress relaxation in the linear and nonlinear viscoelastic regimes to a primitive path analysis (PPA) and show that tension forces both along the original paths and along primitive paths, that is, the backbone of the tube, in the stretching direction correspond to each other. Unlike homogeneous relaxation along the chain contour, the PPA reveals a so far not observed long-lived clustering of topological constraints along the chains in the deformed state. PMID:29503762

Probabilistic Modeling of High-Temperature Material Properties of a 5-Harness 0/90 Sylramic Fiber/ CVI-SiC/ MI-SiC Woven Composite

NASA Technical Reports Server (NTRS)

Nagpal, Vinod K.; Tong, Michael; Murthy, P. L. N.; Mital, Subodh

1998-01-01

An integrated probabilistic approach has been developed to assess composites for high temperature applications. This approach was used to determine thermal and mechanical properties and their probabilistic distributions of a 5-harness 0/90 Sylramic fiber/CVI-SiC/Mi-SiC woven Ceramic Matrix Composite (CMC) at high temperatures. The purpose of developing this approach was to generate quantitative probabilistic information on this CMC to help complete the evaluation for its potential application for HSCT combustor liner. This approach quantified the influences of uncertainties inherent in constituent properties called primitive variables on selected key response variables of the CMC at 2200 F. The quantitative information is presented in the form of Cumulative Density Functions (CDFs). Probability Density Functions (PDFS) and primitive variable sensitivities on response. Results indicate that the scatters in response variables were reduced by 30-50% when the uncertainties in the primitive variables, which showed the most influence, were reduced by 50%.

Exponential-fitted methods for integrating stiff systems of ordinary differential equations: Applications to homogeneous gas-phase chemical kinetics

NASA Technical Reports Server (NTRS)

Pratt, D. T.

1984-01-01

Conventional algorithms for the numerical integration of ordinary differential equations (ODEs) are based on the use of polynomial functions as interpolants. However, the exact solutions of stiff ODEs behave like decaying exponential functions, which are poorly approximated by polynomials. An obvious choice of interpolant are the exponential functions themselves, or their low-order diagonal Pade (rational function) approximants. A number of explicit, A-stable, integration algorithms were derived from the use of a three-parameter exponential function as interpolant, and their relationship to low-order, polynomial-based and rational-function-based implicit and explicit methods were shown by examining their low-order diagonal Pade approximants. A robust implicit formula was derived by exponential fitting the trapezoidal rule. Application of these algorithms to integration of the ODEs governing homogenous, gas-phase chemical kinetics was demonstrated in a developmental code CREK1D, which compares favorably with the Gear-Hindmarsh code LSODE in spite of the use of a primitive stepsize control strategy.

An evaluation of the wind chill factor: its development and applicability.

PubMed

Bluestein, M

1998-04-01

The wind chill factor has become a standard meteorologic term in cold climates. Meteorologic charts provide wind chill temperatures meant to represent the hypothetical air temperature that would, under conditions of no wind, effect the same heat loss from unclothed human skin as does the actual combination of air temperature and wind velocity. As this wind chill factor has social and economic significance, an investigation was conducted on the development of this factor and its applicability based on modern heat transfer principles. The currently used wind chill factor was found to be based on a primitive study conducted by the U.S. Antarctic Service over 50 years ago. The resultant equation for the wind chill temperature assumes an unrealistic constant skin temperature and utilizes heat transfer coefficients that differ markedly from those obtained from equations of modern convective heat transfer methods. The combined effect of these two factors is to overestimate the effect of a given wind velocity and to predict a wind chill temperature that is too low.

On solving the compressible Navier-Stokes equations for unsteady flows at very low Mach numbers

NASA Technical Reports Server (NTRS)

Pletcher, R. H.; Chen, K.-H.

1993-01-01

The properties of a preconditioned, coupled, strongly implicit finite difference scheme for solving the compressible Navier-Stokes equations in primitive variables are investigated for two unsteady flows at low speeds, namely the impulsively started driven cavity and the startup of pipe flow. For the shear-driven cavity flow, the computational effort was observed to be nearly independent of Mach number, especially at the low end of the range considered. This Mach number independence was also observed for steady pipe flow calculations; however, rather different conclusions were drawn for the unsteady calculations. In the pressure-driven pipe startup problem, the compressibility of the fluid began to significantly influence the physics of the flow development at quite low Mach numbers. The present scheme was observed to produce the expected characteristics of completely incompressible flow when the Mach number was set at very low values. Good agreement with incompressible results available in the literature was observed.

Linear hypergeneralization of learned dynamics across movement speeds reveals anisotropic, gain-encoding primitives for motor adaptation.

PubMed

Joiner, Wilsaan M; Ajayi, Obafunso; Sing, Gary C; Smith, Maurice A

2011-01-01

The ability to generalize learned motor actions to new contexts is a key feature of the motor system. For example, the ability to ride a bicycle or swing a racket is often first developed at lower speeds and later applied to faster velocities. A number of previous studies have examined the generalization of motor adaptation across movement directions and found that the learned adaptation decays in a pattern consistent with the existence of motor primitives that display narrow Gaussian tuning. However, few studies have examined the generalization of motor adaptation across movement speeds. Following adaptation to linear velocity-dependent dynamics during point-to-point reaching arm movements at one speed, we tested the ability of subjects to transfer this adaptation to short-duration higher-speed movements aimed at the same target. We found near-perfect linear extrapolation of the trained adaptation with respect to both the magnitude and the time course of the velocity profiles associated with the high-speed movements: a 69% increase in movement speed corresponded to a 74% extrapolation of the trained adaptation. The close match between the increase in movement speed and the corresponding increase in adaptation beyond what was trained indicates linear hypergeneralization. Computational modeling shows that this pattern of linear hypergeneralization across movement speeds is not compatible with previous models of adaptation in which motor primitives display isotropic Gaussian tuning of motor output around their preferred velocities. Instead, we show that this generalization pattern indicates that the primitives involved in the adaptation to viscous dynamics display anisotropic tuning in velocity space and encode the gain between motor output and motion state rather than motor output itself.

Calculations of and evidence for chain packing stress in inverse lyotropic bicontinuous cubic phases.

PubMed

Shearman, Gemma C; Khoo, Bee J; Motherwell, Mary-Lynn; Brakke, Kenneth A; Ces, Oscar; Conn, Charlotte E; Seddon, John M; Templer, Richard H

2007-06-19

Inverse bicontinuous cubic lyotropic phases are a complex solution to the dilemma faced by all self-assembled water-amphiphile systems: how to satisfy the incompatible requirements for uniform interfacial curvature and uniform molecular packing. The solution reached in this case is for the water-amphiphile interfaces to deform hyperbolically onto triply periodic minimal surfaces. We have previously suggested that although the molecular packing in these structures is rather uniform the relative phase behavior of the gyroid, double diamond, and primitive inverse bicontinuous cubic phases can be understood in terms of subtle differences in packing frustration. In this work, we have calculated the packing frustration for these cubics under the constraint that their interfaces have constant mean curvature. We find that the relative packing stress does indeed differ between phases. The gyroid cubic has the least packing stress, and at low water volume fraction, the primitive cubic has the greatest packing stress. However, at very high water volume fraction, the double diamond cubic becomes the structure with the greatest packing stress. We have tested the model in two ways. For a system with a double diamond cubic phase in excess water, the addition of a hydrophobe may release packing frustration and preferentially stabilize the primitive cubic, since this has previously been shown to have lower curvature elastic energy. We have confirmed this prediction by adding the long chain alkane tricosane to 1-monoolein in excess water. The model also predicts that if one were able to hydrate the double diamond cubic to high water volume fractions, one should destabilize the phase with respect to the primitive cubic. We have found that such highly swollen metastable bicontinuous cubic phases can be formed within onion vesicles. Data from monoelaidin in excess water display a well-defined transition, with the primitive cubic appearing above a water volume fraction of 0.75. Both of these results lend support to the proposition that differences in the packing frustration between inverse bicontinuous cubic phases play a pivotal role in their relative phase stability.

Western boundary upwelling dynamics off Oman

NASA Astrophysics Data System (ADS)

Vic, Clément; Capet, Xavier; Roullet, Guillaume; Carton, Xavier

2017-05-01

Despite its climatic and ecosystemic significance, the coastal upwelling that takes place off Oman is not well understood. A primitive-equation, regional model forced by climatological wind stress is used to investigate its dynamics and to compare it with the better-known Eastern Boundary Upwellings (EBUs). The solution compares favorably with existing observations, simulating well the seasonal cycles of thermal structure, surface circulation (mean and turbulent), and sea-surface temperature (SST). There is a 1.5-month lag between the maximum of the upwelling-favorable wind-stress-curl forcing and the oceanic response (minima in sea-surface height and SST), which we attribute to onshore-propagating Rossby waves. A southwestward-flowing undercurrent (opposite to the direction of the near-surface flow) is also simulated with a core depth of 1000 m, much deeper than found in EBUs (150-200 m). An EKE budget reveals that, in contrast to EBUs, the upwelling jet is more prone to barotropic than baroclinic instability and the contribution of locally-generated instabilities to EKE is higher by an order of magnitude. Advection and redistribution of EKE by standing mesoscale features also play a significant role in EKE budget.

An examination of relationship between neurological soft signs and neurocognition.

PubMed

Solanki, Ram Kumar; Swami, Mukesh Kumar; Singh, Paramjeet

2012-03-01

Neurological soft signs (NSS) and cognitive function had been examined in schizophrenia, but their relationship has remained elusive for several years. We examined the relationship between NSS and cognitive functions in the present study. A cross sectional study was carried out. Subjects were drawn from first degree relatives of schizophrenia patients, admitted as inpatient or attending as an outpatient. Controls were recruited by word of mouth from hospital staff and visitors of hospitalized patients. Those subjects who satisfied the screening process were subjected to Cambridge Neurological Inventory for soft sign assessment and digit span test, paired associate learning test (PALT) and visuo-spatial working memory matrix (VSWMM) for cognitive function assessment. Correlation analysis and structural equation modeling (SEM) was used for analysis. Significant negative correlation of primitive reflexes with PALT; of motor coordination with VSWMM, working memory (WM) and cognitive index; of total NSS with WM and cognitive index among first degree relatives. SEM showed that motor soft signs have important negative influence over WM. The current findings indicate that NSS have significant negative effect on cognitive functioning. Copyright © 2011 Elsevier B.V. All rights reserved.

Efficient Agent-Based Models for Non-Genomic Evolution

NASA Technical Reports Server (NTRS)

Gupta, Nachi; Agogino, Adrian; Tumer, Kagan

2006-01-01

Modeling dynamical systems composed of aggregations of primitive proteins is critical to the field of astrobiological science involving early evolutionary structures and the origins of life. Unfortunately traditional non-multi-agent methods either require oversimplified models or are slow to converge to adequate solutions. This paper shows how to address these deficiencies by modeling the protein aggregations through a utility based multi-agent system. In this method each agent controls the properties of a set of proteins assigned to that agent. Some of these properties determine the dynamics of the system, such as the ability for some proteins to join or split other proteins, while additional properties determine the aggregation s fitness as a viable primitive cell. We show that over a wide range of starting conditions, there are mechanisins that allow protein aggregations to achieve high values of overall fitness. In addition through the use of agent-specific utilities that remain aligned with the overall global utility, we are able to reach these conclusions with 50 times fewer learning steps.

Entropic effects in the electric double layer of model colloids with size-asymmetric monovalent ions

NASA Astrophysics Data System (ADS)

Guerrero-García, Guillermo Iván; González-Tovar, Enrique; Olvera de la Cruz, Mónica

2011-08-01

The structure of the electric double layer of charged nanoparticles and colloids in monovalent salts is crucial to determine their thermodynamics, solubility, and polyion adsorption. In this work, we explore the double layer structure and the possibility of charge reversal in relation to the size of both counterions and coions. We examine systems with various size-ratios between counterions and coions (ion size asymmetries) as well as different total ion volume fractions. Using Monte Carlo simulations and integral equations of a primitive-model electric double layer, we determine the highest charge neutralization and electrostatic screening near the electrified surface. Specifically, for two binary monovalent electrolytes with the same counterion properties but differing only in the coion's size surrounding a charged nanoparticle, the one with largest coion size is found to have the largest charge neutralization and screening. That is, in size-asymmetric double layers with a given counterion's size the excluded volume of the coions dictates the adsorption of the ionic charge close to the colloidal surface for monovalent salts. Furthermore, we demonstrate that charge reversal can occur at low surface charge densities, given a large enough total ion concentration, for systems of monovalent salts in a wide range of ion size asymmetries. In addition, we find a non-monotonic behavior for the corresponding maximum charge reversal, as a function of the colloidal bare charge. We also find that the reversal effect disappears for binary salts with large-size counterions and small-size coions at high surface charge densities. Lastly, we observe a good agreement between results from both Monte Carlo simulations and the integral equation theory across different colloidal charge densities and 1:1-elec-trolytes with different ion sizes.

Transitions between discrete and rhythmic primitives in a unimanual task

PubMed Central

Sternad, Dagmar; Marino, Hamal; Charles, Steven K.; Duarte, Marcos; Dipietro, Laura; Hogan, Neville

2013-01-01

Given the vast complexity of human actions and interactions with objects, we proposed that control of sensorimotor behavior may utilize dynamic primitives. However, greater computational simplicity may come at the cost of reduced versatility. Evidence for primitives may be garnered by revealing such limitations. This study tested subjects performing a sequence of progressively faster discrete movements in order to “stress” the system. We hypothesized that the increasing pace would elicit a transition to rhythmic movements, assumed to be computationally and neurally more efficient. Abrupt transitions between the two types of movements would support the hypothesis that rhythmic and discrete movements are distinct primitives. Ten subjects performed planar point-to-point arm movements paced by a metronome: starting at 2 s, the metronome intervals decreased by 36 ms per cycle to 200 ms, stayed at 200 ms for several cycles, then increased by similar increments. Instructions emphasized to insert explicit stops between each movement with a duration that equaled the movement time. The experiment was performed with eyes open and closed, and with short and long metronome sounds, the latter explicitly specifying the dwell duration. Results showed that subjects matched instructed movement times but did not preserve the dwell times. Rather, they progressively reduced dwell time to zero, transitioning to continuous rhythmic movements before movement times reached their minimum. The acceleration profiles showed an abrupt change between discrete and rhythmic profiles. The loss of dwell time occurred earlier with long auditory specification, when subjects also showed evidence of predictive control. While evidence for hysteresis was weak, taken together, the results clearly indicated a transition between discrete and rhythmic movements, supporting the proposal that representation is based on primitives rather than on veridical internal models. PMID:23888139

Use of Optical Storage Devices as Shared Resources in Local Area Networks

DTIC Science & Technology

1989-09-01

13 3. SERVICE CALLS FOR MS-DOS CD-ROM EXTENSIONS . 14 4. MS-DOS PRIMITIVE GROUPS ....................... 15 5. RAM USAGE FOR VARIOUS LAN...17 2. Service Call Translation to DOS Primitives ............. 19 3. MS-DOS Device Drivers ............................. 21 4. MS-DOS/ROM...directed to I/O devices will be referred to as primitive instruction groups). These primitive instruction groups include keyboard, video, disk, serial

Modeling discrete and rhythmic movements through motor primitives: a review.

PubMed

Degallier, Sarah; Ijspeert, Auke

2010-10-01

Rhythmic and discrete movements are frequently considered separately in motor control, probably because different techniques are commonly used to study and model them. Yet the increasing interest in finding a comprehensive model for movement generation requires bridging the different perspectives arising from the study of those two types of movements. In this article, we consider discrete and rhythmic movements within the framework of motor primitives, i.e., of modular generation of movements. In this way we hope to gain an insight into the functional relationships between discrete and rhythmic movements and thus into a suitable representation for both of them. Within this framework we can define four possible categories of modeling for discrete and rhythmic movements depending on the required command signals and on the spinal processes involved in the generation of the movements. These categories are first discussed in terms of biological concepts such as force fields and central pattern generators and then illustrated by several mathematical models based on dynamical system theory. A discussion on the plausibility of theses models concludes the work.

Field and numerical studies of flow structure in Lake Shira (Khakassia) in summer

NASA Astrophysics Data System (ADS)

Yakubaylik, Tatyana; Kompaniets, Lidia

2014-05-01

Investigations of Lake Shira are conducted within a multidisciplinary approach that includes the study of biodiversity, biochemistry, geology of lake sediments, as well as its hydrophysics. Our report focuses on field measurements in the lake during the 2009 - 2013 and numerical modeling of flow structure. The flow velocity, temperature and salinity distribution and fluctuations of the thermocline (density) were measured in summer. An analysis of spatial and temporal variability of the major hydrophysical characteristics leads us to conclusion that certain meteorological conditions may cause internal waves in this lake. Digital terrain model is constructed from measurements of Lake bathymetry allowing us to carry out numerical simulation. Three-dimensional primitive equation numerical model GETM is applied to simulate hydrophysical processes in Lake Shira. The model is hydrostatic and Boussinesq. An algorithm of high order approximation is opted for calculating the equations of heat and salt transfer. Temperature and salinity distributions resulting from field observations are taken as initial data for numerical simulations. Model calculations as well as calculations with appropriate real wind pattern being observed on Lake Shira have been carried out. In the model calculations we follow (1). Significant differences are observed between model calculations with constant wind and calculations with real wind pattern. Unsteady wind pattern leads to the appearance of horizontal vortexes and a significant increase of vertical fluctuations in temperature (density, impurities). It causes lifting of the sediments to the upper layers at the areas where the thermocline contacts the bottom. It is important for understanding the overall picture of the processes occurring in the lake in summer. Comparison of the results of numerical experiments with the field data shows the possibility of such a phenomena in Lake Shira. The work was supported by the Russian Foundation for Fundamental Studies under Grant 13-05-00853 and interdisciplinary integration project of SB RAS 56. REFERENCES 1. Beletsky D. Numerical Simulation of Internal Kelvin Waves and Coastal Upwelling Fronts. D. Beletsky, W. P. O'Connor J. of Physical Oceanography. - v.27. - July 1997. - P. 1197-1215.

Regional forecasting system of marine state and variability of dynamical processes in the easternmost part of the Black Sea

NASA Astrophysics Data System (ADS)

Kordzadze, Avtandil; Demetrashvili, Demuri

2014-05-01

The regional forecasting system for the easternmost part of the Black Sea developed at M. Nodia Institute of Geophysics of I. Javakhishvili Tbilisi State University under the EU framework projects ARENA and ECOOP is a part of the Black Sea basin-scale Nowcasting/Forecasting System. A core of the regional forecasting system is a baroclinic regional model of Black Sea dynamics with 1 km spacing based on hydrostatic primitive equations of ocean hydrothermodynamics, which are written in z-coordinates for deviations of thermodynamic values from their standard vertical distributions. To solve the problem the two-cycle method of splitting the model equation system with respect to both physical processes and coordinate planes and lines is used. The regional model of M. Nodia Institute of Geophysics is nested in the basin-scale model of Black Sea dynamics of Marine Hydrophysical Institute (Sevastopol/Ukraine). The regional forecasting system provides 3 days' forecasts of current, temperature and salinity for the easternmost part of the Black Sea, which is limited to the Caucasian and Turkish coastal lines and the western liquid boundary coinciding with the meridian 39.080E. Data needed on liquid and upper boundaries, also the 3-D initial hydrophysical fields for the easternmost regional area are provided in near operative mode from Marine hydrophysical Institute via Internet. These data on the liquid boundary are values of velocity components, temperature and salinity predicted by the basin-scale model of Black Sea dynamics of Marine Hydrophysical Institute and on the sea surface 2-D meteorological boundary fields - wind stress, heat fluxes, evaporation and precipitation rates predicted by the regional atmospheric model ALADIN are used. The analysis of the results of modeling and forecast of dynamic processes developed for 2010-2014 showed that the easternmost water area of the Black Sea is a dynamically very active zone, where continuously there are processes of generation, deformation and disappearance of the cyclonic and anticyclonic vortex formations of different sizes. Acknowledgement. The significant part of the researches was supported by the Shota Rustaveli National Science Foundation, Grant No. AR/373/9-120/12.

Intercomparison of general circulation models for hot extrasolar planets

NASA Astrophysics Data System (ADS)

Polichtchouk, I.; Cho, J. Y.-K.; Watkins, C.; Thrastarson, H. Th.; Umurhan, O. M.; de la Torre Juárez, M.

2014-02-01

We compare five general circulation models (GCMs) which have been recently used to study hot extrasolar planet atmospheres (BOB, CAM, IGCM, MITgcm, and PEQMOD), under three test cases useful for assessing model convergence and accuracy. Such a broad, detailed intercomparison has not been performed thus far for extrasolar planets study. The models considered all solve the traditional primitive equations, but employ different numerical algorithms or grids (e.g., pseudospectral and finite volume, with the latter separately in longitude-latitude and ‘cubed-sphere’ grids). The test cases are chosen to cleanly address specific aspects of the behaviors typically reported in hot extrasolar planet simulations: (1) steady-state, (2) nonlinearly evolving baroclinic wave, and (3) response to fast timescale thermal relaxation. When initialized with a steady jet, all models maintain the steadiness, as they should-except MITgcm in cubed-sphere grid. A very good agreement is obtained for a baroclinic wave evolving from an initial instability in pseudospectral models (only). However, exact numerical convergence is still not achieved across the pseudospectral models: amplitudes and phases are observably different. When subject to a typical ‘hot-Jupiter’-like forcing, all five models show quantitatively different behavior-although qualitatively similar, time-variable, quadrupole-dominated flows are produced. Hence, as have been advocated in several past studies, specific quantitative predictions (such as the location of large vortices and hot regions) by GCMs should be viewed with caution. Overall, in the tests considered here, pseudospectral models in pressure coordinate (PEBOB and PEQMOD) perform the best and MITgcm in cubed-sphere grid performs the worst.

Development and Application of a Cohesive Sediment Transport Model in Coastal Louisiana

NASA Astrophysics Data System (ADS)

Sorourian, S.; Nistor, I.

2017-12-01

The Louisiana coast has suffered from rapid land loss due to the combined effects of increasing the rate of eustatic sea level rise, insufficient riverine sediment input and subsidence. The sediment in this region is dominated by cohesive sediments (up to 80% of clay). This study presents a new model for calculating suspended sediment concentration (SSC) of cohesive sediments. Several new concepts are incorporated into the proposed model, which is capable of estimating the spatial and temporal variation in the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed in time-dependent form. Simulated SSC profiles are compared with field data collected from Vermilion Bay, Louisiana. The results of the proposed model agree well with the experimental data, as soon as steady state condition is achieved. The results of the new numerical models provide a better estimation of the suspended sediment concentration profile compared to the initial model developed by Mehta and Li, 2003. Among the proposed developments, the formulation of a time-dependent erosion rate shows the most accurate results. Coupling of present model with the Finite-Volume, primitive equation Community Ocean Model (FVCOM) would shed light on the fate of fine-grained sediments in order to increase overall retention and restoration of the Louisiana coastal plain.

Method for concurrent execution of primitive operations by dynamically assigning operations based upon computational marked graph and availability of data

NASA Technical Reports Server (NTRS)

Mielke, Roland V. (Inventor); Stoughton, John W. (Inventor)

1990-01-01

Computationally complex primitive operations of an algorithm are executed concurrently in a plurality of functional units under the control of an assignment manager. The algorithm is preferably defined as a computationally marked graph contianing data status edges (paths) corresponding to each of the data flow edges. The assignment manager assigns primitive operations to the functional units and monitors completion of the primitive operations to determine data availability using the computational marked graph of the algorithm. All data accessing of the primitive operations is performed by the functional units independently of the assignment manager.

How to Spot a Primitive Black Hole

NASA Image and Video Library

2010-03-17

These two data plots from NASA Spitzer Space Telescope show a primitive supermassive black hole top compared to a typical one; usually, dust tori are missing and only gas disks are observed in primitive black holes.

The Repeated Replacement Method: A Pure Lagrangian Meshfree Method for Computational Fluid Dynamics

PubMed Central

Walker, Wade A.

2012-01-01

In this paper we describe the repeated replacement method (RRM), a new meshfree method for computational fluid dynamics (CFD). RRM simulates fluid flow by modeling compressible fluids’ tendency to evolve towards a state of constant density, velocity, and pressure. To evolve a fluid flow simulation forward in time, RRM repeatedly “chops out” fluid from active areas and replaces it with new “flattened” fluid cells with the same mass, momentum, and energy. We call the new cells “flattened” because we give them constant density, velocity, and pressure, even though the chopped-out fluid may have had gradients in these primitive variables. RRM adaptively chooses the sizes and locations of the areas it chops out and replaces. It creates more and smaller new cells in areas of high gradient, and fewer and larger new cells in areas of lower gradient. This naturally leads to an adaptive level of accuracy, where more computational effort is spent on active areas of the fluid, and less effort is spent on inactive areas. We show that for common test problems, RRM produces results similar to other high-resolution CFD methods, while using a very different mathematical framework. RRM does not use Riemann solvers, flux or slope limiters, a mesh, or a stencil, and it operates in a purely Lagrangian mode. RRM also does not evaluate numerical derivatives, does not integrate equations of motion, and does not solve systems of equations. PMID:22866175

Fully automatic adjoints: a robust and efficient mechanism for generating adjoint ocean models

NASA Astrophysics Data System (ADS)

Ham, D. A.; Farrell, P. E.; Funke, S. W.; Rognes, M. E.

2012-04-01

The problem of generating and maintaining adjoint models is sufficiently difficult that typically only the most advanced and well-resourced community ocean models achieve it. There are two current technologies which each suffer from their own limitations. Algorithmic differentiation, also called automatic differentiation, is employed by models such as the MITGCM [2] and the Alfred Wegener Institute model FESOM [3]. This technique is very difficult to apply to existing code, and requires a major initial investment to prepare the code for automatic adjoint generation. AD tools may also have difficulty with code employing modern software constructs such as derived data types. An alternative is to formulate the adjoint differential equation and to discretise this separately. This approach, known as the continuous adjoint and employed in ROMS [4], has the disadvantage that two different model code bases must be maintained and manually kept synchronised as the model develops. The discretisation of the continuous adjoint is not automatically consistent with that of the forward model, producing an additional source of error. The alternative presented here is to formulate the flow model in the high level language UFL (Unified Form Language) and to automatically generate the model using the software of the FEniCS project. In this approach it is the high level code specification which is differentiated, a task very similar to the formulation of the continuous adjoint [5]. However since the forward and adjoint models are generated automatically, the difficulty of maintaining them vanishes and the software engineering process is therefore robust. The scheduling and execution of the adjoint model, including the application of an appropriate checkpointing strategy is managed by libadjoint [1]. In contrast to the conventional algorithmic differentiation description of a model as a series of primitive mathematical operations, libadjoint employs a new abstraction of the simulation process as a sequence of discrete equations which are assembled and solved. It is the coupling of the respective abstractions employed by libadjoint and the FEniCS project which produces the adjoint model automatically, without further intervention from the model developer. This presentation will demonstrate this new technology through linear and non-linear shallow water test cases. The exceptionally simple model syntax will be highlighted and the correctness of the resulting adjoint simulations will be demonstrated using rigorous convergence tests.

Symbol Recognition Using a Concept Lattice of Graphical Patterns

NASA Astrophysics Data System (ADS)

Rusiñol, Marçal; Bertet, Karell; Ogier, Jean-Marc; Lladós, Josep

In this paper we propose a new approach to recognize symbols by the use of a concept lattice. We propose to build a concept lattice in terms of graphical patterns. Each model symbol is decomposed in a set of composing graphical patterns taken as primitives. Each one of these primitives is described by boundary moment invariants. The obtained concept lattice relates which symbolic patterns compose a given graphical symbol. A Hasse diagram is derived from the context and is used to recognize symbols affected by noise. We present some preliminary results over a variation of the dataset of symbols from the GREC 2005 symbol recognition contest.

Primitive Sca-1 Positive Bone Marrow HSC in Mouse Model of Aplastic Anemia: A Comparative Study through Flowcytometric Analysis and Scanning Electron Microscopy

PubMed Central

Chatterjee, Sumanta; Basak, Pratima; Das, Prosun; Das, Madhurima; Pereira, Jacintha Archana; Dutta, Ranjan Kumar; Chaklader, Malay; Chaudhuri, Samaresh; Law, Sujata

2010-01-01

Self-renewing Hematopoietic Stem Cells (HSCs) are responsible for reconstitution of all blood cell lineages. Sca-1 is the “stem cell antigen” marker used to identify the primitive murine HSC population, the expression of which decreases upon differentiation to other mature cell types. Sca-1+ HSCs maintain the bone marrow stem cell pool throughout the life. Aplastic anemia is a disease considered to involve primary stem cell deficiency and is characterized by severe pancytopenia and a decline in healthy blood cell generation system. Studies conducted in our laboratory revealed that the primitive Sca-1+ BM-HSCs (bone marrow hematopoietic stem cell) are significantly affected in experimental Aplastic animals pretreated with chemotherapeutic drugs (Busulfan and Cyclophosphamide) and there is increased Caspase-3 activity with consecutive high Annexin-V positivity leading to premature apoptosis in the bone marrow hematopoietic stem cell population in Aplastic condition. The Sca-1bright, that is, “more primitive” BM-HSC population was more affected than the “less primitive” BM-HSC Sca-1dim  population. The decreased cell population and the receptor expression were directly associated with an empty and deranged marrow microenvironment, which is evident from scanning electron microscopy (SEM). The above experimental evidences hint toward the manipulation of receptor expression for the benefit of cytotherapy by primitive stem cell population in Aplastic anemia cases. PMID:21048851

A key heterogeneous structure of fractal networks based on inverse renormalization scheme

NASA Astrophysics Data System (ADS)

Bai, Yanan; Huang, Ning; Sun, Lina

2018-06-01

Self-similarity property of complex networks was found by the application of renormalization group theory. Based on this theory, network topologies can be classified into universality classes in the space of configurations. In return, through inverse renormalization scheme, a given primitive structure can grow into a pure fractal network, then adding different types of shortcuts, it exhibits different characteristics of complex networks. However, the effect of primitive structure on networks structural property has received less attention. In this paper, we introduce a degree variance index to measure the dispersion of nodes degree in the primitive structure, and investigate the effect of the primitive structure on network structural property quantified by network efficiency. Numerical simulations and theoretical analysis show a primitive structure is a key heterogeneous structure of generated networks based on inverse renormalization scheme, whether or not adding shortcuts, and the network efficiency is positively correlated with degree variance of the primitive structure.

Discovery of survival factor for primitive chronic myeloid leukemia cells using induced pluripotent stem cells

PubMed Central

Suknuntha, Kran; Ishii, Yuki; Tao, Lihong; Hu, Kejin; McIntosh, Brian E.; Yang, David; Swanson, Scott; Stewart, Ron; Wang, Jean Y.J.; Thomson, James; Slukvin, Igor

2016-01-01

A definitive cure for chronic myeloid leukemia (CML) requires identifying novel therapeutic targets to eradicate leukemia stem cells (LSCs). However, the rarity of LSCs within the primitive hematopoietic cell compartment remains a major limiting factor for their study in humans. Here we show that primitive hematopoietic cells with typical LSC features, including adhesion defect, increased long-term survival and proliferation, and innate resistance to tyrosine kinase inhibitor (TKI) imatinib, can be generated de novo from reprogrammed primary CML cells. Using CML iPSC-derived primitive leukemia cells, we discovered olfactomedin 4 (OLFM4) as a novel factor that contributes to survival and growth of somatic lin−CD34+ cells from bone marrow of patients with CML in chronic phase, but not primitive hematopoietic cells from normal bone marrow. Overall, this study shows the feasibility and advantages of using reprogramming technology to develop strategies for targeting primitive leukemia cells. PMID:26561938

SSM - SOLID SURFACE MODELER, VERSION 6.0

NASA Technical Reports Server (NTRS)

Goza, S. P.

1994-01-01

The Solid Surface Modeler (SSM) is an interactive graphics software application for solid-shaded and wireframe three- dimensional geometric modeling. It enables the user to construct models of real-world objects as simple as boxes or as complex as Space Station Freedom. The program has a versatile user interface that, in many cases, allows mouse input for intuitive operation or keyboard input when accuracy is critical. SSM can be used as a stand-alone model generation and display program and offers high-fidelity still image rendering. Models created in SSM can also be loaded into other software for animation or engineering simulation. (See the information below for the availability of SSM with the Object Orientation Manipulator program, OOM, a graphics software application for three-dimensional rendering and animation.) Models are constructed within SSM using functions of the Create Menu to create, combine, and manipulate basic geometric building blocks called primitives. Among the simpler primitives are boxes, spheres, ellipsoids, cylinders, and plates; among the more complex primitives are tubes, skinned-surface models and surfaces of revolution. SSM also provides several methods for duplicating models. Constructive Solid Geometry (CSG) is one of the most powerful model manipulation tools provided by SSM. The CSG operations implemented in SSM are union, subtraction and intersection. SSM allows the user to transform primitives with respect to each axis, transform the camera (the user's viewpoint) about its origin, apply texture maps and bump maps to model surfaces, and define color properties; to select and combine surface-fill attributes, including wireframe, constant, and smooth; and to specify models' points of origin (the positions about which they rotate). SSM uses Euler angle transformations for calculating the results of translation and rotation operations. The user has complete control over the modeling environment from within the system. A variety of file formats are supported to facilitate modification of models and to provide for translation to other formats. This combination of features makes SSM valuable for research and development beyond its intended role in the creation of simulation and animation models. SSM makes an important distinction between models, objects, and surfaces. Models consist of one or more objects and are the highest level geometric entity upon which SSM operates. File operations are performed solely at the model level. (All primitives are models consisting of a single object.) The majority of SSM's manipulation functions operate at the object level. Objects consist of one or more surfaces and surfaces may consist of one or more polygons, which are the structural basis for the modeling method used by SSM. Surfaces are the lowest-level geometric entity upon which SSM operates. Surface-fill attributes, for example, may be assigned at the surface level. Surfaces cannot exist except as part of an object and objects cannot exist except as part of a model. SSM can simultaneously accommodate as many models as the host computer's memory permits. In its default display mode, SSM renders model surfaces using two shading methods: constant shading and smooth shading. Constant shading reveals each polygon of an object's surfaces, giving the object an angular appearance. Smooth shading causes an object's polygons to blend into one another, giving its surfaces a smooth, continuous appearance. When used in proper combination, each of these methods contribute to object realism. SSM applies each method automatically during the creation of primitives, but the user can manually override the default settings. Both fill attributes and shading characteristics can be defined for individual surfaces, objects, and models. SSM provides two optional display modes for reducing rendering time for complex models. In wireframe mode, SSM represents all model geometry data in unshaded line drawings, and no hidden-surface removal is performed. In simple mode, only the outermost boundaries (or bounding volume) that define each model are depicted. In either case the user is allowed to trade off visual authenticity for update speed. SSM is written in C-language for implementation on SGI IRIS 4D series workstations running the IRIX operating system. A minimum of 8Mb of RAM is recommended for this program. The standard distribution medium for SSM is a .25 inch streaming magnetic IRIX tape cartridge in UNIX tar format. SSM is also offered as a bundle with a related program, OOM (Object Orientation Manipulator). Please see the abstract for SSM/OOM (COS-10047) for information about the bundled package. Version 6.0 of SSM was released in 1993.

Drake Equation for the Multiverse:. from the String Landscape to Complex Life

NASA Astrophysics Data System (ADS)

Gleiser, M.

It is argued that the selection criteria usually referred to as "anthropic conditions" for the existence of intelligent (typical) observers widely adopted in cosmology amount only to preconditions for primitive life. The existence of life does not imply in the existence of intelligent life. On the contrary, the transition from single-celled to complex, multicellular organisms is far from trivial, requiring stringent additional conditions on planetary platforms. An attempt is made to disentangle the necessary steps leading from a selection of universes out of a hypothetical multiverse to the existence of life and of complex life. It is suggested that what is currently called the "anthropic principle" should instead be named the "prebiotic principle."

Operational environmental assessment "Prestige" (a recent application of the MOCASSIM system).

NASA Astrophysics Data System (ADS)

Vitorino, J.; Rusu, E.; Almeida, S.; Monteiro, M.; Lermusiaux, P.; Haley, P.; Leslie, W.; Miller, P.; Coelho, E.; Signell, R.

2003-04-01

The sinking of tanker "Prestige", on the 19th November 2002, offshore the northwestern coasts of Spain and Portugal, has lead to a major environmental disaster. In this contribution we present several aspects of the operational environmental assessment "Prestige" conducted by Instituto Hidrografico (IH) in close colaboration with Instituto de Meteorologia (IM), the Harvard University, the Plymouth Marine Laboratory (PML) and the Saclancentre. The operational system MOCASSIM, which is presently being developed at IH, was used to provide forecasts of the evolution of oceanographic conditions offshore the NW Iberian coast. The system integrates a primitive equation model with data assimilation (the Harvard Ocean Prediction System - HOPS) and two wave models (the SWAN and WW3 models). The numerical domains used in both HOPS and SWAN models covered the area bewteen 40ºN and 46ºN and from 7ºW to 15ºW, and included the sinking area as well as the coastal regions more directly exposed to the oil spill. The models were run with atmospheric forcing conditions provided by the limited area model ALADIN, run operationally at IM, complemented with NOGAPS wind fields from the NATO METOC site of Rota. The HOPS simulations included assimilation of several data available for region. These data sets included CTD casts from the Northern Spanish shelf and slope (made available by University of Baleares) and SST data processed at the Remote Sensing Group of the PML. Results from both models were used in oil spill models and allowed an estimation of the impacts on the coastal areas.

A mutli-technique search for the most primitive CO chondrites

NASA Astrophysics Data System (ADS)

Alexander, C. M. O'D.; Greenwood, R. C.; Bowden, R.; Gibson, J. M.; Howard, K. T.; Franchi, I. A.

2018-01-01

As part of a study to identify the most primitive COs and to look for weakly altered CMs amongst the COs, we have conducted a multi-technique study of 16 Antarctic meteorites that had been classified as primitive COs. For this study, we have determined: (1) the bulk H, C and N abundances and isotopes, (2) bulk O isotopic compositions, (3) bulk modal mineralogies, and (4) for some selected samples the abundances and compositions of their insoluble organic matter (IOM). Two of the 16 meteorites do appear to be CMs - BUC 10943 seems to be a fairly typical CM, while MIL 090073 has probably been heated. Of the COs, DOM 08006 appears to be the most primitive CO identified to date and is quite distinct from the other members of its pairing group. The other COs fall into two groups that are less primitive than DOM 08006 and ALH 77307, the previously most primitive CO. The first group is composed of members of the DOM 08004 pairing group, except DOM 08006. The second group is composed of meteorites belonging to the MIL 03377 and MIL 07099 pairing groups. These two pairing groups should probably be combined. There is a dichotomy in the bulk O isotopes between the primitive (all Antarctic finds) and the more metamorphosed COs (mostly falls). This dichotomy can only partly be explained by the terrestrial weathering experienced by the primitive Antarctic samples. It seems that the more equilibrated samples interacted to a greater extent with 16O-poor material, probably water, than the more primitive meteorites.

Dynamic primitives in the control of locomotion.

PubMed

Hogan, Neville; Sternad, Dagmar

2013-01-01

Humans achieve locomotor dexterity that far exceeds the capability of modern robots, yet this is achieved despite slower actuators, imprecise sensors, and vastly slower communication. We propose that this spectacular performance arises from encoding motor commands in terms of dynamic primitives. We propose three primitives as a foundation for a comprehensive theoretical framework that can embrace a wide range of upper- and lower-limb behaviors. Building on previous work that suggested discrete and rhythmic movements as elementary dynamic behaviors, we define submovements and oscillations: as discrete movements cannot be combined with sufficient flexibility, we argue that suitably-defined submovements are primitives. As the term "rhythmic" may be ambiguous, we define oscillations as the corresponding class of primitives. We further propose mechanical impedances as a third class of dynamic primitives, necessary for interaction with the physical environment. Combination of these three classes of primitive requires care. One approach is through a generalized equivalent network: a virtual trajectory composed of simultaneous and/or sequential submovements and/or oscillations that interacts with mechanical impedances to produce observable forces and motions. Reliable experimental identification of these dynamic primitives presents challenges: identification of mechanical impedances is exquisitely sensitive to assumptions about their dynamic structure; identification of submovements and oscillations is sensitive to their assumed form and to details of the algorithm used to extract them. Some methods to address these challenges are presented. Some implications of this theoretical framework for locomotor rehabilitation are considered.

LEGO-MM: LEarning structured model by probabilistic loGic Ontology tree for MultiMedia.

PubMed

Tang, Jinhui; Chang, Shiyu; Qi, Guo-Jun; Tian, Qi; Rui, Yong; Huang, Thomas S

2016-09-22

Recent advances in Multimedia ontology have resulted in a number of concept models, e.g., LSCOM and Mediamill 101, which are accessible and public to other researchers. However, most current research effort still focuses on building new concepts from scratch, very few work explores the appropriate method to construct new concepts upon the existing models already in the warehouse. To address this issue, we propose a new framework in this paper, termed LEGO1-MM, which can seamlessly integrate both the new target training examples and the existing primitive concept models to infer the more complex concept models. LEGOMM treats the primitive concept models as the lego toy to potentially construct an unlimited vocabulary of new concepts. Specifically, we first formulate the logic operations to be the lego connectors to combine existing concept models hierarchically in probabilistic logic ontology trees. Then, we incorporate new target training information simultaneously to efficiently disambiguate the underlying logic tree and correct the error propagation. Extensive experiments are conducted on a large vehicle domain data set from ImageNet. The results demonstrate that LEGO-MM has significantly superior performance over existing state-of-the-art methods, which build new concept models from scratch.

Surface signature of Mediterranean water eddies in a long-term high-resolution simulation

NASA Astrophysics Data System (ADS)

Ciani, D.; Carton, X.; Barbosa Aguiar, A. C.; Peliz, A.; Bashmachnikov, I.; Ienna, F.; Chapron, B.; Santoleri, R.

2017-12-01

We study the surface signatures of Mediterranean water eddies (Meddies) in the context of a regional, primitive equations model simulation (using the Regional Oceanic Modeling System, ROMS). This model simulation was previously performed to study the mean characteristics and pathways of Meddies during their evolution in the Atlantic Ocean. The advantage of our approach is to take into account different physical mechanisms acting on the evolution of Meddies and their surface signature, having full information on the 3D distribution of all physical variables of interest. The evolution of around 90 long-lived Meddies (whose lifetimes exceeded one year) was investigated. In particular, their surface signature was determined in sea-surface height, temperature and salinity. The Meddy-induced anomalies were studied as a function of the Meddy structure and of the oceanic background. We show that the Meddies can generate positive anomalies in the elevation of the oceanic free-surface and that these anomalies are principally related to the Meddies potential vorticity structure at depth (around 1000 m below the sea-surface). On the contrary, the Meddies thermohaline surface signatures proved to be mostly dominated by local surface conditions and little correlated to the Meddy structure at depth. This work essentially points out that satellite altimetry is the most suitable approach to track subsurface vortices from observations of the sea-surface.

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: a partially perturbative density functional theory study.

PubMed

Peng, Bo; Yu, Yang-Xin

2009-10-07

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Intraseasonal and Interannual Variability of Mars Present Climate

NASA Astrophysics Data System (ADS)

Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

1996-01-01

This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. The focus of this JRI has been to investigate the nature of intraseasonal and interannual variability of Mars'present climate. We have applied a three-dimensional climate model based on the full hydrostatic primitive equations to determine the spatial, but primarily, the temporal structures of the planet's large-scale circulation as it evolves during a given seasonal advance, and, over multi-annual cycles. The particular climate model applies simplified physical parameterizations and is computationally efficient. It could thus easily be integrated in a perpetual season or advancing season configuration, as well as over many Mars years. We have assessed both high and low-frequency components of the circulation (i.e., motions having periods of Omicron(2-10 days) or greater than Omicron(10 days), respectively). Results from this investigation have explored the basic issue whether Mars' climate system is naturally 'chaotic' associated with nonlinear interactions of the large-scale circulation-regardless of any allowance for year-to-year variations in external forcing mechanisms. Titles of papers presented at scientific conferences and a manuscript to be submitted to the scientific literature are provided. An overview of a areas for further investigation is also presented.

Intrathermocline eddies in the coastal transition zone off central Chile (31-41°S)

NASA Astrophysics Data System (ADS)

Hormazabal, Samuel; Combes, Vincent; Morales, Carmen E.; Correa-Ramirez, Marco A.; Di Lorenzo, Emmanuel; Nuñez, Sergio

2013-10-01

The three-dimensional structure and the origin of mesoscale anticyclonic intrathermocline eddies (ITEs) in the coastal transition zone (CTZ) off central Chile (31-41°S) were analyzed through the combination of data from oceanographic cruises and satellite altimetry, and the application of an eddy-resolving primitive equation ocean model coupled with a numerical experiment using a passive tracer. In this region, ITEs are represented by subsurface lenses (˜100 km diameter; 500 m thickness or vertical extension) of nearly homogeneous salinity (>34.5) and oxygen-deficient (<1.0 mL L-1) waters, properties which are linked to the equatorial subsurface water mass (ESSW) transported poleward by the Peru-Chile undercurrent (PCUC) in the coastal band. At least five to seven ITEs were observed simultaneously in the area between 31° and 38°S during winter cruises in 1997 and 2009. Satellite data indicated that the ITEs identified from in situ data moved westward, each at a mean speed of ˜2 km d-1 and transported a total volume of ˜1 × 106 m3 s-1 (=1 Sv); the lifespan of each ITE ranged from a few months to 1 year. Model results indicate that ITEs become detached from the PCUC under summer upwelling conditions in the coastal zone.

Influence of sediment recycling on the trace element composition of primitive arc lavas

NASA Astrophysics Data System (ADS)

Collinet, M.; Jagoutz, O. E.

2017-12-01

Primitive calc-alkaline lavas from continental arcs are, on average, enriched in incompatible elements compared to those from intra-oceanic arcs. This relative enrichment is observed in different groups of trace elements: LILE (e.g. K, Rb), LREE to MREE (La-Dy) and HFSE (e.g.Zr, Nb) and is thought to result from (1) a transfer of material from the subducting slab to the mantle wedge at higher temperature than in intra-oceanic margins and/or (2) lower average degrees of melting in the mantle wedge, as a consequence of thicker overlying crusts and higher average pressures of melting. In addition to thicker overlying crusts and generally higher slab temperatures, continental margins are characterized by larger volumes of rock exposed above sea level and enhanced erosion rates compared to intra-oceanic arcs. As several geochemical signatures of arc lavas attest to the importance of sediment recycling in subduction zones, we explore the possibility that the high concentrations of incompatible elements in primitive lavas from continental arcs directly reflect a larger input of sediment to the subduction system. Previous efforts to quantify the sediment flux to oceanic trenches focused on the thickness of pelagic and hemipelagic sediments on top of the plate entering the subduction zone (Plank and Langmuir, 1993, Nature). These estimates primarily relied on the sediment layer drilled outboard from the subduction system and likely underestimate the volume of sediment derived from the arc itself. Accordingly, we find that such estimates of sediment flux do not correlate with the concentration of incompatible elements in primitive arc lavas. To account for regional contributions of coarser detrital sediments, usually delivered to oceanic trenches by turbidity currents, we apply to arc segments a model that quantifies the sediment load of rivers based on the average relief, area, temperature and runoff of their respective drainage areas (Syvitski et al., 2003, Sediment. Geol.). Our new estimates of sediment fluxes correlate positively with incompatible element concentrations in primitive arc lavas. We conclude that a large fraction of the local terrigenous sediments is subducted and contributes to the observed dichotomy in the trace element budget between primitive lavas from continental and oceanic margins.

Along-strike variability of primitive magmas (major and volatile elements) inferred from olivine-hosted melt inclusions, southernmost Andean Southern Volcanic Zone, Chile

NASA Astrophysics Data System (ADS)

Weller, D. J.; Stern, C. R.

2018-01-01

Glass compositions of melt inclusions in olivine phenocrysts found in tephras derived from explosive eruptions of the four volcanoes along the volcanic front of the southernmost Andean Southern Volcanic Zone (SSVZ) are used to constrain primitive magma compositions and melt generation parameters. Primitive magmas from Hudson, Macá, and Melimoyu have similar compositions and are formed by low degrees (8-18%) of partial melting. Compared to these other three centers, primitive magmas from Mentolat have higher Al2O3 and lower MgO, TiO2 and other incompatible minor elements, and are generated by somewhat higher degrees (12-20%) of partial melting. The differences in the estimated primitive parental magma compositions between Mentolat and the other three volcanic centers are consistent with difference in the more evolved magmas erupted from these centers, Mentolat magmas having higher Al2O3 and lower MgO, TiO2 and other incompatible minor element contents, suggesting that these differences are controlled by melting processes in the mantle source region above the subducted oceanic plate. Parental magma S = 1430-594 and Cl = 777-125 (μg/g) contents of Hudson, Macá, and Melimoyu are similar to other volcanoes further north in the SVZ. However, Mentolat primitive magmas have notably higher concentrations of S = 2656-1227 and Cl = 1078-704 (μg/g). The observed along-arc changes in parental magma chemistry may be due to the close proximity below Mentolat of the subducted Guamblin Fracture Zone that could efficiently transport hydrous mineral phases, seawater, and sediment into the mantle, driving enhanced volatile fluxed melting beneath this center compared to the others. Table S2. Olivine-hosted melt inclusion compositions, host-olivine compositions, and the post-entrapment crystallization corrected melt inclusion compositions. Table S3. Olivine-hosted melt inclusion modeling information. Table S4. Major element compositions of the fractionation corrected melt inclusion in equilibrium with mantle olivine. Table S5. Melting parameters Fm and CoH2O. Table S6. Major element compositions of phenocrysts and glasses occurring with the olivine-hosted melt inclusions.

Comparative Analysis of the 5S rRNA and Its Associated Proteins Reveals Unique Primitive Rather Than Parasitic Features in Giardia lamblia

PubMed Central

Xin, De-Dong; Wen, Jian-Fan

2012-01-01

Background 5S rRNA is a highly conserved ribosomal component. Eukaryotic 5S rRNA and its associated proteins (5S rRNA system) have become very well understood. Giardia lamblia was thought by some researchers to be the most primitive extant eukaryote while others considered it a highly evolved parasite. Previous reports have indicated that some aspects of its 5S rRNA system are simpler than that of common eukaryotes. We here explore whether this is true to its entire system, and whether this simplicity is a primitive or parasitic feature. Methodology/Principal Findings By collecting and confirming pre-existing data and identifying new data, we obtained almost complete datasets of the system of three isolates of G. lamblia, two other parasitic excavates (Trichomonas vaginalis, Trypanosoma cruzi), and one free-living one (Naegleria gruberi). After comprehensively comparing each aspect of the system among these excavates and also with those of archaea and common eukaryotes, we found all the three Giardia isolates to harbor a same simplified 5S rRNA system, which is not only much simpler than that of common eukaryotes but also the simplest one among those of these excavates, and is surprisingly very similar to that of archaea; we also found among these excavates the system in parasitic species is not necessarily simpler than that in free-living species, conversely, the system of free-living species is even simpler in some respects than those of parasitic ones. Conclusion/Significance The simplicity of Giardia 5S rRNA system should be considered a primitive rather than parasitically-degenerated feature. Therefore, Giardia 5S rRNA system might be a primitive system that is intermediate between that of archaea and the common eukaryotic model system, and it may reflect the evolutionary history of the eukaryotic 5S rRNA system from the archaeal form. Our results also imply G. lamblia might be a primitive eukaryote with secondary parasitically-degenerated features. PMID:22685540

Fundamental physical theories: Mathematical structures grounded on a primitive ontology

NASA Astrophysics Data System (ADS)

Allori, Valia

In my dissertation I analyze the structure of fundamental physical theories. I start with an analysis of what an adequate primitive ontology is, discussing the measurement problem in quantum mechanics and theirs solutions. It is commonly said that these theories have little in common. I argue instead that the moral of the measurement problem is that the wave function cannot represent physical objects and a common structure between these solutions can be recognized: each of them is about a clear three-dimensional primitive ontology that evolves according to a law determined by the wave function. The primitive ontology is what matter is made of while the wave function tells the matter how to move. One might think that what is important in the notion of primitive ontology is their three-dimensionality. If so, in a theory like classical electrodynamics electromagnetic fields would be part of the primitive ontology. I argue that, reflecting on what the purpose of a fundamental physical theory is, namely to explain the behavior of objects in three-dimensional space, one can recognize that a fundamental physical theory has a particular architecture. If so, electromagnetic fields play a different role in the theory than the particles and therefore should be considered, like the wave function, as part of the law. Therefore, we can characterize the general structure of a fundamental physical theory as a mathematical structure grounded on a primitive ontology. I explore this idea to better understand theories like classical mechanics and relativity, emphasizing that primitive ontology is crucial in the process of building new theories, being fundamental in identifying the symmetries. Finally, I analyze what it means to explain the word around us in terms of the notion of primitive ontology in the case of regularities of statistical character. Here is where the notion of typicality comes into play: we have explained a phenomenon if the typical histories of the primitive ontology give rise to the statistical regularities we observe.

A novel class sensitive hashing technique for large-scale content-based remote sensing image retrieval

NASA Astrophysics Data System (ADS)

Reato, Thomas; Demir, Begüm; Bruzzone, Lorenzo

2017-10-01

This paper presents a novel class sensitive hashing technique in the framework of large-scale content-based remote sensing (RS) image retrieval. The proposed technique aims at representing each image with multi-hash codes, each of which corresponds to a primitive (i.e., land cover class) present in the image. To this end, the proposed method consists of a three-steps algorithm. The first step is devoted to characterize each image by primitive class descriptors. These descriptors are obtained through a supervised approach, which initially extracts the image regions and their descriptors that are then associated with primitives present in the images. This step requires a set of annotated training regions to define primitive classes. A correspondence between the regions of an image and the primitive classes is built based on the probability of each primitive class to be present at each region. All the regions belonging to the specific primitive class with a probability higher than a given threshold are highly representative of that class. Thus, the average value of the descriptors of these regions is used to characterize that primitive. In the second step, the descriptors of primitive classes are transformed into multi-hash codes to represent each image. This is achieved by adapting the kernel-based supervised locality sensitive hashing method to multi-code hashing problems. The first two steps of the proposed technique, unlike the standard hashing methods, allow one to represent each image by a set of primitive class sensitive descriptors and their hash codes. Then, in the last step, the images in the archive that are very similar to a query image are retrieved based on a multi-hash-code-matching scheme. Experimental results obtained on an archive of aerial images confirm the effectiveness of the proposed technique in terms of retrieval accuracy when compared to the standard hashing methods.

Cometary dust: the diversity of primitive refractory grains

PubMed Central

Ishii, H. A.

2017-01-01

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive cometary particles has expanded significantly through microscale investigations of cosmic dust samples (anhydrous interplanetary dust particles (IDPs), chondritic porous (CP) IDPs and UltraCarbonaceous Antarctic micrometeorites, Stardust and Rosetta), as well as through remote sensing (Spitzer IR spectroscopy). Comet dust are aggregate particles of materials unequilibrated at submicrometre scales. We discuss the properties and processes experienced by primitive matter in comets. Primitive particles exhibit a diverse range of: structure and typology; distribution of constituents; concentration and form of carbonaceous and refractory organic matter; Mg- and Fe-contents of the silicate minerals; sulfides; existence/abundance of type II chondrule fragments; high-temperature calcium–aluminium inclusions and ameboid-olivine aggregates; and rarely occurring Mg-carbonates and magnetite, whose explanation requires aqueous alteration on parent bodies. The properties of refractory materials imply there were disc processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disc present at the time and in the region where the comets formed. This article is part of the themed issue ‘Cometary science after Rosetta’. PMID:28554979

Data assimilation experiments using diffusive back-and-forth nudging for the NEMO ocean model

NASA Astrophysics Data System (ADS)

Ruggiero, G. A.; Ourmières, Y.; Cosme, E.; Blum, J.; Auroux, D.; Verron, J.

2015-04-01

The diffusive back-and-forth nudging (DBFN) is an easy-to-implement iterative data assimilation method based on the well-known nudging method. It consists of a sequence of forward and backward model integrations, within a given time window, both of them using a feedback term to the observations. Therefore, in the DBFN, the nudging asymptotic behaviour is translated into an infinite number of iterations within a bounded time domain. In this method, the backward integration is carried out thanks to what is called backward model, which is basically the forward model with reversed time step sign. To maintain numeral stability, the diffusion terms also have their sign reversed, giving a diffusive character to the algorithm. In this article the DBFN performance to control a primitive equation ocean model is investigated. In this kind of model non-resolved scales are modelled by diffusion operators which dissipate energy that cascade from large to small scales. Thus, in this article, the DBFN approximations and their consequences for the data assimilation system set-up are analysed. Our main result is that the DBFN may provide results which are comparable to those produced by a 4Dvar implementation with a much simpler implementation and a shorter CPU time for convergence. The conducted sensitivity tests show that the 4Dvar profits of long assimilation windows to propagate surface information downwards, and that for the DBFN, it is worth using short assimilation windows to reduce the impact of diffusion-induced errors. Moreover, the DBFN is less sensitive to the first guess than the 4Dvar.

Experimental Phase Relations of Hydrous, Primitive Melts: Implications for variably depleted mantle melting in arcs and the generation of primitive high-SiO2 melts

NASA Astrophysics Data System (ADS)

Weaver, S.; Wallace, P. J.; Johnston, A.

2010-12-01

There has been considerable experimental and theoretical work on how the introduction of H2O-rich fluids into the mantle wedge affects partial melting in arcs and chemical evolution of mantle melts as they migrate through the mantle. Studies aimed at describing these processes have become largely quantitative, with an emphasis on creating models that suitably predict the production and evolution of melts and describe the thermal state of arcs worldwide. A complete experimental data set that explores the P-T conditions of melt generation and subsequent melt extraction is crucial to the development, calibration, and testing of these models. This work adds to that data set by constraining the P-T-H2O conditions of primary melt extraction from two end-member subduction zones, a continental arc (Mexico) and an intraoceanic arc (Aleutians). We present our data in context with primitive melts found worldwide and with other experimental studies of melts produced from fertile and variably depleted mantle sources. Additionally, we compare our experimental results to melt compositions predicted by empirical and thermodynamic models. We used a piston-cylinder apparatus and employed an inverse approach in our experiments, constraining the permissible mantle residues with which our melts could be in equilibrium. We confirmed our inverse approach with forced saturation experiments at the P-T-H2O conditions of melt-mantle equilibration. Our experimental results show that a primitive, basaltic andesite melt (JR-28) from monogenetic cinder cone Volcan Jorullo (Central Mexico) last equilibrated with a harzburgite mantle residue at 1.2-1.4 GPa and 1150-1175°C with H2O contents in the range of 5.5-7 wt% H2O prior to ascent and eruption. Phase relations of a tholeiitic high-MgO basaltic melt (ID-16) from the Central Aleutians (Okmok) show the conditions of last equilibration with a fertile lherzolite mantle residue at shallower (1.2 GPa) but hotter (1275°C) conditions with approximately 2 wt% H2O. Given the estimated crustal thicknesses of these two regions, our data suggest that both samples equilibrate with mantle minerals just below the Moho. Recent viscosity dependent thermal models that account for slab geometry suggest that JR-28 melts last equilibrate with harzburgite in a cooler region of the mantle wedge. In contrast, ID-16 equilibrated with a fertile source near the hotter core of the mantle wedge. Our results support the hypothesis that lherzolite melting (wet or dry) produces essentially basaltic melts, whereas more Si-rich primitive melts require shallow hydrous melting of harzburgite or reequilibration of basaltic melts with harzburgite in the uppermost part of the wedge.

SCaLeM: A Framework for Characterizing and Analyzing Execution Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chavarría-Miranda, Daniel; Manzano Franco, Joseph B.; Krishnamoorthy, Sriram

2014-10-13

As scalable parallel systems evolve towards more complex nodes with many-core architectures and larger trans-petascale & upcoming exascale deployments, there is a need to understand, characterize and quantify the underlying execution models being used on such systems. Execution models are a conceptual layer between applications & algorithms and the underlying parallel hardware and systems software on which those applications run. This paper presents the SCaLeM (Synchronization, Concurrency, Locality, Memory) framework for characterizing and execution models. SCaLeM consists of three basic elements: attributes, compositions and mapping of these compositions to abstract parallel systems. The fundamental Synchronization, Concurrency, Locality and Memory attributesmore » are used to characterize each execution model, while the combinations of those attributes in the form of compositions are used to describe the primitive operations of the execution model. The mapping of the execution model’s primitive operations described by compositions, to an underlying abstract parallel system can be evaluated quantitatively to determine its effectiveness. Finally, SCaLeM also enables the representation and analysis of applications in terms of execution models, for the purpose of evaluating the effectiveness of such mapping.« less

Designers workbench: toward real-time immersive modeling

NASA Astrophysics Data System (ADS)

Kuester, Falko; Duchaineau, Mark A.; Hamann, Bernd; Joy, Kenneth I.; Ma, Kwan-Liu

2000-05-01

This paper introduces the Designers Workbench, a semi- immersive virtual environment for two-handed modeling, sculpting and analysis tasks. The paper outlines the fundamental tools, design metaphors and hardware components required for an intuitive real-time modeling system. As companies focus on streamlining productivity to cope with global competition, the migration to computer-aided design (CAD), computer-aided manufacturing, and computer-aided engineering systems has established a new backbone of modern industrial product development. However, traditionally a product design frequently originates form a clay model that, after digitization, forms the basis for the numerical description of CAD primitives. The Designers Workbench aims at closing this technology or 'digital gap' experienced by design and CAD engineers by transforming the classical design paradigm into its fully integrate digital and virtual analog allowing collaborative development in a semi- immersive virtual environment. This project emphasizes two key components form the classical product design cycle: freeform modeling and analysis. In the freedom modeling stage, content creation in the form of two-handed sculpting of arbitrary objects using polygonal, volumetric or mathematically defined primitives is emphasized, whereas the analysis component provides the tools required for pre- and post-processing steps for finite element analysis tasks applied to the created models.

Basic primitives for molecular diagram sketching

PubMed Central

2010-01-01

A collection of primitive operations for molecular diagram sketching has been developed. These primitives compose a concise set of operations which can be used to construct publication-quality 2 D coordinates for molecular structures using a bare minimum of input bandwidth. The input requirements for each primitive consist of a small number of discrete choices, which means that these primitives can be used to form the basis of a user interface which does not require an accurate pointing device. This is particularly relevant to software designed for contemporary mobile platforms. The reduction of input bandwidth is accomplished by using algorithmic methods for anticipating probable geometries during the sketching process, and by intelligent use of template grafting. The algorithms and their uses are described in detail. PMID:20923555

The role of the complete Coriolis force in weakly stratified oceanic flows

NASA Astrophysics Data System (ADS)

Tort, M.; Winters, K. B.; Ribstein, B.; Zeitlin, V.

2016-02-01

Ocean dynamics is usually described using the primitive equations based on the so-called traditional approximation (TA), where the Coriolis force associated with the horizontal component of the planetary rotation is neglected (also called non-traditional (NT) part proportional to cosΦ, see Fig 1.). However, recent studies have shown that the NT part of the Coriolis force plays a non-negligible dynamical role in some particular oceanic flows (see Gerkema et al., 2008 for an extensive review of NT effects for geophysical and astrophysical flows). Here we explore the relevance of including the NT component of the Coriolis force in ocean models, by presenting particular results regarding two different mid-latitude flow configurations after relaxing the TA: Propagation of wind-induced near-inertial waves (NIWs). Under the TA, NIWs propagate toward the equator, the inertially poleward propagation being internally reflected at a depth-independent critical latitude. The combined effects of the NT Coriolis force and weak stratification in the deep ocean leads to the existence of waveguides for sub-inertial waves, which get trapped and propagate further poleward (Winters et al., 2011). Here we consider storm-induced NIWs and their evolution in a non-linear Boussinesq model on the β-plane in the NT approximation. Preliminary results are presented concerning the behavior of the waves in a weakly stratified mixed-layer, where NT effects are expected to be significant. Inertial instability. A detailed linear stability analysis of the Bickley jet at large Rossby numbers in the NT approximation on the f-plane is performed for long waves in a continuously stratified Boussinesq model. For a sufficiently weak stratification, both symmetric and asymmetric inertial instabilities have substantially higher growth rates than in the TA while no discernible differences between the two approximations are observed for strong enough stratifications (Tort et al., 2015).

The role of the Indonesian Throughflow in equatorial Pacific thermocline ventilation

NASA Astrophysics Data System (ADS)

Rodgers, Keith B.; Cane, Mark A.; Naik, Naomi H.; Schrag, Daniel P.

1999-09-01

The role of the Indonesian Throughflow (ITF) in the thermocline circulation of the low-latitude Pacific Ocean is explored using a high-resolution primitive equation ocean circulation model. Seasonally forced runs for a domain with an open Indonesian passage are compared with seasonally forced runs for a closed Pacific domain. Three cases are considered: one with no throughflow, one with 10 Sv of imposed ITF transport, and one with 20 Sv of ITF transport. Two idealized tracers, one that tags northern component subtropical water and another that tags southern component subtropical water, are used to diagnose the mixing ratio of northern and southern component waters in the equatorial thermocline. It is found that the mixing ratio of north/south component waters in the equatorial thermocline is highly sensitive to whether the model accounts for an ITF. Without an ITF, the source of equatorial undercurrent water is primarily of North Pacific origin, with the ratio of northern to southern component water being approximately 2.75 to 1. The ratio of northern to southern component water in the Equatorial Undercurrent with 10 Sv of ITF is approximately 1.4 to 1, and the ratio with 20 Sv of imposed ITF is 1 to 1.25. Estimates from data suggest a mean mixing ratio of northern to southern component water of less than 1 to 1. Assuming that the mixing ratio changes approximately linearly as the ITF transport varies between 10 and 20 Sv, an approximate balance between northern and southern component water is reached when the ITF transport is approximately 16 Sv. It is also shown that for the isopycnal surfaces within the core of the equatorial undercurrent, a 2°C temperature front exists across the equator in the western equatorial Pacific, beneath the warm pool. The implications of the model results and the temperature data for the heat budget of the equatorial Pacific are considered.

Efficient design of CMOS TSC checkers

NASA Technical Reports Server (NTRS)

Biddappa, Anita; Shamanna, Manjunath K.; Maki, Gary; Whitaker, Sterling

1990-01-01

This paper considers the design of an efficient, robustly testable, CMOS Totally Self-Checking (TSC) Checker for k-out-of-2k codes. Most existing implementations use primitive gates and assume the single stuck-at fault model. The self-testing property has been found to fail for CMOS TSC checkers under the stuck-open fault model due to timing skews and arbitrary delays in the circuit. A new four level design using CMOS primitive gates (NAND, NOR, INVERTERS) is presented. This design retains its properties under the stuck-open fault model. Additionally, this method offers an impressive reduction (greater than 70 percent) in gate count, gate inputs, and test set size when compared to the existing method. This implementation is easily realizable and is based on Anderson's technique. A thorough comparative study has been made on the proposed implementation and Kundu's implementation and the results indicate that the proposed one is better than Kundu's in all respects for k-out-of-2k codes.

Origin and Evolutionary Alteration of the Mitochondrial Import System in Eukaryotic Lineages

PubMed Central

Fukasawa, Yoshinori; Oda, Toshiyuki; Tomii, Kentaro

2017-01-01

Abstract Protein transport systems are fundamentally important for maintaining mitochondrial function. Nevertheless, mitochondrial protein translocases such as the kinetoplastid ATOM complex have recently been shown to vary in eukaryotic lineages. Various evolutionary hypotheses have been formulated to explain this diversity. To resolve any contradiction, estimating the primitive state and clarifying changes from that state are necessary. Here, we present more likely primitive models of mitochondrial translocases, specifically the translocase of the outer membrane (TOM) and translocase of the inner membrane (TIM) complexes, using scrutinized phylogenetic profiles. We then analyzed the translocases’ evolution in eukaryotic lineages. Based on those results, we propose a novel evolutionary scenario for diversification of the mitochondrial transport system. Our results indicate that presequence transport machinery was mostly established in the last eukaryotic common ancestor, and that primitive translocases already had a pathway for transporting presequence-containing proteins. Moreover, secondary changes including convergent and migrational gains of a presequence receptor in TOM and TIM complexes, respectively, likely resulted from constrained evolution. The nature of a targeting signal can constrain alteration to the protein transport complex. PMID:28369657

Creation and Distribution of CAIs in the Protoplanetary Nebula

NASA Technical Reports Server (NTRS)

Cuzzi, J. N.; Davis, S. S.; Dobrovolskis, A. R.

2003-01-01

CaAl rich refractory mineral inclusions (CAIs) found at 1 - 10% mass fraction in primitive chondrites appear to be several million years older than the dominant (chondrule) components in the same parent bodies. A prevalent concern is that it is difficult to retain CAIs for this long against gas-drag-induced radial drift into the sun. We assess a hot inner (turbulent) nebula context for CAI formation, using analytical models of nebula evolution and particle diffusion. We show that outward radial diffusion in a weakly turbulent nebula can prevent significant numbers of CAI-size particles from being lost into the sun for times of 1 - 3 x 10(exp 6) years. To match the CAI abundances quantitatively, we advocate an enhancement of the inner hot nebula in silicate-forming material, due to rapid inward migration of very primitive, silicate and carbon rich, meter-sized objects. 'Combustion' of the carbon into CO would make the CAI formation environment more reduced than solar, as certain observations imply. Abundant CO might also play a role in mass-independent chemical fractionation of oxygen isotopes as seen in CAIs and associated primitive, high-temperature condensates.

Multi-processor including data flow accelerator module

DOEpatents

Davidson, George S.; Pierce, Paul E.

1990-01-01

An accelerator module for a data flow computer includes an intelligent memory. The module is added to a multiprocessor arrangement and uses a shared tagged memory architecture in the data flow computer. The intelligent memory module assigns locations for holding data values in correspondence with arcs leading to a node in a data dependency graph. Each primitive computation is associated with a corresponding memory cell, including a number of slots for operands needed to execute a primitive computation, a primitive identifying pointer, and linking slots for distributing the result of the cell computation to other cells requiring that result as an operand. Circuitry is provided for utilizing tag bits to determine automatically when all operands required by a processor are available and for scheduling the primitive for execution in a queue. Each memory cell of the module may be associated with any of the primitives, and the particular primitive to be executed by the processor associated with the cell is identified by providing an index, such as the cell number for the primitive, to the primitive lookup table of starting addresses. The module thus serves to perform functions previously performed by a number of sections of data flow architectures and coexists with conventional shared memory therein. A multiprocessing system including the module operates in a hybrid mode, wherein the same processing modules are used to perform some processing in a sequential mode, under immediate control of an operating system, while performing other processing in a data flow mode.

Dynamic primitives in the control of locomotion

PubMed Central

Hogan, Neville; Sternad, Dagmar

2013-01-01

Humans achieve locomotor dexterity that far exceeds the capability of modern robots, yet this is achieved despite slower actuators, imprecise sensors, and vastly slower communication. We propose that this spectacular performance arises from encoding motor commands in terms of dynamic primitives. We propose three primitives as a foundation for a comprehensive theoretical framework that can embrace a wide range of upper- and lower-limb behaviors. Building on previous work that suggested discrete and rhythmic movements as elementary dynamic behaviors, we define submovements and oscillations: as discrete movements cannot be combined with sufficient flexibility, we argue that suitably-defined submovements are primitives. As the term “rhythmic” may be ambiguous, we define oscillations as the corresponding class of primitives. We further propose mechanical impedances as a third class of dynamic primitives, necessary for interaction with the physical environment. Combination of these three classes of primitive requires care. One approach is through a generalized equivalent network: a virtual trajectory composed of simultaneous and/or sequential submovements and/or oscillations that interacts with mechanical impedances to produce observable forces and motions. Reliable experimental identification of these dynamic primitives presents challenges: identification of mechanical impedances is exquisitely sensitive to assumptions about their dynamic structure; identification of submovements and oscillations is sensitive to their assumed form and to details of the algorithm used to extract them. Some methods to address these challenges are presented. Some implications of this theoretical framework for locomotor rehabilitation are considered. PMID:23801959

Experiments with the Mesoscale Atmospheric Simulation System (MASS) using the synthetic relative humidity

NASA Technical Reports Server (NTRS)

Chang, Chia-Bo

1994-01-01

This study is intended to examine the impact of the synthetic relative humidity on the model simulation of mesoscale convective storm environment. The synthetic relative humidity is derived from the National Weather Services surface observations, and non-conventional sources including aircraft, radar, and satellite observations. The latter sources provide the mesoscale data of very high spatial and temporal resolution. The synthetic humidity data is used to complement the National Weather Services rawinsonde observations. It is believed that a realistic representation of initial moisture field in a mesoscale model is critical for the model simulation of thunderstorm development, and the formation of non-convective clouds as well as their effects on the surface energy budget. The impact will be investigated based on a real-data case study using the mesoscale atmospheric simulation system developed by Mesoscale Environmental Simulations Operations, Inc. The mesoscale atmospheric simulation system consists of objective analysis and initialization codes, and the coarse-mesh and fine-mesh dynamic prediction models. Both models are a three dimensional, primitive equation model containing the essential moist physics for simulating and forecasting mesoscale convective processes in the atmosphere. The modeling system is currently implemented at the Applied Meteorology Unit, Kennedy Space Center. Two procedures involving the synthetic relative humidity to define the model initial moisture fields are considered. It is proposed to perform several short-range (approximately 6 hours) comparative coarse-mesh simulation experiments with and without the synthetic data. They are aimed at revealing the model sensitivities should allow us both to refine the specification of the observational requirements, and to develop more accurate and efficient objective analysis schemes. The goal is to advance the MASS (Mesoscal Atmospheric Simulation System) modeling expertise so that the model output can provide reliable guidance for thunderstorm forecasting.

Large eddy simulation of transitional flow in an idealized stenotic blood vessel: evaluation of subgrid scale models.

PubMed

Pal, Abhro; Anupindi, Kameswararao; Delorme, Yann; Ghaisas, Niranjan; Shetty, Dinesh A; Frankel, Steven H

2014-07-01

In the present study, we performed large eddy simulation (LES) of axisymmetric, and 75% stenosed, eccentric arterial models with steady inflow conditions at a Reynolds number of 1000. The results obtained are compared with the direct numerical simulation (DNS) data (Varghese et al., 2007, "Direct Numerical Simulation of Stenotic Flows. Part 1. Steady Flow," J. Fluid Mech., 582, pp. 253-280). An inhouse code (WenoHemo) employing high-order numerical methods for spatial and temporal terms, along with a 2nd order accurate ghost point immersed boundary method (IBM) (Mark, and Vanwachem, 2008, "Derivation and Validation of a Novel Implicit Second-Order Accurate Immersed Boundary Method," J. Comput. Phys., 227(13), pp. 6660-6680) for enforcing boundary conditions on curved geometries is used for simulations. Three subgrid scale (SGS) models, namely, the classical Smagorinsky model (Smagorinsky, 1963, "General Circulation Experiments With the Primitive Equations," Mon. Weather Rev., 91(10), pp. 99-164), recently developed Vreman model (Vreman, 2004, "An Eddy-Viscosity Subgrid-Scale Model for Turbulent Shear Flow: Algebraic Theory and Applications," Phys. Fluids, 16(10), pp. 3670-3681), and the Sigma model (Nicoud et al., 2011, "Using Singular Values to Build a Subgrid-Scale Model for Large Eddy Simulations," Phys. Fluids, 23(8), 085106) are evaluated in the present study. Evaluation of SGS models suggests that the classical constant coefficient Smagorinsky model gives best agreement with the DNS data, whereas the Vreman and Sigma models predict an early transition to turbulence in the poststenotic region. Supplementary simulations are performed using Open source field operation and manipulation (OpenFOAM) ("OpenFOAM," http://www.openfoam.org/) solver and the results are inline with those obtained with WenoHemo.

West Florida shelf circulation and temperature budget for the 1998 fall transition

NASA Astrophysics Data System (ADS)

He, Ruoying; Weisberg, Robert H.

2003-05-01

Mid-latitude continental shelves undergo a fall transition as the net heat flux changes from warming to cooling. Using in situ data and a numerical model we investigate the circulation on the west Florida shelf (WFS) for the fall transition of 1998. The model is a regional adaptation of the primitive equation, Princeton Ocean Model forced by NCEP reanalysis wind, air pressure, and heat flux fields, plus river inflows. After comparison with observations the model is used to draw inferences on the seasonal and synoptic scale features of the shelf circulation. By running twin experiments, one without and the other with an idealized Loop Current (LC), we explore the relative importance of local versus deep-ocean forcing. We find that local forcing largely controls the inner-shelf circulation, including changes from the Florida Panhandle in the north to regions farther south. The effects of the LC in fall 1998 are to reinforce the mid-shelf currents and to increase the across-shelf transports in the bottom Ekman layer, thereby accentuating the shoreward transport of cold, nutrient rich water of deep-ocean origin. A three-dimensional analysis of the temperature budget reveals that surface heat flux largely controls both the seasonal and synoptic scale temperature variations. Surface cooling leads to convective mixing that rapidly alters temperature gradients. One interesting consequence is that upwelling can result in near-shore warming as warmer offshore waters are advected landward. The temperature balances on the shelf are complex and fully three-dimensional.

36 CFR 261.21 - National Forest primitive areas.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false National Forest primitive areas. 261.21 Section 261.21 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE PROHIBITIONS General Prohibitions § 261.21 National Forest primitive areas. The following are...

Semi-implicit finite difference methods for three-dimensional shallow water flow

USGS Publications Warehouse

Casulli, Vincenzo; Cheng, Ralph T.

1992-01-01

A semi-implicit finite difference method for the numerical solution of three-dimensional shallow water flows is presented and discussed. The governing equations are the primitive three-dimensional turbulent mean flow equations where the pressure distribution in the vertical has been assumed to be hydrostatic. In the method of solution a minimal degree of implicitness has been adopted in such a fashion that the resulting algorithm is stable and gives a maximal computational efficiency at a minimal computational cost. At each time step the numerical method requires the solution of one large linear system which can be formally decomposed into a set of small three-diagonal systems coupled with one five-diagonal system. All these linear systems are symmetric and positive definite. Thus the existence and uniquencess of the numerical solution are assured. When only one vertical layer is specified, this method reduces as a special case to a semi-implicit scheme for solving the corresponding two-dimensional shallow water equations. The resulting two- and three-dimensional algorithm has been shown to be fast, accurate and mass-conservative and can also be applied to simulate flooding and drying of tidal mud-flats in conjunction with three-dimensional flows. Furthermore, the resulting algorithm is fully vectorizable for an efficient implementation on modern vector computers.

Historical Development of Origins Research

PubMed Central

Lazcano, Antonio

2010-01-01

Following the publication of the Origin of Species in 1859, many naturalists adopted the idea that living organisms were the historical outcome of gradual transformation of lifeless matter. These views soon merged with the developments of biochemistry and cell biology and led to proposals in which the origin of protoplasm was equated with the origin of life. The heterotrophic origin of life proposed by Oparin and Haldane in the 1920s was part of this tradition, which Oparin enriched by transforming the discussion of the emergence of the first cells into a workable multidisciplinary research program. On the other hand, the scientific trend toward understanding biological phenomena at the molecular level led authors like Troland, Muller, and others to propose that single molecules or viruses represented primordial living systems. The contrast between these opposing views on the origin of life represents not only contrasting views of the nature of life itself, but also major ideological discussions that reached a surprising intensity in the years following Stanley Miller’s seminal result which showed the ease with which organic compounds of biochemical significance could be synthesized under putative primitive conditions. In fact, during the years following the Miller experiment, attempts to understand the origin of life were strongly influenced by research on DNA replication and protein biosynthesis, and, in socio-political terms, by the atmosphere created by Cold War tensions. The catalytic versatility of RNA molecules clearly merits a critical reappraisal of Muller’s viewpoint. However, the discovery of ribozymes does not imply that autocatalytic nucleic acid molecules ready to be used as primordial genes were floating in the primitive oceans, or that the RNA world emerged completely assembled from simple precursors present in the prebiotic soup. The evidence supporting the presence of a wide range of organic molecules on the primitive Earth, including membrane-forming compounds, suggests that the evolution of membrane-bounded molecular systems preceded cellular life on our planet, and that life is the evolutionary outcome of a process, not of a single, fortuitous event. PMID:20534710

Approximate strip exchanging.

PubMed

Roy, Swapnoneel; Thakur, Ashok Kumar

2008-01-01

Genome rearrangements have been modelled by a variety of primitives such as reversals, transpositions, block moves and block interchanges. We consider such a genome rearrangement primitive Strip Exchanges. Given a permutation, the challenge is to sort it by using minimum number of strip exchanges. A strip exchanging move interchanges the positions of two chosen strips so that they merge with other strips. The strip exchange problem is to sort a permutation using minimum number of strip exchanges. We present here the first non-trivial 2-approximation algorithm to this problem. We also observe that sorting by strip-exchanges is fixed-parameter-tractable. Lastly we discuss the application of strip exchanges in a different area Optical Character Recognition (OCR) with an example.

Underscreening in ionic liquids: a first principles analysis.

PubMed

Rotenberg, Benjamin; Bernard, Olivier; Hansen, Jean-Pierre

2018-02-07

An attempt is made to understand the underscreening effect, observed in concentrated electrolyte solutions or melts, on the basis of simple, admittedly crude models involving charged (for the ions) and neutral (for the solvent molecules) hard spheres. The thermodynamic and structural properties of these 'primitive' and 'semi-primitive' models are calculated within mean spherical approximation, which provides the basic input required to determine the partial density response functions. The screening length [Formula: see text], which is unambiguously defined in terms of the wave-number-dependent response functions, exhibits a cross-over from a low density, Debye-like regime, to a regime where [Formula: see text] increases with density beyond a critical density at which the Debye length [Formula: see text] becomes comparable to the ion diameter. In this high density regime the ratio [Formula: see text] increases according to a power law, in qualitative agreement with experimental measurements, albeit at a much slower rate.

Isotopic Anomalies in Primitive Solar System Matter: Spin-State-Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds

NASA Technical Reports Server (NTRS)

Wirstrom, Eva S.; Charnley, Steven B.; Cordiner, Martin A.; Milam, Stefanie N.

2012-01-01

Organic material found in meteorites and interplanetary dust particles is enriched in D and N-15. This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar nebula, Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and N-15 and can account for the largest isotopic enrichments measured in carbonaceous meteorites. However, more recent measurements have shown that, in some primitive samples, a large N-15 enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, N-15 enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H2, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both N-15 and D in dense cloud cores. We also show that while the nitriles, HCN and HNC, contain the greatest N=15 enrichment, this is not expected to correlate with extreme D enrichment. These calculations therefore support the view that solar system N-15 and D isotopic anomalies have an interstellar heritage. We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

Isotopic Anomalies in Primitive Solar System Matter: Spin-State Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds

NASA Technical Reports Server (NTRS)

Wirstrom, Eva S.; Charnley, Steven B.; Cordiner, Martin A.; Milan, Stefanie N.

2012-01-01

Organic material found in meteorites and interplanetary dust particles is enriched in D and N-15, This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar core. Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and N-15 and can account for the largest isotop c enrichments measured in carbonaceous meteorites, However, more recent measurements have shown that, in some primitive samples, a large N-15 enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, N-15 enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H2, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both N-15 and D in dense cloud cores, We also show that while the nitriles, HCN and HNC, contain the greatest N-15 enrichment, this is not expected to correlate with extreme D emichment. These calculations therefore support the view that Solar System N-15 and D isotopic anomalies have an interstellar heritage, We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

The Distributed Memory Computing Conference (5th) Held in Charleston, South Carolina on April 8-12, 1990. Volume 1. Applications

DTIC Science & Technology

1991-03-31

nodes, directional arrows show the parent and child rela- and the graphics driver runs on the CP, i.e., the tionship of processes. Although there is a...about ODB plus some number of transitory primitives, whether or not its child primitives are resident. Transitory primitives are discarded as needed...true if this Hnode’s child primitives approached. are not resident. This method of ODB decomposition has the ability to distribute a very large number of

A Feature-adaptive Subdivision Method for Real-time 3D Reconstruction of Repeated Topology Surfaces

NASA Astrophysics Data System (ADS)

Lin, Jinhua; Wang, Yanjie; Sun, Honghai

2017-03-01

It's well known that rendering for a large number of triangles with GPU hardware tessellation has made great progress. However, due to the fixed nature of GPU pipeline, many off-line methods that perform well can not meet the on-line requirements. In this paper, an optimized Feature-adaptive subdivision method is proposed, which is more suitable for reconstructing surfaces with repeated cusps or creases. An Octree primitive is established in irregular regions where there are the same sharp vertices or creases, this method can find the neighbor geometry information quickly. Because of having the same topology structure between Octree primitive and feature region, the Octree feature points can match the arbitrary vertices in feature region more precisely. In the meanwhile, the patches is re-encoded in the Octree primitive by using the breadth-first strategy, resulting in a meta-table which allows for real-time reconstruction by GPU hardware tessellation unit. There is only one feature region needed to be calculated under Octree primitive, other regions with the same repeated feature generate their own meta-table directly, the reconstruction time is saved greatly for this step. With regard to the meshes having a large number of repeated topology feature, our algorithm improves the subdivision time by 17.575% and increases the average frame drawing time by 0.2373 ms compared to the traditional FAS (Feature-adaptive Subdivision), at the same time the model can be reconstructed in a watertight manner.

A coarse-grid projection method for accelerating incompressible flow computations

NASA Astrophysics Data System (ADS)

San, Omer; Staples, Anne E.

2013-01-01

We present a coarse-grid projection (CGP) method for accelerating incompressible flow computations, which is applicable to methods involving Poisson equations as incompressibility constraints. The CGP methodology is a modular approach that facilitates data transfer with simple interpolations and uses black-box solvers for the Poisson and advection-diffusion equations in the flow solver. After solving the Poisson equation on a coarsened grid, an interpolation scheme is used to obtain the fine data for subsequent time stepping on the full grid. A particular version of the method is applied here to the vorticity-stream function, primitive variable, and vorticity-velocity formulations of incompressible Navier-Stokes equations. We compute several benchmark flow problems on two-dimensional Cartesian and non-Cartesian grids, as well as a three-dimensional flow problem. The method is found to accelerate these computations while retaining a level of accuracy close to that of the fine resolution field, which is significantly better than the accuracy obtained for a similar computation performed solely using a coarse grid. A linear acceleration rate is obtained for all the cases we consider due to the linear-cost elliptic Poisson solver used, with reduction factors in computational time between 2 and 42. The computational savings are larger when a suboptimal Poisson solver is used. We also find that the computational savings increase with increasing distortion ratio on non-Cartesian grids, making the CGP method a useful tool for accelerating generalized curvilinear incompressible flow solvers.

Results of a zonally truncated three-dimensional model of the Venus middle atmosphere

NASA Technical Reports Server (NTRS)

Newman, M.

1992-01-01

Although the equatorial rotational speed of the solid surface of Venus is only 4 m s(exp-1), the atmospheric rotational speed reaches a maximum of approximately 100 m s(exp-1) near the equatorial cloud top level (65 to 70 km). This phenomenon, known as superrotation, is the central dynamical problem of the Venus atmosphere. We report here the results of numerical simulations aimed at clarifying the mechanism for maintaining the equatorial cloud top rotation. Maintenance of an equatorial rotational speed maximum above the surface requires waves or eddies that systematically transport angular momentum against its zonal mean gradient. The zonally symmetric Hadley circulation is driven thermally and acts to reduce the rotational speed at the equatorial cloud top level; thus wave or eddy transport must counter this tendency as well as friction. Planetary waves arising from horizontal shear instability of the zonal flow (barotropic instability) could maintain the equatorial rotation by transporting angular momentum horizontally from midlatitudes toward the equator. Alternatively, vertically propagating waves could provide the required momentum source. The relative motion between the rotating atmosphere and the pattern of solar heating, which as a maximum where solar radiation is absorbed near the cloud tops, drives diurnal and semidiurnal thermal tides that propagate vertically away from the cloud top level. The effect of this wave propagation is to transport momentum toward the cloud top level at low latitudes and accelerate the mean zonal flow there. We employ a semispectral primitive equation model with a zonal mean flow and zonal wavenumbers 1 and 2. These waves correspond to the diurnal and semidiurnal tides, but they can also be excited by barotropic or baroclinic instability. Waves of higher wavenumbers and interactions between the waves are neglected. Symmetry about the equator is assumed, so the model applies to one hemisphere and covers the altitude range 30 to 110 km. Horizontal resolution is 1.5 deg latitude, and vertical resolution is 1.5 km. Solar and thermal infrared heating, based on Venus observations and calculations drive the model flow. Dissipation is accomplished mainly by Rayleigh friction, chosen to produce strong dissipation above 85 km in order to absorb upward propagating waves and limit extreme flow velocities there, yet to give very weak Rayleigh friction below 70 km; results in the cloud layer do not appear to be sensitive to the Rayleigh friction. The model also has weak vertical diffusion, and very weak horizontal diffusion, which has a smoothing effect on the flow only at the two grid points nearest the pole.

A Method for Automatic Surface Inspection Using a Model-Based 3D Descriptor.

PubMed

Madrigal, Carlos A; Branch, John W; Restrepo, Alejandro; Mery, Domingo

2017-10-02

Automatic visual inspection allows for the identification of surface defects in manufactured parts. Nevertheless, when defects are on a sub-millimeter scale, detection and recognition are a challenge. This is particularly true when the defect generates topological deformations that are not shown with strong contrast in the 2D image. In this paper, we present a method for recognizing surface defects in 3D point clouds. Firstly, we propose a novel 3D local descriptor called the Model Point Feature Histogram (MPFH) for defect detection. Our descriptor is inspired from earlier descriptors such as the Point Feature Histogram (PFH). To construct the MPFH descriptor, the models that best fit the local surface and their normal vectors are estimated. For each surface model, its contribution weight to the formation of the surface region is calculated and from the relative difference between models of the same region a histogram is generated representing the underlying surface changes. Secondly, through a classification stage, the points on the surface are labeled according to five types of primitives and the defect is detected. Thirdly, the connected components of primitives are projected to a plane, forming a 2D image. Finally, 2D geometrical features are extracted and by a support vector machine, the defects are recognized. The database used is composed of 3D simulated surfaces and 3D reconstructions of defects in welding, artificial teeth, indentations in materials, ceramics and 3D models of defects. The quantitative and qualitative results showed that the proposed method of description is robust to noise and the scale factor, and it is sufficiently discriminative for detecting some surface defects. The performance evaluation of the proposed method was performed for a classification task of the 3D point cloud in primitives, reporting an accuracy of 95%, which is higher than for other state-of-art descriptors. The rate of recognition of defects was close to 94%.

A Method for Automatic Surface Inspection Using a Model-Based 3D Descriptor

PubMed Central

Branch, John W.

2017-01-01

Automatic visual inspection allows for the identification of surface defects in manufactured parts. Nevertheless, when defects are on a sub-millimeter scale, detection and recognition are a challenge. This is particularly true when the defect generates topological deformations that are not shown with strong contrast in the 2D image. In this paper, we present a method for recognizing surface defects in 3D point clouds. Firstly, we propose a novel 3D local descriptor called the Model Point Feature Histogram (MPFH) for defect detection. Our descriptor is inspired from earlier descriptors such as the Point Feature Histogram (PFH). To construct the MPFH descriptor, the models that best fit the local surface and their normal vectors are estimated. For each surface model, its contribution weight to the formation of the surface region is calculated and from the relative difference between models of the same region a histogram is generated representing the underlying surface changes. Secondly, through a classification stage, the points on the surface are labeled according to five types of primitives and the defect is detected. Thirdly, the connected components of primitives are projected to a plane, forming a 2D image. Finally, 2D geometrical features are extracted and by a support vector machine, the defects are recognized. The database used is composed of 3D simulated surfaces and 3D reconstructions of defects in welding, artificial teeth, indentations in materials, ceramics and 3D models of defects. The quantitative and qualitative results showed that the proposed method of description is robust to noise and the scale factor, and it is sufficiently discriminative for detecting some surface defects. The performance evaluation of the proposed method was performed for a classification task of the 3D point cloud in primitives, reporting an accuracy of 95%, which is higher than for other state-of-art descriptors. The rate of recognition of defects was close to 94%. PMID:28974037

Mechanisms of Resistance in Microbial Spores.

DTIC Science & Technology

1986-11-14

1702 by Leeuwenhoek with rotifers and nematodes. Cryptobiosis occurs also in the primitive tardigrade animals, the cysts and larvae of certain...excellent unicelTular, prokaryotic model for studying the extended maintenance of the organized structure that characterizes living organisms. Despite

Physics of Life: A Model for Non-Newtonian Properties of Living Systems

NASA Technical Reports Server (NTRS)

Zak, Michail

2010-01-01

This innovation proposes the reconciliation of the evolution of life with the second law of thermodynamics via the introduction of the First Principle for modeling behavior of living systems. The structure of the model is quantum-inspired: it acquires the topology of the Madelung equation in which the quantum potential is replaced with the information potential. As a result, the model captures the most fundamental property of life: the progressive evolution; i.e. the ability to evolve from disorder to order without any external interference. The mathematical structure of the model can be obtained from the Newtonian equations of motion (representing the motor dynamics) coupled with the corresponding Liouville equation (representing the mental dynamics) via information forces. All these specific non-Newtonian properties equip the model with the levels of complexity that matches the complexity of life, and that makes the model applicable for description of behaviors of ecological, social, and economical systems. Rather than addressing the six aspects of life (organization, metabolism, growth, adaptation, response to stimuli, and reproduction), this work focuses only on biosignature ; i.e. the mechanical invariants of life, and in particular, the geometry and kinematics of behavior of living things. Living things obey the First Principles of Newtonian mechanics. One main objective of this model is to extend the First Principles of classical physics to include phenomenological behavior on living systems; to develop a new mathematical formalism within the framework of classical dynamics that would allow one to capture the specific properties of natural or artificial living systems such as formation of the collective mind based upon abstract images of the selves and non-selves; exploitation of this collective mind for communications and predictions of future expected characteristics of evolution; and for making decisions and implementing the corresponding corrections if the expected scenario is different from the originally planned one. This approach postulates that even a primitive living species possesses additional, non-Newtonian properties that are not included in the laws of Newtonian or statistical mechanics. These properties follow from a privileged ability of living systems to possess a self-image (a concept introduced in psychology) and to interact with it. The proposed mathematical system is based on the coupling of the classical dynamical system representing the motor dynamics with the corresponding Liouville equation describing the evolution of initial uncertainties in terms of the probability density and representing the mental dynamics. The coupling is implemented by the information-based supervising forces that can be associated with self-awareness. These forces fundamentally change the pattern of the probability evolution, and therefore, lead to a major departure of the behavior of living systems from the patterns of both Newtonian and statistical mechanics. This innovation is meant to capture the signature of life based only on observable behavior, not on any biochemistry. This will not prevent the use of this model for developing artificial living systems, as well as for studying some general properties of behavior of natural, living systems.

A Numerical Method of Calculating Propeller Noise Including Acoustic Nonlinear Effects

NASA Technical Reports Server (NTRS)

Korkan, K. D.

1985-01-01

Using the transonic flow fields(s) generated by the NASPROP-E computer code for an eight blade SR3-series propeller, a theoretical method is investigated to calculate the total noise values and frequency content in the acoustic near and far field without using the Ffowcs Williams - Hawkings equation. The flow field is numerically generated using an implicit three dimensional Euler equation solver in weak conservation law form. Numerical damping is required by the differencing method for stability in three dimensions, and the influence of the damping on the calculated acoustic values is investigated. The acoustic near field is solved by integrating with respect to time the pressure oscillations induced at a stationary observer location. The acoustic far field is calculated from the near field primitive variables as generated by NASPROP-E computer code using a method involving a perturbation velocity potential as suggested by Hawkings in the calculation of the acoustic pressure time-history at a specified far field observed location. the methodologies described are valid for calculating total noise levels and are applicable to any propeller geometry for which a flow field solution is available.

Distributed Relaxation for Conservative Discretizations

NASA Technical Reports Server (NTRS)

Diskin, Boris; Thomas, James L.

2001-01-01

A multigrid method is defined as having textbook multigrid efficiency (TME) if the solutions to the governing system of equations are attained in a computational work that is a small (less than 10) multiple of the operation count in one target-grid residual evaluation. The way to achieve this efficiency is the distributed relaxation approach. TME solvers employing distributed relaxation have already been demonstrated for nonconservative formulations of high-Reynolds-number viscous incompressible and subsonic compressible flow regimes. The purpose of this paper is to provide foundations for applications of distributed relaxation to conservative discretizations. A direct correspondence between the primitive variable interpolations for calculating fluxes in conservative finite-volume discretizations and stencils of the discretized derivatives in the nonconservative formulation has been established. Based on this correspondence, one can arrive at a conservative discretization which is very efficiently solved with a nonconservative relaxation scheme and this is demonstrated for conservative discretization of the quasi one-dimensional Euler equations. Formulations for both staggered and collocated grid arrangements are considered and extensions of the general procedure to multiple dimensions are discussed.

Generalized compliant motion primitive

NASA Technical Reports Server (NTRS)

Backes, Paul G. (Inventor)

1994-01-01

This invention relates to a general primitive for controlling a telerobot with a set of input parameters. The primitive includes a trajectory generator; a teleoperation sensor; a joint limit generator; a force setpoint generator; a dither function generator, which produces telerobot motion inputs in a common coordinate frame for simultaneous combination in sensor summers. Virtual return spring motion input is provided by a restoration spring subsystem. The novel features of this invention include use of a single general motion primitive at a remote site to permit the shared and supervisory control of the robot manipulator to perform tasks via a remotely transferred input parameter set.

Primitive neuroectodermal tumors of the central nervous system.

PubMed

Becker, L E; Hinton, D

1983-06-01

Primitive neuroectodermal tumors are morphologically similar malignant tumors arising in intracranial and peripheral sites of the nervous system, showing varying degrees of cellular differentiation with a tendency to disseminate along cerebrospinal fluid pathways. They occur primarily in children and young adults. Under the designation primitive neuroectodermal tumors are included medulloblastomas and tumors that may differentiate in other directions, such as medulloepithelioma, neuroblastoma, polar spongioblastoma, pineoblastoma, ependymoblastoma, retinoblastoma, and olfactory neuroblastoma. From a practical, histologic point of view, these tumors are often indistinguishable from one another and are best thought of as primitive neuroectodermal tumors with or without differentiating features.

Evolution of the magnetized, neutrino-cooled accretion disk in the aftermath of a black hole-neutron star binary merger

NASA Astrophysics Data System (ADS)

Hossein Nouri, Fatemeh; Duez, Matthew D.; Foucart, Francois; Deaton, M. Brett; Haas, Roland; Haddadi, Milad; Kidder, Lawrence E.; Ott, Christian D.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilagyi, Bela

2018-04-01

Black hole-torus systems from compact binary mergers are possible engines for gamma-ray bursts (GRBs). During the early evolution of the postmerger remnant, the state of the torus is determined by a combination of neutrino cooling and magnetically driven heating processes, so realistic models must include both effects. In this paper, we study the postmerger evolution of a magnetized black hole-neutron star binary system using the Spectral Einstein Code (SpEC) from an initial postmerger state provided by previous numerical relativity simulations. We use a finite-temperature nuclear equation of state and incorporate neutrino effects in a leakage approximation. To achieve the needed accuracy, we introduce improvements to SpEC's implementation of general-relativistic magnetohydrodynamics (MHD), including the use of cubed-sphere multipatch grids and an improved method for dealing with supersonic accretion flows where primitive variable recovery is difficult. We find that a seed magnetic field triggers a sustained source of heating, but its thermal effects are largely cancelled by the accretion and spreading of the torus from MHD-related angular momentum transport. The neutrino luminosity peaks at the start of the simulation, and then drops significantly over the first 20 ms but in roughly the same way for magnetized and nonmagnetized disks. The heating rate and disk's luminosity decrease much more slowly thereafter. These features of the evolution are insensitive to grid structure and resolution, formulation of the MHD equations, and seed field strength, although turbulent effects are not fully converged.

West Florida shelf circulation and temperature budget for the 1999 spring transition

USGS Publications Warehouse

He, Ruoying; Weisberg, Robert H.

2002-01-01

Mid-latitude continental shelves undergo a spring transition as the net surface heat flux changes from cooling to warming. Using in situ data and a numerical circulation model we investigate the circulation and temperature budget on the West Florida Continental Shelf (WFS) for the spring transition of 1999. The model is a regional adaptation of the primitive equation, Princeton Ocean Model forced by NCEP reanalysis wind and heat flux fields and by river inflows. Based on agreements between the modeled and observed fields we use the model to draw inferences on how the surface momentum and heat fluxes affect the seasonal and synoptic scale variability. We account for a strong southeastward current at mid-shelf by the baroclinic response to combined wind and buoyancy forcing, and we show how this local forcing leads to annually occurring cold and low salinity tongues. Through term-by-term analyses of the temperature budget we describe the WFS temperature evolution in spring. Heat flux largely controls the seasonal transition, whereas ocean circulation largely controls the synoptic scale variability. These two processes, however, are closely linked. Bottom topography and coastline geometry are important in generating regions of convergence and divergence. Rivers contribute to the local hydrography and are important ecologically. Along with upwelling, river inflows facilitate frontal aggregation of nutrients and the spring formation of a high concentration chlorophyll plume near the shelf break (the so-called ‘Green River’) coinciding with the cold, low salinity tongues. These features originate by local, shelf-wide forcing; the Loop Current is not an essential ingredient.

Trend analysis of regional heat wave warning using RegCM simulations

NASA Astrophysics Data System (ADS)

Pongracz, R.; Bartholy, J.; Bartha, E. B.; Torek, O.; Torma, Cs.

2010-09-01

Heat wave events are important temperature-related climatological extremes due to their impacts on human health. In the future, they are very likely to occur more frequently and more intensely not only in the Carpathian Basin, but in most regions of the world because of global warming. In order to develop adaptation and mitigation strategies on local scale, it is essential to analyze the projected changes related to heat waves. In Hungary, three categories of heat wave warning are applied. They are associated to the daily mean temperature values. (i) Warning category 1 is issued when the daily mean temperature is larger than 25 °C. (ii) Warning category 2 is issued when the daily mean temperature for at least 3 consecutive days is larger than 25 °C. (iii) Warning category 3 is issued when the daily mean temperature for at least 3 consecutive days is larger than 27 °C. In this poster, frequency of these conditions are analyzed using regional climate model experiments of model RegCM with 10-km horizontal resolution adapted at the Department of Meteorology, Eotvos Lorand University in the frame of the CECILIA EU-project. The model RegCM is a 3-dimensional, sigma-coordinate, primitive equation model, and it was originally developed by Giorgi et al. Currently, it is available from the ICTP (International Centre for Theoretical Physics). The initial and lateral boundary conditions of the fine-resolution experiments have been provided by the global climate model ECHAM for the A1B emission scenario for three different time slices (1961-1990, 2021-2050, and 2071-2100).

Physical characteristics and dynamics of the coastal Latex09 Eddy derived from in situ data and numerical modeling

NASA Astrophysics Data System (ADS)

Kersalé, M.; Petrenko, A. A.; Doglioli, A. M.; Dekeyser, I.; Nencioli, F.

2013-01-01

investigate the dynamics of a coastal anticyclonic eddy in the western part of the Gulf of Lion (GoL) in the northwestern Mediterranean Sea during the Latex campaign in the summer 2009 (Latex09). The sampling strategy combines sea surface temperature satellite imagery, hull-mounted acoustic Doppler current profiler data, conductivity-temperature-depth casts, and drifter trajectories. Our measurements reveal an anticyclonic eddy (Latex09 eddy) with a diameter of 23 km and maximum depth of 31 m, centered at 3°34'E, 42°33'N. We use a high resolution, three-dimensional, primitive equation numerical model to investigate its generation process and evolution. The model is able to reproduce the observed eddy, in particular its size and position. The model results suggest that the Latex09 eddy is induced by a large anticyclonic circulation in the northwestern part of the GoL, pushed and squeezed toward the coast by a meander of the Northern Current. This represents a new generation mechanism that has not been reported before. The post generation dynamics of the eddy is also captured by the model. The collision of the Latex09 eddy with Cape Creus results in a transient structure, which is depicted by the trajectories of two Lagrangian drifters during Latex09. The transient structure and its advection lead to a transfer of mass and vorticity from the GoL to the Catalan shelf, indicating the importance of mesoscale structures in modulating such exchanges in the region.

THOR: an open-source exo-GCM

NASA Astrophysics Data System (ADS)

Grosheintz, Luc; Mendonça, João; Käppeli, Roger; Lukas Grimm, Simon; Mishra, Siddhartha; Heng, Kevin

2015-12-01

In this talk, I will present THOR, the first fully conservative, GPU-accelerated exo-GCM (general circulation model) on a nearly uniform, global grid that treats shocks and is non-hydrostatic. THOR will be freely available to the community as a standard tool.Unlike most GCMs THOR solves the full, non-hydrostatic Euler equations instead of the primitive equations. The equations are solved on a global three-dimensional icosahedral grid by a second order Finite Volume Method (FVM). Icosahedral grids are nearly uniform refinements of an icosahedron. We've implemented three different versions of this grid. FVM conserves the prognostic variables (density, momentum and energy) exactly and doesn't require a diffusion term (artificial viscosity) in the Euler equations to stabilize our solver. Historically FVM was designed to treat discontinuities correctly. Hence it excels at resolving shocks, including those present in hot exoplanetary atmospheres.Atmospheres are generally in near hydrostatic equilibrium. We therefore implement a well-balancing technique recently developed at the ETH Zurich. This well-balancing ensures that our FVM maintains hydrostatic equilibrium to machine precision. Better yet, it is able to resolve pressure perturbations from this equilibrium as small as one part in 100'000. It is important to realize that these perturbations are significantly smaller than the truncation error of the same scheme without well-balancing. If during the course of the simulation (due to forcing) the atmosphere becomes non-hydrostatic, our solver continues to function correctly.THOR just passed an important mile stone. We've implemented the explicit part of the solver. The explicit solver is useful to study instabilities or local problems on relatively short time scales. I'll show some nice properties of the explicit THOR. An explicit solver is not appropriate for climate study because the time step is limited by the sound speed. Therefore, we are working on the first fully implicit GCM. By ESS3, I hope to present results for the advection equation.THOR is part of the Exoclimes Simulation Platform (ESP), a set of open-source community codes for simulating and understanding the atmospheres of exoplanets. The ESP also includes tools for radiative transfer and retrieval (HELIOS), an opacity calculator (HELIOS-K), and a chemical kinetics solver (VULCAN). We expect to publicly release an initial version of THOR in 2016 on www.exoclime.org.

Density of Primitive Pythagorean Triples

ERIC Educational Resources Information Center

Killen, Duncan A.

2004-01-01

Based on the properties of a Primitive Pythagorean Triple (PPT), a computer program was written to generate, print, and count all PPTs greater than or equal to I[subscript x], where I[subscript x] is an arbitrarily chosen integer. The Density of Primitive Pythagorean Triples may be defined as the ratio of the number of PPTs whose hypotenuse is…

A Discussion on the Substitution Method for Trigonometric Rational Functions

ERIC Educational Resources Information Center

Ponce-Campuzano, Juan Carlos; Rivera-Figueroa, Antonio

2011-01-01

It is common to see, in the books on calculus, primitives of functions (some authors use the word "antiderivative" instead of primitive). However, the majority of authors pay scant attention to the domains over which the primitives are valid, which could lead to errors in the evaluation of definite integrals. In the teaching of calculus, in…

Scientific Terminology and Minimum Terms in Speech Communication: Some Philosophical Ramblings.

ERIC Educational Resources Information Center

Krivonos, Paul D.; Sussman, Lyle.

Philosophers of science have emphasized the need for primitive terms, or "givens," in the construction of theory for any discipline. While there are inherent dangers regarding the use of primitive terms, they can have great value in serving as the basis for minimum terms, which are primitive terms unique to a discipline. (Borrowed terms are those…

Saturn: Origin and composition of its inner moons and rings

NASA Technical Reports Server (NTRS)

Prentice, A. J. R.

1980-01-01

The contraction of the primitive protosaturnian cloud, using ideas of supersonic turbulent convection was modeled. The model suggested that each of Saturn's inner moons, excepting Rhea, condensed above the ice-point of water and consists primarily of hydrous magnesium silicates. The satellite mean densities steadily increase towards the planet and the rocky moons are irregular in shape.

A Hierarchical and Contextual Model for Learning and Recognizing Highly Variant Visual Categories

DTIC Science & Technology

2010-01-01

neighboring pattern primitives, to create our model. We also present a minimax entropy framework for automatically learning which contextual constraints are...Grammars . . . . . . . . . . . . . . . . . . 19 3.2 Markov Random Fields . . . . . . . . . . . . . . . . . . . . . . . . 23 3.3 Creating a Contextual...Compositional Boosting. . . . . 119 7.8 Top-down hallucinations of missing objects. . . . . . . . . . . . . . . 121 7.9 The bottom-up to top-down

Numerical simulation using vorticity-vector potential formulation

NASA Technical Reports Server (NTRS)

Tokunaga, Hiroshi

1993-01-01

An accurate and efficient computational method is needed for three-dimensional incompressible viscous flows in engineering applications. On solving the turbulent shear flows directly or using the subgrid scale model, it is indispensable to resolve the small scale fluid motions as well as the large scale motions. From this point of view, the pseudo-spectral method is used so far as the computational method. However, the finite difference or the finite element methods are widely applied for computing the flow with practical importance since these methods are easily applied to the flows with complex geometric configurations. However, there exist several problems in applying the finite difference method to direct and large eddy simulations. Accuracy is one of most important problems. This point was already addressed by the present author on the direct simulations on the instability of the plane Poiseuille flow and also on the transition to turbulence. In order to obtain high efficiency, the multi-grid Poisson solver is combined with the higher-order, accurate finite difference method. The formulation method is also one of the most important problems in applying the finite difference method to the incompressible turbulent flows. The three-dimensional Navier-Stokes equations have been solved so far in the primitive variables formulation. One of the major difficulties of this method is the rigorous satisfaction of the equation of continuity. In general, the staggered grid is used for the satisfaction of the solenoidal condition for the velocity field at the wall boundary. However, the velocity field satisfies the equation of continuity automatically in the vorticity-vector potential formulation. From this point of view, the vorticity-vector potential method was extended to the generalized coordinate system. In the present article, we adopt the vorticity-vector potential formulation, the generalized coordinate system, and the 4th-order accurate difference method as the computational method. We present the computational method and apply the present method to computations of flows in a square cavity at large Reynolds number in order to investigate its effectiveness.

Optimal Observations for Variational Data Assimilation

NASA Technical Reports Server (NTRS)

Koehl, Armin; Stammer, Detlef

2003-01-01

An important aspect of Ocean state estimation is the design of an observing system that allows the efficient study of climate aspects in the ocean. A solution of the design problem is presented here in terms of optimal observations that emerge as nondimensionalized singular vectors of the modified data resolution matrix. The actual computation is feasible only for scalar quantities in the limit of large observational errors. In the framework of a lo resolution North Atlantic primitive equation model it is demonstrated that such optimal observations when applied to determining the strength of the volume and heat transport across the Greenland-Scotland ridge, perform significantly better than traditional section data. On seasonal to inter-annual time-scales optimal observations are located primarily along the continental shelf and information about heat-transport, wind stress and stratification is being communicated via boundary waves and advective processes. On time-scales of about a month, sea surface height observations appear to be more efficient in reconstructing the cross-ridge heat transport than hydrographic observations. Optimal observations also provide a tool for understanding how the ocean state is effected by anomalies of integral quantities such as meridional heat transport.

Recent Developments in the VISRAD 3-D Target Design and Radiation Simulation Code

NASA Astrophysics Data System (ADS)

Macfarlane, Joseph; Golovkin, Igor; Sebald, James

2017-10-01

The 3-D view factor code VISRAD is widely used in designing HEDP experiments at major laser and pulsed-power facilities, including NIF, OMEGA, OMEGA-EP, ORION, Z, and LMJ. It simulates target designs by generating a 3-D grid of surface elements, utilizing a variety of 3-D primitives and surface removal algorithms, and can be used to compute the radiation flux throughout the surface element grid by computing element-to-element view factors and solving power balance equations. Target set-up and beam pointing are facilitated by allowing users to specify positions and angular orientations using a variety of coordinates systems (e.g., that of any laser beam, target component, or diagnostic port). Analytic modeling for laser beam spatial profiles for OMEGA DPPs and NIF CPPs is used to compute laser intensity profiles throughout the grid of surface elements. VISRAD includes a variety of user-friendly graphics for setting up targets and displaying results, can readily display views from any point in space, and can be used to generate image sequences for animations. We will discuss recent improvements to conveniently assess beam capture on target and beam clearance of diagnostic components, as well as plans for future developments.

Comet Dust: The Diversity of "Primitive" Particles and Implications

NASA Technical Reports Server (NTRS)

Wooden, Diane H.; Ishii, Hope A.; Bradley, John P.; Zolensky, Michael E.

2016-01-01

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive particles has expanded significantly through microscale investigations of cosmic dust samples ( IDP's(Interplanetary Dust Particles) and AMM's (Antarctic Micrometeorites)) and of comet dust samples (Stardust and Rosetta's COSIMA), as well as through remote sensing (spectroscopy and imaging) via Spitzer and via spacecraft encounters with 103P/Hartley 2 and 67P/Churyumov-Gerasimenko. Microscale investigations show that comet dust and cosmic dust are particles of unequilibrated materials, including aggregates of materials unequilibrated at submicron scales. We call unequilibrated materials "primitive" and we deduce they were incorporated into ice-rich (H2O-, CO2-, and CO-ice) parent bodies that remained cold, i.e., into comets, because of the lack of aqueous or thermal alteration since particle aggregation; yet some Stardust olivines suggest mild thermal metamorphism. Primitive particles exhibit a diverse range of: structure and typology; size and size distribution of constituents; concentration and form of carbonaceous and organic matter; D-, N-, and O- isotopic enhancements over solar; Mg-, Fe-contents of the silicate minerals; the compositions and concentrations of sulfides, and of less abundant mineral species such as chondrules, CAIs and carbonates. The uniformity within a group of samples points to: aerodynamic sorting of particles and/or particle constituents; the inclusion of a limited range of oxygen fugacities; the inclusion or exclusion of chondrules; a selection of organics. The properties of primitive particles imply there were disk processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disk present at the time and in the region where the comets formed.

Comet Dust: The Diversity of Primitive Particles and Implications

NASA Technical Reports Server (NTRS)

John Bradley; Zolensky, Michael E.

2016-01-01

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive particles has expanded significantly through microscale investigations of cosmic dust samples (IDPs and AMMs) and of comet dust samples (Stardust and Rosetta's COSIMA), as well as through remote sensing (spectroscopy and imaging) via Spitzer and via spacecraft encounters with 103P/Hartley 2 and 67P/Churyumov-Gerasimenko. Microscale investigations show that comet dust and cosmic dust are particles of unequilibrated materials, including aggregates of materials unequilibrated at submicron scales. We call unequilibrated materials "primitive" and we deduce they were incorporated into ice-­-rich (H2O-, CO2-, and CO-ice) parent bodies that remained cold, i.e., into comets, because of the lack of aqueous or thermal alteration since particle aggregation; yet some Stardust olivines suggest mild thermal metamorphism. Primitive particles exhibit a diverse range of: structure and typology; size and size distribution of constituents; concentration and form of carbonaceous and organic matter; D-, N-, and O- isotopic enhancements over solar; Mg-, Fe-contentsof thesilicate minerals; the compositions and concentrations of sulfides, and of less abundant mineral species such as chondrules, CAIs and carbonates. The unifomity within a group of samples points to: aerodynamic sorting of particles and/or particle constituents; the inclusion of a limited range of oxygen fugacities; the inclusion or exclusion of chondrules; a selection of organics. The properites of primitive particles imply there were disk processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disk present at the time and in the region where the comets formed.

Effect of equilibration on primitive path analyses of entangled polymers.

PubMed

Hoy, Robert S; Robbins, Mark O

2005-12-01

We use recently developed primitive path analysis (PPA) methods to study the effect of equilibration on entanglement density in model polymeric systems. Values of Ne for two commonly used equilibration methods differ by a factor of 2-4 even though the methods produce similar large-scale chain statistics. We find that local chain stretching in poorly equilibrated samples increases entanglement density. The evolution of Ne with time shows that many entanglements are lost through fast processes such as chain retraction as the local stretching relaxes. Quenching a melt state into a glass has little effect on Ne. Equilibration-dependent differences in short-scale structure affect the craze extension ratio much less than expected from the differences in PPA values of Ne.

Circuit design tool. User's manual, revision 2

NASA Technical Reports Server (NTRS)

Miyake, Keith M.; Smith, Donald E.

1992-01-01

The CAM chip design was produced in a UNIX software environment using a design tool that supports definition of digital electronic modules, composition of these modules into higher level circuits, and event-driven simulation of these circuits. Our design tool provides an interface whose goals include straightforward but flexible primitive module definition and circuit composition, efficient simulation, and a debugging environment that facilitates design verification and alteration. The tool provides a set of primitive modules which can be composed into higher level circuits. Each module is a C-language subroutine that uses a set of interface protocols understood by the design tool. Primitives can be altered simply by recoding their C-code image; in addition new primitives can be added allowing higher level circuits to be described in C-code rather than as a composition of primitive modules--this feature can greatly enhance the speed of simulation.

Retention of primitive reflexes and delayed motor development in very low birth weight infants.

PubMed

Marquis, P J; Ruiz, N A; Lundy, M S; Dillard, R G

1984-06-01

Primitive reflexes and motor development were evaluated in 127 very low birth weight (VLBW) infants (birth weight less than 1501 grams) at four months corrected age. The asymmetrical tonic neck reflex, tonic labyrinth reflex, and Moro reflex were assessed for each child. The ability of each child to reach (obtain a red ring) and roll were observed. The child's performance on the gross motor scale of the Denver Development Screening Test was recorded. Thirty-seven term infants were administered identical evaluations at four months of age. The VLBW infants retained stronger primitive reflexes and exhibited a significantly higher incidence of motor delays than term infants. Significant correlations existed between the strength of the primitive reflexes and early motor development for VLBW infants. This study confirms a high incidence of motor delays among VLBW infants and demonstrates a clear association between retained primitive reflexes and delayed motor development in VLBW infants.

RIPE integrity primitives, part 2 (RACE Integrity Primitives Evaluation)

NASA Astrophysics Data System (ADS)

Denboer, B.; Boly, J. P.; Bosselaers, A.; Brandt, J.; Chaum, D.; Damgaard, I.; Dichtl, M.; Fumy, W.; Vanderham, M.; Jansen, C. J. A.

1993-04-01

A manual intended for those seeking to secure information systems by applying modern cryptography is presented. It represents the successful attainment of goals by RIPE (RACE (Research and development of Advanced Communications technology in Europe) Integrity Primitives Evaluation). The recommended portfolio of integrity primitives, which is the main product of the project, forms the heart of the manual. By integrity, is meant the kinds of security that can be achieved through cryptography, apart from keeping messages secret. Thus included are ways to ensure that stored or communicated data is not illicitly modified, that parties exchanging messages are actually present, and that 'signed' electronic messages can be recognized as authentic by anyone. Of particular concern to the project were the high speed requirements of broadband communication. The project also aimed for completeness in its recommendations. As a result, the portfolio contains primitives, that is building blocks, that can meet most of today's perceived needs for integrity.

RIPE integrity primitives, part 1 (RACE Integrity Primitives Evaluation)

NASA Astrophysics Data System (ADS)

Denboer, B.; Boly, J. P.; Bosselaers, A.; Brandt, J.; Chaum, D.; Damgaard, I.; Dichtl, M.; Fumy, W.; Vanderham, M.; Jansen, C. J. A.

1993-04-01

A manual intended for those seeking to secure information systems by applying modern cryptography is presented. It represents the successful attainment of goals by RIPE (RACE (Research and development of Advanced Communication technology in Europe) Integrity Primitives Evaluation). The recommended portfolio of integrity primitives, which is the main product of the project, forms the heart of the manual. By integrity, is meant the kinds of security that can be achieved through cryptography, apart from keeping messages secret. Thus included are ways to ensure that stored or communicated data is not illicitly modified, that parties exchanging messages are actually present, and that 'signed' electronic messages can be recognized as authentic by anyone. Of particular concern to the project were the high speed requirements of broadband communication. The project also aimed for completeness in its recommendations. As a result, the portfolio contains primitives, that is building blocks, that can meet most of today's perceived needs for integrity.

Designers Workbench: Towards Real-Time Immersive Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuester, F; Duchaineau, M A; Hamann, B

2001-10-03

This paper introduces the DesignersWorkbench, a semi-immersive virtual environment for two-handed modeling, sculpting and analysis tasks. The paper outlines the fundamental tools, design metaphors and hardware components required for an intuitive real-time modeling system. As companies focus on streamlining productivity to cope with global competition, the migration to computer-aided design (CAD), computer-aided manufacturing (CAM), and computer-aided engineering (CAE) systems has established a new backbone of modern industrial product development. However, traditionally a product design frequently originates from a clay model that, after digitization, forms the basis for the numerical description of CAD primitives. The DesignersWorkbench aims at closing this technologymore » or ''digital gap'' experienced by design and CAD engineers by transforming the classical design paradigm into its filly integrated digital and virtual analog allowing collaborative development in a semi-immersive virtual environment. This project emphasizes two key components from the classical product design cycle: freeform modeling and analysis. In the freeform modeling stage, content creation in the form of two-handed sculpting of arbitrary objects using polygonal, volumetric or mathematically defined primitives is emphasized, whereas the analysis component provides the tools required for pre- and post-processing steps for finite element analysis tasks applied to the created models.« less

MOCASSIM - an operational forecast system for the Portuguese coastal waters.

NASA Astrophysics Data System (ADS)

Vitorino, J.; Soares, C.; Almeida, S.; Rusu, E.; Pinto, J.

2003-04-01

An operational system for the forecast of oceanographic conditions off the Portuguese coast is presently being implemented at Instituto Hidrográfico (IH), in the framework of project MOCASSIM. The system is planned to use a broad range of observations provided both from IH observational networks (wave buoys, tidal gauges) and programs (hydrographic surveys, moorings) as well as from external sources. The MOCASSIM system integrates several numerical models which, combined, are intended to cover the relevant physical processes observed in the geographical areas of interest. At the present stage of development the system integrates a circulation module and a wave module. The circulation module is based on the Harvard Ocean Prediction System (HOPS), a primitive equation model formulated under the rigid lid assumption, which includes a data assimilation module. The wave module is based on the WaveWatch3 (WW3) model, which provides wave conditions in the North Atlantic basin, and on the SWAN model which is used to improve the wave forecasts on coastal or other specific areas of interest. The models use the meteorological forcing fields of a limited area model (ALADIN model) covering the Portuguese area, which are being provided in the framework of a close colaboration with Instituto de Meteorologia. Although still under devellopment, the MOCASSIM system has already been used in several operationnal contexts. These included the operational environmental assessment during both national and NATO navy exercises and, more recently, the monitoring of the oceanographic conditions in the NW Iberian area affected by the oil spill of MV "Prestige". The system is also a key component of ongoing research on the oceanography of the Portuguese continental margin, which is presently being conducted at IH in the framework of national and European funded projects.

Observational and Modeling Studies of Radiative, Chemical, and Dynamical Interactions in the Earth''s Atmosphere

NASA Technical Reports Server (NTRS)

Salby, Murry

1998-01-01

A 3-dimensional model was developed to support mechanistic studies. The model solves the global primitive equations in isentropic coordinates, which directly characterize diabatic processes forcing the Brewer-Dobson circulation of the middle atmosphere. It's numerical formulation is based on Hough harmonics, which partition horizontal motion into its rotational and divergent components. These computational features, along with others, enable 3D integrations to be performed practically on RISC computer architecture, on which they can be iterated to support mechanistic studies. The model conserves potential vorticity quite accurately under adiabatic conditions. Forced by observed tropospheric structure, in which integrations are anchored, the model generates a diabatic circulation that is consistent with satellite observations of tracer behavior and diabatic cooling rates. The model includes a basic but fairly complete treatment of gas-phase photochemistry that represents some 20 chemical species and 50 governing reactions with diurnally-varying shortwave absorption. The model thus provides a reliable framework to study transport and underlying diabatic processes, which can then be compared against chemical and dynamical structure observed and in GCM integrations. Integrations with the Langley GCM were performed to diagnose feedback between simulated convection and the tropical circulation. These were studied in relation to tropospheric properties controlling moisture convergence and environmental conditions supporting deep convection, for comparison against mechanistic integrations of wave CISK that successfully reproduce the Madden-Julian Oscillation (MJO) of the tropical circulation. These comparisons were aimed at identifying and ultimately improving aspects of the convective simulation, with the objective of recovering a successful simulation of the MJO in the Langley GCM, behavior that should be important to budgets of upper-tropospheric water vapor and chemical species.

Fast concurrent array-based stacks, queues and deques using fetch-and-increment-bounded, fetch-and-decrement-bounded and store-on-twin synchronization primitives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dong; Gara, Alana; Heidelberger, Philip

Implementation primitives for concurrent array-based stacks, queues, double-ended queues (deques) and wrapped deques are provided. In one aspect, each element of the stack, queue, deque or wrapped deque data structure has its own ticket lock, allowing multiple threads to concurrently use multiple elements of the data structure and thus achieving high performance. In another aspect, new synchronization primitives FetchAndIncrementBounded (Counter, Bound) and FetchAndDecrementBounded (Counter, Bound) are implemented. These primitives can be implemented in hardware and thus promise a very fast throughput for queues, stacks and double-ended queues.

Probabilistic structural analysis of a truss typical for space station

NASA Technical Reports Server (NTRS)

Pai, Shantaram S.

1990-01-01

A three-bay, space, cantilever truss is probabilistically evaluated using the computer code NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) to identify and quantify the uncertainties and respective sensitivities associated with corresponding uncertainties in the primitive variables (structural, material, and loads parameters) that defines the truss. The distribution of each of these primitive variables is described in terms of one of several available distributions such as the Weibull, exponential, normal, log-normal, etc. The cumulative distribution function (CDF's) for the response functions considered and sensitivities associated with the primitive variables for given response are investigated. These sensitivities help in determining the dominating primitive variables for that response.

Origin and Evolutionary Alteration of the Mitochondrial Import System in Eukaryotic Lineages.

PubMed

Fukasawa, Yoshinori; Oda, Toshiyuki; Tomii, Kentaro; Imai, Kenichiro

2017-07-01

Protein transport systems are fundamentally important for maintaining mitochondrial function. Nevertheless, mitochondrial protein translocases such as the kinetoplastid ATOM complex have recently been shown to vary in eukaryotic lineages. Various evolutionary hypotheses have been formulated to explain this diversity. To resolve any contradiction, estimating the primitive state and clarifying changes from that state are necessary. Here, we present more likely primitive models of mitochondrial translocases, specifically the translocase of the outer membrane (TOM) and translocase of the inner membrane (TIM) complexes, using scrutinized phylogenetic profiles. We then analyzed the translocases' evolution in eukaryotic lineages. Based on those results, we propose a novel evolutionary scenario for diversification of the mitochondrial transport system. Our results indicate that presequence transport machinery was mostly established in the last eukaryotic common ancestor, and that primitive translocases already had a pathway for transporting presequence-containing proteins. Moreover, secondary changes including convergent and migrational gains of a presequence receptor in TOM and TIM complexes, respectively, likely resulted from constrained evolution. The nature of a targeting signal can constrain alteration to the protein transport complex. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Hierarchical Aligned Cluster Analysis for Temporal Clustering of Human Motion.

PubMed

Zhou, Feng; De la Torre, Fernando; Hodgins, Jessica K

2013-03-01

Temporal segmentation of human motion into plausible motion primitives is central to understanding and building computational models of human motion. Several issues contribute to the challenge of discovering motion primitives: the exponential nature of all possible movement combinations, the variability in the temporal scale of human actions, and the complexity of representing articulated motion. We pose the problem of learning motion primitives as one of temporal clustering, and derive an unsupervised hierarchical bottom-up framework called hierarchical aligned cluster analysis (HACA). HACA finds a partition of a given multidimensional time series into m disjoint segments such that each segment belongs to one of k clusters. HACA combines kernel k-means with the generalized dynamic time alignment kernel to cluster time series data. Moreover, it provides a natural framework to find a low-dimensional embedding for time series. HACA is efficiently optimized with a coordinate descent strategy and dynamic programming. Experimental results on motion capture and video data demonstrate the effectiveness of HACA for segmenting complex motions and as a visualization tool. We also compare the performance of HACA to state-of-the-art algorithms for temporal clustering on data of a honey bee dance. The HACA code is available online.

Experimental Validation of Motor Primitive-Based Control for Leg Exoskeletons during Continuous Multi-Locomotion Tasks

PubMed Central

Ruiz Garate, Virginia; Parri, Andrea; Yan, Tingfang; Munih, Marko; Molino Lova, Raffaele; Vitiello, Nicola; Ronsse, Renaud

2017-01-01

An emerging approach to design locomotion assistive devices deals with reproducing desirable biological principles of human locomotion. In this paper, we present a bio-inspired controller for locomotion assistive devices based on the concept of motor primitives. The weighted combination of artificial primitives results in a set of virtual muscle stimulations. These stimulations then activate a virtual musculoskeletal model producing reference assistive torque profiles for different locomotion tasks (i.e., walking, ascending stairs, and descending stairs). The paper reports the validation of the controller through a set of experiments conducted with healthy participants. The proposed controller was tested for the first time with a unilateral leg exoskeleton assisting hip, knee, and ankle joints by delivering a fraction of the computed reference torques. Importantly, subjects performed a track involving ground-level walking, ascending stairs, and descending stairs and several transitions between these tasks. These experiments highlighted the capability of the controller to provide relevant assistive torques and to effectively handle transitions between the tasks. Subjects displayed a natural interaction with the device. Moreover, they significantly decreased the time needed to complete the track when the assistance was provided, as compared to wearing the device with no assistance. PMID:28367121

Induced-Pluripotent-Stem-Cell-Derived Primitive Macrophages Provide a Platform for Modeling Tissue-Resident Macrophage Differentiation and Function.

PubMed

Takata, Kazuyuki; Kozaki, Tatsuya; Lee, Christopher Zhe Wei; Thion, Morgane Sonia; Otsuka, Masayuki; Lim, Shawn; Utami, Kagistia Hana; Fidan, Kerem; Park, Dong Shin; Malleret, Benoit; Chakarov, Svetoslav; See, Peter; Low, Donovan; Low, Gillian; Garcia-Miralles, Marta; Zeng, Ruizhu; Zhang, Jinqiu; Goh, Chi Ching; Gul, Ahmet; Hubert, Sandra; Lee, Bernett; Chen, Jinmiao; Low, Ivy; Shadan, Nurhidaya Binte; Lum, Josephine; Wei, Tay Seok; Mok, Esther; Kawanishi, Shohei; Kitamura, Yoshihisa; Larbi, Anis; Poidinger, Michael; Renia, Laurent; Ng, Lai Guan; Wolf, Yochai; Jung, Steffen; Önder, Tamer; Newell, Evan; Huber, Tara; Ashihara, Eishi; Garel, Sonia; Pouladi, Mahmoud A; Ginhoux, Florent

2017-07-18

Tissue macrophages arise during embryogenesis from yolk-sac (YS) progenitors that give rise to primitive YS macrophages. Until recently, it has been impossible to isolate or derive sufficient numbers of YS-derived macrophages for further study, but data now suggest that induced pluripotent stem cells (iPSCs) can be driven to undergo a process reminiscent of YS-hematopoiesis in vitro. We asked whether iPSC-derived primitive macrophages (iMacs) can terminally differentiate into specialized macrophages with the help of growth factors and organ-specific cues. Co-culturing human or murine iMacs with iPSC-derived neurons promoted differentiation into microglia-like cells in vitro. Furthermore, murine iMacs differentiated in vivo into microglia after injection into the brain and into functional alveolar macrophages after engraftment in the lung. Finally, iPSCs from a patient with familial Mediterranean fever differentiated into iMacs with pro-inflammatory characteristics, mimicking the disease phenotype. Altogether, iMacs constitute a source of tissue-resident macrophage precursors that can be used for biological, pathophysiological, and therapeutic studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Studying the hopping parameters of half-Heusler NaAuS using maximally localized Wannier function

NASA Astrophysics Data System (ADS)

Sihi, Antik; Lal, Sohan; Pandey, Sudhir K.

2018-04-01

Here, the electronic behavior of half-Heusler NaAuS is studied using PBEsol exchange correlation functional by plotting the band structure curve. These bands are reproduced using maximally localized Wannier function using WANNIER90. Tight-binding bands are nicely matched with density functional theory bands. By fitting the tight-binding model, hopping parameter for NaAuS is obtained by including Na 2s, 2p, Au 6s, 5p, 5d and S 3s, 3p orbitals within the energy interval of -5 to 16 eV around the Fermi level. In present study, hopping integrals for NaAuS are computed for the first primitive unit cell atoms as well as the first nearest neighbor primitive unit cell. The most dominating hopping integrals are found for Na (3s) - S (3s), Na (2px) - S (2px), Au (6s) - S (3px), Au (6s) - S (3py) and Au (6s) - S (3pz) orbitals. The hopping integrals for the first nearest neighbor primitive unit cell are also discussed in this manuscript. In future, these hopping integrals are very important to find the topological invariant for NaAuS compound.

Planetesimals Born Big by Clustering Instability?

NASA Technical Reports Server (NTRS)

Cuzzi, Jeffrey N.; Hartlep, Thomas; Simon, Justin I.; Estrada, Paul R.

2017-01-01

Roughly 100km diameter primitive bodies (today's asteroids and TNOs; [1]) are thought to be the end product of so-called "primary accretion". They dominated the initial mass function of planetesimals, and precipitated the onset of a subsequent stage, characterized by runaway gravitational effects, which proceeded onwards to planetary mass objects, some of which accreted massive gas envelopes. Asteroids are the parents of primitive meteorites; meteorite data suggest that asteroids initially formed directly from freelyfloating nebula particles in the mm-size range. Unfortunately, the process by which these primary 100km diameter planetesimals formed remains problematic. We review the most diagnostic primitive parent body observations, highlight critical aspects of the nebula context, and describe the issues facing various primary accretion models. We suggest a path forward that combines current scenarios of "turbulent concentration" (TC) and "streaming instabilities" (SI) into a triggered formation process we call clustering instability (CI). Under expected conditions of nebula turbulence, the success of these processes at forming terrestrial region (mostly silicate) planetesimals requires growth by sticking into aggregates in the several cm size range, at least, which is orders of magnitude more massive than allowed by current growth-by-sticking models using current experimental sticking parameters [2-4]. The situation is not as dire in the ice-rich outer solar system; however, growth outside of the snowline has important effects on growth inside of it [4] and at least one aspect of outer solar system planetesimals (high binary fraction) supports some kind of clustering instability.

Planetesimals Born Big by Clustering Instability?

NASA Technical Reports Server (NTRS)

Cuzzi, Jeffrey N.; Hartlep, Thomas; Simon, Justin I.; Estrada, Paul R.

2017-01-01

Roughly 100km diameter primitive bodies (today's asteroids and TNOs; [1]) are thought to be the end product of so-called "primary accretion". They dominated the initial mass function of planetesimals, and precipitated the onset of a subsequent stage, characterized by runaway gravitational effects, which proceeded onwards to planetary mass objects, some of which accreted massive gas envelopes. Asteroids are the parents of primitive meteorites; meteorite data suggest that asteroids initially formed directly from freelyfloating nebula particles in the mm-size range. Unfortunately, the process by which these primary 100km diameter planetesimals formed remains problematic. We review the most diagnostic primitive parent body observations, highlight critical aspects of the nebula context, and describe the issues facing various primary accretion models. We suggest a path forward that combines current scenarios of "turbulent concentration" (TC) and "streaming instabilities" (SI) into a triggered formation process we call clustering instability (CI). Under expected conditions of nebula turbulence, the success of these processes at forming terrestrial region (mostly silicate) planetesimals requires growth by sticking into aggregates in the several cm size range, at least, which is orders of magnitude more massive than allowed by current growth-by-sticking models using current experimental sticking parameters [2-4]. The situation is not as dire in the ice-rich outer solar system; however, growth outside of the snowline has important effects on growth inside of it [4] and at least one aspect of outer solar system planetesimals (high binary fraction) supports some kind of clustering instability

A Darwinian approach to the origin of life cycles with group properties.

PubMed

Rashidi, Armin; Shelton, Deborah E; Michod, Richard E

2015-06-01

A selective explanation for the evolution of multicellular organisms from unicellular ones requires knowledge of both selective pressures and factors affecting the response to selection. Understanding the response to selection is particularly challenging in the case of evolutionary transitions in individuality, because these transitions involve a shift in the very units of selection. We develop a conceptual framework in which three fundamental processes (growth, division, and splitting) are the scaffold for unicellular and multicellular life cycles alike. We (i) enumerate the possible ways in which these processes can be linked to create more complex life cycles, (ii) introduce three genes based on growth, division and splitting that, acting in concert, determine the architecture of the life cycles, and finally, (iii) study the evolution of the simplest five life cycles using a heuristic model of coupled ordinary differential equations in which mutations are allowed in the three genes. We demonstrate how changes in the regulation of three fundamental aspects of colonial form (cell size, colony size, and colony cell number) could lead unicellular life cycles to evolve into primitive multicellular life cycles with group properties. One interesting prediction of the model is that selection generally favors cycles with group level properties when intermediate body size is associated with lowest mortality. That is, a universal requirement for the evolution of group cycles in the model is that the size-mortality curve be U-shaped. Furthermore, growth must decelerate with size. Copyright © 2015 Elsevier Inc. All rights reserved.

An approach to the origin of self-replicating system. I - Intermolecular interactions

NASA Technical Reports Server (NTRS)

Macelroy, R. D.; Coeckelenbergh, Y.; Rein, R.

1978-01-01

The present paper deals with the characteristics and potentialities of a recently developed computer-based molecular modeling system. Some characteristics of current coding systems are examined and are extrapolated to the apparent requirements of primitive prebiological coding systems.

Adaptation of a general circulation model to ocean dynamics

NASA Technical Reports Server (NTRS)

Turner, R. E.; Rees, T. H.; Woodbury, G. E.

1976-01-01

A primitive-variable general circulation model of the ocean was formulated in which fast external gravity waves are suppressed with rigid-lid surface constraint pressires which also provide a means for simulating the effects of large-scale free-surface topography. The surface pressure method is simpler to apply than the conventional stream function models, and the resulting model can be applied to both global ocean and limited region situations. Strengths and weaknesses of the model are also presented.

Features and the ‘primal sketch’

PubMed Central

Morgan, Michael J.

2014-01-01

This review is concerned primarily with psychophysical and physiological evidence relevant to the question of the existence of spatial features or spatial primitives in human vision. The review will be almost exclusively confined to features defined in the luminance domain. The emphasis will be on the experimental and computational methods that have been used for revealing features, rather than on a detailed comparison between different models of feature extraction. Color and texture fall largely outside the scope of the review, though the principles may be similar. Stereo matching and motion matching are also largely excluded because they are covered in other contributions to this volume, although both have addressed the question of the spatial primitives involved in matching. Similarities between different psychophysically-based model will be emphasized rather than minor differences. All the models considered in the review are based on the extraction of directional spatial derivatives of the luminance profile, typically the first and second, but in one case the third order, and all have some form of non-linearity, be it rectification or thresholding. PMID:20696182

Modeling Nucleation and Grain Growth in the Solar Nebula: Initial Progress Report

NASA Technical Reports Server (NTRS)

Nuth, Joseph A.; Paquette, J. A.; Ferguson, F. T.

2010-01-01

The primitive solar nebula was a violent and chaotic environment where high energy collisions, lightning, shocks and magnetic re-connection events rapidly vaporized some fraction of nebular dust, melted larger particles while leaving the largest grains virtually undisturbed. At the same time, some tiny grains containing very easily disturbed noble gas signatures (e.g., small, pre-solar graphite or SiC particles) never experienced this violence, yet can be found directly adjacent to much larger meteoritic components (chondrules or CAIs) that did. Additional components in the matrix of the most primitive carbonaceous chondrites and in some chondritic porous interplanetary dust particles include tiny nebular condensates, aggregates of condensates and partially annealed aggregates. Grains formed in violent transient events in the solar nebula did not come to equilibrium with their surroundings. To understand the formation and textures of these materials as well as their nebular abundances we must rely on Nucleation Theory and kinetic models of grain growth, coagulation and annealing. Such models have been very uncertain in the past: we will discuss the steps we are taking to increase their reliability.

Modeling with Livingstone

NASA Technical Reports Server (NTRS)

Kurien, J.; Nayak, P.; Williams, B.; Koga, Dennis (Technical Monitor)

1998-01-01

MPL is the language with which a modeler describes a system to be diagnosed or controlled by Livingstone. MPL is used to specify what are the components of the system, how they are interconnected, and how they behave both nominally and when failed. Component behavioral models used by Livingstone are described by a set of propositional, well-formed formula (wff). An understanding of well-formed formula, primitive component types specified through defcomponent, and device structure specified by defmodule, is essential to understanding of MPL, This document describes: welI-formed formula (wff): The basis for describing the behavior of a component in a system defvalues: Specifies the domain (legal values) of a variable defcomponent: Defines the modes, behaviors and mode transitions for primitive components deftnodule: Defines composite devices, consisting of interconnected components defrelation: A macro mechanism for expanding a complex wff according to the value of an argument forall: An iteration construct used to expand a wff or relation on a set of arguments defsymbol-expansion: A mechanism for naming a collection of symbols (eg the name of all valves in the system)

Inspection of aeronautical mechanical parts with a pan-tilt-zoom camera: an approach guided by the computer-aided design model

NASA Astrophysics Data System (ADS)

Viana, Ilisio; Orteu, Jean-José; Cornille, Nicolas; Bugarin, Florian

2015-11-01

We focus on quality control of mechanical parts in aeronautical context using a single pan-tilt-zoom (PTZ) camera and a computer-aided design (CAD) model of the mechanical part. We use the CAD model to create a theoretical image of the element to be checked, which is further matched with the sensed image of the element to be inspected, using a graph theory-based approach. The matching is carried out in two stages. First, the two images are used to create two attributed graphs representing the primitives (ellipses and line segments) in the images. In the second stage, the graphs are matched using a similarity function built from the primitive parameters. The similarity scores of the matching are injected in the edges of a bipartite graph. A best-match-search procedure in the bipartite graph guarantees the uniqueness of the match solution. The method achieves promising performance in tests with synthetic data including missing elements, displaced elements, size changes, and combinations of these cases. The results open good prospects for using the method with realistic data.

Proton Transports in Pure Liquid Water Characterized by Melted Ice Lattice Model

NASA Astrophysics Data System (ADS)

Jie, Binbin; Sah, Chihtang

Basic water properties have not been understood for 200 years. Our Melted Ice Lattice model accounts for the 2 basic properties of pure water, the ion product (pH) and mobilities. It has HCP primitive unit cells, each with 4H2O, based on the 1933 Bernal-Fowler model, verified by 1935 Pauling residual entropy theory of 1928-1935 Giauque experimental low temperature specific heat measurements. Our 2 ion species are point-mass protons p + and p-, for mass and electricity transport. Three protonic thermal activation energies are obtained from pH and p + and p- mobilities vs T (0-100OC). Proton transport is analyzed in 3 proton-phonon collision steps: proton detrapping by protonic phonon absorption, proton scattering by oxygenic (water) phonons, and proton trapping with protonic phonon emission. Distinction between Potential and Kinetic Energy Bands of protons (Fermions) and phonons (Bosons) is noted. Experimental protonic activation energies are the phonon energies given by the spring-mass vibration frequencies of lattice, wn = (kn/mn)1/2 . n is the proton-mass unit of the synchronized vibrating particles in the primitive unit cells.

A method of plane geometry primitive presentation

NASA Astrophysics Data System (ADS)

Jiao, Anbo; Luo, Haibo; Chang, Zheng; Hui, Bin

2014-11-01

Point feature and line feature are basic elements in object feature sets, and they play an important role in object matching and recognition. On one hand, point feature is sensitive to noise; on the other hand, there are usually a huge number of point features in an image, which makes it complex for matching. Line feature includes straight line segment and curve. One difficulty in straight line segment matching is the uncertainty of endpoint location, the other is straight line segment fracture problem or short straight line segments joined to form long straight line segment. While for the curve, in addition to the above problems, there is another difficulty in how to quantitatively describe the shape difference between curves. Due to the problems of point feature and line feature, the robustness and accuracy of target description will be affected; in this case, a method of plane geometry primitive presentation is proposed to describe the significant structure of an object. Firstly, two types of primitives are constructed, they are intersecting line primitive and blob primitive. Secondly, a line segment detector (LSD) is applied to detect line segment, and then intersecting line primitive is extracted. Finally, robustness and accuracy of the plane geometry primitive presentation method is studied. This method has a good ability to obtain structural information of the object, even if there is rotation or scale change of the object in the image. Experimental results verify the robustness and accuracy of this method.

A numerical study of circulation driven by mixing over a submarine bank

NASA Astrophysics Data System (ADS)

Cummins, Patrick F.; Foreman, Michael G. G.

1998-04-01

A primitive equation model is applied to study the spin-up of a linearly stratified, rotating fluid over an isolated topographic bank. The model has vertical eddy mixing coefficients that decay away from the bottom over a specified e-folding scale. No external flows are imposed, and a circulation develops due solely to diffusion over the sea bed. Vertical mixing, coupled with the condition of zero diffusive flux of heat through the sea floor, leads to a distortion of isothermal surfaces near the bottom. The associated radial pressure gradients drive a radial-overturning circulation with upslope flow just above the bottom and downslope flows at greater height. Coriolis forces on the radial flows accelerate a verticallysheared azimuthal (alongslope) circulation. Near the bottom the azimuthal motion is cyclonic (upwelling favourable), while outside the boundary layer, the motion is anticyclonic. Sensitivity experiments show that this pattern is robust and maintained even with constant mixing coefficients. Attention is given to the driving mechanism for the depth-averaged azimuthal motion. An analysis of the relative angular momentum balance determines that the torque associated with bottom stresses drives the anticyclonic depth-averaged flow. In terms of vorticity, the anticyclonic vortex over the bank arises due to the curl of bottom stress divided by the depth. A parameter sensitivity study indicates that the depth-averaged flow is relatively insensitive to variations in the bottom drag coefficient.

Annual and longitudinal variations of the Pacific North Equatorial Countercurrent

NASA Technical Reports Server (NTRS)

Lolk, Nina K.

1992-01-01

The climatological annual cycle of the Pacific North Equatorial Countercurrent (NECC) simulated by an ocean general circulation model (OGCM) was studied. The longitudinal variation of transports, degree of geostrophy, and the relationship between Ekman pumping and vertical displacement of the thermocline were emphasized. The longitudinal variation was explored using six sections along 150 deg E, 180 deg, 160 deg W, 140 deg W, 125 deg W, and 110 deg W. A primitive equation OGCM of the Pacific Ocean was run for three years and the fields used were from the third year. The fields consisted of zonal, meridional, and vertical current components and temperature and salinity averaged every three days. The model was forced with the Hellerman and Rosenstein climatological wind stress. The mean annual eastward transport (19.9 Sv) was largest at 160 deg W. The maximum-current boundaries along 160 deg W were 9.2 deg N (1.0 deg), 5.1 deg N (1.1 deg), and 187 m (90.6 m). The annual-cycle amplitude of the NECC was greatest between 160 deg W and 140 deg W. Although the NECC is geostrophic to the first order, deviations from geostrophy were found in the boreal spring and summer near the southern boundary and near the surface. Meridional local acceleration played a role between 3 deg N-5 deg N.

Impact of modeled microgravity on migration, differentiation, and cell cycle control of primitive human hematopoietic progenitor cells.

PubMed

Plett, P Artur; Abonour, Rafat; Frankovitz, Stacy M; Orschell, Christie M

2004-08-01

Migration, proliferation, and differentiation of bone marrow (BM) hematopoietic stem cells (HSC) are important factors in maintaining hematopoietic homeostasis. Homeostatic control of erythrocytes and lymphocytes is perturbed in humans exposed to microgravity (micro-g), resulting in space flight-induced anemia and immunosuppression. We sought to determine whether any of these anomalies can be explained by micro-g-induced changes in migration, proliferation, and differentiation of human BM CD34+ cells, and whether such changes can begin to explain any of the shifts in hematopoietic homeostasis observed in astronauts. BM CD34+ cells were cultured in modeled micro-g (mmicro-g) using NASA's rotating wall vessels (RWV), or in control cultures at earth gravity for 2 to 18 days. Cells were harvested at different times and CD34+ cells assessed for migration potential, cell-cycle kinetics and regulatory proteins, and maturation status. Culture of BM CD34+ cells in RWV for 2 to 3 days resulted in a significant reduction of stromal cell-derived factor 1 (SDF-1alpha)-directed migration, which correlated with decreased expression of F-actin. Modeled micro-g induced alterations in cell-cycle kinetics that were characterized by prolonged S phase and reduced cyclin A expression. Differentiation of primitive CD34+ cells cultured for 14 to 18 days in RWV favored myeloid cell development at the expense of erythroid development, which was significantly reduced compared to controls. These results illustrate that mmicro-g significantly inhibits the migration potential, cell-cycle progression, and differentiation patterns of primitive BM CD34+ cells, which may contribute to some of the hematologic abnormalities observed in humans during space flight.

Representing clinical guidelines in UMl: a comparative study.

PubMed

Hederman, Lucy; Smutek, Daniel; Wade, Vincent; Knape, Thomas

2002-01-01

Clinical guidelines can be represented using models, such as GLIF, specifically designed for healthcare guidelines. This paper demonstrates that they can also be modelled using a mainstream business modelling language such as UML. The paper presents a guideline in GLIF and as UML activity diagrams, and then presents a mapping of GLIF primitives to UML. The potential benefits of using a mainstream modelling language are outlined. These include availability of advanced modelling tools, transfer between modelling tools, and automation via business workflow technology.

Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

DTIC Science & Technology

2009-11-01

imaging using two distinct methods7-15: mathematically based models defined by geometric primitives and voxelized models derived from real human...trees to complete them. We also plan to add further detail by defining the Cooper’s ligaments using geometrical NURBS surfaces. Realistic...generated model for the coronary arterial tree based on multislice CT and morphometric data," Medical Imaging 2006: Physics of Medical Imaging 6142

Comparative Anatomy of Maintenance Tasks (CAMT): A Feasibility Study

DTIC Science & Technology

1992-03-01

systems. Methods for task primitive definition were developed, then taken into the field for testing . Task primitives were defined to cover three remove...engine maintenance) and to test whether task primitives developed for one weapon system could have applicability to other weapon systems (Phase 2...requirements, levying MPT constraints and predicting MPT requirements are only ritualistic exercises until the operational test and evaluation of a

Compositionality in neural control: an interdisciplinary study of scribbling movements in primates

PubMed Central

Abeles, Moshe; Diesmann, Markus; Flash, Tamar; Geisel, Theo; Herrmann, Michael; Teicher, Mina

2013-01-01

This article discusses the compositional structure of hand movements by analyzing and modeling neural and behavioral data obtained from experiments where a monkey (Macaca fascicularis) performed scribbling movements induced by a search task. Using geometrically based approaches to movement segmentation, it is shown that the hand trajectories are composed of elementary segments that are primarily parabolic in shape. The segments could be categorized into a small number of classes on the basis of decreasing intra-class variance over the course of training. A separate classification of the neural data employing a hidden Markov model showed a coincidence of the neural states with the behavioral categories. An additional analysis of both types of data by a data mining method provided evidence that the neural activity patterns underlying the behavioral primitives were formed by sets of specific and precise spike patterns. A geometric description of the movement trajectories, together with precise neural timing data indicates a compositional variant of a realistic synfire chain model. This model reproduces the typical shapes and temporal properties of the trajectories; hence the structure and composition of the primitives may reflect meaningful behavior. PMID:24062679

Novel Insights into the Genetic Controls of Primitive and Definitive Hematopoiesis from Zebrafish Models

PubMed Central

Sood, Raman; Liu, Paul

2012-01-01

Hematopoiesis is a dynamic process where initiation and maintenance of hematopoietic stem cells, as well as their differentiation into erythroid, myeloid and lymphoid lineages, are tightly regulated by a network of transcription factors. Understanding the genetic controls of hematopoiesis is crucial as perturbations in hematopoiesis lead to diseases such as anemia, thrombocytopenia, or cancers, including leukemias and lymphomas. Animal models, particularly conventional and conditional knockout mice, have played major roles in our understanding of the genetic controls of hematopoiesis. However, knockout mice for most of the hematopoietic transcription factors are embryonic lethal, thus precluding the analysis of their roles during the transition from embryonic to adult hematopoiesis. Zebrafish are an ideal model organism to determine the function of a gene during embryonic-to-adult transition of hematopoiesis since bloodless zebrafish embryos can develop normally into early larval stage by obtaining oxygen through diffusion. In this review, we discuss the current status of the ontogeny and regulation of hematopoiesis in zebrafish. By providing specific examples of zebrafish morphants and mutants, we have highlighted the contributions of the zebrafish model to our overall understanding of the roles of transcription factors in regulation of primitive and definitive hematopoiesis. PMID:22888355

Concept-based query language approach to enterprise information systems

NASA Astrophysics Data System (ADS)

Niemi, Timo; Junkkari, Marko; Järvelin, Kalervo

2014-01-01

In enterprise information systems (EISs) it is necessary to model, integrate and compute very diverse data. In advanced EISs the stored data often are based both on structured (e.g. relational) and semi-structured (e.g. XML) data models. In addition, the ad hoc information needs of end-users may require the manipulation of data-oriented (structural), behavioural and deductive aspects of data. Contemporary languages capable of treating this kind of diversity suit only persons with good programming skills. In this paper we present a concept-oriented query language approach to manipulate this diversity so that the programming skill requirements are considerably reduced. In our query language, the features which need technical knowledge are hidden in application-specific concepts and structures. Therefore, users need not be aware of the underlying technology. Application-specific concepts and structures are represented by the modelling primitives of the extended RDOOM (relational deductive object-oriented modelling) which contains primitives for all crucial real world relationships (is-a relationship, part-of relationship, association), XML documents and views. Our query language also supports intensional and extensional-intensional queries, in addition to conventional extensional queries. In its query formulation, the end-user combines available application-specific concepts and structures through shared variables.

Xenon Formal Security Policy Model

DTIC Science & Technology

2007-08-14

munication primitives such as locks or semaphores , machine instruction results, hypercall results, traps, and interrupts. For an informal example...communicated on the corresponding side of the parallel oper- ator. Events that are in X ∪ Y are synchronized over the two processes. So if we define

MACROPHAGE AGGREGATES AS BIOMARKERS OF EXPOSURE: FROM FERAL POPULATIONS TO LABORATORY MODELS

EPA Science Inventory

Macrophage aggregates (MAs) are structures within the spleen, kidney and sometimes liver of teleost fishes. They are believed to function much like primitive lymph nodes in that phagocytized material is transported to these areas by macrophages, for destruction, recycling or stor...

Effective screening length and quasiuniversality for the restricted primitive model of an electrolyte solution.

PubMed

Janecek, Jirí; Netz, Roland R

2009-02-21

Monte Carlo simulations for the restricted primitive model of an electrolyte solution above the critical temperature are performed at a wide range of concentrations and temperatures. Thermodynamic properties such as internal energy, osmotic coefficient, activity coefficient, as well as spatial correlation functions are determined. These observables are used to investigate whether quasiuniversality in terms of an effective screening length exists, similar to the role played by the effective electron mass in solid-state physics. To that end, an effective screening length is extracted from the asymptotic behavior of the Fourier-transformed charge-correlation function and plugged into the Debye-Huckel limiting expressions for various thermodynamic properties. Comparison with numerical results is favorable, suggesting that correlation and other effects not captured on the Debye-Huckel limiting level can be successfully incorporated by a single effective parameter while keeping the functional form of Debye-Huckel expressions. We also compare different methods to determine mean ionic activity coefficient in molecular simulations and check the internal consistency of the numerical data.

Fitting primitive shapes in point clouds: a practical approach to improve autonomous underwater grasp specification of unknown objects

NASA Astrophysics Data System (ADS)

Fornas, D.; Sales, J.; Peñalver, A.; Pérez, J.; Fernández, J. J.; Marín, R.; Sanz, P. J.

2016-03-01

This article presents research on the subject of autonomous underwater robot manipulation. Ongoing research in underwater robotics intends to increase the autonomy of intervention operations that require physical interaction in order to achieve social benefits in fields such as archaeology or biology that cannot afford the expenses of costly underwater operations using remote operated vehicles. Autonomous grasping is still a very challenging skill, especially in underwater environments, with highly unstructured scenarios, limited availability of sensors and adverse conditions that affect the robot perception and control systems. To tackle these issues, we propose the use of vision and segmentation techniques that aim to improve the specification of grasping operations on underwater primitive shaped objects. Several sources of stereo information are used to gather 3D information in order to obtain a model of the object. Using a RANSAC segmentation algorithm, the model parameters are estimated and a set of feasible grasps are computed. This approach is validated in both simulated and real underwater scenarios.

System for conversion between the boundary representation model and a constructive solid geometry model of an object

DOEpatents

Christensen, Noel C.; Emery, James D.; Smith, Maurice L.

1988-04-05

A system converts from the boundary representation of an object to the constructive solid geometry representation thereof. The system converts the boundary representation of the object into elemental atomic geometrical units or I-bodies which are in the shape of stock primitives or regularized intersections of stock primitives. These elemental atomic geometrical units are then represented in symbolic form. The symbolic representations of the elemental atomic geometrical units are then assembled heuristically to form a constructive solid geometry representation of the object usable for manufacturing thereof. Artificial intelligence is used to determine the best constructive solid geometry representation from the boundary representation of the object. Heuristic criteria are adapted to the manufacturing environment for which the device is to be utilized. The surface finish, tolerance, and other information associated with each surface of the boundary representation of the object are mapped onto the constructive solid geometry representation of the object to produce an enhanced solid geometry representation, particularly useful for computer-aided manufacture of the object.

Ar-Ar and I-Xe Ages of Caddo County and Thermal History of IAB Iron Meteorites

NASA Technical Reports Server (NTRS)

Bogard, Donald D.; Garrison, Daniel H.; Takeda, Hiroshi

2005-01-01

Inclusions in IAB iron meteorites include non-chondritic silicate and those with more primitive chondritic silicate composition. Coarse-grained gabbroic material rich in plagioclase and diopside occurs in the Caddo County IAB iron meteorite and represents a new type of chemically differentiated, extra-terrestrial, andesitic silicate. Other parts of Caddo contain mostly andesitic material. Caddo thus exhibits petrologic characteristics of parent body metamorphism of a chondrite-like parent and inhomogeneous segregation of melts. Proposed IAB formation models include parent body partial melting and fractional crystallization or incomplete differentiation due to internal heat sources, and impact/induced melting and mixing. Benedix et al. prefer a hybrid model whereby the IAB parent body largely melted, then underwent collisional breakup, partial mixing of phases, and reassembly. Most reported 129I- Xe-129 ages of IABs are greater than 4.56 Gyr and a few are greater than or = 4.567 Gyr. These oldest ages exceed the 4.567 Gyr Pb-Pb age of Ca, Al-rich inclusions in primitive meteorites,

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandra, Mani; Gammie, Charles F.; Foucart, Francois, E-mail: manic@illinois.edu, E-mail: gammie@illinois.edu, E-mail: fvfoucart@lbl.gov

Hot, diffuse, relativistic plasmas such as sub-Eddington black-hole accretion flows are expected to be collisionless, yet are commonly modeled as a fluid using ideal general relativistic magnetohydrodynamics (GRMHD). Dissipative effects such as heat conduction and viscosity can be important in a collisionless plasma and will potentially alter the dynamics and radiative properties of the flow from that in ideal fluid models; we refer to models that include these processes as Extended GRMHD. Here we describe a new conservative code, grim, that enables all of the above and additional physics to be efficiently incorporated. grim combines time evolution and primitive variablemore » inversion needed for conservative schemes into a single step using an algorithm that only requires the residuals of the governing equations as inputs. This algorithm enables the code to be physics agnostic as well as flexibility regarding time-stepping schemes. grim runs on CPUs, as well as on GPUs, using the same code. We formulate a performance model and use it to show that our implementation runs optimally on both architectures. grim correctly captures classical GRMHD test problems as well as a new suite of linear and nonlinear test problems with anisotropic conduction and viscosity in special and general relativity. As tests and example applications, we resolve the shock substructure due to the presence of dissipation, and report on relativistic versions of the magneto-thermal instability and heat flux driven buoyancy instability, which arise due to anisotropic heat conduction, and of the firehose instability, which occurs due to anisotropic pressure (i.e., viscosity). Finally, we show an example integration of an accretion flow around a Kerr black hole, using Extended GRMHD.« less

Origin of fatty acid synthesis - Thermodynamics and kinetics of reaction pathways

NASA Technical Reports Server (NTRS)

Weber, Arthur L.

1991-01-01

The primitiveness of contemporary fatty acid biosynthesis was evaluated by using the thermodynamics and kinetics of its component reactions to estimate the extent of its dependence on powerful and selective catalysis by enzymes. Since this analysis indicated that the modern pathway is not primitive because it requires sophisticated enzymatic catalysis, an alternative pathway of primitive fatty acid synthesis is proposed that uses glycolaldehyde as a substrate. In contrast to the modern pathway, this primitive pathway is not dependent on an exogenous source of phosphoanhydride energy. Furthermore, the chemical spontaneity of its reactions suggests that it could have been readily catalyzed by the rudimentary biocatalysts available at an early stage in the origin of life.

Physics of the primitive solar nebula and of giant gaseous protoplanets

NASA Technical Reports Server (NTRS)

Cameron, A. G. W.

1978-01-01

It has been proposed that the supernova responsible for injecting Al-26 into the early solar system was in fact responsible for triggering the collapse of an interstellar cloud in order to produce a system of stars, one of which would be the solar system. Details concerning the mechanism involved in such a process are discussed. Attention is given to the evolution of the primitive solar nebula, the instabilities in the primitive solar nebula, and the giant gaseous protoplanets. The principal conclusion to be drawn from the material presented is that the primitive solar nebula was a rather chaotic place, highly turbulent, with the multiple formation of giant gaseous protoplanets.

Possible complex organic compounds on Mars.

PubMed

Kobayashi, K; Sato, T; Kajishima, S; Kaneko, T; Ishikawa, Y; Saito, T

1997-01-01

It is suggested that primitive Mars had somehow similar environments as primitive Earth. If life was born on the primitive earth using organic compounds which were produced from the early Earth environment, the same types of organic compounds were also formed on primitive Mars. Such organic compounds might have been preserved on Mars still now. We are studying possible organic formation on primitive and present Mars. A gaseous mixture of CO2, CO, N2 and H2O with various mixing ratios were irradiated with high energy protons (major components of cosmic rays). Hydrogen cyanide and formaldehyde were detected among volatile products, and yellow-brown-colored water-soluble non-volatile substances were produced, which gave amino acids after acid-hydrolysis. Major part of "amino acid precursors" were not simple molecules like aminonitriles, but complex compounds which eluted earlier than free amino acids in cation-exchange HPLC. These organic compounds should be major targets in the future Mars mission. Strategy for the detection of the complex organics on Mars will be discussed.

Using Parallel Processing for Problem Solving.

DTIC Science & Technology

1979-12-01

are the basic parallel proces- sing primitive . Different goals of the system can be pursued in parallel by placing them in separate activities...Language primitives are provided for manipulating running activities. Viewpoints are a generalization of context FOM -(over "*’ DD I FON 1473 ’EDITION OF I...arc the basic parallel processing primitive . Different goals of the system can be pursued in parallel by placing them in separate activities. Language

Security Primitives for Reconfigurable Hardware-Based Systems

DTIC Science & Technology

2010-05-01

work, we propose security primitives using ideas centered around the notion of “moats and drawbridges .” The primitives encompass four design properties...Santa Bar- bara, CA 93106; email: sherwood@cs.ucsb.edu; R. Kastner, Department of Computer Science and Engineering , University of California, San...fingerprint reader), the other to control the ethernet IP core—and an AES encryption engine used by both of the processor cores. These cores are all implemented

A Generalized-Compliant-Motion Primitive

NASA Technical Reports Server (NTRS)

Backes, Paul G.

1993-01-01

Computer program bridges gap between planning and execution of compliant robotic motions developed and installed in control system of telerobot. Called "generalized-compliant-motion primitive," one of several task-execution-primitive computer programs, which receives commands from higher-level task-planning programs and executes commands by generating required trajectories and applying appropriate control laws. Program comprises four parts corresponding to nominal motion, compliant motion, ending motion, and monitoring. Written in C language.

Intrapartum synthetic oxytocin reduce the expression of primitive reflexes associated with breastfeeding.

PubMed

Marín Gabriel, Miguel A; Olza Fernández, Ibone; Malalana Martínez, Ana M; González Armengod, Carmen; Costarelli, Valeria; Millán Santos, Isabel; Fernández-Cañadas Morillo, Aurora; Pérez Riveiro, Pilar; López Sánchez, Francisco; García Murillo, Lourdes

2015-05-01

Several synthetic peptide manipulations during the time surrounding birth can alter the specific neurohormonal status in the newborn brain. This study is aimed at assessing whether intrapartum oxytocin administration has any effect on primitive neonatal reflexes and determining whether such an effect is dose-dependent. A cohort prospective study was conducted at a tertiary hospital. Mother-infant dyads who received intrapartum oxytocin (n=53) were compared with mother-infant dyads who did not receive intrapartum oxytocin (n=45). Primitive neonatal reflexes (endogenous, antigravity, motor, and rhythmic reflexes) were quantified by analyzing videotaped breastfeeding sessions in a biological nurturing position. Two observers blind to the group assignment and the oxytocin dose analyzed the videotapes and assesed the newborn's state of consciousness according to the Brazelton scale. The release of all rhythmic reflexes (p=0.01), the antigravity reflex (p=0.04), and total primitive neonatal reflexes (p=0.02) in the group exposed to oxytocin was lower than in the group not exposed to oxytocin. No correlations were observed between the dose of oxytocin administered and the percentage of primitive neonatal reflexes released (r=0.03; p=0.82). Intrapartum oxytocin administration might inhibit the expression of several primitive neonatal reflexes associated with breastfeeding. This correlation does not seem to be dose-dependent.

Isolation and characterisation of cancer stem cells from canine osteosarcoma.

PubMed

Wilson, H; Huelsmeyer, M; Chun, R; Young, K M; Friedrichs, K; Argyle, D J

2008-01-01

There is increasing evidence that cancer is a stem cell disease. This study sought to isolate and characterise cancer stem cells from canine osteosarcoma. One human and three canine cell lines were cultured in non-adherent culture conditions using serum-starved, semi-solid media. Primitive sarcosphere colonies from all cell lines were identified under these conditions and were characterised using molecular and cytochemical techniques for embryonic stem cell markers. Expression of the embryonic stem cell-associated genes Nanog, Oct4 and STAT3 indicated a primitive phenotype. Sarcospheres could be reproduced consistently when passaged multiple times and produced adherent cell cultures when returned to normal growth conditions. Similarities between human and canine osteosarcoma cell lines add credence to the potential of the dog as a model for human disease.

A theory of circular organization and negative feedback: defining life in a cybernetic context.

PubMed

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

A Theory of Circular Organization and Negative Feedback: Defining Life in a Cybernetic Context

NASA Astrophysics Data System (ADS)

Tsokolov, Sergey

2010-12-01

All life today incorporates a variety of systems controlled by negative feedback loops and sometimes amplified by positive feedback loops. The first forms of life necessarily also required primitive versions of feedback, yet surprisingly little emphasis has been given to the question of how feedback emerged out of primarily chemical systems. One chemical system has been established that spontaneously develops autocatalytic feedback, the Belousov-Zhabotinsky (BZ) reaction. In this essay, I discuss the BZ reaction as a possible model for similar reactions that could have occurred under prebiotic Earth conditions. The main point is that the metabolism of contemporary life evolved from primitive homeostatic networks regulated by negative feedback. Because life could not exist in their absence, feedback loops should be included in definitions of life.

Supermodeling by Synchronization of Alternative SPEEDO Models

NASA Astrophysics Data System (ADS)

Duane, Gregory; Selten, Frank

2016-04-01

The supermodeling approach, wherein different imperfect models of the same objective process are dynamically combined in run-time to reduce systematic error, is tested using SPEEDO - a primitive equation atmospheric model coupled to the CLIO ocean model. Three versions of SPEEDO are defined by parameters that differ in a range that arguably mimics differences among state-of-the-art climate models. A fourth model is taken to represent truth. The "true" ocean drives all three model atmospheres. The three models are also connected to one another at every level, with spatially uniform nudging coefficients that are trained so that the three models, which synchronize with one another, also synchronize with truth when data is continuously assimilated, as in weather prediction. The SPEEDO supermodel is evaluated in weather-prediction mode, with nudging to truth. It is found that the supemodel performs better than any of the three models and marginally better than the best weighted average of the outputs of the three models run separately. To evaluate the utility for climate projection, parameters corresponding to green house gas levels are changed in truth and in the three models. The supermodel formed with inter-model connections from the present-CO2 runs no longer give the optimal configuration for the supermodel in the doubled-CO2 realm, but the supermodel with the previously trained connections is still useful as compared to the separate models or averages of their outputs. In ongoing work, a training algorithm is examined that attempts to match the blocked-zonal index cycle of the SPEEDO model atmosphere to truth, rather than simply minimizing the RMS error in the various fields. Such an approach comes closer to matching the model attractor to the true attractor - the desired effect in climate projection - rather than matching instantaneous states. Gradient descent in a cost function defined over a finite temporal window can indeed be done efficiently. Preliminary results are presented for a crudely defined index cycle.

Shortest multiple disconnected path for the analysis of entanglements in two- and three-dimensional polymeric systems

NASA Astrophysics Data System (ADS)

Kröger, Martin

2005-06-01

We present an algorithm which returns a shortest path and related number of entanglements for a given configuration of a polymeric system in 2 or 3 dimensions. Rubinstein and Helfand, and later Everaers et al. introduced a concept to extract primitive paths for dense polymeric melts made of linear chains (a multiple disconnected multibead 'path'), where each primitive path is defined as a path connecting the (space-fixed) ends of a polymer under the constraint of non-interpenetration (excluded volume) between primitive paths of different chains, such that the multiple disconnected path fulfills a minimization criterion. The present algorithm uses geometrical operations and provides a—model independent—efficient approximate solution to this challenging problem. Primitive paths are treated as 'infinitely' thin (we further allow for finite thickness to model excluded volume), and tensionless lines rather than multibead chains, excluded volume is taken into account without a force law. The present implementation allows to construct a shortest multiple disconnected path (SP) for 2D systems (polymeric chain within spherical obstacles) and an optimal SP for 3D systems (collection of polymeric chains). The number of entanglements is then simply obtained from the SP as either the number of interior kinks, or from the average length of a line segment. Further, information about structure and potentially also the dynamics of entanglements is immediately available from the SP. We apply the method to study the 'concentration' dependence of the degree of entanglement in phantom chain systems. Program summaryTitle of program:Z Catalogue number:ADVG Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVG Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: Silicon Graphics (Irix), Sun (Solaris), PC (Linux) Operating systems or monitors under which the program has been tested: UNIX, Linux Program language used: USANSI Fortran 77 and Fortran 90 Memory required to execute with typical data: 1 MByte No. of lines in distributed program, including test data, etc.: 10 660 No. of bytes in distributed program, including test data, etc.: 119 551 Distribution formet:tar.gz Nature of physical problem: The problem is to obtain primitive paths substantiating a shortest multiple disconnected path (SP) for a given polymer configuration (chains of particles, with or without additional single particles as obstacles for the 2D case). Primitive paths are here defined as in [M. Rubinstein, E. Helfand, J. Chem. Phys. 82 (1985) 2477; R. Everaers, S.K. Sukumaran, G.S. Grest, C. Svaneborg, A. Sivasubramanian, K. Kremer, Science 303 (2004) 823] as the shortest line (path) respecting 'topological' constraints (from neighboring polymers or point obstacles) between ends of polymers. There is a unique solution for the 2D case. For the 3D case it is unique if we construct a primitive path of a single chain embedded within fixed line obstacles [J.S.B. Mitchell, Geometric shortest paths and network optimization, in: J.-R. Sack, J. Urrutia (Eds.), Handbook of Computational Geometry, Elsevier, Amsterdam, 2000, pp. 633-701]. For a large 3D configuration made of several chains, short is meant to be the Euclidean shortest multiple disconnected path (SP) where primitive paths are constructed for all chains simultaneously. While the latter problem, in general, does not possess a unique solution, the algorithm must return a locally optimal solution, robust against minor displacements of the disconnected path and chain re-labeling. The problem is solved if the number of kinks (or entanglements Z), explicitly deduced from the SP, is quite insensitive to the exact conformation of the SP which allows to estimate Z with a small error. Efficient method of solution: Primitive paths are constructed from the given polymer configuration (a non-shortest multiple disconnected path, including obstacles, if present) by first replacing each polymer contour by a line with a number of 'kinks' (beads, nodes) and 'segments' (edges). To obtain primitive paths, defined to be uncrossable by any other objects (neighboring primitive paths, line or point obstacles), the algorithm minimizes the length of all primitive paths consecutively, until a final minimum Euclidean length of the SP is reached. Fast geometric operations rather than dynamical methods are used to minimize the contour lengths of the primitive paths. Neighbor lists are used to keep track of potentially intersecting segments of other chains. Periodic boundary conditions are employed. A finite small line thickness is used in order to make sure that entanglements are not 'lost' due to finite precision of representation of numbers. Restrictions on the complexity of the problem: For a single chain embedded within fixed line or point obstacles, the algorithm returns the exact SP. For more complex problems, the algorithm returns a locally optimal SP. Except for exotic, probably rare, configurations it turns out that different locally optimal SPs possess quite an identical number of nodes. In general, the problem constructing the SP is known to be NP-hard [J.S.B. Mitchell, Geometric shortest paths and network optimization, in: J.-R. Sack, J. Urrutia (Eds.), Handbook of Computational Geometry, Elsevier, Amsterdam, 2000, pp. 633-701], and we offer a solution which should suffice to analyze physical problems, and gives an estimate about the precision and uniqueness of the result (from a standard deviation by varying the parameter: cyclicswitch). The program is NOT restricted to handle systems for which segment lengths of the SP exceed half the box size. Typical running time: Typical running times are approximately two orders of magnitude shorter compared with the ones needed for a corresponding molecular dynamics approach, and scale mostly linearly with system size. We provide a benchmark table.

Ginzburg criterion for ionic fluids: the effect of Coulomb interactions.

PubMed

Patsahan, O

2013-08-01

The effect of the Coulomb interactions on the crossover between mean-field and Ising critical behavior in ionic fluids is studied using the Ginzburg criterion. We consider the charge-asymmetric primitive model supplemented by short-range attractive interactions in the vicinity of the gas-liquid critical point. The model without Coulomb interactions exhibiting typical Ising critical behavior is used to calibrate the Ginzburg temperature of the systems comprising electrostatic interactions. Using the collective variables method, we derive a microscopic-based effective Hamiltonian for the full model. We obtain explicit expressions for all the relevant Hamiltonian coefficients within the framework of the same approximation, i.e., the one-loop approximation. Then we consistently calculate the reduced Ginzburg temperature t(G) for both the purely Coulombic model (a restricted primitive model) and the purely nonionic model (a hard-sphere square-well model) as well as for the model parameters ranging between these two limiting cases. Contrary to the previous theoretical estimates, we obtain the reduced Ginzburg temperature for the purely Coulombic model to be about 20 times smaller than for the nonionic model. For the full model including both short-range and long-range interactions, we show that t(G) approaches the value found for the purely Coulombic model when the strength of the Coulomb interactions becomes sufficiently large. Our results suggest a key role of Coulomb interactions in the crossover behavior observed experimentally in ionic fluids as well as confirm the Ising-like criticality in the Coulomb-dominated ionic systems.

Empirical equations to predict the sulfur content of mafic magmas at sulfide saturation and applications to magmatic sulfide deposits

NASA Astrophysics Data System (ADS)

Li, Chusi; Ripley, Edward M.

2005-03-01

Empirical equations to predict the sulfur content of a mafic magma at the time of sulfide saturation have been developed based on several sets of published experimental data. The S content at sulfide saturation (SCSS) can be expressed as: ln X_{text S} = 1.229 - 0.74(10^4/T) - 0.021(P) - 0.311 ln X_{{text{FeO}}} - 6.166X_{{text{SiO}}_{text{2}}} - 9.153X_{{text{Na}}_{text{2}} {text{O + K}}_{text{2}} {text{O}}} - 1.914X_{{text{MgO}}} + 6.594X_{{text{FeO}}} where T is in degrees Kelvin, X is mole fraction and P is in kbar. The squared multiple correlation coefficient ( r 2) for the equation is 0.88. Application of the equation to data from sulfide-saturated mid-ocean ridge basalts (MORB) samples show that the SCSS is closely predicted for primitive MORBs, but that accuracy decreases for lower T (<1,130°C) and more evolved MORB samples. This suggests that because the calibrations are based on anhydrous experimental runs done at temperatures of 1,200°C and above, it is not possible to extrapolate them to significantly lower temperatures and hydrous conditions. Because the SCSS of a primitive MORB magma increases with decreasing P, sulfide saturation in MORB appears to be a function of the degree of en route assimilation of S from country rocks as well as the degree of fractional crystallization in shallow staging chambers. Application of the equation to the high- T impact melt sheet that produced the Sudbury Igneous Complex and associated Ni-Cu sulfide ores indicates that sulfide-saturation was reached at 1,500°C, well above the start of orthopyroxene crystallization at 1,190°C. This would permit ample time for the gravitational settling and collection of immiscible sulfide liquid that produced the high-grade ore bodies. The development of a platinum group element (PGE)-enriched layer in the Sonju Lake Intrusion of the Duluth Complex is thought to be due to the attainment of sulfide saturation in the magma after a period of fractional crystallization. Using the composition of the parent magma of the Sonju Lake Intrusion the presented equation indicates that sulfide saturation would have been reached at 60% crystallization, when iron oxide was a liquidus mineral; the prediction is in agreement with field evidence which indicates that PGE-enrichment occurs in the oxide-rich gabbro zone. Contamination and mixing processes that may be related to the attainment of sulfide saturation in mafic magmas can also be evaluated. Mixing of a siliceous melt and a liquid of olivine tholeiite composition, similar to that thought to be a reasonable parental composition for many Duluth Complex intrusions, can induce sulfide saturation at mixing ratios in excess of 0.1. If the contaminant contains low quantities of sulfur the mixing ratio required to promote saturation is reduced. Mixing of mafic magmas at various stages of fractionation is evaluated using magma compositions that are thought to be appropriate for the generation of the Merensky Reef in the Bushveld Complex. Magma mixing is shown to be an effective process for the attainment of sulfide saturation, depending strongly on the sulfur concentrations of the end-member magmas.

An In-Situ Study of REE Abundances in Three Anorthositic Impact Melt Lunar Highland Meteorites

NASA Astrophysics Data System (ADS)

Consolmagno, G. J.; Russell, S. S.; Jeffries, T. E.

2004-03-01

REE measurements of the lunar highland meteorites DAG 400, Dhofar 081, and NWA 482, and models of the REE in melts in equilibrium with them, suggest that they may contain components more primitive than those found in Apollo FAN samples.

Monaural Speech Segregation by Integrating Primitive and Schema-Based Analysis

DTIC Science & Technology

2008-02-03

vol. 19, pp. 475-492. Wang D.L. and Chang P.S. (2008): An oscillatory correlation model of auditory streaming. Cognitive Neurodynamics , vol. 2, pp...Subcontracts DeLiang Wang (Principal Investigator) March 2008 Department of Computer Science & Engineering and Center for Cognitive Science The

Strontium and neodymium isotopic evidence for the heterogeneous nature and development of the mantle beneath Afar (Ethiopia)

NASA Astrophysics Data System (ADS)

Betton, P. J.; Civetta, L.

1984-11-01

Neodymium isotope and REE analyses of recent volcanic rocks and spinel lherzolite nodules from the Afar area are reported. The 143Nd/ 144Nd ratios of the volcanic rocks range from 0.51286 to 0.51304, similar to the range recorded from Iceland. However, the 87Sr/ 86Sr ratios display a distinctly greater range (0.70328-0.70410) than those reported from the primitive rocks of Iceland. Whole rock samples and mineral separates from the spinel lherzolite nodules exhibit uniform 143Nd/ 144Nd ratios (ca. 0.5129) but varied 87Sr/ 86Sr ratios in the range 0.70427-0.70528. The Sr sbnd Nd isotope variations suggest that the volcanic rocks may have been produced by mixing between two reservoirs with distinct isotopic compositions. Two possible magma reservoirs in this area are the source which produced the "MORB-type" volcanics in the Red Sea and Gulf of Aden and the anomalous source represented by the nodule suite. The isotopic composition of the volcanics is compatible with mixing between these two reservoirs. It is shown that the anomalous source with a high 87Sr/ 86Sr ratio cannot have been produced by simple processes of partial melting and mixing within normal mantle. Instead the high 87Sr/ 86Sr is equated with a fluid phase. A primitive cognate fluid, subducted seawater or altered oceanic lithosphere may have been responsible for the generation of the source with a high 87Sr/ 86Sr ratio.

Cave men: stone tools, Victorian science, and the 'primitive mind' of deep time.

PubMed

Pettitt, Paul B; White, Mark J

2011-03-20

Palaeoanthropology, the study of the evolution of humanity, arose in the nineteenth century. Excavations in Europe uncovered a series of archaeological sediments which provided proof that the antiquity of human life on Earth was far longer than the biblical six thousand years, and by the 1880s authors had constructed a basic paradigm of what 'primitive' human life was like. Here we examine the development of Victorian palaeoanthropology for what it reveals of the development of notions of cognitive evolution. It seems that Victorian specialists rarely addressed cognitive evolution explicitly, although several assumptions were generally made that arose from preconceptions derived from contemporary 'primitive' peoples. We identify three main phases of development of notions of the primitive mind in the period.

Primitive neuroectodermal tumor of the cervix: a case report

PubMed Central

2011-01-01

Introduction Peripheral primitive neuroectodermal tumor of the cervix uteri is extremely rare. Between 1987 and 2010, there were only nine cases reported in the English literature, with considerably different management policies. Case presentation A 45-year-old Iranian woman presented to our facility with a primitive neuroectodermal tumor of the cervix uteri. Her clinical stage IB2 tumor was treated successfully with chemotherapy. Our patient underwent radical hysterectomy. There was no trace of the tumor after four years of follow-up. Conclusions According to current knowledge, primitive neuroectodermal tumors belong to the Ewing's sarcoma family, and the improvement of treatment outcome in our patient was due to dose-intensive neoadjuvant chemotherapy, surgery and consolidation chemotherapy in accordance with the protocol for bony Ewing's sarcoma. PMID:21962148

Insights to primitive replication derived from structures of small oligonucleotides

NASA Technical Reports Server (NTRS)

Smith, G. K.; Fox, G. E.

1995-01-01

Available information on the structure of small oligonucleotides is surveyed. It is observed that even small oligomers typically exhibit defined structures over a wide range of pH and temperature. These structures rely on a plethora of non-standard base-base interactions in addition to the traditional Watson-Crick pairings. Stable duplexes, though typically antiparallel, can be parallel or staggered and perfect complementarity is not essential. These results imply that primitive template directed reactions do not require high fidelity. Hence, the extensive use of Watson-Crick complementarity in genes rather than being a direct consequence of the primitive condensation process, may instead reflect subsequent selection based on the advantage of accuracy in maintaining the primitive genetic machinery once it arose.

Generalizing on Multiple Grounds: Performance Learning in Model-Based Troubleshooting

DTIC Science & Technology

1989-02-01

Aritificial Intelligence , 24, 1984. [Ble88] Guy E. Blelloch. Scan Primitives and Parallel Vector Models. PhD thesis, Artificial Intelligence Laboratory...Diagnostic reasoning based on strcture and behavior. Aritificial Intelligence , 24, 1984. [dK86] J. de Kleer. An assumption-based truth maintenance system...diagnosis. Aritificial Intelligence , 24. �. )3 94 BIBLIOGRAPHY [Ham87] Kristian J. Hammond. Learning to anticipate and avoid planning prob- lems