Surface structures of normal paraffins and cyclohexane monolayers and thin crystals grown on the (111) crystal face of platinum. A low-energy electron diffraction study

International Nuclear Information System (INIS)

Firment, L.E.; Somorjai, G.A.

1977-01-01

The surfaces of the normal paraffins (C 3 --C 8 ) and cyclohexane have been studied using low-energy electron diffraction (LEED). The samples were prepared by vapor deposition on the (111) face of a platinum single crystal in ultrahigh vacuum, and were studied both as thick films and as adsorbed monolayers. These molecules form ordered monolayers on the clean metal surface in the temperature range 100--220 K and at a vapor flux corresponding to 10 -7 Torr. In the adsorbed monolayers of the normal paraffins (C 4 --C 8 ), the molecules lie with their chain axes parallel to the Pt surface and Pt[110]. The paraffin monolayer structures undergo order--disorder transitions as a function of temperature. Multilayers condensed upon the ordered monolayers maintained the same orientation and packing as found in the monolayers. The surface structures of the growing organic crystals do not corresond to planes in their reported bulk crystal structures and are evidence for epitaxial growth of pseudomorphic crystal forms. Multilayers of n-octane and n-heptane condensed upon disordered monolayers have also grown with the (001) plane of the triclinic bulk crystal structures parallel to the surface. n-Butane has three monolayer structures on Pt(111) and one of the three is maintained during growth of the crystal. Cyclohexane forms an ordered monolayer, upon which a multilayer of cyclohexane grows exhibiting the (001) surface orientation of the monoclinic bulk crystal structure. Surface structures of saturated hydrocarbons are found to be very susceptible to electron beam induced damage. Surface charging interferes with LEED only at sample thicknesses greater than 200 A

Parallel image-acquisition in continuous-wave electron paramagnetic resonance imaging with a surface coil array: Proof-of-concept experiments

Science.gov (United States)

Enomoto, Ayano; Hirata, Hiroshi

2014-02-01

This article describes a feasibility study of parallel image-acquisition using a two-channel surface coil array in continuous-wave electron paramagnetic resonance (CW-EPR) imaging. Parallel EPR imaging was performed by multiplexing of EPR detection in the frequency domain. The parallel acquisition system consists of two surface coil resonators and radiofrequency (RF) bridges for EPR detection. To demonstrate the feasibility of this method of parallel image-acquisition with a surface coil array, three-dimensional EPR imaging was carried out using a tube phantom. Technical issues in the multiplexing method of EPR detection were also clarified. We found that degradation in the signal-to-noise ratio due to the interference of RF carriers is a key problem to be solved.

Plane parallel radiance transport for global illumination in vegetation

Energy Technology Data Exchange (ETDEWEB)

Max, N.; Mobley, C.; Keating, B.; Wu, E.H.

1997-01-05

This paper applies plane parallel radiance transport techniques to scattering from vegetation. The leaves, stems, and branches are represented as a volume density of scattering surfaces, depending only on height and the vertical component of the surface normal. Ordinary differential equations are written for the multiply scattered radiance as a function of the height above the ground, with the sky radiance and ground reflectance as boundary conditions. They are solved using a two-pass integration scheme to unify the two-point boundary conditions, and Fourier series for the dependence on the azimuthal angle. The resulting radiance distribution is used to precompute diffuse and specular `ambient` shading tables, as a function of height and surface normal, to be used in rendering, together with a z-buffer shadow algorithm for direct solar illumination.

Energy flow of electric dipole radiation in between parallel mirrors

Science.gov (United States)

Xu, Zhangjin; Arnoldus, Henk F.

2017-11-01

We have studied the energy flow patterns of the radiation emitted by an electric dipole located in between parallel mirrors. It appears that the field lines of the Poynting vector (the flow lines of energy) can have very intricate structures, including many singularities and vortices. The flow line patterns depend on the distance between the mirrors, the distance of the dipole to one of the mirrors and the angle of oscillation of the dipole moment with respect to the normal of the mirror surfaces. Already for the simplest case of a dipole moment oscillating perpendicular to the mirrors, singularities appear at regular intervals along the direction of propagation (parallel to the mirrors). For a parallel dipole, vortices appear in the neighbourhood of the dipole. For a dipole oscillating under a finite angle with the surface normal, the radiating tends to swirl around the dipole before travelling off parallel to the mirrors. For relatively large mirror separations, vortices appear in the pattern. When the dipole is off-centred with respect to the midway point between the mirrors, the flow line structure becomes even more complicated, with numerous vortices in the pattern, and tiny loops near the dipole. We have also investigated the locations of the vortices and singularities, and these can be found without any specific knowledge about the flow lines. This provides an independent means of studying the propagation of dipole radiation between mirrors.

Electron acceleration by surface plasma waves in double metal surface structure

Science.gov (United States)

Liu, C. S.; Kumar, Gagan; Singh, D. B.; Tripathi, V. K.

2007-12-01

Two parallel metal sheets, separated by a vacuum region, support a surface plasma wave whose amplitude is maximum on the two parallel interfaces and minimum in the middle. This mode can be excited by a laser using a glass prism. An electron beam launched into the middle region experiences a longitudinal ponderomotive force due to the surface plasma wave and gets accelerated to velocities of the order of phase velocity of the surface wave. The scheme is viable to achieve beams of tens of keV energy. In the case of a surface plasma wave excited on a single metal-vacuum interface, the field gradient normal to the interface pushes the electrons away from the high field region, limiting the acceleration process. The acceleration energy thus achieved is in agreement with the experimental observations.

From Massively Parallel Algorithms and Fluctuating Time Horizons to Nonequilibrium Surface Growth

International Nuclear Information System (INIS)

Korniss, G.; Toroczkai, Z.; Novotny, M. A.; Rikvold, P. A.

2000-01-01

We study the asymptotic scaling properties of a massively parallel algorithm for discrete-event simulations where the discrete events are Poisson arrivals. The evolution of the simulated time horizon is analogous to a nonequilibrium surface. Monte Carlo simulations and a coarse-grained approximation indicate that the macroscopic landscape in the steady state is governed by the Edwards-Wilkinson Hamiltonian. Since the efficiency of the algorithm corresponds to the density of local minima in the associated surface, our results imply that the algorithm is asymptotically scalable. (c) 2000 The American Physical Society

X-ray diffraction study of surface-layer structure in parallel grazing rays

International Nuclear Information System (INIS)

Shtypulyak, N.I.; Yakimov, I.I.; Litvintsev, V.V.

1989-01-01

An x-ray diffraction method is described for study of thin polycrystalline and amorphous films and surface layers in an extremely asymmetrical diffraction system in parallel grazing rays using a DRON-3.0 diffractometer. The minimum grazing angles correspond to diffraction under conditions of total external reflection and a layer depth of ∼ 2.5-8 nm

RPE cell surface proteins in normal and dystrophic rats

International Nuclear Information System (INIS)

Clark, V.M.; Hall, M.O.

1986-01-01

Membrane-bound proteins in plasma membrane enriched fractions from cultured rat RPE were analyzed by two-dimensional gel electrophoresis. Membrane proteins were characterized on three increasingly specific levels. Total protein was visualized by silver staining. A maximum of 102 separate proteins were counted in silver-stained gels. Glycoproteins were labeled with 3H-glucosamine or 3H-fucose and detected by autoradiography. Thirty-eight fucose-labeled and 61-71 glucosamine-labeled proteins were identified. All of the fucose-labeled proteins were labeled with glucosamine-derived radioactivity. Proteins exposed at the cell surface were labeled by lactoperoxidase-catalyzed radioiodination prior to preparation of membranes for two-dimensional analysis. Forty separate 125I-labeled surface proteins were resolved by two-dimensional electrophoresis/autoradiography. Comparison with the glycoprotein map showed that a number of these surface labeled proteins were glycoproteins. Two-dimensional maps of total protein, fucose-labeled, and glucosamine-labeled glycoproteins, and 125I-labeled surface proteins of membranes from dystrophic (RCS rdy-p+) and normal (Long Evans or RCS rdy+p+) RPE were compared. No differences in the total protein or surface-labeled proteins were observed. However, the results suggest that a 183K glycoprotein is more heavily glycosylated with glucosamine and fucose in normal RPE membranes as compared to membranes from dystrophic RPE

Bistatic scattering from a three-dimensional object above a two-dimensional randomly rough surface modeled with the parallel FDTD approach.

Science.gov (United States)

Guo, L-X; Li, J; Zeng, H

2009-11-01

We present an investigation of the electromagnetic scattering from a three-dimensional (3-D) object above a two-dimensional (2-D) randomly rough surface. A Message Passing Interface-based parallel finite-difference time-domain (FDTD) approach is used, and the uniaxial perfectly matched layer (UPML) medium is adopted for truncation of the FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. This makes the parallel FDTD algorithm easier to implement. The parallel performance with different number of processors is illustrated for one rough surface realization and shows that the computation time of our parallel FDTD algorithm is dramatically reduced relative to a single-processor implementation. Finally, the composite scattering coefficients versus scattered and azimuthal angle are presented and analyzed for different conditions, including the surface roughness, the dielectric constants, the polarization, and the size of the 3-D object.

A Case Study of a Hybrid Parallel 3D Surface Rendering Graphics Architecture

DEFF Research Database (Denmark)

Holten-Lund, Hans Erik; Madsen, Jan; Pedersen, Steen

1997-01-01

This paper presents a case study in the design strategy used inbuilding a graphics computer, for drawing very complex 3Dgeometric surfaces. The goal is to build a PC based computer systemcapable of handling surfaces built from about 2 million triangles, andto be able to render a perspective view...... of these on a computer displayat interactive frame rates, i.e. processing around 50 milliontriangles per second. The paper presents a hardware/softwarearchitecture called HPGA (Hybrid Parallel Graphics Architecture) whichis likely to be able to carry out this task. The case study focuses ontechniques to increase...

Parallel Architectures and Parallel Algorithms for Integrated Vision Systems. Ph.D. Thesis

Science.gov (United States)

Choudhary, Alok Nidhi

1989-01-01

Computer vision is regarded as one of the most complex and computationally intensive problems. An integrated vision system (IVS) is a system that uses vision algorithms from all levels of processing to perform for a high level application (e.g., object recognition). An IVS normally involves algorithms from low level, intermediate level, and high level vision. Designing parallel architectures for vision systems is of tremendous interest to researchers. Several issues are addressed in parallel architectures and parallel algorithms for integrated vision systems.

A Screen Space GPGPU Surface LIC Algorithm for Distributed Memory Data Parallel Sort Last Rendering Infrastructures

Energy Technology Data Exchange (ETDEWEB)

Loring, Burlen; Karimabadi, Homa; Rortershteyn, Vadim

2014-07-01

The surface line integral convolution(LIC) visualization technique produces dense visualization of vector fields on arbitrary surfaces. We present a screen space surface LIC algorithm for use in distributed memory data parallel sort last rendering infrastructures. The motivations for our work are to support analysis of datasets that are too large to fit in the main memory of a single computer and compatibility with prevalent parallel scientific visualization tools such as ParaView and VisIt. By working in screen space using OpenGL we can leverage the computational power of GPUs when they are available and run without them when they are not. We address efficiency and performance issues that arise from the transformation of data from physical to screen space by selecting an alternate screen space domain decomposition. We analyze the algorithm's scaling behavior with and without GPUs on two high performance computing systems using data from turbulent plasma simulations.

Body surface area prediction in normal, hypermuscular, and obese mice.

Science.gov (United States)

Cheung, Michael C; Spalding, Paul B; Gutierrez, Juan C; Balkan, Wayne; Namias, Nicholas; Koniaris, Leonidas G; Zimmers, Teresa A

2009-05-15

Accurate determination of body surface area (BSA) in experimental animals is essential for modeling effects of burn injury or drug metabolism. Two-dimensional surface area is related to three-dimensional body volume, which in turn can be estimated from body mass. The Meeh equation relates body surface area to the two-thirds power of body mass, through a constant, k, which must be determined empirically by species and size. We found older values of k overestimated BSA in certain mice; thus we determined empirically k for various strains of normal, obese, and hypermuscular mice. BSA was computed from digitally scanned pelts and nonlinear regression analysis was used to determine the best-fit k. The empirically determined k for C57BL/6J mice of 9.82 was not significantly different from other inbred and outbred mouse strains of normal body composition. However, mean k of the nearly spheroid, obese lepr(db/db) mice (k = 8.29) was significantly lower than for normals, as were values for dumbbell-shaped, hypermuscular mice with either targeted deletion of the myostatin gene (Mstn) (k = 8.48) or with skeletal muscle specific expression of a dominant negative myostatin receptor (Acvr2b) (k = 8.80). Hypermuscular and obese mice differ substantially from normals in shape and density, resulting in considerably altered k values. This suggests Meeh constants should be determined empirically for animals of altered body composition. Use of these new, improved Meeh constants will allow greater accuracy in experimental models of burn injury and pharmacokinetics.

Normal Incidence for Graded Index Surfaces

Science.gov (United States)

Khankhoje, Uday K.; Van Zyl, Jakob

2011-01-01

A plane wave is incident normally from vacuum (eta(sub 0) = 1) onto a smooth surface. The substrate has three layers; the top most layer has thickness d(sub 1) and permittivity epsilon(sub 1). The corresponding numbers for the next layer are d(sub 2); epsilon(sub 2), while the third layer which is semi-in nite has index eta(sub 3). The Hallikainen model [1] is used to relate volumetric soil moisture to the permittivity. Here, we consider the relation for the real part of the permittivity for a typical loam soil: acute epsilon(mv) = 2.8571 + 3.9678 x mv + 118:85 x mv(sup 2).

Message-passing-interface-based parallel FDTD investigation on the EM scattering from a 1-D rough sea surface using uniaxial perfectly matched layer absorbing boundary.

Science.gov (United States)

Li, J; Guo, L-X; Zeng, H; Han, X-B

2009-06-01

A message-passing-interface (MPI)-based parallel finite-difference time-domain (FDTD) algorithm for the electromagnetic scattering from a 1-D randomly rough sea surface is presented. The uniaxial perfectly matched layer (UPML) medium is adopted for truncation of FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. This makes the parallel FDTD algorithm easier to implement. The parallel performance with different processors is illustrated for one sea surface realization, and the computation time of the parallel FDTD algorithm is dramatically reduced compared to a single-process implementation. Finally, some numerical results are shown, including the backscattering characteristics of sea surface for different polarization and the bistatic scattering from a sea surface with large incident angle and large wind speed.

GPU Parallel Bundle Block Adjustment

Directory of Open Access Journals (Sweden)

ZHENG Maoteng

2017-09-01

Full Text Available To deal with massive data in photogrammetry, we introduce the GPU parallel computing technology. The preconditioned conjugate gradient and inexact Newton method are also applied to decrease the iteration times while solving the normal equation. A brand new workflow of bundle adjustment is developed to utilize GPU parallel computing technology. Our method can avoid the storage and inversion of the big normal matrix, and compute the normal matrix in real time. The proposed method can not only largely decrease the memory requirement of normal matrix, but also largely improve the efficiency of bundle adjustment. It also achieves the same accuracy as the conventional method. Preliminary experiment results show that the bundle adjustment of a dataset with about 4500 images and 9 million image points can be done in only 1.5 minutes while achieving sub-pixel accuracy.

An Algorithm for Parallel Sn Sweeps on Unstructured Meshes

International Nuclear Information System (INIS)

Pautz, Shawn D.

2002-01-01

A new algorithm for performing parallel S n sweeps on unstructured meshes is developed. The algorithm uses a low-complexity list ordering heuristic to determine a sweep ordering on any partitioned mesh. For typical problems and with 'normal' mesh partitionings, nearly linear speedups on up to 126 processors are observed. This is an important and desirable result, since although analyses of structured meshes indicate that parallel sweeps will not scale with normal partitioning approaches, no severe asymptotic degradation in the parallel efficiency is observed with modest (≤100) levels of parallelism. This result is a fundamental step in the development of efficient parallel S n methods

Detachment of polystyrene particles from collector surfaces by surface tension forces induced by air-bubble passage through a parallel plate flow chamber

NARCIS (Netherlands)

Wit, PJ; vanderMei, HC; Busscher, HJ

1997-01-01

By allowing an air-bubble to pass through a parallel plate flow chamber with negatively charged, colloidal polystyrene particles adhering to the bottom collector plate of the chamber, the detachment of adhering particles stimulated by surface tension forces induced by the passage of a liquid-air

X-ray diffractometric study on the near-surface layer structure in parallel glancing rays

International Nuclear Information System (INIS)

Shtypulyak, N.I.; Yakimov, I.I.; Litvintsev, V.V.

1988-01-01

X-ray diffraction method is suggested to use to investigate thin films and near-surface layers under the conditions of total external reflection (TER) and in the geometry of parallel glancing rays. Experimental realization of the method using the DRON-30 diffractometer is described. Calculation for the required width of the aperture of Soller slot system is presented. The described diffraction scheme is used to investigate thin film crystal structure at glancing angles in the range from TER up to 8-10 deg. The thickness of the investigated layer in this case changes from 2.5-8 nm up to 10 3 nm. The suggested diffraction method in parallel glancing rays is especially important when investigating the films with thickness lower than 1000-2000A

Anti-parallel polarization switching in a triglycine sulfate organic ferroelectric insulator: The role of surface charges

Science.gov (United States)

Ma, He; Wu, Zhuangchun; Peng, Dongwen; Wang, Yaojin; Wang, Yiping; Yang, Ying; Yuan, Guoliang

2018-04-01

Four consecutive ferroelectric polarization switchings and an abnormal ring-like domain pattern can be introduced by a single tip bias of a piezoresponse force microscope in the (010) triglycine sulfate (TGS) crystal. The external electric field anti-parallel to the original polarization induces the first polarization switching; however, the surface charges of TGS can move toward the tip location and induce the second polarization switching once the tip bias is removed. The two switchings allow a ring-like pattern composed of the central domain with downward polarization and the outer domain with upward polarization. Once the two domains disappear gradually as a result of depolarization, the other two polarization switchings occur one by one at the TGS where the tip contacts. However, the backswitching phenomenon does not occur when the external electric field is parallel to the original polarization. These results can be explained according to the surface charges instead of the charges injected inside.

Crossover from normal (N) Ohmic subdivision to superconducting (S) equipartition of current in parallel conductors at the N-S transition: Theory

OpenAIRE

Kumar, N.

2007-01-01

The recently observed (1) equipartition of current in parallel at and below the Normal-Superconducting (N-S) transition can be understood in terms of a Landau-Ginzburg order-parameter phenomenology. This complements the explanation proposed earlier (1) based on the flux-flow resistance providing a nonlinear negative current feedback towards equipartition when the transition is approached from above. The present treatment also unifies the usual textbook inductive subdivision expected much belo...

Selecting the induction heating for normalization of deposited surfaces of cylindrical parts

Directory of Open Access Journals (Sweden)

Олена Валеріївна Бережна

2017-07-01

Full Text Available The machine parts recovered by electric contact surfacing with metal strip are characterized by high loading of the surface layer, which has a significant impact on their performance. Therefore, the improvement of the operational stability of fast-wearing machine parts through the use of combined treatment technologies is required. Not all the work-piece but just the worn zones are subjected to recovery with electric contact surfacing; the tape thickness and depth of the heat affected zone being not more than a few millimeters. Therefore, the most optimal in this case is the use of a local surface heating method of high frequency currents. This method has economical benefits because there is no need to heat the entire work-piece. The induction heating mode at a constant power density has been proposed and analytically investigated. The ratios that make it possible to determine the main heating parameters ensuring calculation of the inductor for the normalization of the reconstructed surface of cylindrical parts have been given. These parameters are: specific power, frequency and warm-up time. The proposed induction heating mode is intermediate between the quenching and cross-cutting heating and makes it possible to simultaneously obtain the required temperatures at the surface and at the predetermined depth of the heated layer of cylindrical parts with the normalization of their surfaces restored with electric contact surfacing

Log-Normality and Multifractal Analysis of Flame Surface Statistics

Science.gov (United States)

Saha, Abhishek; Chaudhuri, Swetaprovo; Law, Chung K.

2013-11-01

The turbulent flame surface is typically highly wrinkled and folded at a multitude of scales controlled by various flame properties. It is useful if the information contained in this complex geometry can be projected onto a simpler regular geometry for the use of spectral, wavelet or multifractal analyses. Here we investigate local flame surface statistics of turbulent flame expanding under constant pressure. First the statistics of local length ratio is experimentally obtained from high-speed Mie scattering images. For spherically expanding flame, length ratio on the measurement plane, at predefined equiangular sectors is defined as the ratio of the actual flame length to the length of a circular-arc of radius equal to the average radius of the flame. Assuming isotropic distribution of such flame segments we convolute suitable forms of the length-ratio probability distribution functions (pdfs) to arrive at corresponding area-ratio pdfs. Both the pdfs are found to be near log-normally distributed and shows self-similar behavior with increasing radius. Near log-normality and rather intermittent behavior of the flame-length ratio suggests similarity with dissipation rate quantities which stimulates multifractal analysis. Currently at Indian Institute of Science, India.

Precise on-machine extraction of the surface normal vector using an eddy current sensor array

International Nuclear Information System (INIS)

Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun

2016-01-01

To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces. (paper)

Precise on-machine extraction of the surface normal vector using an eddy current sensor array

Science.gov (United States)

Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun

2016-11-01

To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces.

Asymptotic Normality of the Optimal Solution in Multiresponse Surface Mathematical Programming

OpenAIRE

Díaz-García, José A.; Caro-Lopera, Francisco J.

2015-01-01

An explicit form for the perturbation effect on the matrix of regression coeffi- cients on the optimal solution in multiresponse surface methodology is obtained in this paper. Then, the sensitivity analysis of the optimal solution is studied and the critical point characterisation of the convex program, associated with the optimum of a multiresponse surface, is also analysed. Finally, the asymptotic normality of the optimal solution is derived by the standard methods.

Improved Topographic Normalization for Landsat TM Images by Introducing the MODIS Surface BRDF

Directory of Open Access Journals (Sweden)

Yanli Zhang

2015-05-01

Full Text Available In rugged terrain, the accuracy of surface reflectance estimations is compromised by atmospheric and topographic effects. We propose a new method to simultaneously eliminate atmospheric and terrain effects in Landsat Thematic Mapper (TM images based on a 30 m digital elevation model (DEM and Moderate Resolution Imaging Spectroradiometer (MODIS atmospheric products. Moreover, we define a normalized factor of a Bidirectional Reflectance Distribution Function (BRDF to convert the sloping pixel reflectance into a flat pixel reflectance by using the Ross Thick-Li Sparse BRDF model (Ambrals algorithm and MODIS BRDF/albedo kernel coefficient products. Sole atmospheric correction and topographic normalization were performed for TM images in the upper stream of the Heihe River Basin. The results show that using MODIS atmospheric products can effectively remove atmospheric effects compared with the Fast Line-of-Sight Atmospheric Analysis of Spectral Hypercubes (FLAASH model and the Landsat Climate Data Record (CDR. Moreover, superior topographic effect removal can be achieved by considering the surface BRDF when compared with the surface Lambertian assumption of topographic normalization.

Study of MPI based on parallel MOM on PC clusters for EM-beam scattering by 2-D PEC rough surfaces

International Nuclear Information System (INIS)

Jun, Ma; Li-Xin, Guo; An-Qi, Wang

2009-01-01

This paper firstly applies the finite impulse response filter (FIR) theory combined with the fast Fourier transform (FFT) method to generate two-dimensional Gaussian rough surface. Using the electric field integral equation (EFIE), it introduces the method of moment (MOM) with RWG vector basis function and Galerkin's method to investigate the electromagnetic beam scattering by a two-dimensional PEC Gaussian rough surface on personal computer (PC) clusters. The details of the parallel conjugate gradient method (CGM) for solving the matrix equation are also presented and the numerical simulations are obtained through the message passing interface (MPI) platform on the PC clusters. It finds significantly that the parallel MOM supplies a novel technique for solving a two-dimensional rough surface electromagnetic-scattering problem. The influences of the root-mean-square height, the correlation length and the polarization on the beam scattering characteristics by two-dimensional PEC Gaussian rough surfaces are finally discussed. (classical areas of phenomenology)

Surface energy and surface stress on vicinals by revisiting the Shuttleworth relation

Science.gov (United States)

Hecquet, Pascal

2018-04-01

In 1998 [Surf. Sci. 412/413, 639 (1998)], we showed that the step stress on vicinals varies as 1/L, L being the distance between steps, while the inter-step interaction energy primarily follows the law as 1/L2 from the well-known Marchenko-Parshin model. In this paper, we give a better understanding of the interaction term of the step stress. The step stress is calculated with respect to the nominal surface stress. Consequently, we calculate the diagonal surface stresses in both the vicinal system (x, y, z) where z is normal to the vicinal and the projected system (x, b, c) where b is normal to the nominal terrace. Moreover, we calculate the surface stresses by using two methods: the first called the 'Zero' method, from the surface pressure forces and the second called the 'One' method, by homogeneously deforming the vicinal in the parallel direction, x or y, and by calculating the surface energy excess proportional to the deformation. By using the 'One' method on the vicinal Cu(0 1 M), we find that the step deformations, due to the applied deformation, vary as 1/L by the same factor for the tensor directions bb and cb, and by twice the same factor for the parallel direction yy. Due to the vanishing of the surface stress normal to the vicinal, the variation of the step stress in the direction yy is better described by using only the step deformation in the same direction. We revisit the Shuttleworth formula, for while the variation of the step stress in the direction xx is the same between the two methods, the variation in the direction yy is higher by 76% for the 'Zero' method with respect to the 'One' method. In addition to the step energy, we confirm that the variation of the step stress must be taken into account for the understanding of the equilibrium of vicinals when they are not deformed.

Normal Contacts of Lubricated Fractal Rough Surfaces at the Atomic Scale

NARCIS (Netherlands)

Solhjoo, Soheil; Vakis, Antonis I.

The friction of contacting interfaces is a function of surface roughness and applied normal load. Under boundary lubrication, this frictional behavior changes as a function of lubricant wettability, viscosity, and density, by practically decreasing the possibility of dry contact. Many studies on

Near surface silicide formation after off-normal Fe-implantation of Si(001) surfaces

Energy Technology Data Exchange (ETDEWEB)

Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de; Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Lützenkirchen-Hecht, D. [Fachbereich C - Physik, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Hübner, R.; Grenzer, J.; Facsko, S. [Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany)

2014-07-14

We report on formation of non-crystalline Fe-silicides of various stoichiometries below the amorphized surface of crystalline Si(001) after irradiation with 5 keV Fe{sup +} ions under off-normal incidence. We examined samples prepared with ion fluences of 0.1 × 10{sup 17} and 5 × 10{sup 17} ions cm{sup −2} exhibiting a flat and patterned surface morphology, respectively. Whereas the iron silicides are found across the whole surface of the flat sample, they are concentrated at the top of ridges at the rippled surface. A depth resolved analysis of the chemical states of Si and Fe atoms in the near surface region was performed by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) using synchrotron radiation. The chemical shift and the line shape of the Si 2p core levels and valence bands were measured and associated with the formation of silicide bonds of different stoichiometric composition changing from an Fe-rich silicides (Fe{sub 3}Si) close to the surface into a Si-rich silicide (FeSi{sub 2}) towards the inner interface to the Si(001) substrate. This finding is supported by XAS analysis at the Fe K-edge which shows changes of the chemical environment and the near order atomic coordination of the Fe atoms in the region close to surface. Because a similar Fe depth profile has been found for samples co-sputtered with Fe during Kr{sup +} ion irradiation, our results suggest the importance of chemically bonded Fe in the surface region for the process of ripple formation.

General Rotational Surfaces in Pseudo-Euclidean 4-Space with Neutral Metric

OpenAIRE

Aleksieva, Yana; Milousheva, Velichka; Turgay, Nurettin Cenk

2016-01-01

We define general rotational surfaces of elliptic and hyperbolic type in the pseudo-Euclidean 4-space with neutral metric which are analogous to the general rotational surfaces of C. Moore in the Euclidean 4-space. We study Lorentz general rotational surfaces with plane meridian curves and give the complete classification of minimal general rotational surfaces of elliptic and hyperbolic type, general rotational surfaces with parallel normalized mean curvature vector field, flat general rotati...

Cell-surface glycoproteins of human sarcomas: differential expression in normal and malignant tissues and cultured cells

International Nuclear Information System (INIS)

Rettig, W.F.; Garin-Chesa, P.; Beresford, H.R.; Oettgen, H.F.; Melamed, M.R.; Old, L.J.

1988-01-01

Normal differentiation and malignant transformation of human cells are characterized by specific changes in surface antigen phenotype. In the present study, the authors have defined six cell-surface antigens of human sarcomas and normal mesenchymal cells, by using mixed hemadsorption assays and immunochemical methods for the analysis of cultured cells and immunohistochemical staining for the analysis of normal tissues and > 200 tumor specimens. Differential patterns of F19, F24, G171, G253, S5, and Thy-1 antigen expression were found to characterize (i) subsets of cultured sarcoma cell lines, (ii) cultured fibroblasts derived from various organs, (iii) normal resting and activated mesenchymal tissues, and (iv) sarcoma and nonmesenchymal tumor tissues. These results provide a basic surface antigenic map for cultured mesenchymal cells and mesenchymal tissues and permit the classification of human sarcomas according to their antigenic phenotypes

Empirical valence bond models for reactive potential energy surfaces: a parallel multilevel genetic program approach.

Science.gov (United States)

Bellucci, Michael A; Coker, David F

2011-07-28

We describe a new method for constructing empirical valence bond potential energy surfaces using a parallel multilevel genetic program (PMLGP). Genetic programs can be used to perform an efficient search through function space and parameter space to find the best functions and sets of parameters that fit energies obtained by ab initio electronic structure calculations. Building on the traditional genetic program approach, the PMLGP utilizes a hierarchy of genetic programming on two different levels. The lower level genetic programs are used to optimize coevolving populations in parallel while the higher level genetic program (HLGP) is used to optimize the genetic operator probabilities of the lower level genetic programs. The HLGP allows the algorithm to dynamically learn the mutation or combination of mutations that most effectively increase the fitness of the populations, causing a significant increase in the algorithm's accuracy and efficiency. The algorithm's accuracy and efficiency is tested against a standard parallel genetic program with a variety of one-dimensional test cases. Subsequently, the PMLGP is utilized to obtain an accurate empirical valence bond model for proton transfer in 3-hydroxy-gamma-pyrone in gas phase and protic solvent. © 2011 American Institute of Physics

Renal function maturation in children: is normalization to surface area valid?

International Nuclear Information System (INIS)

Rutland, M.D.; Hassan, I.M.; Que, L.

1999-01-01

Full text: Gamma camera DTPA renograms were analysed to measure renal function by the rate at which the kidneys took up tracer from the blood. This was expressed either directly as the fractional uptake rate (FUR), which is not related to body size, or it was converted to a camera-based GFR by the formula GFR blood volume x FUR, and this GFR was normalized to a body surface area of 1.73 m2. Most of the patients studied had one completely normal kidney, and one kidney with reflux but normal function and no large scars. The completely normal kidneys contributed, on average, 50% of the total renal function. The results were considered in age bands, to display the effect of age on renal function. The camera-GFR measurements showed the conventional results of poor renal function in early childhood, with a slow rise to near-adult values by the age of 2 years, and somewhat low values throughout childhood. The uptake values showed a different pattern, with renal function rising to adult equivalent values by the age of 4 months, and with children having better renal function than adults throughout most of their childhood. The standard deviations expressed as coefficients of variation (CV) were smaller for the FUR technique than the GFR (Wilcoxon rank test, P < 0.01). These results resemble recent published measurements of absolute DMSA uptake, which are also unrelated to body size and show early renal maturation. The results also suggest that the reason children have lower serum creatinine levels than adults is that they have better renal function. If this were confirmed, it would raise doubts about the usefulness of normalizing renal function to body surface area in children

Determination of Optimum Viewing Angles for the Angular Normalization of Land Surface Temperature over Vegetated Surface

Directory of Open Access Journals (Sweden)

Huazhong Ren

2015-03-01

Full Text Available Multi-angular observation of land surface thermal radiation is considered to be a promising method of performing the angular normalization of land surface temperature (LST retrieved from remote sensing data. This paper focuses on an investigation of the minimum requirements of viewing angles to perform such normalizations on LST. The normally kernel-driven bi-directional reflectance distribution function (BRDF is first extended to the thermal infrared (TIR domain as TIR-BRDF model, and its uncertainty is shown to be less than 0.3 K when used to fit the hemispheric directional thermal radiation. A local optimum three-angle combination is found and verified using the TIR-BRDF model based on two patterns: the single-point pattern and the linear-array pattern. The TIR-BRDF is applied to an airborne multi-angular dataset to retrieve LST at nadir (Te-nadir from different viewing directions, and the results show that this model can obtain reliable Te-nadir from 3 to 4 directional observations with large angle intervals, thus corresponding to large temperature angular variations. The Te-nadir is generally larger than temperature of the slant direction, with a difference of approximately 0.5~2.0 K for vegetated pixels and up to several Kelvins for non-vegetated pixels. The findings of this paper will facilitate the future development of multi-angular thermal infrared sensors.

A vibrating wire parallel to a high temperature superconducting slab. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

Saif, A G; El-sabagh, M A [Department of Mathematic and Theoretical physics, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)

1996-03-01

The power losses problem for an idealized high temperature type II superconducting system of a simple geometry is studied. This system is composed of a vibrating normal conducting wire (two wires) carrying a direct current parallel to an uniaxial anisotropic type II superconducting slab (moving slab). First, the electromagnetic equation governing the dynamics of this system, and its solutions are obtained. Secondly, a modified anisotropic london equation is developed to study these systems in the case of the slab moving. Thirdly, it is found that, the power losses is dependent on the frequency, london penetration depth, permeability, conductivity, velocity, and the distance between the normal conductors and the surfaces of the superconducting slab. Moreover, the power losses decreases as the distance between the normal conductors and the surface of the superconducting slab decreases; and increases as the frequency, the london penetration depth, permeability, conductivity, and velocity are increased. These losses along the versor of the anisotropy axis is increased as {lambda}{sub |}| increases. Moreover, it is greater than the power losses along the crystal symmetry direction. In the isotropic case as well as the slab thickness tends to infinity, agreement with previous results are obtained. 2 figs.

Solving very large scattering problems using a parallel PWTD-enhanced surface integral equation solver

KAUST Repository

Liu, Yang

2013-07-01

The computational complexity and memory requirements of multilevel plane wave time domain (PWTD)-accelerated marching-on-in-time (MOT)-based surface integral equation (SIE) solvers scale as O(NtNs(log 2)Ns) and O(Ns 1.5); here N t and Ns denote numbers of temporal and spatial basis functions discretizing the current [Shanker et al., IEEE Trans. Antennas Propag., 51, 628-641, 2003]. In the past, serial versions of these solvers have been successfully applied to the analysis of scattering from perfect electrically conducting as well as homogeneous penetrable targets involving up to Ns ≈ 0.5 × 106 and Nt ≈ 10 3. To solve larger problems, parallel PWTD-enhanced MOT solvers are called for. Even though a simple parallelization strategy was demonstrated in the context of electromagnetic compatibility analysis [M. Lu et al., in Proc. IEEE Int. Symp. AP-S, 4, 4212-4215, 2004], by and large, progress in this area has been slow. The lack of progress can be attributed wholesale to difficulties associated with the construction of a scalable PWTD kernel. © 2013 IEEE.

About the geometry of the Earth geodetic reference surfaces

Science.gov (United States)

Husár, Ladislav; Švaral, Peter; Janák, Juraj

2017-10-01

The paper focuses on the comparison of metrics of three most common reference surfaces of the Earth used in geodesy (excluding the plane which also belongs to reference surfaces used in geodesy when dealing with small areas): a sphere, an ellipsoid of revolution and a triaxial ellipsoid. The two latter surfaces are treated in a more detailed way. First, the mathematical form of the metric tensors using three types of coordinates is derived and the lengths of meridian and parallel arcs between the two types of ellipsoids are compared. Three kinds of parallels, according to the type of latitude, can be defined on a triaxial ellipsoid. We show that two types of parallels are spatial curves and one is represented by ellipses. The differences of curvature of both kinds of ellipsoid are analysed using the normal curvature radii. Priority of the chosen triaxial ellipsoid is documented by its better fit with respect to the high-degree geoid model EIGEN6c4 computed up to degree and order 2160.

Investigation of a cable-driven parallel mechanism for interaction with a variety of surface, applied to the cleaning of free-form buildings

NARCIS (Netherlands)

Voss, K.H.J.; van der Wijk, V.; Herder, Justus Laurens; Lenarcic, Jadran; Husty, Manfred

2012-01-01

In this paper, the capability of a specific cable-driven parallel mechanism to interact with a variety of surfaces is investigated. This capability could be of use in for example the cleaning of large building surfaces. A method is presented to investigate the workspace for which the cables do not

Air bubble-induced detachment of polystyrene particles with different sizes from collector surfaces in a parallel plate flow chamber

NARCIS (Netherlands)

Gomez-Suarez, C; van der Mei, HC; Busscher, HJ

2001-01-01

Particle size was found to be an important factor in air bubble-induced detachment of colloidal particles from collector surfaces in a parallel plate flow chamber and generally polystyrene particles with a diameter of 806 nm detached less than particles with a diameter of 1400 nm. Particle

A detailed chemistry model for transient hydrogen and carbon monoxide catalytic recombination on parallel flat Pt surfaces implemented in an integral code

International Nuclear Information System (INIS)

Jimenez, Miguel A.; Martin-Valdepenas, Juan M.; Martin-Fuertes, Francisco; Fernandez, Jose A.

2007-01-01

A detailed chemistry model has been adapted and developed for surface chemistry, heat and mass transfer between H 2 /CO/air/steam/CO 2 mixtures and vertical parallel Pt-coated surfaces. This model is based onto a simplified Deutschmann reaction scheme for methane surface combustion and the analysis by Elenbaas for buoyancy-induced heat transfer between parallel plates. Mass transfer is treated by the heat and mass transfer analogy. The proposed model is able to simulate the H 2 /CO recombination phenomena characteristic of parallel-plate Passive Autocatalytic Recombiners (PARs), which have been proposed and implemented as a promising hydrogen-control strategy in the safety of nuclear power stations or other industries. The transient model is able to approach the warm-up phase of the PAR and its shut-down as well as the dynamic changes within the surrounding atmosphere. The model has been implemented within the MELCOR code and assessed against results of the Battelle Model Containment tests of the Zx series. Results show accurate predictions and a better performance than traditional methods in integral codes, i.e. empirical correlations, which are also much case-specific. Influence of CO present in the mixture on the PAR performance is also addressed in this paper

Dynamics of an optically confined nanoparticle diffusing normal to a surface.

Science.gov (United States)

Schein, Perry; O'Dell, Dakota; Erickson, David

2016-06-01

Here we measure the hindered diffusion of an optically confined nanoparticle in the direction normal to a surface, and we use this to determine the particle-surface interaction profile in terms of the absolute height. These studies are performed using the evanescent field of an optically excited single-mode silicon nitride waveguide, where the particle is confined in a height-dependent potential energy well generated from the balance of optical gradient and surface forces. Using a high-speed cmos camera, we demonstrate the ability to capture the short time-scale diffusion dominated motion for 800-nm-diam polystyrene particles, with measurement times of only a few seconds per particle. Using established theory, we show how this information can be used to estimate the equilibrium separation of the particle from the surface. As this measurement can be made simultaneously with equilibrium statistical mechanical measurements of the particle-surface interaction energy landscape, we demonstrate the ability to determine these in terms of the absolute rather than relative separation height. This enables the comparison of potential energy landscapes of particle-surface interactions measured under different experimental conditions, enhancing the utility of this technique.

Surface Casimir densities and induced cosmological constant on parallel branes in AdS spacetime

International Nuclear Information System (INIS)

Saharian, Aram A.

2004-01-01

Vacuum expectation value of the surface energy-momentum tensor is evaluated for a massive scalar field with general curvature coupling parameter subject to Robin boundary conditions on two parallel branes located on (D+1)-dimensional anti-de Sitter bulk. The general case of different Robin coefficients on separate branes is considered. As a regularization procedure the generalized zeta function technique is used, in combination with contour integral representations. The surface energies on the branes are presented in the form of the sums of single brane and second brane-induced parts. For the geometry of a single brane both regions, on the left (L-region) and on the right (R-region), of the brane are considered. The surface densities for separate L- and R-regions contain pole and finite contributions. For an infinitely thin brane taking these regions together, in odd spatial dimensions the pole parts cancel and the total surface energy is finite. The parts in the surface densities generated by the presence of the second brane are finite for all nonzero values of the interbrane separation. It is shown that for large distances between the branes the induced surface densities give rise to an exponentially suppressed cosmological constant on the brane. In the Randall-Sundrum braneworld model, for the interbrane distances solving the hierarchy problem between the gravitational and electroweak mass scales, the cosmological constant generated on the visible brane is of the right order of magnitude with the value suggested by the cosmological observations

Parallel paving: An algorithm for generating distributed, adaptive, all-quadrilateral meshes on parallel computers

Energy Technology Data Exchange (ETDEWEB)

Lober, R.R.; Tautges, T.J.; Vaughan, C.T.

1997-03-01

Paving is an automated mesh generation algorithm which produces all-quadrilateral elements. It can additionally generate these elements in varying sizes such that the resulting mesh adapts to a function distribution, such as an error function. While powerful, conventional paving is a very serial algorithm in its operation. Parallel paving is the extension of serial paving into parallel environments to perform the same meshing functions as conventional paving only on distributed, discretized models. This extension allows large, adaptive, parallel finite element simulations to take advantage of paving`s meshing capabilities for h-remap remeshing. A significantly modified version of the CUBIT mesh generation code has been developed to host the parallel paving algorithm and demonstrate its capabilities on both two dimensional and three dimensional surface geometries and compare the resulting parallel produced meshes to conventionally paved meshes for mesh quality and algorithm performance. Sandia`s {open_quotes}tiling{close_quotes} dynamic load balancing code has also been extended to work with the paving algorithm to retain parallel efficiency as subdomains undergo iterative mesh refinement.

Friction of hydrogels with controlled surface roughness on solid flat substrates.

Science.gov (United States)

Yashima, Shintaro; Takase, Natsuko; Kurokawa, Takayuki; Gong, Jian Ping

2014-05-14

This study investigated the effect of hydrogel surface roughness on its sliding friction against a solid substrate having modestly adhesive interaction with hydrogels under small normal pressure in water. The friction test was performed between bulk polyacrylamide hydrogels of varied surface roughness and a smooth glass substrate by using a strain-controlled rheometer with parallel-plates geometry. At small pressure (normal strain 1.4-3.6%), the flat surface gel showed a poor reproducibility in friction. In contrast, the gels with a surface roughness of 1-10 μm order showed well reproducible friction behaviors and their frictional stress was larger than that of the flat surface hydrogel. Furthermore, the flat gel showed an elasto-hydrodynamic transition while the rough gels showed a monotonous decrease of friction with velocity. The difference between the flat surface and the rough surface diminished with the increase of the normal pressure. These phenomena are associated with the different contact behaviors of these soft hydrogels in liquid, as revealed by the observation of the interface using a confocal laser microscope.

Comparison of waxy and normal potato starch remaining granules after chemical surface gelatinization: Pasting behavior and surface morphology

NARCIS (Netherlands)

Huang, J.; Chen Zenghong,; Xu, Yalun; Li, Hongliang; Liu, Shuxing; Yang, Daqing; Schols, H.A.

2014-01-01

o understand the contribution of granule inner portion to the pasting property of starch, waxy potato starch and two normal potato starches and their acetylated starch samples were subjected to chemical surface gelatinization by 3.8 mol/L CaCl2 to obtain remaining granules. Native and acetylated,

Air bubble-induced detachment of positively and negatively charged polystyrene particles from collector surfaces in a parallel-plate flow chamber

NARCIS (Netherlands)

Gomez-Suarez, C; Van der Mei, HC; Busscher, HJ

2000-01-01

Electrostatic interactions between colloidal particles and collector surfaces were found tcr be important in particle detachment as induced by the passage of air bubbles in a parallel-plate Row chamber. Electrostatic interactions between adhering particles and passing air bubbles, however, a-ere

Internal structure of normal maize starch granules revealed by chemical surface gelatinization.

Science.gov (United States)

Pan, D D; Jane, J I

2000-01-01

Normal maize starch was fractionated into two sizes: large granules with diameters more than 5 microns and small granules with diameters less than 5 microns. The large granules were surface gelatinized by treating them with an aqueous LiCl solution (13 M) at 22-23 degrees C. Surface-gelatinized remaining granules were obtained by mechanical blending, and gelatinized surface starch was obtained by grinding with a mortar and a pestle. Starches of different granular sizes and radial locations, obtained after different degrees of surface gelatinization, were subjected to scanning electron microscopy, iodine potentiometric titration, gel-permeation chromatography, and amylopectin branch chain length analysis. Results showed that the remaining granules had a rough surface with a lamella structure. Amylose was more concentrated at the periphery than at the core of the granule. Amylopectin had longer long B-chains at the core than at the periphery of the granule. Greater proportions of the long B-chains were present at the core than at the periphery of the granule.

Electron transfer in gas surface collisions

International Nuclear Information System (INIS)

Wunnik, J.N.M. van.

1983-01-01

In this thesis electron transfer between atoms and metal surfaces in general is discussed and the negative ionization of hydrogen by scattering protons at a cesiated crystalline tungsten (110) surface in particular. Experimental results and a novel theoretical analysis are presented. In Chapter I a theoretical overview of resonant electron transitions between atoms and metals is given. In the first part of chapter II atom-metal electron transitions at a fixed atom-metal distance are described on the basis of a model developed by Gadzuk. In the second part the influence of the motion of the atom on the atomic charge state is incorporated. Measurements presented in chapter III show a strong dependence of the fraction of negatively charged H atoms scattered at cesiated tungsten, on the normal as well as the parallel velocity component. In chapter IV the proposed mechanism for the parallel velocity effect is incorporated in the amplitude method. The scattering process of protons incident under grazing angles on a cesium covered surface is studied in chapter V. (Auth.)

Continuum modeling of ion-beam eroded surfaces under normal incidence: Impact of stochastic fluctuations

International Nuclear Information System (INIS)

Dreimann, Karsten; Linz, Stefan J.

2010-01-01

Graphical abstract: Deterministic surface pattern (left) and its stochastic counterpart (right) arising in a stochastic damped Kuramoto-Sivashinsky equation that serves as a model equation for ion-beam eroded surfaces and is systematically investigated. - Abstract: Using a recently proposed field equation for the surface evolution of ion-beam eroded semiconductor target materials under normal incidence, we systematically explore the impact of additive stochastic fluctuations that are permanently present during the erosion process. Specifically, we investigate the dependence of the surface roughness, the underlying pattern forming properties and the bifurcation behavior on the strength of the fluctuations.

Parallelization of the FLAPW method

International Nuclear Information System (INIS)

Canning, A.; Mannstadt, W.; Freeman, A.J.

1999-01-01

The FLAPW (full-potential linearized-augmented plane-wave) method is one of the most accurate first-principles methods for determining electronic and magnetic properties of crystals and surfaces. Until the present work, the FLAPW method has been limited to systems of less than about one hundred atoms due to a lack of an efficient parallel implementation to exploit the power and memory of parallel computers. In this work we present an efficient parallelization of the method by division among the processors of the plane-wave components for each state. The code is also optimized for RISC (reduced instruction set computer) architectures, such as those found on most parallel computers, making full use of BLAS (basic linear algebra subprograms) wherever possible. Scaling results are presented for systems of up to 686 silicon atoms and 343 palladium atoms per unit cell, running on up to 512 processors on a CRAY T3E parallel computer

Parallelization of the FLAPW method

Science.gov (United States)

Canning, A.; Mannstadt, W.; Freeman, A. J.

2000-08-01

The FLAPW (full-potential linearized-augmented plane-wave) method is one of the most accurate first-principles methods for determining structural, electronic and magnetic properties of crystals and surfaces. Until the present work, the FLAPW method has been limited to systems of less than about a hundred atoms due to the lack of an efficient parallel implementation to exploit the power and memory of parallel computers. In this work, we present an efficient parallelization of the method by division among the processors of the plane-wave components for each state. The code is also optimized for RISC (reduced instruction set computer) architectures, such as those found on most parallel computers, making full use of BLAS (basic linear algebra subprograms) wherever possible. Scaling results are presented for systems of up to 686 silicon atoms and 343 palladium atoms per unit cell, running on up to 512 processors on a CRAY T3E parallel supercomputer.

Surface spectra of Weyl semimetals through self-adjoint extensions

Science.gov (United States)

Seradjeh, Babak; Vennettilli, Michael

2018-02-01

We apply the method of self-adjoint extensions of Hermitian operators to the low-energy, continuum Hamiltonians of Weyl semimetals in bounded geometries and derive the spectrum of the surface states on the boundary. This allows for the full characterization of boundary conditions and the surface spectra on surfaces both normal to the Weyl node separation as well as parallel to it. We show that the boundary conditions for quadratic bulk dispersions are, in general, specified by a U (2 ) matrix relating the wave function and its derivatives normal to the surface. We give a general procedure to obtain the surface spectra from these boundary conditions and derive them in specific cases of bulk dispersion. We consider the role of global symmetries in the boundary conditions and their effect on the surface spectrum. We point out several interesting features of the surface spectra for different choices of boundary conditions, such as a Mexican-hat shaped dispersion on the surface normal to Weyl node separation. We find that the existence of bound states, Fermi arcs, and the shape of their dispersion, depend on the choice of boundary conditions. This illustrates the importance of the physics at and near the boundaries in the general statement of bulk-boundary correspondence.

Transmission line theory for long plasma production by radio frequency discharges between parallel-plate electrodes

International Nuclear Information System (INIS)

Nonaka, S.

1991-01-01

In order to seek for a radio frequency (RF) eigen-mode of waves in producing a plasma between a pair of long dielectric-covered parallel-plate RF electrodes, this paper analyzed all normal modes propagating along the electrodes by solving Maxwell's equations. The result showed that only an odd surface wave mode will produce the plasma in usual experimental conditions, which will become a basic transmission line theory when use of such long electrodes for on-line mass-production of amorphous silicon solar cells

Growth of contact area between rough surfaces under normal stress

Science.gov (United States)

Stesky, R. M.; Hannan, S. S.

1987-05-01

The contact area between deforming rough surfaces in marble, alabaster, and quartz was measured from thin sections of surfaces bonded under load with low viscosity resin epoxy. The marble and alabaster samples had contact areas that increased with stress at an accelerating rate. This result suggests that the strength of the asperity contacts decreased progressively during the deformation, following some form of strain weakening relationship. This conclusion is supported by petrographic observation of the thin sections that indicate that much of the deformation was cataclastic, with minor twinning of calcite and kinking of gypsum. In the case of the quartz, the observed contact area was small and increased approximately linearly with normal stress. Only the irreversible cataclastic deformation was observed; however strain-induced birefringence and cracking of the epoxy, not observed with the other rocks, suggests that significant elastic deformation occurred, but recovered during unloading.

Fast Edge Detection and Segmentation of Terrestrial Laser Scans Through Normal Variation Analysis

Science.gov (United States)

Che, E.; Olsen, M. J.

2017-09-01

Terrestrial Laser Scanning (TLS) utilizes light detection and ranging (lidar) to effectively and efficiently acquire point cloud data for a wide variety of applications. Segmentation is a common procedure of post-processing to group the point cloud into a number of clusters to simplify the data for the sequential modelling and analysis needed for most applications. This paper presents a novel method to rapidly segment TLS data based on edge detection and region growing. First, by computing the projected incidence angles and performing the normal variation analysis, the silhouette edges and intersection edges are separated from the smooth surfaces. Then a modified region growing algorithm groups the points lying on the same smooth surface. The proposed method efficiently exploits the gridded scan pattern utilized during acquisition of TLS data from most sensors and takes advantage of parallel programming to process approximately 1 million points per second. Moreover, the proposed segmentation does not require estimation of the normal at each point, which limits the errors in normal estimation propagating to segmentation. Both an indoor and outdoor scene are used for an experiment to demonstrate and discuss the effectiveness and robustness of the proposed segmentation method.

A high performance parallel approach to medical imaging

International Nuclear Information System (INIS)

Frieder, G.; Frieder, O.; Stytz, M.R.

1988-01-01

Research into medical imaging using general purpose parallel processing architectures is described and a review of the performance of previous medical imaging machines is provided. Results demonstrating that general purpose parallel architectures can achieve performance comparable to other, specialized, medical imaging machine architectures is presented. A new back-to-front hidden-surface removal algorithm is described. Results demonstrating the computational savings obtained by using the modified back-to-front hidden-surface removal algorithm are presented. Performance figures for forming a full-scale medical image on a mesh interconnected multiprocessor are presented

Parallel Monte Carlo simulation of aerosol dynamics

KAUST Repository

Zhou, K.

2014-01-01

A highly efficient Monte Carlo (MC) algorithm is developed for the numerical simulation of aerosol dynamics, that is, nucleation, surface growth, and coagulation. Nucleation and surface growth are handled with deterministic means, while coagulation is simulated with a stochastic method (Marcus-Lushnikov stochastic process). Operator splitting techniques are used to synthesize the deterministic and stochastic parts in the algorithm. The algorithm is parallelized using the Message Passing Interface (MPI). The parallel computing efficiency is investigated through numerical examples. Near 60% parallel efficiency is achieved for the maximum testing case with 3.7 million MC particles running on 93 parallel computing nodes. The algorithm is verified through simulating various testing cases and comparing the simulation results with available analytical and/or other numerical solutions. Generally, it is found that only small number (hundreds or thousands) of MC particles is necessary to accurately predict the aerosol particle number density, volume fraction, and so forth, that is, low order moments of the Particle Size Distribution (PSD) function. Accurately predicting the high order moments of the PSD needs to dramatically increase the number of MC particles. 2014 Kun Zhou et al.

Effects of temperature on surface modification of W exposed to He particles

International Nuclear Information System (INIS)

Li, C.; Greuner, H.; Yuan, Y.; Luo, G.N.; Böswirth, B.; Fu, B.Q.; Xu, H.Y.; Jia, Y.Z.; Liu, W.

2014-01-01

Highlights: • Blisters were observed on W surface under He beam heating at ∼950 °C. • He-induced blistering shows a clear grain orientation dependence. • An evolution to a coral-like structure was observed under loading at ∼2700 °C. • A texture with 〈0 0 1〉 parallel to the surface normal direction will be beneficial. - Abstract: The effect of combined heating and helium particle flux on annealed tungsten samples has been studied in the neutral beam facility GLADIS. He beams with power densities of 2.4 MW/m 2 and 9.5 MW/m 2 were used to adiabatically load the samples to peak surface temperatures from ∼950 °C (1223 K) to ∼2700 °C (2973 K). Changes in the surface morphology resulting from combined heat and the flux exposure were studied for He fluences up to 3 × 10 22 /m 2 . Typical structures for the sample loaded at ∼950 °C (1223 K) were blisters with a clear grain orientation dependence and the largest blisters formed on grains with 〈0 0 1〉 surface normal. However at higher temperatures, blistering was more easily suppressed for grains near this orientation because the growth of larger blister takes place more slowly. An evolution from a “porous structure” to a “coral-like structure” with increasing fluence was observed on the samples loaded at the highest temperature. Based on these results mechanisms for surface modification at different temperatures are discussed and a texture with 〈0 0 1〉 parallel to the normal direction of the grains is suggested to optimize the plasma facing material due to their stronger resistance to early stage blistering

A Study of Parallels Between Antarctica South Pole Traverse Equipment and Lunar/Mars Surface Systems

Science.gov (United States)

Mueller, Robert P.; Hoffman, Stephen, J.; Thur, Paul

2010-01-01

The parallels between an actual Antarctica South Pole re-supply traverse conducted by the National Science Foundation (NSF) Office of Polar Programs in 2009 have been studied with respect to the latest mission architecture concepts being generated by the United States National Aeronautics and Space Administration (NASA) for lunar and Mars surface systems scenarios. The challenges faced by both endeavors are similar since they must both deliver equipment and supplies to support operations in an extreme environment with little margin for error in order to be successful. By carefully and closely monitoring the manifesting and operational support equipment lists which will enable this South Pole traverse, functional areas have been identified. The equipment required to support these functions will be listed with relevant properties such as mass, volume, spare parts and maintenance schedules. This equipment will be compared to space systems currently in use and projected to be required to support equivalent and parallel functions in Lunar and Mars missions in order to provide a level of realistic benchmarking. Space operations have historically required significant amounts of support equipment and tools to operate and maintain the space systems that are the primary focus of the mission. By gaining insight and expertise in Antarctic South Pole traverses, space missions can use the experience gained over the last half century of Antarctic operations in order to design for operations, maintenance, dual use, robustness and safety which will result in a more cost effective, user friendly, and lower risk surface system on the Moon and Mars. It is anticipated that the U.S Antarctic Program (USAP) will also realize benefits for this interaction with NASA in at least two areas: an understanding of how NASA plans and carries out its missions and possible improved efficiency through factors such as weight savings, alternative technologies, or modifications in training and

Parallel Computation of RCS of Electrically Large Platform with Coatings Modeled with NURBS Surfaces

Directory of Open Access Journals (Sweden)

Ying Yan

2012-01-01

Full Text Available The significance of Radar Cross Section (RCS in the military applications makes its prediction an important problem. This paper uses large-scale parallel Physical Optics (PO to realize the fast computation of RCS to electrically large targets, which are modeled by Non-Uniform Rational B-Spline (NURBS surfaces and coated with dielectric materials. Some numerical examples are presented to validate this paper’s method. In addition, 1024 CPUs are used in Shanghai Supercomputer Center (SSC to perform the simulation of a model with the maximum electrical size 1966.7 λ for the first time in China. From which, it can be found that this paper’s method can greatly speed the calculation and is capable of solving the real-life problem of RCS prediction.

Trampoline motions in Xe-graphite(0 0 0 1) surface scattering

Science.gov (United States)

Watanabe, Yoshimasa; Yamaguchi, Hiroki; Hashinokuchi, Michihiro; Sawabe, Kyoichi; Maruyama, Shigeo; Matsumoto, Yoichiro; Shobatake, Kosuke

2005-09-01

We have investigated Xe scattering from the graphite(0 0 0 1) surface at hyperthermal incident energies using a molecular beam-surface scattering technique and molecular dynamics simulations. For all incident conditions, the incident Xe atom conserves the momentum parallel to the surface and loses approximately 80% of the normal incident energy. The weak interlayer potential of graphite disperses the deformation over the wide range of a graphene sheet. The dynamic corrugation induced by the collision is smooth even at hyperthermal incident energy; the graphene sheet moves like a trampoline net and the Xe atom like a trampoliner.

Formation times of RbHe exciplexes on the surface of superfluid versus normal fluid helium nanodroplets

International Nuclear Information System (INIS)

Droppelmann, G.; Buenermann, O.; Stienkemeier, F.; Schulz, C.P.

2004-01-01

Nanodroplets of either superfluid He 4 or normal fluid He 3 are doped with Rb atoms that are bound to the surface of the droplets. The formation of RbHe exciplexes upon 5P 3/2 excitation is monitored in real time by femtosecond pump-probe techniques. We find formation times of 8.5 and 11.6 ps for Rb He 4 and Rb He 3 , respectively. A comparison to calculations based on a tunneling model introduced for these systems by Reho et al. [J. Chem. Phys. 113, 9694 (2000)] shows that the proposed mechanism cannot account for our findings. Apparently, a different relaxation dynamics of the superfluid opposed to the normal fluid surface is responsible for the observed formation times

Implementation of a parallel version of a regional climate model

Energy Technology Data Exchange (ETDEWEB)

Gerstengarbe, F.W. [ed.; Kuecken, M. [Potsdam-Institut fuer Klimafolgenforschung (PIK), Potsdam (Germany); Schaettler, U. [Deutscher Wetterdienst, Offenbach am Main (Germany). Geschaeftsbereich Forschung und Entwicklung

1997-10-01

A regional climate model developed by the Max Planck Institute for Meterology and the German Climate Computing Centre in Hamburg based on the `Europa` and `Deutschland` models of the German Weather Service has been parallelized and implemented on the IBM RS/6000 SP computer system of the Potsdam Institute for Climate Impact Research including parallel input/output processing, the explicit Eulerian time-step, the semi-implicit corrections, the normal-mode initialization and the physical parameterizations of the German Weather Service. The implementation utilizes Fortran 90 and the Message Passing Interface. The parallelization strategy used is a 2D domain decomposition. This report describes the parallelization strategy, the parallel I/O organization, the influence of different domain decomposition approaches for static and dynamic load imbalances and first numerical results. (orig.)

Identification of surface species by vibrational normal mode analysis. A DFT study

Science.gov (United States)

Zhao, Zhi-Jian; Genest, Alexander; Rösch, Notker

2017-10-01

Infrared spectroscopy is an important experimental tool for identifying molecular species adsorbed on a metal surface that can be used in situ. Often vibrational modes in such IR spectra of surface species are assigned and identified by comparison with vibrational spectra of related (molecular) compounds of known structure, e. g., an organometallic cluster analogue. To check the validity of this strategy, we carried out a computational study where we compared the normal modes of three C2Hx species (x = 3, 4) in two types of systems, as adsorbates on the Pt(111) surface and as ligands in an organometallic cluster compound. The results of our DFT calculations reproduce the experimental observed frequencies with deviations of at most 50 cm-1. However, the frequencies of the C2Hx species in both types of systems have to be interpreted with due caution if the coordination mode is unknown. The comparative identification strategy works satisfactorily when the coordination mode of the molecular species (ethylidyne) is similar on the surface and in the metal cluster. However, large shifts are encountered when the molecular species (vinyl) exhibits different coordination modes on both types of substrates.

How Can Polarization States of Reflected Light from Snow Surfaces Inform Us on Surface Normals and Ultimately Snow Grain Size Measurements?

Science.gov (United States)

Schneider, A. M.; Flanner, M.; Yang, P.; Yi, B.; Huang, X.; Feldman, D.

2016-12-01

The Snow Grain Size and Pollution (SGSP) algorithm is a method applied to Moderate Resolution Imaging Spectroradiometer data to estimate snow grain size from space-borne measurements. Previous studies validate and quantify potential sources of error in this method, but because it assumes flat snow surfaces, however, large scale variations in surface normals can cause biases in its estimates due to its dependence on solar and observation zenith angles. To address these variations, we apply the Monte Carlo method for photon transport using data containing the single scattering properties of different ice crystals to calculate polarization states of reflected monochromatic light at 1500nm from modeled snow surfaces. We evaluate the dependence of these polarization states on solar and observation geometry at 1500nm because multiple scattering is generally a mechanism for depolarization and the ice crystals are relatively absorptive at this wavelength. Using 1500nm thus results in a higher number of reflected photons undergoing fewer scattering events, increasing the likelihood of reflected light having higher degrees of polarization. In evaluating the validity of the model, we find agreement with previous studies pertaining to near-infrared spectral directional hemispherical reflectance (i.e. black-sky albedo) and similarities in measured bidirectional reflectance factors, but few studies exist modeling polarization states of reflected light from snow surfaces. Here, we present novel results pertaining to calculated polarization states and compare dependences on solar and observation geometry for different idealized snow surfaces. If these dependencies are consistent across different ice particle shapes and sizes, then these findings could inform the SGSP algorithm by providing useful relationships between measurable physical quantities and solar and observation geometry to better understand variations in snow surface normals from remote sensing observations.

Effect of parallel electric fields on the whistler mode wave propagation in the magnetosphere

International Nuclear Information System (INIS)

Gupta, G.P.; Singh, R.N.

1975-01-01

The effect of parallel electric fields on whistler mode wave propagation has been studied. To account for the parallel electric fields, the dispersion equation has been analyzed, and refractive index surfaces for magnetospheric plasma have been constructed. The presence of parallel electric fields deforms the refractive index surfaces which diffuse the energy flow and produce defocusing of the whistler mode waves. The parallel electric field induces an instability in the whistler mode waves propagating through the magnetosphere. The growth or decay of whistler mode instability depends on the direction of parallel electric fields. It is concluded that the analyses of whistler wave records received on the ground should account for the role of parallel electric fields

Distribution of Different Sized Ocular Surface Vessels in Diabetics and Normal Individuals.

Science.gov (United States)

Banaee, Touka; Pourreza, Hamidreza; Doosti, Hassan; Abrishami, Mojtaba; Ehsaei, Asieh; Basiry, Mohsen; Pourreza, Reza

2017-01-01

To compare the distribution of different sized vessels using digital photographs of the ocular surface of diabetic and normal individuals. In this cross-sectional study, red-free conjunctival photographs of diabetic and normal individuals, aged 30-60 years, were taken under defined conditions and analyzed using a Radon transform-based algorithm for vascular segmentation. The image areas occupied by vessels (AOV) of different diameters were calculated. The main outcome measure was the distribution curve of mean AOV of different sized vessels. Secondary outcome measures included total AOV and standard deviation (SD) of AOV of different sized vessels. Two hundred and sixty-eight diabetic patients and 297 normal (control) individuals were included, differing in age (45.50 ± 5.19 vs. 40.38 ± 6.19 years, P distribution curves of mean AOV differed between patients and controls (smaller AOV for larger vessels in patients; P distribution curve of vessels compared to controls. Presence of diabetes mellitus is associated with contraction of larger vessels in the conjunctiva. Smaller vessels dilate with diabetic retinopathy. These findings may be useful in the photographic screening of diabetes mellitus and retinopathy.

Research surface resistance of copper normal and abnormal skin-effects depending on the frequency of electromagnetic field

International Nuclear Information System (INIS)

Kutovyi, V.A.; Komir, A.I.

2013-01-01

The results of the frequency dependence of surface resistance of copper in diffuse and specular reflection of electrons from the conductive surface of the high-frequency resonance of the system depending on the frequency of the electromagnetic field in the normal and anomalous skin effect. Found, the surface resistance of copper is reduced by more than 10 times at the temperature of liquid helium, as compared with a surface resistivity at room temperature, at frequencies f ≤ 173 MHz, for diffuse reflection of conduction electrons from the surface of the conductive layer, and the specular reflection - at frequencies f ≤ 346 MHz

Parallel Libraries to support High-Level Programming

DEFF Research Database (Denmark)

Larsen, Morten Nørgaard

and the Microsoft .NET iv framework. Normally, one would not directly think of the .NET framework when talking scientific applications, but Microsoft has in the last couple of versions of .NET introduce a number of tools for writing parallel and high performance code. The first section examines how programmers can...

Detachment of colloidal particles from collector surfaces with different electrostatic charge and hydrophobicity by attachment to air bubbles in a parallel plate flow chamber

NARCIS (Netherlands)

Suarez, CG; van der Mei, HC; Busscher, HJ

1999-01-01

The detachment of polystyrene particles adhering to collector surfaces with different electrostatic charge and hydrophobicity by attachment to a passing air bubble has been studied in a parallel plate flow chamber. Particle detachment decreased linearly with increasing air bubble velocity and

Arcing and surface damage in DITE

International Nuclear Information System (INIS)

Goodall, D.H.J.; McCracken, G.M.

1977-11-01

An investigation into the arcing damage on surfaces exposed to plasmas in the DITE tokamak is described. It has been found that arcing occurs on the fixed limiters, on probes inserted into the plasma and on parts of the torus structure. For surfaces parallel to the toroidal field most of the arcs run across the surface orthogonal to the field direction. Observations in the scanning electron microscope show that the arc tracks are formed by a series of melted craters characteristic of cathode arc spots. The amount of metal removed from the surface is consistent with the concentration of metal observed in the plasma. In plasmas with hydrogen gas puffing during the discharge or with injection of low Z impurities, the arc tracks are observed to be much shallower than in normal low density discharges. Several types of surface damage other than arc tracks have also been observed on probes. These phenomena occur less frequently than arcing and appear to be associated with abnormal discharge conditions. (author)

Modeling of normal contact of elastic bodies with surface relief taken into account

Science.gov (United States)

Goryacheva, I. G.; Tsukanov, I. Yu

2018-04-01

An approach to account the surface relief in normal contact problems for rough bodies on the basis of an additional displacement function for asperities is considered. The method and analytic expressions for calculating the additional displacement function for one-scale and two-scale wavy relief are presented. The influence of the microrelief geometric parameters, including the number of scales and asperities density, on additional displacements of the rough layer is analyzed.

Massively parallel fabrication of repetitive nanostructures: nanolithography for nanoarrays

International Nuclear Information System (INIS)

Luttge, Regina

2009-01-01

This topical review provides an overview of nanolithographic techniques for nanoarrays. Using patterning techniques such as lithography, normally we aim for a higher order architecture similarly to functional systems in nature. Inspired by the wealth of complexity in nature, these architectures are translated into technical devices, for example, found in integrated circuitry or other systems in which structural elements work as discrete building blocks in microdevices. Ordered artificial nanostructures (arrays of pillars, holes and wires) have shown particular properties and bring about the opportunity to modify and tune the device operation. Moreover, these nanostructures deliver new applications, for example, the nanoscale control of spin direction within a nanomagnet. Subsequently, we can look for applications where this unique property of the smallest manufactured element is repetitively used such as, for example with respect to spin, in nanopatterned magnetic media for data storage. These nanostructures are generally called nanoarrays. Most of these applications require massively parallel produced nanopatterns which can be directly realized by laser interference (areas up to 4 cm 2 are easily achieved with a Lloyd's mirror set-up). In this topical review we will further highlight the application of laser interference as a tool for nanofabrication, its limitations and ultimate advantages towards a variety of devices including nanostructuring for photonic crystal devices, high resolution patterned media and surface modifications of medical implants. The unique properties of nanostructured surfaces have also found applications in biomedical nanoarrays used either for diagnostic or functional assays including catalytic reactions on chip. Bio-inspired templated nanoarrays will be presented in perspective to other massively parallel nanolithography techniques currently discussed in the scientific literature. (topical review)

Surface flatness measurement of quasi-parallel plates employing three-beam interference with strong reference beam

Science.gov (United States)

Sunderland, Zofia; Patorski, Krzysztof

2016-12-01

A big challenge for standard interferogram analysis methods such as Temporal Phase Shifting or Fourier Transform is a parasitic set of fringes which might occur in the analyzed fringe pattern intensity distribution. It is encountered, for example, when transparent glass plates with quasi-parallel surfaces are tested in Fizeau or Twyman-Green interferometers. Besides the beams reflected from the plate front surface and the interferometer reference the beam reflected from the plate rear surface also plays important role; its amplitude is comparable with the amplitude of other beams. In result we face three families of fringes of high contrast which cannot be easily separated. Earlier we proposed a competitive solution for flatness measurements which relies on eliminating one of those fringe sets from the three-beam interferogram and separating two remaining ones with the use of 2D Continuous Wavelet Transform. In this work we cover the case when the intensity of the reference beam is significantly higher than the intensities of two object beams. The main advantage of differentiating beam intensities is the change in contrast of individual fringe families. Processing of such three-beam interferograms is modified but also takes advantage of 2D CWT. We show how to implement this method in Twyman-Green and Fizeau setups and compare this processing path and measurement procedures with previously proposed solutions.

PARALLEL MOVING MECHANICAL SYSTEMS

Directory of Open Access Journals (Sweden)

Florian Ion Tiberius Petrescu

2014-09-01

Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Moving mechanical systems parallel structures are solid, fast, and accurate. Between parallel systems it is to be noticed Stewart platforms, as the oldest systems, fast, solid and precise. The work outlines a few main elements of Stewart platforms. Begin with the geometry platform, kinematic elements of it, and presented then and a few items of dynamics. Dynamic primary element on it means the determination mechanism kinetic energy of the entire Stewart platforms. It is then in a record tail cinematic mobile by a method dot matrix of rotation. If a structural mottoelement consists of two moving elements which translates relative, drive train and especially dynamic it is more convenient to represent the mottoelement as a single moving components. We have thus seven moving parts (the six motoelements or feet to which is added mobile platform 7 and one fixed.

Image reconstruction method for electrical capacitance tomography based on the combined series and parallel normalization model

International Nuclear Information System (INIS)

Dong, Xiangyuan; Guo, Shuqing

2008-01-01

In this paper, a novel image reconstruction method for electrical capacitance tomography (ECT) based on the combined series and parallel model is presented. A regularization technique is used to obtain a stabilized solution of the inverse problem. Also, the adaptive coefficient of the combined model is deduced by numerical optimization. Simulation results indicate that it can produce higher quality images when compared to the algorithm based on the parallel or series models for the cases tested in this paper. It provides a new algorithm for ECT application

Normal appearance of the prostate and seminal tract: MR imaging using an endorectal surface coil

International Nuclear Information System (INIS)

Kim, Myeong Jin; Lee, Jong Tae; Lee, Moo Sang; Choi, Pil Sik; Hong, Sung Joon; Lee, Yeon Hee; Choi, Hak Yong

1994-01-01

To assess the ability of MR imaging with an endorectal surface coil for the depiction of normal anatomical structure of prostate and its adjacent organs. MR imaging using an endorectal surface coil was performed in 23 male patients(age ; 20-75) to evaluate various prostatic and vasovesicular disorders, i. e, 14 cases of ejaculatory problems, 3 cases of hypogonadism, and 4 cases of prostatic cancers and 2 cases of benign prostatic hyperplasia. MR images were obtained with axial, sagittal and coronal fast spin echo long TR/TE images and axial spin echo short TR/TE images. Field of views was 10-12 cm and scan thickness was 3-5 mm. Depiction of normal anatomcial structures was excellent in all cases. On T2WI, zonal anatomy of the prostate and prostatic urethra, urethral crest, and ejaculatory duct were cleary visualized. On T1WI, periprostatic fat plane is more cleary visualized. On transverse images, periprostatic structures were well visualized on T1WI,and on T2WI, anterior fibromuscular stroma, transition zone and peripheral zone could be readily differentiated. Coronal images were more helpful in visualization of both central and peripheral zones. Vas deferens, ejaculatory duct and vermontanum were also more easily defined on these images. Sagittal images was helpful in the depiction of anterior fibromuscular stroma, central zone and peripheral zone with prostatic urethra and ejaculatory duct in a single plane. High resolution MR imaging with an endorectal surface coil can readily visualize the normal anatomy of the prostate and its related structures and may be useful in the evaluation of various diseases of prostate and vasvesicular system

Normal appearance of the prostate and seminal tract: MR imaging using an endorectal surface coil

Energy Technology Data Exchange (ETDEWEB)

Kim, Myeong Jin; Lee, Jong Tae; Lee, Moo Sang; Choi, Pil Sik; Hong, Sung Joon; Lee, Yeon Hee; Choi, Hak Yong [Yonsei University College of Medicine, Seoul (Korea, Republic of)

1994-06-15

To assess the ability of MR imaging with an endorectal surface coil for the depiction of normal anatomical structure of prostate and its adjacent organs. MR imaging using an endorectal surface coil was performed in 23 male patients(age ; 20-75) to evaluate various prostatic and vasovesicular disorders, i. e, 14 cases of ejaculatory problems, 3 cases of hypogonadism, and 4 cases of prostatic cancers and 2 cases of benign prostatic hyperplasia. MR images were obtained with axial, sagittal and coronal fast spin echo long TR/TE images and axial spin echo short TR/TE images. Field of views was 10-12 cm and scan thickness was 3-5 mm. Depiction of normal anatomcial structures was excellent in all cases. On T2WI, zonal anatomy of the prostate and prostatic urethra, urethral crest, and ejaculatory duct were cleary visualized. On T1WI, periprostatic fat plane is more cleary visualized. On transverse images, periprostatic structures were well visualized on T1WI,and on T2WI, anterior fibromuscular stroma, transition zone and peripheral zone could be readily differentiated. Coronal images were more helpful in visualization of both central and peripheral zones. Vas deferens, ejaculatory duct and vermontanum were also more easily defined on these images. Sagittal images was helpful in the depiction of anterior fibromuscular stroma, central zone and peripheral zone with prostatic urethra and ejaculatory duct in a single plane. High resolution MR imaging with an endorectal surface coil can readily visualize the normal anatomy of the prostate and its related structures and may be useful in the evaluation of various diseases of prostate and vasvesicular system.

3D modeling to characterize lamina cribrosa surface and pore geometries using in vivo images from normal and glaucomatous eyes

Science.gov (United States)

Sredar, Nripun; Ivers, Kevin M.; Queener, Hope M.; Zouridakis, George; Porter, Jason

2013-01-01

En face adaptive optics scanning laser ophthalmoscope (AOSLO) images of the anterior lamina cribrosa surface (ALCS) represent a 2D projected view of a 3D laminar surface. Using spectral domain optical coherence tomography images acquired in living monkey eyes, a thin plate spline was used to model the ALCS in 3D. The 2D AOSLO images were registered and projected onto the 3D surface that was then tessellated into a triangular mesh to characterize differences in pore geometry between 2D and 3D images. Following 3D transformation of the anterior laminar surface in 11 normal eyes, mean pore area increased by 5.1 ± 2.0% with a minimal change in pore elongation (mean change = 0.0 ± 0.2%). These small changes were due to the relatively flat laminar surfaces inherent in normal eyes (mean radius of curvature = 3.0 ± 0.5 mm). The mean increase in pore area was larger following 3D transformation in 4 glaucomatous eyes (16.2 ± 6.0%) due to their more steeply curved laminar surfaces (mean radius of curvature = 1.3 ± 0.1 mm), while the change in pore elongation was comparable to that in normal eyes (−0.2 ± 2.0%). This 3D transformation and tessellation method can be used to better characterize and track 3D changes in laminar pore and surface geometries in glaucoma. PMID:23847739

Parallel hierarchical global illumination

Energy Technology Data Exchange (ETDEWEB)

Snell, Quinn O. [Iowa State Univ., Ames, IA (United States)

1997-10-08

Solving the global illumination problem is equivalent to determining the intensity of every wavelength of light in all directions at every point in a given scene. The complexity of the problem has led researchers to use approximation methods for solving the problem on serial computers. Rather than using an approximation method, such as backward ray tracing or radiosity, the authors have chosen to solve the Rendering Equation by direct simulation of light transport from the light sources. This paper presents an algorithm that solves the Rendering Equation to any desired accuracy, and can be run in parallel on distributed memory or shared memory computer systems with excellent scaling properties. It appears superior in both speed and physical correctness to recent published methods involving bidirectional ray tracing or hybrid treatments of diffuse and specular surfaces. Like progressive radiosity methods, it dynamically refines the geometry decomposition where required, but does so without the excessive storage requirements for ray histories. The algorithm, called Photon, produces a scene which converges to the global illumination solution. This amounts to a huge task for a 1997-vintage serial computer, but using the power of a parallel supercomputer significantly reduces the time required to generate a solution. Currently, Photon can be run on most parallel environments from a shared memory multiprocessor to a parallel supercomputer, as well as on clusters of heterogeneous workstations.

Sharing of nonlinear load in parallel-connected three-phase converters

DEFF Research Database (Denmark)

Borup, Uffe; Blaabjerg, Frede; Enjeti, Prasad N.

2001-01-01

compensation are connected in parallel. Without the new solution, they are normally not able to distinguish the harmonic currents that flow to the load and harmonic currents that circulate between the converters. Analysis and experimental results on two 90-kVA 400-Hz converters in parallel are presented......In this paper, a new control method is presented which enables equal sharing of linear and nonlinear loads in three-phase power converters connected in parallel, without communication between the converters. The paper focuses on solving the problem that arises when two converters with harmonic....... The results show that both linear and nonlinear loads can be shared equally by the proposed concept....

A poloidal non-uniformity of the collisionless parallel current in a tokamak plasma

Energy Technology Data Exchange (ETDEWEB)

Romannikov, A.; Fenzi-Bonizec, C

2005-07-01

The collisionless distortion of the ion (electron) distribution function at certain points on a magnetic surface is studied in the framework of a simple model of a large aspect ratio tokamak plasma. The flow velocity driven by this distortion is calculated. The possibility of an additional non-uniform collisionless parallel current density on a magnetic surface, other than the known neo-classical non-uniformity is shown. The difference between the parallel current density on the low and high field side of a magnetic surface is close to the neoclassical bootstrap current density. The first Tore-Supra experimental test indicates the possibility of the poloidal non-uniformity of the parallel current density. (authors)

A parallel algorithm for transient solid dynamics simulations with contact detection

International Nuclear Information System (INIS)

Attaway, S.; Hendrickson, B.; Plimpton, S.; Gardner, D.; Vaughan, C.; Heinstein, M.; Peery, J.

1996-01-01

Solid dynamics simulations with Lagrangian finite elements are used to model a wide variety of problems, such as the calculation of impact damage to shipping containers for nuclear waste and the analysis of vehicular crashes. Using parallel computers for these simulations has been hindered by the difficulty of searching efficiently for material surface contacts in parallel. A new parallel algorithm for calculation of arbitrary material contacts in finite element simulations has been developed and implemented in the PRONTO3D transient solid dynamics code. This paper will explore some of the issues involved in developing efficient, portable, parallel finite element models for nonlinear transient solid dynamics simulations. The contact-detection problem poses interesting challenges for efficient implementation of a solid dynamics simulation on a parallel computer. The finite element mesh is typically partitioned so that each processor owns a localized region of the finite element mesh. This mesh partitioning is optimal for the finite element portion of the calculation since each processor must communicate only with the few connected neighboring processors that share boundaries with the decomposed mesh. However, contacts can occur between surfaces that may be owned by any two arbitrary processors. Hence, a global search across all processors is required at every time step to search for these contacts. Load-imbalance can become a problem since the finite element decomposition divides the volumetric mesh evenly across processors but typically leaves the surface elements unevenly distributed. In practice, these complications have been limiting factors in the performance and scalability of transient solid dynamics on massively parallel computers. In this paper the authors present a new parallel algorithm for contact detection that overcomes many of these limitations

Power stability methods for parallel systems

International Nuclear Information System (INIS)

Wallach, Y.

1988-01-01

Parallel-Processing Systems are already commercially available. This paper shows that if one of them - the Alternating Sequential Parallel, or ASP system - is applied to network stability calculations it will lead to a higher speed of solution. The ASP system is first described and is then shown to be cheaper, more reliable and available than other parallel systems. Also, no deadlock need be feared and the speedup is normally very high. A number of ASP systems were already assembled (the SMS systems, Topps, DIRMU etc.). At present, an IBM Local Area Network is being modified so that it too can work in the ASP mode. Existing ASP systems were programmed in Fortran or assembly language. Since newer systems (e.g. DIRMU) are programmed in Modula-2, this language can be used. Stability analysis is based on solving nonlinear differential and algebraic equations. The algorithm for solving the nonlinear differential equations on ASP, is described and programmed in Modula-2. The speedup is computed and is shown to be almost optimal

A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

International Nuclear Information System (INIS)

Fainberg, J; Schaefer, W

2015-01-01

A new algorithm for heat exchange between thermally coupled diffusely radiating interfaces is presented, which can be applied for closed and half open transparent radiating cavities. Interfaces between opaque and transparent materials are automatically detected and subdivided into elementary radiation surfaces named tiles. Contrary to the classical view factor method, the fixed unit sphere area subdivision oriented along the normal tile direction is projected onto the surrounding radiation mesh and not vice versa. Then, the total incident radiating flux of the receiver is approximated as a direct sum of radiation intensities of representative “senders” with the same weight factor. A hierarchical scheme for the space angle subdivision is selected in order to minimize the total memory and the computational demands during thermal calculations. Direct visibility is tested by means of a voxel-based ray tracing method accelerated by means of the anisotropic Chebyshev distance method, which reuses the computational grid as a Chebyshev one. The ray tracing algorithm is fully parallelized using MPI and takes advantage of the balanced distribution of all available tiles among all CPU's. This approach allows tracing of each particular ray without any communication. The algorithm has been implemented in a commercial casting process simulation software. The accuracy and computational performance of the new radiation model for heat treatment, investment and ingot casting applications is illustrated using industrial examples. (paper)

Navier-Stokes Computations of a Wing-Flap Model With Blowing Normal to the Flap Surface

Science.gov (United States)

Boyd, D. Douglas, Jr.

2005-01-01

A computational study of a generic wing with a half span flap shows the mean flow effects of several blown flap configurations. The effort compares and contrasts the thin-layer, Reynolds averaged, Navier-Stokes solutions of a baseline wing-flap configuration with configurations that have blowing normal to the flap surface through small slits near the flap side edge. Vorticity contours reveal a dual vortex structure at the flap side edge for all cases. The dual vortex merges into a single vortex at approximately the mid-flap chord location. Upper surface blowing reduces the strength of the merged vortex and moves the vortex away from the upper edge. Lower surface blowing thickens the lower shear layer and weakens the merged vortex, but not as much as upper surface blowing. Side surface blowing forces the lower surface vortex farther outboard of the flap edge by effectively increasing the aerodynamic span of the flap. It is seen that there is no global aerodynamic penalty or benefit from the particular blowing configurations examined.

Arrays of surface-normal electroabsorption modulators for the generation and signal processing of microwave photonics signals

NARCIS (Netherlands)

Noharet, Bertrand; Wang, Qin; Platt, Duncan; Junique, Stéphane; Marpaung, D.A.I.; Roeloffzen, C.G.H.

2011-01-01

The development of an array of 16 surface-normal electroabsorption modulators operating at 1550nm is presented. The modulator array is dedicated to the generation and processing of microwave photonics signals, targeting a modulation bandwidth in excess of 5GHz. The hybrid integration of the

Normalization in quantitative [18F]FDG PET imaging: the 'body surface area' may be a volume

International Nuclear Information System (INIS)

Laffon, Eric; Suarez, Kleydis; Berthoumieu, Yannick; Ducassou, Dominique; Marthan, Roger

2006-01-01

Non-invasive methods for quantifying [ 18 F]FDG uptake in tumours often require normalization to either body weight or body surface area (BSA), as a surrogate for [ 18 F]FDG distribution volume (DV). Whereas three dimensions are involved in DV and weight (assuming that weight is proportional to volume), only two dimensions are obviously involved in BSA. However, a fractal geometry interpretation, related to an allometric scaling, suggests that the so-called 'body surface area' may stand for DV. (note)

From Intensity Profile to Surface Normal: Photometric Stereo for Unknown Light Sources and Isotropic Reflectances.

Science.gov (United States)

Lu, Feng; Matsushita, Yasuyuki; Sato, Imari; Okabe, Takahiro; Sato, Yoichi

2015-10-01

We propose an uncalibrated photometric stereo method that works with general and unknown isotropic reflectances. Our method uses a pixel intensity profile, which is a sequence of radiance intensities recorded at a pixel under unknown varying directional illumination. We show that for general isotropic materials and uniformly distributed light directions, the geodesic distance between intensity profiles is linearly related to the angular difference of their corresponding surface normals, and that the intensity distribution of the intensity profile reveals reflectance properties. Based on these observations, we develop two methods for surface normal estimation; one for a general setting that uses only the recorded intensity profiles, the other for the case where a BRDF database is available while the exact BRDF of the target scene is still unknown. Quantitative and qualitative evaluations are conducted using both synthetic and real-world scenes, which show the state-of-the-art accuracy of smaller than 10 degree without using reference data and 5 degree with reference data for all 100 materials in MERL database.

Surface-wave potential for triggering tectonic (nonvolcanic) tremor

Science.gov (United States)

Hill, D.P.

2010-01-01

Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle is anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45?? incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia mega-thrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction, ????? 0.2). However, documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, is associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (?? ~ 0.6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

Evolution of the Contact Area with Normal Load for Rough Surfaces: from Atomic to Macroscopic Scales.

Science.gov (United States)

Huang, Shiping

2017-11-13

The evolution of the contact area with normal load for rough surfaces has great fundamental and practical importance, ranging from earthquake dynamics to machine wear. This work bridges the gap between the atomic scale and the macroscopic scale for normal contact behavior. The real contact area, which is formed by a large ensemble of discrete contacts (clusters), is proven to be much smaller than the apparent surface area. The distribution of the discrete contact clusters and the interaction between them are key to revealing the mechanism of the contacting solids. To this end, Green's function molecular dynamics (GFMD) is used to study both how the contact cluster evolves from the atomic scale to the macroscopic scale and the interaction between clusters. It is found that the interaction between clusters has a strong effect on their formation. The formation and distribution of the contact clusters is far more complicated than that predicted by the asperity model. Ignorance of the interaction between them leads to overestimating the contacting force. In real contact, contacting clusters are smaller and more discrete due to the interaction between the asperities. Understanding the exact nature of the contact area with the normal load is essential to the following research on friction.

Trajectories of cortical surface area and cortical volume maturation in normal brain development

Directory of Open Access Journals (Sweden)

Simon Ducharme

2015-12-01

Full Text Available This is a report of developmental trajectories of cortical surface area and cortical volume in the NIH MRI Study of Normal Brain Development. The quality-controlled sample included 384 individual typically-developing subjects with repeated scanning (1–3 per subject, total scans n=753 from 4.9 to 22.3 years of age. The best-fit model (cubic, quadratic, or first-order linear was identified at each vertex using mixed-effects models, with statistical correction for multiple comparisons using random field theory. Analyses were performed with and without controlling for total brain volume. These data are provided for reference and comparison with other databases. Further discussion and interpretation on cortical developmental trajectories can be found in the associated Ducharme et al.׳s article “Trajectories of cortical thickness maturation in normal brain development – the importance of quality control procedures” (Ducharme et al., 2015 [1].

Morphological evolution of dissolving feldspar particles with anisotropic surface kinetics and implications for dissolution rate normalization and grain size dependence: A kinetic modeling study

Science.gov (United States)

Zhang, Li; Lüttge, Andreas

2009-11-01

With previous two-dimensional (2D) simulations based on surface-specific feldspar dissolution succeeding in relating the macroscopic feldspar kinetics to the molecular-scale surface reactions of Si and Al atoms ( Zhang and Lüttge, 2008, 2009), we extended our modeling effort to three-dimensional (3D) feldspar particle dissolution simulations. Bearing on the same theoretical basis, the 3D feldspar particle dissolution simulations have verified the anisotropic surface kinetics observed in the 2D surface-specific simulations. The combined effect of saturation state, pH, and temperature on the surface kinetics anisotropy has been subsequently evaluated, found offering diverse options for morphological evolution of dissolving feldspar nanoparticles with varying grain sizes and starting shapes. Among the three primary faces on the simulated feldspar surface, the (1 0 0) face has the biggest dissolution rate across an extensively wide saturation state range and thus acquires a higher percentage of the surface area upon dissolution. The slowest dissolution occurs to either (0 0 1) or (0 1 0) faces depending on the bond energies of Si-(O)-Si ( ΦSi-O-Si/ kT) and Al-(O)-Si ( ΦAl-O-Si/ kT). When the ratio of ΦSi-O-Si/ kT to ΦAl-O-Si/ kT changes from 6:3 to 7:5, the dissolution rates of three primary faces change from the trend of (1 0 0) > (0 1 0) > (0 0 1) to the trend of (1 0 0) > (0 0 1) > (0 1 0). The rate difference between faces becomes more distinct and accordingly edge rounding becomes more significant. Feldspar nanoparticles also experience an increasing degree of edge rounding from far-from-equilibrium to close-to-equilibrium. Furthermore, we assessed the connection between the continuous morphological modification and the variation in the bulk dissolution rate during the dissolution of a single feldspar particle. Different normalization treatments equivalent to the commonly used mass, cube assumption, sphere assumption, geometric surface area, and reactive

Surface-modified CMOS IC electrochemical sensor array targeting single chromaffin cells for highly parallel amperometry measurements.

Science.gov (United States)

Huang, Meng; Delacruz, Joannalyn B; Ruelas, John C; Rathore, Shailendra S; Lindau, Manfred

2018-01-01

Amperometry is a powerful method to record quantal release events from chromaffin cells and is widely used to assess how specific drugs modify quantal size, kinetics of release, and early fusion pore properties. Surface-modified CMOS-based electrochemical sensor arrays allow simultaneous recordings from multiple cells. A reliable, low-cost technique is presented here for efficient targeting of single cells specifically to the electrode sites. An SU-8 microwell structure is patterned on the chip surface to provide insulation for the circuitry as well as cell trapping at the electrode sites. A shifted electrode design is also incorporated to increase the flexibility of the dimension and shape of the microwells. The sensitivity of the electrodes is validated by a dopamine injection experiment. Microwells with dimensions slightly larger than the cells to be trapped ensure excellent single-cell targeting efficiency, increasing the reliability and efficiency for on-chip single-cell amperometry measurements. The surface-modified device was validated with parallel recordings of live chromaffin cells trapped in the microwells. Rapid amperometric spikes with no diffusional broadening were observed, indicating that the trapped and recorded cells were in very close contact with the electrodes. The live cell recording confirms in a single experiment that spike parameters vary significantly from cell to cell but the large number of cells recorded simultaneously provides the statistical significance.

Experimental studies in a single-phase parallel channel natural circulation system. Preliminary results

International Nuclear Information System (INIS)

Bodkha, Kapil; Pilkhwal, D.S.; Jana, S.S.; Vijayan, P.K.

2016-01-01

Natural circulation systems find extensive applications in industrial engineering systems. One of the applications is in nuclear reactor where the decay heat is removed by natural circulation of the fluid under off-normal conditions. The upcoming reactor designs make use of natural circulation in order to remove the heat from core under normal operating conditions also. These reactors employ multiple vertical fuel channels with provision of on-power refueling/defueling. Natural circulation systems are relatively simple, safe and reliable when compared to forced circulation systems. However, natural circulation systems are prone to encounter flow instabilities which are highly undesirable for various reasons. Presence of parallel channels under natural circulation makes the system more complicated. To examine the behavior of parallel channel system, studies were carried out for single-phase natural circulation flow in a multiple vertical channel system. The objective of the present work is to study the flow behavior of the parallel heated channel system under natural circulation for different operating conditions. Steady state and transient studies have been carried out in a parallel channel natural circulation system with three heated channels. The paper brings out the details of the system considered, different cases analyzed and preliminary results of studies carried out on a single-phase parallel channel system.

Investigation of the near-surface electronic structure of Cr(001)

International Nuclear Information System (INIS)

Klebanoff, L.E.; Robey, S.W.; Liu, G.; Shirley, D.A.

1985-01-01

An angle-resolved photoelectron spectroscopy (ARPES) study of Cr(001) near-surface electronic structure is presented. Measurements are reported for energy-band dispersions along the [010] direction parallel to the crystal surface. The periodicity of these band dispersions indicates that the valence electrons experience and self-consistently establish antiferromagnetism in the near-surface layers of Cr(001). We also present highly-surface-sensitive ARPES measurements of the energy-band dispersions along the [001] direction normal to the surface. The results suggest that the surface magnetic moments, which couple ferromagnetically to each other within the surface layer, couple antiferromagnetically to the moments of the atoms in the second layer. Temperature-dependent studies are presented that reveal the persistence of near-surface antiferromagnetic order for temperatures up to 2.5 times the bulk Neel temperature. The temperature dependence of this antiferromagnetic order suggests that its thermal stability derives in part from the stability of the Cr(001) ferromagnetic surface phase

A study of objective functions for organs with parallel and serial architecture

International Nuclear Information System (INIS)

Stavrev, P.V.; Stavreva, N.A.; Round, W.H.

1997-01-01

An objective function analysis when target volumes are deliberately enlarged to account for tumour mobility and consecutive uncertainty in the tumour position in external beam radiotherapy has been carried out. The dose distribution inside the tumour is assumed to have logarithmic dependence on the tumour cell density which assures an iso-local tumour control probability. The normal tissue immediately surrounding the tumour is irradiated homogeneously at a dose level equal to the dose D(R)) delivered at the edge of the tumour The normal tissue in the high dose field is modelled as being organized in identical functional subunits (FSUs) composed of a relatively large number of cells. Two types of organs - having serial and parallel architecture are considered. Implicit averaging over intrapatient normal tissue radiosensitivity variations is done. A function describing the normal tissue survival probability S 0 is constructed. The objective function is given as a product of the total tumour control probability (TCP) and the normal tissue survival probability S 0 . The values of the dose D(R)) which result in a maximum of the objective function are obtained for different combinations of tumour and normal tissue parameters, such as tumour and normal tissue radiosensitivities, number of cells constituting a normal tissue functional unit, total number of normal cells under high dose (D(R)) exposure and functional reserve for organs having parallel architecture. The corresponding TCP and S 0 values are computed and discussed. (authors)

Ripple formation on Si surfaces during plasma etching in Cl2

Science.gov (United States)

Nakazaki, Nobuya; Matsumoto, Haruka; Sonobe, Soma; Hatsuse, Takumi; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2018-05-01

Nanoscale surface roughening and ripple formation in response to ion incidence angle has been investigated during inductively coupled plasma etching of Si in Cl2, using sheath control plates to achieve the off-normal ion incidence on blank substrate surfaces. The sheath control plate consisted of an array of inclined trenches, being set into place on the rf-biased electrode, where their widths and depths were chosen in such a way that the sheath edge was pushed out of the trenches. The distortion of potential distributions and the consequent deflection of ion trajectories above and in the trenches were then analyzed based on electrostatic particle-in-cell simulations of the plasma sheath, to evaluate the angular distributions of ion fluxes incident on substrates pasted on sidewalls and/or at the bottom of the trenches. Experiments showed well-defined periodic sawtooth-like ripples with their wave vector oriented parallel to the direction of ion incidence at intermediate off-normal angles, while relatively weak corrugations or ripplelike structures with the wave vector perpendicular to it at high off-normal angles. Possible mechanisms for the formation of surface ripples during plasma etching are discussed with the help of Monte Carlo simulations of plasma-surface interactions and feature profile evolution. The results indicate the possibility of providing an alternative to ion beam sputtering for self-organized formation of ordered surface nanostructures.

New partially parallel acquisition technique in cerebral imaging: preliminary findings

International Nuclear Information System (INIS)

Tintera, Jaroslav; Gawehn, Joachim; Bauermann, Thomas; Vucurevic, Goran; Stoeter, Peter

2004-01-01

In MRI applications where short acquisition time is necessary, the increase of acquisition speed is often at the expense of image resolution and SNR. In such cases, the newly developed parallel acquisition techniques could provide images without mentioned limitations and in reasonably shortened measurement time. A newly designed eight-channel head coil array (i-PAT coil) allowing for parallel acquisition of independently reconstructed images (GRAPPA mode) has been tested for its applicability in neuroradiology. Image homogeneity was tested in standard phantom and healthy volunteers. BOLD signal changes were studied in a group of six volunteers using finger tapping stimulation. Phantom studies revealed an important drop of signal even after the use of a normalization filter in the center of the image and an important increase of artifact power with reduction of measurement time strongly depending on the combination of acceleration parameters. The additional application of a parallel acquisition technique such as GRAPPA decreases measurement time in the range of about 30%, but further reduction is often possible only at the expense of SNR. This technique performs best in conditions in which imaging speed is important, such as CE MRA, but time resolution still does not allow the acquisition of angiograms separating the arterial and venous phase. Significantly larger areas of BOLD activation were found using the i-PAT coil compared to the standard head coil. Being an eight-channel surface coil array, peripheral cortical structures profit from high SNR as high-resolution imaging of small cortical dysplasias and functional activation of cortical areas imaged by BOLD contrast. In BOLD contrast imaging, susceptibility artifacts are reduced, but only if an appropriate combination of acceleration parameters is used. (orig.)

New partially parallel acquisition technique in cerebral imaging: preliminary findings

Energy Technology Data Exchange (ETDEWEB)

Tintera, Jaroslav [Institute for Clinical and Experimental Medicine, Prague (Czech Republic); Gawehn, Joachim; Bauermann, Thomas; Vucurevic, Goran; Stoeter, Peter [University Clinic Mainz, Institute of Neuroradiology, Mainz (Germany)

2004-12-01

In MRI applications where short acquisition time is necessary, the increase of acquisition speed is often at the expense of image resolution and SNR. In such cases, the newly developed parallel acquisition techniques could provide images without mentioned limitations and in reasonably shortened measurement time. A newly designed eight-channel head coil array (i-PAT coil) allowing for parallel acquisition of independently reconstructed images (GRAPPA mode) has been tested for its applicability in neuroradiology. Image homogeneity was tested in standard phantom and healthy volunteers. BOLD signal changes were studied in a group of six volunteers using finger tapping stimulation. Phantom studies revealed an important drop of signal even after the use of a normalization filter in the center of the image and an important increase of artifact power with reduction of measurement time strongly depending on the combination of acceleration parameters. The additional application of a parallel acquisition technique such as GRAPPA decreases measurement time in the range of about 30%, but further reduction is often possible only at the expense of SNR. This technique performs best in conditions in which imaging speed is important, such as CE MRA, but time resolution still does not allow the acquisition of angiograms separating the arterial and venous phase. Significantly larger areas of BOLD activation were found using the i-PAT coil compared to the standard head coil. Being an eight-channel surface coil array, peripheral cortical structures profit from high SNR as high-resolution imaging of small cortical dysplasias and functional activation of cortical areas imaged by BOLD contrast. In BOLD contrast imaging, susceptibility artifacts are reduced, but only if an appropriate combination of acceleration parameters is used. (orig.)

Recent progress in 3D EM/EM-PIC simulation with ARGUS and parallel ARGUS

International Nuclear Information System (INIS)

Mankofsky, A.; Petillo, J.; Krueger, W.; Mondelli, A.; McNamara, B.; Philp, R.

1994-01-01

ARGUS is an integrated, 3-D, volumetric simulation model for systems involving electric and magnetic fields and charged particles, including materials embedded in the simulation region. The code offers the capability to carry out time domain and frequency domain electromagnetic simulations of complex physical systems. ARGUS offers a boolean solid model structure input capability that can include essentially arbitrary structures on the computational domain, and a modular architecture that allows multiple physics packages to access the same data structure and to share common code utilities. Physics modules are in place to compute electrostatic and electromagnetic fields, the normal modes of RF structures, and self-consistent particle-in-cell (PIC) simulation in either a time dependent mode or a steady state mode. The PIC modules include multiple particle species, the Lorentz equations of motion, and algorithms for the creation of particles by emission from material surfaces, injection onto the grid, and ionization. In this paper, we present an updated overview of ARGUS, with particular emphasis given in recent algorithmic and computational advances. These include a completely rewritten frequency domain solver which efficiently treats lossy materials and periodic structures, a parallel version of ARGUS with support for both shared memory parallel vector (i.e. CRAY) machines and distributed memory massively parallel MIMD systems, and numerous new applications of the code

Large enhancement of thermoelectric effects in a tunneling-coupled parallel DQD-AB ring attached to one normal and one superconducting lead

Science.gov (United States)

Yao, Hui; Zhang, Chao; Li, Zhi-Jian; Nie, Yi-Hang; Niu, Peng-bin

2018-05-01

We theoretically investigate the thermoelectric properties in a tunneling-coupled parallel DQD-AB ring attached to one normal and one superconducting lead. The role of the intrinsic and extrinsic parameters in improving thermoelectric properties is discussed. The peak value of figure of merit near gap edges increases with the asymmetry parameter decreasing, particularly, when asymmetry parameter is less than 0.5, the figure of merit near gap edges rapidly rises. When the interdot coupling strengh is less than the superconducting gap the thermopower spectrum presents a single-platform structure. While when the interdot coupling strengh is larger than the gap, a double-platform structure appears in thermopower spectrum. Outside the gap the peak values of figure of merit might reach the order of 102. On the basis of optimizing internal parameters the thermoelectric conversion efficiency of the device can be further improved by appropriately matching the total magnetic flux and the flux difference between two subrings.

Parallelization of pressure equation solver for incompressible N-S equations

International Nuclear Information System (INIS)

Ichihara, Kiyoshi; Yokokawa, Mitsuo; Kaburaki, Hideo.

1996-03-01

A pressure equation solver in a code for 3-dimensional incompressible flow analysis has been parallelized by using red-black SOR method and PCG method on Fujitsu VPP500, a vector parallel computer with distributed memory. For the comparison of scalability, the solver using the red-black SOR method has been also parallelized on the Intel Paragon, a scalar parallel computer with a distributed memory. The scalability of the red-black SOR method on both VPP500 and Paragon was lost, when number of processor elements was increased. The reason of non-scalability on both systems is increasing communication time between processor elements. In addition, the parallelization by DO-loop division makes the vectorizing efficiency lower on VPP500. For an effective implementation on VPP500, a large scale problem which holds very long vectorized DO-loops in the parallel program should be solved. PCG method with red-black SOR method applied to incomplete LU factorization (red-black PCG) has more iteration steps than normal PCG method with forward and backward substitution, in spite of same number of the floating point operations in a DO-loop of incomplete LU factorization. The parallelized red-black PCG method has less merits than the parallelized red-black SOR method when the computational region has fewer grids, because the low vectorization efficiency is obtained in red-black PCG method. (author)

Biharmonic Submanifolds with Parallel Mean Curvature Vector in Pseudo-Euclidean Spaces

Energy Technology Data Exchange (ETDEWEB)

Fu, Yu, E-mail: yufudufe@gmail.com [Dongbei University of Finance and Economics, School of Mathematics and Quantitative Economics (China)

2013-12-15

In this paper, we investigate biharmonic submanifolds in pseudo-Euclidean spaces with arbitrary index and dimension. We give a complete classification of biharmonic spacelike submanifolds with parallel mean curvature vector in pseudo-Euclidean spaces. We also determine all biharmonic Lorentzian surfaces with parallel mean curvature vector field in pseudo-Euclidean spaces.

Biharmonic Submanifolds with Parallel Mean Curvature Vector in Pseudo-Euclidean Spaces

International Nuclear Information System (INIS)

Fu, Yu

2013-01-01

In this paper, we investigate biharmonic submanifolds in pseudo-Euclidean spaces with arbitrary index and dimension. We give a complete classification of biharmonic spacelike submanifolds with parallel mean curvature vector in pseudo-Euclidean spaces. We also determine all biharmonic Lorentzian surfaces with parallel mean curvature vector field in pseudo-Euclidean spaces

A new normalization method based on electrical field lines for electrical capacitance tomography

International Nuclear Information System (INIS)

Zhang, L F; Wang, H X

2009-01-01

Electrical capacitance tomography (ECT) is considered to be one of the most promising process tomography techniques. The image reconstruction for ECT is an inverse problem to find the spatially distributed permittivities in a pipe. Usually, the capacitance measurements obtained from the ECT system are normalized at the high and low permittivity for image reconstruction. The parallel normalization model is commonly used during the normalization process, which assumes the distribution of materials in parallel. Thus, the normalized capacitance is a linear function of measured capacitance. A recently used model is a series normalization model which results in the normalized capacitance as a nonlinear function of measured capacitance. The newest presented model is based on electrical field centre lines (EFCL), and is a mixture of two normalization models. The multi-threshold method of this model is presented in this paper. The sensitivity matrices based on different normalization models were obtained, and image reconstruction was carried out accordingly. Simulation results indicate that reconstructed images with higher quality can be obtained based on the presented model

Comparative analysis of the surface exposed proteome of two canine osteosarcoma cell lines and normal canine osteoblasts.

Science.gov (United States)

Milovancev, Milan; Hilgart-Martiszus, Ian; McNamara, Michael J; Goodall, Cheri P; Seguin, Bernard; Bracha, Shay; Wickramasekara, Samanthi I

2013-06-13

Osteosarcoma (OSA) is the most common primary bone tumor of dogs and carries a poor prognosis despite aggressive treatment. An improved understanding of the biology of OSA is critically needed to allow for development of novel diagnostic, prognostic, and therapeutic tools. The surface-exposed proteome (SEP) of a cancerous cell includes a multifarious array of proteins critical to cellular processes such as proliferation, migration, adhesion, and inter-cellular communication. The specific aim of this study was to define a SEP profile of two validated canine OSA cell lines and a normal canine osteoblast cell line utilizing a biotinylation/streptavidin system to selectively label, purify, and identify surface-exposed proteins by mass spectrometry (MS) analysis. Additionally, we sought to validate a subset of our MS-based observations via quantitative real-time PCR, Western blot and semi-quantitative immunocytochemistry. Our hypothesis was that MS would detect differences in the SEP composition between the OSA and the normal osteoblast cells. Shotgun MS identified 133 putative surface proteins when output from all samples were combined, with good consistency between biological replicates. Eleven of the MS-detected proteins underwent analysis of gene expression by PCR, all of which were actively transcribed, but varied in expression level. Western blot of whole cell lysates from all three cell lines was effective for Thrombospondin-1, CYR61 and CD44, and indicated that all three proteins were present in each cell line. Semi-quantitative immunofluorescence indicated that CD44 was expressed at much higher levels on the surface of the OSA than the normal osteoblast cell lines. The results of the present study identified numerous differences, and similarities, in the SEP of canine OSA cell lines and normal canine osteoblasts. The PCR, Western blot, and immunocytochemistry results, for the subset of proteins evaluated, were generally supportive of the mass spectrometry data

Parallel Programming with Intel Parallel Studio XE

CERN Document Server

Blair-Chappell , Stephen

2012-01-01

Optimize code for multi-core processors with Intel's Parallel Studio Parallel programming is rapidly becoming a "must-know" skill for developers. Yet, where to start? This teach-yourself tutorial is an ideal starting point for developers who already know Windows C and C++ and are eager to add parallelism to their code. With a focus on applying tools, techniques, and language extensions to implement parallelism, this essential resource teaches you how to write programs for multicore and leverage the power of multicore in your programs. Sharing hands-on case studies and real-world examples, the

Coupling of morphology to surface transport in ion-beam-irradiated surfaces: normal incidence and rotating targets

International Nuclear Information System (INIS)

Munoz-Garcia, Javier; Cuerno, Rodolfo; Castro, Mario

2009-01-01

Continuum models have proved their applicability to describe nanopatterns produced by ion-beam sputtering of amorphous or amorphizable targets at low and medium energies. Here we pursue the recently introduced 'hydrodynamic approach' in the cases of bombardment at normal incidence, or of oblique incidence onto rotating targets, known to lead to self-organized arrangements of nanodots. Our approach stresses the dynamical roles of material (defect) transport at the target surface and of local redeposition. By applying results previously derived for arbitrary angles of incidence, we derive effective evolution equations for these geometries of incidence, which are then numerically studied. Moreover, we show that within our model these equations are identical (albeit with different coefficients) in both cases, provided surface tension is isotropic in the target. We thus account for the common dynamics for both types of incidence conditions, namely formation of dots with short-range order and long-wavelength disorder, and an intermediate coarsening of dot features that improves the local order of the patterns. We provide for the first time approximate analytical predictions for the dependence of stationary dot features (amplitude and wavelength) on phenomenological parameters, that improve upon previous linear estimates. Finally, our theoretical results are discussed in terms of experimental data.

CONTRIBUTION OF QUADRATIC RESIDUE DIFFUSERS TO EFFICIENCY OF TILTED PROFILE PARALLEL HIGHWAY NOISE BARRIERS

Directory of Open Access Journals (Sweden)

M. R. Monazzam ، P. Nassiri

2009-10-01

Full Text Available This paper presents the results of an investigation on the acoustic performance of tilted profile parallel barriers with quadratic residue diffuser (QRD tops and faces. A 2D boundary element method (BEM is used to predict the barrier insertion loss. The results of rigid and with absorptive coverage are also calculated for comparisons. Using QRD on the top surface and faces of all tilted profile parallel barrier models introduced here is found to improve the efficiency of barriers compared with rigid equivalent parallel barrier at the examined receiver positions. Applying a QRD with frequency design of 400 Hz on 5 degrees tilted parallel barrier improves the overall performance of its equivalent rigid barrier by 1.8 dB(A. Increase in the treated surfaces with reactive elements shifts the effective performance toward lower frequencies. It is found that by tilting the barriers from 0 to 10 degrees in parallel set up, the degradation effects in parallel barriers is reduced but the absorption effect of fibrous materials and also diffusivity of the quadratic residue diffuser is reduced significantly. In this case all the designed barriers have better performance with 10 degrees tilting in parallel set up. The most economic traffic noise parallel barrier which produces significantly high performance, is achieved by covering the top surface of the barrier closed to the receiver by just a QRD with frequency design of 400 Hz and tilting angle of 10 degrees. The average A-weighted insertion loss in this barrier is predicted to be 16.3 dB (A.

Parallel comparative studies on toxicity of quantum dots synthesized and surface engineered with different methods in vitro and in vivo

Directory of Open Access Journals (Sweden)

Liu F

2017-07-01

Full Text Available Fengjun Liu1,* Wen Ye1,* Jun Wang2 Fengxiang Song1 Yingsheng Cheng3 Bingbo Zhang21Department of Radiology, Shanghai Public Health Clinical Center, 2Institute of Photomedicine, Shanghai Skin Disease Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, 3Department of Radiology, Shanghai Sixth People’s Hospital, Shanghai Jiao Tong University, Shanghai, China *These authors contributed equally to this work Abstract: Quantum dots (QDs have been considered to be promising probes for biosensing, bioimaging, and diagnosis. However, their toxicity issues caused by heavy metals in QDs remain to be addressed, in particular for their in vivo biomedical applications. In this study, a parallel comparative investigation in vitro and in vivo is presented to disclose the impact of synthetic methods and their following surface modifications on the toxicity of QDs. Cellular assays after exposure to QDs were conducted including cell viability assessment, DNA breakage study in a single cellular level, intracellular reactive oxygen species (ROS receptor measurement, and transmission electron microscopy to evaluate their toxicity in vitro. Mice experiments after QD administration, including analysis of hemobiological indices, pharmacokinetics, histological examination, and body weight, were further carried out to evaluate their systematic toxicity in vivo. Results show that QDs fabricated by the thermal decomposition approach in organic phase and encapsulated by an amphiphilic polymer (denoted as QDs-1 present the least toxicity in acute damage, compared with those of QDs surface engineered by glutathione-mediated ligand exchange (denoted as QDs-2, and the ones prepared by coprecipitation approach in aqueous phase with mercaptopropionic acid capped (denoted as QDs-3. With the extension of the investigation time of mice respectively injected with QDs, we found that the damage caused by QDs to the organs can be

The island dynamics model on parallel quadtree grids

Science.gov (United States)

Mistani, Pouria; Guittet, Arthur; Bochkov, Daniil; Schneider, Joshua; Margetis, Dionisios; Ratsch, Christian; Gibou, Frederic

2018-05-01

We introduce an approach for simulating epitaxial growth by use of an island dynamics model on a forest of quadtree grids, and in a parallel environment. To this end, we use a parallel framework introduced in the context of the level-set method. This framework utilizes: discretizations that achieve a second-order accurate level-set method on non-graded adaptive Cartesian grids for solving the associated free boundary value problem for surface diffusion; and an established library for the partitioning of the grid. We consider the cases with: irreversible aggregation, which amounts to applying Dirichlet boundary conditions at the island boundary; and an asymmetric (Ehrlich-Schwoebel) energy barrier for attachment/detachment of atoms at the island boundary, which entails the use of a Robin boundary condition. We provide the scaling analyses performed on the Stampede supercomputer and numerical examples that illustrate the capability of our methodology to efficiently simulate different aspects of epitaxial growth. The combination of adaptivity and parallelism in our approach enables simulations that are several orders of magnitude faster than those reported in the recent literature and, thus, provides a viable framework for the systematic study of mound formation on crystal surfaces.

Variable field-to-normal angles in the shock foreshock boundary observed by ISEE 1 and 2

International Nuclear Information System (INIS)

Greenstadt, E.W.; Mellot, M.M.

1985-01-01

Saturated ULF waves in the foreshock, with amplitudes comparable to the magnitude of the average field, are convected by the solar wind to the quasi-parallel shock where the average field-normal angle is less than, or about, 45 0 . Several examples from ISEE 1 and 2 magnetometer data show waves that defined local, instantaneous field-normal angles very different periodically from the average. Local geometric conditions at the nominally quasi-parallel shock varied from nearly parallel to nearly perpendicular, at the periods of typical upstream waves. Clear magnetic shock transitions occurred under temporarily quasi-perpendicular geometry

Temperatures of the Ocular Surface, Lid, and Periorbital Regions of Sjögren's, Evaporative, and Aqueous-Deficient Dry Eyes Relative to Normals.

Science.gov (United States)

Abreau, Kerstin; Callan, Christine; Kottaiyan, Ranjini; Zhang, Aizhong; Yoon, Geunyoung; Aquavella, James V; Zavislan, James; Hindman, Holly B

2016-01-01

To compare the temperatures of the ocular surface, eyelid, and periorbital skin in normal eyes with Sjögren's syndrome (SS) eyes, evaporative dry eyes (EDE), and aqueous deficient dry eyes (ADDE). 10 eyes were analyzed in each age-matched group (normal, SS, EDE, and ADDE). A noninvasive infrared thermal camera captured two-dimensional images in three regions of interest (ROI) in each of three areas: the ocular surface, the upper eyelid, and the periorbital skin within a controlled environmental chamber. Mean temperatures in each ROI were calculated from the videos. Ocular surface time-segmented cooling rates were calculated over a 5-s blink interval. Relative to normal eyes, dry eyes had lower initial central OSTs (SS -0.71°C, EDE -0.55°C, ADDE -0.95°C, KW Peyes had the lowest initial central OST (Peyes had the lowest central lid temperature and lower periorbital temperatures (Pdry eye. Copyright © 2016 Elsevier Inc. All rights reserved.

State of the art of parallel scientific visualization applications on PC clusters; Etat de l'art des applications de visualisation scientifique paralleles sur grappes de PC

Energy Technology Data Exchange (ETDEWEB)

Juliachs, M

2004-07-01

In this state of the art on parallel scientific visualization applications on PC clusters, we deal with both surface and volume rendering approaches. We first analyze available PC cluster configurations and existing parallel rendering software components for parallel graphics rendering. CEA/DIF has been studying cluster visualization since 2001. This report is part of a study to set up a new visualization research platform. This platform consisting of an eight-node PC cluster under Linux and a tiled display was installed in collaboration with Versailles-Saint-Quentin University in August 2003. (author)

The Acoustic and Peceptual Effects of Series and Parallel Processing

Directory of Open Access Journals (Sweden)

Melinda C. Anderson

2009-01-01

Full Text Available Temporal envelope (TE cues provide a great deal of speech information. This paper explores how spectral subtraction and dynamic-range compression gain modifications affect TE fluctuations for parallel and series configurations. In parallel processing, algorithms compute gains based on the same input signal, and the gains in dB are summed. In series processing, output from the first algorithm forms the input to the second algorithm. Acoustic measurements show that the parallel arrangement produces more gain fluctuations, introducing more changes to the TE than the series configurations. Intelligibility tests for normal-hearing (NH and hearing-impaired (HI listeners show (1 parallel processing gives significantly poorer speech understanding than an unprocessed (UNP signal and the series arrangement and (2 series processing and UNP yield similar results. Speech quality tests show that UNP is preferred to both parallel and series arrangements, although spectral subtraction is the most preferred. No significant differences exist in sound quality between the series and parallel arrangements, or between the NH group and the HI group. These results indicate that gain modifications affect intelligibility and sound quality differently. Listeners appear to have a higher tolerance for gain modifications with regard to intelligibility, while judgments for sound quality appear to be more affected by smaller amounts of gain modification.

Xe ion beam induced rippled structures on differently oriented single-crystalline Si surfaces

Energy Technology Data Exchange (ETDEWEB)

Hanisch, Antje; Grenzer, Joerg; Facsko, Stefan [Forschungszentrum Dresden-Rossendorf, Institut fuer Ionenstrahlphysik und Materialforschung, PO Box 510119, 01314 Dresden (Germany); Biermanns, Andreas; Pietsch, Ullrich, E-mail: A.Hanisch@fzd.d [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany)

2010-03-24

We report on Xe{sup +} induced ripple formation at medium energy on single-crystalline silicon surfaces of different orientations using substrates with an intentional miscut from the [0 0 1] direction and a [1 1 1] oriented wafer. The ion beam incidence angle with respect to the surface normal was kept fixed at 65{sup 0} and the ion beam projection was parallel or perpendicular to the [1 1 0] direction. By a combination of atomic force microscopy, x-ray diffraction and high-resolution transmission electron microscopy we found that the features of the surface and subsurface rippled structures such as ripple wavelength and amplitude and the degree of order do not depend on the surface orientation as assumed in recent models of pattern formation for semiconductor surfaces. (fast track communication)

Spin currents in a normal two-dimensional electron gas in contact with a spin-orbit interaction region

International Nuclear Information System (INIS)

Sukhanov, Aleksei A; Sablikov, Vladimir A; Tkach, Yurii Ya

2009-01-01

Spin effects in a normal two-dimensional (2D) electron gas in lateral contact with a 2D region with spin-orbit interaction are studied. The peculiarity of this system is the presence of spin-dependent scattering of electrons from the interface. This results in an equilibrium edge spin current and nontrivial spin responses to a particle current. We investigate the spatial distribution of the spin currents and spin density under non-equilibrium conditions caused by a ballistic electron current flowing normal or parallel to the interface. The parallel electron current is found to generate a spin density near the interface and to change the edge spin current. The perpendicular electron current changes the edge spin current proportionally to the electron current and produces a bulk spin current penetrating deep into the normal region. This spin current has two components, one of which is directed normal to the interface and polarized parallel to it, and the second is parallel to the interface and is polarized in the plane perpendicular to the contact line. Both spin currents have a high degree of polarization (∼40-60%).

Thin-Section Diffusion-Weighted Magnetic Resonance Imaging of the Brain with Parallel Imaging

International Nuclear Information System (INIS)

Oner, A.Y.; Celik, H.; Tali, T.; Akpek, S.; Tokgoz, N.

2007-01-01

Background: Thin-section diffusion-weighted imaging (DWI) is known to improve lesion detectability, with long imaging time as a drawback. Parallel imaging (PI) is a technique that takes advantage of spatial sensitivity information inherent in an array of multiple-receiver surface coils to partially replace time-consuming spatial encoding and reduce imaging time. Purpose: To prospectively evaluate a 3-mm-thin-section DWI technique combined with PI by means of qualitative and quantitative measurements. Material and Methods: 30 patients underwent conventional echo-planar (EPI) DWI (5-mm section thickness, 1-mm intersection gap) without parallel imaging, and thin-section EPI-DWI with PI (3-mm section thickness, 0-mm intersection gap) for a b value of 1000 s/mm 2 , with an imaging time of 40 and 80 s, respectively. Signal-to-noise ratio (SNR), relative signal intensity (rSI), and apparent diffusion coefficient (ADC) values were measured over a lesion-free cerebral region on both series by two radiologists. A quality score was assigned for each set of images to assess the image quality. When a brain lesion was present, contrast-to-noise ratio (CNR) and corresponding ADC were also measured. Student t-tests were used for statistical analysis. Results: Mean SNR values of the normal brain were 33.61±4.35 and 32.98±7.19 for conventional and thin-slice DWI (P>0.05), respectively. Relative signal intensities were significantly higher on thin-section DWI (P 0.05). Quality scores and overall lesion CNR were found to be higher in thin-section DWI with parallel imaging. Conclusion: A thin-section technique combined with PI improves rSI, CNR, and image quality without compromising SNR and ADC measurements in an acceptable imaging time. Keywords: Brain; DWI; parallel imaging; thin section

Development and application of efficient strategies for parallel magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Breuer, F.

2006-07-01

Virtually all existing MRI applications require both a high spatial and high temporal resolution for optimum detection and classification of the state of disease. The main strategy to meet the increasing demands of advanced diagnostic imaging applications has been the steady improvement of gradient systems, which provide increased gradient strengths and faster switching times. Rapid imaging techniques and the advances in gradient performance have significantly reduced acquisition times from about an hour to several minutes or seconds. In order to further increase imaging speed, much higher gradient strengths and much faster switching times are required which are technically challenging to provide. In addition to significant hardware costs, peripheral neuro-stimulations and the surpassing of admissable acoustic noise levels may occur. Today's whole body gradient systems already operate just below the allowed safety levels. For these reasons, alternative strategies are needed to bypass these limitations. The greatest progress in further increasing imaging speed has been the development of multi-coil arrays and the advent of partially parallel acquisition (PPA) techniques in the late 1990's. Within the last years, parallel imaging methods have become commercially available,and are therefore ready for broad clinical use. The basic feature of parallel imaging is a scan time reduction, applicable to nearly any available MRI method, while maintaining the contrast behavior without requiring higher gradient system performance. PPA operates by allowing an array of receiver surface coils, positioned around the object under investigation, to partially replace time-consuming spatial encoding which normally is performed by switching magnetic field gradients. Using this strategy, spatial resolution can be improved given a specific imaging time, or scan times can be reduced at a given spatial resolution. Furthermore, in some cases, PPA can even be used to reduce image

Development and application of efficient strategies for parallel magnetic resonance imaging

International Nuclear Information System (INIS)

Breuer, F.

2006-01-01

Virtually all existing MRI applications require both a high spatial and high temporal resolution for optimum detection and classification of the state of disease. The main strategy to meet the increasing demands of advanced diagnostic imaging applications has been the steady improvement of gradient systems, which provide increased gradient strengths and faster switching times. Rapid imaging techniques and the advances in gradient performance have significantly reduced acquisition times from about an hour to several minutes or seconds. In order to further increase imaging speed, much higher gradient strengths and much faster switching times are required which are technically challenging to provide. In addition to significant hardware costs, peripheral neuro-stimulations and the surpassing of admissable acoustic noise levels may occur. Today's whole body gradient systems already operate just below the allowed safety levels. For these reasons, alternative strategies are needed to bypass these limitations. The greatest progress in further increasing imaging speed has been the development of multi-coil arrays and the advent of partially parallel acquisition (PPA) techniques in the late 1990's. Within the last years, parallel imaging methods have become commercially available,and are therefore ready for broad clinical use. The basic feature of parallel imaging is a scan time reduction, applicable to nearly any available MRI method, while maintaining the contrast behavior without requiring higher gradient system performance. PPA operates by allowing an array of receiver surface coils, positioned around the object under investigation, to partially replace time-consuming spatial encoding which normally is performed by switching magnetic field gradients. Using this strategy, spatial resolution can be improved given a specific imaging time, or scan times can be reduced at a given spatial resolution. Furthermore, in some cases, PPA can even be used to reduce image artifacts

Transmission Index Research of Parallel Manipulators Based on Matrix Orthogonal Degree

Science.gov (United States)

Shao, Zhu-Feng; Mo, Jiao; Tang, Xiao-Qiang; Wang, Li-Ping

2017-11-01

Performance index is the standard of performance evaluation, and is the foundation of both performance analysis and optimal design for the parallel manipulator. Seeking the suitable kinematic indices is always an important and challenging issue for the parallel manipulator. So far, there are extensive studies in this field, but few existing indices can meet all the requirements, such as simple, intuitive, and universal. To solve this problem, the matrix orthogonal degree is adopted, and generalized transmission indices that can evaluate motion/force transmissibility of fully parallel manipulators are proposed. Transmission performance analysis of typical branches, end effectors, and parallel manipulators is given to illustrate proposed indices and analysis methodology. Simulation and analysis results reveal that proposed transmission indices possess significant advantages, such as normalized finite (ranging from 0 to 1), dimensionally homogeneous, frame-free, intuitive and easy to calculate. Besides, proposed indices well indicate the good transmission region and relativity to the singularity with better resolution than the traditional local conditioning index, and provide a novel tool for kinematic analysis and optimal design of fully parallel manipulators.

Hydrogen-enriched non-premixed jet flames : analysis of the flame surface, flame normal, flame index and Wobbe index

NARCIS (Netherlands)

Ranga Dinesh, K.K.J.; Jiang, X.; Oijen, van J.A.

2014-01-01

A non-premixed impinging jet flame is studied using three-dimensional direct numerical simulation with detailed chemical kinetics in order to investigate the influence of fuel variability on flame surface, flame normal, flame index and Wobbe index for hydrogen-enriched combustion. Analyses indicate

State of the art of parallel scientific visualization applications on PC clusters; Etat de l'art des applications de visualisation scientifique paralleles sur grappes de PC

Energy Technology Data Exchange (ETDEWEB)

Juliachs, M

2004-07-01

In this state of the art on parallel scientific visualization applications on PC clusters, we deal with both surface and volume rendering approaches. We first analyze available PC cluster configurations and existing parallel rendering software components for parallel graphics rendering. CEA/DIF has been studying cluster visualization since 2001. This report is part of a study to set up a new visualization research platform. This platform consisting of an eight-node PC cluster under Linux and a tiled display was installed in collaboration with Versailles-Saint-Quentin University in August 2003. (author)

Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

Energy Technology Data Exchange (ETDEWEB)

Šindler, M., E-mail: sindler@fzu.cz [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Tesař, R. [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-121 16 Praha (Czech Republic); Koláček, J. [Institute of Physics ASCR, v. v. i., Cukrovarnická 10, CZ-162 53 Praha 6 (Czech Republic); Skrbek, L. [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, CZ-121 16 Praha (Czech Republic)

2017-02-15

Highlights: • Transmission through thin NbN film in parallel magnetic field exhibits strong anisotropic behaviour in the terahertz range. • Response for a polarisation parallel with the applied field is given as weighted sum of superconducting and normal state contributions. • Effective medium approach fails to describe response for linear polarisation perpendicular to the applied magnetic field. - Abstract: Transmission of terahertz waves through a thin layer of the superconductor NbN deposited on an anisotropic R-cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample. A significant difference is found between transmitted intensities of beams linearly polarised parallel with and perpendicular to the direction of applied magnetic field.

Momentum-energy transport from turbulence driven by parallel flow shear

International Nuclear Information System (INIS)

Dong, J.Q.; Horton, W.; Bengtson, R.D.; Li, G.X.

1994-04-01

The low frequency E x B turbulence driven by the shear in the mass flow velocity parallel to the magnetic field is studied using the fluid theory in a slab configuration with magnetic shear. Ion temperature gradient effects are taken into account. The eigenfunctions of the linear instability are asymmetric about the mode rational surfaces. Quasilinear Reynolds stress induced by such asymmetric fluctuations produces momentum and energy transport across the magnetic field. Analytic formulas for the parallel and perpendicular Reynolds stress, viscosity and energy transport coefficients are given. Experimental observations of the parallel and poloidal plasma flows on TEXT-U are presented and compared with the theoretical models

Practical parallel computing

CERN Document Server

Morse, H Stephen

1994-01-01

Practical Parallel Computing provides information pertinent to the fundamental aspects of high-performance parallel processing. This book discusses the development of parallel applications on a variety of equipment.Organized into three parts encompassing 12 chapters, this book begins with an overview of the technology trends that converge to favor massively parallel hardware over traditional mainframes and vector machines. This text then gives a tutorial introduction to parallel hardware architectures. Other chapters provide worked-out examples of programs using several parallel languages. Thi

Parallel rendering

Science.gov (United States)

Crockett, Thomas W.

1995-01-01

This article provides a broad introduction to the subject of parallel rendering, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of parallel rendering algorithms and systems. We examine the different types of parallelism and how they can be applied in rendering applications. Concepts from parallel computing, such as data decomposition, task granularity, scalability, and load balancing, are considered in relation to the rendering problem. We also explore concepts from computer graphics, such as coherence and projection, which have a significant impact on the structure of parallel rendering algorithms. Our survey covers a number of practical considerations as well, including the choice of architectural platform, communication and memory requirements, and the problem of image assembly and display. We illustrate the discussion with numerous examples from the parallel rendering literature, representing most of the principal rendering methods currently used in computer graphics.

Position Analysis of a Hybrid Serial-Parallel Manipulator in Immersion Lithography

Directory of Open Access Journals (Sweden)

Jie-jie Shao

2015-01-01

Full Text Available This paper proposes a novel hybrid serial-parallel mechanism with 6 degrees of freedom. The new mechanism combines two different parallel modules in a serial form. 3-P̲(PH parallel module is architecture of 3 degrees of freedom based on higher joints and specializes in describing two planes’ relative pose. 3-P̲SP parallel module is typical architecture which has been widely investigated in recent researches. In this paper, the direct-inverse position problems of the 3-P̲SP parallel module in the couple mixed-type mode are analyzed in detail, and the solutions are obtained in an analytical form. Furthermore, the solutions for the direct and inverse position problems of the novel hybrid serial-parallel mechanism are also derived and obtained in the analytical form. The proposed hybrid serial-parallel mechanism is applied to regulate the immersion hood’s pose in an immersion lithography system. Through measuring and regulating the pose of the immersion hood with respect to the wafer surface simultaneously, the immersion hood can track the wafer surface’s pose in real-time and the gap status is stabilized. This is another exploration to hybrid serial-parallel mechanism’s application.

Parallel computations

CERN Document Server

1982-01-01

Parallel Computations focuses on parallel computation, with emphasis on algorithms used in a variety of numerical and physical applications and for many different types of parallel computers. Topics covered range from vectorization of fast Fourier transforms (FFTs) and of the incomplete Cholesky conjugate gradient (ICCG) algorithm on the Cray-1 to calculation of table lookups and piecewise functions. Single tridiagonal linear systems and vectorized computation of reactive flow are also discussed.Comprised of 13 chapters, this volume begins by classifying parallel computers and describing techn

Parallel sorting algorithms

CERN Document Server

Akl, Selim G

1985-01-01

Parallel Sorting Algorithms explains how to use parallel algorithms to sort a sequence of items on a variety of parallel computers. The book reviews the sorting problem, the parallel models of computation, parallel algorithms, and the lower bounds on the parallel sorting problems. The text also presents twenty different algorithms, such as linear arrays, mesh-connected computers, cube-connected computers. Another example where algorithm can be applied is on the shared-memory SIMD (single instruction stream multiple data stream) computers in which the whole sequence to be sorted can fit in the

State of the art of parallel scientific visualization applications on PC clusters

International Nuclear Information System (INIS)

Juliachs, M.

2004-01-01

In this state of the art on parallel scientific visualization applications on PC clusters, we deal with both surface and volume rendering approaches. We first analyze available PC cluster configurations and existing parallel rendering software components for parallel graphics rendering. CEA/DIF has been studying cluster visualization since 2001. This report is part of a study to set up a new visualization research platform. This platform consisting of an eight-node PC cluster under Linux and a tiled display was installed in collaboration with Versailles-Saint-Quentin University in August 2003. (author)

Potential fields on the ventricular surface of the exposed dog heart during normal excitation.

Science.gov (United States)

Arisi, G; Macchi, E; Baruffi, S; Spaggiari, S; Taccardi, B

1983-06-01

We studied the normal spread of excitation on the anterior and posterior ventricular surface of open-chest dogs by recording unipolar electrograms from an array of 1124 electrodes spaced 2 mm apart. The array had the shape of the ventricular surface of the heart. The electrograms were processed by a computer and displayed as epicardial equipotential maps at 1-msec intervals. Isochrone maps also were drawn. Several new features of epicardial potential fields were identified: (1) a high number of breakthrough points; (2) the topography, apparent widths, velocities of the wavefronts and the related potential drop; (3) the topography of positive potential peaks in relation to the wavefronts. Fifteen to 24 breakthrough points were located on the anterior, and 10 to 13 on the posterior ventricular surface. Some were in previously described locations and many others in new locations. Specifically, 3 to 5 breakthrough points appeared close to the atrioventricular groove on the anterior right ventricle and 2 to 4 on the posterior heart aspect; these basal breakthrough points appeared when a large portion of ventricular surface was still unexcited. Due to the presence of numerous breakthrough points on the anterior and posterior aspect of the heart which had not previously been described, the spread of excitation on the ventricular surface was "mosaic-like," with activation wavefronts spreading in all directions, rather than radially from the two breakthrough points, as traditionally described. The positive potential peaks which lay ahead of the expanding wavefronts moved along preferential directions which were probably related to the myocardial fiber direction.

Parallel MR imaging.

Science.gov (United States)

Deshmane, Anagha; Gulani, Vikas; Griswold, Mark A; Seiberlich, Nicole

2012-07-01

Parallel imaging is a robust method for accelerating the acquisition of magnetic resonance imaging (MRI) data, and has made possible many new applications of MR imaging. Parallel imaging works by acquiring a reduced amount of k-space data with an array of receiver coils. These undersampled data can be acquired more quickly, but the undersampling leads to aliased images. One of several parallel imaging algorithms can then be used to reconstruct artifact-free images from either the aliased images (SENSE-type reconstruction) or from the undersampled data (GRAPPA-type reconstruction). The advantages of parallel imaging in a clinical setting include faster image acquisition, which can be used, for instance, to shorten breath-hold times resulting in fewer motion-corrupted examinations. In this article the basic concepts behind parallel imaging are introduced. The relationship between undersampling and aliasing is discussed and two commonly used parallel imaging methods, SENSE and GRAPPA, are explained in detail. Examples of artifacts arising from parallel imaging are shown and ways to detect and mitigate these artifacts are described. Finally, several current applications of parallel imaging are presented and recent advancements and promising research in parallel imaging are briefly reviewed. Copyright © 2012 Wiley Periodicals, Inc.

Resonant and kinematical enhancement of He scattering from LiF(001) surface and pseudosurface vibrational normal modes

International Nuclear Information System (INIS)

Nichols, W.L.; Weare, J.H.

1986-01-01

One-phonon cross sections calculated from sagittally polarized vibrational normal modes account for most salient inelastic-scattering intensities seen in He-LiF(001) and measurements published by Brusdeylins, Doak, and Toennies. We have found that most inelastic intensities which cannot be attributed to potential resonances can be explained as kinematically enhanced scattering from both surface and pseudosurface bulk modes

High-Performance Psychometrics: The Parallel-E Parallel-M Algorithm for Generalized Latent Variable Models. Research Report. ETS RR-16-34

Science.gov (United States)

von Davier, Matthias

2016-01-01

This report presents results on a parallel implementation of the expectation-maximization (EM) algorithm for multidimensional latent variable models. The developments presented here are based on code that parallelizes both the E step and the M step of the parallel-E parallel-M algorithm. Examples presented in this report include item response…

Badlands: A parallel basin and landscape dynamics model

Directory of Open Access Journals (Sweden)

T. Salles

2016-01-01

Full Text Available Over more than three decades, a number of numerical landscape evolution models (LEMs have been developed to study the combined effects of climate, sea-level, tectonics and sediments on Earth surface dynamics. Most of them are written in efficient programming languages, but often cannot be used on parallel architectures. Here, I present a LEM which ports a common core of accepted physical principles governing landscape evolution into a distributed memory parallel environment. Badlands (acronym for BAsin anD LANdscape DynamicS is an open-source, flexible, TIN-based landscape evolution model, built to simulate topography development at various space and time scales.

Parallel nanostructuring of GeSbTe film with particle mask

Energy Technology Data Exchange (ETDEWEB)

Wang, Z.B.; Hong, M.H.; Wang, Q.F.; Chong, T.C. [Data Storage Institute, DSI Building, 5 Engineering Drive 1, 117608, Singapore (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 119260, Singapore (Singapore); Luk' yanchuk, B.S.; Huang, S.M.; Shi, L.P. [Data Storage Institute, DSI Building, 5 Engineering Drive 1, 117608, Singapore (Singapore)

2004-09-01

Parallel nanostructuring of a GeSbTe film may significantly improve the recording performance in data storage. In this paper, a method that permits direct and massively parallel nanopatterning of the substrate surface by laser irradiation is investigated. Polystyrene spherical particles were deposited on the surface in a monolayer array by self-assembly. The array was then irradiated with a 248-nm KrF laser. A sub-micron nanodent array can be obtained after single-pulse irradiation. These nanodents change their shapes at different laser energies. The optical near-field distribution around the particles was calculated according to the exact solution of the light-scattering problem. The influence of the presence of the substrate on the optical near field was also studied. The mechanisms for the generation of the nanodent structures are discussed. (orig.)

Surface tree languages and parallel derivation trees

NARCIS (Netherlands)

Engelfriet, Joost

1976-01-01

The surface tree languages obtained by top-down finite state transformation of monadic trees are exactly the frontier-preserving homomorphic images of sets of derivation trees of ETOL systems. The corresponding class of tree transformation languages is therefore equal to the class of ETOL languages.

Evaluation of fault-normal/fault-parallel directions rotated ground motions for response history analysis of an instrumented six-story building

Science.gov (United States)

Kalkan, Erol; Kwong, Neal S.

2012-01-01

According to regulatory building codes in United States (for example, 2010 California Building Code), at least two horizontal ground-motion components are required for three-dimensional (3D) response history analysis (RHA) of buildings. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately (when FN and then FP are aligned with the transverse direction of the structural axes). It is assumed that this approach will lead to two sets of responses that envelope the range of possible responses over all nonredundant rotation angles. This assumption is examined here using a 3D computer model of a six-story reinforced-concrete instrumented building subjected to an ensemble of bidirectional near-fault ground motions. Peak responses of engineering demand parameters (EDPs) were obtained for rotation angles ranging from 0° through 180° for evaluating the FN/FP directions. It is demonstrated that rotating ground motions to FN/FP directions (1) does not always lead to the maximum responses over all angles, (2) does not always envelope the range of possible responses, and (3) does not provide maximum responses for all EDPs simultaneously even if it provides a maximum response for a specific EDP.

MR findings of facial nerve on oblique sagittal MRI using TMJ surface coil: normal vs peripheral facial nerve palsy

International Nuclear Information System (INIS)

Park, Yong Ok; Lee, Myeong Jun; Lee, Chang Joon; Yoo, Jeong Hyun

2000-01-01

To evaluate the findings of normal facial nerve, as seen on oblique sagittal MRI using a TMJ (temporomandibular joint) surface coil, and then to evaluate abnormal findings of peripheral facial nerve palsy. We retrospectively reviewed the MR findings of 20 patients with peripheral facial palsy and 50 normal facial nerves of 36 patients without facial palsy. All underwent oblique sagittal MRI using a T MJ surface coil. We analyzed the course, signal intensity, thickness, location, and degree of enhancement of the facial nerve. According to the angle made by the proximal parotid segment on the axis of the mastoid segment, course was classified as anterior angulation (obtuse and acute, or buckling), straight and posterior angulation. Among 50 normal facial nerves, 24 (48%) were straight, and 23 (46%) demonstrated anterior angulation; 34 (68%) showed iso signal intensity on T1W1. In the group of patients, course on the affected side was either straight (40%) or showed anterior angulation (55%), and signal intensity in 80% of cases was isointense. These findings were similar to those in the normal group, but in patients with post-traumatic or post-operative facial palsy, buckling, of course, appeared. In 12 of 18 facial palsy cases (66.6%) in which contrast materials were administered, a normal facial nerve of the opposite facial canal showed mild enhancement on more than one segment, but on the affected side the facial nerve showed diffuse enhancement in all 14 patients with acute facial palsy. Eleven of these (79%) showed fair or marked enhancement on more than one segment, and in 12 (86%), mild enhancement of the proximal parotid segment was noted. Four of six chronic facial palsy cases (66.6%) showed atrophy of the facial nerve. When oblique sagittal MR images are obtained using a TMJ surface coil, enhancement of the proximal parotid segment of the facial nerve and fair or marked enhancement of at least one segment within the facial canal always suggests pathology of

Plane-parallel biases computed from inhomogeneous Arctic clouds and sea ice

Science.gov (United States)

Rozwadowska, Anna; Cahalan, Robert F.

2002-10-01

Monte Carlo simulations of the expected influence of nonuniformity in cloud structure and surface albedo on shortwave radiative fluxes in the Arctic atmosphere are presented. In particular, plane-parallel biases in cloud albedo and transmittance are studied for nonabsorbing, low-level, all-liquid stratus clouds over sea ice. The "absolute bias" is defined as the difference between the cloud albedo or transmittance for the uniform or plane-parallel case, and the albedo or transmittance for nonuniform conditions with the same mean cloud optical thickness and the same mean surface albedo, averaged over a given area (i.e., bias > 0 means plane-parallel overestimates). Ranges of means and standard deviations of input parameters typical of Arctic conditions are determined from the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment Artic Cloud Experiment (FIRE/ACE)/Surface Heat Budget of the Arctic Ocean (SHEBA)/Atmospheric Radiation Measurement Program (ARM) experiment, a cooperative effort of the Department of Energy, NASA, NSF, the National Oceanic and Atmospheric Administration, the Office of Naval Research, and the Atmospheric Environment Service. We determine the sensitivity of the bias with respect to the following: domain averaged means and spatial variances of cloud optical thickness and surface albedo, shape of the surface reflectance function, presence of a scattering layer under the clouds, and solar zenith angle. The simulations show that the biases in Arctic conditions are generally lower than in subtropical stratocumulus. The magnitudes of the absolute biases are unlikely to exceed 0.02 for albedo and 0.05 for transmittance. The "relative bias" expresses the absolute bias as a percentage of the actual cloud albedo or transmittance. The magnitude of the relative bias in albedo is typically below 2% over the reflective Arctic surface, while the magnitude of the relative bias in transmittance can exceed 10%.

Multilayer Relaxation and Surface Energies of Metallic Surfaces

Science.gov (United States)

Bozzolo, Guillermo; Rodriguez, Agustin M.; Ferrante, John

1994-01-01

The perpendicular and parallel multilayer relaxations of fcc (210) surfaces are studied using equivalent crystal theory (ECT). A comparison with experimental and theoretical results is made for AI(210). The effect of uncertainties in the input parameters on the magnitudes and ordering of surface relaxations for this semiempirical method is estimated. A new measure of surface roughness is proposed. Predictions for the multilayer relaxations and surface energies of the (210) face of Cu and Ni are also included.

Three-Dimensional Induced Polarization Parallel Inversion Using Nonlinear Conjugate Gradients Method

Directory of Open Access Journals (Sweden)

Huan Ma

2015-01-01

Full Text Available Four kinds of array of induced polarization (IP methods (surface, borehole-surface, surface-borehole, and borehole-borehole are widely used in resource exploration. However, due to the presence of large amounts of the sources, it will take much time to complete the inversion. In the paper, a new parallel algorithm is described which uses message passing interface (MPI and graphics processing unit (GPU to accelerate 3D inversion of these four methods. The forward finite differential equation is solved by ILU0 preconditioner and the conjugate gradient (CG solver. The inverse problem is solved by nonlinear conjugate gradients (NLCG iteration which is used to calculate one forward and two “pseudo-forward” modelings and update the direction, space, and model in turn. Because each source is independent in forward and “pseudo-forward” modelings, multiprocess modes are opened by calling MPI library. The iterative matrix solver within CULA is called in each process. Some tables and synthetic data examples illustrate that this parallel inversion algorithm is effective. Furthermore, we demonstrate that the joint inversion of surface and borehole data produces resistivity and chargeability results are superior to those obtained from inversions of individual surface data.

A SPECT reconstruction method for extending parallel to non-parallel geometries

International Nuclear Information System (INIS)

Wen Junhai; Liang Zhengrong

2010-01-01

Due to its simplicity, parallel-beam geometry is usually assumed for the development of image reconstruction algorithms. The established reconstruction methodologies are then extended to fan-beam, cone-beam and other non-parallel geometries for practical application. This situation occurs for quantitative SPECT (single photon emission computed tomography) imaging in inverting the attenuated Radon transform. Novikov reported an explicit parallel-beam formula for the inversion of the attenuated Radon transform in 2000. Thereafter, a formula for fan-beam geometry was reported by Bukhgeim and Kazantsev (2002 Preprint N. 99 Sobolev Institute of Mathematics). At the same time, we presented a formula for varying focal-length fan-beam geometry. Sometimes, the reconstruction formula is so implicit that we cannot obtain the explicit reconstruction formula in the non-parallel geometries. In this work, we propose a unified reconstruction framework for extending parallel-beam geometry to any non-parallel geometry using ray-driven techniques. Studies by computer simulations demonstrated the accuracy of the presented unified reconstruction framework for extending parallel-beam to non-parallel geometries in inverting the attenuated Radon transform.

The language parallel Pascal and other aspects of the massively parallel processor

Science.gov (United States)

Reeves, A. P.; Bruner, J. D.

1982-01-01

A high level language for the Massively Parallel Processor (MPP) was designed. This language, called Parallel Pascal, is described in detail. A description of the language design, a description of the intermediate language, Parallel P-Code, and details for the MPP implementation are included. Formal descriptions of Parallel Pascal and Parallel P-Code are given. A compiler was developed which converts programs in Parallel Pascal into the intermediate Parallel P-Code language. The code generator to complete the compiler for the MPP is being developed independently. A Parallel Pascal to Pascal translator was also developed. The architecture design for a VLSI version of the MPP was completed with a description of fault tolerant interconnection networks. The memory arrangement aspects of the MPP are discussed and a survey of other high level languages is given.

Parallel Atomistic Simulations

Energy Technology Data Exchange (ETDEWEB)

HEFFELFINGER,GRANT S.

2000-01-18

Algorithms developed to enable the use of atomistic molecular simulation methods with parallel computers are reviewed. Methods appropriate for bonded as well as non-bonded (and charged) interactions are included. While strategies for obtaining parallel molecular simulations have been developed for the full variety of atomistic simulation methods, molecular dynamics and Monte Carlo have received the most attention. Three main types of parallel molecular dynamics simulations have been developed, the replicated data decomposition, the spatial decomposition, and the force decomposition. For Monte Carlo simulations, parallel algorithms have been developed which can be divided into two categories, those which require a modified Markov chain and those which do not. Parallel algorithms developed for other simulation methods such as Gibbs ensemble Monte Carlo, grand canonical molecular dynamics, and Monte Carlo methods for protein structure determination are also reviewed and issues such as how to measure parallel efficiency, especially in the case of parallel Monte Carlo algorithms with modified Markov chains are discussed.

Analysis of clinical complication data for radiation hepatitis using a parallel architecture model

International Nuclear Information System (INIS)

Jackson, A.; Haken, R.K. ten; Robertson, J.M.; Kessler, M.L.; Kutcher, G.J.; Lawrence, T.S.

1995-01-01

Purpose: The detailed knowledge of dose volume distributions available from the three-dimensional (3D) conformal radiation treatment of tumors in the liver (reported elsewhere) offers new opportunities to quantify the effect of volume on the probability of producing radiation hepatitis. We aim to test a new parallel architecture model of normal tissue complication probability (NTCP) with these data. Methods and Materials: Complication data and dose volume histograms from a total of 93 patients with normal liver function, treated on a prospective protocol with 3D conformal radiation therapy and intraarterial hepatic fluorodeoxyuridine, were analyzed with a new parallel architecture model. Patient treatment fell into six categories differing in doses delivered and volumes irradiated. By modeling the radiosensitivity of liver subunits, we are able to use dose volume histograms to calculate the fraction of the liver damaged in each patient. A complication results if this fraction exceeds the patient's functional reserve. To determine the patient distribution of functional reserves and the subunit radiosensitivity, the maximum likelihood method was used to fit the observed complication data. Results: The parallel model fit the complication data well, although uncertainties on the functional reserve distribution and subunit radiosensitivy are highly correlated. Conclusion: The observed radiation hepatitis complications show a threshold effect that can be described well with a parallel architecture model. However, additional independent studies are required to better determine the parameters defining the functional reserve distribution and subunit radiosensitivity

Parallel integer sorting with medium and fine-scale parallelism

Science.gov (United States)

Dagum, Leonardo

1993-01-01

Two new parallel integer sorting algorithms, queue-sort and barrel-sort, are presented and analyzed in detail. These algorithms do not have optimal parallel complexity, yet they show very good performance in practice. Queue-sort designed for fine-scale parallel architectures which allow the queueing of multiple messages to the same destination. Barrel-sort is designed for medium-scale parallel architectures with a high message passing overhead. The performance results from the implementation of queue-sort on a Connection Machine CM-2 and barrel-sort on a 128 processor iPSC/860 are given. The two implementations are found to be comparable in performance but not as good as a fully vectorized bucket sort on the Cray YMP.

About Parallel Programming: Paradigms, Parallel Execution and Collaborative Systems

Directory of Open Access Journals (Sweden)

Loredana MOCEAN

2009-01-01

Full Text Available In the last years, there were made efforts for delineation of a stabile and unitary frame, where the problems of logical parallel processing must find solutions at least at the level of imperative languages. The results obtained by now are not at the level of the made efforts. This paper wants to be a little contribution at these efforts. We propose an overview in parallel programming, parallel execution and collaborative systems.

Parallel computing works!

CERN Document Server

Fox, Geoffrey C; Messina, Guiseppe C

2014-01-01

A clear illustration of how parallel computers can be successfully appliedto large-scale scientific computations. This book demonstrates how avariety of applications in physics, biology, mathematics and other scienceswere implemented on real parallel computers to produce new scientificresults. It investigates issues of fine-grained parallelism relevant forfuture supercomputers with particular emphasis on hypercube architecture. The authors describe how they used an experimental approach to configuredifferent massively parallel machines, design and implement basic systemsoftware, and develop

Fast Evaluation of Segmentation Quality with Parallel Computing

Directory of Open Access Journals (Sweden)

Henry Cruz

2017-01-01

Full Text Available In digital image processing and computer vision, a fairly frequent task is the performance comparison of different algorithms on enormous image databases. This task is usually time-consuming and tedious, such that any kind of tool to simplify this work is welcome. To achieve an efficient and more practical handling of a normally tedious evaluation, we implemented the automatic detection system, with the help of MATLAB®’s Parallel Computing Toolbox™. The key parts of the system have been parallelized to achieve simultaneous execution and analysis of segmentation algorithms on the one hand and the evaluation of detection accuracy for the nonforested regions, such as a study case, on the other hand. As a positive side effect, CPU usage was reduced and processing time was significantly decreased by 68.54% compared to sequential processing (i.e., executing the system with each algorithm one by one.

The distribution of deformation in parallel fault-related folds with migrating axial surfaces: comparison between fault-propagation and fault-bend folding

Science.gov (United States)

Salvini, Francesco; Storti, Fabrizio

2001-01-01

In fault-related folds that form by axial surface migration, rocks undergo deformation as they pass through axial surfaces. The distribution and intensity of deformation in these structures has been impacted by the history of axial surface migration. Upon fold initiation, unique dip panels develop, each with a characteristic deformation intensity, depending on their history. During fold growth, rocks that pass through axial surfaces are transported between dip panels and accumulate additional deformation. By tracking the pattern of axial surface migration in model folds, we predict the distribution of relative deformation intensity in simple-step, parallel fault-bend and fault-propagation anticlines. In both cases the deformation is partitioned into unique domains we call deformation panels. For a given rheology of the folded multilayer, deformation intensity will be homogeneously distributed in each deformation panel. Fold limbs are always deformed. The flat crests of fault-propagation anticlines are always undeformed. Two asymmetric deformation panels develop in fault-propagation folds above ramp angles exceeding 29°. For lower ramp angles, an additional, more intensely-deformed panel develops at the transition between the crest and the forelimb. Deformation in the flat crests of fault-bend anticlines occurs when fault displacement exceeds the length of the footwall ramp, but is never found immediately hinterland of the crest to forelimb transition. In environments dominated by brittle deformation, our models may serve as a first-order approximation of the distribution of fractures in fault-related folds.

Transient reflection and transmission of E polarized electromagnetic waves at boundary surface between air and moving isotropic plasma

International Nuclear Information System (INIS)

Saito, Yukimasa

1977-01-01

The transient reflection and transmission waves of E polarized electromagnetic waves coming into the boundary surface between air and moving isotropic plasma were theoretically investigated. By using the Laplace transformation in the moving system, the formulae of Lorentz and inverse Lorentz transformations concerning electromagnetic field were transformed, thus the transient reflection and transmission waves were obtained. These waves were normalized with the angular frequency of the incident waves, and the variation of the wave form was obtained. Examples of the numerical calculation of reflected waves are shown for the plasma moving in parallel to the boundary surface. (Kato, T.)

Surface morphology of active normal faults in hard rock: Implications for the mechanics of the Asal Rift, Djibouti

Science.gov (United States)

Pinzuti, Paul; Mignan, Arnaud; King, Geoffrey C. P.

2010-10-01

Tectonic-stretching models have been previously proposed to explain the process of continental break-up through the example of the Asal Rift, Djibouti, one of the few places where the early stages of seafloor spreading can be observed. In these models, deformation is distributed starting at the base of a shallow seismogenic zone, in which sub-vertical normal faults are responsible for subsidence whereas cracks accommodate extension. Alternative models suggest that extension results from localised magma intrusion, with normal faults accommodating extension and subsidence only above the maximum reach of the magma column. In these magmatic rifting models, or so-called magmatic intrusion models, normal faults have dips of 45-55° and root into dikes. Vertical profiles of normal fault scarps from levelling campaign in the Asal Rift, where normal faults seem sub-vertical at surface level, have been analysed to discuss the creation and evolution of normal faults in massive fractured rocks (basalt lava flows), using mechanical and kinematics concepts. We show that the studied normal fault planes actually have an average dip ranging between 45° and 65° and are characterised by an irregular stepped form. We suggest that these normal fault scarps correspond to sub-vertical en echelon structures, and that, at greater depth, these scarps combine and give birth to dipping normal faults. The results of our analysis are compatible with the magmatic intrusion models instead of tectonic-stretching models. The geometry of faulting between the Fieale volcano and Lake Asal in the Asal Rift can be simply related to the depth of diking, which in turn can be related to magma supply. This new view supports the magmatic intrusion model of early stages of continental breaking.

Pros and cons of rotating ground motion records to fault-normal/parallel directions for response history analysis of buildings

Science.gov (United States)

Kalkan, Erol; Kwong, Neal S.

2014-01-01

According to the regulatory building codes in the United States (e.g., 2010 California Building Code), at least two horizontal ground motion components are required for three-dimensional (3D) response history analysis (RHA) of building structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHAs should be performed separately (when FN and then FP are aligned with the transverse direction of the structural axes). It is assumed that this approach will lead to two sets of responses that envelope the range of possible responses over all nonredundant rotation angles. This assumption is examined here, for the first time, using a 3D computer model of a six-story reinforced-concrete instrumented building subjected to an ensemble of bidirectional near-fault ground motions. Peak values of engineering demand parameters (EDPs) were computed for rotation angles ranging from 0 through 180° to quantify the difference between peak values of EDPs over all rotation angles and those due to FN/FP direction rotated motions. It is demonstrated that rotating ground motions to FN/FP directions (1) does not always lead to the maximum responses over all angles, (2) does not always envelope the range of possible responses, and (3) does not provide maximum responses for all EDPs simultaneously even if it provides a maximum response for a specific EDP.

Surface tension of normal and heavy water

International Nuclear Information System (INIS)

Straub, J.; Rosner, N.; Grigull, V.

1980-01-01

A Skeleton Table and simple interpolation equation for the surface tension of light water was developed by the Working Group III of the International Association for the Properties of Steam and is recommended as an International Standard. The Skeleton Table is based on all known measurements of the surface tension and individual data were weighted corresponding to the accuracy of the measurements. The form of the interpolation equation is based on a physical concept. It represents an extension of van der Waals-equation, where the exponent conforms to the 'Scaling Laws'. In addition for application purposes simple relations for the Laplace-coefficient and for the density difference between the liquid and gaseous phases of light water are given. The same form of interpolation equation for the surface tension can be used for heavy water, for which the coefficients are given. However, this equation is based only on a single set of data. (orig.) [de

F-Nets and Software Cabling: Deriving a Formal Model and Language for Portable Parallel Programming

Science.gov (United States)

DiNucci, David C.; Saini, Subhash (Technical Monitor)

1998-01-01

Parallel programming is still being based upon antiquated sequence-based definitions of the terms "algorithm" and "computation", resulting in programs which are architecture dependent and difficult to design and analyze. By focusing on obstacles inherent in existing practice, a more portable model is derived here, which is then formalized into a model called Soviets which utilizes a combination of imperative and functional styles. This formalization suggests more general notions of algorithm and computation, as well as insights into the meaning of structured programming in a parallel setting. To illustrate how these principles can be applied, a very-high-level graphical architecture-independent parallel language, called Software Cabling, is described, with many of the features normally expected from today's computer languages (e.g. data abstraction, data parallelism, and object-based programming constructs).

Characterizing the adhesion of motile and nonmotile Escherichia coli to a glass surface using a parallel-plate flow chamber.

Science.gov (United States)

McClaine, Jennifer W; Ford, Roseanne M

2002-04-20

A parallel-plate flow chamber was used to measure the attachment and detachment rates of Escherichia coli to a glass surface at various fluid velocities. The effect of flagella on adhesion was investigated by performing experiments with several E. coli strains: AW405 (motile); HCB136 (nonmotile mutant with paralyzed flagella); and HCB137 (nonmotile mutant without flagella). We compared the total attachment rates and the fraction of bacteria retained on the surface to determine how the presence and movement of the flagella influence transport to the surface and adhesion strength in this dynamic system. At the lower fluid velocities, there was no significant difference in the total attachment rates for the three bacterial strains; nonmotile strains settled at a rate that was of the same order of magnitude as the diffusion rate of the motile strain. At the highest fluid velocity, the effect of settling was minimized to better illustrate the importance of motility, and the attachment rates of both nonmotile strains were approximately five times slower than that of the motile bacteria. Thus, different processes controlled the attachment rate depending on the parameter regime in which the experiment was performed. The fractions of motile bacteria retained on the glass surface increased with increasing velocity, whereas the opposite trend was found for the nonmotile strains. This suggests that the rotation of the flagella enables cells to detach from the surface (at the lower fluid velocities) and strengthens adhesion (at higher fluid velocities), whereas nonmotile cells detach as a result of shear. There was no significant difference in the initial attachment rates of the two nonmotile species, which suggests that merely the presence of flagella was not important in this stage of biofilm development. Copyright 2002 Wiley Periodicals, Inc.

Endpoint-based parallel data processing in a parallel active messaging interface of a parallel computer

Science.gov (United States)

Archer, Charles J.; Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

2014-08-12

Endpoint-based parallel data processing in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes coupled for data communications through the PAMI, including establishing a data communications geometry, the geometry specifying, for tasks representing processes of execution of the parallel application, a set of endpoints that are used in collective operations of the PAMI including a plurality of endpoints for one of the tasks; receiving in endpoints of the geometry an instruction for a collective operation; and executing the instruction for a collective operation through the endpoints in dependence upon the geometry, including dividing data communications operations among the plurality of endpoints for one of the tasks.

New Parallel Algorithms for Landscape Evolution Model

Science.gov (United States)

Jin, Y.; Zhang, H.; Shi, Y.

2017-12-01

Most landscape evolution models (LEM) developed in the last two decades solve the diffusion equation to simulate the transportation of surface sediments. This numerical approach is difficult to parallelize due to the computation of drainage area for each node, which needs huge amount of communication if run in parallel. In order to overcome this difficulty, we developed two parallel algorithms for LEM with a stream net. One algorithm handles the partition of grid with traditional methods and applies an efficient global reduction algorithm to do the computation of drainage areas and transport rates for the stream net; the other algorithm is based on a new partition algorithm, which partitions the nodes in catchments between processes first, and then partitions the cells according to the partition of nodes. Both methods focus on decreasing communication between processes and take the advantage of massive computing techniques, and numerical experiments show that they are both adequate to handle large scale problems with millions of cells. We implemented the two algorithms in our program based on the widely used finite element library deal.II, so that it can be easily coupled with ASPECT.

Bioinformatics algorithm based on a parallel implementation of a machine learning approach using transducers

International Nuclear Information System (INIS)

Roche-Lima, Abiel; Thulasiram, Ruppa K

2012-01-01

Finite automata, in which each transition is augmented with an output label in addition to the familiar input label, are considered finite-state transducers. Transducers have been used to analyze some fundamental issues in bioinformatics. Weighted finite-state transducers have been proposed to pairwise alignments of DNA and protein sequences; as well as to develop kernels for computational biology. Machine learning algorithms for conditional transducers have been implemented and used for DNA sequence analysis. Transducer learning algorithms are based on conditional probability computation. It is calculated by using techniques, such as pair-database creation, normalization (with Maximum-Likelihood normalization) and parameters optimization (with Expectation-Maximization - EM). These techniques are intrinsically costly for computation, even worse when are applied to bioinformatics, because the databases sizes are large. In this work, we describe a parallel implementation of an algorithm to learn conditional transducers using these techniques. The algorithm is oriented to bioinformatics applications, such as alignments, phylogenetic trees, and other genome evolution studies. Indeed, several experiences were developed using the parallel and sequential algorithm on Westgrid (specifically, on the Breeze cluster). As results, we obtain that our parallel algorithm is scalable, because execution times are reduced considerably when the data size parameter is increased. Another experience is developed by changing precision parameter. In this case, we obtain smaller execution times using the parallel algorithm. Finally, number of threads used to execute the parallel algorithm on the Breezy cluster is changed. In this last experience, we obtain as result that speedup is considerably increased when more threads are used; however there is a convergence for number of threads equal to or greater than 16.

The Parallel SBAS-DInSAR algorithm: an effective and scalable tool for Earth's surface displacement retrieval

Science.gov (United States)

Zinno, Ivana; De Luca, Claudio; Elefante, Stefano; Imperatore, Pasquale; Manunta, Michele; Casu, Francesco

2014-05-01

been carried out on real data acquired by ENVISAT and COSMO-SkyMed sensors. Moreover, the P-SBAS performances with respect to the size of the input dataset will also be investigated. This kind of analysis is essential for assessing the goodness of the P-SBAS algorithm and gaining insight into its applicability to different scenarios. Besides, such results will also become crucial to identify and evaluate how to appropriately exploit P-SBAS to process the forthcoming large Sentinel-1 data stream. References [1] Massonnet, D., Briole, P., Arnaud, A., "Deflation of Mount Etna monitored by Spaceborne Radar Interferometry", Nature, vol. 375, pp. 567-570, 1995. [2] Berardino, P., G. Fornaro, R. Lanari, and E. Sansosti, "A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms", IEEE Trans. Geosci. Remote Sens., vol. 40, no. 11, pp. 2375-2383, Nov. 2002. [3] Elefante, S., Imperatore, P. , Zinno, I., M. Manunta, E. Mathot, F. Brito, J. Farres, W. Lengert, R. Lanari, F. Casu, "SBAS-DINSAR Time series generation on cloud computing platforms", IEEE IGARSS 2013, July 2013, Melbourne (AU). [4] Zinno, P. Imperatore, S. Elefante, F. Casu, M. Manunta, E. Mathot, F. Brito, J. Farres, W. Lengert, R. Lanari, "A Novel Parallel Computational Framework for Processing Large INSAR Data Sets", Living Planet Symposium 2013, Sept. 9-13, 2013.

Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

International Nuclear Information System (INIS)

Xie Tao; Zhao Shang-Zhuo; Fang He; Yu Wen-Jin; He Yi-Jun; Perrie, William

2016-01-01

Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. (paper)

Parallel phase model : a programming model for high-end parallel machines with manycores.

Energy Technology Data Exchange (ETDEWEB)

Wu, Junfeng (Syracuse University, Syracuse, NY); Wen, Zhaofang; Heroux, Michael Allen; Brightwell, Ronald Brian

2009-04-01

This paper presents a parallel programming model, Parallel Phase Model (PPM), for next-generation high-end parallel machines based on a distributed memory architecture consisting of a networked cluster of nodes with a large number of cores on each node. PPM has a unified high-level programming abstraction that facilitates the design and implementation of parallel algorithms to exploit both the parallelism of the many cores and the parallelism at the cluster level. The programming abstraction will be suitable for expressing both fine-grained and coarse-grained parallelism. It includes a few high-level parallel programming language constructs that can be added as an extension to an existing (sequential or parallel) programming language such as C; and the implementation of PPM also includes a light-weight runtime library that runs on top of an existing network communication software layer (e.g. MPI). Design philosophy of PPM and details of the programming abstraction are also presented. Several unstructured applications that inherently require high-volume random fine-grained data accesses have been implemented in PPM with very promising results.

Systematic approach for deriving feasible mappings of parallel algorithms to parallel computing platforms

NARCIS (Netherlands)

Arkin, Ethem; Tekinerdogan, Bedir; Imre, Kayhan M.

2017-01-01

The need for high-performance computing together with the increasing trend from single processor to parallel computer architectures has leveraged the adoption of parallel computing. To benefit from parallel computing power, usually parallel algorithms are defined that can be mapped and executed

Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

Energy Technology Data Exchange (ETDEWEB)

Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Grimaldi, M.G.

2013-06-01

We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced.

Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

International Nuclear Information System (INIS)

Ruffino, F.; Grimaldi, M.G.

2013-01-01

We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced

Ultrasonic off-normal imaging techniques for under sodium viewing

International Nuclear Information System (INIS)

Michaels, T.E.; Horn, J.E.

1979-01-01

Advanced imaging methods have been evaluated for the purpose of constructing images of objects from ultrasonic data. Feasibility of imaging surfaces which are off-normal to the sound beam has been established. Laboratory results are presented which show a complete image of a typical core component. Using the previous system developed for under sodium viewing (USV), only normal surfaces of this object could be imaged. Using advanced methods, surfaces up to 60 degrees off-normal have been imaged. Details of equipment and procedures used for this image construction are described. Additional work on high temperature transducers, electronics, and signal analysis is required in order to adapt the off-normal viewing process described here to an eventual USV application

A surface embossing technique to create micro-grooves on an aluminum fin stock for drainage enhancement

International Nuclear Information System (INIS)

Liu Liping; Jacobi, Anthony M; Chvedov, Dmitri

2009-01-01

Recent advances using a surface embossing technique allow us to inexpensively impart micro-scale surface features on heat exchanger construction material, which we exploit to reduce condensate retention. The retention of condensate is important to the performance of heat exchangers in a broad range of air-cooling and dehumidification applications. We report a study of wetting behavior and drainage performance on a series of embossed surfaces with different micro-groove dimensions. Static contact angles, critical sliding angles, droplet aspect ratios, etc, are reported with detailed surface topographical information. Our results show that unless the spacing between grooves is very large (>100 µm), the parallel-grooved surface feature normally increases the apparent contact angle of a droplet on the surface. The micro-groove structure causes anisotropic wetting behavior of the droplets, and apparent contact angles measured by viewing along with the micro-grooves (θ p erpendicular) were found to be larger than those measured from the other direction (θ || ) (by viewing perpendicular to the grooves). A consistent reduction of a critical sliding angle was observed on surfaces after embossing (the micro-grooves are aligned to be parallel with gravity). This may be due to contact line discontinuities and contact-line pinning induced by a groove structure of the surface. Water droplets exhibit an elongated shape along the micro-grooves, which is in contrast to the nearly circular base contour observed on an isotropic surface. Smaller groove spacing, larger depth and steeper sidewalls are observed to be favorable for drainage enhancement and recommended as design guidelines in the future

Parallel algorithms

CERN Document Server

Casanova, Henri; Robert, Yves

2008-01-01

""…The authors of the present book, who have extensive credentials in both research and instruction in the area of parallelism, present a sound, principled treatment of parallel algorithms. … This book is very well written and extremely well designed from an instructional point of view. … The authors have created an instructive and fascinating text. The book will serve researchers as well as instructors who need a solid, readable text for a course on parallelism in computing. Indeed, for anyone who wants an understandable text from which to acquire a current, rigorous, and broad vi

Surface Spectroscopic Signatures of Mechanical Deformation in HDPE.

Science.gov (United States)

Averett, Shawn C; Stanley, Steven K; Hanson, Joshua J; Smith, Stacey J; Patterson, James E

2018-01-01

High-density polyethylene (HDPE) has been extensively studied, both as a model for semi-crystalline polymers and because of its own industrial utility. During cold drawing, crystalline regions of HDPE are known to break up and align with the direction of tensile load. Structural changes due to deformation should also manifest at the surface of the polymer, but until now, a detailed molecular understanding of how the surface responds to mechanical deformation has been lacking. This work establishes a precedent for using vibrational sum-frequency generation (VSFG) spectroscopy to investigate changes in the molecular-level structure of the surface of HDPE after cold drawing. X-ray diffraction (XRD) was used to confirm that the observed surface behavior corresponds to the expected bulk response. Before tensile loading, the VSFG spectra indicate that there is significant variability in the surface structure and tilt of the methylene groups away from the surface normal. After deformation, the VSFG spectroscopic signatures are notably different. These changes suggest that hydrocarbon chains at the surface of visibly necked HDPE are aligned with the direction of loading, while the associated methylene groups are oriented with the local C 2 v symmetry axis roughly parallel to the surface normal. Small amounts of unaltered material are also found at the surface of necked HDPE, with the relative amount of unaltered material decreasing as the amount of deformation increases. Aspects of the nonresonant SFG response in the transition zone between necked and undeformed polymer provide additional insight into the deformation process and may provide the first indication of mechanical deformation. Nonlinear surface spectroscopy can thus be used as a noninvasive and nondestructive tool to probe the stress history of a HPDE sample in situations where X-ray techniques are not available or not applicable. Vibrational sum-frequency generation thus has great potential as a platform for

PFLOTRAN User Manual: A Massively Parallel Reactive Flow and Transport Model for Describing Surface and Subsurface Processes

Energy Technology Data Exchange (ETDEWEB)

Lichtner, Peter C. [OFM Research, Redmond, WA (United States); Hammond, Glenn E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Chuan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bisht, Gautam [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Andre, Benjamin [National Center for Atmospheric Research, Boulder, CO (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mills, Richard [Intel Corporation, Portland, OR (United States); Univ. of Tennessee, Knoxville, TN (United States); Kumar, Jitendra [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-01-20

PFLOTRAN solves a system of generally nonlinear partial differential equations describing multi-phase, multicomponent and multiscale reactive flow and transport in porous materials. The code is designed to run on massively parallel computing architectures as well as workstations and laptops (e.g. Hammond et al., 2011). Parallelization is achieved through domain decomposition using the PETSc (Portable Extensible Toolkit for Scientific Computation) libraries for the parallelization framework (Balay et al., 1997). PFLOTRAN has been developed from the ground up for parallel scalability and has been run on up to 218 processor cores with problem sizes up to 2 billion degrees of freedom. Written in object oriented Fortran 90, the code requires the latest compilers compatible with Fortran 2003. At the time of this writing this requires gcc 4.7.x, Intel 12.1.x and PGC compilers. As a requirement of running problems with a large number of degrees of freedom, PFLOTRAN allows reading input data that is too large to fit into memory allotted to a single processor core. The current limitation to the problem size PFLOTRAN can handle is the limitation of the HDF5 file format used for parallel IO to 32 bit integers. Noting that 2³² = 4; 294; 967; 296, this gives an estimate of the maximum problem size that can be currently run with PFLOTRAN. Hopefully this limitation will be remedied in the near future.

Implementation of QR up- and downdating on a massively parallel |computer

DEFF Research Database (Denmark)

Bendtsen, Claus; Hansen, Per Christian; Madsen, Kaj

1995-01-01

We describe an implementation of QR up- and downdating on a massively parallel computer (the Connection Machine CM-200) and show that the algorithm maps well onto the computer. In particular, we show how the use of corrected semi-normal equations for downdating can be efficiently implemented. We...... also illustrate the use of our algorithms in a new LP algorithm....

The parallel dynamics of drift wave turbulence in the WEGA stellarator

Energy Technology Data Exchange (ETDEWEB)

Marsen, S; Endler, M; Otte, M; Wagner, F, E-mail: stefan.marsen@ipp.mpg.d [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Wendelsteinstrasse 1, 17491 Greifswald (Germany)

2009-08-15

The three-dimensional structure of turbulence in the edge (inside the last closed flux surface) of the WEGA stellarator is studied focusing on the parallel dynamics. WEGA as a small stellarator with moderate plasma parameters offers the opportunity to study turbulence with Langmuir probes providing high spatial and temporal resolution. Multiple probes with radial, poloidal and toroidal resolution are used to measure density fluctuations. Correlation analysis is used to reconstruct a 3D picture of turbulent structures. We find that these structures originate predominantly on the low field side and have a three-dimensional character with a finite averaged parallel wavenumber. The ratio between the parallel and perpendicular wavenumber component is in the order of 10{sup -2}. The parallel dynamics are compared at magnetic inductions of 57 and 500 mT. At 500 mT, the parallel wavelength is in the order of the field line connection length 2{pi}R{iota}-bar. A frequency resolved measure of k{sub ||}/k{sub {theta}} shows a constant ratio in this case. At 57 mT the observed k{sub ||} is much smaller than at 500 mT. However, the observed small average value is due to an averaging over positive and negative components pointing parallel and antiparallel to the magnetic field vector.

Flux pinning and critical current in layered type-II superconductors in parallel magnetic fields

International Nuclear Information System (INIS)

Prokic, V.; Davidovic, D.; Dobrosavljevic-Grujic, L.

1995-01-01

We have shown, within the Ginzburg-Landau theory, that the interaction between vortices and normal-metal layers in high-T c superconductor--normal-metal superlattices can cause high critical-current densities j c . The interaction is primarily magnetic, except at very low temperatures T, where the core interaction is dominant. For a lattice of vortices commensurate with an array of normal-metal layers in a parallel magnetic field H, strong magnetic pinning is obtained, with a nonmonotonic critical-current dependence on H, and with j c of the order of 10 7 --10 8 A/cm 2

SU-F-J-146: Experimental Validation of 6 MV Photon PDD in Parallel Magnetic Field Calculated by EGSnrc

Energy Technology Data Exchange (ETDEWEB)

Ghila, A; Steciw, S; Fallone, B; Rathee, S [Cross Cancer Institute, Edmonton, AB (Canada)

2016-06-15

Purpose: Integrated linac-MR systems are uniquely suited for real time tumor tracking during radiation treatment. Understanding the magnetic field dose effects and incorporating them in treatment planning is paramount for linac-MR clinical implementation. We experimentally validated the EGSnrc dose calculations in the presence of a magnetic field parallel to the radiation beam travel. Methods: Two cylindrical bore electromagnets produced a 0.21 T magnetic field parallel to the central axis of a 6 MV photon beam. A parallel plate ion chamber was used to measure the PDD in a polystyrene phantom, placed inside the bore in two setups: phantom top surface coinciding with the magnet bore center (183 cm SSD), and with the magnet bore’s top surface (170 cm SSD). We measured the field of the magnet at several points and included the exact dimensions of the coils to generate a 3D magnetic field map in a finite element model. BEAMnrc and DOSXYZnrc simulated the PDD experiments in parallel magnetic field (i.e. 3D magnetic field included) and with no magnetic field. Results: With the phantom surface at the top of the electromagnet, the surface dose increased by 10% (compared to no-magnetic field), due to electrons being focused by the smaller fringe fields of the electromagnet. With the phantom surface at the bore center, the surface dose increased by 30% since extra 13 cm of air column was in relatively higher magnetic field (>0.13T) in the magnet bore. EGSnrc Monte Carlo code correctly calculated the radiation dose with and without the magnetic field, and all points passed the 2%, 2 mm Gamma criterion when the ion chamber’s entrance window and air cavity were included in the simulated phantom. Conclusion: A parallel magnetic field increases the surface and buildup dose during irradiation. The EGSnrc package can model these magnetic field dose effects accurately. Dr. Fallone is a co-founder and CEO of MagnetTx Oncology Solutions (under discussions to license Alberta bi

Patterns of pulmonary maturation in normal and abnormal pregnancy.

Science.gov (United States)

Goldkrand, J W; Slattery, D S

1979-03-01

Fetal pulmonary maturation may be a variable event depending on various feto-maternal environmental and biochemical influences. The patterns of maturation were studied in 211 amniotic fluid samples from 123 patients (normal 55; diabetes 23; Rh sensitization 19; preeclampsia 26). The phenomenon of globule formation from the amniotic fluid lipid extract and is relation to pulmonary maturity was utilized for this analysis. Validation of this technique is presented. A normal curve was constructed from 22 to 42 weeks; gestation and compared to the abnormal pregnancies. Patients with class A, B, and C diabetes and Rh-sensitized pregnancies had delayed pulmonary maturation. Patients with class D diabetes and preclampsia paralleled the normal course of maturation. A discussion of these results and their possible cause is presented.

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

Science.gov (United States)

Maeda, Yoshitaka; Urata, Shinya; Nakai, Hideo; Takeuchi, Yuuya; Yun, Kyyoul; Yanase, Shunji; Okazaki, Yasuo

2017-05-01

In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D) magnetic properties (properties under the arbitrary alternating and the rotating flux conditions) of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

A parallel form of the Gudjonsson Suggestibility Scale.

Science.gov (United States)

Gudjonsson, G H

1987-09-01

The purpose of this study is twofold: (1) to present a parallel form of the Gudjonsson Suggestibility Scale (GSS, Form 1); (2) to study test-retest reliabilities of interrogative suggestibility. Three groups of subjects were administered the two suggestibility scales in a counterbalanced order. Group 1 (28 normal subjects) and Group 2 (32 'forensic' patients) completed both scales within the same testing session, whereas Group 3 (30 'forensic' patients) completed the two scales between one week and eight months apart. All the correlations were highly significant, giving support for high 'temporal consistency' of interrogative suggestibility.

Parallel algorithms for mapping pipelined and parallel computations

Science.gov (United States)

Nicol, David M.

1988-01-01

Many computational problems in image processing, signal processing, and scientific computing are naturally structured for either pipelined or parallel computation. When mapping such problems onto a parallel architecture it is often necessary to aggregate an obvious problem decomposition. Even in this context the general mapping problem is known to be computationally intractable, but recent advances have been made in identifying classes of problems and architectures for which optimal solutions can be found in polynomial time. Among these, the mapping of pipelined or parallel computations onto linear array, shared memory, and host-satellite systems figures prominently. This paper extends that work first by showing how to improve existing serial mapping algorithms. These improvements have significantly lower time and space complexities: in one case a published O(nm sup 3) time algorithm for mapping m modules onto n processors is reduced to an O(nm log m) time complexity, and its space requirements reduced from O(nm sup 2) to O(m). Run time complexity is further reduced with parallel mapping algorithms based on these improvements, which run on the architecture for which they create the mappings.

Radiation-Induced Changes in Normal-Appearing White Matter in Patients With Cerebral Tumors: A Diffusion Tensor Imaging Study

International Nuclear Information System (INIS)

Nagesh, Vijaya; Tsien, Christina I.; Chenevert, Thomas L.; Ross, Brian D.; Lawrence, Theodore S.; Junick, Larry; Cao Yue

2008-01-01

Purpose: To quantify the radiation-induced changes in normal-appearing white matter before, during, and after radiotherapy (RT) in cerebral tumor patients. Methods and Materials: Twenty-five patients with low-grade glioma, high-grade glioma, or benign tumor treated with RT were studied using diffusion tensor magnetic resonance imaging. The biologically corrected doses ranged from 50 to 81 Gy. The temporal changes were assessed before, during, and to 45 weeks after the start of RT. The mean diffusivity of water ( ), fractional anisotropy of diffusion, diffusivity perpendicular (λ perpendicular ) and parallel (λ parallel ) to white matter fibers were calculated in normal-appearing genu and splenium of the corpus callosum. Results: In the genu and splenium, fractional anisotropy decreased and , λ parallel , λ -perpendicular increased linearly and significantly with time (p -perpendicular had increased ∼30% in the genu and splenium, and λ parallel had increased 5% in the genu and 9% in the splenium, suggesting that demyelination is predominant. The increases in λ perpendicular and λ parallel were dose dependent, starting at 3 weeks and continuing to 32 weeks from the start of RT. The dose-dependent increase in λ perpendicular and λ parallel was not sustained after 32 weeks, indicating the transition from focal to diffuse effects. Conclusion: The acute and subacute changes in normal-appearing white matter fibers indicate radiation-induced demyelination and mild structural degradation of axonal fibers. The structural changes after RT are progressive, with early dose-dependent demyelination and subsequent diffuse dose-independent demyelination and mild axonal degradation. Diffusion tensor magnetic resonance imaging is potentially a biomarker for the assessment of radiation-induced white matter injury

A parallelized three-dimensional cellular automaton model for grain growth during additive manufacturing

Science.gov (United States)

Lian, Yanping; Lin, Stephen; Yan, Wentao; Liu, Wing Kam; Wagner, Gregory J.

2018-05-01

In this paper, a parallelized 3D cellular automaton computational model is developed to predict grain morphology for solidification of metal during the additive manufacturing process. Solidification phenomena are characterized by highly localized events, such as the nucleation and growth of multiple grains. As a result, parallelization requires careful treatment of load balancing between processors as well as interprocess communication in order to maintain a high parallel efficiency. We give a detailed summary of the formulation of the model, as well as a description of the communication strategies implemented to ensure parallel efficiency. Scaling tests on a representative problem with about half a billion cells demonstrate parallel efficiency of more than 80% on 8 processors and around 50% on 64; loss of efficiency is attributable to load imbalance due to near-surface grain nucleation in this test problem. The model is further demonstrated through an additive manufacturing simulation with resulting grain structures showing reasonable agreement with those observed in experiments.

A parallelized three-dimensional cellular automaton model for grain growth during additive manufacturing

Science.gov (United States)

Lian, Yanping; Lin, Stephen; Yan, Wentao; Liu, Wing Kam; Wagner, Gregory J.

2018-01-01

In this paper, a parallelized 3D cellular automaton computational model is developed to predict grain morphology for solidification of metal during the additive manufacturing process. Solidification phenomena are characterized by highly localized events, such as the nucleation and growth of multiple grains. As a result, parallelization requires careful treatment of load balancing between processors as well as interprocess communication in order to maintain a high parallel efficiency. We give a detailed summary of the formulation of the model, as well as a description of the communication strategies implemented to ensure parallel efficiency. Scaling tests on a representative problem with about half a billion cells demonstrate parallel efficiency of more than 80% on 8 processors and around 50% on 64; loss of efficiency is attributable to load imbalance due to near-surface grain nucleation in this test problem. The model is further demonstrated through an additive manufacturing simulation with resulting grain structures showing reasonable agreement with those observed in experiments.

Parallel computing works

Energy Technology Data Exchange (ETDEWEB)

1991-10-23

An account of the Caltech Concurrent Computation Program (C{sup 3}P), a five year project that focused on answering the question: Can parallel computers be used to do large-scale scientific computations '' As the title indicates, the question is answered in the affirmative, by implementing numerous scientific applications on real parallel computers and doing computations that produced new scientific results. In the process of doing so, C{sup 3}P helped design and build several new computers, designed and implemented basic system software, developed algorithms for frequently used mathematical computations on massively parallel machines, devised performance models and measured the performance of many computers, and created a high performance computing facility based exclusively on parallel computers. While the initial focus of C{sup 3}P was the hypercube architecture developed by C. Seitz, many of the methods developed and lessons learned have been applied successfully on other massively parallel architectures.

Parallel time domain solvers for electrically large transient scattering problems

KAUST Repository

Liu, Yang

2014-09-26

Marching on in time (MOT)-based integral equation solvers represent an increasingly appealing avenue for analyzing transient electromagnetic interactions with large and complex structures. MOT integral equation solvers for analyzing electromagnetic scattering from perfect electrically conducting objects are obtained by enforcing electric field boundary conditions and implicitly time advance electric surface current densities by iteratively solving sparse systems of equations at all time steps. Contrary to finite difference and element competitors, these solvers apply to nonlinear and multi-scale structures comprising geometrically intricate and deep sub-wavelength features residing atop electrically large platforms. Moreover, they are high-order accurate, stable in the low- and high-frequency limits, and applicable to conducting and penetrable structures represented by highly irregular meshes. This presentation reviews some recent advances in the parallel implementations of time domain integral equation solvers, specifically those that leverage multilevel plane-wave time-domain algorithm (PWTD) on modern manycore computer architectures including graphics processing units (GPUs) and distributed memory supercomputers. The GPU-based implementation achieves at least one order of magnitude speedups compared to serial implementations while the distributed parallel implementation are highly scalable to thousands of compute-nodes. A distributed parallel PWTD kernel has been adopted to solve time domain surface/volume integral equations (TDSIE/TDVIE) for analyzing transient scattering from large and complex-shaped perfectly electrically conducting (PEC)/dielectric objects involving ten million/tens of millions of spatial unknowns.

Surface roughening of silicon, thermal silicon dioxide, and low-k dielectric coral films in argon plasma

International Nuclear Information System (INIS)

Yin Yunpeng; Sawin, Herbert H.

2008-01-01

The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO 2 ), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followed the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide

SequenceL: Automated Parallel Algorithms Derived from CSP-NT Computational Laws

Science.gov (United States)

Cooke, Daniel; Rushton, Nelson

2013-01-01

With the introduction of new parallel architectures like the cell and multicore chips from IBM, Intel, AMD, and ARM, as well as the petascale processing available for highend computing, a larger number of programmers will need to write parallel codes. Adding the parallel control structure to the sequence, selection, and iterative control constructs increases the complexity of code development, which often results in increased development costs and decreased reliability. SequenceL is a high-level programming language that is, a programming language that is closer to a human s way of thinking than to a machine s. Historically, high-level languages have resulted in decreased development costs and increased reliability, at the expense of performance. In recent applications at JSC and in industry, SequenceL has demonstrated the usual advantages of high-level programming in terms of low cost and high reliability. SequenceL programs, however, have run at speeds typically comparable with, and in many cases faster than, their counterparts written in C and C++ when run on single-core processors. Moreover, SequenceL is able to generate parallel executables automatically for multicore hardware, gaining parallel speedups without any extra effort from the programmer beyond what is required to write the sequen tial/singlecore code. A SequenceL-to-C++ translator has been developed that automatically renders readable multithreaded C++ from a combination of a SequenceL program and sample data input. The SequenceL language is based on two fundamental computational laws, Consume-Simplify- Produce (CSP) and Normalize-Trans - pose (NT), which enable it to automate the creation of parallel algorithms from high-level code that has no annotations of parallelism whatsoever. In our anecdotal experience, SequenceL development has been in every case less costly than development of the same algorithm in sequential (that is, single-core, single process) C or C++, and an order of magnitude less

Template based parallel checkpointing in a massively parallel computer system

Science.gov (United States)

Archer, Charles Jens [Rochester, MN; Inglett, Todd Alan [Rochester, MN

2009-01-13

A method and apparatus for a template based parallel checkpoint save for a massively parallel super computer system using a parallel variation of the rsync protocol, and network broadcast. In preferred embodiments, the checkpoint data for each node is compared to a template checkpoint file that resides in the storage and that was previously produced. Embodiments herein greatly decrease the amount of data that must be transmitted and stored for faster checkpointing and increased efficiency of the computer system. Embodiments are directed to a parallel computer system with nodes arranged in a cluster with a high speed interconnect that can perform broadcast communication. The checkpoint contains a set of actual small data blocks with their corresponding checksums from all nodes in the system. The data blocks may be compressed using conventional non-lossy data compression algorithms to further reduce the overall checkpoint size.

Surface Aggregation of Candida albicans on Glass in the Absence and Presence of Adhering Streptococcus gordonii in a Parallel-Plate Flow Chamber: A Surface Thermodynamical Analysis Based on Acid-Base Interactions.

Science.gov (United States)

Millsap; Bos; Busscher; van der Mei HC

1999-04-15

Adhesive interactions between yeasts and bacteria are important in the maintenance of infectious mixed biofilms on natural and biomaterial surfaces in the human body. In this study, the extended DLVO (Derjaguin-Landau-Verwey-Overbeek) approach has been applied to explain adhesive interactions between C. albicans ATCC 10261 and S. gordonii NCTC 7869 adhering on glass. Contact angles with different liquids and the zeta potentials of both the yeasts and bacteria were determined and their adhesive interactions were measured in a parallel-plate flow chamber.Streptococci were first allowed to adhere to the bottom glass plate of the flow chamber to different seeding densities, and subsequently deposition of yeasts was monitored with an image analysis system, yielding the degree of initial surface aggregation of the adhering yeasts and their spatial arrangement in a stationary end point. Irrespective of growth temperature, the yeast cells appeared uncharged in TNMC buffer, but yeasts grown at 37 degrees C were intrinsically more hydrophilic and had an increased electron-donating character than cells grown at 30 degrees C. All yeasts showed surface aggregation due to attractive Lifshitz-van der Waals forces. In addition, acid-base interactions between yeasts, yeasts and the glass substratum, and yeasts and the streptococci were attractive for yeasts grown at 30 degrees C, but yeasts grown at 37 degrees C only had favorable acid-base interactions with the bacteria, explaining the positive relationship between the surface coverage of the glass by streptococci and the surface aggregation of the yeasts. Copyright 1999 Academic Press.

Fourier-transform infrared anisotropy in cross and parallel sections of tendon and articular cartilage

Directory of Open Access Journals (Sweden)

Bidthanapally Aruna

2008-10-01

Full Text Available Abstract Background Fourier Transform Infrared Imaging (FTIRI is used to investigate the amide anisotropies at different surfaces of a three-dimensional cartilage or tendon block. With the change in the polarization state of the incident infrared light, the resulting anisotropic behavior of the tissue structure is described here. Methods Thin sections (6 μm thick were obtained from three different surfaces of the canine tissue blocks and imaged at 6.25 μm pixel resolution. For each section, infrared imaging experiments were repeated thirteen times with the identical parameters except a 15° increment of the analyzer's angle in the 0° – 180° angular space. The anisotropies of amide I and amide II components were studied in order to probe the orientation of the collagen fibrils at different tissue surfaces. Results For tendon, the anisotropy of amide I and amide II components in parallel sections is comparable to that of regular sections; and tendon's cross sections show distinct, but weak anisotropic behavior for both the amide components. For articular cartilage, parallel sections in the superficial zone have the expected infrared anisotropy that is consistent with that of regular sections. The parallel sections in the radial zone, however, have a nearly isotropic amide II absorption and a distinct amide I anisotropy. Conclusion From the inconsistency in amide anisotropy between superficial to radial zone in parallel section results, a schematic model is used to explain the origins of these amide anisotropies in cartilage and tendon.

Introduction to parallel programming

CERN Document Server

Brawer, Steven

1989-01-01

Introduction to Parallel Programming focuses on the techniques, processes, methodologies, and approaches involved in parallel programming. The book first offers information on Fortran, hardware and operating system models, and processes, shared memory, and simple parallel programs. Discussions focus on processes and processors, joining processes, shared memory, time-sharing with multiple processors, hardware, loops, passing arguments in function/subroutine calls, program structure, and arithmetic expressions. The text then elaborates on basic parallel programming techniques, barriers and race

Parallelism in matrix computations

CERN Document Server

Gallopoulos, Efstratios; Sameh, Ahmed H

2016-01-01

This book is primarily intended as a research monograph that could also be used in graduate courses for the design of parallel algorithms in matrix computations. It assumes general but not extensive knowledge of numerical linear algebra, parallel architectures, and parallel programming paradigms. The book consists of four parts: (I) Basics; (II) Dense and Special Matrix Computations; (III) Sparse Matrix Computations; and (IV) Matrix functions and characteristics. Part I deals with parallel programming paradigms and fundamental kernels, including reordering schemes for sparse matrices. Part II is devoted to dense matrix computations such as parallel algorithms for solving linear systems, linear least squares, the symmetric algebraic eigenvalue problem, and the singular-value decomposition. It also deals with the development of parallel algorithms for special linear systems such as banded ,Vandermonde ,Toeplitz ,and block Toeplitz systems. Part III addresses sparse matrix computations: (a) the development of pa...

Experimental survey of the potential energy surfaces associated with fission

International Nuclear Information System (INIS)

Britt, H.C.

1980-01-01

Progress in the experimental determination of the properties of the potential energy surface associated with fission is reviewed. The importance of nuclear symmetry effects on the calculation of fission widths is demonstrated. Evidence is presented for the fragmentation of the mass-asymmetric second barrier in the thorium region and the axial asymmetric first barrier in the californium region. Detailed analyses of experimental data suggest the presence of two parallel second barriers; the normal mass-asymmetric, axial-symmetric barrier and a slightly higher mass-symmetric, axial-asymmetric barrier. Experimental barrier parameters are determined systematically and compared with calculations from various theoretical models. Techniques for expanding fission probability measurements to higher energies are discussed. (author)

Development of the apparatus for measuring magnetic properties of electrical steel sheets in arbitrary directions under compressive stress normal to their surface

Directory of Open Access Journals (Sweden)

Yoshitaka Maeda

2017-05-01

Full Text Available In designing motors, one must grasp the magnetic properties of electrical steel sheets considering actual conditions in motors. Especially important is grasping the stress dependence of magnetic power loss. This paper describes a newly developed apparatus to measure two-dimensional (2-D magnetic properties (properties under the arbitrary alternating and the rotating flux conditions of electrical steel sheets under compressive stress normal to the sheet surface. The apparatus has a 2-D magnetic excitation circuit to generate magnetic fields in arbitrary directions in the evaluation area. It also has a pressing unit to apply compressive stress normal to the sheet surface. During measurement, it is important to apply uniform stress throughout the evaluation area. Therefore, we have developed a new flux density sensor using needle probe method. It is composed of thin copper foils sputtered on electrical steel sheets. By using this sensor, the stress can be applied to the surface of the specimen without influence of this sensor. This paper described the details of newly developed apparatus with this sensor, and measurement results of iron loss by using are shown.

Model-driven product line engineering for mapping parallel algorithms to parallel computing platforms

NARCIS (Netherlands)

Arkin, Ethem; Tekinerdogan, Bedir

2016-01-01

Mapping parallel algorithms to parallel computing platforms requires several activities such as the analysis of the parallel algorithm, the definition of the logical configuration of the platform, the mapping of the algorithm to the logical configuration platform and the implementation of the

Parallelization in Modern C++

CERN Multimedia

CERN. Geneva

2016-01-01

The traditionally used and well established parallel programming models OpenMP and MPI are both targeting lower level parallelism and are meant to be as language agnostic as possible. For a long time, those models were the only widely available portable options for developing parallel C++ applications beyond using plain threads. This has strongly limited the optimization capabilities of compilers, has inhibited extensibility and genericity, and has restricted the use of those models together with other, modern higher level abstractions introduced by the C++11 and C++14 standards. The recent revival of interest in the industry and wider community for the C++ language has also spurred a remarkable amount of standardization proposals and technical specifications being developed. Those efforts however have so far failed to build a vision on how to seamlessly integrate various types of parallelism, such as iterative parallel execution, task-based parallelism, asynchronous many-task execution flows, continuation s...

Identification of a developmental gene expression signature, including HOX genes, for the normal human colonic crypt stem cell niche: overexpression of the signature parallels stem cell overpopulation during colon tumorigenesis.

Science.gov (United States)

Bhatlekar, Seema; Addya, Sankar; Salunek, Moreh; Orr, Christopher R; Surrey, Saul; McKenzie, Steven; Fields, Jeremy Z; Boman, Bruce M

2014-01-15

Our goal was to identify a unique gene expression signature for human colonic stem cells (SCs). Accordingly, we determined the gene expression pattern for a known SC-enriched region--the crypt bottom. Colonic crypts and isolated crypt subsections (top, middle, and bottom) were purified from fresh, normal, human, surgical specimens. We then used an innovative strategy that used two-color microarrays (∼18,500 genes) to compare gene expression in the crypt bottom with expression in the other crypt subsections (middle or top). Array results were validated by PCR and immunostaining. About 25% of genes analyzed were expressed in crypts: 88 preferentially in the bottom, 68 in the middle, and 131 in the top. Among genes upregulated in the bottom, ∼30% were classified as growth and/or developmental genes including several in the PI3 kinase pathway, a six-transmembrane protein STAMP1, and two homeobox (HOXA4, HOXD10) genes. qPCR and immunostaining validated that HOXA4 and HOXD10 are selectively expressed in the normal crypt bottom and are overexpressed in colon carcinomas (CRCs). Immunostaining showed that HOXA4 and HOXD10 are co-expressed with the SC markers CD166 and ALDH1 in cells at the normal crypt bottom, and the number of these co-expressing cells is increased in CRCs. Thus, our findings show that these two HOX genes are selectively expressed in colonic SCs and that HOX overexpression in CRCs parallels the SC overpopulation that occurs during CRC development. Our study suggests that developmental genes play key roles in the maintenance of normal SCs and crypt renewal, and contribute to the SC overpopulation that drives colon tumorigenesis.

Synthesis, characterization, and evaluation of a superficially porous particle with unique, elongated pore channels normal to the surface.

Science.gov (United States)

Wei, Ta-Chen; Mack, Anne; Chen, Wu; Liu, Jia; Dittmann, Monika; Wang, Xiaoli; Barber, William E

2016-04-01

In recent years, superficially porous particles (SPPs) have drawn great interest because of their special particle characteristics and improvement in separation efficiency. Superficially porous particles are currently manufactured by adding silica nanoparticles onto solid cores using either a multistep multilayer process or one-step coacervation process. The pore size is mainly controlled by the size of the silica nanoparticles and the tortuous pore channel geometry is determined by how those nanoparticles randomly aggregate. Such tortuous pore structure is also similar to that of all totally porous particles used in HPLC today. In this article, we report on the development of a next generation superficially porous particle with a unique pore structure that includes a thinner shell thickness and ordered pore channels oriented normal to the particle surface. The method of making the new superficially porous particles is a process called pseudomorphic transformation (PMT), which is a form of micelle templating. Porosity is no longer controlled by randomly aggregated nanoparticles but rather by micelles that have an ordered liquid crystal structure. The new particle possesses many advantages such as a narrower particle size distribution, thinner porous layer with high surface area and, most importantly, highly ordered, non-tortuous pore channels oriented normal to the particle surface. This PMT process has been applied to make 1.8-5.1μm SPPs with pore size controlled around 75Å and surface area around 100m(2)/g. All particles with different sizes show the same unique pore structure with tunable pore size and shell thickness. The impact of the novel pore structure on the performance of these particles is characterized by measuring van Deemter curves and constructing kinetic plots. Reduced plate heights as low as 1.0 have been achieved on conventional LC instruments. This indicates higher efficiency of such particles compared to conventional totally porous and

Hi-Corrector: a fast, scalable and memory-efficient package for normalizing large-scale Hi-C data.

Science.gov (United States)

Li, Wenyuan; Gong, Ke; Li, Qingjiao; Alber, Frank; Zhou, Xianghong Jasmine

2015-03-15

Genome-wide proximity ligation assays, e.g. Hi-C and its variant TCC, have recently become important tools to study spatial genome organization. Removing biases from chromatin contact matrices generated by such techniques is a critical preprocessing step of subsequent analyses. The continuing decline of sequencing costs has led to an ever-improving resolution of the Hi-C data, resulting in very large matrices of chromatin contacts. Such large-size matrices, however, pose a great challenge on the memory usage and speed of its normalization. Therefore, there is an urgent need for fast and memory-efficient methods for normalization of Hi-C data. We developed Hi-Corrector, an easy-to-use, open source implementation of the Hi-C data normalization algorithm. Its salient features are (i) scalability-the software is capable of normalizing Hi-C data of any size in reasonable times; (ii) memory efficiency-the sequential version can run on any single computer with very limited memory, no matter how little; (iii) fast speed-the parallel version can run very fast on multiple computing nodes with limited local memory. The sequential version is implemented in ANSI C and can be easily compiled on any system; the parallel version is implemented in ANSI C with the MPI library (a standardized and portable parallel environment designed for solving large-scale scientific problems). The package is freely available at http://zhoulab.usc.edu/Hi-Corrector/. © The Author 2014. Published by Oxford University Press.

Normal tissue dose-effect models in biological dose optimisation

International Nuclear Information System (INIS)

Alber, M.

2008-01-01

Sophisticated radiotherapy techniques like intensity modulated radiotherapy with photons and protons rely on numerical dose optimisation. The evaluation of normal tissue dose distributions that deviate significantly from the common clinical routine and also the mathematical expression of desirable properties of a dose distribution is difficult. In essence, a dose evaluation model for normal tissues has to express the tissue specific volume effect. A formalism of local dose effect measures is presented, which can be applied to serial and parallel responding tissues as well as target volumes and physical dose penalties. These models allow a transparent description of the volume effect and an efficient control over the optimum dose distribution. They can be linked to normal tissue complication probability models and the equivalent uniform dose concept. In clinical applications, they provide a means to standardize normal tissue doses in the face of inevitable anatomical differences between patients and a vastly increased freedom to shape the dose, without being overly limiting like sets of dose-volume constraints. (orig.)

Normal variants of the intracranial circulation demonstrated by MR angiography at 3 T

International Nuclear Information System (INIS)

Parmar, H.; Sitoh, Y.Y.; Hui, F.

2005-01-01

Magnetic resonance angiography (MRA) at 3 T offers increased signal to noise ratio with better background suppression, leading to exquisite depiction of the intracranial circulation. We present a pictorial review of the normal variations and anomalies of the intracranial circulation detected on MRA performed on a high field 3 T clinical scanner using parallel imaging techniques. The salient imaging features of these anomalies and normal variations are discussed with relevance to clinical practice

Massively parallel mathematical sieves

Energy Technology Data Exchange (ETDEWEB)

Montry, G.R.

1989-01-01

The Sieve of Eratosthenes is a well-known algorithm for finding all prime numbers in a given subset of integers. A parallel version of the Sieve is described that produces computational speedups over 800 on a hypercube with 1,024 processing elements for problems of fixed size. Computational speedups as high as 980 are achieved when the problem size per processor is fixed. The method of parallelization generalizes to other sieves and will be efficient on any ensemble architecture. We investigate two highly parallel sieves using scattered decomposition and compare their performance on a hypercube multiprocessor. A comparison of different parallelization techniques for the sieve illustrates the trade-offs necessary in the design and implementation of massively parallel algorithms for large ensemble computers.

Computer-Aided Parallelizer and Optimizer

Science.gov (United States)

Jin, Haoqiang

2011-01-01

The Computer-Aided Parallelizer and Optimizer (CAPO) automates the insertion of compiler directives (see figure) to facilitate parallel processing on Shared Memory Parallel (SMP) machines. While CAPO currently is integrated seamlessly into CAPTools (developed at the University of Greenwich, now marketed as ParaWise), CAPO was independently developed at Ames Research Center as one of the components for the Legacy Code Modernization (LCM) project. The current version takes serial FORTRAN programs, performs interprocedural data dependence analysis, and generates OpenMP directives. Due to the widely supported OpenMP standard, the generated OpenMP codes have the potential to run on a wide range of SMP machines. CAPO relies on accurate interprocedural data dependence information currently provided by CAPTools. Compiler directives are generated through identification of parallel loops in the outermost level, construction of parallel regions around parallel loops and optimization of parallel regions, and insertion of directives with automatic identification of private, reduction, induction, and shared variables. Attempts also have been made to identify potential pipeline parallelism (implemented with point-to-point synchronization). Although directives are generated automatically, user interaction with the tool is still important for producing good parallel codes. A comprehensive graphical user interface is included for users to interact with the parallelization process.

Data communications in a parallel active messaging interface of a parallel computer

Science.gov (United States)

Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

2013-11-12

Data communications in a parallel active messaging interface (`PAMI`) of a parallel computer composed of compute nodes that execute a parallel application, each compute node including application processors that execute the parallel application and at least one management processor dedicated to gathering information regarding data communications. The PAMI is composed of data communications endpoints, each endpoint composed of a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes and the endpoints coupled for data communications through the PAMI and through data communications resources. Embodiments function by gathering call site statistics describing data communications resulting from execution of data communications instructions and identifying in dependence upon the call cite statistics a data communications algorithm for use in executing a data communications instruction at a call site in the parallel application.

Marginal Assessment of Crowns by the Aid of Parallel Radiography

Directory of Open Access Journals (Sweden)

Farnaz Fattahi

2015-03-01

Full Text Available Introduction: Marginal adaptation is the most critical item in long-term prognosis of single crowns. This study aimed to assess the marginal quality as well asthe discrepancies in marginal integrity of some PFM single crowns of posterior teeth by employing parallel radiography in Shiraz Dental School, Shiraz, Iran. Methods: In this descriptive study, parallel radiographies were taken from 200 fabricated PFM single crowns of posterior teeth after cementation and before discharging the patient. To calculate the magnification of the images, a metallic sphere with the thickness of 4 mm was placed in the direction of the crown margin on the occlusal surface. Thereafter, the horizontal and vertical space between the crown margins, the margin of preparations and also the vertical space between the crown margin and the bone crest were measured by using digital radiological software. Results: Analysis of data by descriptive statistics revealed that 75.5% and 60% of the cases had more than the acceptable space (50µm in the vertical (130±20µm and horizontal (90±15µm dimensions, respectively. Moreover, 85% of patients were found to have either horizontal or vertical gap. In 77% of cases, the margins of crowns invaded the biologic width in the mesial and 70% in distal surfaces. Conclusion: Parallel radiography can be expedient in the stage of framework try-in to yield some important information that cannot be obtained by routine clinical evaluations and may improve the treatment prognosis

A parallel buffer tree

DEFF Research Database (Denmark)

Sitchinava, Nodar; Zeh, Norbert

2012-01-01

We present the parallel buffer tree, a parallel external memory (PEM) data structure for batched search problems. This data structure is a non-trivial extension of Arge's sequential buffer tree to a private-cache multiprocessor environment and reduces the number of I/O operations by the number of...... in the optimal OhOf(psortN + K/PB) parallel I/O complexity, where K is the size of the output reported in the process and psortN is the parallel I/O complexity of sorting N elements using P processors....

Application Portable Parallel Library

Science.gov (United States)

Cole, Gary L.; Blech, Richard A.; Quealy, Angela; Townsend, Scott

1995-01-01

Application Portable Parallel Library (APPL) computer program is subroutine-based message-passing software library intended to provide consistent interface to variety of multiprocessor computers on market today. Minimizes effort needed to move application program from one computer to another. User develops application program once and then easily moves application program from parallel computer on which created to another parallel computer. ("Parallel computer" also include heterogeneous collection of networked computers). Written in C language with one FORTRAN 77 subroutine for UNIX-based computers and callable from application programs written in C language or FORTRAN 77.

Parallel Algorithms and Patterns

Energy Technology Data Exchange (ETDEWEB)

Robey, Robert W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-06-16

This is a powerpoint presentation on parallel algorithms and patterns. A parallel algorithm is a well-defined, step-by-step computational procedure that emphasizes concurrency to solve a problem. Examples of problems include: Sorting, searching, optimization, matrix operations. A parallel pattern is a computational step in a sequence of independent, potentially concurrent operations that occurs in diverse scenarios with some frequency. Examples are: Reductions, prefix scans, ghost cell updates. We only touch on parallel patterns in this presentation. It really deserves its own detailed discussion which Gabe Rockefeller would like to develop.

Realization of cantilever arrays for parallel proximity imaging

International Nuclear Information System (INIS)

Sarov, Y; Ivanov, Tz; Frank, A; Zoellner, J-P; Nikolov, N; Rangelow, I W

2010-01-01

This paper reports on the fabrication and characterisation of self-actuating, and self-sensing cantilever arrays for large-scale parallel surface scanning. Each cantilever is integrated with a sharp silicon tip, a thermal-driven bimorph actuator, and a piezoresistive deflection sensor. Thus, the tip to the sample distance can be controlled individually for each cantilever. A radius of the tips below 10 nm is obtained, which enables nanometre in-plane surface imaging by Angstrom resolution in vertical direction. The fabricated cantilever probe arrays are also applicable for large-area manipulation, sub-10 nm metrology, bottom-up synthesis, high-speed gas analysis, for different bio-applications like recognition of DNA, RNA, or various biomarkers of a single disease, etc.

Totally parallel multilevel algorithms

Science.gov (United States)

Frederickson, Paul O.

1988-01-01

Four totally parallel algorithms for the solution of a sparse linear system have common characteristics which become quite apparent when they are implemented on a highly parallel hypercube such as the CM2. These four algorithms are Parallel Superconvergent Multigrid (PSMG) of Frederickson and McBryan, Robust Multigrid (RMG) of Hackbusch, the FFT based Spectral Algorithm, and Parallel Cyclic Reduction. In fact, all four can be formulated as particular cases of the same totally parallel multilevel algorithm, which are referred to as TPMA. In certain cases the spectral radius of TPMA is zero, and it is recognized to be a direct algorithm. In many other cases the spectral radius, although not zero, is small enough that a single iteration per timestep keeps the local error within the required tolerance.

Surface impedance of travelling--Wave antenna in magnetized plasma

International Nuclear Information System (INIS)

Denisenko, I.B.; Ostrikov, K.N.

1993-01-01

Wave properties of metal antennas immersed in a magnetoactive plasma are intensively studied nowadays with the objects of radio communications in ionosphere, plasma heating, gas discharge technique. Many papers are devoted to studies of sheath waves (SW) in magnetoplasma, which are surface by nature and propagate along the metal-low-density sheath-plasma waveguide structure. The results of these papers suggest that the existence of these waves makes significant contribution in antenna impedance. Note that the impedance measurement is one of possible ways of experimental surface waves characterization. In the present report the surface impedance of travelling SW antenna immersed in magnetoactive plasma is calculated and its dependence on the waveguide structure parameters such as plasma density, external magnetic field H 0 and electrons collisional frequency values, sheath region width, conductivity of metal surface is studied. The calculations have been carried out in a quasiplane approximation, when antenna radius greatly exceeds the SW skin depth. Note that the finite conductivity of metal is necessary to be taken into account to provide a finite surface impedance value. The surface impedance is calculated in two cases, namely when SW propagate along (Ζ parallel ) and across (Ζ perpendicular ) the external magnetic field. The relation between the values Ζ parallel and Ζ perpendicular is obtained. This relation shows that the values Ζ parallel and Ζ parallel may satisfy both inequalities Ζ parallel much-gt Ζ perpendicular and Ζ perpendicular approx-gt Ζ perpendicular dependent on the parameters of the structure. The comparison of dispersion properties of the SW propagating along Η 0 with the experimental results is carried out. The results are shown to satisfactorily correspond to the experimental results

Research on a Novel Parallel Engraving Machine and its Key Technologies

Directory of Open Access Journals (Sweden)

Zhang Shi-hui

2008-11-01

Full Text Available In order to compensate the disadvantages of conventional engraving machine and exert the advantages of parallel mechanism, a novel parallel engraving machine is presented and some key technologies are studied in this paper. Mechanism performances are analyzed in terms of the first and the second order influence coefficient matrix firstly. So the sizes of mechanism, which are better for all the performance indices of both kinematics and dynamics, can be confirmed and the restriction due to considering only the first order influence coefficient matrix in the past is broken through. Therefore, the theory basis for designing the mechanism size of novel engraving machine with better performances is provided. In addition, method for tool path planning and control technology for engraving force is also studied in the paper. The proposed algorithm for tool path planning on curved surface can be applied to arbitrary spacial curved surface in theory, control technology for engraving force based on fuzzy neural network(FNN has well adaptability to the changing environment. Research on teleoperation for parallel engraving machine based on B/S architecture resolves the key problems such as control mode, sharing mechanism for multiuser, real-time control for engraving job and real-time transmission for video information. Simulation results further show the feasibility and validity of the proposed methods.

Research on a Novel Parallel Engraving Machine and its Key Technologies

Directory of Open Access Journals (Sweden)

Kong Ling-fu

2004-12-01

Full Text Available In order to compensate the disadvantages of conventional engraving machine and exert the advantages of parallel mechanism, a novel parallel engraving machine is presented and some key technologies are studied in this paper. Mechanism performances are analyzed in terms of the first and the second order influence coefficient matrix firstly. So the sizes of mechanism, which are better for all the performance indices of both kinematics and dynamics, can be confirmed and the restriction due to considering only the first order influence coefficient matrix in the past is broken through. Therefore, the theory basis for designing the mechanism size of novel engraving machine with better performances is provided. In addition, method for tool path planning and control technology for engraving force is also studied in the paper. The proposed algorithm for tool path planning on curved surface can be applied to arbitrary spacial curved surface in theory, control technology for engraving force based on fuzzy neural network(FNN has well adaptability to the changing environment. Research on teleoperation for parallel engraving machine based on B/S architecture resolves the key problems such as control mode, sharing mechanism for multiuser, real-time control for engraving job and real-time transmission for video information. Simulation results further show the feasibility and validity of the proposed methods.

On the wall-normal velocity of the compressible boundary-layer equations

Science.gov (United States)

Pruett, C. David

1991-01-01

Numerical methods for the compressible boundary-layer equations are facilitated by transformation from the physical (x,y) plane to a computational (xi,eta) plane in which the evolution of the flow is 'slow' in the time-like xi direction. The commonly used Levy-Lees transformation results in a computationally well-behaved problem for a wide class of non-similar boundary-layer flows, but it complicates interpretation of the solution in physical space. Specifically, the transformation is inherently nonlinear, and the physical wall-normal velocity is transformed out of the problem and is not readily recovered. In light of recent research which shows mean-flow non-parallelism to significantly influence the stability of high-speed compressible flows, the contribution of the wall-normal velocity in the analysis of stability should not be routinely neglected. Conventional methods extract the wall-normal velocity in physical space from the continuity equation, using finite-difference techniques and interpolation procedures. The present spectrally-accurate method extracts the wall-normal velocity directly from the transformation itself, without interpolation, leaving the continuity equation free as a check on the quality of the solution. The present method for recovering wall-normal velocity, when used in conjunction with a highly-accurate spectral collocation method for solving the compressible boundary-layer equations, results in a discrete solution which is extraordinarily smooth and accurate, and which satisfies the continuity equation nearly to machine precision. These qualities make the method well suited to the computation of the non-parallel mean flows needed by spatial direct numerical simulations (DNS) and parabolized stability equation (PSE) approaches to the analysis of stability.

HVI Ballistic Performance Characterization of Non-Parallel Walls

Science.gov (United States)

Bohl, William; Miller, Joshua; Christiansen, Eric

2012-01-01

The Double-Wall, "Whipple" Shield [1] has been the subject of many hypervelocity impact studies and has proven to be an effective shield system for Micro-Meteoroid and Orbital Debris (MMOD) impacts for spacecraft. The US modules of the International Space Station (ISS), with their "bumper shields" offset from their pressure holding rear walls provide good examples of effective on-orbit use of the double wall shield. The concentric cylinder shield configuration with its large radius of curvature relative to separation distance is easily and effectively represented for testing and analysis as a system of two parallel plates. The parallel plate double wall configuration has been heavily tested and characterized for shield performance for normal and oblique impacts for the ISS and other programs. The double wall shield and principally similar Stuffed Whipple Shield are very common shield types for MMOD protection. However, in some locations with many spacecraft designs, the rear wall cannot be modeled as being parallel or concentric with the outer bumper wall. As represented in Figure 1, there is an included angle between the two walls. And, with a cylindrical outer wall, the effective included angle constantly changes. This complicates assessment of critical spacecraft components located within outer spacecraft walls when using software tools such as NASA's BumperII. In addition, the validity of the risk assessment comes into question when using the standard double wall shield equations, especially since verification testing of every set of double wall included angles is impossible.

Neural Parallel Engine: A toolbox for massively parallel neural signal processing.

Science.gov (United States)

Tam, Wing-Kin; Yang, Zhi

2018-05-01

Large-scale neural recordings provide detailed information on neuronal activities and can help elicit the underlying neural mechanisms of the brain. However, the computational burden is also formidable when we try to process the huge data stream generated by such recordings. In this study, we report the development of Neural Parallel Engine (NPE), a toolbox for massively parallel neural signal processing on graphical processing units (GPUs). It offers a selection of the most commonly used routines in neural signal processing such as spike detection and spike sorting, including advanced algorithms such as exponential-component-power-component (EC-PC) spike detection and binary pursuit spike sorting. We also propose a new method for detecting peaks in parallel through a parallel compact operation. Our toolbox is able to offer a 5× to 110× speedup compared with its CPU counterparts depending on the algorithms. A user-friendly MATLAB interface is provided to allow easy integration of the toolbox into existing workflows. Previous efforts on GPU neural signal processing only focus on a few rudimentary algorithms, are not well-optimized and often do not provide a user-friendly programming interface to fit into existing workflows. There is a strong need for a comprehensive toolbox for massively parallel neural signal processing. A new toolbox for massively parallel neural signal processing has been created. It can offer significant speedup in processing signals from large-scale recordings up to thousands of channels. Copyright © 2018 Elsevier B.V. All rights reserved.

2D-RBUC for efficient parallel compression of residuals

Science.gov (United States)

Đurđević, Đorđe M.; Tartalja, Igor I.

2018-02-01

In this paper, we present a method for lossless compression of residuals with an efficient SIMD parallel decompression. The residuals originate from lossy or near lossless compression of height fields, which are commonly used to represent models of terrains. The algorithm is founded on the existing RBUC method for compression of non-uniform data sources. We have adapted the method to capture 2D spatial locality of height fields, and developed the data decompression algorithm for modern GPU architectures already present even in home computers. In combination with the point-level SIMD-parallel lossless/lossy high field compression method HFPaC, characterized by fast progressive decompression and seamlessly reconstructed surface, the newly proposed method trades off small efficiency degradation for a non negligible compression ratio (measured up to 91%) benefit.

Attractor hopping between polarization dynamical states in a vertical-cavity surface-emitting laser subject to parallel optical injection

Science.gov (United States)

Denis-le Coarer, Florian; Quirce, Ana; Valle, Angel; Pesquera, Luis; Rodríguez, Miguel A.; Panajotov, Krassimir; Sciamanna, Marc

2018-03-01

We present experimental and theoretical results of noise-induced attractor hopping between dynamical states found in a single transverse mode vertical-cavity surface-emitting laser (VCSEL) subject to parallel optical injection. These transitions involve dynamical states with different polarizations of the light emitted by the VCSEL. We report an experimental map identifying, in the injected power-frequency detuning plane, regions where attractor hopping between two, or even three, different states occur. The transition between these behaviors is characterized by using residence time distributions. We find multistability regions that are characterized by heavy-tailed residence time distributions. These distributions are characterized by a -1.83 ±0.17 power law. Between these regions we find coherence enhancement of noise-induced attractor hopping in which transitions between states occur regularly. Simulation results show that frequency detuning variations and spontaneous emission noise play a role in causing switching between attractors. We also find attractor hopping between chaotic states with different polarization properties. In this case, simulation results show that spontaneous emission noise inherent to the VCSEL is enough to induce this hopping.

A possibility of parallel and anti-parallel diffraction measurements on ...

Indian Academy of Sciences (India)

However, a bent perfect crystal (BPC) monochromator at monochromatic focusing condition can provide a quite flat and equal resolution property at both parallel and anti-parallel positions and thus one can have a chance to use both sides for the diffraction experiment. From the data of the FWHM and the / measured ...

Pseudo--Normals for Signed Distance Computation

DEFF Research Database (Denmark)

Aanæs, Henrik; Bærentzen, Jakob Andreas

2003-01-01

the relation of a point to a mesh. At the vertices and edges of a triangle mesh, the surface is not \\$C\\^1\\$ continuous. Hence, the normal is undefined at these loci. Thürmer and Wüthrich proposed the \\$\\backslash\\$emph{angle weighted pseudo--normal} as a way to deal with this problem. In this paper, we...

Formulae for the determination of the elements of the E\\"otvos matrix of the Earth's normal gravity field and a relation between normal and actual Gaussian curvature

OpenAIRE

Manoussakis, G.; Delikaraoglou, D.

2011-01-01

In this paper we form relations for the determination of the elements of the E\\"otv\\"os matrix of the Earth's normal gravity field. In addition a relation between the Gauss curvature of the normal equipotential surface and the Gauss curvature of the actual equipotential surface both passing through the point P is presented. For this purpose we use a global Cartesian system (X, Y, Z) and use the variables X, and Y to form a local parameterization a normal equipotential surface to describe its ...

Deformation associated with continental normal faults

Science.gov (United States)

Resor, Phillip G.

Deformation associated with normal fault earthquakes and geologic structures provide insights into the seismic cycle as it unfolds over time scales from seconds to millions of years. Improved understanding of normal faulting will lead to more accurate seismic hazard assessments and prediction of associated structures. High-precision aftershock locations for the 1995 Kozani-Grevena earthquake (Mw 6.5), Greece image a segmented master fault and antithetic faults. This three-dimensional fault geometry is typical of normal fault systems mapped from outcrop or interpreted from reflection seismic data and illustrates the importance of incorporating three-dimensional fault geometry in mechanical models. Subsurface fault slip associated with the Kozani-Grevena and 1999 Hector Mine (Mw 7.1) earthquakes is modeled using a new method for slip inversion on three-dimensional fault surfaces. Incorporation of three-dimensional fault geometry improves the fit to the geodetic data while honoring aftershock distributions and surface ruptures. GPS Surveying of deformed bedding surfaces associated with normal faulting in the western Grand Canyon reveals patterns of deformation that are similar to those observed by interferometric satellite radar interferometry (InSAR) for the Kozani Grevena earthquake with a prominent down-warp in the hanging wall and a lesser up-warp in the footwall. However, deformation associated with the Kozani-Grevena earthquake extends ˜20 km from the fault surface trace, while the folds in the western Grand Canyon only extend 500 m into the footwall and 1500 m into the hanging wall. A comparison of mechanical and kinematic models illustrates advantages of mechanical models in exploring normal faulting processes including incorporation of both deformation and causative forces, and the opportunity to incorporate more complex fault geometry and constitutive properties. Elastic models with antithetic or synthetic faults or joints in association with a master

Parallel implementation of the PHOENIX generalized stellar atmosphere program. II. Wavelength parallelization

International Nuclear Information System (INIS)

Baron, E.; Hauschildt, Peter H.

1998-01-01

We describe an important addition to the parallel implementation of our generalized nonlocal thermodynamic equilibrium (NLTE) stellar atmosphere and radiative transfer computer program PHOENIX. In a previous paper in this series we described data and task parallel algorithms we have developed for radiative transfer, spectral line opacity, and NLTE opacity and rate calculations. These algorithms divided the work spatially or by spectral lines, that is, distributing the radial zones, individual spectral lines, or characteristic rays among different processors and employ, in addition, task parallelism for logically independent functions (such as atomic and molecular line opacities). For finite, monotonic velocity fields, the radiative transfer equation is an initial value problem in wavelength, and hence each wavelength point depends upon the previous one. However, for sophisticated NLTE models of both static and moving atmospheres needed to accurately describe, e.g., novae and supernovae, the number of wavelength points is very large (200,000 - 300,000) and hence parallelization over wavelength can lead both to considerable speedup in calculation time and the ability to make use of the aggregate memory available on massively parallel supercomputers. Here, we describe an implementation of a pipelined design for the wavelength parallelization of PHOENIX, where the necessary data from the processor working on a previous wavelength point is sent to the processor working on the succeeding wavelength point as soon as it is known. Our implementation uses a MIMD design based on a relatively small number of standard message passing interface (MPI) library calls and is fully portable between serial and parallel computers. copyright 1998 The American Astronomical Society

Modelling of real area of contact between tool and workpiece in metal forming processes including the influence of subsurface deformation

DEFF Research Database (Denmark)

Nielsen, Chris Valentin; Martins, Paulo A. F.; Bay, Niels Oluf

2016-01-01

New equipment for testing asperity deformation at various normal loads and subsurface elongations is presented. Resulting real contact area ratios increase heavily with increasing subsurface expansion due to lowered yield pressure on the asperities when imposing subsurface normal stress parallel ...... for estimating friction in the numerical modelling of metal forming processes.......New equipment for testing asperity deformation at various normal loads and subsurface elongations is presented. Resulting real contact area ratios increase heavily with increasing subsurface expansion due to lowered yield pressure on the asperities when imposing subsurface normal stress parallel...... to the surface. Finite element modelling supports the presentation and contributes by extrapolation of results to complete the mapping of contact area as function of normal pressure and one-directional subsurface strain parallel to the surface. Improved modelling of the real contact area is the basis...

Des proprietes de l'etat normal du modele de Hubbard bidimensionnel

Science.gov (United States)

Lemay, Francois

Depuis leur decouverte, les etudes experimentales ont demontre que les supra-conducteurs a haute temperature ont une phase normale tres etrange. Les proprietes de ces materiaux ne sont pas bien decrites par la theorie du liquide de Fermi. Le modele de Hubbard bidimensionnel, bien qu'il ne soit pas encore resolu, est toujours considere comme un candidat pour expliquer la physique de ces composes. Dans cet ouvrage, nous mettons en evidence plusieurs proprietes electroniques du modele qui sont incompatibles avec l'existence de quasi-particules. Nous montrons notamment que la susceptibilite des electrons libres sur reseau contient des singularites logarithmiques qui influencent de facon determinante les proprietes de la self-energie a basse frequence. Ces singularites sont responsables de la destruction des quasi-particules. En l'absence de fluctuations antiferromagnetiques, elles sont aussi responsables de l'existence d'un petit pseudogap dans le poids spectral au niveau de Fermi. Les proprietes du modele sont egalement etudiees pour une surface de Fermi similaire a celle des supraconducteurs a haute temperature. Un parallele est etabli entre certaines caracteristiques du modele et celles de ces materiaux.

Parallel k-means++

Energy Technology Data Exchange (ETDEWEB)

2017-04-04

A parallelization of the k-means++ seed selection algorithm on three distinct hardware platforms: GPU, multicore CPU, and multithreaded architecture. K-means++ was developed by David Arthur and Sergei Vassilvitskii in 2007 as an extension of the k-means data clustering technique. These algorithms allow people to cluster multidimensional data, by attempting to minimize the mean distance of data points within a cluster. K-means++ improved upon traditional k-means by using a more intelligent approach to selecting the initial seeds for the clustering process. While k-means++ has become a popular alternative to traditional k-means clustering, little work has been done to parallelize this technique. We have developed original C++ code for parallelizing the algorithm on three unique hardware architectures: GPU using NVidia's CUDA/Thrust framework, multicore CPU using OpenMP, and the Cray XMT multithreaded architecture. By parallelizing the process for these platforms, we are able to perform k-means++ clustering much more quickly than it could be done before.

Parallel Dynamic Analysis of a Large-Scale Water Conveyance Tunnel under Seismic Excitation Using ALE Finite-Element Method

Directory of Open Access Journals (Sweden)

Xiaoqing Wang

2016-01-01

Full Text Available Parallel analyses about the dynamic responses of a large-scale water conveyance tunnel under seismic excitation are presented in this paper. A full three-dimensional numerical model considering the water-tunnel-soil coupling is established and adopted to investigate the tunnel’s dynamic responses. The movement and sloshing of the internal water are simulated using the multi-material Arbitrary Lagrangian Eulerian (ALE method. Nonlinear fluid–structure interaction (FSI between tunnel and inner water is treated by using the penalty method. Nonlinear soil-structure interaction (SSI between soil and tunnel is dealt with by using the surface to surface contact algorithm. To overcome computing power limitations and to deal with such a large-scale calculation, a parallel algorithm based on the modified recursive coordinate bisection (MRCB considering the balance of SSI and FSI loads is proposed and used. The whole simulation is accomplished on Dawning 5000 A using the proposed MRCB based parallel algorithm optimized to run on supercomputers. The simulation model and the proposed approaches are validated by comparison with the added mass method. Dynamic responses of the tunnel are analyzed and the parallelism is discussed. Besides, factors affecting the dynamic responses are investigated. Better speedup and parallel efficiency show the scalability of the parallel method and the analysis results can be used to aid in the design of water conveyance tunnels.

Parallel magnetic resonance imaging

International Nuclear Information System (INIS)

Larkman, David J; Nunes, Rita G

2007-01-01

Parallel imaging has been the single biggest innovation in magnetic resonance imaging in the last decade. The use of multiple receiver coils to augment the time consuming Fourier encoding has reduced acquisition times significantly. This increase in speed comes at a time when other approaches to acquisition time reduction were reaching engineering and human limits. A brief summary of spatial encoding in MRI is followed by an introduction to the problem parallel imaging is designed to solve. There are a large number of parallel reconstruction algorithms; this article reviews a cross-section, SENSE, SMASH, g-SMASH and GRAPPA, selected to demonstrate the different approaches. Theoretical (the g-factor) and practical (coil design) limits to acquisition speed are reviewed. The practical implementation of parallel imaging is also discussed, in particular coil calibration. How to recognize potential failure modes and their associated artefacts are shown. Well-established applications including angiography, cardiac imaging and applications using echo planar imaging are reviewed and we discuss what makes a good application for parallel imaging. Finally, active research areas where parallel imaging is being used to improve data quality by repairing artefacted images are also reviewed. (invited topical review)

Air Entrainment and Surface Ripples in a Turbulent Ship Hull Boundary Layer

Science.gov (United States)

Masnadi, Naeem; Erinin, Martin; Duncan, James H.

2017-11-01

The air entrainment and free-surface fluctuations caused by the interaction of a free surface and the turbulent boundary layer of a vertical surface-piercing plate is studied experimentally. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes. This belt device is mounted inside a large water tank with the water level set just below the top edge of the belt. The belt, rollers, and supporting frame are contained within a sheet metal box to keep the device dry except for one 6-meter-long straight test section. The belt is accelerated suddenly from rest until reaching constant speed in order to create a temporally evolving boundary layer analogous to the spatially evolving boundary layer that would exist along a surface-piercing towed flat plate. Surface ripples are measured using a cinematic laser-induced fluorescence technique with the laser sheet oriented parallel or normal to the belt surface. Air entrainment events and bubble motions are recorded from underneath the water surface using a stereo imaging system. Measurements of small bubbles, that tend to stay submerged for a longer time, are planned via a high-speed digital in-line holographic system. The support of the Office of Naval Research is gratefully acknowledged.

Solving Large Quadratic|Assignment Problems in Parallel

DEFF Research Database (Denmark)

Clausen, Jens; Perregaard, Michael

1997-01-01

and recalculation of bounds between branchings when used in a parallel Branch-and-Bound algorithm. The algorithm has been implemented on a 16-processor MEIKO Computing Surface with Intel i860 processors. Computational results from the solution of a number of large QAPs, including the classical Nugent 20...... processors, and have hence not been ideally suited for computations essentially involving non-vectorizable computations on integers.In this paper we investigate the combination of one of the best bound functions for a Branch-and-Bound algorithm (the Gilmore-Lawler bound) and various testing, variable binding...

Radiation-hard/high-speed parallel optical links

Energy Technology Data Exchange (ETDEWEB)

Gan, K.K., E-mail: gan@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Buchholz, P.; Heidbrink, S. [Fachbereich Physik, Universität Siegen, Siegen (Germany); Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Vogt, M.; Ziolkowski, M. [Fachbereich Physik, Universität Siegen, Siegen (Germany)

2016-09-21

We have designed and fabricated a compact parallel optical engine for transmitting data at 5 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The performance of the optical engine up at 5 Gb/s is satisfactory.

Silver nanoparticle based surface enhanced Raman scattering spectroscopy of diabetic and normal rat pancreatic tissue under near-infrared laser excitation

International Nuclear Information System (INIS)

Huang, H; Shi, H; Chen, W; Yu, Y; Lin, D; Xu, Q; Feng, S; Lin, J; Huang, Z; Li, Y; Chen, R

2013-01-01

This paper presents the use of high spatial resolution silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) from rat pancreatic tissue to obtain biochrmical information about the tissue. A high quality SERS signal from a mixture of pancreatic tissues and silver nanoparticles can be obtained within 10 s using a Renishaw micro-Raman system. Prominent SERS bands of pancreatic tissue were assigned to known molecular vibrations, such as the vibrations of DNA bases, RNA bases, proteins and lipids. Different tissue structures of diabetic and normal rat pancreatic tissues have characteristic features in SERS spectra. This exploratory study demonstrated great potential for using SERS imaging to distinguish diabetic and normal pancreatic tissues on frozen sections without using dye labeling of functionalized binding sites. (letter)

Experiences in Data-Parallel Programming

Directory of Open Access Journals (Sweden)

Terry W. Clark

1997-01-01

Full Text Available To efficiently parallelize a scientific application with a data-parallel compiler requires certain structural properties in the source program, and conversely, the absence of others. A recent parallelization effort of ours reinforced this observation and motivated this correspondence. Specifically, we have transformed a Fortran 77 version of GROMOS, a popular dusty-deck program for molecular dynamics, into Fortran D, a data-parallel dialect of Fortran. During this transformation we have encountered a number of difficulties that probably are neither limited to this particular application nor do they seem likely to be addressed by improved compiler technology in the near future. Our experience with GROMOS suggests a number of points to keep in mind when developing software that may at some time in its life cycle be parallelized with a data-parallel compiler. This note presents some guidelines for engineering data-parallel applications that are compatible with Fortran D or High Performance Fortran compilers.

Precision wood particle feedstocks with retained moisture contents of greater than 30% dry basis

Science.gov (United States)

Dooley, James H; Lanning, David N

2014-10-28

Wood particles having fibers aligned in a grain, wherein: the wood particles are characterized by a length dimension (L) aligned substantially parallel to the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L; the L.times.H dimensions define two side surfaces characterized by substantially intact longitudinally arrayed fibers; the W.times.H dimensions define two cross-grain end surfaces characterized individually as aligned either normal to the grain or oblique to the grain; the L.times.W dimensions define two substantially parallel top and bottom surfaces; and, a majority of the W.times.H surfaces in the mixture of wood particles have end checking.

Precision wood particle feedstocks

Science.gov (United States)

Dooley, James H; Lanning, David N

2013-07-30

Wood particles having fibers aligned in a grain, wherein: the wood particles are characterized by a length dimension (L) aligned substantially parallel to the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L; the L.times.H dimensions define two side surfaces characterized by substantially intact longitudinally arrayed fibers; the W.times.H dimensions define two cross-grain end surfaces characterized individually as aligned either normal to the grain or oblique to the grain; the L.times.W dimensions define two substantially parallel top and bottom surfaces; and, a majority of the W.times.H surfaces in the mixture of wood particles have end checking.

A Study on the Fatigue-Fractured Surface of Normalized SS41 Steel and M.E.F. Dual Phase Steel by an X-ray Diffraction Technique

International Nuclear Information System (INIS)

Oh, Sae Wook; Park, Young Chul; Park, Soo Young; Kim, Deug Jin; Hue, Sun Chul

1996-01-01

This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone, W y , were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel. K max could be estimated by the measurement of W y

Non-Cartesian parallel imaging reconstruction.

Science.gov (United States)

Wright, Katherine L; Hamilton, Jesse I; Griswold, Mark A; Gulani, Vikas; Seiberlich, Nicole

2014-11-01

Non-Cartesian parallel imaging has played an important role in reducing data acquisition time in MRI. The use of non-Cartesian trajectories can enable more efficient coverage of k-space, which can be leveraged to reduce scan times. These trajectories can be undersampled to achieve even faster scan times, but the resulting images may contain aliasing artifacts. Just as Cartesian parallel imaging can be used to reconstruct images from undersampled Cartesian data, non-Cartesian parallel imaging methods can mitigate aliasing artifacts by using additional spatial encoding information in the form of the nonhomogeneous sensitivities of multi-coil phased arrays. This review will begin with an overview of non-Cartesian k-space trajectories and their sampling properties, followed by an in-depth discussion of several selected non-Cartesian parallel imaging algorithms. Three representative non-Cartesian parallel imaging methods will be described, including Conjugate Gradient SENSE (CG SENSE), non-Cartesian generalized autocalibrating partially parallel acquisition (GRAPPA), and Iterative Self-Consistent Parallel Imaging Reconstruction (SPIRiT). After a discussion of these three techniques, several potential promising clinical applications of non-Cartesian parallel imaging will be covered. © 2014 Wiley Periodicals, Inc.

Influence of Paralleling Dies and Paralleling Half-Bridges on Transient Current Distribution in Multichip Power Modules

DEFF Research Database (Denmark)

Li, Helong; Zhou, Wei; Wang, Xiongfei

2018-01-01

This paper addresses the transient current distribution in the multichip half-bridge power modules, where two types of paralleling connections with different current commutation mechanisms are considered: paralleling dies and paralleling half-bridges. It reveals that with paralleling dies, both t...

Improved performance of parallel surface/packed-bed discharge reactor for indoor VOCs decomposition: optimization of the reactor structure

International Nuclear Information System (INIS)

Jiang, Nan; Hui, Chun-Xue; Li, Jie; Lu, Na; Shang, Ke-Feng; Wu, Yan; Mizuno, Akira

2015-01-01

The purpose of this paper is to develop a high-efficiency air-cleaning system for volatile organic compounds (VOCs) existing in the workshop of a chemical factory. A novel parallel surface/packed-bed discharge (PSPBD) reactor, which utilized a combination of surface discharge (SD) plasma with packed-bed discharge (PBD) plasma, was designed and employed for VOCs removal in a closed vessel. In order to optimize the structure of the PSPBD reactor, the discharge characteristic, benzene removal efficiency, and energy yield were compared for different discharge lengths, quartz tube diameters, shapes of external high-voltage electrode, packed-bed discharge gaps, and packing pellet sizes, respectively. In the circulation test, 52.8% of benzene was removed and the energy yield achieved 0.79 mg kJ −1 after a 210 min discharge treatment in the PSPBD reactor, which was 10.3% and 0.18 mg kJ −1 higher, respectively, than in the SD reactor, 21.8% and 0.34 mg kJ −1 higher, respectively, than in the PBD reactor at 53 J l −1 . The improved performance in benzene removal and energy yield can be attributed to the plasma chemistry effect of the sequential processing in the PSPBD reactor. The VOCs mineralization and organic intermediates generated during discharge treatment were followed by CO x selectivity and FT-IR analyses. The experimental results indicate that the PSPBD plasma process is an effective and energy-efficient approach for VOCs removal in an indoor environment. (paper)

Standardized uptake values of fluorine-18 fluorodeoxyglucose: the value of different normalization procedures

International Nuclear Information System (INIS)

Schomburg, A.; Bender, H.; Reichel, C.; Sommer, T.; Ruhlmann, J.; Kozak, B.; Biersack, H.J.

1996-01-01

While the evident advantages of absolute metabolic rate determinations cannot be equalled by static image analysis of fluorine-18 fluorodexyglucose positron emission tomographic (FDG PET) studies, various algorithms for the normalization of static FDG uptake values have been proposed. This study was performed to compare different normalization procedures in terms of dependency on individual patient characteristics. Standardized FDG uptake values (SUVs) were calculated for liver and lung tissue in 126 patients studied with whole-body FDG PET. Uptake values were normalized for total body weight, lean body mass and body surface area. Ranges, means, medians, standard deviations and variation coefficients of these SUV parameters were calculated and their interdependency with total body weight, lean body mass, body surface area, patient height and blood sugar levels was calculated by means of regression analysis. Standardized FDG uptake values normalized for body surface area were clearly superior to SUV parameters normalized for total body weight or lean body mass. Variation and correlation coefficients of body surface area-normalized uptake values were minimal when compared with SUV parameters derived from the other normalization procedures. Normalization for total body weight resulted in uptake values still dependent on body weight and blood sugar levels, while normalization for lean body mass did not eliminate the positive correlation with lean body mass and patient height. It is concluded that normalization of FDG uptake values for body surface area is less dependent on the individual patient characteristics than are FDG uptake values normalized for other parameters, and therefore appears to be preferable for FDG PET studies in oncology. (orig.)

Algorithms for parallel flow solvers on message passing architectures

Science.gov (United States)

Vanderwijngaart, Rob F.

1995-01-01

The purpose of this project has been to identify and test suitable technologies for implementation of fluid flow solvers -- possibly coupled with structures and heat equation solvers -- on MIMD parallel computers. In the course of this investigation much attention has been paid to efficient domain decomposition strategies for ADI-type algorithms. Multi-partitioning derives its efficiency from the assignment of several blocks of grid points to each processor in the parallel computer. A coarse-grain parallelism is obtained, and a near-perfect load balance results. In uni-partitioning every processor receives responsibility for exactly one block of grid points instead of several. This necessitates fine-grain pipelined program execution in order to obtain a reasonable load balance. Although fine-grain parallelism is less desirable on many systems, especially high-latency networks of workstations, uni-partition methods are still in wide use in production codes for flow problems. Consequently, it remains important to achieve good efficiency with this technique that has essentially been superseded by multi-partitioning for parallel ADI-type algorithms. Another reason for the concentration on improving the performance of pipeline methods is their applicability in other types of flow solver kernels with stronger implied data dependence. Analytical expressions can be derived for the size of the dynamic load imbalance incurred in traditional pipelines. From these it can be determined what is the optimal first-processor retardation that leads to the shortest total completion time for the pipeline process. Theoretical predictions of pipeline performance with and without optimization match experimental observations on the iPSC/860 very well. Analysis of pipeline performance also highlights the effect of uncareful grid partitioning in flow solvers that employ pipeline algorithms. If grid blocks at boundaries are not at least as large in the wall-normal direction as those

Pattern-Driven Automatic Parallelization

Directory of Open Access Journals (Sweden)

Christoph W. Kessler

1996-01-01

Full Text Available This article describes a knowledge-based system for automatic parallelization of a wide class of sequential numerical codes operating on vectors and dense matrices, and for execution on distributed memory message-passing multiprocessors. Its main feature is a fast and powerful pattern recognition tool that locally identifies frequently occurring computations and programming concepts in the source code. This tool also works for dusty deck codes that have been "encrypted" by former machine-specific code transformations. Successful pattern recognition guides sophisticated code transformations including local algorithm replacement such that the parallelized code need not emerge from the sequential program structure by just parallelizing the loops. It allows access to an expert's knowledge on useful parallel algorithms, available machine-specific library routines, and powerful program transformations. The partially restored program semantics also supports local array alignment, distribution, and redistribution, and allows for faster and more exact prediction of the performance of the parallelized target code than is usually possible.

Data communications in a parallel active messaging interface of a parallel computer

Science.gov (United States)

Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

2013-10-29

Data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the parallel computer including a plurality of compute nodes that execute a parallel application, the PAMI composed of data communications endpoints, each endpoint including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes and the endpoints coupled for data communications through the PAMI and through data communications resources, including receiving in an origin endpoint of the PAMI a data communications instruction, the instruction characterized by an instruction type, the instruction specifying a transmission of transfer data from the origin endpoint to a target endpoint and transmitting, in accordance with the instruction type, the transfer data from the origin endpoint to the target endpoint.

The STAPL Parallel Graph Library

KAUST Repository

Harshvardhan,; Fidel, Adam; Amato, Nancy M.; Rauchwerger, Lawrence

2013-01-01

This paper describes the stapl Parallel Graph Library, a high-level framework that abstracts the user from data-distribution and parallelism details and allows them to concentrate on parallel graph algorithm development. It includes a customizable

Quantum dissipative effects in moving imperfect mirrors: Sidewise and normal motions

International Nuclear Information System (INIS)

Fosco, Cesar D.; Lombardo, Fernando C.; Mazzitelli, Francisco D.

2011-01-01

We extend our previous work on the functional approach to the dynamical Casimir effect, to compute dissipative effects due to the relative motion of two flat, parallel, imperfect mirrors in vacuum. The interaction between the internal degrees of freedom of the mirrors and the vacuum field is modeled with a nonlocal term in the vacuum field action. We consider two different situations: either the motion is 'normal', i.e., the mirrors advance or recede changing the distance a(t) between them; or it is 'parallel', namely, a remains constant, but there is a relative sliding motion of the mirrors' planes. For the latter, we show explicitly that there is a nonvanishing frictional force, even for a constant shifting speed.

Parallelism and array processing

International Nuclear Information System (INIS)

Zacharov, V.

1983-01-01

Modern computing, as well as the historical development of computing, has been dominated by sequential monoprocessing. Yet there is the alternative of parallelism, where several processes may be in concurrent execution. This alternative is discussed in a series of lectures, in which the main developments involving parallelism are considered, both from the standpoint of computing systems and that of applications that can exploit such systems. The lectures seek to discuss parallelism in a historical context, and to identify all the main aspects of concurrency in computation right up to the present time. Included will be consideration of the important question as to what use parallelism might be in the field of data processing. (orig.)

[Experimental studies on the diffusion of excitation on the right ventricular surface in the dog, during normal and stimulated beats].

Science.gov (United States)

Arisi, G; Macchi, E; Baruffi, S; Musso, E; Spaggiari, S; Stilli, D; Taccardi, B

1982-01-01

Previous work on the spread of excitation on the dog's ventricular surface enabled us to locate up to 30 breakthrough points (BKTPs) where excitation reaches the ventricular surface. In particular the equipotential contour maps enabled us to detect 3 to 5 BKTPs on the anterior right ventricular surface, near the a-v groove when a large part of ventricular surface was still at rest. With a view to investigating the mechanism underlying the early excitation of these basal regions, we stimulated the heart at several right ventricular BKTPs and in other points located at a distance from the BKTPs. The instantaneous equipotential maps showed that after stimulation most right ventricular BKTPs remained in the same position as observed the normal beats. The early appearance of epicardial wavefronts in the basal region and generally in other areas of the right ventricle was attributed to the rapid propagation of excitation waves through the Purkinje network, probably associated to a short transmural crossing time, due to a local thinness of the ventricular wall.

Engineered plant biomass feedstock particles

Science.gov (United States)

Dooley, James H [Federal Way, WA; Lanning, David N [Federal Way, WA; Broderick, Thomas F [Lake Forest Park, WA

2012-04-17

A new class of plant biomass feedstock particles characterized by consistent piece size and shape uniformity, high skeletal surface area, and good flow properties. The particles of plant biomass material having fibers aligned in a grain are characterized by a length dimension (L) aligned substantially parallel to the grain and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. In particular, the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces. The L.times.W surfaces of particles with L/H dimension ratios of 4:1 or less are further elaborated by surface checking between longitudinally arrayed fibers. The length dimension L is preferably aligned within 30.degree. parallel to the grain, and more preferably within 10.degree. parallel to the grain. The plant biomass material is preferably selected from among wood, agricultural crop residues, plantation grasses, hemp, bagasse, and bamboo.

Vectorization, parallelization and porting of nuclear codes (vectorization and parallelization). Progress report fiscal 1998

International Nuclear Information System (INIS)

Ishizuki, Shigeru; Kawai, Wataru; Nemoto, Toshiyuki; Ogasawara, Shinobu; Kume, Etsuo; Adachi, Masaaki; Kawasaki, Nobuo; Yatake, Yo-ichi

2000-03-01

Several computer codes in the nuclear field have been vectorized, parallelized and transported on the FUJITSU VPP500 system, the AP3000 system and the Paragon system at Center for Promotion of Computational Science and Engineering in Japan Atomic Energy Research Institute. We dealt with 12 codes in fiscal 1998. These results are reported in 3 parts, i.e., the vectorization and parallelization on vector processors part, the parallelization on scalar processors part and the porting part. In this report, we describe the vectorization and parallelization on vector processors. In this vectorization and parallelization on vector processors part, the vectorization of General Tokamak Circuit Simulation Program code GTCSP, the vectorization and parallelization of Molecular Dynamics NTV (n-particle, Temperature and Velocity) Simulation code MSP2, Eddy Current Analysis code EDDYCAL, Thermal Analysis Code for Test of Passive Cooling System by HENDEL T2 code THANPACST2 and MHD Equilibrium code SELENEJ on the VPP500 are described. In the parallelization on scalar processors part, the parallelization of Monte Carlo N-Particle Transport code MCNP4B2, Plasma Hydrodynamics code using Cubic Interpolated Propagation Method PHCIP and Vectorized Monte Carlo code (continuous energy model / multi-group model) MVP/GMVP on the Paragon are described. In the porting part, the porting of Monte Carlo N-Particle Transport code MCNP4B2 and Reactor Safety Analysis code RELAP5 on the AP3000 are described. (author)

Parallel External Memory Graph Algorithms

DEFF Research Database (Denmark)

Arge, Lars Allan; Goodrich, Michael T.; Sitchinava, Nodari

2010-01-01

In this paper, we study parallel I/O efficient graph algorithms in the Parallel External Memory (PEM) model, one o f the private-cache chip multiprocessor (CMP) models. We study the fundamental problem of list ranking which leads to efficient solutions to problems on trees, such as computing lowest...... an optimal speedup of ¿(P) in parallel I/O complexity and parallel computation time, compared to the single-processor external memory counterparts....

Inflammatory Cytokine Tumor Necrosis Factor α Confers Precancerous Phenotype in an Organoid Model of Normal Human Ovarian Surface Epithelial Cells

Directory of Open Access Journals (Sweden)

Joseph Kwong

2009-06-01

Full Text Available In this study, we established an in vitro organoid model of normal human ovarian surface epithelial (HOSE cells. The spheroids of these normal HOSE cells resembled epithelial inclusion cysts in human ovarian cortex, which are the cells of origin of ovarian epithelial tumor. Because there are strong correlations between chronic inflammation and the incidence of ovarian cancer, we used the organoid model to test whether protumor inflammatory cytokine tumor necrosis factor α would induce malignant phenotype in normal HOSE cells. Prolonged treatment of tumor necrosis factor α induced phenotypic changes of the HOSE spheroids, which exhibited the characteristics of precancerous lesions of ovarian epithelial tumors, including reinitiation of cell proliferation, structural disorganization, epithelial stratification, loss of epithelial polarity, degradation of basement membrane, cell invasion, and overexpression of ovarian cancer markers. The result of this study provides not only an evidence supporting the link between chronic inflammation and ovarian cancer formation but also a relevant and novel in vitro model for studying of early events of ovarian cancer.

Surface structure evolution in a homologous series of ionic liquids.

Science.gov (United States)

Haddad, Julia; Pontoni, Diego; Murphy, Bridget M; Festersen, Sven; Runge, Benjamin; Magnussen, Olaf M; Steinrück, Hans-Georg; Reichert, Harald; Ocko, Benjamin M; Deutsch, Moshe

2018-02-06

Interfaces of room temperature ionic liquids (RTILs) are important for both applications and basic science and are therefore intensely studied. However, the evolution of their interface structure with the cation's alkyl chain length [Formula: see text] from Coulomb to van der Waals interaction domination has not yet been studied for even a single broad homologous RTIL series. We present here such a study of the liquid-air interface for [Formula: see text], using angstrom-resolution X-ray methods. For [Formula: see text], a typical "simple liquid" monotonic surface-normal electron density profile [Formula: see text] is obtained, like those of water and organic solvents. For [Formula: see text], increasingly more pronounced nanoscale self-segregation of the molecules' charged moieties and apolar chains yields surface layering with alternating regions of headgroups and chains. The layering decays into the bulk over a few, to a few tens, of nanometers. The layering periods and decay lengths, their linear [Formula: see text] dependence, and slopes are discussed within two models, one with partial-chain interdigitation and the other with liquid-like chains. No surface-parallel long-range order is found within the surface layer. For [Formula: see text], a different surface phase is observed above melting. Our results also impact general liquid-phase issues like supramolecular self-aggregation and bulk-surface structure relations.

Surface wave propagation in an ideal Hall-magnetohydrodynamic plasma jet in flowing environment

International Nuclear Information System (INIS)

Sikka, Himanshu; Kumar, Nagendra; Zhelyazkov, Ivan

2004-01-01

The behavior of the Hall-magnetohydrodynamic (Hall-MHD) sausage and kink waves is studied in the presence of steady flow. The influence of the flow both inside and outside the plasma slab is taken into account. The plasma in the environment is considered to be cold and moves with the different flow velocity outside the slab. In the limit of parallel propagation, dispersion relation is derived to discuss the propagation of both the modes. Numerical results for the propagation characteristics are obtained for different Alfvenic Mach number ratios inside and outside the slab. It is found that the dispersion curves for both surface modes, namely, the sausage and kink ones in cold plasma show complexities in their behavior in terms of multivalued portions of the curves. These multivalued portions correspond to the different normalized phase velocities for the same value of Alfvenic Mach number. In contrast to the conventional MHD surface waves which are assumed to be pure surface waves or pseudosurface waves, surface waves are obtained which are bulk waves for very small dimensionless wave numbers, then turn to leaky waves and finally transform to pure surface waves for values of dimensionless wave number greater than one

Parallel inter channel interaction mechanisms

International Nuclear Information System (INIS)

Jovic, V.; Afgan, N.; Jovic, L.

1995-01-01

Parallel channels interactions are examined. For experimental researches of nonstationary regimes flow in three parallel vertical channels results of phenomenon analysis and mechanisms of parallel channel interaction for adiabatic condition of one-phase fluid and two-phase mixture flow are shown. (author)

Screw-System-Based Mobility Analysis of a Family of Fully Translational Parallel Manipulators

Directory of Open Access Journals (Sweden)

Ernesto Rodriguez-Leal

2013-01-01

Full Text Available This paper investigates the mobility of a family of fully translational parallel manipulators based on screw system analysis by identifying the common constraint and redundant constraints, providing a case study of this approach. The paper presents the branch motion-screws for the 3-RP̲C-Y parallel manipulator, the 3-RCC-Y (or 3-RP̲RC-Y parallel manipulator, and a newly proposed 3-RP̲C-T parallel manipulator. Then the paper determines the sets of platform constraint-screws for each of these three manipulators. The constraints exerted on the platforms of the 3-RP̲C architectures and the 3-RCC-Y manipulators are analyzed using the screw system approach and have been identified as couples. A similarity has been identified with the axes of couples: they are perpendicular to the R joint axes, but in the former the axes are coplanar with the base and in the latter the axes are perpendicular to the limb. The remaining couples act about the axis that is normal to the base. The motion-screw system and constraint-screw system analysis leads to the insightful understanding of the mobility of the platform that is then obtained by determining the reciprocal screws to the platform constraint screw sets, resulting in three independent instantaneous translational degrees-of-freedom. To validate the mobility analysis of the three parallel manipulators, the paper includes motion simulations which use a commercially available kinematics software.

Adsorption of asymmetric rigid rods or heteronuclear diatomic moleculeson homogeneous surfaces

Science.gov (United States)

Engl, W.; Courbin, L.; Panizza, P.

2004-10-01

We treat the adsorption on homogeneous surfaces of asymmetric rigid rods (like for instance heteronuclear diatomic molecules). We show that the n→0 vector spin formalism is well suited to describe such a problem. We establish an isomorphism between the coupling constants of the magnetic Hamiltonian and the adsorption parameters of the rigid rods. By solving this Hamiltonian within a mean-field approximation, we obtain analytical expressions for the densities of the different rod’s configurations, both isotherm and isobar adsorptions curves. The most probable configurations of the molecules (normal or parallel to the surface) which depends on temperature and energy parameters are summarized in a diagram. We derive that the variation of Qv , the heat of adsorption at constant volume, with the temperature is a direct signature of the adsorbed molecules configuration change. We show that this formalism can be generalized to more complicated problems such as for instance the adsorption of symmetric and asymmetric rigid rods mixtures in the presence or not of interactions.

Formation of organic layer on femtosecond laser-induced periodic surface structures

Energy Technology Data Exchange (ETDEWEB)

Yasumaru, Naoki, E-mail: yasuma@fukui-nct.ac.jp [National Institute of Technology, Fukui College, Sabae, Fukui 916-8507 (Japan); Sentoku, Eisuke [National Institute of Technology, Fukui College, Sabae, Fukui 916-8507 (Japan); Kiuchi, Junsuke [Eyetec Co., Ltd., Sabae, Fukui 916-0016 (Japan)

2017-05-31

Highlights: • Surface analyses of two types of femtosecond laser-induced periodic surface structures (LIPSS) on titanium were conducted. • The parallel-oriented ultrafine LIPSS showed the almost same roughness and chemical states as the non-irradiated Ti surface. • The well-known perpendicular-oriented LIPSS were typically covered with an organic layer similar to a cellulose derivative. - Abstract: Two types of laser-induced periodic surface structures (LIPSS) formed on titanium by femtosecond (fs) laser pulses (λ = 800 nm, τ = 180 fs, ν = 1 kHz) in air were investigated experimentally. At a laser fluence F above the ablation threshold, LIPSS with a minimum mean spacing of D < λ⁄2 were observed perpendicular to the laser polarization direction. In contrast, for F slightly below than the ablation threshold, ultrafine LIPSS with a minimum value of D < λ/10 were formed parallel to the polarization direction. The surface roughness of the parallel-oriented LIPSS was almost the same as that of the non-irradiated surface, unlike the high roughness of the perpendicular-oriented LIPSS. In addition, although the surface state of the parallel-oriented LIPSS was the same as that of the non-irradiated surface, the perpendicular-oriented LIPSS were covered with an organic thin film similar to a cellulose derivative that cannot be easily formed by conventional chemical synthesis. The results of these surface analyses indicate that these two types of LIPSS are formed through different mechanisms. This fs-laser processing technique may become a new technology for the artificial synthesis of cellulose derivatives.

Normalization constraint for variational bounds on fluid permeability

International Nuclear Information System (INIS)

Berryman, J.G.; Milton, G.W.

1985-01-01

A careful reexamination of the formulation of Prager's original variational principle for viscous flow through porous media has uncovered a subtle error in the normalization constraint on the trial functions. Although a certain surface integral of the true pressure field over the internal surface area always vanishes for isotropic materials, the corresponding surface integral for a given trial pressure field does not necessarily vanish but has nevertheless been previously neglected in the normalization. When this error is corrected, the form of the variational estimate is actually simpler than before and furthermore the resulting bounds have been shown to improve when the constant trial functions are used in either the two-point or three-point bounds

Normal gravity field in relativistic geodesy

Science.gov (United States)

Kopeikin, Sergei; Vlasov, Igor; Han, Wen-Biao

2018-02-01

Modern geodesy is subject to a dramatic change from the Newtonian paradigm to Einstein's theory of general relativity. This is motivated by the ongoing advance in development of quantum sensors for applications in geodesy including quantum gravimeters and gradientometers, atomic clocks and fiber optics for making ultra-precise measurements of the geoid and multipolar structure of the Earth's gravitational field. At the same time, very long baseline interferometry, satellite laser ranging, and global navigation satellite systems have achieved an unprecedented level of accuracy in measuring 3-d coordinates of the reference points of the International Terrestrial Reference Frame and the world height system. The main geodetic reference standard to which gravimetric measurements of the of Earth's gravitational field are referred is a normal gravity field represented in the Newtonian gravity by the field of a uniformly rotating, homogeneous Maclaurin ellipsoid of which mass and quadrupole momentum are equal to the total mass and (tide-free) quadrupole moment of Earth's gravitational field. The present paper extends the concept of the normal gravity field from the Newtonian theory to the realm of general relativity. We focus our attention on the calculation of the post-Newtonian approximation of the normal field that is sufficient for current and near-future practical applications. We show that in general relativity the level surface of homogeneous and uniformly rotating fluid is no longer described by the Maclaurin ellipsoid in the most general case but represents an axisymmetric spheroid of the fourth order with respect to the geodetic Cartesian coordinates. At the same time, admitting a post-Newtonian inhomogeneity of the mass density in the form of concentric elliptical shells allows one to preserve the level surface of the fluid as an exact ellipsoid of rotation. We parametrize the mass density distribution and the level surface with two parameters which are

Seeing or moving in parallel

DEFF Research Database (Denmark)

Christensen, Mark Schram; Ehrsson, H Henrik; Nielsen, Jens Bo

2013-01-01

a different network, involving bilateral dorsal premotor cortex (PMd), primary motor cortex, and SMA, was more active when subjects viewed parallel movements while performing either symmetrical or parallel movements. Correlations between behavioral instability and brain activity were present in right lateral...... adduction-abduction movements symmetrically or in parallel with real-time congruent or incongruent visual feedback of the movements. One network, consisting of bilateral superior and middle frontal gyrus and supplementary motor area (SMA), was more active when subjects performed parallel movements, whereas...

Accretion onto magnetized neutron stars: Normal mode analysis of the interchange instability at the magnetopause

International Nuclear Information System (INIS)

Arons, J.; Lea, S.M.

1976-01-01

We describe the results of a linearized hydromagnetic stability analysis of the magnetopause of an accreting neutron star. The magnetosphere is assumed to be slowly rotating, and the plasma just outside of the magnetopause is assumed to be weakly magnetized. The plasma layer is assumed to be bounded above by a shock wave, and to be thin compared with the radius of the magnetosphere. Under these circumstances, the growing modes are shown to be localized in the direction parallel to the zero-order magnetic field. The structure of the modes is still similar to the flute mode, however. The growth rate at each magnetic latitude is lambda given by γ 2 =g/sub n/kα/sub eff/(lambda) tanh [kz/sub s/(lambda)] where g/sub n/ is the magnitude of the gravitational acceleration normal to the surface, kapprox. =vertical-barmvertical-bar/R (lambda)cos lambda, vertical-barmvertical-bar is the azimuthal mode number, R (lambda) is the radius of the magnetosphere, z/sub s/ is the height of the shock above the magnetopause, and α/sub eff/(lambda) <1 is the effective Atwood number which embodies the stabilizing effects of favorable curvature and magnetic tension. We calculate α/sub eff/(lambda), and also discuss the stabilizing effects of viscosity and of aligned flow parallel to the magnetopause

The numerical parallel computing of photon transport

International Nuclear Information System (INIS)

Huang Qingnan; Liang Xiaoguang; Zhang Lifa

1998-12-01

The parallel computing of photon transport is investigated, the parallel algorithm and the parallelization of programs on parallel computers both with shared memory and with distributed memory are discussed. By analyzing the inherent law of the mathematics and physics model of photon transport according to the structure feature of parallel computers, using the strategy of 'to divide and conquer', adjusting the algorithm structure of the program, dissolving the data relationship, finding parallel liable ingredients and creating large grain parallel subtasks, the sequential computing of photon transport into is efficiently transformed into parallel and vector computing. The program was run on various HP parallel computers such as the HY-1 (PVP), the Challenge (SMP) and the YH-3 (MPP) and very good parallel speedup has been gotten

Hypergraph partitioning implementation for parallelizing matrix-vector multiplication using CUDA GPU-based parallel computing

Science.gov (United States)

Murni, Bustamam, A.; Ernastuti, Handhika, T.; Kerami, D.

2017-07-01

Calculation of the matrix-vector multiplication in the real-world problems often involves large matrix with arbitrary size. Therefore, parallelization is needed to speed up the calculation process that usually takes a long time. Graph partitioning techniques that have been discussed in the previous studies cannot be used to complete the parallelized calculation of matrix-vector multiplication with arbitrary size. This is due to the assumption of graph partitioning techniques that can only solve the square and symmetric matrix. Hypergraph partitioning techniques will overcome the shortcomings of the graph partitioning technique. This paper addresses the efficient parallelization of matrix-vector multiplication through hypergraph partitioning techniques using CUDA GPU-based parallel computing. CUDA (compute unified device architecture) is a parallel computing platform and programming model that was created by NVIDIA and implemented by the GPU (graphics processing unit).

Writing parallel programs that work

CERN Multimedia

CERN. Geneva

2012-01-01

Serial algorithms typically run inefficiently on parallel machines. This may sound like an obvious statement, but it is the root cause of why parallel programming is considered to be difficult. The current state of the computer industry is still that almost all programs in existence are serial. This talk will describe the techniques used in the Intel Parallel Studio to provide a developer with the tools necessary to understand the behaviors and limitations of the existing serial programs. Once the limitations are known the developer can refactor the algorithms and reanalyze the resulting programs with the tools in the Intel Parallel Studio to create parallel programs that work. About the speaker Paul Petersen is a Sr. Principal Engineer in the Software and Solutions Group (SSG) at Intel. He received a Ph.D. degree in Computer Science from the University of Illinois in 1993. After UIUC, he was employed at Kuck and Associates, Inc. (KAI) working on auto-parallelizing compiler (KAP), and was involved in th...

Parallel Framework for Cooperative Processes

Directory of Open Access Journals (Sweden)

Mitică Craus

2005-01-01

Full Text Available This paper describes the work of an object oriented framework designed to be used in the parallelization of a set of related algorithms. The idea behind the system we are describing is to have a re-usable framework for running several sequential algorithms in a parallel environment. The algorithms that the framework can be used with have several things in common: they have to run in cycles and the work should be possible to be split between several "processing units". The parallel framework uses the message-passing communication paradigm and is organized as a master-slave system. Two applications are presented: an Ant Colony Optimization (ACO parallel algorithm for the Travelling Salesman Problem (TSP and an Image Processing (IP parallel algorithm for the Symmetrical Neighborhood Filter (SNF. The implementations of these applications by means of the parallel framework prove to have good performances: approximatively linear speedup and low communication cost.

Compiler Technology for Parallel Scientific Computation

Directory of Open Access Journals (Sweden)

Can Özturan

1994-01-01

Full Text Available There is a need for compiler technology that, given the source program, will generate efficient parallel codes for different architectures with minimal user involvement. Parallel computation is becoming indispensable in solving large-scale problems in science and engineering. Yet, the use of parallel computation is limited by the high costs of developing the needed software. To overcome this difficulty we advocate a comprehensive approach to the development of scalable architecture-independent software for scientific computation based on our experience with equational programming language (EPL. Our approach is based on a program decomposition, parallel code synthesis, and run-time support for parallel scientific computation. The program decomposition is guided by the source program annotations provided by the user. The synthesis of parallel code is based on configurations that describe the overall computation as a set of interacting components. Run-time support is provided by the compiler-generated code that redistributes computation and data during object program execution. The generated parallel code is optimized using techniques of data alignment, operator placement, wavefront determination, and memory optimization. In this article we discuss annotations, configurations, parallel code generation, and run-time support suitable for parallel programs written in the functional parallel programming language EPL and in Fortran.

Generating a normalized geometric liver model with warping

International Nuclear Information System (INIS)

Boes, J.L.; Weymouth, T.E.; Meyer, C.R.; Quint, L.E.; Bland, P.H.; Bookstein, F.L.

1990-01-01

This paper reports on the automated determination of the liver surface in abdominal CT scans for radiation treatment, surgery planning, and anatomic visualization. The normalized geometric model of the liver is generated by averaging registered outlines from a set of 15 studies of normal liver. The outlines have been registered with the use of thin-plate spline warping based on a set of five homologous landmarks. Thus, the model consists of an average of the surface and a set of five anatomic landmarks. The accuracy of the model is measured against both the set of studies used in model generation and an alternate set of 15 normal studies with use of, as an error measure, the ratio of nonoverlapping model and study volume to total model volume

Parallel computing: numerics, applications, and trends

National Research Council Canada - National Science Library

Trobec, Roman; Vajteršic, Marián; Zinterhof, Peter

2009-01-01

... and/or distributed systems. The contributions to this book are focused on topics most concerned in the trends of today's parallel computing. These range from parallel algorithmics, programming, tools, network computing to future parallel computing. Particular attention is paid to parallel numerics: linear algebra, differential equations, numerica...

Parallel Computing Strategies for Irregular Algorithms

Science.gov (United States)

Biswas, Rupak; Oliker, Leonid; Shan, Hongzhang; Biegel, Bryan (Technical Monitor)

2002-01-01

Parallel computing promises several orders of magnitude increase in our ability to solve realistic computationally-intensive problems, but relies on their efficient mapping and execution on large-scale multiprocessor architectures. Unfortunately, many important applications are irregular and dynamic in nature, making their effective parallel implementation a daunting task. Moreover, with the proliferation of parallel architectures and programming paradigms, the typical scientist is faced with a plethora of questions that must be answered in order to obtain an acceptable parallel implementation of the solution algorithm. In this paper, we consider three representative irregular applications: unstructured remeshing, sparse matrix computations, and N-body problems, and parallelize them using various popular programming paradigms on a wide spectrum of computer platforms ranging from state-of-the-art supercomputers to PC clusters. We present the underlying problems, the solution algorithms, and the parallel implementation strategies. Smart load-balancing, partitioning, and ordering techniques are used to enhance parallel performance. Overall results demonstrate the complexity of efficiently parallelizing irregular algorithms.

The Glasgow Parallel Reduction Machine: Programming Shared-memory Many-core Systems using Parallel Task Composition

Directory of Open Access Journals (Sweden)

Ashkan Tousimojarad

2013-12-01

Full Text Available We present the Glasgow Parallel Reduction Machine (GPRM, a novel, flexible framework for parallel task-composition based many-core programming. We allow the programmer to structure programs into task code, written as C++ classes, and communication code, written in a restricted subset of C++ with functional semantics and parallel evaluation. In this paper we discuss the GPRM, the virtual machine framework that enables the parallel task composition approach. We focus the discussion on GPIR, the functional language used as the intermediate representation of the bytecode running on the GPRM. Using examples in this language we show the flexibility and power of our task composition framework. We demonstrate the potential using an implementation of a merge sort algorithm on a 64-core Tilera processor, as well as on a conventional Intel quad-core processor and an AMD 48-core processor system. We also compare our framework with OpenMP tasks in a parallel pointer chasing algorithm running on the Tilera processor. Our results show that the GPRM programs outperform the corresponding OpenMP codes on all test platforms, and can greatly facilitate writing of parallel programs, in particular non-data parallel algorithms such as reductions.

Differential geometry of CR-submanifolds of a normal almost para contact manifold

International Nuclear Information System (INIS)

Shahid, M.H.

1992-12-01

The aim of this paper is to study the geometry of CR-submanifolds of a normal almost para contact manifold. We discuss the integrability conditions of distributions involved in the definition and geometry of leaves of CR-submanifolds, some results on CR-submanifolds with parallel structures and contact CR-product are also given. (author). 10 refs

Streaming for Functional Data-Parallel Languages

DEFF Research Database (Denmark)

Madsen, Frederik Meisner

In this thesis, we investigate streaming as a general solution to the space inefficiency commonly found in functional data-parallel programming languages. The data-parallel paradigm maps well to parallel SIMD-style hardware. However, the traditional fully materializing execution strategy...... by extending two existing data-parallel languages: NESL and Accelerate. In the extensions we map bulk operations to data-parallel streams that can evaluate fully sequential, fully parallel or anything in between. By a dataflow, piecewise parallel execution strategy, the runtime system can adjust to any target...... flattening necessitates all sub-computations to materialize at the same time. For example, naive n by n matrix multiplication requires n^3 space in NESL because the algorithm contains n^3 independent scalar multiplications. For large values of n, this is completely unacceptable. We address the problem...

Development of novel series and parallel sensing system based on nanostructured surface enhanced Raman scattering substrate for biomedical application

Science.gov (United States)

Chang, Te-Wei

With the advance of nanofabrication, the capability of nanoscale metallic structure fabrication opens a whole new study in nanoplasmonics, which is defined as the investigation of photon-electron interaction in the vicinity of nanoscale metallic structures. The strong oscillation of free electrons at the interface between metal and surrounding dielectric material caused by propagating surface plasmon resonance (SPR) or localized surface plasmon resonance (LSPR) enables a variety of new applications in different areas, especially biological sensing techniques. One of the promising biological sensing applications by surface resonance polariton is surface enhanced Raman spectroscopy (SERS), which significantly reinforces the feeble signal of traditional Raman scattering by at least 104 times. It enables highly sensitive and precise molecule identification with the assistance of a SERS substrate. Until now, the design of new SERS substrate fabrication process is still thriving since no dominant design has emerged yet. The ideal process should be able to achieve both a high sensitivity and low cost device in a simple and reliable way. In this thesis two promising approaches for fabricating nanostructured SERS substrate are proposed: thermal dewetting technique and nanoimprint replica technique. These two techniques are demonstrated to show the capability of fabricating high performance SERS substrate in a reliable and cost efficient fashion. In addition, these two techniques have their own unique characteristics and can be integrated with other sensing techniques to build a serial or parallel sensing system. The breakthrough of a combination system with different sensing techniques overcomes the inherent limitations of SERS detection and leverages it to a whole new level of systematic sensing. The development of a sensing platform based on thermal dewetting technique is covered as the first half of this thesis. The process optimization, selection of substrate material

Shrinkage Analysis on Thick Plate Part using Response Surface Methodology (RSM

Directory of Open Access Journals (Sweden)

Isafiq M.

2016-01-01

Full Text Available The work reported herein is about an analysis on the quality (shrinkage on a thick plate part using Response Surface Methodology (RSM. Previous researches showed that the most influential factor affecting the shrinkage on moulded parts are mould and melt temperature. Autodesk Moldflow Insight software was used for the analysis, while specifications of Nessei NEX 1000 injection moulding machine and P20 mould material were incorporated in this study on top of Acrylonitrile Butadiene Styrene (ABS as a moulded thermoplastic material. Mould temperature, melt temperature, packing pressure and packing time were selected as variable parameters. The results show that the shrinkage have improved 42.48% and 14.41% in parallel and normal directions respectively after the optimisation process.

Patterns for Parallel Software Design

CERN Document Server

Ortega-Arjona, Jorge Luis

2010-01-01

Essential reading to understand patterns for parallel programming Software patterns have revolutionized the way we think about how software is designed, built, and documented, and the design of parallel software requires you to consider other particular design aspects and special skills. From clusters to supercomputers, success heavily depends on the design skills of software developers. Patterns for Parallel Software Design presents a pattern-oriented software architecture approach to parallel software design. This approach is not a design method in the classic sense, but a new way of managin

High performance parallel I/O

CERN Document Server

Prabhat

2014-01-01

Gain Critical Insight into the Parallel I/O EcosystemParallel I/O is an integral component of modern high performance computing (HPC), especially in storing and processing very large datasets to facilitate scientific discovery. Revealing the state of the art in this field, High Performance Parallel I/O draws on insights from leading practitioners, researchers, software architects, developers, and scientists who shed light on the parallel I/O ecosystem.The first part of the book explains how large-scale HPC facilities scope, configure, and operate systems, with an emphasis on choices of I/O har

Parallel transport of long mean-free-path plasma along open magnetic field lines: Parallel heat flux

International Nuclear Information System (INIS)

Guo Zehua; Tang Xianzhu

2012-01-01

In a long mean-free-path plasma where temperature anisotropy can be sustained, the parallel heat flux has two components with one associated with the parallel thermal energy and the other the perpendicular thermal energy. Due to the large deviation of the distribution function from local Maxwellian in an open field line plasma with low collisionality, the conventional perturbative calculation of the parallel heat flux closure in its local or non-local form is no longer applicable. Here, a non-perturbative calculation is presented for a collisionless plasma in a two-dimensional flux expander bounded by absorbing walls. Specifically, closures of previously unfamiliar form are obtained for ions and electrons, which relate two distinct components of the species parallel heat flux to the lower order fluid moments such as density, parallel flow, parallel and perpendicular temperatures, and the field quantities such as the magnetic field strength and the electrostatic potential. The plasma source and boundary condition at the absorbing wall enter explicitly in the closure calculation. Although the closure calculation does not take into account wave-particle interactions, the results based on passing orbits from steady-state collisionless drift-kinetic equation show remarkable agreement with fully kinetic-Maxwell simulations. As an example of the physical implications of the theory, the parallel heat flux closures are found to predict a surprising observation in the kinetic-Maxwell simulation of the 2D magnetic flux expander problem, where the parallel heat flux of the parallel thermal energy flows from low to high parallel temperature region.

Representing and computing regular languages on massively parallel networks

Energy Technology Data Exchange (ETDEWEB)

Miller, M.I.; O' Sullivan, J.A. (Electronic Systems and Research Lab., of Electrical Engineering, Washington Univ., St. Louis, MO (US)); Boysam, B. (Dept. of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Inst., Troy, NY (US)); Smith, K.R. (Dept. of Electrical Engineering, Southern Illinois Univ., Edwardsville, IL (US))

1991-01-01

This paper proposes a general method for incorporating rule-based constraints corresponding to regular languages into stochastic inference problems, thereby allowing for a unified representation of stochastic and syntactic pattern constraints. The authors' approach first established the formal connection of rules to Chomsky grammars, and generalizes the original work of Shannon on the encoding of rule-based channel sequences to Markov chains of maximum entropy. This maximum entropy probabilistic view leads to Gibb's representations with potentials which have their number of minima growing at precisely the exponential rate that the language of deterministically constrained sequences grow. These representations are coupled to stochastic diffusion algorithms, which sample the language-constrained sequences by visiting the energy minima according to the underlying Gibbs' probability law. The coupling to stochastic search methods yields the all-important practical result that fully parallel stochastic cellular automata may be derived to generate samples from the rule-based constraint sets. The production rules and neighborhood state structure of the language of sequences directly determines the necessary connection structures of the required parallel computing surface. Representations of this type have been mapped to the DAP-510 massively-parallel processor consisting of 1024 mesh-connected bit-serial processing elements for performing automated segmentation of electron-micrograph images.

Unsteady MHD blood flow through porous medium in a parallel plate channel

Science.gov (United States)

Latha, R.; Rushi Kumar, B.

2017-11-01

In this study, we have analyzed heat and mass transfer effects on unsteady blood flow through parallel plate channel in a saturated porous medium in the presence of a transverse magnetic field with thermal radiation. The governing higher order nonlinear PDE’S are converted to dimensionless equations using dimensionless variables. The dimensionless equations are then solved analytically using boundary conditions by choosing the axial flow transport and the fields of concentration and temperature apart from the normal velocity as a function of y and t. The effects of different pertinent parameters appeared in this model viz thermal radiation, Prandtl number, Heat source parameter, Hartmann number, Permeability parameter, Decay parameter on axial flow transport and the normal velocity are analyzed in detail.

Is Monte Carlo embarrassingly parallel?

Energy Technology Data Exchange (ETDEWEB)

Hoogenboom, J. E. [Delft Univ. of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Delft Nuclear Consultancy, IJsselzoom 2, 2902 LB Capelle aan den IJssel (Netherlands)

2012-07-01

Monte Carlo is often stated as being embarrassingly parallel. However, running a Monte Carlo calculation, especially a reactor criticality calculation, in parallel using tens of processors shows a serious limitation in speedup and the execution time may even increase beyond a certain number of processors. In this paper the main causes of the loss of efficiency when using many processors are analyzed using a simple Monte Carlo program for criticality. The basic mechanism for parallel execution is MPI. One of the bottlenecks turn out to be the rendez-vous points in the parallel calculation used for synchronization and exchange of data between processors. This happens at least at the end of each cycle for fission source generation in order to collect the full fission source distribution for the next cycle and to estimate the effective multiplication factor, which is not only part of the requested results, but also input to the next cycle for population control. Basic improvements to overcome this limitation are suggested and tested. Also other time losses in the parallel calculation are identified. Moreover, the threading mechanism, which allows the parallel execution of tasks based on shared memory using OpenMP, is analyzed in detail. Recommendations are given to get the maximum efficiency out of a parallel Monte Carlo calculation. (authors)

Is Monte Carlo embarrassingly parallel?

International Nuclear Information System (INIS)

Hoogenboom, J. E.

2012-01-01

Monte Carlo is often stated as being embarrassingly parallel. However, running a Monte Carlo calculation, especially a reactor criticality calculation, in parallel using tens of processors shows a serious limitation in speedup and the execution time may even increase beyond a certain number of processors. In this paper the main causes of the loss of efficiency when using many processors are analyzed using a simple Monte Carlo program for criticality. The basic mechanism for parallel execution is MPI. One of the bottlenecks turn out to be the rendez-vous points in the parallel calculation used for synchronization and exchange of data between processors. This happens at least at the end of each cycle for fission source generation in order to collect the full fission source distribution for the next cycle and to estimate the effective multiplication factor, which is not only part of the requested results, but also input to the next cycle for population control. Basic improvements to overcome this limitation are suggested and tested. Also other time losses in the parallel calculation are identified. Moreover, the threading mechanism, which allows the parallel execution of tasks based on shared memory using OpenMP, is analyzed in detail. Recommendations are given to get the maximum efficiency out of a parallel Monte Carlo calculation. (authors)

Parallel algorithms for continuum dynamics

International Nuclear Information System (INIS)

Hicks, D.L.; Liebrock, L.M.

1987-01-01

Simply porting existing parallel programs to a new parallel processor may not achieve the full speedup possible; to achieve the maximum efficiency may require redesigning the parallel algorithms for the specific architecture. The authors discuss here parallel algorithms that were developed first for the HEP processor and then ported to the CRAY X-MP/4, the ELXSI/10, and the Intel iPSC/32. Focus is mainly on the most recent parallel processing results produced, i.e., those on the Intel Hypercube. The applications are simulations of continuum dynamics in which the momentum and stress gradients are important. Examples of these are inertial confinement fusion experiments, severe breaks in the coolant system of a reactor, weapons physics, shock-wave physics. Speedup efficiencies on the Intel iPSC Hypercube are very sensitive to the ratio of communication to computation. Great care must be taken in designing algorithms for this machine to avoid global communication. This is much more critical on the iPSC than it was on the three previous parallel processors

Parallel S/sub n/ iteration schemes

International Nuclear Information System (INIS)

Wienke, B.R.; Hiromoto, R.E.

1986-01-01

The iterative, multigroup, discrete ordinates (S/sub n/) technique for solving the linear transport equation enjoys widespread usage and appeal. Serial iteration schemes and numerical algorithms developed over the years provide a timely framework for parallel extension. On the Denelcor HEP, the authors investigate three parallel iteration schemes for solving the one-dimensional S/sub n/ transport equation. The multigroup representation and serial iteration methods are also reviewed. This analysis represents a first attempt to extend serial S/sub n/ algorithms to parallel environments and provides good baseline estimates on ease of parallel implementation, relative algorithm efficiency, comparative speedup, and some future directions. The authors examine ordered and chaotic versions of these strategies, with and without concurrent rebalance and diffusion acceleration. Two strategies efficiently support high degrees of parallelization and appear to be robust parallel iteration techniques. The third strategy is a weaker parallel algorithm. Chaotic iteration, difficult to simulate on serial machines, holds promise and converges faster than ordered versions of the schemes. Actual parallel speedup and efficiency are high and payoff appears substantial

Method of Parallel-Hierarchical Network Self-Training and its Application for Pattern Classification and Recognition

Directory of Open Access Journals (Sweden)

TIMCHENKO, L.

2012-11-01

Full Text Available Propositions necessary for development of parallel-hierarchical (PH network training methods are discussed in this article. Unlike already known structures of the artificial neural network, where non-normalized (absolute similarity criteria are used for comparison, the suggested structure uses a normalized criterion. Based on the analysis of training rules, a conclusion is made that application of two training methods with a teacher is optimal for PH network training: error correction-based training and memory-based training. Mathematical models of training and a combined method of PH network training for recognition of static and dynamic patterns are developed.

Normalization of satellite imagery

Science.gov (United States)

Kim, Hongsuk H.; Elman, Gregory C.

1990-01-01

Sets of Thematic Mapper (TM) imagery taken over the Washington, DC metropolitan area during the months of November, March and May were converted into a form of ground reflectance imagery. This conversion was accomplished by adjusting the incident sunlight and view angles and by applying a pixel-by-pixel correction for atmospheric effects. Seasonal color changes of the area can be better observed when such normalization is applied to space imagery taken in time series. In normalized imagery, the grey scale depicts variations in surface reflectance and tonal signature of multi-band color imagery can be directly interpreted for quantitative information of the target.

Large-area parallel near-field optical nanopatterning of functional materials using microsphere mask

Energy Technology Data Exchange (ETDEWEB)

Chen, G.X. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Hong, M.H. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)], E-mail: Hong_Minghui@dsi.a-star.edu.sg; Lin, Y. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Wang, Z.B. [Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Ng, D.K.T. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Xie, Q. [Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Tan, L.S. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Chong, T.C. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)

2008-01-31

Large-area parallel near-field optical nanopatterning on functional material surfaces was investigated with KrF excimer laser irradiation. A monolayer of silicon dioxide microspheres was self-assembled on the sample surfaces as the processing mask. Nanoholes and nanospots were obtained on silicon surfaces and thin silver films, respectively. The nanopatterning results were affected by the refractive indices of the surrounding media. Near-field optical enhancement beneath the microspheres is the physical origin of nanostructure formation. Theoretical calculation was performed to study the intensity of optical field distributions under the microspheres according to the light scattering model of a sphere on the substrate.

Fault detection for hydraulic pump based on chaotic parallel RBF network

Directory of Open Access Journals (Sweden)

Ma Ning

2011-01-01

Full Text Available Abstract In this article, a parallel radial basis function network in conjunction with chaos theory (CPRBF network is presented, and applied to practical fault detection for hydraulic pump, which is a critical component in aircraft. The CPRBF network consists of a number of radial basis function (RBF subnets connected in parallel. The number of input nodes for each RBF subnet is determined by different embedding dimension based on chaotic phase-space reconstruction. The output of CPRBF is a weighted sum of all RBF subnets. It was first trained using the dataset from normal state without fault, and then a residual error generator was designed to detect failures based on the trained CPRBF network. Then, failure detection can be achieved by the analysis of the residual error. Finally, two case studies are introduced to compare the proposed CPRBF network with traditional RBF networks, in terms of prediction and detection accuracy.

Multipactor saturation in parallel-plate waveguides

International Nuclear Information System (INIS)

Sorolla, E.; Mattes, M.

2012-01-01

The saturation stage of a multipactor discharge is considered of interest, since it can guide towards a criterion to assess the multipactor onset. The electron cloud under multipactor regime within a parallel-plate waveguide is modeled by a thin continuous distribution of charge and the equations of motion are calculated taking into account the space charge effects. The saturation is identified by the interaction of the electron cloud with its image charge. The stability of the electron population growth is analyzed and two mechanisms of saturation to explain the steady-state multipactor for voltages near above the threshold onset are identified. The impact energy in the collision against the metal plates decreases during the electron population growth due to the attraction of the electron sheet on the image through the initial plate. When this growth remains stable till the impact energy reaches the first cross-over point, the electron surface density tends to a constant value. When the stability is broken before reaching the first cross-over point the surface charge density oscillates chaotically bounded within a certain range. In this case, an expression to calculate the maximum electron surface charge density is found whose predictions agree with the simulations when the voltage is not too high.

Vectorization, parallelization and porting of nuclear codes. Vectorization and parallelization. Progress report fiscal 1999

Energy Technology Data Exchange (ETDEWEB)

Adachi, Masaaki; Ogasawara, Shinobu; Kume, Etsuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishizuki, Shigeru; Nemoto, Toshiyuki; Kawasaki, Nobuo; Kawai, Wataru [Fujitsu Ltd., Tokyo (Japan); Yatake, Yo-ichi [Hitachi Ltd., Tokyo (Japan)

2001-02-01

Several computer codes in the nuclear field have been vectorized, parallelized and trans-ported on the FUJITSU VPP500 system, the AP3000 system, the SX-4 system and the Paragon system at Center for Promotion of Computational Science and Engineering in Japan Atomic Energy Research Institute. We dealt with 18 codes in fiscal 1999. These results are reported in 3 parts, i.e., the vectorization and the parallelization part on vector processors, the parallelization part on scalar processors and the porting part. In this report, we describe the vectorization and parallelization on vector processors. In this vectorization and parallelization on vector processors part, the vectorization of Relativistic Molecular Orbital Calculation code RSCAT, a microscopic transport code for high energy nuclear collisions code JAM, three-dimensional non-steady thermal-fluid analysis code STREAM, Relativistic Density Functional Theory code RDFT and High Speed Three-Dimensional Nodal Diffusion code MOSRA-Light on the VPP500 system and the SX-4 system are described. (author)

Parallel R-matrix computation

International Nuclear Information System (INIS)

Heggarty, J.W.

1999-06-01

For almost thirty years, sequential R-matrix computation has been used by atomic physics research groups, from around the world, to model collision phenomena involving the scattering of electrons or positrons with atomic or molecular targets. As considerable progress has been made in the understanding of fundamental scattering processes, new data, obtained from more complex calculations, is of current interest to experimentalists. Performing such calculations, however, places considerable demands on the computational resources to be provided by the target machine, in terms of both processor speed and memory requirement. Indeed, in some instances the computational requirements are so great that the proposed R-matrix calculations are intractable, even when utilising contemporary classic supercomputers. Historically, increases in the computational requirements of R-matrix computation were accommodated by porting the problem codes to a more powerful classic supercomputer. Although this approach has been successful in the past, it is no longer considered to be a satisfactory solution due to the limitations of current (and future) Von Neumann machines. As a consequence, there has been considerable interest in the high performance multicomputers, that have emerged over the last decade which appear to offer the computational resources required by contemporary R-matrix research. Unfortunately, developing codes for these machines is not as simple a task as it was to develop codes for successive classic supercomputers. The difficulty arises from the considerable differences in the computing models that exist between the two types of machine and results in the programming of multicomputers to be widely acknowledged as a difficult, time consuming and error-prone task. Nevertheless, unless parallel R-matrix computation is realised, important theoretical and experimental atomic physics research will continue to be hindered. This thesis describes work that was undertaken in

Implementation and performance of parallelized elegant

International Nuclear Information System (INIS)

Wang, Y.; Borland, M.

2008-01-01

The program elegant is widely used for design and modeling of linacs for free-electron lasers and energy recovery linacs, as well as storage rings and other applications. As part of a multi-year effort, we have parallelized many aspects of the code, including single-particle dynamics, wakefields, and coherent synchrotron radiation. We report on the approach used for gradual parallelization, which proved very beneficial in getting parallel features into the hands of users quickly. We also report details of parallelization of collective effects. Finally, we discuss performance of the parallelized code in various applications.

Parallelizing the spectral transform method: A comparison of alternative parallel algorithms

International Nuclear Information System (INIS)

Foster, I.; Worley, P.H.

1993-01-01

The spectral transform method is a standard numerical technique for solving partial differential equations on the sphere and is widely used in global climate modeling. In this paper, we outline different approaches to parallelizing the method and describe experiments that we are conducting to evaluate the efficiency of these approaches on parallel computers. The experiments are conducted using a testbed code that solves the nonlinear shallow water equations on a sphere, but are designed to permit evaluation in the context of a global model. They allow us to evaluate the relative merits of the approaches as a function of problem size and number of processors. The results of this study are guiding ongoing work on PCCM2, a parallel implementation of the Community Climate Model developed at the National Center for Atmospheric Research

Algorithms for parallel computers

International Nuclear Information System (INIS)

Churchhouse, R.F.

1985-01-01

Until relatively recently almost all the algorithms for use on computers had been designed on the (usually unstated) assumption that they were to be run on single processor, serial machines. With the introduction of vector processors, array processors and interconnected systems of mainframes, minis and micros, however, various forms of parallelism have become available. The advantage of parallelism is that it offers increased overall processing speed but it also raises some fundamental questions, including: (i) which, if any, of the existing 'serial' algorithms can be adapted for use in the parallel mode. (ii) How close to optimal can such adapted algorithms be and, where relevant, what are the convergence criteria. (iii) How can we design new algorithms specifically for parallel systems. (iv) For multi-processor systems how can we handle the software aspects of the interprocessor communications. Aspects of these questions illustrated by examples are considered in these lectures. (orig.)

Parallel processing for fluid dynamics applications

International Nuclear Information System (INIS)

Johnson, G.M.

1989-01-01

The impact of parallel processing on computational science and, in particular, on computational fluid dynamics is growing rapidly. In this paper, particular emphasis is given to developments which have occurred within the past two years. Parallel processing is defined and the reasons for its importance in high-performance computing are reviewed. Parallel computer architectures are classified according to the number and power of their processing units, their memory, and the nature of their connection scheme. Architectures which show promise for fluid dynamics applications are emphasized. Fluid dynamics problems are examined for parallelism inherent at the physical level. CFD algorithms and their mappings onto parallel architectures are discussed. Several example are presented to document the performance of fluid dynamics applications on present-generation parallel processing devices

Poiseuille, thermal transpiration and Couette flows of a rarefied gas between plane parallel walls with nonuniform surface properties in the transverse direction and their reciprocity relations

Science.gov (United States)

Doi, Toshiyuki

2018-04-01

Slow flows of a rarefied gas between two plane parallel walls with nonuniform surface properties are studied based on kinetic theory. It is assumed that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary whose accommodation coefficient varies periodically in the direction perpendicular to the flow. The time-independent Poiseuille, thermal transpiration and Couette flows are considered. The flow behavior is numerically studied based on the linearized Bhatnagar-Gross-Krook-Welander model of the Boltzmann equation. The flow field, the mass and heat flow rates in the gas, and the tangential force acting on the wall surface are studied over a wide range of the gas rarefaction degree and the parameters characterizing the distribution of the accommodation coefficient. The locally convex velocity distribution is observed in Couette flow of a highly rarefied gas, similarly to Poiseuille flow and thermal transpiration. The reciprocity relations are numerically confirmed over a wide range of the flow parameters.

Parallel discrete event simulation

NARCIS (Netherlands)

Overeinder, B.J.; Hertzberger, L.O.; Sloot, P.M.A.; Withagen, W.J.

1991-01-01

In simulating applications for execution on specific computing systems, the simulation performance figures must be known in a short period of time. One basic approach to the problem of reducing the required simulation time is the exploitation of parallelism. However, in parallelizing the simulation

Data Parallel Line Relaxation (DPLR) Code User Manual: Acadia - Version 4.01.1

Science.gov (United States)

Wright, Michael J.; White, Todd; Mangini, Nancy

2009-01-01

Data-Parallel Line Relaxation (DPLR) code is a computational fluid dynamic (CFD) solver that was developed at NASA Ames Research Center to help mission support teams generate high-value predictive solutions for hypersonic flow field problems. The DPLR Code Package is an MPI-based, parallel, full three-dimensional Navier-Stokes CFD solver with generalized models for finite-rate reaction kinetics, thermal and chemical non-equilibrium, accurate high-temperature transport coefficients, and ionized flow physics incorporated into the code. DPLR also includes a large selection of generalized realistic surface boundary conditions and links to enable loose coupling with external thermal protection system (TPS) material response and shock layer radiation codes.

Overview of the Force Scientific Parallel Language

Directory of Open Access Journals (Sweden)

Gita Alaghband

1994-01-01

Full Text Available The Force parallel programming language designed for large-scale shared-memory multiprocessors is presented. The language provides a number of parallel constructs as extensions to the ordinary Fortran language and is implemented as a two-level macro preprocessor to support portability across shared memory multiprocessors. The global parallelism model on which the Force is based provides a powerful parallel language. The parallel constructs, generic synchronization, and freedom from process management supported by the Force has resulted in structured parallel programs that are ported to the many multiprocessors on which the Force is implemented. Two new parallel constructs for looping and functional decomposition are discussed. Several programming examples to illustrate some parallel programming approaches using the Force are also presented.

The Galley Parallel File System

Science.gov (United States)

Nieuwejaar, Nils; Kotz, David

1996-01-01

Most current multiprocessor file systems are designed to use multiple disks in parallel, using the high aggregate bandwidth to meet the growing I/0 requirements of parallel scientific applications. Many multiprocessor file systems provide applications with a conventional Unix-like interface, allowing the application to access multiple disks transparently. This interface conceals the parallelism within the file system, increasing the ease of programmability, but making it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. In addition to providing an insufficient interface, most current multiprocessor file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic scientific multiprocessor workloads. We discuss Galley's file structure and application interface, as well as the performance advantages offered by that interface.

PDDP, A Data Parallel Programming Model

Directory of Open Access Journals (Sweden)

Karen H. Warren

1996-01-01

Full Text Available PDDP, the parallel data distribution preprocessor, is a data parallel programming model for distributed memory parallel computers. PDDP implements high-performance Fortran-compatible data distribution directives and parallelism expressed by the use of Fortran 90 array syntax, the FORALL statement, and the WHERE construct. Distributed data objects belong to a global name space; other data objects are treated as local and replicated on each processor. PDDP allows the user to program in a shared memory style and generates codes that are portable to a variety of parallel machines. For interprocessor communication, PDDP uses the fastest communication primitives on each platform.

Design considerations for parallel graphics libraries

Science.gov (United States)

Crockett, Thomas W.

1994-01-01

Applications which run on parallel supercomputers are often characterized by massive datasets. Converting these vast collections of numbers to visual form has proven to be a powerful aid to comprehension. For a variety of reasons, it may be desirable to provide this visual feedback at runtime. One way to accomplish this is to exploit the available parallelism to perform graphics operations in place. In order to do this, we need appropriate parallel rendering algorithms and library interfaces. This paper provides a tutorial introduction to some of the issues which arise in designing parallel graphics libraries and their underlying rendering algorithms. The focus is on polygon rendering for distributed memory message-passing systems. We illustrate our discussion with examples from PGL, a parallel graphics library which has been developed on the Intel family of parallel systems.

First results on irradiation of ceramic parallel plate chambers with gammas and neutrons

International Nuclear Information System (INIS)

Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C.; Dajko, G.; D'Alessandro, R.; Fenyvesi, A.; Ferrando, A.; Fouz, M.C.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Malinin, A.; Meschini, M.; Molnar, J.; Pojidaev, V.; Salicio, J.M.; Tanko, L.; Vesztergombi, G.

1996-01-01

Ceramic parallel plate chambers were irradiated with gamma rays and neutrons. Results on radiation resistance are presented after 60 Mrad gamma and 0.5.10 16 neutrons per cm 2 irradiation of the detector surface. Results of activation analysis of chambers made of two different ceramic materials are also presented. (orig.)

On the problem of propagation of magnetoplasma surface waves in semiconductors

International Nuclear Information System (INIS)

Davydov, A.B.; Zakharov, V.A.

1975-01-01

A calculation is made of the spectrum of surface waves traveling along a boundary separating a dielectric from a magnetized semiconductor plasma parallel or at right angles to a magnetic field B. Dispersion relationships are obtained for the k is parallel to B case and these relationships explain the origin of the investigated surface waves on the boundary of a two-component (electron-hole) plasma in InSb. An analysis is made of the dispersion of the surface waves in the k is perpendicular to B case, which leads to a nonreciprocal propagation. (author)

Surface Topography Hinders Bacterial Surface Motility.

Science.gov (United States)

Chang, Yow-Ren; Weeks, Eric R; Ducker, William A

2018-03-21

We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower. That is, there is a threshold between 1 and 2 μm for response to the topography. Cells on the 4 μm hemispheres were more likely to travel parallel to the local crystal axis than in other directions. Cells on the 8 μm topography were less likely to travel across the crowns of the hemispheres and were also more likely to make 30°-50° turns than on flat surfaces. These results show that surface topography can act as a significant barrier to surface motility and may therefore hinder surface exploration by bacteria. Because surface exploration can be a part of the process whereby bacteria form colonies and seek nutrients, these results help to elucidate the mechanism by which surface topography hinders biofilm formation.

Automatic Loop Parallelization via Compiler Guided Refactoring

DEFF Research Database (Denmark)

Larsen, Per; Ladelsky, Razya; Lidman, Jacob

For many parallel applications, performance relies not on instruction-level parallelism, but on loop-level parallelism. Unfortunately, many modern applications are written in ways that obstruct automatic loop parallelization. Since we cannot identify sufficient parallelization opportunities...... for these codes in a static, off-line compiler, we developed an interactive compilation feedback system that guides the programmer in iteratively modifying application source, thereby improving the compiler’s ability to generate loop-parallel code. We use this compilation system to modify two sequential...... benchmarks, finding that the code parallelized in this way runs up to 8.3 times faster on an octo-core Intel Xeon 5570 system and up to 12.5 times faster on a quad-core IBM POWER6 system. Benchmark performance varies significantly between the systems. This suggests that semi-automatic parallelization should...

Aspects of computation on asynchronous parallel processors

International Nuclear Information System (INIS)

Wright, M.

1989-01-01

The increasing availability of asynchronous parallel processors has provided opportunities for original and useful work in scientific computing. However, the field of parallel computing is still in a highly volatile state, and researchers display a wide range of opinion about many fundamental questions such as models of parallelism, approaches for detecting and analyzing parallelism of algorithms, and tools that allow software developers and users to make effective use of diverse forms of complex hardware. This volume collects the work of researchers specializing in different aspects of parallel computing, who met to discuss the framework and the mechanics of numerical computing. The far-reaching impact of high-performance asynchronous systems is reflected in the wide variety of topics, which include scientific applications (e.g. linear algebra, lattice gauge simulation, ordinary and partial differential equations), models of parallelism, parallel language features, task scheduling, automatic parallelization techniques, tools for algorithm development in parallel environments, and system design issues

Mn-silicide nanostructures aligned on massively parallel silicon nano-ribbons

International Nuclear Information System (INIS)

De Padova, Paola; Ottaviani, Carlo; Ronci, Fabio; Colonna, Stefano; Quaresima, Claudio; Cricenti, Antonio; Olivieri, Bruno; Dávila, Maria E; Hennies, Franz; Pietzsch, Annette; Shariati, Nina; Le Lay, Guy

2013-01-01

The growth of Mn nanostructures on a 1D grating of silicon nano-ribbons is investigated at atomic scale by means of scanning tunneling microscopy, low energy electron diffraction and core level photoelectron spectroscopy. The grating of silicon nano-ribbons represents an atomic scale template that can be used in a surface-driven route to control the combination of Si with Mn in the development of novel materials for spintronics devices. The Mn atoms show a preferential adsorption site on silicon atoms, forming one-dimensional nanostructures. They are parallel oriented with respect to the surface Si array, which probably predetermines the diffusion pathways of the Mn atoms during the process of nanostructure formation.

Depth-Averaged Non-Hydrostatic Hydrodynamic Model Using a New Multithreading Parallel Computing Method

Directory of Open Access Journals (Sweden)

Ling Kang

2017-03-01

Full Text Available Compared to the hydrostatic hydrodynamic model, the non-hydrostatic hydrodynamic model can accurately simulate flows that feature vertical accelerations. The model’s low computational efficiency severely restricts its wider application. This paper proposes a non-hydrostatic hydrodynamic model based on a multithreading parallel computing method. The horizontal momentum equation is obtained by integrating the Navier–Stokes equations from the bottom to the free surface. The vertical momentum equation is approximated by the Keller-box scheme. A two-step method is used to solve the model equations. A parallel strategy based on block decomposition computation is utilized. The original computational domain is subdivided into two subdomains that are physically connected via a virtual boundary technique. Two sub-threads are created and tasked with the computation of the two subdomains. The producer–consumer model and the thread lock technique are used to achieve synchronous communication between sub-threads. The validity of the model was verified by solitary wave propagation experiments over a flat bottom and slope, followed by two sinusoidal wave propagation experiments over submerged breakwater. The parallel computing method proposed here was found to effectively enhance computational efficiency and save 20%–40% computation time compared to serial computing. The parallel acceleration rate and acceleration efficiency are approximately 1.45% and 72%, respectively. The parallel computing method makes a contribution to the popularization of non-hydrostatic models.

Exponential model normalization for electrical capacitance tomography with external electrodes under gap permittivity conditions

International Nuclear Information System (INIS)

Baidillah, Marlin R; Takei, Masahiro

2017-01-01

A nonlinear normalization model which is called exponential model for electrical capacitance tomography (ECT) with external electrodes under gap permittivity conditions has been developed. The exponential model normalization is proposed based on the inherently nonlinear relationship characteristic between the mixture permittivity and the measured capacitance due to the gap permittivity of inner wall. The parameters of exponential equation are derived by using an exponential fitting curve based on the simulation and a scaling function is added to adjust the experiment system condition. The exponential model normalization was applied to two dimensional low and high contrast dielectric distribution phantoms by using simulation and experimental studies. The proposed normalization model has been compared with other normalization models i.e. Parallel, Series, Maxwell and Böttcher models. Based on the comparison of image reconstruction results, the exponential model is reliable to predict the nonlinear normalization of measured capacitance in term of low and high contrast dielectric distribution. (paper)

Modeling and experimental study of oil/water contact angle on biomimetic micro-parallel-patterned self-cleaning surfaces of selected alloys used in water industry

Energy Technology Data Exchange (ETDEWEB)

Nickelsen, Simin; Moghadam, Afsaneh Dorri, E-mail: afsaneh@uwm.edu; Ferguson, J.B.; Rohatgi, Pradeep

2015-10-30

Graphical abstract: - Highlights: • Wetting behavior of four metallic materials as a function of surface roughness has been studied. • A model to predict the abrasive particle size and water/oil contact angles relationship is proposed. • Active wetting regime is determined in different materials using the proposed model. - Abstract: In the present study, the wetting behavior of surfaces of various common metallic materials used in the water industry including C84400 brass, commercially pure aluminum (99.0% pure), Nickle–Molybdenum alloy (Hastelloy C22), and 316 Stainless Steel prepared by mechanical abrasion and contact angles of several materials after mechanical abrasion were measured. A model to estimate roughness factor, R{sub f}, and fraction of solid/oil interface, ƒ{sub so}, for surfaces prepared by mechanical abrasion is proposed based on the assumption that abrasive particles acting on a metallic surface would result in scratches parallel to each other and each scratch would have a semi-round cross-section. The model geometrically describes the relation between sandpaper particle size and water/oil contact angle predicted by both the Wenzel and Cassie–Baxter contact type, which can then be used for comparison with experimental data to find which regime is active. Results show that brass and Hastelloy followed Cassie–Baxter behavior, aluminum followed Wenzel behavior and stainless steel exhibited a transition from Wenzel to Cassie–Baxter. Microstructural studies have also been done to rule out effects beyond the Wenzel and Cassie–Baxter theories such as size of structural details.

Numerical studies on the interaction between atmosphere and ocean using different kinds of parallel computers

International Nuclear Information System (INIS)

Lee, Soon-Hwan; Chino, Masamichi

2000-01-01

The coupling between atmosphere and ocean model has physical and computational difficulties for short-term forecasting of weather and ocean current. In this research, a combination system between high-resolution meso-scale atmospheric model and ocean model has been constructed using a new message-passing library, called Stampi (Seamless Thinking Aid Message Passing Interface), for prediction of particle dispersion at emergency nuclear accident. Stampi, which is based on the MPI (Message Passing Interface) 2 specification, makes us carry out parallel calculations of combination system without parallelization skill to model code. And it realizes dynamic process creation on different machines and communication between spawned one within the scope of MPI semantics. The models included in this combination system are PHYSIC as an atmosphere model, and POM (Princeton Ocean Model) as an ocean model. We applied this combination system to predict sea surface current at Sea of Japan in winter season. Simulation results indicate that the wind stress near the sea surface tends to be a predominant factor to determine surface ocean currents and dispersion of radioactive contamination in the ocean. The surface ocean current is well correspondent with wind direction, induced by high mountains at North Korea. The satellite data of NSCAT (NASA-SCATterometer), which is an image of sea surface current, also agrees well with the results of this system. (author)

Heterodyne frequency-domain multispectral diffuse optical tomography of breast cancer in the parallel-plane transmission geometry

Energy Technology Data Exchange (ETDEWEB)

Ban, H. Y.; Kavuri, V. C., E-mail: venk@physics.upenn.edu; Cochran, J. M.; Pathak, S.; Chung, S. H.; Yodh, A. G. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Schweiger, M.; Arridge, S. R. [Department of Computer Science, University College London, London WC1E 7JE (United Kingdom); Xie, L. [Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Busch, D. R. [Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104 (United States); Katrašnik, J. [Faculty of Electrical Engineering, University of Ljubljana, Ljubljana 1000 (Slovenia); Lee, K. [Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-813 (Korea, Republic of); Choe, R. [Department of Biomedical Engineering, University of Rochester, Rochester, New York 14642 (United States); Czerniecki, B. J. [Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2016-07-15

Purpose: The authors introduce a state-of-the-art all-optical clinical diffuse optical tomography (DOT) imaging instrument which collects spatially dense, multispectral, frequency-domain breast data in the parallel-plate geometry. Methods: The instrument utilizes a CCD-based heterodyne detection scheme that permits massively parallel detection of diffuse photon density wave amplitude and phase for a large number of source–detector pairs (10{sup 6}). The stand-alone clinical DOT instrument thus offers high spatial resolution with reduced crosstalk between absorption and scattering. Other novel features include a fringe profilometry system for breast boundary segmentation, real-time data normalization, and a patient bed design which permits both axial and sagittal breast measurements. Results: The authors validated the instrument using tissue simulating phantoms with two different chromophore-containing targets and one scattering target. The authors also demonstrated the instrument in a case study breast cancer patient; the reconstructed 3D image of endogenous chromophores and scattering gave tumor localization in agreement with MRI. Conclusions: Imaging with a novel parallel-plate DOT breast imager that employs highly parallel, high-resolution CCD detection in the frequency-domain was demonstrated.

Generating multiplex gradients of biomolecules for controlling cellular adhesion in parallel microfluidic channels.

Science.gov (United States)

Didar, Tohid Fatanat; Tabrizian, Maryam

2012-11-07

Here we present a microfluidic platform to generate multiplex gradients of biomolecules within parallel microfluidic channels, in which a range of multiplex concentration gradients with different profile shapes are simultaneously produced. Nonlinear polynomial gradients were also generated using this device. The gradient generation principle is based on implementing parrallel channels with each providing a different hydrodynamic resistance. The generated biomolecule gradients were then covalently functionalized onto the microchannel surfaces. Surface gradients along the channel width were a result of covalent attachments of biomolecules to the surface, which remained functional under high shear stresses (50 dyn/cm(2)). An IgG antibody conjugated to three different fluorescence dyes (FITC, Cy5 and Cy3) was used to demonstrate the resulting multiplex concentration gradients of biomolecules. The device enabled generation of gradients with up to three different biomolecules in each channel with varying concentration profiles. We were also able to produce 2-dimensional gradients in which biomolecules were distributed along the length and width of the channel. To demonstrate the applicability of the developed design, three different multiplex concentration gradients of REDV and KRSR peptides were patterned along the width of three parallel channels and adhesion of primary human umbilical vein endothelial cell (HUVEC) in each channel was subsequently investigated using a single chip.

Preliminary surface analysis of etched, bleached, and normal bovine enamel

International Nuclear Information System (INIS)

Ruse, N.D.; Smith, D.C.; Torneck, C.D.; Titley, K.C.

1990-01-01

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness

Parallelization of 2-D lattice Boltzmann codes

International Nuclear Information System (INIS)

Suzuki, Soichiro; Kaburaki, Hideo; Yokokawa, Mitsuo.

1996-03-01

Lattice Boltzmann (LB) codes to simulate two dimensional fluid flow are developed on vector parallel computer Fujitsu VPP500 and scalar parallel computer Intel Paragon XP/S. While a 2-D domain decomposition method is used for the scalar parallel LB code, a 1-D domain decomposition method is used for the vector parallel LB code to be vectorized along with the axis perpendicular to the direction of the decomposition. High parallel efficiency of 95.1% by the vector parallel calculation on 16 processors with 1152x1152 grid and 88.6% by the scalar parallel calculation on 100 processors with 800x800 grid are obtained. The performance models are developed to analyze the performance of the LB codes. It is shown by our performance models that the execution speed of the vector parallel code is about one hundred times faster than that of the scalar parallel code with the same number of processors up to 100 processors. We also analyze the scalability in keeping the available memory size of one processor element at maximum. Our performance model predicts that the execution time of the vector parallel code increases about 3% on 500 processors. Although the 1-D domain decomposition method has in general a drawback in the interprocessor communication, the vector parallel LB code is still suitable for the large scale and/or high resolution simulations. (author)

Parallelization of 2-D lattice Boltzmann codes

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Soichiro; Kaburaki, Hideo; Yokokawa, Mitsuo

1996-03-01

Lattice Boltzmann (LB) codes to simulate two dimensional fluid flow are developed on vector parallel computer Fujitsu VPP500 and scalar parallel computer Intel Paragon XP/S. While a 2-D domain decomposition method is used for the scalar parallel LB code, a 1-D domain decomposition method is used for the vector parallel LB code to be vectorized along with the axis perpendicular to the direction of the decomposition. High parallel efficiency of 95.1% by the vector parallel calculation on 16 processors with 1152x1152 grid and 88.6% by the scalar parallel calculation on 100 processors with 800x800 grid are obtained. The performance models are developed to analyze the performance of the LB codes. It is shown by our performance models that the execution speed of the vector parallel code is about one hundred times faster than that of the scalar parallel code with the same number of processors up to 100 processors. We also analyze the scalability in keeping the available memory size of one processor element at maximum. Our performance model predicts that the execution time of the vector parallel code increases about 3% on 500 processors. Although the 1-D domain decomposition method has in general a drawback in the interprocessor communication, the vector parallel LB code is still suitable for the large scale and/or high resolution simulations. (author).

Explorations of the implementation of a parallel IDW interpolation algorithm in a Linux cluster-based parallel GIS

Science.gov (United States)

Huang, Fang; Liu, Dingsheng; Tan, Xicheng; Wang, Jian; Chen, Yunping; He, Binbin

2011-04-01

To design and implement an open-source parallel GIS (OP-GIS) based on a Linux cluster, the parallel inverse distance weighting (IDW) interpolation algorithm has been chosen as an example to explore the working model and the principle of algorithm parallel pattern (APP), one of the parallelization patterns for OP-GIS. Based on an analysis of the serial IDW interpolation algorithm of GRASS GIS, this paper has proposed and designed a specific parallel IDW interpolation algorithm, incorporating both single process, multiple data (SPMD) and master/slave (M/S) programming modes. The main steps of the parallel IDW interpolation algorithm are: (1) the master node packages the related information, and then broadcasts it to the slave nodes; (2) each node calculates its assigned data extent along one row using the serial algorithm; (3) the master node gathers the data from all nodes; and (4) iterations continue until all rows have been processed, after which the results are outputted. According to the experiments performed in the course of this work, the parallel IDW interpolation algorithm can attain an efficiency greater than 0.93 compared with similar algorithms, which indicates that the parallel algorithm can greatly reduce processing time and maximize speed and performance.

Bianchi surfaces: integrability in an arbitrary parametrization

International Nuclear Information System (INIS)

Nieszporski, Maciej; Sym, Antoni

2009-01-01

We discuss integrability of normal field equations of arbitrarily parametrized Bianchi surfaces. A geometric definition of the Bianchi surfaces is presented as well as the Baecklund transformation for the normal field equations in an arbitrarily chosen surface parametrization.

Parallel Monte Carlo reactor neutronics

International Nuclear Information System (INIS)

Blomquist, R.N.; Brown, F.B.

1994-01-01

The issues affecting implementation of parallel algorithms for large-scale engineering Monte Carlo neutron transport simulations are discussed. For nuclear reactor calculations, these include load balancing, recoding effort, reproducibility, domain decomposition techniques, I/O minimization, and strategies for different parallel architectures. Two codes were parallelized and tested for performance. The architectures employed include SIMD, MIMD-distributed memory, and workstation network with uneven interactive load. Speedups linear with the number of nodes were achieved

The normalization of surface anisotropy effects present in SEVIRI reflectances by using the MODIS BRDF method

DEFF Research Database (Denmark)

Proud, Simon Richard; Zhang, Qingling; Schaaf, Crystal

2014-01-01

A modified version of the MODerate resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) algorithm is presented for use in the angular normalization of surface reflectance data gathered by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI...... acquisition period than the comparable MODIS products while, at the same time, removing many of the angular perturbations present within the original MSG data. The NBAR data are validated against reflectance data from the MODIS instrument and in situ data gathered at a field location in Africa throughout 2008....... It is found that the MSG retrievals are stable and are of high-quality across much of the SEVIRI disk while maintaining a higher temporal resolution than the MODIS BRDF products. However, a number of circumstances are discovered whereby the BRDF model is unable to function correctly with the SEVIRI...

M-dwarf exoplanet surface density distribution. A log-normal fit from 0.07 to 400 AU

Science.gov (United States)

Meyer, Michael R.; Amara, Adam; Reggiani, Maddalena; Quanz, Sascha P.

2018-04-01

Aims: We fit a log-normal function to the M-dwarf orbital surface density distribution of gas giant planets, over the mass range 1-10 times that of Jupiter, from 0.07 to 400 AU. Methods: We used a Markov chain Monte Carlo approach to explore the likelihoods of various parameter values consistent with point estimates of the data given our assumed functional form. Results: This fit is consistent with radial velocity, microlensing, and direct-imaging observations, is well-motivated from theoretical and phenomenological points of view, and predicts results of future surveys. We present probability distributions for each parameter and a maximum likelihood estimate solution. Conclusions: We suggest that this function makes more physical sense than other widely used functions, and we explore the implications of our results on the design of future exoplanet surveys.

The effects of shear and normal stress paths on rock friction

International Nuclear Information System (INIS)

Olsson, W.A.

1990-01-01

The effect of variable normal stress on the coefficient of friction of smooth artificial surfaces in welded tuff was studied. The shear stress response to changes in normal stress during constant-velocity sliding suggests that friction depends on the history of the normal stress; or, more generally, the path in shear/normal stress space. 6 refs., 5 figs

Parallel Implicit Algorithms for CFD

Science.gov (United States)

Keyes, David E.

1998-01-01

The main goal of this project was efficient distributed parallel and workstation cluster implementations of Newton-Krylov-Schwarz (NKS) solvers for implicit Computational Fluid Dynamics (CFD.) "Newton" refers to a quadratically convergent nonlinear iteration using gradient information based on the true residual, "Krylov" to an inner linear iteration that accesses the Jacobian matrix only through highly parallelizable sparse matrix-vector products, and "Schwarz" to a domain decomposition form of preconditioning the inner Krylov iterations with primarily neighbor-only exchange of data between the processors. Prior experience has established that Newton-Krylov methods are competitive solvers in the CFD context and that Krylov-Schwarz methods port well to distributed memory computers. The combination of the techniques into Newton-Krylov-Schwarz was implemented on 2D and 3D unstructured Euler codes on the parallel testbeds that used to be at LaRC and on several other parallel computers operated by other agencies or made available by the vendors. Early implementations were made directly in Massively Parallel Integration (MPI) with parallel solvers we adapted from legacy NASA codes and enhanced for full NKS functionality. Later implementations were made in the framework of the PETSC library from Argonne National Laboratory, which now includes pseudo-transient continuation Newton-Krylov-Schwarz solver capability (as a result of demands we made upon PETSC during our early porting experiences). A secondary project pursued with funding from this contract was parallel implicit solvers in acoustics, specifically in the Helmholtz formulation. A 2D acoustic inverse problem has been solved in parallel within the PETSC framework.

Parallel kinematics type, kinematics, and optimal design

CERN Document Server

Liu, Xin-Jun

2014-01-01

Parallel Kinematics- Type, Kinematics, and Optimal Design presents the results of 15 year's research on parallel mechanisms and parallel kinematics machines. This book covers the systematic classification of parallel mechanisms (PMs) as well as providing a large number of mechanical architectures of PMs available for use in practical applications. It focuses on the kinematic design of parallel robots. One successful application of parallel mechanisms in the field of machine tools, which is also called parallel kinematics machines, has been the emerging trend in advanced machine tools. The book describes not only the main aspects and important topics in parallel kinematics, but also references novel concepts and approaches, i.e. type synthesis based on evolution, performance evaluation and optimization based on screw theory, singularity model taking into account motion and force transmissibility, and others.   This book is intended for researchers, scientists, engineers and postgraduates or above with interes...

Possible origin and significance of extension-parallel drainages in Arizona's metamophic core complexes

Science.gov (United States)

Spencer, J.E.

2000-01-01

The corrugated form of the Harcuvar, South Mountains, and Catalina metamorphic core complexes in Arizona reflects the shape of the middle Tertiary extensional detachment fault that projects over each complex. Corrugation axes are approximately parallel to the fault-displacement direction and to the footwall mylonitic lineation. The core complexes are locally incised by enigmatic, linear drainages that parallel corrugation axes and the inferred extension direction and are especially conspicuous on the crests of antiformal corrugations. These drainages have been attributed to erosional incision on a freshly denuded, planar, inclined fault ramp followed by folding that elevated and preserved some drainages on the crests of rising antiforms. According to this hypothesis, corrugations were produced by folding after subacrial exposure of detachment-fault foot-walls. An alternative hypothesis, proposed here, is as follows. In a setting where preexisting drainages cross an active normal fault, each fault-slip event will cut each drainage into two segments separated by a freshly denuded fault ramp. The upper and lower drainage segments will remain hydraulically linked after each fault-slip event if the drainage in the hanging-wall block is incised, even if the stream is on the flank of an antiformal corrugation and there is a large component of strike-slip fault movement. Maintenance of hydraulic linkage during sequential fault-slip events will guide the lengthening stream down the fault ramp as the ramp is uncovered, and stream incision will form a progressively lengthening, extension-parallel, linear drainage segment. This mechanism for linear drainage genesis is compatible with corrugations as original irregularities of the detachment fault, and does not require folding after early to middle Miocene footwall exhumations. This is desirable because many drainages are incised into nonmylonitic crystalline footwall rocks that were probably not folded under low

How Parallel Are Excited State Potential Energy Surfaces from Time-Independent and Time-Dependent DFT? A BODIPY Dye Case Study.

Science.gov (United States)

Komoto, Keenan T; Kowalczyk, Tim

2016-10-06

To support the development and characterization of chromophores with targeted photophysical properties, excited-state electronic structure calculations should rapidly and accurately predict how derivatization of a chromophore will affect its excitation and emission energies. This paper examines whether a time-independent excited-state density functional theory (DFT) approach meets this need through a case study of BODIPY chromophore photophysics. A restricted open-shell Kohn-Sham (ROKS) treatment of the S 1 excited state of BODIPY dyes is contrasted with linear-response time-dependent density functional theory (TDDFT). Vertical excitation energies predicted by the two approaches are remarkably different due to overestimation by TDDFT and underestimation by ROKS relative to experiment. Overall, ROKS with a standard hybrid functional provides the more accurate description of the S 1 excited state of BODIPY dyes, but excitation energies computed by the two methods are strongly correlated. The two approaches also make similar predictions of shifts in the excitation energy upon functionalization of the chromophore. TDDFT and ROKS models of the S 1 potential energy surface are then examined in detail for a representative BODIPY dye through molecular dynamics sampling on both model surfaces. We identify the most significant differences in the sampled surfaces and analyze these differences along selected normal modes. Differences between ROKS and TDDFT descriptions of the S 1 potential energy surface for this BODIPY derivative highlight the continuing need for validation of widely used approximations in excited state DFT through experimental benchmarking and comparison to ab initio reference data.

Cell surface glycopeptides from human intestinal epithelial cell lines derived from normal colon and colon adenocarcinomas

International Nuclear Information System (INIS)

Youakim, A.; Herscovics, A.

1985-01-01

The cell surface glycopeptides from an epithelial cell line (CCL 239) derived from normal human colon were compared with those from three cell lines (HCT-8R, HCT-15, and CaCo-2) derived independently from human colonic adenocarcinomas. Cells were incubated with D-[2- 3 H]mannose or L-[5,6- 3 H]fucose for 24 h and treated with trypsin to release cell surface components which were then digested exhaustively with Pronase and fractionated on Bio-Gel P-6 before and after treatment with endo-beta-N-acetylglucosaminidase H. The most noticeable difference between the labeled glycopeptides from the tumor and CCL 239 cells was the presence in the former of an endo-beta-N-acetylglucosaminidase H-resistant high molecular weight glycopeptide fraction which was eluted in the void volume of Bio-Gel P-6. This fraction was obtained with both labeled mannose and fucose as precursors. However, acid hydrolysis of this fraction obtained after incubation with [2- 3 H]mannose revealed that as much as 60-90% of the radioactivity was recovered as fucose. Analysis of the total glycopeptides (cell surface and cell pellet) obtained after incubation with [2- 3 H]mannose showed that from 40-45% of the radioactivity in the tumor cells and less than 10% of the radioactivity in the CCL 239 cells was recovered as fucose. After incubation of the HCT-8R cells with D-[1,6- 3 H]glucosamine and L-[1- 14 C]fucose, strong acid hydrolysis of the labeled glycopeptide fraction excluded from Bio-Gel P-6 produced 3 H-labeled N-acetylglucosamine and N-acetylgalactosamine

Experiments with parallel algorithms for combinatorial problems

NARCIS (Netherlands)

G.A.P. Kindervater (Gerard); H.W.J.M. Trienekens

1985-01-01

textabstractIn the last decade many models for parallel computation have been proposed and many parallel algorithms have been developed. However, few of these models have been realized and most of these algorithms are supposed to run on idealized, unrealistic parallel machines. The parallel machines

Thermal dynamics of silver clusters grown on rippled silica surfaces

Energy Technology Data Exchange (ETDEWEB)

Bhatnagar, Mukul, E-mail: mkbh10@gmail.com [FCIPT, Institute for Plasma Research, Gandhinagar, Gujarat (India); Nirma University, Ahmedabad, Gujarat (India); Ranjan, Mukesh [FCIPT, Institute for Plasma Research, Gandhinagar, Gujarat (India); Nirma University, Ahmedabad, Gujarat (India); Jolley, Kenny; Lloyd, Adam; Smith, Roger [Dept. of Mathematical Sciences, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Mukherjee, Subroto [FCIPT, Institute for Plasma Research, Gandhinagar, Gujarat (India); Nirma University, Ahmedabad, Gujarat (India)

2017-02-15

Highlights: • Low energy oblique angle ion bombardment forms ripple pattern on silicon surface. • The ripple patterns have wavelengths between 20 and 45 nm and correspondingly low height. • Silver nanoparticles have been deposited at an angle of 70° on patterned silicon templates. • The as-deposited np are annealed in vacuo at temperature of 573 K for a time duration of 1 h. • MD simulation is used to model the process and compare the results to the experiment. • Results show that silver clusters grow preferentially along parallel to the rippled surface. • Mobility of silver atoms depends on the site to which they are bonded on this amorphous surface. • MD simulations show contour ordered coalescence which is dependent on ripple periodicity. - Abstract: Silver nanoparticles have been deposited on silicon rippled patterned templates at an angle of incidence of 70° to the surface normal. The templates are produced by oblique incidence argon ion bombardment and as the fluence increases, the periods and heights of the structures increase. Structures with periods of 20 nm, 35 nm and 45 nm have been produced. Moderate temperature vacuum annealing shows the phenomenon of cluster coalescence following the contour of the more exposed faces of the ripple for the case of 35 nm and 45 nm but not at 20 nm where the silver aggregates into larger randomly distributed clusters. In order to understand this effect, the morphological changes of silver nanoparticles deposited on an asymmetric rippled silica surface are investigated through the use of molecular dynamics simulations for different deposition angles of incidence between 0° and 70° and annealing temperatures between 500 K and 900 K. Near to normal incidence, clusters are observed to migrate over the entire surface but for deposition at 70°, a similar patterning is observed as in the experiment. The random distribution of clusters for the periodicity ≈ of 20 nm is linked to the geometry of the silica

Parallel reservoir simulator computations

International Nuclear Information System (INIS)

Hemanth-Kumar, K.; Young, L.C.

1995-01-01

The adaptation of a reservoir simulator for parallel computations is described. The simulator was originally designed for vector processors. It performs approximately 99% of its calculations in vector/parallel mode and relative to scalar calculations it achieves speedups of 65 and 81 for black oil and EOS simulations, respectively on the CRAY C-90

The STAPL Parallel Graph Library

KAUST Repository

Harshvardhan,

2013-01-01

This paper describes the stapl Parallel Graph Library, a high-level framework that abstracts the user from data-distribution and parallelism details and allows them to concentrate on parallel graph algorithm development. It includes a customizable distributed graph container and a collection of commonly used parallel graph algorithms. The library introduces pGraph pViews that separate algorithm design from the container implementation. It supports three graph processing algorithmic paradigms, level-synchronous, asynchronous and coarse-grained, and provides common graph algorithms based on them. Experimental results demonstrate improved scalability in performance and data size over existing graph libraries on more than 16,000 cores and on internet-scale graphs containing over 16 billion vertices and 250 billion edges. © Springer-Verlag Berlin Heidelberg 2013.

The parallel volume at large distances

DEFF Research Database (Denmark)

Kampf, Jürgen

In this paper we examine the asymptotic behavior of the parallel volume of planar non-convex bodies as the distance tends to infinity. We show that the difference between the parallel volume of the convex hull of a body and the parallel volume of the body itself tends to . This yields a new proof...... for the fact that a planar body can only have polynomial parallel volume, if it is convex. Extensions to Minkowski spaces and random sets are also discussed....

The parallel volume at large distances

DEFF Research Database (Denmark)

Kampf, Jürgen

In this paper we examine the asymptotic behavior of the parallel volume of planar non-convex bodies as the distance tends to infinity. We show that the difference between the parallel volume of the convex hull of a body and the parallel volume of the body itself tends to 0. This yields a new proof...... for the fact that a planar body can only have polynomial parallel volume, if it is convex. Extensions to Minkowski spaces and random sets are also discussed....

Expressing Parallelism with ROOT

Energy Technology Data Exchange (ETDEWEB)

Piparo, D. [CERN; Tejedor, E. [CERN; Guiraud, E. [CERN; Ganis, G. [CERN; Mato, P. [CERN; Moneta, L. [CERN; Valls Pla, X. [CERN; Canal, P. [Fermilab

2017-11-22

The need for processing the ever-increasing amount of data generated by the LHC experiments in a more efficient way has motivated ROOT to further develop its support for parallelism. Such support is being tackled both for shared-memory and distributed-memory environments. The incarnations of the aforementioned parallelism are multi-threading, multi-processing and cluster-wide executions. In the area of multi-threading, we discuss the new implicit parallelism and related interfaces, as well as the new building blocks to safely operate with ROOT objects in a multi-threaded environment. Regarding multi-processing, we review the new MultiProc framework, comparing it with similar tools (e.g. multiprocessing module in Python). Finally, as an alternative to PROOF for cluster-wide executions, we introduce the efforts on integrating ROOT with state-of-the-art distributed data processing technologies like Spark, both in terms of programming model and runtime design (with EOS as one of the main components). For all the levels of parallelism, we discuss, based on real-life examples and measurements, how our proposals can increase the productivity of scientists.

Expressing Parallelism with ROOT

Science.gov (United States)

Piparo, D.; Tejedor, E.; Guiraud, E.; Ganis, G.; Mato, P.; Moneta, L.; Valls Pla, X.; Canal, P.

2017-10-01

The need for processing the ever-increasing amount of data generated by the LHC experiments in a more efficient way has motivated ROOT to further develop its support for parallelism. Such support is being tackled both for shared-memory and distributed-memory environments. The incarnations of the aforementioned parallelism are multi-threading, multi-processing and cluster-wide executions. In the area of multi-threading, we discuss the new implicit parallelism and related interfaces, as well as the new building blocks to safely operate with ROOT objects in a multi-threaded environment. Regarding multi-processing, we review the new MultiProc framework, comparing it with similar tools (e.g. multiprocessing module in Python). Finally, as an alternative to PROOF for cluster-wide executions, we introduce the efforts on integrating ROOT with state-of-the-art distributed data processing technologies like Spark, both in terms of programming model and runtime design (with EOS as one of the main components). For all the levels of parallelism, we discuss, based on real-life examples and measurements, how our proposals can increase the productivity of scientists.

Parallel hierarchical radiosity rendering

Energy Technology Data Exchange (ETDEWEB)

Carter, Michael [Iowa State Univ., Ames, IA (United States)

1993-07-01

In this dissertation, the step-by-step development of a scalable parallel hierarchical radiosity renderer is documented. First, a new look is taken at the traditional radiosity equation, and a new form is presented in which the matrix of linear system coefficients is transformed into a symmetric matrix, thereby simplifying the problem and enabling a new solution technique to be applied. Next, the state-of-the-art hierarchical radiosity methods are examined for their suitability to parallel implementation, and scalability. Significant enhancements are also discovered which both improve their theoretical foundations and improve the images they generate. The resultant hierarchical radiosity algorithm is then examined for sources of parallelism, and for an architectural mapping. Several architectural mappings are discussed. A few key algorithmic changes are suggested during the process of making the algorithm parallel. Next, the performance, efficiency, and scalability of the algorithm are analyzed. The dissertation closes with a discussion of several ideas which have the potential to further enhance the hierarchical radiosity method, or provide an entirely new forum for the application of hierarchical methods.

DEVELOPMENT AND USE OF A PARALLEL-PLATE FLOW CHAMBER FOR STUDYING CELLULAR ADHESION TO SOLID-SURFACES

NARCIS (Netherlands)

VANKOOTEN, TG; SCHAKENRAAD, JM; VANDERMEI, HC; BUSSCHER, HJ

A parallel-plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the

Shared Variable Oriented Parallel Precompiler for SPMD Model

Institute of Scientific and Technical Information of China (English)

无

1995-01-01

For the moment,commercial parallel computer systems with distributed memory architecture are usually provided with parallel FORTRAN or parallel C compliers,which are just traditional sequential FORTRAN or C compilers expanded with communication statements.Programmers suffer from writing parallel programs with communication statements. The Shared Variable Oriented Parallel Precompiler (SVOPP) proposed in this paper can automatically generate appropriate communication statements based on shared variables for SPMD(Single Program Multiple Data) computation model and greatly ease the parallel programming with high communication efficiency.The core function of parallel C precompiler has been successfully verified on a transputer-based parallel computer.Its prominent performance shows that SVOPP is probably a break-through in parallel programming technique.

On rationally supported surfaces

DEFF Research Database (Denmark)

Gravesen, Jens; Juttler, B.; Sir, Z.

2008-01-01

We analyze the class of surfaces which are equipped with rational support functions. Any rational support function can be decomposed into a symmetric (even) and an antisymmetric (odd) part. We analyze certain geometric properties of surfaces with odd and even rational support functions....... In particular it is shown that odd rational support functions correspond to those rational surfaces which can be equipped with a linear field of normal vectors, which were discussed by Sampoli et al. (Sampoli, M.L., Peternell, M., Juttler, B., 2006. Rational surfaces with linear normals and their convolutions...... with rational surfaces. Comput. Aided Geom. Design 23, 179-192). As shown recently, this class of surfaces includes non-developable quadratic triangular Bezier surface patches (Lavicka, M., Bastl, B., 2007. Rational hypersurfaces with rational convolutions. Comput. Aided Geom. Design 24, 410426; Peternell, M...

Evaluating parallel optimization on transputers

Directory of Open Access Journals (Sweden)

A.G. Chalmers

2003-12-01

Full Text Available The faster processing power of modern computers and the development of efficient algorithms have made it possible for operations researchers to tackle a much wider range of problems than ever before. Further improvements in processing speed can be achieved utilising relatively inexpensive transputers to process components of an algorithm in parallel. The Davidon-Fletcher-Powell method is one of the most successful and widely used optimisation algorithms for unconstrained problems. This paper examines the algorithm and identifies the components that can be processed in parallel. The results of some experiments with these components are presented which indicates under what conditions parallel processing with an inexpensive configuration is likely to be faster than the traditional sequential implementations. The performance of the whole algorithm with its parallel components is then compared with the original sequential algorithm. The implementation serves to illustrate the practicalities of speeding up typical OR algorithms in terms of difficulty, effort and cost. The results give an indication of the savings in time a given parallel implementation can be expected to yield.

Programming massively parallel processors a hands-on approach

CERN Document Server

Kirk, David B

2010-01-01

Programming Massively Parallel Processors discusses basic concepts about parallel programming and GPU architecture. ""Massively parallel"" refers to the use of a large number of processors to perform a set of computations in a coordinated parallel way. The book details various techniques for constructing parallel programs. It also discusses the development process, performance level, floating-point format, parallel patterns, and dynamic parallelism. The book serves as a teaching guide where parallel programming is the main topic of the course. It builds on the basics of C programming for CUDA, a parallel programming environment that is supported on NVI- DIA GPUs. Composed of 12 chapters, the book begins with basic information about the GPU as a parallel computer source. It also explains the main concepts of CUDA, data parallelism, and the importance of memory access efficiency using CUDA. The target audience of the book is graduate and undergraduate students from all science and engineering disciplines who ...

Parallel computing simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G.S.

2001-01-01

This paper presents the application of parallel computing techniques to large-scale modeling of fluid flow in the unsaturated zone (UZ) at Yucca Mountain, Nevada. In this study, parallel computing techniques, as implemented into the TOUGH2 code, are applied in large-scale numerical simulations on a distributed-memory parallel computer. The modeling study has been conducted using an over-one-million-cell three-dimensional numerical model, which incorporates a wide variety of field data for the highly heterogeneous fractured formation at Yucca Mountain. The objective of this study is to analyze the impact of various surface infiltration scenarios (under current and possible future climates) on flow through the UZ system, using various hydrogeological conceptual models with refined grids. The results indicate that the one-million-cell models produce better resolution results and reveal some flow patterns that cannot be obtained using coarse-grid modeling models

Precaval retropancreatic space: Normal anatomy

Energy Technology Data Exchange (ETDEWEB)

Lee, Yeon Hee; Kim, Ki Whang; Kim, Myung Jin; Yoo, Hyung Sik; Lee, Jong Tae [Yonsei University College of Medicine, Seoul (Korea, Republic of)

1992-07-15

The authors defined precaval retropancreatic space as the space between pancreatic head with portal vein and IVC and analyzed the CT findings of this space to know the normal structures and size in this space. We evaluated 100 cases of normal abdominal CT scan to find out normal anatomic structures of precaval retropancreatic space retrospectively. We also measured the distance between these structures and calculated the minimum, maximum and mean values. At the splenoportal confluence level, normal structures between portal vein and IVC were vessel (21%), lymph node (19%), and caudate lobe of liver (2%) in order of frequency. The maximum AP diameter of portocaval lymph node was 4 mm. Common bile duct (CBD) was seen in 44% and the diameter was mean 3 mm and maximum 11 mm. CBD was located in extrapancreatic (75%) and lateral (60.6%) to pancreatic head. At IVC-left renal vein level, the maximum distance between CBD and IVC was 5 mm and the structure between posterior pancreatic surface and IVC was only fat tissue. Knowledge of these normal structures and measurement will be helpful in differentiating pancreatic mass with retropancreatic mass such as lymphadenopathy.

Exploiting Symmetry on Parallel Architectures.

Science.gov (United States)

Stiller, Lewis Benjamin

1995-01-01

This thesis describes techniques for the design of parallel programs that solve well-structured problems with inherent symmetry. Part I demonstrates the reduction of such problems to generalized matrix multiplication by a group-equivariant matrix. Fast techniques for this multiplication are described, including factorization, orbit decomposition, and Fourier transforms over finite groups. Our algorithms entail interaction between two symmetry groups: one arising at the software level from the problem's symmetry and the other arising at the hardware level from the processors' communication network. Part II illustrates the applicability of our symmetry -exploitation techniques by presenting a series of case studies of the design and implementation of parallel programs. First, a parallel program that solves chess endgames by factorization of an associated dihedral group-equivariant matrix is described. This code runs faster than previous serial programs, and discovered it a number of results. Second, parallel algorithms for Fourier transforms for finite groups are developed, and preliminary parallel implementations for group transforms of dihedral and of symmetric groups are described. Applications in learning, vision, pattern recognition, and statistics are proposed. Third, parallel implementations solving several computational science problems are described, including the direct n-body problem, convolutions arising from molecular biology, and some communication primitives such as broadcast and reduce. Some of our implementations ran orders of magnitude faster than previous techniques, and were used in the investigation of various physical phenomena.

Interference effects on guided Cherenkov emission in silicon from perpendicular, oblique, and parallel boundaries

Science.gov (United States)

Couillard, M.; Yurtsever, A.; Muller, D. A.

2010-05-01

Waveguide electromagnetic modes excited by swift electrons traversing Si slabs at normal and oblique incidence are analyzed using monochromated electron energy-loss spectroscopy and interpreted using a local dielectric theory that includes relativistic effects. At normal incidence, sharp spectral features in the visible/near-infrared optical domain are directly assigned to p -polarized modes. When the specimen is tilted, s -polarized modes, which are completely absent at normal incidence, become visible in the loss spectra. In the tilted configuration, the dispersion of p -polarized modes is also modified. For tilt angles higher than ˜50° , Cherenkov radiation, the phenomenon responsible for the excitation of waveguide modes, is expected to partially escape the silicon slab and the influence of this effect on experimental measurements is discussed. Finally, we find evidence for an interference effect at parallel Si/SiO2 interfaces, as well as a delocalized excitation of guided Cherenkov modes.

Interference effects on guided Cherenkov emission in silicon from perpendicular, oblique, and parallel boundaries

International Nuclear Information System (INIS)

Couillard, M.; Yurtsever, A.; Muller, D. A.

2010-01-01

Waveguide electromagnetic modes excited by swift electrons traversing Si slabs at normal and oblique incidence are analyzed using monochromated electron energy-loss spectroscopy and interpreted using a local dielectric theory that includes relativistic effects. At normal incidence, sharp spectral features in the visible/near-infrared optical domain are directly assigned to p-polarized modes. When the specimen is tilted, s-polarized modes, which are completely absent at normal incidence, become visible in the loss spectra. In the tilted configuration, the dispersion of p-polarized modes is also modified. For tilt angles higher than ∼50 deg. Cherenkov radiation, the phenomenon responsible for the excitation of waveguide modes, is expected to partially escape the silicon slab and the influence of this effect on experimental measurements is discussed. Finally, we find evidence for an interference effect at parallel Si/SiO 2 interfaces, as well as a delocalized excitation of guided Cherenkov modes.

Advanced parallel processing with supercomputer architectures

International Nuclear Information System (INIS)

Hwang, K.

1987-01-01

This paper investigates advanced parallel processing techniques and innovative hardware/software architectures that can be applied to boost the performance of supercomputers. Critical issues on architectural choices, parallel languages, compiling techniques, resource management, concurrency control, programming environment, parallel algorithms, and performance enhancement methods are examined and the best answers are presented. The authors cover advanced processing techniques suitable for supercomputers, high-end mainframes, minisupers, and array processors. The coverage emphasizes vectorization, multitasking, multiprocessing, and distributed computing. In order to achieve these operation modes, parallel languages, smart compilers, synchronization mechanisms, load balancing methods, mapping parallel algorithms, operating system functions, application library, and multidiscipline interactions are investigated to ensure high performance. At the end, they assess the potentials of optical and neural technologies for developing future supercomputers

Endpoint-based parallel data processing with non-blocking collective instructions in a parallel active messaging interface of a parallel computer

Science.gov (United States)

Archer, Charles J; Blocksome, Michael A; Cernohous, Bob R; Ratterman, Joseph D; Smith, Brian E

2014-11-11

Endpoint-based parallel data processing with non-blocking collective instructions in a PAMI of a parallel computer is disclosed. The PAMI is composed of data communications endpoints, each including a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task. The compute nodes are coupled for data communications through the PAMI. The parallel application establishes a data communications geometry specifying a set of endpoints that are used in collective operations of the PAMI by associating with the geometry a list of collective algorithms valid for use with the endpoints of the geometry; registering in each endpoint in the geometry a dispatch callback function for a collective operation; and executing without blocking, through a single one of the endpoints in the geometry, an instruction for the collective operation.

A model for generating Surface EMG signal of m. Tibialis Anterior.

Science.gov (United States)

Siddiqi, Ariba; Kumar, Dinesh; Arjunan, Sridhar P

2014-01-01

A model that simulates surface electromyogram (sEMG) signal of m. Tibialis Anterior has been developed and tested. This has a firing rate equation that is based on experimental findings. It also has a recruitment threshold that is based on observed statistical distribution. Importantly, it has considered both, slow and fast type which has been distinguished based on their conduction velocity. This model has assumed that the deeper unipennate half of the muscle does not contribute significantly to the potential induced on the surface of the muscle and has approximated the muscle to have parallel structure. The model was validated by comparing the simulated and the experimental sEMG signal recordings. Experiments were conducted on eight subjects who performed isometric dorsiflexion at 10, 20, 30, 50, 75, and 100% maximal voluntary contraction. Normalized root mean square and median frequency of the experimental and simulated EMG signal were computed and the slopes of the linearity with the force were statistically analyzed. The gradients were found to be similar (p>0.05) for both experimental and simulated sEMG signal, validating the proposed model.

SOFTWARE FOR DESIGNING PARALLEL APPLICATIONS

Directory of Open Access Journals (Sweden)

M. K. Bouza

2017-01-01

Full Text Available The object of research is the tools to support the development of parallel programs in C/C ++. The methods and software which automates the process of designing parallel applications are proposed.

An Introduction to Parallel Computation R

Indian Academy of Sciences (India)

How are they programmed? This article provides an introduction. A parallel computer is a network of processors built for ... and have been used to solve problems much faster than a single ... in parallel computer design is to select an organization which ..... The most ambitious approach to parallel computing is to develop.

Building a parallel file system simulator

International Nuclear Information System (INIS)

Molina-Estolano, E; Maltzahn, C; Brandt, S A; Bent, J

2009-01-01

Parallel file systems are gaining in popularity in high-end computing centers as well as commercial data centers. High-end computing systems are expected to scale exponentially and to pose new challenges to their storage scalability in terms of cost and power. To address these challenges scientists and file system designers will need a thorough understanding of the design space of parallel file systems. Yet there exist few systematic studies of parallel file system behavior at petabyte- and exabyte scale. An important reason is the significant cost of getting access to large-scale hardware to test parallel file systems. To contribute to this understanding we are building a parallel file system simulator that can simulate parallel file systems at very large scale. Our goal is to simulate petabyte-scale parallel file systems on a small cluster or even a single machine in reasonable time and fidelity. With this simulator, file system experts will be able to tune existing file systems for specific workloads, scientists and file system deployment engineers will be able to better communicate workload requirements, file system designers and researchers will be able to try out design alternatives and innovations at scale, and instructors will be able to study very large-scale parallel file system behavior in the class room. In this paper we describe our approach and provide preliminary results that are encouraging both in terms of fidelity and simulation scalability.

Professional Parallel Programming with C# Master Parallel Extensions with NET 4

CERN Document Server

Hillar, Gastón

2010-01-01

Expert guidance for those programming today's dual-core processors PCs As PC processors explode from one or two to now eight processors, there is an urgent need for programmers to master concurrent programming. This book dives deep into the latest technologies available to programmers for creating professional parallel applications using C#, .NET 4, and Visual Studio 2010. The book covers task-based programming, coordination data structures, PLINQ, thread pools, asynchronous programming model, and more. It also teaches other parallel programming techniques, such as SIMD and vectorization.Teach

Parallelization for first principles electronic state calculation program

International Nuclear Information System (INIS)

Watanabe, Hiroshi; Oguchi, Tamio.

1997-03-01

In this report we study the parallelization for First principles electronic state calculation program. The target machines are NEC SX-4 for shared memory type parallelization and FUJITSU VPP300 for distributed memory type parallelization. The features of each parallel machine are surveyed, and the parallelization methods suitable for each are proposed. It is shown that 1.60 times acceleration is achieved with 2 CPU parallelization by SX-4 and 4.97 times acceleration is achieved with 12 PE parallelization by VPP 300. (author)

Parallel computation

International Nuclear Information System (INIS)

Jejcic, A.; Maillard, J.; Maurel, G.; Silva, J.; Wolff-Bacha, F.

1997-01-01

The work in the field of parallel processing has developed as research activities using several numerical Monte Carlo simulations related to basic or applied current problems of nuclear and particle physics. For the applications utilizing the GEANT code development or improvement works were done on parts simulating low energy physical phenomena like radiation, transport and interaction. The problem of actinide burning by means of accelerators was approached using a simulation with the GEANT code. A program of neutron tracking in the range of low energies up to the thermal region has been developed. It is coupled to the GEANT code and permits in a single pass the simulation of a hybrid reactor core receiving a proton burst. Other works in this field refers to simulations for nuclear medicine applications like, for instance, development of biological probes, evaluation and characterization of the gamma cameras (collimators, crystal thickness) as well as the method for dosimetric calculations. Particularly, these calculations are suited for a geometrical parallelization approach especially adapted to parallel machines of the TN310 type. Other works mentioned in the same field refer to simulation of the electron channelling in crystals and simulation of the beam-beam interaction effect in colliders. The GEANT code was also used to simulate the operation of germanium detectors designed for natural and artificial radioactivity monitoring of environment

Neoclassical parallel flow calculation in the presence of external parallel momentum sources in Heliotron J

Energy Technology Data Exchange (ETDEWEB)

Nishioka, K.; Nakamura, Y. [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Nishimura, S. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Lee, H. Y. [Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kobayashi, S.; Mizuuchi, T.; Nagasaki, K.; Okada, H.; Minami, T.; Kado, S.; Yamamoto, S.; Ohshima, S.; Konoshima, S.; Sano, F. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

2016-03-15

A moment approach to calculate neoclassical transport in non-axisymmetric torus plasmas composed of multiple ion species is extended to include the external parallel momentum sources due to unbalanced tangential neutral beam injections (NBIs). The momentum sources that are included in the parallel momentum balance are calculated from the collision operators of background particles with fast ions. This method is applied for the clarification of the physical mechanism of the neoclassical parallel ion flows and the multi-ion species effect on them in Heliotron J NBI plasmas. It is found that parallel ion flow can be determined by the balance between the parallel viscosity and the external momentum source in the region where the external source is much larger than the thermodynamic force driven source in the collisional plasmas. This is because the friction between C{sup 6+} and D{sup +} prevents a large difference between C{sup 6+} and D{sup +} flow velocities in such plasmas. The C{sup 6+} flow velocities, which are measured by the charge exchange recombination spectroscopy system, are numerically evaluated with this method. It is shown that the experimentally measured C{sup 6+} impurity flow velocities do not contradict clearly with the neoclassical estimations, and the dependence of parallel flow velocities on the magnetic field ripples is consistent in both results.

Structural Properties of G,T-Parallel Duplexes

Directory of Open Access Journals (Sweden)

Anna Aviñó

2010-01-01

Full Text Available The structure of G,T-parallel-stranded duplexes of DNA carrying similar amounts of adenine and guanine residues is studied by means of molecular dynamics (MD simulations and UV- and CD spectroscopies. In addition the impact of the substitution of adenine by 8-aminoadenine and guanine by 8-aminoguanine is analyzed. The presence of 8-aminoadenine and 8-aminoguanine stabilizes the parallel duplex structure. Binding of these oligonucleotides to their target polypyrimidine sequences to form the corresponding G,T-parallel triplex was not observed. Instead, when unmodified parallel-stranded duplexes were mixed with their polypyrimidine target, an interstrand Watson-Crick duplex was formed. As predicted by theoretical calculations parallel-stranded duplexes carrying 8-aminopurines did not bind to their target. The preference for the parallel-duplex over the Watson-Crick antiparallel duplex is attributed to the strong stabilization of the parallel duplex produced by the 8-aminopurines. Theoretical studies show that the isomorphism of the triads is crucial for the stability of the parallel triplex.

High-speed parallel solution of the neutron diffusion equation with the hierarchical domain decomposition boundary element method incorporating parallel communications

International Nuclear Information System (INIS)

Tsuji, Masashi; Chiba, Gou

2000-01-01

A hierarchical domain decomposition boundary element method (HDD-BEM) for solving the multiregion neutron diffusion equation (NDE) has been fully parallelized, both for numerical computations and for data communications, to accomplish a high parallel efficiency on distributed memory message passing parallel computers. Data exchanges between node processors that are repeated during iteration processes of HDD-BEM are implemented, without any intervention of the host processor that was used to supervise parallel processing in the conventional parallelized HDD-BEM (P-HDD-BEM). Thus, the parallel processing can be executed with only cooperative operations of node processors. The communication overhead was even the dominant time consuming part in the conventional P-HDD-BEM, and the parallelization efficiency decreased steeply with the increase of the number of processors. With the parallel data communication, the efficiency is affected only by the number of boundary elements assigned to decomposed subregions, and the communication overhead can be drastically reduced. This feature can be particularly advantageous in the analysis of three-dimensional problems where a large number of processors are required. The proposed P-HDD-BEM offers a promising solution to the deterioration problem of parallel efficiency and opens a new path to parallel computations of NDEs on distributed memory message passing parallel computers. (author)

Parallel education: what is it?

OpenAIRE

Amos, Michelle Peta

2017-01-01

In the history of education it has long been discussed that single-sex and coeducation are the two models of education present in schools. With the introduction of parallel schools over the last 15 years, there has been very little research into this 'new model'. Many people do not understand what it means for a school to be parallel or they confuse a parallel model with co-education, due to the presence of both boys and girls within the one institution. Therefore, the main obj...

Parallel computing of physical maps--a comparative study in SIMD and MIMD parallelism.

Science.gov (United States)

Bhandarkar, S M; Chirravuri, S; Arnold, J

1996-01-01

Ordering clones from a genomic library into physical maps of whole chromosomes presents a central computational problem in genetics. Chromosome reconstruction via clone ordering is usually isomorphic to the NP-complete Optimal Linear Arrangement problem. Parallel SIMD and MIMD algorithms for simulated annealing based on Markov chain distribution are proposed and applied to the problem of chromosome reconstruction via clone ordering. Perturbation methods and problem-specific annealing heuristics are proposed and described. The SIMD algorithms are implemented on a 2048 processor MasPar MP-2 system which is an SIMD 2-D toroidal mesh architecture whereas the MIMD algorithms are implemented on an 8 processor Intel iPSC/860 which is an MIMD hypercube architecture. A comparative analysis of the various SIMD and MIMD algorithms is presented in which the convergence, speedup, and scalability characteristics of the various algorithms are analyzed and discussed. On a fine-grained, massively parallel SIMD architecture with a low synchronization overhead such as the MasPar MP-2, a parallel simulated annealing algorithm based on multiple periodically interacting searches performs the best. For a coarse-grained MIMD architecture with high synchronization overhead such as the Intel iPSC/860, a parallel simulated annealing algorithm based on multiple independent searches yields the best results. In either case, distribution of clonal data across multiple processors is shown to exacerbate the tendency of the parallel simulated annealing algorithm to get trapped in a local optimum.

On synchronous parallel computations with independent probabilistic choice

International Nuclear Information System (INIS)

Reif, J.H.

1984-01-01

This paper introduces probabilistic choice to synchronous parallel machine models; in particular parallel RAMs. The power of probabilistic choice in parallel computations is illustrate by parallelizing some known probabilistic sequential algorithms. The authors characterize the computational complexity of time, space, and processor bounded probabilistic parallel RAMs in terms of the computational complexity of probabilistic sequential RAMs. They show that parallelism uniformly speeds up time bounded probabilistic sequential RAM computations by nearly a quadratic factor. They also show that probabilistic choice can be eliminated from parallel computations by introducing nonuniformity

Automatic Parallelization Tool: Classification of Program Code for Parallel Computing

Directory of Open Access Journals (Sweden)

Mustafa Basthikodi

2016-04-01

Full Text Available Performance growth of single-core processors has come to a halt in the past decade, but was re-enabled by the introduction of parallelism in processors. Multicore frameworks along with Graphical Processing Units empowered to enhance parallelism broadly. Couples of compilers are updated to developing challenges forsynchronization and threading issues. Appropriate program and algorithm classifications will have advantage to a great extent to the group of software engineers to get opportunities for effective parallelization. In present work we investigated current species for classification of algorithms, in that related work on classification is discussed along with the comparison of issues that challenges the classification. The set of algorithms are chosen which matches the structure with different issues and perform given task. We have tested these algorithms utilizing existing automatic species extraction toolsalong with Bones compiler. We have added functionalities to existing tool, providing a more detailed characterization. The contributions of our work include support for pointer arithmetic, conditional and incremental statements, user defined types, constants and mathematical functions. With this, we can retain significant data which is not captured by original speciesof algorithms. We executed new theories into the device, empowering automatic characterization of program code.

What Are Normal Metal Ion Levels After Total Hip Arthroplasty? A Serologic Analysis of Four Bearing Surfaces.

Science.gov (United States)

Barlow, Brian T; Ortiz, Philippe A; Boles, John W; Lee, Yuo-Yu; Padgett, Douglas E; Westrich, Geoffrey H

2017-05-01

The recent experiences with adverse local tissue reactions have highlighted the need to establish what are normal serum levels of cobalt (Co), chromium (Cr), and titanium (Ti) after hip arthroplasty. Serum Co, Cr, and Ti levels were measured in 80 nonconsecutive patients with well-functioning unilateral total hip arthroplasty and compared among 4 bearing surfaces: ceramic-on-ceramic (CoC); ceramic-on-polyethylene (CoP); metal-on-polyethylene (MoP), and dual mobility (DM). The preoperative and most recent University of California, Los Angeles (UCLA) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were compared among the different bearing surfaces. No significant difference was found among serum Co and Cr levels between the 4 bearing surface groups (P = .0609 and P = .1577). Secondary analysis comparing metal and ceramic femoral heads demonstrated that the metal group (MoP, modular dual mobility (Stryker Orthopedics, Mahwah, NJ) [metal]) had significant higher serum Co levels compared with the ceramic group (CoC, CoP, MDM [ceramic]) (1.05 mg/L ± 1.25 vs 0.59 mg/L ± 0.24; P = .0411). Spearman coefficient identified no correlation between metal ion levels and patient-reported outcome scores. No serum metal ion level differences were found among well-functioning total hip arthroplasty with modern bearing couples. Significantly higher serum Co levels were seen when comparing metal vs ceramic femoral heads in this study and warrants further investigation. Metal ion levels did not correlate with patient-reported outcome measures. Copyright © 2016 Elsevier Inc. All rights reserved.

Detection of tumor-like inclusions embedded within human liver tissue using a short-pulsed near-infrared laser beam: Parallel simulations with radiative transfer equation

International Nuclear Information System (INIS)

Asllanaj, Fatmir; Addoum, Ahmad; Contassot-Vivier, Sylvain

2015-01-01

An efficient solution to detect tumor-like inclusions embedded within a human liver tissue model is presented, using illumination by a short-pulsed laser beam. Light propagation was accurately solved using the time-dependent radiative transfer equation, with multithreaded parallel computing. A modified finite volume method based on unstructured grids and the fourth-order Runge–Kutta approach was employed to solve the equation in the (2-D/3-D) spatial and time domains. The normalization technique applied to the Henyey–Greenstein phase function was adopted to ensure numerical stability for values of the anisotropy factor that were close to unity. The presence of one or two circular/spherical inclusions was analyzed from the time and spatially resolved reflectance on the medium bounding surface. The results allowed a minimal size and a maximum distance for the detection of the inclusion to be highlighted. - Highlights: • We detect tumor-like inclusions embedded within a (2D/3D) human liver tissue model. • The technique is based on a short-pulsed near-infrared laser beam. • We solve the (2D/3D) time-dependent RTE, with multithreaded parallel computing. • The presence of one or two circular/spherical inclusions is analyzed. • The results allows a minimal size and a maximum distance for the detection

Resistor Combinations for Parallel Circuits.

Science.gov (United States)

McTernan, James P.

1978-01-01

To help simplify both teaching and learning of parallel circuits, a high school electricity/electronics teacher presents and illustrates the use of tables of values for parallel resistive circuits in which total resistances are whole numbers. (MF)

Coarse-grain parallel solution of few-group neutron diffusion equations

International Nuclear Information System (INIS)

Sarsour, H.N.; Turinsky, P.J.

1991-01-01

The authors present a parallel numerical algorithm for the solution of the finite difference representation of the few-group neutron diffusion equations. The targeted architectures are multiprocessor computers with shared memory like the Cray Y-MP and the IBM 3090/VF, where coarse granularity is important for minimizing overhead. Most of the work done in the past, which attempts to exploit concurrence, has concentrated on the inner iterations of the standard outer-inner iterative strategy. This produces very fine granularity. To coarsen granularity, the authors introduce parallelism at the nested outer-inner level. The problem's spatial domain was partitioned into contiguous subregions and assigned a processor to solve for each subregion independent of all other subregions, hence, processors; i.e., each subregion is treated as a reactor core with imposed boundary conditions. Since those boundary conditions on interior surfaces, referred to as internal boundary conditions (IBCs), are not known, a third iterative level, the recomposition iterations, is introduced to communicate results between subregions

A study on fungal flora of the normal eye surface in Iranian native cattle

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tohid nouri

2014-11-01

Full Text Available The microflora of the normal ocular surface is one of the sources supplying fungal agents for keratomycosis. This study was conducted to identify fungal isolates of the conjunctiva in clinically healthy Iranian native cattle in Urmia district. Swabs were taken from both eyes of cattle (n=45 and cultured onto Sabouraud dextrose agar with chloramphenicol and malt extract agar. Plates were incubated at 25°C and examined for 7 days. Data were analyzed for the effect of age and sex by fisher’s exact test. Thirteen cattle (28.89% were found to be positive for fungal growth. The isolated fungal genera were Aspergillus spp-7 cases (53.84%, Penicillium spp-6 cases (46.15%, Rhodotorula sp-1 case (7.69% and Candida sp-1 case (7.69%. Yeast genera represented 13.3% of all the isolates. Sex and age of cattle had no significant effect on prevalence of isolates. Incidence of fungal colonization of the eyes compared with similar studies was low which may reflect differences in season and technique of sampling. Unexpected high frequency of Aspergillus may be due to geographic differences.

Parallelization methods study of thermal-hydraulics codes

International Nuclear Information System (INIS)

Gaudart, Catherine

2000-01-01

The variety of parallelization methods and machines leads to a wide selection for programmers. In this study we suggest, in an industrial context, some solutions from the experience acquired through different parallelization methods. The study is about several scientific codes which simulate a large variety of thermal-hydraulics phenomena. A bibliography on parallelization methods and a first analysis of the codes showed the difficulty of our process on the whole applications to study. Therefore, it would be necessary to identify and extract a representative part of these applications and parallelization methods. The linear solver part of the codes forced itself. On this particular part several parallelization methods had been used. From these developments one could estimate the necessary work for a non initiate programmer to parallelize his application, and the impact of the development constraints. The different methods of parallelization tested are the numerical library PETSc, the parallelizer PAF, the language HPF, the formalism PEI and the communications library MPI and PYM. In order to test several methods on different applications and to follow the constraint of minimization of the modifications in codes, a tool called SPS (Server of Parallel Solvers) had be developed. We propose to describe the different constraints about the optimization of codes in an industrial context, to present the solutions given by the tool SPS, to show the development of the linear solver part with the tested parallelization methods and lastly to compare the results against the imposed criteria. (author) [fr

Simulation Exploration through Immersive Parallel Planes

Energy Technology Data Exchange (ETDEWEB)

Brunhart-Lupo, Nicholas J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bush, Brian W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gruchalla, Kenny M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Smith, Steve [Los Alamos Visualization Associates

2017-05-25

We present a visualization-driven simulation system that tightly couples systems dynamics simulations with an immersive virtual environment to allow analysts to rapidly develop and test hypotheses in a high-dimensional parameter space. To accomplish this, we generalize the two-dimensional parallel-coordinates statistical graphic as an immersive 'parallel-planes' visualization for multivariate time series emitted by simulations running in parallel with the visualization. In contrast to traditional parallel coordinate's mapping the multivariate dimensions onto coordinate axes represented by a series of parallel lines, we map pairs of the multivariate dimensions onto a series of parallel rectangles. As in the case of parallel coordinates, each individual observation in the dataset is mapped to a polyline whose vertices coincide with its coordinate values. Regions of the rectangles can be 'brushed' to highlight and select observations of interest: a 'slider' control allows the user to filter the observations by their time coordinate. In an immersive virtual environment, users interact with the parallel planes using a joystick that can select regions on the planes, manipulate selection, and filter time. The brushing and selection actions are used to both explore existing data as well as to launch additional simulations corresponding to the visually selected portions of the input parameter space. As soon as the new simulations complete, their resulting observations are displayed in the virtual environment. This tight feedback loop between simulation and immersive analytics accelerates users' realization of insights about the simulation and its output.

Workspace Analysis for Parallel Robot

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Ying Sun

2013-05-01

Full Text Available As a completely new-type of robot, the parallel robot possesses a lot of advantages that the serial robot does not, such as high rigidity, great load-carrying capacity, small error, high precision, small self-weight/load ratio, good dynamic behavior and easy control, hence its range is extended in using domain. In order to find workspace of parallel mechanism, the numerical boundary-searching algorithm based on the reverse solution of kinematics and limitation of link length has been introduced. This paper analyses position workspace, orientation workspace of parallel robot of the six degrees of freedom. The result shows: It is a main means to increase and decrease its workspace to change the length of branch of parallel mechanism; The radius of the movement platform has no effect on the size of workspace, but will change position of workspace.

Massively Parallel Finite Element Programming

KAUST Repository

Heister, Timo; Kronbichler, Martin; Bangerth, Wolfgang

2010-01-01

Today's large finite element simulations require parallel algorithms to scale on clusters with thousands or tens of thousands of processor cores. We present data structures and algorithms to take advantage of the power of high performance computers in generic finite element codes. Existing generic finite element libraries often restrict the parallelization to parallel linear algebra routines. This is a limiting factor when solving on more than a few hundreds of cores. We describe routines for distributed storage of all major components coupled with efficient, scalable algorithms. We give an overview of our effort to enable the modern and generic finite element library deal.II to take advantage of the power of large clusters. In particular, we describe the construction of a distributed mesh and develop algorithms to fully parallelize the finite element calculation. Numerical results demonstrate good scalability. © 2010 Springer-Verlag.

Massively Parallel Finite Element Programming

KAUST Repository

Heister, Timo

2010-01-01

Today\\'s large finite element simulations require parallel algorithms to scale on clusters with thousands or tens of thousands of processor cores. We present data structures and algorithms to take advantage of the power of high performance computers in generic finite element codes. Existing generic finite element libraries often restrict the parallelization to parallel linear algebra routines. This is a limiting factor when solving on more than a few hundreds of cores. We describe routines for distributed storage of all major components coupled with efficient, scalable algorithms. We give an overview of our effort to enable the modern and generic finite element library deal.II to take advantage of the power of large clusters. In particular, we describe the construction of a distributed mesh and develop algorithms to fully parallelize the finite element calculation. Numerical results demonstrate good scalability. © 2010 Springer-Verlag.

Collectively loading an application in a parallel computer

Science.gov (United States)

Aho, Michael E.; Attinella, John E.; Gooding, Thomas M.; Miller, Samuel J.; Mundy, Michael B.

2016-01-05

Collectively loading an application in a parallel computer, the parallel computer comprising a plurality of compute nodes, including: identifying, by a parallel computer control system, a subset of compute nodes in the parallel computer to execute a job; selecting, by the parallel computer control system, one of the subset of compute nodes in the parallel computer as a job leader compute node; retrieving, by the job leader compute node from computer memory, an application for executing the job; and broadcasting, by the job leader to the subset of compute nodes in the parallel computer, the application for executing the job.

Productive Parallel Programming: The PCN Approach

Directory of Open Access Journals (Sweden)

Ian Foster

1992-01-01

Full Text Available We describe the PCN programming system, focusing on those features designed to improve the productivity of scientists and engineers using parallel supercomputers. These features include a simple notation for the concise specification of concurrent algorithms, the ability to incorporate existing Fortran and C code into parallel applications, facilities for reusing parallel program components, a portable toolkit that allows applications to be developed on a workstation or small parallel computer and run unchanged on supercomputers, and integrated debugging and performance analysis tools. We survey representative scientific applications and identify problem classes for which PCN has proved particularly useful.

High-resolution brain SPECT imaging by combination of parallel and tilted detector heads.

Science.gov (United States)

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Morimoto, Yuichi; Kobashi, Keiji; Ueno, Yuichiro

2015-10-01

To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations. In the simulation study, the tilt angle of the detector heads relative to the axis was 45°. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The ordered-subsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison. The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The cold-rod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT. PT-SPECT provides improved image resolution at not only upper but also at

Parallel-In-Time For Moving Meshes

Energy Technology Data Exchange (ETDEWEB)

Falgout, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Manteuffel, T. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Southworth, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schroder, J. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-02-04

With steadily growing computational resources available, scientists must develop e ective ways to utilize the increased resources. High performance, highly parallel software has be- come a standard. However until recent years parallelism has focused primarily on the spatial domain. When solving a space-time partial di erential equation (PDE), this leads to a sequential bottleneck in the temporal dimension, particularly when taking a large number of time steps. The XBraid parallel-in-time library was developed as a practical way to add temporal parallelism to existing se- quential codes with only minor modi cations. In this work, a rezoning-type moving mesh is applied to a di usion problem and formulated in a parallel-in-time framework. Tests and scaling studies are run using XBraid and demonstrate excellent results for the simple model problem considered herein.

Integrated Task And Data Parallel Programming: Language Design

Science.gov (United States)

Grimshaw, Andrew S.; West, Emily A.

1998-01-01

his research investigates the combination of task and data parallel language constructs within a single programming language. There are an number of applications that exhibit properties which would be well served by such an integrated language. Examples include global climate models, aircraft design problems, and multidisciplinary design optimization problems. Our approach incorporates data parallel language constructs into an existing, object oriented, task parallel language. The language will support creation and manipulation of parallel classes and objects of both types (task parallel and data parallel). Ultimately, the language will allow data parallel and task parallel classes to be used either as building blocks or managers of parallel objects of either type, thus allowing the development of single and multi-paradigm parallel applications. 1995 Research Accomplishments In February I presented a paper at Frontiers '95 describing the design of the data parallel language subset. During the spring I wrote and defended my dissertation proposal. Since that time I have developed a runtime model for the language subset. I have begun implementing the model and hand-coding simple examples which demonstrate the language subset. I have identified an astrophysical fluid flow application which will validate the data parallel language subset. 1996 Research Agenda Milestones for the coming year include implementing a significant portion of the data parallel language subset over the Legion system. Using simple hand-coded methods, I plan to demonstrate (1) concurrent task and data parallel objects and (2) task parallel objects managing both task and data parallel objects. My next steps will focus on constructing a compiler and implementing the fluid flow application with the language. Concurrently, I will conduct a search for a real-world application exhibiting both task and data parallelism within the same program m. Additional 1995 Activities During the fall I collaborated

Performance of the Galley Parallel File System

Science.gov (United States)

Nieuwejaar, Nils; Kotz, David

1996-01-01

As the input/output (I/O) needs of parallel scientific applications increase, file systems for multiprocessors are being designed to provide applications with parallel access to multiple disks. Many parallel file systems present applications with a conventional Unix-like interface that allows the application to access multiple disks transparently. This interface conceals the parallism within the file system, which increases the ease of programmability, but makes it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. Furthermore, most current parallel file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic parallel workloads. Initial experiments, reported in this paper, indicate that Galley is capable of providing high-performance 1/O to applications the applications that rely on them. In Section 3 we describe that access data in patterns that have been observed to be common.

Reconstruction for Time-Domain In Vivo EPR 3D Multigradient Oximetric Imaging—A Parallel Processing Perspective

Directory of Open Access Journals (Sweden)

Christopher D. Dharmaraj

2009-01-01

Full Text Available Three-dimensional Oximetric Electron Paramagnetic Resonance Imaging using the Single Point Imaging modality generates unpaired spin density and oxygen images that can readily distinguish between normal and tumor tissues in small animals. It is also possible with fast imaging to track the changes in tissue oxygenation in response to the oxygen content in the breathing air. However, this involves dealing with gigabytes of data for each 3D oximetric imaging experiment involving digital band pass filtering and background noise subtraction, followed by 3D Fourier reconstruction. This process is rather slow in a conventional uniprocessor system. This paper presents a parallelization framework using OpenMP runtime support and parallel MATLAB to execute such computationally intensive programs. The Intel compiler is used to develop a parallel C++ code based on OpenMP. The code is executed on four Dual-Core AMD Opteron shared memory processors, to reduce the computational burden of the filtration task significantly. The results show that the parallel code for filtration has achieved a speed up factor of 46.66 as against the equivalent serial MATLAB code. In addition, a parallel MATLAB code has been developed to perform 3D Fourier reconstruction. Speedup factors of 4.57 and 4.25 have been achieved during the reconstruction process and oximetry computation, for a data set with 23×23×23 gradient steps. The execution time has been computed for both the serial and parallel implementations using different dimensions of the data and presented for comparison. The reported system has been designed to be easily accessible even from low-cost personal computers through local internet (NIHnet. The experimental results demonstrate that the parallel computing provides a source of high computational power to obtain biophysical parameters from 3D EPR oximetric imaging, almost in real-time.

Reconstruction for time-domain in vivo EPR 3D multigradient oximetric imaging--a parallel processing perspective.

Science.gov (United States)

Dharmaraj, Christopher D; Thadikonda, Kishan; Fletcher, Anthony R; Doan, Phuc N; Devasahayam, Nallathamby; Matsumoto, Shingo; Johnson, Calvin A; Cook, John A; Mitchell, James B; Subramanian, Sankaran; Krishna, Murali C

2009-01-01

Three-dimensional Oximetric Electron Paramagnetic Resonance Imaging using the Single Point Imaging modality generates unpaired spin density and oxygen images that can readily distinguish between normal and tumor tissues in small animals. It is also possible with fast imaging to track the changes in tissue oxygenation in response to the oxygen content in the breathing air. However, this involves dealing with gigabytes of data for each 3D oximetric imaging experiment involving digital band pass filtering and background noise subtraction, followed by 3D Fourier reconstruction. This process is rather slow in a conventional uniprocessor system. This paper presents a parallelization framework using OpenMP runtime support and parallel MATLAB to execute such computationally intensive programs. The Intel compiler is used to develop a parallel C++ code based on OpenMP. The code is executed on four Dual-Core AMD Opteron shared memory processors, to reduce the computational burden of the filtration task significantly. The results show that the parallel code for filtration has achieved a speed up factor of 46.66 as against the equivalent serial MATLAB code. In addition, a parallel MATLAB code has been developed to perform 3D Fourier reconstruction. Speedup factors of 4.57 and 4.25 have been achieved during the reconstruction process and oximetry computation, for a data set with 23 x 23 x 23 gradient steps. The execution time has been computed for both the serial and parallel implementations using different dimensions of the data and presented for comparison. The reported system has been designed to be easily accessible even from low-cost personal computers through local internet (NIHnet). The experimental results demonstrate that the parallel computing provides a source of high computational power to obtain biophysical parameters from 3D EPR oximetric imaging, almost in real-time.

Quantitative ChIP-Seq Normalization Reveals Global Modulation of the Epigenome

Directory of Open Access Journals (Sweden)

David A. Orlando

2014-11-01

Full Text Available Epigenomic profiling by chromatin immunoprecipitation coupled with massively parallel DNA sequencing (ChIP-seq is a prevailing methodology used to investigate chromatin-based regulation in biological systems such as human disease, but the lack of an empirical methodology to enable normalization among experiments has limited the precision and usefulness of this technique. Here, we describe a method called ChIP with reference exogenous genome (ChIP-Rx that allows one to perform genome-wide quantitative comparisons of histone modification status across cell populations using defined quantities of a reference epigenome. ChIP-Rx enables the discovery and quantification of dynamic epigenomic profiles across mammalian cells that would otherwise remain hidden using traditional normalization methods. We demonstrate the utility of this method for measuring epigenomic changes following chemical perturbations and show how reference normalization of ChIP-seq experiments enables the discovery of disease-relevant changes in histone modification occupancy.

Magnetic resonance imaging of normal pituitary gland

International Nuclear Information System (INIS)

Yamanaka, Masami; Uozumi, Tohru; Sakoda, Katsuaki; Ohta, Masahiro; Kagawa, Yoshihiro; Kajima, Toshio.

1986-01-01

Magnetic resonance imaging (MRI) is a suitable procedure for diagnosing such midline-positioned lesions as pituitary adenomas. To differentiate them from microadenomas fifty-seven cases (9 - 74 years old, 29 men and 28 women), including 50 patients without any sellar or parasellar diseases and seven normal volunteers, were studied in order to clarify the MR findings of the shape, height, and signal intensity of the normal pituitary gland, especially at the median sagittal section. The height of a normal pituitary gland varied from 2 to 9 mm (mean: 5.7 mm); the upper surface of the gland was convex in 19.3 %, flat in 49.1 %, and concave in 31.6 %. The mean height of the gland in women in their twenties was 7.5 mm, and the upper convex shape appeared exclusively in women of the second to fourth decades. Nine intrasellar pituitary adenomas (PRL-secreting: 4, GH-secreting: 4, ACTH-secreting: 1), all verified by surgery, were diagnosed using a resistive MR system. The heights of the gland in these cases were from 7 to 15 mm (mean: 11.3 mm); the upper surface was convex in 7 cases. A localized bulging of the upper surface of the gland and a localized depression of the sellar floor were depicted on the coronal and sagittal sections in most cases. Although the GH- and ACTH-secreting adenoma cases showed homogeneous intrasellar contents, in all the PRL-secreting adenoma cases a low-signal-intensity area was detected in the IR images. The mean T1 values of the intrasellar content of the normal volunteers, the PRL-, GH-, and ACTH-secreting adenoma cases, were 367, 416, 355, and 411 ms respectively. However, in the PRL-secreting adenoma cases, the mean T1 value of the areas showing a low signal intensity on IR images was 455 ms; this was a significant prolongation in comparison with that of a normal pituitary gland. (J.P.N.)

Surface impedance and optimum surface resistance of a superconductor with an imperfect surface

Science.gov (United States)

Gurevich, Alex; Kubo, Takayuki

2017-11-01

We calculate a low-frequency surface impedance of a dirty, s -wave superconductor with an imperfect surface incorporating either a thin layer with a reduced pairing constant or a thin, proximity-coupled normal layer. Such structures model realistic surfaces of superconducting materials which can contain oxide layers, absorbed impurities, or nonstoichiometric composition. We solved the Usadel equations self-consistently and obtained spatial distributions of the order parameter and the quasiparticle density of states which then were used to calculate a low-frequency surface resistance Rs(T ) and the magnetic penetration depth λ (T ) as functions of temperature in the limit of local London electrodynamics. It is shown that the imperfect surface in a single-band s -wave superconductor results in a nonexponential temperature dependence of Z (T ) at T ≪Tc which can mimic the behavior of multiband or d -wave superconductors. The imperfect surface and the broadening of the gap peaks in the quasiparticle density of states N (ɛ ) in the bulk give rise to a weakly temperature-dependent residual surface resistance. We show that the surface resistance can be optimized and even reduced below its value for an ideal surface by engineering N (ɛ ) at the surface using pair-breaking mechanisms, particularly by incorporating a small density of magnetic impurities or by tuning the thickness and conductivity of the normal layer and its contact resistance. The results of this work address the limit of Rs in superconductors at T ≪Tc , and the ways of engineering the optimal density of states by surface nanostructuring and impurities to reduce losses in superconducting microresonators, thin-film strip lines, and radio-frequency cavities for particle accelerators.

Fungal invasion of normally non-phagocytic host cells.

Directory of Open Access Journals (Sweden)

Scott G Filler

2006-12-01

Full Text Available Many fungi that cause invasive disease invade host epithelial cells during mucosal and respiratory infection, and subsequently invade endothelial cells during hematogenous infection. Most fungi invade these normally non-phagocytic host cells by inducing their own uptake. Candida albicans hyphae interact with endothelial cells in vitro by binding to N-cadherin on the endothelial cell surface. This binding induces rearrangement of endothelial cell microfilaments, which results in the endocytosis of the organism. The capsule of Cryptococcus neoformans is composed of glucuronoxylomannan, which binds specifically to brain endothelial cells, and appears to mediate both adherence and induction of endocytosis. The mechanisms by which other fungal pathogens induce their own uptake are largely unknown. Some angioinvasive fungi, such as Aspergillus species and the Zygomycetes, invade endothelial cells from the abluminal surface during the initiation of invasive disease, and subsequently invade the luminal surface of endothelial cells during hematogenous dissemination. Invasion of normally non-phagocytic host cells has different consequences, depending on the type of invading fungus. Aspergillus fumigatus blocks apoptosis of pulmonary epithelial cells, whereas Paracoccidioides brasiliensis induces apoptosis of epithelial cells. This review summarizes the mechanisms by which diverse fungal pathogens invade normally non-phagocytic host cells and discusses gaps in our knowledge that provide opportunities for future research.

Influence of skin surface roughness degree on energy characteristics of light scattered by a biological tissue

Science.gov (United States)

Barun, V. V.; Ivanov, A. P.

2017-05-01

We present the results of modelling of photometric characteristics of light in soft tissues illuminated by a parallel beam along the normal to the surface, obtained with allowance for the skin roughness parameters and the angular structure of radiation approaching the surface from within the tissue. The depth structure of the fluence rate and the spectra of the diffuse reflection of light by the tissue in the interval of wavelengths 300 - 1000 nm are considered. We discuss the influence of the tilt angle variance of rough surface microelements and light refraction on the studied characteristics. It is shown that these factors lead to the reduction of the radiation flux only in the near-surface tissue layer and practically do not affect the depth of light penetration into the tissue. On the other hand, the degree of the surface roughness and the conditions of its illumination from within the tissue essentially affect the coefficient of diffuse reflection of light and lead to its considerable growth compared to the cases of a smooth interface and completely diffuse illumination, often considered to simplify the theoretical problem solution. The role of the roughness of skin surface is assessed in application to the solution of different direct and inverse problems of biomedical optics.

Unified Singularity Modeling and Reconfiguration of 3rTPS Metamorphic Parallel Mechanisms with Parallel Constraint Screws

Directory of Open Access Journals (Sweden)

Yufeng Zhuang

2015-01-01

Full Text Available This paper presents a unified singularity modeling and reconfiguration analysis of variable topologies of a class of metamorphic parallel mechanisms with parallel constraint screws. The new parallel mechanisms consist of three reconfigurable rTPS limbs that have two working phases stemming from the reconfigurable Hooke (rT joint. While one phase has full mobility, the other supplies a constraint force to the platform. Based on these, the platform constraint screw systems show that the new metamorphic parallel mechanisms have four topologies by altering the limb phases with mobility change among 1R2T (one rotation with two translations, 2R2T, and 3R2T and mobility 6. Geometric conditions of the mechanism design are investigated with some special topologies illustrated considering the limb arrangement. Following this and the actuation scheme analysis, a unified Jacobian matrix is formed using screw theory to include the change between geometric constraints and actuation constraints in the topology reconfiguration. Various singular configurations are identified by analyzing screw dependency in the Jacobian matrix. The work in this paper provides basis for singularity-free workspace analysis and optimal design of the class of metamorphic parallel mechanisms with parallel constraint screws which shows simple geometric constraints with potential simple kinematics and dynamics properties.

High Compressive Stresses Near the Surface of the Sierra Nevada, California

Science.gov (United States)

Martel, S. J.; Logan, J. M.; Stock, G. M.

2012-12-01

Observations and stress measurements in granitic rocks of the Sierra Nevada, California reveal strong compressive stresses parallel to the surface of the range at shallow depths. New overcoring measurements show high compressive stresses at three locations along an east-west transect through Yosemite National Park. At the westernmost site (west end of Tenaya Lake), the mean compressive stress is 1.9. At the middle site (north shore of Tenaya Lake) the mean compressive stress is 6.8 MPa. At the easternmost site (south side of Lembert Dome) the mean compressive stress is 3.0 MPa. The trend of the most compressive stress at these sites is within ~30° of the strike of the local topographic surface. Previously published hydraulic fracturing measurements by others elsewhere in the Sierra Nevada indicate surface-parallel compressive stresses of several MPa within several tens of meters of the surface, with the stress magnitudes generally diminishing to the west. Both the new and the previously published compressive stress magnitudes are consistent with the presence of sheeting joints (i.e., "exfoliation joints") in the Sierra Nevada, which require lateral compressive stresses of several MPa to form. These fractures are widespread: they are distributed in granitic rocks from the north end of the range to its southern tip and across the width of the range. Uplift along the normal faults of the eastern escarpment, recently measured by others at ~1-2 mm/yr, probably contributes to these stresses substantially. Geodetic surveys reveal that normal faulting flexes a range concave upwards in response to fault slip, and this flexure is predicted by elastic dislocation models. The topographic relief of the eastern escarpment of the Sierra Nevada is 2-4 km, and since alluvial fill generally buries the bedrock east of the faults, the offset of granitic rocks is at least that much. Compressive stresses of several MPa are predicted by elastic dislocation models of the range front

Radiographic film: surface dose extrapolation techniques

International Nuclear Information System (INIS)

Cheung, T.; Yu, P.K.N.; Butson, M.J.; Cancer Services, Wollongong, NSW; Currie, M.

2004-01-01

Full text: Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate 2 dimensional map of surface dose if required. Results have shown that surface % dose can be estimated within ±3% of parallel plate ionisation chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10cm, 20cmand 30cm square fields was estimated to be 15% ± 2%, 29% ± 3% and 38% ± 3% at the central axis and relatively uniform across the treatment field. Corresponding parallel plate ionisation chamber measurement are 16%, 27% and 37% respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine

Infrared studies of gold nanochains on the Si(557) stepped surface

Energy Technology Data Exchange (ETDEWEB)

Vu Hoang, Chung; Klevenz, Markus; Lovrincic, Robert; Skibbe, Olaf; Neubrech, Frank; Pucci, Annemarie [Kirchhoff-Institut fuer Physik der Universitaet Heidelberg (Germany)

2008-07-01

Gold nanochains on Si(557) will be fabricated under ultra high vacuum conditions. The terraces of the stepped surface serve as one-dimensional diffusion channels, which leads to the formation of parallel monoatomic chains. Due to the appearance of metallic chains an anisotropic change of the conductivity of the substrate surface can be expected. The chain growth process and conductivity dependence versus gold composition will be investigated in-situ by using transmittance infrared spectroscopy (IRS) with light polarized parallel and perpendicular to the chains, respectively. IRS is a well-established method to observe conductivity changes on surfaces. The temperature dependent behaviour of gold chains will be studied as well.

Studies on Impingement Effects of Low Density Jets on Surfaces — Determination of Shear Stress and Normal Pressure

Science.gov (United States)

Sathian, Sarith. P.; Kurian, Job

2005-05-01

This paper presents the results of the Laser Reflection Method (LRM) for the determination of shear stress due to impingement of low-density free jets on flat plate. For thin oil film moving under the action of aerodynamic boundary layer the shear stress at the air-oil interface is equal to the shear stress between the surface and air. A direct and dynamic measurement of the oil film slope is measured using a position sensing detector (PSD). The thinning rate of oil film is directly measured which is the major advantage of the LRM over LISF method. From the oil film slope history, direct calculation of the shear stress is done using a three-point formula. For the full range of experiment conditions Knudsen numbers varied till the continuum limit of the transition regime. The shear stress values for low-density flows in the transition regime are thus obtained using LRM and the measured values of shear show fair agreement with those obtained by other methods. Results of the normal pressure measurements on a flat plate in low-density jets by using thermistors as pressure sensors are also presented in the paper. The normal pressure profiles obtained show the characteristic features of Newtonian impact theory for hypersonic flows.

Low-density lipoprotein concentration in the normal left coronary artery tree

Directory of Open Access Journals (Sweden)

Louridas George E

2008-10-01

Full Text Available Abstract Background The blood flow and transportation of molecules in the cardiovascular system plays a crucial role in the genesis and progression of atherosclerosis. This computational study elucidates the Low Density Lipoprotein (LDL site concentration in the entire normal human 3D tree of the LCA. Methods A 3D geometry model of the normal human LCA tree is constructed. Angiographic data used for geometry construction correspond to end-diastole. The resulted model includes the LMCA, LAD, LCxA and their main branches. The numerical simulation couples the flow equations with the transport equation applying realistic boundary conditions at the wall. Results High concentration of LDL values appears at bifurcation opposite to the flow dividers in the proximal regions of the Left Coronary Artery (LCA tree, where atherosclerosis frequently occurs. The area-averaged normalized luminal surface LDL concentrations over the entire LCA tree are, 1.0348, 1.054 and 1.23, for the low, median and high water infiltration velocities, respectively. For the high, median and low molecular diffusivities, the peak values of the normalized LDL luminal surface concentration at the LMCA bifurcation reach 1.065, 1.080 and 1.205, respectively. LCA tree walls are exposed to a cholesterolemic environment although the applied mass and flow conditions refer to normal human geometry and normal mass-flow conditions. Conclusion The relationship between WSS and luminal surface concentration of LDL indicates that LDL is elevated at locations where WSS is low. Concave sides of the LCA tree exhibit higher concentration of LDL than the convex sides. Decreased molecular diffusivity increases the LDL concentration. Increased water infiltration velocity increases the LDL concentration. The regional area of high luminal surface concentration is increased with increasing water infiltration velocity. Regions of high LDL luminal surface concentration do not necessarily co-locate to the

Continuous development of schemes for parallel computing of the electrostatics in biological systems: implementation in DelPhi.

Science.gov (United States)

Li, Chuan; Petukh, Marharyta; Li, Lin; Alexov, Emil

2013-08-15

Due to the enormous importance of electrostatics in molecular biology, calculating the electrostatic potential and corresponding energies has become a standard computational approach for the study of biomolecules and nano-objects immersed in water and salt phase or other media. However, the electrostatics of large macromolecules and macromolecular complexes, including nano-objects, may not be obtainable via explicit methods and even the standard continuum electrostatics methods may not be applicable due to high computational time and memory requirements. Here, we report further development of the parallelization scheme reported in our previous work (Li, et al., J. Comput. Chem. 2012, 33, 1960) to include parallelization of the molecular surface and energy calculations components of the algorithm. The parallelization scheme utilizes different approaches such as space domain parallelization, algorithmic parallelization, multithreading, and task scheduling, depending on the quantity being calculated. This allows for efficient use of the computing resources of the corresponding computer cluster. The parallelization scheme is implemented in the popular software DelPhi and results in speedup of several folds. As a demonstration of the efficiency and capability of this methodology, the electrostatic potential, and electric field distributions are calculated for the bovine mitochondrial supercomplex illustrating their complex topology, which cannot be obtained by modeling the supercomplex components alone. Copyright © 2013 Wiley Periodicals, Inc.

Fast ℓ1-SPIRiT Compressed Sensing Parallel Imaging MRI: Scalable Parallel Implementation and Clinically Feasible Runtime

Science.gov (United States)

Murphy, Mark; Alley, Marcus; Demmel, James; Keutzer, Kurt; Vasanawala, Shreyas; Lustig, Michael

2012-01-01

We present ℓ1-SPIRiT, a simple algorithm for auto calibrating parallel imaging (acPI) and compressed sensing (CS) that permits an efficient implementation with clinically-feasible runtimes. We propose a CS objective function that minimizes cross-channel joint sparsity in the Wavelet domain. Our reconstruction minimizes this objective via iterative soft-thresholding, and integrates naturally with iterative Self-Consistent Parallel Imaging (SPIRiT). Like many iterative MRI reconstructions, ℓ1-SPIRiT’s image quality comes at a high computational cost. Excessively long runtimes are a barrier to the clinical use of any reconstruction approach, and thus we discuss our approach to efficiently parallelizing ℓ1-SPIRiT and to achieving clinically-feasible runtimes. We present parallelizations of ℓ1-SPIRiT for both multi-GPU systems and multi-core CPUs, and discuss the software optimization and parallelization decisions made in our implementation. The performance of these alternatives depends on the processor architecture, the size of the image matrix, and the number of parallel imaging channels. Fundamentally, achieving fast runtime requires the correct trade-off between cache usage and parallelization overheads. We demonstrate image quality via a case from our clinical experimentation, using a custom 3DFT Spoiled Gradient Echo (SPGR) sequence with up to 8× acceleration via poisson-disc undersampling in the two phase-encoded directions. PMID:22345529

Parallel and non-parallel laminar mixed convection flow in an inclined tube: The effect of the boundary conditions

International Nuclear Information System (INIS)

Barletta, A.

2008-01-01

The necessary condition for the onset of parallel flow in the fully developed region of an inclined duct is applied to the case of a circular tube. Parallel flow in inclined ducts is an uncommon regime, since in most cases buoyancy tends to produce the onset of secondary flow. The present study shows how proper thermal boundary conditions may preserve parallel flow regime. Mixed convection flow is studied for a special non-axisymmetric thermal boundary condition that, with a proper choice of a switch parameter, may be compatible with parallel flow. More precisely, a circumferentially variable heat flux distribution is prescribed on the tube wall, expressed as a sinusoidal function of the azimuthal coordinate θ with period 2π. A π/2 rotation in the position of the maximum heat flux, achieved by setting the switch parameter, may allow or not the existence of parallel flow. Two cases are considered corresponding to parallel and non-parallel flow. In the first case, the governing balance equations allow a simple analytical solution. On the contrary, in the second case, the local balance equations are solved numerically by employing a finite element method

Parallel programming with Easy Java Simulations

Science.gov (United States)

Esquembre, F.; Christian, W.; Belloni, M.

2018-01-01

Nearly all of today's processors are multicore, and ideally programming and algorithm development utilizing the entire processor should be introduced early in the computational physics curriculum. Parallel programming is often not introduced because it requires a new programming environment and uses constructs that are unfamiliar to many teachers. We describe how we decrease the barrier to parallel programming by using a java-based programming environment to treat problems in the usual undergraduate curriculum. We use the easy java simulations programming and authoring tool to create the program's graphical user interface together with objects based on those developed by Kaminsky [Building Parallel Programs (Course Technology, Boston, 2010)] to handle common parallel programming tasks. Shared-memory parallel implementations of physics problems, such as time evolution of the Schrödinger equation, are available as source code and as ready-to-run programs from the AAPT-ComPADRE digital library.

The surface diffusion coefficient for an arbitrarily curved fluid-fluid interface. (I). General expression

Science.gov (United States)

M. C. Sagis, Leonard

2001-03-01

In this paper, we develop a theory for the calculation of the surface diffusion coefficient for an arbitrarily curved fluid-fluid interface. The theory is valid for systems in hydrodynamic equilibrium, with zero mass-averaged velocities in the bulk and interfacial regions. We restrict our attention to systems with isotropic bulk phases, and an interfacial region that is isotropic in the plane parallel to the dividing surface. The dividing surface is assumed to be a simple interface, without memory effects or yield stresses. We derive an expression for the surface diffusion coefficient in terms of two parameters of the interfacial region: the coefficient for plane-parallel diffusion D (AB)aa(ξ) , and the driving force d(B)I||(ξ) . This driving force is the parallel component of the driving force for diffusion in the interfacial region. We derive an expression for this driving force using the entropy balance.

Multicoil resonance-based parallel array for smart wireless power delivery.

Science.gov (United States)

Mirbozorgi, S A; Sawan, M; Gosselin, B

2013-01-01

This paper presents a novel resonance-based multicoil structure as a smart power surface to wirelessly power up apparatus like mobile, animal headstage, implanted devices, etc. The proposed powering system is based on a 4-coil resonance-based inductive link, the resonance coil of which is formed by an array of several paralleled coils as a smart power transmitter. The power transmitter employs simple circuit connections and includes only one power driver circuit per multicoil resonance-based array, which enables higher power transfer efficiency and power delivery to the load. The power transmitted by the driver circuit is proportional to the load seen by the individual coil in the array. Thus, the transmitted power scales with respect to the load of the electric/electronic system to power up, and does not divide equally over every parallel coils that form the array. Instead, only the loaded coils of the parallel array transmit significant part of total transmitted power to the receiver. Such adaptive behavior enables superior power, size and cost efficiency then other solutions since it does not need to use complex detection circuitry to find the location of the load. The performance of the proposed structure is verified by measurement results. Natural load detection and covering 4 times bigger area than conventional topologies with a power transfer efficiency of 55% are the novelties of presented paper.

Parallelism and Scalability in an Image Processing Application

DEFF Research Database (Denmark)

Rasmussen, Morten Sleth; Stuart, Matthias Bo; Karlsson, Sven

2008-01-01

parallel programs. This paper investigates parallelism and scalability of an embedded image processing application. The major challenges faced when parallelizing the application were to extract enough parallelism from the application and to reduce load imbalance. The application has limited immediately......The recent trends in processor architecture show that parallel processing is moving into new areas of computing in the form of many-core desktop processors and multi-processor system-on-chip. This means that parallel processing is required in application areas that traditionally have not used...

Parallelism and Scalability in an Image Processing Application

DEFF Research Database (Denmark)

Rasmussen, Morten Sleth; Stuart, Matthias Bo; Karlsson, Sven

2009-01-01

parallel programs. This paper investigates parallelism and scalability of an embedded image processing application. The major challenges faced when parallelizing the application were to extract enough parallelism from the application and to reduce load imbalance. The application has limited immediately......The recent trends in processor architecture show that parallel processing is moving into new areas of computing in the form of many-core desktop processors and multi-processor system-on-chips. This means that parallel processing is required in application areas that traditionally have not used...

Parallel auto-correlative statistics with VTK.

Energy Technology Data Exchange (ETDEWEB)

Pebay, Philippe Pierre; Bennett, Janine Camille

2013-08-01

This report summarizes existing statistical engines in VTK and presents both the serial and parallel auto-correlative statistics engines. It is a sequel to [PT08, BPRT09b, PT09, BPT09, PT10] which studied the parallel descriptive, correlative, multi-correlative, principal component analysis, contingency, k-means, and order statistics engines. The ease of use of the new parallel auto-correlative statistics engine is illustrated by the means of C++ code snippets and algorithm verification is provided. This report justifies the design of the statistics engines with parallel scalability in mind, and provides scalability and speed-up analysis results for the autocorrelative statistics engine.

Conformal pure radiation with parallel rays

International Nuclear Information System (INIS)

Leistner, Thomas; Paweł Nurowski

2012-01-01

We define pure radiation metrics with parallel rays to be n-dimensional pseudo-Riemannian metrics that admit a parallel null line bundle K and whose Ricci tensor vanishes on vectors that are orthogonal to K. We give necessary conditions in terms of the Weyl, Cotton and Bach tensors for a pseudo-Riemannian metric to be conformal to a pure radiation metric with parallel rays. Then, we derive conditions in terms of the tractor calculus that are equivalent to the existence of a pure radiation metric with parallel rays in a conformal class. We also give analogous results for n-dimensional pseudo-Riemannian pp-waves. (paper)

Surface Reconstruction from Parallel Curves with Application to Parietal Bone Fracture Reconstruction.

Directory of Open Access Journals (Sweden)

Abdul Majeed

Full Text Available Maxillofacial trauma are common, secondary to road traffic accident, sports injury, falls and require sophisticated radiological imaging to precisely diagnose. A direct surgical reconstruction is complex and require clinical expertise. Bio-modelling helps in reconstructing surface model from 2D contours. In this manuscript we have constructed the 3D surface using 2D Computerized Tomography (CT scan contours. The fracture part of the cranial vault are reconstructed using GC1 rational cubic Ball curve with three free parameters, later the 2D contours are flipped into 3D with equidistant z component. The constructed surface is represented by contours blending interpolant. At the end of this manuscript a case report of parietal bone fracture is also illustrated by employing this method with a Graphical User Interface (GUI illustration.

The influence of collisional and anomalous radial diffusion on parallel ion transport in edge plasmas

International Nuclear Information System (INIS)

Helander, P.; Hazeltine, R.D.; Catto, P.J.

1996-01-01

The orderings in the kinetic equations commonly used to study the plasma core of a tokamak do not allow a balance between parallel ion streaming and radial diffusion, and are, therefore, inappropriate in the plasma edge. Different orderings are required in the edge region where radial transport across the steep gradients associated with the scrape-off layer is large enough to balance the rapid parallel flow caused by conditions close to collecting surfaces (such as the Bohm sheath condition). In the present work, we derive and solve novel kinetic equations, allowing for such a balance, and construct distinctive transport laws for impure, collisional, edge plasmas in which the perpendicular transport is (i) due to Coulomb collisions of ions with heavy impurities, or (ii) governed by anomalous diffusion driven by electrostatic turbulence. In both the collisional and anomalous radial transport cases, we find that one single diffusion coefficient determines the radial transport of particles, momentum and heat. The parallel transport laws and parallel thermal force in the scrape-off layer assume an unconventional form, in which the relative ion-impurity flow is driven by a combination of the conventional parallel gradients, and new (i) collisional or (ii) anomalous terms involving products of radial derivatives of the temperature and density with the radial shear of the parallel velocity. Thus, in the presence of anomalous radial diffusion, the parallel ion transport cannot be entirely classical, as usually assumed in numerical edge computations. The underlying physical reason is the appearance of a novel type of parallel thermal force resulting from the combined action of anomalous diffusion and radial temperature and velocity gradients. In highly sheared flows the new terms can modify impurity penetration into the core plasma

Parallel plasma fluid turbulence calculations

International Nuclear Information System (INIS)

Leboeuf, J.N.; Carreras, B.A.; Charlton, L.A.; Drake, J.B.; Lynch, V.E.; Newman, D.E.; Sidikman, K.L.; Spong, D.A.

1994-01-01

The study of plasma turbulence and transport is a complex problem of critical importance for fusion-relevant plasmas. To this day, the fluid treatment of plasma dynamics is the best approach to realistic physics at the high resolution required for certain experimentally relevant calculations. Core and edge turbulence in a magnetic fusion device have been modeled using state-of-the-art, nonlinear, three-dimensional, initial-value fluid and gyrofluid codes. Parallel implementation of these models on diverse platforms--vector parallel (National Energy Research Supercomputer Center's CRAY Y-MP C90), massively parallel (Intel Paragon XP/S 35), and serial parallel (clusters of high-performance workstations using the Parallel Virtual Machine protocol)--offers a variety of paths to high resolution and significant improvements in real-time efficiency, each with its own advantages. The largest and most efficient calculations have been performed at the 200 Mword memory limit on the C90 in dedicated mode, where an overlap of 12 to 13 out of a maximum of 16 processors has been achieved with a gyrofluid model of core fluctuations. The richness of the physics captured by these calculations is commensurate with the increased resolution and efficiency and is limited only by the ingenuity brought to the analysis of the massive amounts of data generated

A task parallel implementation of fast multipole methods

KAUST Repository

Taura, Kenjiro

2012-11-01

This paper describes a task parallel implementation of ExaFMM, an open source implementation of fast multipole methods (FMM), using a lightweight task parallel library MassiveThreads. Although there have been many attempts on parallelizing FMM, experiences have almost exclusively been limited to formulation based on flat homogeneous parallel loops. FMM in fact contains operations that cannot be readily expressed in such conventional but restrictive models. We show that task parallelism, or parallel recursions in particular, allows us to parallelize all operations of FMM naturally and scalably. Moreover it allows us to parallelize a \\'\\'mutual interaction\\'\\' for force/potential evaluation, which is roughly twice as efficient as a more conventional, unidirectional force/potential evaluation. The net result is an open source FMM that is clearly among the fastest single node implementations, including those on GPUs; with a million particles on a 32 cores Sandy Bridge 2.20GHz node, it completes a single time step including tree construction and force/potential evaluation in 65 milliseconds. The study clearly showcases both programmability and performance benefits of flexible parallel constructs over more monolithic parallel loops. © 2012 IEEE.

Plasmas fluxes to surfaces for an oblique magnetic field

International Nuclear Information System (INIS)

Pitcher, C.S.; Stangeby, P.C.; Elder, J.D.; Bell, M.G.; Kilpatrick, S.J.; Manos, D.M.; Medley, S.S.; Owens, D.K.; Ramsey, A.T.; Ulrickson, M.

1992-07-01

The poloidal and toroidal spatial distributions of D α , He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface. The distributions are found not to agree with a model (the ''Cosine'' model) which determines the incident flux density using only the parallel fluxes in the scrape-off layer and the projected area of the surface perpendicular to the field lines. In particular, the Cosine model is not able to explain the significant fluxes observed at locations on the surface which are oblique to the magnetic field. It is further shown that these fluxes cannot be explained by the finite Larmor radius of impinging ions. Finally, it is demonstrated, with the use of Monte Carlo codes, that the distributions can be explained by including both parallel and cross-field transport onto the limiter surface

Tuning of tool dynamics for increased stability of parallel (simultaneous) turning processes

Science.gov (United States)

Ozturk, E.; Comak, A.; Budak, E.

2016-01-01

Parallel (simultaneous) turning operations make use of more than one cutting tool acting on a common workpiece offering potential for higher productivity. However, dynamic interaction between the tools and workpiece and resulting chatter vibrations may create quality problems on machined surfaces. In order to determine chatter free cutting process parameters, stability models can be employed. In this paper, stability of parallel turning processes is formulated in frequency and time domain for two different parallel turning cases. Predictions of frequency and time domain methods demonstrated reasonable agreement with each other. In addition, the predicted stability limits are also verified experimentally. Simulation and experimental results show multi regional stability diagrams which can be used to select most favorable set of process parameters for higher stable material removal rates. In addition to parameter selection, developed models can be used to determine the best natural frequency ratio of tools resulting in the highest stable depth of cuts. It is concluded that the most stable operations are obtained when natural frequency of the tools are slightly off each other and worst stability occurs when the natural frequency of the tools are exactly the same.

Second derivative parallel block backward differentiation type ...

African Journals Online (AJOL)

Second derivative parallel block backward differentiation type formulas for Stiff ODEs. ... Log in or Register to get access to full text downloads. ... and the methods are inherently parallel and can be distributed over parallel processors. They are ...

Constructing Fluorine-Free and Cost-Effective Superhydrophobic Surface with Normal-Alcohol-Modified Hydrophobic SiO2 Nanoparticles.

Science.gov (United States)

Ye, Hui; Zhu, Liqun; Li, Weiping; Liu, Huicong; Chen, Haining

2017-01-11

Superhydrophobic coatings have drawn much attention in recent years for their wide potential applications. However, a simple, cost-effective, and environmentally friendly approach is still lacked. Herein, a promising approach using nonhazardous chemicals was proposed, in which multiple hydrophobic functionalized silica nanoparticles (SiO 2 NPs) were first prepared as core component, through the efficient reaction between amino group containing SiO 2 NPs and the isocyanate containing hydrophobic surface modifiers synthesized by normal alcohols, followed by simply spraying onto various substrates for superhydrophobic functionalization. Furthermore, to further improve the mechanical durability, an organic-inorganic composite superhydrophobic coating was fabricated by incorporating cross-linking agent (polyisocyanate) into the mixture of hydrophobic-functionalized SiO 2 NPs and hydroxyl acrylic resin. The hybrid coating with cross-linked network structures is very stable with excellent mechanical durability, self-cleaning property and corrosion resistance.

Parallelization of quantum molecular dynamics simulation code

International Nuclear Information System (INIS)

Kato, Kaori; Kunugi, Tomoaki; Shibahara, Masahiko; Kotake, Susumu

1998-02-01

A quantum molecular dynamics simulation code has been developed for the analysis of the thermalization of photon energies in the molecule or materials in Kansai Research Establishment. The simulation code is parallelized for both Scalar massively parallel computer (Intel Paragon XP/S75) and Vector parallel computer (Fujitsu VPP300/12). Scalable speed-up has been obtained with a distribution to processor units by division of particle group in both parallel computers. As a result of distribution to processor units not only by particle group but also by the particles calculation that is constructed with fine calculations, highly parallelization performance is achieved in Intel Paragon XP/S75. (author)

A Parallel Approach to Fractal Image Compression

OpenAIRE

Lubomir Dedera

2004-01-01

The paper deals with a parallel approach to coding and decoding algorithms in fractal image compressionand presents experimental results comparing sequential and parallel algorithms from the point of view of achieved bothcoding and decoding time and effectiveness of parallelization.

Distributed approximation of Pareto surfaces in multicriteria radiation therapy treatment planning

International Nuclear Information System (INIS)

Bokrantz, Rasmus

2013-01-01

We consider multicriteria radiation therapy treatment planning by navigation over the Pareto surface, implemented by interpolation between discrete treatment plans. Current state of the art for calculation of a discrete representation of the Pareto surface is to sandwich this set between inner and outer approximations that are updated one point at a time. In this paper, we generalize this sequential method to an algorithm that permits parallelization. The principle of the generalization is to apply the sequential method to an approximation of an inexpensive model of the Pareto surface. The information gathered from the model is sub-sequently used for the calculation of points from the exact Pareto surface, which are processed in parallel. The model is constructed according to the current inner and outer approximations, and given a shape that is difficult to approximate, in order to avoid that parts of the Pareto surface are incorrectly disregarded. Approximations of comparable quality to those generated by the sequential method are demonstrated when the degree of parallelization is up to twice the number of dimensions of the objective space. For practical applications, the number of dimensions is typically at least five, so that a speed-up of one order of magnitude is obtained. (paper)

Distributed approximation of Pareto surfaces in multicriteria radiation therapy treatment planning.

Science.gov (United States)

Bokrantz, Rasmus

2013-06-07

We consider multicriteria radiation therapy treatment planning by navigation over the Pareto surface, implemented by interpolation between discrete treatment plans. Current state of the art for calculation of a discrete representation of the Pareto surface is to sandwich this set between inner and outer approximations that are updated one point at a time. In this paper, we generalize this sequential method to an algorithm that permits parallelization. The principle of the generalization is to apply the sequential method to an approximation of an inexpensive model of the Pareto surface. The information gathered from the model is sub-sequently used for the calculation of points from the exact Pareto surface, which are processed in parallel. The model is constructed according to the current inner and outer approximations, and given a shape that is difficult to approximate, in order to avoid that parts of the Pareto surface are incorrectly disregarded. Approximations of comparable quality to those generated by the sequential method are demonstrated when the degree of parallelization is up to twice the number of dimensions of the objective space. For practical applications, the number of dimensions is typically at least five, so that a speed-up of one order of magnitude is obtained.

Differences Between Distributed and Parallel Systems

Energy Technology Data Exchange (ETDEWEB)

Brightwell, R.; Maccabe, A.B.; Rissen, R.

1998-10-01

Distributed systems have been studied for twenty years and are now coming into wider use as fast networks and powerful workstations become more readily available. In many respects a massively parallel computer resembles a network of workstations and it is tempting to port a distributed operating system to such a machine. However, there are significant differences between these two environments and a parallel operating system is needed to get the best performance out of a massively parallel system. This report characterizes the differences between distributed systems, networks of workstations, and massively parallel systems and analyzes the impact of these differences on operating system design. In the second part of the report, we introduce Puma, an operating system specifically developed for massively parallel systems. We describe Puma portals, the basic building blocks for message passing paradigms implemented on top of Puma, and show how the differences observed in the first part of the report have influenced the design and implementation of Puma.

Parallel processing from applications to systems

CERN Document Server

Moldovan, Dan I

1993-01-01

This text provides one of the broadest presentations of parallelprocessing available, including the structure of parallelprocessors and parallel algorithms. The emphasis is on mappingalgorithms to highly parallel computers, with extensive coverage ofarray and multiprocessor architectures. Early chapters provideinsightful coverage on the analysis of parallel algorithms andprogram transformations, effectively integrating a variety ofmaterial previously scattered throughout the literature. Theory andpractice are well balanced across diverse topics in this concisepresentation. For exceptional cla

A survey of parallel multigrid algorithms

Science.gov (United States)

Chan, Tony F.; Tuminaro, Ray S.

1987-01-01

A typical multigrid algorithm applied to well-behaved linear-elliptic partial-differential equations (PDEs) is described. Criteria for designing and evaluating parallel algorithms are presented. Before evaluating the performance of some parallel multigrid algorithms, consideration is given to some theoretical complexity results for solving PDEs in parallel and for executing the multigrid algorithm. The effect of mapping and load imbalance on the partial efficiency of the algorithm is studied.

Hydrodynamic attraction of swimming microorganisms by surfaces

OpenAIRE

Berke, Allison P.; Turner, Linda; Berg, Howard C.; Lauga, Eric

2008-01-01

Cells swimming in confined environments are attracted by surfaces. We measure the steady-state distribution of smooth-swimming bacteria (Escherichia coli) between two glass plates. In agreement with earlier studies, we find a strong increase of the cell concentration at the boundaries. We demonstrate theoretically that hydrodynamic interactions of the swimming cells with solid surfaces lead to their re-orientation in the direction parallel to the surfaces, as well as their attraction by the c...

Parallel computing by Monte Carlo codes MVP/GMVP

International Nuclear Information System (INIS)

Nagaya, Yasunobu; Nakagawa, Masayuki; Mori, Takamasa

2001-01-01

General-purpose Monte Carlo codes MVP/GMVP are well-vectorized and thus enable us to perform high-speed Monte Carlo calculations. In order to achieve more speedups, we parallelized the codes on the different types of parallel computing platforms or by using a standard parallelization library MPI. The platforms used for benchmark calculations are a distributed-memory vector-parallel computer Fujitsu VPP500, a distributed-memory massively parallel computer Intel paragon and a distributed-memory scalar-parallel computer Hitachi SR2201, IBM SP2. As mentioned generally, linear speedup could be obtained for large-scale problems but parallelization efficiency decreased as the batch size per a processing element(PE) was smaller. It was also found that the statistical uncertainty for assembly powers was less than 0.1% by the PWR full-core calculation with more than 10 million histories and it took about 1.5 hours by massively parallel computing. (author)

The parallel processing of EGS4 code on distributed memory scalar parallel computer:Intel Paragon XP/S15-256

Energy Technology Data Exchange (ETDEWEB)

Takemiya, Hiroshi; Ohta, Hirofumi; Honma, Ichirou

1996-03-01

The parallelization of Electro-Magnetic Cascade Monte Carlo Simulation Code, EGS4 on distributed memory scalar parallel computer: Intel Paragon XP/S15-256 is described. EGS4 has the feature that calculation time for one incident particle is quite different from each other because of the dynamic generation of secondary particles and different behavior of each particle. Granularity for parallel processing, parallel programming model and the algorithm of parallel random number generation are discussed and two kinds of method, each of which allocates particles dynamically or statically, are used for the purpose of realizing high speed parallel processing of this code. Among four problems chosen for performance evaluation, the speedup factors for three problems have been attained to nearly 100 times with 128 processor. It has been found that when both the calculation time for each incident particles and its dispersion are large, it is preferable to use dynamic particle allocation method which can average the load for each processor. And it has also been found that when they are small, it is preferable to use static particle allocation method which reduces the communication overhead. Moreover, it is pointed out that to get the result accurately, it is necessary to use double precision variables in EGS4 code. Finally, the workflow of program parallelization is analyzed and tools for program parallelization through the experience of the EGS4 parallelization are discussed. (author).

Towards a streaming model for nested data parallelism

DEFF Research Database (Denmark)

Madsen, Frederik Meisner; Filinski, Andrzej

2013-01-01

The language-integrated cost semantics for nested data parallelism pioneered by NESL provides an intuitive, high-level model for predicting performance and scalability of parallel algorithms with reasonable accuracy. However, this predictability, obtained through a uniform, parallelism-flattening......The language-integrated cost semantics for nested data parallelism pioneered by NESL provides an intuitive, high-level model for predicting performance and scalability of parallel algorithms with reasonable accuracy. However, this predictability, obtained through a uniform, parallelism......-processable in a streaming fashion. This semantics is directly compatible with previously proposed piecewise execution models for nested data parallelism, but allows the expected space usage to be reasoned about directly at the source-language level. The language definition and implementation are still very much work...

Massively Parallel Computing: A Sandia Perspective