NASA Technical Reports Server (NTRS)
Boldman, D. R.; Schmidt, J. F.; Ehlers, R. C.
1972-01-01
An empirical modification of an existing integral energy turbulent boundary layer method is proposed in order to improve the estimates of local heat transfer in converging-diverging nozzles and consequently, provide better assessments of the total or integrated heat transfer. The method involves the use of a modified momentum-heat analogy which includes an acceleration term comprising the nozzle geometry and free stream velocity. The original and modified theories are applied to heat transfer data from previous studies which used heated air in 30 deg - 15 deg, 45 deg - 15 deg, and 60 deg - 15 deg water-cooled nozzles.
NASA Astrophysics Data System (ADS)
Rad, Jamal Amani; Parand, Kourosh; Abbasbandy, Saeid
2015-05-01
For the first time in mathematical finance field, we propose the local weak form meshless methods for option pricing; especially in this paper we select and analysis two schemes of them named local boundary integral equation method (LBIE) based on moving least squares approximation (MLS) and local radial point interpolation (LRPI) based on Wu's compactly supported radial basis functions (WCS-RBFs). LBIE and LRPI schemes are the truly meshless methods, because, a traditional non-overlapping, continuous mesh is not required, either for the construction of the shape functions, or for the integration of the local sub-domains. In this work, the American option which is a free boundary problem, is reduced to a problem with fixed boundary using a Richardson extrapolation technique. Then the θ -weighted scheme is employed for the time derivative. Stability analysis of the methods is analyzed and performed by the matrix method. In fact, based on an analysis carried out in the present paper, the methods are unconditionally stable for implicit Euler (θ = 0) and Crank-Nicolson (θ = 0.5) schemes. It should be noted that LBIE and LRPI schemes lead to banded and sparse system matrices. Therefore, we use a powerful iterative algorithm named the Bi-conjugate gradient stabilized method (BCGSTAB) to get rid of this system. Numerical experiments are presented showing that the LBIE and LRPI approaches are extremely accurate and fast.
Boundary Preserving Dense Local Regions.
Kim, Jaechul; Grauman, Kristen
2015-05-01
We propose a dense local region detector to extract features suitable for image matching and object recognition tasks. Whereas traditional local interest operators rely on repeatable structures that often cross object boundaries (e.g., corners, scale-space blobs), our sampling strategy is driven by segmentation, and thus preserves object boundaries and shape. At the same time, whereas existing region-based representations are sensitive to segmentation parameters and object deformations, our novel approach to robustly sample dense sites and determine their connectivity offers better repeatability. In extensive experiments, we find that the proposed region detector provides significantly better repeatability and localization accuracy for object matching compared to an array of existing feature detectors. In addition, we show our regions lead to excellent results on two benchmark tasks that require good feature matching: weakly supervised foreground discovery and nearest neighbor-based object recognition. PMID:26353319
On Local Boundary CFT and Non-Local CFT on the Boundary
NASA Astrophysics Data System (ADS)
Rehren, Karl-Henning
The holographic relation between local boundary conformal quantum field theories (BCFT) and their non-local boundary restrictions is reviewed, and non-vacuum BCFT's, whose existence was conjectured previously, are constructed. (Based on joint work [18] with R. Longo.)
Nonequilibrium chemistry boundary layer integral matrix procedure
NASA Technical Reports Server (NTRS)
Tong, H.; Buckingham, A. C.; Morse, H. L.
1973-01-01
The development of an analytic procedure for the calculation of nonequilibrium boundary layer flows over surfaces of arbitrary catalycities is described. An existing equilibrium boundary layer integral matrix code was extended to include nonequilibrium chemistry while retaining all of the general boundary condition features built into the original code. For particular application to the pitch-plane of shuttle type vehicles, an approximate procedure was developed to estimate the nonequilibrium and nonisentropic state at the edge of the boundary layer.
Boundary-integral simulations of containerless solidification
NASA Astrophysics Data System (ADS)
Ajaev, Vladimir S.; Davis, Stephen H.
2003-05-01
We carry out boundary-integral simulations of a two-dimensional liquid droplet surrounded by air and solidified from a cool point on the boundary. There are three interfaces in the problem: solid-liquid, air-liquid, and air-solid. All three evolve in time in such a way that certain tri-junction conditions must be satisfied. Our numerical method describes the quasi-steady evolution of the interfaces in the limit of zero surface energy on the solidification front. A new iterative technique is developed to describe the interface evolution when mass and total energy are conserved and the local tri-junction conditions are satisfied at every instant in time. A method is also developed for efficient numerical integration over the interfaces by taking advantage of analytical formulas for Green's functions. We start the simulations by studying the case of equal densities of the solid and liquid. This allows us to verify the numerical method and obtain some estimates of the speed of the solidification front. Solid-liquid interface flattening is observed at the intermediate stages of solidification. When the densities of the two phases are different, elongated solidified particles are observed when the solid density is smaller than the liquid density. At the final stages of solidification, a corner is formed in agreement with observations in related experiments.
NASA Astrophysics Data System (ADS)
Honda, M.; Satake, S.; Suzuki, Y.; Yoshida, M.; Hayashi, N.; Kamiya, K.; Matsuyama, A.; Shinohara, K.; Matsunaga, G.; Nakata, M.; Ide, S.; Urano, H.
2015-07-01
The integrated simulation framework for toroidal momentum transport is developed, which self-consistently calculates the neoclassical toroidal viscosity (NTV), the radial electric field {{E}r} and the resultant toroidal rotation {{V}φ} together with the scrape-off-layer (SOL) physics-based boundary model. The coupling of three codes, the 1.5D transport code TOPICS, the three-dimensional (3D) equilibrium code VMEC and the 3D δ f drift-kinetic equation solver FORTEC-3D, makes it possible to calculate the NTV due to the non-axisymmetric perturbed magnetic field caused by toroidal field coils. Analyses reveal that the NTV significantly influences {{V}φ} in JT-60U and {{E}r} holds the key to determine the NTV profile. The sensitivity of the {{V}φ} profile to the boundary rotation necessitates a boundary condition modelling for toroidal momentum. Owing to the high-resolution measurement system in JT-60U, the {{E}r} gradient is found to be virtually zero at the separatrix regardless of toroidal rotation velocities. Focusing on {{E}r} , the boundary model of toroidal momentum is developed in conjunction with the SOL/divertor plasma code D5PM. This modelling realizes self-consistent predictive simulations for operation scenario development in ITER.
Anchored boundary conditions for locally isostatic networks
NASA Astrophysics Data System (ADS)
Theran, Louis; Nixon, Anthony; Ross, Elissa; Sadjadi, Mahdi; Servatius, Brigitte; Thorpe, M. F.
2015-11-01
Finite pieces of locally isostatic networks have a large number of floppy modes because of missing constraints at the surface. Here we show that by imposing suitable boundary conditions at the surface the network can be rendered effectively isostatic. We refer to these as anchored boundary conditions. An important example is formed by a two-dimensional network of corner sharing triangles, which is the focus of this paper. Another way of rendering such networks isostatic is by adding an external wire along which all unpinned vertices can slide (sliding boundary conditions). This approach also allows for the incorporation of boundaries associated with internal holes and complex sample geometries, which are illustrated with examples. The recent synthesis of bilayers of vitreous silica has provided impetus for this work. Experimental results from the imaging of finite pieces at the atomic level need such boundary conditions, if the observed structure is to be computer refined so that the interior atoms have the perception of being in an infinite isostatic environment.
Integrated Laboratories: Crossing Traditional Boundaries
ERIC Educational Resources Information Center
Dillner, Debra K.; Ferrante, Robert F.; Fitzgerald, Jeffrey P.; Heuer, William B.; Schroeder, Maria J.
2007-01-01
A new, integrated laboratory curriculum was recently developed at the U.S. Naval Academy in response to the 1999 ACS Committee on Professional Training guidelines that required inclusion of biochemistry and a stronger emphasis on student research. To meet these ACS requirements and to introduce more student choice in the major, we embarked on a…
Integrable open boundary conditions for XXC models
NASA Astrophysics Data System (ADS)
Arnaudon, Daniel; Maassarani, Ziad
1998-10-01
The XXC models are multistate generalizations of the well known spin-½ XXZ model. These integrable models share a common underlying su(2) structure. We derive integrable open boundary conditions for the hierarchy of conserved quantities of the XXC models . Due to lack of crossing unitarity of the R-matrix, we develop specific methods to prove integrability. The symmetry of the spectrum is determined.
Integrated watershed planning across jurisdictional boundaries
NASA Astrophysics Data System (ADS)
Watts, A. W.; Roseen, R.; Stacey, P.; Bourdeau, R.
2014-12-01
We will present the foundation for an Coastal Watershed Integrated Plan for three communities in southern New Hampshire. Small communities are often challenged by complex regulatory requirements and limited resources, but are wary of perceived risks in engaging in collaborative projects with other communities. Potential concerns include loss of control, lack of resources to engage in collaboration, technical complexity, and unclear benefits. This project explores a multi-town subwatershed application of integrated planning across jurisdictional boundaries that addresses some of today's highest priority water quality issues: wastewater treatment plant upgrades for nutrient removal; green infrastructure stormwater management for developing and re-developing areas; and regional monitoring of ecosystem indicators in support of adaptive management to achieve nutrient reduction and other water quality goals in local and downstream waters. The project outcome is a collaboratively-developed inter-municipal integrated plan, and a monitoring framework to support cross jurisdictional planning and assess attainment of water quality management goals. This research project has several primary components: 1) assessment of initial conditions, including both the pollutant load inputs and the political, economic and regulatory status within each community, 2) a pollutant load model for point and non-point sources, 3) multi-criteria evaluation of load reduction alternatives 4) a watershed management plan optimized for each community, and for Subwatersheds combining multiple communities. The final plan will quantify the financial and other benefits/drawbacks to each community for both inter municipal and individual pollution control approaches. We will discuss both the technical and collaborative aspects of the work, with lessons learned regarding science to action, incorporation of social, economic and water quality assessment parameters, and stakeholder/researcher interaction.
Bulk locality and boundary creating operators
NASA Astrophysics Data System (ADS)
Nakayama, Yu; Ooguri, Hirosi
2015-10-01
We formulate a minimum requirement for CFT operators to be localized in the dual AdS. In any spacetime dimensions, we show that a general solution to the requirement is a linear superposition of operators creating spherical boundaries in CFT, with the dilatation by the imaginary unit from their centers. This generalizes the recent proposal by Miyaji et al. for bulk local operators in the three dimensional AdS. We show that Ishibashi states for the global conformal symmetry in any dimensions and with the imaginary di-latation obey free field equations in AdS and that incorporating bulk interactions require their superpositions. We also comment on the recent proposals by Kabat et al., and by H. Verlinde.
Boundary Lax pairs from non-ultra-local Poisson algebras
Avan, Jean; Doikou, Anastasia
2009-11-15
We consider non-ultra-local linear Poisson algebras on a continuous line. Suitable combinations of representations of these algebras yield representations of novel generalized linear Poisson algebras or 'boundary' extensions. They are parametrized by a boundary scalar matrix and depend, in addition, on the choice of an antiautomorphism. The new algebras are the classical-linear counterparts of the known quadratic quantum boundary algebras. For any choice of parameters, the non-ultra-local contribution of the original Poisson algebra disappears. We also systematically construct the associated classical Lax pair. The classical boundary principal chiral model is examined as a physical example.
Boundary-Layer Receptivity and Integrated Transition Prediction
NASA Technical Reports Server (NTRS)
Chang, Chau-Lyan; Choudhari, Meelan
2005-01-01
The adjoint parabold stability equations (PSE) formulation is used to calculate the boundary layer receptivity to localized surface roughness and suction for compressible boundary layers. Receptivity efficiency functions predicted by the adjoint PSE approach agree well with results based on other nonparallel methods including linearized Navier-Stokes equations for both Tollmien-Schlichting waves and crossflow instability in swept wing boundary layers. The receptivity efficiency function can be regarded as the Green's function to the disturbance amplitude evolution in a nonparallel (growing) boundary layer. Given the Fourier transformed geometry factor distribution along the chordwise direction, the linear disturbance amplitude evolution for a finite size, distributed nonuniformity can be computed by evaluating the integral effects of both disturbance generation and linear amplification. The synergistic approach via the linear adjoint PSE for receptivity and nonlinear PSE for disturbance evolution downstream of the leading edge forms the basis for an integrated transition prediction tool. Eventually, such physics-based, high fidelity prediction methods could simulate the transition process from the disturbance generation through the nonlinear breakdown in a holistic manner.
NASA Astrophysics Data System (ADS)
Xie, Guizhong; Zhang, Dehai; Zhang, Jianming; Meng, Fannian; Du, Wenliao; Wen, Xiaoyu
2016-07-01
As a widely used numerical method, boundary element method (BEM) is efficient for computer aided engineering (CAE). However, boundary integrals with near singularity need to be calculated accurately and efficiently to implement BEM for CAE analysis on thin bodies successfully. In this paper, the distance in the denominator of the fundamental solution is first designed as an equivalent form using approximate expansion and the original sinh method can be revised into a new form considering the minimum distance and the approximate expansion. Second, the acquisition of the projection point by Newton-Raphson method is introduced. We acquire the nearest point between the source point and element edge by solving a cubic equation if the location of the projection point is outside the element, where boundary integrals with near singularity appear. Finally, the subtriangles of the local coordinate space are mapped into the integration space and the sinh method is applied in the integration space. The revised sinh method can be directly performed in the integration element. Averification test of our method is proposed. Results demonstrate that our method is effective for regularizing the boundary integrals with near singularity.
Integrability of a deterministic cellular automaton driven by stochastic boundaries
NASA Astrophysics Data System (ADS)
Prosen, Tomaž; Mejía-Monasterio, Carlos
2016-05-01
We propose an interacting many-body space–time-discrete Markov chain model, which is composed of an integrable deterministic and reversible cellular automaton (rule 54 of Bobenko et al 1993 Commun. Math. Phys. 158 127) on a finite one-dimensional lattice {({{{Z}}}2)}× n, and local stochastic Markov chains at the two lattice boundaries which provide chemical baths for absorbing or emitting the solitons. Ergodicity and mixing of this many-body Markov chain is proven for generic values of bath parameters, implying the existence of a unique nonequilibrium steady state. The latter is constructed exactly and explicitly in terms of a particularly simple form of matrix product ansatz which is termed a patch ansatz. This gives rise to an explicit computation of observables and k-point correlations in the steady state as well as the construction of a nontrivial set of local conservation laws. The feasibility of an exact solution for the full spectrum and eigenvectors (decay modes) of the Markov matrix is suggested as well. We conjecture that our ideas can pave the road towards a theory of integrability of boundary driven classical deterministic lattice systems.
40 CFR 255.21 - Local consultation on boundaries.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Local consultation on boundaries. 255.21 Section 255.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES IDENTIFICATION OF REGIONS AND AGENCIES FOR SOLID WASTE MANAGEMENT Procedures for Identifying Regions and Agencies § 255.21 Local consultation...
Computing the Casimir force using regularized boundary integral equations
NASA Astrophysics Data System (ADS)
Kilen, Isak; Jakobsen, Per Kristen
2014-11-01
In this paper we use a novel regularization procedure to reduce the calculation of the Casimir force for 2D scalar fields between compact objects to the solution of a classical integral equation defined on the boundaries of the objects. The scalar fields are subject to Dirichlet boundary conditions on the object boundaries. We test the integral equation by comparing with what we get for parallel plates, concentric circles and adjacent circles using mode summation and the functional integral method. We show how symmetries in the shapes and configuration of boundaries can easily be incorporated into our method and that it leads to fast evaluation of the Casimir force for symmetric situations.
Boundary-integral methods in elasticity and plasticity. [solutions of boundary value problems
NASA Technical Reports Server (NTRS)
Mendelson, A.
1973-01-01
Recently developed methods that use boundary-integral equations applied to elastic and elastoplastic boundary value problems are reviewed. Direct, indirect, and semidirect methods using potential functions, stress functions, and displacement functions are described. Examples of the use of these methods for torsion problems, plane problems, and three-dimensional problems are given. It is concluded that the boundary-integral methods represent a powerful tool for the solution of elastic and elastoplastic problems.
Solution of elastoplastic torsion problem by boundary integral method
NASA Technical Reports Server (NTRS)
Mendelson, A.
1975-01-01
The boundary integral method was applied to the elastoplastic analysis of the torsion of prismatic bars, and the results are compared with those obtained by the finite difference method. Although fewer unknowns were used, very good accuracy was obtained with the boundary integral method. Both simply and multiply connected bodies can be handled with equal ease.
Instability of a Supersonic Boundary-Layer with Localized Roughness
NASA Technical Reports Server (NTRS)
Marxen, Olaf; Iaccarino, Gianluca; Shaqfeh, Eric S. G.
2010-01-01
A localized 3-D roughness causes boundary-layer separation and (weak) shocks. Most importantly, streamwise vortices occur which induce streamwise (low U, high T) streaks. Immersed boundary method (volume force) suitable to represent roughness element in DNS. Favorable comparison between bi-global stability theory and DNS for a "y-mode" Outlook: Understand the flow physics (investigate "z-modes" in DNS through sinuous spanwise forcing, study origin of the beat in DNS).
Local and social facets of planetary boundaries: right to nutrients
NASA Astrophysics Data System (ADS)
Kahiluoto, Helena; Kuisma, Miia; Kuokkanen, Anna; Mikkilä, Mirja; Linnanen, Lassi
2015-10-01
Anthropogenic nutrient flows exceed the planetary boundaries. The boundaries and the current excesses vary spatially. Such variations have both an ecological and a social facet. We explored the spatial variation using a bottom-up approach. The local critical boundaries were determined through the current or accumulated flow of the preceding five years before the planetary boundary criteria were met. Finland and Ethiopia served as cases with contrasting ecology and wealth. The variation in excess depends on historical global inequities in the access to nutrients. Globally, the accumulated use per capita is 2300 kg reactive nitrogen (Nr) and 200 kg phosphorus (P). For Finland, the accumulated use per capita is 3400 kg Nr and 690 kg P, whereas for Ethiopia, it is 26 kg Nr and 12 kg P. The critical N boundary in Finland is currently exceeded by 40 kg cap-1 a-1 and the accumulated excess is 65 kg cap-1 a-1, while the global current excess is 24 kg cap-1 a-1 and there is space in Ethiopia to increase even the accumulated flow. The critical P boundary is exceeded in Finland and (although less so) in Ethiopia, but for contrary reasons: (1) the excessive past inflow to the agrifood system in Finland and (2) the excessive outflow from the agrifood system triggered by deficits in inflow and waste management in Ethiopia. The critical boundaries set by Finnish marine systems are lower and those set by freshwaters are higher than the planetary boundaries downscaled per capita. The shift to dominance of internal loading in watercourses represents a tipping point. We conclude that food security within the safe boundaries requires global redistribution of nutrients in residues, soils and sediments and of rights to use nutrients. Bottom-up assessments reveal local dynamics that shed new light on the relevant boundary criteria and on estimates and remedies.
Integrable Boundary for Quad-Graph Systems: Three-Dimensional Boundary Consistency
NASA Astrophysics Data System (ADS)
Caudrelier, Vincent; Crampé, Nicolas; Zhang, Qi Cheng
2014-02-01
We propose the notion of integrable boundary in the context of discrete integrable systems on quad-graphs. The equation characterizing the boundary must satisfy a compatibility equation with the one characterizing the bulk that we called the three-dimensional (3D) boundary consistency. In comparison to the usual 3D consistency condition which is linked to a cube, our 3D boundary consistency condition lives on a half of a rhombic dodecahedron. The We provide a list of integrable boundaries associated to each quad-graph equation of the classification obtained by Adler, Bobenko and Suris. Then, the use of the term ''integrable boundary'' is justified by the facts that there are Bäcklund transformations and a zero curvature representation for systems with boundary satisfying our condition. We discuss the three-leg form of boundary equations, obtain associated discrete Toda-type models with boundary and recover previous results as particular cases. Finally, the connection between the 3D boundary consistency and the set-theoretical reflection equation is established.
Treatment of domain integrals in boundary element methods
Nintcheu Fata, Sylvain
2012-01-01
A systematic and rigorous technique to calculate domain integrals without a volume-fitted mesh has been developed and validated in the context of a boundary element approximation. In the proposed approach, a domain integral involving a continuous or weakly-singular integrand is first converted into a surface integral by means of straight-path integrals that intersect the underlying domain. Then, the resulting surface integral is carried out either via analytic integration over boundary elements or by use of standard quadrature rules. This domain-to-boundary integral transformation is derived from an extension of the fundamental theorem of calculus to higher dimension, and the divergence theorem. In establishing the method, it is shown that the higher-dimensional version of the first fundamental theorem of calculus corresponds to the well-known Poincare lemma. The proposed technique can be employed to evaluate integrals defined over simply- or multiply-connected domains with Lipschitz boundaries which are embedded in an Euclidean space of arbitrary but finite dimension. Combined with the singular treatment of surface integrals that is widely available in the literature, this approach can also be utilized to effectively deal with boundary-value problems involving non-homogeneous source terms by way of a collocation or a Galerkin boundary integral equation method using only the prescribed surface discretization. Sample problems associated with the three-dimensional Poisson equation and featuring the Newton potential are successfully solved by a constant element collocation method to validate this study.
Integrated foreground segmentation and boundary matting for live videos.
Minglun Gong; Yiming Qian; Li Cheng
2015-04-01
The objective of foreground segmentation is to extract the desired foreground object from input videos. Over the years, there have been significant amount of efforts on this topic. Nevertheless, there still lacks a simple yet effective algorithm that can process live videos of objects with fuzzy boundaries (e.g., hair) captured by freely moving cameras. This paper presents an algorithm toward this goal. The key idea is to train and maintain two competing one-class support vector machines at each pixel location, which model local color distributions for both foreground and background, respectively. The usage of two competing local classifiers, as we have advocated, provides higher discriminative power while allowing better handling of ambiguities. By exploiting this proposed machine learning technique, and by addressing both foreground segmentation and boundary matting problems in an integrated manner, our algorithm is shown to be particularly competent at processing a wide range of videos with complex backgrounds from freely moving cameras. This is usually achieved with minimum user interactions. Furthermore, by introducing novel acceleration techniques and by exploiting the parallel structure of the algorithm, near real-time processing speed (14 frames/s without matting and 8 frames/s with matting on a midrange PC & GPU) is achieved for VGA-sized videos. PMID:25675459
Boundary Integral Solutions to Three-Dimensional Unconfined Darcy's Flow
NASA Astrophysics Data System (ADS)
Lennon, Gerard P.; Liu, Philip L.-F.; Liggett, James A.
1980-08-01
The boundary integral equation method (BIEM) is used to solve three-dimensional potential flow problems in porous media. The problems considered here are time dependent and have a nonlinear boundary condition on the free surface. The entire boundary, including the moving free surface, discretized into linear finite elements for the purpose of evaluating the boundary integrals. The technique allows transient, three-dimensional problems to be solved with reasonable computational costs. Numerical examples include recharge through rectangular and circular areas and seepage flow from a surface pond. The examples are used to illustrate the method and show the nonlinear effects.
Magnetization due to localized states on graphene grain boundary
Dutta, Sudipta; Wakabayashi, Katsunori
2015-01-01
Magnetism in graphene has been found to originate from various defects, e.g., vacancy, edge formation, add-atoms etc. Here, we discuss about an alternate route of achieving magnetism in graphene via grain boundary. During chemical vapor deposition of graphene, several graphene nucleation centers grow independently and face themselves with unusual bonding environment, giving rise to the formation of grain boundaries. We investigate the origin of magnetism in such grain boundaries within first-principles calculations, by letting two nucleation centers interact with each other at their interface. We observe formation of unprecedented point defect, consisting of fused three-membered and larger carbon rings, which induces net magnetization to graphene quantum dots. In case of periodic lattices, the appearance of array of point defects leads to the formation of magnetic grain boundaries. The net magnetization on these defects arises due to the deviation from bipartite characteristics of pristine graphene. We observe magnetic grain boundary induced dispersion less flat bands near Fermi energy, showing higher localization of electrons. These flat bands can be accessed via small doping, leading to enhanced magnetism. Moreover, the grain boundaries can induce asymmetric spin conduction behavior along the cross boundary direction. These properties can be exploited for sensor and spin-filtering applications. PMID:26145161
Localized travelling waves in the asymptotic suction boundary layer
NASA Astrophysics Data System (ADS)
Kreilos, Tobias; Gibson, John F.; Schneider, Tobias M.
2016-05-01
We present two spanwise-localized travelling wave solutions in the asymptotic suction boundary layer, obtained by continuation of solutions of plane Couette flow. One of the solutions has the vortical structures located close to the wall, similar to spanwise-localized edge states previously found for this system. The vortical structures of the second solution are located in the free stream far above the laminar boundary layer and are supported by a secondary shear gradient that is created by a large-scale low-speed streak. The dynamically relevant eigenmodes of this solution are concentrated in the free stream, and the departure into turbulence from this solution evolves in the free stream towards the walls. For invariant solutions in free-stream turbulence, this solution thus shows that that the source of energy of the vortical structures can be a dynamical structure of the solution itself, instead of the laminar boundary layer.
40 CFR 255.21 - Local consultation on boundaries.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Local consultation on boundaries. 255.21 Section 255.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES IDENTIFICATION OF REGIONS AND AGENCIES FOR SOLID WASTE MANAGEMENT Procedures for Identifying Regions and...
40 CFR 255.21 - Local consultation on boundaries.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Local consultation on boundaries. 255.21 Section 255.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES IDENTIFICATION OF REGIONS AND AGENCIES FOR SOLID WASTE MANAGEMENT Procedures for Identifying Regions and...
40 CFR 255.21 - Local consultation on boundaries.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Local consultation on boundaries. 255.21 Section 255.21 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES IDENTIFICATION OF REGIONS AND AGENCIES FOR SOLID WASTE MANAGEMENT Procedures for Identifying Regions and...
Wang, Hao; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori
2013-07-31
The energy-density and stress-density schemes (Shiihara et al 2010 Phys. Rev. B 81 075441) within the projector augmented wave (PAW) method based on the generalized gradient approximation (GGA) have been applied to tilt and twist grain boundaries (GBs) and single vacancies in Cu and Al. Local energy and local stress at GBs and defects are obtained by integrating the energy and stress densities in each local region by the Bader integration using a recent algorithm (Yu et al 2011 J. Chem. Phys. 134 064111) as well as by the layer-by-layer integration so as to settle the gauge-dependent problem in the kinetic terms. Results are compared with those by the fuzzy-Voronoi integration and by the embedded atom method (EAM). The features of local energy and local stress at GBs and vacancies depend on the bonding nature of each material. Valence electrons in Al mainly located in the interatomic regions show remarkable response to structural disorder as significant valence charge redistribution or bond reconstruction, often leading to long-range variations of charges, energies and stresses, quite differently from d electrons in Cu mainly located near nuclei. All these features can be well represented by our local energy and local stress. The EAM potential for Al does not reproduce correct local energy or local stress, while the EAM potential for Cu provides satisfactory results. PMID:23835349
Response of Hypervelocity Boundary Layers to Global and Local Distortion
NASA Astrophysics Data System (ADS)
Flaherty, William; Austin, Joanna
2013-11-01
Concave surface curvature can impose significant distortion to compressible boundary layer flows due to multiple, potentially coupled, effects including an adverse pressure gradient, bulk flow compression, and possible centrifugal instabilities. Approximate methods provide insight into dominant mechanisms, however few strategies are capable of treating heat transfer effects and predictions diverge significantly from the available experimental data at larger pressure gradient. In this work, we examine the response of boundary layers to global and local distortions in hypervelocity flows where thermochemical energy exchange has significant impact on boundary layer structure and stability. Experiments are carried out in a novel expansion tube facility built at Illinois. We demonstrate that reasonable estimates of the laminar heat flux augmentation may be obtained as a function of the local turning angle, even at the conditions of greatest distortion. As a model problem to study the evolution of large-scale structures under strained conditions, streamwise vortices are imposed into the boundary layer. The impact of the additional local distortion is investigated. The heat transfer scaling is found to be robust even in the presence of the imposed structures.
Breaking integrability at the boundary: the sine-Gordon model with Robin boundary conditions
NASA Astrophysics Data System (ADS)
Arthur, Robert; Dorey, Patrick; Parini, Robert
2016-04-01
We explore boundary scattering in the sine-Gordon model with a non-integrable family of Robin boundary conditions. The soliton content of the field after collision is analysed using a numerical implementation of the direct scattering problem associated with the inverse scattering method. We find that an antikink may be reflected into various combinations of an antikink, a kink, and one or more breathers, depending on the values of the initial antikink velocity and a parameter associated with the boundary condition. In addition we observe regions with an intricate resonance structure arising from the creation of an intermediate breather whose recollision with the boundary is highly dependent on the breather phase.
Piloting and path integration within and across boundaries.
Mou, Weimin; Wang, Lin
2015-01-01
Three experiments investigated whether navigation is less efficient across boundaries than within boundaries. In an immersive virtual environment, participants learned objects' locations in a large room or a small room. Participants then pointed to the objects' original locations after physically walking a circuitous path without vision. For participants who learned the objects in the large room, the testing position and the learning position were in the same room so that participants did not cross boundaries before testing; for participants who learned the objects in the small room, the testing position and the learning position were in 2 different rooms so that participants crossed boundaries before testing. Participants who learned the objects in the large room, during testing, either saw cues indicating the targets' locations (piloting group) or not (path integration group). Participants who learned the objects in the small room, during testing did not see any cues correctly indicating the targets' locations. The results showed that pointing accuracy was higher for those who learned the objects in the large room and in the piloting group than for those who learned the objects in the small room. However, this cross-boundary cost did not occur when we contrasted participants who learned objects in the large room and in the path integration group with participants who learned in a small room. These results suggested that navigation that relies on path integration only is not sensitive to boundary crossing, although navigation that relies on piloting is less efficient across boundaries than within boundaries. PMID:24933698
On the Implementation of 3D Galerkin Boundary Integral Equations
Nintcheu Fata, Sylvain; Gray, Leonard J
2010-01-01
In this article, a reverse contribution technique is proposed to accelerate the construction of the dense influence matrices associated with a Galerkin approximation of singular and hypersingular boundary integral equations of mixed-type in potential theory. In addition, a general-purpose sparse preconditioner for boundary element methods has also been developed to successfully deal with ill-conditioned linear systems arising from the discretization of mixed boundary-value problems on non-smooth surfaces. The proposed preconditioner, which originates from the precorrected-FFT method, is sparse, easy to generate and apply in a Krylov subspace iterative solution of discretized boundary integral equations. Moreover, an approximate inverse of the preconditioner is implicitly built by employing an incomplete LU factorization. Numerical experiments involving mixed boundary-value problems for the Laplace equation are included to illustrate the performance and validity of the proposed techniques.
Local and bulk melting of Cu at grain boundaries
Luo, Shengnian; Han, Li - Bo; An, Qi; Zheng, Lianqing
2008-01-01
We investigate gain boundary (GB) melting using molecular dynamics simulations on face-centered-cubic Cu bicrystals with symmetric {l_angle}110{r_angle} tilt grain boundaries. Two representative types of GBs are explored: {Sigma} = 11/(113)/50.48{sup o} (low GB energy) and {Sigma} = 27/(552)/148.41{sup o} (high GB energy). The temperature and temporal evolutions of the Cu bicrystals under stepped heating are characterized in terms of order parameters and diffusion coefficients, as ell as the nucleation and growth of melt. Within the GB region, continuous local melting precedes discontinuous bulk melting, while continuous solid state disordering may precede local melting. Premelting may occur for local melting but not for bulk melting. For {Sigma} = 11/(113)/50.48{sup o}, premelting of the GB region is negligible, and local melting occurs near the thermodynamic melting temperature. The GB region as a whole is superheated by about 13% before its bulk melting. In the case of {Sigma} = 27/(552)/148.41, considerable premelting is observed for local melting, while the bulk melting occurs with negligible superheating. The exact melting behavior of a general GB depends on the GB energy, but is likely bracketed within these two cases.
Integral Formulation of the Boundary Value Problem in Waveguides.
ERIC Educational Resources Information Center
Sancho, M.
1980-01-01
Presents an integral approach to the boundary value problem in waveguides deduced from the Kirchoff's integral formulation of the electromagnetic field. Also, the basis for the numerical solution of more general problems is given, including the example of the isosceles right triangular guide. (Author/SK)
Crossing Boundaries: Explorations in Integrative Curriculum.
ERIC Educational Resources Information Center
Braunger, Jane; Hart-Landsberg, Sylvia
Curriculum in the United States is largely a fragmented set of subjects and teachers to present them. Many Pacific Northwestern educators are looking for innovative ways to organize curriculum that over comes the traditional structure. As knowledge of the learning process increases, integrative curriculum is being employed more frequently. Several…
Dissolving Boundaries: Toward an Integrative Curriculum.
ERIC Educational Resources Information Center
Brazee, Edward N.; Capelluti, Jody
An examination of the issues surrounding the concept of change is fundamental to curriculum improvement for elementary and middle schools. New beliefs surround an integrative rather than a separate subject isolation approach to curriculum. This report examines past, current, and future curriculum practice and considerations, focusing on a new…
Boundary Recovery For Delaunay Tetrahedral Meshes Using Local Topological Transformations
Ghadyani, Hamid; Sullivan, John; Wu, Ziji
2009-01-01
Numerous high-quality, volume mesh-generation systems exist. However, no strategy can address all geometry situations without some element qualities being compromised. Many 3D mesh generation algorithms are based on Delaunay tetrahedralization which frequently fails to preserve the input boundary surface topology. For biomedical applications, this surface preservation can be critical as they usually contain multiple material regions of interest coherently connected. In this paper we present an algorithm as a post-processing method that optimizes local regions of compromised element quality and recovers the original boundary surface facets (triangles) regardless of the original mesh generation strategy. The algorithm carves out a small sub-volume in the vicinity of the missing boundary facet or compromised element, creating a cavity. If the task is to recover a surface boundary facet, a natural exit hole in the cavity will be present. This hole is patched with the missing boundary surface face first followed by other patches to seal the cavity. If the task was to improve a compromised region, then the cavity is already sealed. Every triangular facet of the cavity shell is classified as an active face and can be connected to another shell node creating a tetrahedron. In the process the base of the tetrahedron is removed from the active face list and potentially 3 new active faces are created. This methodology is the underpinnings of our last resort method. Each active face can be viewed as the trunk of a tree. An exhaustive breath and depth search will identify all possible tetrahedral combinations to uniquely fill the cavity. We have streamlined this recursive process reducing the time complexity by orders of magnitude. The original surfaces boundaries (internal and external) are fully restored and the quality of compromised regions improved. PMID:20305743
Shao, Yeqin; Gao, Yaozong; Wang, Qian; Yang, Xin; Shen, Dinggang
2015-12-01
Automatic and accurate segmentation of the prostate and rectum in planning CT images is a challenging task due to low image contrast, unpredictable organ (relative) position, and uncertain existence of bowel gas across different patients. Recently, regression forest was adopted for organ deformable segmentation on 2D medical images by training one landmark detector for each point on the shape model. However, it seems impractical for regression forest to guide 3D deformable segmentation as a landmark detector, due to large number of vertices in the 3D shape model as well as the difficulty in building accurate 3D vertex correspondence for each landmark detector. In this paper, we propose a novel boundary detection method by exploiting the power of regression forest for prostate and rectum segmentation. The contributions of this paper are as follows: (1) we introduce regression forest as a local boundary regressor to vote the entire boundary of a target organ, which avoids training a large number of landmark detectors and building an accurate 3D vertex correspondence for each landmark detector; (2) an auto-context model is integrated with regression forest to improve the accuracy of the boundary regression; (3) we further combine a deformable segmentation method with the proposed local boundary regressor for the final organ segmentation by integrating organ shape priors. Our method is evaluated on a planning CT image dataset with 70 images from 70 different patients. The experimental results show that our proposed boundary regression method outperforms the conventional boundary classification method in guiding the deformable model for prostate and rectum segmentations. Compared with other state-of-the-art methods, our method also shows a competitive performance. PMID:26439938
Integrating Science with Local Experiences
ERIC Educational Resources Information Center
Black, Kathie
2004-01-01
Science exists in many forms, but an appreciation of science as an integral part of every day does not occur in the vacuum of laboratory experience or through classroom activities. Throughout the communities, a plethora of places exist to see science at work, from the usually recommended museums and parks to the less thought of factories and…
The Boundary Integral Equation Method for Porous Media Flow
NASA Astrophysics Data System (ADS)
Anderson, Mary P.
Just as groundwater hydrologists are breathing sighs of relief after the exertions of learning the finite element method, a new technique has reared its nodes—the boundary integral equation method (BIEM) or the boundary equation method (BEM), as it is sometimes called. As Liggett and Liu put it in the preface to The Boundary Integral Equation Method for Porous Media Flow, “Lately, the Boundary Integral Equation Method (BIEM) has emerged as a contender in the computation Derby.” In fact, in July 1984, the 6th International Conference on Boundary Element Methods in Engineering will be held aboard the Queen Elizabeth II, en route from Southampton to New York. These conferences are sponsored by the Department of Civil Engineering at Southampton College (UK), whose members are proponents of BIEM. The conferences have featured papers on applications of BIEM to all aspects of engineering, including flow through porous media. Published proceedings are available, as are textbooks on application of BIEM to engineering problems. There is even a 10-minute film on the subject.
Application of boundary integral equations to elastoplastic problems
NASA Technical Reports Server (NTRS)
Mendelson, A.; Albers, L. U.
1975-01-01
The application of boundary integral equations to elastoplastic problems is reviewed. Details of the analysis as applied to torsion problems and to plane problems is discussed. Results are presented for the elastoplastic torsion of a square cross section bar and for the plane problem of notched beams. A comparison of different formulations as well as comparisons with experimental results are presented.
Local-time representation of path integrals
NASA Astrophysics Data System (ADS)
Jizba, Petr; Zatloukal, Václav
2015-12-01
We derive a local-time path-integral representation for a generic one-dimensional time-independent system. In particular, we show how to rephrase the matrix elements of the Bloch density matrix as a path integral over x -dependent local-time profiles. The latter quantify the time that the sample paths x (t ) in the Feynman path integral spend in the vicinity of an arbitrary point x . Generalization of the local-time representation that includes arbitrary functionals of the local time is also provided. We argue that the results obtained represent a powerful alternative to the traditional Feynman-Kac formula, particularly in the high- and low-temperature regimes. To illustrate this point, we apply our local-time representation to analyze the asymptotic behavior of the Bloch density matrix at low temperatures. Further salient issues, such as connections with the Sturm-Liouville theory and the Rayleigh-Ritz variational principle, are also discussed.
Numerical solution of boundary-integral equations for molecular electrostatics.
Bardhan, Jaydeep P
2009-03-01
Numerous molecular processes, such as ion permeation through channel proteins, are governed by relatively small changes in energetics. As a result, theoretical investigations of these processes require accurate numerical methods. In the present paper, we evaluate the accuracy of two approaches to simulating boundary-integral equations for continuum models of the electrostatics of solvation. The analysis emphasizes boundary-element method simulations of the integral-equation formulation known as the apparent-surface-charge (ASC) method or polarizable-continuum model (PCM). In many numerical implementations of the ASC/PCM model, one forces the integral equation to be satisfied exactly at a set of discrete points on the boundary. We demonstrate in this paper that this approach to discretization, known as point collocation, is significantly less accurate than an alternative approach known as qualocation. Furthermore, the qualocation method offers this improvement in accuracy without increasing simulation time. Numerical examples demonstrate that electrostatic part of the solvation free energy, when calculated using the collocation and qualocation methods, can differ significantly; for a polypeptide, the answers can differ by as much as 10 kcal/mol (approximately 4% of the total electrostatic contribution to solvation). The applicability of the qualocation discretization to other integral-equation formulations is also discussed, and two equivalences between integral-equation methods are derived. PMID:19275391
Boundary layer integral matrix procedure: Verification of models
NASA Technical Reports Server (NTRS)
Bonnett, W. S.; Evans, R. M.
1977-01-01
The three turbulent models currently available in the JANNAF version of the Aerotherm Boundary Layer Integral Matrix Procedure (BLIMP-J) code were studied. The BLIMP-J program is the standard prediction method for boundary layer effects in liquid rocket engine thrust chambers. Experimental data from flow fields with large edge-to-wall temperature ratios are compared to the predictions of the three turbulence models contained in BLIMP-J. In addition, test conditions necessary to generate additional data on a flat plate or in a nozzle are given. It is concluded that the Cebeci-Smith turbulence model be the recommended model for the prediction of boundary layer effects in liquid rocket engines. In addition, the effects of homogeneous chemical reaction kinetics were examined for a hydrogen/oxygen system. Results show that for most flows, kinetics are probably only significant for stoichiometric mixture ratios.
An Efficient Boundary Integral Method for the Mullins Sekerka Problem
NASA Astrophysics Data System (ADS)
Zhu, Jingyi; Chen, Xinfu; Hou, Thomas Y.
1996-09-01
We use a boundary integral technique to study the two space dimensional Mullins-Sekerka free boundary problem which originates from a study of solidification and liquidation of materials of negligible specific heat. This is an area preserving and curve shortening motion. Evolution equations for the free boundaries are derived in terms of the tangent angle and total arclength, which makes a small scale decomposition possible and the Fourier transform a powerful tool in numerical calculations. With this formulation, implicit schemes can be implemented to avoid the difficult numerical stiffness associated with explicit schemes. We can compute solutions up to the time when there is a topological change, i.e., when particles touch or break up. Our numerical results for systems of a single particle or multi-particles provide some valuable information in the particle dynamics, such as the circularization of each individual particle, and the mass transfer between different particles during particle interactions.
Defining a boundary in goal localization: Infinite number of points or extended surfaces.
Mou, Weimin; Zhou, Ruojing
2013-07-01
Four experiments examined the roles of extended surfaces and the number of points in the boundary superiority effect in goal localization. Participants learned the locations of 4 objects in the presence of a boundary, landmarks, or both in an immersive virtual environment by reproducing the locations with feedback. Participants then localized the objects in the presence of either the boundary or the landmarks during testing without feedback. The results showed that when both 1 landmark and a circular boundary were presented during learning, localization error during testing increased significantly when only the landmark was presented during testing, whereas localization error did not increase when only the boundary was presented during testing, thus demonstrating a boundary superiority effect. This boundary superiority effect was not observed when 36 landmarks forming a circle and a circular boundary were presented during learning. The landmark superiority effect was observed when 36 landmarks, forming a circular shape, and 1/36th part of the circular boundary were presented during learning. Furthermore, when a varied number of landmarks were presented with a circular boundary during learning, the localization error when the boundary was removed during testing was negatively correlated with the number of the landmarks. These results indicate that the superiority of a circular boundary to a landmark might be due to the larger number of points in the circular boundary but not due to the extended surface of the circular boundary. PMID:23088544
Discretization of the induced-charge boundary integral equation.
Bardhan, J. P.; Eisenberg, R. S.; Gillespie, D.; Rush Univ. Medical Center
2009-07-01
Boundary-element methods (BEMs) for solving integral equations numerically have been used in many fields to compute the induced charges at dielectric boundaries. In this paper, we consider a more accurate implementation of BEM in the context of ions in aqueous solution near proteins, but our results are applicable more generally. The ions that modulate protein function are often within a few angstroms of the protein, which leads to the significant accumulation of polarization charge at the protein-solvent interface. Computing the induced charge accurately and quickly poses a numerical challenge in solving a popular integral equation using BEM. In particular, the accuracy of simulations can depend strongly on seemingly minor details of how the entries of the BEM matrix are calculated. We demonstrate that when the dielectric interface is discretized into flat tiles, the qualocation method of Tausch et al. [IEEE Trans Comput.-Comput.-Aided Des. 20, 1398 (2001)] to compute the BEM matrix elements is always more accurate than the traditional centroid-collocation method. Qualocation is not more expensive to implement than collocation and can save significant computational time by reducing the number of boundary elements needed to discretize the dielectric interfaces.
Discretization of the induced-charge boundary integral equation
NASA Astrophysics Data System (ADS)
Bardhan, Jaydeep P.; Eisenberg, Robert S.; Gillespie, Dirk
2009-07-01
Boundary-element methods (BEMs) for solving integral equations numerically have been used in many fields to compute the induced charges at dielectric boundaries. In this paper, we consider a more accurate implementation of BEM in the context of ions in aqueous solution near proteins, but our results are applicable more generally. The ions that modulate protein function are often within a few angstroms of the protein, which leads to the significant accumulation of polarization charge at the protein-solvent interface. Computing the induced charge accurately and quickly poses a numerical challenge in solving a popular integral equation using BEM. In particular, the accuracy of simulations can depend strongly on seemingly minor details of how the entries of the BEM matrix are calculated. We demonstrate that when the dielectric interface is discretized into flat tiles, the qualocation method of Tausch [IEEE Trans Comput.-Comput.-Aided Des. 20, 1398 (2001)] to compute the BEM matrix elements is always more accurate than the traditional centroid-collocation method. Qualocation is not more expensive to implement than collocation and can save significant computational time by reducing the number of boundary elements needed to discretize the dielectric interfaces.
Discretization of the Induced-Charge Boundary Integral Equation
Bardhan, Jaydeep P.; Eisenberg, Robert S.; Gillespie, Dirk
2013-01-01
Boundary-element methods (BEM) for solving integral equations numerically have been used in many fields to compute the induced charges at dielectric boundaries. In this paper, we consider a more accurate implementation of BEM in the context of ions in aqueous solution near proteins, but our results are applicable more generally. The ions that modulate protein function are often within a few Angstroms of the protein, which leads to the significant accumulation of polarization charge at the protein/solvent interface. Computing the induced charge accurately and quickly poses a numerical challenge in solving a popular integral equation using BEM. In particular, the accuracy of simulations can depend strongly on seemingly minor details of how the entries of the BEM matrix are calculated. We demonstrate that when the dielectric interface is discretized into flat tiles, the qualocation method of Tausch, Wang, and White (IEEE. Trans. Comput.-Aided Des. 20:1398, 2001) to compute the BEM matrix elements is always more accurate than the traditional centroid collocation method. Qualocation is no more expensive to implement than collocation and can save significant computional time by reducing the number of boundary elements needed to discretize the dielectric interfaces. PMID:19658728
Local-time representation of path integrals.
Jizba, Petr; Zatloukal, Václav
2015-12-01
We derive a local-time path-integral representation for a generic one-dimensional time-independent system. In particular, we show how to rephrase the matrix elements of the Bloch density matrix as a path integral over x-dependent local-time profiles. The latter quantify the time that the sample paths x(t) in the Feynman path integral spend in the vicinity of an arbitrary point x. Generalization of the local-time representation that includes arbitrary functionals of the local time is also provided. We argue that the results obtained represent a powerful alternative to the traditional Feynman-Kac formula, particularly in the high- and low-temperature regimes. To illustrate this point, we apply our local-time representation to analyze the asymptotic behavior of the Bloch density matrix at low temperatures. Further salient issues, such as connections with the Sturm-Liouville theory and the Rayleigh-Ritz variational principle, are also discussed. PMID:26764662
Integrated program designed for local governments.
1993-01-01
Local Philippine governments are required under the 1991 Local Government Code to plan and manage their own health and nutrition programs. In response to their requests, the Municipal Integrated Nutrition Program (MINP) is being developed. This program will integrate the local efforts of the following national nutrition programs: the Teacher-Child-Parent Approach of the Department of Education, Culture, and Sports; the Community-Based Planning and Management of Nutrition Programs of the Department of Health; the Early Childhood Enrichment Program of the Department of Social welfare and Development; and the Bio-Intensive Gardening for Home/Community Food Security of the Department of Agriculture. The Nutrition Center of the Philippines (NCP) has assisted in the development, testing, and evaluation of the MINP. In 1993, MINP models will begin in 1 or 2 barangays in Carmen, Cebu; Hilongos, Leyte; and Dapitan City in Zamboanga del Norte. NCP will provide program materials and technical assistance. Modeling activities will include advocating to local government units; designing and installing nutrition planning capability via planning workshops; packaging of program requirements and costs; designing a strategy to mobilize resources; facilitating purchase, delivery, and payment of program requirements; facilitating and coordinating training; designing and installing a monitoring and evaluation system; and documenting and disseminating. Local government officials, technical government agencies, nongovernment organizations, and private entities will work together. PMID:12287618
A boundary integral formalism for stochastic ray tracing in billiards
Chappell, David J.; Tanner, Gregor
2014-12-15
Determining the flow of rays or non-interacting particles driven by a force or velocity field is fundamental to modelling many physical processes. These include particle flows arising in fluid mechanics and ray flows arising in the geometrical optics limit of linear wave equations. In many practical applications, the driving field is not known exactly and the dynamics are determined only up to a degree of uncertainty. This paper presents a boundary integral framework for propagating flows including uncertainties, which is shown to systematically interpolate between a deterministic and a completely random description of the trajectory propagation. A simple but efficient discretisation approach is applied to model uncertain billiard dynamics in an integrable rectangular domain.
Defining a Boundary in Goal Localization: Infinite Number of Points or Extended Surfaces
ERIC Educational Resources Information Center
Mou, Weimin; Zhou, Ruojing
2013-01-01
Four experiments examined the roles of extended surfaces and the number of points in the boundary superiority effect in goal localization. Participants learned the locations of 4 objects in the presence of a boundary, landmarks, or both in an immersive virtual environment by reproducing the locations with feedback. Participants then localized the…
Shen, Hui-min; Lee, Kok-Meng; Hu, Liang; Foong, Shaohui; Fu, Xin
2016-01-01
Localization of active neural source (ANS) from measurements on head surface is vital in magnetoencephalography. As neuron-generated magnetic fields are extremely weak, significant uncertainties caused by stochastic measurement interference complicate its localization. This paper presents a novel computational method based on reconstructed magnetic field from sparse noisy measurements for enhanced ANS localization by suppressing effects of unrelated noise. In this approach, the magnetic flux density (MFD) in the nearby current-free space outside the head is reconstructed from measurements through formulating the infinite series solution of the Laplace's equation, where boundary condition (BC) integrals over the entire measurements provide "smooth" reconstructed MFD with the decrease in unrelated noise. Using a gradient-based method, reconstructed MFDs with good fidelity are selected for enhanced ANS localization. The reconstruction model, spatial interpolation of BC, parametric equivalent current dipole-based inverse estimation algorithm using reconstruction, and gradient-based selection are detailed and validated. The influences of various source depths and measurement signal-to-noise ratio levels on the estimated ANS location are analyzed numerically and compared with a traditional method (where measurements are directly used), and it was demonstrated that gradient-selected high-fidelity reconstructed data can effectively improve the accuracy of ANS localization. PMID:26358243
The development of high angle deformation boundaries and local orientations in aluminum
Hughes, D.A.
1996-03-01
High angle boundaries and their local surroundings are important for all aspects of recrystallization including nucleation, growth and texture formation. They are thus important for processing of aluminum alloys. Deformation induced high angle boundaries have been observed and quantitatively characterized using transmission electron microscopy in aluminum following rolling to large reductions. The distribution of local orientations between individual dislocation boundaries and their angle/axis pairs have been measured using convergent beam Kikuchi analysis and are compared to the macroscopic texture. The sequence of near neighbor orientations shows that individual grains subdivide across their thickness into three to four different texture components separated by sharp boundaries. The local orientations surrounding high angle boundaries are much more diverse than suggested by simple models and single crystal studies. The origins for these high angle boundaries are suggested and discussed.
The Application of a Boundary Integral Equation Method to the Prediction of Ducted Fan Engine Noise
NASA Technical Reports Server (NTRS)
Dunn, M. H.; Tweed, J.; Farassat, F.
1999-01-01
The prediction of ducted fan engine noise using a boundary integral equation method (BIEM) is considered. Governing equations for the BIEM are based on linearized acoustics and describe the scattering of incident sound by a thin, finite-length cylindrical duct in the presence of a uniform axial inflow. A classical boundary value problem (BVP) is derived that includes an axisymmetric, locally reacting liner on the duct interior. Using potential theory, the BVP is recast as a system of hypersingular boundary integral equations with subsidiary conditions. We describe the integral equation derivation and solution procedure in detail. The development of the computationally efficient ducted fan noise prediction program TBIEM3D, which implements the BIEM, and its utility in conducting parametric noise reduction studies are discussed. Unlike prediction methods based on spinning mode eigenfunction expansions, the BIEM does not require the decomposition of the interior acoustic field into its radial and axial components which, for the liner case, avoids the solution of a difficult complex eigenvalue problem. Numerical spectral studies are presented to illustrate the nexus between the eigenfunction expansion representation and BIEM results. We demonstrate BIEM liner capability by examining radiation patterns for several cases of practical interest.
Kolmogorov turbulence, Anderson localization and KAM integrability
NASA Astrophysics Data System (ADS)
Shepelyansky, D. L.
2012-06-01
The conditions for emergence of Kolmogorov turbulence, and related weak wave turbulence, in finite size systems are analyzed by analytical methods and numerical simulations of simple models. The analogy between Kolmogorov energy flow from large to small spacial scales and conductivity in disordered solid state systems is proposed. It is argued that the Anderson localization can stop such an energy flow. The effects of nonlinear wave interactions on such a localization are analyzed. The results obtained for finite size system models show the existence of an effective chaos border between the Kolmogorov-Arnold-Moser (KAM) integrability at weak nonlinearity, when energy does not flow to small scales, and developed chaos regime emerging above this border with the Kolmogorov turbulent energy flow from large to small scales.
Turning the corner in fertility: high DNA integrity of boundary-following sperm.
Eamer, Lise; Vollmer, Marion; Nosrati, Reza; San Gabriel, Maria C; Zeidan, Krista; Zini, Armand; Sinton, David
2016-07-01
We present a passive microfluidic sperm selection strategy that collects motile sperm based on their preference to follow boundaries and turn corners. Clinical assessment of selected human sperm from the device revealed a strong correlation between high DNA integrity and the tendency for sperm to follow boundaries. Human sperm with preference to follow boundaries on the left- or right-hand sides have higher (>51%) DNA integrity than straight swimmers and significantly higher (>67%) DNA integrity than sperm in raw semen. Boundary following behaviour offers a strategy to selecting sperm with the highest DNA integrity to improve the success rate of assisted reproduction. PMID:27241827
Erlikhman, Gennady; Kellman, Philip J
2016-01-01
Spatiotemporal boundary formation (SBF) is the perception of illusory boundaries, global form, and global motion from spatially and temporally sparse transformations of texture elements (Shipley and Kellman, 1993a, 1994; Erlikhman and Kellman, 2015). It has been theorized that the visual system uses positions and times of element transformations to extract local oriented edge fragments, which then connect by known interpolation processes to produce larger contours and shapes in SBF. To test this theory, we created a novel display consisting of a sawtooth arrangement of elements that disappeared and reappeared sequentially. Although apparent motion along the sawtooth would be expected, with appropriate spacing and timing, the resulting percept was of a larger, moving, illusory bar. This display approximates the minimal conditions for visual perception of an oriented edge fragment from spatiotemporal information and confirms that such events may be initiating conditions in SBF. Using converging objective and subjective methods, experiments showed that edge formation in these displays was subject to a temporal integration constraint of ~80 ms between element disappearances. The experiments provide clear support for models of SBF that begin with extraction of local edge fragments, and they identify minimal conditions required for this process. We conjecture that these results reveal a link between spatiotemporal object perception and basic visual filtering. Motion energy filters have usually been studied with orientation given spatially by luminance contrast. When orientation is not given in static frames, these same motion energy filters serve as spatiotemporal edge filters, yielding local orientation from discrete element transformations over time. As numerous filters of different characteristic orientations and scales may respond to any simple SBF stimulus, we discuss the aperture and ambiguity problems that accompany this conjecture and how they might be resolved
Erlikhman, Gennady; Kellman, Philip J.
2016-01-01
Spatiotemporal boundary formation (SBF) is the perception of illusory boundaries, global form, and global motion from spatially and temporally sparse transformations of texture elements (Shipley and Kellman, 1993a, 1994; Erlikhman and Kellman, 2015). It has been theorized that the visual system uses positions and times of element transformations to extract local oriented edge fragments, which then connect by known interpolation processes to produce larger contours and shapes in SBF. To test this theory, we created a novel display consisting of a sawtooth arrangement of elements that disappeared and reappeared sequentially. Although apparent motion along the sawtooth would be expected, with appropriate spacing and timing, the resulting percept was of a larger, moving, illusory bar. This display approximates the minimal conditions for visual perception of an oriented edge fragment from spatiotemporal information and confirms that such events may be initiating conditions in SBF. Using converging objective and subjective methods, experiments showed that edge formation in these displays was subject to a temporal integration constraint of ~80 ms between element disappearances. The experiments provide clear support for models of SBF that begin with extraction of local edge fragments, and they identify minimal conditions required for this process. We conjecture that these results reveal a link between spatiotemporal object perception and basic visual filtering. Motion energy filters have usually been studied with orientation given spatially by luminance contrast. When orientation is not given in static frames, these same motion energy filters serve as spatiotemporal edge filters, yielding local orientation from discrete element transformations over time. As numerous filters of different characteristic orientations and scales may respond to any simple SBF stimulus, we discuss the aperture and ambiguity problems that accompany this conjecture and how they might be resolved
A time-domain finite element boundary integration method for ultrasonic nondestructive evaluation.
Shi, Fan; Choi, Wonjae; Skelton, Elizabeth A; Lowe, Michael J S; Craster, Richard V
2014-12-01
A 2-D and 3-D numerical modeling approach for calculating the elastic wave scattering signals from complex stress-free defects is evaluated. In this method, efficient boundary integration across the complex boundary of the defect is coupled with a time-domain finite element (FE) solver. The model is designed to simulate time-domain ultrasonic nondestructive evaluation in bulk media. This approach makes use of the hybrid concept of linking a local numerical model to compute the near-field scattering behavior and theoretical mathematical formulas for postprocessing to calculate the received signals. It minimizes the number of monitoring signals from the FE calculation so that the computation effort in postprocessing decreases significantly. In addition, by neglecting the conventional regular monitoring box, the region for FE calculation can be made smaller. In this paper, the boundary integral method is implemented in a commercial FE code, and it is validated by comparing the scattering signals with results from corresponding full FE models. The coupled method is then implemented in real inspection scenarios in both 2-D and 3-D, and the accuracy and the efficiency are demonstrated. The limitations of the proposed model and future works are also discussed. PMID:25474780
Control of a shock wave-boundary layer interaction using localized arc filament plasma actuators
NASA Astrophysics Data System (ADS)
Webb, Nathan Joseph
Supersonic flight is currently possible, but expensive. Inexpensive supersonic travel will require increased efficiency of high-speed air entrainment, an integral part of air-breathing propulsion systems. Although mixed compression inlet geometry can significantly improve entrainment efficiency, numerous Shock Wave-Boundary Layer Interactions (SWBLIs) are generated in this configuration. The boundary layer must therefore develop through multiple regions of adverse pressure gradient, causing it to thicken, and, in severe cases, separate. The associated increase in unsteadiness can have adverse effects on downstream engine hardware. The most severe consequence of these interactions is the increased aerodynamic blockage generated by the thickened boundary layer. If the increase is sufficient, it can choke the flow, causing inlet unstart, and resulting in a loss of thrust and high transient forces on the engine, airframe, and aircraft occupants. The potentially severe consequences associated with SWBLIs require flow control to ensure proper operation. Traditionally, boundary layer bleed has been used to control the interaction. Although this method is effective, it has inherent efficiency penalties. Localized Arc Filament Plasma Actuators (LAFPAs) are designed to generate perturbations for flow control. Natural flow instabilities act to amplify certain perturbations, allowing the LAFPAs to control the flow with minimal power input. LAFPAs also have the flexibility to maintain control over a variety of operating conditions. This work seeks to examine the effectiveness of LAFPAs as a separation control method for an oblique, impinging SWBLI. The low frequency unsteadiness in the reflected shock was thought to be the natural manifestation of a Kelvin-Helmholtz instability in the shear layer above the separation region. The LAFPAs were therefore placed upstream of the interaction to allow their perturbations to convect to the receptivity region (near the shear layer origin
Boundary diffraction wave integrals for diffraction modeling of external occulters.
Cady, Eric
2012-07-01
An occulter is a large diffracting screen which may be flown in conjunction with a telescope to image extrasolar planets. The edge is shaped to minimize the diffracted light in a region beyond the occulter, and a telescope may be placed in this dark shadow to view an extrasolar system with the starlight removed. Errors in position, orientation, and shape of the occulter will diffract additional light into this region, and a challenge of modeling an occulter system is to accurately and quickly model these effects. We present a fast method for the calculation of electric fields following an occulter, based on the concept of the boundary diffraction wave: the 2D structure of the occulter is reduced to a 1D edge integral which directly incorporates the occulter shape, and which can be easily adjusted to include changes in occulter position and shape, as well as the effects of sources-such as exoplanets-which arrive off-axis to the occulter. The structure of a typical implementation of the algorithm is included. PMID:22772218
NASA Astrophysics Data System (ADS)
Abaie, Behnam; Hosseini, Seyed Rasoul; Karbasi, Salman; Mafi, Arash
2016-04-01
Impact of the boundaries on transversely localized modes of a truncated one-dimensional disordered optical lattice is numerically studied. The results show lower modal number density near the boundaries compared with the bulk, while the average decay rate of the tail of localized modes is the same near the boundaries as in the bulk. It is suggested that the perceived suppressed localization near the boundaries is due to a lower mode density: on average, it is less probable to excite a localized mode near the boundaries; however, once it is excited, its localization is with the same exponential decay rate as any other localized mode.
The D(D3)-anyon chain: integrable boundary conditions and excitation spectra
NASA Astrophysics Data System (ADS)
Finch, Peter E.; Frahm, Holger
2013-05-01
Chains of interacting non-Abelian anyons with local interactions invariant under the action of the Drinfeld double of the dihedral group D3 are constructed. Formulated as a spin chain the Hamiltonians are generated from commuting transfer matrices of an integrable vertex model for periodic and braided as well as open boundaries. A different anyonic model with the same local Hamiltonian is obtained within the fusion path formulation. This model is shown to be related to an integrable fusion interaction round the face model. Bulk and surface properties of the anyon chain are computed from the Bethe equations for the spin chain. The low-energy effective theories and operator content of the models (in both the spin chain and fusion path formulation) are identified from analytical and numerical studies of the finite-size spectra. For all boundary conditions considered the continuum theory is found to be a product of two conformal field theories. Depending on the coupling constants the factors can be a Z4 parafermion or a {M}_{(5,6)} minimal model.
Boundary Ambiguity in Parents with Chronically Ill Children: Integrating Theory and Research
ERIC Educational Resources Information Center
Berge, Jerica M.; Holm, Kristen E.
2007-01-01
This article integrates theory and research related to boundary ambiguity in parents of children with a chronic health condition. We propose that boundary ambiguity is a risk factor for psychological distress in these parents. Clinical applications and a case example highlight how boundary ambiguity can be assessed and managed in clinical settings…
Application of boundary integral method to elastic analysis of V-notched beams
NASA Technical Reports Server (NTRS)
Rzasnicki, W.; Mendelson, A.; Albers, L. U.
1973-01-01
A semidirect boundary integral method, using Airy's stress function and its derivatives in Green's boundary integral formula, is used to obtain an accurate numerical solution for elastic stress and strain fields in V-notched beams in pure bending. The proper choice of nodal spacing on the boundary is shown to be necessary to achieve an accurate stress field in the vicinity of the tip of the notch. Excellent agreement is obtained with the results of the collocation method of solution.
Piloting and Path Integration within and across Boundaries
ERIC Educational Resources Information Center
Mou, Weimin; Wang, Lin
2015-01-01
Three experiments investigated whether navigation is less efficient across boundaries than within boundaries. In an immersive virtual environment, participants learned objects' locations in a large room or a small room. Participants then pointed to the objects' original locations after physically walking a circuitous path without vision.…
NASA Technical Reports Server (NTRS)
Siegel, R.
1993-01-01
An analytical solution was obtained by Siegel (1991, 1992) for local boundary heat fluxes by a radiating medium at uniform temperature in a 2D rectangular region. It is shown here that, after local fluxes from the medium to the walls have been evaluated, it is very easy to compute local fluxes arriving from the adjacent and opposite walls. This extends the previous analysis and provides convenient relations to include radiation from a black boundary, each side of the rectangle being at a different uniform temperature. The final expressions are helpful in performing spectral calculations that must be made for many spectral bands.
Turbulent shear spectra and local isotropy in the low-speed boundary layer
NASA Technical Reports Server (NTRS)
Sandborn, Virgil A; Braun, Willis H
1956-01-01
From measurements of turbulent shear spectra together with previously reported longitudinal turbulent energy spectra, the concept of local isotropy in a low-speed boundary layer was examined. Results of these measurements and measurements of the time derivatives of turbulent velocities in the x- and y- directions for various frequency bands showed no evidence of local isotropy in the boundary layer. Several methods (based on isotropy) of evaluating the turbulent dissipation term failed to give consistent answers, further emphasizing a lack of local isotropy.
NASA Astrophysics Data System (ADS)
Ginzburg, Irina; Roux, Laetitia; Silva, Goncalo
2015-10-01
This work demonstrates that in advection-diffusion Lattice Boltzmann schemes, the local mass-conserving boundary rules, such as bounce-back and local specular reflection, may modify the transport coefficients predicted by the Chapman-Enskog expansion when they enforce to zero not only the normal, but also the tangential boundary flux. In order to accommodate it to the bulk solution, the system develops a Knudsen-layer correction to the non-equilibrium part of the population solution. Two principal secondary effects-(i) decrease in the diffusion coefficient, and (ii) retardation of the average advection velocity, obtained in a closed analytical form, are proportional, respectively, to freely assigned diagonal weights for equilibrium mass and velocity terms. In addition, due to their transverse velocity gradients, the boundary layers affect the longitudinal diffusion coefficient similarly to Taylor dispersion, as they grow as the square of the Péclet number. These numerical artifacts can be eliminated or reduced by a proper space distribution of the free-tunable collision eigenvalue in two-relaxation-time schemes.
NASA Astrophysics Data System (ADS)
Kluge, M. D.; Wolf, D.; Lutsko, J. F.; Phillpot, S. R.
1990-03-01
A new formalism for use in atomistic simulations to calculate the full local elastic-constant tensor in terms of local stresses and strains is presented. Results of simulations on a high-angle (001) twist grain boundary are illustrated, using both a Lennard-Jones potential for Cu and an embedded-atom potential for Au. The two conceptionally rather different potentials show similar anomalies in all elastic constants, confined to within a few lattice planes of the grain boundary, with an especially dramatic reduction in the resistance to shear parallel to the grain-boundary plane. It is found that the primary cause of the anomalies is the atomic disorder near the grain boundary, as evidenced by the slice-by-slice radial distribution functions for the inhomogeneous interface system.
A non-local free boundary problem arising in a theory of financial bubbles
Berestycki, Henri; Monneau, Regis; Scheinkman, José A.
2014-01-01
We consider an evolution non-local free boundary problem that arises in the modelling of speculative bubbles. The solution of the model is the speculative component in the price of an asset. In the framework of viscosity solutions, we show the existence and uniqueness of the solution. We also show that the solution is convex in space, and establish several monotonicity properties of the solution and of the free boundary with respect to parameters of the problem. To study the free boundary, we use, in particular, the fact that the odd part of the solution solves a more standard obstacle problem. We show that the free boundary is and describe the asymptotics of the free boundary as c, the cost of transacting the asset, goes to zero. PMID:25288815
Boundary regularized integral equation formulation of the Helmholtz equation in acoustics.
Sun, Qiang; Klaseboer, Evert; Khoo, Boo-Cheong; Chan, Derek Y C
2015-01-01
A boundary integral formulation for the solution of the Helmholtz equation is developed in which all traditional singular behaviour in the boundary integrals is removed analytically. The numerical precision of this approach is illustrated with calculation of the pressure field owing to radiating bodies in acoustic wave problems. This method facilitates the use of higher order surface elements to represent boundaries, resulting in a significant reduction in the problem size with improved precision. Problems with extreme geometric aspect ratios can also be handled without diminished precision. When combined with the CHIEF method, uniqueness of the solution of the exterior acoustic problem is assured without the need to solve hypersingular integrals. PMID:26064591
Boundary integral equation analysis for steady thermoelastic problems using thermoelastic potential
Koizumi, T.; Shibuya, T.; Kurokawa, K.; Tsuji, T.; Takakuda, K.
1988-01-01
In a boundary integral formulation for a thermoelastic problem, the temperature change is treated as an equivalent body force. Therefore, even in the case of zero body force, the formulation involves volume integrals. In the present paper, it is proved that the introduction of the thermoelastic potential succeeds in eliminating the volume integrals in the three-dimensional formulation. The formulations are transformed from Cartesian coordinates into axisymmetric coordinates. All the surface integrals are replaced by line integrals along the boundary of the axisymmetric domain. By using the above formulation, the deformation and stress distributions of a bonded cylinder subjected to a uniform temperature change are analyzed numerically. 7 references.
NASA Astrophysics Data System (ADS)
Bhattacharya, Amitabh
2013-11-01
An efficient algorithm for simulating Stokes flow around particles is presented here, in which a second order Finite Difference method (FDM) is coupled to a Boundary Integral method (BIM). This method utilizes the strong points of FDM (i.e. localized stencil) and BIM (i.e. accurate representation of particle surface). Specifically, in each iteration, the flow field away from the particles is solved on a Cartesian FDM grid, while the traction on the particle surface (given the the velocity of the particle) is solved using BIM. The two schemes are coupled by matching the solution in an intermediate region between the particle and surrounding fluid. We validate this method by solving for flow around an array of cylinders, and find good agreement with Hasimoto's (J. Fluid Mech. 1959) analytical results.
NASA Astrophysics Data System (ADS)
Gambini, Rodolfo; Pullin, Jorge
2013-01-01
We discuss a gauge fixing of gravity coupled to a scalar field in spherical symmetry such that the Hamiltonian is an integral over space of a local density. In a previous paper, we had presented it using Ashtekar’s new variables. Here we study it in metric variables. We specify completely the initial-boundary value problem for ingoing Gaussian pulses.
Local versus nonlocal boundary-layer diffusion in a global climate model
Holtslag, A.A.M. ); Boville, B.A. )
1993-10-01
The results of a local and a nonlocal scheme for vertical diffusion in the atmospheric boundary layer are compared within the context of a global climate model. The global model is an updated version of the NCAR Community Climate Model (CCM2). The local diffusion scheme uses an eddy diffusivity determined independently at each point in the vertical, based on local vertical gradients of wind and virtual potential temperature, similar to the usual approach in global atmospheric models. The nonlocal scheme determines an eddy-diffusivity profile based on a diagnosed boundary-layer height and a turbulent velocity scale. It also incorporates nonlocal (vertical) transport effects for heat and moisture. The two diffusion schemes are summarized, and their results are compared with independent radiosonde observations for a number of locations. The focus herein is on the temperature and humidity structure over ocean, where the surface temperatures are specified, since the boundary-layer scheme interacts strongly with the land-surface parameterization. Systematic differences are shown in global-climate simulations, with CCM2 using the two schemes. The nonlocal scheme transports moisture away from the surface more rapidly than the local scheme, and deposits the moisture at higher levels. The local scheme tends to saturate the lowest model levels unrealistically, which typically leads to clouds too low in the atmosphere. The nonlocal scheme has been chosen for CCM2 because of its more comprehensive representation of the physics of boundary-layer transport in dry convective conditions. 35 refs., 12 figs.
Shear flow beneath oceanic plates - Local nonsimilarity boundary layers for olivine rheology
NASA Technical Reports Server (NTRS)
Yuen, D. A.; Tovish, A.; Schubert, G.
1978-01-01
The principle of local similarity, which has been used to model the two-dimensional boundary layers in the oceanic upper mantle, permits calculation of the temperature, velocity, and stress fields with essentially analytic techniques. Finite difference numerical methods are hard pressed to resolve the detail required by the large variation of viscosity between the lithosphere and the asthenosphere. In this paper the local similarity approximation has been justified by quantitatively evaluating the effect of nonsimilarity due to viscous heating, nonlinear temperature- and pressure-dependent rheology, buoyancy, adiabatic cooling, etc. Nonsimilar effects produce only small modifications of the locally similar boundary layers; important geophysical observables such as surface heat flux and ocean floor topography are given to better than 10 percent by the locally similar solution. A posteriori evaluations of the terms neglected in the boundary layer simplification of the complete equations have been conducted on the locally similar temperature and velocity profiles close to the spreading ridge. The boundary layer models are valid to depths of 100 km at 3 m.y. and 10 km at 0.3 m.y.
Direct numerical simulation of bedload transport using a local, dynamic boundary condition
Schmeeckle, M.W.; Nelson, J.M.
2003-01-01
Temporally and spatially averaged models of bedload transport are inadequate to describe the highly variable nature of particle motion at low transport stages. The primary sources of this variability are the resisting forces to downstream motion resulting from the geometrical relation (pocket friction angle) of a bed grain to the grains that it rests upon, variability of the near-bed turbulent velocity field and the local modification of this velocity field by upstream, protruding grains. A model of bedload transport is presented that captures these sources of variability by directly integrating the equations of motion of each particle of a simulated mixed grain-size sediment bed. Experimental data from the velocity field downstream and below the tops of upstream, protruding grains are presented. From these data, an empirical relation for the velocity modification resulting from upstream grains is provided to the bedload model. The temporal variability of near-bed turbulence is provided by a measured near-bed time series of velocity over a gravel bed. The distribution of pocket friction angles results as a consequence of directly calculating the initiation and cessation of motion of each particle as a result of the combination of fluid forcing and interaction with other particles. Calculations of bedload flux in a uniform boundary and simulated pocket friction angles agree favourably with previous studies.
Local homeoprotein diffusion can stabilize boundaries generated by graded positional cues.
Quiñinao, Cristóbal; Prochiantz, Alain; Touboul, Jonathan
2015-05-15
Boundary formation in the developing neuroepithelium decides on the position and size of compartments in the adult nervous system. In this study, we start from the French Flag model proposed by Lewis Wolpert, in which boundaries are formed through the combination of morphogen diffusion and of thresholds in cell responses. In contemporary terms, a response is characterized by the expression of cell-autonomous transcription factors, very often of the homeoprotein family. Theoretical studies suggest that this sole mechanism results in the formation of boundaries of imprecise shapes and positions. Alan Turing, on the other hand, proposed a model whereby two morphogens that exhibit self-activation and reciprocal inhibition, and are uniformly distributed and diffuse at different rates lead to the formation of territories of unpredictable shapes and positions but with sharp boundaries (the 'leopard spots'). Here, we have combined the two models and compared the stability of boundaries when the hypothesis of local homeoprotein intercellular diffusion is, or is not, introduced in the equations. We find that the addition of homeoprotein local diffusion leads to a dramatic stabilization of the positioning of the boundary, even when other parameters are significantly modified. This novel Turing/Wolpert combined model has thus important theoretical consequences for our understanding of the role of the intercellular diffusion of homeoproteins in the developmental robustness of and the changes that take place in the course of evolution. PMID:25968317
Comments on localized and integral localized approximations in spherical coordinates
NASA Astrophysics Data System (ADS)
Gouesbet, Gérard; Lock, James A.
2016-08-01
Localized approximation procedures are efficient ways to evaluate beam shape coefficients of laser beams, and are particularly useful when other methods are ineffective or inefficient. Comments on these procedures are, however, required in order to help researchers make correct decisions concerning their use. This paper has the flavor of a short review and takes the opportunity to attract the attention of the readers to a required refinement of terminology.
Boundary uniqueness theorems for functions whose integrals over hyperbolic discs vanish
Ochakovskaya, Oksana A
2013-02-28
Sharp conditions are found describing the admissible rate of decrease of a nontrivial function whose integrals over all hyperbolic discs with fixed radius vanish. For the first time, the boundary behaviour of the function is investigated in a neighbourhood of a single point on the boundary of the domain of definition. Bibliography: 17 titles.
Integrated Multi-Strategic Web Document Pre-Processing for Sentence and Word Boundary Detection.
ERIC Educational Resources Information Center
Shim, Junhyeok; Kim, Dongseok; Cha, Jeongwon; Lee, Gary Geunbae; Seo, Jungyun
2002-01-01
Discussion of natural language processing focuses on a multi-strategic integrated text preprocessing method for difficult problems of sentence boundary disambiguation and word boundary disambiguation of Web texts. Describes an evaluation of the method using Korean Web document collections. (Author/LRW)
Non-local sub-characteristic zones of influence in unsteady interactive boundary-layers
NASA Technical Reports Server (NTRS)
Rothmayer, A. P.
1992-01-01
The properties of incompressible, unsteady, interactive, boundary layers are examined for a model hypersonic boundary layer and internal flow past humps or, equivalently, external flow past short-scaled humps. Using a linear high frequency analysis, it is shown that the domains of dependence within the viscous sublayer may be a strong function of position within the sublayer and may be strongly influenced by the pressure displacement interaction, or the prescribed displacement condition. Detailed calculations are presented for the hypersonic boundary layer. This effect is found to carry over directly to the fully viscous problem as well as the nonlinear problem. In the fully viscous problem, the non-local character of the domains of dependence manifests itself in the sub-characteristics. Potential implications of the domain of dependence structure on finite difference computations of unsteady boundary layers are briefly discussed.
Multiple integral representation for the trigonometric SOS model with domain wall boundaries
NASA Astrophysics Data System (ADS)
Galleas, W.
2012-05-01
Using the dynamical Yang-Baxter algebra we derive a functional equation for the partition function of the trigonometric SOS model with domain wall boundary conditions. The solution of the equation is given in terms of a multiple contour integral.
Integrabilities of the long-range t-J models with twisted boundary conditions
Liu, J.T.; Wang, D.F.
1997-02-01
The integrability of the one-dimensional long-range supersymmetric t-J model has previously been established for both open systems and those closed by periodic boundary conditions through explicit construction of its integrals of motion. Recently the system has been extended to include the effect of magnetic flux, which gives rise to a closed chain with twisted boundary conditions. While the t-J model with twisted boundary conditions has been solved for the ground state and full energy spectrum, proof of its integrability has so far been lacking. In this paper we extend the proof of integrability of the long-range supersymmetric t-J model and its SU(m{vert_bar}n) generalization to include the case of twisted boundary conditions. {copyright} {ital 1997} {ital The American Physical Society}
NASA Astrophysics Data System (ADS)
Willemsen, Bram; Malcolm, Alison; Lewis, Winston
2016-03-01
In a set of problems ranging from 4-D seismic to salt boundary estimation, updates to the velocity model often have a highly localized nature. Numerical techniques for these applications such as full-waveform inversion (FWI) require an estimate of the wavefield to compute the model updates. When dealing with localized problems, it is wasteful to compute these updates in the global domain, when we only need them in our region of interest. This paper introduces a local solver that generates forward and adjoint wavefields which are, to machine precision, identical to those generated by a full-domain solver evaluated within the region of interest. This means that the local solver computes all interactions between model updates within the region of interest and the inhomogeneities in the background model outside. Because no approximations are made in the calculation of the forward and adjoint wavefields, the local solver can compute the identical gradient in the region of interest as would be computed by the more expensive full-domain solver. In this paper, the local solver is used to efficiently generate the FWI gradient at the boundary of a salt body. This gradient is then used in a level set method to automatically update the salt boundary.
Local inhomogeneities in a Robertson-Walker background. II. Flux conditions at boundary surfaces
Lake, K.
1980-12-15
Energy flux doncitions imposed on spherical boundary surfaces are examined. The zero flux restriction which is the hallmark of the standard ''Swiss cheese'' type construction, is relaxed. We discuss a class of locally inhomogeneous exact solutions to the Einstein equations which admit an effectively Newtonian accretion mode.
Topology and boundary shape optimization as an integrated design tool
NASA Technical Reports Server (NTRS)
Bendsoe, Martin Philip; Rodrigues, Helder Carrico
1990-01-01
The optimal topology of a two dimensional linear elastic body can be computed by regarding the body as a domain of the plane with a high density of material. Such an optimal topology can then be used as the basis for a shape optimization method that computes the optimal form of the boundary curves of the body. This results in an efficient and reliable design tool, which can be implemented via common FEM mesh generator and CAD type input-output facilities.
Fermionic path integrals and local anomalies
NASA Astrophysics Data System (ADS)
Roepstorff, G.
2003-05-01
No doubt, the subject of path integrals proved to be an immensely fruitful human, i.e. Feynman's idea. No wonder it is more timely than ever. Some even claim that it is the most daring, innovative and revolutionary idea since the days of Heisenberg and Bohr. It is thus likely to generate enthusiasm, if not addiction among physicists who seek simplicity together with perfection. Professor Devreese's long-lasting interest in, if not passion on the subject stems from his firm conviction that, beyond being the tool of choice, path integration provides the key to all quantum phenomena, be it in solid state, atomic, molecular or particle physics as evidenced by the impressive list of publications at the address http://lib.ua.ac.be/AB/a867.html. In this note, I review a pitfall of fermionic path integrals and a way to get around it in situations relevant to the Standard Model of particle physics.
Three-dimensional analysis of chevron-notched specimens by boundary integral method
NASA Technical Reports Server (NTRS)
Mendelson, A.; Ghosn, L.
1983-01-01
The chevron-notched short bar and short rod specimens was analyzed by the boundary integral equations method. This method makes use of boundary surface elements in obtaining the solution. The boundary integral models were composed of linear triangular and rectangular surface segments. Results were obtained for two specimens with width to thickness ratios of 1.45 and 2.00 and for different crack length to width ratios ranging from 0.4 to 0.7. Crack opening displacement and stress intensity factors determined from displacement calculations along the crack front and compliance calculations were compared with experimental values and with finite element analysis.
A moving-frame boundary-integral method for particle transport in microchannels of complex shape
NASA Astrophysics Data System (ADS)
Zinchenko, Alexander Z.; Ashley, John F.; Davis, Robert H.
2012-04-01
A new, three-dimensional algorithm is developed to accurately simulate low-Reynolds number, flow-driven motion of a neutrally buoyant spherical particle in plane-parallel microchannels of complex shape. The channel profile may consist of an arbitrary number of straight line segments with sharp corners in an arbitrary configuration. This geometry provides a suitable model for particle transport in many microfluidic devices with multiple branch bifurcations. The particle may be comparable with the narrowest channel dimensions, but is typically much smaller than the overall channel domain, which creates difficulties with a standard boundary-integral approach. To make simulations feasible, the 3D problem is solved locally in a computational cell that is smaller than the full domain and is dynamically constructed around the particle as it moves through the channel; the outer boundary conditions are provided by the 2D flow that would exist in the channel in the absence of the particle. Difficulties with particle-corner close interactions are alleviated using special iterative techniques, (near-) singularity subtractions and corner-fitted, gap-adaptive discretizations of the cell boundary. The algorithm is applied to simulate "pinched-flow fractionation" and predict how particle interactions with a narrow pinch region and sharp corners result in particle focusing and separation in the outlet according to their size. As another application, the particle motion through a T-bifurcation with sharp corners is simulated, with calculation of the particle flux partition ratio for a broad range of parameters. It is demonstrated how the particle-corner interactions can make the side branch inaccessible to particles, even for relatively strong fluid suction through this branch.
NASA Astrophysics Data System (ADS)
Yang, Zhiguo; Wang, Li-Lian; Rong, Zhijian; Wang, Bo; Zhang, Baile
2016-04-01
In this paper, we present an efficient spectral-element method (SEM) for solving general two-dimensional Helmholtz equations in anisotropic media, with particular applications in accurate simulation of polygonal invisibility cloaks, concentrators and circular rotators arisen from the field of transformation electromagnetics (TE). In practice, we adopt a transparent boundary condition (TBC) characterized by the Dirichlet-to-Neumann (DtN) map to reduce wave propagation in an unbounded domain to a bounded domain. We then introduce a semi-analytic technique to integrate the global TBC with local curvilinear elements seamlessly, which is accomplished by using a novel elemental mapping and analytic formulas for evaluating global Fourier coefficients on spectral-element grids exactly. From the perspective of TE, an invisibility cloak is devised by a singular coordinate transformation of Maxwell's equations that leads to anisotropic materials coating the cloaked region to render any object inside invisible to observers outside. An important issue resides in the imposition of appropriate conditions at the outer boundary of the cloaked region, i.e., cloaking boundary conditions (CBCs), in order to achieve perfect invisibility. Following the spirit of [48], we propose new CBCs for polygonal invisibility cloaks from the essential "pole" conditions related to singular transformations. This allows for the decoupling of the governing equations of inside and outside the cloaked regions. With this efficient spectral-element solver at our disposal, we can study the interesting phenomena when some defects and lossy or dispersive media are placed in the cloaking layer of an ideal polygonal cloak.
Probing local strain at MX(2)-metal boundaries with surface plasmon-enhanced Raman scattering.
Sun, Yinghui; Liu, Kai; Hong, Xiaoping; Chen, Michelle; Kim, Jonghwan; Shi, Sufei; Wu, Junqiao; Zettl, Alex; Wang, Feng
2014-09-10
Interactions between metal and atomically thin two-dimensional (2D) materials can exhibit interesting physical behaviors that are of both fundamental interests and technological importance. In addition to forming a metal–semiconductor Schottky junction that is critical for electrical transport, metal deposited on 2D layered materials can also generate a local mechanical strain. We investigate the local strain at the boundaries between metal (Ag, Au) nanoparticles and MX2 (M = Mo, W; X = S) layers by exploiting the strong local field enhancement at the boundary in surface plasmon-enhanced Raman scattering (SERS). We show that the local mechanical strain splits both the in-plane vibration mode E2g(1) and the out-of-plane vibration mode A1g in monolayer MoS2, and activates the in-plane mode E1g that is normally forbidden in backscattering Raman process. In comparison, the effects of mechanical strain in thicker MoS2 layers are significantly weaker. We also observe that photoluminescence from the indirect bandgap transition (when the number of layers is ≥2) is quenched with the metal deposition, while a softened and broadened shoulder peak emerges close to the original direct-bandgap transition because of the mechanical strain. The strain at metal–MX2 boundaries, which locally modifies the electronic and phonon structures of MX2, can have important effects on electrical transport through the metal–MX2 contact. PMID:25133959
Feischl, Michael; Gantner, Gregor; Praetorius, Dirk
2015-01-01
We consider the Galerkin boundary element method (BEM) for weakly-singular integral equations of the first-kind in 2D. We analyze some residual-type a posteriori error estimator which provides a lower as well as an upper bound for the unknown Galerkin BEM error. The required assumptions are weak and allow for piecewise smooth parametrizations of the boundary, local mesh-refinement, and related standard piecewise polynomials as well as NURBS. In particular, our analysis gives a first contribution to adaptive BEM in the frame of isogeometric analysis (IGABEM), for which we formulate an adaptive algorithm which steers the local mesh-refinement and the multiplicity of the knots. Numerical experiments underline the theoretical findings and show that the proposed adaptive strategy leads to optimal convergence. PMID:26085698
Shape integral method for magnetospheric shapes. [boundary layer calculations
NASA Technical Reports Server (NTRS)
Michel, F. C.
1979-01-01
A method is developed for calculating the shape of any magnetopause to arbitrarily high precision. The method uses an integral equation which is evaluated for a trial shape. The resulting values of the integral equation as a function of auxiliary variables indicate how close one is to the desired solution. A variational method can then be used to improve the trial shape. Some potential applications are briefly mentioned.
D'Elia, Marta; Perego, Mauro; Bochev, Pavel B.; Littlewood, David John
2015-12-21
We develop and analyze an optimization-based method for the coupling of nonlocal and local diffusion problems with mixed volume constraints and boundary conditions. The approach formulates the coupling as a control problem where the states are the solutions of the nonlocal and local equations, the objective is to minimize their mismatch on the overlap of the nonlocal and local domains, and the controls are virtual volume constraints and boundary conditions. When some assumptions on the kernel functions hold, we prove that the resulting optimization problem is well-posed and discuss its implementation using Sandia’s agile software components toolkit. As a result, the latter provides the groundwork for the development of engineering analysis tools, while numerical results for nonlocal diffusion in three-dimensions illustrate key properties of the optimization-based coupling method.
D'Elia, Marta; Perego, Mauro; Bochev, Pavel B.; Littlewood, David John
2015-12-21
We develop and analyze an optimization-based method for the coupling of nonlocal and local diffusion problems with mixed volume constraints and boundary conditions. The approach formulates the coupling as a control problem where the states are the solutions of the nonlocal and local equations, the objective is to minimize their mismatch on the overlap of the nonlocal and local domains, and the controls are virtual volume constraints and boundary conditions. When some assumptions on the kernel functions hold, we prove that the resulting optimization problem is well-posed and discuss its implementation using Sandia’s agile software components toolkit. As a result,more » the latter provides the groundwork for the development of engineering analysis tools, while numerical results for nonlocal diffusion in three-dimensions illustrate key properties of the optimization-based coupling method.« less
INTEGRATING A LINEAR INTERPOLATION FUNCTION ACROSS TRIANGULAR CELL BOUNDARIES
J. R. WISEMAN; J. S. BROCK
2000-04-01
Computational models of particle dynamics often exchange solution data with discretized continuum-fields using interpolation functions. These particle methods require a series expansion of the interpolation function for two purposes: numerical analysis used to establish the model's consistency and accuracy, and logical-coordinate evaluation used to locate particles within a grid. This report presents discrete-expansions for a linear interpolation function commonly used within triangular cell geometries. Discrete-expansions, unlike a Taylor's series, account for interpolation discontinuities across cell boundaries and, therefore, are valid throughout a discretized domain. Verification of linear discrete-expansions is demonstrated on a simple test problem.
Kiss, Ákos K; Rauch, Edgar F; Pécz, Béla; Szívós, János; Lábár, János L
2015-04-01
A new approach for measurement of local thickness and characterization of grain boundaries is presented. The method is embodied in a software tool that helps to find and set sample orientations useful for high-resolution transmission electron microscopic (HRTEM) examination of grain boundaries in polycrystalline thin films. The novelty is the simultaneous treatment of the two neighboring grains and orienting both grains and the boundary plane simultaneously. The same metric matrix-based formalism is used for all crystal systems. Input into the software tool includes orientation data for the grains in question, which is determined automatically for a large number of grains by the commercial ASTAR program. Grain boundaries suitable for HRTEM examination are automatically identified by our software tool. Individual boundaries are selected manually for detailed HRTEM examination from the automatically identified set. Goniometer settings needed to observe the selected boundary in HRTEM are advised by the software. Operation is demonstrated on examples from cubic and hexagonal crystal systems. PMID:25801740
NASA Astrophysics Data System (ADS)
Ivanyshyn Yaman, Olha; Le Louër, Frédérique
2016-09-01
This paper deals with the material derivative analysis of the boundary integral operators arising from the scattering theory of time-harmonic electromagnetic waves and its application to inverse problems. We present new results using the Piola transform of the boundary parametrisation to transport the integral operators on a fixed reference boundary. The transported integral operators are infinitely differentiable with respect to the parametrisations and simplified expressions of the material derivatives are obtained. Using these results, we extend a nonlinear integral equations approach developed for solving acoustic inverse obstacle scattering problems to electromagnetism. The inverse problem is formulated as a pair of nonlinear and ill-posed integral equations for the unknown boundary representing the boundary condition and the measurements, for which the iteratively regularized Gauss-Newton method can be applied. The algorithm has the interesting feature that it avoids the numerous numerical solution of boundary value problems at each iteration step. Numerical experiments are presented in the special case of star-shaped obstacles.
NASA Astrophysics Data System (ADS)
Li, Yuan; Dang, HuaYang; Xu, GuangTao; Fan, CuiYing; Zhao, MingHao
2016-08-01
The extended displacement discontinuity boundary integral equation (EDDBIE) and boundary element method is developed for the analysis of planar cracks of arbitrary shape in the isotropic plane of three-dimensional (3D) transversely isotropic thermo-magneto-electro-elastic (TMEE) media. The extended displacement discontinuities (EDDs) include conventional displacement discontinuity, electric potential discontinuity, magnetic potential discontinuity, as well as temperature discontinuity across crack faces; correspondingly, the extended stresses represent conventional stress, electric displacement, magnetic induction and heat flux. Employing a Hankel transformation, the fundamental solutions for unit point EDDs in 3D transversely isotropic TMEE media are derived. The EDDBIEs for a planar crack of arbitrary shape in the isotropic plane of a 3D transversely isotropic TMEE medium are then established. Using the boundary integral equation method, the singularities of near-crack border fields are obtained and the extended stress field intensity factors are expressed in terms of the EDDs on crack faces. According to the analogy between the EDDBIEs for an isotropic thermoelastic material and TMEE medium, an analogical solution method for crack problems of a TMEE medium is proposed for coupled multi-field loadings. Employing constant triangular elements, the EDDBIEs are discretized and numerically solved. As an application, the problems of an elliptical crack subjected to combined mechanical-electric-magnetic-thermal loadings are investigated.
Signal subspace integration for improved seizure localization
Stamoulis, Catherine; Fernández, Iván Sánchez; Chang, Bernard S.; Loddenkemper, Tobias
2012-01-01
A subspace signal processing approach is proposed for improved scalp EEG-based localization of broad-focus epileptic seizures, and estimation of the directions of source arrivals (DOA). Ictal scalp EEGs from adult and pediatric patients with broad-focus seizures were first decomposed into dominant signal modes, and signal and noise subspaces at each modal frequency, to improve the signal-to-noise ratio while preserving the original data correlation structure. Transformed (focused) modal signals were then resynthesized into wideband signals from which the number of sources and DOA were estimated. These were compared to denoised signals via principal components analysis (PCA). Coherent subspace processing performed better than PCA, significantly improved the localization of ictal EEGs and the estimation of distinct sources and corresponding DOAs. PMID:23366067
Signal subspace integration for improved seizure localization.
Stamoulis, Catherine; Fernández, Iván Sánchez; Chang, Bernard S; Loddenkemper, Tobias
2012-01-01
A subspace signal processing approach is proposed for improved scalp EEG-based localization of broad-focus epileptic seizures, and estimation of the directions of source arrivals (DOA). Ictal scalp EEGs from adult and pediatric patients with broad-focus seizures were first decomposed into dominant signal modes, and signal and noise subspaces at each modal frequency, to improve the signal-to-noise ratio while preserving the original data correlation structure. Transformed (focused) modal signals were then resynthesized into wideband signals from which the number of sources and DOA were estimated. These were compared to denoised signals via principal components analysis (PCA). Coherent subspace processing performed better than PCA, significantly improved the localization of ictal EEGs and the estimation of distinct sources and corresponding DOAs. PMID:23366067
Local Integral Estimates for Quasilinear Equations with Measure Data
Tian, Qiaoyu; Zhang, Shengzhi; Xu, Yonglin; Mu, Jia
2016-01-01
Local integral estimates as well as local nonexistence results for a class of quasilinear equations −Δpu = σP(u) + ω for p > 1 and Hessian equations Fk[−u] = σP(u) + ω were established, where σ is a nonnegative locally integrable function or, more generally, a locally finite measure, ω is a positive Radon measure, and P(u) ~ expαuβ with α > 0 and β ≥ 1 or P(u) = up−1. PMID:27294190
Local Integral Estimates for Quasilinear Equations with Measure Data.
Tian, Qiaoyu; Zhang, Shengzhi; Xu, Yonglin; Mu, Jia
2016-01-01
Local integral estimates as well as local nonexistence results for a class of quasilinear equations -Δ p u = σP(u) + ω for p > 1 and Hessian equations F k [-u] = σP(u) + ω were established, where σ is a nonnegative locally integrable function or, more generally, a locally finite measure, ω is a positive Radon measure, and P(u) ~ expαu (β) with α > 0 and β ≥ 1 or P(u) = u (p-1). PMID:27294190
Integrals of motion for one-dimensional Anderson localized systems
NASA Astrophysics Data System (ADS)
Modak, Ranjan; Mukerjee, Subroto; Yuzbashyan, Emil A.; Shastry, B. Sriram
2016-03-01
Anderson localization is known to be inevitable in one-dimension for generic disordered models. Since localization leads to Poissonian energy level statistics, we ask if localized systems possess ‘additional’ integrals of motion as well, so as to enhance the analogy with quantum integrable systems. We answer this in the affirmative in the present work. We construct a set of nontrivial integrals of motion for Anderson localized models, in terms of the original creation and annihilation operators. These are found as a power series in the hopping parameter. The recently found Type-1 Hamiltonians, which are known to be quantum integrable in a precise sense, motivate our construction. We note that these models can be viewed as disordered electron models with infinite-range hopping, where a similar series truncates at the linear order. We show that despite the infinite range hopping, all states but one are localized. We also study the conservation laws for the disorder free Aubry-Andre model, where the states are either localized or extended, depending on the strength of a coupling constant. We formulate a specific procedure for averaging over disorder, in order to examine the convergence of the power series. Using this procedure in the Aubry-Andre model, we show that integrals of motion given by our construction are well-defined in localized phase, but not so in the extended phase. Finally, we also obtain the integrals of motion for a model with interactions to lowest order in the interaction.
Wavelet-based identification of localized turbulent regions in a transitional boundary layer
NASA Astrophysics Data System (ADS)
Yoshikawa, Joe; Nishio, Yu; Izawa, Seiichiro; Fukunishi, Yu
2014-11-01
A numerical study in order to develop a method to identify localized turbulent regions in a transitional boundary layer is carried out using a wavelet transformation. Finding the onset of turbulence is quite difficult because it is not easy to distinguish the localized turbulent regions from ``non-active'' groups of vortices. The base flow with low-speed streaks is generated by placing an array of obstacles. Then a short duration jet is ejected from the wall into the low-speed streak. First, a hairpin vortex appears in the laminar boundary layer which travels downstream growing up. Downstream, localized turbulent regions appear in the boundary layer, where a lot of vortices are entangled with each other. A wavelet analysis is applied to the spatial waveforms of streamwise velocity fluctuations obtained from these two flow fields. It is shown that the hairpin vortex appears as a high amplitude spot in the wavelet spectrum, which is small in both wavenumber-wise and streamwise scales. On the other hand, the isolated turbulent region appears more wide spread in the wavenumber-wise scale. So, using this method, localized turbulent regions can be identified.
OhioLINK: Implementing Integrated Library Services across Institutional Boundaries.
ERIC Educational Resources Information Center
Hawks, Carol Pitts
1995-01-01
Discusses the implementation of the OhioLINK (Ohio Library and Information Network) system, an integrated library system linking 23 public and private academic institutions and the Ohio State Library. Topics include a history of OhioLINK; organizational structure; decision-making procedures; public relations strategies; cooperative circulation;…
On the determination of phase boundaries via thermodynamic integration across coexistence regions
Abramo, Maria Concetta Caccamo, Carlo Costa, Dino Giaquinta, Paolo V. Malescio, Gianpietro Munaò, Gianmarco; Prestipino, Santi
2015-06-07
Specialized Monte Carlo methods are nowadays routinely employed, in combination with thermodynamic integration (TI), to locate phase boundaries of classical many-particle systems. This is especially useful for the fluid-solid transition, where a critical point does not exist and both phases may notoriously go deeply metastable. Using the Lennard-Jones model for demonstration, we hereby investigate on the alternate possibility of tracing reasonably accurate transition lines directly by integrating the pressure equation of state computed in a canonical-ensemble simulation with local moves. The recourse to this method would become a necessity when the stable crystal structure is not known. We show that, rather counterintuitively, metastability problems can be alleviated by reducing (rather than increasing) the size of the system. In particular, the location of liquid-vapor coexistence can exactly be predicted by just TI. On the contrary, TI badly fails in the solid-liquid region, where a better assessment (to within 10% accuracy) of the coexistence pressure can be made by following the expansion, until melting, of the defective solid which has previously emerged from the decay of the metastable liquid.
Seismic response of laterally inhomogeneous geological region by boundary integral equations
NASA Astrophysics Data System (ADS)
Parvanova, S.; Dineva, P.; Fontara, I.-K.; Wuttke, F.
2015-07-01
The proposed study deals with synthesis of seismograms by BIEM (boundary integral equation method) taking into account all three base components-seismic source, wave path and local region of interest. Consider a laterally inhomogeneous geological profile situated in a half-plane with non-parallel layers. Seismic load is time-harmonic or transient in time. It is presented by incident SH wave or wave radiating from an embedded line seismic source. Two types of lateral inhomogeneities with arbitrary shape and located in the inhomogeneous half-plane are considered: (i) free-surface relief as a canyon or a hill; (ii) alluvial basin with properties different from those of the layered half-plane. The computational tool is BIEM based on the frequency-dependent elastodynamic fundamental solutions. A relation between displacements and tractions along the free surface and arbitrary interface of the soil stratum is derived, which is applicable for arbitrary geometry of the interfaces between soil layers. Validation and convergence study is presented. All simulations reveal the sensitivity of the synthetic seismic signals on the type and characteristics of the seismic time-harmonic or transient load, on the wave path inhomogeneity and on the specific geotechnical properties of the local geological region.
NASA Technical Reports Server (NTRS)
Choudhari, Meelan; Street, Craig L.
1991-01-01
Previous theoretical work on the boundary layer receptivity problem has utilized large Reynolds number asymptotic theories, thus being limited to a narrow part of the frequency - Reynolds number domain. An alternative approach is presented for the prediction of localized instability generation which has a general applicability, and also accounts for finite Reynolds number effects. This approach is illustrated for the case of Tollmien-Schlichting wave generation in a Blasius boundary layer due to the interaction of a free stream acoustic wave with a region of short scale variation in the surface boundary condition. The specific types of wall inhomogeneities studied are: regions of short scale variations in wall suction, wall admittance, and wall geometry (roughness). Extensive comparison is made between the results of the finite Reynolds number approach and previous asymptotic predictions, which also suggests an alternative way of using the latter at Reynolds numbers of interest in practice.
Boundary integral equation Neumann-to-Dirichlet map method for gratings in conical diffraction.
Wu, Yumao; Lu, Ya Yan
2011-06-01
Boundary integral equation methods for diffraction gratings are particularly suitable for gratings with complicated material interfaces but are difficult to implement due to the quasi-periodic Green's function and the singular integrals at the corners. In this paper, the boundary integral equation Neumann-to-Dirichlet map method for in-plane diffraction problems of gratings [Y. Wu and Y. Y. Lu, J. Opt. Soc. Am. A26, 2444 (2009)] is extended to conical diffraction problems. The method uses boundary integral equations to calculate the so-called Neumann-to-Dirichlet maps for homogeneous subdomains of the grating, so that the quasi-periodic Green's functions can be avoided. Since wave field components are coupled on material interfaces with the involvement of tangential derivatives, a least squares polynomial approximation technique is developed to evaluate tangential derivatives along these interfaces for conical diffraction problems. Numerical examples indicate that the method performs equally well for dielectric or metallic gratings. PMID:21643404
NASA Astrophysics Data System (ADS)
Bermúdez, María; Neal, Jeffrey C.; Bates, Paul D.; Coxon, Gemma; Freer, Jim E.; Cea, Luis; Puertas, Jerónimo
2016-04-01
Flood inundation models require appropriate boundary conditions to be specified at the limits of the domain, which commonly consist of upstream flow rate and downstream water level. These data are usually acquired from gauging stations on the river network where measured water levels are converted to discharge via a rating curve. Derived streamflow estimates are therefore subject to uncertainties in this rating curve, including extrapolating beyond the maximum observed ratings magnitude. In addition, the limited number of gauges in reach-scale studies often requires flow to be routed from the nearest upstream gauge to the boundary of the model domain. This introduces additional uncertainty, derived not only from the flow routing method used, but also from the additional lateral rainfall-runoff contributions downstream of the gauging point. Although generally assumed to have a minor impact on discharge in fluvial flood modeling, this local hydrological input may become important in a sparse gauge network or in events with significant local rainfall. In this study, a method to incorporate rating curve uncertainty and the local rainfall-runoff dynamics into the predictions of a reach-scale flood inundation model is proposed. Discharge uncertainty bounds are generated by applying a non-parametric local weighted regression approach to stage-discharge measurements for two gauging stations, while measured rainfall downstream from these locations is cascaded into a hydrological model to quantify additional inflows along the main channel. A regional simplified-physics hydraulic model is then applied to combine these inputs and generate an ensemble of discharge and water elevation time series at the boundaries of a local-scale high complexity hydraulic model. Finally, the effect of these rainfall dynamics and uncertain boundary conditions are evaluated on the local-scale model. Improvements in model performance when incorporating these processes are quantified using observed
Huang, Kuo-Feng; Liao, Jung-Wei; Hsieh, Cheng-Yu; Wang, Liang-Wei; Huang, Yen-Chun; Wen, Wei-Chih; Chang, Mu-Tung; Lo, Shen-Chuan; Yuan, Jun; Lin, Hsiu-Hau; Lai, Chih-Huang
2015-01-01
Magnetic patterning, with designed spatial profile of the desired magnetic properties, has been a rising challenge for developing magnetic devices at nanoscale. Most existing methods rely on locally modifying magnetic anisotropy energy or saturation magnetization, and thus post stringent constraints on the adaptability in diverse applications. We propose an alternative route for magnetic patterning: by manipulating the local intergranular exchange coupling to tune lateral magnetic properties. As demonstration, the grain boundary structure of Co/Pt multilayers is engineered by thermal treatment, where the stress state of the multilayers and thus the intergranular exchange coupling can be modified. With Ag passivation layers on top of the Co/Pt multilayers, we can hinder the stress relaxation and grain boundary modification. Combining the pre-patterned Ag passivation layer with thermal treatment, we can design spatial variations of the magnetic properties by tuning the intergranular exchange coupling, which diversifies the magnetic patterning process and extends its feasibility for varieties of new devices. PMID:26156786
NASA Astrophysics Data System (ADS)
Chang, A. H.; Yee, K. S.; Prodan, J.
1992-08-01
To obtain an accurate solution in the method of moments (MM), it is vital that an appropriate integral equation be used. In solving the problem of scattering from bodies of revolution (BOR) with anisotropic surface impedance boundary conditions (IBC), different answers may result from seemingly minor differences in the integral equation formulation adopted. In this communication different types of integral equations are compared with one another when they are applied to bodies of revolution.
Singularity Preserving Numerical Methods for Boundary Integral Equations
NASA Technical Reports Server (NTRS)
Kaneko, Hideaki (Principal Investigator)
1996-01-01
In the past twelve months (May 8, 1995 - May 8, 1996), under the cooperative agreement with Division of Multidisciplinary Optimization at NASA Langley, we have accomplished the following five projects: a note on the finite element method with singular basis functions; numerical quadrature for weakly singular integrals; superconvergence of degenerate kernel method; superconvergence of the iterated collocation method for Hammersteion equations; and singularity preserving Galerkin method for Hammerstein equations with logarithmic kernel. This final report consists of five papers describing these projects. Each project is preceeded by a brief abstract.
Parameter estimation for boundary value problems by integral equations of the second kind
NASA Technical Reports Server (NTRS)
Kojima, Fumio
1988-01-01
This paper is concerned with the parameter estimation for boundary integral equations of the second kind. The parameter estimation technique through use of the spline collocation method is proposed. Based on the compactness assumption imposed on the parameter space, the convergence analysis for the numerical method of parameter estimation is discussed. The results obtained here are applied to a boundary parameter estimation for 2-D elliptic systems.
NASA Technical Reports Server (NTRS)
Tetervin, Neal; Lin, Chia Chiao
1951-01-01
A general integral form of the boundary-layer equation, valid for either laminar or turbulent incompressible boundary-layer flow, is derived. By using the experimental finding that all velocity profiles of the turbulent boundary layer form essentially a single-parameter family, the general equation is changed to an equation for the space rate of change of the velocity-profile shape parameter. The lack of precise knowledge concerning the surface shear and the distribution of the shearing stress across turbulent boundary layers prevented the attainment of a reliable method for calculating the behavior of turbulent boundary layers.
Dynamical many-body localization in an integrable model
NASA Astrophysics Data System (ADS)
Keser, Aydin Cem; Ganeshan, Sriram; Refael, Gil; Galitski, Victor
2016-08-01
We investigate dynamical many-body localization and delocalization in an integrable system of periodically-kicked, interacting linear rotors. The linear-in-momentum Hamiltonian makes the Floquet evolution operator analytically tractable for arbitrary interactions. One of the hallmarks of this model is that depending on certain parameters, it manifests both localization and delocalization in momentum space. We present a set of "emergent" integrals of motion, which can serve as a fundamental diagnostic of dynamical localization in the interacting case. We also propose an experimental scheme, involving voltage-biased Josephson junctions, to realize such many-body kicked models.
Analytical solution of boundary integral equations for 2-D steady linear wave problems
NASA Astrophysics Data System (ADS)
Chuang, J. M.
2005-10-01
Based on the Fourier transform, the analytical solution of boundary integral equations formulated for the complex velocity of a 2-D steady linear surface flow is derived. It has been found that before the radiation condition is imposed, free waves appear both far upstream and downstream. In order to cancel the free waves in far upstream regions, the eigensolution of a specific eigenvalue, which satisfies the homogeneous boundary integral equation, is found and superposed to the analytical solution. An example, a submerged vortex, is used to demonstrate the derived analytical solution. Furthermore, an analytical approach to imposing the radiation condition in the numerical solution of boundary integral equations for 2-D steady linear wave problems is proposed.
A finite element-boundary integral method for cavities in a circular cylinder
NASA Technical Reports Server (NTRS)
Kempel, Leo C.; Volakis, John L.
1992-01-01
Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. However, due to a lack of rigorous mathematical models for conformal antenna arrays, antenna designers resort to measurement and planar antenna concepts for designing non-planar conformal antennas. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. We extend this formulation to conformal arrays on large metallic cylinders. In this report, we develop the mathematical formulation. In particular, we discuss the shape functions, the resulting finite elements and the boundary integral equations, and the solution of the conformal finite element-boundary integral system. Some validation results are presented and we further show how this formulation can be applied with minimal computational and memory resources.
Application of the method of integral relations to laminar boundary layers in three dimensions
NASA Technical Reports Server (NTRS)
Holt, M.; Modarress, D.
1977-01-01
The method of integral relations is extended to general three-dimensional compressible laminar boundary layer flows. The transformation employed to transform the basic three-dimensional compressible boundary layer equations into quasi-incompressible form is an extension of the Howarth transformation. The resulting system of differential equations is integrated numerically by the method of integral relations as proposed by Dorodnitsyn. To demonstrate the accuracy of the method, it is applied to calculation of the parabolic flow over a flat plate and the boundary flow over an infinite yawed cylinder, for which solutions are known. It is then applied to the flow over a flat plate disturbed by a cylinder normal to the plate, for which a finite-difference solution is available for comparison. It is finally applied to calculating the crossflow velocity variation for supersonic flow over a swept wedge.
A spectral boundary integral equation method for the 2-D Helmholtz equation
NASA Technical Reports Server (NTRS)
Hu, Fang Q.
1994-01-01
In this paper, we present a new numerical formulation of solving the boundary integral equations reformulated from the Helmholtz equation. The boundaries of the problems are assumed to be smooth closed contours. The solution on the boundary is treated as a periodic function, which is in turn approximated by a truncated Fourier series. A Fourier collocation method is followed in which the boundary integral equation is transformed into a system of algebraic equations. It is shown that in order to achieve spectral accuracy for the numerical formulation, the nonsmoothness of the integral kernels, associated with the Helmholtz equation, must be carefully removed. The emphasis of the paper is on investigating the essential elements of removing the nonsmoothness of the integral kernels in the spectral implementation. The present method is robust for a general boundary contour. Aspects of efficient implementation of the method using FFT are also discussed. A numerical example of wave scattering is given in which the exponential accuracy of the present numerical method is demonstrated.
Magnetic local time variation and scaling of poleward auroral boundary dynamics
NASA Astrophysics Data System (ADS)
Longden, N.; Chisham, G.; Freeman, M. P.
2014-12-01
The balance of dayside and nightside reconnection processes within the Earth's magnetosphere and its effect on the amount of open magnetic flux threading the ionosphere is well understood in terms of the expanding-contracting polar cap model. However, the nature and character of the consequential fluctuations in the polar cap boundary are poorly understood. By using the poleward auroral luminosity boundary (PALB), as measured by the FUV instrument of the IMAGE spacecraft, as a proxy for the polar cap boundary, we have studied the motion of this boundary for more than 2 years across the complete range of magnetic local time. Our results show that the dayside PALB dynamics are broadly self-similar on timescales of 12 min to 6 h and appear to be monofractal. Similarity with the characteristics of solar wind and interplanetary magnetic field variability suggests that this dayside monofractal behavior is predominantly inherited from the solar wind via the reconnection process. The nightside PALB dynamics exhibit scale-free behavior at intermediate time scales (12-90 min) and appear to be multifractal. We propose that this character is a result of the intermittent multifractal structure of magnetotail reconnection.
Integrating Sustainability into the Curriculum: Crossing Disciplinary Boundaries
NASA Astrophysics Data System (ADS)
Pushnik, J.
2012-12-01
The next generation will confront an increased number of global issues that interface the complexities of socioeconomic perspectives, environmental stability, poverty and development. Recently California State University Chico undertook a general education reform, providing a unique opportunity to craft a general education pathway to prepare students for these challenges by focusing a curriculum on sustainability. The Sustainability Pathway emphasizes a system thinking approach to help students understand and be able to address a set of problems involving the biosphere processes, human institutions and the economic vitality. The curriculum intentionally integrates courses from across the disciplines of natural sciences, social sciences, agriculture, engineering, economics, arts and humanities into a central focused theme of sustainability. The diverse backgrounds and academic focus of the participating faculty has necessitate the development of a common language and a cohesion within the curriculum. To address these needs a faculty learning community (FLC) was established to build on a common set of case studies. Three regional environmental water related issues were selected that had demonstrable socioeconomic, equity/ethical dimensions and environmental consequences. These case studies are Klamath River basin in northern California, the Bay-Delta project in the central part of the state and the Sultan Sea in southern California. Members of the FLC has contributed a perspective from their academic discipline which includes proposed reading lists, web based resources and PowerPoint presentations which are housed in common web- based resource repository. The pedagogical rational is to create linkages and cohesion among the courses in the curriculum by iteratively examining these case studies as basis for development of a multidisciplinary perspective as students progress through their general education.
Blow-up problems for the heat equation with a local nonlinear Neumann boundary condition
NASA Astrophysics Data System (ADS)
Yang, Xin; Zhou, Zhengfang
2016-09-01
This paper estimates the blow-up time for the heat equation ut = Δu with a local nonlinear Neumann boundary condition: The normal derivative ∂ u / ∂ n =uq on Γ1, one piece of the boundary, while on the rest part of the boundary, ∂ u / ∂ n = 0. The motivation of the study is the partial damage to the insulation on the surface of space shuttles caused by high speed flying subjects. We show the finite time blow-up of the solution and estimate both upper and lower bounds of the blow-up time in terms of the area of Γ1. In many other work, they need the convexity of the domain Ω and only consider the problem with Γ1 = ∂ Ω. In this paper, we remove the convexity condition and only require ∂Ω to be C2. In addition, we deal with the local nonlinearity, namely Γ1 can be just part of ∂Ω.
Integrals of motion for one-dimensional Anderson localized systems
Modak, Ranjan; Mukerjee, Subroto; Yuzbashyan, Emil A.; Shastry, B. Sriram
2016-03-02
Anderson localization is known to be inevitable in one-dimension for generic disordered models. Since localization leads to Poissonian energy level statistics, we ask if localized systems possess ‘additional’ integrals of motion as well, so as to enhance the analogy with quantum integrable systems. Weanswer this in the affirmative in the present work. We construct a set of nontrivial integrals of motion for Anderson localized models, in terms of the original creation and annihilation operators. These are found as a power series in the hopping parameter. The recently found Type-1 Hamiltonians, which are known to be quantum integrable in a precisemore » sense, motivate our construction.Wenote that these models can be viewed as disordered electron models with infinite-range hopping, where a similar series truncates at the linear order.Weshow that despite the infinite range hopping, all states but one are localized.Wealso study the conservation laws for the disorder free Aubry–Andre model, where the states are either localized or extended, depending on the strength of a coupling constant.Weformulate a specific procedure for averaging over disorder, in order to examine the convergence of the power series. Using this procedure in the Aubry–Andre model, we show that integrals of motion given by our construction are well-defined in localized phase, but not so in the extended phase. Lastly, we also obtain the integrals of motion for a model with interactions to lowest order in the interaction.« less
Salient object detection based on discriminative boundary and multiple cues integration
NASA Astrophysics Data System (ADS)
Jiang, Qingzhu; Wu, Zemin; Tian, Chang; Liu, Tao; Zeng, Mingyong; Hu, Lei
2016-01-01
In recent years, many saliency models have achieved good performance by taking the image boundary as the background prior. However, if all boundaries of an image are equally and artificially selected as background, misjudgment may happen when the object touches the boundary. We propose an algorithm called weighted contrast optimization based on discriminative boundary (wCODB). First, a background estimation model is reliably constructed through discriminating each boundary via Hausdorff distance. Second, the background-only weighted contrast is improved by fore-background weighted contrast, which is optimized through weight-adjustable optimization framework. Then to objectively estimate the quality of a saliency map, a simple but effective metric called spatial distribution of saliency map and mean saliency in covered window ratio (MSR) is designed. Finally, in order to further promote the detection result using MSR as the weight, we propose a saliency fusion framework to integrate three other cues-uniqueness, distribution, and coherence from three representative methods into our wCODB model. Extensive experiments on six public datasets demonstrate that our wCODB performs favorably against most of the methods based on boundary, and the integrated result outperforms all state-of-the-art methods.
A Formulation of Asymptotic and Exact Boundary Conditions Using Local Operators
NASA Technical Reports Server (NTRS)
Hagstrom, T.; Hariharan, S. I.
1998-01-01
In this paper we describe a systematic approach for constructing asymptotic boundary conditions for isotropic wave-like equations using local operators. The conditions take a recursive form with increasing order of accuracy. In three dimensions the recursion terminates and the resulting conditions are exact for solutions which are described by finite combinations of angular spherical harmonics. First, we develop the expansion for the two-dimensional wave equation and construct a sequence of easily implementable boundary conditions. We show that in three dimensions and analogous conditions are again easily implementable in addition to being exact. Also, we provide extensions of these ideas to hyperbolic systems. Namely, Maxwell's equations for TM waves are used to demonstrate the construction. Finally, we provide numerical examples to demonstrate the effectiveness of these conditions for a model problem governed by the wave equation.
Brown, Phil
2013-06-01
This article reviews the personal and professional processes of developing an interdisciplinary approach to understanding the complex issues of environmental health in their community, political-economic, social science, and scientific contexts. This interdisciplinary approach includes a synthesis of research, policy work, and advocacy. To examine multiple forms of interdisciplinarity, I examine pathways of integrating medical and environmental sociology via three challenges to the boundaries of traditional research: (1) crossing the boundaries of medical and environmental sociology, (2) linking social science and environmental health science, and (3) crossing the boundary of research and advocacy. These boundary crossings are discussed in light of conceptual and theoretical developments of popular epidemiology, contested illnesses, and health social movements. This interdisciplinary work offers a more comprehensive sociological lens for understanding complex problems and a practical ability to join with scientists, activists, and officials to meet public health needs for amelioration and prevention of environmental health threats. PMID:23598897
NASA Technical Reports Server (NTRS)
Patel, D. K.; Czarnecki, K. R.
1977-01-01
An investigation was made to determine the feasibility of using a boundary layer integral method to study the separation of a turbulent boundary layer on a two dimensional ramp at supersonic speeds. The numerical calculations were made for a free stream Mach number of 3, a Reynolds number of 10 million, and over a ramp angle range from 0 deg to 30 deg. For ramp angles where no flow separation was indicated, theoretical calculations were in reasonable agreement with experimental data except for a somewhat belated rise in pressure. For larger ramp angles, where separation was present, the investigation produced results that were not in agreement with experiment or with results calculated by time dependent Navier-Stokes methods. This apparently was true because no provision had been made for a proper shock boundary layer interaction where strong normal pressure gradients are induced within the boundary layer under the shock independent of surface curvature effects.
Bardhan, J. P.; Mathematics and Computer Science
2008-10-14
The importance of molecular electrostatic interactions in aqueous solution has motivated extensive research into physical models and numerical methods for their estimation. The computational costs associated with simulations that include many explicit water molecules have driven the development of implicit-solvent models, with generalized-Born (GB) models among the most popular of these. In this paper, we analyze a boundary-integral equation interpretation for the Coulomb-field approximation (CFA), which plays a central role in most GB models. This interpretation offers new insights into the nature of the CFA, which traditionally has been assessed using only a single point charge in the solute. The boundary-integral interpretation of the CFA allows the use of multiple point charges, or even continuous charge distributions, leading naturally to methods that eliminate the interpolation inaccuracies associated with the Still equation. This approach, which we call boundary-integral-based electrostatic estimation by the CFA (BIBEE/CFA), is most accurate when the molecular charge distribution generates a smooth normal displacement field at the solute-solvent boundary, and CFA-based GB methods perform similarly. Conversely, both methods are least accurate for charge distributions that give rise to rapidly varying or highly localized normal displacement fields. Supporting this analysis are comparisons of the reaction-potential matrices calculated using GB methods and boundary-element-method (BEM) simulations. An approximation similar to BIBEE/CFA exhibits complementary behavior, with superior accuracy for charge distributions that generate rapidly varying normal fields and poorer accuracy for distributions that produce smooth fields. This approximation, BIBEE by preconditioning (BIBEE/P), essentially generates initial guesses for preconditioned Krylov-subspace iterative BEMs. Thus, iterative refinement of the BIBEE/P results recovers the BEM solution; excellent agreement
Calculation of three-dimensional boundary layers on rotor blades using integral methods
Karimipanah, M.T.; Olsson, E. )
1993-04-01
The important effects of rotation and compressibility on rotor blade boundary layers are theoretically investigated. The calculations are based on the momentum integral method and results from calculations of a transonic compressor rotor are presented. Influence of rotation is shown by comparing the incompressible rotating flow with the stationary one. Influence of compressibility is shown by comparing the compressible rotating flow with the incompressible rotating one. Two computer codes for three-dimensional laminar and turbulent boundary layers, originally developed by SSPA Maritime Consulting AB, have been further developed by introducing rotation and compressibility terms into the boundary layer equations. The effect of rotation and compressibility on the transition have been studied. The Coriolis and centrifugal forces that contribute to the development of the boundary layers and influence its behavior generate crosswise flow inside the blade boundary layers, the magnitude of which depends upon the angular velocity of the rotor and the rotor geometry. The calculations show the influence of rotation and compressibility on the boundary layer parameters. Momentum thickness and shape factor increase with increasing rotation and decrease when compressible flow is taken into account. For skin friction such effects have inverse influences. The different boundary layer parameters behave similarly on the suction and pressure sides with the exception of the crossflow angle, the crosswise momentum thickness, and the skin friction factor. The codes use a nearly orthogonal streamline coordinate system, which is fixed to the blade surface and rotates with the blade.
NASA Astrophysics Data System (ADS)
Jonas, Matthias; Ometto, Jean Pierre; Batistella, Mateus; Franklin, Oskar; Hall, Marianne; Lapola, David M.; Moran, Emilio F.; Tramberend, Sylvia; Queiroz, Bernardo Lanza; Schaffartzik, Anke; Shvidenko, Anatoly; Nilsson, Sten B.; Nobre, Carlos A.
2014-08-01
Resolving challenges related to the sustainability of natural capital and ecosystem services is an urgent issue. No roadmap on reaching sustainability exists; and the kind of sustainable land use required in a world that acknowledges both multiple environmental boundaries and local human well-being presents a quandary. In this commentary, we argue that a new globally consistent and expandable systems-analytical framework is needed to guide and facilitate decision making on sustainability from the planetary to the local level, and vice versa. This framework would strive to link a multitude of Earth system processes and targets; it would give preference to systemic insight over data complexity through being highly explicit in spatiotemporal terms. Its strength would lie in its ability to help scientists uncover and explore potential, and even unexpected, interactions between Earth's subsystems with planetary environmental boundaries and socioeconomic constraints coming into play. Equally importantly, such a framework would allow countries such as Brazil, a case study in this commentary, to understand domestic or even local sustainability measures within a global perspective and to optimize them accordingly.
Histone Crosstalk Directed by H2B Ubiquitination Is Required for Chromatin Boundary Integrity
Ma, Meiji Kit-Wan; Heath, Carol; Hair, Alan; West, Adam G.
2011-01-01
Genomic maps of chromatin modifications have provided evidence for the partitioning of genomes into domains of distinct chromatin states, which assist coordinated gene regulation. The maintenance of chromatin domain integrity can require the setting of boundaries. The HS4 insulator element marks the 3′ boundary of a heterochromatin region located upstream of the chicken β-globin gene cluster. Here we show that HS4 recruits the E3 ligase RNF20/BRE1A to mediate H2B mono-ubiquitination (H2Bub1) at this insulator. Knockdown experiments show that RNF20 is required for H2Bub1 and processive H3K4 methylation. Depletion of RNF20 results in a collapse of the active histone modification signature at the HS4 chromatin boundary, where H2Bub1, H3K4 methylation, and hyperacetylation of H3, H4, and H2A.Z are rapidly lost. A remarkably similar set of events occurs at the HSA/HSB regulatory elements of the FOLR1 gene, which mark the 5′ boundary of the same heterochromatin region. We find that persistent H2Bub1 at the HSA/HSB and HS4 elements is required for chromatin boundary integrity. The loss of boundary function leads to the sequential spreading of H3K9me2, H3K9me3, and H4K20me3 over the entire 50 kb FOLR1 and β-globin region and silencing of FOLR1 expression. These findings show that the HSA/HSB and HS4 boundary elements direct a cascade of active histone modifications that defend the FOLR1 and β-globin gene loci from the pervasive encroachment of an adjacent heterochromatin domain. We propose that many gene loci employ H2Bub1-dependent boundaries to prevent heterochromatin spreading. PMID:21811414
ERIC Educational Resources Information Center
Kao, Gloria Yi-Ming; Lin, Sunny S. J.; Sun, Chuen-Tsai
2008-01-01
The authors address the role of computer support for building conceptual self-awareness--that is, enabling students to think outside of concept boundaries in hope of enhancing creative potential. Based on meta-cognition theory, we developed an integrated concept mapping system (ICMSys) to improve users' conceptual self-awareness in addition to…
Chen, Ke
1996-12-31
We study various preconditioning techniques for the iterative solution of boundary integral equations, and aim to provide a theory for a class of sparse preconditioners. Two related ideas are explored here: singularity separation and inverse approximation. Our preliminary conclusion is that singularity separation based preconditioners perform better than approximate inverse based while it is desirable to have both features.
Tarasov, Yu.V. Shostenko, L.D.
2015-05-15
A unified theory for the conductance of an infinitely long multimode quantum wire whose finite segment has randomly rough lateral boundaries is developed. It enables one to rigorously take account of all feasible mechanisms of wave scattering, both related to boundary roughness and to contacts between the wire rough section and the perfect leads within the same technical frameworks. The rough part of the conducting wire is shown to act as a mode-specific randomly modulated effective potential barrier whose height is governed essentially by the asperity slope. The mean height of the barrier, which is proportional to the average slope squared, specifies the number of conducting channels. Under relatively small asperity amplitude this number can take on arbitrary small, up to zero, values if the asperities are sufficiently sharp. The consecutive channel cut-off that arises when the asperity sharpness increases can be regarded as a kind of localization, which is not related to the disorder per se but rather is of entropic or (equivalently) geometric origin. The fluctuating part of the effective barrier results in two fundamentally different types of guided wave scattering, viz., inter- and intramode scattering. The intermode scattering is shown to be for the most part very strong except in the cases of (a) extremely smooth asperities, (b) excessively small length of the corrugated segment, and (c) the asperities sharp enough for only one conducting channel to remain in the wire. Under strong intermode scattering, a new set of conducting channels develops in the corrugated waveguide, which have the form of asymptotically decoupled extended modes subject to individual solely intramode random potentials. In view of this fact, two transport regimes only are realizable in randomly corrugated multimode waveguides, specifically, the ballistic and the localized regime, the latter characteristic of one-dimensional random systems. Two kinds of localization are thus shown to
Non-local susceptibility of the wire medium in the spatial domain considering material boundaries
NASA Astrophysics Data System (ADS)
Hanson, George W.; Silveirinha, Mário G.; Burghignoli, Paolo; Yakovlev, Alexander B.
2013-08-01
We show that the non-local susceptibility \\bar{\\boldsymbol{\\chi}}\\left (\\mathbf{r},\\mathbf{r}^{\\prime }\\right ) for a non-translationally invariant homogenized wire medium is, modulo a constant, given by a simple Green function related to the material geometry. We also show that two previous methods for solving wave interaction problems for bounded wire media (wave expansion method and transport equation) are equivalent to each other, and to a third method involving particle reflection at the boundary. We discuss the importance of the dead layer or virtual interface, and find it to be analogous to the excitonic semiconductor case. Several examples are provided to clarify the material.
NASA Astrophysics Data System (ADS)
Slavin, Jonathan D.
2016-03-01
The outer boundary conditions of the heliosphere are set by the circumheliospheric interstellar medium, which is part of the Local Interstellar Cloud (LIC). In particular the ram pressure, ionization and magnetic field strength are important for determining the size and shape of the heliosphere. The in situ as well as line of sight data indicate that the LIC is a warm, partially ionized cloud. We discuss the observational evidence on the nature of the LIC and theoretical models that explain its temperature and ionization.
N{sup ±}-integrals and boundary values of Cauchy-type integrals of finite measures
Aliev, R. A. E-mail: alievrashid@box.az
2014-07-31
Let Γ be a simple closed Lyapunov contour with finite complex measure ν, and let G{sup +} be the bounded and G{sup −} the unbounded domains with boundary Γ. Using new notions (so-called N-integration and N{sup +}- and N{sup −}-integrals), we prove that the Cauchy-type integrals F{sup +}(z), z∈G{sup +}, and F{sup −}(z), z∈G{sup −}, of ν are Cauchy N{sup +}- and N{sup −}-integrals, respectively. In the proof of the corresponding results, the additivity property and the validity of the change-of-variable formula for the N{sup +}- and N{sup −}-integrals play an essential role. Bibliography: 21 titles. (paper)
Local isotropy in distorted turbulent boundary layers at high Reynolds number
NASA Technical Reports Server (NTRS)
Saddoughi, Seyed G.
1993-01-01
This is a report on the continuation of our experimental investigations of the hypothesis of local isotropy in shear flows. This hypothesis, which states that at sufficiently high Reynolds numbers the small-scale structures of turbulent motions are independent of large-scale structures and mean deformations, has been used in theoretical studies of turbulence and computational methods such as large-eddy simulation. Since Kolmogorov proposed his theory, there have been many experiments, conducted in wakes, jets, mixing layers, a tidal channel, and atmospheric and laboratory boundary layers, in which attempts have been made to verify - or refute - the local-isotropy hypothesis. However, a review of the literature over the last five decades indicated that, despite all these experiments in shear flows, there was no consensus in the scientific community regarding this hypothesis, and, therefore, it seemed worthwhile to undertake a fresh experimental investigation into this question.
NASA Astrophysics Data System (ADS)
Rogowitz, Anna; Grasemann, Bernhard; Clancy White, Joseph
2015-04-01
Strain localization in monomineralic rocks is often associated with brittle precursors, resulting in stress and strain concentration, followed by grain size reduction and activation of grain-size-sensitive deformation mechanisms such as diffusion creep, grain boundary sliding and cataclastic flow. The aforementioned mechanisms typically tend to produce a random crystallographic orientation or a decrease in intensity of a pre-existing texture. However, reports of fine grained polycrystalline materials showing a preferred crystallographic orientation indicate a need for subsequent grain re-organization by either static annealing or the activation of additional deformation mechanisms in conjunction with grain boundary sliding. We present observations from an almost pure calcite marble layer from Syros Island (Cyclades, Greece) deformed in lower greenschist facies conditions. The presence of a crack (i.e. cross-cutting element) that rotated during shear resulted in the formation of a flanking structure. At the location of maximum displacement (120 cm) along the cross-cutting element, the marble is extremely fine grained (3 µm) leading to anticipation of deformation by grain-size-sensitive mechanisms. Detailed microstructural analysis of the highly strained (80 < gamma < 1000) calcite ultramylonite by optical microscopy, electron backscatter diffraction and scanning transmission electron microscopy show that recrystallization by bulging results in small, strain-free grains. The change in grain size appears to be concomitant with increased activity of independent grain boundary sliding as indicated by a random misorientation angle distribution. At the same time, dislocation multiplication through Frank-Read sources produces high mean dislocation density (~ 5x10^13 m^-2) as well as a weak primary CPO; the latter all argue that grain boundary sliding was accommodated by dislocation activity. Theoretical and experimental determined relationships (paleowattmeter
NASA Technical Reports Server (NTRS)
Lakin, W. D.
1986-01-01
Integrating and differentiating matrices allow the numerical integration and differential of functions whose values are known at points of a discrete grid. Previous derivations of these matrices were restricted to one dimensional grids or to rectangular grids with uniform spacing in at least one direction. Integrating and differentiating matrices were developed for grids with nonuniform spacing in both directions. The use of these matrices as operators to reformulate boundary value problems on rectangular domains as matrix problems for a finite dimensional solution vector is considered. The method requires nonuniform grids which include near boundary points. An eigenvalue problem for the transverse vibrations of a simply supported rectangular plate is solved to illustrate the method.
Daeva, S.G.; Setukha, A.V.
2015-03-10
A numerical method for solving a problem of diffraction of acoustic waves by system of solid and thin objects based on the reduction the problem to a boundary integral equation in which the integral is understood in the sense of finite Hadamard value is proposed. To solve this equation we applied piecewise constant approximations and collocation methods numerical scheme. The difference between the constructed scheme and earlier known is in obtaining approximate analytical expressions to appearing system of linear equations coefficients by separating the main part of the kernel integral operator. The proposed numerical scheme is tested on the solution of the model problem of diffraction of an acoustic wave by inelastic sphere.
Living Authors, Living Stories: Integrating Local Authors into Our Curriculum
ERIC Educational Resources Information Center
Newman, Beatrice Mendez
2009-01-01
Keeping literature classrooms vibrant, energized, and current can require supreme pedagogical effort, especially in light of students' sometimes pointed disinterest in traditional and/or canonical texts. Integrating local authors into a standard curriculum can be an effective strategy for invigorating students' interest in literature and helping…
STATE AND LOCAL AREA INTEGRATED TELEPHONE SURVEY (SLAITS)
The State and Local Area Integrated Telephone Survey (SLAITS) is a telephone interview mechanism that employs the sampling frame of the National Immunization Survey. The purpose of SLAITS is to provide high quality health and welfare-related data on individuals and families at th...
A GPU-accelerated direct-sum boundary integral Poisson-Boltzmann solver
NASA Astrophysics Data System (ADS)
Geng, Weihua; Jacob, Ferosh
2013-06-01
In this paper, we present a GPU-accelerated direct-sum boundary integral method to solve the linear Poisson-Boltzmann (PB) equation. In our method, a well-posed boundary integral formulation is used to ensure the fast convergence of Krylov subspace based linear algebraic solver such as the GMRES. The molecular surfaces are discretized with flat triangles and centroid collocation. To speed up our method, we take advantage of the parallel nature of the boundary integral formulation and parallelize the schemes within CUDA shared memory architecture on GPU. The schemes use only 11N+6Nc size-of-double device memory for a biomolecule with N triangular surface elements and Nc partial charges. Numerical tests of these schemes show well-maintained accuracy and fast convergence. The GPU implementation using one GPU card (Nvidia Tesla M2070) achieves 120-150X speed-up to the implementation using one CPU (Intel L5640 2.27 GHz). With our approach, solving PB equations on well-discretized molecular surfaces with up to 300,000 boundary elements will take less than about 10 min, hence our approach is particularly suitable for fast electrostatics computations on small to medium biomolecules.
Local Interstellar Magnetic Field Determined from the Interstellar Boundary Explorer Ribbon
NASA Astrophysics Data System (ADS)
Zirnstein, E. J.; Heerikhuisen, J.; Funsten, H. O.; Livadiotis, G.; McComas, D. J.; Pogorelov, N. V.
2016-02-01
The solar wind emanating from the Sun interacts with the local interstellar medium (LISM), forming the heliosphere. Hydrogen energetic neutral atoms (ENAs) produced by the solar-interstellar interaction carry important information about plasma properties from the boundaries of the heliosphere, and are currently being measured by NASA's Interstellar Boundary Explorer (IBEX). IBEX observations show the existence of a “ribbon” of intense ENA emission projecting a circle on the celestial sphere that is centered near the local interstellar magnetic field (ISMF) vector. Here we show that the source of the IBEX ribbon as a function of ENA energy outside the heliosphere, uniquely coupled to the draping of the ISMF around the heliopause, can be used to precisely determine the magnitude (2.93 ± 0.08 μG) and direction (227.°28 ± 0.°69, 34.°62 ± 0.°45 in ecliptic longitude and latitude) of the pristine ISMF far (∼1000 AU) from the Sun. We find that the ISMF vector is offset from the ribbon center by ∼8.°3 toward the direction of motion of the heliosphere through the LISM, and their vectors form a plane that is consistent with the direction of deflected interstellar neutral hydrogen, thought to be controlled by the ISMF. Our results yield draped ISMF properties close to that observed by Voyager 1, the only spacecraft to directly measure the ISMF close to the heliosphere, and give predictions of the pristine ISMF that Voyager 1 has yet to sample.
Charged hadrons in local finite-volume QED+QCD with C⋆ boundary conditions
NASA Astrophysics Data System (ADS)
Lucini, B.; Patella, A.; Ramos, A.; Tantalo, N.
2016-02-01
In order to calculate QED corrections to hadronic physical quantities by means of lattice simulations, a coherent description of electrically-charged states in finite volume is needed. In the usual periodic setup, Gauss's law and large gauge transformations forbid the propagation of electrically-charged states. A possible solution to this problem, which does not violate the axioms of local quantum field theory, has been proposed by Wiese and Polley, and is based on the use of C⋆ boundary conditions. We present a thorough analysis of the properties and symmetries of QED in isolation and QED coupled to QCD, with C⋆ boundary conditions. In particular we learn that a certain class of electrically-charged states can be constructed in a fully consistent fashion without relying on gauge fixing and without peculiar complications. This class includes single particle states of most stable hadrons. We also calculate finite-volume corrections to the mass of stable charged particles and show that these are much smaller than in non-local formulations of QED.
Li, Xiaofan; Nie, Qing
2015-01-01
Many applications in materials involve surface diffusion of elastically stressed solids. Study of singularity formation and long-time behavior of such solid surfaces requires accurate simulations in both space and time. Here we present a high-order boundary integral method for an elastically stressed solid with axi-symmetry due to surface diffusions. In this method, the boundary integrals for isotropic elasticity in axi-symmetric geometry are approximated through modified alternating quadratures along with an extrapolation technique, leading to an arbitrarily high-order quadrature; in addition, a high-order (temporal) integration factor method, based on explicit representation of the mean curvature, is used to reduce the stability constraint on time-step. To apply this method to a periodic (in axial direction) and axi-symmetric elastically stressed cylinder, we also present a fast and accurate summation method for the periodic Green’s functions of isotropic elasticity. Using the high-order boundary integral method, we demonstrate that in absence of elasticity the cylinder surface pinches in finite time at the axis of the symmetry and the universal cone angle of the pinching is found to be consistent with the previous studies based on a self-similar assumption. In the presence of elastic stress, we show that a finite time, geometrical singularity occurs well before the cylindrical solid collapses onto the axis of symmetry, and the angle of the corner singularity on the cylinder surface is also estimated. PMID:26487788
NASA Astrophysics Data System (ADS)
Akamatsu, T.; Matsushita, M.; Murata, S.
1985-11-01
A two-parameter integral method is presented which is applicable even to separated boundary layers. The governing equation system, which consists of three moment equations of the boundary layer equation, is shown to be classifiable as a quasi-linear hyperbolic system under the assumed velocity profile function. The governing system is numerically solved by a dissipative finite difference scheme in order to capture a discontinuous solution associated with the singularity of unsteady separation. The spontaneous generation of singularity associated with unsteady separation is confirmed as the focusing of characteristics. The starting flows of a circular and an elliptic cylinder are considered as definite examples. This method is found to give excellent results in comparison with exact methods, not only for practically important boundary layer quantities such as displacement thickness or skin friction coefficient, but also for generation of separation singularity.
Modeling photonic crystals by boundary integral equations and Dirichlet-to-Neumann maps
Yuan Jianhua; Lu Yayan Antoine, Xavier
2008-04-20
Efficient numerical methods for analyzing photonic crystals (PhCs) can be developed using the Dirichlet-to-Neumann (DtN) maps of the unit cells. The DtN map is an operator that takes the wave field on the boundary of a unit cell to its normal derivative. In frequency domain calculations for band structures and transmission spectra of finite PhCs, the DtN maps allow us to reduce the computation to the boundaries of the unit cells. For two-dimensional (2D) PhCs with unit cells containing circular cylinders, the DtN maps can be constructed from analytic solutions (the cylindrical waves). In this paper, we develop a boundary integral equation method for computing DtN maps of general unit cells containing cylinders with arbitrary cross sections. The DtN map method is used to analyze band structures for 2D PhCs with elliptic and other cylinders.
Canonical formulation and path integral for local vacuum energy sequestering
NASA Astrophysics Data System (ADS)
Bufalo, R.; KlusoÅ, J.; Oksanen, M.
2016-08-01
We establish the Hamiltonian analysis and the canonical path integral for a local formulation of vacuum energy sequestering. In particular, by considering the state of the Universe as a superposition of vacuum states corresponding to different values of the cosmological and gravitational constants, the path integral is extended to include integrations over the cosmological and gravitational constants. The result is an extension of the Ng-van Dam form of the path integral of unimodular gravity. It is argued to imply a relation between the fraction of the most likely values of the gravitational and cosmological constants and the average values of the energy density and pressure of matter over spacetime. Finally, we construct and analyze a Becchi-Rouet-Stora-Tyutin-exact formulation of the theory, which can be considered as a topological field theory.
Taylor, P R; Baker, R E; Yates, C A
2014-01-01
In this paper we explore lattice-based position-jump models of diffusion, and the implications of introducing non-local jumping; particles can jump to a range of nearby boxes rather than only to their nearest neighbours. We begin by deriving conditions for equivalence with traditional local jumping models in the continuum limit. We then generalize a previously postulated implementation of the Robin boundary condition for a non-local process of arbitrary maximum jump length, and present a novel implementation of flux boundary conditions, again generalized for a non-local process of arbitrary maximum jump length. In both these cases we validate our results using stochastic simulation. We then proceed to consider two variations on the basic diffusion model: a hybrid local/non-local scheme suitable for models involving sharp concentration gradients, and the implementation of biased jumping. In all cases we show that non-local jumping can deliver substantial time savings for stochastic simulations. PMID:25514045
NASA Astrophysics Data System (ADS)
Taylor, P. R.; Baker, R. E.; Yates, C. A.
2015-02-01
In this paper we explore lattice-based position-jump models of diffusion, and the implications of introducing non-local jumping; particles can jump to a range of nearby boxes rather than only to their nearest neighbours. We begin by deriving conditions for equivalence with traditional local jumping models in the continuum limit. We then generalize a previously postulated implementation of the Robin boundary condition for a non-local process of arbitrary maximum jump length, and present a novel implementation of flux boundary conditions, again generalized for a non-local process of arbitrary maximum jump length. In both these cases we validate our results using stochastic simulation. We then proceed to consider two variations on the basic diffusion model: a hybrid local/non-local scheme suitable for models involving sharp concentration gradients, and the implementation of biased jumping. In all cases we show that non-local jumping can deliver substantial time savings for stochastic simulations.
Corcelli, S.A.; Kress, J.D.; Pratt, L.R.
1995-08-07
This paper develops and characterizes mixed direct-iterative methods for boundary integral formulations of continuum dielectric solvation models. We give an example, the Ca{sup ++}{hor_ellipsis}Cl{sup {minus}} pair potential of mean force in aqueous solution, for which a direct solution at thermal accuracy is difficult and, thus for which mixed direct-iterative methods seem necessary to obtain the required high resolution. For the simplest such formulations, Gauss-Seidel iteration diverges in rare cases. This difficulty is analyzed by obtaining the eigenvalues and the spectral radius of the non-symmetric iteration matrix. This establishes that those divergences are due to inaccuracies of the asymptotic approximations used in evaluation of the matrix elements corresponding to accidental close encounters of boundary elements on different atomic spheres. The spectral radii are then greater than one for those diverging cases. This problem is cured by checking for boundary element pairs closer than the typical spatial extent of the boundary elements and for those cases performing an ``in-line`` Monte Carlo integration to evaluate the required matrix elements. These difficulties are not expected and have not been observed for the thoroughly coarsened equations obtained when only a direct solution is sought. Finally, we give an example application of hybrid quantum-classical methods to deprotonation of orthosilicic acid in water.
Tavara, Luis; Mantic, Vladislav; Salvadori, Alberto; Gray, Leonard J; Paris, Federico
2009-01-01
A symmetric boundary integral formulation for cohesive cracks growing in the interior of homogeneous linear elastic isotropic media and/or at interfaces between these media is developed and implemented in a numerical code. The solution of a problem that includes cohesive cracks depends on the cohesive law adopted. In the present work, models based on the concept of free energy density per unit undeformed area are considered. The corresponding constitutive cohesive equations present a softening branch which induces to the problem a potential instability. Thus, the development and implementation of a suitable solution algorithm capable of following the growth of the cohesive zone becomes an important issue. An arc-length control combined with a Newton-Raphson algorithm for iterative solution of nonlinear equations is used. The Boundary Element Method is very attractive for modeling cohesive crack problems as all nonlinearities are located on the boundaries (including the crack boundaries) of linear elastic domains. A Galerkin approximation scheme, applied to a suitable symmetric integral formulation, ensures an easy treatment of cracks in homogeneous media and excellent convergence behavior of the numerical solution. Numerical results for the wedge split test are presented and compared with experimental results available in the literature.
NASA Astrophysics Data System (ADS)
Semedo, Alvaro
2015-04-01
There are two types of waves at the ocean surface. During the generation and growing processes, they are designated as wind sea; as waves propagate away from their generation area, they are called swell. Swell waves travel long distances across the globe with little attenuation For this reason the wave field does not necessarily reflect the local wind field characteristics. Since swell propagates long distances, across entire ocean basins, in the open ocean the wave field is, most of the times, the result of contributions from waves with different frequencies and directions, reflecting different origins and ages. The qualitative analysis of ocean surface waves has been the focus of several recent studies, from the wave climate to the air-sea interaction community. The reason for this interest lies mostly in the fact that waves have an impact on the lower atmosphere, and that the air-sea coupling is different depending on the wave regime. Waves modulate the exchange of momentum, heat, and mass across the air-sea interface, and this modulation is different and dependent on the prevalence of one type of waves: wind sea or swell. For fully developed seas the coupling between the ocean-surface and the overlaying atmosphere can be seen as quasi-perfect, in a sense that the momentum transfer and energy dissipation at the ocean surface are in equilibrium. This can only occur in special areas of the Ocean, like marginal or enclosed seas, with limited fetch, or in Open Ocean, in areas with strong and persistent wind speed with little or no variation in direction. The wind pattern along eastern boundary currents, in the summer, is equator-ward and coast parallel, due to the presence of a semi-permanente high pressure system off-shore, in the ocean, and to a thermal low in-land. The resulting coast parallel winds are the geostrophically adjusted response to this synoptic pattern that drives upwelling along EBC, due to the Eknam transport offshore, sharpening the thermal and
A finite element-boundary integral method for conformal antenna arrays on a circular cylinder
NASA Technical Reports Server (NTRS)
Kempel, Leo C.; Volakis, John L.; Woo, Alex C.; Yu, C. Long
1992-01-01
Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. In the past, antenna designers have had to resort to expensive measurements in order to develop a conformal array design. This is due to the lack of rigorous mathematical models for conformal antenna arrays, and as a result the design of conformal arrays is primarily based on planar antenna design concepts. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. Herewith we shall extend this formulation for conformal arrays on large metallic cylinders. In this we develop the mathematical formulation. In particular we discuss the finite element equations, the shape elements, and the boundary integral evaluation, and it is shown how this formulation can be applied with minimal computation and memory requirements. The implementation shall be discussed in a later report.
A finite element-boundary integral method for conformal antenna arrays on a circular cylinder
NASA Technical Reports Server (NTRS)
Kempel, Leo C.; Volakis, John L.
1992-01-01
Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. In the past, antenna designers have had to resort to expensive measurements in order to develop a conformal array design. This was due to the lack of rigorous mathematical models for conformal antenna arrays. As a result, the design of conformal arrays was primarily based on planar antenna design concepts. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. We are extending this formulation to conformal arrays on large metallic cylinders. In doing so, we will develop a mathematical formulation. In particular, we discuss the finite element equations, the shape elements, and the boundary integral evaluation. It is shown how this formulation can be applied with minimal computation and memory requirements.
Strong Local-Nonlocal Coupling for Integrated Fracture Modeling
Littlewood, David John; Silling, Stewart A.; Mitchell, John A.; Seleson, Pablo D.; Bond, Stephen D.; Parks, Michael L.; Turner, Daniel Z.; Burnett, Damon J.; Ostien, Jakob; Gunzburger, Max
2015-09-01
Peridynamics, a nonlocal extension of continuum mechanics, is unique in its ability to capture pervasive material failure. Its use in the majority of system-level analyses carried out at Sandia, however, is severely limited, due in large part to computational expense and the challenge posed by the imposition of nonlocal boundary conditions. Combined analyses in which peridynamics is em- ployed only in regions susceptible to material failure are therefore highly desirable, yet available coupling strategies have remained severely limited. This report is a summary of the Laboratory Directed Research and Development (LDRD) project "Strong Local-Nonlocal Coupling for Inte- grated Fracture Modeling," completed within the Computing and Information Sciences (CIS) In- vestment Area at Sandia National Laboratories. A number of challenges inherent to coupling local and nonlocal models are addressed. A primary result is the extension of peridynamics to facilitate a variable nonlocal length scale. This approach, termed the peridynamic partial stress, can greatly reduce the mathematical incompatibility between local and nonlocal equations through reduction of the peridynamic horizon in the vicinity of a model interface. A second result is the formulation of a blending-based coupling approach that may be applied either as the primary coupling strategy, or in combination with the peridynamic partial stress. This blending-based approach is distinct from general blending methods, such as the Arlequin approach, in that it is specific to the coupling of peridynamics and classical continuum mechanics. Facilitating the coupling of peridynamics and classical continuum mechanics has also required innovations aimed directly at peridynamic models. Specifically, the properties of peridynamic constitutive models near domain boundaries and shortcomings in available discretization strategies have been addressed. The results are a class of position-aware peridynamic constitutive laws for
Localized electronic states at grain boundaries on the surface of graphene and graphite
NASA Astrophysics Data System (ADS)
Luican-Mayer, Adina; Barrios-Vargas, Jose E.; Toft Falkenberg, Jesper; Autès, Gabriel; Cummings, Aron W.; Soriano, David; Li, Guohong; Brandbyge, Mads; Yazyev, Oleg V.; Roche, Stephan; Andrei, Eva Y.
2016-09-01
Recent advances in large-scale synthesis of graphene and other 2D materials have underscored the importance of local defects such as dislocations and grain boundaries (GBs), and especially their tendency to alter the electronic properties of the material. Understanding how the polycrystalline morphology affects the electronic properties is crucial for the development of applications such as flexible electronics, energy harvesting devices or sensors. We here report on atomic scale characterization of several GBs and on the structural-dependence of the localized electronic states in their vicinity. Using low temperature scanning tunneling microscopy and spectroscopy, together with tight binding and ab initio numerical simulations we explore GBs on the surface of graphite and elucidate the interconnection between the local density of states and their atomic structure. We show that the electronic fingerprints of these GBs consist of pronounced resonances which, depending on the relative orientation of the adjacent crystallites, appear either on the electron side of the spectrum or as an electron-hole symmetric doublet close to the charge neutrality point. These two types of spectral features will impact very differently the transport properties allowing, in the asymmetric case to introduce transport anisotropy which could be utilized to design novel growth and fabrication strategies to control device performance.
NASA Technical Reports Server (NTRS)
Edwards, S.; Reuther, J.; Chattot, J. J.
1997-01-01
The objective of this paper is to present a control theory approach for the design of airfoils in the presence of viscous compressible flows. A coupled system of the integral boundary layer and the Euler equations is solved to provide rapid flow simulations. An adjunct approach consistent with the complete coupled state equations is employed to obtain the sensitivities needed to drive a numerical optimization algorithm. Design to target pressure distribution is demonstrated on an RAE 2822 airfoil at transonic speed.
NASA Astrophysics Data System (ADS)
Edwards, S.; Reuther, J.; Chattot, J. J.
The objective of this paper is to present a control theory approach for the design of airfoils in the presence of viscous compressible flows. A coupled system of the integral boundary layer and the Euler equations is solved to provide rapid flow simulations. An adjoint approach consistent with the complete coupled state equations is employed to obtain the sensitivities needed to drive a numerical optimization algorithm. Design to a target pressure distribution is demonstrated on an RAE 2822 airfoil at transonic speeds.
Epitaxial integration of a nanoscale BiFeO3 phase boundary with silicon.
Liang, Wen-I; Peng, Chun-Yen; Huang, Rong; Kuo, Wei-Cheng; Huang, Yen-Chin; Adamo, Carolina; Chen, Yi-Chun; Chang, Li; Juang, Jenh-Yih; Schlom, Darrel G; Chu, Ying-Hao
2016-01-21
The successful integration of the strain-driven nanoscale phase boundary of BiFeO3 onto a silicon substrate is demonstrated with extraordinary ferroelectricity and ferromagnetism. The detailed strain history is delineated through a reciprocal space mapping technique. We have found that a distorted monoclinic phase forms prior to a tetragonal-like phase, a phenomenon which may correlates with the thermal strain induced during the growth process. PMID:26689266
Epitaxial integration of a nanoscale BiFeO3 phase boundary with silicon
NASA Astrophysics Data System (ADS)
Liang, Wen-I.; Peng, Chun-Yen; Huang, Rong; Kuo, Wei-Cheng; Huang, Yen-Chin; Adamo, Carolina; Chen, Yi-Chun; Chang, Li; Juang, Jenh-Yih; Schlom, Darrel G.; Chu, Ying-Hao
2016-01-01
The successful integration of the strain-driven nanoscale phase boundary of BiFeO3 onto a silicon substrate is demonstrated with extraordinary ferroelectricity and ferromagnetism. The detailed strain history is delineated through a reciprocal space mapping technique. We have found that a distorted monoclinic phase forms prior to a tetragonal-like phase, a phenomenon which may correlates with the thermal strain induced during the growth process.
A boundary integral method for an inverse problem in thermal imaging
NASA Technical Reports Server (NTRS)
Bryan, Kurt
1992-01-01
An inverse problem in thermal imaging involving the recovery of a void in a material from its surface temperature response to external heating is examined. Uniqueness and continuous dependence results for the inverse problem are demonstrated, and a numerical method for its solution is developed. This method is based on an optimization approach, coupled with a boundary integral equation formulation of the forward heat conduction problem. Some convergence results for the method are proved, and several examples are presented using computationally generated data.
The Reduction of Ducted Fan Engine Noise Via a Boundary Integral Equation Method
NASA Technical Reports Server (NTRS)
Tweed, John
2000-01-01
Engineering studies for reducing ducted fan engine noise were conducted using the noise prediction code TBIEM3D. To conduct parametric noise reduction calculations, it was necessary to advance certain theoretical and computational aspects of the boundary integral equation method (BIEM) described in and implemented in TBIEM3D. Also, enhancements and upgrades to TBIEM3D were made for facilitating the code's use in this research and by the aeroacoustics engineering community.
Navigating the boundary of science for decision making at the state and local level
NASA Astrophysics Data System (ADS)
Gonzales, L. M.; Wood, C.; Boland, M. A.; Rose, C. A.
2015-12-01
Scientific information should play a vital role in many decision making processes, yet issues incorporating geoscience information often arise due to inherent differences between how scientists and decision makers operate. Decision makers and scientists have different priorities, produce work at different rates, and often lack an understanding of each others' institutional constraints. Boundary organizations, entities that facilitate collaboration and information flow across traditional boundaries such as that between scientists and decision makers, are in a unique position to improve the dialogue between disparate groups. The American Geosciences Institute (AGI), a nonprofit federation of 50 geoscience societies and organizations, is linking the geoscience and decision-making communities through its Critical Issues Program. AGI's Critical Issues program has first-hand experience in improving the transfer of information across the science-decision making boundary, particularly in areas pertaining to water resources and hazards. This presentation will focus on how, by collaborating with organizations representing the decision making and geoscience communities to inform our program development, we have created our three main content types - website, webinar series, and research database - to better meet the needs of the decision-making process. The program presents existing geoscience information in a way that makes the interconnected nature of geoscience topics more easily understood, encourages discussion between the scientific and decision-making communities, and has established a trusted source of impartial geoscience information. These efforts have focused on state and local decision makers—groups that increasingly influence climate and risk-related decisions, yet often lack the resources to access and understand geoscience information.
Kreienkamp, Amelia B; Liu, Lucy Y; Minkara, Mona S; Knepley, Matthew G; Bardhan, Jaydeep P; Radhakrishnan, Mala L
2013-06-01
We analyze and suggest improvements to a recently developed approximate continuum-electrostatic model for proteins. The model, called BIBEE/I (boundary-integral based electrostatics estimation with interpolation), was able to estimate electrostatic solvation free energies to within a mean unsigned error of 4% on a test set of more than 600 proteins-a significant improvement over previous BIBEE models. In this work, we tested the BIBEE/I model for its capability to predict residue-by-residue interactions in protein-protein binding, using the widely studied model system of trypsin and bovine pancreatic trypsin inhibitor (BPTI). Finding that the BIBEE/I model performs surprisingly less well in this task than simpler BIBEE models, we seek to explain this behavior in terms of the models' differing spectral approximations of the exact boundary-integral operator. Calculations of analytically solvable systems (spheres and tri-axial ellipsoids) suggest two possibilities for improvement. The first is a modified BIBEE/I approach that captures the asymptotic eigenvalue limit correctly, and the second involves the dipole and quadrupole modes for ellipsoidal approximations of protein geometries. Our analysis suggests that fast, rigorous approximate models derived from reduced-basis approximation of boundary-integral equations might reach unprecedented accuracy, if the dipole and quadrupole modes can be captured quickly for general shapes. PMID:24466561
NASA Technical Reports Server (NTRS)
Hu, Fang Q.
1994-01-01
It is known that the exact analytic solutions of wave scattering by a circular cylinder, when they exist, are not in a closed form but in infinite series which converges slowly for high frequency waves. In this paper, we present a fast number solution for the scattering problem in which the boundary integral equations, reformulated from the Helmholtz equation, are solved using a Fourier spectral method. It is shown that the special geometry considered here allows the implementation of the spectral method to be simple and very efficient. The present method differs from previous approaches in that the singularities of the integral kernels are removed and dealt with accurately. The proposed method preserves the spectral accuracy and is shown to have an exponential rate of convergence. Aspects of efficient implementation using FFT are discussed. Moreover, the boundary integral equations of combined single and double-layer representation are used in the present paper. This ensures the uniqueness of the numerical solution for the scattering problem at all frequencies. Although a strongly singular kernel is encountered for the Neumann boundary conditions, we show that the hypersingularity can be handled easily in the spectral method. Numerical examples that demonstrate the validity of the method are also presented.
Kreienkamp, Amelia B.; Liu, Lucy Y.; Minkara, Mona S.; Knepley, Matthew G.; Bardhan, Jaydeep P.; Radhakrishnan, Mala L.
2013-01-01
We analyze and suggest improvements to a recently developed approximate continuum-electrostatic model for proteins. The model, called BIBEE/I (boundary-integral based electrostatics estimation with interpolation), was able to estimate electrostatic solvation free energies to within a mean unsigned error of 4% on a test set of more than 600 proteins—a significant improvement over previous BIBEE models. In this work, we tested the BIBEE/I model for its capability to predict residue-by-residue interactions in protein–protein binding, using the widely studied model system of trypsin and bovine pancreatic trypsin inhibitor (BPTI). Finding that the BIBEE/I model performs surprisingly less well in this task than simpler BIBEE models, we seek to explain this behavior in terms of the models’ differing spectral approximations of the exact boundary-integral operator. Calculations of analytically solvable systems (spheres and tri-axial ellipsoids) suggest two possibilities for improvement. The first is a modified BIBEE/I approach that captures the asymptotic eigenvalue limit correctly, and the second involves the dipole and quadrupole modes for ellipsoidal approximations of protein geometries. Our analysis suggests that fast, rigorous approximate models derived from reduced-basis approximation of boundary-integral equations might reach unprecedented accuracy, if the dipole and quadrupole modes can be captured quickly for general shapes. PMID:24466561
NASA Technical Reports Server (NTRS)
Robertson, J. S.; Siegman, W. L.; Jacobson, M. J.
1989-01-01
There is substantial interest in the analytical and numerical modeling of low-frequency, long-range atmospheric acoustic propagation. Ray-based models, because of frequency limitations, do not always give an adequate prediction of quantities such as sound pressure or intensity levels. However, the parabolic approximation method, widely used in ocean acoustics, and often more accurate than ray models for lower frequencies of interest, can be applied to acoustic propagation in the atmosphere. Modifications of an existing implicit finite-difference implementation for computing solutions to the parabolic approximation are discussed. A locally-reacting boundary is used together with a one-parameter impedance model. Intensity calculations are performed for a number of flow resistivity values in both quiescent and windy atmospheres. Variations in the value of this parameter are shown to have substantial effects on the spatial variation of the acoustic signal.
Localized and distributed boundary-layer receptivity to convected unsteady wake in free stream
NASA Technical Reports Server (NTRS)
Choudhari, Meelan
1994-01-01
Receptivity to a model convected disturbance in the presence of localized and distributed variations in wall geometry and wall-suction velocity is examined. The model free-stream disturbance corresponds to the time-harmonic wake of a vibrating ribbon that is placed at a suitable distance above the surface of a thin airfoil. The advantages of using this disturbance for experiments on receptivity to convected disturbances are outlined. A brief parametric study is presented for a flat-plate boundary layer. The study quantifies the effect of wake position as well as wake width; in addition, it should be helpful in the choice of an optimal setting for a controlled experiment of the above type, which the above parametric study shows as feasible.
Local surface sampling step estimation for extracting boundaries of planar point clouds
NASA Astrophysics Data System (ADS)
Brie, David; Bombardier, Vincent; Baeteman, Grégory; Bennis, Abdelhamid
2016-09-01
This paper presents a new approach to estimate the surface sampling step of planar point clouds acquired by Terrestrial Laser Scanner (TLS) which is varying with the distance to the surface and the angular positions. The local surface sampling step is obtained by doing a first order Taylor expansion of planar point coordinates. Then, it is shown how to use it in Delaunay-based boundary point extraction. The resulting approach, which is implemented in the ModiBuilding software, is applied to two facade point clouds of a building. The first is acquired with a single station and the second with two stations. In both cases, the proposed approach performs very accurately and appears to be robust to the variations of the point cloud density.
Resistive switching in hafnium dioxide layers: Local phenomenon at grain boundaries
NASA Astrophysics Data System (ADS)
Lanza, M.; Bersuker, G.; Porti, M.; Miranda, E.; Nafría, M.; Aymerich, X.
2012-11-01
Overcoming challenges associated with implementation of resistive random access memory technology for non-volatile information storage requires identifying the material characteristics responsible for resistive switching. In order to connect the switching phenomenon to the nano-scale morphological features of the dielectrics employed in memory cells, we applied the enhanced conductive atomic force microscopy technique for in situ analysis of the simultaneously collected electrical and topographical data on HfO2 stacks of various degrees of crystallinity. We demonstrate that the resistive switching is a local phenomenon associated with the formation of a conductive filament with a sufficiently small cross-section, which is determined by the maximum passing current. Switchable filament is found to be formed at the dielectric sites where the forming voltages were sufficiently small, which, in the case of the stoichiometric HfO2, is observed exclusively at the grain boundary regions representing low resistant conductive paths through the dielectric film.
Numerical solutions to ill-posed and well-posed impedance boundary condition integral equations
NASA Astrophysics Data System (ADS)
Rogers, J. R.
1983-11-01
Exterior scattering from a three-dimensional impedance body can be formulated in terms of various integral equations derived from the Leontovich impedance boundary condition (IBC). The electric and magnetic field integral equations are ill-posed because they theoretically admit spurious solutions at the frequencies of interior perfect conductor cavity resonances. A combined field formulation is well-posed because it does not allow the spurious solutions. This report outlines the derivation of IBC integral equations and describes a procedure for constructing moment-method solutions for bodies of revolution. Numerical results for scattering from impedance spheres are presented which contrast the stability and accuracy of solutions to the ill-posed equations with those of the well-posed equation. The results show that numerical solutions for exterior scattering to the electric and magnetic field integral equations can be severely contaminated by spurious resonant solutions regardless of whether the surface impedance of the body is lossy or lossless.
Coupling finite element and integral equation solutions using decoupled boundary meshes
NASA Technical Reports Server (NTRS)
Cwik, Tom
1992-01-01
A method is outlined for calculating scattered fields from inhomogeneous penetrable objects using a coupled finite element-integral equation solution. The finite element equation can efficiently model fields in penetrable and inhomogeneous regions, while the integral equation exactly models fields on the finite element mesh boundary and in the exterior region. By decoupling the interior finite element and exterior integral equation meshes, considerable flexibility is found in both the number of field expansion points as well as their density. Only the nonmetal portions of the object need be modeled using a finite element expansion; exterior perfect conducting surfaces are modeled using an integral equation with a single unknown field since E(tan) is identically zero on these surfaces. Numerical convergence, accuracy, and stability at interior resonant frequencies are studied in detail.
A boundary integral approach to analyze the viscous scattering of a pressure wave by a rigid body
Homentcovschi, Dorel; Miles, Ronald N.
2008-01-01
The paper provides boundary integral equations for solving the problem of viscous scattering of a pressure wave by a rigid body. By using this mathematical tool uniqueness and existence theorems are proved. Since the boundary conditions are written in terms of velocities, vector boundary integral equations are obtained for solving the problem. The paper introduces single-layer viscous potentials and also a stress tensor. Correspondingly, a viscous double-layer potential is defined. The properties of all these potentials are investigated. By representing the scattered field as a combination of a single-layer viscous potential and a double-layer viscous potential the problem is reduced to the solution of a singular vectorial integral equation of Fredholm type of the second kind. In the case where the stress vector on the boundary is the main quantity of interest the corresponding boundary singular integral equation is proved to have a unique solution. PMID:18709178
Heterogeneous optoelectronic integration using locally polymerized imprinted hard mask
NASA Astrophysics Data System (ADS)
Sodhi, Avantika; Beach, Samuel J.; Chen, Luis; Jacob-Mitos, Matt; Roth, Jonathan E.; Bowers, John; Theogarajan, Luke
2013-03-01
This paper presents a novel technique for the integration of Complementary Metal-Oxide Semiconductor (CMOS) chip with a Photonic Integrated Circuit (PIC). This proposed technique is demonstrated by integrating a PIC comprising of 2X2 optical switches and a CMOS header processor, implemented in the IBM 130nm CMOS technology. The processor configures the switch fabric on the PIC allowing for the design of ultra-fast low-power optical packet switching. An innovative CMOS chip based imprinted hard mask technique, utilizing a heat curable Polydimethylsiloxane (PDMS), allows for accurate microfabrication of wafer-scale sockets. The fabricated sockets in the PIC are at-most 9 μm larger than the chip on all sides. Accurate alignment between chips is achieved by using bottom side contact lithography printer to pattern alignment marks on the backside of the chip, making the process insensitive to chip size variations. Independent temperature control of the arm and the stage in the flip-chip bonder enables localized polymerization of PDMS to form imprinted hard mask for integration of PIC with more than one CMOS chip, enabling seamless multichip integration. The horizontal gap and the vertical displacement between the chip and the PIC were 7 and 0.5 um respectively. Electrical connections between the CMOS chip and the PIC were patterned and tested both electrically and optically. These measurements show that the functionality of the PIC and the CMOS chip were not affected by the integration process.
NASA Astrophysics Data System (ADS)
Xie, Guizhong; Zhang, Jianming; Huang, Cheng; Lu, Chenjun; Li, Guangyao
2014-04-01
This paper presents a direct traction boundary integral equation method (TBIEM) for three-dimensional crack problems. The TBIEM is based on the traction boundary integral equation (TBIE). The TBIE is collocated on both the external boundary and one of the crack surfaces. The displacements and tractions are used as unknowns on the external boundary and the relative crack opening displacements (CODs) are introduced as unknowns on the crack surface. In our implementation, all the surfaces of the considered structure are discretized into discontinuous elements to satisfy the continuity requirement for the existence of finite-part integrals, and special crack-front elements are constructed to capture the crack-tip behavior. To calculate the finite-part integrals, an adaptive singular integral technique is proposed. The stress intensity factors (SIFs) are computed through a modified COD extrapolation method. Numerical examples of SIFs computation are presented to demonstrate the accuracy and efficiency of our method.
Local conservation laws in spin-\\frac{1}{2} XY chains with open boundary conditions
NASA Astrophysics Data System (ADS)
Fagotti, Maurizio
2016-06-01
We revisit the conserved quantities of the spin-\\frac{1}{2} XY model with open boundary conditions. In the absence of a transverse field, we find new families of local charges and show that half of the seeming conservation laws are conserved only if the number of sites is odd. In even chains the set of noninteracting charges is abelian, like in the periodic case when the number of sites is odd. In odd chains the set is doubled and becomes non-abelian, like in even periodic chains. The dependence of the charges on the parity of the chain’s size undermines the common belief that the thermodynamic limit of diagonal ensembles exists. We consider also the transverse-field Ising chain, where the situation is more ordinary. The generalization to the XY model in a transverse field is not straightforward and we propose a general framework to carry out similar calculations. We conjecture the form of the bulk part of the local charges and discuss the emergence of quasilocal conserved quantities. We provide evidence that in a region of the parameter space there is a reduction of the number of quasilocal conservation laws invariant under chain inversion. As a by-product, we study a class of block-Toeplitz-plus-Hankel operators and identify the conditions that their symbols satisfy in order to commute with a given block-Toeplitz.
Turbulent boundary layer induced vibration up to high frequencies by means of local energy methods
NASA Astrophysics Data System (ADS)
Hardy, Pierre; Jezequel, Louis; Ichchou, Mohammed; Jacques, Yves
2002-11-01
The local energy method developed in the last years revealed appropriate in medium and high frequencies and supplies an accurate description of the spread of vibration and acoustic fields up to high frequencies. Our aim in the paper is to provide a complete description of the turbulent boundary layer (TBL) induced vibration by means of this method, for a simply supported thin plate. The first step in the energy method proof is the characterization of energy input from a given model of the TBL pressure interspectrum. Then, is deduced the uncoherent structural response of the panel, and the uncoherent normal mean square velocity. The latter provides, using the acoustic radiation resistance, a prediction of noise radiating by the panel up to high frequencies. Accuracy of the local energy analysis versus the usual random normal modes decomposition is demonstrated. Ultimately, a numerical parametric survey is given for various internal loss level. Precisely, the link between results provided here and SEA predictions of TBL structural induced vibration is discussed.
Evaluation of nonlocal and local planetary boundary layer schemes in the WRF model
NASA Astrophysics Data System (ADS)
Xie, Bo; Fung, Jimmy C. H.; Chan, Allen; Lau, Alexis
2012-06-01
A realistic reproduction of planetary boundary layer (PBL) structure and its evolution is critical to numerical simulation of regional meteorology and air quality. Conversely, insufficient realism in the simulated physical properties often leads to degraded meteorological and air quality prognostic skills. This study employed the Weather Research and Forecasting model (WRF) to evaluate model performance and to quantify meteorological prediction differences produced by four widely used PBL schemes. Evaluated were two nonlocal PBL schemes, YSU and ACM2, and two local PBL schemes, MYJ and Boulac. The model grid comprised four nested domains at horizontal resolutions of 27 km, 9 km, 3 km and 1 km respectively. Simulated surface variables 2 m temperature and 10 m wind at 1 km resolution were compared to measurements collected in Hong Kong. A detailed analysis of land-atmosphere energy balance explicates heat flux and temperature variability among the PBL schemes. Differences in vertical profiles of horizontal velocity, potential temperature, bulk Richardson number and water vapor mixing ratio were examined. Diagnosed PBL heights, estimated by scheme specific formulations, exhibited the large intrascheme variance. To eliminate formulation dependence in PBL height estimation, lidar measurements and a unified diagnosis were jointly used to reanalyze PBL heights. The diagnosis showed that local PBL schemes produced shallower PBL heights than those of nonlocal PBL schemes. It is reasonable to infer that WRF, coupled with the ACM2 PBL physics option can be a viable producer of meteorological forcing to regional air quality modeling in the Pearl River Delta (PRD) Region.
Integrity of the reactor coolant boundary of the European pressurized water reactor (EPR)
Goetsch, D.; Bieniussa, K.; Schulz, H.; Jalouneix, J.
1997-04-01
This paper is an abstract of the work performed in the frame of the development of the IPSN/GRS approach in view of the EPR conceptual safety features. EPR is a pressurized water reactor which will be based on the experience gained by utilities and designers in France and in Germany. The reactor coolant boundary of a PWR includes the reactor pressure vessel (RPV), those parts of the steam generators (SGs) which contain primary coolant, the pressurizer (PSR), the reactor coolant pumps (RCPs), the main coolant lines (MCLs) with their branches as well as the other connecting pipes and all branching pipes including the second isolation valves. The present work covering the integrity of the reactor coolant boundary is mainly restricted to the integrity of the main coolant lines (MCLs) and reflects the design requirements for the main components of the reactor coolant boundary. In the following the conceptual aspects, i.e. design, manufacture, construction and operation, will be assessed. A main aspect is the definition of break postulates regarding overall safety implications.
The Reduction of Ducted Fan Engine Noise Via A Boundary Integral Equation Method
NASA Technical Reports Server (NTRS)
Tweed, J.; Dunn, M.
1997-01-01
The development of a Boundary Integral Equation Method (BIEM) for the prediction of ducted fan engine noise is discussed. The method is motivated by the need for an efficient and versatile computational tool to assist in parametric noise reduction studies. In this research, the work in reference 1 was extended to include passive noise control treatment on the duct interior. The BEM considers the scattering of incident sound generated by spinning point thrust dipoles in a uniform flow field by a thin cylindrical duct. The acoustic field is written as a superposition of spinning modes. Modal coefficients of acoustic pressure are calculated term by term. The BEM theoretical framework is based on Helmholtz potential theory. A boundary value problem is converted to a boundary integral equation formulation with unknown single and double layer densities on the duct wall. After solving for the unknown densities, the acoustic field is easily calculated. The main feature of the BIEM is the ability to compute any portion of the sound field without the need to compute the entire field. Other noise prediction methods such as CFD and Finite Element methods lack this property. Additional BIEM attributes include versatility, ease of use, rapid noise predictions, coupling of propagation and radiation both forward and aft, implementable on midrange personal computers, and valid over a wide range of frequencies.
Integrated modeling and characterization of local crack chemistry
Savchik, J.A.; Burke, M.S.
1995-12-31
The MULTEQ computer program has become an industry wide tool which can be used to calculate the chemical composition in a flow occluded region as the solution within concentrates due to a local boiling process. These results can be used to assess corrosion concerns in plant equipment such as steam generators. Corrosion modeling attempts to quantify corrosion assessments by accounting for the mass transport processes involved in the corrosion mechanism. MULTEQ has played an ever increasing role in defining the local chemistry for such corrosion models. This paper will outline how the integration of corrosion modeling with the analysis of corrosion films and deposits can lead to the development of a useful modeling tool, wherein MULTEQ is interactively linked to a diffusion and migration transport process. This would provide a capability to make detailed inferences of the local crack chemistry based on the analyses of the local corrosion films and deposits inside a crack and thus provide guidance for chemical fixes to avoid cracking. This methodology is demonstrated for a simple example of a cracked tube. This application points out the utility of coupling MULTEQ with a mass transport process and the feasibility of an option in a future version of MULTEQ that would permit relating film and deposit analyses to the local chemical environment. This would increase the amount of information obtained from removed tube analyses and laboratory testing that can contribute to an overall program for mitigating tubing and crevice corrosion.
Graphical construction of a local perspective on differentiation and integration
NASA Astrophysics Data System (ADS)
Hong, Ye Yoon; Thomas, Michael O. J.
2015-06-01
Recent studies of the transition from school to university mathematics have identified a number of epistemological gaps, including the need to change from an emphasis on equality to that of inequality. Another crucial epistemological change during this transition involves the movement from the pointwise and global perspectives of functions usually established through the school curriculum to a view of function that includes a local, or interval, perspective. This is necessary for study of concepts such as continuity and limit that underpin calculus and analysis at university. In this study, a first-year university calculus course in Korea was constructed that integrated use of digital technology and considered the epistemic value of the associated techniques. The aim was to encourage versatile thinking about functions, especially in relation to properties arising from a graphical investigation of differentiation and integration. In this paper, the results of this approach for the learning of derivative and antiderivative, based on integrated technology use, are presented. They show the persistence of what Tall ( Mathematics Education Research Journal, 20(2), 5-24, 2008) describes as symbolic world algebraic thinking on the part of a significant minority of students, who feel the need to introduce algebraic methods, in spite of its disadvantages, even when no explicit algebra is provided. However, the results also demonstrate the ability of many of the students to use technology mediation to build local or interval conceptual thinking about derivative and antiderivative functions.
Application of the method of integral relations to boundary layer flows over blunt bodies
NASA Technical Reports Server (NTRS)
Modarress, D.
1978-01-01
Calculations of boundary layer flows past blunt bodies at angles of incidence are presented. Using the method of integral relations together with the method of lines, the full three-dimensional boundary layer equations are reduced to a system of first-order ordinary differential equations. The streamwise shear stress function and the cross-flow velocity component are represented as suitable functions of the streamwise velocity component. The role of the zone of dependence is automatically satisfied by the choice of differencing in the method of lines. Solutions correct to the second order are obtained in the positive shear region for flow over an ellipsoid at 30-deg incidence. The results are compared with corresponding finite difference solutions.
NASA Technical Reports Server (NTRS)
Hu, Fang Q.; Pizzo, Michelle E.; Nark, Douglas M.
2016-01-01
Based on the time domain boundary integral equation formulation of the linear convective wave equation, a computational tool dubbed Time Domain Fast Acoustic Scattering Toolkit (TD-FAST) has recently been under development. The time domain approach has a distinct advantage that the solutions at all frequencies are obtained in a single computation. In this paper, the formulation of the integral equation, as well as its stabilization by the Burton-Miller type reformulation, is extended to cases of a constant mean flow in an arbitrary direction. In addition, a "Source Surface" is also introduced in the formulation that can be employed to encapsulate regions of noise sources and to facilitate coupling with CFD simulations. This is particularly useful for applications where the noise sources are not easily described by analytical source terms. Numerical examples are presented to assess the accuracy of the formulation, including a computation of noise shielding by a thin barrier motivated by recent Historical Baseline F31A31 open rotor noise shielding experiments. Furthermore, spatial resolution requirements of the time domain boundary element method are also assessed using point per wavelength metrics. It is found that, using only constant basis functions and high-order quadrature for surface integration, relative errors of less than 2% may be obtained when the surface spatial resolution is 5 points-per-wavelength (PPW) or 25 points-per-wavelength squared (PPW2).
NASA Technical Reports Server (NTRS)
Om, D.; Childs, M. E.
1983-01-01
An approximate integral viscous-inviscid interaction method is presented for calculating the development of a turbulent boundary layer subjected to a normal shock wave induced adverse pressure gradient in an internal axisymmetric flow. The inflow conditions and the downstream pressure are provided for the computation. In the supersonic region of shock pressure rise, the Prandtl-Meyer function is used to couple the viscous and inviscid flows. An analytical model for the coupling process is postulated and appropriate equations are defined. Downstream of the sonic point, one-dimensional inviscid flow is assumed for coupling with the viscous flow. The turbulent boundary layer is calculated using Green's integral lag-entrainment method. Comparisons of the solutions with the experimental data are made for interactions which are unseparated, near separation and separated. For comparison purposes, solutions to the time-dependent, mass-averaged, Navier-Stokes equations incorporating a two-equation, Wilcox-Rubesin turbulence model are also shown. The computed results from the integral method show good agreement with experimental data for unseparated interactions and reasonable agreement with the trend of the viscous effects when the interaction becomes increasingly separated.
NASA Astrophysics Data System (ADS)
Geng, Weihua; Krasny, Robert
2013-08-01
We present a treecode-accelerated boundary integral (TABI) solver for electrostatics of solvated biomolecules described by the linear Poisson-Boltzmann equation. The method employs a well-conditioned boundary integral formulation for the electrostatic potential and its normal derivative on the molecular surface. The surface is triangulated and the integral equations are discretized by centroid collocation. The linear system is solved by GMRES iteration and the matrix-vector product is carried out by a Cartesian treecode which reduces the cost from O(N2) to O(NlogN), where N is the number of faces in the triangulation. The TABI solver is applied to compute the electrostatic solvation energy in two cases, the Kirkwood sphere and a solvated protein. We present the error, CPU time, and memory usage, and compare results for the Poisson-Boltzmann and Poisson equations. We show that the treecode approximation error can be made smaller than the discretization error, and we compare two versions of the treecode, one with uniform clusters and one with non-uniform clusters adapted to the molecular surface. For the protein test case, we compare TABI results with those obtained using the grid-based APBS code, and we also present parallel TABI simulations using up to eight processors. We find that the TABI solver exhibits good serial and parallel performance combined with relatively simple implementation, efficient memory usage, and geometric adaptability.
NASA Astrophysics Data System (ADS)
Hayes, Gavin Peter
The relative motion of tectonic plates across their boundaries generates deformation in the surrounding lithosphere. How this deformation is expressed reflects both present-day plate configurations and how plate boundaries evolve. To understand the behavior of plate boundaries, we must study how they have developed. The advances made in seismology over the past fifty years---both in observation and application---provide tools ideal for such analysis. Here, I use these tools to investigate the tectonic evolution of complex plate boundaries. I focus on two areas that have experienced geologically recent plate tectonic variations---the Mendocino triple junction in northern California, and the Australia:Pacific plate boundary south of New Zealand. In northern California, the northward migration of the Mendocino triple junction over the past ˜10Ma has driven a synchronous pattern of thickening and thinning of North American crust. In studying this deformation I find major thinning is localized to a narrow region of crust in the Redwood Valley area. This thinning is accompanied by a steeply dipping Moho (>15°), and by high Poisson's Ratio's in the lower crust, characteristic of layers of melt. These melts may link to shallow (˜10km) dike injections that drive a migrating sequence of seismicity in the shallow crust near Lake Pillsbury. The limited data sets available led me to develop new tools in receiver function and crustal velocity ratio analyses that significantly improve our ability to resolve spatial changes in crustal properties. The application of these techniques forms a second major aspect of this thesis. Finally, I analyze the deformation of Australian lithosphere adjacent to the plate boundary south of New Zealand. I perform earthquake relocations on the distribution of intra- and inter-plate seismicity, and combined with plate reconstructions since the late Oligocene show that deformation occurs over a ˜150km wide area west of the current plate boundary
Extending the diffusion approximation to the boundary using an integrated diffusion model
NASA Astrophysics Data System (ADS)
Chen, Chen; Du, Zhidong; Pan, Liang
2015-06-01
The widely used diffusion approximation is inaccurate to describe the transport behaviors near surfaces and interfaces. To solve such stochastic processes, an integro-differential equation, such as the Boltzmann transport equation (BTE), is typically required. In this work, we show that it is possible to keep the simplicity of the diffusion approximation by introducing a nonlocal source term and a spatially varying diffusion coefficient. We apply the proposed integrated diffusion model (IDM) to a benchmark problem of heat conduction across a thin film to demonstrate its feasibility. We also validate the model when boundary reflections and uniform internal heat generation are present.
Analysis of Well-Clear Boundary Models for the Integration of UAS in the NAS
NASA Technical Reports Server (NTRS)
Upchurch, Jason M.; Munoz, Cesar A.; Narkawicz, Anthony J.; Chamberlain, James P.; Consiglio, Maria C.
2014-01-01
The FAA-sponsored Sense and Avoid Workshop for Unmanned Aircraft Systems (UAS) defnes the concept of sense and avoid for remote pilots as "the capability of a UAS to remain well clear from and avoid collisions with other airborne traffic." Hence, a rigorous definition of well clear is fundamental to any separation assurance concept for the integration of UAS into civil airspace. This paper presents a family of well-clear boundary models based on the TCAS II Resolution Advisory logic. Analytical techniques are used to study the properties and relationships satisfied by the models. Some of these properties are numerically quantifed using statistical methods.
Nair, N V; Shanker, B; Kempel, L
2012-09-01
Boundary integral equations (BIEs) find applications in problems ranging from sonar to medical diagnostics. The two ingredients of the BIE solution technique are (1) representation of the domain and (2) design of approximation spaces to represent physical quantities on the domain. These, in concert, affect accuracy and convergence of the simulation. This paper presents a framework that permits the development of a scheme for refinement (of size and order) in both geometry and function representations. Further, this permits flexibility in the types of basis functions that can be used. Capabilities of the proposed framework are shown via a number of numerical examples. PMID:22978854
Combining the boundary shift integral and tensor-based morphometry for brain atrophy estimation
NASA Astrophysics Data System (ADS)
Michalkiewicz, Mateusz; Pai, Akshay; Leung, Kelvin K.; Sommer, Stefan; Darkner, Sune; Sørensen, Lauge; Sporring, Jon; Nielsen, Mads
2016-03-01
Brain atrophy from structural magnetic resonance images (MRIs) is widely used as an imaging surrogate marker for Alzheimers disease. Their utility has been limited due to the large degree of variance and subsequently high sample size estimates. The only consistent and reasonably powerful atrophy estimation methods has been the boundary shift integral (BSI). In this paper, we first propose a tensor-based morphometry (TBM) method to measure voxel-wise atrophy that we combine with BSI. The combined model decreases the sample size estimates significantly when compared to BSI and TBM alone.
An inverse method for the design of bodies of revolution by boundary integral modelling
NASA Astrophysics Data System (ADS)
Lewis, R. I.
A surface vorticity boundary integral method is presented for the design of bodies of revolution in axisymmetric flow. The analysis finds the desired body shape to deliver a prescribed surface potential flow velocity or pressure distribution. To achieve this the body surface is simulated by a flexible vorticity sheet of prescribed strength. Starting from an arbitrary first guess for the body shape, normally an ellipsoid, the flexible vortex sheet is successively realigned with its own self-induced flow field during an iterative process which converges accurately onto the desired shape. A well-proven analysis method is also presented for back-checking the final design.
NASA Technical Reports Server (NTRS)
Gong, J.; Volakis, J. L.; Chatterjee, A.; Jin, J. M.
1992-01-01
A hybrid finite element boundary integral formulation is developed using tetrahedral and/or triangular elements for discretizing the cavity and/or aperture of microstrip antenna arrays. The tetrahedral elements with edge based linear expansion functions are chosen for modeling the volume region and triangular elements are used for discretizing the aperture. The edge based expansion functions are divergenceless thus removing the requirement to introduce a penalty term and the tetrahedral elements permit greater geometrical adaptability than the rectangular bricks. The underlying theory and resulting expressions are discussed in detail together with some numerical scattering examples for comparison and demonstration.
NASA Technical Reports Server (NTRS)
Collins, J. D.; Volakis, John L.
1992-01-01
A method that combines the finite element and boundary integral techniques for the numerical solution of electromagnetic scattering problems is presented. The finite element method is well known for requiring a low order storage and for its capability to model inhomogeneous structures. Of particular emphasis in this work is the reduction of the storage requirement by terminating the finite element mesh on a boundary in a fashion which renders the boundary integrals in convolutional form. The fast Fourier transform is then used to evaluate these integrals in a conjugate gradient solver, without a need to generate the actual matrix. This method has a marked advantage over traditional integral equation approaches with respect to the storage requirement of highly inhomogeneous structures. Rectangular, circular, and ogival mesh termination boundaries are examined for two-dimensional scattering. In the case of axially symmetric structures, the boundary integral matrix storage is reduced by exploiting matrix symmetries and solving the resulting system via the conjugate gradient method. In each case several results are presented for various scatterers aimed at validating the method and providing an assessment of its capabilities. Important in methods incorporating boundary integral equations is the issue of internal resonance. A method is implemented for their removal, and is shown to be effective in the two-dimensional and three-dimensional applications.
Nichols, D.J.; Brown, J.L.; Attrep, M., Jr.; Orth, C.J.
1992-01-01
A newly discovered Cretaceous-Tertiary (K-T) boundary locality in the western Powder River basin, Wyoming, is characterized by a palynologically defined extinction horizon, a fern-spore abundance anomaly, a strong iridium anomaly, and shock-metamorphosed quartz grains. Detailed microstratigraphic analyses show that about one third of the palynoflora (mostly angiosperm pollen) disappeared abruptly, placing the K-T boundary within a distinctive, 1- to 2-cm-thick claystone layer. Shocked quartz grains are concentrated at the top of this layer, and although fern-spore and iridium concentrations are high in this layer, they reach their maximum concentrations in a 2-cm-thick carbonaceous claystone that overlies the boundary claystone layer. The evidence supports the theory that the K-T boundary event was associated with the impact of an extraterrestrial body or bodies. Palynological analyses of samples from the K-T boundary interval document extensive changes in the flora that resulted from the boundary event. The palynologically and geochemically defined K-T boundary provides a unique time-line of use in regional basin analysis. ?? 1992.
Simplified model for determining local heat flux boundary conditions for slagging wall
Bingzhi Li; Anders Brink; Mikko Hupa
2009-07-15
In this work, two models for calculating heat transfer through a cooled vertical wall covered with a running slag layer are investigated. The first one relies on a discretization of the velocity equation, and the second one relies on an analytical solution. The aim is to find a model that can be used for calculating local heat flux boundary conditions in computational fluid dynamics (CFD) analysis of such processes. Two different cases where molten deposits exist are investigated: the black liquor recovery boiler and the coal gasifier. The results show that a model relying on discretization of the velocity equation is more flexible in handling different temperature-viscosity relations. Nevertheless, a model relying on an analytical solution is the one fast enough for a potential use as a CFD submodel. Furthermore, the influence of simplifications to the heat balance in the model is investigated. It is found that simplification of the heat balance can be applied when the radiation heat flux is dominant in the balance. 9 refs., 7 figs., 10 tabs.
A locally stabilized immersed boundary method for the compressible Navier-Stokes equations
NASA Astrophysics Data System (ADS)
Brehm, C.; Hader, C.; Fasel, H. F.
2015-08-01
A higher-order immersed boundary method for solving the compressible Navier-Stokes equations is presented. The distinguishing feature of this new immersed boundary method is that the coefficients of the irregular finite-difference stencils in the vicinity of the immersed boundary are optimized to obtain improved numerical stability. This basic idea was introduced in a previous publication by the authors for the advection step in the projection method used to solve the incompressible Navier-Stokes equations. This paper extends the original approach to the compressible Navier-Stokes equations considering flux vector splitting schemes and viscous wall boundary conditions at the immersed geometry. In addition to the stencil optimization procedure for the convective terms, this paper discusses other key aspects of the method, such as imposing flux boundary conditions at the immersed boundary and the discretization of the viscous flux in the vicinity of the boundary. Extensive linear stability investigations of the immersed scheme confirm that a linearly stable method is obtained. The method of manufactured solutions is used to validate the expected higher-order accuracy and to study the error convergence properties of this new method. Steady and unsteady, 2D and 3D canonical test cases are used for validation of the immersed boundary approach. Finally, the method is employed to simulate the laminar to turbulent transition process of a hypersonic Mach 6 boundary layer flow over a porous wall and subsonic boundary layer flow over a three-dimensional spherical roughness element.
NASA Technical Reports Server (NTRS)
Young, D. P.; Woo, A. C.; Bussoletti, J. E.; Johnson, F. T.
1986-01-01
A general method is developed combining fast direct methods and boundary integral equation methods to solve Poisson's equation on irregular exterior regions. The method requires O(N log N) operations where N is the number of grid points. Error estimates are given that hold for regions with corners and other boundary irregularities. Computational results are given in the context of computational aerodynamics for a two-dimensional lifting airfoil. Solutions of boundary integral equations for lifting and nonlifting aerodynamic configurations using preconditioned conjugate gradient are examined for varying degrees of thinness.
Efficient solution of time-domain boundary integral equations arising in sound-hard scattering
NASA Astrophysics Data System (ADS)
Veit, Alexander; Merta, Michal; Zapletal, Jan; Lukáš, Dalibor
2016-08-01
We consider the efficient numerical solution of the three-dimensional wave equation with Neumann boundary conditions via time-domain boundary integral equations. A space-time Galerkin method with $C^\\infty$-smooth, compactly supported basis functions in time and piecewise polynomial basis functions in space is employed. We discuss the structure of the system matrix and its efficient parallel assembly. Different preconditioning strategies for the solution of the arising systems with block Hessenberg matrices are proposed and investigated numerically. Furthermore, a C++ implementation parallelized by OpenMP and MPI in shared and distributed memory, respectively, is presented. The code is part of the boundary element library BEM4I. Results of numerical experiments including convergence and scalability tests up to a thousand cores on a cluster are provided. The presented implementation shows good parallel scalability of the system matrix assembly. Moreover, the proposed algebraic preconditioner in combination with the FGMRES solver leads to a significant reduction of the computational time.
Analysis of mixed-mode crack propagation using the boundary integral method
NASA Technical Reports Server (NTRS)
Mendelson, A.; Ghosn, L. J.
1986-01-01
Crack propagation in a rotating inner raceway of a high speed roller bearing is analyzed using the boundary integral equation method. The method consists of an edge crack in a plate under tension, upon which varying Hertzian stress fields are superimposed. A computer program for the boundary integral equation method was written using quadratic elements to determine the stress and displacement fields for discrete roller positions. Mode I and Mode II stress intensity factors and crack extension forces G sub 00 (energy release rate due to tensile opening mode) and G sub r0 (energy release rate due to shear displacement mode) were computed. These calculations permit determination of that crack growth angle for which the change in the crack extension forces is maximum. The crack driving force was found to be the alternating mixed-mode loading that occurs with each passage of the most heavily loaded roller. The crack is predicted to propagate in a step-like fashion alternating between radial and inclined segments, and this pattern was observed experimentally. The maximum changes DeltaG sub 00 and DeltaG sub r0 of the crack extension forces are found to be good measures of the crack propagation rate and direction.
A coupled finite-element, boundary-integral method for simulating ultrasonic flowmeters.
Bezdĕk, Michal; Landes, Hermann; Rieder, Alfred; Lerch, Reinhard
2007-03-01
Today's most popular technology of ultrasonic flow measurement is based on the transit-time principle. In this paper, a numerical simulation technique applicable to the analysis of transit-time flowmeters is presented. A flowmeter represents a large simulation problem that also requires computation of acoustic fields in moving media. For this purpose, a novel boundary integral method, the Helmholtz integral-ray tracing method (HIRM), is derived and validated. HIRM is applicable to acoustic radiation problems in arbitrary mean flows at low Mach numbers and significantly reduces the memory demands in comparison with the finite-element method (FEM). It relies on an approximate free-space Green's function which makes use of the ray tracing technique. For simulation of practical acoustic devices, a hybrid simulation scheme consisting of FEM and HIRM is proposed. The coupling of FEM and HIRM is facilitated by means of absorbing boundaries in combination with a new, reflection-free, acoustic-source formulation. Using the coupled FEM-HIRM scheme, a full three-dimensional (3-D) simulation of a complete transit-time flowmeter is performed for the first time. The obtained simulation results are in good agreement with measurements both at zero flow and under flow conditions. PMID:17375833
NASA Astrophysics Data System (ADS)
Kumar, Mohit; Basu, Tanmoy; Som, Tapobrata
2016-01-01
In this paper, based on piezoforce measurements, we show the presence of opposite polarization at grains and grain boundaries of Al-doped ZnO (AZO). The polarization can be flipped by 180° in phase by switching the polarity of the applied electric field, revealing the existence of nanoscale pseudoferroelectricity in AZO grown on Pt/TiO2/SiO2/Si substrate. We also demonstrate an experimental evidence on local band bending at grain boundaries of AZO films using conductive atomic force microscopy and Kelvin probe force microscopy. The presence of an opposite polarization at grains and grain boundaries gives rise to a polarization-driven barrier formation at grain boundaries. With the help of conductive atomic force microscopy, we show that the polarization-driven barrier along with the defect-induced electrostatic potential barrier account for the measured local band bending at grain boundaries. The present study opens a new avenue to understand the charge transport in light of both polarization and electrostatic effects.
Solution of Poisson's Equation with Global, Local and Nonlocal Boundary Conditions
ERIC Educational Resources Information Center
Aliev, Nihan; Jahanshahi, Mohammad
2002-01-01
Boundary value problems (BVPs) for partial differential equations are common in mathematical physics. The differential equation is often considered in simple and symmetric regions, such as a circle, cube, cylinder, etc., with global and separable boundary conditions. In this paper and other works of the authors, a general method is used for the…
NASA Technical Reports Server (NTRS)
Schowalter, D. G.; DeCroix, D. S.; Lin, Y. L.; Arya, S. P.; Kaplan, M. L.
1996-01-01
It was found that the homogeneity of the surface drag coefficient plays an important role in the large scale structure of turbulence in large-eddy simulation of the convective atmospheric boundary layer. Particularly when a ground surface temperature was specified, large horizontal anisotropies occurred when the drag coefficient depended upon local velocities and heat fluxes. This was due to the formation of streamwise roll structures in the boundary layer. In reality, these structures have been found to form when shear is approximately balanced by buoyancy. The present cases, however, were highly convective. The formation was caused by particularly low values of the drag coefficient at the entrance to thermal plume structures.
NASA Technical Reports Server (NTRS)
Mager, Arthur
1952-01-01
The Navier-Stokes equations of motion and the equation of continuity are transformed so as to apply to an orthogonal curvilinear coordinate system rotating with a uniform angular velocity about an arbitrary axis in space. A usual simplification of these equations as consistent with the accepted boundary-layer theory and an integration of these equations through the boundary layer result in boundary-layer momentum-integral equations for three-dimensional flows that are applicable to either rotating or nonrotating fluid boundaries. These equations are simplified and an approximate solution in closed integral form is obtained for a generalized boundary-layer momentum-loss thickness and flow deflection at the wall in the turbulent case. A numerical evaluation of this solution carried out for data obtained in a curving nonrotating duct shows a fair quantitative agreement with the measures values. The form in which the equations are presented is readily adaptable to cases of steady, three-dimensional, incompressible boundary-layer flow like that over curved ducts or yawed wings; and it also may be used to describe the boundary-layer flow over various rotating surfaces, thus applying to turbomachinery, propellers, and helicopter blades.
RF photonic front-end integrating with local oscillator loop.
Yu, H; Chen, M; Gao, H; Yang, S; Chen, H; Xie, S
2014-02-24
Broadband Radio frequency (RF) photonic front-ends are one of the vital applications of the microwave photonics. A tunable and broadband RF photonic front-end integrating with the optoelectronic oscillator (OEO) based local oscillator has been proposed and experimentally demonstrated, in which only one phase modulator (PM) is employed thanks to the characteristic of the PM. The silicon-on-insulator based narrow-bandwidth band-pass filter is introduced for signal processing. The application condition of the proposed RF photonic front-end has been discussed and the performance of the front-end has also been measured. The SFDR at a frequency of about 7.02 GHz is measured to be 88.6 dB-Hz(2/3). PMID:24663712
Local and Global Illumination in the Volume Rendering Integral
Max, N; Chen, M
2005-10-21
This article is intended as an update of the major survey by Max [1] on optical models for direct volume rendering. It provides a brief overview of the subject scope covered by [1], and brings recent developments, such as new shadow algorithms and refraction rendering, into the perspective. In particular, we examine three fundamentals aspects of direct volume rendering, namely the volume rendering integral, local illumination models and global illumination models, in a wavelength-independent manner. We review the developments on spectral volume rendering, in which visible light are considered as a form of electromagnetic radiation, optical models are implemented in conjunction with representations of spectral power distribution. This survey can provide a basis for, and encourage, new efforts for developing and using complex illumination models to achieve better realism and perception through optical correctness.
NASA Astrophysics Data System (ADS)
Steich, David James
1995-01-01
The Finite Difference Time Domain (FDTD) method is a simple yet powerful method for numerically solving electromagnetic wave phenomenon on computers. The FDTD technique discretizes Maxwell's equations with finite difference equations. These finite difference equations, which approximate local field behavior, are applied to large spatial lattices allowing calculation of a vast array of electromagnetical phenomenon. The greatest strengths of the FDTD method are in its simplicity, efficiency, and diversity. FDTD is capable of modeling the scattering and coupling to lossy dielectrics, lossy magnetics, anisotropic media, dispersive media, and nonlinear materials for general geometric shapes. Wideband frequency information can be obtained using FDTD for both near and far field observation points in a single computational run. However, along with all of its benefits, the FDTD algorithm has some deficiencies. For most problems of interest, poor accuracy at geometry interfaces of differing media and at outer problem space boundarys where the spatial lattice must be truncated are the two largest error sources of the FDTD algorithm. Although most accuracy issues can be circumvented by expending large amounts of computer memory and cpu time, using excessive computer resources is not always possible and is never appealing. The purpose of this thesis is to generalize, analyze, and test various mainstream local Outer Radiating Boundary Conditions (ORBCs) for the FDTD method applied to Maxwell's equations in order to help gain a better understanding of present ORBC limitations. A common mathematical model is presented for the boundary conditions. Boundary conditions shown to fit the model include Mur, Superabsorption, Liao, Higdon, and Lindman ORBCs of varying orders. Simple operators are defined and then used to generate the final discretized equations for each of the boundary conditions, automatically, without requiring complicated high order equations. The procedure also allows
NASA Astrophysics Data System (ADS)
Yang, Xiang; Sadique, Jasim; Mittal, Rajat; Meneveau, Charles
2014-11-01
A new wall model for Large-Eddy-Simulations is proposed. It is based on an integral boundary layer method that assumes a functional form for the local mean velocity profile. The method, iWMLES, evaluates required unsteady and advective terms in the vertically integrated boundary layer equations analytically. The assumed profile contains a viscous or roughness sublayer, and a logarithmic layer with an additional linear term accounting for inertial and pressure gradient effects. The iWMLES method is tested in the context of a finite difference LES code. Test cases include developing turbulent boundary layers on a smooth flat plate at various Reynolds numbers, over flat plates with unresolved roughness, and a sample application to boundary layer flow over a plate that includes resolved roughness elements. The elements are truncated cones acting as idealized barnacle-like roughness elements that often occur in biofouling of marine surfaces. Comparisons with data show that iWMLES provides accurate predictions of near-wall velocity profiles in LES while, similarly to equilibrium wall models, its cost remains independent of Reynolds number and is thus significantly lower compared to standard zonal or hybrid wall models. This work is funded by ONR Grant N00014-12-1-0582 (Dr. R. Joslin, program manager).
Ellipsoidally-shaped local absorbing boundaries for three-dimensional scalar wave propagation
NASA Astrophysics Data System (ADS)
Kallivokas, L. F.; Lee, S.
2004-12-01
In this paper we discuss the performance of second-order absorbing conditions prescribed on ellipsoidally-shaped truncation boundaries for the resolution of scalar wave phenomena in three dimensions. The second-order conditions employed herein belong to a larger class of arbitrarily-shaped convex absorbing boundaries developed earlier [21] for acoustic scattering and radiation problems in unbounded domains. In [21] we discussed their performance when used on spherical truncation boundaries for applications in both the time- and frequency-domains. Here, we extend their applicability to ellipsoidal geometries and demonstrate that significant computational savings are attainable due to the reduced computational domain afforded by the ellipsoid.
Lee, Yong Woo; Lee, Duck Joo
2014-12-01
Kirchhoff's formula for the convective wave equation is derived using the generalized function theory. The generalized convective wave equation for a stationary surface is obtained, and the integral formulation, the convective Kirchhoff's formula, is derived. The formula has a similar form to the classical Kirchhoff's formula, but an additional term appears due to a moving medium effect. For convenience, the additional term is manipulated to a final form as the classical Kirchhoff's formula. The frequency domain boundary integral can be obtained from the current time domain boundary integral form. The derived formula is verified by comparison with the analytic solution of source in the uniform flow. The formula is also utilized as a boundary integral equation. Time domain boundary element method (BEM) analysis using the boundary integral equation is conducted, and the results show good agreement with the analytical solution. The formula derived here can be useful for sound radiation and scattering by arbitrary bodies in a moving medium in the time domain. PMID:25480045
NASA Technical Reports Server (NTRS)
Jin, Jian-Ming; Volakis, John L.; Collins, Jeffery D.
1991-01-01
A review of a hybrid finite element-boundary integral formulation for scattering and radiation by two- and three-dimensional composite structures is presented. In contrast to other hybrid techniques involving the finite element method, the proposed one is in principle exact and can be implemented using a low O(N) storage. This is of particular importance for large scale applications and is a characteristic of the boundary chosen to terminate the finite element mesh, usually as close to the structure as possible. A certain class of these boundaries lead to convolutional boundary integrals which can be evaluated via the fast Fourier transform (FFT) without a need to generate a matrix; thus, retaining the O(N) storage requirement. The paper begins with a general description of the method. A number of two- and three-dimensional applications are then given, including numerical computations which demonstrate the method's accuracy, efficiency, and capability.
An efficient boundary integral formulation for flow through fractured porous media
Lough, M.F.; Lee, S.H.; Kamath, J.
1998-07-01
In this paper the authors present a new model for flow in fractured porous media. They formulate the model in terms of a coupled system of boundary integral equations and present an efficient procedure for solving the equations using the boundary element method. In the new model, the flow in the matrix is governed by the usual Darcy law for porous media, with the fractures being treated as planar sources embedded in the matrix. The flow in an individual fracture is governed by a two-dimensional Darcy law (as in a Hele-Shaw cell), with an associated planar sink distribution. The essential feature of this approach is that the fractures are treated as special planes rather than narrow-gap voids. The error in the resulting system of equations is on the order of an intrinsic dimensionless parameter (the ratio of the fracture gap size to the scale of the volume under consideration). They also describe how they adapt the new model to compute effective grid block permeabilities. This was the principal motivation behind the development of the new model. Using effective grid block permeabilities to model flow in fractured oil and gas reservoirs is a much more efficient process than modeling the flow when every fracture is precisely represented. They present some numerical examples that illustrate the new flow model and how it is used to model flow in a reservoir.
Advances in the study of boundary value problems for nonlinear integrable PDEs
NASA Astrophysics Data System (ADS)
Pelloni, Beatrice
2015-02-01
In this review I summarize some of the most significant advances of the last decade in the analysis and solution of boundary value problems for integrable partial differential equations (PDEs) in two independent variables. These equations arise widely in mathematical physics, and in order to model realistic applications, it is essential to consider bounded domain and inhomogeneous boundary conditions. I focus specifically on a general and widely applicable approach, usually referred to as the unified transform or Fokas transform, that provides a substantial generalization of the classical inverse scattering transform. This approach preserves the conceptual efficiency and aesthetic appeal of the more classical transform approaches, but presents a distinctive and important difference. While the inverse scattering transform follows the ‘separation of variables’ philosophy, albeit in a nonlinear setting, the unified transform is based on the idea of synthesis, rather than separation, of variables. I will outline the main ideas in the case of linear evolution equations, and then illustrate their generalization to certain nonlinear cases of particular significance.
NASA Astrophysics Data System (ADS)
Shen, Yongxing; Barnett, David M.; Pinsky, Peter M.
2008-02-01
Kelvin probe force microscopy (KPFM) is designed for measuring the tip-sample contact potential differences by probing the sample surface, measuring the electrostatic interaction, and adjusting a feedback circuit. However, for the case of a dielectric (insulating) sample, the contact potential difference may be ill defined, and the KPFM probe may be sensing electrostatic interactions with a certain distribution of sample trapped charges or dipoles, leading to difficulty in interpreting the images. We have proposed a general framework based on boundary integral equations for simulating the KPFM image based on the knowledge about the sample charge distributions (forward problem) and a deconvolution algorithm solving for the trapped charges on the surface from an image (inverse problem). The forward problem is a classical potential problem, which can be efficiently solved using the boundary element method. Nevertheless, the inverse problem is ill posed due to data incompleteness. For some special cases, we have developed deconvolution algorithms based on the forward problem solution. As an example, this algorithm is applied to process the KPFM image of a gadolinia-doped ceria thin film to solve for its surface charge density, which is a more relevant quantity for samples of this kind than the contact potential difference (normally only defined for conductive samples) values contained in the raw image.
Integrating remote sensing and GIS data for the Natural Systems Boundary (NSB) model
Leary, T.J.; Flamm, R.O.; Haddad, K.D.
1997-06-01
Significant alterations in hydrology, water quality, and land use have put the entire south Florida ecosystem on the brink of collapse. Considerable federal, state, and local efforts have focused on this region to develop and implement management options for environmental and economic restoration and sustainability. The Governor`s Commission for a Sustainable South Florida was created to represent a broad array of interests in the region and is charged with setting the state is vision, direction, and management options for an environmentally and economically sustainable south Florida ecosystem. The Commission`s Science Research Advisory Committee (SRAC) was given the responsibility of delineating and evaluating alternative natural system boundaries. To meet the Commission`s recommendations, the SRAC empowered the Florida Marine Research Institute (FMR1) to develop a GIS-based modeling application. The resulting ARCVIEW application allows managers and scientists to delineate alternative Natural Systems Boundaries (NSBs) by varying the selection and weight (relative importance) of management criteria such as hydrology, habitat, wildlife, and water quality. Repetitive model runs with modifications to the user-defined inputs afford managers the opportunity to better understand the complexity of the data and their relationship to management objectives.
A Family of Well-Clear Boundary Models for the Integration of UAS in the NAS
NASA Technical Reports Server (NTRS)
Munoz, Cesar A.; Narkawicz, Anthony; Chamberlain, James; Consiglio, Maria; Upchurch, Jason
2014-01-01
The FAA-sponsored Sense and Avoid Workshop for Unmanned Aircraft Systems (UAS) defines the concept of sense and avoid for remote pilots as "the capability of a UAS to remain well clear from and avoid collisions with other airborne traffic." Hence, a rigorous definition of well clear is fundamental to any separation assurance concept for the integration of UAS into civil airspace. This paper presents a family of well-clear boundary models based on the TCAS II Resolution Advisory logic. For these models, algorithms that predict well-clear violations along aircraft current trajectories are provided. These algorithms are analogous to conflict detection algorithms but instead of predicting loss of separation, they predict whether well-clear violations will occur during a given lookahead time interval. Analytical techniques are used to study the properties and relationships satisfied by the models.
Prediction of metallic nano-optical trapping forces by finite element-boundary integral method.
Pan, Xiao-Min; Xu, Kai-Jiang; Yang, Ming-Lin; Sheng, Xin-Qing
2015-03-01
The hybrid of finite element and boundary integral (FE-BI) method is employed to predict nano-optical trapping forces of arbitrarily shaped metallic nanostructures. A preconditioning strategy is proposed to improve the convergence of the iterative solution. Skeletonization is employed to speed up the design and optimization where iteration has to be repeated for each beam configuration. The radiation pressure force (RPF) is computed by vector flux of the Maxwell's stress tensor. Numerical simulations are performed to validate the developed method in analyzing the plasmonic effects as well as the optical trapping forces. It is shown that the proposed method is capable of predicting the trapping forces of complex metallic nanostructures accurately and efficiently. PMID:25836836
Boundary integral equation method calculations of surface regression effects in flame spreading
NASA Technical Reports Server (NTRS)
Altenkirch, R. A.; Rezayat, M.; Eichhorn, R.; Rizzo, F. J.
1982-01-01
A solid-phase conduction problem that is a modified version of one that has been treated previously in the literature and is applicable to flame spreading over a pyrolyzing fuel is solved using a boundary integral equation (BIE) method. Results are compared to surface temperature measurements that can be found in the literature. In addition, the heat conducted through the solid forward of the flame, the heat transfer responsible for sustaining the flame, is also computed in terms of the Peclet number based on a heated layer depth using the BIE method and approximate methods based on asymptotic expansions. Agreement between computed and experimental results is quite good as is agreement between the BIE and the approximate results.
Argani, L P; Bigoni, D; Capuani, D; Movchan, N V
2014-09-01
The infinite-body three-dimensional Green's function set (for incremental displacement and mean stress) is derived for the incremental deformation of a uniformly strained incompressible, nonlinear elastic body. Particular cases of the developed formulation are the Mooney-Rivlin elasticity and the J2-deformation theory of plasticity. These Green's functions are used to develop a boundary integral equation framework, by introducing an ad hoc potential, which paves the way for a boundary element formulation of three-dimensional problems of incremental elasticity. Results are used to investigate the behaviour of a material deformed near the limit of ellipticity and to reveal patterns of shear failure. In fact, within the investigated three-dimensional framework, localized deformations emanating from a perturbation are shown to be organized in conical geometries rather than in planar bands, so that failure is predicted to develop through curved and thin surfaces of intense shearing, as can for instance be observed in the cup-cone rupture of ductile metal bars. PMID:25197258
NASA Technical Reports Server (NTRS)
Goldman, L. J.; Augler, R. E.
1980-01-01
A generalized analysis to predict the two-dimensional aerodynamic losses of film-cooled vanes by using integral boundary-layer parameters is presented. Heat-transfer and trailing-edge injection effects are included in the method. An approximate solution of the generalized equations is also included to show more clearly the effect of the different boundary-layer and cooling parameters on the losses. The analytical predictions agree well with the experimental results, indicating that available boundary-layer calculations for cooled vanes are of sufficient accuracy to use in the prediction method.
Andrews, D.J.
1985-01-01
A numerical boundary integral method, relating slip and traction on a plane in an elastic medium by convolution with a discretized Green function, can be linked to a slip-dependent friction law on the fault plane. Such a method is developed here in two-dimensional plane-strain geometry. Spontaneous plane-strain shear ruptures can make a transition from sub-Rayleigh to near-P propagation velocity. Results from the boundary integral method agree with earlier results from a finite difference method on the location of this transition in parameter space. The methods differ in their prediction of rupture velocity following the transition. The trailing edge of the cohesive zone propagates at the P-wave velocity after the transition in the boundary integral calculations. Refs.
NASA Astrophysics Data System (ADS)
Shen, Y. Q.; Sun, Z. J.; Kromann, R.; Holst, T.; Vase, P.; Freloft, T.
1995-10-01
We have fabricated and tested integrated magnetometers based on the superconducting quantum interference device (SQUID). The magnetometer consists of two patterned films of YBa2Cu3O7, separated by an insulating layer of SrTiO3. A multiturn input coil was integrated on top of the SQUID, where the misorientation angle in a SrTiO3 bicrystal substrate was used to form the grain boundary junctions. The noise spectrum was characterized at 77 K and showed that above 10 Hz the magnetometer sensitivity is limited by a white noise level of around 4×10-5 Φ0/Hz1/2. In the 4 mm × 4 mm detection area of the input coil, this translates into a magnetic field sensitivity of 320 fT/ Hz1/2 at 100 Hz. Compared to the theoretical value of an optimized SQUID the white noise level of the magnetometer is two times higher. Below 10 Hz the noise is dominated by 1/f noise mainly due to the critical current fluctuations.
Local Melatoninergic System as the Protector of Skin Integrity
Slominski, Andrzej T.; Kleszczyński, Konrad; Semak, Igor; Janjetovic, Zorica; Żmijewski, Michał A.; Kim, Tae-Kang; Slominski, Radomir M.; Reiter, Russel J.; Fischer, Tobias W.
2014-01-01
The human skin is not only a target for the protective actions of melatonin, but also a site of melatonin synthesis and metabolism, suggesting an important role for a local melatoninergic system in protection against ultraviolet radiation (UVR) induced damages. While melatonin exerts many effects on cell physiology and tissue homeostasis via membrane bound melatonin receptors, the strong protective effects of melatonin against the UVR-induced skin damage including DNA repair/protection seen at its high (pharmocological) concentrations indicate that these are mainly mediated through receptor-independent mechanisms or perhaps through activation of putative melatonin nuclear receptors. The destructive effects of the UVR are significantly counteracted or modulated by melatonin in the context of a complex intracutaneous melatoninergic anti-oxidative system with UVR-enhanced or UVR-independent melatonin metabolites. Therefore, endogenous intracutaneous melatonin production, together with topically-applied exogenous melatonin or metabolites would be expected to represent one of the most potent anti-oxidative defense systems against the UV-induced damage to the skin. In summary, we propose that melatonin can be exploited therapeutically as a protective agent or as a survival factor with anti-genotoxic properties or as a “guardian” of the genome and cellular integrity with clinical applications in UVR-induced pathology that includes carcinogenesis and skin aging. PMID:25272227
NASA Astrophysics Data System (ADS)
Li, Jing; Zeng, Zhaofa; Huang, Ling; Liu, Fengshan
2012-12-01
When applying the finite difference time domain (FDTD) method in Ground Penetrating Radar (GPR) simulation, the absorbing boundary conditions (ABC) are used to mitigate undesired reflection that can arise at the model's truncation boundaries. The classical PML boundary can make spurious reflection for the waves, such as reaching to the PML interface with near-grazing angles, low frequency waves or evanescent waves. The non-split complex frequency shifted PML which base on recursive integration (CFS-RIPML) has a good absorption effect for these interference waves. Meanwhile, the recursive integration, which does not need split field component, can overcome the shortcoming of CFS technique that needs more intermediate variable and large memory. In addition, the high-order FDTD can improve calculation accuracy and reduce the error caused by numerical dispersion effectively. In this paper, we derive the 3D high-order FDTD method with CFS-RIPML boundary and apply it in GPR simulation. The results show that the CFS-RIPML has significantly better absorption effect and lower reflections error than UPML and PML boundary. Compared with the two-order, the high-order FDTD can improve calculation accuracy effectively with the same grid size. Combination with CFS-RIPML boundary and high-order FDTD can improve the reliability and calculation accuracy of GPR and other geophysics numerical simulation.
NASA Astrophysics Data System (ADS)
Zou, Y.; Nishimura, Y.; Lyons, L. R.; Shiokawa, K.; Donovan, E.; Ruohoniemi, J. M.; McWilliams, K. A.; Nishitani, N.
2014-12-01
Previous radar observations have shown that polar cap flows are highly structured and that localized flow enhancements are related to nightside auroral disturbances. However, such studies are limited to available echo regions. Utilizing wide spatial coverage by an all-sky imager at Resolute Bay and simultaneous SuperDARN radar measurements, we determined properties of such localized flow enhancements and their statistical association with nightside auroral activity. We found that narrow flow enhancements are well collocated with airglow patches with substantially larger velocities (>~200 m/s up to ~700 m/s) than the weak large-scale polar cap convection. The flow widths are similar to the patch widths. During the evolution across nightside the polar cap, the flow directions and speeds are consistent with the patch propagation directions and speeds. These correspondences indicate that patches can visualize localized flow enhancements reflecting the flow width, speed and direction. Such associations were prevalent (~67%) in our survey and tended to be observed under By-dominated IMF. The typical flow channel speed, propagation time, and width within our observation areas were 600 m/s, tens of minutes, and 200-300 km, respectively. Localized flow enhancements were usually observed as a channel elongated in the noon-midnight meridian and directed towards pre-midnight (post-midnight) for +By (-By), and accounted for ~10-40% of the plasma transport across the entire polar cap. Utilizing airglow patches as tracers of localized flow enhancements, we also found that as localized polar cap structures move across the polar cap and impinge on the poleward boundary of the nightside auroral oval, they are followed by poleward boundary intensifications (PBIs), which can extend equatorward as auroral streamers, some of which further propagate equatorward and are followed by a substorm auroral onset. This suggests that localized flow enhancements within the polar cap can contribute
NASA Technical Reports Server (NTRS)
Kojima, Fumio
1989-01-01
The geometrical structure of the boundary shape for a two-dimensional boundary value problem is identified. The output least square identification method is considered for estimating partially unknown boundary shapes. A numerical parameter estimation technique using the spline collocation method is proposed.
NASA Astrophysics Data System (ADS)
Zhang, Hui; Cesnik, Carlos E. S.
2016-04-01
Local interaction simulation approach (LISA) is a highly parallelizable numerical scheme for guided wave simulation in structural health monitoring (SHM). This paper addresses the issue of simulating wave propagation in unbounded domain through the implementation of non-reflective boundary (NRB) in LISA. In this study, two different categories of NRB, i.e., the non-reflective boundary condition (NRBC) and the absorbing boundary layer (ABL), have been investigated in the parallelized LISA scheme. For the implementation of NRBC, a set of general LISA equations considering the effect from boundary stress is obtained first. As a simple example, the Lysmer and Kuhlemeyer (L-K) model is applied here to demonstrate the easiness of NRBC implementation in LISA. As a representative of ABL implementation, the LISA scheme incorporating the absorbing layers with increasing damping (ALID) is also proposed, based on elasto-dynamic equations considering damping effect. Finally, an effective hybrid model combining L-K and ALID methods in LISA is developed, and guidelines for implementing the hybrid model is presented. Case studies on a three-dimensional plate model compares the performance of hybrid method to that of L-K and ALID acting independently. The simulation results demonstrate that best absorbing efficiency is achieved with the hybrid method.
Carrington, David Bradley; Monayem, A. K. M.; Mazumder, H.; Heinrich, Juan C.
2015-03-05
A three-dimensional finite element method for the numerical simulations of fluid flow in domains containing moving rigid objects or boundaries is developed. The method falls into the general category of Arbitrary Lagrangian Eulerian methods; it is based on a fixed mesh that is locally adapted in the immediate vicinity of the moving interfaces and reverts to its original shape once the moving interfaces go past the elements. The moving interfaces are defined by separate sets of marker points so that the global mesh is independent of interface movement and the possibility of mesh entanglement is eliminated. The results is a fully robust formulation capable of calculating on domains of complex geometry with moving boundaries or devises that can also have a complex geometry without danger of the mesh becoming unsuitable due to its continuous deformation thus eliminating the need for repeated re-meshing and interpolation. Moreover, the boundary conditions on the interfaces are imposed exactly. This work is intended to support the internal combustion engines simulator KIVA developed at Los Alamos National Laboratories. The model's capabilities are illustrated through application to incompressible flows in different geometrical settings that show the robustness and flexibility of the technique to perform simulations involving moving boundaries in a three-dimensional domain.
Prototype Local Data Integration System and Central Florida Data Deficiency
NASA Technical Reports Server (NTRS)
Manobianco, John; Case, Jonathan
1998-01-01
This report describes the Applied Meteorology Unit's (AMU) task on the Local Data Integration System (LDIS) and central Florida data deficiency. The objectives of the task are to identify all existing meteorological data sources within 250 km of the Kennedy Space Center (KSC) and the Eastern Range at Cape Canaveral Air Station (CCAS), identify and configure an appropriate LDIS to integrate these data, and implement a working prototype to be used for limited case studies and data non-incorporation (DNI) experiments. The ultimate goal for running LDIS is to generate products that may enhance weather nowcasts and short-range (less than 6 h) forecasts issued in support of the 45th Weather Squadron (45 WS), Spaceflight Meteorology Group (SMG), and the Melbourne National Weather Service (NWS MLB) operational requirements. The LDIS has the potential to provide added value for nowcasts and short term forecasts for two reasons. First, it incorporates all data operationally available in east central Florida. Second, it is run at finer spatial and temporal resolutions than current national-scale operational models. In combination with a suitable visualization tool, LDIS may provide users with a more complete and comprehensive understanding of evolving fine-scale weather features than could be developed by individually examining the disparate data sets over the same area and time. The utility of LDIS depends largely on the reliability and availability of observational data. Therefore, it is important to document all existing meteorological data sources around central Florida that can be incorporated by it. Several factors contribute to the data density and coverage over east central Florida including the level in the atmosphere, distance from KSC/CCAS, time, and prevailing weather. The central Florida mesonet consists of existing surface meteorological and hydrological data available from the Tampa NWS and data servers at Miami and Jacksonville. However the utility of these
NASA Astrophysics Data System (ADS)
Khalilov, E. H.
2016-07-01
The surface integral equation for a spatial mixed boundary value problem for the Helmholtz equation is considered. At a set of chosen points, the equation is replaced with a system of algebraic equations, and the existence and uniqueness of the solution of this system is established. The convergence of the solutions of this system to the exact solution of the integral equation is proven, and the convergence rate of the method is determined.
NASA Astrophysics Data System (ADS)
Jarvis, Ian
2014-05-01
The Cenomanian-Turonian boundary (CTB) interval ~ 94 Ma represented a period of major global palaeoenvironmental change. Increasingly detailed multidisciplinary studies integrating sedimentological, palaeontological and geochemical data from multiple basins, are enabling the development of refined but complex models that aid understanding of the mechanisms driving changes in ocean productivity and climate. This paper reviews some of the exciting new developments in this field. Facies change characterizes the CTB interval in most areas. In the Chalk seas of northern Europe, a widespead hiatus was followed by the deposition of clay-rich organic-lean beds of the Plenus Marl and its equivalents, and then nodular chalks. In the North Sea basin and its onshore extension in eastern England and northern Germany, black shales of the Black Band (Blodøks Formation, Hasseltal Formation) occur. Similarly, in northern Tethys, a brief interval of black shale accumulation within a predominantly carbonate succession, is exemplified by the Niveau Thomel in the Vocontian Basin (SE France), and the Livello Bonarelli in Italy. Widespread deposition of organic-rich marine sediments during CTB times led to 12C depletion in surface carbon reservoirs (oceans, atmosphere, biosphere), and a large positive global δ13C excursion preserved in marine carbonates and both marine and terrestrial organic matter (Oceanic Anoxic Event 2). Significant biotic turnover characterises the boundary interval, and inter-regional correlation may be achieved at high resolution using integrated biostratigraphy employing macrofossils (ammonites, inoceramid bivalves), microfossils (planktonic foraminifera, dinoflagellate cysts) and calcareous nannofossils. Correlations can be tested against those based on comparison of δ13C profiles - carbon isotope chemostratigraphy, supplemented by oxygen isotope and elemental data. Interpretation of paired carbonate - organic matter δ13C data from multiple CTB sections
NASA Astrophysics Data System (ADS)
Gao, Y.; Balaram, P.; Islam, S.
2009-12-01
Water issues and problems have bewildered humankind for a long time yet a systematic approach for understanding such issues remain elusive. This is partly because many water-related problems are framed from a contested terrain in which many actors (individuals, communities, businesses, NGOs, states, and countries) compete to protect their own and often conflicting interests. We argue that origin of many water problems may be understood as a dynamic consequence of competition, interconnections, and feedback among variables in the Natural and Societal Systems (NSSs). Within the natural system, we recognize that triple constraints on water- water quantity (Q), water quality (P), and ecosystem (E)- and their interdependencies and feedback may lead to conflicts. Such inherent and multifaceted constraints of the natural water system are exacerbated often at the societal boundaries. Within the societal system, interdependencies and feedback among values and norms (V), economy (C), and governance (G) interact in various ways to create intractable contextual differences. The observation that natural and societal systems are linked is not novel. Our argument here, however, is that rigid disciplinary boundaries between these two domains will not produce solutions to the water problems we are facing today. The knowledge needed to address water problems need to go beyond scientific assessment in which societal variables (C, G, and V) are treated as exogenous or largely ignored, and policy research that does not consider the impact of natural variables (E, P, and Q) and that coupling among them. Consequently, traditional quantitative methods alone are not appropriate to address the dynamics of water conflicts, because we cannot quantify the societal variables and the exact mathematical relationships among the variables are not fully known. On the other hand, conventional qualitative study in societal domain has mainly been in the form of individual case studies and therefore
NASA Technical Reports Server (NTRS)
Collins, Jeffery D.; Volakis, John L.
1989-01-01
A new technique is presented for computing the scattering by 2-D structures of arbitrary composition. The proposed solution approach combines the usual finite element method with the boundary integral equation to formulate a discrete system. This is subsequently solved via the conjugate gradient (CG) algorithm. A particular characteristic of the method is the use of rectangular boundaries to enclose the scatterer. Several of the resulting boundary integrals are therefore convolutions and may be evaluated via the fast Fourier transform (FFT) in the implementation of the CG algorithm. The solution approach offers the principle advantage of having O(N) memory demand and employs a 1-D FFT versus a 2-D FFT as required with a traditional implementation of the CGFFT algorithm. The speed of the proposed solution method is compared with that of the traditional CGFFT algorithm, and results for rectangular bodies are given and shown to be in excellent agreement with the moment method.
NASA Astrophysics Data System (ADS)
Friedrich, Johannes; Fetzer, Ingo; Cornell, Sarah
2016-04-01
The planetary boundaries framework is an approach to global sustainability that emphasises non-linear threshold behavior in anthropogenically perturbed Earth system processes. However, knowledge about the characteristics and positions of thresholds, and the scope for management of the boundaries is not well established. Global integrated models can help to improve this understanding, by reflecting the complex feedbacks between human and environmental systems. This study analyses the current state of integrated models with regard to the main processes identified as 'critical Earth system processes' in the planetary boundaries framework, and identifies gaps and suggests priorities for future improvements. Our approach involves creating a common ontology of model descriptions, and performing a network analysis on the state of system integration in models. The distinct clusters of specific biophysical and social-economic systems obviously has enabled progress in those specific areas of global change, but it now constrains analysis of important human-driven Earth system dynamics. The modeling process therefore has to be improved through technical integration, scientific gap-filling, and also changes in scientific institutional dynamics. Combined, this can advance model potentials that may help us to find sustainable pathways within planetary boundaries.
NASA Technical Reports Server (NTRS)
Gokoglu, Suleyman A.
1988-01-01
This paper investigates the role played by vapor-phase chemical reactions on CVD rates by comparing the results of two extreme theories developed to predict CVD mass transport rates in the absence of interfacial kinetic barrier: one based on chemically frozen boundary layer and the other based on local thermochemical equilibrium. Both theories consider laminar convective-diffusion boundary layers at high Reynolds numbers and include thermal (Soret) diffusion and variable property effects. As an example, Na2SO4 deposition was studied. It was found that gas phase reactions have no important role on Na2SO4 deposition rates and on the predictions of the theories. The implications of the predictions of the two theories to other CVD systems are discussed.
Some free boundary problems involving non-local diffusion and aggregation
Carrillo, José Antonio; Vázquez, Juan Luis
2015-01-01
We report on recent progress in the study of evolution processes involving degenerate parabolic equations which may exhibit free boundaries. The equations we have selected follow two recent trends in diffusion theory: considering anomalous diffusion with long-range effects, which leads to fractional operators or other operators involving kernels with large tails; and the combination of diffusion and aggregation effects, leading to delicate long-term equilibria whose description is still incipient. PMID:26261360
NASA Astrophysics Data System (ADS)
Mendoza-Arenas, J. J.; Clark, S. R.; Jaksch, D.
2015-04-01
In this work we analyze the simultaneous emergence of diffusive energy transport and local thermalization in a nonequilibrium one-dimensional quantum system, as a result of integrability breaking. Specifically, we discuss the local properties of the steady state induced by thermal boundary driving in a X X Z spin chain with staggered magnetic field. By means of efficient large-scale matrix product simulations of the equation of motion of the system, we calculate its steady state in the long-time limit. We start by discussing the energy transport supported by the system, finding it to be ballistic in the integrable limit and diffusive when the staggered field is finite. Subsequently, we examine the reduced density operators of neighboring sites and find that for large systems they are well approximated by local thermal states of the underlying Hamiltonian in the nonintegrable regime, even for weak staggered fields. In the integrable limit, on the other hand, this behavior is lost, and the identification of local temperatures is no longer possible. Our results agree with the intuitive connection between energy diffusion and thermalization.
Off-shell amplitudes as boundary integrals of analytically continued Wilson line slope
NASA Astrophysics Data System (ADS)
Kotko, P.; Serino, M.; Stasto, A. M.
2016-08-01
One of the methods to calculate tree-level multi-gluon scattering amplitudes is to use the Berends-Giele recursion relation involving off-shell currents or off-shell amplitudes, if working in the light cone gauge. As shown in recent works using the light-front perturbation theory, solutions to these recursions naturally collapse into gauge invariant and gauge-dependent components, at least for some helicity configurations. In this work, we show that such structure is helicity independent and emerges from analytic properties of matrix elements of Wilson line operators, where the slope of the straight gauge path is shifted in a certain complex direction. This is similar to the procedure leading to the Britto-Cachazo-Feng-Witten (BCFW) recursion, however we apply a complex shift to the Wilson line slope instead of the external momenta. While in the original BCFW procedure the boundary integrals over the complex shift vanish for certain deformations, here they are non-zero and are equal to the off-shell amplitudes. The main result can thus be summarized as follows: we derive a decomposition of a helicity-fixed off-shell current into gauge invariant component given by a matrix element of a straight Wilson line plus a reminder given by a sum of products of gauge invariant and gauge dependent quantities. We give several examples realizing this relation, including the five-point next-to-MHV helicity configuration.
NASA Astrophysics Data System (ADS)
Calvisi, Michael; Manmi, Kawa; Wang, Qianxi
2014-11-01
Ultrasound contrast agents (UCAs) are microbubbles stabilized with a shell typically of lipid, polymer, or protein and are emerging as a unique tool for noninvasive therapies ranging from gene delivery to tumor ablation. The nonspherical dynamics of contrast agents are thought to play an important role in both diagnostic and therapeutic applications, for example, causing the emission of subharmonic frequency components and enhancing the uptake of therapeutic agents across cell membranes and tissue interfaces. A three-dimensional model for nonspherical contrast agent dynamics based on the boundary integral method is presented. The effects of the encapsulating shell are approximated by adapting Hoff's model for thin-shell, spherical contrast agents to the nonspherical case. A high-quality mesh of the bubble surface is maintained by implementing a hybrid approach of the Lagrangian method and elastic mesh technique. Numerical analyses for the dynamics of UCAs in an infinite liquid and near a rigid wall are performed in parameter regimes of clinical relevance. The results show that the presence of a coating significantly reduces the oscillation amplitude and period, increases the ultrasound pressure amplitude required to incite jetting, and reduces the jet width and velocity.
NASA Astrophysics Data System (ADS)
Esmaeilzadeh, Hamid; Arzi, Ezatollah; Légaré, François; Hassani, Alireza
2013-08-01
In this paper, using the boundary integral method (BIM), we simulate the effect of temperature fluctuation on the sensitivity of microstructured optical fibre (MOF) surface plasmon resonance (SPR) sensors. The final results indicate that, as the temperature increases, the refractometry sensitivity of our sensor decreases from 1300 nm/RIU at 0 °C to 1200 nm/RIU at 50 °C, leading to ˜7.7% sensitivity reduction and the sensitivity temperature error of 0.15% °C-1 for this case. These results can be used for biosensing temperature-error adjustment in MOF SPR sensors, since biomaterials detection usually happens in this temperature range. Moreover, the signal-to-noise ratio (SNR) of our sensor decreases from 0.265 at 0 °C to 0.154 at 100 °C with the average reduction rate of ˜0.42% °C-1. The results suggest that at lower temperatures the sensor has a higher SNR.
Boundary integral simulations of dissolving drops in segmented two-phase flows
NASA Astrophysics Data System (ADS)
Ramchandran, Arun; Leary, Thomas
2015-11-01
Recent years have seen an upsurge in the literature reporting the microfluidic measurement of the kinetics of `fast' gas-liquid reactions by recording the shrinkage of bubbles in segmented flows of these gas-liquid combinations in microfluidic channels. A critical aspect of the data analysis in these experiments is the knowledge of how dissolution influences the velocity field in the liquid slug, and hence, the mass transport characteristics. Unfortunately, there is no literature on this connection for dissolving bubbles. Our research addresses this gap using boundary integral simulations. The effects of the dissolution rate on the film thickness and the inter-drop separation are examined as a function of the capillary number and the viscosity ratio. The results demonstrate that dissolution can enhance the degree of mixing appreciably from one slug to the next. A curious result is that the film thickness and the droplet separation distance can change significantly beyond a critical capillary number, producing flow patterns completely different from those known for the undissolving bubble case. These results will guide the selection of operating regimes that enable convenient interpretation of data from experiments to deduce kinetic constants.
A hybrid boundary-integral/thin-sheet equation for subduction modeling
NASA Astrophysics Data System (ADS)
Xu, Bingrui; Ribe, Neil M.
2016-06-01
Subducting oceanic lithosphere is an example of a thin sheet-like object whose characteristic lateral dimension greatly exceeds its thickness. Here we exploit this property to derive a new hybrid boundary-integral/thin sheet (BITS) representation of subduction that combines in a single equation all the forces acting on the sheet: gravity, internal resistance to bending and stretching, and the tractions exerted by the ambient mantle. For simplicity, we limit ourselves to two dimensions. We solve the BITS equations using a discrete Lagrangian approach in which the sheet is represented by a set of vertices connected by edges. Instantaneous solutions for the sinking speed of a slab attached to a trailing flat sheet obey a scaling law of the form V/VStokes = fct(St), where VStokes is a characteristic Stokes sinking speed and St is the sheet's flexural stiffness. Time-dependent solutions for the evolution of the sheet's shape and thickness show that these are controlled by the viscosity ratio between the sheet and its surroundings. An important advantage of the BITS approach is the possibility of generalizing the sheet's rheology, either to a viscosity that varies along the sheet or to a non-Newtonian shear-thinning rheology.
Boundary integral method for interfacial potential flows in unbounded axi-symmetric domains
NASA Astrophysics Data System (ADS)
Tjan, Kuan-Khoon
The numerical simulation of the deformation of a liquid free surface subjected to an impulse (acoustically generated or otherwise) in an axisymmetric semi-infinite domain is considered. Using an inviscid boundary integral formulation, the free surface is evolved under the influence of inertial, interfacial and gravitational forces. Within a range of Atwood ratio, Weber number and Froude number, the evolution eventually led to the ejection of droplets. This research is part of a study of the lung damage caused by ultrasonic imaging. It has been observed in animal experiments that a focused ultrasonic beam can cause lung hemorrhage. A possible explanation is that the hemorrhage is caused by the ejected droplets penetrating gas filled cavities which occurs in the pleural surface of the lungs. It was found that the relationship between Weber number and the size and the velocity of the emitted drop is such that there exists a critical Weber number which maximizes the energy and momentum of the drop. While the objective is to explore alternative damage mechanisms due to ultrasound, the work is not restricted as such. Indeed, the work is concerned with surface tension driven singularities at fluid interface in general. Within this study, different regimes are found and the conditions which define them are summarized with a phase diagram.
T.F. Eibert; J.L. Volakis; Y.E. Erdemli
2002-03-03
Hybrid finite element (FE)--boundary integral (BI) analysis of infinite periodic arrays is extended to include planar multilayered Green's functions. In this manner, a portion of the volumetric dielectric region can be modeled via the finite element method whereas uniform multilayered regions can be modeled using a multilayered Green's function. As such, thick uniform substrates can be modeled without loss of efficiency and accuracy. The multilayered Green's function is analytically computed in the spectral domain and the resulting BI matrix-vector products are evaluated via the fast spectral domain algorithm (FSDA). As a result, the computational cost of the matrix-vector products is kept at O(N). Furthermore, the number of Floquet modes in the expansion are kept very few by placing the BI surfaces within the computational unit cell. Examples of frequency selective surface (FSS) arrays are analyzed with this method to demonstrate the accuracy and capability of the approach. One example involves complicated multilayered substrates above and below an inhomogeneous filter element and the other is an optical ring-slot array on a substrate several hundred wavelengths in thickness. Comparisons with measurements are included.
NASA Astrophysics Data System (ADS)
Farooq, M. U.; Villaurrutia, R.; MacLaren, I.; Kungl, H.; Hoffmann, M. J.; Fundenberger, J.-J.; Bouzy, E.
2008-08-01
Reliable automated orientation mapping of 90° domains in a tetragonal perovskite has been achieved for the first time using both EBSD and TEM-Kikuchi pattern analysis. This has been used to compare local measurements of c/a ratios in PZT with global measurements by X-ray diffraction. The local c/a rations are in broad agreement with the global measurements, but further work is needed to determine whether the small discrepancies are real local variations or are caused by experimental factors.
Singh, Ajay V; Gollner, Michael J
2016-01-01
Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided. PMID:27285827
Singh, Ajay V.; Gollner, Michael J.
2016-01-01
Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided. PMID:27285827
The Amazon river breeze and the local boundary layer. I - Observations
NASA Technical Reports Server (NTRS)
De Oliveira, Amauri P.; Fitzjarrald, David R.
1993-01-01
Observations of the diurnal evolution of the planetary boundary layer over the Amazon rain forest, made at sites close to the confluence of the Solimoes and Negro rivers (approximately at 3 deg S, 60 deg W) near Manaus, Amazonas, Brazil, show the existence of a diurnal rotation of the wind near the surface and the frequent presence of low-level nocturnal wind maxima. These circulations are shown to be plausibly explained as elements of a river and land breeze circulation induced by the thermal contrast between the rivers and the adjacent forest.
NASA Astrophysics Data System (ADS)
Hess, G. D.; Garratt, J. R.
Data for the cross-isobaric angle 0, the geostrophic drag coefficient Cg, and the functions A and B of Rossby number similarity theory, obtained from meteorological field experiments, are used to evaluate a range of models of the neutral, barotropic planetary boundary layer. The data give well-defined relationships for 0, Cg, and the integrated dissipation rate over the boundary layer, as a function of the surface Rossby number. Lettau's first-order closure mixing-length model gives an excellent fit to the data; other simple models give reasonable agreement. However more sophisticated models, e.g., higher-order closure, large-eddy simulation, direct numerical simulation and laboratory models, give poor fits to the data. The simplemodels have (at least) one free parameter in their turbulence closure that is matched toatmospheric observations; the more sophisticated models either base their closure onmore general flows or have no free closure parameters. It is suggested that all of theatmospheric experiments that we could locate violate the strict simplifying assumptionsof steady, homogeneous, neutral, barotropic flow required by the sophisticated models.The angle 0 is more sensitive to violations of the assumptions than is Cg.
Two Examples of Integrated Aquifer Characterization at Local and Regional Scales
NASA Astrophysics Data System (ADS)
Lefebvre, R.; Gloaguen, E.; Rivard, C.; Parent, M.; Morin, R. H.; Pugin, A.; Pullan, S.; Crow, H.; Paradis, D.; Tremblay, L.; Blouin, M.; Laurencelle, M.
2012-12-01
An integrated aquifer characterization approach was developed with the aim of efficiently providing detailed data that could be used to develop conceptual hydrogeological models and quantitatively describe the spatial continuity and heterogeneity of unconsolidated sediments. The approach involves the integration of geological, hydraulic, geophysical and geochemical data. The emphasis of the approach is placed on the acquisition of detailed and continuous indirect data and selective soil sampling and direct measurements of hydraulic properties covering the full range of materials present in the system. Direct data are used to establish relations between indirect hydrogeophysical measurements and hydrofacies (HF), which are material types with distinct hydraulic conductivity (K). Surface geophysical surveys are used to provide 1D or 2D definitions of sediment structures and material types. Hydraulic tests are used to define HF and estimate their ranges of K. Groundwater (GW) geochemistry (major, minor, isotopes, GW age) is used to support the definition of conceptual models and to provide constraints on numerical models of GW flow and transport (mass and GW age). The approach relies on the geostatistical integration of multi-source data to define aquifer boundaries, on the recognition of HF and estimation of K from CPT/SMR data using fuzzy clustering and relevant vector machines for HF classification and K regression, on the geostatistical simulation of HF and K to provide the spatial distribution of hydraulic parameters in GW flow and transport models, and on the validation of these models using geochemical data. The integrated characterization approach was first developed and tested at local scale for the study of a shallow granular aquifer within a 12 km2 sub-watershed where a former unlined landfill is located. Results are being applied to the assessment of the efficiency of natural attenuation as a site management approach. The integrated characterization
NASA Technical Reports Server (NTRS)
Abarbanel, Saul; Gottlieb, David; Carpenter, Mark H.
1994-01-01
It has been previously shown that the temporal integration of hyperbolic partial differential equations (PDE's) may, because of boundary conditions, lead to deterioration of accuracy of the solution. A procedure for removal of this error in the linear case has been established previously. In the present paper we consider hyperbolic (PDE's) (linear and non-linear) whose boundary treatment is done via the SAT-procedure. A methodology is present for recovery of the full order of accuracy, and has been applied to the case of a 4th order explicit finite difference scheme.
Improving IMES Localization Accuracy by Integrating Dead Reckoning Information
Fujii, Kenjiro; Arie, Hiroaki; Wang, Wei; Kaneko, Yuto; Sakamoto, Yoshihiro; Schmitz, Alexander; Sugano, Shigeki
2016-01-01
Indoor positioning remains an open problem, because it is difficult to achieve satisfactory accuracy within an indoor environment using current radio-based localization technology. In this study, we investigate the use of Indoor Messaging System (IMES) radio for high-accuracy indoor positioning. A hybrid positioning method combining IMES radio strength information and pedestrian dead reckoning information is proposed in order to improve IMES localization accuracy. For understanding the carrier noise ratio versus distance relation for IMES radio, the signal propagation of IMES radio is modeled and identified. Then, trilateration and extended Kalman filtering methods using the radio propagation model are developed for position estimation. These methods are evaluated through robot localization and pedestrian localization experiments. The experimental results show that the proposed hybrid positioning method achieved average estimation errors of 217 and 1846 mm in robot localization and pedestrian localization, respectively. In addition, in order to examine the reason for the positioning accuracy of pedestrian localization being much lower than that of robot localization, the influence of the human body on the radio propagation is experimentally evaluated. The result suggests that the influence of the human body can be modeled. PMID:26828492
Improving IMES Localization Accuracy by Integrating Dead Reckoning Information.
Fujii, Kenjiro; Arie, Hiroaki; Wang, Wei; Kaneko, Yuto; Sakamoto, Yoshihiro; Schmitz, Alexander; Sugano, Shigeki
2016-01-01
Indoor positioning remains an open problem, because it is difficult to achieve satisfactory accuracy within an indoor environment using current radio-based localization technology. In this study, we investigate the use of Indoor Messaging System (IMES) radio for high-accuracy indoor positioning. A hybrid positioning method combining IMES radio strength information and pedestrian dead reckoning information is proposed in order to improve IMES localization accuracy. For understanding the carrier noise ratio versus distance relation for IMES radio, the signal propagation of IMES radio is modeled and identified. Then, trilateration and extended Kalman filtering methods using the radio propagation model are developed for position estimation. These methods are evaluated through robot localization and pedestrian localization experiments. The experimental results show that the proposed hybrid positioning method achieved average estimation errors of 217 and 1846 mm in robot localization and pedestrian localization, respectively. In addition, in order to examine the reason for the positioning accuracy of pedestrian localization being much lower than that of robot localization, the influence of the human body on the radio propagation is experimentally evaluated. The result suggests that the influence of the human body can be modeled. PMID:26828492
Boundaries around Group Interaction: A Meta-Analytic Integration of the Effects of Group Size.
ERIC Educational Resources Information Center
Mullen, Brian; And Others
1991-01-01
Summarizes research comparing boundaries around larger and smaller groups. Finds that the perception of group boundary permatbility varies with group size. Reports a greater perceived distinction between the group and the individual passerby as group size increases. Describes the effects of varying group member proximity. Discusses implications…
Bresme, F.; Armstrong, J.
2014-01-07
We report non-equilibrium molecular dynamics simulations of heat transport in models of molecular fluids. We show that the “local” thermal conductivities obtained from non-equilibrium molecular dynamics simulations agree within numerical accuracy with equilibrium Green-Kubo computations. Our results support the local equilibrium hypothesis for transport properties. We show how to use the local dependence of the thermal gradients to quantify the thermal conductivity of molecular fluids for a wide range of thermodynamic states using a single simulation.
Effects of Global Boundary and Local Collisionality on Magnetic Reconnection in a Laboratory Plasma
Kuritsyn, A.; Ji, H.; Gerhardt, S. P.; Ren, Y.; Yamada, M.
2007-07-24
The magnetic reconnection process is studied in a wide range of operating conditions in the well-controlled Magnetic Reconnection Experiment. The reconnection rate is observed to be a function of both global (i.e., system size) and local (collisionality) plasma parameters. When only local collisionality is lowered, the current sheet is shortened while effective resistivity is enhanced, both accelerating reconnection rates. At a fixed collisionality, the current sheet length increases with system size, resulting in the reduction of the reconnection rate. These results quantitatively agree with a generalized Sweet-Parker analysis.
NASA Astrophysics Data System (ADS)
Yla-Oijala, Pasi
Electron multipacting is a serious problem in many rf components operating in vacuum. Multipacting can cause remarkable power losses and heating of the walls. This phenomenon starts if certain resonant conditions for electron trajectories are fulfilled and if the impacted surface has a secondary yield larger than one. In this work new computational methods have been developed which combine the standard trajectory calculations with advanced searching and analyzing methods for multipacting resonances. These methods have been applied to the analysis of electron multipacting in TESLA superconducting cavities and input power couplers with ceramic windows. TESLA is an international linear collider research and development project. Since even small errors in the rf field may destroy the trajectory calculation of a relativistic electron, the electromagnetic fields must be known accurately, especially close to the surfaces. The electromagnetic field computation is carried out by the boundary integral equation method. Due to the singularities of the integral equations, the numerical computations become rather involved, especially when computing the fields near the boundaries. Therefore, in this work special integration techniques and algorithms have been developed. In the axisymmetric geometries the numerical efficiency of various boundary integral equations has been studied.
NASA Astrophysics Data System (ADS)
Rogowitz, A.; White, J. C.; Grasemann, B.
2015-09-01
Extreme strain localization occurred in the center of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size (∼3 μm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index (J=1.4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy a deformation sequence is observed comprising, first recrystallization by bulging resulting in the development of the fine-grained ultramylonite followed by the evolution of a high dislocation density (∼1013 m-2) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine grain sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at high strain rate (10-9 s-1) and low temperature (300 °C).
NASA Astrophysics Data System (ADS)
Rogowitz, A.; White, J. C.; Grasemann, B.
2016-03-01
Extreme strain localization occurred in the centre of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element, evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size ( ˜ 3 µm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index (J = 1.4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy, a deformation sequence is observed comprising recrystallization dominantly by bulging, resulting in the development of the fine-grained ultramylonite followed by the development of a high dislocation density ( ˜ 1013 m-2) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine-grain-sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at a high strain rate ( ˜ 10-9 s-1) and low temperature (300 °C).
Localized temporal variation of Earth's inner-core boundary from high-quality waveform doublets
NASA Astrophysics Data System (ADS)
Xin, Danhua
2016-04-01
The accurate determination of the topography of an Earth's internal boundary is difficult because of the possible trade-off with the velocity of the media above it. Here we use waveform-doublet method to map the ICB topography. A waveform doublet is a pair of earthquakes occurring at essentially the same spatial position and received by the same station with high similarity in their waveforms (Poupinet et al. 1984), which make the exact detection of the ICB topography possible. In this study, we used this method to detect temporal change of the ICB using doublets from the Western Pacific (WP) area to increase global coverage of the ICB. Compared with previous study using doublets from South Sandwich Islands (SSI) (Song and Dai, 2008), the new samples showed negligible temporal change of the ICB.
Safe task planning integrating uncertainties and local maps federations
Lambert, A.; Fort-Piat, N.L.
2000-06-01
This paper deals with the generation of safe tasks for displacement missions of a nonholonomic mobile robot in a mapped indoor environment. The goal of this study is to plan safe actions (path-following) as well as observations (they call it local maps federation [LMF]), leading the robot to configurations where pertinent features can be sensed, thus attaining best localization relative to its environment. A path-planning method dealing with uncertainties is proposed, where both uncertainties in localization and in control of a nonholonomic mobile robot are managed. Maps uncertainties are handled using the local map concept, which is introduced as a set of the best landmarks used for planning and executing robust motion movements. The safeness of the proposed method is due to the mixing between the planning phase and the navigation phase.
NASA Astrophysics Data System (ADS)
Kiselev, Yu. N.; Orlov, M. V.; Orlov, S. M.
2015-11-01
An infinite-horizon two-sector economy model with a Cobb-Douglas production function and a utility function that is an integral functional with discounting and a logarithmic integrand is investigated. The application of Pontryagin's maximum principle yields a boundary value problem with special conditions at infinity. The search for the solution of the maximum-principle boundary value problem is complicated by singular modes in its optimal solution. In the construction of the solution to the problem, they are described in analytical form. Additionally, a special version of the sweep method in continuous form is proposed, which is of interest from theoretical and computational points of view. An important result is the proof of the optimality of the extremal solution obtained by applying the maximum-principle boundary value problem.
Exploring the Global/Local Boundary in Education in Developing Countries: The Case of the Caribbean
ERIC Educational Resources Information Center
George, June; Lewis, Theodore
2011-01-01
This article focuses on education in developing countries in the context of globalization and with specific reference to the Caribbean. It examines the concept of globalization and related concepts and positions developing countries within this context. It explores the possibility of the creation of a third space where the local and the global can…
Silva, Silvio Fernandes da; Souza, Nathan Mendes; Barreto, Jorge Otávio Maia
2014-11-01
The scope of this article was to identify the boundaries of the autonomy of local administration in the context of the federal pact in the Brazilian Unified Health System and the importance and potential for promoting innovation, creativity and evidence-based decision-making by local governments. The methodology used was to ask questions that favored dialogue with the specific literature to identify the influence of centrally-formulated policies in spaces of local autonomy and then to identify strategies to foster innovation, creativity and the systematic use of evidence-based research in health policy implementation. A gradual reduction in municipal decision-making autonomy was detected due to increased financial commitment of the municipalities resulting from responsibilities assumed, albeit with the possibility of reverting this trend in the more recent context. Some determinants and challenges for the dissemination of innovative practices were analyzed and some relevant national and international experiences in this respect were presented. The conclusion drawn is that it is possible to make local decision-making more effective provided that initiatives are consolidated to promote this culture and the formulation and implementation of evidence-based health policies. PMID:25351309
NASA Astrophysics Data System (ADS)
Li, L.; Wang, K.; Li, H.; Eibert, T. F.
2014-11-01
A hybrid higher-order finite element boundary integral (FE-BI) technique is discussed where the higher-order FE matrix elements are computed by a fully analytical procedure and where the gobal matrix assembly is organized by a self-identifying procedure of the local to global transformation. This assembly procedure applys to both, the FE part as well as the BI part of the algorithm. The geometry is meshed into three-dimensional tetrahedra as finite elements and nearly orthogonal hierarchical basis functions are employed. The boundary conditions are implemented in a strong sense such that the boundary values of the volume basis functions are directly utilized within the BI, either for the tangential electric and magnetic fields or for the asssociated equivalent surface current densities by applying a cross product with the unit surface normals. The self-identified method for the global matrix assembly automatically discerns the global order of the basis functions for generating the matrix elements. Higher order basis functions do need more unknowns for each single FE, however, fewer FEs are needed to achieve the same satisfiable accuracy. This improvement provides a lot more flexibility for meshing and allows the mesh size to raise up to λ/3. The performance of the implemented system is evaluated in terms of computation time, accuracy and memory occupation, where excellent results with respect to precision and computation times of large scale simulations are found.
Boundary Condition Transfer from Global Atmospheric Model to Local Flood Inundation Model
NASA Astrophysics Data System (ADS)
Kim, H.; Kim, B.; Liu, Z.; Yamazaki, D.; Sanders, B.; Oki, T.; Famiglietti, J.
2012-04-01
Flooding is one of the most common natural disasters. It has been a matter of concern and interest in the history of Hydrology. Various methodologies have been developed to approach the issue. Since the capability of models and available data have not been enough, in general, using site-specific fine-tuned models and/or establishing a flood inundation map as a non-structural measure have been used in local societies, in order to predict and prevent damage from abnormal flooding over the design criteria of hydraulic structures. However, under changing climate, the global hydrologic cycle has been altered and the spatiotemporal pattern of natural extremes also has been modified, which reduces the credence of the estimated model parameters and inundation maps based on historical records. In this study, the transfer of information between different spatiotemporal scales from global through local is evaluated. The proposed modeling framework uses multiple modeling system and observational datasets, which are tested in different sites including the Amazon and the San Gabriel River. The Japanese 25-year Reanalysis (JRA-25) data is used to retrieve reliable large scale climate variability. Monthly bias in the reanalysis precipitation field is corrected using ensemble products of global observations such as GPCC and PREC/L. The Shuttle Radar Topography Mission (SRTM) and National Hydrography Dataset Plus (NHD+) are exploited to describe topography in regional and local simulations. The BreZo hydrodynamic model which solves 2 dimensional shallow-water equations to predict flood wave propagation is employed in local high resolution (~100m) simulations. Regional scale hydrologic simulations are compiled using the Minimal Advanced Treatments of Surface Interaction and RunOff (MATSIRO) with Catchment-based Macro-scale Floodplain model (CaMa-Flood) and the Catchment-Based Hydrologic and Routing Modeling System (CHARMS) coupled with the Community Land Model (CLM) 3.5.
Integral method for the calculation of three-dimensional, laminar and turbulent boundary layers
NASA Technical Reports Server (NTRS)
Stock, H. W.
1978-01-01
The method for turbulent flows is a further development of an existing method; profile families with two parameters and a lag entrainment method replace the simple entrainment method and power profiles with one parameter. The method for laminar flows is a new development. Moment of momentum equations were used for the solution of the problem, the profile families were derived from similar solutions of boundary layer equations. Laminar and turbulent flows at the wings were calculated. The influence of wing tapering on the boundary layer development was shown. The turbulent boundary layer for a revolution ellipsoid is calculated for 0 deg and 10 deg incidence angles.
NASA Technical Reports Server (NTRS)
Jin, Jian-Ming; Volakis, John L.
1990-01-01
A numerical technique is proposed for the electromagnetic characterization of the scattering by a three-dimensional cavity-backed aperture in an infinite ground plane. The technique combines the finite element and boundary integral methods to formulate a system of equations for the solution of the aperture fields and those inside the cavity. Specifically, the finite element method is employed to formulate the fields in the cavity region and the boundary integral approach is used in conjunction with the equivalence principle to represent the fields above the ground plane. Unlike traditional approaches, the proposed technique does not require knowledge of the cavity's Green's function and is, therefore, applicable to arbitrary shape depressions and material fillings. Furthermore, the proposed formulation leads to a system having a partly full and partly sparse as well as symmetric and banded matrix which can be solved efficiently using special algorithms.
NASA Technical Reports Server (NTRS)
Ghosn, L. J.
1988-01-01
Crack propagation in a rotating inner raceway of a high-speed roller bearing is analyzed using the boundary integral method. The model consists of an edge plate under plane strain condition upon which varying Hertzian stress fields are superimposed. A multidomain boundary integral equation using quadratic elements was written to determine the stress intensity factors KI and KII at the crack tip for various roller positions. The multidomain formulation allows the two faces of the crack to be modeled in two different subregions, making it possible to analyze crack closure when the roller is positioned on or close to the crack line. KI and KII stress intensity factors along any direction were computed. These calculations permit determination of crack growth direction along which the average KI times the alternating KI is maximum.
Local Structure of Sb in Cretaceous-Tertiary Boundary Clays from Stevns Klint By the XAFS Method
NASA Astrophysics Data System (ADS)
Hongu, H.; Yoshiasa, A.; Tobase, T.; Hiratoko, T.; Isobe, H.; Arima, H.; Sugiyama, K.; Okube, M.
2014-12-01
The Cretaceous-Tertiary (K-T) mass extinctions has been thought to be due to the asteroid impact since Ir anomalies was found by Alvarez et al. (1980) . The boundary clay is also enriched in Cr, Co, Ni, Cu, Zn, As and Sb. Especially concentrations of Sb and As are unusually large. However, the origins and concentration processes of Sb are unknown. In this study, local structure around antimony atoms in K-T boundary clay from Stevns Klint, Denmark, was determined by Sb K-edge XAFS spectroscopy. The XAFS analyses give the information about the chemical state and coordination environment around Sb atoms and help identify of the concentration phase, and also may provide various kinds of information about the asteroid impact and mass extinction. The XAFS measurements were performed at the BL-NW10A beamline at the Photon Factory in KEK, Tsukuba, Japan. The XANES spectra and radial structure function (RSF) showed that Sb in K-T boundary clays is high oxidation state Sb5+ and occupies a SbO6 octahedral site. The Sb-O interatomic distance in K-T clay sample is 2.08(1) A. It is known that Sb5+ is stable form in soil and soil water under an equilibrium situation within the Earth's surface environment. Antimony belongs to group 15 in the periodic table below arsenic, and the chemical behavior of Sb5+ is similar to that of As5+. Because there is a close correlation on co-precipitation between As and Fe (Ebihara and Miura, 1996; Sakai et al., 2007) , it is considered that Sb also correlates closely with Fe compounds (e.g., ferric hydroxides). Abundant ferric hydroxides occur in K-T boundary clays. It is considered that one of the reasons of abnormal high concentrations of Sb and As in K-T boundary clays is a lot of dust from impact ejecta falls with iron ions and deposits on surface of the Earth for a short period of time after the asteroid impact. ReferencesL. W. Alvarez, Science, 208, 1095-1108 (1980) M. Ebihara and T. Miura, Geochimica et Cosmochimica Acta, 60, 5133
Integrating Local Green Assets into Brownfields Redevelopment: Tools and Examples
EnviroAtlas is a free, online public mapping tool that characterizes green infrastructure and its connection to human health and wellness. The high resolution data contained in this tool can be used to incorporate local green infrastructure into Brownfields redevelopment to benef...
NASA Astrophysics Data System (ADS)
Walls, C.; Blume, F.; Meertens, C.; Arnitz, E.; Lawrence, S.; Miller, S.; Bradley, W.; Jackson, M.; Feaux, K.
2007-12-01
equipment includes CDMA Proxicast modems, Hughes Vsat, Intuicom 900 MHz Ethernet bridge radios and several "real-time" sites use 2.4 GHz Wilan radios. Ultimately, 125 of the existing former-SCIGN GPS stations will be integrated into the So Cal region of PBO, of which 25 have real-time data streams. At the time of this publication the total combined Southern California region has over 40 stations streaming real-time data using both radios and CDMA modems. The real-time GPS sites provide specific benefits beyond the standard GPS station: they can provide a live correction for local surveyors and can be used to trigger an alarm if large displacements are recorded. The cross fault spatial distribution of these 336 GPS stations in the seismically active southern California region has the grand potential of augmenting a strong motion earthquake early warning system.
RF performances of inductors integrated on localized p+-type porous silicon regions
NASA Astrophysics Data System (ADS)
Capelle, Marie; Billoué, Jérôme; Poveda, Patrick; Gautier, Gaël
2012-09-01
To study the influence of localized porous silicon regions on radiofrequency performances of passive devices, inductors were integrated on localized porous silicon regions, full porous silicon sheet, bulk silicon and glass substrates. In this work, a novel strong, resistant fluoropolymer mask is introduced to localize the porous silicon on the silicon wafer. Then, the quality factors and resonant frequencies obtained with the different substrates are presented. A first comparison is done between the performances of inductors integrated on same-thickness localized and full porous silicon sheet layers. The effect of the silicon regions in the decrease of performances of localized porous silicon is discussed. Then, the study shows that the localized porous silicon substrate significantly reduces losses in comparison with high-resistivity silicon or highly doped silicon bulks. These results are promising for the integration of both passive and active devices on the same silicon/porous silicon hybrid substrate.
Local normal forms of smooth weakly hyperbolic integrable systems
NASA Astrophysics Data System (ADS)
Jiang, Kai
2016-01-01
In the smooth ( C∞) category, a completely integrable system near a nondegenerate singularity is geometrically linearizable if the action generated by the vector fields is weakly hyperbolic. This proves partially a conjecture of Nguyen Tien Zung [11]. The main tool used in the proof is a theorem of Marc Chaperon [3] and the slight hypothesis of weak hyperbolicity is generic when all the eigenvalues of the differentials of the vector fields at the non-degenerate singularity are real.
Time-dependent behavior of a localized electron at a heterojunction boundary of graphene
Jang, Min S.; Kim, Hyungjun; Atwater, Harry A.; Goddard, William A.
2010-01-01
We develop a finite-difference time-domain(FDTD) method for simulating the dynamics of graphene electrons, denoted GraFDTD. We then use GraFDTD to study the temporal behavior of a single localized electron wave packet, showing that it exhibits optical-like dynamics including the Goos–Hänchen effect [F. Goos and H. Hänchen, Ann. Phys.436, 333 (1947)] at a heterojunction, but the behavior is quantitatively different than for electromagnetic waves. This suggests issues that must be addressed in designing graphene-based electronic devices analogous to optical devices. GraFDTD should be useful for studying such complex time-dependent behavior of a quasiparticle in graphene.
Local Built-in Potential on Grain Boundary of Cu(In,Ga)Se2 Thin Films
Jiang, C.-S.; Noufi, R.; Ramanathan, K.; AbuShama, J. A.; Moutinho, H. R.; Al-Jassim, M. M.
2005-01-01
We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In,Ga)Se2 (CIGS) thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy (SKPM). The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates the existence of a local built-in potential on GBs and that the GB is positively charged. The role of the built-in potential in device performance was further examined by tuning Ga content or band gap of the film. With increasing Ga content, the GB potential drops sharply in a Ga range of 28%-38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversion efficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage CIGS device.
Allen, Davina
2014-07-01
This article examines the translation of a clinical governance concept - integrated care pathways (ICPs)--into an infrastructural technology. Building on previous work, the application of boundary object theory is extended in this article to argue that stakeholder enrolment in pathway methodology may be less thoroughgoing than originally assumed. Pathways have effectively aligned management and nursing interests around a quality agenda and nurses have emerged as the leaders in this field, but doctors have rather lower levels of engagement. It is suggested that the contradictory logics inherent in pathway philosophy (primarily as these relate to 'evidence') and the social organisation of ICP development foster a transformation of the concept when this is translated into the technology, creating a negative boundary object from the perspective of doctors. Medicine is a powerful actor in health care, which is consequential for whether pathways, as designated boundary objects, become boundary objects-in-use. It also has implications for the diffusion of the concept as a mechanism of clinical governance and the credibility of nurses as emergent leaders in this field. Qualitative case studies of ICP development processes undertaken in the UK National Health Service and ethnographic research on the ICP community provide the empirical foundations for the analysis. PMID:24635748
Cutaneous glucocorticosteroidogenesis: securing local homeostasis and the skin integrity
2014-01-01
Human skin has the ability to synthesize glucocorticoids de novo from cholesterol or from steroid intermediates of systemic origin. By interacting with glucocorticoid receptors, they regulate skin immune functions as well as functions and phenotype of the epidermal, dermal and adnexal compartments. Most of the biochemical (enzyme and transporter activities) and regulatory (neuropeptides mediated activation of cAMP and protein kinase A dependent pathways) principles of steroidogenesis in the skin are similar to those operating in classical steroidogenic organs. However, there are also significant differences determined by the close proximity of synthesis and action (even within the same cells) allowing para-, auto- or intracrine modes of regulation. We also propose that ultraviolet light B (UVB) can regulate the availability of 7-dehydrocholesterol for transformation to cholesterol with its further metabolism to steroids, oxysterols or Δ7 steroids, because of its transformation to vitamin D3. In addition, UVB can rearrange locally produced Δ7 steroids to the corresponding secosteroids with a short- or no-side chain. Thus, different mechanisms of regulation occur in the skin that can be either stochastic or structuralized. We propose that local glucocorticosteroidogenic systems and their regulators, in concert with cognate receptors operate to stabilize skin homeostasis and prevent or attenuate skin pathology. PMID:24888781
Blurring Boundaries: Correlates of Integration and Segmentation between Work and Nonwork
ERIC Educational Resources Information Center
Olson-Buchanan, Julie B.; Boswell, Wendy R.
2006-01-01
This study investigates the interrelations among role integration-segmentation, role identification, reactions to interruptions, and work-life conflict. Results from a field survey of university staff employees suggest that as highly identified roles are integrated into other domains, high role integration is related to less negative reactions to…
Gillespie, D.R.H.; Wang, Z.; Ireland, P.T.; Kohler, S.T.
1998-01-01
Cast impingement cooling geometries offer the gas turbine designer higher structural integrity and improved convective cooling when compared to traditional impingement cooling systems, which rely on plate inserts. In this paper, it is shown that the surface that forms the jets contributes significantly to the total cooling. Local heat transfer coefficient distributions have been measured in a model of an engine wall cooling geometry using the transient heat transfer technique. The method employs temperature-sensitive liquid crystals to measure the surface temperature of large-scale perspex models during transient experiments. Full distributions of local Nusselt number on both surfaces of the impingement plate, and on the impingement target plate, are presented at engine representative Reynolds numbers. The relative effects of the impingement plate thermal boundary condition and the coolant supply temperature on the target plate heat transfer have been determined by maintaining an isothermal boundary condition at the impingement plate during the transient tests. The results are discussed in terms of the interpreted flow field.
Wedge-Local Fields in Integrable Models with Bound States
NASA Astrophysics Data System (ADS)
Cadamuro, Daniela; Tanimoto, Yoh
2015-12-01
Recently, large families of two-dimensional quantum field theories with factorizing S-matrices have been constructed by the operator-algebraic methods, by first showing the existence of observables localized in wedge-shaped regions. However, these constructions have been limited to the class of S-matrices whose components are analytic in rapidity in the physical strip. In this work, we construct candidates for observables in wedges for scalar factorizing S-matrices with poles in the physical strip and show that they weakly commute on a certain domain. We discuss some technical issues concerning further developments, especially the self-adjointness of the candidate operators here and strong commutativity between them.
Interim user's manual for boundary layer integral matrix procedure, version J
NASA Technical Reports Server (NTRS)
Evans, R. M.; Morse, H. L.
1974-01-01
A computer program for analyzing two dimensional and axisymmetric nozzle performance with a variety of wall boundary conditions is described. The program has been developed for application to rocket nozzle problems. Several aids to usage of the program and two auxiliary subroutines are provided. Some features of the output are described and three sample cases are included.
NASA Astrophysics Data System (ADS)
Kitanine, N.; Maillet, J. M.; Niccoli, G.
2014-05-01
We solve the longstanding problem of defining a functional characterization of the spectrum of the transfer matrix associated with the most general spin-1/2 representations of the six-vertex reflection algebra for general inhomogeneous chains. The corresponding homogeneous limit reproduces the spectrum of the Hamiltonian of the spin-1/2 open XXZ and XXX quantum chains with the most general integrable boundaries. The spectrum is characterized by a second order finite difference functional equation of Baxter type with an inhomogeneous term which vanishes only for some special but yet interesting non-diagonal boundary conditions. This functional equation is shown to be equivalent to the known separation of variables (SOV) representation, hence proving that it defines a complete characterization of the transfer matrix spectrum. The polynomial form of the Q-function allows us to show that a finite system of generalized Bethe equations can also be used to describe the complete transfer matrix spectrum.
Sumets, P. P.; Cater, J. E.; Long, D. S.; Clarke, R. J.
2015-01-01
We describe a new boundary-integral representation for biphasic mixture theory, which allows us to efficiently solve certain elastohydrodynamic–mobility problems using boundary element methods. We apply this formulation to model the motion of a rigid particle through a microtube which has non-uniform wall shape, is filled with a viscous Newtonian fluid, and is lined with a thin poroelastic layer. This is relevant to scenarios such as the transport of small rigid cells (such as neutrophils) through microvessels that are lined with an endothelial glycocalyx layer (EGL). In this context, we examine the impact of geometry upon some recently reported phenomena, including the creation of viscous eddies, fluid flux into the EGL, as well as the role of the EGL in transmitting mechanical signals to the underlying endothelial cells. PMID:26345494
33 CFR 230.20 - Integration with State and local procedures.
Code of Federal Regulations, 2010 CFR
2010-07-01
..., DEPARTMENT OF DEFENSE PROCEDURES FOR IMPLEMENTING NEPA § 230.20 Integration with State and local procedures. See 40 CFR 1506.2. ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Integration with State and...
33 CFR 230.20 - Integration with State and local procedures.
Code of Federal Regulations, 2014 CFR
2014-07-01
..., DEPARTMENT OF DEFENSE PROCEDURES FOR IMPLEMENTING NEPA § 230.20 Integration with State and local procedures. See 40 CFR 1506.2. ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Integration with State and...
33 CFR 230.20 - Integration with State and local procedures.
Code of Federal Regulations, 2013 CFR
2013-07-01
..., DEPARTMENT OF DEFENSE PROCEDURES FOR IMPLEMENTING NEPA § 230.20 Integration with State and local procedures. See 40 CFR 1506.2. ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Integration with State and...
33 CFR 230.20 - Integration with State and local procedures.
Code of Federal Regulations, 2011 CFR
2011-07-01
..., DEPARTMENT OF DEFENSE PROCEDURES FOR IMPLEMENTING NEPA § 230.20 Integration with State and local procedures. See 40 CFR 1506.2. ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Integration with State and...
33 CFR 230.20 - Integration with State and local procedures.
Code of Federal Regulations, 2012 CFR
2012-07-01
..., DEPARTMENT OF DEFENSE PROCEDURES FOR IMPLEMENTING NEPA § 230.20 Integration with State and local procedures. See 40 CFR 1506.2. ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Integration with State and...
The integrated local flood warning system: A look at the flood response system
Neal, D.M.; Lee, R.
1988-01-01
Local Flood Warning Systems are instituted and maintained at a local level. They consist of two parts: (1) the flood forecast system, and (2) the flood response system. The flood forecast system is primarily built around the technology used to predict flooding. In this paper, we stress two points about local flood warning systems. First, the system must be integrated. Specifically, collecting data, transmitting data, forecasting the flood, informing local officials, warning local residents, and taking protective action (including evacuation of residents) must all occur in an integrated fashion if the whole system is to succeed. Second, we outline some important organizational characteristics that should be improved when developing a local flood response system. Key organizational characteristics include experience, networks, communications, decision making, everyday disaster task overlap. By focusing upon experience (including learning from the past flood or disaster experience or participating in drills and exercises) and by improving preparedness can be inexpensively improved. 6 refs.,
Local, integrated control of blood flow: Professor Tudor Griffith Memorial.
Edwards, David H
2013-11-01
Professor Tudor Griffith was one of the founding members of the European Study Group on Cardiovascular Oscillations, and hosted the 1st ESGCO Conference in Cardiff, Wales in 2000. Tudor was a passionate scientist, who managed to combine his enthusiasm for vascular biology with his background in physics, to make key and insightful advances to our knowledge and understanding of the integrated vascular control mechanisms that co-ordinate blood flow in tissue perfusion. He had a particular interest in the endothelium, the monolayer of cells that lines the entire cardiovascular system and which is in prime position to sense a wide variety of modulatory stimuli, both chemical and mechanical. Over the last 20 years Tudor produced a series of research papers in which he used chaos theory to analyse the behaviour of arteries that underpins vasomotion. The research led to the development of mathematical models that were able to predict calcium oscillations in vascular smooth muscle with a view to predicting events in a complete virtual artery. This article will review the field in which he worked, with an obvious emphasis on his contribution. PMID:23522722
Darabant, András; Rai, Prem Bahadur; Staudhammer, Christina Lynn; Dorji, Tshewang
2016-08-01
Dendrocalamus hamiltonii, a large, clump-forming bamboo, has great potential to contribute towards poverty alleviation efforts across its distributional range. Harvesting methods that maximize yield while they fulfill local objectives and ensure sustainability are a research priority. Documenting local ecological knowledge on the species and identifying local users' goals for its production, we defined three harvesting treatments (selective cut, horseshoe cut, clear cut) and experimentally compared them with a no-intervention control treatment in an action research framework. We implemented harvesting over three seasons and monitored annually and two years post-treatment. Even though the total number of culms positively influenced the number of shoots regenerated, a much stronger relationship was detected between the number of culms harvested and the number of shoots regenerated, indicating compensatory growth mechanisms to guide shoot regeneration. Shoot recruitment declined over time in all treatments as well as the control; however, there was no difference among harvest treatments. Culm recruitment declined with an increase in harvesting intensity. When univariately assessing the number of harvested culms and shoots, there were no differences among treatments. However, multivariate analyses simultaneously considering both variables showed that harvested output of shoots and culms was higher with clear cut and horseshoe cut as compared to selective cut. Given the ease of implementation and issues of work safety, users preferred the horseshoe cut, but the lack of sustainability of shoot production calls for investigating longer cutting cycles. PMID:27113084
NASA Astrophysics Data System (ADS)
Darabant, András; Rai, Prem Bahadur; Staudhammer, Christina Lynn; Dorji, Tshewang
2016-08-01
Dendrocalamus hamiltonii, a large, clump-forming bamboo, has great potential to contribute towards poverty alleviation efforts across its distributional range. Harvesting methods that maximize yield while they fulfill local objectives and ensure sustainability are a research priority. Documenting local ecological knowledge on the species and identifying local users' goals for its production, we defined three harvesting treatments (selective cut, horseshoe cut, clear cut) and experimentally compared them with a no-intervention control treatment in an action research framework. We implemented harvesting over three seasons and monitored annually and two years post-treatment. Even though the total number of culms positively influenced the number of shoots regenerated, a much stronger relationship was detected between the number of culms harvested and the number of shoots regenerated, indicating compensatory growth mechanisms to guide shoot regeneration. Shoot recruitment declined over time in all treatments as well as the control; however, there was no difference among harvest treatments. Culm recruitment declined with an increase in harvesting intensity. When univariately assessing the number of harvested culms and shoots, there were no differences among treatments. However, multivariate analyses simultaneously considering both variables showed that harvested output of shoots and culms was higher with clear cut and horseshoe cut as compared to selective cut. Given the ease of implementation and issues of work safety, users preferred the horseshoe cut, but the lack of sustainability of shoot production calls for investigating longer cutting cycles.
NASA Astrophysics Data System (ADS)
Orlowska, S.; Beroual, A.; Fleszynski, J.
2004-03-01
This paper deals with the analysis of the influence of moisture on the dielectric properties of a composite insulator core made of epoxy resin and fibre glass, through measurements of the effective permittivity. The experiments are carried out on different core samples—dry and boiled in distilled water over different time intervals. The measured values of the complex permittivity of the core samples are discussed in the light of the results obtained by a numerical approach based on the boundary integral equation method and the PHI3D package. The comparison of the experimental and simulated results aims at finding the water content in the fibre glass.
ERIC Educational Resources Information Center
Venville, Grady; Wallace, John; Rennie, Leonie; Malone, John
2000-01-01
Describes the integration of content from science, mathematics, and technology learning areas as well-grounded in the philosophy of middle schooling. Points out the absence of recent research on how students learn science and mathematics concepts in integrated settings. Analyses 9th grade students' learning experiences in a technology project of…
A Collocation Method for Volterra Integral Equations with Diagonal and Boundary Singularities
NASA Astrophysics Data System (ADS)
Kolk, Marek; Pedas, Arvet; Vainikko, Gennadi
2009-08-01
We propose a smoothing technique associated with piecewise polynomial collocation methods for solving linear weakly singular Volterra integral equations of the second kind with kernels which, in addition to a diagonal singularity, may have a singularity at the initial point of the interval of integration.
NASA Astrophysics Data System (ADS)
Petrizzo, Maria Rose
2014-05-01
Planktonic foraminifera are marine protozoans characterized by an excellent geological record and by high morphological diversification and speciation rates. For these reasons, they have been widely used in biostratigraphy and strongly contributed to the multi-disciplinary efforts to improve Cretaceous chronostratigraphy in pelagic settings. A critical time is the Albian to Santonian interval for which a high-resolution multiple bio-, geochemical and physical integrated stratigraphy framework exportable worldwide is still needed. This is partially because a consistent correlation of the planktonic foraminifera bioevents and calibration against other stratigraphic tools often lacks in accuracy, resolution and reproducibility of the data. At present the GSSPs for the base of the Cenomanian (Mt Risou, SE France), the base of the Turonian (Pueblo, Colorado) and the base of the Santonian (Olazagutia, N Spain) stages have been established and ratified by IUGS. Planktonic foraminifera bioevents are primary defining criteria for the Albian/Cenomanian boundary (appearance level of Thalmanninella globotruncanoides), and secondary defining criteria for the Cenomanian/Turonian (appearance level of Helvetoglobotruncana helvetica) and Coniacian/Santonian (appearance level of Globotruncana linneiana) boundaries. However, the identifications of the foraminiferal index species across those boundaries have been reported to be sometimes difficult or unreliable from a number of localities worldwide either because of their rarity or uncertainty in the taxonomic identifications. Reasons rely on many factors, such as poor sampling resolution, incomplete exposure, facies differences, fossil preservation quality, diachronous taxa occurrences, and regional/provincial distribution of the index species. Often, discrepancies pertain to taxonomic inconsistencies, species misidentifications and different species concepts that accumulate over time in the literature. Nevertheless, biostratigraphy
Wong, Richard W; Mamede, João I; Hope, Thomas J
2015-10-01
It has been known for a number of years that integration sites of human immunodeficiency virus type 1 (HIV-1) DNA show a preference for actively expressed chromosomal locations. A number of viral and cellular proteins are implicated in this process, but the underlying mechanism is not clear. Two recent breakthrough publications advance our understanding of HIV integration site selection by focusing on the localization of the preferred target genes of integration. These studies reveal that knockdown of certain nucleoporins and components of nucleocytoplasmic trafficking alter integration site preference, not by altering the trafficking of the viral genome but by altering the chromatin subtype localization relative to the structure of the nucleus. Here, we describe the link between the nuclear basket nucleoporins (Tpr and Nup153) and chromatin organization and how altering the host environment by manipulating nuclear structure may have important implications for the preferential integration of HIV into actively transcribed genes, facilitating efficient viral replication. PMID:26136574
Wong, Rene; Breiner, Petra; Mylopoulos, Maria
2014-09-01
This article reports on research into the relationships that emerged between hospital-based and community-based interprofessional diabetes programs involved in inter-agency care. Using constructivist grounded theory methodology we interviewed a purposive theoretical sample of 21 clinicians and administrators from both types of programs. Emergent themes were identified through a process of constant comparative analysis. Initial boundaries were constructed based on contrasts in beliefs, practices and expertise. In response to bureaucratic and social pressures, boundaries were redefined in a way that created role uncertainty and disempowered community programs, ultimately preventing collaboration. We illustrate the dynamic and multi-dimensional nature of social and symbolic boundaries in inter-agency diabetes care and the tacit ways in which hospitals can maintain a power position at the expense of other actors in the field. As efforts continue in Canada and elsewhere to move knowledge and resources into community sectors, we highlight the importance of hospitals seeing beyond their own interests and adopting more altruistic models of inter-agency integration. PMID:24766617
Boriskina, Svetlana V; Sewell, Phillip; Benson, Trevor M; Nosich, Alexander I
2004-03-01
A fast and accurate method is developed to compute the natural frequencies and scattering characteristics of arbitrary-shape two-dimensional dielectric resonators. The problem is formulated in terms of a uniquely solvable set of second-kind boundary integral equations and discretized by the Galerkin method with angular exponents as global test and trial functions. The log-singular term is extracted from one of the kernels, and closed-form expressions are derived for the main parts of all the integral operators. The resulting discrete scheme has a very high convergence rate. The method is used in the simulation of several optical microcavities for modern dense wavelength-division-multiplexed systems. PMID:15005404
NASA Astrophysics Data System (ADS)
Zeeden, Christian; Zens, Joerg; Lehmkuhl, Frank
2015-04-01
Stratigraphic marker beds are often used in geosciences for regional and global correlation. For various reasons dating those layers directly proves to be difficult sometimes. In such cases ages from above and below such a horizon represent minimum- and maximum-ages. If these ages are determined from more than one location, it is possible to combine these ages, test their consistency and finally derive an age in agreement with the findings from most localities. Several approaches to integrate the age information from different localities are discussed, resulting in combined ages consistent with both stratigraphy and most of the dating results. All approach rely on assumptions, most importantly the correctness of ages and their reported uncertainty. The Eltville Tephra originates from an unknown eruption in the Eifel volcanic field is an important maker bed in Rhine-Meuse Area nearby the boundary between the deposition of reworked and primary loess during the LGM (ca. 20 ka). The Eltville Tephra is usually imbedded in loess; dates from directly above and below come almost exclusively from luminescence dating. As different luminescence dating techniques were applied to samples over- and underlying the Eltville Tephra a systematic bias of the sum of these techniques seems unlikely, but may be present due to the fact that most ages are feldspar ages uncorrected for fading. The results of several statistical approaches to deal with ages from various localities are compared, and their chances and shortcomings using well understood artificial data are discussed. These are also used to obtain an integrated datum for the Eltville Tephra including a reproducible uncertainty. This has the potential to improve on existing dates for various other stratigraphic marker beds especially in the terrestrial realm, where often dates for (or around) correlative sediments are obtained from various localities.
NASA Technical Reports Server (NTRS)
Santanello, Joseph A., Jr.; Peters-Lidard, Christa D.; Kumar, Sujay V.
2011-01-01
The inherent coupled nature of earth s energy and water cycles places significant importance on the proper representation and diagnosis of land atmosphere (LA) interactions in hydrometeorological prediction models. However, the precise nature of the soil moisture precipitation relationship at the local scale is largely determined by a series of nonlinear processes and feedbacks that are difficult to quantify. To quantify the strength of the local LA coupling (LoCo), this process chain must be considered both in full and as individual components through their relationships and sensitivities. To address this, recent modeling and diagnostic studies have been extended to 1) quantify the processes governing LoCo utilizing the thermodynamic properties of mixing diagrams, and 2) diagnose the sensitivity of coupled systems, including clouds and moist processes, to perturbations in soil moisture. This work employs NASA s Land Information System (LIS) coupled to the Weather Research and Forecasting (WRF) mesoscale model and simulations performed over the U.S. Southern Great Plains. The behavior of different planetary boundary layers (PBL) and land surface scheme couplings in LIS WRF are examined in the context of the evolution of thermodynamic quantities that link the surface soil moisture condition to the PBL regime, clouds, and precipitation. Specifically, the tendency toward saturation in the PBL is quantified by the lifting condensation level (LCL) deficit and addressed as a function of time and space. The sensitivity of the LCL deficit to the soil moisture condition is indicative of the strength of LoCo, where both positive and negative feedbacks can be identified. Overall, this methodology can be applied to any model or observations and is a crucial step toward improved evaluation and quantification of LoCo within models, particularly given the advent of next-generation satellite measurements of PBL and land surface properties along with advances in data assimilation
NASA Astrophysics Data System (ADS)
Wang, Qianxi; Manmi, Kawa; Calvisi, Michael L.
2015-02-01
Ultrasound contrast agents (UCAs) are microbubbles stabilized with a shell typically of lipid, polymer, or protein and are emerging as a unique tool for noninvasive therapies ranging from gene delivery to tumor ablation. While various models have been developed to describe the spherical oscillations of contrast agents, the treatment of nonspherical behavior has received less attention. However, the nonspherical dynamics of contrast agents are thought to play an important role in therapeutic applications, for example, enhancing the uptake of therapeutic agents across cell membranes and tissue interfaces, and causing tissue ablation. In this paper, a model for nonspherical contrast agent dynamics based on the boundary integral method is described. The effects of the encapsulating shell are approximated by adapting Hoff's model for thin-shell, spherical contrast agents. A high-quality mesh of the bubble surface is maintained by implementing a hybrid approach of the Lagrangian method and elastic mesh technique. The numerical model agrees well with a modified Rayleigh-Plesset equation for encapsulated spherical bubbles. Numerical analyses of the dynamics of UCAs in an infinite liquid and near a rigid wall are performed in parameter regimes of clinical relevance. The oscillation amplitude and period decrease significantly due to the coating. A bubble jet forms when the amplitude of ultrasound is sufficiently large, as occurs for bubbles without a coating; however, the threshold amplitude required to incite jetting increases due to the coating. When a UCA is near a rigid boundary subject to acoustic forcing, the jet is directed towards the wall if the acoustic wave propagates perpendicular to the boundary. When the acoustic wave propagates parallel to the rigid boundary, the jet direction has components both along the wave direction and towards the boundary that depend mainly on the dimensionless standoff distance of the bubble from the boundary. In all cases, the jet
Heinen, M.; Kull, H.-J.
2009-05-15
Exact radiation boundary conditions on the surface of a sphere are presented for the single-particle time-dependent Schroedinger equation with a localized interaction. With these boundary conditions, numerical computations of spatially unbounded outgoing wave solutions can be restricted to the finite volume of a sphere. The boundary conditions are expressed in terms of the free-particle Green's function for the outside region. The Green's function is analytically calculated by an expansion in spherical harmonics and by the method of Laplace transformation. For each harmonic number a discrete boundary condition between the function values at adjacent radial grid points is obtained. The numerical method is applied to quantum tunneling through a spherically symmetric potential barrier with different angular-momentum quantum numbers l. Calculations for l=0 are compared to exact theoretical results.
Deniz, Furkan Nur; Alagoz, Baris Baykant; Tan, Nusret; Atherton, Derek P
2016-05-01
This paper introduces an integer order approximation method for numerical implementation of fractional order derivative/integrator operators in control systems. The proposed method is based on fitting the stability boundary locus (SBL) of fractional order derivative/integrator operators and SBL of integer order transfer functions. SBL defines a boundary in the parametric design plane of controller, which separates stable and unstable regions of a feedback control system and SBL analysis is mainly employed to graphically indicate the choice of controller parameters which result in stable operation of the feedback systems. This study reveals that the SBL curves of fractional order operators can be matched with integer order models in a limited frequency range. SBL fitting method provides straightforward solutions to obtain an integer order model approximation of fractional order operators and systems according to matching points from SBL of fractional order systems in desired frequency ranges. Thus, the proposed method can effectively deal with stability preservation problems of approximate models. Illustrative examples are given to show performance of the proposed method and results are compared with the well-known approximation methods developed for fractional order systems. The integer-order approximate modeling of fractional order PID controllers is also illustrated for control applications. PMID:26876378
Michel, Marcus; Aliee, Maryam; Rudolf, Katrin; Bialas, Lisa; Jülicher, Frank; Dahmann, Christian
2016-01-01
The separation of cells with distinct fates and functions is important for tissue and organ formation during animal development. Regions of different fates within tissues are often separated from another along straight boundaries. These compartment boundaries play a crucial role in tissue patterning and growth by stably positioning organizers. In Drosophila, the wing imaginal disc is subdivided into a dorsal and a ventral compartment. Cells of the dorsal, but not ventral, compartment express the selector gene apterous. Apterous expression sets in motion a gene regulatory cascade that leads to the activation of Notch signaling in a few cell rows on either side of the dorsoventral compartment boundary. Both Notch and apterous mutant clones disturb the separation of dorsal and ventral cells. Maintenance of the straight shape of the dorsoventral boundary involves a local increase in mechanical tension at cell bonds along the boundary. The mechanisms by which cell bond tension is locally increased however remain unknown. Here we use a combination of laser ablation of cell bonds, quantitative image analysis, and genetic mutants to show that Notch and Apterous are required to increase cell bond tension along the dorsoventral compartment boundary. Moreover, clonal expression of the Apterous target gene capricious results in cell separation and increased cell bond tension at the clone borders. Finally, using a vertex model to simulate tissue growth, we find that an increase in cell bond tension at the borders of cell clones, but not throughout the cell clone, can lead to cell separation. We conclude that Apterous and Notch maintain the characteristic straight shape of the dorsoventral compartment boundary by locally increasing cell bond tension. PMID:27552097
Michel, Marcus; Aliee, Maryam; Rudolf, Katrin; Bialas, Lisa; Jülicher, Frank; Dahmann, Christian
2016-01-01
The separation of cells with distinct fates and functions is important for tissue and organ formation during animal development. Regions of different fates within tissues are often separated from another along straight boundaries. These compartment boundaries play a crucial role in tissue patterning and growth by stably positioning organizers. In Drosophila, the wing imaginal disc is subdivided into a dorsal and a ventral compartment. Cells of the dorsal, but not ventral, compartment express the selector gene apterous. Apterous expression sets in motion a gene regulatory cascade that leads to the activation of Notch signaling in a few cell rows on either side of the dorsoventral compartment boundary. Both Notch and apterous mutant clones disturb the separation of dorsal and ventral cells. Maintenance of the straight shape of the dorsoventral boundary involves a local increase in mechanical tension at cell bonds along the boundary. The mechanisms by which cell bond tension is locally increased however remain unknown. Here we use a combination of laser ablation of cell bonds, quantitative image analysis, and genetic mutants to show that Notch and Apterous are required to increase cell bond tension along the dorsoventral compartment boundary. Moreover, clonal expression of the Apterous target gene capricious results in cell separation and increased cell bond tension at the clone borders. Finally, using a vertex model to simulate tissue growth, we find that an increase in cell bond tension at the borders of cell clones, but not throughout the cell clone, can lead to cell separation. We conclude that Apterous and Notch maintain the characteristic straight shape of the dorsoventral compartment boundary by locally increasing cell bond tension. PMID:27552097
Mur-Veeman, Ingrid; Hardy, Brian; Steenbergen, Marijke; Wistow, Gerald
2003-09-01
This paper addresses the impact of the public-private mix in the Dutch and English health and social care systems on the development and delivery of integrated care. Integrated care is conceived of as an organisational process of coordination which seeks to achieve seamless and continuous care, tailored to the patients' needs and based on a holistic view of the patient. We describe both systems' structures and characteristics from a historical perspective, which means that developments and processes within the systems are put in the spotlight. We demonstrate that the dividing- or fault-lines, such as the financial split between short-term and long-term care in the Netherlands and the divisions between health and social care as well as between the public, private and voluntary sectors in England have hindered integrated care development and delivery in both countries. Contradictory interests, differences in professional and organisational cultures, power relations, and mistrust between and within these sectors have had a clear impact on integrated care development and delivery within networks of public authorities and public and/or private providers. We explain these phenomena in terms of network theory as a basis for drawing lessons for policy makers and those developing integrated care networks. PMID:12941491
Wave breaking over sloping beaches using a coupled boundary integral-level set method
Garzon, M.; Adalsteinsson, D.; Gray, L.; Sethian, J.A.
2003-12-08
We present a numerical method for tracking breaking waves over sloping beaches. We use a fully non-linear potential model for in-compressible, irrotational and inviscid flow, and consider the effects of beach topography on breaking waves. The algorithm uses a Boundary Element Method (BEM) to compute the velocity at the interface, coupled to a Narrow Band Level Set Method to track the evolving air/water interface, and an associated extension equation to update the velocity potential both on and off the interface. The formulation of the algorithm is applicable to two and three dimensional breaking waves; in this paper, we concentrate on two-dimensional results showing wave breaking and rollup, and perform numerical convergence studies and comparison with previous techniques.
Tello-Leal, Edgar; Chiotti, Omar; Villarreal, Pablo David
2012-12-01
The paper presents a methodology that follows a top-down approach based on a Model-Driven Architecture for integrating and coordinating healthcare services through cross-organizational processes to enable organizations providing high quality healthcare services and continuous process improvements. The methodology provides a modeling language that enables organizations conceptualizing an integration agreement, and identifying and designing cross-organizational process models. These models are used for the automatic generation of: the private view of processes each organization should perform to fulfill its role in cross-organizational processes, and Colored Petri Net specifications to implement these processes. A multi-agent system platform provides agents able to interpret Colored Petri-Nets to enable the communication between the Healthcare Information Systems for executing the cross-organizational processes. Clinical documents are defined using the HL7 Clinical Document Architecture. This methodology guarantees that important requirements for healthcare services integration and coordination are fulfilled: interoperability between heterogeneous Healthcare Information Systems; ability to cope with changes in cross-organizational processes; guarantee of alignment between the integrated healthcare service solution defined at the organizational level and the solution defined at technological level; and the distributed execution of cross-organizational processes keeping the organizations autonomy. PMID:22434534
Thinking outside Discipline Boundaries to Integrate Indian Education for All across the Curriculum
ERIC Educational Resources Information Center
Carjuzaa, Jioanna; Hunts, Holly
2013-01-01
The Montana Indian Education for All (IEFA) Act is an unprecedented reform effort 40 years in the making. In this paper we summarize the IEFA professional development opportunities provided to faculty at a land grant university in the western United States while highlighting a faculty member's personal efforts to integrate IEFA in a culturally…
Nonequilibrium quantum dynamics and transport: from integrability to many-body localization
NASA Astrophysics Data System (ADS)
Vasseur, Romain; Moore, Joel E.
2016-06-01
We review the non-equilibrium dynamics of many-body quantum systems after a quantum quench with spatial inhomogeneities, either in the Hamiltonian or in the initial state. We focus on integrable and many-body localized systems that fail to self-thermalize in isolation and for which the standard hydrodynamical picture breaks down. The emphasis is on universal dynamics, non-equilibrium steady states and new dynamical phases of matter, and on phase transitions far from thermal equilibrium. We describe how the infinite number of conservation laws of integrable and many-body localized systems lead to complex non-equilibrium states beyond the traditional dogma of statistical mechanics.
NASA Astrophysics Data System (ADS)
Venville, Grady; Wallace, John; Rennie, Léonie; Malone, John
2000-01-01
The integration of content from the science, mathematics and technology learning areas is well grounded in the philosophy of middle schooling. However, there is a notable absence of recent empirical research to show if and/or how students learn science and mathematics concepts in integrated settings. This paper presents a case study of a Year 9 class that participated in a technology project constructing a solar boat involving science and mathematics components on electric circuits, statistical analysis, critical pathways and the reading of sun charts. The case study focuses on three pairs of students in the class and the results consists of three learning episodes that made up part of the students' learning experience. The discussion explores the nature of the students' learning and concludes that learning was enhanced as a result of the students' involvement in the solar boat project.
Integrating local and CRI online documentation using SGML and DynaWeb
Shuler, V.; Girill, T.R.
1997-04-01
This paper tells how Lawrence Livermore National Laboratory enriched CRI`s online documentation set by publishing local manuals using the same SGML DTD used by CRI and delivered using (a more sophisticated version of) the same World Wide Web server (DynaWeb3.0). This approach supports flexible local content and styles, yet integrates local and CRI manuals through one access mechanism and user interface. We explain the basic strategy involved, compare the benefits of this approach with three alternatives, and discuss the problems to which it gives rise.
NASA Astrophysics Data System (ADS)
Jackson, M.; Eriksson, S.; Barbour, K.; Venator, S.; Mencin, D.; Prescott, W.
2006-12-01
EarthScope is an NSF-funded, national science initiative to explore the structure and evolution of the North American continent and to understand the physical processes controlling earthquakes and volcanoes. This large-scale experiment provides locally based opportunities for education and outreach which engage students at various levels and the public. UNAVCO is responsible for the Plate Boundary Observatory (PBO) component of EarthScope. PBO includes the installation and operations and maintenance of large networks of Global Positioning Satellite (GPS), strainmeter, seismometer, and tiltmeter instruments and the acquisition of satellite radar imagery, all of which will be used to measure and map the smallest movements across faults, the magma movement inside active volcanoes and the very wide areas of deformation associated with plate tectonic motion. UNAVCO, through its own education and outreach activities and in collaboration with the EarthScope E&O Program, uses the PBO construction activities to increase the understanding and public appreciation of geodynamics, earth deformation processes, and their relevance to society. These include programs for public outreach via various media, events associated with local installations, a program to employ students in the construction of PBO, and development of curricular materials by use in local schools associated with the EarthScope geographic areas of focus. PBO provides information to the media to serve the needs of various groups and localities, including interpretive centers at national parks and forests, such as Mt. St. Helens. UNAVCO staff contributed to a television special with the Spanish language network Univision Aquí y Ahora program focused on the San Andreas Fault and volcanoes in Alaska. PBO participated in an Education Day at the Pathfinder Ranch Science and Outdoor Education School in Mountain Center, California. Pathfinder Ranch hosts two of the eight EarthScope borehole strainmeters in the Anza
Local fracture properties and dissimilar weld integrity in nuclear power plants
NASA Astrophysics Data System (ADS)
Wang, Guozhen; Wang, Haitao; Xuan, Fuzhen; Tu, Shantung; Liu, Changjun
2013-09-01
In this paper, the local fracture properties in a Alloy52M dissimilar metal welded joint (DMWJ) between A508 ferritic steel and 316 L stainless steel in nuclear power plants were investigated by using the single-edge notched bend (SENB) specimens, and their use in integrity assessment of DMWJ structures was analyzed. The results show that the local fracture resistance in the DMWJ is determined by local fracture mechanism, and which is mainly related to the microstructures and local strength mismatches of materials at the crack locations. The initial cracks always grow towards the materials with lower strength, and the crack path deviation is mainly controlled by the local strength mismatch. If the local fracture properties could not be used for cracks in the heat affected zones (HAZs), interface and near interface zones, the use of the fracture properties ( J-resistance curves) of base metals or weld metals following present codes will unavoidably produce non-conservative (unsafe) or excessive conservative assessment results. In most cases, the assessment results will be potentially unsafe. Therefore, it is recommended to obtain and use local mechanical and fracture properties in the integrity assessment of DMWJs.
NASA Astrophysics Data System (ADS)
Emter, Thomas; Petereit, Janko
2014-05-01
An integrated multi-sensor fusion framework for localization and mapping for autonomous navigation in unstructured outdoor environments based on extended Kalman filters (EKF) is presented. The sensors for localization include an inertial measurement unit, a GPS, a fiber optic gyroscope, and wheel odometry. Additionally a 3D LIDAR is used for simultaneous localization and mapping (SLAM). A 3D map is built while concurrently a localization in a so far established 2D map is estimated with the current scan of the LIDAR. Despite of longer run-time of the SLAM algorithm compared to the EKF update, a high update rate is still guaranteed by sophisticatedly joining and synchronizing two parallel localization estimators.
Durairaj, D Christopher; Krishna, Murali C; Murugesan, R
2004-12-01
A Windows-based, object-oriented application system for segmentation and analysis of electron magnetic resonance (EMR) images is described. The integrated system is developed for better recognition of regions of interest (ROI) in murine EMR images. The system combines the clustering method of color segmentation with boundary detection, for efficient segmentation of regions of interest in EMR images. Initially, the red/green/blue (RGB) color space is converted into spherical coordinates transform (SCT) space. Color quantization is then achieved by center split algorithm applied on the color dimensions of the SCT space. Subsequently, Laplacian boundary detection operator is used to extract the contours of the ROI from the variegated coloring information. The system is implemented in Visual C++ and tested on temporal EMR color images of mouse. The system performs well giving perceptually reasonable segmentation of tumor, kidney and bladder of the mouse image. Experimental results with extensive set of EMR color images demonstrate the efficacy of the system developed. PMID:15541951
NASA Technical Reports Server (NTRS)
Lua, Yuan J.; Liu, Wing K.; Belytschko, Ted
1993-01-01
In this paper, the mixed boundary integral equation method is developed to study the elastic interactions of a fatigue crack and a micro-defect such as a void, a rigid inclusion or a transformation inclusion. The method of pseudo-tractions is employed to study the effect of a transformation inclusion. An enriched element which incorporates the mixed-mode stress intensity factors is applied to characterize the singularity at a moving crack tip. In order to evaluate the accuracy of the numerical procedure, the analysis of a crack emanating from a circular hole in a finite plate is performed and the results are compared with the available numerical solution. The effects of various micro-defects on the crack path and fatigue life are investigated. The results agree with the experimental observations.
NASA Astrophysics Data System (ADS)
Sezen-Barrie, Asli; Moore, Joel; Roig, Cara E.
2015-08-01
Drawn from the norms and rules of their fields, scientists use variety of practices, such as asking questions and arguing based on evidence, to engage in research that will contribute to our understanding of Earth and beyond. In this study, we explore how preservice teachers' learn to teach scientific practices while teaching plate tectonic theory. In particular, our aim is to observe which scientific practices preservice teachers use while teaching an earth science unit, how do they integrate these practices into their lessons, and what challenges do they face during their first time teaching of an earth science content area integrated with scientific practices. The study is designed as a qualitative, exploratory case study of seven preservice teachers while they were learning to teach plate tectonic theory to a group of middle school students. The data were driven from the video records and artifacts of the preservice teachers' learning and teaching processes as well as written reflections on the teaching. Intertextual discourse analysis was used to understand what scientific practices preservice teachers choose to integrate into their teaching experience. Our results showed that preservice teachers chose to focus on four aspects of scientific practices: (1) employing historical understanding of how the theory emerged, (2) encouraging the use of evidence to build up a theory, (3) observation and interpretation of data maps, and (4) collaborative practices in making up the theory. For each of these practices, we also looked at the common challenges faced by preservice teachers by using constant comparative analysis. We observed the practices that preservice teachers decided to use and the challenges they faced, which were determined by what might have come as in their personal history as learners. Therefore, in order to strengthen preservice teachers' background, college courses should be arranged to teach important scientific ideas through scientific practices
NASA Astrophysics Data System (ADS)
Ronsin, J.; Barba, D.; Raboisson, S.
1986-04-01
We present an algorithm for texture characterization based upon curvilinear integration of grey tone signal along some predefined directions.In the context of image segmentation, we compare the performances of this very simple technique with two other ones : texture features by second-order cooccurrence probabilities, and texture features by local one dimensional histograms. Good classification performances are obtained on quite different pictures.
An Integrated Online Library System as a Node in a Local Area Network: The Mitre Experience.
ERIC Educational Resources Information Center
Kidwell, Mary Coyle
1987-01-01
Discusses the Mitre Corporation's implementation of OCLC's LS/2000 integrated library system using a local area network (LAN). LAN issues--requirements, equipment, reliability, growth, security, and traffic--are covered in general and as they relate to Mitre. Installation of the LAN/system interface and benefits and drawbacks of using a LAN for…
A Tough-Love Pedagogy in Rehabilitation: Integration of Rehabilitation Ideology with Local Cultures
ERIC Educational Resources Information Center
Chang, Ling-Hui; Wang, Jye
2009-01-01
This study problematizes a unique therapeutic relationship in rehabilitation and how the interaction reflects the integration of rehabilitation ideology with local cultures. The data drew from a larger ethnographic study of a rehabilitation unit in Taiwan. Participants included 21 patient-caregiver pairs and their rehabilitation professionals.…
NASA Technical Reports Server (NTRS)
Sloss, J. M.; Kranzler, S. K.
1972-01-01
The equivalence of a considered integral equation form with an infinite system of linear equations is proved, and the localization of the eigenvalues of the infinite system is expressed. Error estimates are derived, and the problems of finding upper bounds and lower bounds for the eigenvalues are solved simultaneously.
ERIC Educational Resources Information Center
Bodzin, Alec M.
2008-01-01
The author describes an after-school science club program for urban 4th-grade students that integrated instructional technologies to investigate a pond ecosystem in the local schoolyard. The author conducted a design-based evaluation study to examine the effectiveness of the program in promoting environmental attitudes and understandings of the…
S.R. Hudson; D.A. Monticello; A.H. Reiman; D.J. Strickler; S.P. Hirshman; L-P. Ku; E. Lazarus; A. Brooks; M.C. Zarnstorff; A.H. Boozer; G-Y. Fu; and G.H. Neilson
2003-09-15
For the (non-axisymmetric) stellarator class of plasma confinement devices to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux surfaces; however, the inherent lack of a continuous symmetry implies that magnetic islands responsible for breaking the smooth topology of the flux surfaces are guaranteed to exist. Thus, the suppression of magnetic islands is a critical issue for stellarator design, particularly for small aspect ratio devices. Pfirsch-Schluter currents, diamagnetic currents, and resonant coil fields contribute to the formation of magnetic islands, and the challenge is to design the plasma and coils such that these effects cancel. Magnetic islands in free-boundary high-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the Princeton Iterative Equilibrium Solver [Reiman and Greenside, Comp. Phys. Comm. 43 (1986) 157] which iterate s the equilibrium equations to obtain the plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. The changes are constrained to preserve certain measures of engineering acceptability and to preserve the stability of ideal kink modes. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible, the plasma is stable to ideal kink modes, and the coils satisfy engineering constraints. The method is applied to a candidate plasma and coil design for the National Compact Stellarator Experiment [Reiman, et al., Phys. Plasmas 8 (May 2001) 2083].
NASA Astrophysics Data System (ADS)
Wu, Xinyuan; Liu, Changying
2016-02-01
In this paper, we are concerned with the initial boundary value problem of arbitrarily high-dimensional Klein-Gordon equations, posed on a bounded domain Ω ⊂ ℝd for d ≥ 1 and equipped with the requirement of boundary conditions. We derive and analyze an integral formula which is proved to be adapted to different boundary conditions for general Klein-Gordon equations in arbitrarily high-dimensional spaces. The formula gives a closed-form solution to arbitrarily high-dimensional homogeneous linear Klein-Gordon equations, which is totally different from the well-known D'Alembert, Poisson, and Kirchhoff formulas. Some applications are included as well.
The Local Integrity Approach for Urban Contexts: Definition and Vehicular Experimental Assessment.
Margaria, Davide; Falletti, Emanuela
2016-01-01
A novel cooperative integrity monitoring concept, called "local integrity", suitable to automotive applications in urban scenarios, is discussed in this paper. The idea is to take advantage of a collaborative Vehicular Ad hoc NETwork (VANET) architecture in order to perform a spatial/temporal characterization of possible degradations of Global Navigation Satellite System (GNSS) signals. Such characterization enables the computation of the so-called "Local Protection Levels", taking into account local impairments to the received signals. Starting from theoretical concepts, this paper describes the experimental validation by means of a measurement campaign and the real-time implementation of the algorithm on a vehicular prototype. A live demonstration in a real scenario has been successfully carried out, highlighting effectiveness and performance of the proposed approach. PMID:26821028
Bernhard, Stefan; Möhlenkamp, Stefan; Tilgner, Andreas
2006-01-01
Background The pressure drop – flow relations in myocardial bridges and the assessment of vascular heart disease via fractional flow reserve (FFR) have motivated many researchers the last decades. The aim of this study is to simulate several clinical conditions present in myocardial bridges to determine the flow reserve and consequently the clinical relevance of the disease. From a fluid mechanical point of view the pathophysiological situation in myocardial bridges involves fluid flow in a time dependent flow geometry, caused by contracting cardiac muscles overlying an intramural segment of the coronary artery. These flows mostly involve flow separation and secondary motions, which are difficult to calculate and analyse. Methods Because a three dimensional simulation of the haemodynamic conditions in myocardial bridges in a network of coronary arteries is time-consuming, we present a boundary layer model for the calculation of the pressure drop and flow separation. The approach is based on the assumption that the flow can be sufficiently well described by the interaction of an inviscid core and a viscous boundary layer. Under the assumption that the idealised flow through a constriction is given by near-equilibrium velocity profiles of the Falkner-Skan-Cooke (FSC) family, the evolution of the boundary layer is obtained by the simultaneous solution of the Falkner-Skan equation and the transient von-Kármán integral momentum equation. Results The model was used to investigate the relative importance of several physical parameters present in myocardial bridges. Results have been obtained for steady and unsteady flow through vessels with 0 – 85% diameter stenosis. We compare two clinical relevant cases of a myocardial bridge in the middle segment of the left anterior descending coronary artery (LAD). The pressure derived FFR of fixed and dynamic lesions has shown that the flow is less affected in the dynamic case, because the distal pressure partially recovers
In-flight measurement of static pressures and boundary layer state with integrated sensors
NASA Astrophysics Data System (ADS)
Greff, E.
The reliable, integrated sensors for control-system feedback required by advanced transport aircraft wing designs incorporating adaptive geometry features for load control and performance optimization are presently evaluated. Absolute pressure transducers from various manufacturers were tested and adapted to the flight test environment; both laboratory and flight test results indicate steady measurement capabilities. It is shown that the sensing of pressure fluctuations in the wing-buffet regime will improve the prediction of operational limits. The pressure transducers were also used to investigate the laminar/turbulent transition in the attachment-line flow of a swept wing. A comparison of these results with those of hot film probes shows the transducers' effectiveness.
NASA Technical Reports Server (NTRS)
Yates, E. Carson, Jr.; Desmarais, Robert N.
1990-01-01
The technique of implicit differentiation has been used in combination with linearized lifting-surface theory to derive analytical expressions for aerodynamic sensitivities (i.e., rates of change of lifting pressures with respect to general changes in aircraft geometry, including planform variations) for steady or oscillating planar or nonplanar lifting surfaces in subsonic, sonic, or supersonic flow. The geometric perturbation is defined in terms of a single variable, and the user need only provide simple expressions or similar means for defining the continuous or discontinuous global or local perturbation of interest. Example expressions are given for perturbations of the sweep, taper, and aspect ratio of a wing with trapezoidal semispan planform. The present process appears to be readily adaptable to more general surface-panel methods.
NASA Astrophysics Data System (ADS)
Self-Trail, J. M.; Robinson, M. M.; Edwards, L. E.; Powars, D. S.; Wandless, G. A.; Willard, D. A.
2013-12-01
An exceptional Paleocene-Eocene boundary section occurs in a cluster of six short (<15m) coreholes (MCBR 1 through 6) drilled near Mattawoman Creek in western Charles County, Maryland. The sediments consist of glauconite-rich sand of the upper Paleocene Aquia Formation and silty clay of the lower Eocene Marlboro Clay. Sediment samples were analyzed for carbon and oxygen isotopes, percent calcium carbonate, calcareous nannofossils, planktic and benthic foraminifera, dinoflagellates, pollen, and lithology. A well-defined carbon isotope excursion (CIE) documents a gradual negative shift in δ13C values that starts below the lithologic break between the Aquia Formation and the Marlboro Clay. A benthic foraminifer extinction event, reduction of calcareous nannofossil assemblages, and change in core color from gray to alternating gray and pink also occurs within the CIE transition. These alternating changes in color coincide with cyclic peaks in the carbon isotope and percent calcium carbonate curves, where gray color corresponds to a positive shift in carbon isotope values and to a corresponding increase in percent benthic and planktic foraminifera. The upper third of the Marlboro Clay is barren of all calcareous microfossil material, although the presence of foraminiferal molds and linings proves that deposition occurred in a marine environment. Co-occurrence of the dinoflagellates Apectodinium augustum and Phthanoperidinium crenulatum at the top of the Marlboro Clay suggests that the Marlboro Clay at Mattawoman Creek is truncated. This is corroborated by the absence in the Marlboro of specimens of the calcareous nannofossil Rhomboaster-Discoaster assemblage, which is restricted to early Eocene Zone NP9b. Based on planktic/benthic foraminifera ratios, deposition of sediments at Mattawoman Creek occurred predominantly in an inner neritic environment, at water depths between 25-50 m. Occasional deepening to approximately 75m (middle neritic environment) occurred in the
NASA Astrophysics Data System (ADS)
Warner, Thomas T.; Sheu, Rong-Shyang
2000-05-01
Four 6-day simulations of the atmospheric conditions over the Arabian Desert during the time of the 1991 detonation and release of toxic material at the Khamisiyah, Iraq, weapons depot were performed using a mesoscale model run in a data-assimilation mode. These atmospheric simulations are being employed in a forensic analysis of the potential contribution of the toxic material to so-called Gulf War illness. The transport and concentration of such surface-released contaminants are related strongly to the planetary boundary layer (PBL) depth and the horizontal wind speed in the PBL. The product of the PBL depth and the mean wind speed within it is referred to as the ventilation and is used as a metric of the horizontal transport within the PBL. Thus, a corollary study to the larger forensic analysis involves employing the model solutions and available data in an analysis of the multiscale spatial variability of the daytime desert PBL depth and ventilation as they are affected by surface forcing from terrain elevation variations, coastal circulations, and contrasts in surface physical properties.The coarsest computational grid spanned the entire northern Arabian Desert and surrounding areas of the Middle East, and represented the large-scale PBL modulation by the orography. The PBL depths were greatest over the high elevations of the western Arabian Peninsula and over the Zagros Mountains in western Iran and were shallowest over water bodies and the lower elevations in the Tigris-Euphrates Valley. Higher-resolution grids in the nest (the smallest grid increment was 3.3 km) showed that the PBL depth minimum in the Tigris-Euphrates Valley was likely a consequence of compensating subsidence associated with the thermally forced daytime upward motion over the Zagros Mountains to the east in Iran, with possible contributions from an elevated mixed layer. Further local modulation of the daytime desert PBL occurred as a result of the inland penetration of the coastal sea
NASA Technical Reports Server (NTRS)
Tsiveriotis, K.; Brown, R. A.
1993-01-01
A new method is presented for the solution of free-boundary problems using Lagrangian finite element approximations defined on locally refined grids. The formulation allows for direct transition from coarse to fine grids without introducing non-conforming basis functions. The calculation of elemental stiffness matrices and residual vectors are unaffected by changes in the refinement level, which are accounted for in the loading of elemental data to the global stiffness matrix and residual vector. This technique for local mesh refinement is combined with recently developed mapping methods and Newton's method to form an efficient algorithm for the solution of free-boundary problems, as demonstrated here by sample calculations of cellular interfacial microstructure during directional solidification of a binary alloy.
Monitoring the northern Chile megathrust with the Integrated Plate boundary Observatory Chile (IPOC)
NASA Astrophysics Data System (ADS)
Schurr, Bernd; Asch, Günter; Cailleau, Beatrice; Diaz, Guillermo Chong; Barrientos, Sergio; Vilotte, Jean-Pierre; Oncken, Onno
2010-05-01
thousand aftershocks during the following week using waveform cross-correlation and the double-difference algorithm. Aftershocks reveal that rupture during this earthquake was confined to the deeper part (35 - 55 km depth) of the seismogenic coupling zone, except near the Mejillones peninsula that marks rupture termination in the south. Here earthquake activity reaches to depths of 20 km and even shallower, possibly indicating upper plate activation. The sequence also features an M 6.8 earthquake that broke the oceanic slab on an almost vertical plane at the down-dip end of the megathrust rupture. Confrontation with the aftershock distribution of the 1995 M 8.0 Antofagasta earthquake on the adjoining southern segment reveals an intriguing mirror symmetry with an axis crossing the Mejillones peninsula, emphasizing the penisula's significance as a segment boundary. Since then activity inside the remaining seismic gap to the north picked up with three earthquakes exceeding magnitude 6, maybe heralding the next great rupture.
NASA Astrophysics Data System (ADS)
Korotaev, Valery V.; Denisov, Victor M.; Rodrigues, Joel J. P. C.; Serikova, Mariya G.; Timofeev, Andrey V.
2015-05-01
The paper deals with the creation of integrated monitoring systems. They combine fiber-optic classifiers and local sensor networks. These systems allow for the monitoring of complex industrial objects. Together with adjacent natural objects, they form the so-called geotechnical systems. An integrated monitoring system may include one or more spatially continuous fiber-optic classifiers based on optic fiber and one or more arrays of discrete measurement sensors, which are usually combined in sensor networks. Fiber-optic classifiers are already widely used for the control of hazardous extended objects (oil and gas pipelines, railways, high-rise buildings, etc.). To monitor local objects, discrete measurement sensors are generally used (temperature, pressure, inclinometers, strain gauges, accelerometers, sensors measuring the composition of impurities in the air, and many others). However, monitoring complex geotechnical systems require a simultaneous use of continuous spatially distributed sensors based on fiber-optic cable and connected local discrete sensors networks. In fact, we are talking about integration of the two monitoring methods. This combination provides an additional way to create intelligent monitoring systems. Modes of operation of intelligent systems can automatically adapt to changing environmental conditions. For this purpose, context data received from one sensor (e.g., optical channel) may be used to change modes of work of other sensors within the same monitoring system. This work also presents experimental results of the prototype of the integrated monitoring system.
Fagerholm, Nora; Käyhkö, Niina; Van Eetvelde, Veerle
2013-09-01
In many developing countries, political documentation acknowledges the crucial elements of participation and spatiality for effective land use planning. However, operative approaches to spatial data inclusion and representation in participatory land management are often lacking. In this paper, we apply and develop an integrated landscape characterization approach to enhance spatial knowledge generation about the complex human-nature interactions in landscapes in the context of Zanzibar, Tanzania. We apply an integrated landscape conceptualization as a theoretical framework where the expert and local knowledge can meet in spatial context. The characterization is based on combining multiple data sources in GIS, and involves local communities and their local spatial knowledge since the beginning into the process. Focusing on the expected information needs for community forest management, our characterization integrates physical landscape features and retrospective landscape change data with place-specific community knowledge collected through participatory GIS techniques. The characterization is established in a map form consisting of four themes and their synthesis. The characterization maps are designed to support intuitive interpretation, express the inherently uncertain nature of the data, and accompanied by photographs to enhance communication. Visual interpretation of the characterization mediates information about the character of areas and places in the studied local landscape, depicting the role of forest resources as part of the landscape entity. We conclude that landscape characterization applied in GIS is a highly potential tool for participatory land and resource management, where spatial argumentation, stakeholder communication, and empowerment are critical issues. PMID:23934059
NASA Astrophysics Data System (ADS)
Fagerholm, Nora; Käyhkö, Niina; Van Eetvelde, Veerle
2013-09-01
In many developing countries, political documentation acknowledges the crucial elements of participation and spatiality for effective land use planning. However, operative approaches to spatial data inclusion and representation in participatory land management are often lacking. In this paper, we apply and develop an integrated landscape characterization approach to enhance spatial knowledge generation about the complex human-nature interactions in landscapes in the context of Zanzibar, Tanzania. We apply an integrated landscape conceptualization as a theoretical framework where the expert and local knowledge can meet in spatial context. The characterization is based on combining multiple data sources in GIS, and involves local communities and their local spatial knowledge since the beginning into the process. Focusing on the expected information needs for community forest management, our characterization integrates physical landscape features and retrospective landscape change data with place-specific community knowledge collected through participatory GIS techniques. The characterization is established in a map form consisting of four themes and their synthesis. The characterization maps are designed to support intuitive interpretation, express the inherently uncertain nature of the data, and accompanied by photographs to enhance communication. Visual interpretation of the characterization mediates information about the character of areas and places in the studied local landscape, depicting the role of forest resources as part of the landscape entity. We conclude that landscape characterization applied in GIS is a highly potential tool for participatory land and resource management, where spatial argumentation, stakeholder communication, and empowerment are critical issues.
Position of the American Dietetic Association: local support for nutrition integrity in schools.
Bergman, Ethan A; Gordon, Ruth W
2010-08-01
It is the position of the American Dietetic Association (ADA) that schools and communities have a shared responsibility to provide students with access to high-quality, affordable, nutritious foods and beverages. School-based nutrition services, including the provision of meals through the National School Lunch Program and the School Breakfast Program, are an integral part of the total education program. Strong wellness policies promote environments that enhance nutrition integrity and help students to develop lifelong healthy behaviors. ADA actively supported the 2004 and proposed 2010 Child Nutrition reauthorization which determines school nutrition policy. ADA believes that the Dietary Guidelines for Americans should serve as the foundation for all food and nutrition assistance programs and should apply to all foods and beverages sold or served to students during the school day. Local wellness policies are mandated by federal legislation for all school districts participating in the National School Lunch Program. These policies support nutrition integrity,including a healthy school environment. Nutrition integrity also requires coordinating nutrition education and promotion and funding research on program outcomes. Registered dietitians and dietetic technicians, registered, and other credentialed staff, are essential for nutrition integrity in schools to perform in policy-making, management, education, and community building roles. A healthy school environment can be achieved through adequate funding of school meals programs and through implementation and evaluation of strong local wellness policies. PMID:20677413
Liu, Lili; Zhang, Zijun; Mei, Qian; Chen, Ming
2013-01-01
Predicting the subcellular localization of proteins conquers the major drawbacks of high-throughput localization experiments that are costly and time-consuming. However, current subcellular localization predictors are limited in scope and accuracy. In particular, most predictors perform well on certain locations or with certain data sets while poorly on others. Here, we present PSI, a novel high accuracy web server for plant subcellular localization prediction. PSI derives the wisdom of multiple specialized predictors via a joint-approach of group decision making strategy and machine learning methods to give an integrated best result. The overall accuracy obtained (up to 93.4%) was higher than best individual (CELLO) by ~10.7%. The precision of each predicable subcellular location (more than 80%) far exceeds that of the individual predictors. It can also deal with multi-localization proteins. PSI is expected to be a powerful tool in protein location engineering as well as in plant sciences, while the strategy employed could be applied to other integrative problems. A user-friendly web server, PSI, has been developed for free access at http://bis.zju.edu.cn/psi/. PMID:24194827
Integrating communication theory and practice: Successes and challenges in boundary-spanning work
NASA Astrophysics Data System (ADS)
Weiss, M.; Fallon Lambert, K.
2014-12-01
The Science Policy Exchange (SPE) is a consortium of leaders in ecosystem research united to facilitate science from innovation to impact. In our unique model, we catalyze actionable science on pressing environmental issues such as climate change, and undertake comprehensive stakeholder engagement, public communication, and policy outreach. Built on more than 10 years of experience creating programs at the interface of science and policy at Hubbard Brook, Harvard Forest, and other LTER sites, we apply science communication research to practice in various ways depending on the context and problem being addressed. In keeping with the research on co-production and the importance of establishing credibility, salience, and legitimacy, we engage stakeholders from the outset of each project. Stakeholders and scientists collaborate to define the scope of the project, frame questions relevant to society, and define communication products to meet their needs. To promote broader distribution and uptake, we combine message development, storytelling, and media training to craft and deliver relatable stories that tap into news values and human values. Three recent SPE successes include: (1) Wildlands and Woodlands: A regional forest conservation report released in 2010 that generated 137 media stories and influenced land conservation policy, (2) Changes to the Land: A suite of communication products developed in 2013 for a landscape scenarios project in Massachusetts that saturated the state's media markets and have been widely cited by policymakers, and (3) Co-benefits of Carbon Standards: A national air quality report released in 2014 that was cited in 76 media stories and helped reframe the national debate on carbon dioxide emissions standards in terms of their potential local health and environmental benefits. We will describe our successful applications of science communication research and discuss several critical disconnections between research and practice. These include
Li, Lu; Peng, Hu; Chen, Xun; Cheng, Juan; Gao, Dayong
2016-04-01
Transfer function design is a key issue in direct volume rendering. Many sophisticated transfer functions have been proposed to visualize boundaries in volumetric data sets such as computed tomography and magnetic resonance imaging. However, it is still conventionally challenging to reliably detect boundaries. Meanwhile, the interactive strategy is complicated for new users or even experts. In this paper, we first propose the human-centric boundary extraction criteria and our boundary model. Based on the model we present a boundary visualization method through a what material you pick is what boundary you see approach. Users can pick out the material of interest to directly convey semantics. In addition, the 3-D canny edge detection is utilized to ensure the good localization of boundaries. Furthermore, we establish a point-to-material distance measure to guarantee the accuracy and integrity of boundaries. The proposed boundary visualization is intuitive and flexible for the exploration of volumetric data. PMID:26796353
NASA Technical Reports Server (NTRS)
Meredith, B. D.
1984-01-01
The evolutionary growth of the Space Station and the diverse activities onboard are expected to require a hierarchy of integrated,local area networks capable of supporting data, voice and video communications. In addition, fault tolerant network operation is necessary to protect communications between critical systems attached to the net and to relieve the valuable human resources onboard Space Station of day-to-day data system repair tasks. An experimental, local area network is being developed which will serve as a testbed for investigating candidate algorithms and technologies for a fault tolerant, integrated network. The establishment of a set of rules or protocols which govern communications on the net is essential to obtain orderly and reliable operation. A hierarchy of protocols for the experimental network is presented and procedures for data and control communications are described.
Synaptic Integration of Adult-Born Hippocampal Neurons Is Locally Controlled by Astrocytes.
Sultan, Sébastien; Li, Liyi; Moss, Jonathan; Petrelli, Francesco; Cassé, Frédéric; Gebara, Elias; Lopatar, Jan; Pfrieger, Frank W; Bezzi, Paola; Bischofberger, Josef; Toni, Nicolas
2015-12-01
Adult neurogenesis is regulated by the neurogenic niche, through mechanisms that remain poorly defined. Here, we investigated whether niche-constituting astrocytes influence the maturation of adult-born hippocampal neurons using two independent transgenic approaches to block vesicular release from astrocytes. In these models, adult-born neurons but not mature neurons showed reduced glutamatergic synaptic input and dendritic spine density that was accompanied with lower functional integration and cell survival. By taking advantage of the mosaic expression of transgenes in astrocytes, we found that spine density was reduced exclusively in segments intersecting blocked astrocytes, revealing an extrinsic, local control of spine formation. Defects in NMDA receptor (NMDAR)-mediated synaptic transmission and dendrite maturation were partially restored by exogenous D-serine, whose extracellular level was decreased in transgenic models. Together, these results reveal a critical role for adult astrocytes in local dendritic spine maturation, which is necessary for the NMDAR-dependent functional integration of newborn neurons. PMID:26606999
NASA Astrophysics Data System (ADS)
Zieniuk, Eugeniusz; Kapturczak, Marta; Sawicki, Dominik
2016-06-01
In solving of boundary value problems the shapes of the boundary can be modelled by the curves widely used in computer graphics. In parametric integral equations system (PIES) such curves are directly included into the mathematical formalism. Its simplify the way of definition and modification of the shape of the boundary. Until now in PIES the B-spline, Bézier and Hermite curves were used. Recent developments in the computer graphics paid our attention, therefore we implemented in PIES possibility of defining the shape of boundary using the NURBS curves. The curves will allow us to modeling different shapes more precisely. In this paper we will compare PIES solutions (with applied NURBS) with the solutions existing in the literature.
NASA Technical Reports Server (NTRS)
Zimmerle, D.; Bernhard, R. J.
1985-01-01
An alternative method for performing singular boundary element integrals for applications in linear acoustics is discussed. The method separates the integral of the characteristic solution into a singular and nonsingular part. The singular portion is integrated with a combination of analytic and numerical techniques while the nonsingular portion is integrated with standard Gaussian quadrature. The method may be generalized to many types of subparametric elements. The integrals over elements containing the root node are considered, and the characteristic solution for linear acoustic problems are examined. The method may be generalized to most characteristic solutions.
Passive Sensor Integration for Vehicle Self-Localization in Urban Traffic Environment.
Gu, Yanlei; Hsu, Li-Ta; Kamijo, Shunsuke
2015-01-01
This research proposes an accurate vehicular positioning system which can achieve lane-level performance in urban canyons. Multiple passive sensors, which include Global Navigation Satellite System (GNSS) receivers, onboard cameras and inertial sensors, are integrated in the proposed system. As the main source for the localization, the GNSS technique suffers from Non-Line-Of-Sight (NLOS) propagation and multipath effects in urban canyons. This paper proposes to employ a novel GNSS positioning technique in the integration. The employed GNSS technique reduces the multipath and NLOS effects by using the 3D building map. In addition, the inertial sensor can describe the vehicle motion, but has a drift problem as time increases. This paper develops vision-based lane detection, which is firstly used for controlling the drift of the inertial sensor. Moreover, the lane keeping and changing behaviors are extracted from the lane detection function, and further reduce the lateral positioning error in the proposed localization system. We evaluate the integrated localization system in the challenging city urban scenario. The experiments demonstrate the proposed method has sub-meter accuracy with respect to mean positioning error. PMID:26633420
Passive Sensor Integration for Vehicle Self-Localization in Urban Traffic Environment †
Gu, Yanlei; Hsu, Li-Ta; Kamijo, Shunsuke
2015-01-01
This research proposes an accurate vehicular positioning system which can achieve lane-level performance in urban canyons. Multiple passive sensors, which include Global Navigation Satellite System (GNSS) receivers, onboard cameras and inertial sensors, are integrated in the proposed system. As the main source for the localization, the GNSS technique suffers from Non-Line-Of-Sight (NLOS) propagation and multipath effects in urban canyons. This paper proposes to employ a novel GNSS positioning technique in the integration. The employed GNSS technique reduces the multipath and NLOS effects by using the 3D building map. In addition, the inertial sensor can describe the vehicle motion, but has a drift problem as time increases. This paper develops vision-based lane detection, which is firstly used for controlling the drift of the inertial sensor. Moreover, the lane keeping and changing behaviors are extracted from the lane detection function, and further reduce the lateral positioning error in the proposed localization system. We evaluate the integrated localization system in the challenging city urban scenario. The experiments demonstrate the proposed method has sub-meter accuracy with respect to mean positioning error. PMID:26633420
Calibration of a COTS Integration Cost Model Using Local Project Data
NASA Technical Reports Server (NTRS)
Boland, Dillard; Coon, Richard; Byers, Kathryn; Levitt, David
1997-01-01
The software measures and estimation techniques appropriate to a Commercial Off the Shelf (COTS) integration project differ from those commonly used for custom software development. Labor and schedule estimation tools that model COTS integration are available. Like all estimation tools, they must be calibrated with the organization's local project data. This paper describes the calibration of a commercial model using data collected by the Flight Dynamics Division (FDD) of the NASA Goddard Spaceflight Center (GSFC). The model calibrated is SLIM Release 4.0 from Quantitative Software Management (QSM). By adopting the SLIM reuse model and by treating configuration parameters as lines of code, we were able to establish a consistent calibration for COTS integration projects. The paper summarizes the metrics, the calibration process and results, and the validation of the calibration.
Liu, Zhiquan; Ma, Jianfeng; Jiang, Zhongyuan; Miao, Yinbin; Gao, Cong
2016-01-01
With the prevalence of Social Networks (SNs) and services, plenty of trust models for Trustworthy Service Recommendation (TSR) in Service-oriented SNs (S-SNs) have been proposed. The reputation-based schemes usually do not contain user preferences and are vulnerable to unfair rating attacks. Meanwhile, the local trust-based schemes generally have low reliability or even fail to work when the trust path is too long or does not exist. Thus it is beneficial to integrate them for TSR in S-SNs. This work improves the state-of-the-art Combining Global and Local Trust (CGLT) scheme and proposes a novel Integrating Reputation and Local Trust (IRLT) model which mainly includes four modules, namely Service Recommendation Interface (SRI) module, Local Trust-based Trust Evaluation (LTTE) module, Reputation-based Trust Evaluation (RTE) module and Aggregation Trust Evaluation (ATE) module. Besides, a synthetic S-SN based on the famous Advogato dataset is deployed and the well-known Discount Cumulative Gain (DCG) metric is employed to measure the service recommendation performance of our IRLT model with comparing to that of the excellent CGLT model. The results illustrate that our IRLT model is slightly superior to the CGLT model in honest environment and significantly outperforms the CGLT model in terms of the robustness against unfair rating attacks. PMID:26963089
Liu, Zhiquan; Ma, Jianfeng; Jiang, Zhongyuan; Miao, Yinbin; Gao, Cong
2016-01-01
With the prevalence of Social Networks (SNs) and services, plenty of trust models for Trustworthy Service Recommendation (TSR) in Service-oriented SNs (S-SNs) have been proposed. The reputation-based schemes usually do not contain user preferences and are vulnerable to unfair rating attacks. Meanwhile, the local trust-based schemes generally have low reliability or even fail to work when the trust path is too long or does not exist. Thus it is beneficial to integrate them for TSR in S-SNs. This work improves the state-of-the-art Combining Global and Local Trust (CGLT) scheme and proposes a novel Integrating Reputation and Local Trust (IRLT) model which mainly includes four modules, namely Service Recommendation Interface (SRI) module, Local Trust-based Trust Evaluation (LTTE) module, Reputation-based Trust Evaluation (RTE) module and Aggregation Trust Evaluation (ATE) module. Besides, a synthetic S-SN based on the famous Advogato dataset is deployed and the well-known Discount Cumulative Gain (DCG) metric is employed to measure the service recommendation performance of our IRLT model with comparing to that of the excellent CGLT model. The results illustrate that our IRLT model is slightly superior to the CGLT model in honest environment and significantly outperforms the CGLT model in terms of the robustness against unfair rating attacks. PMID:26963089
Carter, Erik W; Blustein, Carly L; Bumble, Jennifer L; Harvey, Sarah; Henderson, Lynnette M; McMillan, Elise D
2016-09-01
Amidst decades of attention directed toward improving employment outcomes for people with intellectual and developmental disabilities (IDD), few efforts have been made to engage communities in identifying local solutions for expanding integrated employment opportunities. We examined the implementation and outcomes of "community conversation" events held in 6 geographically and economically diverse locales. Each event used an asset-based dialogue approach called the World Café ( Brown & Isaacs, 2005 ) to solicit ideas from a broad cross-section of community members on improving integrated employment that reflect local priorities and possibilities. Six key themes encapsulated the 1,556 strategies generated by the almost 400 attendees. Although considerable consistency was found among the categories of strategies raised across events, the manner in which those individual strategies would be implemented locally reflected the unique accent of each community. Attendees also viewed these events as promising and productive pathways for identifying next steps for their community. We offer recommendations for community-level intervention efforts and suggest directions for future research. PMID:27611351
The Local Integrity Approach for Urban Contexts: Definition and Vehicular Experimental Assessment
Margaria, Davide; Falletti, Emanuela
2016-01-01
A novel cooperative integrity monitoring concept, called “local integrity”, suitable to automotive applications in urban scenarios, is discussed in this paper. The idea is to take advantage of a collaborative Vehicular Ad hoc NETwork (VANET) architecture in order to perform a spatial/temporal characterization of possible degradations of Global Navigation Satellite System (GNSS) signals. Such characterization enables the computation of the so-called “Local Protection Levels”, taking into account local impairments to the received signals. Starting from theoretical concepts, this paper describes the experimental validation by means of a measurement campaign and the real-time implementation of the algorithm on a vehicular prototype. A live demonstration in a real scenario has been successfully carried out, highlighting effectiveness and performance of the proposed approach. PMID:26821028
A Non-Local Low-Rank Approach to Enforce Integrability.
Badri, Hicham; Yahia, Hussein
2016-08-01
We propose a new approach to enforce integrability using recent advances in non-local methods. Our formulation consists in a sparse gradient data-fitting term to handle outliers together with a gradient-domain non-local low-rank prior. This regularization has two main advantages: 1) the low-rank prior ensures similarity between non-local gradient patches, which helps recovering high-quality clean patches from severe outliers corruption and 2) the low-rank prior efficiently reduces dense noise as it has been shown in recent image restoration works. We propose an efficient solver for the resulting optimization formulation using alternate minimization. Experiments show that the new method leads to an important improvement compared with previous optimization methods and is able to efficiently handle both outliers and dense noise mixed together. PMID:27214898
MacLaren, I; Sala, B; Andersson, S M L; Pennycook, T J; Xiong, J; Jia, Q X; Choi, E-M; MacManus-Driscoll, J L
2015-12-01
The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn(4+)-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions. PMID:26474888
NASA Astrophysics Data System (ADS)
MacLaren, I.; Sala, B.; Andersson, S. M. L.; Pennycook, T. J.; Xiong, J.; Jia, Q. X.; Choi, E.-M.; MacManus-Driscoll, J. L.
2015-10-01
The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn4+-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.
NASA Astrophysics Data System (ADS)
Bakkali, M.; Davies, M.; Steadman, J. P.
2012-04-01
We currently have an incomplete understanding of how weather varies across London and how the city's microclimate will intensify levels of heat, cold and air pollution in the future. There is a need to target priority areas of the city and to promote design guidance on climate change mitigation strategies. As a result of improvements in the accuracy of local weather data in London, an opportunity is emerging for designers and planners of the built environment to measure the impact of their designs on local urban climate and to enhance the designer's role in creating more informed design choices at an urban micro-scale. However, modelling the different components of the urban environment separately and then collating and comparing the results invariably leads to discrepancies in the output of local urban climate modelling tools designed to work at different scales. Of particular interest is why marked differences appear between the data extracted from local urban climate models when we change the scale of modelling from city to building scale. An example of such differences is those that have been observed in relation to the London Unified Model and London Site Specific Air Temperature model. In order to avoid these discrepancies we need a method for understanding and assessing how the urban environment impacts on local urban climate as a whole. A step to achieving this is by developing inter-linkages between assessment tools. Accurate information on the net impact of the urban environment on the local urban climate will in turn facilitate more accurate predictions of future energy demand and realistic scenarios for comfort and health. This paper will present two key topographies of London's urban environment that influence local urban climate: land use and street canyons. It will look at the possibilities for developing an integrated approach to modelling London's local urban climate from the neighbourhood to the street scale.
NASA Astrophysics Data System (ADS)
Maksimov, Vyacheslav I.; Nagornova, Tatiana A.; Glazyrin, Viktor P.
2016-02-01
Is solved the problem of heat transfer in the closed volume, limited by heat-conducting walls, with the local source of heat emission and the heterogeneous conditions of heat sink on the outer boundaries of solution area. The problem of convective heat transfer is solved with using a system of differential Navier-Stokes equations in the Boussinesq approximation. The simulation of turbulent flow conditions of heated air is carried out within the framework to k-ɛ model. On the basis the analysis of the obtained temperature field and the contour lines of stream functions is made conclusion about the essential transiency of the process in question. The obtained values of temperatures and speeds in different sections of region illustrate turbulence of the process. Are investigated laws governing the formation of temperature fields in closed areas with a local heat emission source under the conditions of intensive local heat sink into environment and accumulation of heat in the enclosing constructions.
NASA Astrophysics Data System (ADS)
Young, D. L.; Tsai, C. H.; Wu, C. S.
2015-11-01
An alternative vector potential formulation is used to solve the Navier-Stokes (N-S) equations in 3D incompressible viscous flow problems with and without through-flow boundaries. Difficulties of the vector potential formulation include the implementation of boundary conditions for through-flow boundaries and the numerical treatment of fourth-order partial differential equations. The advantages on the other hand are the automatic satisfaction of the continuity equation; and pressure is decoupled from the velocity. The objective of this paper is to introduce the appropriate gauge and boundary conditions on the vector potential formulation by a localized meshless method. To handle the divergence-free property, a Coulomb gauge condition is enforced on the vector potential to ensure its existence and uniqueness mathematically. We further improve the algorithm to through-flow problems for the boundary conditions of vector potential by introducing the concept of Stokes' theorem. Based on this innovation, there is no need to include an additional variable to tackle the through-flow fields. This process will greatly simplify the imposition of boundary conditions by the vector potential approach. Under certain conditions, the coupled fourth-order partial differential equations can be easily solved by using this meshless local differential quadrature (LDQ) method. Due to the LDQ capability to deal with the high order differential equations, this algorithm is very attractive to solve this fourth-order vector potential formulation for the N-S equations as comparing to the conventional numerical schemes such as finite element or finite difference methods. The proposed vector potential formulation is simpler and has improved accuracy and efficiency compared to other pressure-free or pressure-coupled algorithms. This investigation can be regarded as the first complete study to obtain the N-S solutions by vector potential formulation through a LDQ method. Two classic 3D benchmark
NASA Astrophysics Data System (ADS)
Ustaszewski, K. M.; Wu, Y.; Suppe, J.; Huang, H.; Carena, S.; Chang, C.
2011-12-01
We performed 3D mapping of crust-mantle boundaries in the Taiwan-Luzon arc-continent collision zone using a local earthquake tomographic model, providing better insight into the mode of subduction polarity reversal. The mapped crust-mantle discontinuities include three tectonically distinct Mohos. Furthermore, a crust-mantle boundary marks the eastern limit of the Eurasian lower crust against the mantle of the Philippine Sea plate. It dips steeply to the east underneath eastern and southern Taiwan and steepens progressively towards north until it becomes vertical at 23.7°N. From there it continues northward in a slightly overturned orientation, where the limit of the tomographic model at the northern tip of the island prevents further mapping. In order to map several Moho discontinuities, we contoured a surface of constant Vp = 7.5 km s-1 constrained from local earthquake tomography and confined to regions with a minimum of 500 rays per tomography cell. Additional constraints for the Moho were derived from layered (1D) Vp models using P-wave arrivals of local earthquakes recorded at 52 seismic stations, employing a genetic algorithm. The Moho of the Eurasian and the Philippine Sea plates are topologically disconnected across the plate boundary. Beneath southern Taiwan, the Eurasian Moho dips to the E at 50-60°, following the orientation of the plate boundary and continuous with the Benioff zone. Towards north, the Eurasian Moho twists to become subvertical, again together with the plate boundary. At the same time, it steps westward into a more external position underneath the thrust belt, giving way to the north-dipping Philippine Sea plate. The Philippine Sea plate Moho shallows towards the surface along the Longitudinal Valley suture. It forms a synform-like crustal root with an axis parallel to the trend of geological units at surface and it is interpreted as the base of the magmatic Luzon arc. Towards the north, the crustal root deepens from 30 km to about 70
Loss estimation of debris flow events in mountain areas - An integrated tool for local authorities
NASA Astrophysics Data System (ADS)
Papathoma-Koehle, M.; Zischg, A.; Fuchs, S.; Keiler, M.; Glade, T.
2012-04-01
Torrents prone to debris flows regularly cause extensive destruction of the built environment, loss of life stock, agricultural land and loss of life in mountain areas. Climate change may increase the frequency and intensity of such events. On the other hand, extensive development of mountain areas is expected to change the spatial pattern of elements at risk exposed and their vulnerability. Consequently, the costs of debris flow events are likely to increase in the coming years. Local authorities responsible for disaster risk reduction are in need of tools that may enable them to assess the future consequences of debris flow events, in particular with respect to the vulnerability of elements at risk. An integrated tool for loss estimation is presented here which is based on a newly developed vulnerability curve and which is applied in test sites in the Province of South Tyrol, Italy. The tool has a dual function: 1) continuous updating of the database regarding damages and process intensities that will eventually improve the existing vulnerability curve and 2) loss estimation of future events and hypothetical events or built environment scenarios by using the existing curve. The tool integrates the vulnerability curve together with new user friendly forms of damage documentation. The integrated tool presented here can be used by local authorities not only for the recording of damage caused by debris flows and the allocation of compensation to the owners of damaged buildings but also for land use planning, cost benefit analysis of structural protection measures and emergency planning.
Faas, F G A; Bárcena, M; Agronskaia, A V; Gerritsen, H C; Moscicka, K B; Diebolder, C A; van Driel, L F; Limpens, R W A L; Bos, E; Ravelli, R B G; Koning, R I; Koster, A J
2013-03-01
Correlative light and electron microscopy is an increasingly popular technique to study complex biological systems at various levels of resolution. Fluorescence microscopy can be employed to scan large areas to localize regions of interest which are then analyzed by electron microscopy to obtain morphological and structural information from a selected field of view at nm-scale resolution. Previously, an integrated approach to room temperature correlative microscopy was described. Combined use of light and electron microscopy within one instrument greatly simplifies sample handling, avoids cumbersome experimental overheads, simplifies navigation between the two modalities, and improves the success rate of image correlation. Here, an integrated approach for correlative microscopy under cryogenic conditions is presented. Its advantages over the room temperature approach include safeguarding the native hydrated state of the biological specimen, preservation of the fluorescence signal without risk of quenching due to heavy atom stains, and reduced photo bleaching. The potential of cryo integrated light and electron microscopy is demonstrated for the detection of viable bacteria, the study of in vitro polymerized microtubules, the localization of mitochondria in mouse embryonic fibroblasts, and for a search into virus-induced intracellular membrane modifications within mammalian cells. PMID:23261400
Maintaining a Local Data Integration System in Support of Weather Forecast Operations
NASA Technical Reports Server (NTRS)
Watson, Leela R.; Blottman, Peter F.; Sharp, David W.; Hoeth, Brian
2010-01-01
Since 2000, both the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) at Johnson Space Center in Houston, TX have used a local data integration system (LDIS) as part of their forecast and warning operations. The original LDIS was developed by NASA's Applied Meteorology Unit (AMU; Bauman et ai, 2004) in 1998 (Manobianco and Case 1998) and has undergone subsequent improvements. Each has benefited from three-dimensional (3-D) analyses that are delivered to forecasters every 15 minutes across the peninsula of Florida. The intent is to generate products that enhance short-range weather forecasts issued in support of NWS MLB and SMG operational requirements within East Central Florida. The current LDIS uses the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS) package as its core, which integrates a wide variety of national, regional, and local observational data sets. It assimilates all available real-time data within its domain and is run at a finer spatial and temporal resolution than current national- or regional-scale analysis packages. As such, it provides local forecasters with a more comprehensive understanding of evolving fine-scale weather features
Connecting the dots: how local structure affects global integration in infants
Palomares, Melanie; Pettet, Mark; Vildavski, Vladimir; Hou, Chuan; Norcia, Anthony
2009-01-01
Glass patterns are moirés created from a sparse random dot field paired with its spatially-shifted copy. Because discrimination of these patterns is not based on local features, they have been used extensively to study global integration processes. Here, we investigated whether 4–5.5 month old infants are sensitive to the global structure of Glass patterns by measuring Visual Evoked Potentials (VEPs). Although we found strong responses to the appearance of the constituent dots, we found sensitivity to the global structure of the Glass patterns in the infants only over a very limited range of spatial separation. In contrast, we observed robust responses in the infants when we connected the dot pairs of the Glass pattern with lines. Moreover, both infants and adults showed differential responses to exchanges between line patterns portraying different global structures. A control study varying luminance contrast in adults suggests that infant sensitivity to global structure is not primarily limited by reduced element visibility. Together our results suggest that the insensitivity to structure in conventional Glass patterns is due to inefficiencies in extracting the local orientation cues generated by the dot pairs. Once the local orientations are made unambiguous or when the interpolation span is small, infants can integrate these signals over the image. PMID:19642888
NASA Technical Reports Server (NTRS)
Burnel, S.; Gougat, P.; Martin, F.
1981-01-01
The natural instabilities which propagate in the laminar boundary layer of a flat plate composed of intermittent wave trains are described. A spectral analysis determines the frequency range and gives a frequency and the harmonic 2 only if there is a wall deformation. This analysis provides the amplitude modulation spectrum of the instabilities. Plots of the evolution of power spectral density are compared with the numerical results obtained from the resolve of the Orr-Sommerfeld equation, while the harmonic is related to a micro-recirculating flow near the wall deformation.
Doikou, Anastasia
2010-04-15
We examine the symmetry breaking of superalgebras due to the presence of appropriate integrable boundary conditions. We investigate the boundary breaking symmetry associated with both reflection algebras and twisted super-Yangians. We extract the generators of the resulting boundary symmetry as well as we provide explicit expressions of the associated Casimir operators.
NASA Astrophysics Data System (ADS)
Kleinert, H.
1989-06-01
The Feynman formula, which expresses the time displacement amplitude > x b | exp (-t Ȟ) | x a< in terms of a path integral Π 1N (∫ dn) Π 1N+1 ( {∫ dp n}/{2π}) exp{Σ 1N [ ip n(x n-x n-1) - ɛH (p n, x n)]} with large N, does not exist for systems with Coulomb {-1}/{r} potential and gives incorrect threshold behaviours near centrifugal {1}/{r 2} or angular {1}/{sin2θ } barriers. We discuss the physical origin of this failure and propose an alternative well-defined path integral formula based on a family of amplitudes that is invariant under arbitrary local time reparametrizations. The time slicing with finite N breaks this invariance. For appropriate choices of the reparametrization function the fluctuations are stabilized and the new formula is applicable to all the above systems.
Ambrosio, Leonardo A.; Hernández-Figueroa, Hugo E.
2011-01-01
Ordinary Bessel beams are described in terms of the generalized Lorenz-Mie theory (GLMT) by adopting, for what is to our knowledge the first time in the literature, the integral localized approximation for computing their beam shape coefficients (BSCs) in the expansion of the electromagnetic fields. Numerical results reveal that the beam shape coefficients calculated in this way can adequately describe a zero-order Bessel beam with insignificant difference when compared to other relative time-consuming methods involving numerical integration over the spherical coordinates of the GLMT coordinate system, or quadratures. We show that this fast and efficient new numerical description of zero-order Bessel beams can be used with advantage, for example, in the analysis of optical forces in optical trapping systems for arbitrary optical regimes. PMID:21750767
a GLOBAL-LOCAL Integrated Study of Roller Chain Meshing Dynamics
NASA Astrophysics Data System (ADS)
Liu, S. P.; Wang, K. W.; Hayek, S. I.; Trethewey, M. W.; Chen, F. H. K.
1997-05-01
It has been recognized that one of the most significant noise sources in roller chain drives is from impacts between the chain and the sprocket during their meshing process. In this paper an analysis is presented which integrates the local meshing phenomena with the global chain/sprocket system dynamic behaviour. A coupled chain/sprocket system interacting with local impacts is modelled and the impulse function is derived. A study is carried out to quantify the intensity of subsequent impacts. It is found that the coupling effects between the sprockets, the chain spans, and the chain/sprocket meshing impulses increase with decreasing sprocket inertia and chain longitudinal stiffness. Experimental studies are also carried out to evaluate the meshing noise. It is found experimentally that the meshing sound pressure level is closely related to the chain speed and its vibrational characteristics, as predicted in the analytical study.
Path-independent integrals to identify localized plastic events in two dimensions.
Talamali, Mehdi; Petäjä, Viljo; Vandembroucq, Damien; Roux, Stéphane
2008-07-01
We use a power expansion representation of plane-elasticity complex potentials due to Kolossov and Muskhelishvili to compute the elastic fields induced by a localized plastic deformation event. Far from its center, the dominant contributions correspond to first-order singularities of quadrupolar and dipolar symmetry which can be associated, respectively, with pure deviatoric and pure volumetric plastic strain of an equivalent circular inclusion. By construction of holomorphic functions from the displacement field and its derivatives, it is possible to define path-independent Cauchy integrals which capture the amplitudes of these singularities. Analytical expressions and numerical tests on simple finite-element data are presented. The development of such numerical tools is of direct interest for the identification of local structural reorganizations, which are believed to be the key mechanisms for plasticity of amorphous materials. PMID:18764022
Quasi-local conserved charges and spin transport in spin-1 integrable chains
NASA Astrophysics Data System (ADS)
Piroli, Lorenzo; Vernier, Eric
2016-05-01
We consider the integrable one-dimensional spin-1 chain defined by the Zamolodchikov–Fateev (ZF) Hamiltonian. The latter is parametrized, analogously to the XXZ spin-1/2 model, by a continuous anisotropy parameter and at the isotropic point coincides with the well-known spin-1 Babujian–Takhtajan Hamiltonian. Following a procedure recently developed for the XXZ model, we explicitly construct a continuous family of quasi-local conserved operators for the periodic spin-1 ZF chain. Our construction is valid for a dense set of commensurate values of the anisotropy parameter in the gapless regime where the isotropic point is excluded. Using the Mazur inequality, we show that, as for the XXZ model, these quasi-local charges are enough to prove that the high-temperature spin Drude weight is non-vanishing in the thermodynamic limit, thus establishing ballistic spin transport at high temperature.
Tolerance for local and global differences in the integration of shape information.
Dickinson, J Edwin; Cribb, Serena J; Riddell, Hugh; Badcock, David R
2015-01-01
Shape is a critical cue to object identity. In psychophysical studies, radial frequency (RF) patterns, paths deformed from circular by a sinusoidal modulation of radius, have proved valuable stimuli for the demonstration of global integration of local shape information. Models of the mechanism of integration have focused on the periodicity in measures of curvature on the pattern, despite the fact that other properties covary. We show that patterns defined by rectified sinusoidal modulation also exhibit global integration and are indistinguishable from conventional RF patterns at their thresholds for detection, demonstrating some indifference to the modulating function. Further, irregular patterns incorporating four different frequencies of modulation are globally integrated, indicating that uniform periodicity is not critical. Irregular patterns can be handed in the sense that mirror images cannot be superimposed. We show that mirror images of the same irregular pattern could not be discriminated near their thresholds for detection. The same irregular pattern and a pattern with four cycles of a constant frequency of modulation completing 2π radians were, however, perfectly discriminated, demonstrating the existence of discrete representations of these patterns by which they are discriminated. It has previously been shown that RF patterns of different frequencies are perfectly discriminated but that patterns with the same frequency but different numbers of cycles of modulation were not. We conclude that such patterns are identified, near threshold, by the set of angles subtended at the center of the pattern by adjacent points of maximum convex curvature. PMID:25814547
Maintaining a Local Data Integration System in Support of Weather Forecast Operations
NASA Technical Reports Server (NTRS)
Watson, Leela R.; Blottman, Peter F.; Sharp, David W.; Hoeth, Brian
2010-01-01
Since 2000, both the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) have used a local data integration system (LDIS) as part of their forecast and warning operations. Each has benefited from 3-dimensional analyses that are delivered to forecasters every 15 minutes across the peninsula of Florida. The intent is to generate products that enhance short-range weather forecasts issued in support of NWS MLB and SMG operational requirements within East Central Florida. The current LDIS uses the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS) package as its core, which integrates a wide variety of national, regional, and local observational data sets. It assimilates all available real-time data within its domain and is run at a finer spatial and temporal resolution than current national- or regional-scale analysis packages. As such, it provides local forecasters with a more comprehensive and complete understanding of evolving fine-scale weather features. Recent efforts have been undertaken to update the LDIS through the formal tasking process of NASA's Applied Meteorology Unit. The goals include upgrading LDIS with the latest version of ADAS, incorporating new sources of observational data, and making adjustments to shell scripts written to govern the system. A series of scripts run a complete modeling system consisting of the preprocessing step, the main model integration, and the post-processing step. The preprocessing step prepares the terrain, surface characteristics data sets, and the objective analysis for model initialization. Data ingested through ADAS include (but are not limited to) Level II Weather Surveillance Radar- 1988 Doppler (WSR-88D) data from six Florida radars, Geostationary Operational Environmental Satellites (GOES) visible and infrared satellite imagery, surface and upper air observations throughout Florida from NOAA's Earth System Research Laboratory/Global Systems Division
Józefowicz, W; Cholewiak, G; Longa, L
2005-03-01
The main focus of the present paper is on studying the nematic-smectic- A phase boundary of an ideally oriented Gay-Berne system. The phase diagram is determined by means of an isothermal-isobaric Monte Carlo simulation. The results are compared with predictions of the local density functional expanded up to second and third order in the one-particle distribution function. It is shown that generally the second-order expansion does not give satisfactory predictions for smectics. Going beyond the leading order yields good quantitative agreement at moderate densities. With increasing density the relative error of the local density functional calculations increases, but usually does not exceed 10% in densities. We conclude that the density functional approach could be competitive to time-consuming simulations in determining phase diagrams of spatially and orientationally ordered liquid crystalline structures. PMID:15903474
NASA Astrophysics Data System (ADS)
Józefowicz, W.; Cholewiak, G.; Longa, L.
2005-03-01
The main focus of the present paper is on studying the nematic-smectic- A phase boundary of an ideally oriented Gay-Berne system. The phase diagram is determined by means of an isothermal-isobaric Monte Carlo simulation. The results are compared with predictions of the local density functional expanded up to second and third order in the one-particle distribution function. It is shown that generally the second-order expansion does not give satisfactory predictions for smectics. Going beyond the leading order yields good quantitative agreement at moderate densities. With increasing density the relative error of the local density functional calculations increases, but usually does not exceed 10% in densities. We conclude that the density functional approach could be competitive to time-consuming simulations in determining phase diagrams of spatially and orientationally ordered liquid crystalline structures.
Brain response to prosodic boundary cues depends on boundary position
Holzgrefe, Julia; Wellmann, Caroline; Petrone, Caterina; Truckenbrodt, Hubert; Höhle, Barbara; Wartenburger, Isabell
2013-01-01
Prosodic information is crucial for spoken language comprehension and especially for syntactic parsing, because prosodic cues guide the hearer's syntactic analysis. The time course and mechanisms of this interplay of prosody and syntax are not yet well-understood. In particular, there is an ongoing debate whether local prosodic cues are taken into account automatically or whether they are processed in relation to the global prosodic context in which they appear. The present study explores whether the perception of a prosodic boundary is affected by its position within an utterance. In an event-related potential (ERP) study we tested if the brain response evoked by the prosodic boundary differs when the boundary occurs early in a list of three names connected by conjunctions (i.e., after the first name) as compared to later in the utterance (i.e., after the second name). A closure positive shift (CPS)—marking the processing of a prosodic phrase boundary—was elicited for stimuli with a late boundary, but not for stimuli with an early boundary. This result is further evidence for an immediate integration of prosodic information into the parsing of an utterance. In addition, it shows that the processing of prosodic boundary cues depends on the previously processed information from the preceding prosodic context. PMID:23882234
NASA Astrophysics Data System (ADS)
Li, Min; Xu, Tao; Wang, Lei
2016-04-01
In this paper, the modified nonlinear Schrödinger equation is investigated via the direct perturbation method, which can describe the femtosecond optical pulse propagation in a monomodal optical fiber. Considering the quintic nonlinear perturbation, we obtain the approximate solution with the first-order correction, which can be expressed by the solution and symmetry of the derivative nonlinear Schrödinger equation. Under the nonvanishing boundary conditions, the approximate dark and anti-dark soliton solutions are derived and the existence conditions are also given. The effects of the perturbation on the propagations and interactions of the solitons on the nonzero background are discussed by comparing the physical quantities of solitons with the unperturbed case. It is found that the quintic nonlinear perturbation can lead to the change of the velocity as well as the pulse compression, but has no influence on the dynamics of the elastic interactions. Finally, numerical simulations are performed to support the theoretical results.
NASA Technical Reports Server (NTRS)
Rzasnicki, W.
1973-01-01
A method of solution is presented, which, when applied to the elasto-plastic analysis of plates having a v-notch on one edge and subjected to pure bending, will produce stress and strain fields in much greater detail than presently available. Application of the boundary integral equation method results in two coupled Fredholm-type integral equations, subject to prescribed boundary conditions. These equations are replaced by a system of simultaneous algebraic equations and solved by a successive approximation method employing Prandtl-Reuss incremental plasticity relations. The method is first applied to number of elasto-static problems and the results compared with available solutions. Good agreement is obtained in all cases. The elasto-plastic analysis provides detailed stress and strain distributions for several cases of plates with various notch angles and notch depths. A strain hardening material is assumed and both plane strain and plane stress conditions are considered.
Mehl, Steffen W.; Hill, Mary C.
2013-01-01
This report documents the addition of ghost node Local Grid Refinement (LGR2) to MODFLOW-2005, the U.S. Geological Survey modular, transient, three-dimensional, finite-difference groundwater flow model. LGR2 provides the capability to simulate groundwater flow using multiple block-shaped higher-resolution local grids (a child model) within a coarser-grid parent model. LGR2 accomplishes this by iteratively coupling separate MODFLOW-2005 models such that heads and fluxes are balanced across the grid-refinement interface boundary. LGR2 can be used in two-and three-dimensional, steady-state and transient simulations and for simulations of confined and unconfined groundwater systems. Traditional one-way coupled telescopic mesh refinement methods can have large, often undetected, inconsistencies in heads and fluxes across the interface between two model grids. The iteratively coupled ghost-node method of LGR2 provides a more rigorous coupling in which the solution accuracy is controlled by convergence criteria defined by the user. In realistic problems, this can result in substantially more accurate solutions and require an increase in computer processing time. The rigorous coupling enables sensitivity analysis, parameter estimation, and uncertainty analysis that reflects conditions in both model grids. This report describes the method used by LGR2, evaluates accuracy and performance for two-and three-dimensional test cases, provides input instructions, and lists selected input and output files for an example problem. It also presents the Boundary Flow and Head (BFH2) Package, which allows the child and parent models to be simulated independently using the boundary conditions obtained through the iterative process of LGR2.
NASA Astrophysics Data System (ADS)
McNamara, J. P.; Aishlin, P. S.; Flores, A. N.; Benner, S. G.; Marshall, H. P.; Pierce, J. L.
2014-12-01
While a proliferation of instrumented research watersheds and new data sharing technologies has transformed hydrologic research in recent decades, similar advances have not been realized in hydrologic education. Long-standing problems in hydrologic education include discontinuity of hydrologic topics from introductory to advanced courses, inconsistency of content across academic departments, and difficulties in development of laboratory and homework assignments utilizing large time series and spatial data sets. Hydrologic problems are typically not amenable to "back-of-the-chapter" examples. Local, long-term research watersheds offer solutions to these problems. Here, we describe our integration of research and monitoring programs in the Dry Creek Experimental Watershed into undergraduate and graduate hydrology programs at Boise State University. We developed a suite of watershed-based exercises into courses and curriculums using real, tangible datasets from the watershed to teach concepts not amenable to traditional textbook and lecture methods. The aggregation of exercises throughout a course or degree allows for scaffolding of concepts with progressive exposure of advanced concepts throughout a course or degree. The need for exercises of this type is growing as traditional lecture-based classes (passive learning from a local authoritative source) are being replaced with active learning courses that integrate many sources of information through situational factors.
Leske, Sabine; Ruhnau, Philipp; Frey, Julia; Lithari, Chrysa; Müller, Nadia; Hartmann, Thomas; Weisz, Nathan
2015-01-01
An ever-increasing number of studies are pointing to the importance of network properties of the brain for understanding behavior such as conscious perception. However, with regards to the influence of prestimulus brain states on perception, this network perspective has rarely been taken. Our recent framework predicts that brain regions crucial for a conscious percept are coupled prior to stimulus arrival, forming pre-established pathways of information flow and influencing perceptual awareness. Using magnetoencephalography (MEG) and graph theoretical measures, we investigated auditory conscious perception in a near-threshold (NT) task and found strong support for this framework. Relevant auditory regions showed an increased prestimulus interhemispheric connectivity. The left auditory cortex was characterized by a hub-like behavior and an enhanced integration into the brain functional network prior to perceptual awareness. Right auditory regions were decoupled from non-auditory regions, presumably forming an integrated information processing unit with the left auditory cortex. In addition, we show for the first time for the auditory modality that local excitability, measured by decreased alpha power in the auditory cortex, increases prior to conscious percepts. Importantly, we were able to show that connectivity states seem to be largely independent from local excitability states in the context of a NT paradigm. PMID:26408799
The role of size constancy for the integration of local elements into a global shape
Rennig, Johannes; Karnath, Hans-Otto; Huberle, Elisabeth
2013-01-01
Visual perception depends on the visual context and is likely to be influenced by size constancy, which predicts a size and distance invariant perception of objects. However, size constancy can also result in optical illusions that allow the manipulation of the perceived size. We thus asked whether the integration of local elements into a global object can be influenced by manipulations of the visual context and size constancy? A set of stimuli was applied in healthy individuals that took advantage of the “Kanizsa” illusion, in which three circles with open wedges oriented toward a center point are placed to form an illusionary perception of a triangle. In addition, a 3D-perspective view was implemented in which the global target (“Kanizsa” triangle) was placed in combination with several distractor circles either in a close or a distant position. Subjects were engaged in a global recognition task on the location of the “Kanizsa” triangle. Global recognition of “Kanizsa” triangles improved with a decreasing length of the illusory contour. Interestingly, recognition of “Kanizsa” triangles decreased when they were perceived as if they were located further away. We conclude that the integration of local elements into a global object is dependent on the visual context and dominated by size constancy. PMID:23840187
An integrative review of information systems and terminologies used in local health departments
Olsen, Jeanette; Baisch, Mary Jo
2014-01-01
Objective The purpose of this integrative review based on the published literature was to identify information systems currently being used by local health departments and to determine the extent to which standard terminology was used to communicate data, interventions, and outcomes to improve public health informatics at the local health department (LHD) level and better inform research, policy, and programs. Materials and methods Whittemore and Knafl's integrative review methodology was used. Data were obtained through key word searches of three publication databases and reference lists of retrieved articles and consulting with experts to identify landmark works. The final sample included 45 articles analyzed and synthesized using the matrix method. Results The results indicated a wide array of information systems were used by LHDs and supported diverse functions aligned with five categories: administration; surveillance; health records; registries; and consumer resources. Detail regarding specific programs being used, location or extent of use, or effectiveness was lacking. The synthesis indicated evidence of growing interest in health information exchange groups, yet few studies described use of data standards or standard terminology in LHDs. Discussion Research to address these gaps is needed to provide current, meaningful data that inform public health informatics research, policy, and initiatives at and across the LHD level. Conclusions Coordination at a state or national level is recommended to collect information efficiently about LHD information systems that will inform improvements while minimizing duplication of efforts and financial burden. Until this happens, efforts to strengthen LHD information systems and policies may be significantly challenged. PMID:24036156
Leske, Sabine; Ruhnau, Philipp; Frey, Julia; Lithari, Chrysa; Müller, Nadia; Hartmann, Thomas; Weisz, Nathan
2015-12-01
An ever-increasing number of studies are pointing to the importance of network properties of the brain for understanding behavior such as conscious perception. However, with regards to the influence of prestimulus brain states on perception, this network perspective has rarely been taken. Our recent framework predicts that brain regions crucial for a conscious percept are coupled prior to stimulus arrival, forming pre-established pathways of information flow and influencing perceptual awareness. Using magnetoencephalography (MEG) and graph theoretical measures, we investigated auditory conscious perception in a near-threshold (NT) task and found strong support for this framework. Relevant auditory regions showed an increased prestimulus interhemispheric connectivity. The left auditory cortex was characterized by a hub-like behavior and an enhanced integration into the brain functional network prior to perceptual awareness. Right auditory regions were decoupled from non-auditory regions, presumably forming an integrated information processing unit with the left auditory cortex. In addition, we show for the first time for the auditory modality that local excitability, measured by decreased alpha power in the auditory cortex, increases prior to conscious percepts. Importantly, we were able to show that connectivity states seem to be largely independent from local excitability states in the context of a NT paradigm. PMID:26408799
Development of local oscillator integrated antenna array for microwave imaging diagnostics
NASA Astrophysics Data System (ADS)
Kuwahara, D.; Ito, N.; Nagayama, Y.; Tsuchiya, H.; Yoshikawa, M.; Kohagura, J.; Yoshinaga, T.; Yamaguchi, S.; Kogi, Y.; Mase, A.; Shinohara, S.
2015-12-01
Microwave imaging diagnostics are powerful tools that are used to obtain details of complex structures and behaviors of such systems as magnetically confined plasmas. For example, microwave imaging reflectometry and microwave imaging interferometers are suitable for observing phenomena that are involved with electron density fluctuations; moreover, electron cyclotron emission imaging diagnostics enable us to accomplish the significant task of observing MHD instabilities in large tokamaks. However, microwave imaging systems include difficulties in terms of multi-channelization and cost. Recently, we solved these problems by developing a Horn-antenna Mixer Array (HMA), a 50 - 110 GHz 1-D heterodyne- type antenna array, which can be easily stacked as a 2-D receiving array, because it uses an end-fire element. However, the HMA still evidenced problems owing to the requirement for local oscillation (LO) optics and an expensive high-power LO source. To solve this problem, we have developed an upgraded HMA, named the Local Integrated Antenna array (LIA), in which each channel has an internal LO supply using a frequency multiplier integrated circuit. Therefore, the proposed antenna array eliminates the need for both the LO optics and the high-power LO source. This paper describes the principle of the LIA, and provides details about an 8 channel prototype LIA.
Han, Ke-Jun; Foster, Daniel; Harhaj, Edward W; Dzieciatkowska, Monika; Hansen, Kirk; Liu, Chang-Wei
2016-04-01
Low levels of the survival motor neuron (SMN) protein cause spinal muscular atrophy, the leading genetic disorder for infant mortality. SMN is ubiquitously expressed in various cell types and localizes in both the cytoplasm and the nucleus, where it concentrates in two subnuclear structures termed Cajal body (CB) and gems. In addition, SMN can also be detected in the nucleolus of neurons. Mechanisms that control SMN sorting in the cell remain largely unknown. Here, we report that the ubiquitin (Ub) ligase Itch directly interacts with and monoubiquitinates SMN. Monoubiquitination of SMN has a mild effect on promoting proteasomal degradation of SMN. We generated two SMN mutants, SMN(K0), in which all lysines are mutated to arginines and thereby abolishing SMN ubiquitination, and Ub-SMN(K0), in which a single Ub moiety is fused at the N-terminus of SMN(K0) and thereby mimicking SMN monoubiquitination. Immunostaining assays showed that SMN(K0) mainly localizes in the nucleus, whereas Ub-SMN(K0) localizes in both the cytoplasm and the nucleolus in neuronal SH-SY5Y cells. Interestingly, canonical CB foci and coilin/small nuclear ribonucleoprotein (snRNP) co-localization are significantly impaired in SH-SY5Y cells stably expressing SMN(K0) or Ub-SMN(K0). Thus, our studies discover that Itch monoubiquitinates SMN and monoubiquitination of SMN plays an important role in regulating its cellular localization. Moreover, mislocalization of SMN disrupts CB integrity and likely impairs snRNP maturation. PMID:26908624
NASA Astrophysics Data System (ADS)
Hristov, Jordan
2016-03-01
Closed form approximate solutions to nonlinear heat (mass) diffusion equation with power-law nonlinearity of the thermal (mass) diffusivity have been developed by the integral-balance method avoiding the commonly used linearization by the Kirchhoff transformation. The main improvement of the solution is based on the double-integration technique and a new approach to the space derivative. Solutions to Dirichlet and Neumann boundary condition problems have been developed and benchmarked against exact numerical and approximate analytical solutions available in the literature.
The Local Gromov-Witten Theory of {{C}{P}^1} and Integrable Hierarchies
NASA Astrophysics Data System (ADS)
Brini, Andrea
2012-08-01
In this paper we begin the study of the relationship between the local Gromov-Witten theory of Calabi-Yau rank two bundles over the projective line and the theory of integrable hierarchies. We first of all construct explicitly, in a large number of cases, the Hamiltonian dispersionless hierarchies that govern the full-descendent genus zero theory. Our main tool is the application of Dubrovin's formalism, based on associativity equations, to the known results on the genus zero theory from local mirror symmetry and localization. The hierarchies we find are apparently new, with the exception of the resolved conifold {{{O}_{{P}^1}(-1) bigoplus {O}_{{P}^1}(-1)}} in the equivariantly Calabi-Yau case. For this example the relevant dispersionless system turns out to be related to the long-wave limit of the Ablowitz-Ladik lattice. This identification provides us with a complete procedure to reconstruct the dispersive hierarchy which should conjecturally be related to the higher genus theory of the resolved conifold. We give a complete proof of this conjecture for genus g ≤ 1; our methods are based on establishing, analogously to the case of KdV, a "quasi-triviality" property for the Ablowitz-Ladik hierarchy at the leading order of the dispersive expansion. We furthermore provide compelling evidence in favour of the resolved conifold/Ablowitz-Ladik correspondence at higher genus by testing it successfully in the primary sector for g = 2.
NASA Astrophysics Data System (ADS)
Ros, V.; Müller, M.; Scardicchio, A.
2015-11-01
We correct a small error in our article Integrals of motion in the many body localized phase[1]. The correction does not alter the main result regarding the convergence of the perturbative expansion for integrals of motion in forward approximation, but reduces the estimate of the radius of convergence by a numerical factor of roughly ≃1.79.
NASA Astrophysics Data System (ADS)
Celli, Michele; Barletta, Antonio; Storesletten, Leiv
2014-04-01
The effects of lack of local thermal equilibrium between the solid phase and the fluid phase are taken into account for the convective stability analysis of a horizontal porous layer. The layer is bounded by a pair of plane parallel walls which are impermeable and such that the lower wall is subject to a uniform flux heating, while the upper wall is isothermal. The local thermal non-equilibrium is modelled through a two-temperature formulation of the energy exchange between the phases, resulting in a pair of local energy balance equations: one for each phase. Small-amplitude disturbances of the basic rest state are envisaged to test the stability. Then, the standard normal mode procedure is adopted to detect the onset conditions of convective rolls. Beyond the Darcy-Rayleigh number, playing the role of order parameter for the transition to instability, the relevant dimensionless parameters are the inter-phase heat transfer parameter and the thermal conductivity ratio. The disturbance governing equations, formulated as an eigenvalue problem, are solved numerically by a shooting method. Results are reported for the neutral stability curves and for the critical values for the onset of instability.
NASA Astrophysics Data System (ADS)
Foley, J. A.
2011-12-01
Although they have been building for decades, changes in the environment are not always smooth and gradual. In fact, the most important changes - such as those to our ecosystems and natural resources - are often sudden and large. Recent research suggests that instead of following a predictable linear path along existing trends, environmental systems often exhibit highly non-linear behavior, including very abrupt shifts in condition. In fact, the complex, non-linear workings of the planet's biological, physical and human systems can give rise to sudden, often catastrophic, environmental disasters. Recent scientific advances have shown can exhibit "tipping points" or "regime shifts". Examples of regime shifts range from lake eutrophication, desertification, and forest die-back, across many regions of the world. But do such regime shifts exist at the global scale? A recent synthesis of global environmental research (published by Rockstrom et al., in Nature, 2010) suggested that there may be "Planetary Boundaries", beyond which the global environment would enter conditions not seen in the Holocene era. In this presentation, I will review case studies of environmental regime shifts at regional scales, and show how they may or may not operate at global scales. Managing such complex systems, across regional and global scales, will be a fundamental challenge as humanity charts attempts to chart a more sustainability path.
Shoberg, Thomas G.; Stoddard, Paul R.
2013-01-01
The ability to augment local gravity surveys with additional gravity stations from easily accessible national databases can greatly increase the areal coverage and spatial resolution of a survey. It is, however, necessary to integrate such data seamlessly with the local survey. One challenge to overcome in integrating data from national databases is that these data are typically of unknown quality. This study presents a procedure for the evaluation and seamless integration of gravity data of unknown quality from a national database with data from a local Global Positioning System (GPS)-based survey. The starting components include the latitude, longitude, elevation and observed gravity at each station location. Interpolated surfaces of the complete Bouguer anomaly are used as a means of quality control and comparison. The result is an integrated dataset of varying quality with many stations having GPS accuracy and other reliable stations of unknown origin, yielding a wider coverage and greater spatial resolution than either survey alone.
The South West Local Health Integration Network Behavioural Supports Ontario Experience.
Gutmanis, Iris; Speziale, Jennifer; Van Bussel, Lisa; Girard, Julie; Hillier, Loretta; Simpson, Kelly
2016-01-01
Creating a seamless system of care with improved system and patient outcomes is imperative to the estimated 35,000 older adults living with mental health problems and addictions in the South West Local Health Integration Network. Building on existing investments and those offered through the Behavioural Supports Ontario program, strategies to improve system coordination were put in place, cross-sectoral partnerships were fostered, interdisciplinary teams from across the care continuum were linked, and educational opportunities were promoted. This evolving, co-created system has resulted in a decrease in alternate level of care cases among those with behavioural specialized needs and improved client/family perceptions of care. Also, in fiscal year 2014/15, it provided more than 7,000 care providers with learning opportunities. PMID:26854549
Jones, E.; Sicherman, A.
1996-07-01
DOE facilities rely increasingly on computerized systems to manage nuclear materials accountability data and to protect against diversion of nuclear materials or other malevolent acts (e.g., hoax due to falsified data) by insider threats. Aspects of modern computerized material accountability (MA) systems including powerful personal computers and applications on networks, mixed security environments, and more users with increased knowledge, skills and abilities help heighten the concern about insider threats to the integrity of the system. In this paper, we describe a methodology for assessing MA applications to help decision makers identify ways of and compare options for preventing or mitigating possible additional risks from the insider threat. We illustrate insights from applying the methodology to local area network materials accountability systems.
Position of the American Dietetic Association: local support for nutrition integrity in schools.
Pilant, Vivian B
2006-01-01
It is the position of the American Dietetic Association that the schools and the community have a shared responsibility to provide all students with access to high-quality foods and school-based nutrition services as an integral part of the total education program. Educational goals, including the nutrition goals of the National School Lunch Program and the School Breakfast Program, should be supported and extended through school district wellness policies that create overall school environments that promote access to healthful school meals and physical activity and provide learning experiences that enable students to develop lifelong healthful eating habits. The National School Lunch and School Breakfast Programs are an important source of nutrients for school-age children, and especially for those of low-income status. The American Dietetic Association was actively involved in the 2004 reauthorization of these programs, ensuring access through continued funding, promoting nutrition education and physical activity to combat overweight and prevent chronic disease, and promoting local wellness policies. The standards established for school meal programs result in school meals that provide nutrients that meet dietary guidelines, but standards do not apply to foods and beverages served and sold outside of the school meal. Labeled as competitive foods by the US Department of Agriculture, there is a growing concern that standards should be applied to food in the entire school environment. Legislation has mandated that all school districts that participate in the US Department of Agriculture's Child Nutrition Program develop and implement a local wellness policy by the school year 2006-2007. Resources are available to assist in the development of wellness policies, and dietetics professionals can assist schools in developing policies that meet nutrition integrity standards. PMID:16390677
ERIC Educational Resources Information Center
Yang, Tung-Mou
2011-01-01
Information sharing and integration has long been considered an important approach for increasing organizational efficiency and performance. With advancements in information and communication technologies, sharing and integrating information across organizations becomes more attractive and practical to organizations. However, achieving…
“T cells integrate Local and Global cues to discriminate between structurally similar antigens”
Voisinne, Guillaume; Nixon, Briana; Melbinger, Anna; Gasteiger, Georg; Vergassola, Massimo; Altan-Bonnet, Grégoire
2015-01-01
T lymphocytes’ ability to discriminate between structurally related antigens has been attributed to the unique signaling properties of the T cell receptor. However, recent studies have suggested that the output of this discrimination process is conditioned by environmental cues. Here we demonstrate how the IL-2 cytokine, collectively generated by strongly activated T cell clones, can induce weaker T cell clones to proliferate. We identify the PI3K pathway as being critical for integrating the antigen and cytokine responses and for controlling cell cycle entry. We build a hybrid stochastic/deterministic computational model that accounts for such signal-synergism and demonstrates quantitatively how T-cells tune their cell cycle entry according to environmental cytokine cues. Our findings indicate that antigen discrimination by T-cells is not solely an intrinsic cellular property but rather a product of integration of multiple cues, including local cues like antigen quality and quantity, to global ones like the extracellular concentration of inflammatory cytokines. PMID:26004178
NASA Astrophysics Data System (ADS)
Chan, A. A.; Elkington, S. R.; Albert, J.; Zheng, L.
2013-12-01
Although much is known about the dynamics of the radiation belts there are still many unanswered questions on the basic physical processes responsible for the storm-time variations of relativistic electrons. Two physical processes that are thought to be especially important are (i) drift-resonant wave-particle interactions with ULF perturbations, which may lead to radial diffusion, and (ii) cyclotron-resonant wave-particle interactions with VLF/ELF waves, which may lead to local energy and pitch-angle diffusion. While there is theoretical and observational support that both of these processes play important roles in radiation belt dynamics, their relative contributions are still not well understood quantitatively. Also, recent work suggests that magnetopause shadowing may play a larger role than previously expected, and the physical connections between changes in the radiation belts and different solar interplanetary drivers are not well understood. In this presentation I will briefly review published work on radial transport, local acceleration, and loss, and I will also present recent results (particularly for high-speed-stream storms) that emphasize the value of integrating theories and observations of the radiation belts, including comments on theories and observations of related electromagnetic fields and plasma populations in the Earth's inner magnetosphere.
Solutions to Kuessner's integral equation in unsteady flow using local basis functions
NASA Technical Reports Server (NTRS)
Fromme, J. A.; Halstead, D. W.
1975-01-01
The computational procedure and numerical results are presented for a new method to solve Kuessner's integral equation in the case of subsonic compressible flow about harmonically oscillating planar surfaces with controls. Kuessner's equation is a linear transformation from pressure to normalwash. The unknown pressure is expanded in terms of prescribed basis functions and the unknown basis function coefficients are determined in the usual manner by satisfying the given normalwash distribution either collocationally or in the complex least squares sense. The present method of solution differs from previous ones in that the basis functions are defined in a continuous fashion over a relatively small portion of the aerodynamic surface and are zero elsewhere. This method, termed the local basis function method, combines the smoothness and accuracy of distribution methods with the simplicity and versatility of panel methods. Predictions by the local basis function method for unsteady flow are shown to be in excellent agreement with other methods. Also, potential improvements to the present method and extensions to more general classes of solutions are discussed.
Yu, Longhai; Zheng, Jiajiu; Xu, Yang; Dai, Daoxin; He, Sailing
2014-11-25
Graphene is well-known as a two-dimensional sheet of carbon atoms arrayed in a honeycomb structure. It has some unique and fascinating properties, which are useful for realizing many optoelectronic devices and applications, including transistors, photodetectors, solar cells, and modulators. To enhance light-graphene interactions and take advantage of its properties, a promising approach is to combine a graphene sheet with optical waveguides, such as silicon nanophotonic wires considered in this paper. Here we report local and nonlocal optically induced transparency (OIT) effects in graphene-silicon hybrid nanophotonic integrated circuits. A low-power, continuous-wave laser is used as the pump light, and the power required for producing the OIT effect is as low as ∼0.1 mW. The corresponding power density is several orders lower than that needed for the previously reported saturated absorption effect in graphene, which implies a mechanism involving light absorption by the silicon and photocarrier transport through the silicon-graphene junction. The present OIT effect enables low power, all-optical, broadband control and sensing, modulation and switching locally and nonlocally. PMID:25372937
Rapid computation of spectrally integrated non-local thermodynamic equilibrium limb emission
NASA Technical Reports Server (NTRS)
Mlynczak, Martin G.; Olander, Daphne S.; Lopez-Puertas, Manuel
1994-01-01
The interpretation of infrared radiance measurements made by satellite-borne limb-scanning broadband radiometers requires accurate and computationally fast techniques with which to evaluate the equation of radiative transfer. This requirement is made even more stringent when analyzing measurements of non-local thermodynamic equilibrium (non-LTE) emission from the terrestrial mesosphere and lower thermosphere. In principle, line-by-line calculations which explicitly account for the departure from thermodynamic equilibrium in both the source functions and the transmittances are necessary. In this paper we extend the emissivity growth approximation (EGA) technique developed for local thermodynamic equilibrium (LTE) limb radiance for the molecular oxygen dayglow (1.27 micrometers and 762 nm), ozone and carbon dioxide in the 9- to 11-micrometer spectral interval, carbon monoxide (4.6 micrometers), nitric oxide (5.3 micrometers), and the carbon dioxide bands (15 micrometers) are presented. Using the non-LTE form of the EGA, the spectrally integrated limb emission is calculated for 35 tangent heights in the mesosphere and lower thermosphere (a total of 1200 atmospheric layers) with line-by-line accuracy in approximately 0.35 s of CPU time on readily available desktop computer hardware, while the corresponding line-by-line calculations may require several minutes. The non-LTE EGA technique will allow kinetic temperature and minor constituend retrieval algorithms to readily include non-LTE efects limited only by the a priori knowledge of the departure from LTE in the observed bands.
Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System.
Guzmán-Quirós, Raúl; Martínez-Sala, Alejandro; Gómez-Tornero, José Luis; García-Haro, Joan
2015-01-01
In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna. Unlike commonly-employed omnidirectional antennas, directional antennas can receive a stronger signal from the direction in which they are pointed, resulting in a different RSS distributions in space and, hence, more distinguishable fingerprints. A simulation tool and a system management software have been also developed to control the system and assist the initial antenna deployment, reducing time-consuming costs. A prototype was mounted in a real scenario, with a number of SRs with omnidirectional and directional antennas properly positioned. Different antenna configurations have been studied, evidencing a promising capability of directional antennas to enhance the performance of RSS fingerprinting-based ILS, reducing the number of required SRs and also increasing the localization success. PMID:26703620
Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System
Guzmán-Quirós, Raúl; Martínez-Sala, Alejandro; Gómez-Tornero, José Luis; García-Haro, Joan
2015-01-01
In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna. Unlike commonly-employed omnidirectional antennas, directional antennas can receive a stronger signal from the direction in which they are pointed, resulting in a different RSS distributions in space and, hence, more distinguishable fingerprints. A simulation tool and a system management software have been also developed to control the system and assist the initial antenna deployment, reducing time-consuming costs. A prototype was mounted in a real scenario, with a number of SRs with omnidirectional and directional antennas properly positioned. Different antenna configurations have been studied, evidencing a promising capability of directional antennas to enhance the performance of RSS fingerprinting-based ILS, reducing the number of required SRs and also increasing the localization success. PMID:26703620
Integrating a local database into the StarView distributed user interface
NASA Technical Reports Server (NTRS)
Silberberg, D. P.
1992-01-01
A distributed user interface to the Space Telescope Data Archive and Distribution Service (DADS) known as StarView is being developed. The DADS architecture consists of the data archive as well as a relational database catalog describing the archive. StarView is a client/server system in which the user interface is the front-end client to the DADS catalog and archive servers. Users query the DADS catalog from the StarView interface. Query commands are transmitted via a network and evaluated by the database. The results are returned via the network and are displayed on StarView forms. Based on the results, users decide which data sets to retrieve from the DADS archive. Archive requests are packaged by StarView and sent to DADS, which returns the requested data sets to the users. The advantages of distributed client/server user interfaces over traditional one-machine systems are well known. Since users run software on machines separate from the database, the overall client response time is much faster. Also, since the server is free to process only database requests, the database response time is much faster. Disadvantages inherent in this architecture are slow overall database access time due to the network delays, lack of a 'get previous row' command, and that refinements of a previously issued query must be submitted to the database server, even though the domain of values have already been returned by the previous query. This architecture also does not allow users to cross correlate DADS catalog data with other catalogs. Clearly, a distributed user interface would be more powerful if it overcame these disadvantages. A local database is being integrated into StarView to overcome these disadvantages. When a query is made through a StarView form, which is often composed of fields from multiple tables, it is translated to an SQL query and issued to the DADS catalog. At the same time, a local database table is created to contain the resulting rows of the query. The
NASA Astrophysics Data System (ADS)
Hung, Hung-Chih; Liu, Yi-Chung; Chien, Sung-Ying
2015-04-01
1. Background Major portions of areas in Asia are expected to increase exposure and vulnerability to climate change and weather extremes due to rapid urbanization and overdevelopment in hazard-prone areas. To prepare and confront the potential impacts of climate change and related hazard risk, many countries have implemented programs of integrated river basin management. This has led to an impending challenge for the police-makers in many developing countries to build effective mechanism to assess how the vulnerability distributes over river basins, and to understand how the local vulnerability links to climatic (climate-related) hazard damages and risks. However, the related studies have received relatively little attention. This study aims to examine whether geographic localities characterized by high vulnerability experience significantly more damages owing to onset weather extreme events at the river basin level, and to explain what vulnerability factors influence these damages or losses. 2. Methods and data An indicator-based assessment framework is constructed with the goal of identifying composite indicators (including exposure, biophysical, socioeconomic, land-use and adaptive capacity factors) that could serve as proxies for attributes of local vulnerability. This framework is applied by combining geographical information system (GIS) techniques with multicriteria decision analysis (MCDA) to evaluate and map integrated vulnerability to climatic hazards across river basins. Furthermore, to explain the relationship between vulnerability factors and disaster damages, we develop a disaster damage model (DDM) based on existing disaster impact theory. We then synthesize a Zero-Inflated Poisson regression model with a Tobit regression analysis to identify and examine how the disaster impacts and vulnerability factors connect to typhoon disaster damages and losses. To illustrate the proposed methodology, the study collects data on the vulnerability attributes of
Boundary-element shape sensitivity analysis for thermal problems with nonlinear boundary conditions
NASA Technical Reports Server (NTRS)
Kane, James H.; Wang, Hua
1991-01-01
Implicit differentiation of the discretized boundary integral equations governing the conduction of heat in solid objects subjected to nonlinear boundary conditions is shown to generate an accurate and economical approach for the computation of shape sensitivities for this class of problems. This approach involves the employment of analytical derivatives of boundary-element kernel functions with respect to shape design variables. A formulation is presented that can consistently account for both temperature-dependent convection and radiation boundary conditions. Several iterative strategies are presented for the solution of the resulting sets of nonlinear equations and the computational performances examined in detail. Multizone analysis and zone condensation strategies are demonstrated to provide substantive computational economies in this process for models with either localized nonlinear boundary conditions or regions of geometric insensitivity to design variables. A series of nonlinear example problems are presented that have closed-form solutions.
NASA Astrophysics Data System (ADS)
McCaughey, J.; Lubis, A. M.; Huang, Z.; Yao, Y.; Hill, E. M.; Eriksson, S.; Sieh, K.
2012-04-01
The Earth Observatory of Singapore (EOS) is building partnerships with local to provincial government agencies, NGOs, and educators in West Sumatra to inform their policymaking, disaster-risk-reduction, and education efforts. Geodetic and paleoseismic studies show that an earthquake as large as M 8.8 is likely sometime in the coming decades on the Mentawai patch of the Sunda megathrust. This earthquake and its tsunami would be devastating for the Mentawai Islands and neighboring areas of the western Sumatra coast. The low-lying coastal Sumatran city of Padang (pop. ~800,000) has been the object of many research and outreach efforts, especially since 2004. Padang experienced deadly earthquakes in 2007 and 2009 that, though tragedies in their own right, served also as wake-up calls for a larger earthquake to come. However, there remain significant barriers to linking science to policy: extant hazard information is sometimes contradictory or confusing for non-scientists, while turnover of agency leadership and staff means that, in the words of one local advocate, "we keep having to start from zero." Both better hazard knowledge and major infrastructure changes are necessary for risk reduction in Padang. In contrast, the small, isolated villages on the outlying Mentawai Islands have received relatively fewer outreach efforts, yet many villages have the potential for timely evacuation with existing infrastructure. Therefore, knowledge alone can go far toward risk reduction. The tragic October 2010 Mentawai tsunami has inspired further disaster-risk reduction work by local stakeholders. In both locations, we are engaging policymakers and local NGOs, providing science to help inform their work. Through outreach contacts, the Mentawai government requested that we produce the first-ever tsunami hazard map for their islands; this aligns well with scientific interests at EOS. We will work with the Mentawai government on the presentation and explanation of the hazard map, as
Schwadron, N. A.; Moebius, E.; Kucharek, H.; Lee, M. A.; French, J.; Saul, L.; Wurz, P.; Bzowski, M.; Fuselier, S. A.; Livadiotis, G.; McComas, D. J.; Frisch, P.; Gruntman, M.; Mueller, H. R.
2013-10-01
Neutral hydrogen atoms that travel into the heliosphere from the local interstellar medium (LISM) experience strong effects due to charge exchange and radiation pressure from resonant absorption and re-emission of Lyα. The radiation pressure roughly compensates for the solar gravity. As a result, interstellar hydrogen atoms move along trajectories that are quite different than those of heavier interstellar species such as helium and oxygen, which experience relatively weak radiation pressure. Charge exchange leads to the loss of primary neutrals from the LISM and the addition of new secondary neutrals from the heliosheath. IBEX observations show clear effects of radiation pressure in a large longitudinal shift in the peak of interstellar hydrogen compared with that of interstellar helium. Here, we compare results from the Lee et al. interstellar neutral model with IBEX-Lo hydrogen observations to describe the distribution of hydrogen near 1 AU and provide new estimates of the solar radiation pressure. We find over the period analyzed from 2009 to 2011 that radiation pressure divided by the gravitational force (μ) has increased slightly from μ = 0.94 ± 0.04 in 2009 to μ = 1.01 ± 0.05 in 2011. We have also derived the speed, temperature, source longitude, and latitude of the neutral H atoms and find that these parameters are roughly consistent with those of interstellar He, particularly when considering the filtration effects that act on H in the outer heliosheath. Thus, our analysis shows that over the period from 2009 to 2011, we observe signatures of neutral H consistent with the primary distribution of atoms from the LISM and a radiation pressure that increases in the early rise of solar activity.
Local rhombohedral symmetry in Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2} near the morphotropic phase boundary
Ma, Tianyu; Liu, Xiaolian; Pan, Xingwen; Li, Xiang; Jiang, Yinzhu; Yan, Mi; Li, Huiying; Fang, Minxia; Ren, Xiaobing
2014-11-10
The recently reported morphotropic phase boundary (MPB) in a number of giant magnetostrictive materials (GMMs) has drawn considerable interest to the local symmetry/structure near MPB region of these materials. In this letter, by in-situ X-ray diffraction and AC magnetic susceptibility measurements, we show that Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2}, the typical composition of Terfenol-D GMMs, has coexistence of rhombohedral and tetragonal phases over a wide temperature range in the vicinity of MPB. High resolution transmission electron microscopy provides direct evidence for local rhombohedral symmetry of the ferromagnetic phase and reveals regular-shaped nanoscale domains below 10 nm. The nano-sized structural/magnetic domains are hierarchically inside a single micron-sized stripe-like domain with the same average magnetization direction. Such domain structures are consistent with the low magnetocrystalline anisotropy and easy magnetic/structural domain switching under magnetic field, thus generating large magnetostriction at low field.
Localized RhoA GTPase activity regulates dynamics of endothelial monolayer integrity
Szulcek, Robert; Beckers, Cora M.L.; Hodzic, Jasmina; de Wit, Jelle; Chen, Zhenlong; Grob, Tim; Musters, Rene J.P.; Minshall, Richard D.; van Hinsbergh, Victor W.M.; van Nieuw Amerongen, Geerten P.
2013-01-01
Aims Endothelial cells (ECs) control vascular permeability by forming a monolayer that is sealed by extracellular junctions. Various mediators modulate the endothelial barrier by acting on junctional protein complexes and the therewith connected F-actin cytoskeleton. Different Rho GTPases participate in this modulation, but their mechanisms are still partly resolved. Here, we aimed to elucidate whether the opening and closure of the endothelial barrier are associated with distinct localized RhoA activities at the subcellular level. Methods and results Live fluorescence resonance energy transfer (FRET) microscopy revealed spatially distinct RhoA activities associated with different aspects of the regulation of endothelial monolayer integrity. Unstimulated ECs were characterized by hotspots of RhoA activity at their periphery. Thrombin receptor activation in the femoral vein of male wistar rats and in cultured ECs enhanced RhoA activity at membrane protrusions, followed by a more sustained RhoA activity associated with cytoplasmic F-actin filaments, where prolonged RhoA activity coincided with cellular contractility. Unexpectedly, thrombin-induced peripheral RhoA hotspots were not spatially correlated to the formation of large inter-endothelial gaps. Rather, spontaneous RhoA activity at membrane protrusions coincided with the closure of inter-endothelial gaps. Electrical impedance measurements showed that RhoA signalling is essential for this protrusive activity and maintenance of barrier restoration. Conclusion Spontaneous RhoA activity at membrane protrusions is spatially associated with closure, but not formation of inter-endothelial gaps, whereas RhoA activity at distant contractile filaments contributes to thrombin-induced disruption of junctional integrity. Thus, these data indicate that distinct RhoA activities are associated with disruption and re-annealing of endothelial junctions. PMID:23536606
NASA Technical Reports Server (NTRS)
Chatfield, Robert B.; Vastano, John A.; Guild, Liane; Hlavka, Christine; Brass, James A.; Russell, Philip B. (Technical Monitor)
1994-01-01
Burning to clear land for crops and to destroy pests is an integral and largely unavoidable part of tropical agriculture. It is easy to note but difficult to quantify using remote sensing. This report describes our efforts to integrate remotely sensed data into our computer model of tropical chemical trace-gas emissions, weather, and reaction chemistry (using the MM5 mesoscale model and our own Global-Regional Atmospheric Chemistry Simulator). The effects of burning over the continents of Africa and South America have been noticed in observations from several satellites. Smoke plumes hundreds of kilometers long may be seen individually, or may merge into a large smoke pall over thousands of kilometers of these continents. These features are related to intense pollution in the much more confined regions with heavy burning. These emissions also translocate nitrogen thousands of kilometers in the tropical ecosystems, with large fixed-nitrogen losses balanced partially by locally intense fertilization downwind, where nitric acid is rained out. At a much larger scale, various satellite measurements have indicated the escape of carbon monoxide and ozone into large filaments which extend across the Tropical and Southern Atlantic Ocean. Our work relates the source emissions, estimated in part from remote sensing, in part from conventional surface reports, to the concentrations of these gases over these intercontinental regions. We will mention work in progress to use meteorological satellite data (AVHRR, GOES, and Meteosat) to estimate the surface temperature and extent and height of clouds, and explain why these uses are so important in our computer simulations of global biogeochemistry. We will compare our simulations and interpretation of remote observations to the international cooperation involving Brazil, South Africa, and the USA in the TRACE-A (Transport and Atmospheric Chemistry near the Equator - Atlantic) and SAFARI (Southern Africa Fire Atmosphere Research
Integrated Modeling of the Human-Natural System to Improve Local Water Management and Planning
NASA Astrophysics Data System (ADS)
Gutowski, W. J., Jr.; Dziubanski, D.; Franz, K.; Goodwin, J.; Rehmann, C. R.; Simpkins, W. W.; Tesfastion, L.; Wanamaker, A. D.; Jie, Y.
2015-12-01
Communities across the world are experiencing the effects of unsustainable water management practices. Whether the problem is a lack of water, too much water, or water of degraded quality, finding acceptable solutions requires community-level efforts that integrate sound science with local needs and values. Our project develops both a software technology (agent-based hydrological modeling) and a social technology (a participatory approach to model development) that will allow communities to comprehensively address local water challenges. Using agent-based modeling (ABM), we are building a modeling system that includes a semi-distributed hydrologic process model coupled with agent (stakeholder) models. Information from the hydrologic model is conveyed to the agent models, which, along with economic information, determine appropriate agent actions that subsequently affect hydrology within the model. The iterative participatory modeling (IPM) process will assist with the continual development of the agent models. Further, IPM creates a learning environment in which all participants, including researchers, are co-exploring relevant data, possible scenarios and solutions, and viewpoints through continuous interactions. Our initial work focuses on the impact of flood mitigation and conservation efforts on reducing flooding in an urban area. We are applying all research elements above to the Squaw Creek watershed that flows through parts of four counties in central Iowa. The watershed offers many of the typical tensions encountered in Iowa, such as different perspectives on water management between upstream farmers and downstream urban areas, competition for various types of recreational services, and increasing absentee land ownership that may conflict with community values. Ultimately, climate change scenarios will be incorporated into the model to determine long term patterns that may develop within the social or natural system.
Yates, Julian S; Gutberlet, Jutta
2011-01-01
Drawing on a participatory study of integrated organic waste management, this article explores the local political barriers and preconditions for its implementation in Diadema, Brazil. Solid waste management in Brazil is embedded in and mediated by a political framework that is characterised by uneven power geometries. This article explores how the local political context affects the potential for integrated organic waste management in Diadema, paying particular attention to relations between stakeholders. The discussion addresses the contested nature of deliberative decision-making spaces and the need for pro-active socio-environmental policies. The findings underline the importance of a praxis of everyday public participation that goes beyond rhetoric. PMID:21910280
Wireless boundary monitor system and method
Haynes, Howard D.; Ayers, Curtis W.
1997-01-01
A wireless boundary monitor system used to monitor the integrity of a boundary surrounding an area uses at least two housings having at least one transmitting means for emitting ultrasonic pressure waves to a medium. Each of the housings has a plurality of receiving means for sensing the pressure waves in the medium. The transmitting means and the receiving means of each housing are aimable and communicably linked. At least one of the housings is equipped with a local alarm means for emitting a first alarm indication whereby, when the pressure waves propagating from a transmitting means to a receiving means are sufficiently blocked by an object a local alarm means or a remote alarm means or a combination thereof emit respective alarm indications. The system may be reset either manually or automatically. This wireless boundary monitor system has useful applications in both indoor and outdoor environments.
Wireless boundary monitor system and method
Haynes, H.D.; Ayers, C.W.
1997-12-09
A wireless boundary monitor system used to monitor the integrity of a boundary surrounding an area uses at least two housings having at least one transmitting means for emitting ultrasonic pressure waves to a medium. Each of the housings has a plurality of receiving means for sensing the pressure waves in the medium. The transmitting means and the receiving means of each housing are aimable and communicably linked. At least one of the housings is equipped with a local alarm means for emitting a first alarm indication whereby, when the pressure waves propagating from a transmitting means to a receiving means are sufficiently blocked by an object a local alarm means or a remote alarm means or a combination thereof emit respective alarm indications. The system may be reset either manually or automatically. This wireless boundary monitor system has useful applications in both indoor and outdoor environments. 4 figs.
Integrated soil fertility management in sub-Saharan Africa: unravelling local adaptation
NASA Astrophysics Data System (ADS)
Vanlauwe, B.; Descheemaeker, K.; Giller, K. E.; Huising, J.; Merckx, R.; Nziguheba, G.; Wendt, J.; Zingore, S.
2015-06-01
Intensification of smallholder agriculture in sub-Saharan Africa is necessary to address rural poverty and natural resource degradation. Integrated soil fertility management (ISFM) is a means to enhance crop productivity while maximizing the agronomic efficiency (AE) of applied inputs, and can thus contribute to sustainable intensification. ISFM consists of a set of best practices, preferably used in combination, including the use of appropriate germplasm, the appropriate use of fertilizer and of organic resources, and good agronomic practices. The large variability in soil fertility conditions within smallholder farms is also recognized within ISFM, including soils with constraints beyond those addressed by fertilizer and organic inputs. The variable biophysical environments that characterize smallholder farming systems have profound effects on crop productivity and AE, and targeted application of agro-inputs and management practices is necessary to enhance AE. Further, management decisions depend on the farmer's resource endowments and production objectives. In this paper we discuss the "local adaptation" component of ISFM and how this can be conceptualized within an ISFM framework, backstopped by analysis of AE at plot and farm level. At plot level, a set of four constraints to maximum AE is discussed in relation to "local adaptation": soil acidity, secondary nutrient and micronutrient (SMN) deficiencies, physical constraints, and drought stress. In each of these cases, examples are presented whereby amendments and/or practices addressing these have a significantly positive impact on fertilizer AE, including mechanistic principles underlying these effects. While the impact of such amendments and/or practices is easily understood for some practices (e.g. the application of SMNs where these are limiting), for others, more complex processes influence AE (e.g. water harvesting under varying rainfall conditions). At farm scale, adjusting fertilizer applications to
Integrated soil fertility management in sub-Saharan Africa: unravelling local adaptation
NASA Astrophysics Data System (ADS)
Vanlauwe, B.; Descheemaeker, K.; Giller, K. E.; Huising, J.; Merckx, R.; Nziguheba, G.; Wendt, J.; Zingore, S.
2014-12-01
Intensification of smallholder agriculture in sub-Saharan Africa is necessary to address rural poverty and natural resource degradation. Integrated Soil Fertility Management (ISFM) is a means to enhance crop productivity while maximizing the agronomic efficiency (AE) of applied inputs, and can thus contribute to sustainable intensification. ISFM consists of a set of best practices, preferably used in combination, including the use of appropriate germplasm, the appropriate use of fertilizer and of organic resources, and good agronomic practices. The large variability in soil fertility conditions within smallholder farms is also recognised within ISFM, including soils with constraints beyond those addressed by fertilizer and organic inputs. The variable biophysical environments that characterize smallholder farming systems have profound effects on crop productivity and AE and targeted application of limited agro-inputs and management practices is necessary to enhance AE. Further, management decisions depend on the farmer's resource endowments and production objectives. In this paper we discuss the "local adaptation" component of ISFM and how this can be conceptualized within an ISFM framework, backstopped by analysis of AE at plot and farm level. At plot level, a set of four constraints to maximum AE is discussed in relation to "local adaptation": soil acidity, secondary nutrient and micro-nutrient (SMN) deficiencies, physical constraints, and drought stress. In each of these cases, examples are presented whereby amendments and/or practices addressing these have a significantly positive impact on fertilizer AE, including mechanistic principles underlying these effects. While the impact of such amendments and/or practices is easily understood for some practices (e.g., the application of SMNs where these are limiting), for others, more complex interactions with fertilizer AE can be identified (e.g., water harvesting under varying rainfall conditions). At farm scale
Local Data Integration in East Central Florida Using the ARPS Data Analysis System
NASA Technical Reports Server (NTRS)
Case, Jonathan; Manobianco, John
1998-01-01
This paper describes the Applied Meteorology Unit's (AMU) efforts to configure, implement, and test a version of the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS; Brewster 1996) that assimilates all available data within 250 km of the Kennedy Space Center (KSC) and the Eastern Range at Cape Canaveral Air Station (CCAS). The objective for running a Local Data Integration System (LDIS) such as ADAS is to generate products which may enhance weather nowcasts and short-range (less than 6 h) forecasts issued in support of ground and aerospace operations at KSC/CCAS. A LDIS such as ADAS has the potential to provide added value because it combines observational data to produce gridded analyses of temperature, wind, and moisture (including clouds) and diagnostic quantities such as vorticity, divergence, etc. at specified temporal and spatial resolutions. In this regard, a LDTS along with suitable visualization tools may provide users with a ignore complete and comprehensive understanding of evolving weather than could be developed by individually examining the disparate data sets over the same area and time. The AMU implemented a working prototype of the ADAS which does not run in real-time. Instead, the AMU is evaluating ADAS through post-analyses of weather events for a warm and cool season case. The case studies were chosen to investigate the capabilities and limitations of a LDIS such as ADAS including the impact of non-incorporation of specific data sources on the utility of the subsequent analyses.
Vydyanathan, Naga; Krishnamoorthy, Sriram; Sabin, Gerald M.; Catalyurek, Umit V.; Kurc, Tahsin; Sadayappan, Ponnuswamy; Saltz, Joel H.
2009-08-01
Complex parallel applications can often be modeled as directed acyclic graphs of coarse-grained application-tasks with dependences. These applications exhibit both task- and data-parallelism, and combining these two (also called mixedparallelism), has been shown to be an effective model for their execution. In this paper, we present an algorithm to compute the appropriate mix of task- and data-parallelism required to minimize the parallel completion time (makespan) of these applications. In other words, our algorithm determines the set of tasks that should be run concurrently and the number of processors to be allocated to each task. The processor allocation and scheduling decisions are made in an integrated manner and are based on several factors such as the structure of the taskgraph, the runtime estimates and scalability characteristics of the tasks and the inter-task data communication volumes. A locality conscious scheduling strategy is used to improve inter-task data reuse. Evaluation through simulations and actual executions of task graphs derived from real applications as well as synthetic graphs shows that our algorithm consistently generates schedules with lower makespan as compared to CPR and CPA, two previously proposed scheduling algorithms. Our algorithm also produces schedules that have lower makespan than pure taskand data-parallel schedules. For task graphs with known optimal schedules or lower bounds on the makespan, our algorithm generates schedules that are closer to the optima than other scheduling approaches.
Han, Taeman; Kim, Jin Ill; Yi, Dae-Am; Jeong, Jongchel; An, Seung Lak; Park, In Gyun; Park, Haechul
2016-01-01
The ball-rolling dung beetles of the genus Scarabaeus are very ecologically important for the recycling of feces of large herbivores and the related nature management. There has been a significant decline, however, in the numbers of many species at the population and individual levels. S. typhon is currently thought to be the sole member of Scarabaeus distributed in Korea; however, that species underwent serious local extinctions in the 1970s. Before planning a full-scale species recovery, it is important to have an understanding of the exact species diversity and genetic structures of the focal species. We therefore attempted an integrative taxonomy focused on the Korean population of S. typhon and also on S. pius and S. sacer, which were once thought to be distributed in Korea, using both morphological and molecular approaches. The results of both approaches reveal the Korean species of Scarabaeus to be S. typhon and S. pius. In particular, our molecular results inferred from cytochrome c oxidase subunit I genetic analysis show that S. typhon should be considered a single species despite having various haplotypes throughout its wide geographical range from Europe to Korea. We identified two distinct lineages of S. pius (groups A and B) across a wide distributional range. We conclude that the Korean specimens of S. pius belong to group A and that S. pius is new to Korea under the current taxonomic treatment. PMID:27470822
Simulation of a Real-Time Local Data Integration System over East-Central Florida
NASA Technical Reports Server (NTRS)
Case, Jonathan
1999-01-01
The Applied Meteorology Unit (AMU) simulated a real-time configuration of a Local Data Integration System (LDIS) using data from 15-28 February 1999. The objectives were to assess the utility of a simulated real-time LDIS, evaluate and extrapolate system performance to identify the hardware necessary to run a real-time LDIS, and determine the sensitivities of LDIS. The ultimate goal for running LDIS is to generate analysis products that enhance short-range (less than 6 h) weather forecasts issued in support of the 45th Weather Squadron, Spaceflight Meteorology Group, and Melbourne National Weather Service operational requirements. The simulation used the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS) software on an IBM RS/6000 workstation with a 67-MHz processor. This configuration ran in real-time, but not sufficiently fast for operational requirements. Thus, the AMU recommends a workstation with a 200-MHz processor and 512 megabytes of memory to run the AMU's configuration of LDIS in real-time. This report presents results from two case studies and several data sensitivity experiments. ADAS demonstrates utility through its ability to depict high-resolution cloud and wind features in a variety of weather situations. The sensitivity experiments illustrate the influence of disparate data on the resulting ADAS analyses.
Harunuzzaman, M.; Islam, M.
1994-08-01
According to the report, public utility commissions (PUCs) are increasingly adopting, or considering the adoption of integrated resource planning (IRP) for local gas distribution companies (LDCs). The Energy Policy Act of 1992 (EPAct) requires PUCs to consider IRP for gas LDCs. This study has two major objectives: (1) to help PUCs develop appropriate regulatory approaches with regard to IRP for gas LDCs; and (2) to help PUCs respond to the EPAct directive. The study finds that it is appropriate for PUCs to pursue energy efficiency within the traditional regulatory framework of minimizing private costs of energy production and delivery; and PUCs should play a limited role in addressing environmental externalities. The study also finds that in promoting energy efficiency, PUCs should pursue policies that are incentive-based, procompetitive, and sensitive to rate impacts. The study evaluates a number of traditional and nontraditional ratemaking mechanisms on the basis of cost minimization, energy efficiency, competitiveness, and other criteria. The mechanisms evaluated include direct recovery of DSM expenses, lost revenue adjustments for DSM options, revenue decoupling mechanisms, sharing of DSM cost savings, performance-based rate of return for DSM, provision of DSM as a separate service, deregulation of DSM service, price caps, and deregulation of the noncore gas market. The study concludes with general recommendations for regulatory approaches and ratemaking mechanisms that PUCs may wish to consider in advancing IRP objectives.
NASA Astrophysics Data System (ADS)
Nair, Vijayakumar S.; Moorthy, K. Krishna; Alappattu, Denny P.; Kunhikrishnan, P. K.; George, Susan; Nair, Prabha R.; Babu, S. Suresh; Abish, B.; Satheesh, S. K.; Tripathi, Sachchida Nand; Niranjan, K.; Madhavan, B. L.; Srikant, V.; Dutt, C. B. S.; Badarinath, K. V. S.; Reddy, R. Ramakrishna
2007-07-01
The Indo-Gangetic Plain (IGP) encompasses a vast area, (accounting for ˜21% of the land area of India), which is densely populated (accommodating ˜40% of the Indian population). Highly growing economy and population over this region results in a wide range of anthropogenic activities. A large number of thermal power plants (most of them coal fed) are clustered along this region. Despite its importance, detailed investigation of aerosols over this region is sparse. During an intense field campaign of winter 2004, extensive aerosol and atmospheric boundary layer measurements were made from three locations: Kharagpur (KGP), Allahabad (ALB), and Kanpur (KNP), within the IGP. These data are used (1) to understand the regional features of aerosols and BC over the IGP and their interdependencies, (2) to compare it with features at locations lying at far away from the IGP where the conditions are totally different, (3) to delineate the effects of mesoscale processes associated with changes in the local atmospheric boundary layer (ABL), (4) to investigate the effects of long-range transport or moving weather phenomena in modulating the aerosol properties as well as the ABL characteristics, and (5) to examine the changes as the season changes over to spring and summer. Our investigations have revealed very high concentrations of aerosols along the IGP, the average mass concentrations (MT) of total aerosols being in the range 260 to 300 μg m-3 and BC mass concentrations (MB) in the range 20 to 30 μg m-3 (both ˜5 to 8 times higher than the values observed at off-IGP stations) during December 2004. Despite, BC constituted about 10% to the total aerosol mass concentration, a value quite comparable to those observed elsewhere over India for this season. The dynamics of the local atmospheric boundary layer (ABL) as well as changes in local emissions strongly influence the diurnal variations of MT and MB, both being inversely correlated with the mixed layer height (Zi) and the
Wootton, Jeffery H.; Hsu, I-Chow Joe; Diederich, Chris J.
2011-02-15
Purpose: The clinical success of hyperthermia adjunct to radiotherapy depends on adequate temperature elevation in the tumor with minimal temperature rise in organs at risk. Existing technologies for thermal treatment of the cervix have limited spatial control or rapid energy falloff. The objective of this work is to develop an endocervical applicator using a linear array of multisectored tubular ultrasound transducers to provide 3-D conformal, locally targeted hyperthermia concomitant to radiotherapy in the uterine cervix. The catheter-based device is integrated within a HDR brachytherapy applicator to facilitate sequential and potentially simultaneous heat and radiation delivery. Methods: Treatment planning images from 35 patients who underwent HDR brachytherapy for locally advanced cervical cancer were inspected to assess the dimensions of radiation clinical target volumes (CTVs) and gross tumor volumes (GTVs) surrounding the cervix and the proximity of organs at risk. Biothermal simulation was used to identify applicator and catheter material parameters to adequately heat the cervix with minimal thermal dose accumulation in nontargeted structures. A family of ultrasound applicators was fabricated with two to three tubular transducers operating at 6.6-7.4 MHz that are unsectored (360 deg.), bisectored (2x180 deg.), or trisectored (3x120 deg.) for control of energy deposition in angle and along the device length in order to satisfy anatomical constraints. The device is housed in a 6 mm diameter PET catheter with cooling water flow for endocervical implantation. Devices were characterized by measuring acoustic efficiencies, rotational acoustic intensity distributions, and rotational temperature distributions in phantom. Results: The CTV in HDR brachytherapy plans extends 20.5{+-}5.0 mm from the endocervical tandem with the rectum and bladder typically <8 mm from the target boundary. The GTV extends 19.4{+-}7.3 mm from the tandem. Simulations indicate that for 60
Wootton, Jeffery H.; Hsu, I-Chow Joe; Diederich, Chris J.
2011-01-01
Purpose: The clinical success of hyperthermia adjunct to radiotherapy depends on adequate temperature elevation in the tumor with minimal temperature rise in organs at risk. Existing technologies for thermal treatment of the cervix have limited spatial control or rapid energy falloff. The objective of this work is to develop an endocervical applicator using a linear array of multisectored tubular ultrasound transducers to provide 3-D conformal, locally targeted hyperthermia concomitant to radiotherapy in the uterine cervix. The catheter-based device is integrated within a HDR brachytherapy applicator to facilitate sequential and potentially simultaneous heat and radiation delivery. Methods: Treatment planning images from 35 patients who underwent HDR brachytherapy for locally advanced cervical cancer were inspected to assess the dimensions of radiation clinical target volumes (CTVs) and gross tumor volumes (GTVs) surrounding the cervix and the proximity of organs at risk. Biothermal simulation was used to identify applicator and catheter material parameters to adequately heat the cervix with minimal thermal dose accumulation in nontargeted structures. A family of ultrasound applicators was fabricated with two to three tubular transducers operating at 6.6–7.4 MHz that are unsectored (360°), bisectored (2×180°), or trisectored (3×120°) for control of energy deposition in angle and along the device length in order to satisfy anatomical constraints. The device is housed in a 6 mm diameter PET catheter with cooling water flow for endocervical implantation. Devices were characterized by measuring acoustic efficiencies, rotational acoustic intensity distributions, and rotational temperature distributions in phantom. Results: The CTV in HDR brachytherapy plans extends 20.5±5.0 mm from the endocervical tandem with the rectum and bladder typically <8 mm from the target boundary. The GTV extends 19.4±7.3 mm from the tandem. Simulations indicate that for 60 min
Wang, Zhisong; Maier, Alexander; Logothetis, Nikos K; Liang, Hualou
2009-08-01
Bistable perception arises when an ambiguous stimulus under continuous view is perceived as an alternation of two mutually exclusive states. Such a stimulus provides a unique opportunity for understanding the neural basis of visual perception because it dissociates the perception from the visual input. In this paper, we focus on extracting the percept-related features from the local field potential (LFP) in monkey visual cortex for decoding its bistable structure-from-motion (SFM) perception. Our proposed feature extraction approach consists of two stages. First, we estimate and remove from each LFP trial the nonpercept-related stimulus-evoked activity via a local regression method called the locally weighted scatterplot smoothing because of the dissociation between the perception and the stimulus in our experimental paradigm. Second, we use the common spatial patterns approach to design spatial filters based on the residue signals of multiple channels to extract the percept-related features. We exploit a support vector machine (SVM) classifier on the extracted features to decode the reported perception on a single-trial basis. We apply the proposed approach to the multichannel intracortical LFP data collected from the middle temporal (MT) visual cortex in a macaque monkey performing an SFM task. We demonstrate that our approach is effective in extracting the discriminative features of the percept-related activity from LFP and achieves excellent decoding performance. We also find that the enhanced gamma band synchronization and reduced alpha and beta band desynchronization may be the underpinnings of the percept-related activity. PMID:19362902
NASA Technical Reports Server (NTRS)
Sidi, Avram; Pennline, James A.
1999-01-01
In this paper we are concerned with high-accuracy quadrature method solutions of nonlinear Fredholm integral equations of the form y(x) = r(x) + definite integral of g(x, t)F(t,y(t))dt with limits between 0 and 1,0 less than or equal to x les than or equal to 1, where the kernel function g(x,t) is continuous, but its partial derivatives have finite jump discontinuities across x = t. Such integral equations arise, e.g., when one applied Green's function techniques to nonlinear two-point boundary value problems of the form y "(x) =f(x,y(x)), 0 less than or equal to x less than or equal to 1, with y(0) = y(sub 0) and y(l) = y(sub l), or other linear boundary conditions. A quadrature method that is especially suitable and that has been employed for such equations is one based on the trepezoidal rule that has a low accuracy. By analyzing the corresponding Euler-Maclaurin expansion, we derive suitable correction terms that we add to the trapezoidal rule, thus obtaining new numerical quadrature formulas of arbitrarily high accuracy that we also use in defining quadrature methods for the integral equations above. We prove an existence and uniqueness theorem for the quadrature method solutions, and show that their accuracy is the same as that of the underlying quadrature formula. The solution of the nonlinear systems resulting from the quadrature methods is achieved through successive approximations whose convergence is also proved. The results are demonstrated with numerical examples.
NASA Technical Reports Server (NTRS)
Sidi, Avram; Pennline, James A.
1999-01-01
In this paper we are concerned with high-accuracy quadrature method solutions of nonlinear Fredholm integral equations of the form y(x) = r(x) + integral(0 to 1) g(x,t) F(t, y(t)) dt, 0 less than or equal to x less than or equal to 1, where the kernel function g(x,t) is continuous, but its partial derivatives have finite jump discontinuities across x = t. Such integrals equations arise, e.g., when one applies Green's function techniques to nonlinear two-point boundary value problems of the form U''(x) = f(x,y(x)), 0 less than or equal to x less than or equal to 1, with y(0) = y(sub 0) and g(l) = y(sub 1), or other linear boundary conditions. A quadrature method that is especially suitable and that has been employed for such equations is one based on the trapezoidal rule that has a low accuracy. By analyzing the corresponding Euler-Maclaurin expansion, we derive suitable correction terms that we add to the trapezoidal thus obtaining new numerical quadrature formulas of arbitrarily high accuracy that we also use in defining quadrature methods for the integral equations above. We prove an existence and uniqueness theorem for the quadrature method solutions, and show that their accuracy is the same as that of the underlying quadrature formula. The solution of the nonlinear systems resulting from the quadrature methods is achieved through successive approximations whose convergence is also proved. The results are demonstrated with numerical examples.
Boundary-Layer Code For Supersonic Combustion
NASA Technical Reports Server (NTRS)
Pinckney, S. Z.; Walton, J. T.
1994-01-01
HUD is integral computer code based on Spaulding-Chi method for predicting development of boundary layers in laminar, transitional, and turbulent regions of flows on two-dimensional or axisymmetric bodies. Approximates nonequilibrium velocity profiles as well as local surface friction in presence of pressure gradient. Predicts transfer of heat in turbulent boundary layer in presence of high axial presure gradient. Provides for pressure gradients both normal and lateral to surfaces. Also used to estimate requirements for cooling scramjet engines. Because of this capability, HUD program incorporated into several scramjet-cycle-performance-analysis codes, including SCRAM (ARC-12338) and SRGULL (LEW-15093). Written in FORTRAN 77.
Dr. Louis Nadelson; Anne Louise Seifert; Meagan McKinney
2014-06-01
Business, industry, parks, nature settings, government infrastructure, and people, can be invaluable resources for connecting STEM curriculum within context which results in conditions ideal for promoting purposeful learning of authentic STEM content. Thus, community-based STEM resources offer ideal context for teaching STEM content. A benefit of focusing teacher attention on these contextual, content aligned resources is that they are in every community; making place-based STEM education a possibility, regardless of the location of STEM teaching and learning. Further, associating STEM teaching and learning with local resources addresses workforce development and the STEM pipeline by exposing students to STEM careers and applications in their local communities. The desire to align STEM teaching and learning with local STEM related resources guided the design of our week-long integrated STEM K-12 teacher professional development (PD) program, i-STEM. We have completed four years of our i-STEM PD program and have made place-based STEM a major emphasis of our curriculum. This report focuses on the data collected in the fourth year of our program. Our week-long i-STEM PD served over 425 educators last summer (2013), providing them with in depth theme-based integrated STEM short courses which were limited to an average of 15 participants and whole group plenary sessions focused around placed based integrated STEM, inquiry, engineering design, standards and practices of Common Core and 21st Century skills. This state wide PD was distributed in five Idaho community colleges and took place over two weeks. The STEM short courses included topics on engineering for sustainability, using engineering to spark interest in STEM, municipal water systems, health, agriculture, food safety, mining, forestry, energy, and others. Integral to these short courses were field trips designed to connect the K-12 educators to the resources in their local communities that could be leveraged
NASA Astrophysics Data System (ADS)
Park, J.; Chi, H. C.; Lim, I.; Jeong, B.
2011-12-01
The Korea Integrated Seismic System(KISS) is a back-bone seismic network which distributes seismic data to different organizations in near-real time at Korea. The association of earthquake monitoring institutes has shared their seismic data through the KISS from 2003. Local data centers operating remote several stations need to send their free field seismic data to NEMA(National Emergency Management Agency) by the law of countermeasure against earthquake hazard in Korea. It is very important the efficient tool for local data centers which want to rapidly detect local seismic intensity and to transfer seismic event information toward national wide data center including PGA, PGV, dominant frequency of P-wave, raw data, and etc. We developed the KISStool(Korea Integrated Seismic System tool) for easy and convenient operation seismic network in local data center. The KISStool has the function of monitoring real time waveforms by clicking station icon on the Google map and real time variation of PGA, PGV, and other data by opening the bar type monitoring section. If they use the KISStool, any local data center can transfer event information to NEMA(National Emergency Management Agency), KMA(Korea Meteorological Agency) or other institutes through the KISS using UDP or TCP/IP protocols. The KISStool is one of the most efficient methods to monitor and transfer earthquake event at local data center in Korea. KIGAM will support this KISStool not only to the member of the monitoring association but also local governments.
NASA Technical Reports Server (NTRS)
Kuhn, G. D.
1971-01-01
A computer program was developed to do the calculations for two-dimensional or axisymmetric configurations from low speeds to hypersonic speeds with arbitrary streamwise pressure, temperature, and Mach number distributions. Options are provided for obtaining initial conditions either from experimental information or from a theoretical similarity solution. The transition region can be described either by an arbitrary distribution of intermittency or by a function based on Emmons' probability theory. Correlations were developed for use in estimating the parameters of the theoretical intermittency function. Correlations obtained from other sources are used for estimating the transition point. Comparisons were made between calculated and measured boundary layer quantities for laminar, transitional, and turbulent flows on flat plates, cones, cone flares, and a waisted body of revolution. Excellent agreement was obtained between the present theory and two other theories based on the method of finite differences. The intermittency required to reproduce some experimental heat transfer results in hypersonic flow was found to be quite different from the theoretical function. It is suggested that the simple probability theory of Emmons may not be valid for representing the intermittency of hypersonic transitional boundary layers and that the program could be useful as a tool for detailed study of the intermittency of the transition region.
Smits, Kathleen; Eagen, Victoria; Trautz, Andrew
2015-01-01
Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study evaporation under various surface boundary conditions to improve our current understanding and characterization of this multiphase phenomenon as well as to validate numerical heat and mass transfer theories that couple Navier-Stokes flow in the atmosphere and Darcian flow in the porous media. Experimental data were collected using a unique soil tank apparatus interfaced with a small climate controlled wind tunnel. The experimental apparatus was instrumented with a suite of state of the art sensor technologies for the continuous and autonomous collection of soil moisture, soil thermal properties, soil and air temperature, relative humidity, and wind speed. This experimental apparatus can be used to generate data under well controlled boundary conditions, allowing for better control and gathering of accurate data at scales of interest not feasible in the field. Induced airflow at several distinct wind speeds over the soil surface resulted in unique behavior of heat and mass transfer during the different evaporative stages. PMID:26131928
Tomsick, John A.; Bodaghee, Arash; Chaty, Sylvain; Rodriguez, Jerome; Halpern, Jules; Kalemci, Emrah; Oezbey Arabaci, Mehtap
2012-08-01
We report on Chandra observations of 18 hard X-ray (>20 keV) sources discovered with the INTEGRAL satellite near the Galactic plane. For 14 of the INTEGRAL sources, we have uncovered one or two potential Chandra counterparts per source. These provide soft X-ray (0.3-10 keV) spectra and subarcsecond localizations, which we use to identify counterparts at other wavelengths, providing information about the nature of each source. Despite the fact that all of the sources are within 5 Degree-Sign of the plane, four of the IGR sources are active galactic nuclei (AGNs; IGR J01545+6437, IGR J15391-5307, IGR J15415-5029, and IGR J21565+5948) and four others are likely AGNs (IGR J03103+5706, IGR J09189-4418, IGR J16413-4046, and IGR J16560-4958) based on each of them having a strong IR excess and/or extended optical or near-IR emission. We compare the X-ray and near-IR fluxes of this group of sources to those of AGNs selected by their 2-10 keV emission in previous studies and find that these IGR AGNs are in the range of typical values. There is evidence in favor of four of the sources being Galactic (IGR J12489-6243, IGR J15293-5609, IGR J16173-5023, and IGR J16206-5253), but only IGR J15293-5609 is confirmed as a Galactic source as it has a unique Chandra counterpart and a parallax measurement from previous optical observations that puts its distance at 1.56 {+-} 0.12 kpc. The 0.3-10 keV luminosity for this source is (1.4{sup +1.0}{sub -0.4}) Multiplication-Sign 10{sup 32} erg s{sup -1}, and its optical/IR spectral energy distribution is well described by a blackbody with a temperature of 4200-7000 K and a radius of 12.0-16.4 R{sub Sun }. These values suggest that IGR J15293-5609 is a symbiotic binary with an early K-type giant and a white dwarf accretor. We also obtained likely Chandra identifications for IGR J13402-6428 and IGR J15368-5102, but follow-up observations are required to constrain their source types.
Gloudemans, J.R. . Nuclear Power Div.)
1989-07-01
The multiloop integral system test (MIST) is part of a multiphase program started in 1983 to address small-break loss-of-coolant accidents (SBLOCAs) specific to Babcock and Wilcox-designed plants. MIST is sponsored by the US Nuclear Regulatory Commission, the Babcock and Wilcox Owners Group, the Electric Power Research Institute, and Babcock and Wilcox. The unique features of the Babcock and Wilcox design, specifically the hot leg U-bends and steam generators, prevented the use of existing integral system data or existing integral system facilities to address the thermal-hydraulic SBLOCA questions. MIST and two other supporting facilities were specifically designed and constructed for this program, and an existing facility --- the once-through integral system (OTIS) --- was also used. Data from MIST and the other facilities will be used to benchmark the adequacy of system codes, such as RELAP-5 and TRAC, for predicting abnormal plant transients. The MIST program is reported in 11 volumes. The program is summarized in Volume 1; Volumes 2 through 8 describe groups of tests by test type; Volume 9 presents inter-group comparisons; Volume 10 provides comparisons between the calculations of RELAP5 MOD2 and MIST observations, and Volume 11 presents the later, Phase 4 tests. This is Volume 3 pertaining to Test Group 31, Boundary Conditions Variations. The specifications, conduct, observations, and results of these tests are described. 8 refs., 328 figs., 15 tabs.
Guerrero, Mariana; Li, X. Allen . E-mail: ali@radonc.mcw.edu; Ma Lijun; Linder, Jeanette; Deyoung, Chad; Erickson, Beth
2005-07-01
Purpose: Whole-pelvis irradiation (WPI) followed by a boost to the tumor site is the standard of practice for the radiotherapeutic management of locally advanced gynecologic cancers. The boost is frequently administered by use of brachytherapy or, occasionally, external-beam radiotherapy (EBRT) when brachytherapy does not provide sufficient coverage because of the size of the tumor or the geometry of the patient. In this work, we propose using an intensity-modulated radiotherapy (IMRT) simultaneous integrated boost (SIB), which is a single-phase process, to replace the conventional two-phase process involving WPI plus a boost. Radiobiological modeling is used to design appropriate regimens for the IMRT SIB. To demonstrate feasibility, a dosimetric study is carried out on an example patient. Methods and Materials: The standard linear-quadratic (LQ) model is used to calculate the biologically effective dose (BED) and equivalent uniform dose (EUD). A series of regimens that are biologically equivalent to those conventional two-phase treatments is calculated for the proposed SIB. A commercial inverse planning system (Corvus) was used to generate IMRT SIB plans for a sample patient case that used the newly designed fractionations. The dose-volume histogram (DVH) and EUD of both the target and normal structures for conventional treatments and the SIB are compared. A sparing factor was introduced to characterize the sparing of normal structures. Results: Fractionation regimes that are equivalent to the conventional treatments and are suitable for the IMRT SIB are deduced. For example, a SIB plan with 25 x 3.1 Gy (77.5 Gy) to a tumor is equivalent to a conventional treatment of EBRT of 45 Gy to the whole pelvis in 25 fractions plus a high-dose rate (HDR) brachytherapy boost with 30 Gy in 5 fractions. The normal tissue BED is found to be lower for the SIB plan than for the whole-pelvis plus HDR scheme when a sparing factor for the critical structures is considered. This
NASA Astrophysics Data System (ADS)
Mustafaev, R. A.
2008-02-01
Dorodnicyn's generalized method of integral relations is used to compute a Verigin-type single-phase unsteady flow in a porous medium. This problem describes the pumping of a gas through a gallery in a bounded horizontal aquifer and is associated with underground gas storage in aquifers. The case of an isothermal process and an ideal gas are considered. The viscosity of the gas is neglected. Sines are used as smoothing functions. The results obtained in the first and third approximations are presented and analyzed. The solution is compared with a finite-difference solution and that produced by the method of integral relations. The results are given in a table.
Computing the Local Field Potential (LFP) from Integrate-and-Fire Network Models.
Mazzoni, Alberto; Lindén, Henrik; Cuntz, Hermann; Lansner, Anders; Panzeri, Stefano; Einevoll, Gaute T
2015-12-01
Leaky integrate-and-fire (LIF) network models are commonly used to study how the spiking dynamics of neural networks changes with stimuli, tasks or dynamic network states. However, neurophysiological studies in vivo often rather measure the mass activity of neuronal microcircuits with the local field potential (LFP). Given that LFPs are generated by spatially separated currents across the neuronal membrane, they cannot be computed directly from quantities defined in models of point-like LIF neurons. Here, we explore the best approximation for predicting the LFP based on standard output from point-neuron LIF networks. To search for this best "LFP proxy", we compared LFP predictions from candidate proxies based on LIF network output (e.g, firing rates, membrane potentials, synaptic currents) with "ground-truth" LFP obtained when the LIF network synaptic input currents were injected into an analogous three-dimensional (3D) network model of multi-compartmental neurons with realistic morphology, spatial distributions of somata and synapses. We found that a specific fixed linear combination of the LIF synaptic currents provided an accurate LFP proxy, accounting for most of the variance of the LFP time course observed in the 3D network for all recording locations. This proxy performed well over a broad set of conditions, including substantial variations of the neuronal morphologies. Our results provide a simple formula for estimating the time course of the LFP from LIF network simulations in cases where a single pyramidal population dominates the LFP generation, and thereby facilitate quantitative comparison between computational models and experimental LFP recordings in vivo. PMID:26657024
Computing the Local Field Potential (LFP) from Integrate-and-Fire Network Models
Cuntz, Hermann; Lansner, Anders; Panzeri, Stefano; Einevoll, Gaute T.
2015-01-01
Leaky integrate-and-fire (LIF) network models are commonly used to study how the spiking dynamics of neural networks changes with stimuli, tasks or dynamic network states. However, neurophysiological studies in vivo often rather measure the mass activity of neuronal microcircuits with the local field potential (LFP). Given that LFPs are generated by spatially separated currents across the neuronal membrane, they cannot be computed directly from quantities defined in models of point-like LIF neurons. Here, we explore the best approximation for predicting the LFP based on standard output from point-neuron LIF networks. To search for this best “LFP proxy”, we compared LFP predictions from candidate proxies based on LIF network output (e.g, firing rates, membrane potentials, synaptic currents) with “ground-truth” LFP obtained when the LIF network synaptic input currents were injected into an analogous three-dimensional (3D) network model of multi-compartmental neurons with realistic morphology, spatial distributions of somata and synapses. We found that a specific fixed linear combination of the LIF synaptic currents provided an accurate LFP proxy, accounting for most of the variance of the LFP time course observed in the 3D network for all recording locations. This proxy performed well over a broad set of conditions, including substantial variations of the neuronal morphologies. Our results provide a simple formula for estimating the time course of the LFP from LIF network simulations in cases where a single pyramidal population dominates the LFP generation, and thereby facilitate quantitative comparison between computational models and experimental LFP recordings in vivo. PMID:26657024
ERIC Educational Resources Information Center
Wise, Dena; Sneed, Christopher; Velandia, Margarita; Berry, Ann; Rhea, Alice; Fairhurst, Ann
2013-01-01
The Local Table project compared results from parallel surveys of consumers and restaurateurs regarding local food purchasing and use. Results were also compared with producers' perception of, capacity for and participation in direct marketing through local venues, on-farm outlets, and restaurants. The surveys found consumers' and…
NASA Astrophysics Data System (ADS)
He, Y.; Billen, M. I.; Puckett, E. G.
2015-12-01
Flow in the Earth's mantle is driven by thermo-chemical convection in which the properties and geochemical signatures of rocks vary depending on their origin and composition. For example, tectonic plates are composed of compositionally-distinct layers of crust, residual lithosphere and fertile mantle, while in the lower-most mantle there are large compositionally distinct "piles" with thinner lenses of different material. Therefore, tracking of active or passive fields with distinct compositional, geochemical or rheologic properties is important for incorporating physical realism into mantle convection simulations, and for investigating the long term mixing properties of the mantle. The difficulty in numerically advecting fields arises because they are non-diffusive and have sharp boundaries, and therefore require different methods than usually used for temperature. Previous methods for tracking fields include the marker-chain, tracer particle, and field-correction (e.g., the Lenardic Filter) methods: each of these has different advantages or disadvantages, trading off computational speed with accuracy in tracking feature boundaries. Here we present a method for modeling active fields in mantle dynamics simulations using a new solver implemented in the deal.II package that underlies the ASPECT software. The new solver for the advection-diffusion equation uses a Local Discontinuous Galerkin (LDG) algorithm, which combines features of both finite element and finite volume methods, and is particularly suitable for problems with a dominant first-order term and discontinuities. Furthermore, we have applied a post-processing technique to insure that the solution satisfies a global maximum/minimum. One potential drawback for the LDG method is that the total number of degrees of freedom is larger than the finite element method. To demonstrate the capabilities of this new method we present results for two benchmarks used previously: a falling cube with distinct buoyancy and
NASA Astrophysics Data System (ADS)
Futamoto, Masaaki; Handa, Takahiro; Takahashi, Yoshio
2010-01-01
The compositions of magnetic crystal grains and boundaries of a CoCrPt-SiO2 granular perpendicular medium were investigated for plan-view and cross-sectional samples by using a transmission electron microscope equipped with an energy-dispersive X-ray spectrometer. The grain boundary composition, which is not easy to measure because of the small width around 1 nm, is estimated from the average composition of magnetic layer and that of crystal grains by considering the grain boundary volume ratio determined by structure observation. The grain boundary is shown to include Si as the major metallic element together with not small amounts of other metallic elements.
Ermak, D L; Nasstrom, J S; Tull, J E; Baskett, R L; Pobanz, B; Mosley-Rovi, R
2002-11-18
The objective of the Local Integration of NARAC With Cities (LINC) project is to demonstrate the capability for providing local government agencies with advanced, CBNP-developed operational atmospheric plume prediction capabilities that can be seamlessly integrated with appropriate federal agency support for homeland security. LINC's approach is to integrate Lawrence Livermore National Laboratory's (LLNL) National Atmospheric Release Advisory Center (NARAC) tools and services with local emergency management and response centers. In the event of an airborne chemical or biological agent release in an urban area, large portions of the city and even the surrounding suburbs may be affected by the airborne plume, depending on the type of agent, size of release, dissemination mechanism and ambient meteorological conditions. The goal of LINC is to provide real-time predictions that would be used by emergency managers and responders (fire, police, hazmat, etc.) to map the extent and effects of hazardous airborne material. Prompt predictions are provided to guide first responders in determining protective actions to be taken (use of personal protective equipment, evacuation, sheltering in place, etc.), safe locations for incident command posts, and critical facilities that may be at risk (hospitals, schools, etc.). LINC also provides response teams from multiple jurisdictions (local, state, and federal) with tools to effectively share information regarding the areas and populations at risk. The ultimate goal of LINC is a seamless and coordinated nationwide system that integrates NARAC prediction and situation awareness resources with the appropriate local, state and federal agencies for homeland security applications ranging from planning to emergency response to consequence assessment and attribution.
Boundary Crossing and Boundary Objects
ERIC Educational Resources Information Center
Akkerman, Sanne F.; Bakker, Arthur
2011-01-01
Diversity and mobility in education and work present a paramount challenge that needs better conceptualization in educational theory. This challenge has been addressed by educational scholars with the notion of "boundaries", particularly by the concepts of "boundary crossing" and "boundary objects". Although studies on boundary crossing and…
NASA Astrophysics Data System (ADS)
Wang, J.; Song, J.; Gao, M.; Zhu, L.
2014-02-01
The trans-boundary area between Northern China, Mongolia and eastern Siberia of Russia is a continuous geographical area located in north eastern Asia. Many common issues in this region need to be addressed based on a uniform resources and environmental data warehouse. Based on the practice of joint scientific expedition, the paper presented a data integration solution including 3 steps, i.e., data collection standards and specifications making, data reorganization and process, data warehouse design and development. A series of data collection standards and specifications were drawn up firstly covering more than 10 domains. According to the uniform standard, 20 resources and environmental survey databases in regional scale, and 11 in-situ observation databases were reorganized and integrated. North East Asia Resources and Environmental Data Warehouse was designed, which included 4 layers, i.e., resources layer, core business logic layer, internet interoperation layer, and web portal layer. The data warehouse prototype was developed and deployed initially. All the integrated data in this area can be accessed online.
NASA Astrophysics Data System (ADS)
Horng, Jason; Balch, Halleh; Feng Wang Team
The spatio-temporal dynamics of local electric fields in ionic solutions plays a central role in various chemical and biological processes ranging from batteries technologies to neuron signaling. A non-invasive, precise detection scheme for measuring local electric fields dynamics has long been sought for. Here, we report a sensitive, high-speed, high spatial resolution optical imaging method for local electric fields based on the unique optoelectronic properties of graphene. With enhancement from a waveguide involving critical coupling concept, we show that our graphene optical sensor provides an ideal platform for studying dynamics of local electric field fluctuations in different nonequilibrium solutions.
NASA Astrophysics Data System (ADS)
Huang, Melin; Huang, Bormin; Huang, Allen H.
2014-10-01
The Weather Research and Forecasting (WRF) model provided operational services worldwide in many areas and has linked to our daily activity, in particular during severe weather events. The scheme of Yonsei University (YSU) is one of planetary boundary layer (PBL) models in WRF. The PBL is responsible for vertical sub-grid-scale fluxes due to eddy transports in the whole atmospheric column, determines the flux profiles within the well-mixed boundary layer and the stable layer, and thus provide atmospheric tendencies of temperature, moisture (including clouds), and horizontal momentum in the entire atmospheric column. The YSU scheme is very suitable for massively parallel computation as there are no interactions among horizontal grid points. To accelerate the computation process of the YSU scheme, we employ Intel Many Integrated Core (MIC) Architecture as it is a multiprocessor computer structure with merits of efficient parallelization and vectorization essentials. Our results show that the MIC-based optimization improved the performance of the first version of multi-threaded code on Xeon Phi 5110P by a factor of 2.4x. Furthermore, the same CPU-based optimizations improved the performance on Intel Xeon E5-2603 by a factor of 1.6x as compared to the first version of multi-threaded code.
NASA Astrophysics Data System (ADS)
Hirose, Masanobu; Miyake, Masayasu; Takada, Jun-Ichi; Arai, Ikuo
1999-01-01
We have derived a new form of the integral equation formulation of the measured equation of invariance (IE-MEI). The new formulation clarifies the existence of a relationship between scattered electric and magnetic fields at consecutive nodes in the IE-MEI and indicates that the relationship in a problem for a perfect electric conductor (PEC) holds for a problem with arbitrary materials. In a scattering problem of a two-dimensional cylinder with an impedance boundary condition (IBC), every matrix in the IE-MEI is a band-like sparse matrix. That is, the solution process in the IE-MEI with an IBC is the same as that for a PEC. Therefore the IE-MEI with an IBC has the same merits of the IE-MEI for a PEC: The more efficient computation can be achieved with the smaller memory than those of the method of moments (MOM). The IE-MEI with an IBC is validated by numerical examples for a circular cylinder and a square cylinder by comparison with a combined field MOM that satisfies exact boundary conditions. Numerical examples show that the IE-MEI with an IBC is applicable to the case where the generalized skin depth is less than half the width of a scatterer.
NASA Technical Reports Server (NTRS)
Morduchow, Morris
1955-01-01
A survey of integral methods in laminar-boundary-layer analysis is first given. A simple and sufficiently accurate method for practical purposes of calculating the properties (including stability) of the laminar compressible boundary layer in an axial pressure gradient with heat transfer at the wall is presented. For flow over a flat plate, the method is applicable for an arbitrarily prescribed distribution of temperature along the surface and for any given constant Prandtl number close to unity. For flow in a pressure gradient, the method is based on a Prandtl number of unity and a uniform wall temperature. A simple and accurate method of determining the separation point in a compressible flow with an adverse pressure gradient over a surface at a given uniform wall temperature is developed. The analysis is based on an extension of the Karman-Pohlhausen method to the momentum and the thermal energy equations in conjunction with fourth- and especially higher degree velocity and stagnation-enthalpy profiles.
NASA Astrophysics Data System (ADS)
Chen, D. S.; Cheng, S. Y.; Liu, L.; Chen, T.; Guo, X. R.
In this paper, an integrated MM5-CMAQ modeling approach was employed to investigate the PM 10 air pollution issue in Beijing, China, with a focus on assessing pollution contributions from surrounding provinces. A 2-level-nested grid domain with spatial resolutions of 36 and 12 km was designed for the study region. Seven monitoring stations across Beijing municipality were selected to provide hourly PM 10 measurement data. The months of January, April, July and October in 2002 were taken as target periods for model performance evaluation. Five emission scenarios were designed and run in order to quantitatively assess the trans-boundary PM 10 contributions. The results show that, while Beijing needs to take positive steps to reduce its own pollution emissions, much effort should also be placed on demanding more pollution reduction and better environmental performance from surrounding provinces.
Integrated aquitard-aquifer flow with a mixed-type well-face boundary and skin effect
NASA Astrophysics Data System (ADS)
Feng, Qinggao; Zhan, Hongbin
2016-03-01
A general analytical model describing groundwater flow to a partially penetrating well pumped at a constant rate in a leaky confined aquifer is developed. The model incorporates the effects of aquitard storage, aquifer anisotropy, wellbore storage and a finite well skin by treating the aquitard leakage as an aquitard-aquifer interface flow problem, and considers the well-face as a mixed-type or non-uniform flux (NUF) rather than a uniform flux (UF) boundary condition, which is novel. The solution is obtained using the Laplace transform coupled with separation of variables and discretization methods, followed by the numerical inverse Laplace transform. Moreover, the solution unifies some cases for flow to a partially penetrating well in a leaky confined aquifer including Perina and Lee (2006), Feng and Zhan (2015) and Hunt (2005) or confined aquifer including Chiu et al. (2007), Yang et al. (2006) and Hantush (1964). The newly developed NUF solution is compared with the UF solution. The NUF drawdown is larger than the UF drawdown at early time, while the NUF drawdown is smaller than the UF drawdown at intermediate and late times. The non-uniform flux along the well-face has significant impact on drawdown in the skin zone, while the UF solution can completely replace the NUF solution at a radial distance from the pumped well equaling to or greater than the aquifer thickness. The NUF and UF drawdowns for no skin case are remarkably smaller than that for the positive skin case and larger than that for the negative skin case. A thicker well skin results in a smaller drawdown in the skin zone.
Porschke, Dietmar
2016-07-01
Because of repeated claims that A-DNA cannot exist without aggregation or condensation, the state of DNA restriction fragments with 84-859 bp has been analyzed in aqueous solutions upon reduction of the water activity. Rotational diffusion times τ (d) measured by electric dichroism at different water activities with a wide variation of viscosities are normalized to values τ (c) at the viscosity of water, which indicate DNA structures at a high sensitivity. For short helices (chain lengths [Formula: see text] ≤ persistence length p), cooperative formation of A-DNA is reflected by the expected reduction of the hydrodynamic length; the transition to the A-form is without aggregation or condensation upon addition of ethanol at monovalent salt ≤1 mM. The aggregation boundary, indicated by a strong increase of τ (c), is shifted to higher monovalent salt (≥4 mM) when ethanol is replaced by trifluoroethanol. The BA transition is not indicated anymore by a cooperative change of τ (c) for [Formula: see text] » p; τ (c) values for these long chains decrease upon reduction of the water activity continuously over the full range, including the BA transition interval. This suggests a non-cooperative BC transition, which induces DNA curvature. The resulting wide distribution of global structures hides changes of local length during the BA transition. Free A-DNA without aggregation/condensation is found at low-salt concentrations where aggregation is inhibited and/or very slow. In an intermediate range of solvent conditions, where the A-form starts to aggregate, a time window remains that can be used for analysis of free A-DNA in a quasi-equilibrium state. PMID:26872482
Tapping into community wisdom and integrating local knowledge into revitalization efforts
Local decision-making is sometimes considered a puzzle by research ecologists, resource managers, and policy researchers. The eternal hope is to find that model or concept that provides the “right” information to support local environmental decisions. Researchers have...
This project will develop a model for place-based green building guidelines based on an analysis of local environmental, social, and land use conditions. The ultimate goal of this project is to develop a methodology and model for placing green buildings within their local cont...
Lin, L. Ding, W. X.; Brower, D. L.
2014-11-15
Combined polarimetry-interferometry capability permits simultaneous measurement of line-integrated density and Faraday effect with fast time response (∼1 μs) and high sensitivity. Faraday effect fluctuations with phase shift of order 0.05° associated with global tearing modes are resolved with an uncertainty ∼0.01°. For physics investigations, local density fluctuations are obtained by inverting the line-integrated interferometry data. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of the polarimetry data. Reconstructed 2D images of density and magnetic field fluctuations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved.
Waisman, Yehezkel
2003-06-01
International medical aid after natural disasters may take various forms, ranging from self-sufficient military forces to single experts or specialists who function primarily as advisers. A model integrating foreign and local medical staff has not previously been reported. In response to the call for international aid by the Honduran and El Salvadorian governments in the wake of Hurricane Mitch in November 1998 and the San Salvador earthquake in January 2001, Israel sent medical supplies and 10 member teams of medical professionals to each country. The aim of the present paper is to describe the unique Israeli approach to providing healthcare in disaster areas by integrating foreign and local medical staff, and to discuss its advantages and disadvantages. The paper focuses on the experience of the two emergency medicine physicians on the team who were assigned to the Atlantida General Hospital in La Ceiba, Honduras. The same team in San Salvador subsequently applied the same approach. PMID:12789069
Boundary transfer matrices and boundary quantum KZ equations
Vlaar, Bart
2015-07-15
A simple relation between inhomogeneous transfer matrices and boundary quantum Knizhnik-Zamolodchikov (KZ) equations is exhibited for quantum integrable systems with reflecting boundary conditions, analogous to an observation by Gaudin for periodic systems. Thus, the boundary quantum KZ equations receive a new motivation. We also derive the commutativity of Sklyanin’s boundary transfer matrices by merely imposing appropriate reflection equations, in particular without using the conditions of crossing symmetry and unitarity of the R-matrix.
NASA Technical Reports Server (NTRS)
Tobagi, Fouad A.; Dalgic, Ismail; Pang, Joseph
1990-01-01
The design and implementation of interface units for high speed Fiber Optic Local Area Networks and Broadband Integrated Services Digital Networks are discussed. During the last years, a number of network adapters that are designed to support high speed communications have emerged. This approach to the design of a high speed network interface unit was to implement package processing functions in hardware, using VLSI technology. The VLSI hardware implementation of a buffer management unit, which is required in such architectures, is described.
An urban approach to planetary boundaries.
Hoornweg, Daniel; Hosseini, Mehdi; Kennedy, Christopher; Behdadi, Azin
2016-09-01
The achievement of global sustainable development goals subject to planetary boundaries will mostly be determined by cities as they drive cultures, economies, material use, and waste generation. Locally relevant, applied and quantitative methodologies are critical to capture the complexity of urban infrastructure systems, global inter-connections, and to monitor local and global progress toward sustainability. An urban monitoring (and communications) tool is presented here illustrating that a city-based approach to sustainable development is possible. Following efforts to define and quantify safe planetary boundaries in areas such as climate change, biosphere integrity, and freshwater use, this paper modifies the methodology to propose boundaries from a city's perspective. Socio-economic boundaries, or targets, largely derived from the Sustainable Development Goals are added to bio-physical boundaries. Issues such as data availability, city priorities, and ease of implementation are considered. The framework is trialed for Toronto, Shanghai, Sao Paulo, Mumbai, and Dakar, as well as aggregated for the world's larger cities. The methodology provides an important tool for cities to play a more fulsome and active role in global sustainable development. PMID:26897006
NASA Astrophysics Data System (ADS)
Scott, Richard; Khan, Faisal M.; Zeineh, Jack; Donovan, Michael; Fernandez, Gerardo
2015-03-01
Immunofluorescent (IF) image analysis of tissue pathology has proven to be extremely valuable and robust in developing prognostic assessments of disease, particularly in prostate cancer. There have been significant advances in the literature in quantitative biomarker expression as well as characterization of glandular architectures in discrete gland rings. However, while biomarker and glandular morphometric features have been combined as separate predictors in multivariate models, there is a lack of integrative features for biomarkers co-localized within specific morphological sub-types; for example the evaluation of androgen receptor (AR) expression within Gleason 3 glands only. In this work we propose a novel framework employing multiple techniques to generate integrated metrics of morphology and biomarker expression. We demonstrate the utility of the approaches in predicting clinical disease progression in images from 326 prostate biopsies and 373 prostatectomies. Our proposed integrative approaches yield significant improvements over existing IF image feature metrics. This work presents some of the first algorithms for generating innovative characteristics in tissue diagnostics that integrate co-localized morphometry and protein biomarker expression.
NASA Astrophysics Data System (ADS)
Vipparthi, Santosh Kumar; Nagar, Shyam Krishna
2014-09-01
This paper presents two new feature descriptors for content based image retrieval (CBIR) application. The proposed two descriptors are named as color local derivative patterns (CLDP) and inter color local derivative pattern (ICLDP). In order to reduce the computational complexity the uniform patterns are applied to both CLDP and ICLDP. Further, uniform CLDP (CLDPu2) and uniform ICLDP (ICLDPu2) are generated respectively. The proposed descriptors are able to exploit individual (R, G and B) spectral channel information and co-relating pair (RG, GB, BR, etc.) of spectral channel information. The retrieval performances of the proposed descriptors (CLDP and ICLDP) are tested by conducting two experiments on Corel-5000 and Corel-10000 benchmark databases. The results after investigation show a significant improvement in terms of precision, average retrieval precision (ARP), recall and average retrieval rate (ARR) as compared to local binary patterns (LBP), local derivative patterns (LDP) and other state-of-the-art techniques for image retrieval.
NASA Astrophysics Data System (ADS)
Vipparthi, Santosh Kumar; Nagar, Shyam Krishna
2015-09-01
This paper presents two new feature descriptors for content based image retrieval (CBIR) application. The proposed two descriptors are named as color local derivative patterns (CLDP) and inter color local derivative pattern (ICLDP). In order to reduce the computational complexity the uniform patterns are applied to both CLDP and ICLDP. Further, uniform CLDP (CLDPu2) and uniform ICLDP (ICLDPu2) are generated respectively. The proposed descriptors are able to exploit individual (R, G and B) spectral channel information and co-relating pair (RG, GB, BR, etc.) of spectral channel information. The retrieval performances of the proposed descriptors (CLDP and ICLDP) are tested by conducting two experiments on Corel-5000 and Corel-10000 benchmark databases. The results after investigation show a significant improvement in terms of precision, average retrieval precision (ARP), recall and average retrieval rate (ARR) as compared to local binary patterns (LBP), local derivative patterns (LDP) and other state-of-the-art techniques for image retrieval.
NASA Technical Reports Server (NTRS)
Lu, Huei-Lin; Robertson, Franklin R.
2003-01-01
A diagnostic study is made of the mean global divergent circulation based upon a constrained least action principle that minimizes column-integrated divergent kinetic energy subject to constraints on mass, moisture, available potential energy (ape) and total kinetic energy. The concept of gross moist stability was incorporated in the prescription of Lagrange weight function associated with the ape constraint in order to simulate the net effects of cumulus convective heating in the tropics. The variational analyses were validated satisfactorily with the original NCEP/NCAR-reanalysis divergence fields for the Septembers of 1987 and 1988. Further analyses show that in the tropical ascending regions, the analyzed divergences are dominated by the mass and ape constraints; the moisture constraint is implicitly satisfied while the kinetic energy constraint is highly dependent on the ape constraint. In the subtropical descending regions, the analyzed divergences are dominated by the mass, moisture and kinetic energy constraints; the ape constraint is implicitly satisfied. When the constraint integrals were blended with the satellite-derived boundary flux data from GPCP precipitation and ERBE/SRB radiation estimates, the newly analyzed divergences are significantly stronger than the reanalysis divergences in the areas where the estimates of precipitation rates are higher. With few exceptions, the increases in upper-layer divergences are coupled with nearly equal increases in lower-layer convergences.
2013-01-01
Background Childhood obesity is a ‘wicked’ public health problem that is best tackled by an integrated approach, which is enabled by integrated public health policies. The development and implementation of such policies have in practice proven to be difficult, however, and studying why this is the case requires a tool that may assist local policy-makers and those assisting them. A comprehensive framework that can help to identify options for improvement and to systematically develop solutions may be used to support local policy-makers. Discussion We propose the ‘Behavior Change Ball’ as a tool to study the development and implementation of integrated public health policies within local government. Based on the tenets of the ‘Behavior Change Wheel’ by Michie and colleagues (2011), the proposed conceptual framework distinguishes organizational behaviors of local policy-makers at the strategic, tactical and operational levels, as well as the determinants (motivation, capability, opportunity) required for these behaviors, and interventions and policy categories that can influence them. To illustrate the difficulty of achieving sustained integrated approaches, we use the metaphor of a ball in our framework: the mountainous landscapes surrounding the ball reflect the system’s resistance to change (by making it difficult for the ball to roll). We apply this framework to the problem of childhood obesity prevention. The added value provided by the framework lies in its comprehensiveness, theoretical basis, diagnostic and heuristic nature and face validity. Summary Since integrated public health policies have not been widely developed and implemented in practice, organizational behaviors relevant to the development of these policies remain to be investigated. A conceptual framework that can assist in systematically studying the policy process may facilitate this. Our Behavior Change Ball adds significant value to existing public health policy frameworks by
An integrative model of the cardiac ventricular myocyte incorporating local control of Ca2+ release.
Greenstein, Joseph L; Winslow, Raimond L
2002-01-01
The local control theory of excitation-contraction (EC) coupling in cardiac muscle asserts that L-type Ca(2+) current tightly controls Ca(2+) release from the sarcoplasmic reticulum (SR) via local interaction of closely apposed L-type Ca(2+) channels (LCCs) and ryanodine receptors (RyRs). These local interactions give rise to smoothly graded Ca(2+)-induced Ca(2+) release (CICR), which exhibits high gain. In this study we present a biophysically detailed model of the normal canine ventricular myocyte that conforms to local control theory. The model formulation incorporates details of microscopic EC coupling properties in the form of Ca(2+) release units (CaRUs) in which individual sarcolemmal LCCs interact in a stochastic manner with nearby RyRs in localized regions where junctional SR membrane and transverse-tubular membrane are in close proximity. The CaRUs are embedded within and interact with the global systems of the myocyte describing ionic and membrane pump/exchanger currents, SR Ca(2+) uptake, and time-varying cytosolic ion concentrations to form a model of the cardiac action potential (AP). The model can reproduce both the detailed properties of EC coupling, such as variable gain and graded SR Ca(2+) release, and whole-cell phenomena, such as modulation of AP duration by SR Ca(2+) release. Simulations indicate that the local control paradigm predicts stable APs when the L-type Ca(2+) current is adjusted in accord with the balance between voltage- and Ca(2+)-dependent inactivation processes as measured experimentally, a scenario where common pool models become unstable. The local control myocyte model provides a means for studying the interrelationship between microscopic and macroscopic behaviors in a manner that would not be possible in experiments. PMID:12496068
On local description of two-dimensional geodesic flows with a polynomial first integral
NASA Astrophysics Data System (ADS)
Pavlov, Maxim V.; Tsarev, Sergey P.
2016-04-01
In this paper we present a construction of multiparametric families of two-dimensional metrics with a polynomial first integral of arbitrary degree in momenta. Such integrable geodesic flows are described by solutions of some semi-Hamiltonian hydrodynamic-type system. We give a constructive algorithm for the solution of the derived hydrodynamic-type system, i.e. we found infinitely many conservation laws and commuting flows. Thus we were able to find infinitely many particular solutions of this hydrodynamic-type system by the generalized hodograph method. Therefore infinitely many particular two-dimensional metrics equipped with first integrals polynomial in momenta were constructed. dedicated to the 55th birthday of our friend E V Ferapontov.
Integrating the Management of Ruaha Landscape of Tanzania with Local Needs and Preferences
NASA Astrophysics Data System (ADS)
Masozera, Michel; Erickson, Jon D.; Clifford, Deana; Coppolillo, Peter; Sadiki, Harrison G.; Mazet, Jonna K.
2013-12-01
Sustainable management of landscapes with multiple competing demands such as the Ruaha Landscape is complex due to the diverse preferences and needs of stakeholder groups involved. This study uses conjoint analysis to assess the preferences of representatives from three stakeholder groups—local communities, district government officials, and non-governmental organizations—toward potential solutions of conservation and development tradeoffs facing local communities in the Ruaha Landscape of Tanzania. Results demonstrate that there is little consensus among stakeholders about the best development strategies for the Ruaha region. This analysis suggests a need for incorporating issues deemed important by these various groups into a development strategy that aims to promote conservation of the Ruaha Landscape and improve the livelihood of local communities.
NASA Astrophysics Data System (ADS)
Boyce, E. S.; Bierma, R. M.; Willoughby, H.; Feaux, K.; Mattioli, G. S.; Enders, M.; Busby, R. W.
2014-12-01
EarthScope's geodetic component in Alaska, the UNAVCO-operated Plate Boundary Observatory (PBO) network, includes 139 continuous GPS sites and 41 supporting telemetry relays. These are spread across a vast area, from northern AK to the Aleutians. Forty-five of these stations were installed or have been upgraded in cooperation with various partner agencies and currently provide data collection and transmission for more than one group. Leveraging existing infrastructure normally has multiple benefits, such as easier permitting requirements and costs savings through reduced overall construction and maintenance expenses. At some sites, PBO-AK power and communications systems have additional capacity beyond that which is needed for reliable acquisition of GPS data. Where permits allow, such stations could serve as platforms for additional instrumentation or real-time observing needs. With the expansion of the Transportable Array (TA) into Alaska, there is increased interest to leverage existing EarthScope resources for station co-location and telemetry integration. Because of the complexity and difficulty of long-term O&M at PBO sites, however, actual integration of GPS and seismic equipment must be considered on a case-by-case basis. UNAVCO currently operates two integrated GPS/seismic stations in collaboration with the Alaska Earthquake Center, and three with the Alaska Volcano Observatory. By the end of 2014, PBO and TA plan to install another four integrated and/or co-located geodetic and seismic systems. While three of these are designed around existing PBO stations, one will be a completely new TA installation, providing PBO with an opportunity to expand geodetic data collection in Alaska within the limited operations and maintenance phase of the project. We will present some of the design considerations, outcomes, and lessons learned from past and ongoing projects to integrate seismometers and other instrumentation at PBO-Alaska stations. Developing the PBO
Ajia, Idris A.; Roqan, I. S.; Edwards, P. R.; Martin, R. W.; Liu, Z.; Yan, J. C.
2014-09-22
AlGaN/AlGaN multi-quantum-wells (MQW) with AlN-rich grains have been grown by metal organic chemical vapor deposition. The grains are observed to have strong excitonic localization characteristics that are affected by their sizes. The tendency to confine excitons progressively intensifies with increasing grain boundary area. Photoluminescence results indicate that the MQW have a dominant effect on the peak energy of the near-bandedge emission at temperatures below 150 K, with the localization properties of the grains becoming evident beyond 150 K. Cathodoluminescence maps reveal that the grain boundary has no effect on the peak intensities of the AlGaN/AlGaN samples.
Local parallel models for integration of stereo matching constraints and intrinsic image combination
NASA Technical Reports Server (NTRS)
Stewart, Charles V.
1989-01-01
Parallel relaxation computations such as those of connectionist networks offer a useful model for constraint integration and intrinsic image combination in developing a general-purpose stereo matching algorithm. This paper describes such a stereo algorithm that incorporates hierarchical, surface-structure, and edge-appearance constraints that are redefined and integrated at the level of individual candidate matches. The algorithm produces a high percentage of correct decisions on a wide variety of stereo pairs. Its few errors arise when the correlation measures defined by the constraints are either weakened or ambiguous, as in the case of periodic patterns in the images. Two additional mechanisms are discussed for overcoming the remaining errors.
NASA Astrophysics Data System (ADS)
Fullea, J.; Fernàndez, M.; Afonso, J.; Verges, J.; Zeyen, H. J.
2009-12-01
In this work we study the present-day thermal and compositional 3D structure of the lithosphere beneath the Atlantic-Mediterranean Transition Region (AMTR) and the lithosphere-asthenosphere interaction from Jurassic times to present. The AMTR comprises the western segment of the Africa-Eurasia plate boundary, encompassing two main large-scale tectonic domains: the Gibraltar Arc System and the Atlas Mountains. We apply an integrated and self-consistent geophysical-petrological methodology (LitMod3D) that combines elevation, gravity, geoid, surface heat flow, and seismic data and allows modelling of compositional heterogeneities within the lithospheric mantle. Our results reveal large variations in the depth of the Moho and the lithosphere-asthenosphere boundary (LAB) as well as a lack of spatial correlation between the thicknesses of these two boundaries. The Moho essentially mimics the topography with depths ranging from ~10 km beneath the oceanic domains of the Atlantic abyssal plains and the Algerian Basin to >34 km in the Eastern Betics and Rif, the High Atlas mountains, and the Sahara Platform. In contrast, the LAB is shallower beneath the central and eastern Alboran Basin (~70 km) and all along the High, Middle and Anti Atlas (<100 km) coinciding with the loci of Cenozoic volcanism. Deeper LAB depths are found along the central and western Betics and the Moroccan Atlantic margin (>140 km) with values exceeding 230 km beneath the Rif and the Sahara Platform. We find that the average bulk composition of the lithospheric mantle corresponds to that of a typical Tecton (i.e. Phanerozoic) domain, with the exceptions of the Sahara Platform, the Alboran Basin, and Atlas Mountains. Distinct mantle compositions are required in these areas to make model predictions and geophysical observables compatible. We propose that the highly irregular LAB topography is the result of the superposition of three different geodynamic mechanisms, which include shortening and thickening
Local Integration Ontological Model of Creative Class Migrants for Creative Cities
ERIC Educational Resources Information Center
Sangkakorn, Korawan; Chakpitak, Nopasit; Yodmongkol, Pitipong
2015-01-01
An innovative creative class drives creative cities, urban areas in which diverse cultures are integrated into social and economic functions. The creative city of Chiang Mai, Thailand is renowned for its vibrant Lan Na culture and traditions, and draws new migrants from other areas in Thailand seeking to become part of the creative class. This…
Lin, Tzu-Hsuan; Lu, Yung-Chi; Hung, Shih-Lin
2014-01-01
This study developed an integrated global-local approach for locating damage on building structures. A damage detection approach with a novel embedded frequency response function damage index (NEFDI) was proposed and embedded in the Imote2.NET-based wireless structural health monitoring (SHM) system to locate global damage. Local damage is then identified using an electromechanical impedance- (EMI-) based damage detection method. The electromechanical impedance was measured using a single-chip impedance measurement device which has the advantages of small size, low cost, and portability. The feasibility of the proposed damage detection scheme was studied with reference to a numerical example of a six-storey shear plane frame structure and a small-scale experimental steel frame. Numerical and experimental analysis using the integrated global-local SHM approach reveals that, after NEFDI indicates the approximate location of a damaged area, the EMI-based damage detection approach can then identify the detailed damage location in the structure of the building. PMID:24672359
Hung, Shih-Lin
2014-01-01
This study developed an integrated global-local approach for locating damage on building structures. A damage detection approach with a novel embedded frequency response function damage index (NEFDI) was proposed and embedded in the Imote2.NET-based wireless structural health monitoring (SHM) system to locate global damage. Local damage is then identified using an electromechanical impedance- (EMI-) based damage detection method. The electromechanical impedance was measured using a single-chip impedance measurement device which has the advantages of small size, low cost, and portability. The feasibility of the proposed damage detection scheme was studied with reference to a numerical example of a six-storey shear plane frame structure and a small-scale experimental steel frame. Numerical and experimental analysis using the integrated global-local SHM approach reveals that, after NEFDI indicates the approximate location of a damaged area, the EMI-based damage detection approach can then identify the detailed damage location in the structure of the building. PMID:24672359
Integrating local, expert, and practical knowledge in community remediation and revitalization
Researchers and natural resource managers often develop tools and methods to facilitate the inclusion of science in local environmental decision-making. The eternal hope is to find that model or concept that provides the “right” information to support these decisions....
NASA Technical Reports Server (NTRS)
Atluri, Satya N.; Shen, Shengping
2002-01-01
In this paper, a very simple method is used to derive the weakly singular traction boundary integral equation based on the integral relationships for displacement gradients. The concept of the MLPG method is employed to solve the integral equations, especially those arising in solid mechanics. A moving Least Squares (MLS) interpolation is selected to approximate the trial functions in this paper. Five boundary integral Solution methods are introduced: direct solution method; displacement boundary-value problem; traction boundary-value problem; mixed boundary-value problem; and boundary variational principle. Based on the local weak form of the BIE, four different nodal-based local test functions are selected, leading to four different MLPG methods for each BIE solution method. These methods combine the advantages of the MLPG method and the boundary element method.
Balluffi, R.W.; Bristowe, P.D.
1990-01-01
The present document is a progress report describing the work accomplished on the study of grain boundaries in Ag, Au, Ni, Si, and Ge. Research was focused on the following four major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; grain boundary migration; short-circuit diffusion along grain boundaries; and development of Thin-Film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals. 10 refs., 1 fig.
Krisiloff, David B; Krauter, Caroline M; Ricci, Francis J; Carter, Emily A
2015-11-10
To treat large molecules with accurate ab initio quantum chemistry, reduced scaling correlated wave function methods are now commonly employed. Optimization of these wave functions in practice requires some approximation of the two-electron integrals. Both Cholesky decomposition (CD) and density fitting (DF) are widely used approaches to approximate these integrals. Here, we compare CD and DF for use in local multireference singles and doubles configuration interaction (LMRSDCI). DF-LMRSDCI provides less accurate total energies than CD-LMRSDCI, but both methods are accurate for energy differences. However, DF-LMRSDCI is significantly less computationally expensive than CD-LMRSDCI on the molecules tested, suggesting that DF-LMRSDCI is an efficient, often sufficiently accurate alternative to our previously reported CD-LMRSDCI method. PMID:26574318
Budde, M.E.; Tappan, G.; Rowland, J.; Lewis, J.; Tieszen, L.L.
2004-01-01
The researchers calculated seasonal integrated normalized difference vegetation index (NDVI) for each of 7 years using a time-series of 1-km data from the Advanced Very High Resolution Radiometer (AVHRR) (1992-93, 1995) and SPOT Vegetation (1998-2001) sensors. We used a local variance technique to identify each pixel as normal or either positively or negatively anomalous when compared to its surroundings. We then summarized the number of years that a given pixel was identified as an anomaly. The resulting anomaly maps were analysed using Landsat TM imagery and extensive ground knowledge to assess the results. This technique identified anomalies that can be linked to numerous anthropogenic impacts including agricultural and urban expansion, maintenance of protected areas and increased fallow. Local variance analysis is a reliable method for assessing vegetation degradation resulting from human pressures or increased land productivity from natural resource management practices. ?? 2004 Published by Elsevier Ltd.
Putz, Mihai V.
2009-01-01
The density matrix theory, the ancestor of density functional theory, provides the immediate framework for Path Integral (PI) development, allowing the canonical density be extended for the many-electronic systems through the density functional closure relationship. Yet, the use of path integral formalism for electronic density prescription presents several advantages: assures the inner quantum mechanical description of the system by parameterized paths; averages the quantum fluctuations; behaves as the propagator for time-space evolution of quantum information; resembles Schrödinger equation; allows quantum statistical description of the system through partition function computing. In this framework, four levels of path integral formalism were presented: the Feynman quantum mechanical, the semiclassical, the Feynman-Kleinert effective classical, and the Fokker-Planck non-equilibrium ones. In each case the density matrix or/and the canonical density were rigorously defined and presented. The practical specializations for quantum free and harmonic motions, for statistical high and low temperature limits, the smearing justification for the Bohr’s quantum stability postulate with the paradigmatic Hydrogen atomic excursion, along the quantum chemical calculation of semiclassical electronegativity and hardness, of chemical action and Mulliken electronegativity, as well as by the Markovian generalizations of Becke-Edgecombe electronic focalization functions – all advocate for the reliability of assuming PI formalism of quantum mechanics as a versatile one, suited for analytically and/or computationally modeling of a variety of fundamental physical and chemical reactivity concepts characterizing the (density driving) many-electronic systems. PMID:20087467
Local and global semantic integration in an argument structure: ERP evidence from Korean.
Nam, Yunju; Hong, Upyong
2016-07-01
The neural responses of Korean speakers were recorded while they read sentences that included local semantic mismatch between adjectives (A) and nouns (N) or/and global semantic mismatch between object nouns (N) and verbs (V), as well as the corresponding control sentences without any semantic anomalies. In Experiment 1 using verb-final declarative sentences (Nsubject [A-N]object V), the local A-N incongruence yielded an N400 effect at the object noun and a combination of N400 and a late negativity effect at the sentence final verb, whereas the global N-V incongruence yielded a biphasic N400 and P600 ERP pattern at the verb compared with the ERPs of same words in the control sentences respectively; in Experiment 2 using verb-initial object relative clause constructions ([Nsubject _V]rel [A-N]object …..) derived from the materials of Experiment 1, the effect of local incongruence changed notably such that not only an N400 but also an additional P600 effect was observed at the object noun, whereas the effect of the global incongruence remained largely the same (N400 and P600). Our theoretical interpretation of these results specifically focused on the reason for the P600 effects observed across different experiment conditions, which turned out to be attributable to (i) coordination of a semantic conflict, (ii) prediction disconfirmation, or (iii) argument structure processing breakdown. PMID:27095512
Integration of local and global features for anatomical object detection in ultrasound.
Rahmatullah, Bahbibi; Papageorghiou, Aris T; Noble, J Alison
2012-01-01
The use of classifier-based object detection has found to be a promising approach in medical anatomy detection. In ultrasound images, the detection task is very challenging due to speckle, shadows and low contrast characteristic features. Typical detection algorithms that use purely intensity-based image features with an exhaustive scan of the image (sliding window approach) tend not to perform very well and incur a very high computational cost. The proposed approach in this paper achieves a significant improvement in detection rates while avoiding exhaustive scanning, thereby gaining a large increase in speed. Our approach uses the combination of local features from an intensity image and global features derived from a local phase-based image known as feature symmetry. The proposed approach has been applied to 2384 two-dimensional (2D) fetal ultrasound abdominal images for the detection of the stomach and the umbilical vein. The results presented show that it outperforms prior related work that uses only local or only global features. PMID:23286156
Xie, G.; Li, J.; Majer, E.; Zuo, D.
1998-07-01
This paper describes a new 3D parallel GILD electromagnetic (EM) modeling and nonlinear inversion algorithm. The algorithm consists of: (a) a new magnetic integral equation instead of the electric integral equation to solve the electromagnetic forward modeling and inverse problem; (b) a collocation finite element method for solving the magnetic integral and a Galerkin finite element method for the magnetic differential equations; (c) a nonlinear regularizing optimization method to make the inversion stable and of high resolution; and (d) a new parallel 3D modeling and inversion using a global integral and local differential domain decomposition technique (GILD). The new 3D nonlinear electromagnetic inversion has been tested with synthetic data and field data. The authors obtained very good imaging for the synthetic data and reasonable subsurface EM imaging for the field data. The parallel algorithm has high parallel efficiency over 90% and can be a parallel solver for elliptic, parabolic, and hyperbolic modeling and inversion. The parallel GILD algorithm can be extended to develop a high resolution and large scale seismic and hydrology modeling and inversion in the massively parallel computer.
Ghorbani Shahna, Farshid; Bahrami, Abdulrahman; Farasati, Farhad
2012-01-01
Local exhaust ventilation (LEV) systems and integrated collectors were designed and implemented in a mining company in order to control emitted air pollutant from furnaces. The LEV was designed for capture and transition of air pollutants emitted from furnaces to the integrated collectors. The integrated collectors including four high efficiency Stairmand model cyclones for control of particulate matter, a venturi scrubber for control of the fine particles, SO(2) and a part of H(2)S to follow them, and a packed scrubber for treatment of the residual H(2)S and SO(2) were designed. Pollutants concentration were measured to determine system effectiveness. The results showed that the effectiveness of LEV for reducing workplace pollution is 91.83%, 96.32% and 83.67% for dust, SO(2) and H(2)S, respectively. Average removal efficiency of particles by combination of cyclone and venturi scrubber was 98.72%. Average removal efficiency of SO(2) and H(2)S were 95.85% and 47.13% for the venturi scrubber and 68.45% and 92.7% for the packed bed scrubber. The average removal efficiency of SO(2) and H(2)S were increased to 99.1% and 95.95% by the combination of venturi and packed bed scrubbers. According to the results, integrated collectors are a good air pollution control option for industries with economic constraints and ancient technologies. PMID:22878358
NASA Astrophysics Data System (ADS)
Maire, Jérôme; Gagné, Jonathan; Lafrenière, David; Doyon, René; Graham, James R.; Véran, Jean-Pierre; Poyneer, Lisa A.
2012-07-01
Direct imaging and spectroscopy can advance our understanding of planet formation and migration through the detection and characterization of extrasolar planets on wide orbits. Accurate photometry and astrometry of detected companions are of crucial importance to derive the planet physical properties.We present an extension of the Locally optimized combination of images (LOCI) method to measure the highest-fidelity photometry as well as accurate astrometry of detected companions. This algorithm is also generalized to Integral-Field Spectrograph (IFS) data processing, giving advantages of a simultaneous angular and spectral differential imaging reduction, retrieving high-fidelity spectra from PSF-subtracted cubes.
NASA Astrophysics Data System (ADS)
Benhalouche, Fatima Zohra; Karoui, Moussa Sofiane; Deville, Yannick; Ouamri, Abdelaziz
2015-10-01
In this paper, a new Spectral-Unmixing-based approach, using Nonnegative Matrix Factorization (NMF), is proposed to locally multi-sharpen hyperspectral data by integrating a Digital Surface Model (DSM) obtained from LIDAR data. In this new approach, the nature of the local mixing model is detected by using the local variance of the object elevations. The hyper/multispectral images are explored using small zones. In each zone, the variance of the object elevations is calculated from the DSM data in this zone. This variance is compared to a threshold value and the adequate linear/linearquadratic spectral unmixing technique is used in the considered zone to independently unmix hyperspectral and multispectral data, using an adequate linear/linear-quadratic NMF-based approach. The obtained spectral and spatial information thus respectively extracted from the hyper/multispectral images are then recombined in the considered zone, according to the selected mixing model. Experiments based on synthetic hyper/multispectral data are carried out to evaluate the performance of the proposed multi-sharpening approach and literature linear/linear-quadratic approaches used on the whole hyper/multispectral data. In these experiments, real DSM data are used to generate synthetic data containing linear and linear-quadratic mixed pixel zones. The DSM data are also used for locally detecting the nature of the mixing model in the proposed approach. Globally, the proposed approach yields good spatial and spectral fidelities for the multi-sharpened data and significantly outperforms the used literature methods.